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Network Working Group                                         R. WeltmanRequest for Comments: 4370                                  Yahoo!, Inc.Category: Standards Track                                  February 2006Lightweight Directory Access Protocol (LDAP)Proxied Authorization ControlStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).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 under 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 under   the current authorization identity associated with the connection.   This document defines support for proxy authorization using the   Control mechanism [RFC2251].  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 authorization identity on a per-operation basis, benefiting   clients that need to perform operations efficiently 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].Weltman                     Standards Track                     [Page 1]

RFC 4370           LDAP Proxied Authorization Control      February 20062.  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 [RFC2252] of a server's root   DSA-specific Entry (DSE).3.  Proxy Authorization Control   A single Proxy Authorization Control may be included in any search,   compare, modify, add, delete, or modify Distinguished Name (DN) or   extended operation request message.  The exception is any extension   that causes a change in authentication, authorization, or data   confidentiality [RFC2829], such as Start TLS [LDAPTLS] as part of the   controls field of the LDAPMessage, as defined in [RFC2251].   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 SHALL either contain an authzId   [AUTH] representing the authorization identity for the request or be   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 123 is returned.4.  Implementation Considerations   One possible interaction of proxy authorization and normal access   control is illustrated here.  During evaluation of a search request,   an entry that would have been returned for the search (if submitted   by the proxy authorization identity directly) may not be returned ifWeltman                     Standards Track                     [Page 2]

RFC 4370           LDAP Proxied Authorization Control      February 2006   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 that does imply   such rights.  This means that fewer results, or no results, may be   returned than would be if 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 [RFC2251] [AUTH] [LDAPTLS].  The control may   be passed over a secure channel 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 that requires 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 has been registered as an LDAP Protocol   Mechanism [RFC3383].   A result code (123) has been assigned by the IANA for the case where   the server does not execute a request using the proxy authorization   identity.7.  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.Weltman                     Standards Track                     [Page 3]

RFC 4370           LDAP Proxied Authorization Control      February 20068.  Normative References   [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [LDAPV3]   Hodges, J. and R. Morgan, "Lightweight Directory Access              Protocol (v3): Technical Specification",RFC 3377,              September 2002.   [SASL]     Myers, J., "Simple Authentication and Security Layer              (SASL)",RFC 2222, October 1997.   [AUTH]     Wahl, M., Alvestrand, H., Hodges, J., and R. Morgan,              "Authentication Methods for LDAP",RFC 2829, May 2000.   [LDAPTLS]  Hodges, J., Morgan, R., and M. Wahl, "Lightweight              Directory Access Protocol (v3): Extension for Transport              Layer Security",RFC 2830, May 2000.   [RFC2251]  Wahl, M., Howes, T., and S. Kille, "Lightweight Directory              Access Protocol (v3)",RFC 2251, December 1997.   [RFC2252]  Wahl, M., Coulbeck, A., Howes, T., and S. Kille,              "Lightweight Directory Access Protocol (v3): Attribute              Syntax Definitions",RFC 2252, December 1997.   [RFC2829]  Wahl, M., Alvestrand, H., Hodges, J., and R. Morgan,              "Authentication Methods for LDAP",RFC 2829, May 2000.   [RFC3383]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)              Considerations for the Lightweight Directory Access              Protocol (LDAP)",BCP 64,RFC 3383, September 2002.Author's Address   Rob Weltman   Yahoo!, Inc.   701 First Avenue   Sunnyvale, CA 94089   USA   Phone: +1 408 349-5504   EMail: robw@worldspot.comWeltman                     Standards Track                     [Page 4]

RFC 4370           LDAP Proxied Authorization Control      February 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   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   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Weltman                     Standards Track                     [Page 5]