netdev - [PATCH net 1/3] rtnetlink: move validate_linkmsg into rtnl_create

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Date: Thu, 25 May 2023 17:49:15 -0400
From: Xin Long <lucien.xin@...il.com>
To: network dev <netdev@...r.kernel.org>
Cc: davem@...emloft.net,
	kuba@...nel.org,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Thomas Graf <tgraf@...radead.org>,
	Alexander Duyck <alexanderduyck@...com>
Subject: [PATCH net 1/3] rtnetlink: move validate_linkmsg into rtnl_create_link

In commit 644c7eebbfd5 ("rtnetlink: validate attributes in do_setlink()"),
it moved validate_linkmsg() from rtnl_setlink() to do_setlink(). However,
as validate_linkmsg() is also called in __rtnl_newlink(), it caused
validate_linkmsg() being called twice when running 'ip link set'.

The validate_linkmsg() was introduced by commit 1840bb13c22f5b ("[RTNL]:
Validate hardware and broadcast address attribute for RTM_NEWLINK") for
existing links. After adding it in do_setlink(), there's no need to call
it in __rtnl_newlink().

Instead of deleting it from __rtnl_newlink(), this patch moves it to
rtnl_create_link() to fix the missing validation for the new created
links.

Fixes: 644c7eebbfd5 ("rtnetlink: validate attributes in do_setlink()")
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/core/rtnetlink.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 653901a1bf75..d1f88ba7e391 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2377,15 +2377,13 @@ static	int rtnl_set_vf_rate(struct net_device *dev, int vf, int min_tx_rate,
 static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
 			    struct netlink_ext_ack *extack)
 {
-	if (dev) {
-		if (tb[IFLA_ADDRESS] &&
-		    nla_len(tb[IFLA_ADDRESS]) < dev->addr_len)
-			return -EINVAL;
+	if (tb[IFLA_ADDRESS] &&
+	    nla_len(tb[IFLA_ADDRESS]) < dev->addr_len)
+		return -EINVAL;
 
-		if (tb[IFLA_BROADCAST] &&
-		    nla_len(tb[IFLA_BROADCAST]) < dev->addr_len)
-			return -EINVAL;
-	}
+	if (tb[IFLA_BROADCAST] &&
+	    nla_len(tb[IFLA_BROADCAST]) < dev->addr_len)
+		return -EINVAL;
 
 	if (tb[IFLA_AF_SPEC]) {
 		struct nlattr *af;
@@ -3285,6 +3283,7 @@ struct net_device *rtnl_create_link(struct net *net, const char *ifname,
 	struct net_device *dev;
 	unsigned int num_tx_queues = 1;
 	unsigned int num_rx_queues = 1;
+	int err;
 
 	if (tb[IFLA_NUM_TX_QUEUES])
 		num_tx_queues = nla_get_u32(tb[IFLA_NUM_TX_QUEUES]);
@@ -3320,13 +3319,18 @@ struct net_device *rtnl_create_link(struct net *net, const char *ifname,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
+	err = validate_linkmsg(dev, tb, extack);
+	if (err < 0) {
+		free_netdev(dev);
+		return ERR_PTR(err);
+	}
+
 	dev_net_set(dev, net);
 	dev->rtnl_link_ops = ops;
 	dev->rtnl_link_state = RTNL_LINK_INITIALIZING;
 
 	if (tb[IFLA_MTU]) {
 		u32 mtu = nla_get_u32(tb[IFLA_MTU]);
-		int err;
 
 		err = dev_validate_mtu(dev, mtu, extack);
 		if (err) {
@@ -3534,10 +3538,6 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 			m_ops = master_dev->rtnl_link_ops;
 	}
 
-	err = validate_linkmsg(dev, tb, extack);
-	if (err < 0)
-		return err;
-
 	if (tb[IFLA_LINKINFO]) {
 		err = nla_parse_nested_deprecated(linkinfo, IFLA_INFO_MAX,
 						  tb[IFLA_LINKINFO],
-- 
2.39.1