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--- NEW FILE appe-Security-Enhanced_Linux-Revision_History.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Appendix A. Revision History</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html" title="8.2. Other Resources"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html"><stro ng>Prev</strong></a></li><li class="next"/></ul><div xml:lang="en-US" class="appendix" title="Appendix A. Revision History"><div class="titlepage"><div><div><h1 id="appe-Security-Enhanced_Linux-Revision_History" class="title">Revision History</h1></div></div></div><div class="para"> <div class="revhistory"><table border="0" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="3"><b>Revision History</b></th></tr><tr><td align="left">Revision 1.4</td><td align="left">Mon Aug 31 2009</td><td align="left"><span class="author"><span class="firstname">Scott</span> <span class="surname">Radvan</span></span></td></tr><tr><td align="left" colspan="3"> <table border="0" summary="Simple list" class="simplelist"><tr><td>Update and verification for Fedora 12</td></tr></table> </td></tr><tr><td align="left">Revision 1.3</td><td align="left">Tue May 12 2009</td><td align="left"><span class="author"><span class="firstname">Scott</span> <span class="surname">Radvan</span></span></td></tr><tr><td align="left" colspan="3"> <table border="0" summary="Simple list" class="simplelist"><tr><td>Update and verification for Fedora 11</td></tr></table> </td></tr><tr><td align="left">Revision 1.2</td><td align="left">Mon Jan 19 2009</td><td align="left"><span class="author"><span class="firstname">Murray</span> <span class="surname">McAllister</span></span></td></tr><tr><td align="left" colspan="3"> <table border="0" summary="Simple list" class="simplelist"><tr><td>Updating hyperlinks to NSA websites</td></tr></table> </td></tr><tr><td align="left">Revision 1.1</td><td align="left">Sat Dec 6 2008</td><td align="left"><span class="author"><span class="firstname">Murray</span> <span class="surname">McAllister</span></span></td></tr><tr><td align="left" colspan="3"> <table border="0" summary="Simple list" class="simplelist"><tr><td>Resolving <a href="https://bugzilla.redhat.com/show_bug.cgi?id=472986">Red Hat Bugzilla #472986, "httpd does not write to /etc/httpd/logs/"</a></td></tr><tr><td>Added new section, "6.6. Booleans for Users Executing Applications"</td></tr><tr><td>Minor text revisions</td></tr></table> </td></tr><tr><td align="left">Revision 1.0</td><td align="left">Tue Nov 25 2008</td><td align="left"><span class="author"><span class="firstname">Murray</span> <span class="surname">McAllister</span></span></td></tr><tr><td align="left" colspan="3"> <table border="0" summary="Simple list" class="simplelist"><tr><td>Initial content release on <a href="http://docs.fedoraproject.org/">http://docs.fedoraproject.org/</a></td></tr></table> </td></tr></table></div> </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html"><strong>Prev</strong>8.2. Other Resources</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Confining_Users.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 6. Confining Users</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html" title="5.10.5. Archiving Files with star"/><link rel="next" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html" title="6.2. Confining New Linux Users: useradd"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/ima ge_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 6. Confining Users"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Confining_Users">Chapter 6. Confining Users</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Confining_Users.html#sect-Security-Enhanced_Linux-Confining_Users-Linux_and_SELinux_User_Mappings">6.1. Linux and SELinux User Mappings</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html">6.2. Confining N ew Linux Users: useradd</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html">6.3. Confining Existing Linux Users: semanage login</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html">6.4. Changing the Default Mapping</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html">6.5. xguest: Kiosk Mode</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html">6.6. Booleans for Users Executing Applications</a></span></dt></dl></div><div class="para"> A number of confined SELinux users are available in Fedora 12. Each Linux user is mapped to an SELinux user via SELinux policy, allowing Linux users to inherit the restrictions placed on SELinux users, for example (depending on the user), not being able to: run the X Window System; use networking; run setuid applications (unless SELinux policy permits it); or run the <code class="command">su</code> and <code class="command">sudo</code> commands. This helps protect the system from the user. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html" title="4.3. Confined and Unconfined Users">Section 4.3, “Confined and Unconfined Users”</a> for further information about confined users. </div><div class="section" title="6.1. Linux and SELinux User Mappings"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-Linux_and_SELinux_User_Mappings">6.1. Linux and SELinux User Mappings</h2></div></div></div><div class="para"> As the Linux root user, run the <code class="command">semanage login -l</code> command to view the mapping between Linux users and SELinux users: </div><pre class="screen"># /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre><div class="para"> In Fedora 12, Linux users are mapped to the SELinux <code class="computeroutput">__default__</code> login by default (which is in turn mapped to the SELinux <code class="computeroutput">unconfined_u</code> user). When a Linux user is created with the <code class="command">useradd</code> command, if no options are specified, they are mapped to the SELinux <code class="computeroutput">unconfined_u</code> user. The following defines the default-mapping: </div><pre class="screen"> __default__ unconfined_u s0-s0:c0.c1023 </pre></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html"><strong>Prev</strong>5.10.5. Archiving Files with star</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html"><strong>Next</strong>6.2. Confining New Linux Users: useradd</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Further_Information.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 8. Further Information</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html" title="7.3.8. Allowing Access: audit2allow"/><link rel="next" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html" title="8.2. Other Resources"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site "/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 8. Further Information"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Further_Information">Chapter 8. Further Information</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Further_Information.html#sect-Security-Enhanced_Linux-Further_Information-Contributors">8.1. Contributors</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html">8.2. Other Resources</a></span></dt></dl></div><div class="section" title="8.1. Contributors"><div class="ti tlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Further_Information-Contributors">8.1. Contributors</h2></div></div></div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> <a href="http://fedoraproject.org/wiki/GeertWarrink">Geert Warrink</a> (translation - Dutch) </div></li><li class="listitem"><div class="para"> <a href="http://fedoraproject.org/wiki/User:Beckerde">Domingo Becker</a> (translation - Spanish) </div></li><li class="listitem"><div class="para"> <a href="http://fedoraproject.org/wiki/User:Logan">Daniel Cabrera</a> (translation - Spanish) </div></li></ul></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html"><strong>Prev</strong>7.3.8. Allowing Access: audit2allow</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html"><strong>Next</strong>8.2. Other Resources</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Introduction.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 2. Introduction</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="chap-Security-Enhanced_Linux-Trademark_Information.html" title="Chapter 1. Trademark Information"/><link rel="next" href="sect-Security-Enhanced_Linux-Introduction-Examples.html" title="2.2. Examples"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous">< a accesskey="p" href="chap-Security-Enhanced_Linux-Trademark_Information.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-Examples.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 2. Introduction"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Introduction">Chapter 2. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Introduction.html#sect-Security-Enhanced_Linux-Introduction-Benefits_of_running_SELinux">2.1. Benefits of running SELinux</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Introduction-Examples.html">2.2. Examples</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html">2.3. SELinux Architecture</a></span></dt><dt><span class="section"><a href="sect-Se curity-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html">2.4. SELinux on Other Operating Systems</a></span></dt></dl></div><div class="para"> Security-Enhanced Linux (SELinux) is an implementation of a <em class="firstterm">mandatory access control</em> mechanism in the Linux kernel, checking for allowed operations after standard <em class="firstterm">discretionary access controls</em> are checked. It was created by the National Security Agency and can enforce rules on files and processes in a Linux system, and on their actions, based on defined policy. </div><div class="para"> When using SELinux, files, including directories and devices, are referred to as objects. Processes, such as a user running a command or the <span class="trademark">Mozilla</span>®<span class="trademark"> Firefox</span>® application, are referred to as subjects. Most operating systems use a Discretionary Access Control (DAC) system that controls how subjects interact with objects, and how subjects interact with each other. On operating systems using DAC, users control the permissions of files (objects) that they own. For example, on <span class="trademark">Linux</span>® operating systems, users could make their home directories world-readable, giving users and processes (subjects) access to potentially sensitive information, with no further protection over this unwanted action. </div><div class="para"> Relying on DAC mechanisms alone is fundamentally inadequate for strong system security. DAC access decisions are only based on user identity and ownership, ignoring other security-relevant information such as the role of the user, the function and trustworthiness of the program, and the sensitivity and integrity of the data. Each user has complete discretion over their files, making it impossible to enforce a system-wide security policy. Furthermore, every program run by a user inherits all of the permissions granted to the user and is free to change access to the user's files, so no protection is provided against malicious software. Many system services and privileged programs must run with coarse-grained privileges that far exceed their requirements, so that a flaw in any one of these programs could be exploited to obtain further system access.<sup>[<a id="d0e495" href="#ftn.d0e495" class="footnote">1</a>]</sup> </div><div class="para"> The following is an example of permissions used on Linux operating systems that do not run Security-Enhanced Linux (SELinux). The permissions and output in these examples may differ from your system. Use the <code class="command">ls -l</code> command to view file permissions: </div><pre class="screen">$ ls -l file1 -rwxrw-r-- 1 user1 group1 0 2009-08-30 11:03 file1 </pre><div class="para"> The first three permission bits, <code class="computeroutput">rwx</code>, control the access the Linux <code class="computeroutput">user1</code> user (in this case, the owner) has to <code class="filename">file1</code>. The next three permission bits, <code class="computeroutput">rw-</code>, control the access the Linux <code class="computeroutput">group1</code> group has to <code class="filename">file1</code>. The last three permission bits, <code class="computeroutput">r--</code>, control the access everyone else has to <code class="filename">file1</code>, which includes all users and processes. </div><div class="para"> Security-Enhanced Linux (SELinux) adds Mandatory Access Control (MAC) to the Linux kernel, and is enabled by default in Fedora. A general purpose MAC architecture needs the ability to enforce an administratively-set security policy over all processes and files in the system, basing decisions on labels containing a variety of security-relevant information. When properly implemented, it enables a system to adequately defend itself and offers critical support for application security by protecting against the tampering with, and bypassing of, secured applications. MAC provides strong separation of applications that permits the safe execution of untrustworthy applications. Its ability to limit the privileges associated with executing processes limits the scope of potential damage that can result from the exploitation of vulnerabilities in applications and system services. MAC enables information to be protected from legitimate users with limited authorization as well as from au thorized users who have unwittingly executed malicious applications.<sup>[<a id="d0e537" href="#ftn.d0e537" class="footnote">2</a>]</sup> </div><div class="para"> The following is an example of the labels containing security-relevant information that are used on processes, Linux users, and files, on Linux operating systems that run SELinux. This information is called the SELinux <span class="emphasis"><em>context</em></span>, and is viewed using the <code class="command">ls -Z</code> command: </div><pre class="screen">$ ls -Z file1 -rwxrw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre><div class="para"> In this example, SELinux provides a user (<code class="computeroutput">unconfined_u</code>), a role (<code class="computeroutput">object_r</code>), a type (<code class="computeroutput">user_home_t</code>), and a level (<code class="computeroutput">s0</code>). This information is used to make access control decisions. With DAC, access is controlled based only on Linux user and group IDs. It is important to remember that SELinux policy rules are checked <span class="emphasis"><em>after</em></span> DAC rules. SELinux policy rules are not used if DAC rules deny access first. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Introduction-Linux_and_SELinux_Users">Linux and SELinux Users</h5> On Linux operating systems that run SELinux, there are Linux users as well as SELinux users. SELinux users are part of SELinux policy. Linux users are mapped to SELinux users. To avoid confusion, this guide uses "Linux user" and "SELinux user" to differentiate between the two. </div><div class="section" title="2.1. Benefits of running SELinux"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Introduction-Benefits_of_running_SELinux">2.1. Benefits of running SELinux</h2></div></div></div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> All processes and files are labeled with a type. A type defines a domain for processes, and a type for files. Processes are separated from each other by running in their own domains, and SELinux policy rules define how processes interact with files, as well as how processes interact with each other. Access is only allowed if an SELinux policy rule exists that specifically allows it. </div></li><li class="listitem"><div class="para"> Fine-grained access control. Stepping beyond traditional <span class="trademark">UNIX</span>® permissions that are controlled at user discretion and based on Linux user and group IDs, SELinux access decisions are based on all available information, such as an SELinux user, role, type, and, optionally, a level. </div></li><li class="listitem"><div class="para"> SELinux policy is administratively-defined, enforced system-wide, and is not set at user discretion. </div></li><li class="listitem"><div class="para"> Reduced vulnerability to privilege escalation attacks. One example: since processes run in domains, and are therefore separated from each other, and because SELinux policy rules define how processes access files and other processes, if a process is compromised, the attacker only has access to the normal functions of that process, and to files the process has been configured to have access to. For example, if the Apache HTTP Server is compromised, an attacker can not use that process to read files in user home directories, unless a specific SELinux policy rule was added or configured to allow such access. </div></li><li class="listitem"><div class="para"> SELinux can be used to enforce data confidentiality and integrity, as well as protecting processes from untrusted inputs. </div></li></ul></div><div class="para"> SELinux is not: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> antivirus software. </div></li><li class="listitem"><div class="para"> a replacement for passwords, firewalls, or other security systems. </div></li><li class="listitem"><div class="para"> an all-in-one security solution. </div></li></ul></div><div class="para"> SELinux is designed to enhance existing security solutions, not replace them. Even when running SELinux, continue to follow good security practices, such as keeping software up-to-date, using hard-to-guess passwords, firewalls, and so on. </div></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e495" href="#d0e495" class="para">1</a>] </sup> "Integrating Flexible Support for Security Policies into the Linux Operating System", by Peter Loscocco and Stephen Smalley. This paper was originally prepared for the National Security Agency and is, consequently, in the public domain. Refer to the <a href="http://www.nsa.gov/research/_files/selinux/papers/freenix01/index.shtml">original paper</a> for details and the document as it was first released. Any edits and changes were done by Murray McAllister. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e537" href="#d0e537" class="para">2</a>] </sup> "Meeting Critical Security Objectives with Security-Enhanced Linux", by Peter Loscocco and Stephen Smalley. This paper was originally prepared for the National Security Agency and is, consequently, in the public domain. Refer to the <a href="http://www.nsa.gov/research/_files/selinux/papers/ottawa01/index.shtml">original paper</a> for details and the document as it was first released. Any edits and changes were done by Murray McAllister. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Trademark_Information.html"><strong>Prev</strong>Chapter 1. Trademark Information</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-Examples.html"><strong>Next</strong>2.2. Examples</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-SELinux_Contexts.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 3. SELinux Contexts</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html" title="2.4. SELinux on Other Operating Systems"/><link rel="next" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html" title="3.2. SELinux Contexts for Processes"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_ri ght.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 3. SELinux Contexts"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-SELinux_Contexts">Chapter 3. SELinux Contexts</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-SELinux_Contexts.html#sect-Security-Enhanced_Linux-SELinux_Contexts-Domain_Transitions">3.1. Domain Transitions</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html">3.2. SELinux Contexts for Processes</a></span></dt>< dt><span class="section"><a href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html">3.3. SELinux Contexts for Users</a></span></dt></dl></div><div class="para"> Processes and files are labeled with an SELinux context that contains additional information, such as an SELinux user, role, type, and, optionally, a level. When running SELinux, all of this information is used to make access control decisions. In Fedora, SELinux provides a combination of Role-Based Access Control (RBAC), <span class="trademark">Type Enforcement</span>® (TE), and, optionally, Multi-Level Security (MLS). </div><div class="para"> The following is an example showing SELinux context. SELinux contexts are used on processes, Linux users, and files, on Linux operating systems that run SELinux. Use the <code class="command">ls -Z</code> command to view the SELinux context of files and directories: </div><pre class="screen">$ ls -Z file1 -rwxrw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre><div class="para"> SELinux contexts follow the <span class="emphasis"><em>SELinux user:role:type:level</em></span> syntax: </div><div class="variablelist"><dl><dt><span class="term"><span class="emphasis"><em>SELinux user</em></span></span></dt><dd><div class="para"> The SELinux user identity is an identity known to the policy that is authorized for a specific set of roles, and for a specific MLS range. Each Linux user is mapped to an SELinux user via SELinux policy. This allows Linux users to inherit the restrictions placed on SELinux users. The mapped SELinux user identity is used in the SELinux context for processes in that session, in order to define what roles and levels they can enter. Run the <code class="command">semanage login -l</code> command as the Linux root user to view a list of mappings between SELinux and Linux user accounts: </div><pre class="screen"> # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre><div class="para"> Output may differ from system to system. The <code class="computeroutput">Login Name</code> column lists Linux users, and the the <code class="computeroutput">SELinux User</code> column lists which SELinux user the Linux user is mapped to. For processes, the SELinux user limits which roles and levels are accessible. The last column, <code class="computeroutput">MLS/MCS Range</code>, is the level used by Multi-Level Security (MLS) and Multi-Category Security (MCS). Levels are briefly discussed later. </div></dd><dt><span class="term"><span class="emphasis"><em>role</em></span></span></dt><dd><div class="para"> Part of SELinux is the Role-Based Access Control (RBAC) security model. The role is an attribute of RBAC. SELinux users are authorized for roles, and roles are authorized for domains. The role serves as an intermediary between domains and SELinux users. The roles that can be entered determine which domains can be entered - ultimately, this controls which object types can be accessed. This helps reduce vulnerability to privilege escalation attacks. </div></dd><dt><span class="term"><span class="emphasis"><em>type</em></span></span></dt><dd><div class="para"> The type is an attribute of Type Enforcement. The type defines a domain for processes, and a type for files. SELinux policy rules define how types can access each other, whether it be a domain accessing a type, or a domain accessing another domain. Access is only allowed if a specific SELinux policy rule exists that allows it. </div></dd><dt><span class="term"><span class="emphasis"><em>level</em></span></span></dt><dd><div class="para"> The level is an attribute of MLS and Multi-Category Security (MCS). An MLS range is a pair of levels, written as <span class="emphasis"><em>lowlevel-highlevel</em></span> if the levels differ, or <span class="emphasis"><em>lowlevel</em></span> if the levels are identical (<code class="computeroutput">s0-s0</code> is the same as <code class="computeroutput">s0</code>). Each level is a sensitivity-category pair, with categories being optional. If there are categories, the level is written as <span class="emphasis"><em>sensitivity:category-set</em></span>. If there are no categories, it is written as <span class="emphasis"><em>sensitivity</em></span>. </div><div class="para"> If the category set is a contiguous series, it can be abbreviated. For example, <code class="computeroutput">c0.c3</code> is the same as <code class="computeroutput">c0,c1,c2,c3</code>. The <code class="filename">/etc/selinux/targeted/setrans.conf</code> file maps levels (<code class="computeroutput">s0:c0</code>) to human-readable form (ie. <code class="computeroutput">CompanyConfidential</code>). Do not edit <code class="filename">setrans.conf</code> with a text editor: use <code class="command">semanage</code> to make changes. Refer to the <span class="citerefentry"><span class="refentrytitle">semanage</span>(8)</span> manual page for further information. In Fedora, targeted policy enforces MCS, and in MCS, there is just one sensitivity, <code class="computeroutput">s0</code>. MCS in Fedora supports 1024 different categories: <code class="computeroutput">c0</code> through to <code class="computeroutput">c1023</code>. <code class="computeroutput">s0-s0:c0.c1023</code> is sensitivity <code class="computeroutput">s0</code> and authorized for all categories. </div><div class="para"> MLS enforces the <a href="http://en.wikipedia.org/wiki/Bell-LaPadula_model">Bell-La Padula Mandatory Access Model</a>, and is used in Labeled Security Protection Profile (LSPP) environments. To use MLS restrictions, install the <span class="package">selinux-policy-mls</span> package, and configure MLS to be the default SELinux policy. The MLS policy shipped with Fedora omits many program domains that were not part of the evaluated configuration, and therefore, MLS on a desktop workstation is unusable (no support for the X Window System); however, an MLS policy from the <a href="http://oss.tresys.com/projects/refpolicy">upstream SELinux Reference Policy</a> can be built that includes all program domains. </div></dd></dl></div><div class="section" title="3.1. Domain Transitions"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-SELinux_Contexts-Domain_Transitions">3.1. Domain Transitions</h2></div></div></div><div class="para"> A process in one domain transitions to another domain by executing an application that has the <code class="computeroutput">entrypoint</code> type for the new domain. The <code class="computeroutput">entrypoint</code> permission is used in SELinux policy, and controls which applications can be used to enter a domain. The following example demonstrates a domain transition: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> A user wants to change their password. To do this, they run the <code class="command">passwd</code> application. The <code class="filename">/usr/bin/passwd</code> executable is labeled with the <code class="computeroutput">passwd_exec_t</code> type: </div><pre class="screen">$ ls -Z /usr/bin/passwd -rwsr-xr-x root root system_u:object_r:passwd_exec_t:s0 /usr/bin/passwd </pre><div class="para"> The <span class="application"><strong>passwd</strong></span> application accesses <code class="filename">/etc/shadow</code>, which is labeled with the <code class="computeroutput">shadow_t</code> type: </div><pre class="screen">$ ls -Z /etc/shadow -r--------. root root system_u:object_r:shadow_t:s0 /etc/shadow </pre></li><li class="listitem"><div class="para"> An SELinux policy rule states that processes running in the <code class="computeroutput">passwd_t</code> domain are allowed to read and write to files labeled with the <code class="computeroutput">shadow_t</code> type. The <code class="computeroutput">shadow_t</code> type is only applied to files that are required for a password change. This includes <code class="filename">/etc/gshadow</code>, <code class="filename">/etc/shadow</code>, and their backup files. </div></li><li class="listitem"><div class="para"> An SELinux policy rule states that the <code class="computeroutput">passwd_t</code> domain has <code class="computeroutput">entrypoint</code> permission to the <code class="computeroutput">passwd_exec_t</code> type. </div></li><li class="listitem"><div class="para"> When a user runs the <code class="command">/usr/bin/passwd</code> application, the user's shell process transitions to the <code class="computeroutput">passwd_t</code> domain. With SELinux, since the default action is to deny, and a rule exists that allows (among other things) applications running in the <code class="computeroutput">passwd_t</code> domain to access files labeled with the <code class="computeroutput">shadow_t</code> type, the <span class="application"><strong>passwd</strong></span> application is allowed to access <code class="filename">/etc/shadow</code>, and update the user's password. </div></li></ol></div><div class="para"> This example is not exhaustive, and is used as a basic example to explain domain transition. Although there is an actual rule that allows subjects running in the <code class="computeroutput">passwd_t</code> domain to access objects labeled with the <code class="computeroutput">shadow_t</code> file type, other SELinux policy rules must be met before the subject can transition to a new domain. In this example, Type Enforcement ensures: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> the <code class="computeroutput">passwd_t</code> domain can only be entered by executing an application labeled with the <code class="computeroutput">passwd_exec_t</code> type; can only execute from authorized shared libraries, such as the <code class="computeroutput">lib_t</code> type; and can not execute any other applications. </div></li><li class="listitem"><div class="para"> only authorized domains, such as <code class="computeroutput">passwd_t</code>, can write to files labeled with the <code class="computeroutput">shadow_t</code> type. Even if other processes are running with superuser privileges, those processes can not write to files labeled with the <code class="computeroutput">shadow_t</code> type, as they are not running in the <code class="computeroutput">passwd_t</code> domain. </div></li><li class="listitem"><div class="para"> only authorized domains can transition to the <code class="computeroutput">passwd_t</code> domain. For example, the <code class="systemitem">sendmail</code> process running in the <code class="computeroutput">sendmail_t</code> domain does not have a legitimate reason to execute <code class="command">passwd</code>; therefore, it can never transition to the <code class="computeroutput">passwd_t</code> domain. </div></li><li class="listitem"><div class="para"> processes running in the <code class="computeroutput">passwd_t</code> domain can only read and write to authorized types, such as files labeled with the <code class="computeroutput">etc_t</code> or <code class="computeroutput">shadow_t</code> types. This prevents the <span class="application"><strong>passwd</strong></span> application from being tricked into reading or writing arbitrary files. </div></li></ul></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html"><strong>Prev</strong>2.4. SELinux on Other Operating Systems</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html"><strong>Next</strong>3.2. SELinux Contexts for Processes</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Targeted_Policy.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 4. Targeted Policy</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html" title="3.3. SELinux Contexts for Users"/><link rel="next" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html" title="4.2. Unconfined Processes"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/
</a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 4. Targeted Policy"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Targeted_Policy">Chapter 4. Targeted Policy</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Targeted_Policy.html#sect-Security-Enhanced_Linux-Targeted_Policy-Confined_Processes">4.1. Confined Processes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html">4.2. Unconfined Processes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Targeted_Pol
icy-Confined_and_Unconfined_Users.html">4.3. Confined and Unconfined Users</a></span></dt></dl></div><div class="para"> Targeted policy is the default SELinux policy used in Fedora. When using targeted policy, processes that are targeted run in a confined domain, and processes that are not targeted run in an unconfined domain. For example, by default, logged in users run in the <code class="computeroutput">unconfined_t</code> domain, and system processes started by init run in the <code class="computeroutput">initrc_t</code> domain - both of these domains are unconfined. </div><div class="para"> Unconfined domains (as well as confined domains) are subject to executable and writeable memory checks. By default, subjects running in an unconfined domain can not allocate writeable memory and execute it. This reduces vulnerability to <a href="http://en.wikipedia.org/wiki/Buffer_overflow">buffer overflow attacks</a>. These memory checks are disabled by setting Booleans, which allow the SELinux policy to be modified at runtime. Boolean configuration is discussed later. </div><div class="section" title="4.1. Confined Processes"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_Processes">4.1. Confined Processes</h2></div></div></div><div class="para"> Almost every service that listens on a network is confined in Fedora. Also, most processes that run as the Linux root user and perform tasks for users, such as the <span class="application"><strong>passwd</strong></span> application, are confined. When a process is confined, it runs in its own domain, such as the <code class="systemitem">httpd</code> process running in the <code class="computeroutput">httpd_t</code> domain. If a confined process is compromised by an attacker, depending on SELinux policy configuration, an attacker's access to resources and the possible damage they can do is limited. </div><div class="para"> The following example demonstrates how SELinux prevents the Apache HTTP Server (<code class="systemitem">httpd</code>) from reading files that are not correctly labeled, such as files intended for use by Samba. This is an example, and should not be used in production. It assumes that the <span class="package">httpd</span>, <span class="package">wget</span>, <span class="package">setroubleshoot-server</span>, and <span class="package">audit</span> packages are installed, that the SELinux targeted policy is used, and that SELinux is running in enforcing mode: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Run the <code class="command">sestatus</code> command to confirm that SELinux is enabled, is running in enforcing mode, and that targeted policy is being used: </div><pre class="screen"> $ /usr/sbin/sestatus SELinux status: enabled SELinuxfs mount: /selinux Current mode: enforcing Mode from config file: enforcing Policy version: 23 Policy from config file: targeted </pre><div class="para"> <code class="computeroutput">SELinux status: enabled</code> is returned when SELinux is enabled. <code class="computeroutput">Current mode: enforcing</code> is returned when SELinux is running in enforcing mode. <code class="computeroutput">Policy from config file: targeted</code> is returned when the SELinux targeted policy is used. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /var/www/html/testfile</code> command to create a file. </div></li><li class="listitem"><div class="para"> Run the <code class="command">ls -Z /var/www/html/testfile</code> command to view the SELinux context: </div><pre class="screen">-rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 /var/www/html/testfile </pre><div class="para"> By default, Linux users run unconfined in Fedora, which is why the <code class="filename">testfile</code> file is labeled with the SELinux <code class="computeroutput">unconfined_u</code> user. RBAC is used for processes, not files. Roles do not have a meaning for files - the <code class="computeroutput">object_r</code> role is a generic role used for files (on persistent storage and network file systems). Under the <code class="filename">/proc/</code> directory, files related to processes may use the <code class="computeroutput">system_r</code> role.<sup>[<a id="d0e1249" href="#ftn.d0e1249" class="footnote">6</a>]</sup> The <code class="computeroutput">httpd_sys_content_t</code> type allows the <code class="systemitem">httpd</code> process to access this file. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">service httpd start</code> command to start the <code class="systemitem">httpd</code> process. The output is as follows if <code class="systemitem">httpd</code> starts successfully: </div><pre class="screen"># /sbin/service httpd start Starting httpd: [ OK ] </pre></li><li class="listitem"><div class="para"> Change into a directory where your Linux user has write access to, and run the <code class="command">wget http://localhost/testfile</code> command. Unless there are changes to the default configuration, this command succeeds: </div><pre class="screen">--2009-05-06 23:00:01-- http://localhost/testfile Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 0 [text/plain] Saving to: `testfile'
[ <=> ] 0 --.-K/s in 0s 2009-05-06 23:00:01 (0.00 B/s) - `testfile' saved [0/0] </pre></li><li class="listitem"><div class="para"> The <code class="command">chcon</code> command relabels files; however, such label changes do not survive when the file system is relabeled. For permanent changes that survive a file system relabel, use the <code class="command">semanage</code> command, which is discussed later. As the Linux root user, run the following command to change the type to a type used by Samba: </div><div class="para"> <code class="command">chcon -t samba_share_t /var/www/html/testfile</code> </div><div class="para"> Run the <code class="command">ls -Z /var/www/html/testfile</code> command to view the changes: </div><pre class="screen">-rw-r--r-- root root unconfined_u:object_r:samba_share_t:s0 /var/www/html/testfile </pre></li><li class="listitem"><div class="para"> Note: the current DAC permissions allow the <code class="systemitem">httpd</code> process access to <code class="filename">testfile</code>. Change into a directory where your Linux user has write access to, and run the <code class="command">wget http://localhost/testfile</code> command. Unless there are changes to the default configuration, this command fails: </div><pre class="screen">--2009-05-06 23:00:54-- http://localhost/testfile Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:80... connected. HTTP request sent, awaiting response... 403 Forbidden 2009-05-06 23:00:54 ERROR 403: Forbidden. </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">rm -i /var/www/html/testfile</code> command to remove <code class="filename">testfile</code>. </div></li><li class="listitem"><div class="para"> If you do not require <code class="systemitem">httpd</code> to be running, as the Linux root user, run the <code class="command">service httpd stop</code> command to stop <code class="systemitem">httpd</code>: </div><pre class="screen"># /sbin/service httpd stop Stopping httpd: [ OK ] </pre></li></ol></div><div class="para"> This example demonstrates the additional security added by SELinux. Although DAC rules allowed the <code class="systemitem">httpd</code> process access to <code class="filename">testfile</code> in step 7, because the file was labeled with a type that the <code class="systemitem">httpd</code> process does not have access to, SELinux denied access. After step 7, an error similar to the following is logged to <code class="filename">/var/log/messages</code>: </div><pre class="screen">May 6 23:00:54 localhost setroubleshoot: SELinux is preventing httpd (httpd_t) "getattr" to /var/www/html/testfile (samba_share_t). For complete SELinux messages. run sealert -l c05911d3-e680-4e42-8e36-fe2ab9f8e654 </pre><div class="para"> Previous log files may use a <code class="filename">/var/log/messages.<em class="replaceable"><code>YYYYMMDD</code></em></code> format. When running <span class="application"><strong>syslog-ng</strong></span>, previous log files may use a <code class="filename">/var/log/messages.<em class="replaceable"><code>X</code></em></code> format. If the <code class="systemitem">setroubleshootd</code> and <code class="systemitem">auditd</code> processes are running, errors similar to the following are logged to <code class="filename">/var/log/audit/audit.log</code>: </div><pre class="screen">type=AVC msg=audit(1220706212.937:70): avc: denied { getattr } for pid=1904 comm="httpd" path="/var/www/html/testfile" dev=sda5 ino=247576 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file
