[IPSEC]: Check encap_type at config time, in user API code.

Here is the patch to check encap_type at the earliest possible
opportunity in xfrm_user/af_key.

This will allow us to assume in esp4 that the encap_type from x->encap
is always valid.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@redhat.com>

net/key/af_key.c

@@ -1075,6 +1075,15 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct sadb_msg *hdr,
 		n_type = ext_hdrs[SADB_X_EXT_NAT_T_TYPE-1];
 		natt->encap_type = n_type->sadb_x_nat_t_type_type;
 
+		switch (natt->encap_type) {
+		case UDP_ENCAP_ESPINUDP:
+		case UDP_ENCAP_ESPINUDP_NON_IKE:
+			break;
+		default:
+			err = -ENOPROTOOPT;
+			goto out;
+		}
+
 		if (ext_hdrs[SADB_X_EXT_NAT_T_SPORT-1]) {
 			struct sadb_x_nat_t_port* n_port =
 				ext_hdrs[SADB_X_EXT_NAT_T_SPORT-1];

net/xfrm/xfrm_user.c

@@ -78,6 +78,15 @@ static int verify_encap_tmpl(struct rtattr **xfrma)
 	if ((rt->rta_len - sizeof(*rt)) < sizeof(*encap))
 		return -EINVAL;
 
+	encap = RTA_DATA(rt);
+	switch (encap->encap_type) {
+	case UDP_ENCAP_ESPINUDP:
+	case UDP_ENCAP_ESPINUDP_NON_IKE:
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+
 	return 0;
 }