INTERNET-DRAFT Rob Weltman
Intended Category: Standards Track Mark Smith
Netscape Communications Corp.
Mark Wahl
Sun Microsystems, Inc.
November, 2001
LDAP Authentication Response Control
draft-weltman-ldapv3-auth-response-05.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Task Force
(IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
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The list of current Internet-Drafts can be accessed at
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Abstract
This document defines support for the Authentication Request Control
and the Authentication Response Control. Controls are an LDAP
protocol version 3 extension, to allow passing arbitrary control
information along with a standard request to a server, and to receive
arbitrary information back with a standard result. The Authentication
Request Control may be submitted by a client in a bind request if
authenticating with version 3 of the LDAP protocol. In the LDAP
server's bind response, it may then include an Authentication
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 that the client can be told what LDAP
identity was granted. Client authentication with certificates is the
primary situation where this applies. Also, some 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].
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1. Introduction
Version 3 of the LDAP protocol provides a means of supplying
arbitrary additional information along with a request to an LDAP
server, and receiving arbitrary additional response information. The
Control protocol extension is described in [LDAPv3], section 4.1.12.
This document defines a way for a server to return the identity
assumed by a client on binding using the Control mechanism.
The key words "MUST", "SHOULD", and "MAY" used in this document are
to be interpreted as described in [RFCKeyWords].
2. Publishing support for the Authentication Request Control and the
Authentication Response Control
Support for the Authentication Request Control and the Authentication
Response Control is indicated by the presence of the OIDs
2.16.840.1.113730.3.4.16 and 2.16.840.1.113730.3.4.15, respectively,
in the supportedControl attribute of a server's root DSE.
3. Authentication 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 [LDAPv3]. In a multi-step bind operation, the server
SHOULD ignore occurrences of the control in bind requests other than
the initial one.
The controlType is "2.16.840.1.113730.3.4.16" and the controlValue is
absent.
4. Authentication Response Control
This control may be included in any final bind response where the
first bind request of the bind operation included an Authentication
Request Control as part of the controls field of the LDAPMessage as
defined in [LDAPv3].
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 anonymous authentication, the controlValue field
is a string of zero length.
If the bind request failed, the control is not included in the bind
response.
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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
Authentication Request Control. The bind response MAY include an
Authentication Response Control indicating the DN in the server's DIT
which the certificate was mapped to.
5. Security Considerations
The Authentication Response Control is subject to standard LDAP
security considerations. The control may be passed over a secure as
well as over an insecure channel. It is not protected by security
layers negotiated by the bind operation.
The 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
deployments, a security layer should be established prior to issuing
a bind request with an Authentication Request Control.
6. Copyright
Copyright (C) The Internet Society (2000). 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
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
7. Bibliography
[LDAPv3] 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.
[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.
[ASN.1] X.680 : ITU-T Recommendation X.680 (1997) | ISO/IEC 8824-
1:1998, Information Technology - Abstract Syntax Notation One
(ASN.1): Specification of Basic Notation
8. Author's Addresses
Rob Weltman
Netscape Communications Corp.
466 Ellis Street
Mountain View, CA 94043
USA
+1 650 937-3194
rweltman@netscape.com
Mark Smith
Netscape Communications Corp.
466 Ellis Street
Mountain View, CA 94043
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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9. Revision history
9.1 Changes from draft-weltman-ldapv3-auth-response-04.txt
Authentication Request Control
Removed clause saying that the control may not be marked critical.
Added sentence stating that the server should ignore authentication
request controls other than on the first bind request in a multi-step
bind operation.
Authentication Response Control
Added "(authzId)" to "authorization identity".
Security Considerations
Added a sentence recommending that a security layer be negotiated
before issuing a bind request with the authentication request control
in deployments where the authorization identity requires privacy
protection.
9.2 No Changes from draft-weltman-ldapv3-auth-response-03.txt
No changes
9.3 Changes from draft-weltman-ldapv3-auth-response-02.txt
Publishing support
The controls are published in supportedControl, not
supportedExtension.
Authentication Response Control
The value of an Authentication Response Control is an authorization
identity, not necessarily a DN.
Security Considerations
Added a short discussion of the fact that an identity is exposed in
the response control.
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Miscellaneous
Eliminated BNF for control contents.
9.4 Changes from draft-weltman-ldapv3-auth-response-01.txt
Authentication Request Control
An Authentication Response Control is now only returned if the client
requested one by submitting an Authentication Request Control.
Contents of Authentication Response Control
Rather than returning both the authentication DN and the
authentication mechanism, the control only returns the authentication
DN.
9.5 Changes from draft-weltman-ldapv3-auth-response-00.txt
Capitalization of ASN.1 macros
AuthResponseControl and AuthResponseValue are capitalized.
Clarifications
Added sentence on behavior for anonymous binds.
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