Re: [tsvwg] Comments on draft-ietf-tsvwg-transport-encrypt-14

Gorry Fairhurst <gorry@erg.abdn.ac.uk> Wed, 08 April 2020 10:08 UTC

Return-Path: <gorry@erg.abdn.ac.uk>
X-Original-To: tsvwg@ietfa.amsl.com
Delivered-To: tsvwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 1B3DB3A1039 for <tsvwg@ietfa.amsl.com>; Wed, 8 Apr 2020 03:08:36 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.896
X-Spam-Level:
X-Spam-Status: No, score=-1.896 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fkHQglOHuisF for <tsvwg@ietfa.amsl.com>; Wed, 8 Apr 2020 03:08:34 -0700 (PDT)
Received: from pegasus.erg.abdn.ac.uk (pegasus.erg.abdn.ac.uk [IPv6:2001:630:42:150::2]) by ietfa.amsl.com (Postfix) with ESMTP id DC13D3A1038 for <tsvwg@ietf.org>; Wed, 8 Apr 2020 03:08:33 -0700 (PDT)
Received: from GF-MacBook-Pro.local (fgrpf.plus.com [212.159.18.54]) by pegasus.erg.abdn.ac.uk (Postfix) with ESMTPSA id 1F43B1B0012D; Wed, 8 Apr 2020 11:08:25 +0100 (BST)
To: Spencer Dawkins at IETF <spencerdawkins.ietf@gmail.com>, Tom Herbert <tom@herbertland.com>
Cc: "Black, David" <David.Black@dell.com>, Joseph Touch <touch@strayalpha.com>, tsvwg <tsvwg@ietf.org>
References: <CALx6S345Ta5LjSkZ+XmNmH8dxKnM++VRCej2iGxfdUqDc+M-Jw@mail.gmail.com> <fc94ff59-4972-3960-7c25-85f8953463f9@erg.abdn.ac.uk> <62B8E2A9-2347-44E2-8B14-DD3CD81937AB@strayalpha.com> <737cf948-065b-0702-ca15-6cc216d73bc9@erg.abdn.ac.uk> <10E067D5-0C17-400B-BA7F-3CB49C2C94B6@strayalpha.com> <CALx6S36_HGekVYSBTiP-=uDigk+nzf2Yw2AtqopPrK5Y1gozgQ@mail.gmail.com> <2856BD08-BFCD-476D-AD1E-FE1EA94C92C7@strayalpha.com> <CALx6S34vazUp+ttxqqJ2S6U_uN8oRNt-MATdGgKvbLRFz=BLsA@mail.gmail.com> <7CC3D01B-8E86-4898-BED4-A93149D13666@strayalpha.com> <MN2PR19MB404509A876B1A187755202AD83C30@MN2PR19MB4045.namprd19.prod.outlook.com> <CALx6S34B9+0OgSJnqazqK5K1BWAA-oXHPCn8C0PkQwa0O0RJng@mail.gmail.com> <a87dce81-e40a-d283-fedb-be142111cf8e@erg.abdn.ac.uk> <CAKKJt-eSvO7iif8F=NRLG2z8URkXaq8fn7crY64CoLTYpR-hFA@mail.gmail.com> <CALx6S35bi_bLieDRUbJ6YqBusnnjwokXakeY3K9m1gEDcyQ7fQ@mail.gmail.com> <CAKKJt-dt1Oc9uZuHNr9wQxbDQRGr9RR+Kj5NTdpVDKZOAO72aw@mail.gmail.com>
From: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
Message-ID: <d218265b-8e30-41d2-6d15-3e95b898f67e@erg.abdn.ac.uk>
Date: Wed, 8 Apr 2020 11:08:23 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:68.0) Gecko/20100101 Thunderbird/68.6.0
MIME-Version: 1.0
In-Reply-To: <CAKKJt-dt1Oc9uZuHNr9wQxbDQRGr9RR+Kj5NTdpVDKZOAO72aw@mail.gmail.com>
Content-Type: multipart/alternative; boundary="------------F26046BC2B3DA7F88F637BE0"
Content-Language: en-GB
Archived-At: <https://mailarchive.ietf.org/arch/msg/tsvwg/pNZOvzgQN_KSZH7aP6kEPH8kEuk>
Subject: Re: [tsvwg] Comments on draft-ietf-tsvwg-transport-encrypt-14
X-BeenThere: tsvwg@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Transport Area Working Group <tsvwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tsvwg/>
List-Post: <mailto:tsvwg@ietf.org>
List-Help: <mailto:tsvwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 08 Apr 2020 10:08:36 -0000

