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Date: Tue, 20 Mar 2012 02:47:46 +0400
From: Cyrill Gorcunov <gorcunov@openvz.org>
To: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Pavel Emelyanov <xemul@parallels.com>,
        Kees Cook <keescook@chromium.org>, Tejun Heo <tj@kernel.org>,
        Matt Helsley <matthltc@us.ibm.com>
Subject: Re: [patch 1/2] c/r: prctl: Add ability to set new
 mm_struct::exe_file
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On Mon, Mar 19, 2012 at 11:41:36PM +0100, richard -rw- weinberger wrote:
> >
> > Actually I liked multi-shot version more but Matt arguments convinced
> > me that one-short fashion is more "secure" in terms of overall kernel
> > state and potential transitions/changes of this /proc/pid/exe symlink.
> >
> > At least with one-shot version the admin may be sure that the symlink
> > is never changed more than once, ever.
> >
> 
> And changing it once does not harm security?
> I'm sure that rootkit writers will like this feature...

The one-shot limits the amount of transitions, but you still
have to obtain CAP_SYS_RESOURCE before you'll be able to change
this symlink (ie it's not 'anyone-can-change-it' feature).

	Cyrill