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, 3 insertions, 1 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 63b4c6056582..98abba8f15cd 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4355,7 +4355,8 @@ 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)
 {
 	struct fib6_config cfg = {
 		.fc_table	= l3mdev_fib_table(dev) ? : RT6_TABLE_DFLT,
@@ -4368,6 +4369,7 @@ struct fib6_info *rt6_add_dflt_router(struct net *net,
 		.fc_nlinfo.portid = 0,
 		.fc_nlinfo.nlh = NULL,
 		.fc_nlinfo.nl_net = net,
+		.fc_expires = jiffies_to_clock_t(lifetime * HZ),
 	};
 
 	cfg.fc_gateway = *gwaddr;