Re: [DNSOP] New Version Notification for draft-pwouters-powerbind-00.txt (fwd)

Michael Casadevall <michael@casadevall.pro> Wed, 21 March 2018 07:11 UTC

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To: Paul Wouters <paul@nohats.ca>
Cc: dnsop@ietf.org
References: <alpine.LRH.2.21.1803190813150.31565@bofh.nohats.ca> <20180319163434.GA25738@laperouse.bortzmeyer.org> <CA+nkc8CWtXOiXCVQf4iyJwBS1K4seLxsJmtZyRyz7yuCn+u8hQ@mail.gmail.com> <20180319194945.GG3322@mournblade.imrryr.org> <20180320112653.GA10054@laperouse.bortzmeyer.org> <alpine.LRH.2.21.1803200740520.29013@bofh.nohats.ca> <558f80ca-be06-1cdd-4406-14b5797cdb26@casadevall.pro> <alpine.LRH.2.21.1803200933160.30728@bofh.nohats.ca>
From: Michael Casadevall <michael@casadevall.pro>
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Date: Wed, 21 Mar 2018 03:10:54 -0400
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Subject: Re: [DNSOP] New Version Notification for draft-pwouters-powerbind-00.txt (fwd)
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Paul: Thanks for the explanation, it clears up a fair bit for me.
Replies inline.

On 03/20/2018 09:48 AM, Paul Wouters wrote:
> On Tue, 20 Mar 2018, Michael Casadevall wrote:
>
>> Without the RRtypes logged, I'm not seeing how you're supposed to be
>> able to audit them. In the case where a KSK is compromised, you could
> 
> Neither this nor certificate transparency protects against a (non-known)
> private key compromise. In the case of CA's there are multiple entities
> that can create a certificate that need to be audited. In DNSSEC, it is
> only the zone or its parents that could create a rogue TLSA record.
>

In my mind, the use case I was making was one of that of an intermediate
certificate being misused, but didn't quite make the mental leap to
equating that to the TLD/root zone. In that context, this proposal as
well as logging DS/NS changes makes considerably more sense to me than
it did before.

I still suspect there's value for full logging of all record types, but
that's a separate discussion.

>> I'm likely missing something obvious, by only logging DS/NS, it would be
>> impossible to determine if a private key is misused to serve fraudulent
>> records which in my mind is a bigger and much more likely/common threat
>> since one can simply attack a target domain and not try to compromise
>> the root.
> 
> This is similar to the TLS server private key being compromised without
> knowledge. That is not what is being protected.
> 

See above.

>> From a technical point of view, aren't there TLDs that as authoritative
>> for second level domains as well? The specification likely needs a way
>> to denote how many levels deep delegation can go. This also would be
>> true in the case of delegation_only being used at a level above both the
>> root and TLD zones.
> 
> In trying to keep this as simple as possible, the idea was to make this
> concept as simple as possible. Making a promise about "every zone cut"
> is much easier then making a promise to point to some more complicated
> policy that might change over time, and then you have to log/audit the
> changes to that policy as well.
> 
> For instance, you could have the DNSKEY flag mean "look for the
> DELEGATE RRtype policy" and in there specify exceptions for your empty
> non-terminals, but it just makes everything much harder.
> 

I can appreciate simplicity in a specification. Obviously having a
hypothetical DELEGATE RRtype would considerable more work both in design
and actual implementation/validation. I'm just slightly concerned that
it might make real world deployment more difficult.

My point is here though is it might be a relatively simple extension to
say "I may delegate X levels down" vs. a rather complex system of
delegation/termination for cases where the TLDs disallow second level
registration.

I'm not qualified enough to say definitively if that's actually a
valuable enough case to be worth extending the specification, but I did
want to highlight it for consideration.

>> At a minimum though, the one case I know off hand of a TLD being
>> authoritative for a second-level domain is that ICANN requires new gTLDs
>> are required to publish a wildcard for 90 days when they're added to the
>> root zone to help catch any name collisions.
> 
> If the software allows signing the wildcard and setting the
> delegation-only flag that would mean the wildcard must be
> treated as BOGUS, that would not be a problem. It would still
> cause problems to be found with name collisions, except now the
> name SERVFAILs instead of resolving to 127.0.0.53. Both will show
> the name collision as a problem.
> 

This likely should be noted as a operational consideration at a minimum
as it impacts how Name Collision tracking is done.

Thanks for your time,
Michael