INTERNET-DRAFT
draft-ietf-ldup-subentry-07.txt
Ed Reed
Reed-Matthews, Inc.
March 1, 2001
LDAP Subentry Schema
1 Status of this Memo
This document is an Internet-Draft and is in full
conformance with all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet
Engineering Task Force (IETF), its areas, and its working
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Internet-Drafts are draft documents valid for a maximum of
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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
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The list of Internet-Draft Shadow Directories can be
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This Internet-Draft expires on September 1, 2001.
2 Abstract / Description
This document describes two object classes called
ldapSubEntry and inheritableLDAPSubEntry, and a control,
ldapSubentriesControl (to control the visibility of entries
of type ldapSubEntry) which MUST be used by directory
servers claiming support for the features of this document
to indicate operations and management related entries in
the directory, called LDAP Subentries. Scope rules are
defined for LDAP Subentries.
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
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described in [RFC2119]. The sections below reiterate these
definitions and include some additional ones.
3 Table of Contents
1 Status of this Memo 1
2 Abstract / Description 1
3 Table of Contents 2
4 Object Class Definitions 2
4.1 ldapSubEntry Class 2
4.1.1 Scope Rules 3
4.2 InheritableLDAPSubentry Class 4
4.2.1 Illustration 5
5 Attribute Definitions 6
5.1 inheritable Attribute 6
5.2 blockInheritance Attribute 6
6 Visibility Controls 7
6.1 ldapSubentriesControl 7
6.1.1 LDAP Search with scope other than baseObject 7
6.1.2 LDAP Search with scope of baseObject 7
6.1.3 Other LDAP operations 8
6.1.4 Correspondence to X.500 [X.511] 8
7 Security Considerations 8
8 References 9
9 Copyright Notice 9
10 Acknowledgements 10
11 Author's Address 11
4 Object Class Definitions
4.1 ldapSubEntry Class
( 2.16.840.1.113719.2.142.6.1.1 NAME 'ldapSubEntry'
DESC 'LDAP Subentry class, version 1'
SUP top STRUCTURAL
MAY ( cn ) )
The class ldapSubEntry is intended to be used as a super-
class when defining other structural classes to be used
as LDAP Subentries, and as the structural class to which
Auxiliary classes may be added for application specific
subentry information. Where possible, the use of Auxiliary
classes to extend LDAP Subentries is strongly preferred.
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The presence of ldapSubEntry in the list of super-classes
of an entry in the directory makes that entry an LDAP
Subentry. Object classes derived from ldapSubEntry are
themselves considered ldapSubEntry classes, for the purpose
of this discussion.
LDAP Subentries MAY be named by their commonName attribute
[RFC2251]. Other naming attributes are also permitted.
LDAP Subentries MAY be containers, unlike their [X.501]
counterparts.
LDAP Subentries MAY be contained by, and will usually be
located in the directory information tree immediately
subordinate to, administrative points. Further (unlike
X.500 subentries), LDAP Subentries MAY be contained by
other LDAP Subentries (the way organizational units may be
contained by other organizational units). Deep nesting of
LDAP Subentries are discouraged, but not prohibited.
Developers are warned that deep nesting of LDAP Subentries
may not be supported by all (or indeed, by any) LDAP server
implementations.
4.1.1Scope Rules
The default scope of an LDAP Subentry is limited to the
administrative area in which it is defined. Specifically,
the subtree of the directory namespace based at the
administrative point most immediately superior to the LDAP
Subentry, down to but not including any subordinate
administrative points or areas. Policy defined in an LDAP
Subentry is not inheritable, unless such inheritance is
explicitly defined (see the object class definition for
InheritableLDAPSubEntry, below, for such an example).
If an LDAP Subentry is subordinate to another LDAP
Subentry, it takes the same default scope as the parent
LDAP Subentry.
Applications MAY define alternative scope semantics for
classes they define which are derived from the ldapSubEntry
class. This means that an application can derive a new
class from the ldapSubEntry class and add an attribute,
like subtreeSpecification [X.501] or inheritance controls
(see below), to define a new scope rule for that
application to use.
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Applications MUST NOT define alternative scope rules for
auxiliary classes used to decorate entries of the
ldapSubEntry class. This restriction is required to avoid
having conflicting or contradictory scope definitions
applied by different applications to the same LDAP
Subentry.
4.2 InheritableLDAPSubEntry Class
( 1.3.6.1.4.1.7628.5.6.1.1 NAME 'inheritableLDAPSubEntry'
DESC 'Inheritable LDAP Subentry class, version 1'
SUP ldapSubEntry STRUCTURAL
MUST ( inheritable )
MAY ( blockInheritance )
The InheritableLDAPSubentry class is derived from the
ldapSubEntry class and provides modified scope semantics to
permit and control inheritance from one administrative area
to one or more subordinate administrative areas.
