Re: [nvo3] Working Group Last Call and IPR Poll for draft-ietf-nvo3-geneve-08.txt

[Daniel Migault <[e-mail]>]

Hi Ilango,

Thanks for the response. Please see a concrete example to illustrate my
concern
for comment 1. For comment 2, it really helped you indicated that Geneve is
expected
to be an end-to-end protocol. This will help me update the security
requirement
document. However, the current Geneve specification with transit devices
seems -
at least to me - to raise an architecture concern as raised in [1].

-- comment 1:

Thanks for the feed back. I understand the purpose of keeping option
independent one from each other, and favour this is strongly recommended.
However, I am not convinced this applies always. More specifically, in a
context of security, the purpose of a security option may be related to
another option. Typically, a security option providing authentication or
encryption is potentially authenticating/encryption another option or
other information contained in the header.

The typical scenario I have in mind would be an authentication option A
authenticating option O. There will clearly some dependencies between A
and O as O could only be used if A has been primarily been validated.
The current statement "SHOULD NOT be dependent" enables this. However, I
have concerns regarding the statement "MUST NOT affect the parsing or
interpretation". In fact, the output of A, will determine if O should be
dropped or processed normally. In case A shows O is not appropriately
authenticated, O might be rejected based on its C value. The ambiguity I
see is that A can be understood as affecting the parsing and
interpretation of O or as a pre-processing operation before parsing or
interpretation of O.

I think, the text needs further clarifications to remove such ambiguity.
Changing MUST NOT by SHOULD NOT was of course only one proposition and
this could be also addressed otherwise. It might be better, I agree, to
explicitly mention that some options may provide condition on the
parsing of the options. This would leave the parsing of the options
unchanged.

-- comment 2:

Thanks for the response that clarifies a bit my understanding of the
transit devices. I believe the issue I have is related to the transit
devices which I do not see, unless I am wrong, meeting the requirements
for being OPTIONAL and that seems - at least to me - contradicting the
status of end-to-end protocol. As suggested in [1], transit devices seem to
raise
architectural concerns that is not needed.

You are correct that the text is clear that transit devices are
OPTIONAL. However, my understanding of OPTIONAL from 2119 is that there
are two sides of it. One is that a vendor may implement it or not, but
the other side is that interoperability with other implementations are
not affected. In this case, two Geneve endpoints using TLS or IPsec will
not be able to interoperate with an implementation based on transit
devices (unless the process being performed by the transit devices is
also performed by the NVE). In that sense, I believe OPTIONAL statement
is not appropriated here.

An implementation with transit devices seems to prevent the
interoperability of with an implementation where  options are treated
by the NVE over a secure channel. If we suppose that NVE and
transit devices support the same options, then transit devices are not
necessary and could be removed from the specification. If options
supported by transit devices are different from those supported by
the NVE, interoperability will not be achieved. Transit device will not be
able to process the options, resulting in options will be ignored (while
being supported by the implementation). In addition, if the options
are critical, the NVE is likely to drop the packet as it does not support
the option.

In addition, I have some hard time to understand the end-to-end model
with a transit device even optional. I believe that end-to-end protocol
is a good path, though. However, my understanding of end-to-end protocol
is that they should only involve two end points. I see the NVE as end
points but the optional transit device does not seems to be one of
these. However, to help me understand better this, as it seems Geneve is
similar to other end-to-end protocol, maybe you could provide similar
end-to-end protocol that involves a transit devices or something similar.

I also have another clarification regarding transit device. I see these
transit devices as adding a lot of complexity to the end-to-end model
with little benefits. Typically, as far as I understand, they can only
read an option. I am thus wondering whether we should not be better off
removing them from the specification. This would end up with a clear
end-to-end model. Reversely, I do not see anything preventing a vendor
to implement them at least for unsecure deployments. Removing them
from the specification would leave the transit devices as implementation
specific. What are actually the benefits of the transit devices that would
justify them to be part of the specification?


