[IPV6] NDISC: Add proxy_ndp sysctl.

We do not always need proxy NDP functionality even we
enable forwarding.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1e5a296..825a291 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -175,6 +175,7 @@
 	.accept_ra_rt_info_max_plen = 0,
 #endif
 #endif
+	.proxy_ndp		= 0,
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@@ -205,6 +206,7 @@
 	.accept_ra_rt_info_max_plen = 0,
 #endif
 #endif
+	.proxy_ndp		= 0,
 };
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@@ -3337,6 +3339,7 @@
 	array[DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN] = cnf->accept_ra_rt_info_max_plen;
 #endif
 #endif
+	array[DEVCONF_PROXY_NDP] = cnf->proxy_ndp;
 }
 
 /* Maximum length of ifinfomsg attributes */
@@ -3860,6 +3863,14 @@
 #endif
 #endif
 		{
+			.ctl_name	=	NET_IPV6_PROXY_NDP,
+			.procname	=	"proxy_ndp",
+			.data		=	&ipv6_devconf.proxy_ndp,
+			.maxlen		=	sizeof(int),
+			.mode		=	0644,
+			.proc_handler	=	&proc_dointvec,
+		},
+		{
 			.ctl_name	=	0,	/* sentinel */
 		}
 	},