| Network Working Group | N. Williams |
| Internet-Draft | Cryptonector |
| Updates: 2743, 2744 (if approved) | July 11, 2013 |
| Intended status: Standards Track | |
| Expires: January 12, 2014 |
Generic Naming Attributes for the Generic Security Services Application Programming Interface (GSS-API)
draft-williams-kitten-generic-naming-attributes-00
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.
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In RFC6680 [RFC6680] we introduced an interface by which to access “attributes” of names. This document specifies some such attributes.
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].
We add a number of generic attributes. Some of these attributes can be used as prefixes of other attributes.
These attributes generally have a single value. Only one of these attributes can also be used a prefix: the issuer name attribute.
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.
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.
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.
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].
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].
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 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.
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.
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.
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.
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.
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.
[Add text regarding name constraint checking and explaining the default-to-safe design of the generic name attributes defined in section 2.]
[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.]
| [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. |
| [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. |