[IPSEC] xfrm: Abstract out encapsulation modes

This patch adds the structure xfrm_mode.  It is meant to represent
the operations carried out by transport/tunnel modes.

By doing this we allow additional encapsulation modes to be added
without clogging up the xfrm_input/xfrm_output paths.

Candidate modes include 4-to-6 tunnel mode, 6-to-4 tunnel mode, and
BEET modes.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index 6b42cc474c01..46a15c7a1a13 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -118,6 +118,10 @@ enum
         XFRM_SHARE_UNIQUE       /* Use once */
 };
 
+#define XFRM_MODE_TRANSPORT 0
+#define XFRM_MODE_TUNNEL 1
+#define XFRM_MODE_MAX 2
+
 /* Netlink configuration messages.  */
 enum {
         XFRM_MSG_BASE = 0x10,