[PATCH 3.14 94/98] net: prevent of emerging cross-namespace symlinks

Greg Kroah-Hartman
2015-01-25T19:08:37Z

From: "Alexander Y. Fomichev" <git.user@gmail.com>

commit 4c75431ac3520631f1d9e74aa88407e6374dbbc4 upstream.

Code manipulating sysfs symlinks on adjacent net_devices(s)
currently doesn't take into account that devices potentially
belong to different namespaces.

This patch trying to fix an issue as follows:
- check for net_ns before creating / deleting symlink.
for now only netdev_adjacent_rename_links and
__netdev_adjacent_dev_remove are affected, afaics
__netdev_adjacent_dev_insert implies both net_devs
belong to the same namespace.
- Drop all existing symlinks to / from all adj_devs before
switching namespace and recreate them just after.

Signed-off-by: Alexander Y. Fomichev <git.user@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Miquel van Smoorenburg <mikevs@xs4all.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/core/dev.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 60 insertions(+), 1 deletion(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4791,7 +4791,8 @@ static void __netdev_adjacent_dev_remove
if (adj->master)
sysfs_remove_link(&(dev->dev.kobj), "master");

- if (netdev_adjacent_is_neigh_list(dev, dev_list))
+ if (netdev_adjacent_is_neigh_list(dev, dev_list) &&
+ net_eq(dev_net(dev),dev_net(adj_dev)))
netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);

list_del_rcu(&adj->list);
@@ -5061,11 +5062,65 @@ void netdev_upper_dev_unlink(struct net_
}
EXPORT_SYMBOL(netdev_upper_dev_unlink);

+void netdev_adjacent_add_links(struct net_device *dev)
+{
+ struct netdev_adjacent *iter;
+
+ struct net *net = dev_net(dev);
+
+ list_for_each_entry(iter, &dev->adj_list.upper, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
+ netdev_adjacent_sysfs_add(iter->dev, dev,
+ &iter->dev->adj_list.lower);
+ netdev_adjacent_sysfs_add(dev, iter->dev,
+ &dev->adj_list.upper);
+ }
+
+ list_for_each_entry(iter, &dev->adj_list.lower, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
+ netdev_adjacent_sysfs_add(iter->dev, dev,
+ &iter->dev->adj_list.upper);
+ netdev_adjacent_sysfs_add(dev, iter->dev,
+ &dev->adj_list.lower);
+ }
+}
+
+void netdev_adjacent_del_links(struct net_device *dev)
+{
+ struct netdev_adjacent *iter;
+
+ struct net *net = dev_net(dev);
+
+ list_for_each_entry(iter, &dev->adj_list.upper, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
+ netdev_adjacent_sysfs_del(iter->dev, dev->name,
+ &iter->dev->adj_list.lower);
+ netdev_adjacent_sysfs_del(dev, iter->dev->name,
+ &dev->adj_list.upper);
+ }
+
+ list_for_each_entry(iter, &dev->adj_list.lower, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
+ netdev_adjacent_sysfs_del(iter->dev, dev->name,
+ &iter->dev->adj_list.upper);
+ netdev_adjacent_sysfs_del(dev, iter->dev->name,
+ &dev->adj_list.lower);
+ }
+}
+
void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
{
struct netdev_adjacent *iter;

+ struct net *net = dev_net(dev);
+
list_for_each_entry(iter, &dev->adj_list.upper, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
netdev_adjacent_sysfs_del(iter->dev, oldname,
&iter->dev->adj_list.lower);
netdev_adjacent_sysfs_add(iter->dev, dev,
@@ -5073,6 +5128,8 @@ void netdev_adjacent_rename_links(struct
}

list_for_each_entry(iter, &dev->adj_list.lower, list) {
+ if (!net_eq(net,dev_net(iter->dev)))
+ continue;
netdev_adjacent_sysfs_del(iter->dev, oldname,
&iter->dev->adj_list.upper);
netdev_adjacent_sysfs_add(iter->dev, dev,
@@ -6679,6 +6736,7 @@ int dev_change_net_namespace(struct net_

/* Send a netdev-removed uevent to the old namespace */
kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
+ netdev_adjacent_del_links(dev);

/* Actually switch the network namespace */
dev_net_set(dev, net);
@@ -6693,6 +6751,7 @@ int dev_change_net_namespace(struct net_

/* Send a netdev-add uevent to the new namespace */
kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
+ netdev_adjacent_add_links(dev);

/* Fixup kobjects */
err = device_rename(&dev->dev, dev->name);