INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Experimental Isode Limited
Expires in six months 13 July 2008
The LDAP Relax Rules Control
<draft-zeilenga-ldap-relax-03.txt>
Status of this Memo
This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor for publication as an
Experimental document. Distribution of this memo is unlimited.
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Extensions mailing list <ldapext@ietf.org>. Please send editorial
comments directly to the author <Kurt.Zeilenga@Isode.COM>.
This document replaces draft-zeilenga-ldap-managedit-xx.txt.
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Abstract
This document defines the Lightweight Directory Access Protocol (LDAP)
Relax Rules Control which allows a directory user agent (a client) to
request the directory service temporarily relax enforcement of various
data and service model rules.
1. Background and Intended Use
Directory servers accessible via Lightweight Directory Access Protocol
(LDAP) [RFC4510] are expected to act in accordance with the X.500
[X.500] series of ITU-T Recommendations. In particular, servers are
expected to ensure the X.500 data and service models are not violated.
An LDAP server is expected to prevent modification of the structural
object class of an object [RFC4512]. That is, the X.500 models do not
allow a 'person' object to be transformed into an
'organizationalPerson' object through modification of the object.
Instead, the 'person' object must be deleted and then a new
'organizationalPerson' object created in its place. This approach,
aside from being inconvient, is problematic for a number reasons.
First, as LDAP does not have a standardized method for performing the
two operations in a single transaction, the intermediate directory
state (after the delete, before the add) is visible to other clients,
which may lead to undesirable client behavior. Second, attributes
such as 'entryUUID' [RFC4530] will reflect the object was replaced,
not transformed.
An LDAP server is expected to prevent clients from modifying values of
NO-USER-MODIFICATION attributes [RFC4512]. For instance, an entry is
not allowed to assign or modify the value of the 'entryUUID'
attribute. However, where an administrator is restoring a previously
existing object, for instance when repartitioning data between
directory servers or when migrating from one vendor server product to
another, it may be desirable to allow the client to assign or modify
the value of the 'entryUUID' attribute.
This document defines the LDAP Relax Rules control. This control may
be attached to LDAP requests to update the Directory Information Tree
(DIT) to request various data and service rules be temporarily relaxed
during the performance of the requested DIT update. The server is
however to ensure the resulting directory state is valid.
Use of this control is expected that use of this extension will be
restricted by administrative and/or access controls. It is intended
to be used primarily by directory administrators.
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This extension is considered experimental as it is not yet clear
whether it adequately addresses directory administrators' needs for
flexible mechanisms for managing directory objects. It is hoped that
after suitable amount of time, either this extension or a suitable
replacement will be standardization.
1.1. 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 5.1 of [RFC4511].
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 RFC 2119 [RFC2119].
DSA stands for Directory System Agent, a server. DSE stands for
DSA-specific Entry.
2. The Relax Rules Control
The Relax Rules control is an LDAP Control [RFC4511] whose controlType
is IANA-ASSIGNED-OID, controlValue is empty, and the criticality of
TRUE.
There is no corresponding response control.
The control is appropriate for all LDAP update requests, including
add, delete, modify, and modifyDN (rename) [RFC4511].
The presence of the Rules Rules control in an LDAP update request
indicates the server temporarily relax X.500 model contraints during
performance of the directory update.
The server may restrict use of this control and/or limit the extent of
the relaxation provided based upon local policy or factors.
The server is obligated to ensure the resulting directory state is
consistent with the X.500 models. For instance, the server ensure
that values of attributes conform to the value syntax.
It is noted that while this extension may be used to add or modify
objects in a manner which violate the controlling subschema, the
presence of objects in the DIT is not inconsistent with the X.500
models. For instance, an object created prior to establshment of a
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DIT content rule may contain an attribute now precluded by the current
controlling DIT Content Rule.
Servers implementing this technical specification SHOULD publish the
object identifier IANA-ASSIGNED-OID 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.
3. Use Cases
3.1. Object metamorphism
In absence of this control, an attempt to modify an object's
'objectClass' in a manner which cause a change in the structural
object class of the object would normally lead to an
objectClassModsProhibited error [RFC4511]. The presence of the Relax
Rules control in the modify request requests the change be allowed.
If the server is willing and able to allow the change in the
structural object class of the object.
For instance, to change an 'organization' object into an
'organizationalUnit' object, a client could issue the following LDAP
request:
dn: o=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: modify
delete: objectClass
objectClass: organization
-
add: objectClass
objectClass: organizationalUnit
-
In this case, the server is expected to either effect the requested
change in the structural object class, including updating of the value
of the structural object class, or fail the operation.
