[IPV6]: ROUTE: Add accept_ra_defrtr sysctl.

This controls whether we accept default router information
in RAs.

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

5 files changed, 26 insertions, 1 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 26364d06ae92..8001faa76ea2 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -717,6 +717,12 @@ accept_ra - BOOLEAN
         Functional default: enabled if local forwarding is disabled.
                             disabled if local forwarding is enabled.
 
+accept_ra_defrtr - BOOLEAN
+        Learn default router in Router Advertisement.
+
+        Functional default: enabled if accept_ra is enabled.
+                            disabled if accept_ra is disabled.
+
 accept_redirects - BOOLEAN
         Accept Redirects.
 
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 9c8f4c9ed429..c5131a02869a 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -145,6 +145,7 @@ struct ipv6_devconf {
         __s32           max_desync_factor;
 #endif
         __s32           max_addresses;
+        __s32           accept_ra_defrtr;
         void            *sysctl;
 };
 
@@ -167,6 +168,7 @@ enum {
         DEVCONF_MAX_DESYNC_FACTOR,
         DEVCONF_MAX_ADDRESSES,
         DEVCONF_FORCE_MLD_VERSION,
+        DEVCONF_ACCEPT_RA_DEFRTR,
         DEVCONF_MAX
 };
 
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index bac61db26456..0f494137d037 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -531,6 +531,7 @@ enum {
         NET_IPV6_MAX_DESYNC_FACTOR=15,
         NET_IPV6_MAX_ADDRESSES=16,
         NET_IPV6_FORCE_MLD_VERSION=17,
+        NET_IPV6_ACCEPT_RA_DEFRTR=18,
         __NET_IPV6_MAX
 };
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 8a8895ef09a7..fbcdcc6ba93b 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -165,6 +165,7 @@ struct ipv6_devconf ipv6_devconf = {
         .max_desync_factor      = MAX_DESYNC_FACTOR,
 #endif
         .max_addresses          = IPV6_MAX_ADDRESSES,
+        .accept_ra_defrtr       = 1,
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt = {
@@ -186,6 +187,7 @@ static struct ipv6_devconf ipv6_devconf_dflt = {
         .max_desync_factor      = MAX_DESYNC_FACTOR,
 #endif
         .max_addresses          = IPV6_MAX_ADDRESSES,
+        .accept_ra_defrtr       = 1,
 };
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@@ -3116,6 +3118,7 @@ static void inline ipv6_store_devconf(struct ipv6_devconf *cnf,
         array[DEVCONF_MAX_DESYNC_FACTOR] = cnf->max_desync_factor;
 #endif
         array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
+        array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
 }
 
 static int inet6_fill_ifinfo(struct sk_buff *skb, struct inet6_dev *idev, 
@@ -3569,6 +3572,14 @@ static struct addrconf_sysctl_table
                         .proc_handler   =       &proc_dointvec,
                 },
                 {
+                        .ctl_name       =       NET_IPV6_ACCEPT_RA_DEFRTR,
+                        .procname       =       "accept_ra_defrtr",
+                        .data           =       &ipv6_devconf.accept_ra_defrtr,
+                        .maxlen         =       sizeof(int),
+                        .mode           =       0644,
+                        .proc_handler   =       &proc_dointvec,
+                },
+                {
                         .ctl_name       =       0,      /* sentinel */
                 }
         },
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index cb8856b1d951..e17116796059 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1019,7 +1019,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
         struct ra_msg *ra_msg = (struct ra_msg *) skb->h.raw;
         struct neighbour *neigh = NULL;
         struct inet6_dev *in6_dev;
-        struct rt6_info *rt;
+        struct rt6_info *rt = NULL;
         int lifetime;
         struct ndisc_options ndopts;
         int optlen;
@@ -1081,6 +1081,9 @@ static void ndisc_router_discovery(struct sk_buff *skb)
                                 (ra_msg->icmph.icmp6_addrconf_other ?
                                         IF_RA_OTHERCONF : 0);
 
+        if (!in6_dev->cnf.accept_ra_defrtr)
+                goto skip_defrtr;
+
         lifetime = ntohs(ra_msg->icmph.icmp6_rt_lifetime);
 
         rt = rt6_get_dflt_router(&skb->nh.ipv6h->saddr, skb->dev);
@@ -1128,6 +1131,8 @@ static void ndisc_router_discovery(struct sk_buff *skb)
                         rt->u.dst.metrics[RTAX_HOPLIMIT-1] = ra_msg->icmph.icmp6_hop_limit;
         }
 
+skip_defrtr:
+
         /*
          *      Update Reachable Time and Retrans Timer
          */