ipv6: use rt6_get_dflt_router to get default router in rt6_route_rcv

[ Upstream commit f104a567e673f382b09542a8dc3500aa689957b4 ]

As the rfc 4191 said, the Router Preference and Lifetime values in a
::/0 Route Information Option should override the preference and lifetime
values in the Router Advertisement header. But when the kernel deals with
a ::/0 Route Information Option, the rt6_get_route_info() always return
NULL, that means that overriding will not happen, because those default
routers were added without flag RTF_ROUTEINFO in rt6_add_dflt_router().

In order to deal with that condition, we should call rt6_get_dflt_router
when the prefix length is 0.

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index bc9103d..1768238 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -592,8 +592,11 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
                prefix = &prefix_buf;
        }
 
-       rt = rt6_get_route_info(net, prefix, rinfo->prefix_len, gwaddr,
-                               dev->ifindex);
+       if (rinfo->prefix_len == 0)
+               rt = rt6_get_dflt_router(gwaddr, dev);
+       else
+               rt = rt6_get_route_info(net, prefix, rinfo->prefix_len,
+                                       gwaddr, dev->ifindex);
 
        if (rt && !lifetime) {
                ip6_del_rt(rt);