dry-run DNSSEC
draft-yorgos-dnsop-dry-run-dnssec-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|---|---|---|---|
| Authors | Yorgos Thessalonikefs , Willem Toorop , Roy Arends | ||
| Last updated | 2022-03-11 (Latest revision 2022-03-04) | ||
| RFC stream | (None) | ||
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draft-yorgos-dnsop-dry-run-dnssec-00
DNSOP Working Group Y. Thessalonikefs
Internet-Draft W. Toorop
Intended status: Standards Track NLnet Labs
Expires: 5 September 2022 R. Arends
ICANN
4 March 2022
dry-run DNSSEC
draft-yorgos-dnsop-dry-run-dnssec-00
Abstract
This document describes a method called "dry-run DNSSEC" that allows
for testing DNSSEC deployments without affecting the DNS service in
case of DNSSEC errors. It accomplishes that by introducing a new DS
Type Digest Algorithm that signals to validating resolvers that dry-
run DNSSEC is used for the zone. DNSSEC errors are then reported
with DNS Error Reporting, but the bogus response is withheld.
Instead resolvers fallback from dry-run DNSSEC and provide the
response that would have been answered without the presence of a dry-
run DS. A further option is presented for clients to opt-in for dry-
run DNSSEC errors and allow for end-to-end DNSSEC testing.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 5 September 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Description . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. The dry-run DS structure . . . . . . . . . . . . . . . . 4
3.2. DNSSEC Error Reporting . . . . . . . . . . . . . . . . . 4
3.3. Parent zone records . . . . . . . . . . . . . . . . . . . 5
3.3.1. CDS and CDNSKEY Consideration . . . . . . . . . . . . 5
3.4. dry-run DS and real DS coexistence . . . . . . . . . . . 5
3.5. wet-run clients . . . . . . . . . . . . . . . . . . . . . 6
4. Implementation Notes . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. DRY-RUN DS Type Digest Algorithm . . . . . . . . . . . . 6
6.2. Wet-Run EDNS0 Option . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
9. Informative References . . . . . . . . . . . . . . . . . . . 7
Appendix A. Implementation Status . . . . . . . . . . . . . . . 8
Appendix B. Change History (to be removed before final
publication) . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
DNSSEC was introduced to provide DNS with data origin authentication
and data integrity. This introduced quite an amount of complexity
and fragility to the DNS which in turn still hinders general
adoption. When an operator decides to publish a newly signed zone
there is no way to realistically check that DNS will not break for
the zone.
This document describes a method called "dry-run DNSSEC" that gives
confidence to operators to adopt DNSSEC by introducing a new DS Type
Digest Algorithm. Resolvers that don't support the algorithm
continue to treat the delegation as insecure [RFC6840], Section 5.2.
Validating resolvers are signaled to treat the delegation as being in
an intermediate test step for DNSSEC. Valid answers yield authentic
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data (AD) responses. Therefore, clients that expect the AD flag can
already profit from the transition. Invalid answers instead of
SERVFAIL yield the response that would have been answered when no
dry-run DS would have been present in the parent. For zones that had
only dry-run DS RRs in the parent, an invalid answer yields an
insecure response. This is of course not proper data integrity but
the delegation should not be considered DNSSEC signed at this point.
Based on DNS Error Reporting [DNS-ERROR-REPORTING], invalid answers
for dry-run DNSSEC errors generate reports in order to monitor
potential DNS breakage when changing the DNSSEC configuration for a
zone. This is also the main purpose of dry-run DNSSEC.
The signed zone is publicly deployed but DNSSEC configuration errors
cannot break DNS resolution yet. DNSSEC health feedback can pinpoint
potential issues back to the operator. When the operator is
confident that the DNSSEC adoption does not introduce DNS breakage,
the real DS record can be published on the parent zone and that
concludes the actual DNSSEC deployment.
Dry-run DNSSEC can further be used on already singed zones to test
key rollovers. In this case a dry-run DS record for the future key
is used next to the current DS record which itself needs to be also
presented in the dry-run format. Validating resolvers that
understand dry-run DNSSEC first try to validate with a dry-run DS
before falling back to real DSes.
