[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/ax25/af_ax25.c b/net/ax25/af_ax25.c
index dae2a42..1d71f85 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -44,6 +44,7 @@
 #include <linux/sysctl.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
+#include <net/net_namespace.h>
 #include <net/tcp_states.h>
 #include <net/ip.h>
 #include <net/arp.h>
@@ -1998,9 +1999,9 @@
 	register_netdevice_notifier(&ax25_dev_notifier);
 	ax25_register_sysctl();
 
-	proc_net_fops_create("ax25_route", S_IRUGO, &ax25_route_fops);
-	proc_net_fops_create("ax25", S_IRUGO, &ax25_info_fops);
-	proc_net_fops_create("ax25_calls", S_IRUGO, &ax25_uid_fops);
+	proc_net_fops_create(&init_net, "ax25_route", S_IRUGO, &ax25_route_fops);
+	proc_net_fops_create(&init_net, "ax25", S_IRUGO, &ax25_info_fops);
+	proc_net_fops_create(&init_net, "ax25_calls", S_IRUGO, &ax25_uid_fops);
 out:
 	return rc;
 }
@@ -2014,9 +2015,9 @@
 
 static void __exit ax25_exit(void)
 {
-	proc_net_remove("ax25_route");
-	proc_net_remove("ax25");
-	proc_net_remove("ax25_calls");
+	proc_net_remove(&init_net, "ax25_route");
+	proc_net_remove(&init_net, "ax25");
+	proc_net_remove(&init_net, "ax25_calls");
 	ax25_rt_free();
 	ax25_uid_free();
 	ax25_dev_free();