INTERNET-DRAFT Rob Weltman
Intended Category: Standards Track Netscape Communications Corp.
April 2002
LDAP Proxied Authorization Control
draft-weltman-ldapv3-proxy-10.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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Abstract
This document defines the Lightweight Directory Access Protocol
(LDAP) Proxied Authorization Control. The Proxied Authorization
Control allows a client to request that an operation be processed
under a provided authorization identity [AUTH] instead of as the
current authorization identity associated with the connection.
1. Introduction
This document defines support for proxied authorization using the
Control mechanism. LDAP [LDAPV3] supports the use of SASL [SASL] for
authentication and for supplying an authorization identity distinct
from the authentication identity, where the authorization identity
applies to the whole LDAP session. The proposed Proxied Authorization
Control provides a mechanism for specifying an authorization identity
on a per operation basis, benefiting clients that need to efficiently
perform operations on behalf of multiple users.
The key words "MUST", "SHOULD", and "MAY" used in this document are
to be interpreted as described in [KEYWORDS].
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2. Publishing support for the Proxied Authorization Control
Support for the Proxied Authorization Control is indicated by the
presence of the OID "2.16.840.1.113730.3.4.18" in the
supportedControl attribute of a server's root DSE.
3. Proxied Authorization Control
A single Proxied Authorization Control may be included in any
search, compare, modify, add, delete, modDN or extended operation
request message (with the exception of any extension that causes a
change in authentication, authorization, or data confidentiality
[RFC 2828], such as startTLS) as part of the controls field of the
LDAPMessage, as defined in [LDAPV3].
The controlType of the proxied authorization control is
"2.16.840.1.113730.3.4.18".
The criticality MUST be present and MUST be TRUE. This requirement
protects clients from submitting a request that is executed with an
unintended authorization identity.
The control value is either an LDAPString [LDAPv3] containing an
authzId as defined in section 9 of [AUTH] to use as the authorization
identity for the request, or an empty value if the anonymous identity
is to be used.
4. Permission to execute as proxy
An LDAP server supporting the Proxied Authorization Control may
choose to honor or not honor a particular request. If the control is
supported but a particular request is denied, the server MUST return
the error code insufficientAccessRights.
The mechanism for determining proxy access rights is server-specific.
A typical implementation will evaluate if the requester has proxy
access rights at the base DN of the request. If the requester has
proxy access rights, and if the authorization identity is recognized
by the server, the request will be honored. If the request is
honored, it will be executed as if submitted by the proxied
authorization identity. The result code TBD is returned if the client
is not authorized to adopt the requested authorization identity.
[Note to the IESG/IANA/RFC Editor: the value TBD is to be replaced
with an IANA assigned LDAP Result Code (see draft-ietf-ldapbis-iana-
xx.txt, Section 3.5)]
The interaction of proxied authorization access control and normal
access control is illustrated here for the case of search requests.
During evaluation of a search request, an entry which would have been
returned for the search if submitted by the proxied authorization
identity directly may not be returned if the server finds that the
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requester does not have proxy rights to the entry, even if the entry
is within the scope of a search request under a base DN which does
imply such rights. This means that fewer results, or no results, may
be returned compared to the case where the proxied authorization
identity issued the request directly. An example of such a case may
be a system with fine-grained access control, where the proxy right
requester has proxy rights at the top of a search tree, but not at or
below a point or points within the tree.
5. Security Considerations
The Proxied Authorization Control method is subject to general LDAP
security considerations [LDAPV3] [AUTH] [LDAPTLS]. The control may be
passed over a secure as well as over an insecure channel.
The control allows for an additional authorization identity to be
passed. In some deployments, these identities may contain
confidential information which require privacy protection.
Note that the server is responsible for determining if a proxied
authorization request is to be honored. "Anonymous" users SHOULD NOT
be allowed to assume the identity of others.
6. Copyright
Copyright (C) The Internet Society (date). 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.
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7. Bibliography
[LDAPV3] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol (v3)", RFC 2251, December 1997.
[KEYWORDS] 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, R. Morgan, "Authentication
Methods for LDAP", RFC 2829, May 2000
[SASL] J. Myers, "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997
[AUTH] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan, "Authentication
Methods for LDAP", RFC 2829, May 2000
[LDAPTLS] J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory
Access Protocol (v3): Extension for Transport Layer Security",
RFC 2830, May 2000
8. Author's Address
Rob Weltman
Netscape Communications Corp.
466 Ellis Street
Mountain View, CA 94043
USA
+1 650 937-3194
rweltman@netscape.com
9. Acknowledgements
Mark Smith of Netscape Communications Corp., Mark Wahl of Sun
Microsystems, Inc, Kurt Zeilenga of OpenLDAP Foundation, and Jim
Sermersheim of Novell have contributed with reviews of this draft.
10. Revision History
10.1 Changes from draft-weltman-ldapv3-proxy-09.txt
Removed description of Control mechanism from Abstract.
Added description of how this is different from SASL authz to the
Introduction.
Reworded description of the value of the control (no semantic
changes).
Added new result code TBD for failure to acquire proxy rights.
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Added references to RFCs 2829 and 2830 in Security section.
10.2 Changes from draft-weltman-ldapv3-proxy-08.txt
Proxied Authorization Control
Clarifications: the control may not be submitted with a startTLS
request; an empty controlValue implies the anonymous identity; only
one control may be included with a request.
Permission to execute as proxy
Replaced "proxy identity" with "proxied authorization identity".
Security Considerations
Added statement that anonymous users should not be allowed to assume
the identity of others.
10.3 Changes from draft-weltman-ldapv3-proxy-07.txt
Proxied Authorization Control
Clarification: the content of the control is an LDAPString.
10.4 Changes from draft-weltman-ldapv3-proxy-06.txt
None
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10.5 Changes from draft-weltman-ldapv3-proxy-05.txt
The control also applies to add and extended operations.
The control value is an authorization ID, not necessarily a DN.
Confidentiality concerns are mentioned.
10.6 Changes from draft-weltman-ldapv3-proxy-04.txt
The control does not apply to bind, unbind, or abandon operations.
The proxy DN is represented as a string in the control, rather than
embedded in a sequence.
Support for the control is published in the supportedControl
attribute of the root DSE, not in supportedExtensions.
The security section mentions confidentiality issues with exposing an
additional identity.
10.7 Changes from draft-weltman-ldapv3-proxy-03.txt
None
10.8 Changes from draft-weltman-ldapv3-proxy-02.txt
The Control is now called Proxied Authorization Control, rather than
Proxied Authentication Control, to reflect that no authentication
occurs as a consequence of processing the Control.
Rather than containing an LDAPDN as the Control value, the Control
contains a Sequence (which contains an LDAPDN). This is to provide
for future extensions.
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