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Date:   Tue, 22 Sep 2020 10:30:12 +0300
From:   Nikolay Aleksandrov <razor@...ckwall.org>
To:     netdev@...r.kernel.org
Cc:     roopa@...dia.com, davem@...emloft.net,
        bridge@...ts.linux-foundation.org,
        Nikolay Aleksandrov <nikolay@...dia.com>
Subject: [PATCH net-next v2 01/16] net: bridge: mdb: use extack in br_mdb_parse()

From: Nikolay Aleksandrov <nikolay@...dia.com>

We can drop the pr_info() calls and just use extack to return a
meaningful error to user-space when br_mdb_parse() fails.

Signed-off-by: Nikolay Aleksandrov <nikolay@...dia.com>
---
 net/bridge/br_mdb.c | 60 +++++++++++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 21 deletions(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 00f1651a6aba..d4031f5554f7 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -629,33 +629,50 @@ void br_rtr_notify(struct net_device *dev, struct net_bridge_port *port,
 	rtnl_set_sk_err(net, RTNLGRP_MDB, err);
 }
 
-static bool is_valid_mdb_entry(struct br_mdb_entry *entry)
+static bool is_valid_mdb_entry(struct br_mdb_entry *entry,
+			       struct netlink_ext_ack *extack)
 {
-	if (entry->ifindex == 0)
+	if (entry->ifindex == 0) {
+		NL_SET_ERR_MSG_MOD(extack, "Zero entry ifindex is not allowed");
 		return false;
+	}
 
 	if (entry->addr.proto == htons(ETH_P_IP)) {
-		if (!ipv4_is_multicast(entry->addr.u.ip4))
+		if (!ipv4_is_multicast(entry->addr.u.ip4)) {
+			NL_SET_ERR_MSG_MOD(extack, "IPv4 entry group address is not multicast");
 			return false;
-		if (ipv4_is_local_multicast(entry->addr.u.ip4))
+		}
+		if (ipv4_is_local_multicast(entry->addr.u.ip4)) {
+			NL_SET_ERR_MSG_MOD(extack, "IPv4 entry group address is local multicast");
 			return false;
+		}
 #if IS_ENABLED(CONFIG_IPV6)
 	} else if (entry->addr.proto == htons(ETH_P_IPV6)) {
-		if (ipv6_addr_is_ll_all_nodes(&entry->addr.u.ip6))
+		if (ipv6_addr_is_ll_all_nodes(&entry->addr.u.ip6)) {
+			NL_SET_ERR_MSG_MOD(extack, "IPv6 entry group address is link-local all nodes");
 			return false;
+		}
 #endif
-	} else
+	} else {
+		NL_SET_ERR_MSG_MOD(extack, "Unknown entry protocol");
 		return false;
-	if (entry->state != MDB_PERMANENT && entry->state != MDB_TEMPORARY)
+	}
+
+	if (entry->state != MDB_PERMANENT && entry->state != MDB_TEMPORARY) {
+		NL_SET_ERR_MSG_MOD(extack, "Unknown entry state");
 		return false;
-	if (entry->vid >= VLAN_VID_MASK)
+	}
+	if (entry->vid >= VLAN_VID_MASK) {
+		NL_SET_ERR_MSG_MOD(extack, "Invalid entry VLAN id");
 		return false;
+	}
 
 	return true;
 }
 
 static int br_mdb_parse(struct sk_buff *skb, struct nlmsghdr *nlh,
-			struct net_device **pdev, struct br_mdb_entry **pentry)
+			struct net_device **pdev, struct br_mdb_entry **pentry,
+			struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
 	struct br_mdb_entry *entry;
@@ -671,36 +688,37 @@ static int br_mdb_parse(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	bpm = nlmsg_data(nlh);
 	if (bpm->ifindex == 0) {
-		pr_info("PF_BRIDGE: br_mdb_parse() with invalid ifindex\n");
+		NL_SET_ERR_MSG_MOD(extack, "Invalid bridge ifindex");
 		return -EINVAL;
 	}
 
 	dev = __dev_get_by_index(net, bpm->ifindex);
 	if (dev == NULL) {
-		pr_info("PF_BRIDGE: br_mdb_parse() with unknown ifindex\n");
+		NL_SET_ERR_MSG_MOD(extack, "Bridge device doesn't exist");
 		return -ENODEV;
 	}
 
 	if (!(dev->priv_flags & IFF_EBRIDGE)) {
-		pr_info("PF_BRIDGE: br_mdb_parse() with non-bridge\n");
+		NL_SET_ERR_MSG_MOD(extack, "Device is not a bridge");
 		return -EOPNOTSUPP;
 	}
 
 	*pdev = dev;
 
-	if (!tb[MDBA_SET_ENTRY] ||
-	    nla_len(tb[MDBA_SET_ENTRY]) != sizeof(struct br_mdb_entry)) {
-		pr_info("PF_BRIDGE: br_mdb_parse() with invalid attr\n");
+	if (!tb[MDBA_SET_ENTRY]) {
+		NL_SET_ERR_MSG_MOD(extack, "Missing MDBA_SET_ENTRY attribute");
 		return -EINVAL;
 	}
-
-	entry = nla_data(tb[MDBA_SET_ENTRY]);
-	if (!is_valid_mdb_entry(entry)) {
-		pr_info("PF_BRIDGE: br_mdb_parse() with invalid entry\n");
+	if (nla_len(tb[MDBA_SET_ENTRY]) != sizeof(struct br_mdb_entry)) {
+		NL_SET_ERR_MSG_MOD(extack, "Invalid MDBA_SET_ENTRY attribute length");
 		return -EINVAL;
 	}
 
+	entry = nla_data(tb[MDBA_SET_ENTRY]);
+	if (!is_valid_mdb_entry(entry, extack))
+		return -EINVAL;
 	*pentry = entry;
+
 	return 0;
 }
 
@@ -797,7 +815,7 @@ static int br_mdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct net_bridge *br;
 	int err;
 
-	err = br_mdb_parse(skb, nlh, &dev, &entry);
+	err = br_mdb_parse(skb, nlh, &dev, &entry, extack);
 	if (err < 0)
 		return err;
 
@@ -892,7 +910,7 @@ static int br_mdb_del(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct net_bridge *br;
 	int err;
 
-	err = br_mdb_parse(skb, nlh, &dev, &entry);
+	err = br_mdb_parse(skb, nlh, &dev, &entry, extack);
 	if (err < 0)
 		return err;
 
-- 
2.25.4

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