I think that would make sense, yes. On Sat, Mar 30, 2024 at 10:58 AM Erik Nygren <erik+i...@nygren.org> wrote:
> Do we want a few sentences in Security Considerations that references > https://www.rfc-editor.org/rfc/rfc9460.html#section-3.1 to call this out? > > This seems like something that became less clear when we split these two > docs apart. > Most of draft-ietf-tls-svcb-ech used to be a section of what is now > rfc9460 but got split out > due to publication timelines. It may be that some non-normative > references back to rfc9460 > might help readers not miss things like this which might have been more > clear when they > were a single document. > > Erik > > > > > On Fri, Mar 29, 2024 at 11:31 PM Ted Lemon <mel...@fugue.com> wrote: > >> Yes, that fully addresses my concern. Thanks! >> >> Op vr 29 mrt 2024 om 22:54 schreef Eric Rescorla <e...@rtfm.com> >> >>> >>> Hi Ted, >>> >>> Doesn't this section of RFC 9460 address this case and say what you are >>> recommending: >>> >>> https://www.rfc-editor.org/rfc/rfc9460.html#section-3.1 >>> >>> -Ekr >>> >>> >>> >>> On Fri, Mar 29, 2024 at 6:49 PM Ted Lemon <mel...@fugue.com> wrote: >>> >>>> Okay, I think I see the disconnect, maybe. The issue I'm pointing to is >>>> that you may or may not be doing DNSSEC validation. And you may or may not >>>> be /able/ to do DNSSEC validation if the infrastructure breaks it >>>> accidentally or deliberately. >>>> >>>> The document says: "The SVCB-optional client behavior specified in >>>> (Section 3 of [SVCB]) permits clients to fall back to a direct connection >>>> if all SVCB options fail. This behavior is not suitable for ECH, because >>>> fallback would negate the privacy benefits of ECH." >>>> >>>> So it's saying that the default handling of SVCB is incorrect and would >>>> fail open, and overriding that behavior. Given that this is the case, that >>>> implies that it matters whether the data has been validated, but nowhere in >>>> the document, certainly not in Security Considerations, is any mention made >>>> of this issue. So that's what I'm pointing out. >>>> >>>> It is absolutely not the case in practice that all stub resolvers do >>>> validation. You are making a security decision about trust based on data >>>> the trustworthiness of which you've not discussed, in a situation where the >>>> implementor has meaningful choices to make with respect to validating that >>>> trustworthiness. So it's worth mentioning that if the policy is not to >>>> validate, this vulnerability exists. >>>> >>>> I'm a DNS guy, not a TLS guy, so I don't know the history of this >>>> work—I'm just making this observation about the document I was asked to >>>> review. The fact that (apparently) no DNSDIR review ever raised this issue >>>> about the other documents you mentioned is of no interest to me—I'm not >>>> reviewing those documents.Whether you take this advice is between you and >>>> the IESG. I'm not even claiming to be right—just pointing out the issue I >>>> see. >>>> >>>> On Fri, Mar 29, 2024 at 7:21 PM Rob Sayre <say...@gmail.com> wrote: >>>> >>>>> I don't think it relates to DNSSEC. You can fail at DNS (DNSSEC >>>>> failure) or you can fail during ECH (unless you want to use non-ECH, which >>>>> is not ECH, and not part of this draft). >>>>> >>>>> It makes sense to me: one can reject a request unless the requirements >>>>> embedded in the SVCB are met (the server chooses those, which can include >>>>> many aspects of the request). I don't understand why one would insert >>>>> DNSSEC here. That seems to be the whole point--it works without it. >>>>> >>>>> thanks, >>>>> Rob >>>>> >>>>> >>>>> On Fri, Mar 29, 2024 at 3:57 PM Ted Lemon <mel...@fugue.com> wrote: >>>>> >>>>>> I'm not telling you that you have to require DNSSEC. I'm saying the >>>>>> document is incomplete if you don't talk about how it relates to DNSSEC. >>>>>> I >>>>>> think EKR got the point, so maybe go with his approach? >>>>>> >>>>>> On Fri, Mar 29, 2024 at 6:27 PM Rob Sayre <say...@gmail.com> wrote: >>>>>> >>>>>>> It's a policy choice, though, right? I think ekr hinted at this >>>>>>> issue as well. >>>>>>> >>>>>>> It's that one might also view requests that reveal the SNI as >>>>>>> insecure. If that's the case, DNSSEC doesn't help. There will certainly >>>>>>> be >>>>>>> a transition period where that will be impractical for many servers. I >>>>>>> think these are separate problems, though. >>>>>>> >>>>>>> thanks, >>>>>>> Rob >>>>>>> >>>>>>> >>>>>>> On Fri, Mar 29, 2024 at 3:10 PM Ted Lemon <mel...@fugue.com> wrote: >>>>>>> >>>>>>>> It looks like if you can't get the SCVB you're going to fail >>>>>>>> insecure, so being able to use DNSSEC to prevent that for signed >>>>>>>> domains >>>>>>>> seems worthwhile. >>>>>>>> >>>>>>>> On Fri, Mar 29, 2024 at 4:41 PM Rob Sayre <say...@gmail.com> wrote: >>>>>>>> >>>>>>>>> On Fri, Mar 29, 2024 at 1:02 PM Ted Lemon via Datatracker < >>>>>>>>> nore...@ietf.org> wrote: >>>>>>>>> >>>>>>>>>> >>>>>>>>>> I don't think it's reasonable to specify the privacy properties >>>>>>>>>> of SVCB and >>>>>>>>>> /not/ talk about DNSSEC validation. >>>>>>>>>> >>>>>>>>> >>>>>>>>> Could you explain more about this part? I think DNSSEC doesn't add >>>>>>>>> much here, unless you want to accept non-ECH traffic. For example, >>>>>>>>> many of >>>>>>>>> the test servers will bounce you to some other site if you don't send >>>>>>>>> ECH >>>>>>>>> or screw it up in some way (speaking as someone who has screwed it up >>>>>>>>> many >>>>>>>>> times...). >>>>>>>>> >>>>>>>>> I think there might be a DoS attack here, where someone messes >>>>>>>>> with the response, but they can also turn off the DNSSEC bit unless >>>>>>>>> it's >>>>>>>>> DoT/DoH/DoQ etc. So, if using those, it's just the trustworthiness of >>>>>>>>> the >>>>>>>>> DNS server itself, right? Sorry if I'm missing something. >>>>>>>>> >>>>>>>>> thanks, >>>>>>>>> Rob >>>>>>>>> >>>>>>>>> _______________________________________________ >>>> TLS mailing list >>>> TLS@ietf.org >>>> https://www.ietf.org/mailman/listinfo/tls >>>> >>>
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