openldap/doc/drafts/draft-zeilenga-ldap-subentry-xx.txt
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INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track OpenLDAP Foundation
Date: 17 May 2002 Steven Legg
Expires in six months Adacel Technologies
Subentries in LDAP
<draft-zeilenga-ldap-subentry-05.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 RFC Editor as a Standard Track document.
Distribution of this memo is unlimited. Technical discussion of this
document will take place on the IETF LDAP Extension Working Group
mailing list <ietf-ldapext@netscape.com>. Please send editorial
comments directly to the author <Kurt@OpenLDAP.org>.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as ``work in progress.''
The list of current Internet-Drafts can be accessed at
<http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
Internet-Draft Shadow Directories can be accessed at
<http://www.ietf.org/shadow.html>.
Copyright 2002, The Internet Society. All Rights Reserved.
Please see the Copyright section near the end of this document for
more information.
Abstract
In X.500 directories, subentries are special entries used to hold
information associated with a subtree or subtree refinement. This
document adapts X.500 subentries mechanisms for use with Lightweight
Directory Access Protocol (LDAP).
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Conventions
Schema definitions are provided using LDAP description formats
[RFC2252]. Definitions provided here are formatted (line wrapped) for
readability.
Protocol elements are described using ASN.1 [X.680]. 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].
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].
1. Overview
From [X.501]:
A subentry is a special kind of entry immediately subordinate to
an administrative point. It contains attributes that pertain to a
subtree (or subtree refinement) associated with its administrative
point. The subentries and their administrative point are part of
the same naming context.
A single subentry may serve all or several aspects of
administrative authority. Alternatively, a specific aspect of
administrative authority may be handled through one or more of its
own subentries.
Subentries in Lightweight Directory Access Protocol (LDAP) [LDAPTS]
SHALL behave in accordance with X.501 unless noted otherwise in this
specification.
In absence of the subentries control (detailed in Section 3),
subentries SHALL NOT be considered in one-level and subtree scope
search operations. For all other operations, including base scope
search operations, subentries SHALL be considered.
2. Subentry Schema
2.1. Subtree Specification Syntax
The Subtree Specification syntax provides a general purpose mechanism
for the specification of a subset of entries in a subtree of the
Directory Information Tree (DIT). A subtree begins at some base entry
and includes the subordinates of that entry down to some identified
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lower boundary, possibly extending to the leaf entries. A subtree
specification is always used within a context or scope which
implicitly determines the bounds of the subtree. For example, the
scope of a subtree specification for a subschema administrative area
does not include the subtrees of any subordinate administrative point
entries for subschema administration. Where a subtree specification
does not identify a contiguous subset of the entries within a single
subtree the collection is termed a subtree refinement.
This syntax corresponds to the SubtreeSpecification ASN.1 type
described in [X.501], Section 11.3. This ASN.1 data type definition
is reproduced here for completeness.
SubtreeSpecification ::= SEQUENCE {
base [0] LocalName DEFAULT { },
COMPONENTS OF ChopSpecification,
specificationFilter [4] Refinement OPTIONAL }
LocalName ::= RDNSequence
ChopSpecification ::= SEQUENCE {
specificExclusions [1] SET OF CHOICE {
chopBefore [0] LocalName,
chopAfter [1] LocalName } OPTIONAL,
minimum [2] BaseDistance DEFAULT 0,
maximum [3] BaseDistance OPTIONAL}
BaseDistance ::= INTEGER (0 .. MAX)
Refinement ::= CHOICE {
item [0] OBJECT-CLASS.&id,
and [1] SET OF Refinement,
or [2] SET OF Refinement,
not [3] Refinement }
The components of SubtreeSpecification are: base, which identifies the
base entry of the subtree or subtree refinement, and
specificExclusions, minimum, maximum and specificationFilter, which
then reduce the set of subordinate entries of the base entry. The
subtree or subtree refinement contains all the entries within scope
that are not excluded by any of the components of the subtree
specification. When all of the components of SubtreeSpecification are
absent (i.e. when a value of the Subtree Specification syntax is the
empty sequence, {}), the subtree so specified implicitly includes all
the entries within scope.
