From 261663b0ee2ee8e3947f4c11c1a08be18cd2cea1 Mon Sep 17 00:00:00 2001
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Wed, 23 Nov 2011 02:14:50 +0000
Subject: [PATCH] ipv4: Don't use the cached pmtu informations for input routes
The pmtu informations on the inetpeer are visible for output and
input routes. On packet forwarding, we might propagate a learned
pmtu to the sender. As we update the pmtu informations of the
inetpeer on demand, the original sender of the forwarded packets
might never notice when the pmtu to that inetpeer increases.
So use the mtu of the outgoing device on packet forwarding instead
of the pmtu to the final destination.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/route.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 11d1b2080a166..fb47c8f0cd86f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1816,15 +1816,15 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
static unsigned int ipv4_mtu(const struct dst_entry *dst)
{
+ const struct rtable *rt = (const struct rtable *) dst;
unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
- if (mtu)
+ if (mtu && rt_is_output_route(rt))
return mtu;
mtu = dst->dev->mtu;
if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
- const struct rtable *rt = (const struct rtable *) dst;
if (rt->rt_gateway != rt->rt_dst && mtu > 576)
mtu = 576;
--
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