Network Working Group N. Williams Internet-Draft Cryptonector Updates: 2743, 2744 (if approved) July 7, 2013 Intended status: Standards Track Expires: January 8, 2014 Generic Naming Attributes for the Generic Security Services Application Programming Interface (GSS-API) draft-williams-kitten-generic-naming-attributes-00 Abstract This document specifies several useful generic naming attributes for use with the Generic Security Services Application Programming Interface (GSS-API) Naming Extensions specified in RFC6680. These attributes allow applications to extract discrete components of a GSS-API "mechanism name" (MN) object: issuer (e.g., realm name, domain name, certification authority name), service and host names (for host-based service names), user names, and others. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on January 8, 2014. Copyright Notice Copyright (c) 2013 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 publication of this document. Please review these documents Williams Expires January 8, 2014 [Page 1] Internet-Draft Simple GSS July 2013 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 Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3 2. Generic Attributes . . . . . . . . . . . . . . . . . . . . 4 2.1. Concrete Attributes . . . . . . . . . . . . . . . . . . . 4 2.1.1. Issuer Name . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.2. User Name . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.3. Service Name . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.4. Host Name . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.5. Domain Name . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Prefix Attributes . . . . . . . . . . . . . . . . . . . . 5 2.2.1. GSS_C_ATTR_GENERIC_UNCONSTRAINED . . . . . . . . . . . . . 6 2.2.2. GSS_C_ATTR_GENERIC_UNCONSTRAINED_OK . . . . . . . . . . . 6 2.2.3. GSS_C_ATTR_GENERIC_FAST . . . . . . . . . . . . . . . . . 6 3. Local Name Attributes . . . . . . . . . . . . . . . . . . 7 3.1. GSS_C_ATTR_LOCAL_LOGIN_USER . . . . . . . . . . . . . . . 7 4. Suggested Mechanism-Specific Name Attributes (INFORMATIONAL) . . . . . . . . . . . . . . . . . . . . . 8 4.1. Suggested Kerberos-Specific Name Attributes . . . . . . . 8 4.2. Suggested PKU2U-Specific Name Attributes . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . 13 Williams Expires January 8, 2014 [Page 2] Internet-Draft Simple GSS July 2013 1. Introduction In RFC6680 [RFC6680] we introduced an interface by which to access "attributes" of names. This document specifies some such attributes. 1.1. 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]. Williams Expires January 8, 2014 [Page 3] Internet-Draft Simple GSS July 2013 2. Generic Attributes We add a number of generic attributes. Some of these attributes can be used as prefixes of other attributes. 2.1. Concrete Attributes These attributes generally have a single value. Only one of these attributes can also be used a prefix: the issuer name attribute. 2.1.1. Issuer Name We add an attribute by which to obtain a name of an issuer of a mechanism name (MN) or of an attribute of an MN. The API name for this attribute is GSS_C_ATTR_GENERIC_ISSUERNAME, and it's actual attribute name is "urn:ietf:id:ietf-kitten-name-attrs-00-issuername". The display form of issuer names is mechanism-specific. The [non-display] form of issuer names SHALL be the exported name token form of the issuer's name. Not all mechanisms will support issuer names as MNs, therefore implementations MAY output a null non- display value. For example, for the Kerberos mechanism [RFC4121] an issuer name would generally (but not always!) be a Kerberos realm name, probably display as just the realm name. (But note that there is not yet a Kerberos realm name as MN specification.) This attribute can be used as prefix of other attributes. When used as a prefix, this attribute indicates that the application wishes to know the name of the issuer of the prefixed attribute of the given MN. 2.1.2. User Name We add an attribute by which to obtain the component of an MN naming a user. The API name for this attribute is GSS_C_ATTR_GENERIC_USERNAME, and it's actual attribute name is "urn:ietf:id:ietf-kitten-name-attrs-00-username". The display form of user names is mechanism-specific. The non-display form of user names is mechanism-specific. Williams Expires January 8, 2014 [Page 4] Internet-Draft Simple GSS July 2013 2.1.3. Service Name We add an attribute by which to obtain the component of an MN naming a service as part of a host- or domain-based service name. The API name for this attribute is GSS_C_ATTR_GENERIC_SERVICENAME, and it's actual attribute name is "urn:ietf:id:ietf-kitten-name-attrs-00-servicename". The display and non-display forms of service names are the same: a character string corresponding to the service names used, for example, in calls to GSS_Import_name() with the GSS_C_NT_HOSTBASED_SERVICE name-type. 2.1.4. Host Name We add an attribute by which to obtain the component of an MN naming a host as part of a host- or domain-based service name. The API name for this attribute is GSS_C_ATTR_GENERIC_HOSTNAME, and it's actual attribute name is "urn:ietf:id:ietf-kitten-name-attrs-00-hostname". The display form of a host name MAY be stylized and SHOULD use U-labels [RFC5890]. The non-display form of host names SHOULD be a character string as described in [RFC1123], and SHOULD use A-labels [RFC5890]. 2.1.5. Domain Name We add an attribute by which to obtain the component of an MN naming a domain as part of a domain-based service name. The API name for this attribute is GSS_C_ATTR_GENERIC_DOMAINNAME, and it's actual attribute name is "urn:ietf:id:ietf-kitten-name-attrs-00-domainname". The display form of a domain name MAY be stylized and SHOULD use U-labels [RFC5890]. The non-display form of domain names SHOULD be a character string as described in [RFC1035], and SHOULD use A-labels [RFC5890]. 