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Network Working Group                                        K. ZeilengaRequest for Comments: 4528                           OpenLDAP FoundationCategory: Standards Track                                      June 2006Lightweight Directory Access Protocol (LDAP)Assertion 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) Assertion Control, which allows a client to specify that a   directory operation should only be processed if an assertion applied   to the target entry of the operation is true.  It can be used to   construct "test and set", "test and clear", and other conditional   operations.Table of Contents1. Overview ........................................................22. Terminology .....................................................23. The Assertion Control ...........................................24. Security Considerations .........................................35. IANA Considerations .............................................45.1. Object Identifier ..........................................45.2. LDAP Protocol Mechanism ....................................45.3. LDAP Result Code ...........................................46. Acknowledgements ................................................57. References ......................................................57.1. Normative References .......................................57.2. Informative References .....................................5Zeilenga                    Standards Track                     [Page 1]

RFC 4528                 LDAP Assertion Control                June 20061.  Overview   This document defines the Lightweight Directory Access Protocol   (LDAP) [RFC4510] assertion control.  The assertion control allows the   client to specify a condition that must be true for the operation to   be processed normally.  Otherwise, the operation is not performed.   For instance, the control can be used with the Modify operation   [RFC4511] to perform atomic "test and set" and "test and clear"   operations.   The control may be attached to any update operation to support   conditional addition, deletion, modification, and renaming of the   target object.  The asserted condition is evaluated as an integral   part the operation.   The control may also be used with the search operation.  Here, the   assertion is applied to the base object of the search before   searching for objects that match the search scope and filter.   The control may also be used with the compare operation.  Here, it   extends the compare operation to allow a more complex assertion.2. Terminology   Protocol elements are described using ASN.1 [X.680] with implicit   tags.  The term "BER-encoded" means the element is to be encoded   using the Basic Encoding Rules [X.690] under the restrictions   detailed inSection 5.1 of [RFC4511].   DSA stands for Directory System Agent (or server).   DSE stands for DSA-specific Entry.   In this document, the key words "MUST", "MUST NOT", "REQUIRED",   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",   and "OPTIONAL" are to be interpreted as described inBCP 14   [RFC2119].3.  The Assertion Control   The assertion control is an LDAP Control [RFC4511] whose controlType   is 1.3.6.1.1.12 and whose controlValue is a BER-encoded Filter   [Protocol,Section 4.5.1].  The criticality may be TRUE or FALSE.   There is no corresponding response control.   The control is appropriate for both LDAP interrogation and update   operations [RFC4511], including Add, Compare, Delete, Modify,   ModifyDN (rename), and Search.  It is inappropriate for Abandon,   Bind, Unbind, and StartTLS operations.Zeilenga                    Standards Track                     [Page 2]

RFC 4528                 LDAP Assertion Control                June 2006   When the control is attached to an LDAP request, the processing of   the request is conditional on the evaluation of the Filter as applied   against the target of the operation.  If the Filter evaluates to   TRUE, then the request is processed normally.  If the Filter   evaluates to FALSE or Undefined, then assertionFailed (122)   resultCode is returned, and no further processing is performed.   For Add, Compare, and ModifyDN operations, the target is indicated by   the entry field in the request.  For Modify operations, the target is   indicated by the object field.  For Delete operations, the target is   indicated by the DelRequest type.  For Compare operations and all   update operations, the evaluation of the assertion MUST be performed   as an integral part of the operation.  That is, the evaluation of the   assertion and the normal processing of the operation SHALL be done as   one atomic action.   For Search operations, the target is indicated by the baseObject   field, and the evaluation is done after "finding" but before   "searching" [RFC4511].  Hence, no entries or continuations references   are returned if the assertion fails.   Servers implementing this technical specification SHOULD publish the   object identifier 1.3.6.1.1.12 as a value of the 'supportedControl'   attribute [RFC4512] in their root DSE.  A server MAY choose to   advertise this extension only when the client is authorized to use   it.   Other documents may specify how this control applies to other LDAP   operations.  In doing so, they must state how the target entry is   determined.4.  Security Considerations   The filter may, like other components of the request, contain   sensitive information.  When it does, this information should be   appropriately protected.   As with any general assertion mechanism, the mechanism can be used to   determine directory content.  Hence, this mechanism SHOULD be subject   to appropriate access controls.   Some assertions may be very complex, requiring significant time and   resources to evaluate.  Hence, this mechanism SHOULD be subject to   appropriate administrative controls.Zeilenga                    Standards Track                     [Page 3]

