Same-Origin Policy for the RPKI Repository Delta Protocol (RRDP)
draft-ietf-sidrops-rrdp-same-origin-04

SIDROPS                                                      J. Snijders
Internet-Draft                                                    Fastly
Updates: 8182 (if approved)                               2 October 2024
Intended status: Standards Track                                        
Expires: 5 April 2025

    Same-Origin Policy for the RPKI Repository Delta Protocol (RRDP)
                 draft-ietf-sidrops-rrdp-same-origin-04

Abstract

   This document describes a Same-Origin Policy (SOP) requirement for
   RPKI Repository Delta Protocol (RRDP) servers and clients.
   Application of SOP in RRDP client/server communication isolates
   resources such as Delta and Snapshot files from different Repository
   Servers, reducing possible attack vectors.  This document updates RFC
   8182.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 5 April 2025.

Copyright Notice

   Copyright (c) 2024 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
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Implications of cross-origin resource requests in RRDP  . . .   3
   3.  Changes to RFC 8182 . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  New Requirements for RRDP Repository Servers  . . . . . .   3
     3.2.  New Requirements for Relying Parties using RRDP . . . . .   3
   4.  Deployability in the Internet's current RPKI  . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   6
   Appendix B.  Implementation status  . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   This document specifies a Same-origin policy (SOP) requirement for
   RPKI Repository Delta Protocol (RRDP) servers and clients.  The SOP
   concept is a security mechanism to restrict how a document loaded
   from one origin can cause interaction with resources from another
   origin.  See [RFC6454] for an overview of the concept of an "origin".
   Application of SOP in RRDP client/server communication isolates
   resources such as Delta and Snapshot files from different Repository
   Servers, reducing possible attack vectors.  Another way to avoid
   undesirable implications (as described in Section 2) would be for a
   future version of the RRDP protocol to use relative URIs instead of
   absolute URIs.  This document updates [RFC8182].

1.1.  Requirements Language

   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.

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2.  Implications of cross-origin resource requests in RRDP

   The first RRDP protocol specification did not explicitly disallow
   'cross-origin' URI references from the Update Notification file
   (Section 3.5.1 of [RFC8182]) towards Delta (Section 3.5.3 of
   [RFC8182]) and Snapshot (Section 3.5.2 of [RFC8182]) files, and was
   silent on the topic of HTTP Redirection (Section 15.4 of [RFC9110]).

   The implication of cross-origin references in Update Notification
   files is that one Repository Server can reference RRDP resources on
   another Repository Server and in doing so inappropriately increase
   the resource consumption for both RRDP clients and the referenced
   Repository Server.  An adversary could also employ cross-origin HTTP
   Redirects towards other Repository Servers, causing similar
   undesirable behavior.

3.  Changes to RFC 8182

   To overcome the aforementioned issue described in Section 2, RRDP
   Repository Servers and Clients MUST apply a Same-Origin Policy to
   both the URIs referenced in an Update Notification File and any HTTP
   Redirects.

3.1.  New Requirements for RRDP Repository Servers

   The following checklist items are added to Section 3.5.1.3 of
   [RFC8182]:

   NEW

   |  *  The "uri" attribute in the snapshot element and optional delta
   |     elements MUST be part of the same origin (i.e., represent the
   |     same principal), meaning referenced URIs MUST have the same
   |     scheme, host, and port as the URI for the Update Notification
   |     File specified in the referring RRDP SIA AccessDescription.
   |  
   |  *  The Repository Server MUST NOT respond with HTTP Redirects
   |     towards locations with an origin different from the origin of
   |     the Update Notification File specified in the referring RRDP
   |     SIA AccessDescription.

3.2.  New Requirements for Relying Parties using RRDP

   The following adds to Section 3.4.1 of [RFC8182]:

   NEW

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   |  *  The Relying Party MUST verify whether the "uri" attributes in
   |     the Update Notification File are of the same origin as the
   |     Update Notification File itself.  If this verification fails,
   |     the file MUST be rejected and RRDP cannot be used, see
   |     Section 3.4.5 of [RFC8182] for considerations.  Implementations
   |     SHOULD log a message when cross-origin referrals are detected.
   |  
   |  *  The Relying Party MUST NOT follow HTTP Redirection following
   |     from attempts to download Update Notification, Delta, and
   |     Snapshot files if the target origin is different from the
   |     origin of the Update Notification File specified in the
   |     referring RRDP SIA AccessDescription.  If this verification
   |     fails, the RRDP session MUST be rejected and RRDP cannot be
   |     used, see Section 3.4.5 of [RFC8182] for considerations.
   |     Implementations SHOULD log a message when cross-origin
   |     redirects are detected.

4.  Deployability in the Internet's current RPKI

   Analysing the [rpkiviews] archives for the period from April to
   September 2024, only one RRDP server (reached following the TALs of
   the five Regional Internet Registries) employed a same-origin HTTP
   redirect.  In the period October 2021 - October 2024 no RRDP
   Repository Servers were observed which employed cross-origin URIs in
   Update Notification Files.

   This means that imposing a requirement for the application of a Same-
   Origin Policy does not cause any existing commonly-used RRDP
   Repository Server operations to become non-compliant.

5.  Security Considerations

   This document addresses an oversight in the original RRDP protocol
   specification: cross-origin requests are detrimental as they allow
   one repository operator to increase resource consumption for other
   repository operators and RRDP clients.

6.  IANA Considerations

   No IANA actions required.

7.  References

7.1.  Normative References

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   [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>.

   [RFC6454]  Barth, A., "The Web Origin Concept", RFC 6454,
              DOI 10.17487/RFC6454, December 2011,
              <https://www.rfc-editor.org/info/rfc6454>.

   [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>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.

7.2.  Informative References

   [FORT-validator]
              Leiva, A., "FORT validator",
              <https://fortproject.net/en/validator>.

   [Routinator]
              NLNet Labs, "Routinator",
              <https://github.com/NLnetLabs/routinator/>.

   [rpki-client]
              Jeker, C., Snijders, J., Dzonsons, K., and T. Buehler,
              "rpki-client", <https://www.rpki-client.org/>.

   [rpki-prover]
              Puzanov, M., "rpki-prover",
              <https://github.com/lolepezy/rpki-prover>.

   [rpkiviews]
              Snijders, J., "rpkiviews", October 2024,
              <http://www.rpkiviews.org/>.

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Appendix A.  Acknowledgements

   The author wishes to thank Theo Buehler, Claudio Jeker, Alberto
   Leiva, Tim Bruijnzeels, Ties de Kock, Martin Hoffmann, and Mikhail
   Puzanov for their helpful feedback, comments, and implementation
   work.  The author wishes to thank Keyur Patel, Meral Shirazipour,
   Niclas Comstedt, Dan Harkins, Erik Kline, Roman Danyliw, and Éric
   Vyncke for their review.

Appendix B.  Implementation status

   This section is to be removed before publishing as an RFC.

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in RFC 7942.
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to RFC 7942, "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

   *  OpenBSD's [rpki-client]

   *  Mikhail Puzanov's [rpki-prover]

   *  FORT project's [FORT-validator]

   *  NLNet Labs' [Routinator]

Author's Address

   Job Snijders
   Fastly
   Amsterdam
   Netherlands
   Email: job@fastly.com

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