Resource Public Key Infrastructure (RPKI) Repository Requirements
draft-ietf-sidrops-prefer-rrdp-01

Document Type Active Internet-Draft (sidrops WG)
Authors Tim Bruijnzeels  , Randy Bush  , George Michaelson 
Last updated 2021-10-22
Replaces draft-ietf-sidrops-deprecate-rsync
Stream Internet Engineering Task Force (IETF)
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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: 25 April 2022                                     G. Michaelson
                                                                   APNIC
                                                         22 October 2021

   Resource Public Key Infrastructure (RPKI) Repository Requirements
                   draft-ietf-sidrops-prefer-rrdp-01

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 preferred access protocol, and require rsync as a
   fallback option only.

   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.

   Phase 2 will start once the proposed updates are implemented by all
   compliant Repositories.  In this phase RRDP will become mandatory to
   implement for all compliant 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.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on 25 April 2022.

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Table of Contents

   1.  Requirements notation . . . . . . . . . . . . . . . . . . . .   3
   2.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Plan to prefer RRDP . . . . . . . . . . . . . . . . . . . . .   3
     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  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
       3.2.1.  Updates to RFC 6481 . . . . . . . . . . . . . . . . .   5
       3.2.2.  Measurements  . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Phase 2 - All RP software prefers RRDP  . . . . . . . . .   6
       3.3.1.  Updates to RFC 8182 . . . . . . . . . . . . . . . . .   6
       3.3.2.  Measurements  . . . . . . . . . . . . . . . . . . . .   6
   4.  Appendix - Implementation Status  . . . . . . . . . . . . . .   6
     4.1.  Current RRDP Support in Repository Software . . . . . . .   7
     4.2.  Current RRDP Support in Relying Party software  . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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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.:

   *  rsync is CPU and memory heavy on the server side, and easy to DoS

   *  rsync library support is lacking, complicating RP efficiency and
      error logging

   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 updates being published as
   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 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.

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   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             |
     +-------+------------------------------------------------------+

                                 Table 1

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.  Therefore all repositories
   should support RRDP at their earliest convenience.

3.1.1.  Updates to RFC 8182

   Section 3.4.5 of [RFC8182] has the following on "Considerations
   Regarding Operational Failures in RRDP":

   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]).

   The use of the lower case 'could' in this sentence has led some older
   versions of RP implementations to conclude that any fallback from
   RRDP to rsync as an alternative access mechanism is a local choice.
   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.

   Per this document text mentioned above is replaced by the following:

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   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]).

   Note that there is a risk that the rsync repository, as the
   alternative access mechanism, becomes overloaded in case all Relying
   Parties fall back to it at roughly the same time due to an issue with
   RRDP.  Therefore it is RECOMMENDED that Relying Parties use a retry
   strategy and/or random jitter time before falling back to rsync.
   But, the fallback to rsync MUST NOT be postponed for more than 1
   hour.

3.1.2.  Updates to RFC 6481

   Section 3.3 of [RFC8182] stipulates that RRDP files MUST be made
   available by repositories which support RRDP.  In other words
   [RFC8182] expects that RRDP repository availability is treated as a
   critical service wherever it is supported.

   Per this document the following bullet point is added to the
   considerations listed in in section 3 of [RFC6481]:

   *  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.

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

   In this phase the bullet point update to section 3 of [RFC6481]
   mentioned above, where it was said the publication repository MAY be
   available using the RPKI Repository Delta Protocol is replaced by:

   *  The publication repository MUST be available using the RPKI
      Repository Delta Protocol [RFC8182].  The RRDP server SHOULD be
      hosted on a highly available platform.

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.

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   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.  But note that RP
   software is not prohibited from implementing this support sooner.  At
   the time of this writing all known RP software supports RRDP,
   although it is not known to the authors whether all of them have RRDP
   enabled and use it as the preferred protocol.

3.3.1.  Updates to RFC 8182

   From this phase onwards the first paragraph of section 3.4.1 of
   [RFC8182] is replaced by the following:

   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 RRDP is unsuccessful.

3.3.2.  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 a long, low volume, tail of users who did not upgrade
   and still depend on rsync.

4.  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.

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4.1.  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)      |
             +---------------------------+------------------+

                                 Table 2

   (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.

4.2.  Current RRDP Support in Relying Party software

   All current versions of known Relying Party software support RRDP:

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      +==============================+=========+=========+=========+
      | Relying Party Implementation | support | version |  since  |
      +==============================+=========+=========+=========+
      |             DRL              |   yes   |    ?    |    ?    |
      +------------------------------+---------+---------+---------+
      |             FORT             |   yes   |  1.2.0  | 02/2021 |
      +------------------------------+---------+---------+---------+
      |           OctoRPKI           |   yes   |  1.0.0  | 02/2019 |
      +------------------------------+---------+---------+---------+
      |          Routinator          |   yes   |  0.6.0  | 09/2019 |
      +------------------------------+---------+---------+---------+
      |         rpki-client          |   yes   |  0.7.0  | 04/2021 |
      +------------------------------+---------+---------+---------+
      |           RPSTIR2            |   yes   |   2.0   | 04/2020 |
      +------------------------------+---------+---------+---------+

                                 Table 3

   But, support for RRDP does not necessarily mean that it is also
   enabled and preferred over rsync by default.  The authors kindly
   request that RP implementors provide the following information:

       +==============================+========+=========+=========+
       | Relying Party Implementation | prefer | version |  since  |
       +==============================+========+=========+=========+
       |             DRL              |   ?    |    ?    |    ?    |
       +------------------------------+--------+---------+---------+
       |             FORT             |  yes   |    ?    |    ?    |
       +------------------------------+--------+---------+---------+
       |           OctoRPKI           |   ?    |    ?    |    ?    |
       +------------------------------+--------+---------+---------+
       |          Routinator          |  yes   |  0.6.0  | 09/2019 |
       +------------------------------+--------+---------+---------+
       |         rpki-client          |   ?    |    ?    |    ?    |
       +------------------------------+--------+---------+---------+
       |           RPSTIR2            |   ?    |    ?    |    ?    |
       +------------------------------+--------+---------+---------+

                                  Table 4

5.  IANA Considerations

   This document has no IANA actions.

6.  Security Considerations

   TBD

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7.  Acknowledgements

   TBD

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>.

   [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>.

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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