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Network Working Group                                         R. WeltmanRequest for Comments: 3829                                America OnlineCategory: Informational                                         M. Smith                                                     Pearl Crescent, LLC                                                                 M. Wahl                                                               July 2004Lightweight Directory Access Protocol (LDAP)Authorization Identity Request and Response ControlsStatus of this Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2004).Abstract   This document extends the Lightweight Directory Access Protocol   (LDAP) bind 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   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].Weltman, et al.              Informational                      [Page 1]

RFC 3829          Authorization Identity Bind Control          July 2004   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 DSA-specific Entry (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.   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.Weltman, et al.              Informational                      [Page 2]

RFC 3829          Authorization Identity Bind Control          July 2004   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 may 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.  Upon 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 Directory Information Tree (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 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   deployments, a security layer should be established prior to issuing   a bind request with an Authorization Identity Request Control.Weltman, et al.              Informational                      [Page 3]

RFC 3829          Authorization Identity Bind Control          July 20047.  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   has been registered as an LDAP Protocol Mechanism [IANALDAP].8.  References8.1.  Normative References   [LDAPv3]      Hodges, J. and R. Morgan, "Lightweight Directory Access                 Protocol (v3): Technical Specification",RFC 3377,                 September 2002.   [LDAPPROT]    Wahl, M., Howes, T. and S. Kille, "Lightweight                 Directory Access Protocol (v3)",RFC 2251, December                 1997.   [RFCKeyWords] Bradner, S., "Key Words for use in RFCs to Indicate                 Requirement Levels",BCP 14,RFC 2119, March 1997.   [AUTH]        Wahl, M., Alvestrand, H., Hodges, J. and R. Morgan,                 "Authentication Methods for LDAP",RFC 2829, May 2000.   [SASL]        Myers, J., "Simple Authentication and Security Layer                 (SASL)",RFC 2222, October 1997.   [LDAPATTRS]   Wahl, M., Coulbeck, A., Howes, T. and S. Kille,                 "Lightweight Directory Access Protocol (v3): Attribute                 Syntax Definitions",RFC 2252, December 1997.   [IANALDAP]    Hodges, J. and R. Morgan, "Lightweight Directory Access                 Protocol (v3): Technical Specification",RFC 3377,                 September 2002.8.2.  Informative References   [AUTHZID]     Zeilenga, K.,"LDAP 'Who am I?' Operation", Work in                 Progress, April 2002.Weltman, et al.              Informational                      [Page 4]

RFC 3829          Authorization Identity Bind Control          July 20049.  Author's Addresses   Rob Weltman   America Online   360 W. Caribbean Drive   Sunnyvale, CA 94089   USA   Phone: +1 650 937-3194   EMail: robw@worldspot.com   Mark Smith   Pearl Crescent, LLC   447 Marlpool Drive   Saline, MI 48176   USA   Phone: +1 734 944-2856   EMail: mcs@pearlcrescent.com   Mark Wahl   PO Box 90626   Austin, TX 78709-0626   USAWeltman, et al.              Informational                      [Page 5]

RFC 3829          Authorization Identity Bind Control          July 200410.  Full Copyright Statement   Copyright (C) The Internet Society (2004).  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 currently provided by the   Internet Society.Weltman, et al.              Informational                      [Page 6]