[1] https://mailarchive.ietf.org/arch/msg/nvo3/ekLofhq8erRLE_Msuk8N_SCdhcs


Yours,
Daniel

On Sat, Mar 2, 2019 at 8:18 PM Ganga, Ilango S <[e-mail]>
wrote:

> Hi Daniel,
>
>
>
> Let us be specific. I see that you have two comments on the latest
> draft-ietf-nvo3-geneve-09.  Please see below for responses to your comments.
>
>
>
> Comment 1:
>
> OLD
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option MUST NOT affect the parsing or interpretation of any
>
>       other option.
>
>
>
> NEW
>
>
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option SHOULD NOT affect the parsing or interpretation of any
>
>       other option.
>
>
>
> <Ilango>
>
> Architecturally Geneve options can be processed independent of one
> another. The second statement clearly states that parsing or interpretation
> of one option must not affect the other.  This is a reasonable constraint
> to avoid nested dependencies. Options can be designed to work with the
> requirements specified in Geneve.
>
>
>
> Let us take specific examples:
>
> We could think of a design of a Header Integrity check option (related to
> your example). In this case if the header integrity check fails, as a
> result the entire header is invalid and hence the most likely outcome of a
> failed check is that the packet being dropped (including any options in
> that packet whether parsed/interpreted or not). The current text does not
> preclude the packet being dropped as result of failure.
>
>
>
> It is possible to design options, including any security options, with
> these constraints.  We don’t see a reason to change this requirement that
> may have unintended consequences.
>
>
>
> Comment 2:
>


