[PATCH net v3] openvswitch: Fix pop_vlan action for double tagged frames

[Eric Garver]

skb_vlan_pop() expects skb->protocol to be a valid TPID for double
tagged frames. So set skb->protocol to the TPID and let skb_vlan_pop()
shift the true ethertype into position for us.

Fixes: 5108bbaddc37 ("openvswitch: add processing of L3 packets")
Signed-off-by: Eric Garver <e...@erig.me>
---
 net/openvswitch/flow.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index dbe2379329c5..f039064ce922 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -579,6 +579,7 @@ static int key_extract(struct sk_buff *skb, struct 
sw_flow_key *key)
                        return -EINVAL;
 
                skb_reset_network_header(skb);
+               key->eth.type = skb->protocol;
        } else {
                eth = eth_hdr(skb);
                ether_addr_copy(key->eth.src, eth->h_source);
@@ -592,15 +593,23 @@ static int key_extract(struct sk_buff *skb, struct 
sw_flow_key *key)
                if (unlikely(parse_vlan(skb, key)))
                        return -ENOMEM;
 
-               skb->protocol = parse_ethertype(skb);
-               if (unlikely(skb->protocol == htons(0)))
+               key->eth.type = parse_ethertype(skb);
+               if (unlikely(key->eth.type == htons(0)))
                        return -ENOMEM;
 
+               /* Multiple tagged packets need to retain TPID to satisfy
+                * skb_vlan_pop(), which will later shift the ethertype into
+                * skb->protocol.
+                */
+               if (key->eth.cvlan.tci & htons(VLAN_TAG_PRESENT))
+                       skb->protocol = key->eth.cvlan.tpid;
+               else
+                       skb->protocol = key->eth.type;
+
                skb_reset_network_header(skb);
                __skb_push(skb, skb->data - skb_mac_header(skb));
        }
        skb_reset_mac_len(skb);
-       key->eth.type = skb->protocol;
 
        /* Network layer. */
        if (key->eth.type == htons(ETH_P_IP)) {
-- 
2.12.0