net: blackhole route should always be recalculated

[ Upstream commit ae2688d59b5f861dc70a091d003773975d2ae7fb ]

Blackhole routes are used when xfrm_lookup() returns -EREMOTE (error
triggered by IKE for example), hence this kind of route is always
temporary and so we should check if a better route exists for next
packets.
Bug has been introduced by commit d11a4dc18bf41719c9f0d7ed494d295dd2973b92.

Signed-off-by: Jianzhao Wang <jianzhao.wang@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 560acc677ce485cce87a0161fa709f5e50b8e56f..0189deb093d7c5335663101039124594016acc75 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2741,6 +2741,11 @@ slow_output:
 
 EXPORT_SYMBOL_GPL(__ip_route_output_key);
 
+static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
+{
+       return NULL;
+}
+
 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu)
 {
 }
@@ -2749,7 +2754,7 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
        .family                 =       AF_INET,
        .protocol               =       cpu_to_be16(ETH_P_IP),
        .destroy                =       ipv4_dst_destroy,
-       .check                  =       ipv4_dst_check,
+       .check                  =       ipv4_blackhole_dst_check,
        .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
        .entries                =       ATOMIC_INIT(0),
 };