[IPV6]: ADDRCONF: Add accept_ra_pinfo sysctl.

This controls whether we accept Prefix Information in RAs.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

@@ -723,6 +723,12 @@ accept_ra_defrtr - BOOLEAN
 	Functional default: enabled if accept_ra is enabled.
 			    disabled if accept_ra is disabled.
 
+accept_ra_pinfo - BOOLEAN
+	Learn Prefix Inforamtion in Router Advertisement.
+
+	Functional default: enabled if accept_ra is enabled.
+			    disabled if accept_ra is disabled.
+
 accept_redirects - BOOLEAN
 	Accept Redirects.
 
@@ -733,8 +739,8 @@ autoconf - BOOLEAN
 	Autoconfigure addresses using Prefix Information in Router 
 	Advertisements.
 
-	Functional default: enabled if accept_ra is enabled.
-			    disabled if accept_ra is disabled.
+	Functional default: enabled if accept_ra_pinfo is enabled.
+			    disabled if accept_ra_pinfo is disabled.
 
 dad_transmits - INTEGER
 	The amount of Duplicate Address Detection probes to send.

include/linux/ipv6.h

@@ -146,6 +146,7 @@ struct ipv6_devconf {
 #endif
 	__s32		max_addresses;
 	__s32		accept_ra_defrtr;
+	__s32		accept_ra_pinfo;
 	void		*sysctl;
 };
 
@@ -169,6 +170,7 @@ enum {
 	DEVCONF_MAX_ADDRESSES,
 	DEVCONF_FORCE_MLD_VERSION,
 	DEVCONF_ACCEPT_RA_DEFRTR,
+	DEVCONF_ACCEPT_RA_PINFO,
 	DEVCONF_MAX
 };
 

include/linux/sysctl.h

@@ -532,6 +532,7 @@ enum {
 	NET_IPV6_MAX_ADDRESSES=16,
 	NET_IPV6_FORCE_MLD_VERSION=17,
 	NET_IPV6_ACCEPT_RA_DEFRTR=18,
+	NET_IPV6_ACCEPT_RA_PINFO=19,
 	__NET_IPV6_MAX
 };
 

net/ipv6/addrconf.c

@@ -166,6 +166,7 @@ struct ipv6_devconf ipv6_devconf = {
 #endif
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
+	.accept_ra_pinfo	= 1,
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt = {
@@ -188,6 +189,7 @@ static struct ipv6_devconf ipv6_devconf_dflt = {
 #endif
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
+	.accept_ra_pinfo	= 1,
 };
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@@ -3119,6 +3121,7 @@ static void inline ipv6_store_devconf(struct ipv6_devconf *cnf,
 #endif
 	array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
 	array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
+	array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo;
 }
 
 static int inet6_fill_ifinfo(struct sk_buff *skb, struct inet6_dev *idev, 
@@ -3579,6 +3582,14 @@ static struct addrconf_sysctl_table
 			.mode		=	0644,
          		.proc_handler	=	&proc_dointvec,
 		},
+		{
+			.ctl_name	=	NET_IPV6_ACCEPT_RA_PINFO,
+			.procname	=	"accept_ra_pinfo",
+         		.data		=	&ipv6_devconf.accept_ra_pinfo,
+			.maxlen		=	sizeof(int),
+			.mode		=	0644,
+         		.proc_handler	=	&proc_dointvec,
+		},
 		{
 			.ctl_name	=	0,	/* sentinel */
 		}

net/ipv6/ndisc.c

@@ -1191,7 +1191,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 			     NEIGH_UPDATE_F_ISROUTER);
 	}
 
-	if (ndopts.nd_opts_pi) {
+	if (in6_dev->cnf.accept_ra_pinfo && ndopts.nd_opts_pi) {
 		struct nd_opt_hdr *p;
 		for (p = ndopts.nd_opts_pi;
 		     p;