udp: exclude gso from xfrm paths

UDP GSO delays final datagram construction to the GSO layer. This
conflicts with protocol transformations.

Fixes: bec1f6f6 ("udp: generate gso with UDP_SEGMENT")
CC: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -788,7 +788,8 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 			return -EINVAL;
 		if (sk->sk_no_check_tx)
 			return -EINVAL;
-		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite)
+		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
+		    dst_xfrm(skb_dst(skb)))
 			return -EIO;
 
 		skb_shinfo(skb)->gso_size = cork->gso_size;

net/ipv6/udp.c

@@ -1053,7 +1053,8 @@ static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6,
 			return -EINVAL;
 		if (udp_sk(sk)->no_check6_tx)
 			return -EINVAL;
-		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite)
+		if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
+		    dst_xfrm(skb_dst(skb)))
 			return -EIO;
 
 		skb_shinfo(skb)->gso_size = cork->gso_size;