Network Working Group K. Zeilenga Request for Comments: 4528 OpenLDAP Foundation Category: Standards Track June 2006
Lightweight Directory Access Protocol (LDAP) Assertion Control
Status 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.
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.
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 [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 in BCP 14 [RFC2119].
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.
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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.
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.
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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.
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 Control
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: none
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: none
[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.org
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RFC 4528 LDAP Assertion Control June 2006
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