[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/unix/af_unix.c b/net/unix/af_unix.c
index a05c342..2386090 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -103,6 +103,7 @@
 #include <asm/uaccess.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
+#include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <net/af_unix.h>
@@ -2135,7 +2136,7 @@
 
 	sock_register(&unix_family_ops);
 #ifdef CONFIG_PROC_FS
-	proc_net_fops_create("unix", 0, &unix_seq_fops);
+	proc_net_fops_create(&init_net, "unix", 0, &unix_seq_fops);
 #endif
 	unix_sysctl_register();
 out:
@@ -2146,7 +2147,7 @@
 {
 	sock_unregister(PF_UNIX);
 	unix_sysctl_unregister();
-	proc_net_remove("unix");
+	proc_net_remove(&init_net, "unix");
 	proto_unregister(&unix_proto);
 }