[IPV6]: Add and use new 'strict' parameter to ip6_chk_addr().

RFC 2461 requires that the source address of Neighbor Discovery messages
is an address assigned to the sending interface.

Duplicate Address Detection should also be interface specific. We don't,
for example, want a node to DoS itself just because it has two interfaces
on the same link and both happen to listen to the same multicast group. If
there is a true duplicate on the link, the interface doing DAD will notice
it anyway.

The attached patch adds a 'strict' parameter to ip6_chk_addr() and
ip6_get_ifaddr() to allow link-local protocols like ND and DAD to do
strict address checks even on addresses with greater scope than
link-local.

include/net/addrconf.h

@@ -57,9 +57,11 @@ extern int			addrconf_del_ifaddr(void *arg);
 extern int			addrconf_set_dstaddr(void *arg);
 
 extern int			ipv6_chk_addr(struct in6_addr *addr,
-					      struct net_device *dev);
+					      struct net_device *dev,
+					      int strict);
 extern struct inet6_ifaddr *	ipv6_get_ifaddr(struct in6_addr *addr,
-						struct net_device *dev);
+						struct net_device *dev,
+						int strict);
 extern int			ipv6_get_saddr(struct dst_entry *dst, 
 					       struct in6_addr *daddr,
 					       struct in6_addr *saddr);

net/ipv6/addrconf.c

@@ -910,7 +910,7 @@ static int ipv6_count_addresses(struct inet6_dev *idev)
 	return cnt;
 }
 
-int ipv6_chk_addr(struct in6_addr *addr, struct net_device *dev)
+int ipv6_chk_addr(struct in6_addr *addr, struct net_device *dev, int strict)
 {
 	struct inet6_ifaddr * ifp;
 	u8 hash = ipv6_addr_hash(addr);
@@ -920,7 +920,7 @@ int ipv6_chk_addr(struct in6_addr *addr, struct net_device *dev)
 		if (ipv6_addr_cmp(&ifp->addr, addr) == 0 &&
 		    !(ifp->flags&IFA_F_TENTATIVE)) {
 			if (dev == NULL || ifp->idev->dev == dev ||
-			    !(ifp->scope&(IFA_LINK|IFA_HOST)))
+			    !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))
 				break;
 		}
 	}
@@ -945,7 +945,7 @@ int ipv6_chk_same_addr(const struct in6_addr *addr, struct net_device *dev)
 	return ifp != NULL;
 }
 
-struct inet6_ifaddr * ipv6_get_ifaddr(struct in6_addr *addr, struct net_device *dev)
+struct inet6_ifaddr * ipv6_get_ifaddr(struct in6_addr *addr, struct net_device *dev, int strict)
 {
 	struct inet6_ifaddr * ifp;
 	u8 hash = ipv6_addr_hash(addr);
@@ -954,7 +954,7 @@ struct inet6_ifaddr * ipv6_get_ifaddr(struct in6_addr *addr, struct net_device *
 	for(ifp = inet6_addr_lst[hash]; ifp; ifp=ifp->lst_next) {
 		if (ipv6_addr_cmp(&ifp->addr, addr) == 0) {
 			if (dev == NULL || ifp->idev->dev == dev ||
-			    !(ifp->scope&(IFA_LINK|IFA_HOST))) {
+			    !(ifp->scope&(IFA_LINK|IFA_HOST) || strict)) {
 				in6_ifa_hold(ifp);
 				break;
 			}
@@ -1393,7 +1393,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
 
 ok:
 
-		ifp = ipv6_get_ifaddr(&addr, dev);
+		ifp = ipv6_get_ifaddr(&addr, dev, 1);
 
 		if (ifp == NULL && valid_lft) {
 			int max_addresses = in6_dev->cnf.max_addresses;
@@ -2952,7 +2952,7 @@ static void ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 			if (!ipv6_addr_any(&addr))
 				ipv6_dev_ac_dec(ifp->idev->dev, &addr);
 		}
-		if (!ipv6_chk_addr(&ifp->addr, NULL))
+		if (!ipv6_chk_addr(&ifp->addr, ifp->idev->dev, 1))
 			ip6_rt_addr_del(&ifp->addr, ifp->idev->dev);
 		break;
 	}

net/ipv6/af_inet6.c

@@ -355,7 +355,7 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 			 */
 			v4addr = LOOPBACK4_IPV6;
 			if (!(addr_type & IPV6_ADDR_MULTICAST))	{
-				if (!ipv6_chk_addr(&addr->sin6_addr, dev)) {
+				if (!ipv6_chk_addr(&addr->sin6_addr, dev, 0)) {
 					if (dev)
 						dev_put(dev);
 					err = -EADDRNOTAVAIL;

net/ipv6/anycast.c

@@ -113,7 +113,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
 		return -EPERM;
 	if (ipv6_addr_type(addr) & IPV6_ADDR_MULTICAST)
 		return -EINVAL;
-	if (ipv6_chk_addr(addr, NULL))
+	if (ipv6_chk_addr(addr, NULL, 0))
 		return -EINVAL;
 
