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Date: Wed, 14 Sep 2011 12:27:44 -0700
From: Kees Cook <kees@ubuntu.com>
To: Vasiliy Kulikov <segoon@openwall.com>
Cc: kernel-hardening@lists.openwall.com,
        Andrew Morton <akpm@linux-foundation.org>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Lameter <cl@linux-foundation.org>,
        Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo
Message-ID: <20110914192744.GC4529@outflux.net>
References: <20110910164001.GA2342@albatros>
 <20110910164134.GA2442@albatros>
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Hi Vasiliy,

On Sat, Sep 10, 2011 at 08:41:34PM +0400, Vasiliy Kulikov wrote:
> Historically /proc/slabinfo has 0444 permissions and is accessible to
> the world.  slabinfo contains rather private information related both to
> the kernel and userspace tasks.  Depending on the situation, it might
> reveal either private information per se or information useful to make
> another targeted attack.  Some examples of what can be learned by
> reading/watching for /proc/slabinfo entries:
> ...
> World readable slabinfo simplifies kernel developers' job of debugging
> kernel bugs (e.g. memleaks), but I believe it does more harm than
> benefits.  For most users 0444 slabinfo is an unreasonable attack vector.
> 
> Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>

Haven't had any mass complaints about the 0400 in Ubuntu (sorry Dave!), so
I'm obviously for it.

Reviewed-by: Kees Cook <kees@ubuntu.com>

-Kees

-- 
Kees Cook
Ubuntu Security Team