Network Working Group N. Cam-Winget Internet-Draft H. Zhou Intended status: Standards Track Cisco Systems Expires: July 9, 2010 January 5, 2010 EAP Type-Length-Value Container draft-cam-winget-eap-tlv-00 Abstract The Extensible Authentication Protocol (EAP), defined in RFC 3748, facilitates multiple authentication methods that are widely deployed today. As tunnel mechanisms become more prevalent, there has been interest in carrying other types of data between the EAP Peer and the EAP server. Existing tunnel EAP methods have already defined generic data structures to carry such information. This document defines a generic TLV "container" that can be used within an EAP method. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 July 9, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. Cam-Winget & Zhou Expires July 9, 2010 [Page 1] Internet-Draft EAP TLV January 2010 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Specification Requirements . . . . . . . . . . . . . . . . . . 3 3. EAP Type-Length-Value Format and Support . . . . . . . . . . . 3 4. EAP TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 4 5. NAK TLV . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Error TLV . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Vendor-Specific TLV . . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 11.2. Informative References . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Cam-Winget & Zhou Expires July 9, 2010 [Page 2] Internet-Draft EAP TLV January 2010 1. Introduction Different authentication systems use the Extensible Authentication Protocol (EAP) framework to define tunnel authentication methods for establishing strong mutual authentication through the use of different authentication schemes including smart cards, One Time Passwords, cleartext passwords and others. Tunnel EAP methods whose requirements are defined in [I-D.salowey-emu-eaptunnel-req] carry EAP methods and other authorization information such as channel binding that need an inner tunnel transport mechanism. Other IETF groups have also expressed the need to carry other types of data between the EAP Peer and EAP Server. Tunnel EAP methods such as EAP-FAST [RFC4851] and EAP-TTLS [RFC5281] already use TLV structures to carry data. EAP-TTLS overloads the Diameter AVP attribute type space, while EAP-FAST and other previous work, such as the one presented in "draft-hiller-eap-tlv" use a separate attribute type namespace. This memo takes the approach of using the separate namespace used in EAP-FAST. 2. Specification Requirements 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. EAP Type-Length-Value Format and Support To allow for interoperability, the EAP Type-Length-Value (EAP-TLV) defines a container format used to carry arbitrary data between the EAP peer and the EAP server. It is intended that this container be used only inside a protected EAP tunnel. The mandatory bit in an EAP-TLV indicates whether support of the EAP- TLV is required. If the EAP Peer or Server does not support an EAP- TLV marked mandatory, then it MUST send a NAK TLV in the response, and all the other EAP-TLVs in the message MUST be ignored. If an EAP Peer or Server finds an unsupported TLV which is marked as optional, it can ignore the unsupported EAP-TLV. It MUST NOT send a NAK TLV for an EAP-TLV that is not marked mandatory. Note that an EAP Peer or Server may support an EAP-TLV with the mandatory bit set, but may not understand the contents. The appropriate response to a supported EAP-TLV with content that is not understood is defined by the individual EAP-TLV specification. Cam-Winget & Zhou Expires July 9, 2010 [Page 3] Internet-Draft EAP TLV January 2010 EAP implementations compliant with this specification MUST support EAP-TLV exchanges, as well as processing of mandatory/optional settings on the EAP-TLV. Implementations conforming to this specification MUST support the following subset of EAP-TLVs defined in this document: NAK TLV 4. EAP TLV Format EAP-TLVs are defined as described below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |M|R| TLV Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ M 0 Optional TLV 1 Mandatory TLV R Reserved, set to zero (0) TLV Type A 14-bit field, denoting the TLV type. Allocated Types include: 0 Reserved Cam-Winget & Zhou Expires July 9, 2010 [Page 4] Internet-Draft EAP TLV January 2010 1 Reserved 2 Reserved 3 Reserved 4 NAK TLV 5 Error TLV 7 Vendor Specific TLV Length The length of the Value field in octets. Value The value of the TLV. 5. NAK TLV The NAK TLV allows an EAP Peer or Server to detect TLVs that are not supported by the other party. An EAP packet can contain 0 or more NAK TLVs. The NAK TLV is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |M|R| TLV Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NAK-Type | TLVs.... