linux-kernel - Re: [PATCH] Make /proc/slabinfo 0400

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Date:	Sat, 5 Mar 2011 00:14:57 +0200
From:	Pekka Enberg <penberg@...nel.org>
To:	Dan Rosenberg <drosenberg@...curity.com>
Cc:	Matt Mackall <mpm@...enic.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Theodore Tso <tytso@....edu>, cl@...ux-foundation.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] Make /proc/slabinfo 0400

On Sat, Mar 5, 2011 at 12:10 AM, Pekka Enberg <penberg@...nel.org> wrote:
> I can think of four things that will make things harder for the
> attacker (in the order of least theoretical performance impact):
>
>  (1) disable slub merging
>
>  (2) pin down random objects in the slab during setup (i.e. don't
> allow them to be allocated)
>
>  (3) randomize the initial freelist
>
>  (4) randomize padding between objects in a slab
>
> AFAICT, all of them will make brute force attacks using the kernel
> heap as an attack vector harder but won't prevent them.

There's also a fifth one:

  (5) randomize slab page allocation order

which will make it harder to make sure you have full control over a
slab and figure out which allocation lands on it.

                        Pekka
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