 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);

net/ipv6/datagram.c

@@ -307,7 +307,7 @@ int datagram_send_ctl(struct msghdr *msg, struct flowi *fl,
 						return -ENODEV;
 				}
 			}
-			if (!ipv6_chk_addr(&src_info->ipi6_addr, dev)) {
+			if (!ipv6_chk_addr(&src_info->ipi6_addr, dev, 0)) {
 				if (dev)
 					dev_put(dev);
 				err = -EINVAL;

net/ipv6/icmp.c

@@ -298,7 +298,7 @@ void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
 	 */
 	addr_type = ipv6_addr_type(&hdr->daddr);
 
-	if (ipv6_chk_addr(&hdr->daddr, skb->dev))
+	if (ipv6_chk_addr(&hdr->daddr, skb->dev, 0))
 		saddr = &hdr->daddr;
 
 	/*

net/ipv6/ip6_tunnel.c

@@ -777,10 +777,10 @@ static void ip6_tnl_set_cap(struct ip6_tnl *t)
 		if (p->link)
 			ldev = dev_get_by_index(p->link);
 		
-		if ((ltype&IPV6_ADDR_UNICAST) && !ipv6_chk_addr(laddr, ldev))
+		if (ltype&IPV6_ADDR_UNICAST && !ipv6_chk_addr(laddr, ldev, 0))
 			l_ok = 0;
 		
-		if ((rtype&IPV6_ADDR_UNICAST) && ipv6_chk_addr(raddr, NULL))
+		if (rtype&IPV6_ADDR_UNICAST && ipv6_chk_addr(raddr, NULL, 0))
 			r_ok = 0;
 		
 		if (l_ok && r_ok) {

net/ipv6/ndisc.c

@@ -434,7 +434,7 @@ static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
 	len = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);
 
 	/* for anycast or proxy, solicited_addr != src_addr */
-	ifp = ipv6_get_ifaddr(solicited_addr, dev);
+	ifp = ipv6_get_ifaddr(solicited_addr, dev, 1);
  	if (ifp) {
 		src_addr = solicited_addr;
 		in6_ifa_put(ifp);
@@ -680,7 +680,7 @@ static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
 	struct in6_addr *target = (struct in6_addr *)&neigh->primary_key;
 	int probes = atomic_read(&neigh->probes);
 
-	if (skb && ipv6_chk_addr(&skb->nh.ipv6h->saddr, dev))
+	if (skb && ipv6_chk_addr(&skb->nh.ipv6h->saddr, dev, 1))
 		saddr = &skb->nh.ipv6h->saddr;
 
 	if ((probes -= neigh->parms->ucast_probes) < 0) {
@@ -758,7 +758,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 		}
 	}
 
-	if ((ifp = ipv6_get_ifaddr(&msg->target, dev)) != NULL) {
+	if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1)) != NULL) {
 		if (ifp->flags & IFA_F_TENTATIVE) {
 			/* Address is tentative. If the source
 			   is unspecified address, it is someone
@@ -955,7 +955,7 @@ static void ndisc_recv_na(struct sk_buff *skb)
 			return;
 		}
 	}
-	if ((ifp = ipv6_get_ifaddr(&msg->target, dev))) {
+	if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1))) {
 		if (ifp->flags & IFA_F_TENTATIVE) {
 			addrconf_dad_failure(ifp);
 			return;

net/ipv6/raw.c

@@ -227,7 +227,7 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 		v4addr = LOOPBACK4_IPV6;
 		if (!(addr_type & IPV6_ADDR_MULTICAST))	{
 			err = -EADDRNOTAVAIL;
-			if (!ipv6_chk_addr(&addr->sin6_addr, dev)) {
+			if (!ipv6_chk_addr(&addr->sin6_addr, dev, 0)) {
 				if (dev)
 					dev_put(dev);
 				goto out;

net/sctp/ipv6.c

@@ -510,7 +510,7 @@ static int sctp_v6_available(union sctp_addr *addr, struct sctp_opt *sp)
 	if (!(type & IPV6_ADDR_UNICAST))
 		return 0;
 
-	return ipv6_chk_addr(in6, NULL);
+	return ipv6_chk_addr(in6, NULL, 0);
 }
 
 /* This function checks if the address is a valid address to be used for