> NEW
>
> Security Consideration
>
>
>
> Geneve Overlay may be secured using by protecting the NVE-to-NVE
>
> communication using IPsec or DTLS. However, such mechanisms cannot be
>
> applied for deployments that include transit devices.
>
>
>
> Some deployment may not be able to secure the full communication using
>
> IPsec or DTLS between the NVEs. This could be motivated by the presence
>
> of transit devices or by a risk analysis that concludes that the Geneve
>
> packet be only partially protected - typically reduced to the Geneve
>
> Header information. In such cases Geneve specific mechanisms needs to be
>
> designed.
>
>
>
> <Ilango> The challenge is, you are asking to impose requirements that is
> not supported by Geneve architecture. Geneve has an optional feature where
> transit devices may be able to interpret Geneve options. However this is
> not a requirement for Geneve operation between tunnel end point to tunnel
> end point. We have tried make this very clear by adding clarifying text
> during the last two revisions. If the Geneve packet is in the clear then
> transit devices may be able to view the Genve header, options, and the
> payload. However if the packet is encrypted then transit devices cannot
> view the packet contents. This is consistent with other transport protocols
> encrypting the packets. So we don’t see a reason why Geneve should be
> different.
>
>
>
> Geneve is an end to end protocol between tunnel endpoints and the NVEs
> decide to secure (encrypt) the packets between tunnel endpoints. If a
> middle box has a need to see an encrypted packet, then it has to implement
> tunnel endpoint functionality.
>
>
>
> We already have text in 6.4 security consideration section that provides
> clear guidance to the operators.
>
>
>
> So we don’t see a good reason to add the suggested text above.
>
>
>
> For a complete threat analysis, a security analysis of Geneve or some
>
> guide lines to secure a Geneve overlay network, please refer to
>
> [draft-mglt-nvo3-geneve-security-requirements] as well as
>
> [draft-ietf-nvo3-security-requirements].
>
>
>
> <Ilango>
>
> The security requirements document  makes certain assumptions that is
> unsupported by Geneve architecture. We have tried to clarify this multiple
> times, however you have still maintained this in the requirements document.
> So this needs to be addressed. Also the document is not yet adopted by the
> working group.
>
>
>
> Moreover, Geneve security consideration section has been significantly
> enhanced to provide guidance to operators and to address the comments. So
> both documents can progress independently.
>
>
>
> Thanks,
>
> Ilango
>
>
>
>
>
> *From:* Daniel Migault [mailto:[e-mail]]
> *Sent:* Saturday, March 2, 2019 8:49 AM
> *To:* Bocci, Matthew (Nokia - GB) <[e-mail]>
> *Cc:* [e-mail]; Pankaj Garg <pankajg=
> [e-mail]>; NVO3 <[e-mail]>
> *Subject:* Re: [nvo3] Working Group Last Call and IPR Poll for
> draft-ietf-nvo3-geneve-08.txt
>
>
>
> Hi Matt,
>
>
>
>
>
> You are correct, this is at least not an regular process to have a
>
> standard track document being updated by an informational. I do not see
>
> either any requirements for having a WG status to become a reference,
>
> but that is something we could confirm with the RFC-editor.
>
>
>
> Back to the initial suggestion, I also believe the difficulties of
> updating
>
> the Geneve specifications are far less complex than updating the
>
> implementation, and for that specific reason, it would be good we have a
>
> consensus on the security analyse.
>
>
>
> I agree that WG draft would be better, and RFC would be even better as
>
> we have seen WG document being stalled. I am confident we can make this
>
> happen or at least I do not see major issues.
>
>
>
> Yours,
>
> Daniel
>
>
>
>
>
> On Fri, Mar 1, 2019 at 11:51 AM Bocci, Matthew (Nokia - GB) <
> [e-mail]> wrote:
>
> WG, Daniel,
>
>
>
> Apologies but I mis-spoke on the suggestion for the security requirements
> to act as an update to the encapsulation RFC in future. This would be
> difficult to do as it is informational.
>
>
>
> Nonetheless I think we should only be referencing a WG draft (at a
> minimum) here.
>
>
>
> Matthew
>
>
>
>
>
>
>
> *From: *Dacheng Zhang <[e-mail]> on behalf of "Bocci,
> Matthew (Nokia - GB)" <[e-mail]>
> *Date: *Friday, 1 March 2019 at 16:24
> *To: *Daniel Migault <[e-mail]>
> *Cc: *"[e-mail]" <[e-mail]>,
> Pankaj Garg <pankajg=[e-mail]>, NVO3 <[e-mail]>
> *Subject: *Re: [nvo3] Working Group Last Call and IPR Poll for
> draft-ietf-nvo3-geneve-08.txt
>
>
>
> Daniel
>
>
>
> From a procedural perspective, referring to your draft creates a
> dependency and that draft has not yet been adopted by the WG. The old
> Security requirements framework expired a couple of years ago and does not
> seem to be being progressed.
>
> Maybe a better approach to allow progress, as long as the WG can agree to
> your text (if needed) to satisfy the concern that future security
> mechanisms can be used, and that the evolving threat analysis is understood
> by implementers and users of Geneve, would be to mark the Geneve security
> requirements as an update to the geneve encapsulation RFC when it is
> published.
>
>
>
> Matthew
>
>
>
> *From: *Daniel Migault <[e-mail]>
> *Date: *Friday, 1 March 2019 at 16:11
