Re: [netmod] Eric Rescorla's Discuss on draft-ietf-netmod-schema-mount-11: (with DISCUSS)
Martin Bjorklund <mbj@tail-f.com> Wed, 17 October 2018 07:24 UTC
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Date: Wed, 17 Oct 2018 09:24:51 +0200
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Subject: Re: [netmod] Eric Rescorla's Discuss on draft-ietf-netmod-schema-mount-11: (with DISCUSS)
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Hi, Eric Rescorla <ekr@rtfm.com> wrote: > OK, after reading your explanation and the example, I think I am clearer on > the use case and the text you propose seems appropriate. Why don't you > provide a new ID and I'll clear my DISCUSS Thank you! I have fixed this and uploaded a new version (draft-ietf-netmod-schema-mount-12). /martin > > -Ekr > > > On Tue, Oct 16, 2018 at 9:05 AM joel jaeggli <joelja@gmail.com> wrote: > > > On 10/16/18 06:00, Eric Rescorla wrote: > > > I'm sorry, but I still don't think I understand the security impacts of > > > this well enough to know if this text is OK. > > > > > > Can you provide a more detailed explanation of what XPath expressions > > > can and cannot do here? Happy to discuss live either on the phone or in > > BKK > > I'm probably grossly simplifying the goal here, but. > > > > xpath statement allow for referencing another path or applying > > constraints e.g. when / must (rfc 6020) > > > > the canonical example in 6020 being something like > > > > container interface { > > leaf ifType { > > type enumeration { > > enum ethernet; > > enum atm; > > } > > } > > leaf ifMTU { > > type uint32; > > } > > must "ifType != 'ethernet' or " + > > "(ifType = 'ethernet' and ifMTU = 1500)" { > > error-message "An ethernet MTU must be 1500"; > > } > > must "ifType != 'atm' or " + > > "(ifType = 'atm' and ifMTU <= 17966 and ifMTU >= 64)" { > > error-message "An atm MTU must be 64 .. 17966"; > > } > > > > http://www.yang-central.org/twiki/pub/Main/YangDocuments/rfc6020.html#xpath > > > > Imposing constraints using nodes in mounted modules is kind of a key > > application of schema-mount. > > > > > -Ekr > > > > > > > > > On Tue, Oct 16, 2018 at 5:45 AM Martin Bjorklund <mbj@tail-f.com > > > <mailto:mbj@tail-f.com>> wrote: > > > > > > Hi, > > > > > > Eric Rescorla <ekr@rtfm.com <mailto:ekr@rtfm.com>> wrote: > > > > That seems like it's going to have some pretty surprising > > > consequences and > > > > at minimum needs more information in the Security Considerations. > > > > > > Ok. Howabout we add a paragraph to the end of the Security > > > Considerations section: > > > > > > Care must be taken when the "parent-reference" XPath expressions > > are > > > constructed, since the result of the evaluation of these > > expressions > > > is added to the accessible tree for any XPath expression found in > > > the mounted schema. > > > > > > > > > /martin > > > > > > > On Thu, Oct 11, 2018 at 12:18 AM Martin Bjorklund <mbj@tail-f.com > > > <mailto:mbj@tail-f.com>> wrote: > > > > > > > > > Eric Rescorla <ekr@rtfm.com <mailto:ekr@rtfm.com>> wrote: > > > > > > 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 > > > > > > > > > > Yes, but note that these XPath expressions ("parent-reference") > > are > > > > > read-only (config false in the YANG model). Thus they are set > > > by the > > > > > implementation, and used to inform the operator about the > > > environment > > > > > in which other XPath expressions are evaluated. > > > > > > > > > > > > > > > /martin > > > > > > > > > > > > > > > > > > > > > > -Ekr > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Wed, Oct 10, 2018 at 6:38 AM Martin Bjorklund > > > <mbj@tail-f.com <mailto:mbj@tail-f.com>> wrote: > > > > > > > > > > > > > Eric Rescorla <ekr@rtfm.com <mailto:ekr@rtfm.com>> wrote: > > > > > > > > On Wed, Oct 10, 2018 at 5:32 AM Martin Bjorklund > > > <mbj@tail-f.com <mailto:mbj@tail-f.com>> > > > > > wrote: > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > Eric Rescorla <ekr@rtfm.com <mailto: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 > > > > > > > > > > > > > > > > > > > > >
- [netmod] Eric Rescorla's Discuss on draft-ietf-ne… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Martin Bjorklund
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Martin Bjorklund
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Martin Bjorklund
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Martin Bjorklund
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… joel jaeggli
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… joel jaeggli
- Re: [netmod] Eric Rescorla's Discuss on draft-iet… Martin Bjorklund