From: Patrick McHardy <kaber@trash.net>
Date: Sun, 26 Aug 2012 17:13:55 +0000 (+0200)
Subject: ipv4: fix path MTU discovery with connection tracking
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~47^2~226^2~26
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5f2d04f1f9b52604fca6ee08a77972c0df67e082;p=pandora-kernel.git

ipv4: fix path MTU discovery with connection tracking

IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and
(in case of forwarded packets) refragments them at POST_ROUTING
independent of the IP_DF flag. Refragmentation uses the dst_mtu() of
the local route without caring about the original fragment sizes,
thereby breaking PMTUD.

This patch fixes this by keeping track of the largest received fragment
with IP_DF set and generates an ICMP fragmentation required error during
refragmentation if that size exceeds the MTU.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
---

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