RFC 4528                 LDAP Assertion Control                June 2006   Security considerations for the base operations [RFC4511] extended by   this control, as well as general LDAP security considerations   [RFC4510], generally apply to implementation and use of this   extension.5.  IANA Considerations5.1.  Object Identifier   The IANA has assigned an LDAP Object Identifier [RFC4520] to identify   the LDAP Assertion Control defined in this document.       Subject: Request for LDAP Object Identifier Registration       Person & email address to contact for further information:           Kurt Zeilenga <kurt@OpenLDAP.org>       Specification:RFC 4528       Author/Change Controller: IESG       Comments:           Identifies the LDAP Assertion Control5.2.  LDAP Protocol Mechanism   Registration of this protocol mechanism [RFC4520] is requested.       Subject: Request for LDAP Protocol Mechanism Registration       Object Identifier: 1.3.6.1.1.12       Description: Assertion Control       Person & email address to contact for further information:           Kurt Zeilenga <kurt@openldap.org>       Usage: Control       Specification:RFC 4528       Author/Change Controller: IESG       Comments: none5.3.  LDAP Result Code   The IANA has assigned an LDAP Result Code [RFC4520] called   'assertionFailed' (122).       Subject: LDAP Result Code Registration       Person & email address to contact for further information:           Kurt Zeilenga <kurt@OpenLDAP.org>       Result Code Name: assertionFailed       Specification:RFC 4528       Author/Change Controller: IESG       Comments:  noneZeilenga                    Standards Track                     [Page 4]

RFC 4528                 LDAP Assertion Control                June 20066.  Acknowledgements   The assertion control concept is attributed to Morteza Ansari.7.  References7.1.  Normative References   [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate                 Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC4510]     Zeilenga, K., Ed., "Lightweight Directory Access                 Protocol (LDAP): Technical Specification Road Map",RFC4510, June 2006.   [RFC4511]     Sermersheim, J., Ed., "Lightweight Directory Access                 Protocol (LDAP): The Protocol",RFC 4511, June 2006.   [RFC4512]     Zeilenga, K., "Lightweight Directory Access Protocol                 (LDAP): Directory Information Models",RFC 4512, June                 2006.   [X.680]       International Telecommunication Union -                 Telecommunication Standardization Sector, "Abstract                 Syntax Notation One (ASN.1) - Specification of Basic                 Notation", X.680(2002) (also ISO/IEC 8824-1:2002).   [X.690]       International Telecommunication Union -                 Telecommunication Standardization Sector,                 "Specification of ASN.1 encoding rules: Basic Encoding                 Rules (BER), Canonical Encoding Rules (CER), and                 Distinguished Encoding Rules (DER)", X.690(2002) (also                 ISO/IEC 8825-1:2002).7.2.  Informative References   [RFC4520]     Zeilenga, K., "Internet Assigned Numbers Authority                 (IANA) Considerations for the Lightweight Directory                 Access Protocol (LDAP)",BCP 64,RFC 4520, June 2006.Author's Address   Kurt D. Zeilenga   OpenLDAP Foundation   EMail: Kurt@OpenLDAP.orgZeilenga                    Standards Track                     [Page 5]

RFC 4528                 LDAP Assertion Control                June 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).Zeilenga                    Standards Track                     [Page 6]