Internet Engineering Task Force (IETF)                           M. West
Request for Comments: 7762                                   Google, Inc
Category: Informational                                     January 2016
ISSN: 2070-1721


Initial Assignment for the Content Security Policy Directives Registry

Abstract

  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; see Section 2 of RFC 5741.

  Information about the current status of this document, any errata,
  and how to provide feedback on it may be obtained at
  http://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 to BCP 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.






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Table of Contents

  1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
  2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
  3.  Use of the Registry . . . . . . . . . . . . . . . . . . . . .   2
  4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
    4.1.  Content Security Policy Directives Registry . . . . . . .   3
    4.2.  Registration Policy for Content Security Policy
          Directives  . . . . . . . . . . . . . . . . . . . . . . .   4
  5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
  6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
    6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
    6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
  Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  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 in Section 3.  The IANA




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  registration policy for such parameters is "Specification Required"
  [RFC5226] and is further discussed in Section 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]     |
                     +-----------------+-----------+




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4.2.  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.

















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6.  References

6.1.  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: [email protected]
  URI:   https://mikewest.org/








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