netdev - Re: [PATCH net] ip6_tunnel: Fix encapsulation layout

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Message-Id: <20181018.165535.1982091847075806302.davem@davemloft.net>
Date:   Thu, 18 Oct 2018 16:55:35 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     sbrivio@...hat.com
Cc:     tom@...bertland.com, kraig@...gle.com, pabeni@...hat.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net] ip6_tunnel: Fix encapsulation layout

From: Stefano Brivio <sbrivio@...hat.com>
Date: Thu, 18 Oct 2018 21:25:07 +0200

> Commit 058214a4d1df ("ip6_tun: Add infrastructure for doing
> encapsulation") added the ip6_tnl_encap() call in ip6_tnl_xmit(), before
> the call to ipv6_push_frag_opts() to append the IPv6 Tunnel Encapsulation
> Limit option (option 4, RFC 2473, par. 5.1) to the outer IPv6 header.
> 
> As long as the option didn't actually end up in generated packets, this
> wasn't an issue. Then commit 89a23c8b528b ("ip6_tunnel: Fix missing tunnel
> encapsulation limit option") fixed sending of this option, and the
> resulting layout, e.g. for FoU, is:
> 
> .-------------------.------------.----------.-------------------.----- - -
> | Outer IPv6 Header | UDP header | Option 4 | Inner IPv6 Header | Payload
> '-------------------'------------'----------'-------------------'----- - -
> 
> Needless to say, FoU and GUE (at least) won't work over IPv6. The option
> is appended by default, and I couldn't find a way to disable it with the
> current iproute2.
> 
> Turn this into a more reasonable:
> 
> .-------------------.----------.------------.-------------------.----- - -
> | Outer IPv6 Header | Option 4 | UDP header | Inner IPv6 Header | Payload
> '-------------------'----------'------------'-------------------'----- - -
> 
> With this, and with 84dad55951b0 ("udp6: fix encap return code for
> resubmitting"), FoU and GUE work again over IPv6.
> 
> Fixes: 058214a4d1df ("ip6_tun: Add infrastructure for doing encapsulation")
> Signed-off-by: Stefano Brivio <sbrivio@...hat.com>

This goes back to v4.7 then, I can't believe this has been broken for
so long. :-/

Applied and queued up for -stable, thanks.