INTERNET-DRAFT                                               Rob Weltman
Intended Category: Standards Track         Netscape Communications Corp.
                                                              May 2002

                   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.

   Internet-Drafts are working documents of the Internet Task Force
   (IETF), its areas, and its working groups.  Note that other groups
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   This document defines the Lightweight Directory Access Protocol
   (LDAP) Proxied Authorization Control. The Proxied Authorization
   Control allows a client to request that an operation be processed
   under a provided authorization identity [AUTH] instead of as the
   current authorization identity associated with the connection.

1. Introduction

   This document defines support for proxied authorization using the
   Control mechanism. LDAP [LDAPV3] supports the use of SASL [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 proposed Proxied Authorization
   Control provides a mechanism for specifying an authorization identity
   on a per operation basis, benefiting clients that need to efficiently
   perform operations on behalf of multiple users.

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

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2. Publishing support for the Proxied Authorization Control

   Support for the Proxied Authorization Control is indicated by the
   presence of the OID "2.16.840.1.113730.3.4.18" in the
   supportedControl attribute of a server's root DSE.

3. Proxied Authorization Control

   A single Proxied Authorization Control may be included in any search,
   compare, modify, add, delete, modDN or extended operation request
   message (with the exception of any extension that causes a change in
   authentication, authorization, or data confidentiality [RFC 2828],
   such as startTLS) as part of the controls field of the LDAPMessage,
   as defined in [LDAPV3].

   The controlType of the proxied 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.

   The controlValue is either an LDAPString [LDAPv3] containing an
   authzId as defined in section 9 of [AUTH] to use as the authorization
   identity for the request, or an empty value if the anonymous identity
   is to be used.

   The mechanism for determining proxy access rights is specific to the
   server's access control 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 proxied
   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 draft-ietf-ldapbis-iana-
   xx.txt, Section 3.5)]

4. Implementation Considerations

   The interaction of proxied authorization access control 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 proxied 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 proxied authorization identity issued the request
   directly. An example of such a case may be a system with fine-grained

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   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 Proxied Authorization Control method is subject to general LDAP
   security considerations [LDAPV3] [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 proxied
   authorization request is to be honored. "Anonymous" users SHOULD NOT
   be allowed to assume the identity of others.

6. Copyright

   Copyright (C) The Internet Society (date). All Rights Reserved.

   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.

   This document and the information contained herein is provided on an

7. References

   [LDAPV3] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
        Protocol (v3)", RFC 2251, December 1997.

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

    [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 2828] R. Shirey, "Internet Security Glossary", RFC 2828, May

8. Author's Address

   Rob Weltman
   Netscape Communications Corp.
   466 Ellis Street
   Mountain View, CA 94043
   +1 650 937-3194

9. Acknowledgements

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

10. Revision History

10.1 Changes from draft-weltman-ldapv3-proxy-10.txt

   Clarified the interaction of proxy access rights and normal access
   control evaluation.

10.2 Changes from draft-weltman-ldapv3-proxy-09.txt

   Removed description of Control mechanism from Abstract.

   Added description of how this is different from SASL authz to the

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   Reworded description of the value of the control (no semantic
   Added new result code TBD for failure to acquire proxy rights.

   Added references to RFCs 2829 and 2830 in Security section.

10.3 Changes from draft-weltman-ldapv3-proxy-08.txt

   Proxied Authorization Control

   Clarifications:  the control may not be submitted with a startTLS
   request; an empty controlValue implies the anonymous identity; only
   one control may be included with a request.

   Permission to execute as proxy

   Replaced "proxy identity" with "proxied authorization identity".

   Security Considerations

   Added statement that anonymous users should not be allowed to assume
   the identity of others.

10.4 Changes from draft-weltman-ldapv3-proxy-07.txt

   Proxied Authorization Control

   Clarification:  the content of the control is an LDAPString.

10.5 Changes from draft-weltman-ldapv3-proxy-06.txt


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10.6 Changes from draft-weltman-ldapv3-proxy-05.txt

   The control also applies to add and extended operations.

   The control value is an authorization ID, not necessarily a DN.

   Confidentiality concerns are mentioned.

10.7 Changes from draft-weltman-ldapv3-proxy-04.txt

   The control does not apply to bind, unbind, or abandon operations.

   The proxy DN is represented as a string in the control, rather than
   embedded in a sequence.

   Support for the control is published in the supportedControl
   attribute of the root DSE, not in supportedExtensions.

   The security section mentions confidentiality issues with exposing an
   additional identity.

10.8 Changes from draft-weltman-ldapv3-proxy-03.txt


10.9 Changes from draft-weltman-ldapv3-proxy-02.txt

   The Control is now called Proxied Authorization Control, rather than
   Proxied Authentication Control, to reflect that no authentication
   occurs as a consequence of processing the Control.

   Rather than containing an LDAPDN as the Control value, the Control
   contains a Sequence (which contains an LDAPDN). This is to provide
   for future extensions.

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