vrf: Fix IPv6 with qdisc and xfrm

When a qdisc is attached to the VRF device, the packet goes down the ndo
xmit function which is setup to send the packet back to the VRF driver
which does a lookup to send the packet out. The lookup in the VRF driver
is not considering xfrm policies. Change it to use ip6_dst_lookup_flow
rather than ip6_route_output.

Fixes: 35402e3136 ("net: Add IPv6 support to VRF device")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -188,8 +188,8 @@ static netdev_tx_t vrf_process_v6_outbound(struct sk_buff *skb,
 	fl6.flowi6_proto = iph->nexthdr;
 	fl6.flowi6_flags = FLOWI_FLAG_SKIP_NH_OIF;
 
-	dst = ip6_route_output(net, NULL, &fl6);
-	if (dst == dst_null)
+	dst = ip6_dst_lookup_flow(net, NULL, &fl6, NULL);
+	if (IS_ERR(dst) || dst == dst_null)
 		goto err;
 
 	skb_dst_drop(skb);