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authorStephen Suryaputra Lin <stephen.suryaputra.lin@gmail.com>2016-11-10 19:16:15 +0300
committerDavid S. Miller <davem@davemloft.net>2016-11-13 20:24:44 +0300
commit969447f226b451c453ddc83cac6144eaeac6f2e3 (patch)
tree2ea71d6490d1789212d6893d9b663480fcb052da /net/ipv4/route.c
parentca0a75316dc62af92943761b1cc049e15c92eb09 (diff)
downloadlinux-969447f226b451c453ddc83cac6144eaeac6f2e3.tar.xz
ipv4: use new_gw for redirect neigh lookup
In v2.6, ip_rt_redirect() calls arp_bind_neighbour() which returns 0 and then the state of the neigh for the new_gw is checked. If the state isn't valid then the redirected route is deleted. This behavior is maintained up to v3.5.7 by check_peer_redirect() because rt->rt_gateway is assigned to peer->redirect_learned.a4 before calling ipv4_neigh_lookup(). After commit 5943634fc559 ("ipv4: Maintain redirect and PMTU info in struct rtable again."), ipv4_neigh_lookup() is performed without the rt_gateway assigned to the new_gw. In the case when rt_gateway (old_gw) isn't zero, the function uses it as the key. The neigh is most likely valid since the old_gw is the one that sends the ICMP redirect message. Then the new_gw is assigned to fib_nh_exception. The problem is: the new_gw ARP may never gets resolved and the traffic is blackholed. So, use the new_gw for neigh lookup. Changes from v1: - use __ipv4_neigh_lookup instead (per Eric Dumazet). Fixes: 5943634fc559 ("ipv4: Maintain redirect and PMTU info in struct rtable again.") Signed-off-by: Stephen Suryaputra Lin <ssurya@ieee.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/route.c')
-rw-r--r--net/ipv4/route.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 62d4d90c1389..2a57566e6e91 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -753,7 +753,9 @@ static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flow
goto reject_redirect;
}
- n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
+ n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
+ if (!n)
+ n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
if (!IS_ERR(n)) {
if (!(n->nud_state & NUD_VALID)) {
neigh_event_send(n, NULL);