[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/key/af_key.c b/net/key/af_key.c
index 0241fff..5b802bb 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -26,6 +26,7 @@
 #include <linux/in6.h>
 #include <linux/proc_fs.h>
 #include <linux/init.h>
+#include <net/net_namespace.h>
 #include <net/xfrm.h>
 
 #include <net/sock.h>
@@ -3776,7 +3777,7 @@
 static void __exit ipsec_pfkey_exit(void)
 {
 	xfrm_unregister_km(&pfkeyv2_mgr);
-	remove_proc_entry("net/pfkey", NULL);
+	remove_proc_entry("pfkey", init_net.proc_net);
 	sock_unregister(PF_KEY);
 	proto_unregister(&key_proto);
 }
@@ -3793,7 +3794,7 @@
 		goto out_unregister_key_proto;
 #ifdef CONFIG_PROC_FS
 	err = -ENOMEM;
-	if (create_proc_read_entry("net/pfkey", 0, NULL, pfkey_read_proc, NULL) == NULL)
+	if (create_proc_read_entry("pfkey", 0, init_net.proc_net, pfkey_read_proc, NULL) == NULL)
 		goto out_sock_unregister;
 #endif
 	err = xfrm_register_km(&pfkeyv2_mgr);