Re: [DNSOP] Second Working Group Last Call for draft-ietf-dnsop-extended-error

Wes Hardaker <wjhns1@hardakers.net> Wed, 13 November 2019 17:56 UTC

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From: Wes Hardaker <wjhns1@hardakers.net>
To: Puneet Sood <puneets@google.com>
Cc: Wes Hardaker <wjhns1@hardakers.net>, dnsop <dnsop@ietf.org>
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Date: Wed, 13 Nov 2019 09:56:20 -0800
In-Reply-To: <CA+9_gVvqqKwrkM7WYuEGGzfy+DSm3TzwmCDXA+AyyQ3c0Hr8wg@mail.gmail.com> (Puneet Sood's message of "Tue, 22 Oct 2019 21:49:14 -0400")
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Subject: Re: [DNSOP] Second Working Group Last Call for draft-ietf-dnsop-extended-error
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Puneet Sood <puneets@google.com>; writes:

> Independent of the decision on EDE forwarding and caching, the I-D
> needs to have some guidance for it [truncation]. The EXTRA-TEXT field
> may be obtained from configuration and it is possible that the
> resulting DNS message will exceed UDP message size limit in the
> request.

I added this text to the next version:

      <t>When the response grows beyond the requestor's UDP payload
      size <xref target="RFC6891" />, servers SHOULD truncate messages
      by dropping EDE options before dropping other data from
      packets.  Implementations SHOULD set the truncation bit when
      dropping EDE options.</t>

(and we'll have a forwarding discussion in Singapore)

> > * 14.5.0.4 NOCHANGE 5. Security Considerations
> >
> >   Para 2: "This information is unauthenticated information, and an
> >      attacker (e.g a MITM or malicious recursive server) could insert an
> >      extended error response into already untrusted data ..."  Comment:
> >      Agree with some other comments that this is not relevant since no
> >      action is expected to be taken based on EDEs.  Comment: There are
> >      ideas in the thread to have links to info in the EXTRA-TEXT and
> >      possibly display it to users. I guess the usual warnings to not
> >      click on potentially unsafe links apply.
> >
> >   + Yeah, it really would be remiss to leave out that point.  There may
> >     be nothing we can do, but the whole point of a security
> >     consideration is to properly disclose any known threats/issues.
>
> I do not see text mentioning this.

I think we're miscommunicating.  Can you propose concrete text changes?
-- 
Wes Hardaker
USC/ISI