[34-longterm 202/260] net: blackhole route should always be recalculated

[Paul Gortmaker]

From: Jianzhao Wang <jianzhao.wang@xxxxxxxxx>

commit ae2688d59b5f861dc70a091d003773975d2ae7fb upstream.

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@xxxxxxxxx>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 net/ipv4/route.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index cb562fd..325b43c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2758,6 +2758,11 @@ 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)
 {
 }
@@ -2766,7 +2771,7 @@ 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),
 };
-- 
1.7.3.3

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