Zero Checksum for the Stream Control Transmission Protocol
draft-ietf-tsvwg-sctp-zero-checksum-11

Received changes through RFC Editor sync (changed state to RFC, created became rfc relationship between draft-ietf-tsvwg-sctp-zero-checksum and RFC 9653, changed IESG state to RFC Published)

[Ballot comment]
I support Deb's and Paul's DISCUSS.

No reference entries found for these items, which were mentioned in the text:
[RFCXXXX]. Perhaps a note to the RFC Editor is needed to replace XXXX with the
assigned RFC number.

-------------------------------------------------------------------------------
NIT
-------------------------------------------------------------------------------

All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

Section 8, paragraph 11
> r points have been addressed in an appropriate way. 9. Security Consideratio
>                              ^^^^^^^^^^^^^^^^^^^^^
Consider replacing this phrase with the adverb "appropriately" to avoid
wordiness.

[Ballot discuss]
Should there be a short discussion in the Security Considerations on what to do when DTLS fails? This could be a bid-down attack from DTLS to crc32. Perhaps some text that states if DTLS is configured, that if DTLS fails to establish, this should be a hard fail and not a soft fail to crc32 'protected' clear text?

[Ballot comment]
NITS:

        A Virtual Network (VN) is a network provided by a service provider
        to a customer for the customer to use in any way it wants.

I think "any way" is a bit too strong? Service providers have a lot of AUP and
fine print.

being being received -> being received

[Ballot comment]

# Éric Vyncke, INT AD, comments for draft-ietf-tsvwg-sctp-zero-checksum-10

Thank you for the work put into this document.

Please find below some non-blocking COMMENT points (but replies would be appreciated even if only for my own education).

Special thanks to Marten Seemann for the shepherd's detailed write-up including the WG consensus _and_ the justification of the intended status.

I hope that this review helps to improve the document,

Regards,

-éric

# COMMENTS (non-blocking)

## Section 1

Is CRC32c really a checksum ? I guess it includes a polynomial function, i.e., a little more than a simple checksum. I note that SCTP uses a field named 'checksum' but using "CRC32c integrity check" would probably be more suitable.

s/use SCTP encapsulated in DTLS/use SCTP over DTLS/ ? I.e., "encapsulate" is more often used when one payload is completely contained in another payload and especially applicable to "tunnels". Mostly a nit though.

## Section 3

```
When using such alternate error detection methods, the SCTP common header containing the 32-bit checksum field might or might not be visible to middleboxes on the paths between the two endpoints.
```

While I fail to understand the sentence above, I really wonder why a "middlebox" (where is such a term defined ?) should care about the checksum field is visible or not ?

## Section 4

`All transported integer numbers are in "network byte order" a.k.a., Big Endian.` isn't it implicit in all IETF I-Ds ? Again mostly a nit.

## Section 6

`IANA is requested to assign the Error Detection Method Identifier of 1 for this method.` should this rather appear in the IANA considerations ? Or at least having a not to the RFC editor to replace this paragraph by "IANA has assigned 1 ....".

[Ballot discuss]
Currently Section 9 says roughly that there are no changes to the Security Considerations to RFC 9260.  I have two comments:

1.  Since this draft is proposing to remove an integrity mechanism in SCTP, there should be an update to the paragraph in RFC9260 Security Considerations, specifically 12.2.2.  Protecting against Data Corruption in the Network.  Please explain how the data is protected from corruption in the situation where the SCTP checksum is not utilized.

2.  There should be a statement here about the requirement to choose an appropriate cryptographic tunnel protocol. It can be general, but there is a security risk to data integrity if a substandard protocol is chosen. Maybe as simple as 'A secure cryptographic tunnel protocol MUST be used to prevent increasing the risk to data integrity'.  Or words to that effect.

[Ballot comment]
# Gunter Van de Velde, RTG AD, comments for draft-ietf-tsvwg-sctp-zero-checksum-10

Please find https://www.ietf.org/blog/handling-iesg-ballot-positions/ documenting the handling of ballots.

