net/ipv6: set expires in rt6_add_dflt_router().

Pass the duration of a lifetime (in seconds) to the function
rt6_add_dflt_router() so that it can properly set the expiration time.

The function ndisc_router_discovery() is the only one that calls
rt6_add_dflt_router(), and it will later set the expiration time for the
route created by rt6_add_dflt_router(). However, there is a gap of time
between calling rt6_add_dflt_router() and setting the expiration time in
ndisc_router_discovery(). During this period, there is a possibility that a
new route may be removed from the routing table. By setting the correct
expiration time in rt6_add_dflt_router(), we can prevent this from
happening. The reason for setting RTF_EXPIRES in rt6_add_dflt_router() is
to start the Garbage Collection (GC) timer, as it only activates when a
route with RTF_EXPIRES is added to a table.

Suggested-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 28b065790261..52a51c69aa9d 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -170,7 +170,8 @@ struct fib6_info *rt6_get_dflt_router(struct net *net,
 struct fib6_info *rt6_add_dflt_router(struct net *net,
 				     const struct in6_addr *gwaddr,
 				     struct net_device *dev, unsigned int pref,
-				     u32 defrtr_usr_metric);
+				     u32 defrtr_usr_metric,
+				     int lifetime);
 
 void rt6_purge_dflt_routers(struct net *net);