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opsawg-cira-securehomegateway-mud.txt
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6tisch Working Group M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Informational J. Latour
Expires: 29 June 2020 CIRA Labs
27 December 2019
Loading MUD URLs from QR codes
draft-richardson-opsawg-securehomegateway-mud-02
Abstract
This informational document details the mechanism used by the CIRA
Secure Home Gateway (SHG) to load MUD definitions for devices which
have no integrated MUD (RFC8520) support.
The document describes extensions to the WiFi Alliance DPP QR code to
support the use of MUD URLs.
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
working documents as Internet-Drafts. The list of current Internet-
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 29 June 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
Richardson & Latour Expires 29 June 2020 [Page 1]
Internet-Draft SHG-MUD December 2019
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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Manufacturer Usage Description (MUD) [RFC8520] defines a YANG
data model to express what sort of access a device requires to
operate correctly. The document additionally defines three ways for
the device to communicate the URL of the resulting JSON [RFC8259]
format file to a network enforcement point: DHCP, within an X.509
certificate extension, and via LLDP.
Each of the above mechanism conveys the MUD URL inband, and requires
modifications to the device firmware. Most small IoT devices do not
have LLDP, and have very restricted DHCP clients. Adding the LLDP or
DHCP options requires at least some minimal configuration change, and
possibly entire new subsystems. The X.509 certificateion extension
only makes sense to deploy as part of a larger IDevID based
[ieee802-1AR] system such as [I-D.ietf-anima-bootstrapping-keyinfra].
In all cases these mechanisms can only be implemented by persons with
access to modify and update the firmware of the device. The MUD
system was designed to be implemented by Manufacturers afterall!
In the meantime there is a chicken or egg problem ([chickenegg]): no
manufacturers include MUD URLs in their products as there are no
gateways that use them. No gateways include code that processes MUD
URLs as no products produce them.
The mechanism described here allows any person with physical access
to the device to affix a reference to a MUD URL that can later be
scanned by an end user. This can be done by the (marketing
department) of the Manufacturer, by an outsourced assembler plant, by
value added resellers, by a company importing the product (possibly
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to comply with a local regulation), by a network administrator
(perhaps before sending devices home with employees), or even by a
retailer as a value added service.
The mechanism uses the QRcode, which is informally described in
[qrcode]. QR code generators are available as web services
([qrcodewebservice]), or as programs such as [qrencode]. They are
formally defined in [isoiec18004].
This document details how the CIRALabs Secure Home Gateway encode MUD
URLs as QR codes.
A issue addressed by this document is the question of whether and
when the MUD file should be specific to a specific version of the
device firmware.
The third issue is that an intermediary (ISP, or third-party security
service) may want to extend or amend a MUD file received from a
manufacturer. In order to maintain an audit trail of changes, a way
to encode the previous MUD URL and signature file (and status) is
provided. (FOR DISCUSSION)
2. Terminology
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.
3. Protocol
The [dpp] specification from the Wi-Fi Alliance has created a base
for a QRcode based enrollment system. This specification extends it
to include a MUD URL.
The QR code is as specified in section 5.2.1 of [dpp] is repeated
here:
dpp-qr = “DPP:” [channel-list “;”] [mac “;”]
[information “;”] public-key “;;”
This is amended as follows:
dpp-qr = “DPP:” [channel-list “;”] [channel-list “;”]
[mac “;”] [information “;”] public-key
[";" mudurl ] “;;”
mudurl = "D:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
Richardson & Latour Expires 29 June 2020 [Page 3]
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While the ABNF defined in the [dpp] document assumes a specific order
(C:, M:, I:, K:), this specification relaxes this so that the tags
can come in any order. However, in order to make interoperation with
future DPP-only clients as seamless as possible, the MUD extension
suggested here are placed after those defined in [dpp].
This document establishes an IANA registry for DPP attributes.
The syntax of the QR code definition given above does not permit a
semicolon to be included. Semicolons (";") would otherwise be
permitted in MUD URLs. This restriction on the content the URL is
not considered a concern as it is uncommon to use them in a URL.