If the 'inheritable' attribute is TRUE (1), then the policy
information contained in the InheritableLDAPSubEntry is
intended to apply to any (and all) subordinate
administrative areas. Subordinate administrative areas
MUST include Inheritable LDAP Subentries from their
immediately superior administrative area (unless blocked,
see below). The means of such inclusion (that is, whether
via replication, caching, or explicitly walking the tree to
locate and "include" them, are left to the application that
consumes the inheritable policy information contained on
the inheritableLDAPSubEntry.
If the 'inheritable' attribute is FALSE (0), the policy is
NOT inheritable, and subordinate administrative areas MUST
treat the associated policy information as UNDEFINED (that
is, absent) unless explicitly defined within their own
administrative area.
If a subordinate administrative area defines an Inheritable
LDAP Subentry for an application with the same name as one
defined in a superior administrative area, and if the
subordinateÆs Inheritable LDAP Subentry has the attribute
'blockInheritance' with the value TRUE, then inheritance is
blocked from the superior administrative area to that
subordinate administrative area, and the effect is the same
as if the superior Inheritable LDAP Subentry contained the
'inheritable' attribute set to FALSE.
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The value of the 'blockInheritance' attribute in a superior
administrative area Inheritable LDAP Subentry is irrelevant
to a subordinate administrative area for this object class.
No mechanism is defined (at this time) to signal to
subordinate administrative areas that they may not block
inheritable policy from superior administrative areas.
4.2.1Illustration
An illustration may help clarify the use of the class and
these attributes.
Suppose the administrative area based at 'dc=com' has an
Inheritable LDAP Subentry for an application defined with
the 'inheritable' attribute set to TRUE. Subordinate
administrative areas, for instance 'dc=widget, dc=com'
might or might not want to accept the inherited policy from
the 'dc=com' administrative area.
If the administrator of the 'dc=widget, dc=com'
administrative area creates an Inheritable LDAP Subentry
(say, 'cn=example, dc=widget, dc=com') with the same
relative distinguished name as used in the 'dc=com'
administrative area (that is, 'cn=example, dc=com') setting
the 'blockInheritance' attribute set to TRUE, then the
inheritance of the policy defined (on 'cn=example, dc=com')
is effectively blocked from affecting the 'dc=widget,
dc=com' administrative area. WeÆll call this a blocking
subentry for our discussion here.
If the administrator of the 'dc=widget, dc=com'
administrative area creates a blocking subentry (as above)
with some locally defined policy information, that policy
information effectively replaces the policy information
defined by the superior administrative area. WeÆll call
this an over-riding subentry for our discussion here.
An over-riding subentry MAY itself be inheritable, in which
case the 'inheritable' attribute on the locally defined
Inheritable LDAP Subentry MAY be set to TRUE or FALSE, at
the discretion of the local administrative authority, with
appropriate implications for inheritance of the new,
locally defined policy, on any other subordinate
administrative areas. In this way, the 'dc=widget, dc=com'
administrator can set inheritable policy for organizational
units (like 'ou=eng, dc=widget, dc=com') for an application
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while over-riding inheritable policy from the superior
'dc=com' administrative area.
5 Attribute Definitions
5.1 inheritable Attribute
( 1.3.6.1.4.1.7628.5.4.1 NAME 'inheritable'
SYNTAX BOOLEAN
SINGLE-VALUE NO-USER-MODIFICATION USAGE dSAOperation )
Used to signal whether an inheritableLDAPSubEntry is
intended to be inherited by subordinate administrative
areas, or not. TRUE indicates that the subentry and the
policy it contains is inheritable.
FALSE indicates that information from the
inheritableLDAPSubEntry is not to be inherited by
subordinate administrative areas.
5.2 blockInheritance Attribute
( 1.3.6.1.4.1.7628.5.4.2 NAME 'blockInheritance'
SYNTAX BOOLEAN
SINGLE-VALUE NO-USER-MODIFICATION USAGE dSAOperation )
Used by administrators of subordinate administrative areas
to over-ride, or block, the inheritance of
inheritableLDAPSubEntry policy from superior administrative
areas.
A value of TRUE indicates that inheritance is to be
blocked.
A value of FALSE is implies that inheritance is not to be
blocked, but specific semantic interpretation is left to
applications (who may specify any of a variety of policy
aggregation mechanisms to define how inherited policy is to
be mixed with locally defined policy, which mechanisms are
explicitly outside the scope of this specification).
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6 Visibility Controls
6.1 ldapSubentriesControl
This control is included in the searchRequest message as
part of the controls field of the LDAPMessage, as defined
in Section 4.1.12 of [RFC2251].
The controlType is set to "1.3.6.1.4.1.7628.5.101.1". The
criticality MAY be set to either TRUE or FALSE. The
controlValue is absent.
There is no corresponding response control defined.
LDAP servers that support this control MUST treat LDAP
Subentries as "operational objects" in much the same way
that "operational attributes" are not returned in search
results and [X.511] read operations when only user
attributes are requested.
Entries which are not LDAP Subentries may still be
referenced in the base object of search operations where
the ldapSubentriesControl is present in the request.