3.2. Inactive Attribute Types
In absence of the Relax Rules control, an attempt to add or modify
values to an attribute whose type has been marked inactive in the
controlling subschema (its attribute type description contains the
OBSOLETE field) [RFC4512] normally results in a failure.
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In the presence of the Relax Rules control, the server performs the
update operation as if the attribute's type is marked active in the
controlling subschema (its attribute type description does not contain
the OBSOLETE field).
3.3. DIT Content Rules
In absence of the Relax Rules control, an attempt to include the name
(or OID) of an auxiliary class to an object's 'objectClass' which is
not allowed by the controlling DIT Content Rule would be disallowed
[RFC4512]. Additionally, an attempt to add values of an attribute
not allowed (or explicitly precluded) by the DIT Content Rule would
fail.
In presence of the Relax Rules control, the server performs the update
operation as if the controlling DIT Content Rule allowed any and all
known auxiliary classses to be present and allowed any and all known
attributes to be present (and precluded no attributes).
3.4. DIT Structure Rules and Name Forms
In absence of the Relax Rules control, the service enforces DIT
structure rules and name form requirements of the controlling
subschema [RFC4512].
In the presence of the Relax Rules control, the server performs the
update operation ignoring all DIT structure rules and name forms in
the controlling subschema.
3.5. Modification of Nonconformant Objects
It is also noted that in absense of this control, modification of an
object which presently violates the controlling subschema will fail
unless the modification would result in the object conforming to the
controlling subschema. That is, modifications of an non-conformant
object should result in a conformant object.
In the presence of this control, modifications of a non-conformant
object need not result in a conformant object.
3.6. NO-USER-MODIFICATION attribute modification
In absence of this control, an attempt to modify values of a
NO-USER-MODIFICATION attribute [RFC4512] would normally lead to a
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constraintViolation or other appropriate error [RFC4511]. In the
presence of the Relax Rules control in the update request requests the
modification be allowed.
Relaxation of the NO-USER-MODIFICATION constraint is not appropriate
for some operational attribute types. For instance, as the value of
the 'structuralObjectClass' is derived by the values of the
'objectClass' attribute, the 'structuralObjectClass' attribute type's
NO-USER-MODIFICATION contraint MUST NOT be relaxed. To effect a
change in the structuralObjectClass class, values of objectClass
should be changed as discussed in Section 3.1. Other attributes for
which the NO-USER-MODIFICATION constraint should not be relaxed
include 'subschemaSubentry' [RFC4512] and
'collectiveAttributeSubentries' [RFC3671].
The subsections of this section discuss modification of various
operational attributes where their NO-USER-MODIFICATION constraint may
be relaxed. Future documents may specify where NO-USER-MODIFICATION
constraints on other operational attribute may be relaxed. In absence
of a document detailing that the NO-USER-MODIFICATION constraint on a
particular operational attribute may be relaxed, implementors SHOULD
assume relaxation of the constraint is not appropriate for that
attribute.
3.1.1. 'entryUUID' attribute
To provide a value for the 'entryUUID' [RFC4530] attribute on entry
creation, the client should issue an LDAP Add request with a Relax
Rules control providing the desired value. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: add
objectClass: organizationalUnit
ou: Unit
entryUUID: 597ae2f6-16a6-1027-98f4-d28b5365dc14
In this case, the server is either to add the entry using the
provided 'entryUUID' value or fail the request.
To provide a replacement value for the 'entryUUID' after entry
creation, the client should issue an LDAP Modify request with a
Relax Rules control including an approrpiate change. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: modify
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replace: entryUUID
entryUUID: 597ae2f6-16a6-1027-98f4-d28b5365dc14
-
In this case, the server is either to replace the 'entryUUID' value
as requested or fail the request.
3.2.2. createTimestamp
To provide a value for the 'createTimestamp' [RFC4512] attribute
on entry creation, the client should issue an LDAP Add request with
a Relax Rules control providing the desired 'createTimestamp'
value. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: add
objectClass: organizationalUnit
ou: Unit
createTimestamp: 20060101000000Z
In this case, the server is either to add the entry using the
provided 'createTimestamp' value or fail the request.
To provide a replacement value for the 'createTimestamp' after
entry creation, the client should issue an LDAP Modify request with
a Relax Rules control including an approrpiate change. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: modify
replace: createTimestamp
createTimestamp: 20060101000000Z
-
In this case, the server is either to replace the 'createTimestamp'
value as requested or fail the request.
