From f4ef85bbda96324785097356336bc79cdd37db0a Mon Sep 17 00:00:00 2001
From: Eric Dumazet
Date: Thu, 4 Oct 2012 01:25:26 +0000
Subject: ipv4: add a fib_type to fib_info
commit d2d68ba9fe8 (ipv4: Cache input routes in fib_info nexthops.)
introduced a regression for forwarding.
This was hard to reproduce but the symptom was that packets were
delivered to local host instead of being forwarded.
David suggested to add fib_type to fib_info so that we dont
inadvertently share same fib_info for different purposes.
With help from Julian Anastasov who provided very helpful
hints, reproduced here :
Can it be a problem related to fib_info reuse
from different routes. For example, when local IP address
is created for subnet we have:
broadcast 192.168.0.255 dev DEV proto kernel scope link src
192.168.0.1
192.168.0.0/24 dev DEV proto kernel scope link src 192.168.0.1
local 192.168.0.1 dev DEV proto kernel scope host src 192.168.0.1
The "dev DEV proto kernel scope link src 192.168.0.1" is
a reused fib_info structure where we put cached routes.
The result can be same fib_info for 192.168.0.255 and
192.168.0.0/24. RTN_BROADCAST is cached only for input
routes. Incoming broadcast to 192.168.0.255 can be cached
and can cause problems for traffic forwarded to 192.168.0.0/24.
So, this patch should solve the problem because it
separates the broadcast from unicast traffic.
And the ip_route_input_slow caching will work for
local and broadcast input routes (above routes 1 and 3) just
because they differ in scope and use different fib_info.
Many thanks to Chris Clayton for his patience and help.
Reported-by: Chris Clayton
Bisected-by: Chris Clayton
Reported-by: Dave Jones
Signed-off-by: Eric Dumazet
Cc: Julian Anastasov
Tested-by: Chris Clayton
Signed-off-by: David S. Miller
---
net/ipv4/fib_semantics.c | 2 ++
1 file changed, 2 insertions(+)
(limited to 'net')
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 3509065e409a..267753060ffc 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -314,6 +314,7 @@ static struct fib_info *fib_find_info(const struct fib_info *nfi)
nfi->fib_scope == fi->fib_scope &&
nfi->fib_prefsrc == fi->fib_prefsrc &&
nfi->fib_priority == fi->fib_priority &&
+ nfi->fib_type == fi->fib_type &&
memcmp(nfi->fib_metrics, fi->fib_metrics,
sizeof(u32) * RTAX_MAX) == 0 &&
((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
@@ -833,6 +834,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
fi->fib_flags = cfg->fc_flags;
fi->fib_priority = cfg->fc_priority;
fi->fib_prefsrc = cfg->fc_prefsrc;
+ fi->fib_type = cfg->fc_type;
fi->fib_nhs = nhs;
change_nexthops(fi) {
--
cgit v1.2.3