INTERNET-DRAFT Kurt D. Zeilenga Intended Category: Standard Track Isode Limited Expires in six months 6 January 2011 The LDAP Don't Use Copy Control 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 document. Distribution of this memo is unlimited. Technical discussion of this document will take place on the IETF LDAP Extensions mailing list . Please send editorial comments directly to the author . This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. 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/1id-abstracts.html. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. Zeilenga LDAP Don't Use Copy Control [Page 1] INTERNET-DRAFT draft-zeilenga-ldap-dontusecopy-09 6 January 2011 Abstract This document defines the Lightweight Directory Access Protocol (LDAP) Don't Use Copy control extension which allows a client to specify that copied information should not be used in providing service. This control is based upon the X.511 dontUseCopy service control option. 1. Background and Intended Usage This document defines the Lightweight Directory Access Protocol (LDAP) [RFC4510] Don't Use Copy control extension. The control may be attached to request messages to indicate that copied (replicated or cached) information [X.500] is not be used in providing service. This control is based upon the X.511 [X.511] dontUseCopy service control option. The Don't Use Copy control is intended to be used where the client requires the service be provided using original (master) information [X.500]. In absence of this control, the server is free to make use of copied information in providing the requested service. For instance, a client might desire to have an authoritative answer to a question of whether or not a particular user is a member of a group. To ask this question of a server, the client might issue a compare request [RFC4511], with the Don't Use Copy control, where the entry parameter is the Distinguished Name (DN) of the group, the ava.attributeDesc is 'member', and the ava.assertionValue is the DN of the user the client desires to know is or isn't a member of the group. If the server has access to the original (master) information directly or through chaining, it performs the operation against the original (master) information and return compareTrue or compareFalse (or an error). If the server does not have access to the orignal information, the server is obligated to either return a referral or an error. It is noted that a referral, if returned, is not necessarily to the server holding the original (master) information. It is also noted that an authoritative answer to the question might not be available to the client for any number of reasons. Where the client chases a referral to a server as referenced by an LDAP URL in the server response in order to obtain an authorative response , the client MUST provide the dontUseCopy control with the interrogation request it makes to the referred to server. While LDAP allows return of other kinds of URIs, the syntax and semantics of other kinds of URIs, as well the particulars of acting upon such other kinds of URIs, to future specifications. This document also leaves Zeilenga LDAP Don't Use Copy Control [Page 2] INTERNET-DRAFT draft-zeilenga-ldap-dontusecopy-09 6 January 2011 the particulars of how to act upon other kinds of URIs to future specifications. It is noted that in absence of some assurance that only authoratitive information is used in producing an answer, the client ought to assume non-authorative information is used. It is not intended that this control be used generally (e.g., for all LDAP interrogation operations) but only as required to ensure proper directory application behavior. In general, directory applications ought to designed to well use copied information. 2. Terminology 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 RFC 2119 [RFC2119]. 3. The Don't Use Copy Control The Don't Use Copy control is an LDAP Control [RFC4511] whose controlType is IANA-ASSIGNED-OID and controlValue is absent. The criticality MUST be TRUE. There is no corresponding response control. The control is appropriate for LDAP interrogation operations, including Compare and Search operations [RFC4511]. It is inappropriate for all other operations, including Abandon, Bind, Delete, Modify, ModifyDN, StartTLS, and Unbind operations [RFC4511]. When the control is attached to an LDAP request, the requested operation MUST NOT be performed on copied information. That is, the requested operation MUST be performed on original information. If original (master) information for the target or base object of the operation is not available (either locally or through chaining), the server MUST either return a referral directing the client to a server believed to be better able to service the request or return an appropriate result code (e.g., unwillingToPerform). 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. Zeilenga LDAP Don't Use Copy Control [Page 3] INTERNET-DRAFT draft-zeilenga-ldap-dontusecopy-09 6 January 2011 4. Security Considerations This control is intended to be provided where providing service using copied information might lead to unexpected application behavior. Use of the Don't Use Copy control may permit an attacker to perform or amplify a Denial of Service attack by causing additional server resources to be employed, such as when the server chooses to chain the request instead of returning a referral. Server capable of such chaining can mitigate this threat by limiting chaining to a particular group of authenticated entities. LDAP is frequently used for storage and distribution of security sensitive information, including access control and security policy information. Failure to use the Don't Use Copy control may thus permit an attacker to gain unauthorized access by allowing reliance on stale data. 5. IANA Considerations 5.1. Object Identifier It is requested that IANA assign upon Standards Action an LDAP Object Identifier [RFC4520] to identify the LDAP Don't Use Copy Control defined in this document. Subject: Request for LDAP Object Identifier Registration Person & email address to contact for further information: Kurt Zeilenga Specification: RFC XXXX Author/Change Controller: IESG Comments: Identifies the LDAP Don't Use Copy 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: Don't Use Copy Control Person & email address to contact for further information: Kurt Zeilenga Usage: Control Specification: RFC XXXX Author/Change Controller: IESG Comments: none Zeilenga LDAP Don't Use Copy Control [Page 4] INTERNET-DRAFT draft-zeilenga-ldap-dontusecopy-09 6 January 2011 6. Acknowledgements The author thanks Ben Campbell, Phillip Hallam-Baker, and Ted Hardie for providing review and specific suggestions. 7. Author's Address Kurt D. Zeilenga Isode Limited Email: Kurt.Zeilenga@Isode.COM 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. [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 Models", RFC 4512, June 2006. 8.2. Informative References [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). [X.511] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory: Abstract Service Definition", X.511(1993) (also ISO/IEC 9594-3:1993). Zeilenga LDAP Don't Use Copy Control [Page 5] INTERNET-DRAFT draft-zeilenga-ldap-dontusecopy-09 6 January 2011 [RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", RFC 4520, BCP 64, June 2006. Full Copyright Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Zeilenga LDAP Don't Use Copy Control [Page 6]