Any particular use of this mechanism MAY impose limitations or
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constraints on the components of SubtreeSpecification.
The LDAP syntax specification is:
( 1.3.6.1.4.1.1466.115.121.1.45 DESC 'SubtreeSpecification' )
The native LDAP encoding of values of this syntax is defined by the
Generic String Encoding Rules [GSER]. Appendix A provides an
equivalent ABNF for this syntax.
2.1.1. Base
The base component of SubtreeSpecification nominates the base entry of
the subtree or subtree refinement. The base entry may be an entry
which is subordinate to the root entry of the scope in which the
subtree specification is used, in which case the base component
contains a sequence of RDNs relative to the root entry of the scope,
or may be the root entry of the scope itself (the default), in which
case the base component is absent or contains an empty sequence of
RDNs.
Entries that are not subordinates of the base entry are excluded from
the subtree or subtree refinement.
2.1.2. Specific Exclusions
The specificExclusions component of a ChopSpecification is a list of
exclusions that specify entries and their subordinates to be excluded
from the the subtree or subtree refinement. The entry is specified by
a sequence of RDNs relative to the base entry (i.e. a LocalName).
Each exclusion is of either the chopBefore or chopAfter form. If the
chopBefore form is used then the specified entry and its subordinates
are excluded from the subtree or subtree refinement. If the chopAfter
form is used then only the subordinates of the specified entry are
excluded from the subtree or subtree refinement.
2.1.3. Minimum and Maximum
The minimum and maximum components of a ChopSpecification allow the
exclusion of entries based on their depth in the DIT.
Entries that are less than the minimum number of RDN arcs below the
base entry are excluded from the subtree or subtree refinement. A
minimum value of zero (the default) corresponds to the base entry.
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Entries that are more than the maximum number of RDN arcs below the
base entry are excluded from the subtree or subtree refinement. An
absent maximum component indicates that there is no upper limit on the
number of RDN arcs below the base entry for entries in the subtree or
subtree refinement.
2.1.4. Specification Filter
The specificationFilter component is a boolean expression of
assertions about the values of the objectClass attribute of the base
entry and its subordinates. A Refinement assertion item evaluates to
true for an entry if that entry's objectClass attribute contains the
OID nominated in the assertion. Entries for which the overall filter
evaluates to false are excluded from the subtree refinement. If the
specificationFilter is absent then no entries are excluded from the
subtree or subtree refinement because of their objectClass attribute
values.
2.2. Administrative Role Attribute Type
The Administrative Model defined in [X.501], clause 10 requires that
administrative entries contain an administrativeRole attribute to
indicate that the associated administrative area is concerned with one
or more administrative roles.
The administrativeRole operational attribute is specified as follows:
( 2.5.18.5 NAME 'administrativeRole'
EQUALITY objectIdentifierMatch
USAGE directoryOperation
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 )
The possible values of this attribute defined in X.501 are:
OID NAME
-------- -------------------------------
2.5.23.1 autonomousArea
2.5.23.2 accessControlSpecificArea
2.5.23.3 accessControlInnerArea
2.5.23.4 subschemaAdminSpecificArea
2.5.23.5 collectiveAttributeSpecificArea
2.5.23.6 collectiveAttributeInnerArea
Other values may be defined in other specifications. Names associated
with each administrative role are Object Identifier Descriptors
[LDAPIANA].
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The administrativeRole operational attribute is also used to regulate
the subentries permitted to be subordinate to an administrative entry.
A subentry not of a class permitted by the administrativeRole
attribute cannot be subordinate to the administrative entry.
2.3. Subtree Specification Attribute Type
The subtreeSpecification operational attribute is defined as follows:
( 2.5.18.6 NAME 'subtreeSpecification'
SINGLE-VALUE
USAGE directoryOperation
SYNTAX 1.3.6.1.4.1.1466.115.121.1.45 )
This attribute is present in all subentries. See [X.501], clause 10.
