help adding a type attribute to a domain

Dominick Grift domg472 at gmail.com
Fri Mar 11 16:54:42 UTC 2011


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On 03/11/2011 05:52 PM, Daniel J Walsh wrote:
> On 03/11/2011 11:48 AM, Dominick Grift wrote:
>> On 03/11/2011 05:42 PM, Daniel J Walsh wrote:
>>> On 03/11/2011 10:57 AM, Maria Iano wrote:
>>>> I'm getting a denial that audit2why says is due to constraints.  
>>>> Sesearch does show that the action has an allow rule.
> 
>>>> Here are the audit messages:
> 
>>>> host=eng-vocngcn03.eng.gci type=AVC msg=audit(1299844473.770:740848):  
>>>> avc:  denied  { sigkill } for  pid=22927 comm="kill"  
>>>> scontext=system_u:system_r:rgmanager_t:s0  
>>>> tcontext=system_u:system_r:unconfined_t:s0-s0:c0.c1023 tclass=process
> 
>>>> host=eng-vocngcn03.eng.gci type=SYSCALL  
>>>> msg=audit(1299844473.770:740848): arch=c000003e syscall=62 success=yes  
>>>> exit=0 a0=19ba a1=9 a2=9 a3=0 items=0 ppid=20173 pid=22927  
>>>> auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0  
>>>> fsgid=0 tty=(none) ses=4294967295 comm="kill" exe="/bin/kill"  
>>>> subj=system_u:system_r:rgmanager_t:s0 key=(null)
> 
>>> You have rgmanager sending a kill signal to a process running as
>>> unconfined_t
> 
>> There is no proof that its rgmanager doing that imho. Since rgmanager_t
>> is an unconfined_domain it could be any generic application started by a
>> process running in the rgmanager_t domain (eventually started by rgmanager)
> 
>>> I would bet this process is running with the wrong domain.  I don't
>>> think you want rgmanager_t sending kill signals to user processes.
> 
>>> What process was it trying to kill?
>>>> Here is the result of running sesearch on that same server:
> 
>>>> [root at eng-vocngcn03]# sesearch --allow -s rgmanager_t -t unconfined_t - 
>>>> c process -p sigkill
>>>> Found 1 av rules:
>>>>     allow rgmanager_t unconfined_t : process { sigchld sigkill };
> 
>>>> Here is what audit2why says:
> 
>>>> [root at eng-vocngcn03]# echo 'host=eng-vocngcn03.eng.gci type=AVC  
>>>> msg=audit(1299844473.770:740848): avc:  denied  { sigkill } for   
>>>> pid=22927 comm="kill" scontext=system_u:system_r:rgmanager_t:s0  
>>>> tcontext=system_u:system_r:unconfined_t:s0-s0:c0.c1023 tclass=process'  
>>>> | audit2why
>>>> host=eng-vocngcn03.eng.gci type=AVC msg=audit(1299844473.770:740848):  
>>>> avc:  denied  { sigkill } for  pid=22927 comm="kill"  
>>>> scontext=system_u:system_r:rgmanager_t:s0  
>>>> tcontext=system_u:system_r:unconfined_t:s0-s0:c0.c1023 tclass=process
>>>>          Was caused by:
>>>>                  Constraint violation.
>>>>                  Check policy/constraints.
>>>>                  Typically, you just need to add a type attribute to  
>>>> the domain to satisfy the constraint.
> 
>>>> This is a RHEL 5.5 server and it doesn't have the policy source and I  
>>>> don't see an rpm available with that. I can't find a constraints file,  
>>>> and I assume that's because it doesn't have the source. I'm trying to  
>>>> work out how to add the necessary type attribute to the domain. I do  
>>>> have a custom policy on the system. It's very long so I'll include the  
>>>> relevant pieces:
> 
>>>> require {
>>>>          type rgmanager_t;
>>>>          type unconfined_t;
>>>>          class process { sigkill signal };
>>>> ..<snip>...
>>>> }
> 
>>>> allow rgmanager_t unconfined_t:process sigkill;
>>>> ..<snip>...
> 
>>>> Is there something I can add to my policy to resolve the constraints  
>>>> issue?
> 
>>>> Thanks,
>>>> Maria
>>>> --
>>>> selinux mailing list
>>>> selinux at lists.fedoraproject.org
>>>> https://admin.fedoraproject.org/mailman/listinfo/selinux
> 
> 
> 
> 
> Right although unconifned_t:s0-s0:c0.c1023 is almost assured a logged in
> user.  It could have been a shell secript started via a remove ssh call
> 
> If an init script had started an unconfined_exec_t executable it would
> probably run as s0.
> 
> To solve the constraint you would need to add
> 
> `mcs_killall(rgmanager_t)

Nope its started by that script (note the sigchld as well)
There is no way to deal with that constraint unless you allow
rgmanager_t to run the script with a domain plus range transition.
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