linux-kernel - Re: [patch 1/2] c/r: prctl: Add ability to set new mm_struct::exe

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Message-ID: <CAFLxGvyCRAq6t8_ni+VFUVpOGJ4-iz0i=PRFEFpVJ+ZaPEb3-g@mail.gmail.com>
Date:	Tue, 20 Mar 2012 00:02:44 +0100
From:	richard -rw- weinberger <richard.weinberger@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Cyrill Gorcunov <gorcunov@...nvz.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Oleg Nesterov <oleg@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Kees Cook <keescook@...omium.org>, Tejun Heo <tj@...nel.org>,
	Matt Helsley <matthltc@...ibm.com>
Subject: Re: [patch 1/2] c/r: prctl: Add ability to set new mm_struct::exe_file

On Mon, Mar 19, 2012 at 11:46 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> Well, let's discuss this more completely.  In what ways could an
> attacker use this?  How serious is the problem?  What actions can be
> taken to lessen it?  etcetera.

After considering the problem a bit more I think it's not a big problem.
We must not trust /proc/pid/exe in anyway.
An attacker can always execute another binary without calling execve().

So, why makes that one-short fashion the feature more secure?
Let the user change the exe symlink as often as he wants.
>From a security point of view the exe symlink is anyway useless.

-- 
Thanks,
//richard
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