[IPV6]: Fix anycast usage.

- Recognition of reserved anycasts is removed from ipv6_addr_type()
  Flag IPV6_ADDR_ANYCAST is removed as well.
- Some meaningless noop code checking for anycast which are not
  going to happen is removed from ndisc.c
- ipv6_unicast_destination() replaces suboptimal ipv6_chk_acast_addr()
  in data paths

include/net/ip6_route.h

@@ -45,7 +45,8 @@ extern int			ip6_del_rt(struct rt6_info *,
 					   void *rtattr);
 
 extern int			ip6_rt_addr_add(struct in6_addr *addr,
-						struct net_device *dev);
+						struct net_device *dev,
+						int anycast);
 
 extern int			ip6_rt_addr_del(struct in6_addr *addr,
 						struct net_device *dev);
@@ -118,5 +119,12 @@ static inline void ip6_dst_store(struct sock *sk, struct dst_entry *dst,
 	write_unlock(&sk->sk_dst_lock);
 }
 
+static inline int ipv6_unicast_destination(struct sk_buff *skb)
+{
+	struct rt6_info *rt = (struct rt6_info *) skb->dst;
+
+	return rt->rt6i_flags & RTF_LOCAL;
+}
+
 #endif
 #endif

include/net/ipv6.h

@@ -51,7 +51,7 @@
 /*
  *	Addr type
  *	
- *	type	-	unicast | multicast | anycast
+ *	type	-	unicast | multicast
  *	scope	-	local	| site	    | global
  *	v4	-	compat
  *	v4mapped
@@ -63,7 +63,6 @@
 
 #define IPV6_ADDR_UNICAST      	0x0001U	
 #define IPV6_ADDR_MULTICAST    	0x0002U	
-#define IPV6_ADDR_ANYCAST	0x0004U
 
 #define IPV6_ADDR_LOOPBACK	0x0010U
 #define IPV6_ADDR_LINKLOCAL	0x0020U

net/ipv6/addrconf.c

@@ -209,14 +209,7 @@ int ipv6_addr_type(const struct in6_addr *addr)
 		};
 		return type;
 	}
-	/* check for reserved anycast addresses */
 
-	if ((st & htonl(0xE0000000)) &&
-	    ((addr->s6_addr32[2] == htonl(0xFDFFFFFF) &&
-	    (addr->s6_addr32[3] | htonl(0x7F)) == (u32)~0) ||
-	    (addr->s6_addr32[2] == 0 && addr->s6_addr32[3] == 0)))
-		type = IPV6_ADDR_ANYCAST;
-	else
 	type = IPV6_ADDR_UNICAST;
 
 	/* Consider all addresses with the first three bits different of
@@ -2552,7 +2545,7 @@ static void ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 
 	switch (event) {
 	case RTM_NEWADDR:
-		ip6_rt_addr_add(&ifp->addr, ifp->idev->dev);
+		ip6_rt_addr_add(&ifp->addr, ifp->idev->dev, 0);
 		break;
 	case RTM_DELADDR:
 		addrconf_leave_solict(ifp->idev->dev, &ifp->addr);

net/ipv6/anycast.c

@@ -96,7 +96,6 @@ ip6_onlink(struct in6_addr *addr, struct net_device *dev)
 	return onlink;
 }
 
-
 /*
  *	socket join an anycast group
  */
@@ -110,8 +109,12 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
 	int	ishost = !ipv6_devconf.forwarding;
 	int	err = 0;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
 	if (ipv6_addr_type(addr) & IPV6_ADDR_MULTICAST)
 		return -EINVAL;
+	if (ipv6_chk_addr(addr, NULL))
+		return -EINVAL;
 
 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
 	if (pac == NULL)
@@ -161,21 +164,12 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
 	 * For hosts, allow link-local or matching prefix anycasts.
 	 * This obviates the need for propagating anycast routes while
 	 * still allowing some non-router anycast participation.
-	 *
-	 * allow anyone to join anycasts that don't require a special route
-	 * and can't be spoofs of unicast addresses (reserved anycast only)
 	 */
 	if (!ip6_onlink(addr, dev)) {
 		if (ishost)
 			err = -EADDRNOTAVAIL;
-		else if (!capable(CAP_NET_ADMIN))
-			err = -EPERM;
 		if (err)
 			goto out_dev_put;
-	} else if (!(ipv6_addr_type(addr) & IPV6_ADDR_ANYCAST) &&
-		   !capable(CAP_NET_ADMIN)) {
-		err = -EPERM;
-		goto out_dev_put;
 	}
 
 	err = ipv6_dev_ac_inc(dev, addr);
@@ -266,6 +260,13 @@ void ipv6_sock_ac_close(struct sock *sk)
 		dev_put(dev);
 }
 
