Re: [dns-privacy] [Ext] Re: ADoT requirements for authentication?
Ben Schwartz <bemasc@google.com> Tue, 29 October 2019 20:58 UTC
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From: Ben Schwartz <bemasc@google.com>
Date: Tue, 29 Oct 2019 16:58:38 -0400
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To: Ted Hardie <ted.ietf@gmail.com>
Cc: Paul Hoffman <paul.hoffman@icann.org>, "dns-privacy@ietf.org" <dns-privacy@ietf.org>
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Subject: Re: [dns-privacy] [Ext] Re: ADoT requirements for authentication?
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On Tue, Oct 29, 2019 at 3:07 PM Ted Hardie <ted.ietf@gmail.com> wrote: > On Tue, Oct 29, 2019 at 9:54 AM Ben Schwartz <bemasc@google.com> wrote: > >> FWIW, my expectation has been that ADoT would use TLSA-like >> authentication, with no trust anchors other than DNSSEC (and nothing >> resembling the WebPKI). >> >> Which certificate usage are you thinking of, in RFC 6698 terms? > I'm not very familiar with these terms, but I think I mean usage 2: "trust anchor assertion". Generally, I think TLSA-like authentication rooted in DNSSEC validation is > fine. But I remain pretty much of the opinion that if you get a > certificate via that method that is "wrong" for values of wrong like > "presented the wrong IP address or name in the cert" or "fails DNSSEC > validation" then you should do more than log the error. > I agree: validation failure should generally be fatal. (I expect we'll need fallback behavior for some scenarios, but not validation failures.) I also would like to point out that there are cases where you might have an > authoritative server responding to recursive resolvers where there is a > root of trust between them but where DNSSEC may not be validated: split > DNS. Imagine for a moment that enterprise.example has a hierarchy that > includes FQDNs like hostname.campus.internal.enterprise.example . Each > campus has its own recursive resolver, but they all talk to nameservers > like ns.internal.enterprise.example. In cases like those, the desire of > the enterprise to not show its internal structures may mean that they do > not wish to use DNSSEC to secure anything in internal, but they likely have > a shared root of trust between the recursive resolvers and the > authoritative server. > This resembles the ongoing experiment <https://engineering.fb.com/security/dns-over-tls/> between Facebook and Cloudflare, where both parties have agreed to speak DoT by hardcoding the relevant parameters and special-casing the relevant authoritative servers. They didn't need an ADoT standard to make this possible, because the connection is a "closed system" based on an agreement between the two parties. In your corporate-internal scenario, the recursive and authoritative servers are even more closely tied, being operated and controlled by the same party, so a secure upgrade protocol is much less relevant than on the open internet. The admins can hardcode whatever authentication procedure they want. They can even use pre-shared keys! Leaving that aspect aside, if we suppose that enterprise.example is a signed parent zone, and internal.enterprise.example is an unsigned child zone, we can still potentially enable DNSSEC-rooted ADoT to ns.internal.enterprise.example, if we can find a way to put its TLSA data in the parent zone. I think this is worth attempting. Put another way, I think you may need to support authentication using PKI > trust anchors as well. > Assuming PKI is used to validate the nameserver's name, I'm not sure it's sufficient, because this name is potentially attacker-controlled. If the parent zone is unsigned, I think opportunistic privacy is likely the best we can offer. regards, > > Ted > > On Tue, Oct 29, 2019 at 12:01 PM Ted Hardie <ted.ietf@gmail.com> wrote: >> >>> Hi Paul, >>> >>> On Tue, Oct 29, 2019 at 8:27 AM Paul Hoffman <paul.hoffman@icann.org> >>> wrote: >>> >>>> On 10/29/19 8:02 AM, Ted Hardie wrote: >>>> > To be sure I understand you correctly, in the second case, the >>>> connection would be made to some IP address (e.g. NASA's 198.116.4.181). >>>> The recursive resolver logs the details of the certificate, but it >>>> continues with the connection even if the CA NASA uses for the certificate >>>> is not known to the resolver? What does it do in the face of other >>>> certificate errors like expired certificates or certificates presenting a >>>> different name? >>>> >>>> It continues. This is exactly how opportunistic encryption is defined. >>>> >>>> >>> Just to be clear, it's my experience that accepting self-signed >>> certificates from peers does not equate to accepting certificate errors. >>> The situation in which you set up a connection to n.n.n.n and get a self >>> signed certificate saying "example.com" and when you set up a >>> connection to n.n.n.n expecting "example.com" and get a cert back for >>> "accident.example" are pretty distinguishable. I would expect some >>> configurations to accept the first without issue; I find accepting the >>> second deeply odd. >>> >>> >>>> > I have to say that I'm pretty surprised by the idea that TLS in this >>>> context should behave any differently than TLS in application layer >>>> contexts, and I'm a little concerned about having configuration options for >>>> this that amount to "ignore errors of types $FOO". >>>> >>>> TLS in application layers can specify that opportunistic encryption, >>>> yes? >>>> >>>> >>> I think you are using "opportunistic encryption" to