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Network Working Group R. Weltman
Request for Comments: 3829 America Online
Category: Informational M. Smith
Pearl Crescent, LLC
M. Wahl
July 2004
Lightweight Directory Access Protocol (LDAP)
Authorization Identity Request and Response Controls
Status 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 2004 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 has been registered as an LDAP Protocol Mechanism [IANALDAP]. 8. References 8.1. 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 2004 9. 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 USA Weltman, et al. Informational [Page 5]
RFC 3829 Authorization Identity Bind Control July 2004 10. Full Copyright Statement Copyright (C) The Internet Society (2004). 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. 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 in BCP 78 and BCP 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 at http://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]