LDAP Password Modify Extended Operation

Network Working Group                                        K. Zeilenga
Request for Comments: 3062                           OpenLDAP Foundation
Category: Standards Track                                  February 2001


                LDAP Password Modify Extended Operation

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   The integration of the Lightweight Directory Access Protocol (LDAP)
   and external authentication services has introduced non-DN
   authentication identities and allowed for non-directory storage of
   passwords.  As such, mechanisms which update the directory (e.g.,
   Modify) cannot be used to change a user's password.  This document
   describes an LDAP extended operation to allow modification of user
   passwords which is not dependent upon the form of the authentication
   identity nor the password storage mechanism used.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are
   to be interpreted as described in RFC 2119.

1.  Background and Intent of Use

   Lightweight Directory Access Protocol (LDAP) [RFC2251] is designed to
   support an number of authentication mechanisms including simple user
   name/password pairs.  Traditionally, LDAP users where identified by
   the Distinguished Name [RFC2253] of a directory entry and this entry
   contained a userPassword [RFC2256] attribute containing one or more
   passwords.

   The protocol does not mandate that passwords associated with a user
   be stored in the directory server.  The server may use any attribute
   suitable for password storage (e.g., userPassword), or use non-
   directory storage.

   The integration [RFC2829] of application neutral SASL [RFC2222]
   services which support simple username/password mechanisms (such as
   DIGEST-MD5) has introduced non-LDAP DN authentication identity forms
   and made storage of passwords the responsibility of the SASL service
   provider.

   LDAP update operations are designed to act upon attributes of an
   entry within the directory.  LDAP update operations cannot be used to
   modify a user's password when the user is not represented by a DN,
   does not have a entry, or when that password used by the server is
   not stored as an attribute of an entry.  An alternative mechanism is
   needed.

   This document describes an LDAP Extended Operation intended to allow
   directory clients to update user passwords.  The user may or may not
   be associated with a directory entry.  The user may or may not be
   represented as an LDAP DN.  The user's password may or may not be
   stored in the directory.

   The operation SHOULD NOT be used without adequate security protection
   as the operation affords no privacy or integrity protect itself.
   This operation SHALL NOT be used anonymously.

2.  Password Modify Request and Response

   The Password Modify operation is an LDAPv3 Extended Operation
   [RFC2251, Section 4.12] and is identified by the OBJECT IDENTIFIER
   passwdModifyOID.  This section details the syntax of the protocol
   request and response.

   passwdModifyOID OBJECT IDENTIFIER ::= 1.3.6.1.4.1.4203.1.11.1

   PasswdModifyRequestValue ::= SEQUENCE {
     userIdentity    [0]  OCTET STRING OPTIONAL
     oldPasswd       [1]  OCTET STRING OPTIONAL
     newPasswd       [2]  OCTET STRING OPTIONAL }

   PasswdModifyResponseValue ::= SEQUENCE {
     genPasswd       [0]     OCTET STRING OPTIONAL }

2.1.  Password Modify Request

   A Password Modify request is an ExtendedRequest with the requestName
   field containing passwdModifyOID OID and optionally provides a
   requestValue field.  If the requestValue field is provided, it SHALL
   contain a PasswdModifyRequestValue with one or more fields present.

   The userIdentity field, if present, SHALL contain an octet string
   representation of the user associated with the request.  This string
   may or may not be an LDAPDN [RFC2253].  If no userIdentity field is
   present, the request acts up upon the password of the user currently
   associated with the LDAP session.

   The oldPasswd field, if present, SHALL contain the user's current
   password.

   The newPasswd field, if present, SHALL contain the desired password
   for this user.

2.2.  Password Modify Response

   A Password Modify response is an ExtendedResponse where the
   responseName field is absent and the response field is optional.  The
   response field, if present, SHALL contain a PasswdModifyResponseValue
   with genPasswd field present.

   The genPasswd field, if present, SHALL contain a generated password
   for the user.

   If an resultCode other than success (0) is indicated in the response,
   the response field MUST be absent.

3.  Operation Requirements

   Clients SHOULD NOT submit a Password Modification request without
   ensuring adequate security safeguards are in place.  Servers SHOULD
   return a non-success resultCode if sufficient security protection are
   not in place.

   Servers SHOULD indicate their support for this extended operation by
   providing PasswdModifyOID as a value of the supportedExtension
   attribute type in their root DSE.  A server MAY choose to advertise
   this extension only when the client is authorized and/or has
   established the necessary security protections to use this operation.
   Clients SHOULD verify the server implements this extended operation
   prior to attempting the operation by asserting the supportedExtension
   attribute contains a value of PasswdModifyOID.

   The server SHALL only return success upon successfully changing the
   user's password.  The server SHALL leave the password unmodified and
   return a non-success resultCode otherwise.

   If the server does not recognize provided fields or does not support
   the combination of fields provided, it SHALL NOT change the user
   password.

   If oldPasswd is present and the provided value cannot be verified or
   is incorrect, the server SHALL NOT change the user password.  If
   oldPasswd is not present, the server MAY use other policy to
   determine whether or not to change the password.

   The server SHALL NOT generate a password on behalf of the client if
   the client has provided a newPasswd.  In absence of a client provided
   newPasswd, the server SHALL either generate a password on behalf of
   the client or return a non-success result code.  The server MUST
   provide the generated password upon success as the value of the
   genPasswd field.

   The server MAY return adminLimitExceeded, busy,
   confidentialityRequired, operationsError, unavailable,
   unwillingToPerform, or other non-success resultCode as appropriate to
   indicate that it was unable to successfully complete the operation.

   Servers MAY implement administrative policies which restrict this
   operation.

4.  Security Considerations

   This operation is used to modify user passwords.  The operation
   itself does not provide any security protection to ensure integrity
   and/or confidentiality of the information.  Use of this operation is
   strongly discouraged when privacy protections are not in place to
   guarantee confidentiality and may result in the disclosure of the
   password to unauthorized parties.  This extension MUST be used with
   confidentiality protection, such as Start TLS [RFC 2830].  The NULL
   cipher suite MUST NOT be used.

5. Bibliography

   [RFC2219]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2222]  Myers, J., "Simple Authentication and Security Layer
              (SASL)", RFC 2222, October 1997.

   [RFC2251]  Wahl, M., Howes, T. and S. Kille, "Lightweight Directory
              Access Protocol (v3)", RFC 2251, December 1997.

   [RFC2252]  Wahl, M., Coulbeck, A., Howes, T. and S. Kille,
              "Lightweight Directory Access Protocol (v3): Attribute
              Syntax Definitions", RFC 2252, December 1997.

   [RFC2253]  Wahl, M., Kille,S. and T. Howes, "Lightweight Directory
              Access Protocol (v3): UTF-8 String Representation of
              Distinguished Names", RFC 2253, December 1997.

   [RFC2256]  Wahl, M., "A Summary of the X.500(96) User Schema for use
              with LDAPv3", RFC 2256, December 1997.

   [RFC2829]  Wahl, M., Alvestrand, H., Hodges, J. and R. Morgan,
              "Authentication Methods for LDAP", RFC 2829, May 2000.

   [RFC2830]  Hodges, J., Morgan, R. and M. Wahl, "Lightweight Directory
              Access Protocol (v3): Extension for Transport Layer
              Security", RFC 2830, May 2000.

6.  Acknowledgment

   This document borrows from a number of IETF documents and is based
   upon input from the IETF LDAPext working group.

7.  Author's Address

   Kurt D. Zeilenga
   OpenLDAP Foundation

   EMail: Kurt@OpenLDAP.org

8.  Full Copyright Statement

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

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