The WebSocket Protocol as a Transport for the Binary Floor Control Protocol (BFCP)
draft-ietf-bfcpbis-bfcp-websocket-15

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[Ballot comment]

- I support Ben's discuss and hope the discussion about the
gen-art review continues and reaches a good conclusion.

- WRT Kathleen's comment, while I think it'd be a fine thing
were HOBA usable with ws/wss, I doubt that browsers will do
that, so adding the reference may be misleading.

[Ballot discuss]
I plan to ballot "yes" for this document, but I have some concerns about the security properties that I think need to be resolved first. I have followed the discussion resulting from Robert's Gen-ART review (and will have comments about that in the "COMMENTS section", but I think I see an additional issue that hasn't been covered in that discussion.

draft-ietf-bfcpbis-rfc4582bis (currently in the RFC Editors queue) defines some situations where TLS and client authentication are normatively required. Specifically, section 9 of that draft says that, if the signaling channel is authenticated and has confidentiality and integrity protection, the BFCP client MUST be authenticated. Section 14 additionally says that under those circumstances, BFCP is REQUIRED to use the mandated cryptographic algorithm. But bfcp-websocket only says that WSS and client authentication are RECOMMENDED.

I think this could be fixed by requiring WSS, and the web-based client authentication techniques described in this draft whenever the signaling protocol is secured. The simplest way to describe that might be to say that BFCP-websocket must use at least as strong protections as the signaling channel.

[Ballot comment]
I appreciate the author's efforts in resolving the security considerations issues from Robert's Gen-ART review, but I don't think the current text is quite there yet. Version 14 added the text to say that, when using websockets, the websocket security mechanisms are used instead of those from draft-ietf-bfcpbis-rfc4582bis. But Robert also asked for the draft to describe how that change impacts the security analysis in draft-ietf-bfcpbis-rfc4582bis. I don't see text that does that. I'd like to see, for each of the attacks described in draft-ietf-bfcpbis-rfc4582bis, text that says describes how (or if) a similar attack would be mitigated using websocket.

-4.2, first paragraph: You talk about how the payload size limit is smaller when using websocket. Can you give guidance for actual reasonable limits?

-5, 2nd paragraph: "The BFCP server is a will have a globally routable address"
Is there an implied MUST hiding in there? Also, there's a typo around "is will have".

-8, paragraph 8: Is the point that you SHOULD authenticate the client, or that if you want to authenticate the client you SHOULD do it this way? I suspect the former is intended, but the text implies the latter.

[Ballot comment]
There is ongoing discussion based on the security considerations questions from Robert Sparks in his Gen-ART review. That discussion is not yet finished, but needs to finish before we can approve this document.

[Ballot comment]
I agree with Alexey's comment on section 8.  If fallback to HTTP authentication happens, the implementer should be aware of the weaknesses in HTTP basic [RFC7617] and digest [RFC7616] spelled out in the respective security considerations sections.  The HTTPAuth WG put out a few experimental RFCs with methods to eliminate some of the weaknesses, like HOBA [RFC7486] that gets rid of the need for passwords.  Adding this detail would be helpful.

Request for posting confirmation emailed to previous authors: bfcpbis-chairs@ietf.org, "Anton Roman" , "Victor Pascual" , "Sergio Murillo" , "Gonzalo Salgueiro" , "Stephane Cazeaux" , "Ram R"

[Ballot comment]

In 4.2, last sentence: wouldn't that require a new WebSocket sub-protocol identifier?

In 6.2: some formatting errors in the PDF version. Also, I think you meant Section 3.3 (not 3.2) when talking about WSS.

In 7.2: when referencing Section 3, you are missing the RFC number. At least section 3 of this draft is not relevant.

In 8: HTTP authentication text is rather weak.

[Ballot comment]
I have a couple of questions on authentication in this draft.

Does this text,

      Since the WebSocket API does not distinguish between certificate
      errors and other kinds of failure to establish a connection, it is
      expected that browser vendors will warn end users directly of any
      kind of problem with the server certificate.

apply to any WebSocket-based application?

In this text,

  A floor control server that receives a message over TCP/WS can
  request the use of TCP/WSS by generating an Error message, as
  described in Section 13.8 of [I-D.ietf-bfcpbis-rfc4582bis], with an
  Error code with a value of 9 (use TLS).

is "request" the right word? Or is "require" more accurate, if the server isn't going to establish a TCP/WS connection?