type=SYSCALL msg=audit(1220706212.937:70): arch=40000003 syscall=196 success=no exit=-13 a0=b9e21da0 a1=bf9581dc a2=555ff4 a3=2008171 items=0 ppid=1902 pid=1904 auid=500 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=1 comm="httpd" exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null) </pre><div class="para"> Also, an error similar to the following is logged to <code class="filename">/var/log/httpd/error_log</code>: </div><pre class="screen">[Wed May 06 23:00:54 2009] [error] [client <em class="replaceable"><code>127.0.0.1</code></em>] (13)Permission denied: access to /testfile denied </pre><div class="note"><h2>Note</h2><div class="para"> In Fedora, the <span class="package">setroubleshoot-server</span> and <span class="package">audit</span> packages are installed by default. These packages include the <code class="systemitem">setroubleshootd</code> and <code class="systemitem">auditd</code> daemons respectively. These daemons run by default. Stopping either of these daemons changes where SELinux denials are written to. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html" title="5.2. Which Log File is Used">Section 5.2, “Which Log File is Used”</a> for further information. </div></div></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e1249" href="#d0e1249" class="para">6</a>] </sup> When using other policies, such as MLS, other roles may be used, for example, <code class="computeroutput">secadm_r</code>. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html"><strong>Prev</strong>3.3. SELinux Contexts for Users</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html"><strong>Next</strong>4.2. Unconfined Processes</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Trademark_Information.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 1. Trademark Information</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="pr01s02.html" title="2. We Need Feedback!"/><link rel="next" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="pr01s02.html"><strong>P rev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Introduction.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 1. Trademark Information"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Trademark_Information">Chapter 1. Trademark Information</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Trademark_Information.html#chap-Security-Enhanced_Linux-Trademark_Information-Source_Code">1.1. Source Code</a></span></dt></dl></div><div class="para"> <span class="trademark">Linux</span>® is the registered trademark of Linus Torvalds in the U.S. and other countries. </div><div class="para"> UNIX is a registered trademark of The Open Group. </div><div class="para"> Type Enforcement is a trademark of Secure Computing, LLC, a wholly owned subsidiary of McAfee, Inc., registered in the U.S. and in other countries. Neither McAfee nor Secure Computing, LLC, has consented to the use or reference to this trademark by the author outside of this guide. </div><div class="para"> Apache is a trademark of The Apache Software Foundation. </div><div class="para"> MySQL is a trademark or registered trademark of MySQL AB in the U.S. and other countries. </div><div class="para"> Other products mentioned may be trademarks of their respective corporations. </div><div class="section" title="1.1. Source Code"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Trademark_Information-Source_Code">1.1. Source Code</h2></div></div></div><div class="para"> The XML source for this guide is available at <a href="http://svn.fedorahosted.org/svn/selinuxguide/">http://svn.fedorahosted.org/svn/selinuxguide/</a> </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="pr01s02.html"><strong>Prev</strong>2. We Need Feedback!</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Introduction.html"><strong>Next</strong>Chapter 2. Introduction</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Troubleshooting.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 7. Troubleshooting</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html" title="6.6. Booleans for Users Executing Applications"/><link rel="next" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html" title="7.2. Top Three Causes of Problems"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/imag es/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 7. Troubleshooting"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Troubleshooting">Chapter 7. Troubleshooting</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Troubleshooting.html#sect-Security-Enhanced_Linux-Troubleshooting-What_Happens_when_Access_is_Denied">7.1. What Happens when Access is Denied</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html">7.2. Top T hree Causes of Problems</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html#sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Labeling_Problems">7.2.1. Labeling Problems</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html">7.2.2. How are Confined Services Running?</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html">7.2.3. Evolving Rules and Broken Applications</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html">7.3. Fixing Problems</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html#sect-Security-Enhanced_Linux-Fixing_Problems-Linux_Permissions">7 .3.1. Linux Permissions</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html">7.3.2. Possible Causes of Silent Denials</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html">7.3.3. Manual Pages for Services</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html">7.3.4. Permissive Domains</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html">7.3.5. Searching For and Viewing Denials</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html">7.3.6. Raw Audit Messages</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html">7.3.7. sealert Messages</a></span></dt><dt> <span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html">7.3.8. Allowing Access: audit2allow</a></span></dt></dl></dd></dl></div><div class="para"> The following chapter describes what happens when SELinux denies access; the top three causes of problems; where to find information about correct labeling; analyzing SELinux denials; and creating custom policy modules with <code class="command">audit2allow</code>. </div><div class="section" title="7.1. What Happens when Access is Denied"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Troubleshooting-What_Happens_when_Access_is_Denied">7.1. What Happens when Access is Denied</h2></div></div></div><div class="para"> SELinux decisions, such as allowing or disallowing access, are cached. This cache is known as the Access Vector Cache (AVC). Denial messages are logged when SELinux denies access. These denials are also known as "AVC denials", and are logged to a different location, depending on which daemons are running: </div><div class="segmentedlist"><table border="0"><thead><tr class="segtitle"><th>Daemon</th><th>Log Location</th></tr></thead><tbody><tr class="seglistitem"><td class="seg">auditd on</td><td class="seg"><code class="filename">/var/log/audit/audit.log</code></td></tr><tr class="seglistitem"><td class="seg">auditd off; rsyslogd on</td><td class="seg"><code class="filename">/var/log/messages</code></td></tr><tr class="seglistitem"><td class="seg">setroubleshootd, rsyslogd, and auditd on</td><td class="seg"><code class="filename">/var/log/audit/audit.log</code>. Easier-to-read denial messages also sent to <code class="filename">/var/log/messages</code></td></tr></tbody></table></div><div class="para"> If you are running the X Window System, have the <span class="package">setroubleshoot</span> and <span class="package">setroubleshoot-server</span> packages installed, and the <code class="systemitem">setroubleshootd</code> and <code class="systemitem">auditd</code> daemons are running, a warning is displayed when access is denied by SELinux: </div><div class="mediaobject"><img src="./images/setroubleshoot_denial.png"/></div><div class="para"> Clicking on the star icon, or on 'Show', presents a detailed analysis of why SELinux denied access, and a possible solution for allowing access. If you are not running the X Window System, it is less obvious when access is denied by SELinux. For example, users browsing your website may receive an error similar to the following: </div><pre class="screen"> Forbidden
You don't have permission to access <em class="replaceable"><code>file name</code></em> on this server </pre><div class="para"> For these situations, if DAC rules (standard Linux permissions) allow access, check <code class="filename">/var/log/messages</code> and <code class="filename">/var/log/audit/audit.log</code> for <code class="computeroutput">"SELinux is preventing"</code> and <code class="computeroutput">"denied"</code> errors respectively. This can be done by running the following commands as the Linux root user: </div><div class="para"> <code class="command">grep "SELinux is preventing" /var/log/messages</code> </div><div class="para"> <code class="command">grep "denied" /var/log/audit/audit.log</code> </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html"><strong>Prev</strong>6.6. Booleans for Users Executing Applications</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html"><strong>Next</strong>7.2. Top Three Causes of Problems</a></li></ul></body></html>
--- NEW FILE chap-Security-Enhanced_Linux-Working_with_SELinux.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Chapter 5. Working with SELinux</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html" title="4.3. Confined and Unconfined Users"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html" title="5.2. Which Log File is Used"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="D ocumentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="chapter" title="Chapter 5. Working with SELinux"><div class="titlepage"><div><div><h2 class="title" id="chap-Security-Enhanced_Linux-Working_with_SELinux">Chapter 5. Working with SELinux</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Working_with_SELinux.html#sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Packages">5.1. SELinux Packages</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html">5.2. Which Log File is Used</a></span></dt><dt><span class="s ection"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html">5.3. Main Configuration File</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html">5.4. Enabling and Disabling SELinux</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html#sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Enabling_SELinux">5.4.1. Enabling SELinux</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html">5.4.2. Disabling SELinux</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html">5.5. SELinux Modes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html">5.6. Booleans</a></sp an></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html#sect-Security-Enhanced_Linux-Booleans-Listing_Booleans">5.6.1. Listing Booleans</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html">5.6.2. Configuring Booleans</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html">5.6.3. Booleans for NFS and CIFS</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html">5.7. SELinux Contexts - Labeling Files</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html#sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Temporary_Changes_chcon">5.7.1. Temporary Changes: chcon</a></span></dt><dt><span class="section"><a href ="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html">5.7.2. Persistent Changes: semanage fcontext</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html">5.8. The file_t and default_t Types</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html">5.9. Mounting File Systems</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html#sect-Security-Enhanced_Linux-Mounting_File_Systems-Context_Mounts">5.9.1. Context Mounts</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html">5.9.2. Changing the Default Context</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mou nting_an_NFS_File_System.html">5.9.3. Mounting an NFS File System</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html">5.9.4. Multiple NFS Mounts</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html">5.9.5. Making Context Mounts Persistent</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html">5.10. Maintaining SELinux Labels </a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html#sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Copying_Files_and_Directories">5.10.1. Copying Files and Directories</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html">5. 10.2. Moving Files and Directories</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html">5.10.3. Checking the Default SELinux Context</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html">5.10.4. Archiving Files with tar</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html">5.10.5. Archiving Files with star</a></span></dt></dl></dd></dl></div><div class="para"> The following sections give a brief overview of the main SELinux packages in Fedora; installing and updating packages; which log files are used; the main SELinux configuration file; enabling and disabling SELinux; SELinux modes; configuring Booleans; temporarily and persistently changing file and directory labels; overriding file system labels with the <code class="command">mount</code> command; mounting NFS file systems; and how to preserve SELinux contexts when copying and archiving files and directories. </div><div class="section" title="5.1. SELinux Packages"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Packages">5.1. SELinux Packages</h2></div></div></div><div class="para"> In Fedora, the SELinux packages are installed by default, unless they are manually excluded during installation. By default, SELinux targeted policy is used, and SELinux runs in enforcing mode. The following is a brief description of the main SELinux packages: </div><div class="para"> <span class="package">policycoreutils</span>: provides utilities, such as <code class="command">semanage</code>, <code class="command">restorecon</code>, <code class="command">audit2allow</code>, <code class="command">semodule</code>, <code class="command">load_policy</code>, and <code class="command">setsebool</code>, for operating and managing SELinux. </div><div class="para"> <span class="package">policycoreutils-gui</span>: provides <code class="command">system-config-selinux</code>, a graphical tool for managing SELinux. </div><div class="para"> <span class="package">selinux-policy</span>: provides the SELinux Reference Policy. The SELinux Reference Policy is a complete SELinux policy, and is used as a basis for other policies, such as the SELinux targeted policy. Refer to the Tresys Technology <a href="http://oss.tresys.com/projects/refpolicy">SELinux Reference Policy</a> page for further information. The <span class="package">selinux-policy-devel</span> package provides development tools, such as <code class="command">/usr/share/selinux/devel/policygentool</code> and <code class="command">/usr/share/selinux/devel/policyhelp</code>, as well as example policy files. This package was merged into the <span class="package">selinux-policy</span> package. </div><div class="para"> <span class="package">selinux-policy-<em class="replaceable"><code>policy</code></em></span>: provides SELinux policies. For targeted policy, install <span class="package">selinux-policy-targeted</span>. For MLS, install <span class="package">selinux-policy-mls</span>. In Fedora 8, the strict policy was merged into targeted policy, allowing confined and unconfined users to co-exist on the same system. </div><div class="para"> <span class="package">setroubleshoot-server</span>: translates denial messages, produced when access is denied by SELinux, into detailed descriptions that are viewed with <code class="command">sealert</code> (which is provided by this package). </div><div class="para"> <span class="package">setools</span>, <span class="package">setools-gui</span>, and <span class="package">setools-console</span>: these packages provide the <a href="http://oss.tresys.com/projects/setools">Tresys Technology SETools distribution</a>, a number of tools and libraries for analyzing and querying policy, audit log monitoring and reporting, and file context management<sup>[<a id="d0e2080" href="#ftn.d0e2080" class="footnote">8</a>]</sup>. The <span class="package">setools</span> package is a meta-package for SETools. The <span class="package">setools-gui</span> package provides the <code class="command">apol</code>, <code class="command">seaudit</code>, and <code class="command">sediffx</code> tools. The <span class="package">setools-console</span> package provides the <code class="command">seaudit-report</code>, <code class="command">sechecker</code>, <code class="command">sediff</code>, <code class="command">seinfo</code>, <code class="command">sesearch</code>, <code class="command">findcon</code>, <code class="command">replcon</code>, and <code class="command">indexcon</code> command line tools. Refer to the <a href="http://oss.tresys.com/projects/setools">Tresys Technology SETools</a> page for information about these tools. </div><div class="para"> <span class="package">libselinux-utils</span>: provides the <code class="command">avcstat</code>, <code class="command">getenforce</code>, <code class="command">getsebool</code>, <code class="command">matchpathcon</code>, <code class="command">selinuxconlist</code>, <code class="command">selinuxdefcon</code>, <code class="command">selinuxenabled</code>, <code class="command">setenforce</code>, <code class="command">togglesebool</code> tools. </div><div class="para"> <span class="package">mcstrans</span>: translates levels, such as <code class="computeroutput">s0-s0:c0.c1023</code>, to an easier to read form, such as <code class="computeroutput">SystemLow-SystemHigh</code>. This package is not installed by default. </div><div class="para"> To install packages in Fedora, as the Linux root user, run the <code class="command">yum install <em class="replaceable"><code>package-name</code></em></code> command. For example, to install the <span class="package">mcstrans</span> package, run the <code class="command">yum install mcstrans</code> command. To upgrade all installed packages in Fedora, run the <code class="command">yum update</code> command. </div><div class="para"> Refer to <a href="http://docs.fedoraproject.org/yum/en/">Managing Software with yum</a><sup>[<a id="d0e2192" href="#ftn.d0e2192" class="footnote">9</a>]</sup> for further information about using <code class="command">yum</code> to manage packages. </div><div class="note"><h2>Note</h2><div class="para"> In previous versions of Fedora, the <span class="package">selinux-policy-devel</span> package is required when making a local policy module with <code class="command">audit2allow -M</code>. </div></div></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e2080" href="#d0e2080" class="para">8</a>] </sup> Brindle, Joshua. "Re: blurb for fedora setools packages" Email to Murray McAllister. 1 November 2008. Any edits or changes in this version were done by Murray McAllister. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e2192" href="#d0e2192" class="para">9</a>] </sup> Managing Software with yum, written by Stuart Ellis, edited by Paul W. Frields, Rodrigo Menezes, and Hugo Cisneiros. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html"><strong>Prev</strong>4.3. Confined and Unconfined Users</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html"><strong>Next</strong>5.2. Which Log File is Used</a></li></ul></body></html>
--- NEW FILE index.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Security-Enhanced Linux</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><meta name="description" content="The SELinux User Guide assists users and administrators in managing and using Security-Enhanced Linux."/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="next" href="pref-Security-Enhanced_Linux-Preface.html" title="Preface"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"/><li class="next"><a accesskey="n" href="pref-Security-Enhanced_Linux-Prefa ce.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="book" title="Security-Enhanced Linux"><div class="titlepage"><div><div class="producttitle"><span class="productname">Fedora</span> <span class="productnumber">12</span></div><div><h1 id="d0e1" class="title">Security-Enhanced Linux</h1></div><div><h2 class="subtitle">User Guide</h2></div><p class="edition">Edition 1.4</p><div><h3 class="corpauthor"> <span class="inlinemediaobject"><object data="Common_Content/images/title_logo.svg" type="image/svg+xml"> Logo</object></span> </h3></div><div><div xml:lang="en-US" class="authorgroup"><div class="author"><h3 class="author"><span class="firstname">Murray</span> <span class="surname">McAllister</span></h3><div class="affiliation"><span class="orgname">Red Hat</span> <span class="orgdiv">Engineering Content Services</span></div><code class="email"><a class="email" href="mailto:mmcallis@redhat.com">mmcallis@redhat.com</a></code></div><div class="author"><h3 class="author"><span class="firstname">Daniel</span> <span class="surname">Walsh</span></h3><div class="affiliation"><span class="orgname">Red Hat</span> <span class="orgdiv">Security Engineering</span></div><code class="email"><a class="email" href="mailto:dwalsh@redhat.com">dwalsh@redhat.com</a></code></div><div class="author"><h3 class="author"><span class="firstname">Dominick</span> <span class="surname">Grift</span></h3><span class="contrib">Technical editor for the Introduction, SELinux Contexts, Targeted Policy, Working with SELinux, Confin ing Users, and Troubleshooting chapters.</span> <div class="affiliation"><span class="orgname"/> <span class="orgdiv"/></div><code class="email"><a class="email" href="mailto:domg472@gmail.com">domg472@gmail.com</a></code></div><div class="author"><h3 class="author"><span class="firstname">Eric</span> <span class="surname">Paris</span></h3><span class="contrib">Technical editor for the Mounting File Systems and Raw Audit Messages sections.</span> <div class="affiliation"><span class="orgname">Red Hat</span> <span class="orgdiv">Security Engineering</span></div><code class="email"><a class="email" href="mailto:eparis@parisplace.org">eparis@parisplace.org</a></code></div><div class="author"><h3 class="author"><span class="firstname">James</span> <span class="surname">Morris</span></h3><span class="contrib">Technical editor for the Introduction and Targeted Policy chapters.</span> <div class="affiliation"><span class="orgname">Red Hat</span> <span class="orgdiv">Security Eng ineering</span></div><code class="email"><a class="email" href="mailto:jmorris@redhat.com">jmorris@redhat.com</a></code></div><div class="author"><h3 class="author"><span class="firstname">Scott</span> <span class="surname">Radvan</span></h3><div class="affiliation"><span class="orgname">Red Hat</span> <span class="orgdiv">Engineering Content Services</span></div><code class="email"><a class="email" href="mailto:sradvan@redhat.com">sradvan@redhat.com</a></code></div></div></div><div><p class="copyright">Copyright © 2009 Red Hat, Inc.</p></div><hr/><div><div id="d0e35" class="legalnotice"><h1 class="legalnotice">Legal Notice</h1><div class="para"> Copyright <span class="trademark"/>© 2009 Red Hat, Inc. This material may only be distributed subject to the terms and conditions set forth in the Open Publication License, V1.0, (the latest version is presently available at <a href="http://www.opencontent.org/openpub/">http://www.opencontent.org/openpub/</a>). </div><div class="para"> Fedora and the Fedora Infinity Design logo are trademarks or registered trademarks of Red Hat, Inc., in the U.S. and other countries. </div><div class="para"> Red Hat and the Red Hat "Shadow Man" logo are registered trademarks of Red Hat Inc. in the United States and other countries. </div><div class="para"> All other trademarks and copyrights referred to are the property of their respective owners. </div><div class="para"> Documentation, as with software itself, may be subject to export control. Read about Fedora Project export controls at <a href="http://fedoraproject.org/wiki/Legal/Export">http://fedoraproject.org/wiki/Legal/Export</a>. </div></div></div><div><div class="abstract" title="Abstract"><h6>Abstract</h6><div class="para">The SELinux User Guide assists users and administrators in managing and using Security-Enhanced <span class="trademark">Linux</span>®.</div></div></div></div><hr/></div><div class="toc"><dl><dt><span class="preface"><a href="pref-Security-Enhanced_Linux-Preface.html">Preface</a></span></dt><dd><dl><dt><span class="section"><a href="pref-Security-Enhanced_Linux-Preface.html#d0e158">1. Document Conventions</a></span></dt><dd><dl><dt><span class="section"><a href="pref-Security-Enhanced_Linux-Preface.html#d0e168">1.1. Typographic Conventions</a></span></dt><dt><span class="section"><a href="pref-Security-Enhanced_Linux-Preface.html#d0e384">1.2. Pull-quote Conventions</a></span></dt><dt><span class="section"><a href="pref-Security-Enhanced_Linux-Preface.html#d0e403">1.3. Notes and Warnings</a></span></dt></dl></dd><dt><span class="section"><a href="pr01s02.html">2. We Need Feedback!</a></span></dt></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Trademark_Information.html">1. Trademark Information</a></span></dt><dd><dl> <dt><span class="section"><a href="chap-Security-Enhanced_Linux-Trademark_Information.html#chap-Security-Enhanced_Linux-Trademark_Information-Source_Code">1.1. Source Code</a></span></dt></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Introduction.html">2. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Introduction.html#sect-Security-Enhanced_Linux-Introduction-Benefits_of_running_SELinux">2.1. Benefits of running SELinux</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Introduction-Examples.html">2.2. Examples</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html">2.3. SELinux Architecture</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html">2.4. SELinux on Other Operating Systems</a></span></dt></dl></dd><dt><span class="cha pter"><a href="chap-Security-Enhanced_Linux-SELinux_Contexts.html">3. SELinux Contexts</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-SELinux_Contexts.html#sect-Security-Enhanced_Linux-SELinux_Contexts-Domain_Transitions">3.1. Domain Transitions</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html">3.2. SELinux Contexts for Processes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html">3.3. SELinux Contexts for Users</a></span></dt></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Targeted_Policy.html">4. Targeted Policy</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Targeted_Policy.html#sect-Security-Enhanced_Linux-Targeted_Policy-Confined_Processes">4.1. Confined Processes</a></span></dt><dt><span class="section"><a hr ef="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html">4.2. Unconfined Processes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html">4.3. Confined and Unconfined Users</a></span></dt></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Working_with_SELinux.html">5. Working with SELinux</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Working_with_SELinux.html#sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Packages">5.1. SELinux Packages</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html">5.2. Which Log File is Used</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html">5.3. Main Configuration File</a></span></dt><dt><span class="section"><a href="sect-Securit y-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html">5.4. Enabling and Disabling SELinux</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html#sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Enabling_SELinux">5.4.1. Enabling SELinux</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html">5.4.2. Disabling SELinux</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html">5.5. SELinux Modes</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html">5.6. Booleans</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html#sect-Security-Enhanced_Linux-Booleans-Listing_Booleans">5.6.1. Listing Bo oleans</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html">5.6.2. Configuring Booleans</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html">5.6.3. Booleans for NFS and CIFS</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html">5.7. SELinux Contexts - Labeling Files</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html#sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Temporary_Changes_chcon">5.7.1. Temporary Changes: chcon</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html">5.7.2. Persistent Changes: semanage fcontext</a></span></dt></dl></dd><dt><span cl ass="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html">5.8. The file_t and default_t Types</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html">5.9. Mounting File Systems</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html#sect-Security-Enhanced_Linux-Mounting_File_Systems-Context_Mounts">5.9.1. Context Mounts</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html">5.9.2. Changing the Default Context</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html">5.9.3. Mounting an NFS File System</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.h tml">5.9.4. Multiple NFS Mounts</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html">5.9.5. Making Context Mounts Persistent</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html">5.10. Maintaining SELinux Labels </a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html#sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Copying_Files_and_Directories">5.10.1. Copying Files and Directories</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html">5.10.2. Moving Files and Directories</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html">5.1 0.3. Checking the Default SELinux Context</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html">5.10.4. Archiving Files with tar</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html">5.10.5. Archiving Files with star</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Confining_Users.html">6. Confining Users</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Confining_Users.html#sect-Security-Enhanced_Linux-Confining_Users-Linux_and_SELinux_User_Mappings">6.1. Linux and SELinux User Mappings</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html">6.2. Confining New Linux Users: useradd</a></span></dt><dt><span class="section"><a href="sect-Security-E nhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html">6.3. Confining Existing Linux Users: semanage login</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html">6.4. Changing the Default Mapping</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html">6.5. xguest: Kiosk Mode</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html">6.6. Booleans for Users Executing Applications</a></span></dt></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Troubleshooting.html">7. Troubleshooting</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Troubleshooting.html#sect-Security-Enhanced_Linux-Troubleshooting-What_Happens_when_Access_is_Denied">7.1. What Happens when Access is Denied </a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html">7.2. Top Three Causes of Problems</a></span></dt><dd><dl><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html#sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Labeling_Problems">7.2.1. Labeling Problems</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html">7.2.2. How are Confined Services Running?</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html">7.2.3. Evolving Rules and Broken Applications</a></span></dt></dl></dd><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html">7.3. Fixing Problems</a></span></dt><dd><dl><dt><span class="section"
<a href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html#sect-Security-Enhanced_Linux-Fixing_Problems-Linux_Permissions">7.3.1. Linux Permissions</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html">7.3.2. Possible Causes of Silent Denials</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html">7.3.3. Manual Pages for Services</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html">7.3.4. Permissive Domains</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html">7.3.5. Searching For and Viewing Denials</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html">7.3.6. Raw Audit Messages</a></span></dt><dt><
span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html">7.3.7. sealert Messages</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html">7.3.8. Allowing Access: audit2allow</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="chap-Security-Enhanced_Linux-Further_Information.html">8. Further Information</a></span></dt><dd><dl><dt><span class="section"><a href="chap-Security-Enhanced_Linux-Further_Information.html#sect-Security-Enhanced_Linux-Further_Information-Contributors">8.1. Contributors</a></span></dt><dt><span class="section"><a href="sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html">8.2. Other Resources</a></span></dt></dl></dd><dt><span class="appendix"><a href="appe-Security-Enhanced_Linux-Revision_History.html">A. Revision History</a></span></dt></dl></div></div><ul class="docnav"><li class="previous"/><li class="ne xt"><a accesskey="n" href="pref-Security-Enhanced_Linux-Preface.html"><strong>Next</strong>Preface</a></li></ul></body></html>
--- NEW FILE pr01s02.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>2. We Need Feedback!</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="pref-Security-Enhanced_Linux-Preface.html" title="Preface"/><link rel="prev" href="pref-Security-Enhanced_Linux-Preface.html" title="Preface"/><link rel="next" href="chap-Security-Enhanced_Linux-Trademark_Information.html" title="Chapter 1. Trademark Information"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesske y="p" href="pref-Security-Enhanced_Linux-Preface.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Trademark_Information.html"><strong>Next</strong></a></li></ul><div class="section" title="2. We Need Feedback!"><div class="titlepage"><div><div><h2 class="title" id="d0e423">2. We Need Feedback!</h2></div></div></div><a id="d0e426" class="indexterm"/><div class="para"> If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you! Please submit a report in Bugzilla: <a href="http://bugzilla.redhat.com/bugzilla/">http://bugzilla.redhat.com/bugzilla/</a> against the product <span class="application"><strong>Fedora Documentation.</strong></span> </div><div class="para"> When submitting a bug report, be sure to mention the manual's identifier: <em class="citetitle">selinux-user-guide</em> </div><div class="para"> If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="pref-Security-Enhanced_Linux-Preface.html"><strong>Prev</strong>Preface</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Trademark_Information.html"><strong>Next</strong>Chapter 1. Trademark Information</a></li></ul></body></html>
