Resource Public Key Infrastructure (RPKI) Repository Requirements
draft-ietf-sidrops-prefer-rrdp-00
Network Working Group T. Bruijnzeels
Internet-Draft NLnet Labs
Updates: 6841, 8182 (if approved) R. Bush
Intended status: Standards TrackInternet Initiative Japan & Arrcus, Inc.
Expires: August 26, 2021 G. Michaelson
APNIC
February 22, 2021
Resource Public Key Infrastructure (RPKI) Repository Requirements
draft-ietf-sidrops-prefer-rrdp-00
Abstract
This document formulates a plan of a phased transition to a state
where RPKI repositories and Relying Party software performing RPKI
Validation will use the RPKI Repository Delta Protocol (RRDP)
[RFC8182] as the only mandatory to implement access protocol.
The first objective is to make RRDP the preferred access protocol,
and require rsync as a fallback option only. This will greatly
reduce the operational burden and concerns for RPKI repository
operators.
In phase 0, today's deployment, RRDP is supported by most, but not
all Repositories, and most but not all RP software.
In the proposed phase 1 RRDP will become mandatory to implement for
Repositories, in addition to rsync. This phase can start as soon as
this document is published.
Once the proposed updates are implemented by all Repositories phase 2
will start. In this phase RRDP will become mandatory to implement
for all RP software, and rsync will be required as a fallback option
only.
It should be noted that although this document currently includes
descriptions and updates to RFCs for each of these phases, we may
find that it will be beneficial to have one or more separate
documents for these phases, so that it might be more clear to all
when the updates to RFCs take effect.
Furthermore, this document currently includes an early discussion of
a future objective, which would be to change the RPKI standards such
that names in RPKI objects are no longer tightly coupled to rsync.
By using transport independent names and validation, we will obtain
the agility needed to phase out rsync altogether and/or introduce
other future access protocols.
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Status of This Memo
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Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Plan to prefer RRDP . . . . . . . . . . . . . . . . . . . . . 4
3.1. Phase 0 - RPKI repositories support rsync, and optionally
RRDP . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Updates to RFC 8182 . . . . . . . . . . . . . . . . . 4
3.1.2. Updates to RFC 6481 . . . . . . . . . . . . . . . . . 5
3.2. Phase 1 - RPKI repositories support both rsync and RRDP . 6
3.2.1. Updates to RFC 6481 . . . . . . . . . . . . . . . . . 6
3.2.2. Measurements . . . . . . . . . . . . . . . . . . . . 7
3.3. Phase 2 - All RP software prefers RRDP . . . . . . . . . 7
3.3.1. Updates to RFC 8182 . . . . . . . . . . . . . . . . . 7
3.3.2. Rsync URIs as object identifiers . . . . . . . . . . 7
3.3.3. Measurements . . . . . . . . . . . . . . . . . . . . 8
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4. Future Objective: Remove the dependency on rsync . . . . . . 8
4.1. Phase 3 - RPKI repositories support RRDP, and optionally
rsync . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Updates to RFC 6481 . . . . . . . . . . . . . . . . . 8
4.2. Transport agnostic RPKI object names . . . . . . . . . . 9
5. Appendix - Implementation Status . . . . . . . . . . . . . . 10
5.1. Current RRDP Support in Repository Software . . . . . . . 10
5.2. Current RRDP Support in Relying Party software . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Requirements notation
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.
2. Motivation
The Resource Public Key Infrastructure (RPKI) [RFC6480] as originally
defined uses rsync as its distribution protocol, as outlined in
[RFC6481]. Later, the RPKI Repository Delta Protocol (RRDP)
[RFC8182] was designed to provide an alternative. In order to
facilitate incremental deployment RRDP has been deployed as an
additional optional protocol, while rsync was still mandatory to
implement.
While rsync has been very useful in the initial deployment of RPKI, a
number of issues observed with it motivated the design of RRDP, e.g.:
o rsync is CPU and memory heavy on the server side, and easy to DoS
o rsync library support is lacking, complicating RP efficiency and
error logging
o we cannot ensure that RPs get atomic sets of updated objects
RRDP was designed to leverage HTTPS CDN infrastructure to provide
RPKI Repository content in a resilient way, while reducing the load
on the Repository server. It supports that updates are published as
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atomic deltas, which can help prevent most of the issues described in
section 6 of [RFC6486].
For a longer discussion please see section 1 of [RFC8182].
In conclusion: we believe that while RRDP is not perfect, and we may
indeed need future work to improve on it, it is an improvement over
using rsync in the context of RPKI. Therefore, this document
outlines a transition plan where RRDP becomes mandatory to implement,
and the operational dependency on rsync is reduced to that of a
fallback option.
