Internet DRAFT - draft-birkholz-rats-mud
draft-birkholz-rats-mud
RATS Working Group H. Birkholz
Internet-Draft Fraunhofer SIT
Intended status: Standards Track March 10, 2020
Expires: September 11, 2020
MUD-Based RATS Resources Discovery
draft-birkholz-rats-mud-00
Abstract
Manufacturer Usage Description (MUD) files and the MUD URI that point
to them are defined in RFC 8520. This document introduces a new type
of MUD file to be delivered in conjunction with a MUD file signature
and/or to be referenced via a MUD URI embedded in an IEEE 802.1AR
Secure Device Identifier (DevID). A DevID is a device specific pub-
key identity document that can be presented to other entities, e.g. a
network management system. If this entity is also a verifier as
defined by the IETF Remote ATtestation procedureS (RATS)
architecture, this verifier can use the references found in the MUD
file specified in this document in order to discover appropriate
Reference Integrity Measurements (RIM), Endorsement Documents, or
even globally suitable Remote Attestation Services (RAS). All three
types of theses resources are required to conduct RATS. Hence, the
MUD file defined in this document enables remote attestation
procedures by supporting the discovery of these required resources or
services.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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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 September 11, 2020.
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Copyright Notice
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info) in effect on the date of
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 Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 4
2. MUD URIs in DevIDs . . . . . . . . . . . . . . . . . . . . . 4
3. MUD File Signatures . . . . . . . . . . . . . . . . . . . . . 4
4. Trusting MUD URIs and MUD Files . . . . . . . . . . . . . . . 4
4.1. Trusting RATS Resources referenced by a MUD File . . . . 5
5. Specification of RATS MUD files referenced by MUD URIs . . . 5
5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 5
5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 5
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Verifiers, Endorsers, and Attesters are roles defined in the RATS
Architecture [I-D.ietf-rats-architecture]. In the RATS architecture,
the Attester role relies on the Verifier and Endorser roles to enable
the appraisal of Attestation Evidence produced by said Attesters; and
to create corresponding Attestation Results. Attestation Results
compose a believable chunk of information that can be digested by
Relying Parities in order to assess an Attester's trustworthiness.
The assessment of a remote peer's trustworthiness is vital to steer
any future protocol interaction between the Attester and the remote
Relying Party. To create these Attestation Results to be consumed by
Relying Parties, the Attestation Evidence an Attester creates has to
be processed by one or more appropriate Verifiers.
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This document defines a procedure that enables the discovery of
viable resources for RATS services in a local scope: 1.) Reference
Integrity Measurements, and 2.) Endorsement documents.
Additionally, a third option is provided: this document defines the
option to enable the discovery of remote Verfiers: 3.) Remote
Attestation Services (RAS) in a global scope (if no local trusted
authorities are available).
Attestation Policies and Endorsements are required to enable an
appropriate appraisal of Attestation Evidence in a fashion that helps
Relying Parties to digest the corresponding Attestation Results.
This document defines the use of MUD URIs embedded in Secure Device
Identifiers (IEEE 802.1AR DevIDs) as defined by [RFC8520]. These
DevIDs are enrolled on the Attester by manufacturers or related
supply chain entities with appropriate authority. The DevIDs can be
presented to local Network Management Systems, AAA-services (e.g. via
IEEE 802.1X), or other points of first contact (e.g. [RFC8071]) in a
local scope. These local entities of authority can digest the DevID
and conduct trust decisions based on the DevID by tracing associated
certification paths and trust anchors [RFC4949]. If the DevID
presented by the Attester is deemed to be trusted by the local trust
authority, the MUD URI embedded is considered to be a trusted source
of viable (and if their Identity Documents are also to be trusted -
believable) Attestation Policies, Endorsements, and even globally
available RAS.
In essence, the MUD file that is referenced by the DevID presented
refers to sources of Attestation Policies and Endorsements
recommended by the manufacturer or related supply chain entities with
appropriate authority. These sources are required by appraisal
procedures conducted by Verifiers in order to create well-founded
Attestation Results. For example, trusted Endorses can enrich
Attestation Results by vouching for the quality of hardware
components, the composition of a Composite Attester, or other
security characteristics of an Attester.
This specification does not define the format of Attestation Policies
and Endorsement documents. A type of Attestation Policies and their
representation is defined in [I-D.birkholz-rats-coswid-rim]. A
specific format of Endorsements for hardware components based on
[I-D.ietf-rats-eat] is defined in [I-D.birkholz-rats-endorsement-
eat].
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1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. MUD URIs in DevIDs
The MUD URI embedded in a DevID presented by an Attester points to a
MUD file. [RFC8520] defines the format of how to embed MUD URIs in
Secure Device Identifiers. This document uses this specification and
does neither modify nor augment the definition about how to compose a
MUD URI.
3. MUD File Signatures
As the resources required by a Verifier's appraisal procedures have
to be trustworthy, a MUD signature file for a corresponding MUD File
MUST be available. The MUD File MUST also include a reference to its
MUD signature file via the 'mud-signature' statement. A MUD
signature MAY be referenced in the DevID, but entities consuming this
information must be aware that a MUD File can change. If MUD file
changed (the MUD signature in the DevID does not match any more), a
MUD signature file referenced in the MUD File itself MUST exist and
MUST be available. If both the signature embedded in a DevID and
referenced by a MUD File do not match, the MUD File SHOULD NOT be
trusted.