--- NEW FILE pref-Security-Enhanced_Linux-Preface.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Preface</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="index.html" title="Security-Enhanced Linux"/><link rel="prev" href="index.html" title="Security-Enhanced Linux"/><link rel="next" href="pr01s02.html" title="2. We Need Feedback!"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="index.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="pr01s0 2.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="preface" title="Preface"><div class="titlepage"><div><div><h1 id="pref-Security-Enhanced_Linux-Preface" class="title">Preface</h1></div></div></div><div class="para"> The Fedora 12 SELinux User Guide is for people with minimal or no experience with SELinux. Although system administration experience is not necessary, content in this guide is written for system administration tasks. This guide provides an introduction to fundamental concepts and practical applications of SELinux. After reading this guide you should have an intermediate understanding of SELinux. </div><div class="para"> Thank you to everyone who offered encouragement, help, and testing - it is most appreciated. Very special thanks to: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Dominick Grift, Stephen Smalley, and Russell Coker for their contributions, help, and patience. </div></li><li class="listitem"><div class="para"> Karsten Wade for his help, adding a component for this guide to <a href="https://bugzilla.redhat.com/"> Red Hat Bugzilla</a>, and sorting out web hosting on <a href="http://docs.fedoraproject.org/">http://docs.fedoraproject.org/</a>. </div></li><li class="listitem"><div class="para"> The <a href="http://fedoraproject.org/wiki/Infrastructure">Fedora Infrastructure Team</a> for providing hosting. </div></li><li class="listitem"><div class="para"> Jens-Ulrik Petersen for making sure the Red Hat Brisbane office has up-to-date Fedora mirrors. </div></li></ul></div><div xml:lang="en-US" class="section" title="1. Document Conventions"><div class="titlepage"><div><div><h2 class="title" id="d0e158">1. Document Conventions</h2></div></div></div><div class="para"> This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information. </div><div class="para"> In PDF and paper editions, this manual uses typefaces drawn from the <a href="https://fedorahosted.org/liberation-fonts/">Liberation Fonts</a> set. The Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not, alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later includes the Liberation Fonts set by default. </div><div class="section" title="1.1. Typographic Conventions"><div class="titlepage"><div><div><h3 class="title" id="d0e168">1.1. Typographic Conventions</h3></div></div></div><div class="para"> Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows. </div><div class="para"> <code class="literal">Mono-spaced Bold</code> </div><div class="para"> Used to highlight system input, including shell commands, file names and paths. Also used to highlight key caps and key-combinations. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> To see the contents of the file <code class="filename">my_next_bestselling_novel</code> in your current working directory, enter the <code class="command">cat my_next_bestselling_novel</code> command at the shell prompt and press <span class="keycap"><strong>Enter</strong></span> to execute the command. </div></blockquote></div><div class="para"> The above includes a file name, a shell command and a key cap, all presented in Mono-spaced Bold and all distinguishable thanks to context. </div><div class="para"> Key-combinations can be distinguished from key caps by the hyphen connecting each part of a key-combination. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> Press <span class="keycap"><strong>Enter</strong></span> to execute the command. </div><div class="para"> Press <span class="keycap"><strong>Ctrl</strong></span>+<span class="keycap"><strong>Alt</strong></span>+<span class="keycap"><strong>F1</strong></span> to switch to the first virtual terminal. Press <span class="keycap"><strong>Ctrl</strong></span>+<span class="keycap"><strong>Alt</strong></span>+<span class="keycap"><strong>F7</strong></span> to return to your X-Windows session. </div></blockquote></div><div class="para"> The first sentence highlights the particular key cap to press. The second highlights two sets of three key caps, each set pressed simultaneously. </div><div class="para"> If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in <code class="literal">Mono-spaced Bold</code>. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> File-related classes include <code class="classname">filesystem</code> for file systems, <code class="classname">file</code> for files, and <code class="classname">dir</code> for directories. Each class has its own associated set of permissions. </div></blockquote></div><div class="para"> <span class="application"><strong>Proportional Bold</strong></span> </div><div class="para"> This denotes words or phrases encountered on a system, including application names; dialogue box text; labelled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> Choose <span class="guimenu"><strong>System > Preferences > Mouse</strong></span> from the main menu bar to launch <span class="application"><strong>Mouse Preferences</strong></span>. In the <span class="guilabel"><strong>Buttons</strong></span> tab, click the <span class="guilabel"><strong>Left-handed mouse</strong></span> check box and click <span class="guibutton"><strong>Close</strong></span> to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand). </div><div class="para"> To insert a special character into a <span class="application"><strong>gedit</strong></span> file, choose <span class="guimenu"><strong>Applications > Accessories > Character Map</strong></span> from the main menu bar. Next, choose <span class="guimenu"><strong>Search > Find…</strong></span> from the <span class="application"><strong>Character Map</strong></span> menu bar, type the name of the character in the <span class="guilabel"><strong>Search</strong></span> field and click <span class="guibutton"><strong>Next</strong></span>. The character you sought will be highlighted in the <span class="guilabel"><strong>Character Table</strong></span>. Double-click this highlighted character to place it in the <span class="guilabel"><strong>Text to copy</strong></span> field and then click the <span class="guibutton"><strong>Copy</strong></span> button. Now switch back to your document and choose <span class="guimenu"><strong>Edit > Paste</strong></span> from the < span class="application"><strong>gedit</strong></span> menu bar. </div></blockquote></div><div class="para"> The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in Proportional Bold and all distinguishable by context. </div><div class="para"> Note the <span class="guimenu"><strong>></strong></span> shorthand used to indicate traversal through a menu and its sub-menus. This is to avoid the difficult-to-follow 'Select <span class="guimenuitem"><strong>Mouse</strong></span> from the <span class="guimenu"><strong>Preferences</strong></span> sub-menu in the <span class="guimenu"><strong>System</strong></span> menu of the main menu bar' approach. </div><div class="para"> <code class="command"><em class="replaceable"><code>Mono-spaced Bold Italic</code></em></code> or <span class="application"><strong><em class="replaceable"><code>Proportional Bold Italic</code></em></strong></span> </div><div class="para"> Whether Mono-spaced Bold or Proportional Bold, the addition of Italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> To connect to a remote machine using ssh, type <code class="command">ssh <em class="replaceable"><code>username</code></em>@<em class="replaceable"><code>domain.name</code></em></code> at a shell prompt. If the remote machine is <code class="filename">example.com</code> and your username on that machine is john, type <code class="command">ssh john@example.com</code>. </div><div class="para"> The <code class="command">mount -o remount <em class="replaceable"><code>file-system</code></em></code> command remounts the named file system. For example, to remount the <code class="filename">/home</code> file system, the command is <code class="command">mount -o remount /home</code>. </div><div class="para"> To see the version of a currently installed package, use the <code class="command">rpm -q <em class="replaceable"><code>package</code></em></code> command. It will return a result as follows: <code class="command"><em class="replaceable"><code>package-version-release</code></em></code>. </div></blockquote></div><div class="para"> Note the words in bold italics above — username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system. </div><div class="para"> Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example: </div><div class="blockquote"><blockquote class="blockquote"><div class="para"> When the Apache HTTP Server accepts requests, it dispatches child processes or threads to handle them. This group of child processes or threads is known as a <em class="firstterm">server-pool</em>. Under Apache HTTP Server 2.0, the responsibility for creating and maintaining these server-pools has been abstracted to a group of modules called <em class="firstterm">Multi-Processing Modules</em> (<em class="firstterm">MPMs</em>). Unlike other modules, only one module from the MPM group can be loaded by the Apache HTTP Server. </div></blockquote></div></div><div class="section" title="1.2. Pull-quote Conventions"><div class="titlepage"><div><div><h3 class="title" id="d0e384">1.2. Pull-quote Conventions</h3></div></div></div><div class="para"> Two, commonly multi-line, data types are set off visually from the surrounding text. </div><div class="para"> Output sent to a terminal is set in <code class="computeroutput">Mono-spaced Roman</code> and presented thus: </div><pre class="screen"> books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs </pre><div class="para"> Source-code listings are also set in <code class="computeroutput">Mono-spaced Roman</code> but are presented and highlighted as follows: </div><pre class="programlisting"> package org.jboss.book.jca.ex1;
import javax.naming.InitialContext;
public class ExClient { public static void main(String args[]) throws Exception { InitialContext iniCtx = new InitialContext(); Object ref = iniCtx.lookup("EchoBean"); EchoHome home = (EchoHome) ref; Echo echo = home.create();
System.out.println("Created Echo");
System.out.println("Echo.echo('Hello') = " + echo.echo("Hello")); }
} </pre></div><div class="section" title="1.3. Notes and Warnings"><div class="titlepage"><div><div><h3 class="title" id="d0e403">1.3. Notes and Warnings</h3></div></div></div><div class="para"> Finally, we use three visual styles to draw attention to information that might otherwise be overlooked. </div><div class="note"><h2>Note</h2><div class="para"> A note is a tip or shortcut or alternative approach to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier. </div></div><div class="important"><h2>Important</h2><div class="para"> Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring Important boxes won't cause data loss but may cause irritation and frustration. </div></div><div class="warning"><h2>Warning</h2><div class="para"> A Warning should not be ignored. Ignoring warnings will most likely cause data loss. </div></div></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="index.html"><strong>Prev</strong>Security-Enhanced Linux</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="pr01s02.html"><strong>Next</strong>2. We Need Feedback!</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.6.3. Booleans for NFS and CIFS</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html" title="5.6. Booleans"/><link rel="prev" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html" title="5.6.2. Configuring Booleans"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html" title="5.7. SELinux Contexts - Labeling Files"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Comm on_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html"><strong>Next</strong></a></li></ul><div class="section" title="5.6.3. Booleans for NFS and CIFS"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS">5.6.3. Booleans for NFS and CIFS</h3></div></div></div><div class="para"> By default, NFS mounts on the client side are labeled with a default context defined by policy for NFS file systems. In common policies, this default context uses the <code class="computeroutput">nfs_t</code> type. Also, by default, Samba shares mounted on the client side are labeled with a default context defined by policy. In common policies, this default context uses the <code class="computeroutput">cifs_t</code> type. </div><div class="para"> Depending on policy configuration, services may not be able to read files labeled with the <code class="computeroutput">nfs_t</code> or <code class="computeroutput">cifs_t</code> types. This may prevent file systems labeled with these types from being mounted and then read or exported by other services. Booleans can be turned on or off to control which services are allowed to access the <code class="computeroutput">nfs_t</code> and <code class="computeroutput">cifs_t</code> types. </div><div class="para"> The <code class="command">setsebool</code> and <code class="command">semanage</code> commands must be run as the Linux root user. The <code class="command">setsebool -P</code> command makes persistent changes. Do not use the <code class="option">-P</code> option if you do not want changes to persist across reboots: </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_NFS_and_CIFS-Apache_HTTP_Server">Apache HTTP Server</h5> To allow access to NFS file systems (files labeled with the <code class="computeroutput">nfs_t</code> type): </div><div class="para"> <code class="command">/usr/sbin/setsebool -P httpd_use_nfs on</code> </div><div class="para"> To allow access to Samba file systems (files labeled with the <code class="computeroutput">cifs_t</code> type): </div><div class="para"> <code class="command">/usr/sbin/setsebool -P httpd_use_cifs on</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_NFS_and_CIFS-Samba">Samba</h5> To export NFS file systems: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P samba_share_nfs on</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_NFS_and_CIFS-FTP_vsftpd">FTP (<code class="systemitem">vsftpd</code>)</h5> To allow access to NFS file systems: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_ftpd_use_nfs on</code> </div><div class="para"> To allow access to Samba file systems: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_ftpd_use_cifs on</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_NFS_and_CIFS-Other_Services">Other Services</h5> For a list of NFS related Booleans for other services: </div><div class="para"> <code class="command">/usr/sbin/semanage boolean -l | grep nfs</code> </div><div class="para"> For a list of Samba related Booleans for other services: </div><div class="para"> <code class="command">/usr/sbin/semanage boolean -l | grep cifs</code> </div><div class="note"><h2>Note</h2><div class="para"> These Booleans exist in SELinux policy as shipped with Fedora 12. They may not exist in policy shipped with other versions of Fedora or other operating systems. </div></div><div class="para"> Refer to the SELinux Managing Confined Services Guide:<a href="http://docs.fedoraproject.org/selinux-managing-confined-services-guide">http://docs.fedoraproject.org/selinux-managing-confined-services-guide</a> for more information relating to SELinux Booleans. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html"><strong>Prev</strong>5.6.2. Configuring Booleans</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html"><strong>Next</strong>5.7. SELinux Contexts - Labeling Files</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.6.2. Configuring Booleans</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html" title="5.6. Booleans"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html" title="5.6. Booleans"/><link rel="next" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html" title="5.6.3. Booleans for NFS and CIFS"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Doc umentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html"><strong>Next</strong></a></li></ul><div class="section" title="5.6.2. Configuring Booleans"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans">5.6.2. Configuring Booleans</h3></div></div></div><div class="para"> The <code class="command">setsebool <em class="replaceable"><code>boolean-name</code></em> <em class="replaceable"><code>x</code></em></code> command turns Booleans on or off, where <em class="replaceable"><code>boolean-name</code></em> is a Boolean name, and <em class="replaceable"><code>x</code></em> is either <code class="option">on</code> to turn the Boolean on, or <code class="option">off</code> to turn it off. </div><div class="para"> The following example demonstrates configuring the <code class="computeroutput">httpd_can_network_connect_db</code> Boolean: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> By default, the <code class="computeroutput">httpd_can_network_connect_db</code> Boolean is off, preventing Apache HTTP Server scripts and modules from connecting to database servers: </div><pre class="screen">$ /usr/sbin/getsebool httpd_can_network_connect_db httpd_can_network_connect_db --> off </pre></li><li class="listitem"><div class="para"> To temporarily enable Apache HTTP Server scripts and modules to connect to database servers, run the <code class="command">setsebool httpd_can_network_connect_db on</code> command as the Linux root user. </div></li><li class="listitem"><div class="para"> Use the <code class="command">getsebool httpd_can_network_connect_db</code> command to verify the Boolean is turned on: </div><pre class="screen">$ /usr/sbin/getsebool httpd_can_network_connect_db httpd_can_network_connect_db --> on </pre><div class="para"> This allows Apache HTTP Server scripts and modules to connect to database servers. </div></li><li class="listitem"><div class="para"> This change is not persistent across reboots. To make changes persistent across reboots, run the <code class="command">setsebool -P <em class="replaceable"><code>boolean-name</code></em> on</code> command as the Linux root user: </div><pre class="screen"># /usr/sbin/setsebool -P httpd_can_network_connect_db on </pre></li><li class="listitem"><div class="para"> To temporarily revert to the default behavior, as the Linux root user, run the <code class="command">setsebool httpd_can_network_connect_db off</code> command. For changes that persist across reboots, run the <code class="command">setsebool -P httpd_can_network_connect_db off</code> command. </div></li></ol></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html"><strong>Prev</strong>5.6. Booleans</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html"><strong>Next</strong>5.6.3. Booleans for NFS and CIFS</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>6.6. Booleans for Users Executing Applications</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="prev" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html" title="6.5. xguest: Kiosk Mode"/><link rel="next" href="chap-Security-Enhanced_Linux-Troubleshooting.html" title="Chapter 7. Troubleshooting"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Troubleshooting.html"><strong>Next</strong></a></li></ul><div class="section" title="6.6. Booleans for Users Executing Applications"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications">6.6. Booleans for Users Executing Applications</h2></div></div></div><div class="para"> Not allowing Linux users to execute applications (which inherit users' permissions) in their home directories and <code class="filename">/tmp/</code>, which they have write access to, helps prevent flawed or malicious applications from modifying files that users own. In Fedora 12, by default, Linux users in the <code class="computeroutput">guest_t</code> and <code class="computeroutput">xguest_t</code> domains can not execute applications in their home directories or <code class="filename">/tmp/</code>; however, by default, Linux users in the <code class="computeroutput">user_t</code> and <code class="computeroutput">staff_t</code> domains can. </div><div class="para"> Booleans are available to change this behavior, and are configured with the <code class="command">setsebool</code> command. The <code class="command">setsebool</code> command must be run as the Linux root user. The <code class="command">setsebool -P</code> command makes persistent changes. Do not use the <code class="option">-P</code> option if you do not want changes to persist across reboots: </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_Users_Executing_Applications-guest_t">guest_t</h5> To <span class="emphasis"><em>allow</em></span> Linux users in the <code class="computeroutput">guest_t</code> domain to execute applications in their home directories and <code class="filename">/tmp/</code>: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_guest_exec_content on</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_Users_Executing_Applications-xguest_t">xguest_t</h5> To <span class="emphasis"><em>allow</em></span> Linux users in the <code class="computeroutput">xguest_t</code> domain to execute applications in their home directories and <code class="filename">/tmp/</code>: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_xguest_exec_content on</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_Users_Executing_Applications-user_t">user_t</h5> To <span class="emphasis"><em>prevent</em></span> Linux users in the <code class="computeroutput">user_t</code> domain from executing applications in their home directories and <code class="filename">/tmp/</code>: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_user_exec_content off</code> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Booleans_for_Users_Executing_Applications-staff_t">staff_t</h5> To <span class="emphasis"><em>prevent</em></span> Linux users in the <code class="computeroutput">staff_t</code> domain from executing applications in their home directories and <code class="filename">/tmp/</code>: </div><div class="para"> <code class="command">/usr/sbin/setsebool -P allow_staff_exec_content off</code> </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html"><strong>Prev</strong>6.5. xguest: Kiosk Mode</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Troubleshooting.html"><strong>Next</strong>Chapter 7. Troubleshooting</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>6.4. Changing the Default Mapping</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="prev" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html" title="6.3. Confining Existing Linux Users: semanage login"/><link rel="next" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html" title="6.5. xguest: Kiosk Mode"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproj ect.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html"><strong>Next</strong></a></li></ul><div class="section" title="6.4. Changing the Default Mapping"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping">6.4. Changing the Default Mapping</h2></div></div></div><div class="para"> In Fedora 12, Linux users are mapped to the SELinux <code class="computeroutput">__default__</code> login by default (which is in turn mapped to the SELinux <code class="computeroutput">unconfined_u</code> user). If you would like new Linux users, and Linux users not specifically mapped to an SELinux user to be confined by default, change the default mapping with the <code class="command">semanage login</code> command. </div><div class="para"> For example, run the following command as the Linux root user to change the default mapping from <code class="computeroutput">unconfined_u</code> to <code class="computeroutput">user_u</code>: </div><div class="para"> <code class="command">/usr/sbin/semanage login -m -S targeted -s "user_u" -r s0 __default__</code> </div><div class="para"> Run the <code class="command">semanage login -l</code> command as the Linux root user to verify the <code class="computeroutput">__default__</code> login is mapped to <code class="computeroutput">user_u</code>: </div><pre class="screen"> # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ user_u s0 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre><div class="para"> If a new Linux user is created and an SELinux user is not specified, or if an existing Linux user logs in and does not match a specific entry from the <code class="command">semanage login -l</code> output, they are mapped to <code class="computeroutput">user_u</code>, as per the <code class="computeroutput">__default__</code> login. </div><div class="para"> To change back to the default behavior, run the following command as the Linux root user to map the <code class="computeroutput">__default__</code> login to the SELinux <code class="computeroutput">unconfined_u</code> user: </div><div class="para"> <pre class="screen">/usr/sbin/semanage login -m -S targeted -s "unconfined_u" -r\ s0-s0:c0.c1023 __default__ </pre> </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html"><strong>Prev</strong>6.3. Confining Existing Linux Users: semanage log...</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html"><strong>Next</strong>6.5. xguest: Kiosk Mode</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>6.3. Confining Existing Linux Users: semanage login</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="prev" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html" title="6.2. Confining New Linux Users: useradd"/><link rel="next" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html" title="6.4. Changing the Default Mapping"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http:// docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html"><strong>Next</strong></a></li></ul><div class="section" title="6.3. Confining Existing Linux Users: semanage login"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login">6.3. Confining Existing Linux Users: semanage login</h2></div></div></div><div class="para"> If a Linux user is mapped to the SELinux <code class="computeroutput">unconfined_u</code> user (the default behavior), and you would like to change which SELinux user they are mapped to, use the <code class="command">semanage login</code> command. The following example creates a new Linux user named newuser, then maps that Linux user to the SELinux <code class="computeroutput">user_u</code> user: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/useradd newuser</code> command to create a new Linux user (newuser). Since this user uses the default mapping, it does not appear in the <code class="command">/usr/sbin/semanage login -l</code> output: </div><pre class="screen"> # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre></li><li class="listitem"><div class="para"> To map the Linux newuser user to the SELinux <code class="computeroutput">user_u</code> user, run the following command as the Linux root user: </div><div class="para"> <code class="command">/usr/sbin/semanage login -a -s user_u newuser</code> </div><div class="para"> The <code class="option">-a</code> option adds a new record, and the <code class="option">-s</code> option specifies the SELinux user to map a Linux user to. The last argument, <code class="computeroutput">newuser</code>, is the Linux user you want mapped to the specified SELinux user. </div></li><li class="listitem"><div class="para"> To view the mapping between the Linux newuser user and <code class="computeroutput">user_u</code>, run the <code class="command">semanage login -l</code> command as the Linux root user: </div><pre class="screen"> # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 newuser user_u s0 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">passwd newuser</code> command to assign a password to the Linux newuser user: </div><pre class="screen"> # passwd newuser Changing password for user newuser. New UNIX password: <em class="replaceable"><code>Enter a password</code></em> Retype new UNIX password: <em class="replaceable"><code>Enter the same password again</code></em> passwd: all authentication tokens updated successfully. </pre></li><li class="listitem"><div class="para"> Log out of your current session, and log in as the Linux newuser user. Run the <code class="command">id -Z</code> command to view the newuser's SELinux context: </div><pre class="screen"> [newuser@rlocalhost ~]$ id -Z user_u:user_r:user_t:s0 </pre></li><li class="listitem"><div class="para"> Log out of the Linux newuser's session, and log back in with your account. If you do not want the Linux newuser user, run the <code class="command">userdel -r newuser</code> command as the Linux root user to remove it, along with its home directory. Also, the mapping between the Linux newuser user and <code class="computeroutput">user_u</code> is removed: </div><pre class="screen"> # /usr/sbin/userdel -r newuser # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre></li></ol></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html"><strong>Prev</strong>6.2. Confining New Linux Users: useradd</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html"><strong>Next</strong>6.4. Changing the Default Mapping</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>6.2. Confining New Linux Users: useradd</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="prev" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="next" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html" title="6.3. Confining Existing Linux Users: semanage login"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"
<img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Confining_Users.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html"><strong>Next</strong></a></li></ul><div class="section" title="6.2. Confining New Linux Users: useradd"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-Confining_New_Linux_Users_useradd">6.2. Confining New Linux Users: useradd</h2></div></div></div><div class="para">
Linux users mapped to the SELinux <code class="computeroutput">unconfined_u</code> user run in the <code class="computeroutput">unconfined_t</code> domain. This is seen by running the <code class="command">id -Z</code> command while logged-in as a Linux user mapped to <code class="computeroutput">unconfined_u</code>: </div><pre class="screen"> $ id -Z unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 </pre><div class="para"> When Linux users run in the <code class="computeroutput">unconfined_t</code> domain, SELinux policy rules are applied, but policy rules exist that allow Linux users running in the <code class="computeroutput">unconfined_t</code> domain almost all access. If unconfined Linux users execute an application that SELinux policy defines can transition from the <code class="computeroutput">unconfined_t</code> domain to its own confined domain, unconfined Linux users are still subject to the restrictions of that confined domain. The security benefit of this is that, even though a Linux user is running unconfined, the application remains confined, and therefore, the exploitation of a flaw in the application can be limited by policy. Note: this does not protect the system from the user. Instead, the user and the system are being protected from possible damage caused by a flaw in the application. </div><div class="para"> When creating Linux users with <code class="command">useradd</code>, use the <code class="option">-Z</code> option to specify which SELinux user they are mapped to. The following example creates a new Linux user, useruuser, and maps that user to the SELinux <code class="computeroutput">user_u</code> user. Linux users mapped to the SELinux <code class="computeroutput">user_u</code> user run in the <code class="computeroutput">user_t</code> domain. In this domain, Linux users are unable to run setuid applications unless SELinux policy permits it (such as <code class="command">passwd</code>), and can not run <code class="command">su</code> or <code class="command">sudo</code>, preventing them from becoming the Linux root user with these commands. </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/useradd -Z user_u useruuser</code> command to create a new Linux user (useruuser) that is mapped to the SELinux <code class="computeroutput">user_u</code> user. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">semanage login -l</code> command to view the mapping between the Linux <code class="computeroutput">useruuser</code> user and <code class="computeroutput">user_u</code>: </div><pre class="screen"> # /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 useruuser user_u s0 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">passwd useruuser</code> command to assign a password to the Linux useruuser user: </div><pre class="screen"> # passwd useruuser Changing password for user useruuser. New UNIX password: <em class="replaceable"><code>Enter a password</code></em> Retype new UNIX password: <em class="replaceable"><code>Enter the same password again</code></em> passwd: all authentication tokens updated successfully. </pre></li><li class="listitem"><div class="para"> Log out of your current session, and log in as the Linux useruuser user. When you log in, pam_selinux maps the Linux user to an SELinux user (in this case, <code class="computeroutput">user_u</code>), and sets up the resulting SELinux context. The Linux user's shell is then launched with this context. Run the <code class="command">id -Z</code> command to view the context of a Linux user: </div><pre class="screen"> [useruuser@localhost ~]$ id -Z user_u:user_r:user_t:s0 </pre></li><li class="listitem"><div class="para"> Log out of the Linux useruuser's session, and log back in with your account. If you do not want the Linux useruuser user, run the <code class="command">/usr/sbin/userdel -r useruuser</code> command as the Linux root user to remove it, along with its home directory. </div></li></ol></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Confining_Users.html"><strong>Prev</strong>Chapter 6. Confining Users</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Confining_Existing_Linux_Users_semanage_login.html"><strong>Next</strong>6.3. Confining Existing Linux Users: semanage log...</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>6.5. xguest: Kiosk Mode</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/><link rel="prev" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html" title="6.4. Changing the Default Mapping"/><link rel="next" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html" title="6.6. Booleans for Users Executing Applications"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedorapr oject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html"><strong>Next</strong></a></li></ul><div class="section" title="6.5. xguest: Kiosk Mode"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Confining_Users-xguest_Kiosk_Mode">6.5. xguest: Kiosk Mode</h2></div></div></div><div class="para"> The <span class="package">xguest</span> package provides a kiosk user account. This account is used to secure machines that people walk up to and use, such as those at libraries, banks, airports, information kiosks, and coffee shops. The kiosk user account is very limited: essentially, it only allows users to log in and use <span class="application"><strong>Firefox</strong></span> to browse Internet websites. Any changes made while logged in with his account, such as creating files or changing settings, are lost when you log out. </div><div class="para"> To set up the kiosk account: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run <code class="command">yum install xguest</code> command to install the <span class="package">xguest</span> package. Install dependencies as required. </div></li><li class="listitem"><div class="para"> In order to allow the kiosk account to be used by a variety of people, the account is not password-protected, and as such, the account can only be protected if SELinux is running in enforcing mode. Before logging in with this account, use the <code class="command">getenforce</code> command to confirm that SELinux is running in enforcing mode: </div><pre class="screen"> $ /usr/sbin/getenforce Enforcing </pre><div class="para"> If this is not the case, refer to <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html" title="5.5. SELinux Modes">Section 5.5, “SELinux Modes”</a> for information about changing to enforcing mode. It is not possible to log in with this account if SELinux is in permissive mode or disabled. </div></li><li class="listitem"><div class="para"> You can only log in to this account via the GNOME Display Manager (GDM). Once the <span class="package">xguest</span> package is installed, a <code class="computeroutput">Guest</code> account is added to GDM. To log in, click on the <code class="computeroutput">Guest</code> account: </div><div class="mediaobject"><img src="./images/xguest.png"/></div></li></ol></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Confining_Users-Changing_the_Default_Mapping.html"><strong>Prev</strong>6.4. Changing the Default Mapping</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html"><strong>Next</strong>6.6. Booleans for Users Executing Applications</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.4.2. Disabling SELinux</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html" title="5.4. Enabling and Disabling SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html" title="5.4. Enabling and Disabling SELinux"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html" title="5.5. SELinux Modes"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedor aproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html"><strong>Next</strong></a></li></ul><div class="section" title="5.4.2. Disabling SELinux"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux">5.4.2. Disabling SELinux</h3></div></div></div><div class="para"> To disable SELinux, configure <code class="option">SELINUX=disabled</code> in <code class="filename">/etc/selinux/config</code>: </div><pre class="screen"># This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted </pre><div class="para"> Reboot your system. After reboot, confirm that the <code class="command">getenforce</code> command returns <code class="computeroutput">Disabled</code>: </div><pre class="screen">$ /usr/sbin/getenforce Disabled </pre></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html"><strong>Prev</strong>5.4. Enabling and Disabling SELinux</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html"><strong>Next</strong>5.5. SELinux Modes</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.8. Allowing Access: audit2allow</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html" title="7.3.7. sealert Messages"/><link rel="next" href="chap-Security-Enhanced_Linux-Further_Information.html" title="Chapter 8. Further Information"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right .png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Further_Information.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.8. Allowing Access: audit2allow"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow">7.3.8. Allowing Access: audit2allow</h3></div></div></div><div class="para"> Do not use the example in this section in production. It is used only to demonstrate the use of <code class="command">audit2allow</code>. </div><div class="para"> From the <span class="citerefentry"><span class="refentrytitle">audit2allow</span>(1)</span> manual page: "<code class="command">audit2allow</code> - generate SELinux policy allow rules from logs of denied operations"<sup>[<a id="d0e6536" href="#ftn.d0e6536" class="footnote">19</a>]</sup>. After analyzing denials as per <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html" title="7.3.7. sealert Messages">Section 7.3.7, “sealert Messages”</a>, and if no label changes or Booleans allowed access, use <code class="command">audit2allow</code> to create a local policy module. After access is denied by SELinux, running the <code class="command">audit2allow</code> command presents Type Enforcement rules that allow the previously denied access. </div><div class="para"> The following example demonstrates using <code class="command">audit2allow</code> to create a policy module: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> A denial and the associated system call are logged to <code class="filename">/var/log/audit/audit.log</code>: </div><pre class="screen"> type=AVC msg=audit(1226270358.848:238): avc: denied { write } for pid=13349 comm="certwatch" name="cache" dev=dm-0 ino=218171 scontext=system_u:system_r:certwatch_t:s0 tcontext=system_u:object_r:var_t:s0 tclass=dir
type=SYSCALL msg=audit(1226270358.848:238): arch=40000003 syscall=39 success=no exit=-13 a0=39a2bf a1=3ff a2=3a0354 a3=94703c8 items=0 ppid=13344 pid=13349 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="certwatch" exe="/usr/bin/certwatch" subj=system_u:system_r:certwatch_t:s0 key=(null) </pre><div class="para"> In this example, <span class="application"><strong>certwatch</strong></span> (<code class="computeroutput">comm="certwatch"</code>) was denied write access (<code class="computeroutput">{ write }</code>) to a directory labeled with the <code class="computeroutput">var_t</code> type (<code class="computeroutput">tcontext=system_u:object_r:var_t:s0</code>). Analyze the denial as per <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html" title="7.3.7. sealert Messages">Section 7.3.7, “sealert Messages”</a>. If no label changes or Booleans allowed access, use <code class="command">audit2allow</code> to create a local policy module. </div></li><li class="listitem"><div class="para"> With a denial logged, such as the <code class="computeroutput">certwatch</code> denial in step 1, run the <code class="command">audit2allow -w -a</code> command to produce a human-readable description of why access was denied. The <code class="option">-a</code> option causes all audit logs to be read. The <code class="option">-w</code> option produces the human-readable description. The <code class="command">audit2allow</code> tool accesses <code class="filename">/var/log/audit/audit.log</code>, and as such, must be run as the Linux root user: </div><pre class="screen"> # audit2allow -w -a type=AVC msg=audit(1226270358.848:238): avc: denied { write } for pid=13349 comm="certwatch" name="cache" dev=dm-0 ino=218171 scontext=system_u:system_r:certwatch_t:s0 tcontext=system_u:object_r:var_t:s0 tclass=dir Was caused by: Missing type enforcement (TE) allow rule.
