Re: [TLS] TLS renegotiation issue
Nicolas Williams <Nicolas.Williams@sun.com> Thu, 05 November 2009 20:32 UTC
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Date: Thu, 05 Nov 2009 14:21:31 -0600
From: Nicolas Williams <Nicolas.Williams@sun.com>
To: Eric Rescorla <ekr@rtfm.com>
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Cc: "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] TLS renegotiation issue
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On Thu, Nov 05, 2009 at 11:09:51AM -0800, Eric Rescorla wrote: > On Thu, Nov 5, 2009 at 10:46 AM, Nicolas Williams > <Nicolas.Williams@sun.com> wrote: > > On Thu, Nov 05, 2009 at 10:16:11AM -0800, Eric Rescorla wrote: > >> I now have a draft extension up at: > >> > >> https://svn.resiprocate.org/rep/ietf-drafts/ekr/draft-rescorla-tls-renegotiate.txt > >> https://svn.resiprocate.org/rep/ietf-drafts/ekr/draft-rescorla-tls-renegotiate.xml > > > > Initial comments based on a brief skim: > > > > - Please add a normative reference to RFC5056. > > There's no need for a normative reference here. This mechanism is > self-contained. > I'd be happy to add an informative reference. That's also true about draft-altman-tls-channel-bindings then, but you have a normative reference to it. I'm happy with an informative reference. > > - There's no real need for the ServerHello to include both of the > > Finished messages from the outer TLS connection. (I think there's no > > real need for the ServerHello to include either of them, actually, > > but I've not thought enough about that.) But it's OK as is, of > > course. > > The general consensus was that it was harmless and might potentially > avoid some reflection logic errors. If the server sends anything other than a mere acknowledgement, it should send its Finished message from the outer connection -- the client can then check that to see that the server really does understand this -- and the doc should say that the client must check this (but I think it does say this). The server sending the client's Finished message back is superfluous, but I agree that it's harmless. > > - You call for each TLS handshake to bind to the one immediately > > outside it. > > > > Would it be better to bind to the outer-most one instead? > > > > (In practice there's probably never more than one outer and one inner > > handshake, right?) > > Why do you think this is an improvement. Either way the binding would ultimately be to the outer-most connection, therefore this way there's less state to track. A minor point, I agree. > > - There is a way for clients to protect themselves even when servers > > don't implement this extension: > > > > a) clients MUST NOT ever send any application-level messages without > > TLS protection if they are willing to negotiate a TLS connection > > after sending any application-level messages, > > > > _and_, > > > > b) if a server requests re-negotiation then the client MUST ensure > > that the outer and inner TLS connection handshakes used a server > > certificate, and, specifically, the _same_ server certificate, > > otherwise the client MUST abort without ever completing the > > second/inner handshake. > > This isn't enough. If you look at the diagram you can see that the > client never experiences a renegotiation. That's one diagram. There's other cases, but even in the case you described, if the client never experiences a re-negotiation then it will not have authenticated itself, or, if it has authenticated itself then it will/should also have authenticated the server to the client, in which case the MITM can't be. As a result the MITM gets nothing. (My rules cover the case where a client would send a request unprotected, then negotiates TLS when the server requires authentication -- my rules forbid that.) > > - Might as well update RFC5246 to indicate that the Finished messages > > for any connection MUST be exported to applications. Better get this > > done now. > > This sort of interface issue seems out of scope for the TLS spec. Let me re-phrase: the finished messages should be added to SecurityParameters (Martin evidently takes that to be something should be exported to apps; I don't entirely agree with Martin on that point). Nico --
- [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Florian Weimer
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Florian Weimer
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- [TLS] TLS or HTTP issue? (was: TLS renegotiation … Nikos Mavrogiannopoulos
- Re: [TLS] TLS renegotiation issue Yngve N. Pettersen (Developer Opera Software ASA)
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Cullen Jennings
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Michael Gray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Florian Weimer
- Re: [TLS] TLS or HTTP issue? Bruno Harbulot
- Re: [TLS] TLS renegotiation issue Blumenthal, Uri - 0662 - MITLL
- Re: [TLS] TLS or HTTP issue? Peter Saint-Andre
- Re: [TLS] TLS or HTTP issue? Martin Rex
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nicolas Williams
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nathaniel W Filardo
- Re: [TLS] TLS or HTTP issue? Marsh Ray
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nicolas Williams
- [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Michael D'Errico
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Robert Relyea
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Michael D'Errico
- Re: [TLS] TLS or HTTP issue? Dean Anderson
- Re: [TLS] TLS renegotiation issue David Harrington
- [TLS] To API or not (Re: TLS renegotiation issue) Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Marsh Ray
- [TLS] Simple way to drop re-negotiation in HTTP (… Nicolas Williams
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] Simple way to drop re-negotiation in HT… Marsh Ray
- Re: [TLS] TLS or HTTP issue? Nikos Mavrogiannopoulos
- Re: [TLS] TLS or HTTP issue? Marsh Ray
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS or HTTP issue? Michael D'Errico
- Re: [TLS] Test Server (was TLS renegotiation issu… Michael D'Errico
- Re: [TLS] Test Server (was TLS renegotiation issu… Michael D'Errico
- Re: [TLS] TLS renegotiation issue Nagendra Modadugu
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS or HTTP issue? Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Florian Weimer
- Re: [TLS] Simple way to drop re-negotiation in HT… Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Chris Newman
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Chris Newman
- Re: [TLS] TLS renegotiation issue Bodo Moeller
- Re: [TLS] TLS or HTTP issue? Nikos Mavrogiannopoulos
- [TLS] Comments on draft-rescorla-tls-renegotiate Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Martin Rex
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nelson B Bolyard
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Bodo Moeller