In the draft is written:
  If an endpoint not supporting the extension described in this
  document receives this parameter in an INIT or INIT ACK chunk, it is
  REQUIRED to skip this parameter and continue to process further
  parameters in the chunk.  This behavior is specified by [RFC9260]
  because the highest-order two bits of the Type are '10'.

Would this procedure result that even when the CRC32c checksum
is anything else as zero it is accepted and valid?

G/

[Ballot comment]
# Internet AD comments for draft-ietf-tsvwg-sctp-zero-checksum-10
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Comments

### S7

* Should (SHOULD?) there be a section about considerations for the TAPS API?

### S9

* Is a DoS attack possible via a downgrade attack style mechanism?

  I.e., if a sender does not include this option but an on-path attacker
  is able to inject it, I suppose the worst that happens is that incorrectly
  zero-valued checksum packets are dropped all over the place.

  Nevertheless, is such a thing possible?

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

IANA has completed its review of draft-ietf-tsvwg-sctp-zero-checksum-09. If any part of this review is inaccurate, please let us know.

IANA has a question about one of the actions requested in the IANA Considerations section of this document.

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

First, in the Chunk Parameter Types registry in the Stream Control Transmission Protocol (SCTP) Parameters registry group located at:

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

a single new registration is to be made as follows:

ID Value: [ TBD-at-Registration ]
Chunk Parameter Type: Zero Checksum Acceptable
Reference: [ RFC-to-be ]

IANA notes that the authors have suggested an ID Value of 32769 and that the Type be Zero Checksum Acceptable (0x8001).

Second, a new registry is to be created called the Error Detection Method registry.

IANA Question --> Where should this new registry be located? Should it be added to an existing registry group? If it needs a new registry group, does it also need a new category at http://www.iana.org/protocols (and if so, should the page and the category have the same name)?

The new registry will be maintained via Specification Required as defined in RFC8126.

There are two initial registrations in the new registry as follows:

ID Value: 0
Error Detection Method: Reserved
Reference: [ RFC-to-be ]

ID Value: 1
Error Detection Method: SCTP over DTLS
Reference: [ RFC-to-be ]

ID Values 2 - 4294967295 are unassigned.

We understand that these are the only actions 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 meant only to confirm the list of actions that will be performed.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Sr. Specialist

Request for Last Call review by GENART Completed: Ready with Nits. Reviewer: Meral Shirazipour. Sent review to list. Submission of review completed at an earlier date.

Request for Last Call review by ARTART Completed: Ready with Issues. Reviewer: Bernard Aboba. Sent review to list. Submission of review completed at an earlier date.

The following Last Call announcement was sent out (ends 2024-05-16):

From: The IESG
To: IETF-Announce
CC: draft-ietf-tsvwg-sctp-zero-checksum@ietf.org, martenseemann@gmail.com, tsvwg-chairs@ietf.org, tsvwg@ietf.org, zahed.sarker.ietf@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Zero Checksum for the Stream Control Transmission Protocol) to Proposed Standard


The IESG has received a request from the Transport and Services Working Group
WG (tsvwg) to consider the following document: - 'Zero Checksum for the
Stream Control Transmission Protocol'
  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
last-call@ietf.org mailing lists by 2024-05-16. 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 Stream Control Transmission Protocol (SCTP) uses a 32-bit
  checksum in the common header of each packet to provide some level of
  data integrity.  If another method used by SCTP already provides the
  same or a higher level of data integrity, computing this checksum
  does not provide any additional protection, but does consume
  computing resources.

  This document provides a simple extension allowing SCTP to save these
  computing resources by using zero as the checksum in a backwards
  compatible way.  It also defines how this feature can be used when
  SCTP packets are encapsulated in Datagram Transport Layer Security
  (DTLS) packets.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-zero-checksum/



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

Shepherd Review - SCTP Zero Checksum
Document History
Was the document considered in any WG, and if so, why was it not adopted as a work item there?
The document was only considered in TSVWG.

