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Message-ID: <20130520141941.GA16412@breakpoint.cc> Date: Mon, 20 May 2013 16:19:41 +0200 From: Florian Westphal <fw@...len.de> 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 Eric Dumazet <eric.dumazet@...il.com> 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 What about emitting additional instructions at random locations in the generated code itself? Eg., after every instruction, have random chance to insert 'xor $0xcc,%al; xor $0xcc,%al', etc? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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