[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>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index b80ef57..0c7382f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2409,7 +2409,7 @@
 		return -EINVAL;
 }
 
-ctl_table ipv6_route_table[] = {
+ctl_table ipv6_route_table_template[] = {
 	{
 		.procname	=	"flush",
 		.data		=	&flush_delay,
@@ -2499,6 +2499,15 @@
 	{ .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)