tun: Allow tap device to send/receive UFO packets.

- Allow setting UFO on tap device and handle UFO packets.
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

---------------------------------------------------------
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -641,6 +641,9 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun,
 		case VIRTIO_NET_HDR_GSO_TCPV6:
 			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
 			break;
+		case VIRTIO_NET_HDR_GSO_UDP:
+			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
+			break;
 		default:
 			tun->dev->stats.rx_frame_errors++;
 			kfree_skb(skb);
@@ -726,6 +729,8 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 			else if (sinfo->gso_type & SKB_GSO_TCPV6)
 				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+			else if (sinfo->gso_type & SKB_GSO_UDP)
+				gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
 			else
 				BUG();
 			if (sinfo->gso_type & SKB_GSO_TCP_ECN)
@@ -1073,7 +1078,8 @@ static int set_offload(struct net_device *dev, unsigned long arg)
 	old_features = dev->features;
 	/* Unset features, set them as we chew on the arg. */
 	features = (old_features & ~(NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST
-				    |NETIF_F_TSO_ECN|NETIF_F_TSO|NETIF_F_TSO6));
+				    |NETIF_F_TSO_ECN|NETIF_F_TSO|NETIF_F_TSO6
+				    |NETIF_F_UFO));
 
 	if (arg & TUN_F_CSUM) {
 		features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
@@ -1090,6 +1096,11 @@ static int set_offload(struct net_device *dev, unsigned long arg)
 				features |= NETIF_F_TSO6;
 			arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
 		}
+
+		if (arg & TUN_F_UFO) {
+			features |= NETIF_F_UFO;
+			arg &= ~TUN_F_UFO;
+		}
 	}
 
 	/* This gives the user a way to test for new features in future by

include/linux/if_tun.h

@@ -62,6 +62,7 @@
 #define TUN_F_TSO4	0x02	/* I can handle TSO for IPv4 packets */
 #define TUN_F_TSO6	0x04	/* I can handle TSO for IPv6 packets */
 #define TUN_F_TSO_ECN	0x08	/* I can handle TSO with ECN bits. */
+#define TUN_F_UFO	0x10	/* I can handle UFO packets */
 
 /* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
 #define TUN_PKT_STRIP	0x0001