

INTERNET-DRAFT                                               Rob Weltman 
Intended Category: Standards Track                          Yahoo!, Inc. 
                                                               June 2005 
    
                   LDAP Proxied Authorization Control 
                   draft-weltman-ldapv3-proxy-13.txt 
 
 
Status of this Memo 
 
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   all provisions of Section 10 of RFC2026. 
    
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Abstract 
    
   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 
   users. 
    
   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" 
   used in this document  are  to be interpreted as described in 
   [KEYWORDS]. 
    
    
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 
   "2.16.840.1.113730.3.4.18". 
    
   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 
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 
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   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, 
        1997. 
    
   [LDAPV3] Hodges, J. and R. Morgan, "Lightweight Directory Access 
        Protocol (v3): Technical Specification", RFC 3377, September 
        2002. 
     
   [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 
   USA 
   +1 408 349-5504 
   robw@worldspot.com 
    
    
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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