]> Same-Origin Policy for the RPKI Repository Delta Protocol (RRDP) Fastly
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OPS sidrops same-origin RPKI RRDP This document describes a Same-Origin Policy (SOP) requirement for Resource Public Key Infrastructure (RPKI) Repository Delta Protocol (RRDP) servers and clients. Application of a 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.
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 for an overview of the concept of an "origin". Application of a 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 ) would be for a future version of RRDP to use relative URIs instead of absolute URIs. This document updates .
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 when, and only when, they appear in all capitals, as shown here.
Implications of Cross-Origin Resource Requests in RRDP The first RRDP specification did not explicitly disallow 'cross-origin' URI references from the Update Notification file () towards Delta () and Snapshot () files, and it was silent on the topic of HTTP Redirection (). 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.
Changes to RFC 8182 To overcome the issue described in , 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.
New Requirements for RRDP Repository Servers The following checklist items are added to : 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.
New Requirements for Relying Parties Using RRDP The following adds to : NEW
  • 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 for considerations. Implementations SHOULD log a message when cross-origin referrals are detected.
  • The Relying Party MUST NOT follow HTTP Redirection that results 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 for considerations. Implementations SHOULD log a message when cross-origin redirects are detected.
Deployability in the Internet's Current RPKI Analyzing the archives for the period from April to September 2024, only one RRDP server (reached following the Trust Anchor Locators (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 that 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.
Security Considerations This document addresses an oversight in the original RRDP specification: Cross-origin requests are detrimental as they allow one repository operator to increase resource consumption for other repository operators and RRDP clients.
IANA Considerations This document has no IANA actions.
References Normative References Informative References rpkiviews
Acknowledgements The author wishes to thank , , , , , , and for their helpful feedback, comments, and implementation work. The author wishes to thank , , , , , , and for their review.