On 05/25/2017 01:21 PM, Stephen Smalley wrote:
On Thu, 2017-05-25 at 12:19 -0700, Bill D wrote:
Hello Phil:
Thank you for the response. Your suggested fix resolved the error.
However, I am unable to get the desired effect.
I am not able to prevent a Linux user from running/accessing a Java JAR file using SELinux categories.
I would appreciate any other hints to make this work.
Following are the details of what I did:
# semanage user -l
Labeling MLS/ MLS/
SELinux User Prefix MCS Level MCS Range SELinux Roles
git_shell_u user SystemLow SystemLow git_shell_r guest_u user SystemLow SystemLow guest_r root user SystemLow SystemLow-SystemHigh staff_r sysadm_r system_r unconfined_r staff_u user SystemLow SystemLow-SystemHigh staff_r sysadm_r system_r unconfined_r sysadm_u user SystemLow SystemLow-SystemHigh sysadm_r system_u user SystemLow SystemLow-SystemHigh system_r unconfined_r unconfined_u user SystemLow SystemLow-SystemHigh system_r unconfined_r user_u user SystemLow SystemLow user_r xguest_u user SystemLow SystemLow xguest_r
# semanage user -m -r s0-s0:c0.c1023 user_u
# semanage user -l
Labeling MLS/ MLS/
SELinux User Prefix MCS Level MCS Range SELinux Roles
git_shell_u user SystemLow SystemLow git_shell_r guest_u user SystemLow SystemLow guest_r root user SystemLow SystemLow-SystemHigh staff_r sysadm_r system_r unconfined_r staff_u user SystemLow SystemLow-SystemHigh staff_r sysadm_r system_r unconfined_r sysadm_u user SystemLow SystemLow-SystemHigh sysadm_r system_u user SystemLow SystemLow-SystemHigh system_r unconfined_r unconfined_u user SystemLow SystemLow-SystemHigh system_r unconfined_r user_u user SystemLow SystemLow-SystemHigh user_r xguest_u user SystemLow SystemLow xguest_r
# cat setrans.conf
# # Multi-Category Security translation table for SELinux # # Uncomment the following to disable translation libary # disable=1 # # Objects can be categorized with 0-1023 categories defined by the admin. # Objects can be in more than one category at a time. # Categories are stored in the system as c0-c1023. Users can use this # table to translate the categories into a more meaningful output. # Examples: # s0:c0=CompanyConfidential # s0:c1=PatientRecord # s0:c2=Unclassified # s0:c3=TopSecret # s0:c1,c3=CompanyConfidentialRedHat s0:c0=NetworkAdministrator s0:c1=Operator s0=SystemLow s0-s0:c0.c1023=SystemLow-SystemHigh s0:c0.c1023=SystemHigh
# service mcstrans restart Stopping mcstransd: [ OK ] Starting mcstransd: [ OK ]
# chcat -L s0:c0 NetworkAdministrator s0:c1 Operator s0 SystemLow s0-s0:c0.c1023 SystemLow-SystemHigh s0:c0.c1023 SystemHigh
# useradd foo
# useradd bar
# passwd foo Changing password for user foo. New password: Retype new password: passwd: all authentication tokens updated successfully.
# passwd bar Changing password for user bar. New password: Retype new password: passwd: all authentication tokens updated successfully.
# semanage login -a foo
# semanage login -a bar
# chcat -l -- +NetworkAdministrator foo
# chcat -l -- +Operator bar
# chcat -L -l bar foo bar: s0:c0.c1023,c1 <===== why is it not just s0:c1? foo: s0:c0.c1023,c0 <===== why is it not just just s0:c0?
# chcat -- +NetworkAdministrator /usr/local/soup/bin/Foo.jar
# ls -Z /usr/local/soup/bin/Foo.jar -rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar
Now Login as the 'foo' Linux user and notice that it can run Foo.jar as expected
$ whoami foo
$ id -Z user_u:user_r:user_t:SystemLow-SystemHigh
$ ls -Z /usr/local/soup/bin/Foo.jar -rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar
$ java -jar /usr/local/soup/bin/Foo.jar Hello Foo
Now login as the 'bar' Linux user and notice that it can also run Foo.jar which is NOT expected
$ whoami bar
$ id -Z user_u:user_r:user_t:SystemLow-SystemHigh
$ ls -Z /usr/local/soup/bin/Foo.jar -rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar
$ java -jar /usr/local/soup/bin/Foo.jar Hello Foo
Why is Linux user 'bar' able to run/access Foo.jar when its category doesn't match Foo.jar's category?
