[XFRM]: BEET mode

This patch introduces the BEET mode (Bound End-to-End Tunnel) with as
specified by the ietf draft at the following link:

http://www.ietf.org/internet-drafts/draft-nikander-esp-beet-mode-06.txt

The patch provides only single family support (i.e. inner family =
outer family).

Signed-off-by: Diego Beltrami <diego.beltrami@gmail.com>
Signed-off-by: Miika Komu     <miika@iki.fi>
Signed-off-by: Herbert Xu     <herbert@gondor.apana.org.au>
Signed-off-by: Abhinav Pathak <abhinav.pathak@hiit.fi>
Signed-off-by: Jeff Ahrenholz <ahrenholz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/in.h

@@ -40,6 +40,7 @@ enum {
 
   IPPROTO_ESP = 50,            /* Encapsulation Security Payload protocol */
   IPPROTO_AH = 51,             /* Authentication Header protocol       */
+  IPPROTO_BEETPH = 94,	       /* IP option pseudo header for BEET */
   IPPROTO_PIM    = 103,		/* Protocol Independent Multicast	*/
 
   IPPROTO_COMP   = 108,                /* Compression Header protocol */

include/linux/ip.h

@@ -80,6 +80,8 @@
 #define	IPOPT_TS_TSANDADDR	1		/* timestamps and addresses */
 #define	IPOPT_TS_PRESPEC	3		/* specified modules only */
 
+#define IPV4_BEET_PHMAXLEN 8
+
 struct iphdr {
 #if defined(__LITTLE_ENDIAN_BITFIELD)
 	__u8	ihl:4,
@@ -123,4 +125,11 @@ struct ip_comp_hdr {
 	__be16 cpi;
 };
 
+struct ip_beet_phdr {
+	__u8 nexthdr;
+	__u8 hdrlen;
+	__u8 padlen;
+	__u8 reserved;
+};
+
 #endif	/* _LINUX_IP_H */

include/linux/ipsec.h

@@ -12,7 +12,8 @@
 enum {
 	IPSEC_MODE_ANY		= 0,	/* We do not support this for SA */
 	IPSEC_MODE_TRANSPORT	= 1,
-	IPSEC_MODE_TUNNEL	= 2
+	IPSEC_MODE_TUNNEL	= 2,
+	IPSEC_MODE_BEET         = 3
 };
 
 enum {

include/linux/xfrm.h

@@ -129,7 +129,8 @@ enum
 #define XFRM_MODE_TUNNEL 1
 #define XFRM_MODE_ROUTEOPTIMIZATION 2
 #define XFRM_MODE_IN_TRIGGER 3
-#define XFRM_MODE_MAX 4
+#define XFRM_MODE_BEET 4
+#define XFRM_MODE_MAX 5
 
 /* Netlink configuration messages.  */
 enum {