NETWORK WORKING GROUP L. Zhu Internet-Draft Microsoft Corporation Updates: 4120 (if approved) October 10, 2006 Intended status: Standards Track Expires: April 13, 2007 Additional Kerberos Naming Constraits draft-ietf-krb-wg-naming-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 13, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document defines new naming constraints for reserved Keberos names. A reserved name can be either a Kerberos principal name or a Kerberos realm name. All reserved names defined in this document are critical, so if a reserved name is unknown, authentication MUST fail. Zhu Expires April 13, 2007 [Page 1]
Internet-Draft Kerberos Naming October 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . . 3 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Reserved Kerberos Principal Names . . . . . . . . . . . . . 3 3.2. Reserved Kerberos Realm Names . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 6 Zhu Expires April 13, 2007 [Page 2]
Internet-Draft Kerberos Naming October 2006 1. Introduction Occasionally protocol designers need to designate a Kerberos principal name or a Kerberos realm name to have special meanings, other than identifying a particular instance. An example is that the the anonymous principal name and the anonymous realm name are defined for the Kerberos anonymity support [ANON]. This anonymity name pair conveys no more meaning than that the client's identity is not disclosed. In the case of the anonymity support, it is critical that deployed Kerberos implementations that do not support anonymity MUST fail the authentication if the anonymity name pair is used, therefore no access is granted accidentally to a principal who's name happens to match with that of the anonymous identity. However Kerberos as defined in [RFC4120] does not have such reserved names. As such, protocol designers have resolved to use exceedingly- unlikely-to-have-been-used names to avoid collision. Even if a registry were setup to avoid collision for new implementations, there is no guarantee for deployed implementations to prevent accidental reuse of names that can lead to access being grantedly unexpectedly. The Kerberos realm name in [RFC4120] has a reserved name space although no specific name is defined and the criticality of unknown reserved realm names is not specified. This document is to remedy these by defining reserved Kerberos names. All reserved names defined based on this specification are critical: Authentication MUST fail if an unknown reserved name is used by conforming implementations. 2. Conventions Used in This Document 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 [RFC2119]. 3. Definitions In this section, reserved names are defined for both the kerberos principal name and the kerberos realm name. 3.1. Reserved Kerberos Principal Names A new name type is defined for reserved principal names. The Kerberos principal name is defined in Section 6.2 of [RFC4120]. Zhu Expires April 13, 2007 [Page 3]
Internet-Draft Kerberos Naming October 2006 KRB_NT_RESERVED TBA The reserved principal name MUST have at least two or more KerberosString components, and the first component must be the string literal "RESERVED". For implementations conforming with this specification, authentication MUST fail with KRB_AP_ERR_RESERVED_PRINCIPAL_NAME_UNKNOWN if an unknown reserved principal name is used. There is no accompanying error data for this error. KRB_AP_ERR_RESERVED_PRINCIPAL_NAME_UNKNOWN TBA -- a reserved Kerberos principal name is unknown 3.2. Reserved Kerberos Realm Names Section 6.1 of [RFC4120] defines the "other" style realm name, a new type RESERVED is defined as a name of type "other", with the NAMETYPE part filled in with the word "RESERVED". other: RESERVED:realm-name This name type is designated for reserved Kerberos realms. For implementations conforming with this specification, authentication MUST fail with KRB_AP_ERR_RESERVED_REALM_NAME_UNKNOWN if an unknown reserved realm name is used. There is no accompanying error data for this error. KRB_AP_ERR_RESERVED_REALM_NAME_UNKNOWN TBA -- a reserved Kerberos realm name is unknown 4. Security Considerations If a reserved name is unknown, authentication MUST fail. Otherwise, access can be granted unintentionally, resulting in a security weakness. Care MUST be taken to avoid accidental reuse of names. 5. Acknowledgements The initial document was mostly based on the author's conversation with Clifford Newman and Sam Hartman. Zhu Expires April 13, 2007 [Page 4]
Internet-Draft Kerberos Naming October 2006 6. IANA Considerations This document provides the framework for defining reserved Kerberos names and Kerberos realms. A new IANA registry should be created to contain reserved Kerberos names and Kerberos realms that are defined based on this document. 7. Normative References [ANON] Zhu, L., Leach, P. and Jaganathan, K., "Kerberos Anonymity Support", draft-ietf-krb-wg-anon, work in progress. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The Kerberos Network Authentication Service (V5)", RFC 4120, July 2005. Author's Address Larry Zhu Microsoft Corporation One Microsoft Way Redmond, WA 98052 US Email: lzhu@microsoft.com Zhu Expires April 13, 2007 [Page 5]
Internet-Draft Kerberos Naming October 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, 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 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Zhu Expires April 13, 2007 [Page 6]