Was there controversy about particular points that caused the WG to not adopt the document?
No.

Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarize 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.

For protocol documents, are there existing implementations of the contents of the document? Have a significant number of potential implementers indicated plans to implement? Are any existing implementations reported somewhere, either in the document itself (as RFC 7942 recommends) or elsewhere (where)?
There are a number of implementations I'm aware of:
FreeBSD SCTP kernel stack: https://cgit.freebsd.org/src/tree/. This shares the SCTP code with (2)
usrsctp userland stack: https://github.com/sctplab/usrsct. This shares the SCTP code with (1).
Userland SCTP implementation of Google: https://webrtc.googlesource.com/src/+/refs/heads/main/net/dcsctp. Please note that this is an implementation for https://www.ietf.org/archive/id/draft-ietf-tsvwg-sctp-zero-checksum-00.html. Victor is working on updating the code to the latest draft version.
Userland SCTP implementation in go: https://github.com/pion/sctp/pull/284. There needs to be some changes in the API.
Support in Wireshark: https://gitlab.com/wireshark/wireshark
Support in the SCTP capable fork of packetdrill: https://github.com/nplab/packetdrill
Testcases for packetdrill: https://github.com/tsvwg/zero-checksum/tree/main/zero-checksum-tests
Michael is working on adding support for zero checksum to the SCTP Test Tool: https://github.com/nplab/stt. He's planning to port of the testcases in (7) to stt to be able to use the tests for testing (4).


Additional Reviews
Do the contents of this document closely interact with technologies in other
IETF working groups or external organizations, and would it therefore benefit
from their review? Have those reviews occurred? If yes, describe which
reviews took place.
No.

Describe how the document meets any required formal expert review criteria,
such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
There are no parameters that need review.

If the document contains a YANG module, has the final version of the module
been checked with any of the recommended validation tools for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module
comply with the Network Management Datastore Architecture (NMDA) as specified
in RFC 8342?
The document doesn't contain a YANG module.

Describe reviews and automated checks performed to validate sections of the
final version of the document written in a formal language, such as XML code,
BNF rules, MIB definitions, CBOR's CDDL, etc.
There are no parameters that need validation.


Document Shepherd Checks
Based on the shepherd's review of the document, is it their opinion that this
document is needed, clearly written, complete, correctly designed, and ready
to be handed off to the responsible Area Director?
Yes, the document is needed, clearly written, complete, correctly designed, and ready
to be handed off to the responsible Area Director.
As in other SCTP specifications in the RFC-series, this document includes a section with considerations for the SCTP API.

Several IETF Areas have assembled lists of common issues that their
reviewers encounter. For which areas have such issues been identified
and addressed? For which does this still need to happen in subsequent
reviews?
No common issues were identified or need to be addressed.

What type of RFC publication is being requested on the IETF stream (Best
Current Practice, Proposed Standard, Internet Standard,
Informational, Experimental or Historic)? Why is this the proper type
of RFC? Do all Datatracker state attributes correctly reflect this intent?
The document is requested to be published as Proposed Standard. This is the proper type for this document since it is generally stable, has resolved known design choices, is believed to be well-understood, has received significant community review, and appears to enjoy enough community interest to be considered valuable.
The datatracker state correctly reflects this request.

Have reasonable efforts been made to remind all authors of the intellectual
property rights (IPR) disclosure obligations described in BCP 79? To
the best of your knowledge, have all required disclosures been filed? If
not, explain why. If yes, summarize any relevant discussion, including links
to publicly-available messages when applicable.
The authors were emailed in February 2024, and every one of them confirmed that they're not aware of any IPR.

Has each author, editor, and contributor shown their willingness to be
listed as such? If the total number of authors and editors on the front page
is greater than five, please provide a justification.
All authors have agreed to be listed as such.

Document any remaining I-D nits in this document. Simply running the idnits
tool is not enough; please review the "Content Guidelines" on
authors.ietf.org. (Also note that the current idnits tool generates
some incorrect warnings; a rewrite is underway.)
Document looks good.