The server should ensure the requested 'createTimestamp' value is
appropriate. In particular, it should fail the request if the
requested 'createTimestamp' value is in the future or is greater
than the value of the 'modifyTimestamp' attribute.
3.2.3. modifyTimestamp
To provide a value for the 'modifyTimestamp' [RFC4512] attribute
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on entry creation, the client should issue an LDAP Add request with
a Relax Rules control providing the desired 'modifyTimestamp'
value. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: add
objectClass: organizationalUnit
ou: Unit
modifyTimestamp: 20060101000000Z
In this case, the server is either to add the entry using
the provided 'modifyTimestamp' value or fail the request.
To provide a replacement value for the 'modifyTimestamp' after
entry creation, the client should issue an LDAP Modify
request with a Relax Rules control including an approrpiate
change. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: modify
replace: modifyTimestamp
modifyTimestamp: 20060101000000Z
-
In this case, the server is either to replace the 'modifyTimestamp'
value as requested or fail the request.
The server should ensure the requested 'modifyTimestamp' value is
appropriate. In particular, it should fail the request if the
requested 'modifyTimestamp' value is in the future or is less than
the value of the 'createTimestamp' attribute.
3.2.3. creatorsName and modifiersName
To provide a value for the 'creatorsName' and/or 'modifiersName'
[RFC4512] attribute on entry creation, the client should issue an
LDAP Add request with a Relax Rules control providing the desired
values. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: add
objectClass: organizationalUnit
ou: Unit
creatorsName: cn=Jane Doe,dc=example,net
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modifiersName: cn=Jane Doe,dc=example,net
In this case, the server is either to add the entry using
the provided values or fail the request.
To provide a replacement values after entry creation for either of
the 'creatorsName' or 'modifiersName' attributes or both, the
client should issue an LDAP Modify request with a Relax Rules control
including the approrpiate changes. For instance:
dn: ou=Unit,dc=example,dc=net
control: IANA-ASSIGNED-OID
changetype: modify
replace: creatorsName
creatorsName: cn=Jane Doe,dc=example,net
-
replace: modifiersName
modifiersName: cn=Jane Doe,dc=example,net
-
In this case, the server is either to replace the provided
values as requested or fail the request.
4. Security Considerations
Use of this extension should be subject to appropriate administrative
and access controls. Use of this mechanism is intended to be
restricted to directory administrators.
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.
5. IANA Considerations
5.1. Object Identifier
It is requested that the IANA assign a LDAP Object Identifier
[RFC4520] to identify the LDAP Relax Rules Control defined in this
document.
Subject: Request for LDAP Object Identifier Registration
Person & email address to contact for further information:
Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Specification: RFC XXXX
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Author/Change Controller: Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Comments: Identifies the LDAP Relax Rules Control
5.2 LDAP Protocol Mechanism
Registration of this protocol mechanism [RFC4520] is requested.
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: IANA-ASSIGNED-OID
Description: Relax Rules Control
Person & email address to contact for further information:
Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Usage: Control
Specification: RFC XXXX
Author/Change Controller: Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Comments: none
6. Author's Address
Kurt D. Zeilenga
Isode Limited
Email: Kurt.Zeilenga@Isode.COM
7. References
[[Note to the RFC Editor: please replace the citation tags used in
referencing Internet-Drafts with tags of the form RFCnnnn where
possible.]]
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (also RFC 2119), March 1997.
[RFC3671] Zeilenga, K., "Collective Attributes in LDAP", RFC 3671,
December 2003.
[RFC4510] Zeilenga, K. (editor), "LDAP: Technical Specification
Road Map", RFC 4510, June 2006.
[RFC4511] Sermersheim, J. (editor), "LDAP: The Protocol", RFC
4511, June 2006.
[RFC4512] Zeilenga, K. (editor), "LDAP: Directory Information
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Models", RFC 4512, June 2006.
[RFC4530] Zeilenga, K., "Lightweight Directory Access Protocol
(LDAP) entryUUID Operational Attribute", RFC 4530, June
2006.
[X.500] International Telecommunication Union -
Telecommunication Standardization Sector, "The Directory
-- Overview of concepts, models and services,"
X.500(1993) (also ISO/IEC 9594-1:1994).
7.2. Informative References
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority
(IANA) Considerations for the Lightweight Directory
Access Protocol (LDAP)", RFC 4520, BCP 64, June 2006.
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