3. Plan to prefer RRDP
Changing the RPKI infrastructure to rely on RRDP instead of rsync is
a delicate operation. There is current deployment of Certification
Authorities, Repository Servers and Relying Party software which
relies on rsync, and which may not yet support RRDP.
Therefore we need to have a plan that ultimately updates the relevant
RFCs, but which uses a phased approach combined with measurements to
limit the operational impact of doing this to (almost) zero.
The general outline of the plan is as follows. We will describe each
step in more detail below.
+-------+------------------------------------------------------+
| Phase | Description |
+-------+------------------------------------------------------+
| 0 | RPKI repositories support rsync, and optionally RRDP |
| 1 | RPKI repositories support both rsync and RRDP |
| 2 | All RP software prefers RRDP |
+-------+------------------------------------------------------+
3.1. Phase 0 - RPKI repositories support rsync, and optionally RRDP
This is the situation at the time of writing this document. Relying
Parties can prefer RRDP over rsync today, but they need to support
rsync until all RPKI repositories support RRDP. Therefore all
repositories should support RRDP at their earliest convenience.
3.1.1. Updates to RFC 8182
Repositories which support RRDP MUST ensure that RRDP resources are
available to Relying Parties (section 3.3 of [RFC8182]).
Furthermore, the RRDP repository MUST include all current repository
objects. Because of this the choice of falling back to alternative
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repository access mechanisms was left as a local policy choice of RP
software.
However, following discussions on this subject it has become clear
that there is a preference to instruct RP software to make use of all
possible data sources. The main motivation being that because of
RPKI object security using a secondary source of data can never lead
to a worse outcome in terms of validation.
The following update is therefore applicable to section 3.4.5
"Considerations Regarding Operational Failures in RRDP" of [RFC8182]:
OLD: Relying Parties could attempt to use alternative repository
access mechanisms, if they are available, according to the
accessMethod element value(s) specified in the SIA of the associated
certificate (see Section 4.8.8 of [RFC6487]).
NEW: Relying Parties MUST attempt to use alternative repository
access mechanisms, if they are available, according to the
accessMethod element value(s) specified in the SIA of the associated
certificate (see Section 4.8.8 of [RFC6487]).
3.1.2. Updates to RFC 6481
As noted above section 3.3 of [RFC8182] already stipulates that RRDP
files MUST be made available by repositories which support RRDP. In
other words the RRDP service must be treated as a critical service
wherever it is supported.
During this phase the updates are applied to section 3 of [RFC6481],
to make this abundantly clear:
OLD:
o The publication repository SHOULD be hosted on a highly available
service and high-capacity publication platform.
o The publication repository MUST be available using rsync [RFC5781]
[RSYNC]. Support of additional retrieval mechanisms is the choice
of the repository operator. The supported retrieval mechanisms
MUST be consistent with the accessMethod element value(s)
specified in the SIA of the associated CA or EE certificate.
NEW:
o The publication repository MAY be available using the RPKI
Repository Delta Protocol [RFC8182]. If RPDP is provided, it
SHOULD be hosted on a highly available platform.
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o The publication repository MUST be available using rsync [RFC5781]
[RSYNC]. The rsync server SHOULD be hosted on a highly available
platform.
o Support of additional retrieval mechanisms is the choice of the
repository operator. The supported retrieval mechanisms MUST be
consistent with the accessMethod element value(s) specified in the
SIA of the associated CA or EE certificate.
3.2. Phase 1 - RPKI repositories support both rsync and RRDP
During this phase we will make RRDP mandatory to support for
Repository Servers, and measure whether the deployed Repository
Servers have been upgraded to do so, in as far as they don't support
RRDP already.
3.2.1. Updates to RFC 6481
During this phase the updates are applied to section 3 of [RFC6481].
OLD:
o The publication repository SHOULD be hosted on a highly available
service and high-capacity publication platform.
o The publication repository MUST be available using rsync [RFC5781]
[RSYNC]. Support of additional retrieval mechanisms is the choice
of the repository operator. The supported retrieval mechanisms
MUST be consistent with the accessMethod element value(s)
specified in the SIA of the associated CA or EE certificate.
NEW:
o The publication repository MUST be available using the RPKI
Repository Delta Protocol [RFC8182]. The RRDP server SHOULD be
hosted on a highly available platform.
o The publication repository MUST be available using rsync [RFC5781]
[RSYNC]. The rsync server SHOULD be hosted on a highly available
platform.
o Support of additional retrieval mechanisms is the choice of the
repository operator. The supported retrieval mechanisms MUST be
consistent with the accessMethod element value(s) specified in the
SIA of the associated CA or EE certificate.
