Re: File context rule not working

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

On Sun, Jul 26, 2020 at 5:03 PM Ian Pilcher <arequipeno@gmail.com> wrote:
>
> I'm tearing my hair out trying to figure out why this rule isn't
> matching.
>
>    /usr(/local)?/bin/raidcheck    system_u:object_r:raidcheck_exec_t:s0
>
> The rule shows up in the output of 'semanage fcontext -l', so it's
> loaded, but either /usr/bin/raidcheck and /usr/local/bin/raidcheck  are
> still being set to bin_t.
>
> Is there any way to get restorecon to show the steps that it takes to
> determine the context for a file?

Hello,
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.

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.

Regards,
Nicolas