Re: [netmod] Benjamin Kaduk's No Objection on draft-ietf-netmod-factory-default-14: (with COMMENT)

Qin Wu <bill.wu@huawei.com> Thu, 23 April 2020 04:54 UTC

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From: Qin Wu <bill.wu@huawei.com>
To: Benjamin Kaduk <kaduk@mit.edu>, The IESG <iesg@ietf.org>
CC: "draft-ietf-netmod-factory-default@ietf.org" <draft-ietf-netmod-factory-default@ietf.org>, "netmod-chairs@ietf.org" <netmod-chairs@ietf.org>, "netmod@ietf.org" <netmod@ietf.org>, Kent Watsen <kent+ietf@watsen.net>
Thread-Topic: Benjamin Kaduk's No Objection on draft-ietf-netmod-factory-default-14: (with COMMENT)
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Date: Thu, 23 Apr 2020 04:54:37 +0000
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Subject: Re: [netmod] Benjamin Kaduk's No Objection on draft-ietf-netmod-factory-default-14: (with COMMENT)
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Hi, Ben:
Thanks for your valuable comments, see reply inline below.
-----邮件原件-----
发件人: Benjamin Kaduk via Datatracker [mailto:noreply@ietf.org] 
发送时间: 2020年4月23日 9:39
收件人: The IESG <iesg@ietf.org>
抄送: draft-ietf-netmod-factory-default@ietf.org; netmod-chairs@ietf.org; netmod@ietf.org; Kent Watsen <kent+ietf@watsen.net>et>; kent+ietf@watsen.net
主题: Benjamin Kaduk's No Objection on draft-ietf-netmod-factory-default-14: (with COMMENT)

Benjamin Kaduk has entered the following ballot position for
draft-ietf-netmod-factory-default-14: No Objection

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The document, along with other ballot positions, can be found here:
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----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

While many of the secdir reviewer's complaints stem from the YANG security considerations boilerplate, it still seems like it would be worth some form of response to the review.

[Qin]: You are correct, we authors also bring up the discussion on sec-review comment on YANG security consideration boilerplate to netmod list. I have sent my response to the sec-review, 
Thanks for kindly reminder.

Section 1

   This document defines a method to reset a server to its factory
   default content.  The reset operation may be used, e.g., when the
   existing configuration has major errors so re-starting the
   configuration process from scratch is the best option.

   A "factory-reset" RPC is defined.  When resetting a device, all
   previous configuration settings will be lost and replaced by the
   factory default content.

nit: these two paragraphs talk about the same thing, but the next paragraph is a different thing.  It may be better to combine these two in to a single paragraph.
[Qin]:The format of this section is to first introduce what method we proposed? And then introduce what this method look like, or two key components for this method, i.e., one new factory-reset RPC and one new factory datastore.
I prefer to keep as it is. Maybe we could tweak the first paragraph a little bit as follows:
"
   This document defines a method to reset a server to its factory
   default content.  This method may be used, e.g., when the
   existing configuration has major errors so re-starting the
   configuration process from scratch is the best option.
"
   A "factory-default" read-only datastore is defined, that contains the
   data to replace the contents of implemented read-write conventional
   configuration datastores at reset.  [...]

Can I suggest instead:

% A "factory-default" read-only datastore is defined, that reflects what the % conventional read-write datastores would be overwritten with in the case of % a factory-reset operation.
[Qin]: Looks equivalent, but I think the original one is more clear.

Section 2

                                                          All security
   sensitive data (i.e., private keys, passwords, etc.)  SHOULD be
   overwritten with zeros or a pattern before deletion.  [...]

I might suggest instead:

% When this process includes security-sensitive data such as cryptographic keys or passwords, it is RECOMMENDED to perform the deletion in a manner as  thorough as possible (e.g., overwriting the physical storage medium with zeros and/or random bits) to reduce the risk of the sensitive material being recoverable.

[Qin]: Sounds reasonable to me, thanks.
It's probably worth noting that since this is only dymanically generated files, any cryptographic keys that are part of the factory-installed image will be retained (such as an IDevID certificate).
[Qin]:If this is conclusion of the draft-ietf-anima-bootstrapping-keyinfra discussion, yes, will consider it.
Section 3

   Following the guidelines for defining Datastores in the appendix A of
   [RFC8342], this document introduces a new optional datastore resource
   named "factory-default" that represents a preconfigured initial
   configuration that can be used to initialize the configuration of a

nit/soapbox: "preconfigured initial configuration" feels like an awkward wording to me; perhaps "pre-set initial configuration" or "fixed initial configuration"?

[Qin]: I see they are equivalent, but I am happy to take your proposal.

Section 4

        description
          "This read-only datastore contains the factory default
          configuration for the device used to replace the contents
          of the read-write conventional configuration datastores
          during a 'factory-reset' RPC operation.";

nit: the grammar here is off; maybe "for the device that will be used"?
(Or some adaptation of my proposed text from earlier.)
[Qin]: Sounds good to me.

Section 6

If the factory-default configuration is an "open" one, then performing the reset could leave the device (and thus the network!) vulnerable to attack until it is properly configured.  The rtgdir reviewer's comments seem related to this.

An attacker that could somehow cause the factory-reset to be performed would cause the loss of running state/crypto keys that would potentially require a lot of operator effort to recover (in addition to the more immediate DoS issues).

There is some discussion in draft-ietf-anima-bootstrapping-keyinfra about attacks that are possible when a device is restored to its factory default state; it might be worth trying to incorporate some of that discussion in some manner (whether inline or by reference).
[Qin]: Okay and will consider it.

   The "factory-reset" RPC can prevent any further management of the
   device if the session and client config are included in the factory
   default contents.

I'm not sure this is 100% correct.  If the factory default config overwrites this items, then yes, it will prevent further management.  But we also say to delete dynamic files from nonvoliatile storage, which at least to me seems like it could include this class of items and cause the same symptoms even if the configuration items in question are not included in the factory default contents.
[Qin] It seems your comment is related to Eric's. Overwriting happen before deletion, Overwriting can be used to prevent such symptom.