Re: [mile] Artart last call review of draft-ietf-mile-rolie-10

[Martin Thomson <[e-mail]>]

(-ietf@ and art@ to save those inboxes)

Hi Stephen,

Thanks for the explanation.  I somewhat expected that this would be
the use case, but I couldn't reconcile that with the long list of
requirements for client authentication.  Can you go into some more
detail about that as well?  Happy to hash that out here (I'm not
subscribed to mile@ though).

If the intent is to have the information for a web site (as opposed to
the organization) accessible in a location that can be readily found,
then I think that you have justification for using .well-known for the
service document.  The category document can be linked from the
service document, so I think it would be best if you did remove that
.well-known registration.  You might also consider using simply
.well-known/rolie once you have just one resource.

On Wed, Oct 18, 2017 at 3:18 AM, Banghart, Stephen A. (Fed)
<[e-mail]> wrote:
> Martin,
>
> Thanks for the great review. We've been working through your comments and preparing a -11 version. I'll have a full response to your comments out to the list once we've completed addressing them all, but wanted to open a discussion on a few points in the meantime.
>
> The .well-known registration for /servicedocument has a use case/discovery story that we feel is important enough for registration, or at least for standardization. In the case where there is no standardized location template for the service document, a vendor/company/site that wants to stand up a ROLIE repository and provide regular syndicated information must provide a link to the service document somewhere on their regular site, or otherwise distribute the URL. While this potentially provides a means for humans to find the repository (although the link would likely be hidden in some strange place), it doesn't help automated tools locate the repository.
>
> As a user of ROLIE, I'd like to be able to provide a tool with the hostname:port of a vendor whose syndicated information I'd like to receive, and have the tool return the status of any repository that is or in not hosted by that top level site. For example, I'd like to give a tool "www.microsoft.com" and have it provide me all the ROLIE (and non-ROLIE AtomPub if provided in the same ServDoc) Collections provided by that host. Without a .well-known registration, the standard would have to provide a defined non-/.well-known URL template location, which we felt was bad practice.
>
> Its likely that the standard doesn't provide enough context around the /.well-known registration, and that adding more explanatory text around our discovery story would help make the need for a URL template more clear.
>
> If the issue is with the use of /.well-known, and not with the standardized URL template, we could simply remove the .well-known registration and instead provide a non-registered requirement for a {host}/rolie/servicedocument URL template.
>
> We agree that the discovery story for /categorydocument is decidedly weaker, as any out-of-line category documents would be linked to from the Service Document. We would open to dropping this registration/requirement outright as you suggest.
>
> Thanks again for the thorough review,
> Stephen Banghart
>
>> -----Original Message-----
>> From: mile [mailto:[e-mail]] On Behalf Of Martin Thomson
>> Sent: Monday, October 09, 2017 1:08 AM
>> To: [e-mail]
>> Cc: [e-mail]; [e-mail]; [e-mail]
>> Subject: [mile] Artart last call review of draft-ietf-mile-rolie-10
>>
>> Reviewer: Martin Thomson
>> Review result: Almost Ready
>>
>> I have reviewed this document, and - despite what appears to be a lengthy
>> list of issues - I think that it is in pretty good shape.  It's clear, readable, and
>> addresses the requirements well.  Most of my comments should be trivial to
>> resolve.
>>
>> Major:
>>
>> The decision to define a .well-known URI without a discovery story is - in my
>> opinion - inadvisable.  Such a registration is usually appropriate if you design a
>> protocol that depends on discovery by hostname and port.  As such, this
>> does not use that at all.  A configuration system can (and should) accept a
>> complete URI for the service endpoint.  It would be better to defer creation
>> of yet another .well-known URI registration until the working group is certain
>> that discovery requires it.
>>
>> The same comment applies to the .well-known resource for the category
>> document.
>>  Given that this sort of document is readily discoverable via the service
>> document, I would say that the need for a .well-known resource is less well-
>> justified than the service document.
>>
>> The requirements in Section 5.3 on TLS use are unnecessarily strict.  It's great
>> to recommend the use of TLS 1.2, but given that the document has no real
>> requirement on any particular version of TLS, the use of "MUST" here is not
>> needed.  Similarly, the prohibition on the use of 0-RTT is groundless.  The
>> lengthy list of requirements around certificate validation only risk creating a
>> conflict with advice in other RFCs.  Many, if not all, of these requirements are
>> transitively included by way of referencing HTTPS documents.  I would prefer
>> to see this entire section reduced to a simple RFC 7525 reference.
>>
>> User authentication is under-specified.
>>
>> * Section 5.3 mandates the use of TLS cipher suites that support client
>> authentication using certificates, but offers no further advice.  Aside from
>> being an unnecessary requirement - cipher suites that support certificate-
>> based authentication of servers all allow for client authentication - this sort of
>> requirement is rarely sufficient for interoperation.  For instance, you need to
>> specify how a server will request a certificate such that clients can select the
>> correct certificate.  If a client and server have agreed to share information on
>> terms that rely on authentication of clients, it is better for those peers to
>> arrange the terms on which they will authenticate.
>>
>> * Section 5.4 uses "SHOULD" regarding client authentication using federation,
>> but offers no hints about what this entails.  It also uses "SHOULD" regarding
>> authorization checks, which isn't an interoperability requirement.  It's more
