Network Working Group S. Josefsson Internet-Draft SJD AB Intended status: Standards Track L. Hornquist Astrand Expires: September 25, 2010 Apple, Inc. March 24, 2010 Context Token Encapsulate/Decapsulate Functions for the Generic Security Service Application Program Interface (GSS-API) draft-josefsson-gss-capsulate-00 Abstract This document describes two abstract Generic Security Service Application Program Interface (GSS-API) interfaces used to encapsulate and decapsulate context tokens, and their C bindings. 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 September 25, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. 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 Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 1] Internet-Draft GSS-API en/de-capsulate March 2010 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. Conventions used in this document . . . . . . . . . . . . . . 4 3. GSS_Encapsulate_Token call . . . . . . . . . . . . . . . . . . 5 3.1. gss_encapsulate_token . . . . . . . . . . . . . . . . . . 6 4. GSS_Decapsulate_token call . . . . . . . . . . . . . . . . . . 7 4.1. gss_decapsulate_token . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7.1. Normative References . . . . . . . . . . . . . . . . . . . 11 7.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 2] Internet-Draft GSS-API en/de-capsulate March 2010 1. Introduction Generic Security Service Application Program Interface (GSS-API) [RFC2743] is a framework that provides security services to applications using a variety of authentication mechanisms. There are widely implemented C bindings [RFC2743] for the abstract interface. For initial context tokens a mechanism-independent token format may be used, see section 3.1 of [RFC2743]. Some protocols, e.g., SASL GS2 [I-D.ietf-sasl-gs2], needs the ability to add and remove the token header from context tokens. This document adds GSS-API interfaces so that GSS-API libraries can provide this functionality. The intention is that text from this specification should be possible to use for implementation documentation, and for this reason this entire document should be considered a code component. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 3] Internet-Draft GSS-API en/de-capsulate March 2010 2. Conventions used in this document The document uses terms from, and is structured in a similar way as, [RFC2743] and [RFC2744]. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 4] Internet-Draft GSS-API en/de-capsulate March 2010 3. GSS_Encapsulate_Token call Inputs: o input_token OCTET STRING -- buffer with token data to encapsulate o token_oid OBJECT IDENTIFIER -- object identifier of mechanism for the token Outputs: o major_status INTEGER o output_token OCTET STRING -- Encapsulated token data; caller must release with GSS_Release_buffer() Return major_status codes: o GSS_S_COMPLETE indicates successful completion, and that output parameters holds correct information. o GSS_S_FAILURE indicates that encapsulation failed for reasons unspecified at the GSS-API level. GSS_Encapsulate_token() is used to add the mechanism-independent token header to GSS-API context token data. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 5] Internet-Draft GSS-API en/de-capsulate March 2010 3.1. gss_encapsulate_token OM_uint32 gss_encapsulate_token ( const gss_buffer_t input_token, const gss_OID token_oid, gss_buffer_t output_token); Purpose: Add the mechanism-independent token header to GSS-API context token data. Parameters: input_token buffer, opaque, read Buffer with GSS-API context token data. token_oid Object ID, read Object identifier of token. output_token buffer, opaque, modify Encapsulated token data; caller must release with gss_release_buffer(). Function value: GSS status code GSS_S_COMPLETE Indicates successful completion, and that output parameters holds correct information. GSS_S_FAILURE Indicates that encapsulation failed for reasons unspecified at the GSS-API level. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 6] Internet-Draft GSS-API en/de-capsulate March 2010 4. GSS_Decapsulate_token call Inputs: o input_token OCTET STRING -- buffer with token to decapsulate o token_oid OBJECT IDENTIFIER -- expected object identifier of token Outputs: o major_status INTEGER o output_token OCTET STRING -- Decapsulated token data; caller must release with GSS_Release_buffer() Return major_status codes: o GSS_S_COMPLETE indicates successful completion, and that output parameters holds correct information. o GSS_S_DEFECTIVE_TOKEN means that the token failed consistency checks (e.g., OID mismatch or ASN.1 DER length errors). o GSS_S_FAILURE indicates that decapsulation failed for reasons unspecified at the GSS-API level. GSS_Decapsulate_token() is used to remove the mechanism- independent token header from an initial GSS-API context token. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 7] Internet-Draft GSS-API en/de-capsulate March 2010 4.1. gss_decapsulate_token OM_uint32 gss_decapsulate_token ( const gss_buffer_t input_token, const gss_OID token_oid, gss_buffer_t output_token) Purpose: Remove the mechanism-independent token header from an initial GSS-API context token. Parameters: input_token buffer, opaque, read Buffer with GSS-API context token. token_oid Object ID, read Expected object identifier of token. output_token buffer, opaque, modify Decapsulated token data; caller must release with gss_release_buffer(). Function value: GSS status code GSS_S_COMPLETE Indicates successful completion, and that output parameters holds correct information. GSS_S_DEFECTIVE_TOKEN Means that the token failed consistency checks (e.g., OID mismatch or ASN.1 DER length errors). GSS_S_FAILURE Indicates that decapsulation failed for reasons unspecified at the GSS-API level. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 8] Internet-Draft GSS-API en/de-capsulate March 2010 5. IANA Considerations None. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 9] Internet-Draft GSS-API en/de-capsulate March 2010 6. Security Considerations Implementations needs to treat input as potentially untrustworthy for purposes of dereferencing memory objects to avoid security vulnerabilities. In particular, ASN.1 DER length fields is a common source of mistakes. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 10] Internet-Draft GSS-API en/de-capsulate March 2010 7. References 7.1. Normative References [RFC2743] Linn, J., "Generic Security Service Application Program Interface Version 2, Update 1", RFC 2743, January 2000. 7.2. Informative References [RFC2744] Wray, J., "Generic Security Service API Version 2 : C-bindings", RFC 2744, January 2000. [I-D.ietf-sasl-gs2] Josefsson, S. and N. Williams, "Using GSS-API Mechanisms in SASL: The GS2 Mechanism Family", draft-ietf-sasl-gs2-20 (work in progress), January 2010. Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 11] Internet-Draft GSS-API en/de-capsulate March 2010 Authors' Addresses Simon Josefsson SJD AB Hagagatan 24 Stockholm 113 47 SE Email: simon@josefsson.org URI: http://josefsson.org/ Love Hornquist Astrand Apple, Inc. Email: lha@apple.com Josefsson & Hornquist Astrand Expires September 25, 2010 [Page 12]