Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]

Hubert Kario <hkario@redhat.com> Thu, 02 June 2016 15:32 UTC

Return-Path: <hkario@redhat.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2080812D778 for <tls@ietfa.amsl.com>; Thu, 2 Jun 2016 08:32:59 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8.348
X-Spam-Level:
X-Spam-Status: No, score=-8.348 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RP_MATCHES_RCVD=-1.426, SPF_HELO_PASS=-0.001, SPF_PASS=-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 zOZPC88KGE2l for <tls@ietfa.amsl.com>; Thu, 2 Jun 2016 08:32:57 -0700 (PDT)
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 3C9CA12D76E for <tls@ietf.org>; Thu, 2 Jun 2016 08:32:57 -0700 (PDT)
Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E8840C00C91C; Thu, 2 Jun 2016 15:32:56 +0000 (UTC)
Received: from pintsize.usersys.redhat.com (dhcp-0-138.brq.redhat.com [10.34.0.138]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u52FWt3c021910 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 2 Jun 2016 11:32:56 -0400
From: Hubert Kario <hkario@redhat.com>
To: David Benjamin <davidben@chromium.org>
Date: Thu, 02 Jun 2016 17:32:55 +0200
Message-ID: <1572975.CxeTyXB7rM@pintsize.usersys.redhat.com>
User-Agent: KMail/4.14.10 (Linux/4.4.10-200.fc22.x86_64; KDE/4.14.17; x86_64; ; )
In-Reply-To: <CAF8qwaA5_A0c9yhpjtReM-HRXLmy9y_2+8E9ey0QCgL4-Ks1TA@mail.gmail.com>
References: <CAF8qwaDuGyHOu_4kpWN+c+vJKXyERPJu-2xR+nu=sPzG5vZ+ag@mail.gmail.com> <CAF8qwaASpH3Fapo61TDBuF35++GyMbZa4c-9Uy-JZ8CKywpAFw@mail.gmail.com> <CAF8qwaA5_A0c9yhpjtReM-HRXLmy9y_2+8E9ey0QCgL4-Ks1TA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="nextPart2139975.7phPDyiLET"; micalg="pgp-sha512"; protocol="application/pgp-signature"
X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 02 Jun 2016 15:32:57 +0000 (UTC)
Archived-At: <http://mailarchive.ietf.org/arch/msg/tls/D1bPtFaTu9GeNupzInsxbNdqtuo>
Cc: tls@ietf.org
Subject: Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: "This is the mailing list for the Transport Layer Security working group of the IETF." <tls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tls>, <mailto:tls-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tls/>
List-Post: <mailto:tls@ietf.org>
List-Help: <mailto:tls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tls>, <mailto:tls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 02 Jun 2016 15:32:59 -0000

On Thursday 02 June 2016 15:22:03 David Benjamin wrote:
> On Thu, Jun 2, 2016 at 11:07 AM David Benjamin <davidben@chromium.org>
> wrote:
> > On Thu, Jun 2, 2016 at 6:43 AM Hubert Kario <hkario@redhat.com> 
wrote:
> >> On Thursday 02 June 2016 11:39:20 Yoav Nir wrote:
> >> > > On 2 Jun 2016, at 10:31 AM, Nikos Mavrogiannopoulos
> >> > > <nmav@redhat.com> wrote:>
> >> > > 
> >> > > On Wed, 2016-06-01 at 15:43 -0700, Eric Rescorla wrote:
> >> > >> 2% is actually pretty good, but I agree that we're going to
> >> > >> need
> >> > >> fallback.
> >> > > 
> >> > > Please not. Lets let these fallbacks die. Not every client is a
> >> > > browser. TLS 1.3 must be a protocol which doesn't require hacks
> >> > > to
> >> > > operate. CBC was removed, lets do the same for insecure
> >> > > fallbacks.
> >> > 
> >> > Not every client is a browser, but some are. So what does the
> >> > browser
> >> > do when a server resets the connection after seeing the
> >> > ClientHello?
> >> > 
> >> > Blank screen with a failure message?
> >> 
> >> fallback to check if the connection failure is caused by TLSv1.3,
> >> and if it is, display error message and put the blame squarely on
> >> the server
> (We already do that, by the way. That's exactly what
> ERR_SSL_FALLBACK_BEYOND_MINIMUM_VERSION in Chrome is.)

the rest of the information on such error page definitely doesn't give 
that impression

Correct me if I'm wrong, but isn't the full text on it:


"""
The web page at https://example.com might be temporarily down or it may 
have moved permanently to a new web address.

Error code: ERR_SSL_FALLBACK_BEYOND_MINIMUM_VERSION
"""

-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic