Subject: [6lo] Secdir last call review of draft-ietf-6lo-plc-05

From: Robert Sparks via Datatracker <[email-masked]>
Date: Sun, 14 Feb 2021 14:50:09 -0800

Reviewer: Robert Sparks
Review result: Has Issues

I have reviewed this document as part of the security directorate's ongoing
effort to review all IETF documents being processed by the IESG. These comments
were written primarily for the benefit of the security area directors. Document
editors and WG chairs should treat these comments just like any other last call
comments.

This document has issues that should be addressed before publication as
Proposed Standard RFC.

Document reviewed: draft-ietf-6lo-plc-05

This document's primary point is to standardize mappings of ipv6 identifiers
for using ipv6 over IEEE 1901.1, 1901.2, and IT-T G.9903 networks.

Those standards are not publicy available, and I have not reviewed how these
mappings and the security mechanisms in those protocols interact.

The document has content that is not needed for its purpose. Section 5 in
particular might be useful in an informational RFC, but is has no impact on
someone implementing what this document is trying to standardize.

The security considerations section speaks primarily to generic considerations
for 6lo-like networks. There is no specific discussion of the impact of the
identifier mappings with the underlying protocols, in particular the
constraints that don't allow using the full number of bits of entropy in the
identifiers in those underlying protocols. There is only a passing mention of
RFC8065.

Implementors are advised to "look at" RFC8604 when considering building stable
addresses, but this document specifies doing things that RFC8604 recommends
against (see the use of RFC2464, for example). More discussion seems warranted.

There is a short mention of the possibility of acquiring a network encryption
key during onboarding but there's no discussion about what that means for these
specific layer-2 protocols.

Editorial comments:

At section 4.6, the first paragraph can make its point more clearly. All that's
needed to say is that the lower layers handle segmentation and reassembly, but
the adaptation layer still needs to be ready to do so in the lower layer cant
handle the 1280 octet MTU. At the last paragraph, when you say "referring to"
do you mean "as specified in"?

At section 7, "For security consideration, link layer security is guaranteed in
every PLC technology." needs clarification. Do you mean the three protocols
discussed here provide link layer security? Or do you mean to say that if
anyone plans to provide an adaptation layer to some other PLC protocol, that it
must provide link layer security? Or do you mean something else?

Nit: Expand LLN on first use.