[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>

net/core/dst.c

@@ -15,6 +15,7 @@
 #include <linux/skbuff.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <net/net_namespace.h>
 
 #include <net/dst.h>
 
@@ -252,6 +253,9 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event, void
 	struct net_device *dev = ptr;
 	struct dst_entry *dst;
 
+	if (dev->nd_net != &init_net)
+		return NOTIFY_DONE;
+
 	switch (event) {
 	case NETDEV_UNREGISTER:
 	case NETDEV_DOWN:

net/core/fib_rules.c

@@ -11,6 +11,7 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
+#include <net/net_namespace.h>
 #include <net/fib_rules.h>
 
 static LIST_HEAD(rules_ops);
@@ -596,6 +597,9 @@ static int fib_rules_event(struct notifier_block *this, unsigned long event,
 	struct net_device *dev = ptr;
 	struct fib_rules_ops *ops;
 
+	if (dev->nd_net != &init_net)
+		return NOTIFY_DONE;
+
 	ASSERT_RTNL();
 	rcu_read_lock();
 

net/core/pktgen.c

@@ -1975,6 +1975,9 @@ static int pktgen_device_event(struct notifier_block *unused,
 {
 	struct net_device *dev = ptr;
 
+	if (dev->nd_net != &init_net)
+		return NOTIFY_DONE;
+
 	/* It is OK that we do not hold the group lock right now,
 	 * as we run under the RTNL lock.
 	 */

net/core/rtnetlink.c

@@ -1286,6 +1286,10 @@ static void rtnetlink_rcv(struct sock *sk, int len)
 static int rtnetlink_event(struct notifier_block *this, unsigned long event, void *ptr)
 {
 	struct net_device *dev = ptr;
+
+	if (dev->nd_net != &init_net)
+		return NOTIFY_DONE;
+
 	switch (event) {
 	case NETDEV_UNREGISTER:
 		rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);