INTERNET-DRAFT S. Legg
draft-legg-ldap-acm-admin-03.txt Adacel Technologies
Intended Category: Standards Track June 16, 2004
Lightweight Directory Access Protocol (LDAP):
Access Control Administration
Copyright (C) The Internet Society (2004). All Rights Reserved.
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Abstract
This document adapts the X.500 directory administrative model, as it
pertains to access control administration, for use by the Lightweight
Directory Access Protocol. The administrative model partitions the
Directory Information Tree for various aspects of directory data
administration, e.g., subschema, access control and collective
attributes. This document provides the particular definitions that
support access control administration, but does not define a
particular access control scheme.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Access Control Administrative Areas. . . . . . . . . . . . . . 3
4. Access Control Scheme Indication . . . . . . . . . . . . . . . 3
5. Access Control Information . . . . . . . . . . . . . . . . . . 4
6. Access Control Subentries. . . . . . . . . . . . . . . . . . . 4
7. Applicable Access Control Information. . . . . . . . . . . . . 5
8. Security Considerations. . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
11.1. Normative References. . . . . . . . . . . . . . . . . . 6
11.2. Informative References. . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This document adapts the X.500 directory administrative model [X501],
as it pertains to access control administration, for use by the
Lightweight Directory Access Protocol (LDAP) [RFC3377].
The administrative model [ADMIN] partitions the Directory Information
Tree (DIT) for various aspects of directory data administration,
e.g., subschema, access control and collective attributes. The parts
of the administrative model that apply to every aspect of directory
data administration are described in [ADMIN]. This document
describes the administrative framework for access control.
An access control scheme describes the means by which access to
directory information, and potentially to access rights themselves,
may be controlled. This document describes the framework for
employing access control schemes but does not define a particular
access control scheme. Two access control schemes known as Basic
Access Control and Simplified Access Control are defined by [BAC].
Other access control schemes may be defined by other documents.
This document is derived from, and duplicates substantial portions
of, Sections 4 and 8 of X.501 [X501].
2. Conventions
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, RFC 2119
[RFC2119].
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Schema definitions are provided using LDAP description formats
[RFC2252]. Note that the LDAP descriptions have been rendered with
additional white-space and line breaks for the sake of readability.
3. Access Control Administrative Areas
The specific administrative area [ADMIN] for access control is termed
an Access Control Specific Area (ACSA). The root of the ACSA is
termed an Access Control Specific Point (ACSP) and is represented in
the DIT by an administrative entry [ADMIN] which includes
accessControlSpecificArea as a value of its administrativeRole
operational attribute [SUBENTRY].
An ACSA MAY be partitioned into subtrees termed inner administrative
areas [ADMIN]. Each such inner area is termed an Access Control
Inner Area (ACIA). The root of the ACIA is termed an Access Control
Inner Point (ACIP) and is represented in the DIT by an administrative
entry which includes accessControlInnerArea as a value of its
administrativeRole operational attribute.
An administrative entry can never be both an ACSP and an ACIP. The
corresponding values can therefore never be present simultaneously in
the administrativeRole attribute.
Each entry necessarily falls within one and only one ACSA. Each such
entry may also fall within one or more ACIAs nested inside the ACSA
containing the entry.
An ACSP or ACIP has zero, one or more subentries that contain Access
Control Information (ACI).
4. Access Control Scheme Indication
The access control scheme (e.g., Basic Access Control [BAC]) in force
in an ACSA is indicated by the accessControlScheme operational
attribute contained in the administrative entry for the relevant
ACSP.
The LDAP description [RFC2252] for the accessControlScheme
operational attribute is:
( 2.5.24.1 NAME 'accessControlScheme'
EQUALITY objectIdentifierMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38
SINGLE-VALUE USAGE directoryOperation )
An access control scheme conforming to the access control framework
described in this document MUST define a distinct OBJECT IDENTIFIER
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value to identify it through the accessControlScheme attribute.
Object Identifier Descriptors for access control scheme identifiers
may be registered with IANA [BCP64].
Only administrative entries for ACSPs are permitted to contain an
accessControlScheme attribute. If the accessControlScheme attribute
is absent from a given ACSP, the access control scheme in force in
the corresponding ACSA, and its effect on operations, results and
errors, is implementation defined.
Any entry or subentry in an ACSA is permitted to contain ACI if and
only if such ACI is permitted by, and consistent with, the access
control scheme identified by the value of the accessControlScheme
attribute of the ACSP.
5. Access Control Information
There are three categories of Access Control Information (ACI):
entry, subentry and prescriptive.
Entry ACI applies to only the entry or subentry in which it appears,
and the contents thereof. Subject to the access control scheme, any
entry or subentry MAY hold entry ACI.
Subentry ACI applies to only the subentries of the administrative
entry in which it appears. Subject to the access control scheme, any
administrative entry, for any aspect of administration, MAY hold
subentry ACI.
Prescriptive ACI applies to all the entries within a subtree or
subtree refinement of an administrative area (either an ACSA or an
ACIA), as defined by the subtreeSpecification attribute of the
subentry in which it appears. Prescriptive ACI is only permitted in
subentries of an ACSP or ACIP. Prescriptive ACI in the subentries of
a particular administrative point never applies to the same or any
other subentry of that administrative point, but does apply to the
subentries of subordinate administrative points, where those
subentries are within the subtree or subtree refinement.
6. Access Control Subentries
Each subentry which contains prescriptive ACI MUST have
accessControlSubentry as a value of its objectClass attribute. Such
a subentry is called an access control subentry.
The LDAP description [RFC2252] for the accessControlSubentry
auxiliary object class is:
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( 2.5.17.1 NAME 'accessControlSubentry' AUXILIARY )
A subentry of this object class MUST contain at least one
prescriptive ACI attribute of a type consistent with the value of the
accessControlScheme attribute of the corresponding ACSP.
The subtree or subtree refinement for an access control subentry is
termed a Directory Access Control Domain (DACD). A DACD can contain
zero entries, and can encompass entries that have not yet been added
to the DIT, but does not extend beyond the scope of the ACSA or ACIA
with which it is associated.
Since a subtreeSpecification may define a subtree refinement, DACDs
within a given ACSA may arbitrarily overlap.
7. Applicable Access Control Information
Although particular items of ACI may specify attributes or values as
the protected items, ACI is logically associated with entries.
The ACI that is considered in access control decisions regarding an
entry includes:
(1) Entry ACI from that particular entry.
(2) Prescriptive ACI from access control subentries whose DACDs
contain the entry. Each of these access control subentries is
necessarily either a subordinate of the ACSP for the ACSA
containing the entry, or a subordinate of the ACIP for an ACIA
that contains the entry.
The ACI that is considered in access control decisions regarding a
subentry includes:
(1) Entry ACI from that particular subentry.
(2) Prescriptive ACI from access control subentries whose DACDs
contain the subentry, excluding those belonging to the same
administrative point as the subentry for which the decision is
being made.
(3) Subentry ACI from the administrative point associated with the
subentry.
8. Security Considerations
This document defines a framework for employing an access control
scheme, i.e., the means by which access to directory information and
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potentially to access rights themselves may be controlled, but does
not itself define any particular access control scheme. The degree
of protection provided, and any security risks, are determined by the
provisions of the access control schemes (defined elsewhere) making
use of this framework.
Security considerations that apply to directory administration in
general [ADMIN] also apply to access control administration.
9. Acknowledgements
This document is derived from, and duplicates substantial portions
of, Sections 4 and 8 of X.501 [X501].
10. IANA Considerations
The Internet Assigned Numbers Authority (IANA) is requested to update
the LDAP descriptors registry [BCP64] as indicated by the following
templates:
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): accessControlScheme
Object Identifier: 2.5.24.1
Person & email address to contact for further information:
Steven Legg <steven.legg@adacel.com.au>
Usage: attribute type
Specification: RFC XXXX
Author/Change Controller: IESG
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): accessControlSubentry
Object Identifier: 2.5.17.1
Person & email address to contact for further information:
Steven Legg <steven.legg@adacel.com.au>
Usage: object class
Specification: RFC XXXX
Author/Change Controller: IESG
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2252] Wahl, M., Coulbeck, A., Howes, T. and S. Kille,
"Lightweight Directory Access Protocol (v3): Attribute
Syntax Definitions", RFC 2252, December 1997.
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[RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377,
September 2002.
[BCP64] Zeilenga, K., "Internet Assigned Numbers Authority (IANA
Considerations for the Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 3383, September 2002.
[SUBENTRY] Zeilenga, K. and S. Legg, "Subentries in the Lightweight
Directory Access Protocol (LDAP)", RFC 3672, December
2003.
[ADMIN] Legg, S., "Lightweight Directory Access Protocol (LDAP):
Directory Administrative Model",
draft-legg-ldap-admin-xx.txt, a work in progress, June
2004.
11.2. Informative References
[COLLECT] Zeilenga, K., "Collective Attributes in the Lightweight
Directory Access Protocol (LDAP)", RFC 3671, December
2003.
[BAC] Legg, S., "Lightweight Directory Access Protocol (LDAP):
Basic and Simplified Access Control",
draft-legg-ldap-acm-bac-xx.txt, a work in progress, June
2004.
[X501] ITU-T Recommendation X.501 (02/01) | ISO/IEC 9594-2:2001,
Information technology - Open Systems Interconnection -
The Directory: Models
Author's Address
Steven Legg
Adacel Technologies Ltd.
250 Bay Street
Brighton, Victoria 3186
AUSTRALIA
Phone: +61 3 8530 7710
Fax: +61 3 8530 7888
EMail: steven.legg@adacel.com.au
Full Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
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except as set forth therein, the authors retain all their rights.
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Changes in Draft 01
Section 4 has been extracted to become a separate Internet draft,
draft-legg-ldap-admin-00.txt. The subsections of Section 5 have
become the new Sections 3 to 7. Editorial changes have been made to
accommodate this split. No technical changes have been introduced.
Changes in Draft 02
RFC 3377 replaces RFC 2251 as the reference for LDAP.
An IANA Considerations section has been added.
Changes in Draft 03
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The document has been reformatted in line with current practice.
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