[Ballot comment]
1) I find this sentence slightly confusing: 
„This document specifies a new WebSocket sub-
  protocol as a reliable transport mechanism between Binary Floor
  Control Protocol (BFCP) entities to enable usage of BFCP in new
  scenarios.“
because it suggests that this document specifies a new protocol which is not true.
How about the following instead:
„This document specifies the use of Binary Floor
  Control Protocol (BFCP) as a new WebSocket sub-
  protocol enabling a reliable transport mechanism between 
  BFCP entities in new scenarios.“
If this change is used, please also check similar wording in the rest of the doc.
2) In section 4.1:
„The WebSocket messages transmitted over this connection MUST conform to
  the negotiated WebSocket sub-protocol.“
Not sure if this is actually meaningful given the subsequent MUSTs in the next section. I guess this sentence could simply be removed… Also would this mean that it is the task of the BFCP WS sub protocol to verify that BFCP messages are valid?
3) In section 5: „Each BFCP message MUST be carried within a single WebSocket message,
  and a WebSocket message MUST NOT contain more than one BFCP message.“
This seem to be long rather in section 4.2 than in 5.
4) The following sentence in section 6.2 is basically copied and pasted from ietf-bfcpbis-sdp-ws-uri. It’s usually not a good idea to duplicate normative text (as problems when updating might occur). I’d recommend to either a) remove this text (and only refer to ietf-bfcpbis-sdp-ws-uri), or b) use quotes to make clear that this is a citation, or c) rephrase in non-normative language (with a clear indication that the normative text can be found in ietf-bfcpbis-sdp-ws-uri).
„When the 'ws-uri' or 'wss-uri' attribute is present in the
  media section of the SDP, the IP and port information provided in the
  'c' lines SHALL be ignored and the full URI SHALL be used instead to
  open the WebSocket connection. “

(Via drafts-lastcall-comment@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has completed its review of draft-ietf-bfcpbis-bfcp-websocket-13.txt. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there are two actions which we must complete.

First, in the WebSocket Subprotocol Name Registry in the WebSocket Protocol Registries located at:

https://www.iana.org/assignments/websocket/

a new entry will be added as follows:

Subprotocol Identifier: bfcp
Subprotocol Common Name: WebSocket Transport for BFCP (Binary Floor Control Protocol)
Subprotocol Definition: [ TBD-at-registration ]
Referece: [ RFC-to-be ]

Second, in the proto subregistry of the Session Description Protocol (SDP) Parameters registry located at:

https://www.iana.org/assignments/sdp-parameters/

two new values will be registered as follows:

Type: proto
SDP Name: TCP/WS/BFCP
Reference: [ RFC-to-be ]

Type: proto
SDP Name: TCP/WSS/BFCP
Reference: [ RFC-to-be ]

The IANA Services Operator understands that these two actions are the only ones required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.

Thank you,

Sabrina Tanamal
IANA Services Specialist
PTI

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: "Charles Eckel" , draft-ietf-bfcpbis-bfcp-websocket@ietf.org, bfcpbis-chairs@ietf.org, bfcpbis@ietf.org, alissa@cooperw.in, eckelcu@cisco.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (The WebSocket Protocol as a Transport for the Binary Floor Control Protocol (BFCP)) to Proposed Standard


The IESG has received a request from the Binary Floor Control Protocol
Bis  WG (bfcpbis) to consider the following document:
- 'The WebSocket Protocol as a Transport for the Binary Floor Control
  Protocol (BFCP)'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2017-01-11. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  The WebSocket protocol enables two-way realtime communication between
  clients and servers.  This document specifies a new WebSocket sub-
  protocol as a reliable transport mechanism between Binary Floor
  Control Protocol (BFCP) entities to enable usage of BFCP in new
  scenarios.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bfcpbis-bfcp-websocket/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-bfcpbis-bfcp-websocket/ballot/


No IPR declarations have been submitted directly on this I-D.

Request for posting confirmation emailed to previous authors: bfcpbis-chairs@ietf.org, "Anton Roman" , "Victor Pascual" , "Sergio Murillo" , "Gonzalo Salgueiro" , "Stephane Cazeaux" , "Ram R"

Request for posting confirmation emailed to previous authors: bfcpbis-chairs@ietf.org, "Anton Roman" , "Victor Pascual" , "Sergio Murillo" , "Gonzalo Salgueiro" , "Stephane Cazeaux" , "Ram R"

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet Standard, Informational, Experimental, or Historic)? Why is this the proper type of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard. The title page has an intended status of "Standards Track".

(2) The IESG approval announcement includes a Document Announcement Write-Up. Please provide such a Document Announcement Write-Up. Recent examples can be found in the "Action" announcements for approved documents. The approval announcement contains the following sections:

Technical Summary:
The WebSocket [RFC6455] protocol enables two-way message exchange between clients and servers on top of a persistent TCP connection, optionally secured with Transport Layer Security (TLS) [RFC5246].  This document specifies a new WebSocket sub-protocol as a reliable transport mechanism between Binary Floor Control Protocol (BFCP) entities to enable usage of BFCP in new scenarios.
The initial protocol handshake makes use of Hypertext Transfer Protocol (HTTP) [RFC7230] semantics, allowing the WebSocket protocol to reuse existing HTTP infrastructure.

