[IPV6]: ROUTE: Add accept_ra_rtr_pref sysctl.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt

@@ -729,6 +729,12 @@ accept_ra_pinfo - BOOLEAN
 	Functional default: enabled if accept_ra is enabled.
 			    disabled if accept_ra is disabled.
 
+accept_ra_rtr_pref - BOOLEAN
+	Accept Router Preference in RA.
+
+	Functional default: enabled if accept_ra is enabled.
+			    disabled if accept_ra is disabled.
+
 accept_redirects - BOOLEAN
 	Accept Redirects.
 

include/linux/ipv6.h

@@ -147,6 +147,9 @@ struct ipv6_devconf {
 	__s32		max_addresses;
 	__s32		accept_ra_defrtr;
 	__s32		accept_ra_pinfo;
+#ifdef CONFIG_IPV6_ROUTER_PREF
+	__s32		accept_ra_rtr_pref;
+#endif
 	void		*sysctl;
 };
 
@@ -171,6 +174,7 @@ enum {
 	DEVCONF_FORCE_MLD_VERSION,
 	DEVCONF_ACCEPT_RA_DEFRTR,
 	DEVCONF_ACCEPT_RA_PINFO,
+	DEVCONF_ACCEPT_RA_RTR_PREF,
 	DEVCONF_MAX
 };
 

include/linux/sysctl.h

@@ -533,6 +533,7 @@ enum {
 	NET_IPV6_FORCE_MLD_VERSION=17,
 	NET_IPV6_ACCEPT_RA_DEFRTR=18,
 	NET_IPV6_ACCEPT_RA_PINFO=19,
+	NET_IPV6_ACCEPT_RA_RTR_PREF=20,
 	__NET_IPV6_MAX
 };
 

net/ipv6/addrconf.c

@@ -167,6 +167,9 @@ struct ipv6_devconf ipv6_devconf = {
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
 	.accept_ra_pinfo	= 1,
+#ifdef CONFIG_IPV6_ROUTER_PREF
+	.accept_ra_rtr_pref	= 1,
+#endif
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt = {
@@ -190,6 +193,9 @@ static struct ipv6_devconf ipv6_devconf_dflt = {
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
 	.accept_ra_pinfo	= 1,
+#ifdef CONFIG_IPV6_ROUTER_PREF
+	.accept_ra_rtr_pref	= 1,
+#endif
 };
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@@ -3122,6 +3128,9 @@ static void inline ipv6_store_devconf(struct ipv6_devconf *cnf,
 	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;
+#ifdef CONFIG_IPV6_ROUTER_PREF
+	array[DEVCONF_ACCEPT_RA_RTR_PREF] = cnf->accept_ra_rtr_pref;
+#endif
 }
 
 static int inet6_fill_ifinfo(struct sk_buff *skb, struct inet6_dev *idev, 
@@ -3590,6 +3599,16 @@ static struct addrconf_sysctl_table
 			.mode		=	0644,
          		.proc_handler	=	&proc_dointvec,
 		},
+#ifdef CONFIG_IPV6_ROUTER_PREF
+		{
+			.ctl_name	=	NET_IPV6_ACCEPT_RA_RTR_PREF,
+			.procname	=	"accept_ra_rtr_pref",
+			.data		=	&ipv6_devconf.accept_ra_rtr_pref,
+			.maxlen		=	sizeof(int),
+			.mode		=	0644,
+			.proc_handler	=	&proc_dointvec,
+		},
+#endif
 		{
 			.ctl_name	=	0,	/* sentinel */
 		}

net/ipv6/ndisc.c

@@ -1090,7 +1090,8 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	pref = ra_msg->icmph.icmp6_router_pref;
 	/* 10b is handled as if it were 00b (medium) */
-	if (pref == ICMPV6_ROUTER_PREF_INVALID)
+	if (pref == ICMPV6_ROUTER_PREF_INVALID ||
+	    in6_dev->cnf.accept_ra_rtr_pref)
 		pref = ICMPV6_ROUTER_PREF_MEDIUM;
 #endif