Should any informative references be normative or vice-versa? See the IESG
Statement on Normative and Informative References.
Both informative and normative references look correct to me.

List any normative references that are not freely available to anyone. Did
the community have sufficient access to review any such normative
references?
All normative references are freely available.

Are there any normative downward references (see RFC 3967 and BCP
97) that are not already listed in the DOWNREF registry? If so,
list them.
The document doesn't have any downward references.

Are there normative references to documents that are not ready to be
submitted to the IESG for publication or are otherwise in an unclear state?
If so, what is the plan for their completion?
There are only normative references to already published RFCs.

Will publication of this document change the status of any existing RFCs? If
so, does the Datatracker metadata correctly reflect this and are those RFCs
listed on the title page, in the abstract, and discussed in the
introduction? If not, explain why and point to the part of the document
where the relationship of this document to these other RFCs is discussed.
The document doesn't change the status of any existing RFC.

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 aspects of the document requiring IANA assignments are
associated with the appropriate reservations in IANA registries. Confirm
that any referenced IANA registries have been clearly identified. Confirm
that each newly created IANA registry specifies its initial contents,
allocations procedures, and a reasonable name (see RFC 8126).
The document defines the Zero Checksum Acceptable Chunk Parameter. The description of the parameter is consistent with the rest of the document.
The document establishes a new IANA registry for the "Error Correction Method", including the initial contents. The name seems reasonable.

List any new IANA registries that require Designated Expert Review for
future allocations. Are the instructions to the Designated Expert clear?
Please include suggestions of designated experts, if appropriate.
Designated Expert Review is required for the newly established registry. The instructions are clear.
Suggestion for designated export: Michael Tüxen

Shepherd Review - SCTP Zero Checksum
Document History
Was the document considered in any WG, and if so, why was it not adopted as a work item there?
The document was only considered in TSVWG.

Was there controversy about particular points that caused the WG to not adopt the document?
No.

Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarize 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.

For protocol documents, are there existing implementations of the contents of the document? Have a significant number of potential implementers indicated plans to implement? Are any existing implementations reported somewhere, either in the document itself (as RFC 7942 recommends) or elsewhere (where)?
There are a number of implementations I'm aware of:
FreeBSD SCTP kernel stack: https://cgit.freebsd.org/src/tree/. This shares the SCTP code with (2)
usrsctp userland stack: https://github.com/sctplab/usrsct. This shares the SCTP code with (1).
Userland SCTP implementation of Google: https://webrtc.googlesource.com/src/+/refs/heads/main/net/dcsctp. Please note that this is an implementation for https://www.ietf.org/archive/id/draft-ietf-tsvwg-sctp-zero-checksum-00.html. Victor is working on updating the code to the latest draft version.
Userland SCTP implementation in go: https://github.com/pion/sctp/pull/284. There needs to be some changes in the API.
Support in Wireshark: https://gitlab.com/wireshark/wireshark
Support in the SCTP capable fork of packetdrill: https://github.com/nplab/packetdrill
Testcases for packetdrill: https://github.com/tsvwg/zero-checksum/tree/main/zero-checksum-tests
Michael is working on adding support for zero checksum to the SCTP Test Tool: https://github.com/nplab/stt. He's planning to port of the testcases in (7) to stt to be able to use the tests for testing (4).


Additional Reviews
Do the contents of this document closely interact with technologies in other
IETF working groups or external organizations, and would it therefore benefit
from their review? Have those reviews occurred? If yes, describe which
reviews took place.
No.

Describe how the document meets any required formal expert review criteria,
such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
There are no parameters that need review.

If the document contains a YANG module, has the final version of the module
been checked with any of the recommended validation tools for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module
comply with the Network Management Datastore Architecture (NMDA) as specified
in RFC 8342?
The document doesn't contain a YANG module.

Describe reviews and automated checks performed to validate sections of the
final version of the document written in a formal language, such as XML code,
BNF rules, MIB definitions, CBOR's CDDL, etc.
There are no parameters that need validation.


