[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/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index e089a97..8855e64 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -62,6 +62,7 @@
 #include <linux/init.h>
 #include <linux/times.h>
 
+#include <net/net_namespace.h>
 #include <net/icmp.h>
 #include <net/inet_hashtables.h>
 #include <net/tcp.h>
@@ -2249,7 +2250,7 @@
 	afinfo->seq_fops->llseek	= seq_lseek;
 	afinfo->seq_fops->release	= seq_release_private;
 
-	p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops);
+	p = proc_net_fops_create(&init_net, afinfo->name, S_IRUGO, afinfo->seq_fops);
 	if (p)
 		p->data = afinfo;
 	else
@@ -2261,7 +2262,7 @@
 {
 	if (!afinfo)
 		return;
-	proc_net_remove(afinfo->name);
+	proc_net_remove(&init_net, afinfo->name);
 	memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
 }