Values of the subtreeSpecification attribute nominate collections of
entries within the DIT for one or more aspects of administrative
authority.
2.4. Subentry Object Class
The subentry object class is a structural object class.
( 2.5.20.0 NAME 'subentry'
SUP top STRUCTURAL
MUST ( cn $ subtreeSpecification ) )
3. Subentries Control
The subentries control MAY be sent with a searchRequest to control the
visibility of entries and subentries which are within scope.
Non-visible entries or subentries are not returned in response to the
request.
The subentries control is an LDAP Control whose controlType is
1.3.6.1.4.1.4203.1.10.1, criticality is TRUE or FALSE (hence absent),
and controlValue contains a BER-encoded BOOLEAN indicating visibility.
A controlValue containing the value TRUE indicates that subentries are
visible and normal entries are not. A controlValue containing the
value FALSE indicates that normal entries are visible and subentries
are not.
Note that TRUE visibility has the three octet encoding { 01 01 FF }
and FALSE visibility has the three octet encoding { 01 01 00 }.
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The controlValue SHALL NOT be absent.
In absence of this control, subentries are not visible to singleLevel
and wholeSubtree scope Search requests but are visible to baseObject
scope Search requests.
There is no corresponding response control.
This control is not appropriate for non-Search operations.
4. Security Considerations
Subentries often hold administrative information or other sensitive
information and should be protected from unauthorized access and
disclosure as described in [RFC2829][RFC2830].
General LDAP [LDAPTS] security considerations also apply.
5. IANA Considerations
5.1 Descriptors
It is requested that IANA register the LDAP descriptors used in this
document per the following registration template:
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): see comment
Object Identifier: see comment
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Usage: see comment
Specification: RFCXXXX
Author/Change Controller: IESG
Comments:
NAME Type OID
------------------------ ---- --------
accessControlInnerArea R 2.5.23.3
accessControlSpecificArea R 2.5.23.2
administrativeRole A 2.5.18.5
autonomousArea R 2.5.23.1
collectiveAttributeInnerArea R 2.5.23.6
collectiveAttributeSpecificArea R 2.5.23.5
subentry O 2.5.20.0
subschemaAdminSpecificArea R 2.5.23.4
subtreeSpecification A 2.5.18.6
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where Type A is Attribute, Type O is ObjectClass, and Type R is
Administrative Role.
5.2 Object Identifiers
No IANA assignment of object identifiers is requested.
This document uses the OID 1.3.6.1.4.1.4203.1.10.1 to identify an LDAP
protocol element defined herein. This OID was assigned [ASSIGN] by
OpenLDAP Foundation under its IANA assigned private enterprise
allocation [PRIVATE] for use in this specification.
Other OIDs which appear in this document were either assigned by the
ISO/IEC Joint Technical Committee 1 - Subcommitte 6 to identify
elements of X.500 schema or assigned in RFC 2252 for the use described
here.
6. Acknowledgment
This document is based on engineering done by IETF LDUP and LDAPext
Working Groups including "LDAP Subentry Schema" by Ed Reed. This
document also borrows from a number of ITU documents including X.501.
7. Authors' Addresses
Kurt D. Zeilenga
OpenLDAP Foundation
Email: Kurt@OpenLDAP.org
Steven Legg
Adacel Technologies Ltd.
405-409 Ferntree Gully Road
Mount Waverley, Victoria 3149
AUSTRALIA
Phone: +61 3 9451 2107
Fax: +61 3 9541 2121
EMail: steven.legg@adacel.com.au
8. Normative References
[X.501] ITU-T, "The Directory -- Models," X.501, 1993.
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[X.680] ITU-T, "Abstract Syntax Notation One (ASN.1) -
Specification of Basic Notation", X.680, 1994.
[X.690] ITU-T, "Specification of ASN.1 encoding rules: Basic,
Canonical, and Distinguished Encoding Rules", X.690, 1994.
