[NETNS][IPV6]: Make multiple instance of sysctl tables.

Each network namespace wants its own set of sysctl value, eg. we
should not be able from a namespace to set a sysctl value for another
namespace , especially for the initial network namespace.

This patch duplicates the sysctl table when we register a new network
namespace for ipv6. The duplicated table are postfixed with the
"template" word to notify the developper the table is cloned.
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ipv6.h

@@ -619,8 +619,8 @@ static inline int snmp6_unregister_dev(struct inet6_dev *idev)
 #endif
 
 #ifdef CONFIG_SYSCTL
-extern ctl_table ipv6_route_table[];
-extern ctl_table ipv6_icmp_table[];
+extern ctl_table ipv6_route_table_template[];
+extern ctl_table ipv6_icmp_table_template[];
 
 extern int ipv6_sysctl_register(void);
 extern void ipv6_sysctl_unregister(void);

include/net/netns/ipv6.h

@@ -5,6 +5,15 @@
 #ifndef __NETNS_IPV6_H__
 #define __NETNS_IPV6_H__
 
+struct ctl_table_header;
+
+struct netns_sysctl_ipv6 {
+#ifdef CONFIG_SYSCTL
+	struct ctl_table_header *table;
+#endif
+};
+
 struct netns_ipv6 {
+	struct netns_sysctl_ipv6 sysctl;
 };
 #endif

net/ipv6/icmp.c

@@ -907,7 +907,7 @@ int icmpv6_err_convert(int type, int code, int *err)
 EXPORT_SYMBOL(icmpv6_err_convert);
 
 #ifdef CONFIG_SYSCTL
-ctl_table ipv6_icmp_table[] = {
+ctl_table ipv6_icmp_table_template[] = {
 	{
 		.ctl_name	= NET_IPV6_ICMP_RATELIMIT,
 		.procname	= "ratelimit",
@@ -918,5 +918,15 @@ ctl_table ipv6_icmp_table[] = {
 	},
 	{ .ctl_name = 0 },
 };
+
+struct ctl_table *ipv6_icmp_sysctl_init(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = kmemdup(ipv6_icmp_table_template,
+			sizeof(ipv6_icmp_table_template),
+			GFP_KERNEL);
+	return table;
+}
 #endif
 

net/ipv6/route.c

@@ -2409,7 +2409,7 @@ int ipv6_sysctl_rtcache_flush(ctl_table *ctl, int write, struct file * filp,
 		return -EINVAL;
 }
 
-ctl_table ipv6_route_table[] = {
+ctl_table ipv6_route_table_template[] = {
 	{
 		.procname	=	"flush",
 		.data		=	&flush_delay,
@@ -2499,6 +2499,15 @@ ctl_table ipv6_route_table[] = {
 	{ .ctl_name = 0 }
 };
 
+struct ctl_table *ipv6_route_sysctl_init(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = kmemdup(ipv6_route_table_template,
+			sizeof(ipv6_route_table_template),
+			GFP_KERNEL);
+	return table;
+}
 #endif
 
 int __init ip6_route_init(void)

net/ipv6/sysctl_net_ipv6.c

@@ -14,20 +14,23 @@
 #include <net/addrconf.h>
 #include <net/inet_frag.h>
 
-static ctl_table ipv6_table[] = {
+extern struct ctl_table *ipv6_route_sysctl_init(struct net *net);
+extern struct ctl_table *ipv6_icmp_sysctl_init(struct net *net);
+
+static ctl_table ipv6_table_template[] = {
 	{
 		.ctl_name	= NET_IPV6_ROUTE,
 		.procname	= "route",
 		.maxlen		= 0,
 		.mode		= 0555,
-		.child		= ipv6_route_table
+		.child		= ipv6_route_table_template
 	},
 	{
 		.ctl_name	= NET_IPV6_ICMP,
 		.procname	= "icmp",
 		.maxlen		= 0,
 		.mode		= 0555,
-		.child		= ipv6_icmp_table
+		.child		= ipv6_icmp_table_template
 	},
 	{
 		.ctl_name	= NET_IPV6_BINDV6ONLY,
@@ -89,22 +92,66 @@ struct ctl_path net_ipv6_ctl_path[] = {
 };
 EXPORT_SYMBOL_GPL(net_ipv6_ctl_path);
 
-static struct ctl_table_header *ipv6_sysctl_header;
-
 static int ipv6_sysctl_net_init(struct net *net)
 {
-	ipv6_sysctl_header = register_net_sysctl_table(net, net_ipv6_ctl_path,
+	struct ctl_table *ipv6_table;
+	struct ctl_table *ipv6_route_table;
+	struct ctl_table *ipv6_icmp_table;
+	int err;
+
+	err = -ENOMEM;
+	ipv6_table = kmemdup(ipv6_table_template, sizeof(ipv6_table_template),
+			     GFP_KERNEL);
+	if (!ipv6_table)
+		goto out;
+
+	ipv6_route_table = ipv6_route_sysctl_init(net);
+	if (!ipv6_route_table)
+		goto out_ipv6_table;
+
+	ipv6_icmp_table = ipv6_icmp_sysctl_init(net);
+	if (!ipv6_icmp_table)
+		goto out_ipv6_route_table;
+
+	ipv6_table[0].child = ipv6_route_table;
+	ipv6_table[1].child = ipv6_icmp_table;
+
+	net->ipv6.sysctl.table = register_net_sysctl_table(net, net_ipv6_ctl_path,
 							   ipv6_table);
-	if (!ipv6_sysctl_header)
+	if (!net->ipv6.sysctl.table)
 		return -ENOMEM;
 
-	return 0;
+	if (!net->ipv6.sysctl.table)
+		goto out_ipv6_icmp_table;
+
+	err = 0;
+out:
+	return err;
 
+out_ipv6_icmp_table:
+	kfree(ipv6_icmp_table);
+out_ipv6_route_table:
+	kfree(ipv6_route_table);
+out_ipv6_table:
+	kfree(ipv6_table);
+	goto out;
 }
 
 static void ipv6_sysctl_net_exit(struct net *net)
 {
-	unregister_net_sysctl_table(ipv6_sysctl_header);
+	struct ctl_table *ipv6_table;
+	struct ctl_table *ipv6_route_table;
+	struct ctl_table *ipv6_icmp_table;
+
+	ipv6_table = net->ipv6.sysctl.table->ctl_table_arg;
+	ipv6_route_table = ipv6_table[0].child;
+	ipv6_icmp_table = ipv6_table[1].child;
+
+	unregister_net_sysctl_table(net->ipv6.sysctl.table);
+
+	kfree(ipv6_table);
+	kfree(ipv6_route_table);
+	kfree(ipv6_icmp_table);
 }
 
 static struct pernet_operations ipv6_sysctl_net_ops = {