For further end-to-end DNS testing, a new EDNS0 option code is
introduced that a client can send along with a query to a validating
resolver. This signals validating resolvers that the client has
opted-in to DNSSEC errors for dry-run delegations. The resolver
still uses DNS Error Reporting [DNS-ERROR-REPORTING] for dry-run
errors but instead of the insecure answer it provides the client with
the SERVFAIL answer, same as with actual DNSSEC. These clients are
called "wet-run clients".
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
dry-run DS The DS record with the special DS type digest algorithm
that signals dry-run DNSSEC for the delegation.
real DS The actual DS record for the delegation. Replaces the dry-
run DS to complete DNSSEC deployment.
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dry-run zone A zone that is DNSSEC signed but uses a dry-run DS to
signal the use of the dry-run DNSSEC method.
wet-run client A client that has opted-in to receive the actual
DNSSEC errors from the upstream validating resolver instead of the
insecure answers.
3. Description
TODO
3.1. The dry-run DS structure
The dry-run DS record is a normal DS record with updated semantics to
allow for dry-run signaling to a validating resolver. The DS Type
Digest Algorithm value MUST be TBD (DRY-RUN). The first octet of the
DS Digest field contains the actual Type Digest Algorithm, followed
by the actual Digest:
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Tag | Algorithm | DRY-RUN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Digest Type | /
+-+-+-+-+-+-+-+-+ Digest /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Validating resolvers encountering such a DS record will know to mark
this delegation as dry-run DNSSEC and extract the actual Type Digest
Algorithm and Digest from the dry-run DS Digest field.
Validating resolvers that have no knowledge for the DRY-RUN DS Type
Digest Algorithm MUST disregard the DS record as per [RFC6840],
Section 5.2.
3.2. DNSSEC Error Reporting
The main purpose of the dry-run DNSSEC proposal is to be able to
monitor potential DNS breakage when adopting DNSSEC for a zone. The
main tool to do that is DNS Error Reporting [DNS-ERROR-REPORTING].
Operators that want to use dry-run DNSSEC SHOULD support DNSSEC Error
Reporting and have a reporting agent in place to receive the error
reports.
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Implementations that support dry-run DNSSEC MUST also support DNSSEC
Error Reporting and report any DNSSEC errors for the dry-run zone to
the designated report agent.
3.3. Parent zone records
The only change that needs to happen for dry-run DNSSEC is for the
parent to be able to publish the dry-run DS record. If the parent
accepts DS records from the child, the child needs to provide the
dry-run DS record. If the parent does not accept DS records and
generates the DS records from the DNSKEY, support for generating the
dry-run DS record, when needed, should be added to the parent if dry-
run DNSSEC is a desirable feature.
When the child zone operator wants to complete the DNSSEC deployment,
the parent needs to be notified for the real DS record.
3.3.1. CDS and CDNSKEY Consideration
CDS works as expected by providing the dry-run DS content for the CDS
record. CDNSKEY cannot work by itself; it needs to be accompanied by
the aforementioned CDS to signal dry-run DNSSEC for the delegation.
Thus, parents that rely only on CDNSKEY need to add support for
checking the accompanying CDS record for the DRY-RUN DS Type Digest
Algorithm and generating a dry-run DS record.
Operators of a dry-run child zone are advised to publish both CDS and
CDNSKEY so that both cases above are covered.
3.4. dry-run DS and real DS coexistence
TODO tldr: for example testing key rollover.
* For ease of implementation and DoS prevention validators SHOULD
pick a DS and DNSKEY pair they understand from both the dry-run
and real pool of available DSes.
* If dry-run DSes are present, the validator MUST first consider
those.
* If real DS is picked by validator, carry on.
* If dry-run DS is picked,
- If everything OK, secure.
- If something not OK, should report and fallback to real DS. No
insecure answers for this one. It guarantees that the DNSSEC
of the zone is not altered.
- If going back to real DS, the real DS is now cached and no EDER
reports for the same dry-run DS should be generated.