You can use audit2allow to generate a loadable module to allow this access. </pre><div class="para"> As shown, access was denied due to a missing Type Enforcement rule. </div></li><li class="listitem"><div class="para"> Run the <code class="command">audit2allow -a</code> command to view the Type Enforcement rule that allows the denied access: </div><pre class="screen"> # audit2allow -a
#============= certwatch_t ============== allow certwatch_t var_t:dir write; </pre><div class="important"><h2>Important</h2><div class="para"> Missing Type Enforcement rules are usually caused by bugs in SELinux policy, and should be reported in <a href="https://bugzilla.redhat.com/">Red Hat Bugzilla</a>. For Fedora, create bugs against the <code class="computeroutput">Fedora</code> product, and select the <code class="computeroutput">selinux-policy</code> component. Include the output of the <code class="command">audit2allow -w -a</code> and <code class="command">audit2allow -a</code> commands in such bug reports. </div></div></li><li class="listitem"><div class="para"> To use the rule displayed by <code class="command">audit2allow -a</code>, run the <code class="command">audit2allow -a -M <em class="replaceable"><code>mycertwatch</code></em></code> command as the Linux root user to create custom module. The <code class="option">-M</code> option creates a Type Enforcement file (<code class="filename">.te</code>) with the name specified with <code class="option">-M</code>, in your current working directory: </div><pre class="screen"> # audit2allow -a -M mycertwatch
******************** IMPORTANT *********************** To make this policy package active, execute:
semodule -i mycertwatch.pp
# ls mycertwatch.pp mycertwatch.te </pre><div class="para"> Also, <code class="command">audit2allow</code> compiles the Type Enforcement rule into a policy package (<code class="filename">.pp</code>). To install the module, run the <code class="command">/usr/sbin/semodule -i <em class="replaceable"><code>mycertwatch.pp</code></em></code> command as the Linux root user. </div><div class="important"><h2>Important</h2><div class="para"> Modules created with <code class="command">audit2allow</code> may allow more access than required. It is recommended that policy created with <code class="command">audit2allow</code> be posted to an SELinux list, such as <a href="http://www.redhat.com/mailman/listinfo/fedora-selinux-list">fedora-selinux-list</a>, for review. If you believe their is a bug in policy, create a bug in <a href="https://bugzilla.redhat.com/">Red Hat Bugzilla</a>. </div></div></li></ol></div><div class="para"> If you have multiple denials from multiple processes, but only want to create a custom policy for a single process, use the <code class="command">grep</code> command to narrow down the input for <code class="command">audit2allow</code>. The following example demonstrates using <code class="command">grep</code> to only send denials related to <code class="command">certwatch</code> through <code class="command">audit2allow</code>: </div><pre class="screen"> # grep certwatch /var/log/audit/audit.log | audit2allow -M mycertwatch2 ******************** IMPORTANT *********************** To make this policy package active, execute:
# /usr/sbin/semodule -i mycertwatch2.pp </pre><div class="para"> Refer to Dan Walsh's <a href="http://danwalsh.livejournal.com/24750.html">"Using audit2allow to build policy modules. Revisited."</a> blog entry for further information about using <code class="command">audit2allow</code> to build policy modules. </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e6536" href="#d0e6536" class="para">19</a>] </sup> From the <span class="citerefentry"><span class="refentrytitle">audit2allow</span>(1)</span> manual page, as shipped with the <span class="package">policycoreutils</span> package in Fedora 12. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html"><strong>Prev</strong>7.3.7. sealert Messages</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Further_Information.html"><strong>Next</strong>Chapter 8. Further Information</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.3. Manual Pages for Services</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html" title="7.3.2. Possible Causes of Silent Denials"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html" title="7.3.4. Permissive Domains"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><im g src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.3. Manual Pages for Services"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services">7.3.3. Manual Pages for Services</h3></div></div></div><div class="para"> Manual pages for services contain valuable information, such as what file type to use for a given situation, and Booleans to change the access a service has (such as <code class="systemitem">httpd</code> accessing NFS file systems). This information may be in the standard manual page, or a manual page with <code class="computeroutput">selinux</code> prepended or appended. </div><div class="para"> For example, the <span class="citerefentry"><span class="refentrytitle">httpd_selinux</span>(8)</span> manual page has information about what file type to use for a given situation, as well as Booleans to allow scripts, sharing files, accessing directories inside user home directories, and so on. Other manual pages with SELinux information for services include: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Samba: the <span class="citerefentry"><span class="refentrytitle">samba_selinux</span>(8)</span> manual page describes that files and directories to be exported via Samba must be labeled with the <code class="computeroutput">samba_share_t</code> type, as well as Booleans to allow files labeled with types other than <code class="computeroutput">samba_share_t</code> to be exported via Samba. </div></li><li class="listitem"><div class="para"> NFS: the <span class="citerefentry"><span class="refentrytitle">nfs_selinux</span>(8)</span> manual page describes that, by default, file systems can not be exported via NFS, and that to allow file systems to be exported, Booleans such as <code class="computeroutput">nfs_export_all_ro</code> or <code class="computeroutput">nfs_export_all_rw</code> must be turned on. </div></li><li class="listitem"><div class="para"> Berkeley Internet Name Domain (BIND): the <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span> manual page describes what file type to use for a given situation (see the <code class="computeroutput">Red Hat SELinux BIND Security Profile</code> section). The <span class="citerefentry"><span class="refentrytitle">named_selinux</span>(8)</span> manual page describes that, by default, <code class="systemitem">named</code> can not write to master zone files, and to allow such access, the <code class="computeroutput">named_write_master_zones</code> Boolean must be turned on. </div></li></ul></div><div class="para"> The information in manual pages helps you configure the correct file types and Booleans, helping to prevent SELinux from denying access. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html"><strong>Prev</strong>7.3.2. Possible Causes of Silent Denials</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html"><strong>Next</strong>7.3.4. Permissive Domains</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.4. Permissive Domains</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html" title="7.3.3. Manual Pages for Services"/><link rel="next" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html" title="7.3.4.2. Denials for Permissive Domains"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.or g"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.4. Permissive Domains"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains">7.3.4. Permissive Domains</h3></div></div></div><div class="para"> When SELinux is running in permissive mode, SELinux does not deny access, but denials are logged for actions that would have been denied if running in enforcing mode. Previously, it was not possible to make a single domain permissive (remember: processes run in domains). In certain situations, this led to making the whole system permissive to troubleshoot issues. </div><div class="para"> Fedora 12 includes permissive domains, where an administrator can configure a single process (domain) to run permissive, rather than making the whole system permissive. SELinux checks are still performed for permissive domains; however, the kernel allows access and reports an AVC denial for situations where SELinux would have denied access. Permissive domains are also available in Fedora 9 (with the latest updates applied). </div><div class="para"> In Red Hat Enterprise Linux 4 and 5, <code class="computeroutput"><em class="replaceable"><code>domain</code></em>_disable_trans</code> Booleans are available to prevent an application from transitioning to a confined domain, and therefore, the process runs in an unconfined domain, such as <code class="computeroutput">initrc_t</code>. Turning such Booleans on can cause major problems. For example, if the <code class="computeroutput">httpd_disable_trans</code> Boolean is turned on: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> <code class="systemitem">httpd</code> runs in the unconfined <code class="computeroutput">initrc_t</code> domain. Files created by processes running in the <code class="computeroutput">initrc_t</code> domain may not have the same labeling rules applied as files created by a process running in the <code class="computeroutput">httpd_t</code> domain, potentially allowing processes to create mislabeled files. This causes access problems later on. </div></li><li class="listitem"><div class="para"> confined domains that are allowed to communicate with <code class="computeroutput">httpd_t</code> can not communicate with <code class="computeroutput">initrc_t</code>, possibly causing additional failures. </div></li></ul></div><div class="para"> The <code class="computeroutput"><em class="replaceable"><code>domain</code></em>_disable_trans</code> Booleans were removed from Fedora 7, even though there was no replacement. Permissive domains solve the above issues: transition rules apply, and files are created with the correct labels. </div><div class="para"> Permissive domains can be used for: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> making a single process (domain) run permissive to troubleshoot an issue, rather than putting the entire system at risk by making the entire system permissive. </div></li><li class="listitem"><div class="para"> creating policies for new applications. Previously, it was recommended that a minimal policy be created, and then the entire machine put into permissive mode, so that the application could run, but SELinux denials still logged. <code class="command">audit2allow</code> could then be used to help write the policy. This put the whole system at risk. With permissive domains, only the domain in the new policy can be marked permissive, without putting the whole system at risk. </div></li></ul></div><div class="section" title="7.3.4.1. Making a Domain Permissive"><div class="titlepage"><div><div><h4 class="title" id="sect-Security-Enhanced_Linux-Permissive_Domains-Making_a_Domain_Permissive">7.3.4.1. Making a Domain Permissive</h4></div></div></div><div class="para"> To make a domain permissive, run the <code class="command">semanage permissive -a <em class="replaceable"><code>domain</code></em></code> command, where <em class="replaceable"><code>domain</code></em> is the domain you want to make permissive. For example, run the following command as the Linux root user to make the <code class="computeroutput">httpd_t</code> domain (the domain the Apache HTTP Server runs in) permissive: </div><div class="para"> <code class="command">/usr/sbin/semanage permissive -a httpd_t</code> </div><div class="para"> To view a list of domains you have made permissive, run the <code class="command">semodule -l | grep permissive</code> command as the Linux root user. For example: </div><pre class="screen"> # /usr/sbin/semodule -l | grep permissive permissive_httpd_t 1.0 </pre><div class="para"> If you no longer want a domain to be permissive, run the <code class="command">semanage permissive -d <em class="replaceable"><code>domain</code></em></code> command as the Linux root user. For example: </div><div class="para"> <code class="command">/usr/sbin/semanage permissive -d httpd_t</code> </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html"><strong>Prev</strong>7.3.3. Manual Pages for Services</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html"><strong>Next</strong>7.3.4.2. Denials for Permissive Domains</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.2. Possible Causes of Silent Denials</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html" title="7.3.3. Manual Pages for Services"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Co ntent/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.2. Possible Causes of Silent Denials"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials">7.3.2. Possible Causes of Silent Denials</h3></div></div></div><div class="para"> In certain situations, AVC denials may not be logged when SELinux denies access. Applications and system library functions often probe for more access than required to perform their tasks. To maintain least privilege without filling audit logs with AVC denials for harmless application probing, the policy can silence AVC denials without allowing a permission by using <code class="computeroutput">dontaudit</code> rules. These rules are common in standard policy. The downside of <code class="computeroutput">dontaudit</code> is that, although SELinux denies access, denial messages are not logged, making troubleshooting hard. </div><div class="para"> To temporarily disable <code class="computeroutput">dontaudit</code> rules, allowing all denials to be logged, run the following command as the Linux root user: </div><div class="para"> <code class="command">/usr/sbin/semodule -DB</code> </div><div class="para"> The <code class="option">-D</code> option disables <code class="computeroutput">dontaudit</code> rules; the <code class="option">-B</code> option rebuilds policy. After running <code class="command">semodule -DB</code>, try exercising the application that was encountering permission problems, and see if SELinux denials — relevant to the application — are now being logged. Take care in deciding which denials should be allowed, as some should be ignored and handled via <code class="computeroutput">dontaudit</code> rules. If in doubt, or in search of guidance, contact other SELinux users and developers on an SELinux list, such as <a href="http://www.redhat.com/mailman/listinfo/fedora-selinux-list">fedora-selinux-list</a>. </div><div class="para"> To rebuild policy and enable <code class="computeroutput">dontaudit</code> rules, run the following command as the Linux root user: </div><div class="para"> <code class="command">/usr/sbin/semodule -B</code> </div><div class="para"> This restores the policy to its original state. For a full list of <code class="computeroutput">dontaudit</code> rules, run the <code class="command">sesearch --dontaudit</code> command. Narrow down searches using the <code class="option">-s <em class="replaceable"><code>domain</code></em></code> option and the <code class="command">grep</code> command. For example: </div><pre class="screen"> $ sesearch --dontaudit -s smbd_t | grep squid WARNING: This policy contained disabled aliases; they have been removed. dontaudit smbd_t squid_port_t : tcp_socket name_bind ; dontaudit smbd_t squid_port_t : udp_socket name_bind ; </pre><div class="para"> Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html" title="7.3.6. Raw Audit Messages">Section 7.3.6, “Raw Audit Messages”</a> and <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html" title="7.3.7. sealert Messages">Section 7.3.7, “sealert Messages”</a> for information about analyzing denials. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html"><strong>Prev</strong>7.3. Fixing Problems</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Manual_Pages_for_Services.html"><strong>Next</strong>7.3.3. Manual Pages for Services</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.6. Raw Audit Messages</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html" title="7.3.5. Searching For and Viewing Denials"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html" title="7.3.7. sealert Messages"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Comm on_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.6. Raw Audit Messages"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages">7.3.6. Raw Audit Messages</h3></div></div></div><div class="para"> Raw audit messages are logged to <code class="filename">/var/log/audit/audit.log</code>. The following is an example AVC denial (and the associated system call) that occurred when the Apache HTTP Server (running in the <code class="computeroutput">httpd_t</code> domain) attempted to access the <code class="filename">/var/www/html/file1</code> file (labeled with the <code class="computeroutput">samba_share_t</code> type): </div><pre class="screen"> type=AVC msg=audit(1226874073.147:96): avc: denied { getattr } for pid=2465 comm="httpd" path="/var/www/html/file1" dev=dm-0 ino=284133 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file
type=SYSCALL msg=audit(1226874073.147:96): arch=40000003 syscall=196 success=no exit=-13 a0=b98df198 a1=bfec85dc a2=54dff4 a3=2008171 items=0 ppid=2463 pid=2465 auid=502 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=6 comm="httpd" exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null) </pre><div class="variablelist"><dl><dt><span class="term"><em class="replaceable"><code>{ getattr }</code></em></span></dt><dd><div class="para"> The item in braces indicates the permission that was denied. <code class="computeroutput">getattr</code> indicates the source process was trying to read the target file's status information. This occurs before reading files. This action is denied due to the file being accessed having the wrong label. Commonly seen permissions include <code class="computeroutput">getattr</code>, <code class="computeroutput">read</code>, and <code class="computeroutput">write</code>. </div></dd><dt><span class="term">comm="<em class="replaceable"><code>httpd</code></em>"</span></dt><dd><div class="para"> The executable that launched the process. The full path of the executable is found in the <code class="computeroutput">exe=</code> section of the system call (<code class="computeroutput">SYSCALL</code>) message, which in this case, is <code class="computeroutput">exe="/usr/sbin/httpd"</code>. </div></dd><dt><span class="term">path="<em class="replaceable"><code>/var/www/html/file1</code></em>"</span></dt><dd><div class="para"> The path to the object (target) the process attempted to access. </div></dd><dt><span class="term">scontext="<em class="replaceable"><code>unconfined_u:system_r:httpd_t:s0</code></em>"</span></dt><dd><div class="para"> The SELinux context of the process that attempted the denied action. In this case, it is the SELinux context of the Apache HTTP Server, which is running in the <code class="computeroutput">httpd_t</code> domain. </div></dd><dt><span class="term">tcontext="<em class="replaceable"><code>unconfined_u:object_r:samba_share_t:s0</code></em>"</span></dt><dd><div class="para"> The SELinux context of the object (target) the process attempted to access. In this case, it is the SELinux context of <code class="filename">file1</code>. Note: the <code class="computeroutput">samba_share_t</code> type is not accessible to processes running in the <code class="computeroutput">httpd_t</code> domain. </div><div class="para"> In certain situations, the <code class="computeroutput">tcontext</code> may match the <code class="computeroutput">scontext</code>, for example, when a process attempts to execute a system service that will change characteristics of that running process, such as the user ID. Also, the <code class="computeroutput">tcontext</code> may match the <code class="computeroutput">scontext</code> when a process tries to use more resources (such as memory) than normal limits allow, resulting in a security check to see if that process is allowed to break those limits. </div></dd></dl></div><div class="para"> From the system call (<code class="computeroutput">SYSCALL</code>) message, two items are of interest: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> <code class="computeroutput">success=<em class="replaceable"><code>no</code></em></code>: indicates whether the denial (AVC) was enforced or not. <code class="computeroutput">success=no</code> indicates the system call was not successful (SELinux denied access). <code class="computeroutput">success=yes</code> indicates the system call was successful - this can be seen for permissive domains or unconfined domains, such as <code class="computeroutput">initrc_t</code> and <code class="computeroutput">kernel_t</code>. </div></li><li class="listitem"><div class="para"> <code class="computeroutput">exe="<em class="replaceable"><code>/usr/sbin/httpd</code></em>"</code>: the full path to the executable that launched the process, which in this case, is <code class="computeroutput">exe="/usr/sbin/httpd"</code>. </div></li></ul></div><div class="para"> An incorrect file type is a common cause for SELinux denying access. To start troubleshooting, compare the source context (<code class="computeroutput">scontext</code>) with the target context (<code class="computeroutput">tcontext</code>). Should the process (<code class="computeroutput">scontext</code>) be accessing such an object (<code class="computeroutput">tcontext</code>)? For example, the Apache HTTP Server (<code class="computeroutput">httpd_t</code>) should only be accessing types specified in the <span class="citerefentry"><span class="refentrytitle">httpd_selinux</span>(8)</span> manual page, such as <code class="computeroutput">httpd_sys_content_t</code>, <code class="computeroutput">public_content_t</code>, and so on, unless configured otherwise. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html"><strong>Prev</strong>7.3.5. Searching For and Viewing Denials</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html"><strong>Next</strong>7.3.7. sealert Messages</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.5. Searching For and Viewing Denials</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html" title="7.3.4.2. Denials for Permissive Domains"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html" title="7.3.6. Raw Audit Messages"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.o rg"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.5. Searching For and Viewing Denials"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials">7.3.5. Searching For and Viewing Denials</h3></div></div></div><div class="para"> This section assumes the <span class="package">setroubleshoot</span>, <span class="package">setroubleshoot-server</span>, and <span class="package">audit</span> packages are installed, and that the <code class="systemitem">auditd</code>, <code class="systemitem">rsyslogd</code>, and <code class="systemitem">setroubleshootd</code> daemons are running. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html" title="5.2. Which Log File is Used">Section 5.2, “Which Log File is Used”</a> for information about starting these daemons. A number of tools are available for searching for and viewing SELinux denials, such as <code class="command">ausearch</code>, <code class="command">aureport</code>, and <code class="command">sealert</code>. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Searching_For_and_Viewing_Denials-ausearch">ausearch</h5> The <span class="package">audit</span> package provides <code class="command">ausearch</code>. From the <span class="citerefentry"><span class="refentrytitle">ausearch</span>(8)</span> manual page: "<code class="command">ausearch</code> is a tool that can query the audit daemon logs based for events based on different search criteria"<sup>[<a id="d0e5982" href="#ftn.d0e5982" class="footnote">16</a>]</sup>. The <code class="command">ausearch</code> tool accesses <code class="filename">/var/log/audit/audit.log</code>, and as such, must be run as the Linux root user: </div><div class="segmentedlist"><table border="0"><thead><tr class="segtitle"><th>Searching For</th><th>Command</th></tr></thead><tbody><tr class="seglistitem"><td class="seg">all denials</td><td class="seg"><code class="command">/sbin/ausearch -m avc</code></td></tr><tr class="seglistitem"><td class="seg">denials for that today</td><td class="seg"><code class="command">/sbin/ausearch -m avc -ts today</code></td></tr><tr class="seglistitem"><td class="seg">denials from the last 10 minutes</td><td class="seg"><code class="command">/sbin/ausearch -m avc -ts recent</code></td></tr></tbody></table></div><div class="para"> To search for SELinux denials for a particular service, use the <code class="option">-c <em class="replaceable"><code>comm-name</code></em></code> option, where <em class="replaceable"><code>comm-name</code></em> "is the executable’s name"<sup>[<a id="d0e6034" href="#ftn.d0e6034" class="footnote">17</a>]</sup>, for example, <code class="systemitem">httpd</code> for the Apache HTTP Server, and <code class="systemitem">smbd</code> for Samba: </div><div class="para"> <code class="command">/sbin/ausearch -m avc -c httpd</code> </div><div class="para"> <code class="command">/sbin/ausearch -m avc -c smbd</code> </div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">ausearch</span>(8)</span> manual page for further <code class="command">ausearch</code> options. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Searching_For_and_Viewing_Denials-aureport">aureport</h5> The <span class="package">audit</span> package provides <code class="command">aureport</code>. From the <span class="citerefentry"><span class="refentrytitle">aureport</span>(8)</span> manual page: "<code class="command">aureport</code> is a tool that produces summary reports of the audit system logs"<sup>[<a id="d0e6094" href="#ftn.d0e6094" class="footnote">18</a>]</sup>. The <code class="command">aureport</code> tool accesses <code class="filename">/var/log/audit/audit.log</code>, and as such, must be run as the Linux root user. To view a list of SELinux denials and how often each one occurred, run the <code class="command">aureport -a</code> command. The following is example output that includes two denials: </div><pre class="screen"> # /sbin/aureport -a
AVC Report ======================================================== # date time comm subj syscall class permission obj event ======================================================== 1. 05/01/2009 21:41:39 httpd unconfined_u:system_r:httpd_t:s0 195 file getattr system_u:object_r:samba_share_t:s0 denied 2 2. 05/03/2009 22:00:25 vsftpd unconfined_u:system_r:ftpd_t:s0 5 file read unconfined_u:object_r:cifs_t:s0 denied 4 </pre><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">aureport</span>(8)</span> manual page for further <code class="command">aureport</code> options. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Searching_For_and_Viewing_Denials-sealert">sealert</h5> The <span class="package">setroubleshoot-server</span> package provides <code class="command">sealert</code>, which reads denial messages translated by <span class="package">setroubleshoot-server</span>. Denials are assigned IDs, as seen in <code class="filename">/var/log/messages</code>. The following is an example denial from <code class="filename">messages</code>: </div><pre class="screen"> setroubleshoot: SELinux is preventing httpd (httpd_t) "getattr" to /var/www/html/file1 (samba_share_t). For complete SELinux messages. run sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020 </pre><div class="para"> In this example, the denial ID is <code class="computeroutput">84e0b04d-d0ad-4347-8317-22e74f6cd020</code>. The <code class="option">-l</code> option takes an ID as an argument. Running the <code class="command">sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020</code> command presents a detailed analysis of why SELinux denied access, and a possible solution for allowing access. </div><div class="para"> If you are running the X Window System, have the <span class="package">setroubleshoot</span> and <span class="package">setroubleshoot-server</span> packages installed, and the <code class="systemitem">setroubleshootd</code> and <code class="systemitem">auditd</code> daemons are running, a yellow star and a warning are displayed when access is denied by SELinux. Clicking on the star launches the <code class="command">sealert</code> GUI, and displays denials in HTML output: </div><div class="mediaobject"><img src="./images/sealert_gui.png"/></div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Run the <code class="command">sealert -b</code> command to launch the <code class="command">sealert</code> GUI. </div></li><li class="listitem"><div class="para"> Run the <code class="command">sealert -l *</code> command to view a detailed analysis of all denials. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">sealert -a /var/log/audit/audit.log -H > audit.html</code> command to create a HTML version of the <code class="command">sealert</code> analysis, as seen with the <code class="command">sealert</code> GUI. </div></li></ul></div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">sealert</span>(8)</span> manual page for further <code class="command">sealert</code> options. </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e5982" href="#d0e5982" class="para">16</a>] </sup> From the <span class="citerefentry"><span class="refentrytitle">ausearch</span>(8)</span> manual page, as shipped with the <span class="package">audit</span> package in Fedora 12. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e6034" href="#d0e6034" class="para">17</a>] </sup> From the <span class="citerefentry"><span class="refentrytitle">ausearch</span>(8)</span> manual page, as shipped with the <span class="package">audit</span> package in Fedora 12. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e6094" href="#d0e6094" class="para">18</a>] </sup> From the <span class="citerefentry"><span class="refentrytitle">aureport</span>(8)</span> manual page, as shipped with the <span class="package">audit</span> package in Fedora 12. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html"><strong>Prev</strong>7.3.4.2. Denials for Permissive Domains</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html"><strong>Next</strong>7.3.6. Raw Audit Messages</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.7. sealert Messages</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html" title="7.3.6. Raw Audit Messages"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html" title="7.3.8. Allowing Access: audit2allow"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Conten t/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.7. sealert Messages"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-sealert_Messages">7.3.7. sealert Messages</h3></div></div></div><div class="para"> Denials are assigned IDs, as seen in <code class="filename">/var/log/messages</code>. The following is an example AVC denial (logged to <code class="filename">messages</code>) that occurred when the Apache HTTP Server (running in the <code class="computeroutput">httpd_t</code> domain) attempted to access the <code class="filename">/var/www/html/file1</code> file (labeled with the <code class="computeroutput">samba_share_t</code> type): </div><pre class="screen"> <em class="replaceable"><code>hostname</code></em> setroubleshoot: SELinux is preventing httpd (httpd_t) "getattr" to /var/www/html/file1 (samba_share_t). For complete SELinux messages. run sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020 </pre><div class="para"> As suggested, run the <code class="command">sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020</code> command to view the complete message. This command only works on the local machine, and presents the same information as the <code class="command">sealert</code> GUI: </div><pre class="screen"> $ sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020
Summary:
SELinux is preventing httpd (httpd_t) "getattr" to /var/www/html/file1 (samba_share_t).
Detailed Description:
SELinux denied access to /var/www/html/file1 requested by httpd. /var/www/html/file1 has a context used for sharing by different program. If you would like to share /var/www/html/file1 from httpd also, you need to change its file context to public_content_t. If you did not intend to this access, this could signal a intrusion attempt.
