[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/core/neighbour.c b/net/core/neighbour.c
index ecd43c4..5f25f4f 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -25,6 +25,7 @@
 #include <linux/sysctl.h>
 #endif
 #include <linux/times.h>
+#include <net/net_namespace.h>
 #include <net/neighbour.h>
 #include <net/dst.h>
 #include <net/sock.h>
@@ -1350,7 +1351,7 @@
 		panic("cannot create neighbour cache statistics");
 
 #ifdef CONFIG_PROC_FS
-	tbl->pde = create_proc_entry(tbl->id, 0, proc_net_stat);
+	tbl->pde = create_proc_entry(tbl->id, 0, init_net.proc_net_stat);
 	if (!tbl->pde)
 		panic("cannot create neighbour proc dir entry");
 	tbl->pde->proc_fops = &neigh_stat_seq_fops;