RPCSEC_GSS Version 2
RFC 5403

[Ballot comment]
Review by Chris Vogt:

This document describes updates to the RPCSEC_GSS protocol that enable
channel binding between the RPCSEC_GSS protocol and secure channels at
lower layers.

The document assumes that the reader is very familiar with
implementation-specific details of the RPCSEC_GSS protocol.  The
document is not understandable to a reader without such detailed
knowledge.  The reason is that the document specifies protocol updates
mostly in terms of pseudo-code fragments.  The pseudo-code fragments
may make sense to an RPCSEC_GSS protocol implementor, but they bear
little information to a reader unfamiliar with the RPCSEC_GSS
protocol's implementation specifics.

Making the document plausible for the average reader would require
major rewriting of this document.  To avoid such rewriting but still
ensure that the document is unambiguous for implementation purposes, I
suggest to have the document reviewed by implementers who have worked
with the RPCSEC_GSS protocol.  Based on such a review, an informed
decision could be made on whether or not to publish this document in
its current form.

[Ballot comment]
Boilerplate: This is an IESG comment and should be treated in a similar
fashion to an IETF last call comment from any IETF participant.  This
comment does not prevent advancement of your document through the IETF
process.  However, it may contain suggestions to improve the document,
and it is polite to consider those suggestions.

I support Pasi's Discuss.

Section 3.3, second bullet:

I suggest you also reference the IANA registry "Hash Function Textual Names" to help find new hash functions as they're defined.

General Concern:

A test vector or two would greatly improve this document.  While
I have an adequate understanding of XDR, hash functions, channel
bindings, ASN.1 and Kerberos, I'm skeptical that I would correctly
implement this protocol on the first try.  There are a lot of
important details in prose (such as hashing the channel bindings)
that leave room for implementation errors.  Protocols like this can
gain a bad reputation from implementation errors unless there is a
reference implementation or test vector that implementers can use
for validation to catch errors before they're released in the wild.

[Ballot discuss]
I have reviewed draft-ietf-nfsv4-rpcsec-gss-v2-05. Overall, the
document looks good, but I have the following concerns that I'd like
to discuss before recommending approval of the document:

Since GSS-API already supports channel bindings (with some GSS-API
mechanisms), it seems we end up with three different ways to do channel
bindings in RPCSEC_GSS: either in the GSS-API layer, or outside it
in RPCSEC_GSS layer, or both. The document probably should describe
why the existing GSS-API layer channel bindings are not sufficient
(i.e. why something new is needed), and give some guidance about
their use (e.g. perhaps the intent is that GSS-API layer channel
bindings MUST NOT be used with RPCSEC?).

I think the document would also be improved by explicitly noting that
a channel (e.g., IPsec or TLS) can have multiple channel bindings with
different prefixes (e.g., for TLS we currently have two), and describing
how the initiator picks which of them to use (and how this interacts
with RGSS2_BIND_CHAN_PREF_NOTSUPP).

[Ballot comment]
The acrnym GSS is never expanded in the document. I suggest to expand it at the first occurence in the Abstract or Introduction section.

[Ballot discuss]
This DISCUSS is entered for clarification purposes. I will probably clear it during or after the meeting or even earlier with the proper explanation or if necessary actions are agreed.

I do not get a clear understanding from the document about the relation with RFC 2203. From what I get in section 4 the two versions of the protocol can coexist on the wire and a mechanism to negotiate the versions is in place. From the introductory sections I get that the reasons and advantages of using version 2 are limited to specific cases where low level hardware encryption is in place, or to avoid redundancy if encryption takes place at lower layer. What is the operational recommendation for deployment then - always upgrade or only in specific use cases?

Should not the document header mention Update RFC2203 - when approved?

[Ballot comment]
Boilerplate: This is an IESG comment and should be treated in a similar
fashion to an IETF last call comment from any IETF participant.  This
comment does not prevent advancement of your document through the IETF
process.  However, it may contain suggestions to improve the document,
and it is polite to consider those suggestions.

Section 3.3, second bullet:

I suggest you also reference the IANA registry "Hash Function Textual Names" to help find new hash functions as they're defined.

General Concern:

A test vector or two would greatly improve this document.  While
I have an adequate understanding of XDR, hash functions, channel
bindings, ASN.1 and Kerberos, I'm skeptical that I would correctly
implement this protocol on the first try.  There are a lot of
important details in prose (such as hashing the channel bindings)
that leave room for implementation errors.  Protocols like this can
gain a bad reputation from implementation errors unless there is a
reference implementation or test vector that implementers can use
for validation to catch errors before they're released in the wild.

