Internet DRAFT - draft-guenther-geopriv-saml-policy
draft-guenther-geopriv-saml-policy
Geopriv C. Guenther
Internet-Draft Siemens
Expires: January 14, 2006 July 13, 2005
SAML in Authorization Policies
draft-guenther-geopriv-saml-policy-01.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of 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 January 14, 2006.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
Rules of an authorization policy prescribe under which conditions an
entity or subject has which permissions. Existing policies support
identity-based authorization by matching the authenticated identity
of the entity requesting access to a resource with the available
policies. This document is about formulating policy rules that
express conditions with respect to SAML assertions, thereby
supporting non-identity-based authorization and anonymity.
Guenther Expires January 14, 2006 [Page 1]
Internet-Draft SAML in Authorization Policies July 2005
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Basic Scenario . . . . . . . . . . . . . . . . . . . . . . . 5
4. SAML Condition Example . . . . . . . . . . . . . . . . . . . 6
5. SAML Condition Schema . . . . . . . . . . . . . . . . . . . 9
6. Common Policy Schema . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1 Normative References . . . . . . . . . . . . . . . . . . 18
10.2 Informative References . . . . . . . . . . . . . . . . . 18
Author's Address . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . 19
Guenther Expires January 14, 2006 [Page 2]
Internet-Draft SAML in Authorization Policies July 2005
1. Introduction
The Security Assertion Markup Language, see [SAMLCore], is an XML
sublanguage for exchanging security information. It is suitable for
expressing assertions concerning previously performed authentication
procedures and authorization decisions. For example, a SAML
assertion can be used by the assertion issuer to assure that the
assertion subject (e.g., a person, a network entity, ...) has been
authenticated by means of a specific authentication method. A
recipient of such an assertion - if it has trust in the assertion
issuer and the integrity of the assertion - can then base its
authorization decisions on this assertion.
This document is about defining an extension to the Common Policy
markup language, see [I-D.ietf-geopriv-common-policy], that allows to
express conditions with respect to statements contained in SAML
assertions. It shall be possible to express authorization policy
rules of the following fashion: If the SAML assertion has been issued
by the assertion issuer A and if the assertion assures that the
assertion subject S has been authenticated by means of the
authenticated method M, then S is permitted to ... .
Guenther Expires January 14, 2006 [Page 3]
Internet-Draft SAML in Authorization Policies July 2005
2. Terminology
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].
Guenther Expires January 14, 2006 [Page 4]
Internet-Draft SAML in Authorization Policies July 2005
3. Basic Scenario
Figure 1 depicts a basic scenario in the scope of this document: a
Subject S wishes to have access to a certain resource (e.g., location
information of a particular entity). After a successful
authentication protocol execution between S and the Asserting Party
(AP), see step 1, the AP issues a SAML assertion (step 2), which
asserts that S has been authenticated by AP using method M and is
associated with a certain set of attributes.
+-------------+ 1: Authentication +------------+
| |<----------------->| Asserting |
| Subject (S) | | Party |
| |<------------------| (AP) |
+-------------+ 2: SAML Assertion +------------+
|
|
3:| Service Request
| + Assertion
v
+-------------+ +------------+
| Relying | 4: Policy | Policy |
| Party |<------------------| Server |
| (RP) | | (PS) |
+-------------+ +------------+
Figure 1: Basic Scenario
After receipt of the assertion, the Relying Party (RP) can base its
resource access authorization decision on this assertion. The
authorization policy governing access to the requested resource is
stored at the Policy Server (PS). Thanks to the language elements
introduced in this document, this policy can contain rules whose
conditions parts express properties that the SAML assertion must meet
in order to make the rule match.
Guenther Expires January 14, 2006 [Page 5]
Internet-Draft SAML in Authorization Policies July 2005
4. SAML Condition Example
Each policy rule of the Common Policy markup language [I-D.ietf-
geopriv-common-policy] consists of a <conditions>, an <actions> and a
<transformations> element (all of which are optional elements). The
Common Policy XML schema defines the <conditions> element in such a
way that it allows for any child elements that belong to XML
namespaces different from the common policy namespace.
