[PATCH] --secontext: Implement displaying of expected context upon mismatch

Renaud Métrich rmetrich at redhat.com
Wed Dec 29 10:22:35 UTC 2021

On 12/29/21 10:47, Dmitry V. Levin wrote:
>> Unfortunately readlink() is not working here because readlink() doesn't
>> resolve fully but selabel_lookup() really requires knowing the path,
>> because it just checks in its database for the corresponding regex.
>> Example:
>> $ cd /tmp
>> $ ln -s /home/rmetrich symlinkdir
>> $ touch /home/rmetrich/bar
>> $ ln -s /tmp/symlinkdir/bar
>> $ matchpathcon $(readlink bar)
>> /tmp/symlinkdir/bar	<<none>>
>> ---> WRONG
>> $ matchpathcon $(realpath bar)
>> /home/rmetrich/bar	unconfined_u:object_r:user_home_t:s0
> When the function is called by selinux_getfdcon, the symlink in question
> is /proc/%u/fd/%u and it shouldn't need an extra canonicalization effort.
> Maybe in case of selinux_getfilecon you need this awful realpath, though.

OK, let's move realpath() to selinux_getfilecon() then and use 
readlink() in selinux_getfdcon().

I'll submit the new patch soon.

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