[PATCH v9 net-next 3/7] openvswitch: add support to push and pop mpls for layer3 packets

[Simon Horman <simon.horman@netronome.com>]

Allow push and pop mpls actions to act on layer 3 packets by teaching
them not to access non-existent L2 headers of such packets.

Signed-off-by: Simon Horman <simon.horman@netronome.com>
---
v9
* New Patch
---
 net/openvswitch/actions.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 879185fe183f..fe885a89f501 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -160,8 +160,10 @@ static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
 
 	skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);
 
-	hdr = eth_hdr(skb);
-	hdr->h_proto = mpls->mpls_ethertype;
+	if (skb->mac_len) {
+		hdr = eth_hdr(skb);
+		hdr->h_proto = mpls->mpls_ethertype;
+	}
 
 	if (!skb->inner_protocol)
 		skb_set_inner_protocol(skb, skb->protocol);
@@ -174,7 +176,6 @@ static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
 static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
 		    const __be16 ethertype)
 {
-	struct ethhdr *hdr;
 	int err;
 
 	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
@@ -189,11 +190,16 @@ static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
 	__skb_pull(skb, MPLS_HLEN);
 	skb_reset_mac_header(skb);
 
-	/* skb_mpls_header() is used to locate the ethertype
-	 * field correctly in the presence of VLAN tags.
-	 */
-	hdr = (struct ethhdr *)(skb_mpls_header(skb) - ETH_HLEN);
-	hdr->h_proto = ethertype;
+	if (skb->mac_len) {
+		/* skb_mpls_header() is used to locate the ethertype
+		 * field correctly in the presence of VLAN tags.
+		 */
+		struct ethhdr *hdr;
+
+		hdr = (struct ethhdr *)(skb_mpls_header(skb) - ETH_HLEN);
+		BUG_ON((unsigned char *)hdr < skb_mac_header(skb));
+		hdr->h_proto = ethertype;
+	}
 	if (eth_p_mpls(skb->protocol))
 		skb->protocol = ethertype;
 
-- 
2.7.0.rc3.207.g0ac5344