Red Hat changed the way MCS works in modern versions of RHEL. It went from being a user-centric model to being something they only use to separate sandboxes, containers, VMs, openshift instances, etc. So a domain is only restricted by MCS if it is specifically marked as being MCS constrained.
How to mark a file's domain/type as MCS constrained? Or is that not possible?
MLS on the other hand is still applied to all domains except those explicitly exempted (trusted to cross levels).
I would greatly appreciate any hints on how to use MLS to control file access.
Thanks!
Bill
Following is how to create the Foo.jar file:
$ cat Foo.java public class Foo { public static void main(String[] args) { System.out.println("Hello Foo"); } }
$ cat manifest.txt Main-Class:
$ javac Foo.java
$ jar cvfe Foo.jar Foo Foo.class added manifest adding: Foo.class(in = 409) (out= 282)(deflated 31%)
Best Regards,
Bill
On 05/24/2017 04:39 PM, Philip Seeley wrote:
Hi Bill,
I think this was my mistake in transcribing. The user_u line after the "semanage user -m" command should be: user_u user SystemLow SystemLow- SystemHigh user_r
So the command should have been:
semanage user -m -r s0-s0:c0.c1023 user_u
Or even:
semanage user -m -r SystemLow-SystemHigh user_u
Appologies for that.
Phil
Bill D ---25/05/2017 02:28:19---Hello Phil, I have tried your suggestion of extending the user_u definition without
From: Bill D littus@icloud.com To: Philip Seeley pseeley@au1.ibm.com Cc: littus@icloud.com, selinux@lists.fedoraproject.org Date: 25/05/2017 02:28 Subject: Re: Controlling execution of Java JAR files with SELinux RBAC
Hello Phil, I have tried your suggestion of extending the user_u definition without success: # semanage user -l
Labeling MLS/
MLS/ SELinux User Prefix MCS Level MCS Range SELinux Roles
git_shell_u user SystemLow SystemLow git_shell_r guest_u user SystemLow SystemLow guest_r root user SystemLow SystemLow- SystemHigh staff_r sysadm_r system_r unconfined_r staff_u user SystemLow SystemLow- SystemHigh staff_r sysadm_r system_r unconfined_r sysadm_u user SystemLow SystemLow- SystemHigh sysadm_r system_u user SystemLow SystemLow- SystemHigh system_r unconfined_r unconfined_u user SystemLow SystemLow- SystemHigh system_r unconfined_r user_u user SystemLow SystemLow user_r xguest_u user SystemLow SystemLow xguest_r # semanage user -m -r s0:c0.c1023 user_u # semanage user -l
Labeling MLS/
MLS/ SELinux User Prefix MCS Level MCS Range SELinux Roles
git_shell_u user SystemLow SystemLow git_shell_r guest_u user SystemLow SystemLow guest_r root user SystemLow SystemLow- SystemHigh staff_r sysadm_r system_r unconfined_r staff_u user SystemLow SystemLow- SystemHigh staff_r sysadm_r system_r unconfined_r sysadm_u user SystemLow SystemLow- SystemHigh sysadm_r system_u user SystemLow SystemLow- SystemHigh system_r unconfined_r unconfined_u user SystemLow SystemLow- SystemHigh system_r unconfined_r user_u user SystemLow SystemHigh user_r xguest_u user SystemLow SystemLow xguest_r # useradd kate # passwd kate Changing password for user kate. New password: Retype new password: passwd: all authentication tokens updated successfully. # semanage login -a kate libsemanage.validate_handler: MLS range s0 for Unix user regularuser exceeds allowed range s0:c0.c1023 for SELinux user user_u (No such file or directory). libsemanage.validate_handler: seuser mapping [regularuser -> (user_u, s0)] is invalid (No such file or directory). libsemanage.dbase_llist_iterate: could not iterate over records (No such file or directory). /usr/sbin/semanage: Could not commit semanage transaction I would greatly appreciate any other hints to make this work. Regards, Bill On 5/23/2017 8:42 PM, Philip Seeley wrote: Hi Bill,
This is probably because the default RHEL6 configuration does not include any categories in the user_u SELinux user's range:
# semanage user -l
Labeling MLS/ MLS/
SELinux User Prefix MCS Level MCS Range SELinux Roles
guest_u user s0 s0 guest_r root user s0 s0-s0:c0.c1023 staff_r sysadm_r system_r unconfined_r staff_u user s0 s0-s0:c0.c1023 staff_r sysadm_r system_r unconfined_r sysadm_u user s0 s0-s0:c0.c1023 sysadm_r system_u user s0 s0-s0:c0.c1023 system_r unconfined_r unconfined_u user s0 s0-s0:c0.c1023 system_r unconfined_r user_u user s0 s0 user_r
You probably have to extend the user definition to include the categories you're using. As an example, this gives all categories:
# semanage user -m -r s0:c0.c1023 user_u
# semanage user -l
Labeling MLS/ MLS/
SELinux User Prefix MCS Level MCS Range SELinux Roles
guest_u user s0 s0 guest_r root user s0 s0-s0:c0.c1023 staff_r sysadm_r system_r unconfined_r staff_u user s0 s0-s0:c0.c1023 staff_r sysadm_r system_r unconfined_r sysadm_u user s0 s0-s0:c0.c1023 sysadm_r system_u user s0 s0-s0:c0.c1023 system_r unconfined_r unconfined_u user s0 s0-s0:c0.c1023 system_r unconfined_r user_u user s0 s0:c0.c1023 user_r
Hope that helps.
