openvswitch: Fix pop_vlan action for double tagged frames

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>
Reviewed-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files 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)) {