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3.2.2. Measurements
We can find out whether all RPKI repositories support RRDP by running
(possibly) modified Relying Party software that keeps track of this.
When it is found that Repositories do not yet support RRDP, outreach
should be done to them individually. Since the number of
Repositories is fairly low, and it is in their interest to run RRDP
because it addresses availability concerns, we have confidence that
we will find these Repositories willing to make changes.
3.3. Phase 2 - All RP software prefers RRDP
Once all Repositories support RRDP we can proceed to make RRDP
mandatory to implement for Relying Party software.
3.3.1. Updates to RFC 8182
From this phase onwards the updates are applied to section 3.4.1 of
[RFC8182].
OLD: When a Relying Party performs RPKI validation and learns about a
valid certificate with an SIA entry for the RRDP protocol, it SHOULD
use this protocol as follows.
NEW: When a Relying Party performs RPKI validation and learns about a
valid certificate with an SIA entry for the RRDP protocol, it MUST
use this protocol with preference.
Relying Parties MUST NOT attempt to fetch objects using alternate
access mechanisms, if object retrieval through this protocol is
successful.
However, as stipulated in section 3.4.5, Relying Parties MUST attempt
to use alternative repository access mechanisms, if object retrieval
through this protocol is unsuccessful.
3.3.2. Rsync URIs as object identifiers
Rsync URIs are used in the RPKI to name objects and hierarchies, and
they are as such very useful when doing RPKI object validation, as
well as for error reporting on validation issues.
Note that RRDP includes rsync URIs in its structure. See section 3.5
of [RFC8182]. Theoretically, RRDP servers could include any rsync
URI. However, Relying Party software knows which RRDP server to is
expected to include the rsync URIs for RPKI objects issued under any
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given CA certificate, because of the id-ad-rpkiNotify SIA extenion,
see section 3.2 of [RFC8182].
Thus, objects retrieved through RRDP can be mapped easily to files
and URIs, similar to as though rsync would have been used to retrieve
them.
3.3.3. Measurements
Although the tools may support RRDP, users will still need to install
updated versions of these tools in their infrastructure. Any
Repository operator can measure this transition by observing access
to their RRDP and rsync repositories respectively.
But even after new versions have been available, it is expected that
there will be long, low volume, tail of users who did not upgrade and
still depend on rsync.
It is hard to quantify here now, what would be an acceptable moment
to conclude that it's safe to move to the next phase and make rsync
optional. A parallel to the so-called DNS Flag Day comes to mind.
4. Future Objective: Remove the dependency on rsync
Note that, while we discuss this here, we would probably do well to
separate this section into a separate follow-up document.
4.1. Phase 3 - RPKI repositories support RRDP, and optionally rsync
The end goal of this phase would be that there will be no operational
dependencies on rsync for Repositories, although they MAY still
choose to operate rsync at a best effort basis.
The most pragmatic way to deal with rsync URIs in the RPKI would be
to continue to use them as namespaces, but no longer require that
rsync is available. Much like how https based namespaces are used in
XML.
4.1.1. Updates to RFC 6481
From this phase onwards these updates are applied to section 3 of
[RFC6481] as it was updated during Phase 2 described above:
OLD:
o The publication repository MUST be available using the RPKI
Repository Delta Protocol [RFC8182]. The RRDP server SHOULD be
hosted on a highly available platform.
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o The publication repository MUST be available using rsync [RFC5781]
[RSYNC]. The rsync server SHOULD be hosted on a highly available
platform.
o Support of additional retrieval mechanisms is the choice of the
repository operator. The supported retrieval mechanisms MUST be
consistent with the accessMethod element value(s) specified in the
SIA of the associated CA or EE certificate.
NEW:
o The publication repository MUST be available using the RPKI
Repository Delta Protocol [RFC8182]. The RRDP server SHOULD be
hosted on a highly available platform.
o The publication repository MAY be available using rsync [RFC5781]
[RSYNC].
o Support of additional retrieval mechanisms is the choice of the
repository operator. The supported retrieval mechanisms MUST be
consistent with the accessMethod element value(s) specified in the
SIA of the associated CA or EE certificate.
Note that this means that RP software is still required to try to
fall back to rsync if RRDP is unavailable, but it may find that the
rsync repository is not available.
