SELinux and gitosis (FC11)

[Daniel J Walsh]

On 07/07/2009 05:59 AM, Jonathan Stott wrote:
> On Mon, 06 Jul 2009 08:12:26 -0400
> Daniel J Walsh<dwalsh at redhat.com>  wrote:
>
>> On 07/04/2009 07:41 AM, Jonathan Stott wrote:
>>> Hi
>>>
>>> # rpm -q selinux-policy selinux-policy-targeted
>>> selinux-policy-3.6.12-62.fc11.noarch
>>> selinux-policy-targeted-3.6.12-62.fc11.noarch
>>>
>>> (previously it was 3.6.12-53)
>>>
>>> And gitosis-serve is labelled gitosis_exec_t
>>>
>>> Even after upgrading the selinux policy versions, it still seems to
>>> hang in the same manner though.
>>>
>>> Regards,
>>> Jon
>>>
>>> --
>>> fedora-selinux-list mailing list
>>> fedora-selinux-list at redhat.com
>>> https://www.redhat.com/mailman/listinfo/fedora-selinux-list
>> Are you seeing any avc messages in /var/log/audit/audit.log?
>>
>> ps -eZ | grep gitosis
>>
>> Does this show apps running under the correct domain?
>>
>
> It's hard to tell whether it's running under the correct context (gitosis-serve seems to very quickly shell out to whatever git command is called and I'm not sure how to trigger ps at the correct time).  However it definitely has the correct context on the executable (which is the only copy of gitosis-serve on the system), and I've relabeled the file system just to be sure.
>
> However, I still seem to get the same AVC denial:
>
> -----------------------------------------------------------------------------
> Summary:
>
> SELinux is preventing bash (guest_t) "write" sshd_t.
>
> Detailed Description:
>
> SELinux denied access requested by bash. It is not expected that this access is
> required by bash and this access may signal an intrusion attempt. It is also
> possible that the specific version or configuration of the application is
> causing it to require additional access.
>
> Allowing Access:
>
> You can generate a local policy module to allow this access - see FAQ
> (http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385) Or you can disable
> SELinux protection altogether. Disabling SELinux protection is not recommended.
> Please file a bug report (http://bugzilla.redhat.com/bugzilla/enter_bug.cgi)
> against this package.
>
> Additional Information:
>
> Source Context                guest_u:guest_r:guest_t:s0
> Target Context                system_u:system_r:sshd_t:s0-s0:c0.c1023
> Target Objects                pipe [ fifo_file ]
> Source                        bash
> Source Path                   /bin/bash
> Port<Unknown>
> Host                          hzhangpg02.ph.man.ac.uk
> Source RPM Packages           bash-4.0-6.fc11
> Target RPM Packages
> Policy RPM                    selinux-policy-3.6.12-62.fc11
> Selinux Enabled               True
> Policy Type                   targeted
> MLS Enabled                   True
> Enforcing Mode                Enforcing
> Plugin Name                   catchall
> Host Name                     hzhangpg02.ph.man.ac.uk
> Platform                      Linux hzhangpg02.ph.man.ac.uk
>                                2.6.29.5-191.fc11.x86_64 #1 SMP Tue Jun 16
>                                23:23:21 EDT 2009 x86_64 x86_64
> Alert Count                   31
> First Seen                    Tue 30 Jun 2009 16:48:17 BST
> Last Seen                     Tue 07 Jul 2009 10:51:13 BST
> Local ID                      1cf6580e-12c8-48fb-bbb8-c06c3e55109d
> Line Numbers
>
> Raw Audit Messages
>
> node=hzhangpg02.ph.man.ac.uk type=AVC msg=audit(1246960273.947:80): avc:  denied  { write } for  pid=3472 comm="bash" path="pipe:[51971]" dev=pipefs ino=51971 scontext=guest_u:guest_r:guest_t:s0 tcontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tclass=fifo_file
>
> node=hzhangpg02.ph.man.ac.uk type=AVC msg=audit(1246960273.947:80): avc:  denied  { write } for  pid=3472 comm="bash" path="pipe:[51972]" dev=pipefs ino=51972 scontext=guest_u:guest_r:guest_t:s0 tcontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tclass=fifo_file
>
> node=hzhangpg02.ph.man.ac.uk type=SYSCALL msg=audit(1246960273.947:80): arch=c000003e syscall=59 success=yes exit=0 a0=7f5e932395d0 a1=7ffff16ddc90 a2=7f5e932314c0 a3=7ffff16dd940 items=0 ppid=3471 pid=3472 auid=501 uid=501 gid=501 euid=501 suid=501 fsuid=501 egid=501 sgid=501 fsgid=501 tty=(none) ses=5 comm="bash" exe="/bin/bash" subj=guest_u:guest_r:guest_t:s0 key=(null)
>
> --------------------------------------------------------------------
>
> Piping the raw audit messages into audit2allow and installing the module doesn't seem to remove them, though.
>
> Regards,
> Jon
So you intended on using the guest_t user?  What does the te file 
created by audit2allow look like?

I think the problem here is the guest_t user is running at s0 and trying 
to write to a fifo_file at s0-s0:c0.c1023

If you take the above audit messages and run them through audit2why, 
what does the tool say?