This is a note to let you know that I've just added the patch titled
net/ipv6: SKB symmetric hash should incorporate transport ports
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-ipv6-skb-symmetric-hash-should-incorporate-transport-ports.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a5e2151ff9d5852d0ababbbcaeebd9646af9c8d9 Mon Sep 17 00:00:00 2001
From: Quan Tian <qtian@xxxxxxxxxx>
Date: Tue, 5 Sep 2023 10:36:10 +0000
Subject: net/ipv6: SKB symmetric hash should incorporate transport ports
From: Quan Tian <qtian@xxxxxxxxxx>
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@xxxxxxxxx>
Closes: https://github.com/antrea-io/antrea/issues/5457
Signed-off-by: Quan Tian <qtian@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -1780,8 +1780,7 @@ 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);
}
Patches currently in stable-queue which might be from qtian@xxxxxxxxxx are
queue-6.5/net-ipv6-skb-symmetric-hash-should-incorporate-transport-ports.patch
