From: Wei Wang <weiwan@google.com>
Date: Sat, 17 Jun 2017 10:42:26 -0700
Subject: net: use loopback dev when generating blackhole route
Patch-mainline: v4.13-rc1
Git-commit: 1dbe32525e26ec28d2cc17f65a90fc7b53f1f8d0
References: bsc#1061739
Existing ipv4/6_blackhole_route() code generates a blackhole route
with dst->dev pointing to the passed in dst->dev.
It is not necessary to hold reference to the passed in dst->dev
because the packets going through this route are dropped anyway.
A loopback interface is good enough so that we don't need to worry about
releasing this dst->dev when this dev is going down.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
---
net/ipv4/route.c | 2 +-
net/ipv6/route.c | 9 +++++----
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 22ba873546c3..135a18eb9b08 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2485,7 +2485,7 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or
new->input = dst_discard;
new->output = dst_discard_out;
- new->dev = ort->dst.dev;
+ new->dev = net->loopback_dev;
if (new->dev)
dev_hold(new->dev);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9b93b4a1f48e..98f44f5bad99 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1245,9 +1245,12 @@ EXPORT_SYMBOL_GPL(ip6_route_output_flags);
struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{
struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;
+ struct net_device *loopback_dev = net->loopback_dev;
struct dst_entry *new = NULL;
- rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, DST_OBSOLETE_NONE, 0);
+
+ rt = dst_alloc(&ip6_dst_blackhole_ops, loopback_dev, 1,
+ DST_OBSOLETE_NONE, 0);
if (rt) {
rt6_info_init(rt);
@@ -1257,10 +1260,8 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
new->output = dst_discard_out;
dst_copy_metrics(new, &ort->dst);
- rt->rt6i_idev = ort->rt6i_idev;
- if (rt->rt6i_idev)
- in6_dev_hold(rt->rt6i_idev);
+ rt->rt6i_idev = in6_dev_get(loopback_dev);
rt->rt6i_gateway = ort->rt6i_gateway;
rt->rt6i_flags = ort->rt6i_flags & ~RTF_PCPU;
rt->rt6i_metric = 0;
--
2.14.2