net/ipv4: VTI support new module for ip_vti.

New VTI tunnel kernel module, Kconfig and Makefile changes.

Signed-off-by: Saurabh Mohan <saurabh.mohan@vyatta.com>
Reviewed-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Saurabh

include/linux/if_tunnel.h

@@ -80,4 +80,18 @@ enum {
 
 #define IFLA_GRE_MAX	(__IFLA_GRE_MAX - 1)
 
+/* VTI-mode i_flags */
+#define VTI_ISVTI 0x0001
+
+enum {
+	IFLA_VTI_UNSPEC,
+	IFLA_VTI_LINK,
+	IFLA_VTI_IKEY,
+	IFLA_VTI_OKEY,
+	IFLA_VTI_LOCAL,
+	IFLA_VTI_REMOTE,
+	__IFLA_VTI_MAX,
+};
+
+#define IFLA_VTI_MAX	(__IFLA_VTI_MAX - 1)
 #endif /* _IF_TUNNEL_H_ */

net/ipv4/Kconfig

@@ -310,6 +310,17 @@ config SYN_COOKIES
 
 	  If unsure, say N.
 
+config NET_IPVTI
+	tristate "Virtual (secure) IP: tunneling"
+	select INET_TUNNEL
+	depends on INET_XFRM_MODE_TUNNEL
+	---help---
+	  Tunneling means encapsulating data of one protocol type within
+	  another protocol and sending it over a channel that understands the
+	  encapsulating protocol. This can be used with xfrm mode tunnel to give
+	  the notion of a secure tunnel for IPSEC and then use routing protocol
+	  on top.
+
 config INET_AH
 	tristate "IP: AH transformation"
 	select XFRM_ALGO

net/ipv4/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_IP_MROUTE) += ipmr.o
 obj-$(CONFIG_NET_IPIP) += ipip.o
 obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
 obj-$(CONFIG_NET_IPGRE) += ip_gre.o
+obj-$(CONFIG_NET_IPVTI) += ip_vti.o
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
 obj-$(CONFIG_INET_AH) += ah4.o
 obj-$(CONFIG_INET_ESP) += esp4.o