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Date: Tue, 24 Oct 2023 17:20:22 +0200
From: Florian Westphal <fw@strlen.de>
To: Antony Antony <antony.antony@secunet.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
	Florian Westphal <fw@strlen.de>,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Andreas Gruenbacher <agruenba@redhat.com>, devel@linux-ipsec.org,
	netdev@vger.kernel.org
Subject: Re: [RFC PATCH ipsec-next] udpencap: Remove Obsolete
 UDP_ENCAP_ESPINUDP_NON_IKE Support
Message-ID: <20231024152022.GC29201@breakpoint.cc>
References: <b604dc470c708e1e70c954f1513e4b461531e7cc.1698136108.git.antony.antony@secunet.com>
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User-Agent: Mutt/1.10.1 (2018-07-13)

Antony Antony <antony.antony@secunet.com> wrote:
> The UDP_ENCAP_ESPINUDP_NON_IKE mode, introduced into the Linux kernel
> in 2004 [2], has remained inactive and obsolete for an extended period.
> 
> This mode was originally defined in an early version of an IETF draft
> [1] from 2001. By the time it was integrated into the kernel in 2004 [2],
> it had already been replaced by UDP_ENCAP_ESPINUDP [3] in later
> versions of draft-ietf-ipsec-udp-encaps, particularly in version 06.
> 
> Over time, UDP_ENCAP_ESPINUDP_NON_IKE has lost its relevance, with no
> known use cases.
> 
> With this commit, we remove support for UDP_ENCAP_ESPINUDP_NON_IKE,
> simplifying the code base and eliminating unnecessary complexity.
> 
> References:
> [1] https://datatracker.ietf.org/doc/html/draft-ietf-ipsec-udp-encaps-00.txt
> 
> [2] Commit that added UDP_ENCAP_ESPINUDP_NON_IKE to the Linux historic
>     repository.
> 
>     Author: Andreas Gruenbacher <agruen@suse.de>
>     Date: Fri Apr 9 01:47:47 2004 -0700
> 
>    [IPSEC]: Support draft-ietf-ipsec-udp-encaps-00/01, some ipec impls need it.
> 
> [3] Commit that added UDP_ENCAP_ESPINUDP to the Linux historic
>     repository.
> 
>     Author: Derek Atkins <derek@ihtfp.com>
>     Date: Wed Apr 2 13:21:02 2003 -0800
> 
>     [IPSEC]: Implement UDP Encapsulation framework.
> 
> Should I leave the '#define UDP_ENCAP_ESPINUDP_NON_IKE' in the uapi/linux/udp.h?
> since it is a chnage to ABI?

Yes, but you can add e.g. append "(obsolete)" or "(not supported
anymore)" or something like that to the trailing comment.

And you could wrap it in "#ifndef __KERNEL__" to have build breakage
if anytning in the kernel tries to make use of it.

Patch LGTM.