From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yves-Alexis Perez <corsac@debian.org>
Subject: Re: Regression for ip6-in-ip4 IPsec tunnel in 4.14.16
Date: Wed, 07 Feb 2018 18:05:39 +0100
Message-ID: <1518023139.2100.7.camel@debian.org>
References: <1518021487.2100.2.camel@debian.org>
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Cc: "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, debian-kernel@lists.debian.org,
        Tobias Brunner <tobias@strongswan.org>
To: Mike Maloney <maloney@google.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1518021487.2100.2.camel@debian.org>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org


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On Wed, 2018-02-07 at 17:38 +0100, Yves-Alexis Perez wrote:
> Starting with 4.14.16, IPv6 traffic is broken. When trying a simple ping
> to an IPv6 address I get:
>=20
> ping: sendmsg: Invalid argument

I forgot an important bit of information: due to the way routers usually br=
oke
path MTU discovery by filtering ICMP, I'm lowering the MTU to 1280 (so exac=
tly
  IPV6_MIN_MTU) when using IPsec.

The MTU is configured by the IKE daemon (strongSwan, thus adding Tobias to
CC:) in routing table 220:

default via 192.168.28.254 dev eth0 proto static src 192.168.0.129 mtu 1280=
 advmss 1320

I'll try to printk the mtu before returning EINVAL to see why it's lower th=
an
1280, but maybe the IP encapsulation is not correctly handled?

Regards,
--=20
Yves-Alexis
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