This document defines a new XML element, namely, the <samlcondition>
element, whose purpose is to be used as such a child element of the
common policy <conditions> element. This paragraph provides an
example of an XML document valid with respect to the SAML Condition
schema (as shown in Section 5) and the Common Policy schema (as
listed in Section 6).
<?xml version="1.0" encoding="UTF-8"?>
<ruleset
xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:samlcond="urn:ietf:params:xml:ns:saml-condition"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:common-policy common-policy.xsd
urn:ietf:params:xml:ns:saml-condition saml-condition.xsd">
<rule id="Hz90op54I">
<conditions>
<validity>
<from>2005-08-02T17:00:00-05:00</from>
<to>2005-08-04T19:00:00-05:00</to>
</validity>
<samlcond:samlcondition>
<samlcond:issuer>idp.com</samlcond:issuer>
<samlcond:subject>
<samlcond:nameid>bob@example.com</samlcond:nameid>
</samlcond:subject>
<samlcond:authnstatement>
<samlcond:authncontext>
<samlcond:authncontextclassref>
urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport
Guenther Expires January 14, 2006 [Page 6]
Internet-Draft SAML in Authorization Policies July 2005
</samlcond:authncontextclassref>
</samlcond:authncontext>
<samlcond:authncontext>
<samlcond:authncontextclassref>
urn:oasis:names:tc:SAML:2.0:ac:classes:X509
</samlcond:authncontextclassref>
</samlcond:authncontext>
</samlcond:authnstatement>
</samlcond:samlcondition>
</conditions>
<actions></actions>
</rule>
</ruleset>
The rule set in this example consists of one rule only. The
<conditions> part of the rule consists of a <validity> condition
(defined by the Common Policy schema) and a <samlcondition> (defined
by this document in Section 5). The <validity> element specifies the
time period during which the rule is applicable. The <samlcondition>
element as shown above evaluates to true if and only if the SAML
assertion presented to the Relying Party satisfies the following
properties:
1) The issuer of the SAML assertion is idp.com.
2) The subject of the SAML assertion is bob@example.com.
3) The authentication context class referenced in the SAML assertion
is PasswordProtectedTransport (i.e., the subject of the assertion
has authenticated to the Asserting Party through the presentation
of a password over a protected session) or X509 (i.e., the subject
of the assertion has authenticated to the Asserting Party by means
of a digital signature where the key was validated as part of a
X.509 public key infrastructure).
To be more precisely, the SAML assertion presented to the Relying
Party has to satisfy the following properties to make the
<samlcondition> element evaluate to true:
Guenther Expires January 14, 2006 [Page 7]
Internet-Draft SAML in Authorization Policies July 2005
1) The content of the <saml:Issuer> element of the SAML assertion
must equal the string "idp.com".
2) The SAML assertion must contain a <saml:Subject> child element
(which is optional by the SAML assertion schema), and this <saml:
Subject> element must contain a <saml:NameID> element whose
content equals the string "bob@example.com".
3) The SAML assertion must contain an <saml:AuthnStatement> element
with an <saml:AuthnContext> child element that possesses an <saml:
AuthnContextClassRef> child element whose content is either
urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport
or urn:oasis:names:tc:SAML:2.0:ac:classes:X509.
The complete list of Authentication Context types defined by SAML can
be found in [SAMLAuthnContext].