The URL provided MUST NOT have a query (?) portion present.
An IANA registry is created for the attributes below.
4. Privacy Considerations
TBD.
5. Security Considerations
The security of the Device Provisioning Protocol is enhanced when the
public key for a device is not available without physical access to
the device. Placement of a QR code for use by a MUD controller has
no such dependancy, and so such QR codes may be affixed in prominant
places on the outside of packaging. This is not a recommended
practice as future versions of the sticker may include full DPP
information.
The QRcode described in this document is identical for all instances
of the device, and the stickers may be mass produced. The situation
is not the same when a full DPP content is present: each sticker is
unique. A manufacturing plant designed to affix MUD URLs may get
confused and not be ready for the full DPP.
It is recommended that the manufacturing process be designed with the
full DPP process -- unique QR codes per device -- initially so that
no changes are necessary when/if DPP is introduced.
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6. IANA Considerations
IANA is requested to create a new Registry entitled: "Device
Provisioning Protocol Attributes". New items can be added to using
Specification Required. In order to conserve space, registrations
are expected to be single upper-case ASCII letters, but the Expert
Reviewer MAY make exceptions. No entry may contain a colon. All
entries beginning with "X" are reserved as Private-Use values.
The following items are to be added to the initial table:
+--------+--------------+-----------------+
| Letter | Name | Document |
+========+==============+=================+
| C | channel-list | [dpp] |
+--------+--------------+-----------------+
| M | MAC address | [dpp] |
+--------+--------------+-----------------+
| I | information | [dpp] |
+--------+--------------+-----------------+
| K | public key | [dpp] |
+--------+--------------+-----------------+
| D | MUD URL | [This document] |
+--------+--------------+-----------------+
Table 1
(EDITORIAL NOTE: the authors of the DPP specification have consented
to seeding control to IANA)
7. Acknowledgements
This work was supported by the Canadian Internet Registration
Authority (cira.ca).
8. References
8.1. Normative References
[qrcode] Wikipedia, ., "QR Code", December 2019,
<https://en.wikipedia.org/wiki/QR_code>.
[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>.
Richardson & Latour Expires 29 June 2020 [Page 5]
Internet-Draft SHG-MUD December 2019
[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>.
[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>.
8.2. Informative References
[chickenegg]
Wikipedia, ., "Chicken or the egg", December 2019,
<https://en.wikipedia.org/wiki/Chicken_or_the_egg>.
[dpp] "Device Provisioning Protocol Specification", April 2018,
<https://www.wi-fi.org/downloads-registered-guest/Device_P
rovisioning_Protocol_Draft_Technical_Specification_Package
_v0_0_23_0.zip/31255>.
[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", Work in Progress, Internet-
Draft, draft-ietf-anima-bootstrapping-keyinfra-31, 16
December 2019, <http://www.ietf.org/internet-drafts/draft-
ietf-anima-bootstrapping-keyinfra-31.txt>.
[ieee802-1AR]
IEEE Standard, ., "IEEE 802.1AR Secure Device Identifier",
2009, <http://standards.ieee.org/findstds/
standard/802.1AR-2009.html>.
[isoiec18004]
ISO/IEC, ., "Information technology — Automatic
identification and data capture techniques — QR Code bar
code symbology specification (ISO/IEC 18004)", February
2015.
[qrcodewebservice]
Internet, ., "QR Code Generators", December 2019,
<https://duckduckgo.com/?q=QR+code+web+generator>.
[qrencode] Fukuchi, K., "QR encode", December 2019,
<https://fukuchi.org/works/qrencode/index.html.en>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
Richardson & Latour Expires 29 June 2020 [Page 6]
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DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
Authors' Addresses
Michael Richardson
Sandelman Software Works
Email: [email protected]
Jacques Latour
CIRA Labs
Email: [email protected]
Richardson & Latour Expires 29 June 2020 [Page 7]