ipv6: some fixes for ipv6_dev_find()

This patch is to do 3 things for ipv6_dev_find():

As David A. noticed,

- rt6_lookup() is not really needed. Different from __ip_dev_find(),
ipv6_dev_find() doesn't have a compatibility problem, so remove it.

As Hideaki suggested,

- "valid" (non-tentative) check for the address is also needed.
ipv6_chk_addr() calls ipv6_chk_addr_and_flags(), which will
traverse the address hash list, but it's heavy to be called
inside ipv6_dev_find(). This patch is to reuse the code of
ipv6_chk_addr_and_flags() for ipv6_dev_find().

- dev parameter is passed into ipv6_dev_find(), as link-local
addresses from user space has sin6_scope_id set and the dev
lookup needs it.

Fixes: 81f6cb31222d ("ipv6: add ipv6_dev_find()")
Suggested-by: YOSHIFUJI Hideaki <[e-mail]>
Reported-by: David Ahern <[e-mail]>
Signed-off-by: Xin Long <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/addrconf.h

···
 
 int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev);
 
-struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr);
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr,
+				 struct net_device *dev);
 
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
 				     const struct in6_addr *addr,

net/ipv6/addrconf.c

···
  *   2. does the address exist on the specific device
  *      (skip_dev_check = false)
  */
-int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
-			    const struct net_device *dev, bool skip_dev_check,
-			    int strict, u32 banned_flags)
+static struct net_device *
+__ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
+			  const struct net_device *dev, bool skip_dev_check,
+			  int strict, u32 banned_flags)
 {
 	unsigned int hash = inet6_addr_hash(net, addr);
-	const struct net_device *l3mdev;
+	struct net_device *l3mdev, *ndev;
 	struct inet6_ifaddr *ifp;
 	u32 ifp_flags;
 
···
 		dev = NULL;
 
 	hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
-		if (!net_eq(dev_net(ifp->idev->dev), net))
+		ndev = ifp->idev->dev;
+		if (!net_eq(dev_net(ndev), net))
 			continue;
 
-		if (l3mdev_master_dev_rcu(ifp->idev->dev) != l3mdev)
+		if (l3mdev_master_dev_rcu(ndev) != l3mdev)
 			continue;
 
 		/* Decouple optimistic from tentative for evaluation here.
···
 			    : ifp->flags;
 		if (ipv6_addr_equal(&ifp->addr, addr) &&
 		    !(ifp_flags&banned_flags) &&
-		    (!dev || ifp->idev->dev == dev ||
+		    (!dev || ndev == dev ||
 		     !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))) {
 			rcu_read_unlock();
-			return 1;
+			return ndev;
 		}
 	}
 
 	rcu_read_unlock();
-	return 0;
+	return NULL;
+}
+
+int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
+			    const struct net_device *dev, bool skip_dev_check,
+			    int strict, u32 banned_flags)
+{
+	return __ipv6_chk_addr_and_flags(net, addr, dev, skip_dev_check,
+					 strict, banned_flags) ? 1 : 0;
 }
 EXPORT_SYMBOL(ipv6_chk_addr_and_flags);
 
···
  *
  * The caller should be protected by RCU, or RTNL.
  */
-struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr,
+				 struct net_device *dev)
 {
-	unsigned int hash = inet6_addr_hash(net, addr);
-	struct inet6_ifaddr *ifp, *result = NULL;
-	struct net_device *dev = NULL;
-
-	rcu_read_lock();
-	hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
-		if (net_eq(dev_net(ifp->idev->dev), net) &&
-		    ipv6_addr_equal(&ifp->addr, addr)) {
-			result = ifp;
-			break;
-		}
-	}
-
-	if (!result) {
-		struct rt6_info *rt;
-
-		rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
-		if (rt) {
-			dev = rt->dst.dev;
-			ip6_rt_put(rt);
-		}
-	} else {
-		dev = result->idev->dev;
-	}
-	rcu_read_unlock();
-
-	return dev;
+	return __ipv6_chk_addr_and_flags(net, addr, dev, !dev, 1,
+					 IFA_F_TENTATIVE);
 }
 EXPORT_SYMBOL(ipv6_dev_find);
 

net/tipc/udp_media.c

···
 	struct udp_tunnel_sock_cfg tuncfg = {NULL};
 	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
 	u8 node_id[NODE_ID_LEN] = {0,};
+	struct net_device *dev;
 	int rmcast = 0;
 
 	ub = kzalloc(sizeof(*ub), GFP_ATOMIC);
···
 	rcu_assign_pointer(ub->bearer, b);
 	tipc_udp_media_addr_set(&b->addr, &local);
 	if (local.proto == htons(ETH_P_IP)) {
-		struct net_device *dev;
-
 		dev = __ip_dev_find(net, local.ipv4.s_addr, false);
 		if (!dev) {
 			err = -ENODEV;
···
 		b->mtu = b->media->mtu;
 #if IS_ENABLED(CONFIG_IPV6)
 	} else if (local.proto == htons(ETH_P_IPV6)) {
-		struct net_device *dev;
-
-		dev = ipv6_dev_find(net, &local.ipv6);
+		dev = ub->ifindex ? __dev_get_by_index(net, ub->ifindex) : NULL;
+		dev = ipv6_dev_find(net, &local.ipv6, dev);
 		if (!dev) {
 			err = -ENODEV;
 			goto err;