net/sched: act_tunnel_key: Don't dump dst port if it wasn't set

It's possible to set a tunnel without a destination port. However,
on dump(), a zero dst port is returned to user space even if it was not
set, fix that.

Note that so far it wasn't required, b/c key less tunnels were not
supported and the UDP tunnels do require destination port.
Signed-off-by: NAdi Nissim <adin@mellanox.com>
Reviewed-by: NOz Shlomo <ozsh@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/act_tunnel_key.c

@@ -512,7 +512,9 @@ static int tunnel_key_dump(struct sk_buff *skb, struct tc_action *a,
 		     nla_put_be32(skb, TCA_TUNNEL_KEY_ENC_KEY_ID, key_id)) ||
 		    tunnel_key_dump_addresses(skb,
 					      &params->tcft_enc_metadata->u.tun_info) ||
-		    nla_put_be16(skb, TCA_TUNNEL_KEY_ENC_DST_PORT, key->tp_dst) ||
+		    (key->tp_dst &&
+		      nla_put_be16(skb, TCA_TUNNEL_KEY_ENC_DST_PORT,
+				   key->tp_dst)) ||
 		    nla_put_u8(skb, TCA_TUNNEL_KEY_NO_CSUM,
 			       !(key->tun_flags & TUNNEL_CSUM)) ||
 		    tunnel_key_opts_dump(skb, info))