SELinux constrain policy for escalated root user

[Daniel J Walsh]

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On 09/03/2013 02:28 AM, Anamitra Dutta Majumdar (anmajumd) wrote:
> We need to constrain a tomcat escalated root user from executing "useradd"
> and "semanage" commands on RHEL6.
> 
> Can we add a SELinux constraint policy to achieve  the same?
> 
> A tomcat escalated root user (I.e when a "tomcat" user escalates to the
> "root" user on the system) has the following security context
> 
> uid=0(*root*) gid=0(root) 
> groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel) 
> context=system_u:system_r:*tomcatd_t*:SystemLow-SystemHigh
> 
> The logic of this constraint should be be as follows..
> 
> If id="root" and source type="tomcatd_t"
> 
> Then disallow domain transition to both "useradd_/exec_t" as well as 
> "semanage_/exec_t"
> 
> 1. Is this something doable through an SELinux constrain policy. 2. If so
> what should be the syntax of the policy.
> 
> 
> -- selinux mailing list selinux at lists.fedoraproject.org 
> https://admin.fedoraproject.org/mailman/listinfo/selinux
> 
This is a type enforcement issue not a constraint issue. tomcatd can be
prevented from running useradd_t regardless of its UID, and more importantly
should not be allowed to write /etc/passwd (etc_t) or /etc/shadow (shadow_t).

No constraint needed to do this.  Just don't allow t to write etc_t and shadow_t.
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