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Message-ID: <20110526185432.GB3476@elte.hu>
Date: Thu, 26 May 2011 20:54:32 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Will Drewry <wad@...omium.org>, Colin Walters <walters@...bum.org>,
Kees Cook <kees.cook@...onical.com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
linux-kernel@...r.kernel.org, James Morris <jmorris@...ei.org>
Subject: Re: [PATCH 3/5] v2 seccomp_filters: Enable ftrace-based system call
filtering
* Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> And if you filter system calls, it's entirely possible that you can
> attack suid executables through such a vector. Your "limit system
> calls for security" security suddenly turned into "avoid the system
> call that made things secure"!
That should not be possible with Will's event filter based solution
(his last submitted patch), due to this code in fs/exec.c (which is
in your upstream tree as well):
/*
* Flush performance counters when crossing a
* security domain:
*/
if (!get_dumpable(current->mm))
perf_event_exit_task(current);
This will drop all filters if a setuid-root (or whatever setuid)
binary is executed from a filtered environment.
Does this cover the case you were thinking of?
Thanks,
Ingo
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