[IPV6]: Disallow RH0 by default.

A security issue is emerging.  Disallow Routing Header Type 0 by default
as we have been doing for IPv4.
Note: We allow RH2 by default because it is harmless.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 2c5fb38..9a8970b 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -580,6 +580,7 @@
 	NET_IPV6_RTR_PROBE_INTERVAL=21,
 	NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
 	NET_IPV6_PROXY_NDP=23,
+	NET_IPV6_ACCEPT_SOURCE_ROUTE=25,
 	__NET_IPV6_MAX
 };