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bpf: fix cb access in socket filter programs

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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: d691f9e8d4 ("bpf: allow programs to write to certain skb fields")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2015-10-07 10:55:41 -07:00 • committed by David S. Miller
parent d49ae37c61
commit ff936a04e5
5 changed files with 51 additions and 18 deletions
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6
include/linux/bpf.h
View file

@ -100,6 +100,8 @@ enum bpf_access_type {
BPF_WRITE = 2
};
struct bpf_prog;
struct bpf_verifier_ops {
/* return eBPF function prototype for verification */
const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
@ -111,7 +113,7 @@ struct bpf_verifier_ops {
u32 (*convert_ctx_access)(enum bpf_access_type type, int dst_reg,
int src_reg, int ctx_off,
struct bpf_insn *insn);
struct bpf_insn *insn, struct bpf_prog *prog);
};
struct bpf_prog_type_list {
@ -120,8 +122,6 @@ struct bpf_prog_type_list {
enum bpf_prog_type type;
};
struct bpf_prog;
struct bpf_prog_aux {
atomic_t refcnt;
u32 used_map_cnt;