4.2. Transport agnostic RPKI object names
We could develop a new naming scheme for RPKI objects. Perhaps based
on Universal Resource Names ([RFC8141]). Doing so, would allow us to
use names which are independent from retrieval mechanisms, and thus
they could be less confusing in some regards, and provide more
agility with regards to future changes in those mechanisms. However,
this would require that many updates are made to existing RFCs. An
incomplete list:
o RFC6487 New names would have be allowed in the SIA, or perhaps an
X509 extension, could be used. But, the latter would have a
direct impact on the deployability of updated CA certificates - RP
software would reject these certificates if the extension is
marked as critical by the CA and not understood by the RP.
o RFC6492 New names (in whatever form) would need to be included
certificate sign requests sent to a parent CA. The parent CA will
need to include a 'cert_url', indicating where an issued
certificate is published, in a different format.
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o RFC8181 The RPKI publication protocol is based rsync URIs, and it
assumes that publishers have access to a specific directory in
rsync space. This would need to be changed.
o RFC8183 This RFC defines the identity exchange between an RPKI CA
and Publication Server. The server's response includes an
'sia_base', in the form of an rsync directory, under which a CA is
supposed to name its objects.
o RFC8182 The RRDP protocol uses rsync URIs for compatibility with
rsync as a retrieval method. This would need to be updated.
Obviously this needs more discussion.
The exercise would not be trivial. But, arguably doing this work
will not become easier by postponing it, and once done would leave
the RPKI better positioned to use alternative access methods in
future as well.
5. Appendix - Implementation Status
Note that this section is included for tracking purposes during the
discussion phase of this document and is not intended to be included
in an RFC.
5.1. Current RRDP Support in Repository Software
The currently known support for RRDP for repositories is as follows:
+---------------------------+------------------+
| Repository Implementation | Support for RRDP |
+---------------------------+------------------+
| afrinic | yes |
| apnic | yes |
| arin | yes |
| lacnic | ongoing |
| ripe ncc | yes |
| Dragon Research Labs | yes(1,2) |
| krill | yes(1) |
+---------------------------+------------------+
(1) in use at various National Internet Registries, as well as other
resource holders under RIRs. (2) not all organizations using this
software have upgraded to using RRDP.
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5.2. Current RRDP Support in Relying Party software
The currently known support for RRDP in Relying Party software is as
follows:
+------------------------------+---------+---------+---------+
| Relying Party Implementation | RRDP | version | since |
+------------------------------+---------+---------+---------+
| FORT | yes | 1.2.0 | 02/2021 |
| OctoRPKI | yes | 1.0.0 | 02/2019 |
| rcynic | yes | ? | ? |
| RIPE NCC RPKI Validator 2.x | yes | 2.18 | 07/2015 |
| RIPE NCC RPKI Validator 3.x | yes | 3.0 | 03/2018 |
| Routinator | yes | 0.6.0 | 09/2019 |
| rpki-client | ongoing | ? | ? |
| RPSTIR2 | yes | 2.0 | 04/2020 |
+------------------------------+---------+---------+---------+
The authors kindly request Relying Party software implementers to let
us know in which version of their tool support for RRDP was
introduced, and when that version was released.
6. IANA Considerations
This document has no IANA actions.
7. Security Considerations
TBD
8. Acknowledgements
TBD
9. References
9.1. 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>.
[RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI
Scheme", RFC 5781, DOI 10.17487/RFC5781, February 2010,
<https://www.rfc-editor.org/info/rfc5781>.
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[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <https://www.rfc-editor.org/info/rfc6480>.
[RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for
Resource Certificate Repository Structure", RFC 6481,
DOI 10.17487/RFC6481, February 2012,
<https://www.rfc-editor.org/info/rfc6481>.
[RFC6486] Austein, R., Huston, G., Kent, S., and M. Lepinski,
"Manifests for the Resource Public Key Infrastructure
(RPKI)", RFC 6486, DOI 10.17487/RFC6486, February 2012,
<https://www.rfc-editor.org/info/rfc6486>.
[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>.
[RFC8182] Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"The RPKI Repository Delta Protocol (RRDP)", RFC 8182,
DOI 10.17487/RFC8182, July 2017,
<https://www.rfc-editor.org/info/rfc8182>.
9.2. Informative References
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/info/rfc8141>.
Authors' Addresses
Tim Bruijnzeels
NLnet Labs
Email: tim@nlnetlabs.nl
URI: https://www.nlnetlabs.nl/
Randy Bush
Internet Initiative Japan & Arrcus, Inc.
Email: randy@psg.com
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George Michaelson
APNIC
Email: ggm@apnic.net
URI: http://www.apnic.net
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