





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                                    17 May 2002



                        LDAP "Who am I?" Operation
                   <draft-zeilenga-ldap-authzid-06.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
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  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
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  Copyright 2002, The Internet Society.  All Rights Reserved.

  Please see the Copyright section near the end of this document for
  more information.


Abstract

  This specification provides a mechanism for Lightweight Directory
  Access Protocol (LDAP) clients to obtain the authorization identity
  which the server has associated with the user or application entity.
  This mechanism is specified as an LDAP extended operation called the
  LDAP "Who am I?" operation.



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Conventions

  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. Background and Intent of Use

  This specification describes a Lightweight Directory Access Protocol
  (LDAP) [RFC2251] extended operation which clients can use to obtain
  the primary authorization identity in its primary form which the
  server has associated with the user or application entity.

  Servers often associate multiple authorization identities with the
  client and each authorization identity may be represented by multiple
  authzId [RFC2829] strings.  This operation requests and returns the
  authzId the server considers to be primary.  In the specification, the
  term "the authorization identity" and "the authzid" are to generally
  read as "the primary authorization identity" and the "the primary
  authzid", respectively.

  This specification is intended to replace the existing [AUTHCTL]
  mechanism which uses Bind request and response controls to request and
  return the authorization identity.  Bind controls are not protected by
  the security layers established by the Bind operation which they are
  transferred as part of.  While it is possible to establish security
  layers prior to the Bind operation, it is often desirable to only use
  security layers established by the Bind operation.  An extended
  operation sent after a Bind operation is protected by the security
  layers established by the Bind operation.

  There are other cases where it is desirable to request the
  authorization identity which the server associated with the client
  separately from the Bind operation.  For example, the "Who am I?"
  operation can be augmented with a Proxied Authorization Control
  [PROXYCTL] to determine the authorization identity which the server
  associates with the identity asserted in the Proxied Authorization
  Control.  The "Who am I?" operation can also be used prior to the Bind
  operation.

  The LDAP "Who am I?" operation is named after the UNIX whoami(1)
  command.  The whoami(1) command displays the effective user id.


2. The "Who am I?" Operation

  The "Who am I?" operation is defined as an LDAP Extended Operation



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  [RFC2251, Section 4.12] identified by the whoamiOID Object Identifier
  (OID).  This section details the syntax of the operation's whoami
  request and response messages.

       whoamiOID ::= "1.3.6.1.4.1.4203.1.11.3"


2.1. The whoami Request

  The whoami request is an ExtendedRequest with the requestName field
  containing the whoamiOID OID and an absent requestValue field.  For
  example, a whoami request could be encoded as the sequence of octets
  (in hex):


2.2. The whoami Response

  The whoami response is an ExtendedResponse where the responseName
  field is absent and, if present, the response field is empty or an
  authzId [RFC2829].   For example, a whoami response returning the
  authzid "u:kurt@OPENLDAP.ORG" (in response to the example request)
  would be encoded as the sequence of octets (in hex):



3. Operational Semantics

  The function of the "Who am I?" operation is to request that the
  server returns the authorization identity it currently associates with
  the client.  The client requests this authorization identity by
  issuing a whoami Request.  The server responds to this request with a
  whoami Response.

  If the server is willing and able to provide the authorization
  identity it associates with the client, the server SHALL return a
  whoami Response with a success resultCode.  If the server is treating
  the client as an anonymous entity, the response field is empty.
  Otherwise the server is to provide the authzId [RFC2829] representing
  the authorization identity it currently associates with the client in
  the response field.

  If the server is unwilling or unable to provide the authorization
  identity it associates with the client, the server SHALL return a
  whoami Response with an appropriate non-success resultCode (such as
  operationsError, protocolError, confidentialityRequired,
  insufficientAccessRights, busy, unavailable, unwillingToPerform, or
  other) and an absent response field.




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  As described in [RFC2251] and [RFC2829], an LDAP session has an
  "anonymous" association until the client has been successfully
  authenticated using the Bind operation.  Clients MUST NOT invoke the
  "Who Am I?" operation while any Bind operation is in progress,
  including between two Bind requests made as part of a multi-stage Bind
  operation.


4. Extending the "Who am I?" operation with controls

  Future specifications may extend the "Who am I?" operation using the
  control mechanism.  When extended by controls, the "Who am I?"
  operation requests and returns the authorization identity the server
  associates with the client in a particular context indicated by the
  controls.


4.1. Proxied Authorization Control

  The Proxied Authorization Control [PROXYCTL] is used by clients to
  request that the operation it is attached to operates under the
  authorization of an assumed identity.  The client provides the
  identity to assume in the Proxied Authorization request control.  If
  the client is authorized to assume the requested identity, the server
  executes the operation as if the requested identity had issued the
  operation.

  As servers often map the asserted authzId to another identity
  [RFC2829], it is desirable to request the server provide the authzId
  it associates with the assumed identity.

  When a Proxied Authorization Control is be attached to the "Who Am I?"
  operation, the operation requests the return of the authzid the server
  associates with the identity asserted in the Proxied Authorization
  Control.  The TBD result code is used to indicate that the server does
  not allow the client to assume the asserted identity.  [[Note to RFC
  Editor: TBD is to be replaced with the name/code assigned by IANA for
  [PROXYCTL] use.]]


5. Security Considerations

  Identities associated with users may be sensitive information.  When
  so, security layers [RFC2829][RFC2830] should be established to
  protect this information.  This mechanism is specifically designed to
  allow security layers established by a Bind operation to protect the
  integrity and/or confidentiality of the authorization identity.




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  Servers may place access control or other restrictions upon the use of
  this operation.

  As with any other extended operations, general LDAP considerations
  apply.  These are detailed in [RFC2251], [RFC2829], and [RFC2830].


6. IANA Considerations

  No IANA assignments are requested.

  This document uses the OID 1.3.6.1.4.1.4203.1.11.3 to identify the
  LDAP "Who Am I? extended operation.  This OID was assigned [ASSIGN] by
  OpenLDAP Foundation under its IANA assigned private enterprise
  allocation [PRIVATE] for use in this specification.


7. Acknowledgment

  This document borrows from prior work in this area including
  "Authentication Response Control" [AUTHCTL] by Rob Weltman, Mark Smith
  and Mark Wahl.


8. Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation
  <Kurt@OpenLDAP.org>


9. Normative References

  [RFC2119]  S. Bradner, "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14 (also RFC 2119), March 1997.

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

  [RFC2829]  M. Wahl, H. Alvestrand, J. Hodges, RL "Bob" Morgan,
             "Authentication Methods for LDAP", RFC 2829, June 2000.

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

  [PROXYCTL] R. Weltman, "LDAP Proxied Authentication Control", draft-
             weltman-ldapv3-proxy-xx.txt (a work in progress).



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10. Informative References

  [ASSIGN]   OpenLDAP Foundation, "OpenLDAP OID Delegations",
             http://www.openldap.org/foundation/oid-delegate.txt.

  [AUTHCTL]  R. Weltman, M. Smith, M. Wahl, "LDAP Authentication
             Response Control", draft-weltman-ldapv3-auth-response-
             xx.txt (a work in progress).

  [PRIVATE]  IANA, "Private Enterprise Numbers",
             http://www.iana.org/assignments/enterprise-numbers.


Copyright 2002, The Internet Society.  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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  the copyright notice or references to the Internet Society or other
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  ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
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  INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
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