File contexts again

[Paul Howarth]

Stephen Smalley wrote:
> On Wed, 2006-05-31 at 13:58 -0400, Christopher Ashworth wrote:
>> On Wed, 2006-05-31 at 13:05 -0400, Stephen Smalley wrote:
>>> On Wed, 2006-05-31 at 12:54 -0400, Christopher Ashworth wrote:
>>>> On Wed, 2006-05-31 at 17:50 +0100, Paul Howarth wrote:
>>>>> Hmm, that doesn't explain why file contexts that aren't regexes do 
>>>>> actually work. So if I have:
>>>>>
>>>>> /home/pgsql/pgstartup\.log      -- 
>>>>> gen_context(system_u:object_r:postgresql_log_t,s0)
>>>>>
>>>>> this actually works as expected, even though the /home/[^/]*/.+
>>>>> homedir context also matches.
>>>> Ah, true.  I forgot you had said that this behavior was occurring.  It
>>>> seems I have misremembered what is happening.  Let me look again to
>>>> confirm what's going on.
>>> libselinux gives precedence to fully specified pathnames (no regex
>>> characters).  Doesn't matter where they fall within the config files.
>> Ah, right; thanks.  (As specified in libselinux/src/matchpathcon.c)
>>
>> So what I said before was true, modulo the fact that when the actual
>> call to matchpathcon is made, one final sort is performed, to give fully
>> specified pathnames precedence.

Is there some reason why this final sort is only done for 
fully-specified pathnames and doesn't use the same comparison function 
as lower down in the hierarchy?

>> Seems like the end-to-end process is a bit confusing, what with several
>> layers of sorting going on, but I can't immediately suggest an
>> improvement.  I guess it's just a matter of documenting the life of file
>> contexts as clearly as possible.
> 
> Ultimately, we'd like to migrate all integration and ordering of the
> various file contexts sources into libsemanage and eliminate the need
> for it in libselinux.  Mostly a legacy issue.

So that would mean that the file contexts would be sorted in the order 
previously discussed, no matter where their origin was (base policy, 
semodule, semanage, homedir etc.)? That would be much clearer :)

Whilst we're stuck with the existing ordering, is there a way to disable 
generation of the homedir contexts, so that someone could then add the 
contexts from file_contexts.homedirs to policy using semanage instead? 
This shouldn't be too onerous for most users of targeted policy with 
only user_u and root to worry about. The result would be a set of 
contexts that obeyed the expected ordering rules, wouldn't it?

Paul.