Re: File context rule not working

[Ian Pilcher <arequipeno@gmail.com>]

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

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.

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