INTERNET-DRAFT Rob Weltman
Intended Category: Informational Mark Smith
Netscape Communications Corp.
Mark Wahl
Sun Microsystems, Inc.
April 2003
LDAP Authorization Identity Request and Response Controls
draft-weltman-ldapv3-auth-response-09.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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(IETF), its areas, and its working groups. Note that other groups
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The list of current Internet-Drafts can be accessed at
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Abstract
This document extends the Lightweight Directory Access Protocol
(LDAP) [RFC3377] bind [LDAPPROT] operation with a mechanism for
requesting and returning the authorization identity it establishes.
Specifically, this document defines the Authorization Identity
Request and Response controls for use with the Bind operation.
1. Introduction
This document defines support for the Authorization Identity Request
Control and the Authorization Identity Response Control for
requesting and returning the authorization established in a bind
operation. The Authorization Identity Request Control may be
submitted by a client in a bind request if authenticating with
version 3 of the Lightweight Directory Access Protocol (LDAP)
protocol [LDAPv3]. In the LDAP server's bind response, it may then
include an Authorization Identity Response Control. The response
control contains the identity assumed by the client. This is useful
when there is a mapping step or other indirection during the bind, so
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that the client can be told what LDAP identity was granted. Client
authentication with certificates is the primary situation where this
applies. Also, some Simple Authentication and Security Layer (SASL)
authentication mechanisms may not involve the client explicitly
providing a DN, or may result in an authorization identity which is
different from the authentication identity provided by the client
[AUTH].
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
used in this document are to be interpreted as described in
[RFCKeyWords].
2. Publishing support for the Authorization Identity Request Control
and the Authorization Identity Response Control
Support for the Authorization Identity Request Control and the
Authorization Identity Response Control is indicated by the presence
of the Object Identifiers (OIDs) 2.16.840.1.113730.3.4.16 and
2.16.840.1.113730.3.4.15, respectively, in the supportedControl
attribute [LDAPATTRS] of a server's root DSE.
3. Authorization Identity Request Control
This control MAY be included in any bind request which specifies
protocol version 3, as part of the controls field of the LDAPMessage
as defined in [LDAPPROT]. In a multi-step bind operation, the client
MUST provide the control with each bind request.
The controlType is "2.16.840.1.113730.3.4.16" and the controlValue is
absent.
4. Authorization Identity Response Control
This control MAY be included in any final bind response where the
first bind request of the bind operation included an Authorization
Identity Request Control as part of the controls field of the
LDAPMessage as defined in [LDAPPROT].
The controlType is "2.16.840.1.113730.3.4.15". If the bind request
succeeded and resulted in an identity (not anonymous), the
controlValue contains the authorization identity (authzId), as
defined in [AUTH] section 9, granted to the requestor. If the bind
request resulted in an anonymous association, the controlValue field
is a string of zero length. If the bind request resulted in more than
one authzId, the primary authzId is returned in the controlValue
field.
The control is only included in a bind response if the resultCode for
the bind operation is success.
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If the server requires confidentiality protections to be in place
prior to use of this control (see Security Considerations), the
server reports failure to have adequate confidentiality protections
in place by returning the confidentialityRequired result code.
If the client has insufficient access rights to the requested
authorization information, the server reports this by returning the
insufficientAccessRights result code.
Identities presented by a client as part of the authentication
process may be mapped by the server to one or more authorization
identities. The bind response control can be used to retrieve the
primary authzId.
For example, during client authentication with certificates [AUTH], a
client may possess more than one certificate and not be able to
determine which one was ultimately selected for authentication to the
server. The subject DN field in the selected certificate may not
correspond exactly to a DN in the directory, but rather have gone
through a mapping process controlled by the server. On completing the
certificate-based authentication, the client may issue a SASL [SASL]
bind request, specifying the EXTERNAL mechanism and including an
Authorization Identity Request Control. The bind response MAY include
an Authorization Identity Response Control indicating the DN in the
server's DIT which the certificate was mapped to.
5. Alternative Approach with Extended Operation
The LDAP "Who am I?" [AUTHZID] extended operation provides a
mechanism to query the authorization identity associated with a bound
connection. Using an extended operation as opposed to a bind response
control allows a client to learn the authorization identity after the
bind has has established integrity and data confidentiality
protections. The disadvantages of the extended operation approach are
coordination issues between "Who am I?" requests, bind requests, and
other requests, and that an extra operation is required to learn the
authorization identity. For multithreaded or high bandwidth server
application environments, the bind response approach may be
preferable.
6. Security Considerations
The Authorization Identity Request and Response Controls are subject
to standard LDAP security considerations. The controls may be passed
over a secure as well as over an insecure channel. They are not
protected by security layers negotiated by the bind operation.
The response control allows for an additional authorization identity
to be passed. In some deployments, these identities may contain
confidential information which require privacy protection. In such
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deployments, a security layer should be established prior to issuing
a bind request with an Authorization Identity Request Control.
7. IANA Considerations
The OIDs 2.16.840.1.113730.3.4.16 and 2.16.840.1.113730.3.4.15 are
reserved for the Authorization Identity Request and Response
Controls, respectively. The Authorization Identity Request Control is
to be registered as an LDAP Protocol Mechanism [IANALDAP].
8. Copyright
Copyright (C) The Internet Society (2003). 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
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
9. References
[LDAPV3] Hodges, J. and R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377, September
2002.
[LDAPPROT] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol (v3)", RFC 2251, December 1997.
[RFCKeyWords] Bradner, Scott, "Key Words for use in RFCs to Indicate
Requirement Levels", draft-bradner-key-words-03.txt, January
1997.
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[AUTH] M. Wahl, H. Alvestrand, J. Hodges, RL "Bob" Morgan,
"Authentication Methods for LDAP", RFC 2829, May 2000.
[SASL] J. Myers, "Simple Authentication and Security Layer (SASL",
RFC 2222, October 1997.
[AUTHZID] K. Zeilenga, "LDAP 'Who am I?' Operation", draft-zeilenga-
ldap-authzid-03.txt, April 2002
[LDAPATTRS] M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight
Directory Access Protocol (v3): Attribute Syntax Definitions",
RFC 2252, December 1997
[IANALDAP] J. Hodges, R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377, September
2002
10. Author's Addresses
Rob Weltman
Netscape Communications Corp.
360 W. Caribbean Drive
Sunnyvale, CA 94089
USA
+1 650 937-3194
rweltman@netscape.com
Mark Smith
Netscape Communications Corp.
360 W. Caribbean Drive
Sunnyvale, CA 94089
USA
+1 650 937-3477
mcs@netscape.com
Mark Wahl
Sun Microsystems, Inc.
911 Capital of Texas Hwy, Suite 4140
Austin, TX 78759
USA
+1 512 231 7224
Mark.Wahl@sun.com
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