ipv6: ndisc: inherit metadata dst when creating ndisc requests

If output device wants to see the dst, inherit the dst of the original skb
in the ndisc request.

This is an IPv6 counterpart of commit 0accfc26 ("arp: Inherit metadata
dst when creating ARP requests").
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ndisc.h

@@ -182,7 +182,8 @@ int ndisc_rcv(struct sk_buff *skb);
 
 void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
 		   const struct in6_addr *solicit,
-		   const struct in6_addr *daddr, const struct in6_addr *saddr);
+		   const struct in6_addr *daddr, const struct in6_addr *saddr,
+		   struct sk_buff *oskb);
 
 void ndisc_send_rs(struct net_device *dev,
 		   const struct in6_addr *saddr, const struct in6_addr *daddr);

net/ipv6/addrconf.c

@@ -3656,7 +3656,7 @@ static void addrconf_dad_work(struct work_struct *w)
 
 	/* send a neighbour solicitation for our addr */
 	addrconf_addr_solict_mult(&ifp->addr, &mcaddr);
-	ndisc_send_ns(ifp->idev->dev, NULL, &ifp->addr, &mcaddr, &in6addr_any);
+	ndisc_send_ns(ifp->idev->dev, NULL, &ifp->addr, &mcaddr, &in6addr_any, NULL);
 out:
 	in6_ifa_put(ifp);
 	rtnl_unlock();

net/ipv6/ndisc.c

@@ -553,7 +553,8 @@ static void ndisc_send_unsol_na(struct net_device *dev)
 
 void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
 		   const struct in6_addr *solicit,
-		   const struct in6_addr *daddr, const struct in6_addr *saddr)
+		   const struct in6_addr *daddr, const struct in6_addr *saddr,
+		   struct sk_buff *oskb)
 {
 	struct sk_buff *skb;
 	struct in6_addr addr_buf;
@@ -589,6 +590,9 @@ void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
 		ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR,
 				       dev->dev_addr);
 
+	if (!(dev->priv_flags & IFF_XMIT_DST_RELEASE) && oskb)
+		skb_dst_copy(skb, oskb);
+
 	ndisc_send_skb(skb, daddr, saddr);
 }
 
@@ -675,12 +679,12 @@ static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
 				  "%s: trying to ucast probe in NUD_INVALID: %pI6\n",
 				  __func__, target);
 		}
-		ndisc_send_ns(dev, neigh, target, target, saddr);
+		ndisc_send_ns(dev, neigh, target, target, saddr, skb);
 	} else if ((probes -= NEIGH_VAR(neigh->parms, APP_PROBES)) < 0) {
 		neigh_app_ns(neigh);
 	} else {
 		addrconf_addr_solict_mult(target, &mcaddr);
-		ndisc_send_ns(dev, NULL, target, &mcaddr, saddr);
+		ndisc_send_ns(dev, NULL, target, &mcaddr, saddr, skb);
 	}
 }
 

net/ipv6/route.c

@@ -538,7 +538,7 @@ static void rt6_probe_deferred(struct work_struct *w)
 		container_of(w, struct __rt6_probe_work, work);
 
 	addrconf_addr_solict_mult(&work->target, &mcaddr);
-	ndisc_send_ns(work->dev, NULL, &work->target, &mcaddr, NULL);
+	ndisc_send_ns(work->dev, NULL, &work->target, &mcaddr, NULL, NULL);
 	dev_put(work->dev);
 	kfree(work);
 }