x86: bpf_jit_comp: secure bpf jit against spraying attacks

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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@zytor.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

...

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Eric Dumazet 2013-05-17 16:37:03 +00:00 • committed by David S. Miller

parent 3e59cb0ddf

commit 314beb9bca

1 changed files with 47 additions and 6 deletions

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arch/x86/net/bpf_jit_comp.c

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