Lightweight Directory Access Protocol (LDAP) Assertion Control
draft-zeilenga-ldap-assert-05

INTERNET-DRAFT                                   Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                            10 February 2005

                        The LDAP Assertion Control
                   <draft-zeilenga-ldap-assert-05.txt>

Status of this Memo

  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>.

  By submitting this Internet-Draft, I accept the provisions of Section
  4 of RFC 3667.  By submitting this Internet-Draft, I certify that any
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  Copyright (C) The Internet Society (2005).  All Rights Reserved.

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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.

1.  Overview

  This document defines the Lightweight Directory Access Protocol (LDAP)
  [Roadmap] 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.  For instance, the
  control can be used with the Modify operation [Protocol] 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 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 5.2 of [Protocol].

  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

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  The assertion control is an LDAP Control [Protocol] whose controlType
  is IANA-ASSIGNED-OID and 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 [Protocol] including Add, Compare, Delete, Modify, ModifyDN
  (rename), and Search.  It is inappropriate for Abandon, Bind nor
  Unbind, and Start TLS operations.

  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"
  [Protocol].  Hence, no entries or continuations references are
  returned if the assertion fails.

  Servers implementing this technical specification SHOULD publish the
  object identifier IANA-ASSIGNED-OID as a value of the
  'supportedControl' attribute [Models] 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

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  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.

  Security considerations for the base operations [Protocol] extended by
  this control, as well as general LDAP security considerations
  [Roadmap], generally apply to implementation and use of this
  extension.

5.  IANA Considerations

5.1.  Object Identifier

  It is requested that IANA assign upon Standards Action an LDAP Object
  Identifier [BCP64bis] 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 [BCP64bis] 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 [BCP64bis] called 'assertionFailed'
  is requested.

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      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.

7.  Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation

  Email: Kurt@OpenLDAP.org

8. References

  [[Note to the RFC Editor: please replace the citation tags used in
  referencing Internet-Drafts with tags of the form RFCnnnn where
  possible.]]

8.1. Normative References

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

  [Roadmap]     Zeilenga, K. (editor), "LDAP: Technical Specification
                Road Map", draft-ietf-ldapbis-roadmap-xx.txt, a work in
                progress.

  [Protocol]    Sermersheim, J. (editor), "LDAP: The Protocol",
                draft-ietf-ldapbis-protocol-xx.txt, a work in progress.

  [Models]      Zeilenga, K. (editor), "LDAP: Directory Information
                Models", draft-ietf-ldapbis-models-xx.txt, a work in
                progress.

8.2. Informative References

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  [BCP64bis]    Zeilenga, K., "IANA Considerations for LDAP",
                draft-ietf-ldapbis-bcp64-xx.txt, a work in progress.

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