xfrm: tunnel: add extack to ipip_init_state, xfrm6_tunnel_init_state

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv4/xfrm4_tunnel.c

@@ -24,11 +24,15 @@ static int ipip_xfrm_rcv(struct xfrm_state *x, struct sk_buff *skb)
 
 static int ipip_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
 {
-	if (x->props.mode != XFRM_MODE_TUNNEL)
+	if (x->props.mode != XFRM_MODE_TUNNEL) {
+		NL_SET_ERR_MSG(extack, "IPv4 tunnel can only be used with tunnel mode");
 		return -EINVAL;
+	}
 
-	if (x->encap)
+	if (x->encap) {
+		NL_SET_ERR_MSG(extack, "IPv4 tunnel is not compatible with encapsulation");
 		return -EINVAL;
+	}
 
 	x->props.header_len = sizeof(struct iphdr);
 

net/ipv6/xfrm6_tunnel.c

@@ -272,11 +272,15 @@ static int xfrm6_tunnel_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 
 static int xfrm6_tunnel_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
 {
-	if (x->props.mode != XFRM_MODE_TUNNEL)
+	if (x->props.mode != XFRM_MODE_TUNNEL) {
+		NL_SET_ERR_MSG(extack, "IPv6 tunnel can only be used with tunnel mode");
 		return -EINVAL;
+	}
 
-	if (x->encap)
+	if (x->encap) {
+		NL_SET_ERR_MSG(extack, "IPv6 tunnel is not compatible with encapsulation");
 		return -EINVAL;
+	}
 
 	x->props.header_len = sizeof(struct ipv6hdr);