>> of a "don't be silly" type of requirement, which doesn't need to be written
>> down in an RFC.
>>
>> Section 5.5 prohibits the use of GET on "/".  This prohibits use of the resource
>> for other purposes.  It seems reasonable to accept POST messages as
>> defined in RFC 6546, but this requirement is overly strict (and further
>> entrenches the violation of RFC 7320).  If, for instance, the server operator
>> wishes to provide HTML in response to a GET request to "/", this would
>> prohibit that.  The requirement to return 404 if RFC 6546 is not supported is
>> worse; not supporting RFC 6546 might be a choice that a deployment makes
>> to avoid the need to reserve "/" for that protocol.
>>
>> In Section 6.2.3, what is the advantage of "rolie:format" over having a well-
>> defined media type?  Media types can take advantage of content
>> negotiation, existing support in link relations, and other existing tools.
>> This rolie:format element has namespace, format, and schema; these are not
>> useful to anyone that is ignorant of their contents.  The only advantage I see
>> is that syntax might be validated, but semantics can't be extracted.  There's a
>> lot of implied work in adding this element, but that doesn't seem to be
>> justified by that advantage.  (I see that RFC 7970 doesn't define a media type,
>> but it seems like it would be easier to correct that than to define an element
>> like this.)
>>
>> Section 6.2.4 defines a generic key-value mechanism.  But that is something
>> that XML is actually good at.  Why can't users that require additional
>> metadata use additional metadata as originally defined by Atom?  That is,
>> replace <rolie:property name="urn:ietf:params:rolie:property:csirt-iodef-id"
>> value="12345"/> with something like
>> <rolie:csirt-iodef-id>12345</rolie:csirt-iodef-id>.  The final paragraph of the
>> section recognizes this possibility.
>>
>> Minor:
>>
>> Section 5.1.1 recommends the use of workspaces to separate "private" and
>> "public" information.  But workspaces don't really contain enough
>> information to signal their status to a consumer of the information.  I would
>> suggest mentioning this, removing the recommendation, or expanding on
>> the manner in which the status of information is signaled.
>>
>> Section 6.1.1 says "zero or more atom:category elements", but this
>> contradicts the text and amendment to the schema in Section 6.1.
>>
>> Section 6.1.3 requires updating the "atom:updated" element when the
>> representation changes.  I don't think that this is what was intended.  I think
>> that the element needs to be updated when the contents of the feed
>> change in any way.
>>
>> Question: it's fairly widely accepted that use of IRIs in Atom has been less
>> than successful.  Do you want to mandate use of URIs instead?  This would
>> apply to both link relations and the "src" attribute.
>>
>> In Section 7.1, the definition of the namespace prefix
>> "urn:ietf:params:rolie:category:local" seems unnecessary.  Namespace URIs
>> are cheap and it seems reasonable to experiment with feeds that produce
>> non-ROLIE information by omitting the
>> "urn:ietf:params:rolie:category:information-type"
>> category, even if that feed might comply with the requirements of ROLIE.
>> The other way to experiment would be to use the category, but define a way
>> to identify "term" attributes that are for use in private or experimental
>> contexts.
>>
>> In Section 7.4, how is "...:rolie:property:content-author-name" superior to
>> "atom:author"?
>>
>> In Section 8.4,  is there a uniqueness requirement on "name"?  I understand
>> this to be the thing that being registered.   Assuming that, what purpose
>> does
>> the "index" serve?
>>
>> This statement from Section 9, "As described in the discovery section, DNS
>> SRV Records are a possible secure solution to discovery." is false without
>> further qualification.  SRV with DNSSEC might be secure, but a lot depends on
>> the input to the discovery process and its provenance.
>>
>> In Section 10, the following statement is false (all of the described privacy
>> violations are available to a client or server, not third parties): "Proper usage
>> of TLS as described in Section 5.3 will in many cases aid in the mitigation of
>> these issues."  I think that you can strike this statement (most of the reason
>> for use of TLS is justified by the security considerations anyway).
>>
>> Nits:
>>
>> Is it "Feed" or "feed"?  RFC 4287 uses the latter, but this document seems to
>> prefer the Proper Noun form.
>>
>> Section 6.2 should say what changed in the schema.  It's hard to eyeball the
>> schema to discover that "atomContent" is no longer optional.  The two new
>> elements are easy to spot and might cause the first change to be missed.
>>
>> Section 6.2.1 is the same.  It should explicitly say that it only permits the
>> atomOutOfLineContent formulation.
>>
>> I found the formulation of Section 7.1.1 confusing.  It includes a list that
>> seems to be authoritative, then disclaims any attempt to register these
>> terms.
>> Maybe this is because the statement "This document does not specify any
>> information types." appears too late.  Some reordering might help.
>>
>> The formatting of the table in Section 8.3 makes most of the columns
>> unreadable.  I would recommend a simple nested list.
>>
>> In section 9, the use of the term "well-known" to refer to information that is
>> either public or widely available risks misinterpretation.
>>
>> FWIW, I would reword this entire paragraph to say simply "Access control to
>> information published using ROLIE should use mechanisms that are
>> appropriate to the sensitivity of the information.  Primitive authentication
>> mechanisms like HTTP Basic Authentication [RFC7617] are rarely appropriate
>> for sensitive information."  I didn't find the remainder of the text on
>> authentication especially helpful.  The text seems to equivocate on the
>> subject of federation, where it would be easier to say nothing.
>>
>> Also in Section 9, the use of the term "message" is used in the context of
>> using additional security controls.  I think that the word "representation" is
>> what was intended here.
>>
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