+#if 0
+/* The function is not used, which is funny. Apparently, author
+ * supposed to use it to filter out datagrams inside udp/raw but forgot.
+ *
+ * It is OK, anycasts are not special comparing to delivery to unicasts.
+ */
+
 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 {
 	struct ipv6_ac_socklist *pac;
@@ -286,6 +287,8 @@ int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 	return found;
 }
 
+#endif
+
 static void aca_put(struct ifacaddr6 *ac)
 {
 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
@@ -347,7 +350,7 @@ int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 	idev->ac_list = aca;
 	write_unlock_bh(&idev->lock);
 
-	ip6_rt_addr_add(&aca->aca_addr, dev);
+	ip6_rt_addr_add(&aca->aca_addr, dev, 1);
 
 	addrconf_join_solict(dev, &aca->aca_addr);
 

net/ipv6/icmp.c

@@ -415,8 +415,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 
 	saddr = &skb->nh.ipv6h->daddr;
 
-	if (ipv6_addr_type(saddr) & IPV6_ADDR_MULTICAST ||
-	    ipv6_chk_acast_addr(0, saddr)) 
+	if (!ipv6_unicast_destination(skb))
 		saddr = NULL;
 
 	memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));

net/ipv6/ndisc.c

@@ -785,8 +785,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 			ipv6_addr_all_nodes(&maddr);
 			ndisc_send_na(dev, NULL, &maddr, &ifp->addr, 
 				      ifp->idev->cnf.forwarding, 0, 
-				      ipv6_addr_type(&ifp->addr)&IPV6_ADDR_ANYCAST ? 0 : 1, 
-				      1);
+				      1, 1);
 			in6_ifa_put(ifp);
 			return;
 		}
@@ -809,8 +808,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 			if (neigh || !dev->hard_header) {
 				ndisc_send_na(dev, neigh, saddr, &ifp->addr, 
 					      ifp->idev->cnf.forwarding, 1, 
-					      ipv6_addr_type(&ifp->addr)&IPV6_ADDR_ANYCAST ? 0 : 1, 
-					      1);
+					      1, 1);
 				if (neigh)
 					neigh_release(neigh);
 			}

net/ipv6/route.c

@@ -1261,7 +1261,7 @@ int ip6_pkt_discard(struct sk_buff *skb)
  *	Add address
  */
 
-int ip6_rt_addr_add(struct in6_addr *addr, struct net_device *dev)
+int ip6_rt_addr_add(struct in6_addr *addr, struct net_device *dev, int anycast)
 {
 	struct rt6_info *rt = ip6_dst_alloc();
 
@@ -1280,6 +1280,8 @@ int ip6_rt_addr_add(struct in6_addr *addr, struct net_device *dev)
 	rt->u.dst.obsolete = -1;
 
 	rt->rt6i_flags = RTF_UP | RTF_NONEXTHOP;
+	if (!anycast)
+		rt->rt6i_flags |= RTF_LOCAL;
 	rt->rt6i_nexthop = ndisc_get_neigh(rt->rt6i_dev, &rt->rt6i_gateway);
 	if (rt->rt6i_nexthop == NULL) {
 		dst_free((struct dst_entry *) rt);

net/ipv6/tcp_ipv6.c

@@ -971,7 +971,7 @@ static void tcp_v6_send_reset(struct sk_buff *skb)
 	if (th->rst)
 		return;
 
-	if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr))
+	if (!ipv6_unicast_destination(skb))
 		return; 
 
 	/*
@@ -1175,8 +1175,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	if (skb->protocol == htons(ETH_P_IP))
 		return tcp_v4_conn_request(sk, skb);
 
-	/* FIXME: do the same check for anycast */
-	if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr))
+	if (!ipv6_unicast_destination(skb))
 		goto drop; 
 
 	/*