bridge: notify mdb changes via netlink

As Stephen mentioned, we need to monitor the mdb
changes in user-space, so add notifications via netlink too.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 84 insertions, 0 deletions

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index ccc43a9bff80..a8cfbf5f3c68 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -155,6 +155,86 @@ out:
         return skb->len;
 }
 
+static int nlmsg_populate_mdb_fill(struct sk_buff *skb,
+                                   struct net_device *dev,
+                                   struct br_mdb_entry *entry, u32 pid,
+                                   u32 seq, int type, unsigned int flags)
+{
+        struct nlmsghdr *nlh;
+        struct br_port_msg *bpm;
+        struct nlattr *nest, *nest2;
+
+        nlh = nlmsg_put(skb, pid, seq, type, sizeof(*bpm), NLM_F_MULTI);
+        if (!nlh)
+                return -EMSGSIZE;
+
+        bpm = nlmsg_data(nlh);
+        bpm->family  = AF_BRIDGE;
+        bpm->ifindex = dev->ifindex;
+        nest = nla_nest_start(skb, MDBA_MDB);
+        if (nest == NULL)
+                goto cancel;
+        nest2 = nla_nest_start(skb, MDBA_MDB_ENTRY);
+        if (nest2 == NULL)
+                goto end;
+
+        if (nla_put(skb, MDBA_MDB_ENTRY_INFO, sizeof(*entry), entry))
+                goto end;
+
+        nla_nest_end(skb, nest2);
+        nla_nest_end(skb, nest);
+        return nlmsg_end(skb, nlh);
+
+end:
+        nla_nest_end(skb, nest);
+cancel:
+        nlmsg_cancel(skb, nlh);
+        return -EMSGSIZE;
+}
+
+static inline size_t rtnl_mdb_nlmsg_size(void)
+{
+        return NLMSG_ALIGN(sizeof(struct br_port_msg))
+                + nla_total_size(sizeof(struct br_mdb_entry));
+}
+
+static void __br_mdb_notify(struct net_device *dev, struct br_mdb_entry *entry,
+                            int type)
+{
+        struct net *net = dev_net(dev);
+        struct sk_buff *skb;
+        int err = -ENOBUFS;
+
+        skb = nlmsg_new(rtnl_mdb_nlmsg_size(), GFP_ATOMIC);
+        if (!skb)
+                goto errout;
+
+        err = nlmsg_populate_mdb_fill(skb, dev, entry, 0, 0, type, NTF_SELF);
+        if (err < 0) {
+                kfree_skb(skb);
+                goto errout;
+        }
+
+        rtnl_notify(skb, net, 0, RTNLGRP_MDB, NULL, GFP_ATOMIC);
+        return;
+errout:
+        rtnl_set_sk_err(net, RTNLGRP_MDB, err);
+}
+
+void br_mdb_notify(struct net_device *dev, struct net_bridge_port *port,
+                   struct br_ip *group, int type)
+{
+        struct br_mdb_entry entry;
+
+        entry.ifindex = port->dev->ifindex;
+        entry.addr.proto = group->proto;
+        entry.addr.u.ip4 = group->u.ip4;
+#if IS_ENABLED(CONFIG_IPV6)
+        entry.addr.u.ip6 = group->u.ip6;
+#endif
+        __br_mdb_notify(dev, &entry, type);
+}
+
 void br_mdb_init(void)
 {
         rtnl_register(PF_BRIDGE, RTM_GETMDB, NULL, br_mdb_dump, NULL);
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 847b98a1d5e0..d929586ce39e 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -681,6 +681,7 @@ static int br_multicast_add_group(struct net_bridge *br,
                     (unsigned long)p);
 
         rcu_assign_pointer(*pp, p);
+        br_mdb_notify(br->dev, port, group, RTM_NEWMDB);
 
 found:
         mod_timer(&p->timer, now + br->multicast_membership_interval);
@@ -1240,6 +1241,7 @@ static void br_multicast_leave_group(struct net_bridge *br,
                         hlist_del_init(&p->mglist);
                         del_timer(&p->timer);
                         call_rcu_bh(&p->rcu, br_multicast_free_pg);
+                        br_mdb_notify(br->dev, port, group, RTM_DELMDB);
 
                         if (!mp->ports && !mp->mglist &&
                             netif_running(br->dev))
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index f95b766c7a98..2807c7680c38 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -435,6 +435,8 @@ extern int br_multicast_toggle(struct net_bridge *br, unsigned long val);
 extern int br_multicast_set_querier(struct net_bridge *br, unsigned long val);
 extern int br_multicast_set_hash_max(struct net_bridge *br, unsigned long val);
 extern void br_mdb_init(void);
+extern void br_mdb_notify(struct net_device *dev, struct net_bridge_port *port,
+                          struct br_ip *group, int type);
 
 static inline bool br_multicast_is_router(struct net_bridge *br)
 {