bpf: fix cb access in socket filter programs
eBPF socket filter programs may see junk in 'u32 cb[5]' area, since it could have been used by protocol layers earlier. For socket filter programs used in af_packet we need to clean 20 bytes of skb->cb area if it could be used by the program. For programs attached to TCP/UDP sockets we need to save/restore these 20 bytes, since it's used by protocol layers. Remove SK_RUN_FILTER macro, since it's no longer used. Long term we may move this bpf cb area to per-cpu scratch, but that requires addition of new 'per-cpu load/store' instructions, so not suitable as a short term fix. Fixes: d691f9e8 ("bpf: allow programs to write to certain skb fields") Reported-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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