Merge branch 'net-fix-a-mcast-issue-for-tipc-udp-media'

Xin Long says:

====================
net: fix a mcast issue for tipc udp media

Patch 1 is to add a function to get the dev by source address,
which will be used by Patch 2.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Author: davem330

include/net/addrconf.h

@@ -97,6 +97,8 @@ bool ipv6_chk_custom_prefix(const struct in6_addr *addr,
 
 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 inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
 				     const struct in6_addr *addr,
 				     struct net_device *dev, int strict);

net/ipv6/addrconf.c

@@ -1983,6 +1983,45 @@ int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
 }
 EXPORT_SYMBOL(ipv6_chk_prefix);
 
+/**
+ * ipv6_dev_find - find the first device with a given source address.
+ * @net: the net namespace
+ * @addr: the source address
+ *
+ * The caller should be protected by RCU, or RTNL.
+ */
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
+{
+	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;
+}
+EXPORT_SYMBOL(ipv6_dev_find);
+
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
 				     struct net_device *dev, int strict)
 {

net/tipc/udp_media.c

@@ -738,13 +738,21 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 		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);
+		if (!dev) {
+			err = -ENODEV;
+			goto err;
+		}
 		udp_conf.family = AF_INET6;
 		udp_conf.use_udp6_tx_checksums = true;
 		udp_conf.use_udp6_rx_checksums = true;
 		if (rmcast)
 			udp_conf.local_ip6 = in6addr_any;
 		else
 			udp_conf.local_ip6 = local.ipv6;
+		ub->ifindex = dev->ifindex;
 		b->mtu = 1280;
 #endif
 	} else {