Re: [netmod] Eric Rescorla's Discuss on draft-ietf-netmod-schema-mount-11: (with DISCUSS)

Eric Rescorla <ekr@rtfm.com> Wed, 10 October 2018 16:30 UTC

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References: <153914105176.10625.9957580509164313779.idtracker@ietfa.amsl.com> <20181010.143257.2013021260712498361.mbj@tail-f.com> <CABcZeBMofmqzptj_w-CH+0TSMXj1jT0dE4KP4r2eJqijSsYQxg@mail.gmail.com> <20181010.153831.1958991667250114039.mbj@tail-f.com>
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From: Eric Rescorla <ekr@rtfm.com>
Date: Wed, 10 Oct 2018 09:29:35 -0700
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To: mbj@tail-f.com
Cc: IESG <iesg@ietf.org>, NetMod WG Chairs <netmod-chairs@ietf.org>, NetMod WG <netmod@ietf.org>, joelja@gmail.com, draft-ietf-netmod-schema-mount@ietf.org, Kent Watsen <kwatsen@juniper.net>, Lou Berger <lberger@labn.net>
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Subject: Re: [netmod] Eric Rescorla's Discuss on draft-ietf-netmod-schema-mount-11: (with DISCUSS)
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I'm sorry but I don't understand this.

Does the externally visible behavior of any mounted module depend in any
way on these XPATH references

-Ekr




On Wed, Oct 10, 2018 at 6:38 AM Martin Bjorklund <mbj@tail-f.com> wrote:

> Eric Rescorla <ekr@rtfm.com> wrote:
> > On Wed, Oct 10, 2018 at 5:32 AM Martin Bjorklund <mbj@tail-f.com> wrote:
> >
> > > Hi,
> > >
> > > Eric Rescorla <ekr@rtfm.com> wrote:
> > > > Eric Rescorla has entered the following ballot position for
> > > > draft-ietf-netmod-schema-mount-11: Discuss
> > > >
> > > > When responding, please keep the subject line intact and reply to all
> > > > email addresses included in the To and CC lines. (Feel free to cut
> this
> > > > introductory paragraph, however.)
> > > >
> > > >
> > > > Please refer to
> > > https://www.ietf.org/iesg/statement/discuss-criteria.html
> > > > for more information about IESG DISCUSS and COMMENT positions.
> > > >
> > > >
> > > > The document, along with other ballot positions, can be found here:
> > > > https://datatracker.ietf.org/doc/draft-ietf-netmod-schema-mount/
> > > >
> > > >
> > > >
> > > >
> ----------------------------------------------------------------------
> > > > DISCUSS:
> > > >
> ----------------------------------------------------------------------
> > > >
> > > > Rich version of this review at:
> > > > https://mozphab-ietf.devsvcdev.mozaws.net/D3506
> > > >
> > > >
> > > >
> > > > DETAIL
> > > > S 4.
> > > > >
> > > > >      It is worth emphasizing that the nodes specified in
> > > > >      "parent-reference" leaf-list are available in the mounted
> schema
> > > only
> > > > >      for XPath evaluations.  In particular, they cannot be accessed
> > > there
> > > > >      via network management protocols such as NETCONF [RFC6241] or
> > > > >      RESTCONF [RFC8040].
> > > >
> > > > What are the security implications of this XPath reference outside
> the
> > > > mount jail? Specifically, how does it interact with the access
> control
> > > > for the enclosing module.
> > >
> > > There is no such interaction, since access control comes into play
> > > when some external entity accesses the data through some management
> > > protocol, and the nodes from the "parent-reference" expressions cannot
> > > be accessed via management protocols.
> > >
> > > The last sentence of the quoted paragraph was supposed to make this
> > > clear, but it seems we might need some additional explanation?
> > >
> >
> > Yes, I think so. I guess I'm not clear on what the XPath expressions are
> > for if they
> > can't be accessed via the management protocols. How can they be used?
>
> These are XPath expressions defined in the YANG models themselves,
> such as "must" expressions or "leafrefs".   The description of
> "parent-reference" refer to them as:
>
>                [...] XPath
>                expressions whose context nodes are defined in the
>                mounted schema
>
>
>
> /martin
>