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: d691f9e8d440 ("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>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3697ad5..b4fdee6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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;