SIDR Operations Z. Yan Internet-Draft CNNIC Intended status: Informational R. Bush Expires: 31 July 2023 IIJ Research Lab & Arrcus, Inc. G.G. Geng Jinan University T. de Kock RIPE NCC J. Yao CNNIC January 2023 Avoidance for ROA Containing Multiple IP Prefixes draft-ietf-sidrops-roa-considerations-06 Abstract When using the RPKI, address space holders need to issue a ROA object(s) to authorize one or more ASes to originate routes to IP prefix(es). This memo discusses operational problems which may arise from ROAs containing multiple IP prefixes, and recommends that each ROA only contain a single IP prefix. 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/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 5 July 2023. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Yan, et al. Expires 31 July 2023 [Page 1] Internet-Draft ROA considerations January 2023 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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction In the Resource Public Key Infrastructure (RPKI), a Route Origin Authorization (ROA) is a digitally signed object which identifies that a single Autonomous System (AS) has been authorized by the address space holder to originate routes to one or more prefixes within the address space [RFC6482]. Each ROA contains an "asID" field and an "ipAddrBlocks" field. The "asID" field contains one single AS number which is authorized to originate routes to the given IP address prefix(es). The "ipAddrBlocks" field contains one or more IP address prefixes to which the AS is authorized to originate the routes. If the address space holder needs to authorize more than one AS to advertise the same set of IP prefixes, multiple ROAs must be issued (one for each AS number [RFC6480]). Prior to this document, there was no guidance for choosing to issue a separate ROA for each IP prefix or a single ROA containing multiple IP prefixes. Yan, et al. Expires 31 July 2023 [Page 2] Internet-Draft ROA considerations January 2023 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. 3. Problem Statement An address space holder can issue a separate ROA for each of its routing announcements. Alternatively, for a given asID, it can issue a single ROA for multiple routing announcements, or even for all of its routing announcements. Since a given ROA is either valid or invalid, the routing announcements for which that ROA was issued will "share fate" when it comes to RPKI validation. Currently, no guidance is offered in existing RFCs to recommend what kinds of ROA are issued: one per prefix, or one ROA for multiple routing announcements. The problem of fate-sharing is not discussed or addressed. In the RPKI trust chain, the Certification Authority (CA) certificate issued by a parent CA to a delegate of some resources may be replaced by the parent at any time resulting in changes to resources specified in the [RFC3779] certificate extension. Any ROA object that includes resources which are a) no longer contained in the new CA certificate, or b) contained in a new CA certificate that is not yet discovered by Relying Party (RP) software, will be rejected as invalid. Since ROA invalidity affects all routes specified in that ROA, unchanged resources with associated routes via that asID cannot be separated from those affected by the change in the CA certificate validity. They will fall under this invalid ROA even though there was no intention to change their validity. Had these resources been in a separate ROA, there would have been no neccessary change to the issuing CA certificate, and therefore no necessary invalidity. CAs should carefully coordinate ROA updates with resource certificate updates. This process may be automated if a single entity manages both the parent CA and the CA issuing the ROAs (scenario D in [[RFC8211] Section 3]). However, in other deployment scenarios, this coordination becomes more complex. For the ROA containing multiple IP prefixes, these IP prefixes share the same expiry configuration. If the ROA is not reissued in a timely manner, the whole set of IP prefixes will be affected after expiry as the ROA becomes invalid. Had these prefixes been in separately issued ROA, their validity interval would be unique to each ROA, and invalidity only affected by re-issuance of the specific parent CA which issued them. Yan, et al. Expires 31 July 2023 [Page 3] Internet-Draft ROA considerations January 2023 A prefix could be allowed to be originated from an AS only for a specific period of time, for example if the