On 08/04/2020 02:57, Spencer Dawkins at IETF wrote:
> Hi, Tom,
>
> On Tue, Apr 7, 2020 at 6:29 PM Tom Herbert <tom@herbertland.com 
> <mailto:tom@herbertland.com>> wrote:
>
>     On Tue, Apr 7, 2020 at 3:54 PM Spencer Dawkins at IETF
>     <spencerdawkins.ietf@gmail.com
>     <mailto:spencerdawkins.ietf@gmail.com>> wrote:
>     >
>     > I'm happy to defer to Magnus on this, but ...
>     >
>     > On Tue, Apr 7, 2020 at 2:10 PM Gorry Fairhurst
>     <gorry@erg.abdn.ac.uk <mailto:gorry@erg.abdn.ac.uk>> wrote:
>     >>
>     >>
>     >> On 07/04/2020 19:11, Tom Herbert wrote:
>     >> > On Tue, Apr 7, 2020 at 9:20 AM Black, David
>     <David.Black@dell.com <mailto:David.Black@dell.com>> wrote:
>     >> >>>> Also, a corollary should be the hard requirement:
>     >> >>>> "Intermediate nodes MUST NOT ever modify transport payload”.
>     >> >>
>     >> >>
>     >> >>> As a general principle, yes - agreed. There’s always the
>     caveat that it’s always OK
>     >> >>> *with the consent of the endpoints*, e.g., if an enterprise
>     wants to set up the
>     >> >>> network that way for their users. But in the arbitrary
>     “middle” of the network, it
>     >> >>> *should* IMO always be MUST NOT.
>     >> >>
>     >> >>
>     >> >> As a general requirement, that’s fine, but it should be
>     stated somewhere other than in this draft, e.g., as this draft is
>     intended to become an Informational RFC.
>     >> >>
>     >> > David,
>     >> >
>     >> > Changing transport layer header, e.g. for traffic flow
>     optimization
>     >> > such as those devices doing receive window modulation, might
>     also be
>     >> > another use of transport header information that could be
>     included in
>     >> > section 2.1. Currently, the draft only seems to consider uses
>     based on
>     >> > passive observation of transport headers.
>     >>
>     >> Yes, that was the intention to talk about using the
>     information, not
>     >> changing the header.  WE don't discuss methods that modify the
>     transport
>     >> header, some ACK-modification methods, Window Modulation,
>     >> proxy-intercept, PEPs, etc, which can't work if you
>     authenticate the
>     >> headers.
>     >
>     >
>     > That was my understanding when I was encouraging Gorry on this
>     draft.
>     >
>     > In addition to the likelihood that the description of passive
>     observers would be considerably delayed by inclusion of
>     description of active middleboxen dorking with transport headers
>     (we did not lack for controversy on passive observers, in 2017), I
>     wasn't confident that we could come up with a taxonomy of what
>     dorkers were doing, and why they were doing it.
>     >
>     > That's probably the result of me spending time in the SIP
>     community, when we tried to describe what Session Border
>     Controllers were doing in https://tools.ietf.org/html/rfc5853,
>     while SBC vendors were adding features as quickly as their
>     engineers could type. You won't be shocked to discover that
>     vendors considered their dorking to be "secret sauce", that
>     differentiated their products from their competitors, and were not
>     lining up to tell us what they were doing.
>     >
>
>     Spencer,
>
>     That reminds me of the olden days when some dorker providers were
>     parsing HTTP and replacing ads with their own :-)
>
>
> I'm guiltier than I look about dorking with TCP and HTTP in 
> middleboxes, but let's just walk away from that  ...
>
>
>     > So, unless someone can convince the working group that
>     documenting the dorkers can be completed in finite time and space,
>     I'd discourage expanding the scope of this draft, at this time.
>     >
>
>     it might be good to clarify the draft that only uses cases of
>     transport information being observed are in scope.
>
>
> That would indeed be a clarification - I'll let the shepherd and 
> author Do The Right Thing, of course :-)
>
> Best,
>
> Spencer
>
>
>     As I said, the potential tussle happens if the transport protocol
>     designer decides to make some transport header information visible and
>     doesn't consider that the network may then modify the information-- I
>     believe this is prevented in QUIC since the plaintext parts of the
>     QUIC header are authenticated, but that might not be the case for
>     other transport protocols.
>
>     Tom
>
>     > And that's not in any way intended to say that documenting the
>     dorkers would be a bad thing, if the working group thought it was
>     possible.
>     >
>     > Best,
>     >
>     > Spencer
>
I see more now. Thanks Tom for raising this threda up, I will take a 
look at the document - I see that since we added examples in the first 
WGLC, there are some places where the language could mislead. I'll seek 
to repair those in the next rev.

Gorry