Allowing Access:
You can alter the file context by executing chcon -t public_content_t '/var/www/html/file1'
Fix Command:
chcon -t public_content_t '/var/www/html/file1'
Additional Information:
Source Context unconfined_u:system_r:httpd_t:s0 Target Context unconfined_u:object_r:samba_share_t:s0 Target Objects /var/www/html/file1 [ file ] Source httpd Source Path /usr/sbin/httpd Port <Unknown> Host <em class="replaceable"><code>hostname</code></em> Source RPM Packages httpd-2.2.10-2 Target RPM Packages Policy RPM selinux-policy-3.5.13-11.fc12 Selinux Enabled True Policy Type targeted MLS Enabled True Enforcing Mode Enforcing Plugin Name public_content Host Name <em class="replaceable"><code>hostname</code></em> Platform <em class="replaceable"><code>Linux hostname 2.6.27.4-68.fc12.i686 #1 SMP Thu Oct</code></em> 30 00:49:42 EDT 2008 i686 i686 Alert Count 4 First Seen Wed Nov 5 18:53:05 2008 Last Seen Wed Nov 5 01:22:58 2008 Local ID 84e0b04d-d0ad-4347-8317-22e74f6cd020 Line Numbers
Raw Audit Messages
node=<em class="replaceable"><code>hostname</code></em> type=AVC msg=audit(1225812178.788:101): avc: denied { getattr } for pid=2441 comm="httpd" path="/var/www/html/file1" dev=dm-0 ino=284916 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file
node=<em class="replaceable"><code>hostname</code></em> type=SYSCALL msg=audit(1225812178.788:101): arch=40000003 syscall=196 success=no exit=-13 a0=b8e97188 a1=bf87aaac a2=54dff4 a3=2008171 items=0 ppid=2439 pid=2441 auid=502 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=3 comm="httpd" exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null) </pre><div class="variablelist"><dl><dt><span class="term">Summary</span></dt><dd><div class="para"> A brief summary of the denied action. This is the same as the denial in <code class="filename">/var/log/messages</code>. In this example, the <code class="systemitem">httpd</code> process was denied access to a file (<code class="filename">file1</code>), which is labeled with the <code class="computeroutput">samba_share_t</code> type. </div></dd><dt><span class="term">Detailed Description</span></dt><dd><div class="para"> A more verbose description. In this example, <code class="filename">file1</code> is labeled with the <code class="computeroutput">samba_share_t</code> type. This type is used for files and directories that you want to export via Samba. The description suggests changing the type to a type that can be accessed by the Apache HTTP Server and Samba, if such access is desired. </div></dd><dt><span class="term">Allowing Access</span></dt><dd><div class="para"> A suggestion for how to allow access. This may be relabeling files, turning a Boolean on, or making a local policy module. In this case, the suggestion is to label the file with a type accessible to both the Apache HTTP Server and Samba. </div></dd><dt><span class="term">Fix Command</span></dt><dd><div class="para"> A suggested command to allow access and resolve the denial. In this example, it gives the command to change the <code class="filename">file1</code> type to <code class="computeroutput">public_content_t</code>, which is accessible to the Apache HTTP Server and Samba. </div></dd><dt><span class="term">Additional Information</span></dt><dd><div class="para"> Information that is useful in bug reports, such as the policy package name and version (<code class="computeroutput">selinux-policy-3.5.13-11.fc12</code>), but may not help towards solving why the denial occurred. </div></dd><dt><span class="term">Raw Audit Messages</span></dt><dd><div class="para"> The raw audit messages from <code class="filename">/var/log/audit/audit.log</code> that are associated with the denial. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html" title="7.3.6. Raw Audit Messages">Section 7.3.6, “Raw Audit Messages”</a> for information about each item in the AVC denial. </div></dd></dl></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages.html"><strong>Prev</strong>7.3.6. Raw Audit Messages</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html"><strong>Next</strong>7.3.8. Allowing Access: audit2allow</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Further_Information-Other_Resources.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>8.2. Other Resources</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Further_Information.html" title="Chapter 8. Further Information"/><link rel="prev" href="chap-Security-Enhanced_Linux-Further_Information.html" title="Chapter 8. Further Information"/><link rel="next" href="appe-Security-Enhanced_Linux-Revision_History.html" title="Appendix A. Revision History"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation S ite"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Further_Information.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="appe-Security-Enhanced_Linux-Revision_History.html"><strong>Next</strong></a></li></ul><div class="section" title="8.2. Other Resources"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Further_Information-Other_Resources">8.2. Other Resources</h2></div></div></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-The_National_Security_Agency_NSA">The National Security Agency (NSA)</h5> From the NSA <a href="http://www.nsa.gov/research/selinux/contrib.shtml">Contributors to SELinux</a> page: </div><div class="para"> <span class="emphasis"><em>Researchers in NSA's National Information Assurance Research Laboratory (NIARL) designed and implemented flexible mandatory access controls in the major subsystems of the Linux kernel and implemented the new operating system components provided by the Flask architecture, namely the security server and the access vector cache. The NSA researchers reworked the LSM-based SELinux for inclusion in Linux 2.6. NSA has also led the development of similar controls for the X Window System (XACE/XSELinux) and for Xen (XSM/Flask).</em></span> </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Main SELinux website: <a href="http://www.nsa.gov/research/selinux/index.shtml">http://www.nsa.gov/research/selinux/index.shtml</a>. </div></li><li class="listitem"><div class="para"> SELinux documentation: <a href="http://www.nsa.gov/research/selinux/docs.shtml">http://www.nsa.gov/research/selinux/docs.shtml</a>. </div></li><li class="listitem"><div class="para"> SELinux background: <a href="http://www.nsa.gov/research/selinux/background.shtml">http://www.nsa.gov/research/selinux/background.shtml</a>. </div></li></ul></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-Tresys_Technology">Tresys Technology</h5> <a href="http://www.tresys.com/">Tresys Technology</a> are the upstream for: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> <a href="http://userspace.selinuxproject.org/trac/">SELinux userland libraries and tools</a>. </div></li><li class="listitem"><div class="para"> <a href="http://oss.tresys.com/projects/refpolicy">SELinux Reference Policy</a>. </div></li></ul></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-SELinux_News">SELinux News</h5> <div class="itemizedlist"><ul><li class="listitem"><div class="para"> News: <a href="http://selinuxnews.org/wp/">http://selinuxnews.org/wp/</a>. </div></li><li class="listitem"><div class="para"> Planet SELinux (blogs): <a href="http://selinuxnews.org/planet/">http://selinuxnews.org/planet/</a>. </div></li></ul></div> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-SELinux_Project_Wiki">SELinux Project Wiki</h5> <div class="itemizedlist"><ul><li class="listitem"><div class="para"> Main page: <a href="http://selinuxproject.org/page/Main_Page">http://selinuxproject.org/page/Main_Page</a>. </div></li><li class="listitem"><div class="para"> User resources, including links to documentation, mailing lists, websites, and tools: <a href="http://selinuxproject.org/page/User_Resources">http://selinuxproject.org/page/User_Resources</a>. </div></li></ul></div> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-Red_Hat_Enterprise_Linux">Red Hat Enterprise Linux</h5> <div class="itemizedlist"><ul><li class="listitem"><div class="para"> The <a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Deployment_Guide/index.html">Red Hat Enterprise Linux Deployment Guide</a> contains an SELinux <a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Deployment_Guide/selg-chapter-0054.html">References</a> section, that has links to SELinux tutorials, general information, and the technology behind SELinux. </div></li><li class="listitem"><div class="para"> The <a href="http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/selinux-guide/index.html">Red Hat Enterprise Linux 4 SELinux Guide</a>. </div></li></ul></div> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-Fedora">Fedora</h5> <div class="itemizedlist"><ul><li class="listitem"><div class="para"> Main page: <a href="http://fedoraproject.org/wiki/SELinux">http://fedoraproject.org/wiki/SELinux</a>. </div></li><li class="listitem"><div class="para"> Troubleshooting: <a href="http://fedoraproject.org/wiki/SELinux/Troubleshooting">http://fedoraproject.org/wiki/SELinux/Troubleshooting</a>. </div></li><li class="listitem"><div class="para"> Fedora Core 5 SELinux FAQ: <a href="http://docs.fedoraproject.org/selinux-faq-fc5/">http://docs.fedoraproject.org/selinux-faq-fc5/</a>. </div></li><li class="listitem"><div class="para"> SELinux Managing Confined Services Guide: <a href="http://docs.fedoraproject.org/selinux-managing-confined-services-guide/">http://docs.fedoraproject.org/selinux-managing-confined-services-guide/</a> </div></li></ul></div> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-The_UnOfficial_SELinux_FAQ">The UnOfficial SELinux FAQ</h5> <a href="http://www.crypt.gen.nz/selinux/faq.html">http://www.crypt.gen.nz/selinux/faq.html</a> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Further_Information-IRC">IRC</h5> On <a href="http://freenode.net/">Freenode</a>: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> #selinux </div></li><li class="listitem"><div class="para"> #fedora-selinux </div></li><li class="listitem"><div class="para"> #security </div></li></ul></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Further_Information.html"><strong>Prev</strong>Chapter 8. Further Information</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="appe-Security-Enhanced_Linux-Revision_History.html"><strong>Next</strong>Appendix A. Revision History</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Introduction-Examples.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>2.2. Examples</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction"/><link rel="prev" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction"/><link rel="next" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html" title="2.3. SELinux Architecture"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul clas s="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Introduction.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html"><strong>Next</strong></a></li></ul><div class="section" title="2.2. Examples"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Introduction-Examples">2.2. Examples</h2></div></div></div><div class="para"> The following examples demonstrate how SELinux increases security: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> the default action is deny. If an SELinux policy rule does not exist to allow access, such as for a process opening a file, access is denied. </div></li><li class="listitem"><div class="para"> SELinux can confine Linux users. A number of confined SELinux users exist in SELinux policy. Linux users can be mapped to confined SELinux users to take advantage of the security rules and mechanisms applied to them. For example, mapping a Linux user to the SELinux user_u user, results in a Linux user that is not able to run (unless configured otherwise) set user ID (setuid) applications, such as <code class="command">sudo</code> and <code class="command">su</code>, as well as preventing them from executing files and applications in their home directory - if configured, this prevents users from executing malicious files from their home directories. </div></li><li class="listitem"><div class="para"> process separation. Processes run in their own domains, preventing processes from accessing files used by other processes, as well as preventing processes from accessing other processes. For example, when running SELinux, unless otherwise configured, an attacker can not compromise a Samba server, and then use that Samba server as an attack vector to read and write to files used by other processes, such as databases used by <span class="trademark">MySQL</span>®. </div></li><li class="listitem"><div class="para"> it helps limit the damage done by configuration mistakes. <a href="http://en.wikipedia.org/wiki/Domain_Name_System">Domain Name System (DNS)</a> servers often replicate information between each other in what is known as a zone transfer. Attackers can use zone transfers to update DNS servers with false information. When running the <a href="https://www.isc.org/software/bind">Berkeley Internet Name Domain (BIND)</a> as a DNS server in Fedora, even if an administrator forgets to limit which servers can perform a zone transfer, the default SELinux policy prevents zone files <sup>[<a id="d0e645" href="#ftn.d0e645" class="footnote">3</a>]</sup> from being updated via zone transfers, by the BIND <code class="systemitem">named</code> daemon itself, and by other processes. </div></li><li class="listitem"><div class="para"> refer to the <a href="http://www.redhatmagazine.com/"><span class="trademark">Red Hat</span>® Magazine</a> article, <a href="http://www.redhatmagazine.com/2008/02/26/risk-report-three-years-of-red-hat-enterprise-linux-4/">Risk report: Three years of Red Hat Enterprise Linux 4</a><sup>[<a id="d0e662" href="#ftn.d0e662" class="footnote">4</a>]</sup>, for exploits that were restricted due to the default SELinux targeted policy in <span class="trademark">Red Hat</span>® Enterprise <span class="trademark">Linux</span>® 4. </div></li><li class="listitem"><div class="para"> refer to the <a href="http://www.linuxworld.com">LinuxWorld.com</a> article, <a href="http://www.linuxworld.com/news/2008/022408-selinux.html?page=1">A seatbelt for server software: SELinux blocks real-world exploits</a><sup>[<a id="d0e682" href="#ftn.d0e682" class="footnote">5</a>]</sup>, for background information about SELinux, and information about various exploits that SELinux has prevented. </div></li><li class="listitem"><div class="para"> refer to James Morris's <a href="http://james-morris.livejournal.com/25421.html">SELinux mitigates remote root vulnerability in OpenPegasus</a> blog post for information about an exploit in <a href="http://www.openpegasus.org/">OpenPegasus</a> that was mitigated by SELinux as shipped with Red Hat Enterprise Linux 4 and 5. </div></li></ul></div><div class="para"> The <a href="http://www.tresys.com/">Tresys Technology</a> website has an <a href="http://www.tresys.com/innovation.php">SELinux Mitigation News</a> section (on the right-hand side), that lists recent exploits that have been mitigated or prevented by SELinux. </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e645" href="#d0e645" class="para">3</a>] </sup> Text files that include information, such as hostname to IP address mappings, that are used by DNS servers. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e662" href="#d0e662" class="para">4</a>] </sup> Cox, Mark. "Risk report: Three years of Red Hat Enterprise Linux 4". Published 26 February 2008. Accessed 27 August 2009: <a href="http://www.redhatmagazine.com/2008/02/26/risk-report-three-years-of-red-hat-enterprise-linux-4/">http://www.redhatmagazine.com/2008/02/26/risk-report-three-years-of-red-hat-enterprise-linux-4/</a>. </p></div><div class="footnote"><p><sup>[<a id="ftn.d0e682" href="#d0e682" class="para">5</a>] </sup> Marti, Don. "A seatbelt for server software: SELinux blocks real-world exploits". Published 24 February 2008. Accessed 27 August 2009: <a href="http://www.linuxworld.com/news/2008/022408-selinux.html?page=1">http://www.linuxworld.com/news/2008/022408-selinux.html?page=1</a>. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Introduction.html"><strong>Prev</strong>Chapter 2. Introduction</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html"><strong>Next</strong>2.3. SELinux Architecture</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>2.3. SELinux Architecture</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction"/><link rel="prev" href="sect-Security-Enhanced_Linux-Introduction-Examples.html" title="2.2. Examples"/><link rel="next" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html" title="2.4. SELinux on Other Operating Systems"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt= "Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-Examples.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html"><strong>Next</strong></a></li></ul><div class="section" title="2.3. SELinux Architecture"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture">2.3. SELinux Architecture</h2></div></div></div><div class="para"> SELinux is a Linux security module that is built into the Linux kernel. SELinux is driven by loadable policy rules. When security-relevant access is taking place, such as when a process attempts to open a file, the operation is intercepted in the kernel by SELinux. If an SELinux policy rule allows the operation, it continues, otherwise, the operation is blocked and the process receives an error. </div><div class="para"> SELinux decisions, such as allowing or disallowing access, are cached. This cache is known as the Access Vector Cache (AVC). Caching decisions decreases how often SELinux policy rules need to be checked, which increases performance. Remember that SELinux policy rules have no effect if DAC rules deny access first. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-Examples.html"><strong>Prev</strong>2.2. Examples</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html"><strong>Next</strong>2.4. SELinux on Other Operating Systems</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>2.4. SELinux on Other Operating Systems</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction"/><link rel="prev" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html" title="2.3. SELinux Architecture"/><link rel="next" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html" title="Chapter 3. SELinux Contexts"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Doc umentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html"><strong>Next</strong></a></li></ul><div class="section" title="2.4. SELinux on Other Operating Systems"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Introduction-SELinux_on_Other_Operating_Systems">2.4. SELinux on Other Operating Systems</h2></div></div></div><div class="para"> Refer to the following for information about running SELinux on operating systems: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Hardened Gentoo: <a href="http://www.gentoo.org/proj/en/hardened/selinux/selinux-handbook.xml">http://www.gentoo.org/proj/en/hardened/selinux/selinux-handbook.xml</a>. </div></li><li class="listitem"><div class="para"> Debian: <a href="http://wiki.debian.org/SELinux">http://wiki.debian.org/SELinux</a>. </div></li><li class="listitem"><div class="para"> Ubuntu: <a href="https://wiki.ubuntu.com/SELinux">https://wiki.ubuntu.com/SELinux</a> and <a href="https://help.ubuntu.com/community/SELinux">https://help.ubuntu.com/community/SELinux</a>. </div></li><li class="listitem"><div class="para"> Red Hat Enterprise Linux: <a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Deployment_Guide/selg-overview.html">Red Hat Enterprise Linux Deployment Guide</a> and <a href="http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/selinux-guide/">Red Hat Enterprise Linux 4 SELinux Guide</a>. </div></li><li class="listitem"><div class="para"> Fedora: <a href="http://fedoraproject.org/wiki/SELinux">http://fedoraproject.org/wiki/SELinux</a> and the <a href="http://docs.fedoraproject.org/selinux-faq-fc5/">Fedora Core 5 SELinux FAQ</a>. </div></li></ul></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Introduction-SELinux_Architecture.html"><strong>Prev</strong>2.3. SELinux Architecture</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html"><strong>Next</strong>Chapter 3. SELinux Contexts</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.10.5. Archiving Files with star</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/><link rel="prev" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html" title="5.10.4. Archiving Files with tar"/><link rel="next" href="chap-Security-Enhanced_Linux-Confining_Users.html" title="Chapter 6. Confining Users"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject. org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Confining_Users.html"><strong>Next</strong></a></li></ul><div class="section" title="5.10.5. Archiving Files with star"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star">5.10.5. Archiving Files with star</h3></div></div></div><div class="para"> <code class="command">star</code> does not retain extended attributes by default. Since SELinux contexts are stored in extended attributes, contexts can be lost when archiving files. Use <code class="command">star -xattr -H=exustar</code> to create archives that retain contexts. The <span class="package">star</span> package is not installed by default. To install <code class="command">star</code>, run the <code class="command">yum install star</code> command as the Linux root user. </div><div class="para"> The following example demonstrates creating a Star archive that retains SELinux contexts: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /var/www/html/file{1,2,3}</code> command to create three files (<code class="filename">file1</code>, <code class="filename">file2</code>, and <code class="filename">file3</code>). These files inherit the <code class="computeroutput">httpd_sys_content_t</code> type from the <code class="filename">/var/www/html/</code> directory: </div><pre class="screen"> # touch /var/www/html/file{1,2,3} # ls -Z /var/www/html/ -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file3 </pre></li><li class="listitem"><div class="para"> Run the <code class="command">cd /var/www/html/</code> command to change into the <code class="filename">/var/www/html/</code> directory. Once in this directory, as the Linux root user, run the <code class="command">star -xattr -H=exustar -c -f=test.star file{1,2,3}</code> command to create a Star archive named <code class="filename">test.star</code>: </div><pre class="screen"> # star -xattr -H=exustar -c -f=test.star file{1,2,3} star: 1 blocks + 0 bytes (total of 10240 bytes = 10.00k). </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mkdir /test</code> command to create a new directory, and then, run the <code class="command">chmod 777 /test/</code> command to allow all users full-access to the <code class="filename">/test/</code> directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">cp /var/www/html/test.star /test/</code> command to copy the <code class="filename">test.star</code> file in to the <code class="filename">/test/</code> directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">cd /test/</code> command to change into the <code class="filename">/test/</code> directory. Once in this directory, run the <code class="command">star -x -f=test.star</code> command to extract the Star archive: </div><pre class="screen"> $ star -x -f=test.star star: 1 blocks + 0 bytes (total of 10240 bytes = 10.00k). </pre></li><li class="listitem"><div class="para"> Run the <code class="command">ls -lZ /test/</code> command to view the SELinux contexts. The <code class="computeroutput">httpd_sys_content_t</code> type has been retained, rather than being changed to <code class="computeroutput">default_t</code>, which would have happened had the <code class="option">--selinux</code> not been used: </div><pre class="screen"> $ ls -lZ /test/ -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file3 -rw-r--r-- user1 group1 unconfined_u:object_r:default_t:s0 test.star </pre></li><li class="listitem"><div class="para"> If the <code class="filename">/test/</code> directory is no longer required, as the Linux root user, run the <code class="command"> rm -ri /test/</code> command to remove it, as well as all files in it. </div></li><li class="listitem"><div class="para"> If <code class="command">star</code> is no longer required, as the Linux root user, run the <code class="command">yum remove star</code> command to remove the package. </div></li></ol></div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">star</span>(1)</span> manual page for further information about <code class="command">star</code>. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html"><strong>Prev</strong>5.10.4. Archiving Files with tar</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Confining_Users.html"><strong>Next</strong>Chapter 6. Confining Users</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.10.4. Archiving Files with tar</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/><link rel="prev" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html" title="5.10.3. Checking the Default SELinux Context"/><link rel="next" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html" title="5.10.5. Archiving Files with star"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="P roduct Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html"><strong>Next</strong></a></li></ul><div class="section" title="5.10.4. Archiving Files with tar"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar">5.10.4. Archiving Files with tar</h3></div></div></div><div class="para"> <code class="command">tar</code> does not retain extended attributes by default. Since SELinux contexts are stored in extended attributes, contexts can be lost when archiving files. Use <code class="command">tar --selinux</code> to create archives that retain contexts. If a Tar archive contains files without extended attributes, or if you want the extended attributes to match the system defaults, run the archive through <code class="command">/sbin/restorecon</code>: </div><pre class="screen"> $ tar -xvf <em class="replaceable"><code>archive.tar</code></em> | /sbin/restorecon -f - </pre><div class="para"> Note: depending on the directory, you may need to be the Linux root user to run the <code class="command">/sbin/restorecon</code> command. </div><div class="para"> The following example demonstrates creating a Tar archive that retains SELinux contexts: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /var/www/html/file{1,2,3}</code> command to create three files (<code class="filename">file1</code>, <code class="filename">file2</code>, and <code class="filename">file3</code>). These files inherit the <code class="computeroutput">httpd_sys_content_t</code> type from the <code class="filename">/var/www/html/</code> directory: </div><pre class="screen"> # touch /var/www/html/file{1,2,3} # ls -Z /var/www/html/ -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file3 </pre></li><li class="listitem"><div class="para"> Run the <code class="command">cd /var/www/html/</code> command to change into the <code class="filename">/var/www/html/</code> directory. Once in this directory, as the Linux root user, run the <code class="command">tar --selinux -cf test.tar file{1,2,3}</code> command to create a Tar archive named <code class="filename">test.tar</code>. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mkdir /test</code> command to create a new directory, and then, run the <code class="command">chmod 777 /test/</code> command to allow all users full-access to the <code class="filename">/test/</code> directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">cp /var/www/html/test.tar /test/</code> command to copy the <code class="filename">test.tar</code> file in to the <code class="filename">/test/</code> directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">cd /test/</code> command to change into the <code class="filename">/test/</code> directory. Once in this directory, run the <code class="command">tar -xvf test.tar</code> command to extract the Tar archive. </div></li><li class="listitem"><div class="para"> Run the <code class="command">ls -lZ /test/</code> command to view the SELinux contexts. The <code class="computeroutput">httpd_sys_content_t</code> type has been retained, rather than being changed to <code class="computeroutput">default_t</code>, which would have happened had the <code class="option">--selinux</code> not been used: </div><pre class="screen"> $ ls -lZ /test/ -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- user1 group1 unconfined_u:object_r:httpd_sys_content_t:s0 file3 -rw-r--r-- user1 group1 unconfined_u:object_r:default_t:s0 test.tar </pre></li><li class="listitem"><div class="para"> If the <code class="filename">/test/</code> directory is no longer required, as the Linux root user, run the <code class="command"> rm -ri /test/</code> command to remove it, as well as all files in it. </div></li></ol></div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">tar</span>(1)</span> manual page for further information about <code class="command">tar</code>, such as the <code class="option">--xattrs</code> option that retains all extended attributes. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html"><strong>Prev</strong>5.10.3. Checking the Default SELinux Context</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_star.html"><strong>Next</strong>5.10.5. Archiving Files with star</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.10.3. Checking the Default SELinux Context</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/><link rel="prev" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html" title="5.10.2. Moving Files and Directories"/><link rel="next" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html" title="5.10.4. Archiving Files with tar"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html"><strong>Next</strong></a></li></ul><div class="section" title="5.10.3. Checking the Default SELinux Context"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context">5.10.3. Checking the Default SELinux Context</h3></div></div></div><div class="para"> Use the <code class="command">/usr/sbin/matchpathcon</code> command to check if files and directories have the correct SELinux context. From the <span class="citerefentry"><span class="refentrytitle">matchpathcon</span>(8)</span> manual page: "<code class="command">matchpathcon</code> queries the system policy and outputs the default security context associated with the file path."<sup>[<a id="d0e4374" href="#ftn.d0e4374" class="footnote">13</a>]</sup>. The following example demonstrates using the <code class="command">/usr/sbin/matchpathcon</code> command to verify that files in <code class="filename">/var/www/html/</code> directory are labeled correctly: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /var/www/html/file{1,2,3}</code> command to create three files (<code class="filename">file1</code>, <code class="filename">file2</code>, and <code class="filename">file3</code>). These files inherit the <code class="computeroutput">httpd_sys_content_t</code> type from the <code class="filename">/var/www/html/</code> directory: </div><pre class="screen"># touch /var/www/html/file{1,2,3} # ls -Z /var/www/html/ -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file3 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">chcon -t samba_share_t /var/www/html/file1</code> command to change the <code class="filename">file1</code> type to <code class="computeroutput">samba_share_t</code>. Note: the Apache HTTP Server can not read files or directories labeled with the <code class="computeroutput">samba_share_t</code> type. </div></li><li class="listitem"><div class="para"> The <code class="command">/usr/sbin/matchpathcon</code> <code class="option">-V</code> option compares the current SELinux context to the correct, default context in SELinux policy. Run the <code class="command">/usr/sbin/matchpathcon -V /var/www/html/*</code> command to check all files in the <code class="filename">/var/www/html/</code> directory: </div><pre class="screen">$ /usr/sbin/matchpathcon -V /var/www/html/* /var/www/html/file1 has context unconfined_u:object_r:samba_share_t:s0, should be system_u:object_r:httpd_sys_content_t:s0 /var/www/html/file2 verified. /var/www/html/file3 verified. </pre></li></ol></div><div class="para"> The following output from the <code class="command">/usr/sbin/matchpathcon</code> command explains that <code class="filename">file1</code> is labeled with the <code class="computeroutput">samba_share_t</code> type, but should be labeled with the <code class="computeroutput">httpd_sys_content_t</code> type: </div><pre class="screen">/var/www/html/file1 has context unconfined_u:object_r:samba_share_t:s0, should be system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> To resolve the label problem and allow the Apache HTTP Server access to <code class="filename">file1</code>, as the Linux root user, run the <code class="command">/sbin/restorecon -v /var/www/html/file1</code> command: </div><pre class="screen"># /sbin/restorecon -v /var/www/html/file1 restorecon reset /var/www/html/file1 context unconfined_u:object_r:samba_share_t:s0->system_u:object_r:httpd_sys_content_t:s0 </pre><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e4374" href="#d0e4374" class="para">13</a>] </sup> The <span class="citerefentry"><span class="refentrytitle">matchpathcon</span>(8)</span> manual page, as shipped with the <span class="package">libselinux-utils</span> package in Fedora, is written by Daniel Walsh. Any edits or changes in this version were done by Murray McAllister. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html"><strong>Prev</strong>5.10.2. Moving Files and Directories</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Archiving_Files_with_tar.html"><strong>Next</strong>5.10.4. Archiving Files with tar</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.10.2. Moving Files and Directories</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/><link rel="next" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html" title="5.10.3. Checking the Default SELinux Context"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Pro duct Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html"><strong>Next</strong></a></li></ul><div class="section" title="5.10.2. Moving Files and Directories"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories">5.10.2. Moving Files and Directories</h3></div></div></div><div class="para"> File and directories keep their current SELinux context when they are moved. In many cases, this is incorrect for the location they are being moved to. The following example demonstrates moving a file from a user's home directory to <code class="filename">/var/www/html/</code>, which is used by the Apache HTTP Server. Since the file is moved, it does not inherit the correct SELinux context: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Run the <code class="command">cd</code> command without any arguments to change into your home directory. Once in your home directory, run the <code class="command">touch file1</code> command to create a file. This file is labeled with the <code class="computeroutput">user_home_t</code> type: </div><pre class="screen">$ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre></li><li class="listitem"><div class="para"> Run the <code class="command">ls -dZ /var/www/html/</code> command to view the SELinux context of the <code class="filename">/var/www/html/</code> directory: </div><pre class="screen">$ ls -dZ /var/www/html/ drwxr-xr-x root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/ </pre><div class="para"> By default, the <code class="filename">/var/www/html/</code> directory is labeled with the <code class="computeroutput">httpd_sys_content_t</code> type. Files and directories created under the <code class="filename">/var/www/html/</code> directory inherit this type, and as such, they are labeled with this type. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mv file1 /var/www/html/</code> command to move <code class="filename">file1</code> to the <code class="filename">/var/www/html/</code> directory. Since this file is moved, it keeps its current <code class="computeroutput">user_home_t</code> type: </div><pre class="screen"># mv file1 /var/www/html/ # ls -Z /var/www/html/file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 /var/www/html/file1 </pre></li></ol></div><div class="para"> By default, the Apache HTTP Server can not read files that are labeled with the <code class="computeroutput">user_home_t</code> type. If all files comprising a web page are labeled with the <code class="computeroutput">user_home_t</code> type, or another type that the Apache HTTP Server can not read, permission is denied when attempting to access them via Firefox or text-based Web browsers. </div><div class="important"><h2>Important</h2><div class="para"> Moving files and directories with the <code class="command">mv</code> command may result in the wrong SELinux context, preventing processes, such as the Apache HTTP Server and Samba, from accessing such files and directories. </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html"><strong>Prev</strong>5.10. Maintaining SELinux Labels </a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html"><strong>Next</strong>5.10.3. Checking the Default SELinux Context</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.9.2. Changing the Default Context</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/><link rel="next" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html" title="5.9.3. Mounting an NFS File System"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs .fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html"><strong>Next</strong></a></li></ul><div class="section" title="5.9.2. Changing the Default Context"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context">5.9.2. Changing the Default Context</h3></div></div></div><div class="para"> As mentioned in <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html" title="5.8. The file_t and default_t Types">Section 5.8, “The file_t and default_t Types”</a>, on file systems that support extended attributes, when a file that lacks an SELinux context on disk is accessed, it is treated as if it had a default context as defined by SELinux policy. In common policies, this default context uses the <code class="computeroutput">file_t</code> type. If it is desirable to use a different default context, mount the file system with the <code class="option">defcontext</code> option. </div><div class="para"> The following example mounts a newly-created file system (on <code class="filename">/dev/sda2</code>) to the newly-created <code class="filename">/test/</code> directory. It assumes that there are no rules in <code class="filename">/etc/selinux/targeted/contexts/files/</code> that define a context for the <code class="filename">/test/</code> directory: </div><pre class="screen"> # mount /dev/sda2 /test/ -o defcontext="system_u:object_r:samba_share_t:s0" </pre><div class="para"> In this example: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> the <code class="option">defcontext</code> option defines that <code class="computeroutput">system_u:object_r:samba_share_t:s0</code> is "the default security context for unlabeled files"<sup>[<a id="d0e3923" href="#ftn.d0e3923" class="footnote">12</a>]</sup>. </div></li><li class="listitem"><div class="para"> when mounted, the root directory (<code class="filename">/test/</code>) of the file system is treated as if it is labeled with the context specified by <code class="option">defcontext</code> (this label is not stored on disk). This affects the labeling for files created under <code class="filename">/test/</code>: new files inherit the <code class="computeroutput">samba_share_t</code> type, and these labels are stored on disk. </div></li><li class="listitem"><div class="para"> files created under <code class="filename">/test/</code> while the file system was mounted with a <code class="option">defcontext</code> option retain their labels. </div></li></ul></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e3923" href="#d0e3923" class="para">12</a>] </sup> Morris, James. "Filesystem Labeling in SELinux". Published 1 October 2004. Accessed 14 October 2008: <a href="http://www.linuxjournal.com/article/7426">http://www.linuxjournal.com/article/7426</a>. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html"><strong>Prev</strong>5.9. Mounting File Systems</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html"><strong>Next</strong>5.9.3. Mounting an NFS File System</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.9.5. Making Context Mounts Persistent</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html" title="5.9.4. Multiple NFS Mounts"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html" title="5.10. Maintaining SELinux Labels"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs .fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html"><strong>Next</strong></a></li></ul><div class="section" title="5.9.5. Making Context Mounts Persistent"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent">5.9.5. Making Context Mounts Persistent</h3></div></div></div><div class="para"> To make context mounts persistent across remounting and reboots, add entries for the file systems in <code class="filename">/etc/fstab</code> or an automounter map, and use the desired context as a mount option. The following example adds an entry to <code class="filename">/etc/fstab</code> for an NFS context mount: </div><pre class="screen"> server:/export /local/mount/ nfs context="system_u:object_r:httpd_sys_content_t:s0" 0 0 </pre><div class="para"> Refer to the <a href="http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Deployment_Guide/s1-nfs-client-config.html">Red Hat Enterprise Linux 5 Deployment Guide, Section 19.2. "NFS Client Configuration"</a> for information about mounting NFS file systems. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html"><strong>Prev</strong>5.9.4. Multiple NFS Mounts</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html"><strong>Next</strong>5.10. Maintaining SELinux Labels </a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.9.3. Mounting an NFS File System</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html" title="5.9.2. Changing the Default Context"/><link rel="next" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html" title="5.9.4. Multiple NFS Mounts"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs .fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html"><strong>Next</strong></a></li></ul><div class="section" title="5.9.3. Mounting an NFS File System"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System">5.9.3. Mounting an NFS File System</h3></div></div></div><div class="para"> By default, NFS mounts on the client side are labeled with a default context defined by policy for NFS file systems. In common policies, this default context uses the <code class="computeroutput">nfs_t</code> type. Depending on policy configuration, services, such as Apache HTTP Server and MySQL, may not be able to read files labeled with the <code class="computeroutput">nfs_t</code> type. This may prevent file systems labeled with this type from being mounted and then read or exported by other services. </div><div class="para"> If you would like to mount an NFS file system and read or export that file system with another service, use the <code class="option">context</code> option when mounting to override the <code class="computeroutput">nfs_t</code> type. Use the following context option to mount NFS file systems so that they can be shared via the Apache HTTP Server: </div><pre class="screen">mount server:/export /local/mount/point -o\ context="system_u:object_r:httpd_sys_content_t:s0" </pre><div class="para"> Since context changes are not written to disk for these situations, the context specified with the <code class="option">context</code> option is only retained if the <code class="option">context</code> option is used on the next mount, and if the same context is specified. </div><div class="para"> As an alternative to mounting file systems with <code class="option">context</code> options, Booleans can be turned on to allow services access to file systems labeled with the <code class="computeroutput">nfs_t</code> type. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html" title="5.6.3. Booleans for NFS and CIFS">Section 5.6.3, “Booleans for NFS and CIFS”</a> for instructions on configuring Booleans to allow services access to the <code class="computeroutput">nfs_t</code> type. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html"><strong>Prev</strong>5.9.2. Changing the Default Context</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html"><strong>Next</strong>5.9.4. Multiple NFS Mounts</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.9.4. Multiple NFS Mounts</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html" title="5.9.3. Mounting an NFS File System"/><link rel="next" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html" title="5.9.5. Making Context Mounts Persistent"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" h ref="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html"><strong>Next</strong></a></li></ul><div class="section" title="5.9.4. Multiple NFS Mounts"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Mounting_File_Systems-Multiple_NFS_Mounts">5.9.4. Multiple NFS Mounts</h3></div></div></div><div class="para"> When mounting multiple mounts from the same NFS export, attempting to override the SELinux context of each mount with a different context, results in subsequent mount commands failing. In the following example, the NFS server has a single export, <code class="filename">/export</code>, which has two subdirectories, <code class="filename">web/</code> and <code class="filename">database/</code>. The following commands attempt two mounts from a single NFS export, and try to override the context for each one: </div><pre class="screen"> # mount server:/export/web /local/web -o\ context="system_u:object_r:httpd_sys_content_t:s0"
# mount server:/export/database /local/database -o\ context="system_u:object_r:mysqld_db_t:s0" </pre><div class="para"> The second mount command fails, and the following is logged to <code class="filename">/var/log/messages</code>: </div><pre class="screen"> kernel: SELinux: mount invalid. Same superblock, different security settings for (dev 0:15, type nfs) </pre><div class="para"> To mount multiple mounts from a single NFS export, with each mount having a different context, use the <code class="option">-o nosharecache,context</code> options. The following example mounts multiple mounts from a single NFS export, with a different context for each mount (allowing a single service access to each one): </div><pre class="screen"> # mount server:/export/web /local/web -o\ nosharecache,context="system_u:object_r:httpd_sys_content_t:s0"
# mount server:/export/database /local/database -o\ nosharecache,context="system_u:object_r:mysqld_db_t:s0" </pre><div class="para"> In this example, <code class="computeroutput">server:/export/web</code> is mounted locally to <code class="filename">/local/web/</code>, with all files being labeled with the <code class="computeroutput">httpd_sys_content_t</code> type, allowing Apache HTTP Server access. <code class="computeroutput">server:/export/database</code> is mounted locally to <code class="filename">/local/database</code>, with all files being labeled with the <code class="computeroutput">mysqld_db_t</code> type, allowing MySQL access. These type changes are not written to disk. </div><div class="important"><h2>Important</h2><div class="para"> The <code class="option">nosharecache</code> options allows you to mount the same subdirectory of an export multiple times with different contexts (for example, mounting <code class="filename">/export/web</code> multiple times). Do not mount the same subdirectory from an export multiple times with different contexts, as this creates an overlapping mount, where files are accessible under two different contexts. </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Mounting_an_NFS_File_System.html"><strong>Prev</strong>5.9.3. Mounting an NFS File System</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html"><strong>Next</strong>5.9.5. Making Context Mounts Persistent</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3.4.2. Denials for Permissive Domains</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html" title="7.3.4. Permissive Domains"/><link rel="prev" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html" title="7.3.4. Permissive Domains"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html" title="7.3.5. Searching For and Viewing Denials"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedorap roject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3.4.2. Denials for Permissive Domains"><div class="titlepage"><div><div><h4 class="title" id="sect-Security-Enhanced_Linux-Permissive_Domains-Denials_for_Permissive_Domains">7.3.4.2. Denials for Permissive Domains</h4></div></div></div><div class="para"> The <code class="computeroutput">SYSCALL</code> message is different for permissive domains. The following is an example AVC denial (and the associated system call) from the Apache HTTP Server: </div><pre class="screen"> type=AVC msg=audit(1226882736.442:86): avc: denied { getattr } for pid=2427 comm="httpd" path="/var/www/html/file1" dev=dm-0 ino=284133 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file type=SYSCALL msg=audit(1226882736.442:86): arch=40000003 syscall=196 success=no exit=-13 a0=b9a1e198 a1=bfc2921c a2=54dff4 a3=2008171 items=0 ppid=2425 pid=2427 auid=502 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=4 comm="httpd" exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null) </pre><div class="para"> By default, the <code class="computeroutput">httpd_t</code> domain is not permissive, and as such, the action is denied, and the <code class="computeroutput">SYSCALL</code> message contains <code class="computeroutput">success=no</code>. The following is an example AVC denial for the same situation, except the <code class="command">semanage permissive -a httpd_t</code> command has been run to make the <code class="computeroutput">httpd_t</code> domain permissive: </div><pre class="screen"> type=AVC msg=audit(1226882925.714:136): avc: denied { read } for pid=2512 comm="httpd" name="file1" dev=dm-0 ino=284133 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file type=SYSCALL msg=audit(1226882925.714:136): arch=40000003 syscall=5 success=yes exit=11 a0=b962a1e8 a1=8000 a2=0 a3=8000 items=0 ppid=2511 pid=2512 auid=502 uid=48 gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=4 comm="httpd" exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null) </pre><div class="para"> In this case, although an AVC denial was logged, access was not denied, as shown by <code class="computeroutput">success=yes</code> in the <code class="computeroutput">SYSCALL</code> message. </div><div class="para"> Refer to Dan Walsh's <a href="http://danwalsh.livejournal.com/24537.html">"Permissive Domains"</a> blog entry for further information about permissive domains. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Fixing_Problems-Permissive_Domains.html"><strong>Prev</strong>7.3.4. Permissive Domains</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Searching_For_and_Viewing_Denials.html"><strong>Next</strong>7.3.5. Searching For and Viewing Denials</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>3.2. SELinux Contexts for Processes</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html" title="Chapter 3. SELinux Contexts"/><link rel="prev" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html" title="Chapter 3. SELinux Contexts"/><link rel="next" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html" title="3.3. SELinux Contexts for Users"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image _right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html"><strong>Next</strong></a></li></ul><div class="section" title="3.2. SELinux Contexts for Processes"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes">3.2. SELinux Contexts for Processes</h2></div></div></div><div class="para"> Use the <code class="command">ps -eZ</code> command to view the SELinux context for processes. For example: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Open a terminal, such as <span class="guimenu"><strong>Applications</strong></span> → <span class="guisubmenu"><strong>System Tools</strong></span> → <span class="guimenuitem"><strong>Terminal</strong></span>. </div></li><li class="listitem"><div class="para"> Run the <code class="command">/usr/bin/passwd</code> command. Do not enter a new password. </div></li><li class="listitem"><div class="para"> Open a new tab, or another terminal, and run the <code class="command">ps -eZ | grep passwd</code> command. The output is similar to the following: </div><pre class="screen">unconfined_u:unconfined_r:passwd_t:s0-s0:c0.c1023 13212 pts/1 00:00:00 passwd </pre></li><li class="listitem"><div class="para"> In the first tab/terminal, press <strong class="userinput"><code>Ctrl+C</code></strong> to cancel the <span class="application"><strong>passwd</strong></span> application. </div></li></ol></div><div class="para"> In this example, when the <code class="filename">/usr/bin/passwd</code> application (labeled with the <code class="computeroutput">passwd_exec_t</code> type) is executed, the user's shell process transitions to the <code class="computeroutput">passwd_t</code> domain. Remember: the type defines a domain for processes, and a type for files. </div><div class="para"> Use the <code class="command">ps -eZ</code> command to view the SELinux contexts for running processes. The following is a limited example of the output, and may differ on your system: </div><pre class="screen">system_u:system_r:setroubleshootd_t:s0 1866 ? 00:00:08 setroubleshootd system_u:system_r:dhcpc_t:s0 1869 ? 00:00:00 dhclient system_u:system_r:sshd_t:s0-s0:c0.c1023 1882 ? 00:00:00 sshd system_u:system_r:gpm_t:s0 1964 ? 00:00:00 gpm system_u:system_r:crond_t:s0-s0:c0.c1023 1973 ? 00:00:00 crond system_u:system_r:kerneloops_t:s0 1983 ? 00:00:05 kerneloops system_u:system_r:crond_t:s0-s0:c0.c1023 1991 ? 00:00:00 atd </pre><div class="para"> The <code class="computeroutput">system_r</code> role is used for system processes, such as daemons. Type Enforcement then separates each domain. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html"><strong>Prev</strong>Chapter 3. SELinux Contexts</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html"><strong>Next</strong>3.3. SELinux Contexts for Users</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>3.3. SELinux Contexts for Users</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html" title="Chapter 3. SELinux Contexts"/><link rel="prev" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html" title="3.2. SELinux Contexts for Processes"/><link rel="next" href="chap-Security-Enhanced_Linux-Targeted_Policy.html" title="Chapter 4. Targeted Policy"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/ima ge_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Targeted_Policy.html"><strong>Next</strong></a></li></ul><div class="section" title="3.3. SELinux Contexts for Users"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Users">3.3. SELinux Contexts for Users</h2></div></div></div><div class="para"> Use the <code class="command">id -Z</code> command to view the SELinux context associated with your Linux user: </div><pre class="screen">unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 </pre><div class="para"> In Fedora, Linux users run unconfined by default. This SELinux context shows that the Linux user is mapped to the SELinux <code class="computeroutput">unconfined_u</code> user, running as the <code class="computeroutput">unconfined_r</code> role, and is running in the <code class="computeroutput">unconfined_t</code> domain. <code class="computeroutput">s0-s0</code> is an MLS range, which in this case, is the same as just <code class="computeroutput">s0</code>. The categories the user has access to is defined by <code class="computeroutput">c0.c1023</code>, which is all categories (<code class="computeroutput">c0</code> through to <code class="computeroutput">c1023</code>). </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts-SELinux_Contexts_for_Processes.html"><strong>Prev</strong>3.2. SELinux Contexts for Processes</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Targeted_Policy.html"><strong>Next</strong>Chapter 4. Targeted Policy</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.7.2. Persistent Changes: semanage fcontext</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html" title="5.7. SELinux Contexts - Labeling Files"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html" title="5.7. SELinux Contexts - Labeling Files"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html" title="5.8. The file_t and default_t Types"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" al t="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html"><strong>Next</strong></a></li></ul><div class="section" title="5.7.2. Persistent Changes: semanage fcontext"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext">5.7.2. Persistent Changes: semanage fcontext</h3></div></div></div><div class="para"> The <code class="command">/usr/sbin/semanage fcontext</code> command changes the SELinux context for files. When using targeted policy, changes made with this command are added to the <code class="filename">/etc/selinux/targeted/contexts/files/file_contexts</code> file if the changes are to files that exists in <code class="filename">file_contexts</code>, or are added to <code class="filename">file_contexts.local</code> for new files and directories, such as creating a <code class="filename">/web/</code> directory. <code class="command">setfiles</code>, which is used when a file system is relabeled, and <code class="command">/sbin/restorecon</code>, which restores the default SELinux contexts, read these files. This means that changes made by <code class="command">/usr/sbin/semanage fcontext</code> are persistent, even if the file system is relabeled. SELinux policy controls whether users are able to modify the SELinux context for any given file. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Persistent_Changes_semanage_fcontext-Quick_Reference">Quick Reference</h5> To make SELinux context changes that survive a file system relabel: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Run the <code class="command">/usr/sbin/semanage fcontext -a <em class="replaceable"><code>options</code></em> <em class="replaceable"><code>file-name</code></em>|<em class="replaceable"><code>directory-name</code></em></code> command, remembering to use the full path to the file or directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">/sbin/restorecon -v <em class="replaceable"><code>file-name</code></em>|<em class="replaceable"><code>directory-name</code></em></code> command to apply the context changes. </div></li></ol></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Persistent_Changes_semanage_fcontext-Changing_a_Files_Type">Changing a File's Type</h5> The following example demonstrates changing a file's type, and no other attributes of the SELinux context: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /etc/file1</code> command to create a new file. By default, newly-created files in the <code class="filename">/etc/</code> directory are labeled with the <code class="computeroutput">etc_t</code> type: </div><pre class="screen"># ls -Z /etc/file1 -rw-r--r-- root root unconfined_u:object_r:etc_t:s0 /etc/file1 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -a -t samba_share_t /etc/file1</code> command to change the <code class="filename">file1</code> type to <code class="computeroutput">samba_share_t</code>. The <code class="option">-a</code> option adds a new record, and the <code class="option">-t</code> option defines a type (<code class="computeroutput">samba_share_t</code>). Note: running this command does not directly change the type - <code class="filename">file1</code> is still labeled with the <code class="computeroutput">etc_t</code> type: </div><pre class="screen"># /usr/sbin/semanage fcontext -a -t samba_share_t /etc/file1 # ls -Z /etc/file1 -rw-r--r-- root root unconfined_u:object_r:etc_t:s0 /etc/file1 </pre><div class="para"> The <code class="command">/usr/sbin/semanage fcontext -a -t samba_share_t /etc/file1</code> command adds the following entry to <code class="filename">/etc/selinux/targeted/contexts/files/file_contexts.local</code>: </div><pre class="screen">/etc/file1 unconfined_u:object_r:samba_share_t:s0 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -v /etc/file1</code> command to change the type. Since the <code class="command">semanage</code> command added an entry to <code class="filename">file.contexts.local</code> for <code class="filename">/etc/file1</code>, the <code class="command">/sbin/restorecon</code> command changes the type to <code class="computeroutput">samba_share_t</code>: </div><pre class="screen"># /sbin/restorecon -v /etc/file1 restorecon reset /etc/file1 context unconfined_u:object_r:etc_t:s0->system_u:object_r:samba_share_t:s0 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">rm -i /etc/file1</code> command to remove <code class="filename">file1</code>. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -d /etc/file1</code> command to remove the context added for <code class="filename">/etc/file1</code>. When the context is removed, running <code class="command">restorecon</code> changes the type to <code class="computeroutput">etc_t</code>, rather than <code class="computeroutput">samba_share_t</code>. </div></li></ol></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Persistent_Changes_semanage_fcontext-Changing_a_Directorys_Type">Changing a Directory's Type</h5> The following example demonstrates creating a new directory and changing that directory's file type, to a type used by Apache HTTP Server: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mkdir /web</code> command to create a new directory. This directory is labeled with the <code class="computeroutput">default_t</code> type: </div><pre class="screen"># ls -dZ /web drwxr-xr-x root root unconfined_u:object_r:default_t:s0 /web </pre><div class="para"> The <code class="command">ls</code> <code class="option">-d</code> option makes <code class="command">ls</code> list information about a directory, rather than its contents, and the <code class="option">-Z</code> option makes <code class="command">ls</code> display the SELinux context (in this example, <code class="computeroutput">unconfined_u:object_r:default_t:s0</code>). </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -a -t httpd_sys_content_t /web</code> command to change the <code class="filename">/web/</code> type to <code class="computeroutput">httpd_sys_content_t</code>. The <code class="option">-a</code> option adds a new record, and the <code class="option">-t</code> option defines a type (<code class="computeroutput">httpd_sys_content_t</code>). Note: running this command does not directly change the type - <code class="filename">/web/</code> is still labeled with the <code class="computeroutput">default_t</code> type: </div><pre class="screen"># /usr/sbin/semanage fcontext -a -t httpd_sys_content_t /web # ls -dZ /web drwxr-xr-x root root unconfined_u:object_r:default_t:s0 /web </pre><div class="para"> The <code class="command">/usr/sbin/semanage fcontext -a -t httpd_sys_content_t /web</code> command adds the following entry to <code class="command">/etc/selinux/targeted/contexts/files/file_contexts.local</code>: </div><pre class="screen">/web unconfined_u:object_r:httpd_sys_content_t:s0 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -v /web</code> command to change the type. Since the <code class="command">semanage</code> command added an entry to <code class="filename">file.contexts.local</code> for <code class="filename">/web</code>, the <code class="command">/sbin/restorecon</code> command changes the type to <code class="computeroutput">httpd_sys_content_t</code>: </div><pre class="screen"># /sbin/restorecon -v /web restorecon reset /web context unconfined_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> By default, newly-created files and directories inherit the SELinux type of their parent folders. When using this example, and before removing the SELinux context added for <code class="filename">/web/</code>, files and directories created in the <code class="filename">/web/</code> directory are labeled with the <code class="computeroutput">httpd_sys_content_t</code> type. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -d /web</code> command to remove the context added for <code class="filename">/web/</code>. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -v /web</code> command to restore the default SELinux context. </div></li></ol></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Persistent_Changes_semanage_fcontext-Changing_a_Directory_and_its_Contents_Types">Changing a Directory and its Contents Types</h5> The following example demonstrates creating a new directory, and changing the directory's file type (along with its contents) to a type used by Apache HTTP Server. The configuration in this example is used if you want Apache HTTP Server to use a different document root (instead of <code class="filename">/var/www/html/</code>): </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mkdir /web</code> command to create a new directory, and then the <code class="command">touch /web/file{1,2,3}</code> command to create 3 empty files (<code class="filename">file1</code>, <code class="filename">file2</code>, and <code class="filename">file3</code>). The <code class="filename">/web/</code> directory and files in it are labeled with the <code class="computeroutput">default_t</code> type: </div><pre class="screen"># ls -dZ /web drwxr-xr-x root root unconfined_u:object_r:default_t:s0 /web # ls -lZ /web -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file3 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -a -t httpd_sys_content_t "/web(/.*)?"</code> command to change the type of the <code class="filename">/web/</code> directory and the files in it, to <code class="computeroutput">httpd_sys_content_t</code>. The <code class="option">-a</code> option adds a new record, and the <code class="option">-t</code> option defines a type (httpd_sys_content_t). The <code class="computeroutput">"/web(/.*)?"</code> regular expression causes the <code class="command">semanage</code> command to apply changes to the <code class="filename">/web/</code> directory, as well as the files in it. Note: running this command does not directly change the type - <code class="filename">/web/</code> and files in it are still labeled with the <code class="computeroutput">default_t</code> type: </div><pre class="screen"># ls -dZ /web drwxr-xr-x root root unconfined_u:object_r:default_t:s0 /web # ls -lZ /web -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file3 </pre><div class="para"> The <code class="command">/usr/sbin/semanage fcontext -a -t httpd_sys_content_t "/web(/.*)?"</code> command adds the following entry to <code class="filename">/etc/selinux/targeted/contexts/files/file_contexts.local</code>: </div><pre class="screen">/web(/.*)? system_u:object_r:httpd_sys_content_t:s0 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -R -v /web</code> command to change the type of the <code class="filename">/web/</code> directory, as well as all files in it. The <code class="option">-R</code> is for recursive, which means all files and directories under the <code class="filename">/web/</code> directory are labeled with the <code class="computeroutput">httpd_sys_content_t</code> type. Since the <code class="command">semanage</code> command added an entry to <code class="filename">file.contexts.local</code> for <code class="computeroutput">/web(/.*)?</code>, the <code class="command">/sbin/restorecon</code> command changes the types to <code class="computeroutput">httpd_sys_content_t</code>: </div><pre class="screen"># /sbin/restorecon -R -v /web restorecon reset /web context unconfined_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0 restorecon reset /web/file2 context unconfined_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0 restorecon reset /web/file3 context unconfined_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0 restorecon reset /web/file1 context unconfined_u:object_r:default_t:s0->system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> By default, newly-created files and directories inherit the SELinux type of their parents. In this example, files and directories created in the <code class="filename">/web/</code> directory will be labeled with the <code class="computeroutput">httpd_sys_content_t</code> type. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -d "/web(/.*)?"</code> command to remove the context added for <code class="computeroutput">"/web(/.*)?"</code>. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -R -v /web</code> command to restore the default SELinux contexts. </div></li></ol></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Persistent_Changes_semanage_fcontext-Deleting_an_added_Context">Deleting an added Context</h5> The following example demonstrates adding and removing an SELinux context: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -a -t httpd_sys_content_t /test</code> command. The <code class="filename">/test/</code> directory does not have to exist. This command adds the following context to <code class="filename">/etc/selinux/targeted/contexts/files/file_contexts.local</code>: </div><pre class="screen">/test system_u:object_r:httpd_sys_content_t:s0 </pre></li><li class="listitem"><div class="para"> To remove the context, as the Linux root user, run the <code class="command">/usr/sbin/semanage fcontext -d <em class="replaceable"><code>file-name</code></em>|<em class="replaceable"><code>directory-name</code></em></code> command, where <em class="replaceable"><code>file-name</code></em>|<em class="replaceable"><code>directory-name</code></em> is the first part in <code class="filename">file_contexts.local</code>. The following is an example of a context in <code class="filename">file_contexts.local</code>: </div><pre class="screen">/test system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> With the first part being <code class="computeroutput">/test</code>. To prevent the <code class="filename">/test/</code> directory from being labeled with the <code class="computeroutput">httpd_sys_content_t</code> after running <code class="command">/sbin/restorecon</code>, or after a file system relabel, run the following command as the Linux root user to delete the context from <code class="filename">file_contexts.local</code>: </div><div class="para"> <code class="command">/usr/sbin/semanage fcontext -d /test</code> </div></li></ol></div><div class="para"> If the context is part of a regular expression, for example, <code class="computeroutput">/web(/.*)?</code>, use quotation marks around the regular expression: </div><div class="para"> <code class="command">/usr/sbin/semanage fcontext -d "/web(/.*)?"</code> </div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">semanage</span>(8)</span> manual page for further information about <code class="command">/usr/sbin/semanage</code>. </div><div class="important"><h2>Important</h2><div class="para"> When changing the SELinux context with <code class="command">/usr/sbin/semanage fcontext -a</code>, use the full path to the file or directory to avoid files being mislabeled after a file system relabel, or after the <code class="command">/sbin/restorecon</code> command is run. </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html"><strong>Prev</strong>5.7. SELinux Contexts - Labeling Files</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html"><strong>Next</strong>5.8. The file_t and default_t Types</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>4.3. Confined and Unconfined Users</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Targeted_Policy.html" title="Chapter 4. Targeted Policy"/><link rel="prev" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html" title="4.2. Unconfined Processes"/><link rel="next" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.p ng" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html"><strong>Next</strong></a></li></ul><div class="section" title="4.3. Confined and Unconfined Users"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users">4.3. Confined and Unconfined Users</h2></div></div></div><div class="para"> Each Linux user is mapped to an SELinux user via SELinux policy. This allows Linux users to inherit the restrictions on SELinux users. This Linux user mapping is seen by running the <code class="command">semanage login -l</code> command as the Linux root user: </div><pre class="screen"># /usr/sbin/semanage login -l
Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre><div class="para"> In Fedora 12, Linux users are mapped to the SELinux <code class="computeroutput">__default__</code> login by default (which is mapped to the SELinux <code class="computeroutput">unconfined_u</code> user). The following defines the default-mapping: </div><pre class="screen">__default__ unconfined_u s0-s0:c0.c1023 </pre><div class="para"> The following example demonstrates adding a new Linux user, and that Linux user being mapped to the SELinux <code class="computeroutput">unconfined_u</code> user. It assumes that the Linux root user is running unconfined, as it does by default in Fedora 12: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/useradd newuser</code> command to create a new Linux user named newuser. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">passwd newuser</code> command to assign a password to the Linux newuser user: </div><pre class="screen"># passwd newuser Changing password for user newuser. New UNIX password: <em class="replaceable"><code>Enter a password</code></em> Retype new UNIX password: <em class="replaceable"><code>Enter the same password again</code></em> passwd: all authentication tokens updated successfully. </pre></li><li class="listitem"><div class="para"> Log out of your current session, and log in as the Linux newuser user. When you log in, pam_selinux maps the Linux user to an SELinux user (in this case, unconfined_u), and sets up the resulting SELinux context. The Linux user's shell is then launched with this context. Run the <code class="command">id -Z</code> command to view the context of a Linux user: </div><pre class="screen">[newuser@localhost ~]$ id -Z unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 </pre></li><li class="listitem"><div class="para"> Log out of the Linux newuser's session, and log in with your account. If you do not want the Linux newuser user, run the <code class="command">/usr/sbin/userdel -r newuser</code> command as the Linux root user to remove it, along with the Linux newuser's home directory. </div></li></ol></div><div class="para"> Confined and unconfined Linux users are subject to executable and writeable memory checks, and are also restricted by MCS (and MLS, if the MLS policy is used). If unconfined Linux users execute an application that SELinux policy defines can transition from the <code class="computeroutput">unconfined_t</code> domain to its own confined domain, unconfined Linux users are still subject to the restrictions of that confined domain. The security benefit of this is that, even though a Linux user is running unconfined, the application remains confined, and therefore, the exploitation of a flaw in the application can be limited by policy. Note: this does not protect the system from the user. Instead, the user and the system are being protected from possible damage caused by a flaw in the application. </div><div class="para"> The following confined SELinux users are available in Fedora 12: </div><div class="table" id="tabl-Security-Enhanced_Linux-Confined_and_Unconfined_Users-SELinux_User_Capabilities"><div class="table-contents"><table summary="SELinux User Capabilities" border="1"><colgroup><col/><col/><col/><col/><col/><col/></colgroup><thead><tr><th> User </th><th> Domain </th><th> X Window System </th><th> su and sudo </th><th> Execute in home directory and /tmp/ </th><th> Networking </th></tr></thead><tbody><tr><td> guest_u </td><td> guest_t </td><td align="center"> no </td><td align="center"> no </td><td align="center"> optional </td><td align="center"> no </td></tr><tr><td> xguest_u </td><td> xguest_t </td><td align="center"> yes </td><td align="center"> no </td><td align="center"> optional </td><td align="center"> only <span class="application"><strong>Firefox</strong></span> </td></tr><tr><td> user_u </td><td> user_t </td><td align="center"> yes </td><td align="center"> no </td><td align="center"> optional </td><td align="center"> yes </td></tr><tr><td> staff_u </td><td> staff_t </td><td align="center"> yes </td><td align="center"> only <code class="command">sudo</code> </td><td align="center"> optional </td><td align="center"> yes </td></tr></tbody></table></div><h6>Table 4.1. SELinux User Capabilities</h6></div><br class="table-break"/><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Linux users in the <code class="computeroutput">guest_t</code>, <code class="computeroutput">xguest_t</code>, and <code class="computeroutput">user_t</code> domains can only run set user ID (setuid) applications if SELinux policy permits it (such as <code class="command">passwd</code>). They can not run the <code class="command">su</code> and <code class="command">/usr/bin/sudo</code> setuid applications, and therefore, can not use these applications to become the Linux root user. </div></li><li class="listitem"><div class="para"> Linux users in the <code class="computeroutput">guest_t</code> domain have no network access, and can only log in via a terminal (including <code class="systemitem">ssh</code>; they can log in via <code class="systemitem">ssh</code>, but can not use <code class="systemitem">ssh</code> to connect to another system). </div></li><li class="listitem"><div class="para"> The only network access Linux users in the <code class="computeroutput">xguest_t</code> domain have is <span class="application"><strong>Firefox</strong></span> connecting to web pages. </div></li><li class="listitem"><div class="para"> Linux users in the <code class="computeroutput">xguest_t</code>, <code class="computeroutput">user_t</code> and <code class="computeroutput">staff_t</code> domains can log in via the X Window System and a terminal. </div></li><li class="listitem"><div class="para"> By default, Linux users in the <code class="computeroutput">staff_t</code> domain do not have permissions to execute applications with <code class="command">/usr/bin/sudo</code>. These permissions must be configured by an administrator. </div></li></ul></div><div class="para"> By default, Linux users in the <code class="computeroutput">guest_t</code> and <code class="computeroutput">xguest_t</code> domains can not execute applications in their home directories or <code class="filename">/tmp/</code>, preventing them from executing applications (which inherit users' permissions) in directories they have write access to. This helps prevent flawed or malicious applications from modifying files users' own. </div><div class="para"> By default, Linux users in the <code class="computeroutput">user_t</code> and <code class="computeroutput">staff_t</code> domains can execute applications in their home directories and <code class="filename">/tmp/</code>. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Confining_Users-Booleans_for_Users_Executing_Applications.html" title="6.6. Booleans for Users Executing Applications">Section 6.6, “Booleans for Users Executing Applications”</a> for information about allowing and preventing users from executing applications in their home directories and <code class="filename">/tmp/</code>. