One document matched: draft-ietf-kitten-gssapi-naming-exts-08.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<?rfc toc="yes" ?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<?rfc tocindent="no" ?>
<?rfc autobreaks="no" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes"?>
<?rfc iprnotified="no" ?>
<?rfc strict="yes" ?>
<rfc category="std" docName="draft-ietf-kitten-gssapi-naming-exts-08.txt"
ipr="pre5378Trust200902">
<front>
<title abbrev="GSS-API Naming Extensions">GSS-API Naming
Extensions</title>
<author fullname="Nicolas Williams" initials="N." surname="Williams">
<organization abbrev="Sun">Sun Microsystems</organization>
<address>
<postal>
<street>5300 Riata Trace Ct</street>
<city>Austin</city>
<region>TX</region>
<code>78727</code>
<country>US</country>
</postal>
<email>Nicolas.Williams@sun.com</email>
</address>
</author>
<author fullname="Leif Johansson" initials="L." surname="Johansson">
<organization abbrev="SUNET">Swedish University Network</organization>
<address>
<postal>
<street>Thulegatan 11</street>
<city>Stockholm</city>
<country>Sweden</country>
</postal>
<email>leifj@sunet.se</email>
<uri>http://www.sunet.se</uri>
</address>
</author>
<date day="24" month="June" year="2010" />
<area>Security</area>
<workgroup>KITTEN WORKING GROUP</workgroup>
<keyword>Internet-Draft</keyword>
<abstract>
<t>The Generic Security Services API (GSS-API) provides a simple naming
architecture that supports name-based authorization. This document
introduces new APIs that extend the GSS-API naming model to support name
attribute transfer between GSS-API peers.</t>
</abstract>
</front>
<middle>
<section title="Conventions used in this document">
<t>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 <xref
target="RFC2119"></xref> .</t>
</section>
<section title="Introduction">
<t>As described in <xref target="RFC4768"></xref> the GSS-API's
naming architecture suffers from certain limitations. This document
proposes concrete GSS-API extensions.</t>
<t>A number of extensions to the GSS-API <xref target="RFC2743"></xref>
and its C Bindings <xref target="RFC2744"></xref> are described herein.
The goal is to make information modeled as "name attributes" available
to applications. Such information MAY for instance be used by
applications to make authorization-decisions. For example, Kerberos V
authorization data elements, both in their raw forms, as well as mapped
to more useful value types, can be made available to GSS-API
applications through these interfaces.</t>
<t>The model is that GSS names have attributes. The attributes of a name
may be authenticated (eg an X509 attribute certificate or signed SAML
attribute assertion), or may have been set on a GSS name for the purpose
of locally "asserting" the attribute during credential acquisition or
security context exchange. Name attributes' values are network
representations thereof (e.g., the actual value octets of the contents
of an X.509 certificate extension, for example) and are intended to be
useful for constructing portable access control facilities. Applications
may often require language- or platform-specific data types, rather than
network representations of name attributes, so a function is provided to
obtain objects of such types associated with names and name
attributes.</t>
</section>
<section title="Name Attribute Authenticity">
<t>An attribute is 'authenticated' iff there is a secure association
between the attribute (and its values) and the trusted source of the
peer credential. Examples of authenticated attributes are (any part of)
the signed portion of an X.509 certificate or AD-KDCIssued
authorization-data elements in Kerberos V Tickets provided of course
that the authenticity of the respective security associations (eg
signatures) have been verified.</t>
<t>Note that the fact that an attribute is authenticated does not imply
anything about the semantics of the attribute nor that the trusted
credential source was authorized to assert the attribute. Such
interpretations SHOULD be the result of applying local policy to the
attribute.</t>
<t>An un-authentciated attribute is called <spanx style="emph">asserted</spanx>
in what follows.This is not to be confused with other uses of the word
asserted or assertion eg "SAML attribute assertion", the attributes of
which may be authenticated in the sense of this document for instance if
the SAML attribute assertion was signed by a key trusted by the
peer.</t>
</section>
<section title="Name Attributes/Values as ACL Subjects">
<t>To facilitate the development of portable applications that make use
of name attributes to construct and evaluate portable ACLs the GSS-API
makes name attribute values available in canonical network encodings
thereof.</t>
</section>
<section title="Attribute Name Syntax">
<t>Attribute names are represented as opaque STRING elements in the API
described below. These attribute names have syntax and semantics that
are understood by the application and by the lower-layer implementations
(some of which are described below). In order to present a consistent
namespace to the application and at the same time impose as few
transformation requirements as possible to lower-layer implementations
attribute names SHOULD be URIs.</t>
<t>Technologies used in lower-layer protocols may of course use
attribute naming that are not based on URIs. Notably X.509 certificates
will use OIDs for most naming purposes. In this case OIDs MUST be mapped
into URIs as described in <xref target="RFC3061"></xref> MUST be used.
