[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>

include/linux/ipv6.h

@@ -176,6 +176,7 @@ struct ipv6_devconf {
 	__s32		accept_ra_rt_info_max_plen;
 #endif
 #endif
+	__s32		proxy_ndp;
 	void		*sysctl;
 };
 
@@ -203,6 +204,7 @@ enum {
 	DEVCONF_ACCEPT_RA_RTR_PREF,
 	DEVCONF_RTR_PROBE_INTERVAL,
 	DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN,
+	DEVCONF_PROXY_NDP,
 	DEVCONF_MAX
 };
 

include/linux/sysctl.h

@@ -556,6 +556,7 @@ enum {
 	NET_IPV6_ACCEPT_RA_RTR_PREF=20,
 	NET_IPV6_RTR_PROBE_INTERVAL=21,
 	NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
+	NET_IPV6_PROXY_NDP=23,
 	__NET_IPV6_MAX
 };