Commit 311cca40 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Paolo Abeni
Browse files

net: fix ifname in netlink ntf during netns move 



dev_get_valid_name() overwrites the netdev's name on success.
This makes it hard to use in prepare-commit-like fashion,
where we do validation first, and "commit" to the change
later.

Factor out a helper which lets us save the new name to a buffer.
Use it to fix the problem of notification on netns move having
incorrect name:

 5: eth0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default
     link/ether be:4d:58:f9:d5:40 brd ff:ff:ff:ff:ff:ff
 6: eth1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default
     link/ether 1e:4a:34:36:e3:cd brd ff:ff:ff:ff:ff:ff

 [ ~]# ip link set dev eth0 netns 1 name eth1

ip monitor inside netns:
 Deleted inet eth0
 Deleted inet6 eth0
 Deleted 5: eth1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default
     link/ether be:4d:58:f9:d5:40 brd ff:ff:ff:ff:ff:ff new-netnsid 0 new-ifindex 7

Name is reported as eth1 in old netns for ifindex 5, already renamed.

Fixes: d9031024 ("net: device name allocation cleanups")
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent a602ee31

net/core/dev.c

+31 −13
Original line number Diff line number Diff line
@@ -1123,6 +1123,26 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) 
	return -ENFILE;

}



static int dev_prep_valid_name(struct net *net, struct net_device *dev,

			       const char *want_name, char *out_name)

{

	int ret;



	if (!dev_valid_name(want_name))

		return -EINVAL;



	if (strchr(want_name, '%')) {

		ret = __dev_alloc_name(net, want_name, out_name);

		return ret < 0 ? ret : 0;

	} else if (netdev_name_in_use(net, want_name)) {

		return -EEXIST;

	} else if (out_name != want_name) {

		strscpy(out_name, want_name, IFNAMSIZ);

	}



	return 0;

}



static int dev_alloc_name_ns(struct net *net,

			     struct net_device *dev,

			     const char *name)
@@ -1160,19 +1180,13 @@ EXPORT_SYMBOL(dev_alloc_name); 
static int dev_get_valid_name(struct net *net, struct net_device *dev,

			      const char *name)

{

	BUG_ON(!net);



	if (!dev_valid_name(name))

		return -EINVAL;



	if (strchr(name, '%'))

		return dev_alloc_name_ns(net, dev, name);

	else if (netdev_name_in_use(net, name))

		return -EEXIST;

	else if (dev->name != name)

		strscpy(dev->name, name, IFNAMSIZ);

	char buf[IFNAMSIZ];

	int ret;



	return 0;

	ret = dev_prep_valid_name(net, dev, name, buf);

	if (ret >= 0)

		strscpy(dev->name, buf, IFNAMSIZ);

	return ret;

}



/**
@@ -11038,6 +11052,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
			       const char *pat, int new_ifindex)

{

	struct net *net_old = dev_net(dev);

	char new_name[IFNAMSIZ] = {};

	int err, new_nsid;



	ASSERT_RTNL();
@@ -11064,7 +11079,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
		/* We get here if we can't use the current device name */

		if (!pat)

			goto out;

		err = dev_get_valid_name(net, dev, pat);

		err = dev_prep_valid_name(net, dev, pat, new_name);

		if (err < 0)

			goto out;

	}
@@ -11135,6 +11150,9 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, 
	kobject_uevent(&dev->dev.kobj, KOBJ_ADD);

	netdev_adjacent_add_links(dev);



	if (new_name[0]) /* Rename the netdev to prepared name */

		strscpy(dev->name, new_name, IFNAMSIZ);



	/* Fixup kobjects */

	err = device_rename(&dev->dev, dev->name);

	WARN_ON(err);