[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>
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 2017d36..3839b70 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -206,6 +206,7 @@
 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 {
 	struct xfrm_state *t;
+	u8 mode = XFRM_MODE_TUNNEL;
 	
 	t = xfrm_state_alloc();
 	if (t == NULL)
@@ -216,7 +217,9 @@
 	t->id.daddr.a4 = x->id.daddr.a4;
 	memcpy(&t->sel, &x->sel, sizeof(t->sel));
 	t->props.family = AF_INET;
-	t->props.mode = XFRM_MODE_TUNNEL;
+	if (x->props.mode == XFRM_MODE_BEET)
+		mode = x->props.mode;
+	t->props.mode = mode;
 	t->props.saddr.a4 = x->props.saddr.a4;
 	t->props.flags = x->props.flags;