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| author | Stephen Suryaputra Lin <stephen.suryaputra.lin@gmail.com> | 2016-11-10 19:16:15 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-11-13 20:24:44 +0300 |
| commit | 969447f226b451c453ddc83cac6144eaeac6f2e3 (patch) | |
| tree | 2ea71d6490d1789212d6893d9b663480fcb052da /net | |
| parent | ca0a75316dc62af92943761b1cc049e15c92eb09 (diff) | |
| download | linux-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')
| -rw-r--r-- | net/ipv4/route.c | 4 |
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); |