[NET]: Make /proc/net per network namespace

This patch makes /proc/net per network namespace.  It modifies the global
variables proc_net and proc_net_stat to be per network namespace.
The proc_net file helpers are modified to take a network namespace argument,
and all of their callers are fixed to pass &init_net for that argument.
This ensures that all of the /proc/net files are only visible and
usable in the initial network namespace until the code behind them
has been updated to be handle multiple network namespaces.

Making /proc/net per namespace is necessary as at least some files
in /proc/net depend upon the set of network devices which is per
network namespace, and even more files in /proc/net have contents
that are relevant to a single network namespace.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9c26dd9..5650229 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -61,6 +61,7 @@
 #include <linux/wireless.h>
 #include <linux/kernel.h>
 #include <linux/kmod.h>
+#include <net/net_namespace.h>
 #include <net/ip.h>
 #include <net/protocol.h>
 #include <linux/skbuff.h>
@@ -1951,7 +1952,7 @@
 
 static void __exit packet_exit(void)
 {
-	proc_net_remove("packet");
+	proc_net_remove(&init_net, "packet");
 	unregister_netdevice_notifier(&packet_netdev_notifier);
 	sock_unregister(PF_PACKET);
 	proto_unregister(&packet_proto);
@@ -1966,7 +1967,7 @@
 
 	sock_register(&packet_family_ops);
 	register_netdevice_notifier(&packet_netdev_notifier);
-	proc_net_fops_create("packet", 0, &packet_seq_fops);
+	proc_net_fops_create(&init_net, "packet", 0, &packet_seq_fops);
 out:
 	return rc;
 }