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net: introduce a function to check if a netdev name is in use 

[ Upstream commit 75ea27d0d6 ]

__dev_get_by_name is currently used to either retrieve a net device
reference using its name or to check if a name is already used by a
registered net device (per ns). In the later case there is no need to
return a reference to a net device.

Introduce a new helper, netdev_name_in_use, to check if a name is
currently used by a registered net device without leaking a reference
the corresponding net device. This helper uses netdev_name_node_lookup
instead of __dev_get_by_name as we don't need the extra logic retrieving
a reference to the corresponding net device.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 311cca4066 ("net: fix ifname in netlink ntf during netns move")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Antoine Tenart 2021-10-07 18:16:50 +02:00 committed by Greg Kroah-Hartman
parent 38ba547935
commit 30e2db4030
2 changed files with 11 additions and 4 deletions
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1
include/linux/netdevice.h
View File

@ -2978,6 +2978,7 @@ struct net_device *__dev_get_by_flags(struct net *net, unsigned short flags,
struct net_device *dev_get_by_name(struct net *net, const char *name);
struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);
struct net_device *__dev_get_by_name(struct net *net, const char *name);
bool netdev_name_in_use(struct net *net, const char *name);
int dev_alloc_name(struct net_device *dev, const char *name);
int dev_open(struct net_device *dev, struct netlink_ext_ack *extack);
void dev_close(struct net_device *dev);

14
net/core/dev.c
View File

@ -303,6 +303,12 @@ static struct netdev_name_node *netdev_name_node_lookup_rcu(struct net *net,
return NULL;
}
bool netdev_name_in_use(struct net *net, const char *name)
{
return netdev_name_node_lookup(net, name);
}
EXPORT_SYMBOL(netdev_name_in_use);
int netdev_name_node_alt_create(struct net_device *dev, const char *name)
{
struct netdev_name_node *name_node;
@ -1135,7 +1141,7 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf)
}
snprintf(buf, IFNAMSIZ, name, i);
if (!__dev_get_by_name(net, buf))
if (!netdev_name_in_use(net, buf))
return i;
/* It is possible to run out of possible slots
@ -1189,7 +1195,7 @@ static int dev_get_valid_name(struct net *net, struct net_device *dev,
if (strchr(name, '%'))
return dev_alloc_name_ns(net, dev, name);
else if (__dev_get_by_name(net, name))
else if (netdev_name_in_use(net, name))
return -EEXIST;
else if (dev->name != name)
strlcpy(dev->name, name, IFNAMSIZ);
@ -11170,7 +11176,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
* we can use it in the destination network namespace.
*/
err = -EEXIST;
if (__dev_get_by_name(net, dev->name)) {
if (netdev_name_in_use(net, dev->name)) {
/* We get here if we can't use the current device name */
if (!pat)
goto out;
@ -11522,7 +11528,7 @@ static void __net_exit default_device_exit(struct net *net)
/* Push remaining network devices to init_net */
snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
if (__dev_get_by_name(&init_net, fb_name))
if (netdev_name_in_use(&init_net, fb_name))
snprintf(fb_name, IFNAMSIZ, "dev%%d");
err = dev_change_net_namespace(dev, &init_net, fb_name);
if (err) {