> *To: *"Bocci, Matthew (Nokia - GB)" <[e-mail]>
> *Cc: *Pankaj Garg <pankajg=[e-mail]>, "
> [e-mail]" <[e-mail]>, NVO3 <
> [e-mail]>
> *Subject: *Re: [nvo3] Working Group Last Call and IPR Poll for
> draft-ietf-nvo3-geneve-08.txt
>
>
>
> Hi Matthew,
>
>
>
> I am happy to clarify and be more specific. However, despite your
>
> reading of [1] I think [1] clearly indicates the changes I expected as
>
> well as that these changes needs to be made.
>
>
>
> I believe the responsibility of not addressing an acknowledged issue is
>
> more on the side of people ignoring the issue  then on the side of the
>
> one raising this issue. My impression is that this is the situation we
>
> are in.
>
>
>
> I agree that my initial comment saying "I am fine with the text if we do
>
> not find something better." might have been confusing and I apology for
>
> this. At the time of writing the initial comment I was not sure I was
>
> not missing something nor that the problem could not be solved here or
>
> somewhere else (in another section). My meaning behind those words were
>
> that I was open to the way the concerned could be addressed. However, -
>
> from my point of view - the text does not say the issue does not need to
>
> be solved which is the way it has been interpreted. In addition, I
>
> believe I have clarified this right away after the concern has been
>
> acknowledged and not addressed. As result, I do not think my comment
>
> could be reasonably read as the text is fine.
>
>
>
> Please fine the below the initial comment its response and the response
>
> to the response from [1].
>
>
>
> """
>
> <mglt> In case we have a option providing authentication, such option
>
> may affect the interpretation of the other options.
>
> s/interpretation/ndependance may not be better.... I think what we want
>
> to say is that option MUST be able to be processed in any order or in
>
> parallel.  I am fine with the text if we do not find something better.
>
> </mglt>
>
>
>
> <Ilango> This is a good point, however we believe that this text
>
> captures the intent.  </>
>
>
>
> <mglt2>The problem I have is that the current text prevents security
>
> options, so I guess some clarification should be brought to clarify the
>
> intent.</mglt2>
>
> """
>
>
>
> If I had to suggest some text I would suggest the following - or
>
> something around the following lines.
>
>
>
>
>
> OLD
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option MUST NOT affect the parsing or interpretation of any
>
>       other option.
>
>
>
> NEW
>
>
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option SHOULD NOT affect the parsing or interpretation of any
>
>       other option.
>
>
>
> There are rare cases were the parsing of one option affects the parsing
>
> or the interpretation of other option. Option related to security may
>
> fall into this category. Typically, if an option enables the
>
> authentication of another option and the authentication does not
>
> succeed, the authenticated option MUST NOT be processed. Other options
>
> may be designed in the future.
>
>
>
> NEW
>
> Security Consideration
>
>
>
> Geneve Overlay may be secured using by protecting the NVE-to-NVE
>
> communication using IPsec or DTLS. However, such mechanisms cannot be
>
> applied for deployments that include transit devices.
>
>
>
> Some deployment may not be able to secure the full communication using
>
> IPsec or DTLS between the NVEs. This could be motivated by the presence
>
> of transit devices or by a risk analysis that concludes that the Geneve
>
> packet be only partially protected - typically reduced to the Geneve
>
> Header information. In such cases Geneve specific mechanisms needs to be
>
> designed.
>
>
>
> For a complete threat analysis, a security analysis of Geneve or some
>
> guide lines to secure a Geneve overlay network, please refer to
>
> [draft-mglt-nvo3-geneve-security-requirements] as well as
>
> [draft-ietf-nvo3-security-requirements].
>
>
>
> For full disclosure I am a co-author of
>
> draft-mglt-nvo3-geneve-security-requirement. However the reason for
>
> referring to these documents is motivated by the fact that I believe
>
> these analysis provide a better security analysis than the current (OLD)
>
> security consideration section.
>
>
>
> Yours,
>
> Daniel
>
>
>
>
>
> On Fri, Mar 1, 2019 at 6:03 AM Bocci, Matthew (Nokia - GB) <
> [e-mail]> wrote:
>
> Hi Daniel
>
>
>
> Thanks for reviewing the latest version. At this stage it would be helpful
> if you could be much more concrete and give specifics.
>
>
>
> I think that the main issue is whether the design of Geneve prevents
> future security extensions.
>
>
>
> However, in [1], you stated that you were comfortable with the text if
> nothing else could be found.
>
>
>
> What specifically do you want to change in the following, bearing in mind
> that there are already claimed implementations of Geneve:
>
> """
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option MUST NOT affect the parsing or interpretation of any
>
>       other option.
>
> """
>
>
>
>
>
> Matthew
>
>
>
>
>
> *From: *Daniel Migault <[e-mail]>
> *Date: *Friday, 1 March 2019 at 03:06
> *To: *Pankaj Garg <pankajg=[e-mail]>
> *Cc: *"Bocci, Matthew (Nokia - GB)" <[e-mail]>, NVO3 <