IP prefix was leased out temporarily. This would be more difficult to manage, and potentially be more error-prone if a ROA with multiple IP prefixes was used. Similarly more complex routing may demand changes in asID or routes for a subset of prefixes. Re-issuance of the ROA may cause change to validity for all routes in the affected ROA. If the time limited resources are in a separate ROA, or for more complex routing if each change in asID or routes for a given prefix reflects changes to discrete ROA, then no change to validity of unaffected routes will be caused. The use of ROA with a single IP prefix can minimize these side- effects. It avoids fate-sharing irrespective of the causes, where the parent CA issuing each ROA remains valid and where each ROA itself remains valid. 4. Recommendations For normal ROA issuance, it is recommended to include a single IP prefix in each ROA, and to issue one ROA for each advertised prefix. In some special scenarios, for example where the resource ownership and route origin state is stable (e.g., the IP addresses of a DNS root server and the related AS number), or a CA has operational problems producing increased number of individual ROAs, or if the goal is to implement fate-sharing for a set of prefixes as a deliberate policy then multiple IP prefixes may be grouped into one ROA. Where announced prefixes align and would permit aggregation, but the aggregated one is not announced in Border Gateway Protoco (BGP), it is not recommended to aggregate multiple announced prefixes into one ROA by adjusting prefix length ([RFC9319] Section 5: Recommendations about Minimal ROAs and maxLength). Instead, the specific announced prefixes should have their own ROA. 5. Security Considerations Issuing separate ROAs for independent IP prefixes may increase the file fetch burden on RP during validation. Then some compression algorithm as in [GSG17] MAY be adopted to reduce the potential impact on the performance of the RPKI ecosystem. 6. IANA Considerations This document does not request any IANA action. Yan, et al. Expires 31 July 2023 [Page 4] Internet-Draft ROA considerations January 2023 7. Acknowledgements The authors wish to thank the following people for their review and contributions to this document: George Michaelson, Tim Bruijnzeels, Job Snijders, Di Ma, Geoff Huston, Tom Harrison, Rob Austein, Stephen Kent, Christopher Morrow, Russ Housley, Ching-Heng Ku, Keyur Patel, Cuiling Zhang and Kejun Dong. Thanks are also due to Warren Kumari for the Security Area Directorate review. This work was supported by the Beijing Nova Program of Science and Technology under grant Z191100001119113. This document was produced using the xml2rfc tool [RFC2629]. 8. References 8.1. 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, . [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, DOI 10.17487/RFC3779, June 2004, . [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480, February 2012, . [RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route Origin Authorizations (ROAs)", RFC 6482, DOI 10.17487/RFC6482, February 2012, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8211] Kent, S. and D. Ma, "Adverse Actions by a Certification Authority (CA) or Repository Manager in the Resource Public Key Infrastructure (RPKI)", RFC 8211, DOI 10.17487/RFC8211, September 2017, . 8.2. Informative References Yan, et al. Expires 31 July 2023 [Page 5] Internet-Draft ROA considerations January 2023 [GSG17] Gilad, Y., Sagga, O., and S. Goldberg, "MaxLength Considered Harmful to the RPKI", CoNEXT '17, DOI 10.1145/3143361.3143363, December 2017, . [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, DOI 10.17487/RFC2629, June 1999, . [RFC9319] Gilad, Y., Goldberg, S., Sriram, K., Snijders, J., and B. Maddison, "The Use of maxLength in the Resource Public Key Infrastructure (RPKI)", BCP 185, RFC 9319, DOI 10.17487/RFC9319, October 2022, . Authors' Addresses Zhiwei Yan CNNIC No.4 South 4th Street, Zhongguancun Beijing, 100190 P.R. China Email: yanzhiwei@cnnic.cn Randy Bush IIJ Research Lab & Arrcus, Inc. Email: randy@psg.com Guanggang Geng Jinan University No.601, West Huangpu Avenue Guangzhou 510632 P.R. China Email: gggeng@jnu.edu.cn Ties de Kock RIPE NCC Stationsplein 11 Amsterdam Netherlands Email: tdekock@ripe.net Yan, et al. Expires 31 July 2023 [Page 6] Internet-Draft ROA considerations January 2023 Jiankang Yao CNNIC No.4 South 4th Street, Zhongguancun Beijing, 100190 P.R. China Email: yaojk@cnnic.cn Yan, et al. Expires 31 July 2023 [Page 7]