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INTERNET-DRAFT                                               Rob Weltman
Intended Category: Standards Track                          Yahoo!, Inc.
                                                               June 2005

                   LDAP Proxied Authorization Control

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   This document defines the Lightweight Directory Access Protocol
   (LDAP) Proxy Authorization Control. The Proxy Authorization Control
   allows a client to request that an operation be processed under a
   provided authorization identity instead of as the current
   authorization identity associated with the connection.

1. Introduction

   Proxy authorization allows a client to request that an operation be
   processed under a provided authorization identity instead of as the
   current authorization identity associated with the connection. This
   document defines support for proxy authorization using the Control
   mechanism [RFC 2251]. The Lightweight Directory Access Protocol
   [LDAPV3] supports the use of the Simple Authentication and Security
   Layer [SASL] for authentication and for supplying an authorization
   identity distinct from the authentication identity, where the
   authorization identity applies to the whole LDAP session. The Proxy
   Authorization Control provides a mechanism for specifying an

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   authorization identity on a per operation basis, benefiting clients
   that need to efficiently perform operations on behalf of multiple

   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
   used in this document  are  to be interpreted as described in

2. Publishing support for the Proxy Authorization Control

   Support for the Proxy Authorization Control is indicated by the
   presence of the Object Identifier (OID) "2.16.840.1.113730.3.4.18" in
   the supportedControl attribute [RFC 2252] of a server's root DSE.

3. Proxy Authorization Control

   A single Proxy Authorization Control may be included in any search,
   compare, modify, add, delete, modify DN or extended operation request
   message with the exception of any extension that causes a change in
   authentication, authorization, or data confidentiality [RFC 2829],
   such as Start TLS [LDAPTLS] as part of the controls field of the
   LDAPMessage, as defined in [RFC 2251].

   The controlType of the proxy authorization control is

   The criticality MUST be present and MUST be TRUE. This requirement
   protects clients from submitting a request that is executed with an
   unintended authorization identity.

   Clients MUST include the criticality flag and MUST set it to TRUE.
   Servers MUST reject any request containing a Proxy Authorization
   Control without a criticality flag or with the flag set to FALSE with
   a protocolError error.  These requirements protect clients from
   submitting a request that is executed with an unintended
   authorization identity.

   The controlValue SHALL be present and contain either an authzId
   [AUTH] representing the authorization identity for the request or
   empty if an anonymous association is to be used.

   The mechanism for determining proxy access rights is specific to the
   server's proxy authorization policy.

   If the requested authorization identity is recognized by the server,
   and the client is authorized to adopt the requested authorization
   identity, the request will be executed as if submitted by the proxy
   authorization identity, otherwise the result code TBD is returned.
   [Note to the IESG/IANA/RFC Editor: the value TBD is to be replaced
   with an IANA assigned LDAP Result Code (see RFC 3383 section 3.6]

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4. Implementation Considerations

   One possible interaction of proxy authorization and normal access
   control is illustrated here for the case of search requests. During
   evaluation of a search request, an entry which would have been
   returned for the search if submitted by the proxy authorization
   identity directly may not be returned if the server finds that the
   requester does not have the right to assume the requested identity
   for searching the entry, even if the entry is within the scope of a
   search request under a base DN which does imply such rights. This
   means that fewer results, or no results, may be returned compared to
   the case where the proxy authorization identity issued the request
   directly. An example of such a case may be a system with fine-grained
   access control, where the proxy right requester has proxy rights at
   the top of a search tree, but not at or below a point or points
   within the tree.

5. Security Considerations

   The Proxy Authorization Control method is subject to general LDAP
   security considerations [RFC 2251] [AUTH] [LDAPTLS]. The control may
   be passed over a secure as well as over an insecure channel.

   The control allows for an additional authorization identity to be
   passed. In some deployments, these identities may contain
   confidential information which require privacy protection.

   Note that the server is responsible for determining if a proxy
   authorization request is to be honored. "Anonymous" users SHOULD NOT
   be allowed to assume the identity of others.

6. IANA Considerations

   The OID "2.16.840.1.113730.3.4.18" is reserved for the Proxy
   Authorization Control. It is to be registered as an LDAP Protocol
   Mechanism [RFC 3383].

   A result code for the case where the server does not execute a
   request using the proxy authorization identity is to be assigned by
   the IANA.

7. Copyright

   Copyright (C) The Internet Society (2005).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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   This document and the information contained herein are provided on an

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the  purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

8. Normative References

   [KEYWORDS] Bradner, Scott, "Key Words for use in RFCs to Indicate
        Requirement Levels", draft-bradner-key-words-03.txt, January,

   [LDAPV3] Hodges, J. and R. Morgan, "Lightweight Directory Access
        Protocol (v3): Technical Specification", RFC 3377, September

   [SASL] J. Myers, "Simple Authentication and Security Layer (SASL)",
        RFC 2222, October 1997

   [AUTH] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan, "Authentication
        Methods for LDAP", RFC 2829, May 2000

   [LDAPTLS] J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory
        Access Protocol (v3): Extension for Transport Layer Security",
        RFC 2830, May 2000

   [RFC 2251] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
        Protocol (v3)", RFC 2251, December 1997.

   [RFC 2252] M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight
        Directory Access Protocol (v3): Attribute Syntax Definitions",
        RFC 2252, December 1997

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   [RFC 2829] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan,
        "Authentication Methods for LDAP", RFC 2829, May 2000

   [RFC 3383] K. Zeilenga, "Internet Assigned Numbers Authority (IANA)
        Considerations for the Lightweight Directory Access Protocol
        (LDAP)", RFC 3383, September 2002

9. Author's Address

   Rob Weltman
   Yahoo!, Inc
   701 First Avenue
   Sunnyvale, CA 94089
   +1 408 349-5504

10. Acknowledgements

   Mark Smith, formerly of Netscape Communications Corp., Mark Wahl,
   formerly of Sun Microsystems, Inc, Kurt Zeilenga of OpenLDAP
   Foundation, Jim Sermersheim of Novell, and Steven Legg of Adacel have
   contributed with reviews of this document.

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