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>
diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 915ba57..3f5fd52 100644
--- a/include/linux/if_tun.h
+++ b/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