After v3.6, output routes are cached, however, the 'rt_iif' field of
struct rtable can not be shared by various traffics using SO_BINDTODEVICE.
It causes that traffic can not reach the local receiver which also uses
SO_BINDTODEVICE after another traffic creates a local route cache.
/* sender and receiver are running on same host. */
sender:
- socket(SOCK_DGRAM)
- setsockopt(SO_BINDTODEVICE, "eth0")
- connect(INADDR_ANY)
- send("message") ------>[loopback]------+
|
receiver: |
- socket(SOCK_DGRAM) |
- setsockopt(SO_BINDTODEVICE, "eth0") |
- bind(INADDR_ANY) |
- recv() <------------------------------+
/* sometimes reach, sometimes not reach!!! */
Before v3.6, above traffics always reached. It seems to be a
regression. Actually the 'dhcp_release' command relies on it.
Commit 7bd86cc282a458b66c41e3f6 ("ipv4: Cache local output routes")
originated this issue. Revert it conditionally.
Signed-off-by: Kouya Shimura <ko...@jp.fujitsu.com>
---
net/ipv4/route.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 02c6229..4b5e024 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2285,6 +2285,8 @@ struct rtable *__ip_route_output_key_hash(struct net
*net, struct flowi4 *fl4,
}
dev_out = net->loopback_dev;
fl4->flowi4_oif = dev_out->ifindex;
+ if (orig_oif)
+ res.fi = NULL;
flags |= RTCF_LOCAL;
goto make_route;
}
--
1.9.1
