[XFRM]: CONFIG_XFRM_MIGRATE option

Add CONFIG_XFRM_MIGRATE option which makes it possible for for user
application to send or receive MIGRATE message to/from netlink socket.

Signed-off-by: Shinta Sugimoto <shinta.sugimoto@ericsson.com>
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/Kconfig

@@ -24,6 +24,17 @@ config XFRM_SUB_POLICY
 
 	  If unsure, say N.
 
+config XFRM_MIGRATE
+	bool "Transformation migrate database (EXPERIMENTAL)"
+	depends on XFRM && EXPERIMENTAL
+	---help---
+	  A feature to update locator(s) of a given IPsec security
+	  association dynamically.  This feature is required, for
+	  instance, in a Mobile IPv6 environment with IPsec configuration
+	  where mobile nodes change their attachment point to the Internet.
+
+	  If unsure, say N.
+
 config NET_KEY
 	tristate "PF_KEY sockets"
 	select XFRM