From 83f7398ea549df793022ac6e7505040a306a2f7e Mon Sep 17 00:00:00 2001
From: Nikolay Aleksandrov <nikolay@nvidia.com>
Date: Tue, 22 Sep 2020 10:30:14 +0300
Subject: [PATCH] net: bridge: mdb: use extack in br_mdb_add() and
 br_mdb_add_group()

Pass and use extack all the way down to br_mdb_add_group().

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/bridge/br_mdb.c | 54 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 92ab7369fee0..1df62d887953 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -723,7 +723,8 @@ static int br_mdb_parse(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 
 static int br_mdb_add_group(struct net_bridge *br, struct net_bridge_port *port,
-			    struct br_ip *group, struct br_mdb_entry *entry)
+			    struct br_ip *group, struct br_mdb_entry *entry,
+			    struct netlink_ext_ack *extack)
 {
 	struct net_bridge_mdb_entry *mp;
 	struct net_bridge_port_group *p;
@@ -742,10 +743,14 @@ static int br_mdb_add_group(struct net_bridge *br, struct net_bridge_port *port,
 	/* host join */
 	if (!port) {
 		/* don't allow any flags for host-joined groups */
-		if (entry->state)
+		if (entry->state) {
+			NL_SET_ERR_MSG_MOD(extack, "Flags are not allowed for host groups");
 			return -EINVAL;
-		if (mp->host_joined)
+		}
+		if (mp->host_joined) {
+			NL_SET_ERR_MSG_MOD(extack, "Group is already joined by host");
 			return -EEXIST;
+		}
 
 		br_multicast_host_join(mp, false);
 		br_mdb_notify(br->dev, mp, NULL, RTM_NEWMDB);
@@ -756,16 +761,20 @@ static int br_mdb_add_group(struct net_bridge *br, struct net_bridge_port *port,
 	for (pp = &mp->ports;
 	     (p = mlock_dereference(*pp, br)) != NULL;
 	     pp = &p->next) {
-		if (p->port == port)
+		if (p->port == port) {
+			NL_SET_ERR_MSG_MOD(extack, "Group is already joined by port");
 			return -EEXIST;
+		}
 		if ((unsigned long)p->port < (unsigned long)port)
 			break;
 	}
 
 	p = br_multicast_new_port_group(port, group, *pp, entry->state, NULL,
 					MCAST_EXCLUDE);
-	if (unlikely(!p))
+	if (unlikely(!p)) {
+		NL_SET_ERR_MSG_MOD(extack, "Couldn't allocate new port group");
 		return -ENOMEM;
+	}
 	rcu_assign_pointer(*pp, p);
 	if (entry->state == MDB_TEMPORARY)
 		mod_timer(&p->timer, now + br->multicast_membership_interval);
@@ -776,7 +785,8 @@ static int br_mdb_add_group(struct net_bridge *br, struct net_bridge_port *port,
 
 static int __br_mdb_add(struct net *net, struct net_bridge *br,
 			struct net_bridge_port *p,
-			struct br_mdb_entry *entry)
+			struct br_mdb_entry *entry,
+			struct netlink_ext_ack *extack)
 {
 	struct br_ip ip;
 	int ret;
@@ -784,7 +794,7 @@ static int __br_mdb_add(struct net *net, struct net_bridge *br,
 	__mdb_entry_to_br_ip(entry, &ip);
 
 	spin_lock_bh(&br->multicast_lock);
-	ret = br_mdb_add_group(br, p, &ip, entry);
+	ret = br_mdb_add_group(br, p, &ip, entry, extack);
 	spin_unlock_bh(&br->multicast_lock);
 
 	return ret;
@@ -808,17 +818,37 @@ static int br_mdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	br = netdev_priv(dev);
 
-	if (!netif_running(br->dev) || !br_opt_get(br, BROPT_MULTICAST_ENABLED))
+	if (!netif_running(br->dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Bridge device is not running");
 		return -EINVAL;
+	}
+
+	if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) {
+		NL_SET_ERR_MSG_MOD(extack, "Bridge's multicast processing is disabled");
+		return -EINVAL;
+	}
 
 	if (entry->ifindex != br->dev->ifindex) {
 		pdev = __dev_get_by_index(net, entry->ifindex);
-		if (!pdev)
+		if (!pdev) {
+			NL_SET_ERR_MSG_MOD(extack, "Port net device doesn't exist");
 			return -ENODEV;
+		}
 
 		p = br_port_get_rtnl(pdev);
-		if (!p || p->br != br || p->state == BR_STATE_DISABLED)
+		if (!p) {
+			NL_SET_ERR_MSG_MOD(extack, "Net device is not a bridge port");
 			return -EINVAL;
+		}
+
+		if (p->br != br) {
+			NL_SET_ERR_MSG_MOD(extack, "Port belongs to a different bridge device");
+			return -EINVAL;
+		}
+		if (p->state == BR_STATE_DISABLED) {
+			NL_SET_ERR_MSG_MOD(extack, "Port is in disabled state");
+			return -EINVAL;
+		}
 		vg = nbp_vlan_group(p);
 	} else {
 		vg = br_vlan_group(br);
@@ -830,12 +860,12 @@ static int br_mdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (br_vlan_enabled(br->dev) && vg && entry->vid == 0) {
 		list_for_each_entry(v, &vg->vlan_list, vlist) {
 			entry->vid = v->vid;
-			err = __br_mdb_add(net, br, p, entry);
+			err = __br_mdb_add(net, br, p, entry, extack);
 			if (err)
 				break;
 		}
 	} else {
-		err = __br_mdb_add(net, br, p, entry);
+		err = __br_mdb_add(net, br, p, entry, extack);
 	}
 
 	return err;