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flow_dissector: do not dissect l4 ports for fragments

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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 5e5d6fed37 ("ipv6: route: dissect flow
in input path if fib rules need it") for details.

[edumazet] rewrote the changelog completely.

Fixes: 06635a35d1 ("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>
This commit is contained in:
배석진 2018-11-09 16:53:06 -08:00 committed by David S. Miller
parent d02854dc19
commit 62230715fd
1 changed files with 2 additions and 2 deletions
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4
net/core/flow_dissector.c
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@ -1166,8 +1166,8 @@ 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);