From: abirvalg@lavabit.com
To: linux-kernel@vger.kernel.org
Subject: procfs doesnt honor cap_dac_override
Date: Fri, 05 Nov 2010 18:33:45 -0400 [thread overview]
Message-ID: <op.vlpyahbg25uvhe@wwwwww-701sd> (raw)
We have a folder /proc/1/fd which contains symlinks.
A superuser can do readlink() on those symlinks.
I expected that a non-root process with cap_dac_override capability set to
EP could also readlink() those symlinks in /proc/1/fd, but alas
"Permission denied".
Just to make sure that my process isn't the culprit, I ran it as a regular
user with UID=1000, I set cap_dac_override=ep and navigated to /root
folder (which is readable only by root) and did readlink() there. It
worked. (/root folder is on ext4.)
Bottom line: procfs doesnt allow readlink() on certain symlinks owned by
root even with cap_dac_override set.
Is this an expected behaviour or is this a bug?
Cheers.
reply other threads:[~2010-11-05 22:33 UTC|newest]
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