[PATCH] flow_dissector: Fix vlan header offset in __skb_flow_dissect

From: YueHaibing <yuehaibing@huawei.com>
To: <davem@davemloft.net>, <sdf@google.com>, <jianbol@mellanox.com>,
	<jiri@mellanox.com>, <mirq-linux@rere.qmqm.pl>,
	<willemb@google.com>
Cc: <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
	YueHaibing <yuehaibing@huawei.com>
Subject: [PATCH] flow_dissector: Fix vlan header offset in __skb_flow_dissect
Date: Thu, 20 Jun 2019 00:01:32 +0800	[thread overview]
Message-ID: <20190619160132.38416-1-yuehaibing@huawei.com> (raw)

We build vlan on top of bonding interface, which vlan offload
is off, bond mode is 802.3ad (LACP) and xmit_hash_policy is
BOND_XMIT_POLICY_ENCAP34.

__skb_flow_dissect() fails to get information from protocol headers
encapsulated within vlan, because 'nhoff' is points to IP header,
so bond hashing is based on layer 2 info, which fails to distribute
packets across slaves.

Fixes: d5709f7ab776 ("flow_dissector: For stripped vlan, get vlan info from skb->vlan_tci")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 net/core/flow_dissector.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 415b95f..2a52abb 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -785,6 +785,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 		    skb && skb_vlan_tag_present(skb)) {
 			proto = skb->protocol;
 		} else {
+			if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX)
+				nhoff -=  sizeof(*vlan);
+
 			vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
 						    data, hlen, &_vlan);
 			if (!vlan) {
-- 
2.7.0