If for example the OID 1.2.3 denotes an Extended Key Usage (cf below),
the corresponding GSS-API attribute name MUST be represented as
urn:oid:1.2.3.</t>
</section>
<section title="Mapping Mechanism Facilities to Name Attributes">
<t>In this section we describe two important examples of lower-layer
implementations of this API. These examples are not mandatory to
implement and are only provided for reference. The use of <xref
target="RFC2119"></xref>-terms in this section is limited to those
implementations of the GSS-API naming extensions that choose to
implement these lower-layer technologies. Future mappings SHOULD be
documented as RFCs.</t>
<t>Kerberos V <xref target="RFC4120"></xref> and the Simple Public-Key
GSS-API Mechanism, SPKM described in <xref target="RFC2025"></xref>,
both support the concept and encoding of containers of
"authorization-data" as described in <xref target="RFC4120"></xref>.</t>
<t>PKIX <xref target="RFC5280"></xref> supports a number of
attribute-like features, like Extended Key Usage values (EKUs) and
certificate extensions.</t>
<section title="Kerberos V and SPKM Authorization-Data">
<t>Authorization-data non-container elements asserted in Kerberos V
AP-REQ Authenticators MUST be mapped into <spanx style="strong">asserted</spanx>
GSS-API name attributes.</t>
<t>Authorization-data included in Kerberos V Tickets that is not
contained in AD-KDCIssued (with valid signature) MUST be mapped into
<spanx style="strong">asserted</spanx> GSS-API name attributes.
Conversely, authorization-data elements in Kerberos V Tickets
contained by AD-KDCIssued MUST be mapped into <spanx style="strong">authenticated</spanx>
GSS-API name attributes.</t>
</section>
<!--
<section title="Kerberos V Cross-Realm Transit Paths">
<t>[Add text on how to represent/encode/interpret krb5
realm transit paths as name attribute values. And
text on PKINIT too... Basically Ticket's
'transited' field should be exposed as an
authenticated name attribute, with some uncompressed
encoding, possibly encompassing certificate
validation paths of client certs used for PKINIT,
with criticality determined by the presence of the
transit-policy-checked flag.]</t>
</section>
-->
<section title="PKIX">
<section title="Standard PKIX Certificate Extensions">
<t>PKIX certificate extensions MAY/SHOULD/MUST (see comment above)
be represented as <spanx style="strong">authenticated</spanx>
GSS-API name attributes named using the <spanx style="emph">same</spanx>
OID mapped to a URN.</t>
<t>SubjectAltNames and Extended Key Usage OIDs, specifically, MUST
be represented as <spanx style="strong">authenticated</spanx>
GSS-API name attributes; see below. Certificate extensions MUST be
represented as GSS-API name attributes named using the OIDs used for
the extensions (represented as URNs). The value associated with
Extended Key Usage attributes MUST have NULL value represented as a
zero-length OCTET STRING.</t>
<t>The standard PKIX certificate key usage (KUs, but not EKUs), MUST
NOT be represented as GSS-API name attributes.</t>
<t>PKIX certificate subjectAltNames MUST be mapped as <spanx
style="strong">authenticated</spanx> GSS-API name attributes. The
values SHOULD be the values of the subjectAltName represented as
OCTET STRINGs if the type of the subjectAltName supports a unique
loss-less representation as string values. Specifically dnsName,
ipAddress, uniformResourceLocator and emailAddress MUST be returned
using the corresponding string representation of those data
types.</t>
</section>
<section title="Other PKIX Certificate Extensions and Attributes">
<t>Any X.509 certificate extension not covered above SHOULD be
represented as GSS-API name attributes with the OID of the X.509
extension and with OCTET STRING values containing the encoded value
of the extension.</t>
</section>
</section>
<section title="SAML attribute assertions">
<t>Attributes contained in SAML attribute assertions MUST be mapped to
GSS-API name attributes with the same URIs as used in the SAML
attribute name.</t>
<t>SAML attributes found in SAML attribute assertions MUST NOT be
mapped as authenticated unless the SAML attribute assertion was signed
by a key trusted by the peer or otherwise protected from unauthorized
modification.</t>
</section>
<!--
<section title="PKIX Certificate CA Paths and Trust Anchors">
<t>[Add text on how to represent/encode/interpret PKI
certificate validation CA paths as name attribute
values, much as with Kerberos V transited paths.]</t>
</section> -->
</section>
<section title="API">
<section title="GSS_Display_name_ext()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME,</t>
<t>display_as_name_type OBJECT IDENTIFIER</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>display_name STRING</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given name could not be
displayed using the syntax of the given name type.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function displays a given name using the given name syntax, if
possible. This operation may require mapping MNs to generic name
syntaxes or generic name syntaxes to mechanism-specific name syntaxes;
such mappings may not always be feasible and MAY be inexact or lossy,
