Authorized update to MUD URLs
draft-richardson-opsawg-mud-acceptable-urls-02

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OPSAWG Working Group                                       M. Richardson
Internet-Draft                                  Sandelman Software Works
Updates: 8520 (if approved)                                      J. Yang
Intended status: Best Current Practice     Huawei Technologies Co., Ltd.
Expires: March 26, 2021                                          E. Lear
                                                           Cisco Systems
                                                      September 22, 2020

                     Authorized update to MUD URLs
             draft-richardson-opsawg-mud-acceptable-urls-02

Abstract

   This document provides a way for an RFC8520 Manufacturer Usage
   Description (MUD) definitions to declare what are acceptable
   replacement URLs for a device.

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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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on March 26, 2021.

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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Updating MUD URLs vs Updating MUD files . . . . . . . . . . .   3
     2.1.  Updating the MUD file in place  . . . . . . . . . . . . .   3
       2.1.1.  Adding capabilities . . . . . . . . . . . . . . . . .   3
       2.1.2.  Removing capabilities . . . . . . . . . . . . . . . .   4
       2.1.3.  Significant changes to protocols  . . . . . . . . . .   4
     2.2.  Motivation for updating MUD URLs  . . . . . . . . . . . .   5
   3.  Threat model for MUD URLs . . . . . . . . . . . . . . . . . .   5
     3.1.  Trust on First Use (TOFU): leveraging the manufacturer
           signature . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Concerns about same-signer mechanism  . . . . . . . . . .   5
   4.  Outline of proposed mechanism . . . . . . . . . . . . . . . .   6
   5.  Changes to RFC8520  . . . . . . . . . . . . . . . . . . . . .   6
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Appendix A.  Appendices . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [RFC8520] provides a standardized way to describe how a specific
   purpose device makes use of Internet resources.  Access Control Lists
   (ACLs) can be defined in an RFC8520 Manufacturer Usage Description
   (MUD) file that permit a device to access Internet resources by DNS
   name.

   MUD URLs can come from a number of sources:

   o  IDevID Extensions

   o  DHCP

   o  LLDP

   o  [I-D.richardson-opsawg-securehomegateway-mud] proposes to scan
      them from QRcodes.

   The IDevID mechanism provides a URL that is asserted
   cryptographically by a manufacturer.  However, it is difficult for

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   manufacturers to update the IDevID of a device which is already in a
   box.

   The DHCP and LLDP mechanisms are not signed, but are asserted by the
   device.  A firmware update may update what MUD URL is emitted.
   Sufficiently well targetted malware could also change the MUD URL.

   The QRcode mechanism is usually done via paper/stickers, and is
   typically not under the control of the device itself at all.