Controller Identification Extension for MUD
draft-lear-opsawg-mud-controller-candidates-00

Abstract

Manufacturer Usage Descriptions (MUD) are a means by which devices can establish expectations about how they are intended to behave, and how the network should treat them. This extension provides a means for a MUD controller to identify itself through its own MUD file.

Status of This Memo

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This Internet-Draft will expire on January 2, 2020.

Copyright Notice

Copyright (c) 2019 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. The ietf-mud-controller model extension
• 2.1. The controller-candidate augmentation to the MUD YANG model
• 3. Examples
• 4. Security Considerations
• 5. Normative References
• Appendix A. Changes from Earlier Versions
• Author's Address

1. Introduction

Manufacturer Usage Descriptions (MUD) [RFC8520] provides a means for devices to identify what they are and what sort of network access they need. Two abstractions made available in that specification are “controller” and “my-controller”. As initially specified, these devices must be identfied by the network administrator. To simplify the administrator’s life, a means of identifying devices that are candidates to be a controller for another device is desirable.

This memo specifies an extension that makes use of the MUD file of the controller itself. It also sets the groundwork to create a RESTful interface for applications that are serving as controllers to make use of the same grouping. However, that work is left either for a future version of this draft, or a future specification.

For example, a light switch might identify as a candidate controller for luminaires. A thermostat might identify as a controller for an air conditioner or heater.

To address the case where “my-controller” is used, the manufacturer of a candidate controller must list the MUD URLs of devices that it knows it can serve. For example, if thermostat manufacturer “Example Thermostat, Inc” knows that it can properly control a heater made by “Example Heating, Inc”, and the heater has a mud url of “https://heating.example.com/mudurls/heater1000.json”, the thermostat would list that or an expression matching that URL in its MUD URL. The heater’s MUD file would be expected to contain a “my-controller” statement in order for this controller to be considered a candidate.

To address the case where “controller” is used, then the class indicated by the controller must be named instead of a MUD URL. In our previous example, let us assume that the heater1000.json file contains a “controller” statement with a class URI of “https://heating.example.com/theromstats”. In this case, the controller would contain a statement that indicates it can be a controller for class “https://heating.example.com”.

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. The ietf-mud-controller model extension

We now formally define this extension. This is done in two parts. First, the extension name “controller-candidate” is listed in the “extensions” array of the MUD file.

Second, the “mud” container is augmented to contain two optional lists, one that contains mud-urls that can be matched for “my-controller”, and a second list that contains classes that can be matched against “controller”.

This is done as follows.

module: ietf-mud-controller-candidate
  augment /mud:mud:
      +--rw controller-candidates
          +--rw urls*      inet:uri
          +--rw classes*   inet:uri

2.1. The controller-candidate augmentation to the MUD YANG model

<CODE BEGINS>file "ietf-mud-controller-candidate@2019-06-20.yang"
module ietf-mud-controller-candidate {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-mud-controller-candidate";
  prefix mud-cc;

  import ietf-mud {
    prefix "mud";
  }

  import ietf-inet-types {
    prefix "inet";
  }

  organization
    "IETF OPSAWG (Ops Area) Working Group";
  contact
    "WG Web: http://tools.ietf.org/wg/opsawg/
     WG List: opsawg@ietf.org
     Author: Eliot Lear
     lear@cisco.com
    ";
  description
    
    "This YANG module augments the ietf-mud model to provide for two
     optional lists to indicate that this device type may be used as
     a controller for other MUD-enabled devices.

     Copyright (c) 2019 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 2019-06-20 {
    description
      "Initial proposed standard.";
    reference "RFC XXXX: QoS for MUD Specification";
  }

  grouping mud-controller-candidates {
    description
      "Controller candidate grouping";
    container controller-candidates {
      description
        "Lists of controller candidates.";
      leaf-list urls {
        type inet:uri;
        description
          "a list of mud urls this device is designed to control.
           Each entry may end with a * to indicate a wildcard that
           matches zero or more of characters from that point.  A
           wildcard MUST NOT appear in the authority section of the
           URL.";
        }
        leaf-list classes {
          type inet:uri;
          description
            "A list of URIs that are used as classes in MUD files,
             indicating that this device can serve as a controller
             in those classes.";
        }
      }
    }

  augment "/mud:mud" {
    uses mud-controller-candidates;
    description
      "add controller candidate list";
  }
}
<CODE ENDS>

3. Examples

TBD

4. Security Considerations

All security considerations of [RFC8520] apply equally to this extension. In addition, some care should be given to claims that a device is permitted to be a controller in any given circumstances. Complete automation requires far more context than is currently specified here. Some form of confirmation or selection is required by an administrator. This memo simply makes it easier for administrator to identify candidates for controller selection.

IANA Considerations ===================

The IANA is requested to add “controller-candidate” to the MUD extensions registry as follows:

  Extension Name: controller-candidate
  Standard reference: This document

5. Normative References

Appendix A. Changes from Earlier Versions

Draft -00:

• Initial revision

Author's Address