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Commit 261663b0 authored by Steffen Klassert's avatar Steffen Klassert Committed by David S. Miller
Browse files

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: default avatarSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b8400f37

net/ipv4/route.c

+2 −2
Original line number Diff line number Diff line
@@ -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;