





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                                25 October 2003


                        The LDAP Assertion Control
                   <draft-zeilenga-ldap-assert-01.txt>


Status of this Memo

  This document is an Internet-Draft and is in full conformance with all
  provisions of Section 10 of RFC2026.

  This document is intended to be, after appropriate review and
  revision, submitted to the IESG for consideration as a Standard Track
  document.  Distribution of this memo is unlimited.  Technical
  discussion of this document will take place on the IETF LDAP
  Extensions mailing list <ldapext@ietf.org>.  Please send editorial
  comments directly to the author <Kurt@OpenLDAP.org>.

  Internet-Drafts are working documents of the Internet Engineering Task
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  Copyright (C) The Internet Society (2003).  All Rights Reserved.

  Please see the Full Copyright section near the end of this document
  for more information.


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" and "test and clear" and other conditional operations.




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1.  Overview

  This document defines the Lightweight Directory Access Protocol (LDAP)
  [RFC3377] assertion control.  The assertion control allows the client
  to specify a condition which must be true for the operation to be
  processed normally.  Otherwise the operation fails.

  The control can be used with the Modify operation [RFC2251] to perform
  atomic "test and set" and "test and clear" operations as the asserted
  condition is evaluated as an integral part the operation.  The control
  may be attached to other update operations to support conditional add,
  delete, and renaming of objects.

  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 matching 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 in
  Section 5.1 of [RFC2251].

  DSA stands for Directory System Agent (or server).
  DSE stands for DSA-specific Entry.

  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
  "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
  document are to be interpreted as described in BCP 14 [RFC2119].


3.  The Assertion Control

  The assertion control is an LDAP Control [RFC2251] whose controlType
  is IANA-ASSIGNED-OID and controlValue is a BER-encoded Filter
  [RFC2251, 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 [RFC2251] including Add, Compare, Delete, Modify, ModifyDN
  (rename), and Search.  It is inappropriate for Abandon, Bind nor
  Unbind operations.  It is also inappropriate for the Start TLS
  [RFC2830] operation.



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  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 (IANA-ASSIGNED-CODE)
  resultCode is returned and no further processing is performed.

  For Add, Compare, and ModifyDN the target is indicated by the entry
  field in the request.  For Modify, the target is indicated by the
  object field.  For Delete, the target is indicated by the DelRequest
  type.  For the Compare operation 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 operation, the target is indicated by the baseObject field
  and the evaluation is done after "finding" but before "searching"
  [RFC2251].  Hence, if the evaluation fails, no entries or
  continuations references are returned.

  Servers implementing this technical specification SHOULD publish the
  object identifier IANA-ASSIGNED-OID as a value of the
  'supportedControl' attribute [RFC2252] 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 so, this information should be
  appropriately protected.

  As with any general assertion mechanism, the mechanism can be used to
  determine directory content.  Hence, the mechanism SHOULD be subject
  to appropriate access controls.

  Some assertions may be very complex, requiring significant time and
  resources to evaluate.  Hence, the mechanism SHOULD be subject to
  appropriate administrative controls.

  All security considerations for the base operations [RFC2251] to which
  this control is attached to apply, as do general LDAP security
  considerations [RFC3377].



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5.  IANA Considerations

5.1.  Object Identifier

  It is requested that IANA assign upon Standards Action an LDAP Object
  Identifier [RFC3383] 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 XXXX
      Author/Change Controller: IESG
      Comments:
          Identifies the LDAP Assertion Control

5.2  LDAP Protocol Mechanism

  Registration of this protocol mechanism [RFC3383] is requested.

      Subject: Request for LDAP Protocol Mechanism Registration
      Object Identifier: IANA-ASSIGNED-OID
      Description: Assertion Control
      Person & email address to contact for further information:
          Kurt Zeilenga <kurt@openldap.org>
      Usage: Control
      Specification: RFC XXXX
      Author/Change Controller: IESG
      Comments: none


5.3  LDAP Result Code

  Assignment of an LDAP Result Code [RFC3383] called 'assertionFailed'
  is requested.

      Subject: LDAP Result Code Registration
      Person & email address to contact for further information:
          Kurt Zeilenga <kurt@OpenLDAP.org>
      Result Code Name: assertionFailed
      Specification: RFC XXXX
      Author/Change Controller: IESG
      Comments:  none


6.  Acknowledgments

  The assertion control concept is attributed to Morteza Ansari.



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7.  Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation
  <Kurt@OpenLDAP.org>


8. Normative References

  [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14 (also RFC 2119), March 1997.

  [RFC2251]     Wahl, M., T. Howes and S. Kille, "Lightweight Directory
                Access Protocol (v3)", RFC 2251, December 1997.

  [RFC2252]     Wahl, M., A. Coulbeck, T. Howes, and S. Kille,
                "Lightweight Directory Access Protocol (v3):  Attribute
                Syntax Definitions", RFC 2252, December 1997.

  [RFC3377]     Hodges, J. and R. Morgan, "Lightweight Directory Access
                Protocol (v3): Technical Specification", RFC 3377,
                September 2002.


9. Informative References

  [RFC3383]     Zeilenga, K., "IANA Considerations for LDAP", BCP 64
                (also RFC 3383), September 2002.



Intellectual Property Rights

  The IETF takes no position regarding the validity or scope of any
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  obtain a general license or permission for the use of such proprietary
  rights by implementors or users of this specification can be obtained
  from the IETF Secretariat.

  The IETF invites any interested party to bring to its attention any



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  copyrights, patents or patent applications, or other proprietary
  rights which may cover technology that may be required to practice
  this standard.  Please address the information to the IETF Executive
  Director.



Full Copyright

  Copyright (C) The Internet Society (2003). All Rights Reserved.

  This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implmentation may be prepared, copied, published and
  distributed, in whole or in part, without restriction of any kind,
  provided that the above copyright notice and this paragraph are
  included on all such copies and derivative works.  However, this
  document itself may not be modified in any way, such as by removing
  the copyright notice or references to the Internet Society or other
  Internet organizations, except as needed for the  purpose of
  developing Internet standards in which case the procedures for
  copyrights defined in the Internet Standards process must be followed,
  or as required to translate it into languages other than English.




























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