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html"><strong>Prev</strong>4.2. Unconfined Processes</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html"><strong>Next</strong>Chapter 5. Working with SELinux</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>4.2. Unconfined Processes</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Targeted_Policy.html" title="Chapter 4. Targeted Policy"/><link rel="prev" href="chap-Security-Enhanced_Linux-Targeted_Policy.html" title="Chapter 4. Targeted Policy"/><link rel="next" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html" title="4.3. Confined and Unconfined Users"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.pn g" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Targeted_Policy.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html"><strong>Next</strong></a></li></ul><div class="section" title="4.2. Unconfined Processes"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Targeted_Policy-Unconfined_Processes">4.2. Unconfined Processes</h2></div></div></div><div class="para"> Unconfined processes run in unconfined domains, for example, init programs run in the unconfined <code class="computeroutput">initrc_t</code> domain, unconfined kernel processes run in the <code class="computeroutput">kernel_t</code> domain, and unconfined Linux users run in the <code class="computeroutput">unconfined_t</code> domain. For unconfined processes, SELinux policy rules are applied, but policy rules exist that allow processes running in unconfined domains almost all access. Processes running in unconfined domains fall back to using DAC rules exclusively. If an unconfined process is compromised, SELinux does not prevent an attacker from gaining access to system resources and data, but of course, DAC rules are still used. SELinux is a security enhancement on top of DAC rules - it does not replace them. </div><div class="para"> The following example demonstrates how the Apache HTTP Server (<code class="systemitem">httpd</code>) can access data intended for use by Samba, when running unconfined. Note: in Fedora, the <code class="systemitem">httpd</code> process runs in the confined <code class="computeroutput">httpd_t</code> domain by default. This is an example, and should not be used in production. It assumes that the <span class="package">httpd</span>, <span class="package">wget</span>, <span class="package">setroubleshoot-server</span>, and <span class="package">audit</span> packages are installed, that the SELinux targeted policy is used, and that SELinux is running in enforcing mode: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Run the <code class="command">sestatus</code> command to confirm that SELinux is enabled, is running in enforcing mode, and that targeted policy is being used: </div><pre class="screen"> $ /usr/sbin/sestatus SELinux status: enabled SELinuxfs mount: /selinux Current mode: enforcing Mode from config file: enforcing Policy version: 23 Policy from config file: targeted </pre><div class="para"> <code class="computeroutput">SELinux status: enabled</code> is returned when SELinux is enabled. <code class="computeroutput">Current mode: enforcing</code> is returned when SELinux is running in enforcing mode. <code class="computeroutput">Policy from config file: targeted</code> is returned when the SELinux targeted policy is used. </div></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">touch /var/www/html/test2file</code> command to create a file. </div></li><li class="listitem"><div class="para"> Run the <code class="command">ls -Z /var/www/html/test2file</code> command to view the SELinux context: </div><pre class="screen">-rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 /var/www/html/test2file </pre><div class="para"> By default, Linux users run unconfined in Fedora, which is why the <code class="filename">test2file</code> file is labeled with the SELinux <code class="computeroutput">unconfined_u</code> user. RBAC is used for processes, not files. Roles do not have a meaning for files - the <code class="computeroutput">object_r</code> role is a generic role used for files (on persistent storage and network file systems). Under the <code class="filename">/proc/</code> directory, files related to processes may use the <code class="computeroutput">system_r</code> role.<sup>[<a id="d0e1499" href="#ftn.d0e1499" class="footnote">7</a>]</sup> The <code class="computeroutput">httpd_sys_content_t</code> type allows the <code class="systemitem">httpd</code> process to access this file. </div></li><li class="listitem"><div class="para"> The <code class="command">chcon</code> command relabels files; however, such label changes do not survive when the file system is relabeled. For permanent changes that survive a file system relabel, use the <code class="command">semanage</code> command, which is discussed later. As the Linux root user, run the following command to change the type to a type used by Samba: </div><div class="para"> <code class="command">chcon -t samba_share_t /var/www/html/test2file</code> </div><div class="para"> Run the <code class="command">ls -Z /var/www/html/test2file</code> command to view the changes: </div><pre class="screen">-rw-r--r-- root root unconfined_u:object_r:samba_share_t:s0 /var/www/html/test2file </pre></li><li class="listitem"><div class="para"> Run the <code class="command">service httpd status</code> command to confirm that the <code class="systemitem">httpd</code> process is not running: </div><pre class="screen">$ /sbin/service httpd status httpd is stopped </pre><div class="para"> If the output differs, run the <code class="command">service httpd stop</code> command as the Linux root user to stop the <code class="systemitem">httpd</code> process: </div><pre class="screen"># /sbin/service httpd stop Stopping httpd: [ OK ] </pre></li><li class="listitem"><div class="para"> To make the <code class="systemitem">httpd</code> process run unconfined, run the following command as the Linux root user to change the type of <code class="filename">/usr/sbin/httpd</code>, to a type that does not transition to a confined domain: </div><div class="para"> <code class="command">chcon -t unconfined_exec_t /usr/sbin/httpd</code> </div></li><li class="listitem"><div class="para"> Run the <code class="command">ls -Z /usr/sbin/httpd</code> command to confirm that <code class="filename">/usr/sbin/httpd</code> is labeled with the <code class="computeroutput">unconfined_exec_t</code> type: </div><pre class="screen">-rwxr-xr-x root root system_u:object_r:unconfined_exec_t /usr/sbin/httpd </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">service httpd start</code> command to start the <code class="systemitem">httpd</code> process. The output is as follows if <code class="systemitem">httpd</code> starts successfully: </div><pre class="screen"># /sbin/service httpd start Starting httpd: [ OK ] </pre></li><li class="listitem"><div class="para"> Run the <code class="command">ps -eZ | grep httpd</code> command to view the <code class="systemitem">httpd</code> running in the <code class="computeroutput">unconfined_t</code> domain: </div><pre class="screen">$ ps -eZ | grep httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7721</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7723</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7724</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7725</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7726</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7727</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7728</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7729</code></em> ? 00:00:00 httpd unconfined_u:system_r:unconfined_t <em class="replaceable"><code>7730</code></em> ? 00:00:00 httpd </pre></li><li class="listitem"><div class="para"> Change into a directory where your Linux user has write access to, and run the <code class="command">wget http://localhost/test2file</code> command. Unless there are changes to the default configuration, this command succeeds: </div><pre class="screen">--2009-05-07 01:41:10-- http://localhost/test2file Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 0 [text/plain] Saving to: `test2file.1'
[ <=> ]--.-K/s in 0s 2009-05-07 01:41:10 (0.00 B/s) - `test2file.1' saved [0/0] </pre><div class="para"> Although the <code class="systemitem">httpd</code> process does not have access to files labeled with the <code class="computeroutput">samba_share_t</code> type, <code class="systemitem">httpd</code> is running in the unconfined <code class="computeroutput">unconfined_t</code> domain, and falls back to using DAC rules, and as such, the <code class="command">wget</code> command succeeds. Had <code class="systemitem">httpd</code> been running in the confined <code class="computeroutput">httpd_t</code> domain, the <code class="command">wget</code> command would have failed. </div></li><li class="listitem"><div class="para"> The <code class="command">restorecon</code> command restores the default SELinux context for files. As the Linux root user, run the <code class="command">restorecon -v /usr/sbin/httpd</code> command to restore the default SELinux context for <code class="filename">/usr/sbin/httpd</code>: </div><pre class="screen"># /sbin/restorecon -v /usr/sbin/httpd restorecon reset /usr/sbin/httpd context system_u:object_r:unconfined_notrans_exec_t:s0->system_u:object_r:httpd_exec_t:s0 </pre><div class="para"> Run the <code class="command">ls -Z /usr/sbin/httpd</code> command to confirm that <code class="filename">/usr/sbin/httpd</code> is labeled with the <code class="computeroutput">httpd_exec_t</code> type: </div><pre class="screen">$ ls -Z /usr/sbin/httpd -rwxr-xr-x root root system_u:object_r:httpd_exec_t /usr/sbin/httpd </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/service httpd restart</code> command to restart <code class="systemitem">httpd</code>. After restarting, run the <code class="command">ps -eZ | grep httpd</code> to confirm that <code class="systemitem">httpd</code> is running in the confined <code class="computeroutput">httpd_t</code> domain: </div><pre class="screen"># /sbin/service httpd restart Stopping httpd: [ OK ] Starting httpd: [ OK ] # ps -eZ | grep httpd unconfined_u:system_r:httpd_t 8880 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8882 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8883 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8884 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8885 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8886 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8887 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8888 ? 00:00:00 httpd unconfined_u:system_r:httpd_t 8889 ? 00:00:00 httpd </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">rm -i /var/www/html/test2file</code> command to remove <code class="filename">test2file</code>. </div></li><li class="listitem"><div class="para"> If you do not require <code class="systemitem">httpd</code> to be running, as the Linux root user, run the <code class="command">service httpd stop</code> command to stop <code class="systemitem">httpd</code>: </div><pre class="screen"># /sbin/service httpd stop Stopping httpd: [ OK ] </pre></li></ol></div><div class="para"> The examples in these sections demonstrate how data can be protected from a compromised confined-process (protected by SELinux), as well as how data is more accessible to an attacker from a compromised unconfined-process (not protected by SELinux). </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e1499" href="#d0e1499" class="para">7</a>] </sup> When using other policies, such as MLS, other roles may also be used, for example, <code class="computeroutput">secadm_r</code>. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Targeted_Policy.html"><strong>Prev</strong>Chapter 4. Targeted Policy</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Targeted_Policy-Confined_and_Unconfined_Users.html"><strong>Next</strong>4.3. Confined and Unconfined Users</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.2.3. Evolving Rules and Broken Applications</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html" title="7.2. Top Three Causes of Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html" title="7.2.2. How are Confined Services Running?"/><link rel="next" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html" title="7.3. Fixing Problems"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="ri ght" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html"><strong>Next</strong></a></li></ul><div class="section" title="7.2.3. Evolving Rules and Broken Applications"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications">7.2.3. Evolving Rules and Broken Applications</h3></div></div></div><div class="para"> Applications may be broken, causing SELinux to deny access. Also, SELinux rules are evolving - SELinux may not have seen an application running in a certain way, possibly causing it to deny access, even though the application is working as expected. For example, if a new version of PostgreSQL is released, it may perform actions the current policy has not seen before, causing access to be denied, even though access should be allowed. </div><div class="para"> For these situations, after access is denied, use <code class="command">audit2allow</code> to create a custom policy module to allow access. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Fixing_Problems-Allowing_Access_audit2allow.html" title="7.3.8. Allowing Access: audit2allow">Section 7.3.8, “Allowing Access: audit2allow”</a> for information about using <code class="command">audit2allow</code>. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html"><strong>Prev</strong>7.2.2. How are Confined Services Running?</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html"><strong>Next</strong>7.3. Fixing Problems</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.2.2. How are Confined Services Running?</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html" title="7.2. Top Three Causes of Problems"/><link rel="prev" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html" title="7.2. Top Three Causes of Problems"/><link rel="next" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html" title="7.2.3. Evolving Rules and Broken Applications"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt=" Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html"><strong>Next</strong></a></li></ul><div class="section" title="7.2.2. How are Confined Services Running?"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running">7.2.2. How are Confined Services Running?</h3></div></div></div><div class="para"> Services can be run in a variety of ways. To cater for this, you must tell SELinux how you are running services. This can be achieved via Booleans that allow parts of SELinux policy to be changed at runtime, without any knowledge of SELinux policy writing. This allows changes, such as allowing services access to NFS file systems, without reloading or recompiling SELinux policy. Also, running services on non-default port numbers requires policy configuration to be updated via the <code class="command">semanage</code> command. </div><div class="para"> For example, to allow the Apache HTTP Server to communicate with MySQL, turn the <code class="computeroutput">httpd_can_network_connect_db</code> Boolean on: </div><pre class="screen"> # /usr/sbin/setsebool -P httpd_can_network_connect_db on </pre><div class="para"> If access is denied for a particular service, use the <code class="command">getsebool</code> and <code class="command">grep</code> commands to see if any Booleans are available to allow access. For example, use the <code class="command">getsebool -a | grep ftp</code> command to search for FTP related Booleans: </div><pre class="screen"> $ /usr/sbin/getsebool -a | grep ftp allow_ftpd_anon_write --> off allow_ftpd_full_access --> off allow_ftpd_use_cifs --> off allow_ftpd_use_nfs --> off ftp_home_dir --> off httpd_enable_ftp_server --> off tftp_anon_write --> off </pre><div class="para"> For a list of Booleans and whether they are on or off, run the <code class="command">/usr/sbin/getsebool -a</code> command. For a list of Booleans, an explanation of what each one is, and whether they are on or off, run the <code class="command">/usr/sbin/semanage boolean -l</code> command as the Linux root user. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html" title="5.6. Booleans">Section 5.6, “Booleans”</a> for information about listing and configuring Booleans. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-How_are_Confined_Services_Running-Port_Numbers">Port Numbers</h5> Depending on policy configuration, services may only be allowed to run on certain port numbers. Attempting to change the port a service runs on without changing policy may result in the service failing to start. For example, run the <code class="command">semanage port -l | grep http</code> command as the Linux root user to list <code class="systemitem">http</code> related ports: </div><pre class="screen"> # /usr/sbin/semanage port -l | grep http http_cache_port_t tcp 3128, 8080, 8118 http_cache_port_t udp 3130 http_port_t tcp 80, 443, 488, 8008, 8009, 8443 pegasus_http_port_t tcp 5988 pegasus_https_port_t tcp 5989 </pre><div class="para"> The <code class="computeroutput">http_port_t</code> port type defines the ports Apache HTTP Server can listen on, which in this case, are TCP ports 80, 443, 488, 8008, 8009, and 8443. If an administrator configures <code class="filename">httpd.conf</code> so that <code class="systemitem">httpd</code> listens on port 9876 (<code class="option">Listen 9876</code>), but policy is not updated to reflect this, the <code class="command">service httpd start</code> command fails: </div><pre class="screen"> # /sbin/service httpd start Starting httpd: (13)Permission denied: make_sock: could not bind to address [::]:9876 (13)Permission denied: make_sock: could not bind to address 0.0.0.0:9876 no listening sockets available, shutting down Unable to open logs [FAILED] </pre><div class="para"> An SELinux denial similar to the following is logged to <code class="filename">/var/log/audit/audit.log</code>: </div><pre class="screen"> type=AVC msg=audit(1225948455.061:294): avc: denied { name_bind } for pid=4997 comm="httpd" src=9876 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=system_u:object_r:port_t:s0 tclass=tcp_socket </pre><div class="para"> To allow <code class="systemitem">httpd</code> to listen on a port that is not listed for the <code class="computeroutput">http_port_t</code> port type, run the <code class="command">semanage port</code> command to add a port to policy configuration<sup>[<a id="d0e5533" href="#ftn.d0e5533" class="footnote">15</a>]</sup>: </div><pre class="screen"> # /usr/sbin/semanage port -a -t http_port_t -p tcp 9876 </pre><div class="para"> The <code class="option">-a</code> option adds a new record; the <code class="option">-t</code> option defines a type; and the <code class="option">-p</code> option defines a protocol. The last argument is the port number to add. </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e5533" href="#d0e5533" class="para">15</a>] </sup> The <code class="command">semanage port -a</code> command adds an entry to the <code class="filename">/etc/selinux/targeted/modules/active/ports.local</code> file. Note: by default, this file can only be viewed by the Linux root user. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html"><strong>Prev</strong>7.2. Top Three Causes of Problems</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html"><strong>Next</strong>7.2.3. Evolving Rules and Broken Applications</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.3. Fixing Problems</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Troubleshooting.html" title="Chapter 7. Troubleshooting"/><link rel="prev" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html" title="7.2.3. Evolving Rules and Broken Applications"/><link rel="next" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html" title="7.3.2. Possible Causes of Silent Denials"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="ht tp://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html"><strong>Next</strong></a></li></ul><div class="section" title="7.3. Fixing Problems"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems">7.3. Fixing Problems</h2></div></div></div><div class="para"> The following sections help troubleshoot issues. They go over: checking Linux permissions, which are checked before SELinux rules; possible causes of SELinux denying access, but no denials being logged; manual pages for services, which contain information about labeling and Booleans; permissive domains, for allowing one process to run permissive, rather than the whole system; how to search for and view denial messages; analyzing denials; and creating custom policy modules with <code class="command">audit2allow</code>. </div><div class="section" title="7.3.1. Linux Permissions"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Fixing_Problems-Linux_Permissions">7.3.1. Linux Permissions</h3></div></div></div><div class="para"> When access is denied, check standard Linux permissions. As mentioned in <a class="xref" href="chap-Security-Enhanced_Linux-Introduction.html" title="Chapter 2. Introduction">Chapter 2, <i>Introduction</i></a>, most operating systems use a Discretionary Access Control (DAC) system to control access, allowing users to control the permissions of files that they own. SELinux policy rules are checked after DAC rules. SELinux policy rules are not used if DAC rules deny access first. </div><div class="para"> If access is denied and no SELinux denials are logged, use the <code class="command">ls -l</code> command to view the standard Linux permissions: </div><pre class="screen"> $ ls -l /var/www/html/index.html -rw-r----- 1 root root 0 2009-05-07 11:06 index.html </pre><div class="para"> In this example, <code class="filename">index.html</code> is owned by the root user and group. The root user has read and write permissions (<code class="computeroutput">-rw</code>), and members of the root group have read permissions (<code class="computeroutput">-r-</code>). Everyone else has no access (<code class="computeroutput">---</code>). By default, such permissions do not allow <code class="systemitem">httpd</code> to read this file. To resolve this issue, use the <code class="command">chown</code> command to change the owner and group. This command must be run as the Linux root user: </div><pre class="screen"> # chown apache:apache /var/www/html/index.html </pre><div class="para"> This assumes the default configuration, in which <code class="systemitem">httpd</code> runs as the Linux apache user. If you run <code class="systemitem">httpd</code> with a different user, replace <code class="computeroutput">apache:apache</code> with that user. </div><div class="para"> Refer to the <a href="http://fedoraproject.org/wiki/Docs/Drafts/AdministrationGuide/Permissions">Fedora Documentation Project "Permissions"</a> draft for information about managing Linux permissions. </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Evolving_Rules_and_Broken_Applications.html"><strong>Prev</strong>7.2.3. Evolving Rules and Broken Applications</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Fixing_Problems-Possible_Causes_of_Silent_Denials.html"><strong>Next</strong>7.3.2. Possible Causes of Silent Denials</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>7.2. Top Three Causes of Problems</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Troubleshooting.html" title="Chapter 7. Troubleshooting"/><link rel="prev" href="chap-Security-Enhanced_Linux-Troubleshooting.html" title="Chapter 7. Troubleshooting"/><link rel="next" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html" title="7.2.2. How are Confined Services Running?"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Comm on_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Troubleshooting.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html"><strong>Next</strong></a></li></ul><div class="section" title="7.2. Top Three Causes of Problems"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Troubleshooting-Top_Three_Causes_of_Problems">7.2. Top Three Causes of Problems</h2></div></div></div><div class="para"> The following sections describe the top three causes of problems: labeling problems, configuring Booleans and ports for services, and evolving SELinux rules. </div><div class="section" title="7.2.1. Labeling Problems"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-Labeling_Problems">7.2.1. Labeling Problems</h3></div></div></div><div class="para"> On systems running SELinux, all processes and files are labeled with a label that contains security-relevant information. This information is called the SELinux context. If these labels are wrong, access may be denied. If an application is labeled incorrectly, the process it transitions to may not have the correct label, possibly causing SELinux to deny access, and the process being able to create mislabeled files. </div><div class="para"> A common cause of labeling problems is when a non-standard directory is used for a service. For example, instead of using <code class="filename">/var/www/html/</code> for a website, an administrator wants to use <code class="filename">/srv/myweb/</code>. On Fedora 12, the <code class="filename">/srv/</code> directory is labeled with the <code class="computeroutput">var_t</code> type. Files and directories created and <code class="filename">/srv/</code> inherit this type. Also, newly-created top-level directories (such as <code class="filename">/myserver/</code>) may be labeled with the <code class="computeroutput">default_t</code> type. SELinux prevents the Apache HTTP Server (<code class="systemitem">httpd</code>) from accessing both of these types. To allow access, SELinux must know that the files in <code class="filename">/srv/myweb/</code> are to be accessible to <code class="systemitem">httpd</code>: </div><pre class="screen"> # /usr/sbin/semanage fcontext -a -t httpd_sys_content_t \ "/srv/myweb(/.*)?" </pre><div class="para"> This <code class="command">semanage</code> command adds the context for the <code class="filename">/srv/myweb/</code> directory (and all files and directories under it) to the SELinux file-context configuration<sup>[<a id="d0e5371" href="#ftn.d0e5371" class="footnote">14</a>]</sup>. The <code class="command">semanage</code> command does not change the context. As the Linux root user, run the <code class="command">restorecon</code> command to apply the changes: </div><pre class="screen"> # /sbin/restorecon -R -v /srv/myweb </pre><div class="para"> Refer to <a class="xref" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html" title="5.7.2. Persistent Changes: semanage fcontext">Section 5.7.2, “Persistent Changes: semanage fcontext”</a> for further information about adding contexts to the file-context configuration. </div><div class="section" title="7.2.1.1. What is the Correct Context?"><div class="titlepage"><div><div><h4 class="title" id="sect-Security-Enhanced_Linux-Labeling_Problems-What_is_the_Correct_Context">7.2.1.1. What is the Correct Context?</h4></div></div></div><div class="para"> The <code class="command">matchpathcon</code> command checks the context of a file path and compares it to the default label for that path. The following example demonstrates using <code class="command">matchpathcon</code> on a directory that contains incorrectly labeled files: </div><pre class="screen"> $ /usr/sbin/matchpathcon -V /var/www/html/* /var/www/html/index.html has context unconfined_u:object_r:user_home_t:s0, should be system_u:object_r:httpd_sys_content_t:s0 /var/www/html/page1.html has context unconfined_u:object_r:user_home_t:s0, should be system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> In this example, the <code class="filename">index.html</code> and <code class="filename">page1.html</code> files are labeled with the <code class="computeroutput">user_home_t</code> type. This type is used for files in user home directories. Using the <code class="command">mv</code> command to move files from your home directory may result in files being labeled with the <code class="computeroutput">user_home_t</code> type. This type should not exist outside of home directories. Use the <code class="command">restorecon</code> command to restore such files to their correct type: </div><pre class="screen"> # /sbin/restorecon -v /var/www/html/index.html restorecon reset /var/www/html/index.html context unconfined_u:object_r:user_home_t:s0->system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> To restore the context for all files under a directory, use the <code class="option">-R</code> option: </div><pre class="screen"> # /sbin/restorecon -R -v /var/www/html/ restorecon reset /var/www/html/page1.html context unconfined_u:object_r:samba_share_t:s0->system_u:object_r:httpd_sys_content_t:s0 restorecon reset /var/www/html/index.html context unconfined_u:object_r:samba_share_t:s0->system_u:object_r:httpd_sys_content_t:s0 </pre><div class="para"> Refer to <a class="xref" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Checking_the_Default_SELinux_Context.html" title="5.10.3. Checking the Default SELinux Context">Section 5.10.3, “Checking the Default SELinux Context”</a> for a more detailed example of <code class="command">matchpathcon</code>. </div></div></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e5371" href="#d0e5371" class="para">14</a>] </sup> Files in <code class="filename">/etc/selinux/targeted/contexts/files/</code> define contexts for files and directories. Files in this directory are read by <code class="command">restorecon</code> and <code class="command">setfiles</code> to restore files and directories to their default contexts. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Troubleshooting.html"><strong>Prev</strong>Chapter 7. Troubleshooting</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Top_Three_Causes_of_Problems-How_are_Confined_Services_Running.html"><strong>Next</strong>7.2.2. How are Confined Services Running?</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.6. Booleans</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html" title="5.5. SELinux Modes"/><link rel="next" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html" title="5.6.2. Configuring Booleans"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documen tation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html"><strong>Next</strong></a></li></ul><div class="section" title="5.6. Booleans"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans">5.6. Booleans</h2></div></div></div><div class="para"> Booleans allow parts of SELinux policy to be changed at runtime, without any knowledge of SELinux policy writing. This allows changes, such as allowing services access to NFS file systems, without reloading or recompiling SELinux policy. </div><div class="section" title="5.6.1. Listing Booleans"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Booleans-Listing_Booleans">5.6.1. Listing Booleans</h3></div></div></div><div class="para"> For a list of Booleans, an explanation of what each one is, and whether they are on or off, run the <code class="command">semanage boolean -l</code> command as the Linux root user. The following example does not list all Booleans: </div><pre class="screen"># /usr/sbin/semanage boolean -l SELinux boolean Description
ftp_home_dir -> off Allow ftp to read and write files in the user home directories xen_use_nfs -> off Allow xen to manage nfs files xguest_connect_network -> on Allow xguest to configure Network Manager </pre><div class="para"> The <code class="computeroutput">SELinux boolean</code> column lists Boolean names. The <code class="computeroutput">Description</code> column lists whether the Booleans are on or off, and what they do. </div><div class="para"> In the following example, the <code class="computeroutput">ftp_home_dir</code> Boolean is off, preventing the FTP daemon (<code class="systemitem">vsftpd</code>) from reading and writing to files in user home directories: </div><pre class="screen">ftp_home_dir -> off Allow ftp to read and write files in the user home directories </pre><div class="para"> The <code class="command">getsebool -a</code> command lists Booleans, whether they are on or off, but does not give a description of each one. The following example does not list all Booleans: </div><pre class="screen">$ /usr/sbin/getsebool -a allow_console_login --> off allow_cvs_read_shadow --> off allow_daemons_dump_core --> on </pre><div class="para"> Run the <code class="command">getsebool <em class="replaceable"><code>boolean-name</code></em></code> command to only list the status of the <em class="replaceable"><code>boolean-name</code></em> Boolean: </div><pre class="screen">$ /usr/sbin/getsebool allow_console_login allow_console_login --> off </pre><div class="para"> Use a space-separated list to list multiple Booleans: </div><pre class="screen">$ getsebool allow_console_login allow_cvs_read_shadow allow_daemons_dump_core allow_console_login --> off allow_cvs_read_shadow --> off allow_daemons_dump_core --> on </pre></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html"><strong>Prev</strong>5.5. SELinux Modes</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Booleans-Configuring_Booleans.html"><strong>Next</strong>5.6.2. Configuring Booleans</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.4. Enabling and Disabling SELinux</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html" title="5.3. Main Configuration File"/><link rel="next" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html" title="5.4.2. Disabling SELinux"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><im g src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html"><strong>Next</strong></a></li></ul><div class="section" title="5.4. Enabling and Disabling SELinux"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux">5.4. Enabling and Disabling SELinux</h2></div></div></div><div class="para"> Use the <code class="command">/usr/sbin/getenforce</code> or <code class="command">/usr/sbin/sestatus</code> commands to check the status of SELinux. The <code class="command">getenforce</code> command returns <code class="computeroutput">Enforcing</code>, <code class="computeroutput">Permissive</code>, or <code class="computeroutput">Disabled</code>. The <code class="command">getenforce</code> command returns <code class="computeroutput">Enforcing</code> when SELinux is enabled (SELinux policy rules are enforced): </div><pre class="screen">$ /usr/sbin/getenforce Enforcing </pre><div class="para"> The <code class="command">getenforce</code> command returns <code class="computeroutput">Permissive</code> when SELinux is enabled, but SELinux policy rules are not enforced, and only DAC rules are used. The <code class="command">getenforce</code> command returns <code class="computeroutput">Disabled</code> if SELinux is disabled. </div><div class="para"> The <code class="command">sestatus</code> command returns the SELinux status and the SELinux policy being used: </div><pre class="screen">$ /usr/sbin/sestatus SELinux status: enabled SELinuxfs mount: /selinux Current mode: enforcing Mode from config file: enforcing Policy version: 23 Policy from config file: targeted </pre><div class="para"> <code class="computeroutput">SELinux status: enabled</code> is returned when SELinux is enabled. <code class="computeroutput">Current mode: enforcing</code> is returned when SELinux is running in enforcing mode. <code class="computeroutput">Policy from config file: targeted</code> is returned when the SELinux targeted policy is used. </div><div class="section" title="5.4.1. Enabling SELinux"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Enabling_SELinux">5.4.1. Enabling SELinux</h3></div></div></div><div class="para"> On systems with SELinux disabled, the <code class="computeroutput">SELINUX=disabled</code> option is configured in <code class="filename">/etc/selinux/config</code>: </div><pre class="screen"># This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted </pre><div class="para"> Also, the <code class="command">getenforce</code> command returns <code class="computeroutput">Disabled</code>: </div><pre class="screen">$ /usr/sbin/getenforce Disabled </pre><div class="para"> To enable SELinux: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Use the <code class="command">rpm -qa | grep selinux</code>, <code class="command">rpm -q policycoreutils</code>, and <code class="command">rpm -qa | grep setroubleshoot</code> commands to confirm that the SELinux packages are installed. This guide assumes the following packages are installed: <span class="package">selinux-policy-targeted</span>, <span class="package">selinux-policy</span>, <span class="package">libselinux</span>, <span class="package">libselinux-python</span>, <span class="package">libselinux-utils</span>, <span class="package">policycoreutils</span>, <span class="package">setroubleshoot</span>, <span class="package">setroubleshoot-server</span>, <span class="package">setroubleshoot-plugins</span>. If these packages are not installed, as the Linux root user, install them via the <code class="command">yum install <em class="replaceable"><code>package-name</code></em></code> command. The following packages are optional: <span class="package">policycoreut ils-gui</span>, <span class="package">setroubleshoot</span>, <span class="package">selinux-policy-devel</span>, and <span class="package">mcstrans</span>. </div><div class="para"> After installing the <span class="package">setroubleshoot-server</span> package, use the <code class="command">/sbin/chkconfig --list setroubleshoot</code> command to confirm that <code class="systemitem">setroubleshootd</code> starts when the system is running in runlevel<sup>[<a id="d0e2520" href="#ftn.d0e2520" class="footnote">10</a>]</sup> 3, 4, and 5: </div><pre class="screen">$ /sbin/chkconfig --list setroubleshoot setroubleshoot 0:off 1:off 2:off 3:on 4:on 5:on 6:off </pre><div class="para"> If the output differs, as the Linux root user, run the <code class="command">/sbin/chkconfig --levels 345 setroubleshoot on</code> command. This makes <code class="systemitem">setroubleshootd</code> automatically start when the system is in runlevel 3, 4, and 5. </div></li><li class="listitem"><div class="para"> Before SELinux is enabled, each file on the file system must be labeled with an SELinux context. Before this happens, confined domains may be denied access, preventing your system from booting correctly. To prevent this, configure <code class="computeroutput">SELINUX=permissive</code> in <code class="filename">/etc/selinux/config</code>: </div><pre class="screen"># This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=permissive # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">reboot</code> command to restart the system. During the next boot, file systems are labeled. The label process labels all files with an SELinux context: </div><pre class="screen">*** Warning -- SELinux targeted policy relabel is required. *** Relabeling could take a very long time, depending on file *** system size and speed of hard drives. **** </pre><div class="para"> Each <code class="computeroutput">*</code> character on the bottom line represents 1000 files that have been labeled. In the above example, four <code class="computeroutput">*</code> characters represent 4000 files have been labeled. The time it takes to label all files depends upon the number of files on the system, and the speed of the hard disk drives. On modern systems, this process can take as little as 10 minutes. </div></li><li class="listitem"><div class="para"> In permissive mode, SELinux policy is not enforced, but denials are still logged for actions that would have been denied if running in enforcing mode. Before changing to enforcing mode, as the Linux root user, run the <code class="command">grep "SELinux is preventing" /var/log/messages</code> command as the Linux root user to confirm that SELinux did not deny actions during the last boot. If SELinux did not deny actions during the last boot, this command does not return any output. Refer to <a class="xref" href="chap-Security-Enhanced_Linux-Troubleshooting.html" title="Chapter 7. Troubleshooting">Chapter 7, <i>Troubleshooting</i></a> for troubleshooting information if SELinux denied access during boot. </div></li><li class="listitem"><div class="para"> If there were no denial messages in <code class="filename">/var/log/messages</code>, configure <code class="computeroutput">SELINUX=enforcing</code> in <code class="filename">/etc/selinux/config</code>: </div><pre class="screen"># This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=enforcing # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted </pre></li><li class="listitem"><div class="para"> Reboot your system. After reboot, confirm that the <code class="command">getenforce</code> command returns <code class="computeroutput">Enforcing</code>: </div><pre class="screen">$ /usr/sbin/getenforce Enforcing </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/usr/sbin/semanage login -l</code> command to view the mapping between SELinux and Linux users. The output should be as follows: </div><pre class="screen">Login Name SELinux User MLS/MCS Range
