vmxnet3: correctly report gso type for UDP tunnels

Commit 3d010c8 ("udp: do not accept non-tunnel GSO skbs landing
in a tunnel") added checks in linux stack to not accept non-tunnel
GRO packets landing in a tunnel. This exposed an issue in vmxnet3
which was not correctly reporting GRO packets for tunnel packets.

This patch fixes this issue by setting correct GSO type for the
tunnel packets.

Currently, vmxnet3 does not support reporting inner fields for LRO
tunnel packets. This is fine for now as workaround is to enable
tnl-segmentation offload on the relevant interfaces. This problem
pre-exists this patch fix and can be addressed as a separate future
patch.

Fixes: dacce2b ("vmxnet3: add geneve and vxlan tunnel offload support")
Signed-off-by: Ronak Doshi <[email protected]>
Acked-by: Guolin Yang <[email protected]>

Changes v1-->v2:
  Do not set encapsulation bit as inner fields are not updated
Changes v2-->v3:
  Update the commit message explaining the next steps to address
  segmentation issues that pre-exists this patch fix.

Signed-off-by: NipaLocal <nipa@local>

Author: Ronak Doshi

drivers/net/vmxnet3/vmxnet3_drv.c

@@ -1572,6 +1572,30 @@ vmxnet3_get_hdr_len(struct vmxnet3_adapter *adapter, struct sk_buff *skb,
 	return (hlen + (hdr.tcp->doff << 2));
 }
 
+static void
+vmxnet3_lro_tunnel(struct sk_buff *skb, __be16 ip_proto)
+{
+	struct udphdr *uh = NULL;
+
+	if (ip_proto == htons(ETH_P_IP)) {
+		struct iphdr *iph = (struct iphdr *)skb->data;
+
+		if (iph->protocol == IPPROTO_UDP)
+			uh = (struct udphdr *)(iph + 1);
+	} else {
+		struct ipv6hdr *iph = (struct ipv6hdr *)skb->data;
+
+		if (iph->nexthdr == IPPROTO_UDP)
+			uh = (struct udphdr *)(iph + 1);
+	}
+	if (uh) {
+		if (uh->check)
+			skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
+		else
+			skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
+	}
+}
+
 static int
 vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
 		       struct vmxnet3_adapter *adapter, int quota)
@@ -1885,6 +1909,8 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
 			if (segCnt != 0 && mss != 0) {
 				skb_shinfo(skb)->gso_type = rcd->v4 ?
 					SKB_GSO_TCPV4 : SKB_GSO_TCPV6;
+				if (encap_lro)
+					vmxnet3_lro_tunnel(skb, skb->protocol);
 				skb_shinfo(skb)->gso_size = mss;
 				skb_shinfo(skb)->gso_segs = segCnt;
 			} else if ((segCnt != 0 || skb->len > mtu) && !encap_lro) {