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net: fix ifname in netlink ntf during netns move

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[ Upstream commit 311cca4066 ]

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: d90310243f ("net: device name allocation cleanups")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jakub Kicinski 2023-10-17 18:38:13 -07:00 committed by Greg Kroah-Hartman
parent ac43ec299a
commit 3f928d1362
1 changed files with 31 additions and 13 deletions
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44
net/core/dev.c
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@ -1151,6 +1151,26 @@ 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)
@ -1188,19 +1208,13 @@ EXPORT_SYMBOL(dev_alloc_name);
static int dev_get_valid_name(struct net *net, struct net_device *dev,
const char *name)
{
BUG_ON(!net);
char buf[IFNAMSIZ];
int ret;
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);
return 0;
ret = dev_prep_valid_name(net, dev, name, buf);
if (ret >= 0)
strscpy(dev->name, buf, IFNAMSIZ);
return ret;
}
/**
@ -11154,6 +11168,7 @@ 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();
@ -11180,7 +11195,7 @@ 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;
}
@ -11248,6 +11263,9 @@ 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);