udp: Set SKB_GSO_UDP_TUNNEL* in UDP GRO path

Properly set GSO types and skb->encapsulation in the UDP tunnel GRO
complete so that packets are properly represented for GSO. This sets
SKB_GSO_UDP_TUNNEL or SKB_GSO_UDP_TUNNEL_CSUM depending on whether
non-zero checksums were received, and sets SKB_GSO_TUNNEL_REMCSUM if
the remote checksum option was processed.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_offload.c

@@ -402,6 +402,13 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff)
 	}
 
 	rcu_read_unlock();
+
+	if (skb->remcsum_offload)
+		skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
+
+	skb->encapsulation = 1;
+	skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
+
 	return err;
 }
 
@@ -410,9 +417,13 @@ static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 	const struct iphdr *iph = ip_hdr(skb);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 
-	if (uh->check)
+	if (uh->check) {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 					  iph->daddr, 0);
+	} else {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
+	}
 
 	return udp_gro_complete(skb, nhoff);
 }

net/ipv6/udp_offload.c

@@ -161,9 +161,13 @@ static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 
-	if (uh->check)
+	if (uh->check) {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 		uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 					  &ipv6h->daddr, 0);
+	} else {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
+	}
 
 	return udp_gro_complete(skb, nhoff);
 }