> [e-mail]>, "[e-mail]" <
> [e-mail]>
> *Subject: *Re: [nvo3] Working Group Last Call and IPR Poll for
> draft-ietf-nvo3-geneve-08.txt
>
>
>
> Hi,
>
>
>
> I just briefly went through the document quickly and in my opinion, the
> document still faces some security issues.
>
>
>
> The current text (in my opinion) prevents any geneve security related
>
> options. Currently Geneve cannot be secured and this prevents future
>
> work to eventually secure Geneve. In my opinion the current text
>
> mandates Geneve to remain unsecure.
>
>
>
> Geneve security option that are willing to authenticate/encrypt a part
>
> of the Geneve Header will affect the parsing of the protected option and
>
> will affect the order in which option needs to be process. Typically a
>
> protected option (authenticated, encrypted) cannot or should not be
>
> processed before authenticated or decrypted.
>
>
>
> This has already been mentioned in [1], and the text needs in my opinion
>
> further clarifications.
>
>
>
> """
>
>    o  An option SHOULD NOT be dependent upon any other option in the
>
>       packet, i.e., options can be processed independent of one another.
>
>       An option MUST NOT affect the parsing or interpretation of any
>
>       other option.
>
> """
>
>
>
>
>
>
>
> As stated in [2] it remains unclear to me why this section is not
>
> referencing and leveraging on the security analysis [3-4] performed by
>
> two different independent teams.
>
>
>
> My reading of the security consideration is that the message is that
>
> IPsec or TLS could be used to protect a geneve overlay network. This is
>
> - in my opinion- not correct as this does not consider the transit
>
> device. In addition, the security consideration only considers the case
>
> where the cloud provider and the overlay network provider are a single
>
> entity, which I believe oversimplifies the problem.
>
>
>
> The threat model seems to me very vague, so the current security
>
> consideration is limited to solving a problem that is not stated.
>
>
>
> My reading of the text indicates the tenant can handle by itself the
>
> confidentiality of its information without necessarily relying on the
>
> overlay service provider. This is not correct. Even when the tenant uses
>
> IPsec/TLS, it still leaks some information. The current text contradicts
>
> [3] section 6.2 and [4] section 5.1.
>
>
>
> My reading is that the text indicates that IPsec/DTLS could be used to
>
> protect the overlay service for both confidentiality and integrity.
>
> While this could be used in some deployment this is not compatible with
>
> transit devices. As such the generic statement is not correct. Section
>
> 6.4 indicates that transit device must be trusted which is incorrect.
>
> Instead the transit device with all nodes between the transit device and
>
> the NVE needs to be trusted.  Overall the impression provided is that
>
> IPsec (or TLS) can be used by the service overlay provider, which is (in
>
> my opinion) not true.
>
>
>
> It is unclear to me how authentication of NVE peers differs from the
>
> authentication communication as the latest usually rely on the first.
>
> Maybe the section should insist on mutual authentication.
>
>
>
> Yours,
>
> Daniel
>
>
>
>
>
> [1] https://mailarchive.ietf.org/arch/msg/nvo3/RFFjYHAUUlMvOsYwRNtdOJOIk9o
>
> [2] https://mailarchive.ietf.org/arch/msg/nvo3/e7YHFlqIuOwIJoL2ep7jyHIrSGw
>
> [3] https://tools.ietf.org/html/draft-ietf-nvo3-security-requirements-07
>
> [4]
> https://tools.ietf.org/html/draft-mglt-nvo3-geneve-security-requirements-05
>
>
>
>
>
>
>
>
>
>
>
> On Wed, Feb 27, 2019 at 7:30 PM Pankaj Garg <pankajg=
> [e-mail]> wrote:
>
> I am not aware of any IP related to draft-ietf-nvo3-geneve which has not
> already been disclosed.
>
>
>
> Thanks
>
> Pankaj
>
>
>
> *From:* Bocci, Matthew (Nokia - GB) <[e-mail]>
> *Sent:* Tuesday, October 9, 2018 2:08 AM
> *To:* NVO3 <[e-mail]>
> *Cc:* [e-mail]
> *Subject:* Working Group Last Call and IPR Poll for
> draft-ietf-nvo3-geneve-08.txt
>
>
>
> This email begins a two-week working group last call for
> draft-ietf-nvo3-geneve-08.txt.
>
>
>
> Please review the draft and post any comments to the NVO3 working group
> list. If you have read the latest version of the draft but have no comments
> and believe it is ready for publication as a standards track RFC, please
> also indicate so to the WG email list.
>
>
>
> We are also polling for knowledge of any undisclosed IPR that applies to
> this document, to ensure that IPR has been disclosed in compliance with
> IETF IPR rules (see RFCs 3979, 4879, 3669 and 5378 for more details).
>
> If you are listed as an Author or a Contributor of this document, please
> respond to this email and indicate whether or not you are aware of any
> relevant undisclosed IPR. The Document won't progress without answers from
> all the Authors and Contributors.
>
>
>
> Currently there are two IPR disclosures against this document.
>
>
>
> If you are not listed as an Author or a Contributor, then please
> explicitly respond only if you are aware of any IPR that has not yet been
> disclosed in conformance with IETF rules.
>
>
>
> This poll will run until Friday 26th October.
>
>
>
> Regards
>
>
>
> Matthew and Sam
>
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