[PATCH 4.15 09/23] ipv6: change route cache aging logic

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wei Wang <weiwan@google.com>


[ Upstream commit 31afeb425f7fad8bcf9561aeb0b8405479f97a98 ]

In current route cache aging logic, if a route has both RTF_EXPIRE and
RTF_GATEWAY set, the route will only be removed if the neighbor cache
has no NTF_ROUTER flag. Otherwise, even if the route has expired, it
won't get deleted.
Fix this logic to always check if the route has expired first and then
do the gateway neighbor cache check if previous check decide to not
remove the exception entry.

Fixes: 1859bac04fb6 ("ipv6: remove from fib tree aged out RTF_CACHE dst")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv6/route.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1586,12 +1586,19 @@ static void rt6_age_examine_exception(st
 	 * EXPIRES exceptions - e.g. pmtu-generated ones are pruned when
 	 * expired, independently from their aging, as per RFC 8201 section 4
 	 */
-	if (!(rt->rt6i_flags & RTF_EXPIRES) &&
-	    time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
-		RT6_TRACE("aging clone %p\n", rt);
+	if (!(rt->rt6i_flags & RTF_EXPIRES)) {
+		if (time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
+			RT6_TRACE("aging clone %p\n", rt);
+			rt6_remove_exception(bucket, rt6_ex);
+			return;
+		}
+	} else if (time_after(jiffies, rt->dst.expires)) {
+		RT6_TRACE("purging expired route %p\n", rt);
 		rt6_remove_exception(bucket, rt6_ex);
 		return;
-	} else if (rt->rt6i_flags & RTF_GATEWAY) {
+	}
+
+	if (rt->rt6i_flags & RTF_GATEWAY) {
 		struct neighbour *neigh;
 		__u8 neigh_flags = 0;
 
@@ -1606,11 +1613,8 @@ static void rt6_age_examine_exception(st
 			rt6_remove_exception(bucket, rt6_ex);
 			return;
 		}
-	} else if (__rt6_check_expired(rt)) {
-		RT6_TRACE("purging expired route %p\n", rt);
-		rt6_remove_exception(bucket, rt6_ex);
-		return;
 	}
+
 	gc_args->more++;
 }