Document Shepherd Checks
Based on the shepherd's review of the document, is it their opinion that this
document is needed, clearly written, complete, correctly designed, and ready
to be handed off to the responsible Area Director?
Yes, the document is needed, clearly written, complete, correctly designed, and ready
to be handed off to the responsible Area Director.
As in other SCTP specifications in the RFC-series, this document includes a section with considerations for the SCTP API.

Several IETF Areas have assembled lists of common issues that their
reviewers encounter. For which areas have such issues been identified
and addressed? For which does this still need to happen in subsequent
reviews?
No common issues were identified or need to be addressed.

What type of RFC publication is being requested on the IETF stream (Best
Current Practice, Proposed Standard, Internet Standard,
Informational, Experimental or Historic)? Why is this the proper type
of RFC? Do all Datatracker state attributes correctly reflect this intent?
The document is requested to be published as Proposed Standard. This is the proper type for this document since it is generally stable, has resolved known design choices, is believed to be well-understood, has received significant community review, and appears to enjoy enough community interest to be considered valuable.
The datatracker state correctly reflects this request.

Have reasonable efforts been made to remind all authors of the intellectual
property rights (IPR) disclosure obligations described in BCP 79? To
the best of your knowledge, have all required disclosures been filed? If
not, explain why. If yes, summarize any relevant discussion, including links
to publicly-available messages when applicable.
The authors were emailed in February 2024, and every one of them confirmed that they're not aware of any IPR.

Has each author, editor, and contributor shown their willingness to be
listed as such? If the total number of authors and editors on the front page
is greater than five, please provide a justification.
All authors have agreed to be listed as such.

Document any remaining I-D nits in this document. Simply running the idnits
tool is not enough; please review the "Content Guidelines" on
authors.ietf.org. (Also note that the current idnits tool generates
some incorrect warnings; a rewrite is underway.)
Document looks good.

Should any informative references be normative or vice-versa? See the IESG
Statement on Normative and Informative References.
Both informative and normative references look correct to me.

List any normative references that are not freely available to anyone. Did
the community have sufficient access to review any such normative
references?
All normative references are freely available.

Are there any normative downward references (see RFC 3967 and BCP
97) that are not already listed in the DOWNREF registry? If so,
list them.
The document doesn't have any downward references.

Are there normative references to documents that are not ready to be
submitted to the IESG for publication or are otherwise in an unclear state?
If so, what is the plan for their completion?
There are only normative references to already published RFCs.

Will publication of this document change the status of any existing RFCs? If
so, does the Datatracker metadata correctly reflect this and are those RFCs
listed on the title page, in the abstract, and discussed in the
introduction? If not, explain why and point to the part of the document
where the relationship of this document to these other RFCs is discussed.
The document doesn't change the status of any existing RFC.

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 aspects of the document requiring IANA assignments are
associated with the appropriate reservations in IANA registries. Confirm
that any referenced IANA registries have been clearly identified. Confirm
that each newly created IANA registry specifies its initial contents,
allocations procedures, and a reasonable name (see RFC 8126).
The document defines the Zero Checksum Acceptable Chunk Parameter. The description of the parameter is consistent with the rest of the document.
The document establishes a new IANA registry for the "Error Correction Method", including the initial contents. The name seems reasonable.

List any new IANA registries that require Designated Expert Review for
future allocations. Are the instructions to the Designated Expert clear?
Please include suggestions of designated experts, if appropriate.
Designated Expert Review is required for the newly established registry. The instructions are clear.
Suggestion for designated export: Michael Tüxen

This email starts a WGLC for draft-ietf-tsvwg-sctp-zero-checksum to progress as a Standards-Track document:

https://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-zero-checksum

People are asked to send experience of implementing the draft; notes of support for publication as an RFC; queries on the content; or any other comments to the tsvwg list.

This call for WG last comments is set to end on 27th October 2023.

Best wishes,
Gorry & Marten
TSVWG Co-Chairs