Re: [DNSOP] Fwd: New Version Notification - draft-ietf-dnsop-svcb-https-06.txt

Feedback on SVCB draft 06 as requested.

On Mon, 28 Jun 2021 at 02:39, Tim Wicinski <tjw.ietf@gmail.com> wrote:
>8
>
> The chairs would like the WG to review these changes, and give us some feedback.

6.1.  "alpn" and "no-default-alpn"

   The presentation "value" SHALL be a comma-separated list
   (Appendix A.1) of one or more "alpn-id"s.  Zone file implementations
   MAY disallow the "," and "\" characters instead of implementing the
   "value-list" escaping procedure, relying on the opaque key format
   (e.g. "key1=\002h2") in the event that these characters are needed.

If implementations MAY ignore the escape mechanism Appendix A.1 completely,
there is little incentive to do otherwise.

However, implementations that do not exercise that option expose themselves
to a litany of potential security weaknesses:

These range from argument strings which produce corrupt content:

   example.com.   SVCB   1 example.com. ipv6hint="2001:db8:5c:5c5c::1"

not ok 29 - SVCB ipv6hint shrinkage
#   Failed test 'SVCB ipv6hint shrinkage'
#   at test.pl line 149.
#          got: 'example.com.    IN    SVCB    ( \# 33 0001
076578616d706c6503636f6d00     ; example.com.
#     0006 000e 20010db8005c0000000000000001 )'
#     expected: 'example.com.    IN    SVCB    ( \# 35 0001
076578616d706c6503636f6d00     ; example.com.
#     0006 0010 20010db8005c5c5c0000000000000001 )'

to crafted RRs which silently subvert the parsing process in undesirable ways:

   example.com.   SVCB   1 example.com.
ipv4hint="92.48.55.48,92.48.56.53,92.48.54.54,92.48.56.50"

not ok 30 - SVCB ipv4hint subversion
#   Failed test 'SVCB ipv4hint subversion'
#   at test.pl line 149.
#          got: 'example.com.    IN    SVCB    ( \# 23 0001
076578616d706c6503636f6d00     ; example.com.
#     0004 0004 46554252 )'
#     expected: 'example.com.    IN    SVCB    ( \# 35 0001
076578616d706c6503636f6d00     ; example.com.
#     0004 0010 5c3037305c3038355c3036365c303832 )'

D.3.  Failure cases

The following additional test vectors are listed below the
corresponding requirement.

 [9, para 1]
 In presentation format, the value is a [SINGLE] ECHConfigList encoded
in Base64.

  example.com.  SVCB  1 foo.example.com. ech            ; missing argument
  example.com.  SVCB  1 foo.example.com. ech=b25l,dHdv  ; multiple arguments

 [6.2, para 2]
 The presentation "value" of the SvcParamValue is a [SINGLE] decimal
integer between 0 and 65535 in ASCII.

 Note: Character set cannot be specified here; it is whatever the
platform or zone file uses (EBCDIC for example).

  example.com.  SVCB  1 foo.example.com. port=1234,4678 ; multiple arguments

 [6.1, para 6]
 When "no-default-alpn" is specified in an RR, "alpn" must also be
specified in order for the RR to be "self-consistent" (Section 2.4.3).

  example.com.  SVCB  1 foo.example.com. (
                      no-default-alpn                   ; without expected alpn
                      )

D.2.  Service form

The test vector for unsorted SvcParams would be better expressed using
numerical keys and disentangled from extraneous clutter.

  example.com.  SVCB  1 foo.example.org. (              ; unsorted SvcParam keys
                      key23609 key23600 mandatory=key23609,key23600
                      )

--rwf

>
> ---------- Forwarded message ---------
> From: <internet-drafts@ietf.org>
> Date: Wed, Jun 16, 2021 at 10:29 AM
> Subject: New Version Notification - draft-ietf-dnsop-svcb-https-06.txt
> To: Tim Wicinski <tjw.ietf@gmail.com>
>
>
>
> A new version (-06) has been submitted for draft-ietf-dnsop-svcb-https:
> https://www.ietf.org/archive/id/draft-ietf-dnsop-svcb-https-06.txt
> https://www.ietf.org/archive/id/draft-ietf-dnsop-svcb-https-06.html
>
>
> The IETF datatracker page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-dnsop-svcb-https/
>
> Diff from previous version:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-dnsop-svcb-https-06
>
> IETF Secretariat.
>
>
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