From: =?UTF-8?q?=EB=B0=B0=EC=84=9D=EC=A7=84?= <soukjin.bae@samsung.com>
Date: Fri, 9 Nov 2018 16:53:06 -0800
Subject: flow_dissector: do not dissect l4 ports for fragments
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Git-commit: 62230715fd2453b3ba948c9d83cfb3ada9169169
Patch-mainline: v4.20-rc2
References: networking-stable-18_11_21

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 <soukjin.bae@samsung.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/core/flow_dissector.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -756,8 +756,8 @@ ip_proto_again:
 		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);