therefore this function may fail.</t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 GSS_Display_name_ext(
OM_uint32 *minor_status,
gss_name_t name,
gss_OID display_as_name_type,
gss_buffer_t display_name
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Inquire_name()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>name_is_MN BOOLEAN,</t>
<t>mn_mech OBJECT IDENTIFIER,</t>
<t>attrs SET OF OCTET STRING</t>
<!-- <t>[NOTE: Perhaps this function should also output
an indicator as to the provenance of the name,
of which, in the GSS-API, there are three:
imported, inquired from a credential, and a
peer's name inquired from a security
context.]</t> -->
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs the set (represented as a NULL terminated
array of gss_buffer_t) of attributes of a name. It also indicates if a
given NAME is an MN or not and, if it is, what mechanism it's an MN
of. The gss_buffer_set_t type and associated API is defined in <xref
target="GFD.024"></xref></t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 gss_inquire_name(
OM_uint32 *minor_status,
gss_name_t name,
int name_is_MN,
gss_OID *MN_mech,
gss_buffer_set_t *attrs
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Get_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME,</t>
<t>attr STRING</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>authenticated BOOLEAN, -- TRUE iff authenticated by the trusted
peer credential source.</t>
<t>complete BOOLEAN -- TRUE iff this represents a complete set of
values for the name.</t>
<t>values SET OF OCTET STRING,</t>
<t>display_values SET OF STRING</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute OID is not
known or set.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs the value(s) associated with a given GSS name
object for a given name attribute.</t>
<t>The complete flag denotes that (if TRUE) the set of values
represents a complete set of values for this name. The peer being an
authoritative source of information for this attribute is a sufficient
condition for the complete flag to be set by the peer.</t>
<t>In the federated case when several peers may hold some of the
attributes about a name this flag may be highly dangerous and SHOULD
NOT be used.</t>
<t>NOTE: This function relies on the GSS-API notion of "SET OF"
allowing for order preservation; this has been discussed on the KITTEN
WG mailing list and the consensus seems to be that, indeed, that was
always the intention. It should be noted however that the order
presented does not always reflect an underlying order of the mechanism
specific source of the attribute values.</t>
<section title="C-Bindings">
<t>The C-bindings of GSS_Get_name_attribute() requires one function
call per-attribute value, for multi-valued name attributes. This is
done by using a single gss_buffer_t for each value and an
input/output integer parameter to distinguish initial and subsequent
calls and to indicate when all values have been obtained.</t>
<t>The 'more' input/output parameter should point to an integer
variable whose value, on first call to gss_name_attribute_get() MUST
be -1, and whose value upon function call return will be non-zero to
indicate that additional values remain, or zero to indicate that no
values remain. The caller should not modify this parameter after the
initial call. The status of the complete and authenticated flags
MUST NOT change between multiple calls to iterate over values for an
attribute.</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_get_name_attribute(
OM_uint32 *minor_status,
gss_name_t name,
gss_buffer_t attr,
int *authenticated,
int *complete,
gss_buffer_t value,
gss_buffer_t display_value,
int *more
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Set_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME,</t>
<t>complete BOOLEAN, -- TRUE iff this represents a complete set of
values for the name.</t>
<t>attr STRING,</t>
<t>values SET OF OCTET STRING</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute OID is not
known or could not be set.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>The complete flag denotes that (if TRUE) the set of values
represents a complete set of values for this name. The peer being an
authoritative source of information for this attribute is a sufficient
condition for the complete flag to be set by the peer.</t>
<t>In the federated case when several peers may hold some of the
attributes about a name this flag may be highly dangerous and SHOULD
NOT be used.</t>
<t>NOTE: This function relies on the GSS-API notion of "SET OF"
allowing for order preservation; this has been discussed on the KITTEN
WG mailing list and the consensus seems to be that, indeed, that was
always the intention. It should be noted that underlying mechanisms
may not respect the given order.</t>
<section title="C-Bindings">
<t>The C-bindings of GSS_Set_name_attribute() requires one function
call per-attribute value, for multi-valued name attributes -- each
call adds one value. To replace an attribute's every value delete
the attribute's values first with GSS_Delete_name_attribute().</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_set_name_attribute(
OM_uint32 *minor_status,
gss_name_t name,
int complete,
gss_buffer_t attr,
