Re: [secdir] Secdir review (early review) of draft-ietf-nvo3-geneve

Magnus Nyström <magnusn@gmail.com> Wed, 07 November 2018 07:20 UTC

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From: =?UTF-8?Q?Magnus_Nystr=C3=B6m?= <magnusn@gmail.com>
Date: Tue, 6 Nov 2018 23:19:49 -0800
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To: "Ganga, Ilango S" <ilango.s.ganga@intel.com>
Cc: secdir@ietf.org, draft-ietf-nvo3-geneve@ietf.org
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Subject: Re: [secdir] Secdir review (early review) of draft-ietf-nvo3-geneve
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Hi Ilango,
Thanks for your thorough follow-up. To me, the new text looks very good.
You could shorten (and perhaps add clarity) by replacing "Hence an
option..." with just "An option ..."

Thanks,
/M

On Tue, Nov 6, 2018 at 7:11 PM Ganga, Ilango S <ilango.s.ganga@intel.com>
wrote:

> Hi Magnus,
>
>
>
> Here is our proposed text that we believe will satisfy your comment on
> 3.5.1:
>
>
>
> *In Section 2.2.1 add new highlighted text in paragraph that began with
> “Transit devices..”*
>
> Options, if present in the packet, MUST be generated and terminated by end
> points. Transit devices MAY be able to interpret the options, however, as
>
>    non-terminating devices, transit devices do not originate or
>
>    terminate the Geneve packet, hence MUST NOT insert or delete options,
>
>    which is the responsibility of Geneve endpoints.  The participation
>
>    of transit devices in interpreting options is OPTIONAL.
>
>
>
>
>
> *Section 3.5.1 - Remove the highlighted text:*
>
> o  Some options may be defined in such a way that the position in the
>
>       option list is significant.  Options or their ordering, MUST NOT
>
>       be changed by transit devices.
>
>
>
> *Section 3.5.1 - Add highlighted text to the last bullet:*
>
>    o  *An option SHOULD NOT be dependent upon any other option in the
> packet, *
>
> * i.e., options can be processed independent of one another. Hence* an
> option MUST NOT affect the parsing or interpretation of any other option.
>
>
>
> *Remove the following paragraph from 6.2:*
>
> Geneve supports Geneve Options, so an operator may choose to use a
>
>    Geneve option TLV to provide a cryptographic data protection
>
>    mechanism, to verify the data integrity of the Geneve header, Geneve
>
>    options or the entire Geneve packet including the payload.
>
>    Implementation of such a mechanism is beyond the scope of this
>
>    document.
>
>
>
> *Introduce new section after 6.3 as follows:*
>
> 6.4  Options Interpretation by Transit Devices
>
>
>
> Options, if present in the packet, are generated and terminated by end
> points. As indicated in 2.2.1, transit devices may interpret the options.
> However, if the packet is protected by end point to end point encryption,
> for example through IPsec, transit devices will not have visibility into
> the Geneve header or options in the packet. In cases where options are
> interpreted by transit devices, the operator MUST ensure that transit
> devices are trusted and not compromised. Implementation of a mechanism to
> ensure this trust is beyond the scope of this document.
>
>
>
> Please let us know if this addresses your comment on 3.5.1.  The other two
> comments have been satisfied as noted below.
>
>
>
> Thanks,
>
> Ilango
>
>
>
>
>
> *From:* Magnus Nyström [mailto:magnusn@gmail.com]
> *Sent:* Wednesday, October 31, 2018 11:34 AM
> *To:* Ganga, Ilango S <ilango.s.ganga@intel.com>om>; secdir@ietf.org;
> draft-ietf-nvo3-geneve@ietf.org
> *Subject:* RE: Secdir review (early review) of draft-ietf-nvo3-geneve
>
>
>
> Hi Ilango,
>
> For 3.4, I think this may be sufficient.
>
>
>
> For 6.2, I will defer to the IETF director/telechat discussion that will
> occur at some point for this draft. If the intent is interoperability and
> robustness of such an option, then I would recommend it to be specified in
