xfrm: Check for the new replay implementation if an esn state is inserted

IPsec extended sequence numbers can be used only with the new
anti-replay window implementation. So check if the new implementation
is used if an esn state is inserted and return an error if it is not.

Signed-off-by: Steffen Klassert <[e-mail]>
Acked-by: Herbert Xu <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/xfrm/xfrm_user.c

···
 {
 	struct nlattr *rt = attrs[XFRMA_REPLAY_ESN_VAL];
 
+	if ((p->flags & XFRM_STATE_ESN) && !rt)
+		return -EINVAL;
+
 	if (!rt)
 		return 0;