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    bpf: fix cb access in socket filter programs · ff936a04
    Alexei Starovoitov 提交于
    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>
    ff936a04
bpf.h 6.4 KB