__default__ unconfined_u s0-s0:c0.c1023 root unconfined_u s0-s0:c0.c1023 system_u system_u s0-s0:c0.c1023 </pre></li></ol></div><div class="para"> If this is not the case, run the following commands as the Linux root user to fix the user mappings. It is safe to ignore the <code class="computeroutput">SELinux-user<em class="replaceable"><code> username</code></em> is already defined</code> warnings if they occur, where <em class="replaceable"><code>username</code></em> can be <code class="computeroutput">unconfined_u</code>, <code class="computeroutput">guest_u</code>, or <code class="computeroutput">xguest_u</code>: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> <pre class="screen">/usr/sbin/semanage user -a -S targeted -P user -R "unconfined_r system_r" -r s0-s0:c0.c1023 unconfined_u </pre> </div></li><li class="listitem"><div class="para"> <pre class="screen">/usr/sbin/semanage login -m -S targeted -s "unconfined_u" -r s0-s0:c0.c1023 __default__ </pre> </div></li><li class="listitem"><div class="para"> <pre class="screen">/usr/sbin/semanage login -m -S targeted -s "unconfined_u" -r s0-s0:c0.c1023 root </pre> </div></li><li class="listitem"><div class="para"> <pre class="screen">/usr/sbin/semanage user -a -S targeted -P user -R guest_r guest_u </pre> </div></li><li class="listitem"><div class="para"> <pre class="screen">/usr/sbin/semanage user -a -S targeted -P user -R xguest_r xguest_u </pre> </div></li></ol></div><div class="important"><h2>Important</h2><div class="para"> When systems run with SELinux in permissive or disabled mode, users have permission to label files incorrectly. Also, files created while SELinux is disabled are not labeled. This causes problems when changing to enforcing mode. To prevent incorrectly labeled and unlabeled files from causing problems, file systems are automatically relabeled when changing from disabled mode to permissive or enforcing mode. </div></div></div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e2520" href="#d0e2520" class="para">10</a>] </sup> Refer to <a href="http://en.wikipedia.org/wiki/Runlevel">http://en.wikipedia.org/wiki/Runlevel</a> for information about runlevels. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html"><strong>Prev</strong>5.3. Main Configuration File</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html"><strong>Next</strong>5.4.2. Disabling SELinux</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.3. Main Configuration File</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html" title="5.2. Which Log File is Used"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html" title="5.4. Enabling and Disabling SELinux"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org "><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html"><strong>Next</strong></a></li></ul><div class="section" title="5.3. Main Configuration File"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File">5.3. Main Configuration File</h2></div></div></div><div class="para"> The <code class="filename">/etc/selinux/config</code> file is the main SELinux configuration file. It controls the SELinux mode and the SELinux policy to use: </div><pre class="screen"># This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=enforcing # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted </pre><div class="variablelist"><dl><dt><span class="term"><code class="computeroutput">SELINUX=enforcing</code></span></dt><dd><div class="para"> The <code class="option">SELINUX</code> option sets the mode SELinux runs in. SELinux has three modes: enforcing, permissive, and disabled. When using enforcing mode, SELinux policy is enforced, and SELinux denies access based on SELinux policy rules. Denial messages are logged. When using permissive mode, SELinux policy is not enforced. SELinux does not deny access, but denials are logged for actions that would have been denied if running SELinux in enforcing mode. When using disabled mode, SELinux is disabled (the SELinux module is not registered with the Linux kernel), and only DAC rules are used. </div></dd><dt><span class="term"><code class="computeroutput">SELINUXTYPE=targeted</code></span></dt><dd><div class="para"> The <code class="option">SELINUXTYPE</code> option sets the SELinux policy to use. Targeted policy is the default policy. Only change this option if you want to use the MLS policy. To use the MLS policy, install the <span class="package">selinux-policy-mls</span> package; configure <code class="option">SELINUXTYPE=mls</code> in <code class="filename">/etc/selinux/config</code>; and reboot your system. </div></dd></dl></div><div class="important"><h2>Important</h2><div class="para"> When systems run with SELinux in permissive or disabled mode, users have permission to label files incorrectly. Also, files created while SELinux is disabled are not labeled. This causes problems when changing to enforcing mode. To prevent incorrectly labeled and unlabeled files from causing problems, file systems are automatically relabeled when changing from disabled mode to permissive or enforcing mode. </div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html"><strong>Prev</strong>5.2. Which Log File is Used</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html"><strong>Next</strong>5.4. Enabling and Disabling SELinux</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.10. Maintaining SELinux Labels</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html" title="5.9.5. Making Context Mounts Persistent"/><link rel="next" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html" title="5.10.2. Moving Files and Directories"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" hr ef="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html"><strong>Next</strong></a></li></ul><div class="section" title="5.10. Maintaining SELinux Labels"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Maintaining_SELinux_Labels_">5.10. Maintaining SELinux Labels </h2></div></div></div><div class="para"> These sections describe what happens to SELinux contexts when copying, moving, and archiving files and directories. Also, it explains how to preserve contexts when copying and archiving. </div><div class="section" title="5.10.1. Copying Files and Directories"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Copying_Files_and_Directories">5.10.1. Copying Files and Directories</h3></div></div></div><div class="para"> When a file or directory is copied, a new file or directory is created if it does not exist. That new file or directory's context is based on default-labeling rules, not the original file or directory's context (unless options were used to preserve the original context). For example, files created in user home directories are labeled with the <code class="computeroutput">user_home_t</code> type: </div><pre class="screen"> $ touch file1 $ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre><div class="para"> If such a file is copied to another directory, such as <code class="filename">/etc/</code>, the new file is created in accordance to default-labeling rules for the <code class="filename">/etc/</code> directory. Copying a file (without additional options) may not preserve the original context: </div><pre class="screen"> $ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 # cp file1 /etc/ $ ls -Z /etc/file1 -rw-r--r-- root root unconfined_u:object_r:etc_t:s0 /etc/file1 </pre><div class="para"> When <code class="filename">file1</code> is copied to <code class="filename">/etc/</code>, if <code class="filename">/etc/file1</code> does not exist, <code class="filename">/etc/file1</code> is created as a new file. As shown in the example above, <code class="filename">/etc/file1</code> is labeled with the <code class="computeroutput">etc_t</code> type, in accordance to default-labeling rules. </div><div class="para"> When a file is copied over an existing file, the existing file's context is preserved, unless the user specified <code class="command">cp</code> options to preserve the context of the original file, such as <code class="option">--preserve=context</code>. SELinux policy may prevent contexts from being preserved during copies. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Copying_Files_and_Directories-Copying_Without_Preserving_SELinux_Contexts">Copying Without Preserving SELinux Contexts</h5> When copying a file with the <code class="command">cp</code> command, if no options are given, the type is inherited from the targeted, parent directory: </div><pre class="screen"> $ touch file1 $ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 $ ls -dZ /var/www/html/ drwxr-xr-x root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/ # cp file1 /var/www/html/ $ ls -Z /var/www/html/file1 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 /var/www/html/file1 </pre><div class="para"> In this example, <code class="filename">file1</code> is created in a user's home directory, and is labeled with the <code class="computeroutput">user_home_t</code> type. The <code class="filename">/var/www/html/</code> directory is labeled with the <code class="computeroutput">httpd_sys_content_t</code> type, as shown with the <code class="command">ls -dZ /var/www/html/</code> command. When <code class="filename">file1</code> is copied to <code class="filename">/var/www/html/</code>, it inherits the <code class="computeroutput">httpd_sys_content_t</code> type, as shown with the <code class="command">ls -Z /var/www/html/file1</code> command. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Copying_Files_and_Directories-Preserving_SELinux_Contexts_When_Copying">Preserving SELinux Contexts When Copying</h5> Use the <code class="command">cp --preserve=context</code> command to preserve contexts when copying: </div><pre class="screen"> $ touch file1 $ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 $ ls -dZ /var/www/html/ drwxr-xr-x root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/ # cp --preserve=context file1 /var/www/html/ $ ls -Z /var/www/html/file1 -rw-r--r-- root root unconfined_u:object_r:user_home_t:s0 /var/www/html/file1 </pre><div class="para"> In this example, <code class="filename">file1</code> is created in a user's home directory, and is labeled with the <code class="computeroutput">user_home_t</code> type. The <code class="filename">/var/www/html/</code> directory is labeled with the <code class="computeroutput">httpd_sys_content_t</code> type, as shown with the <code class="command">ls -dZ /var/www/html/</code> command. Using the <code class="option">--preserve=context</code> option preserves SELinux contexts during copy operations. As shown with the <code class="command">ls -Z /var/www/html/file1</code> command, the <code class="filename">file1</code> <code class="computeroutput">user_home_t</code> type was preserved when the file was copied to <code class="filename">/var/www/html/</code>. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Copying_Files_and_Directories-Copying_and_Changing_the_Context">Copying and Changing the Context</h5> Use the <code class="command">cp -Z</code> command to change the destination copy's context. The following example was performed in the user's home directory: </div><pre class="screen"> $ touch file1 $ cp -Z system_u:object_r:samba_share_t:s0 file1 file2 $ ls -Z file1 file2 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 -rw-rw-r-- user1 group1 system_u:object_r:samba_share_t:s0 file2 $ rm file1 file2 </pre><div class="para"> In this example, the context is defined with the <code class="option">-Z</code> option. Without the <code class="option">-Z</code> option, <code class="filename">file2</code> would be labeled with the <code class="computeroutput">unconfined_u:object_r:user_home_t</code> context. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Copying_Files_and_Directories-Copying_a_File_Over_an_Existing_File">Copying a File Over an Existing File</h5> When a file is copied over an existing file, the existing file's context is preserved (unless an option is used to preserve contexts). For example: </div><pre class="screen"> # touch /etc/file1 # ls -Z /etc/file1 -rw-r--r-- root root unconfined_u:object_r:etc_t:s0 /etc/file1 # touch /tmp/file2 # ls -Z /tmp/file2 -rw-r--r-- root root unconfined_u:object_r:user_tmp_t:s0 /tmp/file2 # cp /tmp/file2 /etc/file1 # ls -Z /etc/file1 -rw-r--r-- root root unconfined_u:object_r:etc_t:s0 /etc/file1 </pre><div class="para"> In this example, two files are created: <code class="filename">/etc/file1</code>, labeled with the <code class="computeroutput">etc_t</code> type, and <code class="filename">/tmp/file2</code>, labeled with the <code class="computeroutput">user_tmp_t</code> type. The <code class="command">cp /tmp/file2 /etc/file1</code> command overwrites <code class="filename">file1</code> with <code class="filename">file2</code>. After copying, the <code class="command">ls -Z /etc/file1</code> command shows <code class="filename">file1</code> labeled with the <code class="computeroutput">etc_t</code> type, not the <code class="computeroutput">user_tmp_t</code> type from <code class="filename">/tmp/file2</code> that replaced <code class="filename">/etc/file1</code>. </div><div class="important"><h2>Important</h2><div class="para"> Copy files and directories, rather than moving them. This helps ensure they are labeled with the correct SELinux contexts. Incorrect SELinux contexts can prevent processes from accessing such files and directories. </div></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Making_Context_Mounts_Persistent.html"><strong>Prev</strong>5.9.5. Making Context Mounts Persistent</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Maintaining_SELinux_Labels_-Moving_Files_and_Directories.html"><strong>Next</strong>5.10.2. Moving Files and Directories</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.9. Mounting File Systems</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html" title="5.8. The file_t and default_t Types"/><link rel="next" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html" title="5.9.2. Changing the Default Context"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedo raproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html"><strong>Next</strong></a></li></ul><div class="section" title="5.9. Mounting File Systems"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems">5.9. Mounting File Systems</h2></div></div></div><div class="para"> By default, when a file system that supports extended attributes is mounted, the security context for each file is obtained from the <span class="emphasis"><em>security.selinux</em></span> extended attribute of the file. Files in file systems that do not support extended attributes are assigned a single, default security context from the policy configuration, based on file system type. </div><div class="para"> Use the <code class="command">mount -o context</code> command to override existing extended attributes, or to specify a different, default context for file systems that do not support extended attributes. This is useful if you do not trust a file system to supply the correct attributes, for example, removable media used in multiple systems. The <code class="command">mount -o context</code> command can also be used to support labeling for file systems that do not support extended attributes, such as File Allocation Table (FAT) or NFS file systems. The context specified with the <code class="option">context</code> is not written to disk: the original contexts are preserved, and are seen when mounting without a <code class="option">context</code> option (if the file system had extended attributes in the first place). </div><div class="para"> For further information about file system labeling, refer to James Morris's "Filesystem Labeling in SELinux" article: <a href="http://www.linuxjournal.com/article/7426">http://www.linuxjournal.com/article/7426</a>. </div><div class="section" title="5.9.1. Context Mounts"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-Mounting_File_Systems-Context_Mounts">5.9.1. Context Mounts</h3></div></div></div><div class="para"> To mount a file system with the specified context, overriding existing contexts if they exist, or to specify a different, default context for a file system that does not support extended attributes, as the Linux root user, use the <code class="command">mount -o context=<em class="replaceable"><code>SELinux_user:role:type:level</code></em></code> command when mounting the desired file system. Context changes are not written to disk. By default, NFS mounts on the client side are labeled with a default context defined by policy for NFS file systems. In common policies, this default context uses the <code class="computeroutput">nfs_t</code> type. Without additional mount options, this may prevent sharing NFS file systems via other services, such as the Apache HTTP Server. The following example mounts an NFS file system so that it can be shared via the Apache HTTP Server: </div><div class="para"> <pre class="screen"># mount server:/export /local/mount/point -o\ context="system_u:object_r:httpd_sys_content_t:s0" </pre> </div><div class="para"> Newly-created files and directories on this file system appear to have the SELinux context specified with <code class="option">-o context</code>; however, since context changes are not written to disk for these situations, the context specified with the <code class="option">context</code> option is only retained if the <code class="option">context</code> option is used on the next mount, and if the same context is specified. </div><div class="para"> Type Enforcement is the main permission control used in SELinux targeted policy. For the most part, SELinux users and roles can be ignored, so, when overriding the SELinux context with <code class="option">-o context</code>, use the SELinux <code class="computeroutput">system_u</code> user and <code class="computeroutput">object_r</code> role, and concentrate on the type. If you are not using the MLS policy or multi-category security, use the <code class="computeroutput">s0</code> level. </div><div class="note"><h2>Note</h2><div class="para"> When a file system is mounted with a <code class="option">context</code> option, context changes (by users and processes) are prohibited. For example, running <code class="command">chcon</code> on a file system mounted with a <code class="option">context</code> option results in a <code class="computeroutput">Operation not supported</code> error. </div></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html"><strong>Prev</strong>5.8. The file_t and default_t Types</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Mounting_File_Systems-Changing_the_Default_Context.html"><strong>Next</strong>5.9.2. Changing the Default Context</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.7. SELinux Contexts - Labeling Files</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html" title="5.6.3. Booleans for NFS and CIFS"/><link rel="next" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html" title="5.7.2. Persistent Changes: semanage fcontext"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" hre f="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html"><strong>Next</strong></a></li></ul><div class="section" title="5.7. SELinux Contexts - Labeling Files"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Contexts_Labeling_Files">5.7. SELinux Contexts - Labeling Files</h2></div></div></div><div class="para"> On systems running SELinux, all processes and files are labeled in a way that represents security-relevant information. This information is called the SELinux context. For files, this is viewed using the <code class="command">ls -Z</code> command: </div><pre class="screen">$ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre><div class="para"> In this example, SELinux provides a user (<code class="computeroutput">unconfined_u</code>), a role (<code class="computeroutput">object_r</code>), a type (<code class="computeroutput">user_home_t</code>), and a level (<code class="computeroutput">s0</code>). This information is used to make access control decisions. On DAC systems, access is controlled based on Linux user and group IDs. SELinux policy rules are checked after DAC rules. SELinux policy rules are not used if DAC rules deny access first. </div><div class="para"> There are multiple commands for managing the SELinux context for files, such as <code class="command">chcon</code>, <code class="command">semanage fcontext</code>, and <code class="command">restorecon</code>. </div><div class="section" title="5.7.1. Temporary Changes: chcon"><div class="titlepage"><div><div><h3 class="title" id="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Temporary_Changes_chcon">5.7.1. Temporary Changes: chcon</h3></div></div></div><div class="para"> The <code class="command">chcon</code> command changes the SELinux context for files. However, changes made with the <code class="command">chcon</code> command do not survive a file system relabel, or the execution of the <code class="command">/sbin/restorecon</code> command. SELinux policy controls whether users are able to modify the SELinux context for any given file. When using <code class="command">chcon</code>, users provide all or part of the SELinux context to change. An incorrect file type is a common cause of SELinux denying access. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Temporary_Changes_chcon-Quick_Reference">Quick Reference</h5> <div class="itemizedlist"><ul><li class="listitem"><div class="para"> Run the <code class="command">chcon -t <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>file-name</code></em></code> command to change the file type, where <em class="replaceable"><code>type</code></em> is a type, such as <code class="computeroutput">httpd_sys_content_t</code>, and <em class="replaceable"><code>file-name</code></em> is a file or directory name. </div></li><li class="listitem"><div class="para"> Run the <code class="command">chcon -R -t <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>directory-name</code></em></code> command to change the type of the directory and its contents, where <em class="replaceable"><code>type</code></em> is a type, such as <code class="computeroutput">httpd_sys_content_t</code>, and <em class="replaceable"><code>directory-name</code></em> is a directory name. </div></li></ul></div> </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Temporary_Changes_chcon-Changing_a_Files_or_Directorys_Type">Changing a File's or Directory's Type</h5> The following example demonstrates changing the type, and no other attributes of the SELinux context: </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> Run the <code class="command">cd</code> command without arguments to change into your home directory. </div></li><li class="listitem"><div class="para"> Run the <code class="command">touch file1</code> command to create a new file. Use the <code class="command">ls -Z file1</code> command to view the SELinux context for <code class="filename">file1</code>: </div><pre class="screen">$ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:user_home_t:s0 file1 </pre><div class="para"> In this example, the SELinux context for <code class="filename">file1</code> includes the SELinux <code class="computeroutput">unconfined_u</code> user, <code class="computeroutput">object_r</code> role, <code class="computeroutput">user_home_t</code> type, and the <code class="computeroutput">s0</code> level. For a description of each part of the SELinux context, refer to <a class="xref" href="chap-Security-Enhanced_Linux-SELinux_Contexts.html" title="Chapter 3. SELinux Contexts">Chapter 3, <i>SELinux Contexts</i></a>. </div></li><li class="listitem"><div class="para"> Run the <code class="command">chcon -t samba_share_t file1</code> command to change the type to <code class="computeroutput">samba_share_t</code>. The <code class="option">-t</code> option only changes the type. View the change with <code class="command">ls -Z file1</code>: </div><pre class="screen">$ ls -Z file1 -rw-rw-r-- user1 group1 unconfined_u:object_r:samba_share_t:s0 file1 </pre></li><li class="listitem"><div class="para"> Use the <code class="command">/sbin/restorecon -v file1</code> command to restore the SELinux context for the <code class="filename">file1</code> file. Use the <code class="option">-v</code> option to view what changes: </div><pre class="screen">$ /sbin/restorecon -v file1 restorecon reset file1 context unconfined_u:object_r:samba_share_t:s0->system_u:object_r:user_home_t:s0 </pre><div class="para"> In this example, the previous type, <code class="computeroutput">samba_share_t</code>, is restored to the correct, <code class="computeroutput">user_home_t</code> type. When using targeted policy (the default SELinux policy in Fedora 11), the <code class="command">/sbin/restorecon</code> command reads the files in the <code class="filename">/etc/selinux/targeted/contexts/files/</code> directory, to see which SELinux context files should have. </div></li></ol></div><div class="para"> The example in this section works the same for directories, for example, if <code class="filename">file1</code> was a directory. </div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Temporary_Changes_chcon-Changing_a_Directory_and_its_Contents_Types">Changing a Directory and its Contents Types</h5> The following example demonstrates creating a new directory, and changing the directory's file type (along with its contents) to a type used by the Apache HTTP Server. The configuration in this example is used if you want Apache HTTP Server to use a different document root (instead of <code class="filename">/var/www/html/</code>): </div><div class="orderedlist"><ol><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">mkdir /web</code> command to create a new directory, and then the <code class="command">touch /web/file{1,2,3}</code> command to create 3 empty files (<code class="filename">file1</code>, <code class="filename">file2</code>, and <code class="filename">file3</code>). The <code class="filename">/web/</code> directory and files in it are labeled with the <code class="computeroutput">default_t</code> type: </div><pre class="screen"># ls -dZ /web drwxr-xr-x root root unconfined_u:object_r:default_t:s0 /web # ls -lZ /web -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:default_t:s0 file3 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">chcon -R -t httpd_sys_content_t /web/</code> command to change the type of the <code class="filename">/web/</code> directory (and its contents) to <code class="computeroutput">httpd_sys_content_t</code>: </div><pre class="screen"># chcon -R -t httpd_sys_content_t /web/ # ls -dZ /web/ drwxr-xr-x root root unconfined_u:object_r:httpd_sys_content_t:s0 /web/ # ls -lZ /web/ -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file1 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file2 -rw-r--r-- root root unconfined_u:object_r:httpd_sys_content_t:s0 file3 </pre></li><li class="listitem"><div class="para"> As the Linux root user, run the <code class="command">/sbin/restorecon -R -v /web/</code> command to restore the default SELinux contexts: </div><pre class="screen"># /sbin/restorecon -R -v /web/ restorecon reset /web context unconfined_u:object_r:httpd_sys_content_t:s0->system_u:object_r:default_t:s0 restorecon reset /web/file2 context unconfined_u:object_r:httpd_sys_content_t:s0->system_u:object_r:default_t:s0 restorecon reset /web/file3 context unconfined_u:object_r:httpd_sys_content_t:s0->system_u:object_r:default_t:s0 restorecon reset /web/file1 context unconfined_u:object_r:httpd_sys_content_t:s0->system_u:object_r:default_t:s0 </pre></li></ol></div><div class="para"> Refer to the <span class="citerefentry"><span class="refentrytitle">chcon</span>(1)</span> manual page for further information about <code class="command">chcon</code>. </div><div class="note"><h2>Note</h2><div class="para"> Type Enforcement is the main permission control used in SELinux targeted policy. For the most part, SELinux users and roles can be ignored. </div></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Booleans-Booleans_for_NFS_and_CIFS.html"><strong>Prev</strong>5.6.3. Booleans for NFS and CIFS</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html"><strong>Next</strong>5.7.2. Persistent Changes: semanage fcontext</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.5. SELinux Modes</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html" title="5.4.2. Disabling SELinux"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html" title="5.6. Booleans"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" a lt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html"><strong>Next</strong></a></li></ul><div class="section" title="5.5. SELinux Modes"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-SELinux_Modes">5.5. SELinux Modes</h2></div></div></div><div class="para"> SELinux has three modes: </div><div class="itemizedlist"><ul><li class="listitem"><div class="para"> Enforcing: SELinux policy is enforced. SELinux denies access based on SELinux policy rules. </div></li><li class="listitem"><div class="para"> Permissive: SELinux policy is not enforced. SELinux does not deny access, but denials are logged for actions that would have been denied if running in enforcing mode. </div></li><li class="listitem"><div class="para"> Disabled: SELinux is disabled. Only DAC rules are used. </div></li></ul></div><div class="para"> Use the <code class="command">/usr/sbin/setenforce</code> command to change between enforcing and permissive mode. Changes made with <code class="command">/usr/sbin/setenforce</code> do not persist across reboots. To change to enforcing mode, as the Linux root user, run the <code class="command">/usr/sbin/setenforce 1</code> command. To change to permissive mode, run the <code class="command">/usr/sbin/setenforce 0</code> command. Use the <code class="command">/usr/sbin/getenforce</code> command to view the current SELinux mode. </div><div class="para"> Persistent mode changes are covered in <a class="xref" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Enabling_and_Disabling_SELinux.html" title="5.4. Enabling and Disabling SELinux">Section 5.4, “Enabling and Disabling SELinux”</a>. </div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-Enabling_and_Disabling_SELinux-Disabling_SELinux.html"><strong>Prev</strong>5.4.2. Disabling SELinux</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Booleans.html"><strong>Next</strong>5.6. Booleans</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.8. The file_t and default_t Types</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html" title="5.7.2. Persistent Changes: semanage fcontext"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html" title="5.9. Mounting File Systems"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href ="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html"><strong>Next</strong></a></li></ul><div class="section" title="5.8. The file_t and default_t Types"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-The_file_t_and_default_t_Types">5.8. The file_t and default_t Types</h2></div></div></div><div class="para"> For file systems that support extended attributes, when a file that lacks an SELinux context on disk is accessed, it is treated as if it had a default context as defined by SELinux policy. In common policies, this default context uses the <code class="computeroutput">file_t</code> type. This should be the only use of this type, so that files without a context on disk can be distinguished in policy, and generally kept inaccessible to confined domains. The <code class="computeroutput">file_t</code> type should not exist on correctly-labeled file systems, because all files on a system running SELinux should have an SELinux context, and the <code class="computeroutput">file_t</code> type is never used in file-context configuration<sup>[<a id="d0e3772" href="#ftn.d0e3772" class="footnote">11</a>]</sup>. </div><div class="para"> The <code class="computeroutput">default_t</code> type is used on files that do not match any other pattern in file-context configuration, so that such files can be distinguished from files that do not have a context on disk, and generally kept inaccessible to confined domains. If you create a new top-level directory, such as <code class="filename">/mydirectory/</code>, this directory may be labeled with the <code class="computeroutput">default_t</code> type. If services need access to such a directory, update the file-contexts configuration for this location. Refer to <a class="xref" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html" title="5.7.2. Persistent Changes: semanage fcontext">Section 5.7.2, “Persistent Changes: semanage fcontext”</a> for details on adding a context to the file-context configuration. </div><div class="footnotes"><br/><hr/><div class="footnote"><p><sup>[<a id="ftn.d0e3772" href="#d0e3772" class="para">11</a>] </sup> Files in <code class="filename">/etc/selinux/targeted/contexts/files/</code> define contexts for files and directories. Files in this directory are read by <code class="command">restorecon</code> and <code class="command">setfiles</code> to restore files and directories to their default contexts. </p></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="sect-Security-Enhanced_Linux-SELinux_Contexts_Labeling_Files-Persistent_Changes_semanage_fcontext.html"><strong>Prev</strong>5.7.2. Persistent Changes: semanage fcontext</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Mounting_File_Systems.html"><strong>Next</strong>5.9. Mounting File Systems</a></li></ul></body></html>
--- NEW FILE sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used.html --- <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><title>5.2. Which Log File is Used</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css"/><meta name="generator" content="publican"/><meta name="package" content="Fedora-Security-Enhanced_Linux-12-en-US-1.4-1"/><link rel="home" href="index.html" title="Security-Enhanced Linux"/><link rel="up" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="prev" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html" title="Chapter 5. Working with SELinux"/><link rel="next" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html" title="5.3. Main Configuration File"/></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site"/></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images /image_right.png" alt="Documentation Site"/></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html"><strong>Next</strong></a></li></ul><div class="section" title="5.2. Which Log File is Used"><div class="titlepage"><div><div><h2 class="title" id="sect-Security-Enhanced_Linux-Working_with_SELinux-Which_Log_File_is_Used">5.2. Which Log File is Used</h2></div></div></div><div class="para"> In Fedora 12, the <span class="package">setroubleshoot-server</span> and <span class="package">audit</span> packages are installed if packages are not removed from the default package selection. These packages include the <code class="systemitem">setroubleshootd</code> and <code class="systemitem">auditd</code> daemons respectively. These daemons run by default. </div><div class="para"> SELinux denial messages, such as the following, are written to <code class="filename">/var/log/audit/audit.log</code> by default: </div><pre class="screen">type=AVC msg=audit(1223024155.684:49): avc: denied { getattr } for pid=2000 comm="httpd" path="/var/www/html/file1" dev=dm-0 ino=399185 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=system_u:object_r:samba_share_t:s0 tclass=file </pre><div class="para"> Also, if <code class="systemitem">setroubleshootd</code> is running, which it is by default, denial messages from <code class="filename">/var/log/audit/audit.log</code> are translated to an easier-to-read form and sent to <code class="filename">/var/log/messages</code>: </div><pre class="screen">May 7 18:55:56 localhost setroubleshoot: SELinux is preventing httpd (httpd_t) "getattr" to /var/www/html/file1 (samba_share_t). For complete SELinux messages. run sealert -l de7e30d6-5488-466d-a606-92c9f40d316d </pre><div class="para"> Denial messages are sent to a different location, depending on which daemons are running: </div><div class="segmentedlist"><table border="0"><thead><tr class="segtitle"><th>Daemon</th><th>Log Location</th></tr></thead><tbody><tr class="seglistitem"><td class="seg">auditd on</td><td class="seg"><code class="filename">/var/log/audit/audit.log</code></td></tr><tr class="seglistitem"><td class="seg">auditd off; rsyslogd on</td><td class="seg"><code class="filename">/var/log/messages</code></td></tr><tr class="seglistitem"><td class="seg">setroubleshootd, rsyslogd, and auditd on</td><td class="seg"><code class="filename">/var/log/audit/audit.log</code>. Easier-to-read denial messages also sent to <code class="filename">/var/log/messages</code></td></tr></tbody></table></div><div class="formalpara"><h5 class="formalpara" id="form-Security-Enhanced_Linux-Which_Log_File_is_Used-Starting_Daemons_Automatically">Starting Daemons Automatically</h5> To configure the <code class="systemitem">auditd</code>, <code class="systemitem">rsyslogd</code>, and <code class="systemitem">setroubleshootd</code> daemons to automatically start at boot, run the following commands as the Linux root user: </div><pre class="screen">/sbin/chkconfig --levels 2345 auditd on </pre><pre class="screen">/sbin/chkconfig --levels 2345 rsyslog on </pre><pre class="screen">/sbin/chkconfig --levels 345 setroubleshoot on </pre><div class="para"> Use the <code class="command">service <em class="replaceable"><code>service-name</code></em> status</code> command to check if these services are running, for example: </div><pre class="screen"> $ /sbin/service auditd status auditd (pid <em class="replaceable"><code>1318</code></em>) is running... </pre><div class="para"> If the above services are not running (<code class="computeroutput"><em class="replaceable"><code>service-name</code></em> is stopped</code>), use the <code class="command">service <em class="replaceable"><code>service-name</code></em> start</code> command as the Linux root user to start them. For example: </div><pre class="screen"> # /sbin/service setroubleshoot start Starting setroubleshootd: [ OK ] </pre></div><ul class="docnav"><li class="previous"><a accesskey="p" href="chap-Security-Enhanced_Linux-Working_with_SELinux.html"><strong>Prev</strong>Chapter 5. Working with SELinux</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="sect-Security-Enhanced_Linux-Working_with_SELinux-Main_Configuration_File.html"><strong>Next</strong>5.3. Main Configuration File</a></li></ul></body></html>
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