File contexts again

[Stephen Smalley]

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.
> 
> 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.
 
-- 
Stephen Smalley
National Security Agency