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
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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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