xfrm: Add Traffic Flow Confidentiality padding XFRM attribute

The XFRMA_TFCPAD attribute for XFRM state installation configures
Traffic Flow Confidentiality by padding ESP packets to a specified
length.

Signed-off-by: Martin Willi <martin@strongswan.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index b971e38..930fdd2 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -283,6 +283,7 @@
 	XFRMA_KMADDRESS,        /* struct xfrm_user_kmaddress */
 	XFRMA_ALG_AUTH_TRUNC,	/* struct xfrm_algo_auth */
 	XFRMA_MARK,		/* struct xfrm_mark */
+	XFRMA_TFCPAD,		/* __u32 */
 	__XFRMA_MAX
 
 #define XFRMA_MAX (__XFRMA_MAX - 1)