From: Antoine Tenart <atenart@xxxxxxxxxx>
[ Upstream commit dc6456e938e938d64ffb6383a286b2ac9790a37f ]
The skb hash comes from sk->sk_txhash when using TCP, except for some
IPv6 RST packets. This is because in tcp_v6_send_reset when not in
TIME_WAIT the hash is taken from sk->sk_hash, while it should come from
sk->sk_txhash as those two hashes are not computed the same way.
Packetdrill script to test the above,
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
+0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
+0 > (flowlabel 0x1) S 0:0(0) <...>
// Wrong ack seq, trigger a rst.
+0 < S. 0:0(0) ack 0 win 4000
// Check the flowlabel matches prior one from SYN.
+0 > (flowlabel 0x1) R 0:0(0) <...>
Fixes: 9258b8b1be2e ("ipv6: tcp: send consistent autoflowlabel in RST packets")
Signed-off-by: Antoine Tenart <atenart@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv6/tcp_ipv6.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1e747241c7710..4d52e25deb9e3 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1064,7 +1064,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
if (np->repflow)
label = ip6_flowlabel(ipv6h);
priority = sk->sk_priority;
- txhash = sk->sk_hash;
+ txhash = sk->sk_txhash;
}
if (sk->sk_state == TCP_TIME_WAIT) {
label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
--
2.39.2
