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bpf: add flags to bpf_skb_store_bytes for clearing hash

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When overwriting parts of the packet with bpf_skb_store_bytes() that
were fed previously into skb->hash calculation, we should clear the
current hash with skb_clear_hash(), so that a next skb_get_hash() call
can determine the correct hash related to this skb.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2016-03-04 15:15:03 +01:00 committed by David S. Miller
parent 8050c0f027
commit 8afd54c87a
2 changed files with 4 additions and 1 deletions
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1
include/uapi/linux/bpf.h
View file

@ -305,6 +305,7 @@ enum bpf_func_id {
/* BPF_FUNC_skb_store_bytes flags. */
#define BPF_F_RECOMPUTE_CSUM (1ULL << 0)
#define BPF_F_INVALIDATE_HASH (1ULL << 1)
/* BPF_FUNC_l3_csum_replace and BPF_FUNC_l4_csum_replace flags.
* First 4 bits are for passing the header field size.

4
net/core/filter.c
View file

@ -1353,7 +1353,7 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
unsigned int len = (unsigned int) r4;
void *ptr;
if (unlikely(flags & ~(BPF_F_RECOMPUTE_CSUM)))
if (unlikely(flags & ~(BPF_F_RECOMPUTE_CSUM | BPF_F_INVALIDATE_HASH)))
return -EINVAL;
/* bpf verifier guarantees that:
@ -1384,6 +1384,8 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
if (flags & BPF_F_RECOMPUTE_CSUM)
skb_postpush_rcsum(skb, ptr, len);
if (flags & BPF_F_INVALIDATE_HASH)
skb_clear_hash(skb);
return 0;
}