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (was RFC 2119), March 1997.
[RFC2251] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol (v3)", RFC 2251, December 1997.
[RFC2252] M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight
Directory Access Protocol (v3): Attribute Syntax
Definitions", RFC 2252, December 1997.
[RFC2829] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan,
"Authentication Methods for LDAP", RFC 2829, May 2000
[RFC2830] J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory
Access Protocol (v3): Extension for Transport Layer
Security", RFC 2830, May 2000.
[LDAPTS] J. Hodges, R.L. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification",
draft-ietf-ldapbis-ldapv3-ts-xx.txt, a work in progress.
[GSER] S. Legg, "Generic String Encoding Rules for ASN.1 Types",
draft-legg-ldapext-gser--xx.txt, a work in progress.
[LDAPIANA] K. Zeilenga, "IANA Considerations for LDAP", draft-ietf-
ldapbis-iana-xx.txt, a work in progress.
9. Informative References
[RFC2234] D. Crocker, P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[GCE] S. Legg, "Common Elements of GSER Encodings",
draft-legg-ldap-gser-abnf-xx.txt, a work in progress.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
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A. Subtree Specification ABNF
This appendix is non-normative.
The LDAP-specific native string encoding for the Subtree Specification
syntax is specified by the Generic String Encoding Rules [GSER]. The
ABNF [RFC2234] in this appendix for this syntax is provided only as a
convenience and is equivalent to the encoding specified by the
application of [GSER]. Since the SubtreeSpecification ASN.1 type may
be extended in future editions of [X.501], the provided ABNF should be
regarded as a snapshot in time. The native LDAP encoding for any
extension to the SubtreeSpecification ASN.1 type can be determined
from [GSER].
In the event that there is a discrepancy between this ABNF and the
encoding determined by [GSER], [GSER] is to be taken as definitive.
SubtreeSpecification = "{" [ sp base ]
[ sep sp specificExclusions ]
[ sep sp minimum ]
[ sep sp maximum ]
[ sep sp specificationFilter ]
sp "}"
base = id-base msp LocalName
specificExclusions = id-specificExclusions msp SpecificExclusions
minimum = id-minimum msp BaseDistance
maximum = id-maximum msp BaseDistance
specificationFilter = id-specificationFilter msp Refinement
id-base = %x62.61.73.65 ; "base"
id-specificExclusions = %x73.70.65.63.69.66.69.63.45.78.63.6C.75.73
%x69.6F.6E.73 ; "specificExclusions"
id-minimum = %x6D.69.6E.69.6D.75.6D ; "minimum"
id-maximum = %x6D.61.78.69.6D.75.6D ; "maximum"
id-specificationFilter = %x73.70.65.63.69.66.69.63.61.74.69.6F.6E.46
%x69.6C.74.65.72 ; "specificationFilter"
SpecificExclusions = "{" sp SpecificExclusion
*( "," sp SpecificExclusion ) sp "}"
SpecificExclusion = chopBefore / chopAfter
chopBefore = id-chopBefore ":" LocalName
chopAfter = id-chopAfter ":" LocalName
id-chopBefore = %x63.68.6F.70.42.65.66.6F.72.65 ; "chopBefore"
id-chopAfter = %x63.68.6F.70.41.66.74.65.72 ; "chopAfter"
Refinement = item / and / or / not
item = id-item ":" OBJECT-IDENTIFIER
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and = id-and ":" Refinements
or = id-or ":" Refinements
not = id-not ":" Refinement
Refinements = "{" [ sp Refinement
*( "," sp Refinement ) ] sp "}"
id-item = %x69.74.65.6D ; "item"
id-and = %x61.6E.64 ; "and"
id-or = %x6F.72 ; "or"
id-not = %x6E.6F.74 ; "not"
BaseDistance = INTEGER
The <sp>, <msp>, <sep>, <INTEGER>, <OBJECT-IDENTIFIER> and <LocalName>
rules are defined in [GCE].
Copyright 2002, The Internet Society. All Rights Reserved.
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