Re: File context rule not working

[Nicolas Iooss <nicolas.iooss@m4x.org>]

On Sun, Jul 26, 2020 at 8:01 PM Ian Pilcher <arequipeno@gmail.com> wrote:
>
> On 7/26/20 11:01 AM, Nicolas Iooss wrote:
> > I guess this is due the rule 3 documented in
> > https://manpages.debian.org/experimental/libselinux1-dev/selabel_lookup_best_match_raw.3.en.html
> > (source https://github.com/SELinuxProject/selinux/blob/master/libselinux/man/man3/selabel_lookup_best_match.3):
> >
> >      The order of precedence for best match is:
> >      1. An exact match for the real path (key) or
> >      2. An exact match for any of the links (aliases), or
> >      3. The longest fixed prefix match.
> >
> > I guess that in your policy, there is a rule that states that
> > /usr/bin(/.*)? is labeled bin_t. As both /usr/bin(/.*)? and
> > /usr(/local)?/bin/raidcheck match /usr/bin/raidcheck, the order of
> > precedence is determined by the number of characters before the first
> > special characters (that indidate a regular expression). As
> > /usr/bin(/.*)? has a longer "fixed prefix", it is the one that
> > matches.
>
> I can't find a '/usr/bin(/.*)?' rule.  'semanage fcontext --list' should
> show it, right?
>
> [root@n5550 files]# semanage fcontext --list | egrep '/usr/bin\('
> /usr/lib/debug/usr/bin(/.*)?                       regular file
> system_u:object_r:bin_t:s0

Yes, on my system (that uses refpolicy):

# semanage fcontext --list | egrep '/usr/bin\('
/usr/bin(/.*)?                                     all files
system_u:object_r:bin_t

> But I suspect that your reasoning is still correct.  I wasn't aware of
> the precedence rule.  The first "special character" does come pretty
> early in my rule, so it's likely that something that's considered more
> specific would match.
>
> > Does using "/usr/bin/raidcheck
> > system_u:object_r:raidcheck_exec_t:s0" fix your issue? If yes, you can
> > either duplicate the line (by adding both /usr/bin/... and
> > /usr/local/bin/...), or configure a substitution pattern such that
> > /usr/local/bin... gets transformed into /usr/bin/... before searching
> > for patterns.
>
> '/usr/bin/raidcheck' and '/usr/local/bin/raidcheck' both work, so I'll
> likely just go with that.

Great! Glad I could help fix your issue.

Cheers,
Nicolas