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<pre>Network Working Group K. Zeilenga
Request for Comments: 4532 OpenLDAP Foundation
Category: Standards Track June 2006
<span class="h1">Lightweight Directory Access Protocol (LDAP)</span>
<span class="h1">"Who am I?" Operation</span>
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 (2006).
Abstract
This specification provides a mechanism for Lightweight Directory
Access Protocol (LDAP) clients to obtain the authorization identity
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.
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Background and Intent of Use</span>
This specification describes a Lightweight Directory Access Protocol
(LDAP) [<a href="./rfc4510" title=""Lightweight Directory Access Protocol (LDAP): Technical Specification Road Map"">RFC4510</a>] operation that clients can use to obtain the primary
authorization identity, in its primary form, that 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 Authorization
Identity Controls [<a href="./rfc3829" title=""Lightweight Directory Access Protocol (LDAP) Authorization Identity Request and Response Controls"">RFC3829</a>] mechanism, which uses Bind request and
response controls to request and return the authorization identity.
Bind controls are not protected by security layers established by the
Bind operation that includes them. While it is possible to establish
security layers using StartTLS [<a href="./rfc4511" title=""Lightweight Directory Access Protocol (LDAP): The Protocol"">RFC4511</a>][RFC4513] 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.
<span class="grey">Zeilenga Standards Track [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
There are other cases where it is desirable to request the
authorization identity that 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
[<a href="./rfc4370" title=""Lightweight Directory Access Protocol (LDAP) Proxied Authorization Control"">RFC4370</a>] to determine the authorization identity that 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 [<a href="./rfc4513" title=""Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms"">RFC4513</a>] strings. This operation requests and
returns the authzId that the server considers 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.
<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>. Conventions Used in This Document</span>
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 <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a> [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. The "Who am I?" Operation</span>
The "Who am I?" operation is defined as an LDAP Extended Operation
[<a href="./rfc4511" title=""Lightweight Directory Access Protocol (LDAP): The Protocol"">RFC4511</a>] 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"
<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>. The whoami Request</span>
The whoami request is an ExtendedRequest with a 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
<span class="grey">Zeilenga Standards Track [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>. The whoami Response</span>
The whoami response is an ExtendedResponse where the responseName
field is absent and the response field, if present, is empty or an
authzId [<a href="./rfc4513" title=""Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms"">RFC4513</a>]. For example, a whoami response returning the
authzId "u:xxyyz@EXAMPLE.NET" (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 78 78 79 79 7a 40 45 58 41 4d 50 4c 45 2e
4e 45 54
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Operational Semantics</span>
The "Who am I?" operation provides a mechanism, a whoami Request, for
the client to request that the server return the authorization
identity it currently associates with the client. It also provides a
mechanism, a whoami Response, for the server to respond to that
request.
Servers indicate their support for this extended operation by
providing a whoamiOID object identifier as a value of the
'supportedExtension' attribute type in their root DSE. The server
SHOULD advertise this extension only when the client is willing and
able to perform this operation.
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 [<a href="./rfc4513" title=""Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms"">RFC4513</a>]
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.
As described in [<a href="./rfc4511" title=""Lightweight Directory Access Protocol (LDAP): The Protocol"">RFC4511</a>] and [<a href="./rfc4513" title=""Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms"">RFC4513</a>], 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
<span class="grey">Zeilenga Standards Track [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
Bind operation. Where a whoami Request is received in violation of
this absolute prohibition, the server should return a whoami Response
with an operationsError resultCode.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Extending the "Who am I?" Operation with Controls</span>
Future specifications may extend the "Who am I?" operation using the
control mechanism [<a href="./rfc4511" title=""Lightweight Directory Access Protocol (LDAP): The Protocol"">RFC4511</a>]. 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.
<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Proxied Authorization Control</span>
The Proxied Authorization Control [<a href="./rfc4370" title=""Lightweight Directory Access Protocol (LDAP) Proxied Authorization Control"">RFC4370</a>] is used by clients to
request that the operation it is attached to operate 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
[<a href="./rfc4513" title=""Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms"">RFC4513</a>], it is desirable to request that 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 authorizationDenied (123) result code is
used to indicate that the server does not allow the client to assume
the asserted identity.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Security Considerations</span>
Identities associated with users may be sensitive information. When
they are, security layers [<a href="./rfc4511" title=""Lightweight Directory Access Protocol (LDAP): The Protocol"">RFC4511</a>][RFC4513] 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.