[Ballot comment]
Boilerplate: This is an IESG comment and should be treated in a similar
fashion to an IETF last call comment from any IETF participant.  While
no action is necessary to advance the document through the IETF
process, this may contain suggestions to improve the document, and it
is polite to consider those suggestions.

Section 3.3, second bullet:

I suggest you also reference the IANA registry "Hash Function Textual Names" to help find new hash functions as they're defined.

General Concern:

A test vector or two would greatly improve this document.  While
I have an adequate understanding of XDR, hash functions, channel
bindings, ASN.1 and Kerberos, I'm skeptical that I would correctly
implement this protocol on the first try.  There are a lot of
important details in prose (such as hashing the channel bindings)
that leave room for implementation errors.  Protocols like this can
gain a bad reputation from implementation errors unless there is a
reference implementation or test vector that implementers can use
for validation to catch errors before they're released in the wild.

The NFSv4 Working Group is requesting of the IESG that this document
be published as a standards track RFC. The following, as per RFC4858,
provides the detail of shepherding the documents forward.
------------------------------------------------------------------

(1.a) Who is the Document Shepherd For this document? Has the
Document Shepherd personally reviewed this version of the
document
and, in particular, does he or she believe this version is ready
for forwarding to the IESG for publication?

The document shepherd is Spencer Shepler. Spencer has reviewed
the documents and believes they are ready for publication.

(1.b) Has the document had adequate review both from key members of
the interested community and others? Does the Document Shepherd
have any concerns about the depth or breadth of the reviews that
have been performed?

The document has been reviewed via working group last call and
all comments/concerns raised have been addressed in this
version of the internet draft.

There are no remaining concerns related to depth or breadth
of the reviews that have occurred.

(1.c) Does the Document Shepherd have concerns that the document
needs more review from a particular or broader perspective, e.g.,
security, operational complexity, someone familiar with AAA,
internationalization or XML?

No concerns exist.

(1.d) Does the Document Shepherd have any specific concerns or
issues 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 interested community has discussed those issues and has
indicated that it still wishes to advance the document, detail
those concerns here.

No such concerns exist.

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

There is broad consensus within the NFS and RPC communities
in this work.

(1.f) 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
entered into the ID Tracker.)

No.

(1.g) Has the Document Shepherd personally verified that the
document satisfies all ID nits? (See
http://www.ietf.org/ID-Checklist.html and
http://tools.ietf.org/tools/idnits/). Boilerplate checks are not
enough; this check needs to be thorough. Has the document met
all
formal review criteria it needs to, such as the MIB Doctor, media
type and URI type reviews?

Yes.

(1.h) Has the document split its references into normative and
informative? 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 strategy for
their
completion? Are there normative references that are downward
references, as described in [RFC3967]? If so, list these
downward
references to support the Area Director in the Last Call
procedure
for them [RFC3967].

Yes.

(1.i) Has the Document Shepherd verified that the document IANA
consideration section exists and is consistent with the body of
the document?

Yes.

If the document specifies protocol extensions, are reservations
requested in appropriate IANA registries? Are the IANA
registries clearly identified? If the document creates a new
registry, does it define the proposed initial contents of the
registry and an allocation procedure for future registrations?
Does it suggested a reasonable name for the new registry? See
[I-D.narten-iana-considerations-rfc2434bis]. If the document
describes an Expert Review process has Shepherd conferred with
the Responsible Area Director so that the IESG can appoint the
needed Expert during the IESG Evaluation?

N/A

(1.j) Has the Document Shepherd verified that sections of the
document that are written in a formal language, such as XML code,
BNF rules, MIB definitions, etc., validate correctly in an
automated checker?

Yes.

(1.k) The IESG approval announcement includes a Document
Announcement Write-Up.


Technical Summary

RPCSEC_GSS version 2 (RPCSEC_GSSv2) is the same as RPCSEC_GSS
version 1 (RPCSEC_GSSv1) except that support for channel
bindings has been added. The primary motivation for channel
bindings is to securely take advantage of hardware assisted
encryption that might exist at lower levels of the networking
protocol stack, such as at the Internet Protocol (IP) layer
in the form of IPsec. The secondary motivation is that even
if lower levels are not any more efficient at encryption than
the RPCSEC_GSS layer, if encryption is occurring at the lower
level, it can be redundant at the RPCSEC_GSS level.

Working Group Summary

The working group development and review of this work was
straightforward. The motivation is well understood and
agreed upon and no major issues were identified or impeded
progress during document review.

Document Quality

No existing implementations yet exist but given the author
and reviewers are knowledgeable about more than one
implemetation of the current RPCSEC_GSS protocol, it is
believed that the quality of this work is to be considered
"high".