bridge: add NTF_USE support

More changes to the recent code to support control of forwarding
database via netlink.
   * Support NTF_USE like neighbour table
   * Validate state bits from application
   * Only send notifications (and change bits) if new entry is
     different.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_fdb.c

@@ -556,7 +556,7 @@ int br_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
-/* Create new static fdb entry */
+/* Update (create or replace) forwarding database entry */
 static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr,
 			 __u16 state, __u16 flags)
 {
@@ -575,16 +575,21 @@ static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr,
 	} else {
 		if (flags & NLM_F_EXCL)
 			return -EEXIST;
+	}
+
+	if (fdb_to_nud(fdb) != state) {
+		if (state & NUD_PERMANENT)
+			fdb->is_local = fdb->is_static = 1;
+		else if (state & NUD_NOARP) {
+			fdb->is_local = 0;
+			fdb->is_static = 1;
+		} else
+			fdb->is_local = fdb->is_static = 0;
 
-		if (flags & NLM_F_REPLACE)
-			fdb->updated = fdb->used = jiffies;
-		fdb->is_local = fdb->is_static = 0;
+		fdb->updated = fdb->used = jiffies;
+		fdb_notify(fdb, RTM_NEWNEIGH);
 	}
 
-	if (state & NUD_PERMANENT)
-		fdb->is_local = fdb->is_static = 1;
-	else if (state & NUD_NOARP)
-		fdb->is_static = 1;
 	return 0;
 }
 
@@ -627,16 +632,27 @@ int br_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 		return -EINVAL;
 	}
 
+	if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE))) {
+		pr_info("bridge: RTM_NEWNEIGH with invalid state %#x\n", ndm->ndm_state);
+		return -EINVAL;
+	}
+
 	p = br_port_get_rtnl(dev);
 	if (p == NULL) {
 		pr_info("bridge: RTM_NEWNEIGH %s not a bridge port\n",
 			dev->name);
 		return -EINVAL;
 	}
 
-	spin_lock_bh(&p->br->hash_lock);
-	err = fdb_add_entry(p, addr, ndm->ndm_state, nlh->nlmsg_flags);
-	spin_unlock_bh(&p->br->hash_lock);
+	if (ndm->ndm_flags & NTF_USE) {
+		rcu_read_lock();
+		br_fdb_update(p->br, p, addr);
+		rcu_read_unlock();
+	} else {
+		spin_lock_bh(&p->br->hash_lock);
+		err = fdb_add_entry(p, addr, ndm->ndm_state, nlh->nlmsg_flags);
+		spin_unlock_bh(&p->br->hash_lock);
+	}
 
 	return err;
 }