ipv6: Remove external dependency on rt6i_gateway and RTF_ANYCAST

When creating a RTF_CACHE route, RTF_ANYCAST is set based on rt6i_dst.
Also, rt6i_gateway is always set to the nexthop while the nexthop
could be a gateway or the rt6i_dst.addr.

After removing the rt6i_dst and rt6i_src dependency in the last patch,
we also need to stop the caller from depending on rt6i_gateway and
RTF_ANYCAST.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 24b359d..713d743 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -337,7 +337,7 @@
 	 * We won't send icmp if the destination is known
 	 * anycast.
 	 */
-	if (((struct rt6_info *)dst)->rt6i_flags & RTF_ANYCAST) {
+	if (ipv6_anycast_destination(dst, &fl6->daddr)) {
 		net_dbg_ratelimited("icmp6_send: acast source\n");
 		dst_release(dst);
 		return ERR_PTR(-EINVAL);
@@ -564,7 +564,7 @@
 
 	if (!ipv6_unicast_destination(skb) &&
 	    !(net->ipv6.sysctl.anycast_src_echo_reply &&
-	      ipv6_anycast_destination(skb)))
+	      ipv6_anycast_destination(skb_dst(skb), saddr)))
 		saddr = NULL;
 
 	memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3097f2c..6174167 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -105,7 +105,7 @@
 	}
 
 	rcu_read_lock_bh();
-	nexthop = rt6_nexthop((struct rt6_info *)dst);
+	nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr);
 	neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop);
 	if (unlikely(!neigh))
 		neigh = __neigh_create(&nd_tbl, nexthop, dst->dev, false);
@@ -934,7 +934,8 @@
 	 */
 	rt = (struct rt6_info *) *dst;
 	rcu_read_lock_bh();
-	n = __ipv6_neigh_lookup_noref(rt->dst.dev, rt6_nexthop(rt));
+	n = __ipv6_neigh_lookup_noref(rt->dst.dev,
+				      rt6_nexthop(rt, &fl6->daddr));
 	err = n && !(n->nud_state & NUD_VALID) ? -EINVAL : 0;
 	rcu_read_unlock_bh();
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 0c889cb..ce3b175 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1945,11 +1945,7 @@
 		if (rt->rt6i_idev)
 			in6_dev_hold(rt->rt6i_idev);
 		rt->dst.lastuse = jiffies;
-
-		if (ort->rt6i_flags & RTF_GATEWAY)
-			rt->rt6i_gateway = ort->rt6i_gateway;
-		else
-			rt->rt6i_gateway = *dest;
+		rt->rt6i_gateway = ort->rt6i_gateway;
 		rt->rt6i_flags = ort->rt6i_flags;
 		rt6_set_from(rt, ort);
 		rt->rt6i_metric = 0;