> the IETF, but I can also see how you would prefer that such specification
> work occurs outside this particular draft – which should be doable. Perhaps
> staying silent on the option alternative and just recommend leveraging
> layer-provided infrastructure such as ipsec may be best for now?
>
>
>
> I'll await your suggested updated language for 3.5.1.
>
>
>
> Thanks,
>
>
>
> Sent from my Windows 10 phone
>
>
>
> *From: *Ganga, Ilango S <ilango.s.ganga@intel.com>
> *Sent: *Tuesday, October 30, 2018 18:12
> *To: *Magnus Nyström <magnusn@gmail.com>om>; secdir@ietf.org;
> draft-ietf-nvo3-geneve@ietf.org
> *Subject: *RE: Secdir review (early review) of draft-ietf-nvo3-geneve
>
>
>
> Hi Magnus,
>
>
>
> Thanks for your review and feedback. Please see inline for my responses.
>
>
>
> Regards,
>
> Ilango
>
>
>
>
>
> *From:* Magnus Nyström [mailto:magnusn@gmail.com <magnusn@gmail.com>]
> *Sent:* Tuesday, October 23, 2018 9:01 PM
> *To:* secdir@ietf.org; draft-ietf-nvo3-geneve@ietf.org
> *Subject:* Secdir review (early review) of draft-ietf-nvo3-geneve
>
>
>
> I have reviewed this document as part of the security directorate's
> ongoing effort to review all IETF documents being processed by the
> IESG. These comments were written primarily for the benefit of the
> security area directors.  Document editors and WG chairs should treat
> these comments just like any other last call comments.
>
>
>
> This document describes "Geneve," a protocol for GEneric NEtwork
> Virtualization Encapsulation. The document is written in a clear manner and
> with a thorough Security Considerations section. I have just a few
> questions/comments:
>
>
>
> - Section 3.4: The "MUST ignore" for the reserved bits should presumably
> state "SHALL be ignored for this version of the Geneve protocol." - as I
> imagine that in a future version, these bits may not be ignored?
>
>
>
> <Ilango> In theory, a future version may change the behavior of any of the
> header fields including the reserved bits.  The header definition is for
> this version of the protocol.
>
>
>
> Please see if the following text would satisfy the intent of your comment.
>
> “Reserved field which MUST be zero on transmission and *MUST be* ignored
> on receipt.”
>
>
>
> Or let us know if you still want to have this qualified with “for this
> version of the protocol”
>
> </>
>
>
>
> - Section 3.5.1: I wonder about the simultaneous requirement that one
> option must not affect the parsing or interpretation of another option but
> that the sequencing (order) of options may be significant - they seem to be
> contradictory since if the sequencing *is* significant, then some option
> must be impacted by a previous one's value? From a security perspective, I
> also wonder if there could be security consequences of re-ordering options
> (and how to tell if someone did re-order - see below)?
>
>
>
> <Ilango> You raise a good point. The intent of this statement is, parsing
> and interpretation of options should not be dependent on one another. We
> are discussing among the authors to see how we can include appropriate
> clarifying statements to address your point. I will update you shortly.
>
> </>
>
>
>
> - Section 6.2, shouldn't such an Option be defined to reduce the risk of
> under-specified or subpar specifications of such integrity mechanisms? Or
> also from an interop perspective?
>
>
>
> <Ilango> Using a Geneve option for the purpose of data integrity is more
> of an optimization. Otherwise data integrity could be provided by using
> existing mechanisms like IPsec (as stated in second paragraph of 6.2). We
> included the last paragraph to show other possibilities. We could remove
> this paragraph if it may cause any confusion.
>
>
>
> We would like to keep the Geneve base specification independent of options
> specifications, options could be a defined in a future standards action.
>
> </>
>
>
>
>
>
> Thanks.
>
> -- Magnus
>
>
>


-- 
-- Magnus