6.1.1LDAP Search with scope other than baseObject
The ldapSubentriesControl is defined for LDAP to signal to
LDAP Search operations that ONLY LDAP Subentries are to be
included in the return set of entries for the Search,
provided other Search criteria (such as scope and filter)
are satisfied. When ldapSubentriesControl is NOT included
in a Search request on a server that supports the control,
LDAP Subentries MUST be omitted from the return set (with
the single exception described in Search Filter Visibility,
below).
6.1.2LDAP Search with scope of baseObject
For Search operations with a scope value of baseObject, the
presence or absence of the ldapSubentriesControl MUST be
ignored. Specifically, baseObject searches applied to
ldapSubEntry entries MUST be evaluated by Search as if the
ldapSubentriesControl is present, even if it is absent.
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This provision is intended to preserve the behavior of
[X.511] Read operations, which are not affected by the
[X.511] subentries control (see Correspondence to X.500,
below), and because it would seem silly to behave
otherwise.
6.1.3Other LDAP operations
The ldapSubentriesControl is not defined for any LDAP
operation other than Search. However, an LDAPv3 Extension
MAY define a use of this control with that extension as
long as such use is consistent with this specification.
6.1.4Correspondence to X.500 [X.511]
In [X.511] a ServiceControl option is used to govern the
visibility of [X.501] subentries. The subentry
ServiceControl option is a specific bit of a bitstring
that, when set to TRUE in the common arguments of an X.500
Search or List operation, indicates that the operation is
to access ONLY the subentries found in the context of the
list or search. In fact, normal entries are explicitly NOT
returned in the result of a list or search operation when
the X.500 subentries ServiceControl is set.
Entries which are not subentries may still be referenced in
the base object of list and search operations where the
subentries control is set.
The [X.511] subentries ServiceControl has no meaning for
operations other than Search and List (i.e., Read, Modify,
Delete, etc.).
In [X.501], the scope of a subentry is a subtree or subtree
refinement. The ldapSubEntry class defined in this
document provides no mechanism to define a subtree
refinement.
7 Security Considerations
LDAP Subentries will frequently be used to hold data which
reflects either the actual or intended behavior of the
directory service. As such, permission to read such
entries MAY need to be restricted to authorized users.
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More importantly, IF a directory service treats the
information in an LDAP Subentry as the authoritative source
of policy to be used to control the behavior of the
directory, then permission to create, modify, or delete
such entries MUST be carefully restricted to authorized
administrators.
This specification defines a policy inheritance model that
allows subordinate administrators to over-ride policy
defined by administrators of administrative areas superior
to the local administrative area. No mechanism is defined
here to keep local administrators from over-riding such
inherited policy. Implementations that intend to provide
such control over the actions of subordinate administrators
will require additional semantics (and possibly syntax).
8 References
[RFC2119] S. Bradner, "Key words for use in RFCs to
Indicate Requirement Levels", RFC 2119, March 1997
[RFC2251] S. Kille, M. Wahl, and T. Howes, "Lightweight
Directory Access Protocol (v3)", RFC 2251, December 1997
[X.501] ITU-T Rec. X.501, "The Directory: Models", 1993 and
subsequent versions
[X.511] ITU-T Rec. X.501, "The Directory: Abstract Service
Definition", 1993 and subsequent versions
9 Copyright Notice
Copyright (C) The Internet Society (2000). All Rights
Reserved.
This document and translations of it may be copied and
furnished to others, and derivative works that comment on
or otherwise explain it or assist in its implementation may
be prepared, copied, published and distributed, in whole or
in part, without restriction of any kind, provided that the
above copyright notice and this paragraph are included on
all such copies and derivative works. However, this
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document itself may not be modified in any way, such as by
removing the copyright notice or references to the Internet
Society or other Internet organizations, except as needed
for the purpose of developing Internet standards in which
case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to
translate it into languages other than English.
The limited permissions granted above are perpetual and
will not be revoked by the Internet Society or its
successors or assigns.
This document and the information contained herein is
provided on an "AS IS" basis and THE INTERNET SOCIETY AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
10 Acknowledgements
The utility of subEntry object class was originally
suggested as a means to store Replica and Replication
Agreement information with a the lucid explanation by Mark
Wahl, (then of Innosoft), of how they could be used and
extended.
The IETF takes no position regarding the validity or scope
of any intellectual property or other rights that might be
claimed to pertain to the implementation or use of the
technology described in this document or the extent to
which any license under such rights might or might not be
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Copies of claims of rights made available for publication
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result of an attempt made to obtain a general license or
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implementers or users of this specification can be obtained
from the IETF Secretariat.
The IETF invites any interested party to bring to its
attention any copyrights, patents or patent applications,
or other proprietary rights which may cover technology that
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may be required to practice this standard. Please address
the information to the IETF Executive Director.
11 Author's Address
Edwards E. Reed
Reed-Matthews, Inc.
1064 E 140 North
Lindon, UT 84042
USA
E-mail: eer@oncalldba.com
LDUP Mailing List: ietf-ldup@imc.org
LDAPEXT Mailing List: ietf-ldapext@netscape.com
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