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Internet Engineering Task Force (IETF)                           M. WestRequest for Comments: 7762                                   Google, IncCategory: Informational                                     January 2016ISSN: 2070-1721Initial Assignment for the Content Security Policy Directives RegistryAbstract   This document establishes an Internet Assigned Number Authority   (IANA) registry for Content Security Policy directives and populates   that registry with the directives defined in the Content Security   Policy Level 2 specification.Status of This Memo   This document is not an Internet Standards Track specification; it is   published for informational purposes.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Not all documents   approved by the IESG are a candidate for any level of Internet   Standard; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7762.Copyright Notice   Copyright (c) 2016 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://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 Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.West                          Informational                     [Page 1]

RFC 7762      Content Security Policy Registry Assignments  January 2016Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .22.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .23.  Use of the Registry . . . . . . . . . . . . . . . . . . . . .24.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .34.1.  Content Security Policy Directives Registry . . . . . . .3     4.2.  Registration Policy for Content Security Policy           Directives  . . . . . . . . . . . . . . . . . . . . . . .45.  Security Considerations . . . . . . . . . . . . . . . . . . .46.  References  . . . . . . . . . . . . . . . . . . . . . . . . .56.1.  Normative References  . . . . . . . . . . . . . . . . . .56.2.  Informative References  . . . . . . . . . . . . . . . . .5   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .5   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .51.  Introduction   The Content Security Policy (CSP) specification [CSP] defines a   mechanism that web developers can use to control the resources that a   particular page can fetch or execute, as well as a number of   additional security-relevant policy decisions.   The policy language specified in that document consists of an   extensible set of "directives", each of which controls a specific   resource type or policy decision.  This specification establishes a   registry to ensure that extensions to CSP are listed and   standardized.2.  Terminology   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [RFC2119].3.  Use of the Registry   Content Security Policy directives must be documented in a readily   available public specification in order to be registered by IANA.   This documentation MUST fully explain the syntax, intended usage, and   semantics of the directive.  The intent of this requirement is to   assure interoperable independent implementations, and to prevent   accidental namespace collisions between implementations of dissimilar   features.   Documents defining new Content Security Policy directives MUST   register them with IANA, as described inSection 3.  The IANAWest                          Informational                     [Page 2]

RFC 7762      Content Security Policy Registry Assignments  January 2016   registration policy for such parameters is "Specification Required"   [RFC5226] and is further discussed inSection 3.2.4.  IANA Considerations   This specification creates a new top-level IANA registry named   "Content Security Policy Directives".4.1.  Content Security Policy Directives Registry   New Content Security Policy directives, and updates to existing   directives, MUST be registered with IANA.   When registering a new Content Security Policy directive, the   following information MUST be provided:   o  The directive's name, an ASCII string conforming to the      "directive-name" rule specified in Section 4.1 of [CSP].  The ABNF      [RFC5234] is as follows:          directive-name  = 1*( ALPHA / DIGIT / "-" )   o  A reference to the readily available public specification defining      the new directive's syntax, usage, and semantics.   The following table contains the initial values for this registry:                      +-----------------+-----------+                      | Directive Name  | Reference |                      +-----------------+-----------+                      | base-uri        | [CSP]     |                      | child-src       | [CSP]     |                      | connect-src     | [CSP]     |                      | default-src     | [CSP]     |                      | font-src        | [CSP]     |                      | form-action     | [CSP]     |                      | frame-ancestors | [CSP]     |                      | frame-src       | [CSP]     |                      | img-src         | [CSP]     |                      | media-src       | [CSP]     |                      | object-src      | [CSP]     |                      | plugin-types    | [CSP]     |                      | report-uri      | [CSP]     |                      | sandbox         | [CSP]     |                      | script-src      | [CSP]     |                      | style-src       | [CSP]     |                      +-----------------+-----------+West                          Informational                     [Page 3]

RFC 7762      Content Security Policy Registry Assignments  January 20164.2.  Registration Policy for Content Security Policy Directives   The registration policy for Content Security Policy directives is   "Specification Required" [RFC5226], which uses a designated expert to   review the specification.   When appointing an Expert (or Experts), the IESG SHOULD draw from the   W3C's security community, coordinating through the liaison.   The designated expert, when deliberating on whether to include a new   directive in the registry, SHOULD consider the following criteria.   This is not an exhaustive list, but representative of the issues to   consider when rendering a decision:   o  Content Security Policy is a restrictive feature, which allows web      developers to deny themselves access to resources and APIs that      would otherwise be available.  Deploying Content Security Policy      is, therefore, a strict reduction in risk.  The expert SHOULD      carefully consider whether proposed directives would violate this      property.   o  Granular directives are valuable, but the expert SHOULD strive to      strike a reasonable balance between providing developers with all      the knobs and switches possible and providing only those with      known security implications.5.  Security Considerations   The registry in this document does not in itself have security   implications.  The directives specified, however, certainly do.  The   documents referenced when registering new directives MUST contain   detailed security and privacy considerations sections, and SHOULD   contain usage information that informs web developers as to the   directive's expected implementation.West                          Informational                     [Page 4]

RFC 7762      Content Security Policy Registry Assignments  January 20166.  References6.1.  Normative References   [CSP]      West, M., Barth, A., and D. Veditz, "Content Security              Policy Level 2", July 2015, <https://www.w3.org/TR/CSP2>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              DOI 10.17487/RFC5226, May 2008,              <http://www.rfc-editor.org/info/rfc5226>.   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax              Specifications: ABNF", STD 68,RFC 5234,              DOI 10.17487/RFC5234, January 2008,              <http://www.rfc-editor.org/info/rfc5234>.6.2.  Informative References   [RFC5341]  Jennings, C. and V. Gurbani, "The Internet Assigned Number              Authority (IANA) tel Uniform Resource Identifier (URI)              Parameter Registry",RFC 5341, DOI 10.17487/RFC5341,              September 2008, <http://www.rfc-editor.org/info/rfc5341>.Acknowledgements   Much of this document's structure comes from [RFC5341].  Thank you to   Cullen Jennings and Vijay K. Gurbani for giving me a reasonable   template to work within and to Barry Leiba for his helpful commentary   and suggestions.Author's Address   Mike West   Google, Inc   Email: mkwst@google.com   URI:https://mikewest.org/West                          Informational                     [Page 5]