This is the core.

Add all and default pointers on the netns_ipv4 and register
a new pernet subsys to initialize them.

Also add the ctl_table_header to register the 
net.ipv4.ip_forward ctl.

I don't allocate additional memory for init_net, but use
global devinets.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index ce830d5..e06d7cf 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -4,6 +4,12 @@
 
 #ifndef __NETNS_IPV4_H__
 #define __NETNS_IPV4_H__
+struct ctl_table_header;
+struct ipv4_devconf;
+
 struct netns_ipv4 {
+	struct ctl_table_header	*forw_hdr;
+	struct ipv4_devconf	*devconf_all;
+	struct ipv4_devconf	*devconf_dflt;
 };
 #endif
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index bfb0fb0..996f07e 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -62,6 +62,7 @@
 #include <net/route.h>
 #include <net/ip_fib.h>
 #include <net/rtnetlink.h>
+#include <net/net_namespace.h>
 
 struct ipv4_devconf ipv4_devconf = {
 	.data = {
@@ -1498,7 +1499,7 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name,
 	devinet_ctl_path[DEVINET_CTL_PATH_DEV].procname = t->dev_name;
 	devinet_ctl_path[DEVINET_CTL_PATH_DEV].ctl_name = ctl_name;
 
-	t->sysctl_header = register_sysctl_paths(devinet_ctl_path,
+	t->sysctl_header = register_net_sysctl_table(net, devinet_ctl_path,
 			t->devinet_vars);
 	if (!t->sysctl_header)
 		goto free_procname;
@@ -1558,27 +1559,113 @@ static struct ctl_table ctl_forward_entry[] = {
 	{ },
 };
 
-static __initdata struct ctl_path net_ipv4_path[] = {
+static __net_initdata struct ctl_path net_ipv4_path[] = {
 	{ .procname = "net", .ctl_name = CTL_NET, },
 	{ .procname = "ipv4", .ctl_name = NET_IPV4, },
 	{ },
 };
 
+static __net_init int devinet_init_net(struct net *net)
+{
+	int err;
+	struct ctl_table *tbl;
+	struct ipv4_devconf *all, *dflt;
+	struct ctl_table_header *forw_hdr;
+
+	err = -ENOMEM;
+	all = &ipv4_devconf;
+	dflt = &ipv4_devconf_dflt;
+	tbl = ctl_forward_entry;
+
+	if (net != &init_net) {
+		all = kmemdup(all, sizeof(ipv4_devconf), GFP_KERNEL);
+		if (all == NULL)
+			goto err_alloc_all;
+
+		dflt = kmemdup(dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
+		if (dflt == NULL)
+			goto err_alloc_dflt;
+
+		tbl = kmemdup(tbl, sizeof(ctl_forward_entry), GFP_KERNEL);
+		if (tbl == NULL)
+			goto err_alloc_ctl;
+
+		tbl[0].data = &all->data[NET_IPV4_CONF_FORWARDING - 1];
+		tbl[0].extra1 = all;
+		tbl[0].extra2 = net;
+	}
+
+#ifdef CONFIG_SYSCTL
+	err = __devinet_sysctl_register(net, "all",
+			NET_PROTO_CONF_ALL, all);
+	if (err < 0)
+		goto err_reg_all;
+
+	err = __devinet_sysctl_register(net, "default",
+			NET_PROTO_CONF_DEFAULT, dflt);
+	if (err < 0)
+		goto err_reg_dflt;
+
+	err = -ENOMEM;
+	forw_hdr = register_net_sysctl_table(net, net_ipv4_path, tbl);
+	if (forw_hdr == NULL)
+		goto err_reg_ctl;
+#endif
+
+	net->ipv4.forw_hdr = forw_hdr;
+	net->ipv4.devconf_all = all;
+	net->ipv4.devconf_dflt = dflt;
+	return 0;
+
+#ifdef CONFIG_SYSCTL
+err_reg_ctl:
+	__devinet_sysctl_unregister(dflt);
+err_reg_dflt:
+	__devinet_sysctl_unregister(all);
+err_reg_all:
+	if (tbl != ctl_forward_entry)
+		kfree(tbl);
+#endif
+err_alloc_ctl:
+	if (dflt != &ipv4_devconf_dflt)
+		kfree(dflt);
+err_alloc_dflt:
+	if (all != &ipv4_devconf)
+		kfree(all);
+err_alloc_all:
+	return err;
+}
+
+static __net_exit void devinet_exit_net(struct net *net)
+{
+	struct ctl_table *tbl;
+
+	tbl = net->ipv4.forw_hdr->ctl_table_arg;
+#ifdef CONFIG_SYSCTL
+	unregister_net_sysctl_table(net->ipv4.forw_hdr);
+	__devinet_sysctl_unregister(net->ipv4.devconf_dflt);
+	__devinet_sysctl_unregister(net->ipv4.devconf_all);
+#endif
+	kfree(tbl);
+	kfree(net->ipv4.devconf_dflt);
+	kfree(net->ipv4.devconf_all);
+}
+
+static __net_initdata struct pernet_operations devinet_ops = {
+	.init = devinet_init_net,
+	.exit = devinet_exit_net,
+};
+
 void __init devinet_init(void)
 {
+	register_pernet_subsys(&devinet_ops);
+
 	register_gifconf(PF_INET, inet_gifconf);
 	register_netdevice_notifier(&ip_netdev_notifier);
 
 	rtnl_register(PF_INET, RTM_NEWADDR, inet_rtm_newaddr, NULL);
 	rtnl_register(PF_INET, RTM_DELADDR, inet_rtm_deladdr, NULL);
 	rtnl_register(PF_INET, RTM_GETADDR, NULL, inet_dump_ifaddr);
-#ifdef CONFIG_SYSCTL
-	__devinet_sysctl_register(&init_net, "all", NET_PROTO_CONF_ALL,
-			&ipv4_devconf);
-	__devinet_sysctl_register(&init_net, "default", NET_PROTO_CONF_DEFAULT,
-			&ipv4_devconf_dflt);
-	register_sysctl_paths(net_ipv4_path, ctl_forward_entry);
-#endif
 }
 
 EXPORT_SYMBOL(in_dev_finish_destroy);
-- 
1.5.3.4