[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>

net/ipv6/mcast.c

@@ -49,6 +49,7 @@
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv6.h>
 
+#include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/snmp.h>
 
@@ -2658,8 +2659,8 @@ int __init igmp6_init(struct net_proto_family *ops)
 	np->hop_limit = 1;
 
 #ifdef CONFIG_PROC_FS
-	proc_net_fops_create("igmp6", S_IRUGO, &igmp6_mc_seq_fops);
-	proc_net_fops_create("mcfilter6", S_IRUGO, &igmp6_mcf_seq_fops);
+	proc_net_fops_create(&init_net, "igmp6", S_IRUGO, &igmp6_mc_seq_fops);
+	proc_net_fops_create(&init_net, "mcfilter6", S_IRUGO, &igmp6_mcf_seq_fops);
 #endif
 
 	return 0;
@@ -2671,7 +2672,7 @@ void igmp6_cleanup(void)
 	igmp6_socket = NULL; /* for safety */
 
 #ifdef CONFIG_PROC_FS
-	proc_net_remove("mcfilter6");
-	proc_net_remove("igmp6");
+	proc_net_remove(&init_net, "mcfilter6");
+	proc_net_remove(&init_net, "igmp6");
 #endif
 }