xfrm: Restrict extended sequence numbers to esp

The IPsec extended sequence numbers are fully implemented just for
esp. So restrict the usage to esp until other protocols have
support too.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_user.c

@@ -127,6 +127,9 @@ static inline int verify_replay(struct xfrm_usersa_info *p,
 	if (!rt)
 		return 0;
 
+	if (p->id.proto != IPPROTO_ESP)
+		return -EINVAL;
+
 	if (p->replay_window != 0)
 		return -EINVAL;