Phil
Bill Durant ---24/05/2017 12:34:53---Hello Phil: Thank you for the suggestion. I have tried the steps from the URL that
From: Bill Durant littus@icloud.com To: Philip Seeley pseeley@au1.ibm.com Cc: littus@icloud.com, selinux@lists.fedoraproject.org Date: 24/05/2017 12:34 Subject: Re: Controlling execution of Java JAR files with SELinux RBAC
Hello Phil: Thank you for the suggestion. I have tried the steps from the URL that you provided without success. I get an error when I try to assign Linux user mary to an SELinux login as follows: # cat /etc/redhat-release CentOS release 6.9 (Final)
;;; Add "s0:c0=NetworkAdministrator" and "s0:c1=Operator" to /etc/selinux/targeted/setrans.conf
# cat /etc/selinux/targeted/setrans.conf # # Multi-Category Security translation table for SELinux # # Uncomment the following to disable translation libary # disable=1 # # Objects can be categorized with 0-1023 categories defined by the admin. # Objects can be in more than one category at a time. # Categories are stored in the system as c0-c1023. Users can use this # table to translate the categories into a more meaningful output. # Examples: # s0:c0=CompanyConfidential # s0:c1=PatientRecord # s0:c2=Unclassified # s0:c3=TopSecret # s0:c1,c3=CompanyConfidentialRedHat s0:c0=NetworkAdministrator s0:c1=Operator s0=SystemLow s0-s0:c0.c1023=SystemLow-SystemHigh s0:c0.c1023=SystemHigh
# service mcstrans start
# chcat -L s0:c0 NetworkAdministrator s0:c1 Operator s0 SystemLow s0-s0:c0.c1023 SystemLow-SystemHigh s0:c0.c1023 SystemHigh
# useradd mary # passwd mary Changing password for user mary. New password: Retype new password: passwd: all authentication tokens updated successfully.
# semanage login -a mary
# chcat -l -- +NetworkAdministrator mary libsemanage.validate_handler: MLS range s0-s0:c0 for Unix user mary exceeds allowed range s0 for SELinux user user_u (No such file or directory). libsemanage.validate_handler: seuser mapping [mary -> (user_u, s0- s0:c0)] is invalid (No such file or directory). libsemanage.dbase_llist_iterate: could not iterate over records (No such file or directory). /usr/sbin/semanage: Could not commit semanage transaction I would appreciate any hints on how to resolve that error. Thanks! Bill
On 05/23/2017 05:49 PM, Philip Seeley wrote: Hi Bill,
Have you thought about using categories?
https://www.centos.org/docs/5/html/Deployment_Guide-en-US/sec-mcs-g etstarted.html
Cheers
Phil
Bill D ---24/05/2017 09:52:00---Greetings: I have been trying to figure out how to control the execution of Java
From: Bill D littus@icloud.com To: selinux@lists.fedoraproject.org Cc: littus@icloud.com Date: 24/05/2017 09:52 Subject: Controlling execution of Java JAR files with SELinux RBAC
Greetings:
I have been trying to figure out how to control the execution of Java JAR files with SELinux RBAC.
I have two Linux users named joe and mary and two Java JAR files named jack.jar and mary.jar.
Here is how jack executes jack.jar: java -jar jack.jar
Here is how mary executes mary.jar: java -jar mary.jar
I would like SELinux RBAC to prevent jack from executing mary.jar and prevent mary from executing jack.jar.
How to configure SELinux RBAC to make that happen?
I have tried various approaches without success. I have also tried the steps in http://forums.fedoraforum.org/archive/index.php/t-222938.h tml without success.
I would greatly appreciate any hints.
Regards,
Bill
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