gss_buffer_t value
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Delete_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME,</t>
<t>attr STRING,</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute OID is not
known.</t>
<t>GSS_S_UNAUTHORIZED indicates that a forbidden delete operation
was attempted eg deleting a negative attribute.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>Deletion of negative authenticated attributes from NAME objects
MUST NOT be allowed and must result in a GSS_S_UNAUTHORIZED.</t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 gss_delete_name_attribute(
OM_uint32 *minor_status,
gss_name_t name,
gss_buffer_t attr
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Export_name_composite()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name NAME</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>exp_composite_name OCTET STRING</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs a token which can be imported with
GSS_Import_name(), using GSS_C_NT_COMPOSITE_EXPORT as the name type
and which preserves any name attribute information associated with the
input name (which GSS_Export_name() may well not). The token format is
no specified here as this facility is intended for inter-process
communication only; however, all such tokens MUST start with a
two-octet token ID, hex 04 02, in network byte order.</t>
<t>The OID for GSS_C_NT_COMPOSITE_EXPORT is <TBD>.</t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 gss_export_name_composite(
OM_uint32 *minor_status,
gss_name_t name,
gss_buffer_t exp_composite_name
);
]]></artwork>
</figure>
</section>
</section>
</section>
<section title="IANA Considerations">
<t>This document creates a namespace of GSS-API name attributes.
Attributes are named by URIs, so no single authority is technically
needed for allocation. However future deployment experience may indicate
the need for an IANA registry for URIs used to reference names specified
by IETF standards. It is expected that this will be a registry of URNs
but this document provides no further guidance on this registry.</t>
</section>
<section title="Security Considerations">
<t>This document extends the GSS-API naming model to include support for
name attributes. The intention is that name attributes are to be used as
a basis for (among other things) authorization decisions or
personalization for applications relying on GSS-API security
contexts.</t>
<t>The security of the application may be critically dependent on the
security of the attributes. This document classifies attributes as
asserted or authenticated. Asserted (non-authenticated) attributes MUST
NOT be used if the attribute has security implications for the
application (eg authorization decisions) since asserted attributes may
easily be controlled by the peer directly.</t>
<t>It is important to understand the meaning of 'authenticated' in this
setting. Authenticated does not imply that any semantic of the attribute
is claimed to be true. The only implication is that a trusted third
party has asserted the attribute as opposed to the attribute being
asserte by the peer itself. Any additional semantics is always the
result of applying policy. For instance in a given deployment the mail
attribute of the subject may be authenticated and sourced from an email
system where 'authoritive' values are kept. In another situations users
may be allowed to modify their mail addresses freely. In both cases the
'mail' attribute may be authenticated by virtue of being included in
signed SAML attribute assertions or by other means authenticated by the
underlying mechanism.</t>
<t>When the underlying security mechanism does not provide a permanent
unique identity (eg anonymous kerberos) the GSS-API naming extensions
may be used to provide a replacement permanent unique identity attribute
which in this case may be unique for each peer party. This is analogous
to the SAML permanentIdentifier attribute and has comparable security
and privacy properties and implications.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include='reference.RFC.2025.xml'?>
<?rfc include='reference.RFC.2119.xml'?>
<?rfc include='reference.RFC.2743.xml'?>
<?rfc include='reference.RFC.2744.xml'?>
<?rfc include='reference.RFC.5280.xml'?>
<?rfc include='reference.RFC.4120.xml'?>
<reference anchor="GFD.024">
<front>
<title>GSS-API Extensions</title>
<author fullname="Samuel Meder">
<organization>Argonne National Laboratory</organization>
</author>
<author fullname="Von Welch">
<organization>National Center for Supercomputing
Applications</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Steven Tuecke">
<organization>Argonne National Laboratory</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Doug Engert">
<organization>Argonne National Laboratory</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="June" year="2004" />
</front>
<seriesInfo name="GFD" value="GFD.024" />
<format target="http://www.ggf.org/documents/GFD.24.pdf" type="PDF" />
</reference>
</references>
<references title="Informative References">
<?rfc include='reference.RFC.4768.xml'?>
<?rfc include='reference.RFC.3061.xml'?>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 03:12:04 |