Subject: [PATCH net v2] openvswitch: Fix pop_vlan action for double tagged frames

From: Eric Garver <[email-masked]>
Date: Wed, 20 Dec 2017 10:39:32 -0500

skb_vlan_pop() expects skb->protocol to be a valid TPID for double
tagged frames, but skb->protocol is set to the ethertype by
key_extract(). So temporarily set it to the TPID when doing a pop_vlan.

Fixes: 5108bbaddc37 ("openvswitch: add processing of L3 packets")
Signed-off-by: Eric Garver <[email-masked]>
---
 net/openvswitch/actions.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 30a5df27116e..c484e0941047 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -280,6 +280,13 @@ static int set_mpls(struct sk_buff *skb, struct sw_flow_key *flow_key,
 static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
 {
 	int err;
+	__be16 proto = skb->protocol;
+
+	/* skb->protocol is set to the inner most parsed ethertype. To satisfy
+	 * skb_vlan_pop() for multi-tagged frames we must set it to the tpid.
+	 */
+	if (is_flow_key_valid(key) && key->eth.vlan.tci && key->eth.cvlan.tci)
+		skb->protocol = key->eth.cvlan.tpid;
 
 	err = skb_vlan_pop(skb);
 	if (skb_vlan_tag_present(skb)) {
@@ -288,6 +295,9 @@ static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
 		key->eth.vlan.tci = 0;
 		key->eth.vlan.tpid = 0;
 	}
+
+	skb->protocol = proto;
+
 	return err;
 }
 
-- 
2.12.0