2.2. Prefix Attributes GSS_Get_name_attribute() using attributes described in the preceding section SHALL fail if there are any name constraints that can be applied to the issuers of those names and, in applying those constraints, it is discovered that the issuer was not permitted to issue credentials for the MN. For example, a Kerberos realm named "FOO.EXAMPLE" might not be Williams Expires January 8, 2014 [Page 5] Internet-Draft Simple GSS July 2013 expected to issue credentials (tickets, keys) to host-based service names for hosts not ending in ".foo.example" or which are not "foo.example". Several generic attribute prefixes are described below for overriding this behavior. 2.2.1. GSS_C_ATTR_GENERIC_UNCONSTRAINED This attribute prefix, named GSS_C_ATTR_GENERIC_UNCONSTRAINED in the API, and with an actual name of "urn:ietf:id:ietf-kitten-name-attrs-00-gen-unconstrained", indicates that the application wants the value of the prefixed attribute without any name constraint checking. 2.2.2. GSS_C_ATTR_GENERIC_UNCONSTRAINED_OK This attribute prefix, named GSS_C_ATTR_GENERIC_UNCONSTRAINED_OK in the API, and with an actual name of "urn:ietf:id:ietf-kitten-name-attrs-00-gen-unconstrained-ok", indicates that the application wants the value of the prefixed attribute regardless of any applicable naming constraints, but to indicate the name constraint status via the 'authenticated' output parameter of the GSS_Get_name_attribute() interface. 2.2.3. GSS_C_ATTR_GENERIC_FAST This attribute prefix, named GSS_C_ATTR_GENERIC_FAST in the API, and with an actual name of "urn:ietf:id:ietf-kitten-name-attrs-00-gen-fast", indicates that the application requires that the mechanism not perform any slow operations (e.g., connecting to a directory for the purposes of name constraint validation) in obtaining the prefixed attribute of the given MN. Williams Expires January 8, 2014 [Page 6] Internet-Draft Simple GSS July 2013 3. Local Name Attributes Normally an Internet specification would not be expected to specify any local name attributes of GSS names. However, there is one common and very useful local name attribute, which we specify below. Implementations are free to use different names for this attribute or exclude it altogether -- it is a local name attribute, after all. 3.1. GSS_C_ATTR_LOCAL_LOGIN_USER This attribute, with suggested API name GSS_C_ATTR_LOCAL_LOGIN_USER, and suggested actual name "local-login-user", requests a local user name corresponding to the given MN, if any. Obtaining the local user name corresponding to an MN may require complex name mapping or lookup operations that are completely implementation-defined. Williams Expires January 8, 2014 [Page 7] Internet-Draft Simple GSS July 2013 4. Suggested Mechanism-Specific Name Attributes (INFORMATIONAL) [[anchor1: This section should really be split out into separate Internet-Drafts. It is here only because the author lacks the time at the moment of writing to create such separate I-Ds.]] 4.1. Suggested Kerberos-Specific Name Attributes o realm (corresponding to issuer name) o component 0 (first component of a principal name) o component 1 (second component of a principal name) o .. o component 9 (10th component of a principal name) o components (ordered set of components of a principal name) o transit path (ordered set of realm and CA names) o specific authorization data elements o PKINIT client certificate o session key enctype o enctypes involved in transit path (this would only be available to initiators) 4.2. Suggested PKU2U-Specific Name Attributes [[anchor2: Add reference to PKU2U.]] o issuer CA name o trust path to a trust anchor o certificate o certificate subject public key o certificate subject name o certificate subject alternate names Williams Expires January 8, 2014 [Page 8] Internet-Draft Simple GSS July 2013 o specific certificate extensions o certificate algorithm names o session key enctype Williams Expires January 8, 2014 [Page 9] Internet-Draft Simple GSS July 2013 5. Security Considerations [Add text regarding name constraint checking and explaining the default-to-safe design of the generic name attributes defined in section 2.] Williams Expires January 8, 2014 [Page 10] Internet-Draft Simple GSS July 2013 6. IANA Considerations [Add text regarding the registration and assignment of the name attributes described in the preceding sections. In particular we should want these attributes' names to not reflect an Internet-Draft name, but an RFC number.] Williams Expires January 8, 2014 [Page 11] Internet-Draft Simple GSS July 2013 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC1123] Braden, R., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, October 1989. [RFC2743] Linn, J., "Generic Security Service Application Program Interface Version 2, Update 1", RFC 2743, January 2000. [RFC2744] Wray, J., "Generic Security Service API Version 2 : C-bindings", RFC 2744, January 2000. [RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, August 2010. [RFC6680] Williams, N., Johansson, L., Hartman, S., and S. Josefsson, "Generic Security Service Application Programming Interface (GSS-API) Naming Extensions", RFC 6680, August 2012. 7.2. Informative References [RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos Version 5 Generic Security Service Application Program Interface (GSS-API) Mechanism: Version 2", RFC 4121, July 2005. Williams Expires January 8, 2014 [Page 12] Internet-Draft Simple GSS July 2013 Author's Address Nicolas Williams Cryptonector, LLC Email: nico@cryptonector.com Williams Expires January 8, 2014 [Page 13]