5.4-stable review patch. If anyone has any objections, please let me know.
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From: Quan Tian qtian@vmware.com
commit a5e2151ff9d5852d0ababbbcaeebd9646af9c8d9 upstream.
__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 uablrek@gmail.com Closes: https://github.com/antrea-io/antrea/issues/5457 Signed-off-by: Quan Tian qtian@vmware.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/flow_dissector.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -1564,8 +1564,7 @@ u32 __skb_get_hash_symmetric(const struc
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); }