Guenther Expires January 14, 2006 [Page 8]
Internet-Draft SAML in Authorization Policies July 2005
5. SAML Condition Schema
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:saml-condition"
xmlns:samlcond="urn:ietf:params:xml:ns:saml-condition"
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:common-policy"
schemaLocation="common-policy.xsd"/>
<!-- Definition of element types for saml conditions -->
<!-- Element names correspond to SAML element names -->
<xs:element name="issuer" type="xs:string"/>
<xs:element name="subject">
<xs:complexType>
<xs:sequence>
<xs:element name="nameid" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="authnstatement">
<xs:complexType>
<xs:sequence>
<xs:element ref="samlcond:authncontext"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="authncontext">
<xs:complexType>
<xs:sequence>
<xs:element ref="samlcond:authncontextclassref"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="authncontextclassref" type="xs:anyURI"/>
<!-- Definition of saml conditions -->
Guenther Expires January 14, 2006 [Page 9]
Internet-Draft SAML in Authorization Policies July 2005
<xs:element name="samlcondition">
<xs:complexType>
<xs:sequence>
<xs:element ref="samlcond:issuer"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="samlcond:subject"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="samlcond:authnstatement"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
Guenther Expires January 14, 2006 [Page 10]
Internet-Draft SAML in Authorization Policies July 2005
6. Common Policy Schema
Just for the sake of completeness, this section contains that version
of the Common Policy XML schema that defines - along with the schema
specified in Section 5 - the XML language to which the example in
Section 4 belongs.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:common-policy"
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!-- Rule Set -->
<xs:element name="ruleset">
<xs:complexType>
<xs:sequence>
<xs:element name="rule" type="cp:ruleType"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- Rule -->
<xs:complexType name="ruleType">
<xs:sequence>
<!-- Conditions -->
<xs:element name="conditions" minOccurs="0">
<xs:complexType>
<xs:sequence>
<xs:element name="validity" minOccurs="0">
<xs:complexType>
<xs:all>
<xs:element name="from" type="xs:dateTime"/>
<xs:element name="to" type="xs:dateTime"/>
</xs:all>
</xs:complexType>
</xs:element>
Guenther Expires January 14, 2006 [Page 11]
Internet-Draft SAML in Authorization Policies July 2005
<xs:element name="identity" minOccurs="0">
<xs:complexType>
<xs:choice>
<xs:element name="id" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
<xs:sequence>
<xs:element name="domain" type="xs:string"/>
<xs:element name="except"
minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:element name="anonymous">
<xs:complexType>
<xs:sequence>
<xs:element name="domain"
minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="exception">
<xs:complexType>
<xs:sequence>
<xs:element name="domain"
minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
<xs:element name="id"
minOccurs="0" maxOccurs="unbounded">
Guenther Expires January 14, 2006 [Page 12]
Internet-Draft SAML in Authorization Policies July 2005
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="any-identity" type="xs:string"/>
</xs:choice>
</xs:complexType>
</xs:element>
<xs:element name="sphere"
minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="val"
type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- Actions -->
<xs:element name="actions" minOccurs="0">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- Transformations -->
<xs:element name="transformations" minOccurs="0">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded" />
Guenther Expires January 14, 2006 [Page 13]
Internet-Draft SAML in Authorization Policies July 2005
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="id" type="xs:string" use="required"/>
</xs:complexType>
</xs:schema>
Guenther Expires January 14, 2006 [Page 14]
Internet-Draft SAML in Authorization Policies July 2005
7. Security Considerations
[tbd]
Guenther Expires January 14, 2006 [Page 15]
Internet-Draft SAML in Authorization Policies July 2005
8. IANA Considerations
[tbd]
Guenther Expires January 14, 2006 [Page 16]
Internet-Draft SAML in Authorization Policies July 2005
9. Open Issues
1) SAML assertions with authorization decision statements.
2) SAML assertions with attribute statements.
3) Alignment with Common Policy markup language.
4) Security Considerations.
5) IANA considerations.
Guenther Expires January 14, 2006 [Page 17]
Internet-Draft SAML in Authorization Policies July 2005
10. References
10.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[SAMLAuthnContext]
OASIS, "Authentication Context for the OASIS Security
Assertion Markup Language (SAML) V2.0", OASIS
Standard saml-authn-context-2.0-os.pdf, March 2005.
[SAMLCore]
OASIS, "Assertions and Protocol for the OASIS Security
Assertion Markup Language (SAML) V2.0", OASIS
Standard saml-core-2.0-os.pdf, March 2005.
10.2 Informative References
[I-D.ietf-geopriv-common-policy]
Schulzrinne, H., Morris, J., Tschofenig, H., Polk, J., and
J. Rosenberg, "A Document Format for Expressing Privacy
Preferences", draft-ietf-geopriv-common-policy-04 (work in
progress), February 2005.
Author's Address
Christian Guenther
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: christian.guenther@siemens.com
Guenther Expires January 14, 2006 [Page 18]
Internet-Draft SAML in Authorization Policies July 2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Guenther Expires January 14, 2006 [Page 19]