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3.5. wet-run clients
Wet-run clients are clients that send the EDNS0 option code TBD (Wet-
Run DNSSEC) when querying a validating resolver. These clients opt-
in to receive error responses in case of DNSSEC errors in a dry-run
zone. They allow for end-to-end DNSSEC testing in a controlled
environment.
Validating resolvers that recognise the option MUST respond with the
error that they would normally respond for a DNSSEC zone and MUST
attach the same EDNS0 option code TBD in the response to mark the
error response as coming from a dry-run zone.
Additional Extended DNS Errors can also be attached in the error
response by the validating resolver as per [RFC8914].
4. Implementation Notes
TODO tldr; validating resolvers need to keep an additional DNSSEC
status for cached records that notes the DNSSEC status for the dry-
run part. Responses can then be provided based on the Wet-Run DNSSEC
EDNS0 option.
5. Security Considerations
Dry-run DNSSEC disables one of the fundamental guarantees of DNSSEC,
data integrity. Bogus answers for expired/invalid data will become
insecure answers providing the potentially wrong information back to
the requester. This is a feature of this proposal but it also allows
forged answers by third parties to still affect the zone. This
should be treated as a warning that dry-run DNSSEC is not an end
solution but rather a temporarily intermediate test step of a zone
going secure.
Parent zones that provide signed delegations to child zones should be
aware that by using dry-run DNSSEC (e.g., testing a key roll to a
stronger algorithm key) they risk the DNSSEC status of the child
zones. If the trust chain becomes invalid between parent and child
because of dry-run DNSSEC the child zone will be treated as insecure.
6. IANA Considerations
6.1. DRY-RUN DS Type Digest Algorithm
This document defines a new entry in the "Delegation Signer (DS)
Resource Record (RR) Type Digest Algorithms" registry:
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+=======+=============+==========+=================+
| Value | Digest Type | Status | Reference |
+=======+=============+==========+=================+
| TBD | DRY-RUN | OPTIONAL | [this document] |
+-------+-------------+----------+-----------------+
Table 1
6.2. Wet-Run EDNS0 Option
This document defines a new entry in the "DNS EDNS0 Option Codes
(OPT)" registry on the "Domain Name System (DNS) Parameters" page:
+=======+================+==========+=================+
| Value | Name | Status | Reference |
+=======+================+==========+=================+
| TBD | Wet-Run DNSSEC | Optional | [this document] |
+-------+----------------+----------+-----------------+
Table 2
7. Acknowledgements
Martin Hoffmann contributed the idea of using the DS record of an
already signed zone also as a dry-run DS in order to facilitate
testing key rollovers.
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8914] Kumari, W., Hunt, E., Arends, R., Hardaker, W., and D.
Lawrence, "Extended DNS Errors", RFC 8914,
DOI 10.17487/RFC8914, October 2020,
<https://www.rfc-editor.org/info/rfc8914>.
9. Informative References
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[DNS-ERROR-REPORTING]
Arends, R. and M. Larson, "DNS Error Reporting",
<https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-
dns-error-reporting>.
[RFC6840] Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and
Implementation Notes for DNS Security (DNSSEC)", RFC 6840,
DOI 10.17487/RFC6840, February 2013,
<https://www.rfc-editor.org/info/rfc6840>.
Appendix A. Implementation Status
*Note to the RFC Editor*: please remove this entire section before
publication.
In the following implementation status descriptions, "dry-run DNSSEC"
refers to dry-run DNSSEC as described in this document.
* TODO
Appendix B. Change History (to be removed before final publication)
* draft-yorgos-dnsop-dry-run-dnssec-00
| Initial public draft.
Authors' Addresses
Yorgos Thessalonikefs
NLnet Labs
Science Park 400
1098 XH Amsterdam
Netherlands
Email: george@nlnetlabs.nl
Willem Toorop
NLnet Labs
Science Park 400
1098 XH Amsterdam
Netherlands
Email: willem@nlnetlabs.nl
Roy Arends
ICANN
Email: roy.arends@icann.org
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