From a5e2151ff9d5852d0ababbbcaeebd9646af9c8d9 Mon Sep 17 00:00:00 2001 From: Quan Tian Date: Tue, 5 Sep 2023 10:36:10 +0000 Subject: [PATCH] net/ipv6: SKB symmetric hash should incorporate transport ports __skb_get_hash_symmetric() was added to compute a symmetric hash over the protocol, addresses and transport ports, by commit eb70db875671 ("packet: Use symmetric hash for PACKET_FANOUT_HASH."). It uses flow_keys_dissector_symmetric_keys as the flow_dissector to incorporate IPv4 addresses, IPv6 addresses and ports. However, it should not specify the flag as FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL, which stops further dissection when an IPv6 flow label is encountered, making transport ports not being incorporated in such case. As a consequence, the symmetric hash is based on 5-tuple for IPv4 but 3-tuple for IPv6 when flow label is present. It caused a few problems, e.g. when nft symhash and openvswitch l4_sym rely on the symmetric hash to perform load balancing as different L4 flows between two given IPv6 addresses would always get the same symmetric hash, leading to uneven traffic distribution. Removing the use of FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL makes sure the symmetric hash is based on 5-tuple for both IPv4 and IPv6 consistently. Fixes: eb70db875671 ("packet: Use symmetric hash for PACKET_FANOUT_HASH.") Reported-by: Lars Ekman Closes: https://github.com/antrea-io/antrea/issues/5457 Signed-off-by: Quan Tian Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/flow_dissector.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 89d15ceaf9af..b3b3af0e7844 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -1831,8 +1831,7 @@ u32 __skb_get_hash_symmetric(const struct sk_buff *skb) memset(&keys, 0, sizeof(keys)); __skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric, - &keys, NULL, 0, 0, 0, - FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); + &keys, NULL, 0, 0, 0, 0); return __flow_hash_from_keys(&keys, &hashrnd); }