4. Trusting MUD URIs and MUD Files
The level of assurance about the integrity of a MUD URI embedded in a
DevID is based on the level of trust put into the corresponding trust
anchor associated with the DevID. If you cannot establish a level of
trust towards the entity that signed a DevID (the signer), the
embedded MUD URI SHOULD NOT be trusted.
The level of assurance about the integrity of a MUD file is based on
the level of trust put into the entity that created the corresponding
MUD File Signature. If you cannot establish a level of trust put
into the corresponding trust anchor associated with the MUD signature
file, the referenced MUD File SHOULD NOT be trusted.
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4.1. Trusting RATS Resources referenced by a MUD File
Reference Integrity Measurements and Endorsement documents that are
referenced by a MUD File MUST be signed. The signing procedures, the
format of corresponding Identity documents, and the establishment of
trust relationships associated with these resources are out-of-scope
of this document.
5. Specification of RATS MUD files referenced by MUD URIs
The MUD URI embedded in a DevID presented by an Attester points to a
MUD File. At the time of writing this -00 I-D, MUD URIs always point
to a piece of data that is a YANG-modeled XML file with a structure
specified in the style of a YANG module definition ([RFC7950] and
corresponding updates: [RFC8342], [RFC8526]). This document
specifies a YANG module augment definition for generic MUD files to
create RATS MUD files. The following definition MUST be used, if a
MUD URI points to a RATS MUD file.
5.1. Tree Diagram
The following tree diagram [RFC8340] provides an overview of the data
model for the "ietf-mud-rats" module augment.
<CODE BEGINS>
module: ietf-mud-rats
augment /mud:mud:
+--rw ras
| +--rw ras-uris* inet:uri
+--rw rim
| +--rw rim-uris* inet:uri
+--rw edt
+--rw edt-uris* inet:uri
<CODE ENDS>
5.2. YANG Module
This YANG module has normative references to [RFC6991] and augments
[RFC8520].
<CODE BEGINS> file ietf-mud-rats@2019-03-09.yang
module ietf-mud-rats {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-mud-rats";
prefix "mud-rats";
import ietf-mud {
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prefix "mud";
}
import ietf-inet-types {
prefix "inet";
}
organization
"IETF RATS (Remote ATtestation procedureS) Working Group";
contact
"WG Web: http://tools.ietf.org/wg/rats/
WG List: rats@ietf.org
Author: Eliot Lear <lear@cisco.com>
Author: Henk Birkholz <henk.birkholz@sit.fraunhofer.de>";
description
"This YANG module augments the ietf-mud model to provide for three
optional lists to enable Remote Attestation Procedures so that
this device type may be used as a controller for other
MUD-enabled devices.
Copyright (c) 2020 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision 2020-03-09 {
description
"Initial proposed standard.";
reference "RFC XXXX: MUD Extension to find RATS supply chain
entity resources: remote attestation services, endorsement
documents, and reference integrity measurement";
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}
grouping mud-rats-grouping {
description
"Grouping to locate RATS services";
container ras {
description
"Lists of Remote Attestation Service
(RAS/Verifiers) candidates.";
leaf-list ras-uris {
type inet:uri;
description
"A list of Verifiers that can appraise evidence produced by
the entity that presents a DevID including this MUD URI.";
}
}
container rim {
description
"Lists of Reference Integrity Measurement (RIM) candidates.";
leaf-list rim-uris {
type inet:uri;
description
"A list of RIM CoSWID that provide reference integrity
measurements represented as signed CoSWID using
the CoSWID RIM extension.";
}
}
container edt {
description
"List of Endorsements for Roots of Trusts (e.g. Endorsement
Key Certificates).";
leaf-list edt-uris {
type inet:uri;
description
"A list of Endorsements that vouch for the characteristics
of Roots of Trusts the entity possesses.";
}
}
}
augment "/mud:mud" {
uses mud-rats-grouping;
description
"add mud-rats URI resources";
}
}
<CODE ENDS>
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6. Privacy Considerations
Potentially
7. Security Considerations
Most likely a summary of the trust relationship corresponding to the
RATS architecture
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
<https://www.rfc-editor.org/info/rfc8071>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
Description Specification", RFC 8520,
DOI 10.17487/RFC8520, March 2019,
<https://www.rfc-editor.org/info/rfc8520>.
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[RFC8526] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "NETCONF Extensions to Support the Network
Management Datastore Architecture", RFC 8526,
DOI 10.17487/RFC8526, March 2019,
<https://www.rfc-editor.org/info/rfc8526>.
8.2. Informative References
[I-D.ietf-rats-architecture]
Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote Attestation Procedures Architecture",
draft-ietf-rats-architecture-02 (work in progress), March
2020.
[I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", draft-
ietf-rats-eat-03 (work in progress), February 2020.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<https://www.rfc-editor.org/info/rfc4949>.
Author's Address
Henk Birkholz
Fraunhofer SIT
Rheinstrasse 75
Darmstadt 64295
Germany
Email: henk.birkholz@sit.fraunhofer.de
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