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INTERNET-DRAFT                                               Rob Weltman
Intended Category: Informational                              Mark Smith
                                           Netscape Communications Corp.
                                                               Mark Wahl
                                                  Sun Microsystems, Inc.
                                                              April 2003


       LDAP Authorization Identity Request and Response Controls
               draft-weltman-ldapv3-auth-response-09.txt


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
   may also distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


Abstract

   This document extends the Lightweight Directory Access Protocol
   (LDAP) [RFC3377] bind [LDAPPROT] operation with a mechanism for
   requesting and returning the authorization identity it establishes.
   Specifically, this document defines the Authorization Identity
   Request and Response controls for use with the Bind operation.


1. Introduction

   This document defines support for the Authorization Identity Request
   Control and the Authorization Identity Response Control for
   requesting and returning the authorization established in a bind
   operation. The Authorization Identity Request Control may be
   submitted by a client in a bind request if authenticating with
   version 3 of the Lightweight Directory Access Protocol (LDAP)
   protocol [LDAPv3]. In the LDAP server's bind response, it may then
   include an Authorization Identity Response Control. The response
   control contains the identity assumed by the client. This is useful
   when there is a mapping step or other indirection during the bind, so

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   that the client can be told what LDAP identity was granted. Client
   authentication with certificates is the primary situation where this
   applies. Also, some Simple Authentication and Security Layer (SASL)
   authentication mechanisms may not involve the client explicitly
   providing a DN, or may result in an authorization identity which is
   different from the authentication identity provided by the client
   [AUTH].

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


2. Publishing support for the Authorization Identity Request Control
   and the Authorization Identity Response Control

   Support for the Authorization Identity Request Control and the
   Authorization Identity Response Control is indicated by the presence
   of the Object Identifiers (OIDs) 2.16.840.1.113730.3.4.16 and
   2.16.840.1.113730.3.4.15, respectively, in the supportedControl
   attribute [LDAPATTRS] of a server's root DSE.


3. Authorization Identity Request Control


   This control MAY be included in any bind request which specifies
   protocol version 3, as part of the controls field of the LDAPMessage
   as defined in [LDAPPROT]. In a multi-step bind operation, the client
   MUST provide the control with each bind request.

   The controlType is "2.16.840.1.113730.3.4.16" and the controlValue is
   absent.


4. Authorization Identity Response Control

   This control MAY be included in any final bind response where the
   first bind request of the bind operation included an Authorization
   Identity Request Control as part of the controls field of the
   LDAPMessage as defined in [LDAPPROT].

   The controlType is "2.16.840.1.113730.3.4.15". If the bind request
   succeeded and resulted in an identity (not anonymous), the
   controlValue contains the authorization identity (authzId), as
   defined in [AUTH] section 9, granted to the requestor. If the bind
   request resulted in an anonymous association, the controlValue field
   is a string of zero length. If the bind request resulted in more than
   one authzId, the primary authzId is returned in the controlValue
   field.

   The control is only included in a bind response if the resultCode for
   the bind operation is success.

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   If the server requires confidentiality protections to be in place
   prior to use of this control (see Security Considerations), the
   server reports failure to have adequate confidentiality protections
   in place by returning the confidentialityRequired result code.

   If the client has insufficient access rights to the requested
   authorization information, the server reports this by returning the
   insufficientAccessRights result code.

   Identities presented by a client as part of the authentication
   process may be mapped by the server to one or more authorization
   identities. The bind response control can be used to retrieve the
   primary authzId.

   For example, during client authentication with certificates [AUTH], a
   client may possess more than one certificate and not be able to
   determine which one was ultimately selected for authentication to the
   server. The subject DN field in the selected certificate may not
   correspond exactly to a DN in the directory, but rather have gone
   through a mapping process controlled by the server. On completing the
   certificate-based authentication, the client may issue a SASL [SASL]
   bind request, specifying the EXTERNAL mechanism and including an
   Authorization Identity Request Control. The bind response MAY include
   an Authorization Identity Response Control indicating the DN in the
   server's DIT which the certificate was mapped to.


5. Alternative Approach with Extended Operation

   The LDAP "Who am I?" [AUTHZID] extended operation provides a
   mechanism to query the authorization identity associated with a bound
   connection. Using an extended operation as opposed to a bind response
   control allows a client to learn the authorization identity after the
   bind has has established integrity and data confidentiality
   protections. The disadvantages of the extended operation approach are
   coordination issues between "Who am I?" requests, bind requests, and
   other requests, and that an extra operation is required to learn the
   authorization identity. For multithreaded or high bandwidth server
   application environments, the bind response approach may be
   preferable.

6. Security Considerations

   The Authorization Identity Request and Response Controls are subject
   to standard LDAP security considerations. The controls may be passed
   over a secure as well as over an insecure channel. They are not
   protected by security layers negotiated by the bind operation.

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


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   deployments, a security layer should be established prior to issuing
   a bind request with an Authorization Identity Request Control.


7. IANA Considerations

   The OIDs 2.16.840.1.113730.3.4.16 and 2.16.840.1.113730.3.4.15 are
   reserved for the Authorization Identity Request and Response
   Controls, respectively. The Authorization Identity Request Control is
   to be registered as an LDAP Protocol Mechanism [IANALDAP].


8. Copyright

   Copyright (C) The Internet Society (2003). 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
   English.

   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
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


9. References

   [LDAPV3] Hodges, J. and R. Morgan, "Lightweight Directory Access
        Protocol (v3): Technical Specification", RFC 3377, September
        2002.

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

   [RFCKeyWords] Bradner, Scott, "Key Words for use in RFCs to Indicate
        Requirement Levels", draft-bradner-key-words-03.txt, January
        1997.

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

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

   [AUTHZID] K. Zeilenga, "LDAP 'Who am I?' Operation", draft-zeilenga-
        ldap-authzid-03.txt, April 2002

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

   [IANALDAP] J. Hodges, R. Morgan, "Lightweight Directory Access
        Protocol (v3): Technical Specification", RFC 3377, September
        2002



10. Author's Addresses

   Rob Weltman
   Netscape Communications Corp.
   360 W. Caribbean Drive
   Sunnyvale, CA 94089
   USA
   +1 650 937-3194
   rweltman@netscape.com

   Mark Smith
   Netscape Communications Corp.
   360 W. Caribbean Drive
   Sunnyvale, CA 94089
   USA
   +1 650 937-3477
   mcs@netscape.com

   Mark Wahl
   Sun Microsystems, Inc.
   911 Capital of Texas Hwy, Suite 4140
   Austin, TX 78759
   USA
   +1 512 231 7224
   Mark.Wahl@sun.com









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