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ M Mandatory, set to one (1) Cam-Winget & Zhou Expires July 9, 2010 [Page 5] Internet-Draft EAP TLV January 2010 R Reserved, set to zero (0) TLV Type 4 for NAK TLV Length >=6 Vendor-Id The Vendor-Id field is four octets, and contains the Vendor-Id of the EAP-TLV that was not supported. The high-order octet is 0 and the low-order 3 octets are the SMI Network Management Private Enterprise Code of the Vendor in network byte order. The Vendor-Id field MUST be zero for EAP-TLVs that are not Vendor-Specific TLVs. NAK-Type The NAK-Type field is two octets. The field contains the Type of the TLV that was not supported. A TLV of this Type MUST have been included in the previous packet. TLVs This field contains a list of TLVs, each of which MUST NOT have the mandatory bit set. These optional TLVs are for future extensibility to communicate why the offending TLV was determined to be unsupported. 6. Error TLV The Error TLV allows an EAP Peer or Server to indicate errors to the other party. For example, an error may occur if the EAP TLV contains information that can not be parsed or if the EAP Peer or Server received an unexpected EAP TLV. An EAP packet can contain 0 or more Cam-Winget & Zhou Expires July 9, 2010 [Page 6] Internet-Draft EAP TLV January 2010 Error TLVs. The appropriate response to an Error TLV is defined by the individual EAP method or EAP-TLV specification. The Error TLV is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |M|R| TLV Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Error-Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ M Mandatory, set to one (1) R Reserved, set to zero (0) TLV Type 5 for Error TLV Length 4 Error-Code The Error-Code field is four octets. Allocated Error Types include: 0 Reserved 1 EAP-TLV could not be processed Cam-Winget & Zhou Expires July 9, 2010 [Page 7] Internet-Draft EAP TLV January 2010 2 Unexpected EAP-TLV 7. Vendor-Specific TLV The Vendor-Specific TLV is available to allow vendors to support their own extended attributes not suitable for general usage. A Vendor-Specific TLV attribute can contain one or more TLVs, referred to as Vendor TLVs. The TLV-type of a Vendor-TLV is defined by the vendor. All the Vendor TLVs inside a single Vendor-Specific TLV belong to the same vendor. The can be multiple Vendor-Specific TLVs from different vendors in the same message. Vendor TLVs may be optional or mandatory. Vendor TLVs sent with Result TLVs MUST be marked as optional. The Vendor-Specific TLV is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |M|R| TLV Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor TLVs.... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ M 0 or 1 R Reserved, set to zero (0) TLV Type 7 for Vendor Specific TLV Cam-Winget & Zhou Expires July 9, 2010 [Page 8] Internet-Draft EAP TLV January 2010 Length >=4 Vendor-Id The Vendor-Id field is four octets, and contains the Vendor-Id of the TLV. The high-order octet is 0 and the low-order 3 octets are the SMI Network Management Private Enterprise Code of the Vendor in network byte order. Vendor TLVs This field is of indefinite length. It contains vendor- specific TLVs, in a format defined by the vendor. 8. Security Considerations The EAP-TLV container can carry arbitrary data between an EAP Peer and the EAP server. It is expected that the EAP TLVs defined in this document are carried by an EAP method that provides the required protection, such as an EAP tunnel method. 9. IANA Considerations This section provides guidance to the Internet Assigned Numbers Authority (IANA) regarding registration of EAP-TLV related values, in accordance with BCP 26, [RFC2434]. The document defines a registry for EAP-TLV types, which may be assigned by Specification Required as defined in [RFC2434]. Section 4 defines the TLV types that initially populate the registry. 10. Acknowledgements The TLVs defined in this draft borrow from the work done in EAP-FAST. The authors would also like to recognize Tom Hiller, Ashwin Palekar and Glen Zorn for introducing this concept to the EAP WG back in 2002. 11. References Cam-Winget & Zhou Expires July 9, 2010 [Page 9] Internet-Draft EAP TLV January 2010 11.1. Normative References [I-D.salowey-emu-eaptunnel-req] Hoeper, K., Hanna, S., Zhou, H., and J. Salowey, "Requirements for an Tunnel Based EAP Method", draft-salowey-emu-eaptunnel-req-01 (work in progress), June 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. [RFC4851] Cam-Winget, N., McGrew, D., Salowey, J., and H. Zhou, "The Flexible Authentication via Secure Tunneling Extensible Authentication Protocol Method (EAP-FAST)", RFC 4851, May 2007. 11.2. Informative References [RFC5281] Funk, P. and S. Blake-Wilson, "Extensible Authentication Protocol Tunneled Transport Layer Security Authenticated Protocol Version 0 (EAP-TTLSv0)", RFC 5281, August 2008. Authors' Addresses Nancy Cam-Winget Cisco Systems 80 West Tasman Drive San Jose, CA 95134 US Email: ncamwing@cisco.com Cam-Winget & Zhou Expires July 9, 2010 [Page 10] Internet-Draft EAP TLV January 2010 Hao Zhou Cisco Systems 4125 Highlander Parkway Richfield, OH 44286 US Email: hzhou@cisco.com Cam-Winget & Zhou Expires July 9, 2010 [Page 11]