[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>

Documentation/networking/ip-sysctl.txt

@@ -765,6 +765,9 @@ conf/all/forwarding - BOOLEAN
 
 	This referred to as global forwarding.
 
+proxy_ndp - BOOLEAN
+	Do proxy ndp.
+
 conf/interface/*:
 	Change special settings per interface.
 

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
 };
 

net/ipv6/addrconf.c

@@ -175,6 +175,7 @@ struct ipv6_devconf ipv6_devconf __read_mostly = {
 	.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 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
 	.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 @@ static void inline ipv6_store_devconf(struct ipv6_devconf *cnf,
 	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 */
@@ -3859,6 +3862,14 @@ static struct addrconf_sysctl_table
 		},
 #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 */
 		}

net/ipv6/ip6_output.c

@@ -412,7 +412,9 @@ int ip6_forward(struct sk_buff *skb)
 		return -ETIMEDOUT;
 	}
 
-	if (pneigh_lookup(&nd_tbl, &hdr->daddr, skb->dev, 0)) {
+	/* XXX: idev->cnf.proxy_ndp? */
+	if (ipv6_devconf.proxy_ndp &&
+	    pneigh_lookup(&nd_tbl, &hdr->daddr, skb->dev, 0)) {
 		int proxied = ip6_forward_proxy_check(skb);
 		if (proxied > 0)
 			return ip6_input(skb);

net/ipv6/ndisc.c

@@ -824,6 +824,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 
 		if (ipv6_chk_acast_addr(dev, &msg->target) ||
 		    (idev->cnf.forwarding && 
+		     (ipv6_devconf.proxy_ndp || idev->cnf.proxy_ndp) &&
 		     (pneigh = pneigh_lookup(&nd_tbl,
 					     &msg->target, dev, 0)) != NULL)) {
 			if (!(NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED) &&
@@ -966,8 +967,13 @@ static void ndisc_recv_na(struct sk_buff *skb)
 		 * has already sent a NA to us.
 		 */
 		if (lladdr && !memcmp(lladdr, dev->dev_addr, dev->addr_len) &&
-		    pneigh_lookup(&nd_tbl, &msg->target, dev, 0))
+		    ipv6_devconf.forwarding && ipv6_devconf.proxy_ndp &&
+		    pneigh_lookup(&nd_tbl, &msg->target, dev, 0)) {
+			/* XXX: idev->cnf.prixy_ndp */
+			WARN_ON(skb->dst != NULL &&
+				((struct rt6_info *)skb->dst)->rt6i_idev);
 			goto out;
+		}
 
 		neigh_update(neigh, lladdr,
 			     msg->icmph.icmp6_solicited ? NUD_REACHABLE : NUD_STALE,