Subject: [PATCH 01/36] flow_dissector: do not dissect l4 ports for fragments

From: 배석진 <[email-masked]>
Date: Fri, 9 Nov 2018 16:53:06 -0800

[ Upstream commit 62230715fd2453b3ba948c9d83cfb3ada9169169 ]

Only first fragment has the sport/dport information,
not the following ones.

If we want consistent hash for all fragments, we need to
ignore ports even for first fragment.

This bug is visible for IPv6 traffic, if incoming fragments
do not have a flow label, since skb_get_hash() will give
different results for first fragment and following ones.

It is also visible if any routing rule wants dissection
and sport or dport.

See commit 5e5d6fed3741 ("ipv6: route: dissect flow
in input path if fib rules need it") for details.

[edumazet] rewrote the changelog completely.

Fixes: 06635a35d13d ("flow_dissect: use programable dissector in skb_flow_dissect and friends")
Signed-off-by: 배석진 <[email-masked]>
Signed-off-by: Eric Dumazet <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/core/flow_dissector.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 53f96e4f7bf5..d48016da1b72 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -993,8 +993,8 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 		break;
 	}
 
-	if (dissector_uses_key(flow_dissector,
-			       FLOW_DISSECTOR_KEY_PORTS)) {
+	if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS) &&
+	    !(key_control->flags & FLOW_DIS_IS_FRAGMENT)) {
 		key_ports = skb_flow_dissector_target(flow_dissector,
 						      FLOW_DISSECTOR_KEY_PORTS,
 						      target_container);
-- 
2.19.1