mean something >>> different from what I mean by it. What I mean by it is "use it when you >>> can, even if you don't know in advance you can". Testing for DoT before >>> using a DNS resolver on UDP 53 and using it if you find it is >>> "opportunistic encryption", for example. >>> >>> >>>> > Accepting self-signed certificates is a known configuration, so I >>>> get that, but if someone has configured roots of trust, accepting other >>>> certificates outside the roots of trust in the configuration is pretty odd >>>> practice. >>>> >>>> Do you feel that there is a requirement that all recursive resolvers >>>> use the same set of trust anchors? >>> >>> >>> No. >>> >>> >>>> If not, and if you are against the use of opportunistic encryption in >>>> this case, >>> >>> >>> See above. I don't think I'm against opportunistic encryption. I think >>> I'm against starting to exchange traffic over a TLS connection with an >>> identifiable error. There are degrees there, obviously. Some folks would >>> say an expired but correct certificate should be logged but accepted, but a >>> flat out "wrong name presented" would likely get different treatment. >>> >>> who will decide what set of trust anchors all resolvers in all >>>> jurisdictions will use? >>>> >>>> >>> Everyone will decide who they accept? That's how the WebPKI works, for >>> all its shuffling glory, and with ACME/Let's Encrypt it has gotten very >>> easy to get a certificate that will often be accepted. >>> >>> Just my two cents, >>> >>> Ted >>> >>> --Paul Hoffman >>>> _______________________________________________ >>>> dns-privacy mailing list >>>> dns-privacy@ietf.org >>>> https://www.ietf.org/mailman/listinfo/dns-privacy >>>> >>> _______________________________________________ >>> dns-privacy mailing list >>> dns-privacy@ietf.org >>> https://www.ietf.org/mailman/listinfo/dns-privacy >>> >>
- [dns-privacy] DPRIVE Interim: 10/29 Brian Haberman
- Re: [dns-privacy] DPRIVE Interim: 10/29 Allison Mankin
- Re: [dns-privacy] DPRIVE Interim: 10/29 tjw ietf
- Re: [dns-privacy] DPRIVE Interim: 10/29 Brian Haberman
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Paul Hoffman
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Brian Haberman
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Livingood, Jason
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Alexander Mayrhofer
- Re: [dns-privacy] DPRIVE Interim: 10/29 Brian Haberman
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Brian Dickson
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Rob Sayre
- Re: [dns-privacy] DPRIVE Interim: 10/29 Eric Vyncke (evyncke)
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Paul Hoffman
- [dns-privacy] ADoT requirements for authenticatio… Paul Hoffman
- Re: [dns-privacy] ADoT requirements for authentic… Ted Hardie
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Paul Hoffman
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ted Hardie
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ben Schwartz
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Paul Wouters
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ted Hardie
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ben Schwartz
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ted Hardie
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ben Schwartz
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ben Schwartz
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Christian Huitema
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Jim Reid
- [dns-privacy] DoT at the DNS root Jim Reid
- Re: [dns-privacy] DoT at the DNS root Jim Reid
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Watson Ladd
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Alexander Mayrhofer
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ralf Weber
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Paul Wouters
- Re: [dns-privacy] ADoT requirements for authentic… Tony Finch
- Re: [dns-privacy] [EXTERNAL] Re: [Ext] Re: DPRIVE… Livingood, Jason
- Re: [dns-privacy] [Ext] Re: DPRIVE Interim: 10/29 Livingood, Jason
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Livingood, Jason
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Jim Reid
- [dns-privacy] ADoT deployment at the root Jim Reid
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Jim Reid
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] ADoT deployment at the root Ted Hardie
- Re: [dns-privacy] ADoT deployment at the root Warren Kumari
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John Levine
- Re: [dns-privacy] ADoT deployment at the root John Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ben Schwartz
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Stephen Farrell
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John R Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Vladimír Čunát
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Vladimír Čunát
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Hollenbeck, Scott
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Vladimír Čunát
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Eric Rescorla
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Vladimír Čunát
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John R Levine
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Ted Hardie
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… Brian Dickson
- Re: [dns-privacy] [Ext] Re: ADoT requirements for… John R Levine
- Re: [dns-privacy] DPRIVE Interim: 10/29 Brian Haberman