Servers may place access control or other restrictions upon the use
of this operation. As stated in <a href="#section-3">Section 3</a>, the server SHOULD
advertise this extension when it is willing and able to perform the
operation.
As with any other extended operations, general LDAP security
considerations [<a href="./rfc4510" title=""Lightweight Directory Access Protocol (LDAP): Technical Specification Road Map"">RFC4510</a>] apply.
<span class="grey">Zeilenga Standards Track [Page 4]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-5" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. IANA Considerations</span>
The OID 1.3.6.1.4.1.4203.1.11.3 is used to identify the LDAP "Who am
I?" extended operation. This OID was assigned [<a href="#ref-ASSIGN" title=""OpenLDAP OID Delegations"">ASSIGN</a>] by the
OpenLDAP Foundation, under its IANA-assigned private enterprise
allocation [<a href="#ref-PRIVATE" title=""Private Enterprise Numbers"">PRIVATE</a>], for use in this specification.
Registration of this protocol mechanism [<a href="./rfc4520" title=""Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)"">RFC4520</a>] has been completed
by the IANA.
Subject: Request for LDAP Protocol Mechanism 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: <a href="./rfc4532">RFC 4532</a>
Author/Change Controller: IESG
Comments: none
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Acknowledgement</span>
This document borrows from prior work in this area, including
"Authentication Response Control" [<a href="./rfc3829" title=""Lightweight Directory Access Protocol (LDAP) Authorization Identity Request and Response Controls"">RFC3829</a>] by Rob Weltman, Mark
Smith, and Mark Wahl.
The LDAP "Who am I?" operation takes it's name from the UNIX
whoami(1) command. The whoami(1) command displays the effective user
ID.
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. References</span>
<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>. Normative References</span>
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC4370">RFC4370</a>] Weltman, R., "Lightweight Directory Access Protocol (LDAP)
Proxied Authorization Control", <a href="./rfc4370">RFC 4370</a>, February 2006.
[<a id="ref-RFC4510">RFC4510</a>] Zeilenga, K., Ed., "Lightweight Directory Access Protocol
(LDAP): Technical Specification Road Map", <a href="./rfc4510">RFC 4510</a>, June
2006.
[<a id="ref-RFC4511">RFC4511</a>] Sermersheim, J., Ed., "Lightweight Directory Access
Protocol (LDAP): The Protocol", <a href="./rfc4511">RFC 4511</a>, June 2006.
<span class="grey">Zeilenga Standards Track [Page 5]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-6" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
[<a id="ref-RFC4513">RFC4513</a>] Harrison, R., Ed., "Lightweight Directory Access Protocol
(LDAP): Authentication Methods and Security Mechanisms",
<a href="./rfc4513">RFC 4513</a>, June 2006.
<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>. Informative References</span>
[<a id="ref-RFC3829">RFC3829</a>] Weltman, R., Smith, M., and M. Wahl, "Lightweight Directory
Access Protocol (LDAP) Authorization Identity Request and
Response Controls", <a href="./rfc3829">RFC 3829</a>, July 2004.
[<a id="ref-RFC4520">RFC4520</a>] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
Considerations for the Lightweight Directory Access
Protocol (LDAP)", <a href="https://www.rfc-editor.org/bcp/bcp64">BCP 64</a>, <a href="./rfc4520">RFC 4520</a>, June 2006.
[<a id="ref-ASSIGN">ASSIGN</a>] OpenLDAP Foundation, "OpenLDAP OID Delegations",
<a href="http://www.openldap.org/foundation/oid-delegate.txt">http://www.openldap.org/foundation/oid-delegate.txt</a>.
[<a id="ref-PRIVATE">PRIVATE</a>] IANA, "Private Enterprise Numbers",
<a href="http://www.iana.org/assignments/enterprise-numbers">http://www.iana.org/assignments/enterprise-numbers</a>.
Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
EMail: Kurt@OpenLDAP.org
<span class="grey">Zeilenga Standards Track [Page 6]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-7" ></span>
<span class="grey"><a href="./rfc4532">RFC 4532</a> LDAP "Who am I?" Operation June 2006</span>
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a>, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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Copies of IPR disclosures made to the IETF Secretariat and any
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The IETF invites any interested party to bring to its attention any
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Acknowledgement
Funding for the RFC Editor function is provided by the IETF
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Zeilenga Standards Track [Page 7]
</pre>
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