Working Group Summary:
The document was initially presented in DISPATCH where it was decided there was sufficient interest in the problem to extend the BFCPBIS charter and milestones to include it. There were no competing documents and the draft was quickly adopted as a working group document. Within the working group the scope was clarified to include BFCP over TCP only. It was challenging at times to find reviewers for the draft, so it progressed slowly despite there being few technical issues. The most significant discussions were around SDP procedures, including the decision to create another draft [draft-ietf-bfcpbis-sdp-ws-uri] covering the specification of the SDP ws-uri since this URI is not specific to BFCP.

Document Quality:

Are there existing implementations of the protocol? Have a significant number of vendors indicated their plan to implement the specification? Are there any reviewers that merit special mention as having done a thorough review, e.g., one that resulted in important changes or a conclusion that the document had no substantive issues? If there was a MIB Doctor, Media Type or other expert review, what was its course (briefly)? In the case of a Media Type review, on what date was the request posted?

The authors are aware of two server-side implementations and one client-side — none of them is open source. There are also partial client and server implementations that exercise what is covered in this draft. Other companies indicated plans to implement this in their WebRTC gateway.

Personnel:

Who is the Document Shepherd? Who is the Responsible Area Director?
Charles Eckel  is the document shepherd.
Alissa Cooper  is the responsible Area Director.

(3) Briefly describe the review of this document that was performed by the Document Shepherd. If this version of the document is not ready for publication, please explain why the document is being forwarded to the IESG.

This document has been reviewed several times both in its entirety as well as diffs for specific changes. I believe this version of the document is ready for publication.

(4) Does the document Shepherd have any concerns about the depth or breadth of the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from broader perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or internationalization? If so, describe the review that took place.

This document required expert review from the SDP Directorate. The review as performed by Dan Wing based on draft-ietf-bfcpbis-bfcp-websocket-10 (see https://mailarchive.ietf.org/arch/msg/bfcpbis/SOqNvB9xMPpN6EkS1hKh-g2DBm4 for complete review). The review called attention to some inconsistencies between this draft and draft-ietf-bfcpbis-sdp-ws-uri-05, and also some descriptions that were too vague and requirements that were too weak. These were addressed by draft-ietf-bfcpbis-bfcp-websocket-11 and draft-ietf-bfcpbis-sdp-ws-uri-06.
No other expert reviews were deemed necessary.

(6) Describe any specific concerns or issues that the Document Shepherd has with this document that the Responsible Area Director and/or the IESG should be aware of? For example, perhaps he or she is uncomfortable with certain parts of the document, or has concerns whether there really is a need for it. In any event, if the WG has discussed those issues and has indicated that it still wishes to advance the document, detail those concerns here.

No concerns.

(7) Has each author confirmed that any and all appropriate IPR disclosures required for full conformance with the provisions of BCP 78 and BCP 79 have already been filed. If not, explain why?

Yes.

(8) Has an IPR disclosure been filed that references this document? If so, summarize any WG discussion and conclusion regarding the IPR disclosures.

No IPR disclosure has been filed.

(9) How solid is the WG consensus behind this document? Does it represent the strong concurrence of a few individuals, with others being silent, or does the WG as a whole understand and agree with it?

The working group does not have many active participants, but the consensus represents that of the significant portion of those that are active. There are no objections to the current version of the draft.

10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise the areas of conflict in separate email messages to the Responsible Area Director. (It should be in a separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist). Boilerplate checks are not enough; this check needs to be thorough.

Outdated reference: A later version (-06) exists of draft-ietf-bfcpbis-sdp-ws-uri-05
This is deemed acceptable and unavoidable due to there being several work in progress drafts that reference each other. It will need to be resolved at the time of publication.

(12) Describe how the document meets any required formal review criteria, such as the MIB Doctor, media type, and URI type reviews.

This document required expert review from the SDP Directorate. The results of those reviews are listed in (5).

(13) Have all references within this document been identified as either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion?

No.

(15) Are there downward normative references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs? Are those RFCs listed on the title page header, listed in the abstract, and discussed in the introduction? If the RFCs are not listed in the Abstract and Introduction, explain why, and point to the part of the document where the relationship of this document to the other RFCs is discussed. If this information is not in the document, explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations section, especially with regard to its consistency with the body of the document. Confirm that all protocol extensions that the document makes are associated with the appropriate reservations in IANA registries. Confirm that any referenced IANA registries have been clearly identified. Confirm that newly created IANA registries include a detailed specification of the initial contents for the registry, that allocations procedures for future registrations are defined, and a reasonable name for the new registry has been suggested (see RFC 5226).

The IANA considerations were thoroughly reviewed and all issues have been resolved.

(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries.

Normal IANA review procedures are sufficient.

(19) Describe reviews and automated checks performed by the Document Shepherd to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, etc.

None beyond that listed previously.

Request for posting confirmation emailed to previous authors: bfcpbis-chairs@ietf.org, "Anton Roman" , "Victor Pascual" , "Sergio Murillo" , "Gonzalo Salgueiro" , "Stephane Cazeaux" , "Ram R"