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Commit 8afd54c8 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: add flags to bpf_skb_store_bytes for clearing hash 



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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8050c0f0

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -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.

net/core/filter.c

+3 −1
Original line number Diff line number Diff line
@@ -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;

}