Re: strange pam_selinux behavior

[Dominick Grift <dac.override@gmail.com>]

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On 03/24/2016 02:30 PM, Miroslav Grepl wrote:
> On 03/24/2016 02:24 PM, Dominick Grift wrote:
>> On 03/24/2016 02:14 PM, Miroslav Grepl wrote:
>> 
>> <snip>
>> 
>>>> 
>>>> added the access vector back in but that seems to not make
>>>> any differenc e.
>> 
>>> So you are still getting the same error message, right?
>> 
>> 
>> not quite right:
>> 
>> It now longer shows this: "Failed to translate security class
>> context"
>> 
>> So that part seems to have been fixed by adding the access
>> vector
>> 
>> however this error is still the same:
>> 
>>> pam_selinux(sshd:session): Security context 
>>> wheel.id:wheel.role:wheel.subj:s0-s0:c0.c1023 is not allowed
>>> for wheel.id:wheel.role:wheel.s ubj:s0-s0:c0.c1023 Mar 24
>>> 13:43:03 void sshd[14723]: pam_selinux(sshd:session): Unable to
>>> get valid context for kcinimod
>> 
>> So looking at the code:
>> 
>>> src_context = context_new (src); dst_context = context_new
>>> (dst); context_range_set(dst_context,
>>> context_range_get(src_context)); if (debug) pam_syslog(pamh,
>>> LOG_NOTICE, "Checking if %s mls range valid for  %s", dst,
>>> context_str(dst_context));
>> 
>>> retval = security_compute_av(context_str(dst_context), dst,
>>> class, bit, &avd); context_free(src_context);
>>> context_free(dst_context); if (retval || ((bit & avd.allowed)
>>> != bit)) return 0;
>> 
>>> return 1;
>> 
>> it appears that security_compute_av returns bad. But i can't
>> figure out how to reproduce that with "compute_av":
>> 
>> # compute_av wheel.id:wheel.role:wheel.subj:s0-s0:c0.c1023 
>> wheel.id:wheel.role:wheel.subj:s0-s0:c0.c1023 process
>> 
>> allowed = { fork sigchld sigkill signull signal getsched
>> setsched setpgid getattr setfscreate }
>> 
>> This works fine with stock fedora policy BTW. this seems to be a
>> DSSP specific issue. I am wondering if my policy has a bug
>> somewhere...
> 
> That's my point. If it is a bug in your policy or there is a bug
> related to CIL. I can try to install your DSSP policy and check
> it.
> 
>> 
>> 
>> 
> 

Heres a brief screencast that attempts to explain the issue

https://www.youtube.com/watch?v=kx0zEreMjTA


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Dominick Grift
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