linux-kernel - Re: [PATCH net-next] x86: bpf_jit_comp: secure bpf jit against spraying attacks

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Message-ID: <519905B6.3080101@redhat.com>
Date:	Sun, 19 May 2013 19:02:46 +0200
From:	Daniel Borkmann <dborkman@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] x86: bpf_jit_comp: secure bpf jit against spraying
 attacks

On 05/18/2013 04:37 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> hpa bringed into my attention some security related issues
> with BPF JIT on x86.
>
> This patch makes sure the bpf generated code is marked read only,
> as other kernel text sections.
>
> It also splits the unused space (we vmalloc() and only use a fraction of
> the page) in two parts, so that the generated bpf code not starts at a
> known offset in the page, but a pseudo random one.
>
> Refs:
> http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html
>
> Reported-by: H. Peter Anvin <hpa@...or.com>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Great work !

Probably other archs could later on follow-up with setting to read-only, too.

Reviewed-by: Daniel Borkmann <dborkman@...hat.com>
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