Re: [Gen-art] Genart last call review of draft-wu-l3sm-rfc8049bis-07

["Adrian Farrel" <[e-mail]>]

Top-posting 'cos I'm lazy.

We need to be careful to not confuse two aspects of security in this model.
One is security in the use of the model: who can read and write to the operator, whether the data is protected in transit, etc.
The other is security within the VPN that is modelled: how sites secure their access to the VPN, how VPN data is protected.

The former is handled by the protocol used to exchange the model. We assume Netconf, and that comes with a variety of security features.
The latter is about what VPN (or VPN site) behaviour is configured.

All that said, the points about authentication and authorisation are well made. Authorisation based on unauthenticated identity is not strong security (basically equates to "guess a valid user name").

A

> -----Original Message-----
> From: ietf [mailto:[e-mail]] On Behalf Of tom p.
> Sent: 26 October 2017 12:10
> To: Qin Wu; Jari Arkko; [e-mail]
> Cc: [e-mail]; [e-mail]
> Subject: Re: Genart last call review of draft-wu-l3sm-rfc8049bis-07
> 
> < see inline>
> Tom Petch
> 
> 
> ----- Original Message -----
> From: "Qin Wu" <[e-mail]>
> Sent: Thursday, October 26, 2017 8:02 AM
> 
> > -----邮件原件-----
> > 发件人: Jari Arkko [mailto:[e-mail]]
> > 发送时间: 2017年10月26日 4:53
> >
> > Reviewer: Jari Arkko
> > Review result: Ready with Issues
> >
> > I am the assigned Gen-ART reviewer for this draft. The General Area
> Review Team (Gen-ART) reviews all IETF documents being processed by the
> IESG for the IETF Chair.  Please treat these comments just like any
> other last call comments.
> >
> > For more information, please see the FAQ at
> >
> > <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.
> >
> > Document: draft-wu-l3sm-rfc8049bis-??
> > Reviewer: Jari Arkko
> > Review Date: 2017-10-25
> > IETF LC End Date: 2017-10-11
> > IESG Telechat date: 2017-10-26
> >
> > Summary: I'm not an expert on YANG *at all*. And not an expert on the
> topic in question either. And I had far too little time to spend on this
> long document.
> > But as far as the textual content of the document goes, it seems
> reasonable. I have a difficulty in assessing how complete and
> implementable this model is however. Are there implementations?
> >
> > [Qin]: Yes, there are implementations, something broken in RFC8049
> needs to get right.
> >
> > I did enjoy the classification of Internet connectivity as a special
> case of cloud service :-) You may be onto something.
> >
> > [Qin]:Yes, internet connectivity is special example of public cloud,
> in my understanding,:-)
> >
> > I did observe a couple of question marks or issues that probably
> deserve some thought or small revisions.
> >
> > Major issues: -
> >
> > Minor issues:
> >
> > I'm not sure I fully understand the need for "SP MUST honour
> <requirement>"
> > language in the document. Are there parts of the described model that
> they SP is *not* required to honour? Other than the explicit strict
> true/false settings? And in any case, sizeable networks are likely to
> have issues that might require negotiation/human involvement.
> >
> > [Qin]: Explicit settings are covered by sub-section of section 6.6,
> such as device constraint, Site Location constraint/parameter, access
> type.
> > Unlike RFC8049, RFC8049bis change "SP SHOULD honor" into "SP MUST
> honor".
> >
> > I don't understand how 6.9.1 can say there is no authentication
> support but then 6.9.2 (encryption) talks about authentication keys. I'd
> suggest some rethinking or at least clarification might be needed here.
> >
> > [Qin]: Authentication provides you access to a resource like a
> computer or a network. Encryption provides confidentiality and controls
> whether an object can be read or not.
> 
> Qin
> 
> I do not see that usage as common in the IETF and I think that it
> reflects a fundamental flaw in this model such that the I-D should not
> go forward in its present form, except that the same flaw is present in
> RFC8049:-(
> 
> Authentication is the process of establishing that a person or object is
> who or what they claim to be, using e.g. pre-shared keys or
> certificates, in an authentication protocol.
> 
> Authorisation is the process of granting rights, privileges, access and
> such like to an authenticated identity.
> 
> Authorisation without authentication is meaningless, a fantasy of
> security
> 
> Scanning the I-D, I think that the usage of authorisation and
> authentication is mostly correct.  As the I-D points it, there is no
> support in the standard model for authentication.  Where the I-D is
> wrong, perhaps dangerously so, is in the Security Considerations where
> it says that because NETCONF may have used TLS or SSH to establish the
> connection, and the NETCONF Access Control may be used to control
> authorisation, then somehow this is secure.
> 
> You haven't a clue what identity has been authenticated and whether or
> not they should be authorised to join a VPN.  This is a common problem
> with applications running over a secure transport, the transport may
> have autheticated an identity but how do you get that identity up to the
> application for the application to verify that the identity really is
> ok?  Channel Binding is one answer but rarely used.
> 
> Tom Petch
> 
> > Both Authentication and Encryption are site level parameters and
> applicable to site connection. Pre-share key as encryption parameter can
> be used, e.g., for routing protocol authentication.
> > But pre-share key parameter is not authentication parameter, one
> example I have for authentication parameter is authentication algorithm
> which is not specified in the model,
> > We will see how to clarify this in the model. thanks.
> >
> > In the security considerations, I would note that if these models are
> used not merely for creation of networks, but also their modification,
> the consequences of inadvertent or malicious modifications can severe
> and network wide. Perhaps that could be discussed.
> >
> > [Qin]:Security consideration section has already considered both
> creation of networks and but also their modification, see the text in
> security consideration section as follows:
> > "
> >    The data nodes defined in the "ietf-l3vpn-svc" YANG module MUST be
> >    carefully created, read, updated, or deleted as appropriate.
> > "
> >
> > Nits/editorial comments:
> >
> > Section 6.12.2. s/fragmented/fragment it/
> >
> > [Qin]: Will fix this, thanks.
> >