





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                                1 November 2002



                        LDAP "Who am I?" Operation
                   <draft-zeilenga-ldap-authzid-08.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 <ldapext@ietf.org>.  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
  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/ietf/1id-abstracts.txt>. The list of
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  <http://www.ietf.org/shadow.html>.

  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) [RFC3377] 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.  The operation is
  called the "Who am I?" operation.

  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 using Start TLS [RFC2830] prior to the Bind operation, it is
  often desirable to 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.

  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 generally to
  be read as "the primary authorization identity" and the "the primary
  authzId", respectively.


2. The "Who am I?" Operation

  The "Who am I?" operation is defined as an LDAP Extended Operation
  [RFC2251, Section 4.12] identified by the whoamiOID Object Identifier
  (OID).  This section details the syntax of the operation's whoami



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  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):

      30 1e 02 01 02 77 19 80  17 31 2e 33 2e 36 2e 31
      2e 34 2e 31 2e 34 32 30  33 2e 31 2e 31 31 2e 33


2.2. The whoami Response

  The whoami response is an ExtendedResponse where the responseName
  field is absent and the response field, if present, 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):

      30 21 02 01 02 78 1c 0a  01 00 04 00 04 00 8b 13
      75 3a 6b 75 72 74 40 4f  50 45 4e 4c 44 41 50 2e
      4f 52 47


3. Operational Semantics

  The "Who am I?" operation provides a mechanism, a whoami Request, for
  the client to request that the server returns the authorization
  identity it currently associates with the client and provides a
  mechanism, a whoami Response, for the server to respond to that
  request.

  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 present but
  empty.  Otherwise the server provides 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



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  operationsError, protocolError, confidentialityRequired,
  insufficientAccessRights, busy, unavailable, unwillingToPerform, or
  other) and an absent response field.

  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 [RFC2251].  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



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  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.

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

  As with any other extended operations, general LDAP security
  considerations [RFC3377] apply.


6. IANA Considerations

  This 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.

  Registration of this protocol mechansism is requested [RFC3383].

  Subject: Request for LDAP Protocol Mechansism Registration

  Object Identifier: 1.3.6.1.4.1.4203.1.11.3

  Description: Who am I?

  Person & email address to contact for further information:
       Kurt Zeilenga <kurt@openldap.org>

  Usage: Extended Operation

  Specification: RFCxxxx

  Author/Change Controller: IESG

  Comments: none


7. Acknowledgment

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

  The LDAP "Who am I?" operation takes it name from the UNIX whoami(1)
  command.  The whoami(1) command displays the effective user id.





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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.

  [RFC3377]  J. Hodges, R. Morgan, "Lightweight Directory Access
             Protocol (v3): Technical Specification", RFC 3377,
             September 2002.

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


10. Informative References

  [RFC3383]  K. Zeilenga, "IANA Considerations for LDAP", BCP 64 (also
             RFC 3383), September 2002.

  [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.




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