Re: C 7, selinux, and rpc.gssd

Lukas Vrabec <[email protected]> Fri, 18 May 2018 17:07:02 +0200
Newsgroups	gmane.linux.redhat.fedora.selinux
Organization	Red Hat, Inc.
Message-ID	<[email protected]>
On 05/18/2018 04:37 PM, [email protected] wrote:
> Lukas Vrabec <[email protected]> wrote:
>> On 05/17/2018 09:12 PM, [email protected] wrote:
>>>     As systems are upgraded, we're getting a ton of complaints
>>> (fortunately, we're in permissive mode) that would break everything.
>>> All of them involve rpc.gssd, and I see a number of bugs listed when I
>>> search.
>>>
>>>     Note that I first saw this on a RHEL system, but now I'm seeing it on
>>> CentOS 7. I'm bringing it up here, because, given that there are
>>> multiple reported, that there's some bigger picture involving policy
>>> and rpc.gssd.
>>>
>>>     I'll note that some of the reported bugs were *closed last year, or
>>> before, so it seems to me an old issue resurfaced.
>>>
>>> Example.
>>> SELinux is preventing /usr/sbin/rpc.gssd from using the block_suspend
>>> capability.
>>
>> While you won't send any logs, I'm not able to help you, but based on
>> our example, it looks like kernel bug affecting SELinux. Solution is to
>> dontaudit this SELinux denial.
>>
>> Also, what version of Centos 7 are you using? Centos 7.5?
>>
> One system is
> LSB Version:	:core-4.1-amd64:core-4.1-noarch
> Distributor ID:	RedHatEnterpriseWorkstation
> Description:	Red Hat Enterprise Linux Workstation release 7.5 (Maipo)
> Release:	7.5
> Codename:	Maipo
> 
> Another is
> LSB Version:	:core-4.1-amd64:core-4.1-noarch
> Distributor ID:	CentOS
> Description:	CentOS Linux release 7.5.1804 (Core)
> Release:	7.5.1804
> Codename:	Core
> 
> What logs do you usually want, the results of running sealert? From that,
> I see, on the CentOS 7.5 system:
> excerpt:
> Raw Audit Messages
> type=AVC msg=audit(1526626994.989:9622): avc:  denied  { block_suspend }
> for  pid=901 comm="rpc.gssd" capability=36 
> scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:system_r:gssd_t:s0
> tclass=capability2
> 
> And on the RHEL system:
> Raw Audit Messages
> type=AVC msg=audit(1526626926.76:162255): avc:  denied  { block_suspend }
> for  pid=1218 comm="rpc.gssd" capability=36 
> scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:system_r:gssd_t:s0
> tclass=capability2
> 
> So, same policy, and same denials. Note that the RHEL system is set for
> enforcing, while the CentOS system is permissive.
> 
>        mark
> 


Hi Mark,

Workaround from my previous mail should fix your issue.

Lukas.

-- 
Lukas Vrabec
Software Engineer, Security Technologies
Red Hat, Inc.

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