ipv4: add a sock pointer to dst->output() path.

In the dst->output() path for ipv4, the code assumes the skb it has to
transmit is attached to an inet socket, specifically via
ip_mc_output() : The sk_mc_loop() test triggers a WARN_ON() when the
provider of the packet is an AF_PACKET socket.

The dst->output() method gets an additional 'struct sock *sk'
parameter. This needs a cascade of changes so that this parameter can
be propagated from vxlan to final consumer.

Fixes: 8f646c922d55 ("vxlan: keep original skb ownership")
Reported-by: lucien xin <lucien.xin@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index ce0cbbf..daccc4a 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -752,7 +752,7 @@
 	return n->output(n, skb);
 }
 
-static int dn_output(struct sk_buff *skb)
+static int dn_output(struct sock *sk, struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct dn_route *rt = (struct dn_route *)dst;
@@ -838,6 +838,18 @@
  * Used to catch bugs. This should never normally get
  * called.
  */
+static int dn_rt_bug_sk(struct sock *sk, struct sk_buff *skb)
+{
+	struct dn_skb_cb *cb = DN_SKB_CB(skb);
+
+	net_dbg_ratelimited("dn_rt_bug: skb from:%04x to:%04x\n",
+			    le16_to_cpu(cb->src), le16_to_cpu(cb->dst));
+
+	kfree_skb(skb);
+
+	return NET_RX_DROP;
+}
+
 static int dn_rt_bug(struct sk_buff *skb)
 {
 	struct dn_skb_cb *cb = DN_SKB_CB(skb);
@@ -1463,7 +1475,7 @@
 
 	rt->n = neigh;
 	rt->dst.lastuse = jiffies;
-	rt->dst.output = dn_rt_bug;
+	rt->dst.output = dn_rt_bug_sk;
 	switch (res.type) {
 	case RTN_UNICAST:
 		rt->dst.input = dn_forward;