[NET]: Make device event notification network namespace safe

Every user of the network device notifiers is either a protocol
stack or a pseudo device.  If a protocol stack that does not have
support for multiple network namespaces receives an event for a
device that is not in the initial network namespace it quite possibly
can get confused and do the wrong thing.

To avoid problems until all of the protocol stacks are converted
this patch modifies all netdev event handlers to ignore events on
devices that are not in the initial network namespace.

As the rest of the code is made network namespace aware these
checks can be removed.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index 60c0e4e17875..c5c70e4b1d36 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -301,6 +301,9 @@ static int pppoe_device_event(struct notifier_block *this,
 {
         struct net_device *dev = (struct net_device *) ptr;
 
+        if (dev->nd_net != &init_net)
+                return NOTIFY_DONE;
+
         /* Only look at sockets that are using this specific device. */
         switch (event) {
         case NETDEV_CHANGEMTU: