Hi Acee!

Thanks for the explanation.  More inline …

From: Acee Lindem (acee) [mailto:a...@cisco.com]
Sent: Wednesday, August 21, 2019 1:51 PM
To: Alvaro Retana <aretana.i...@gmail.com>; draft-ietf-ospf-y...@ietf.org
Cc: Roman Danyliw <r...@cert.org>; Stephane Litkowski 
<stephane.litkow...@orange.com>; lsr-cha...@ietf.org; lsr@ietf.org; The IESG 
<i...@ietf.org>
Subject: Re: Roman Danyliw’s DISCUSS on draft-ietf-ospf-yang-26

Hi Roman,

Discussion on discuss.

From: Alvaro Retana <aretana.i...@gmail.com<mailto:aretana.i...@gmail.com>>
Date: Wednesday, August 21, 2019 at 11:11 AM
To: "draft-ietf-ospf-y...@ietf.org<mailto:draft-ietf-ospf-y...@ietf.org>" 
<draft-ietf-ospf-y...@ietf.org<mailto:draft-ietf-ospf-y...@ietf.org>>
Cc: Roman Danyliw <r...@cert.org<mailto:r...@cert.org>>, Stephane Litkowski 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>, 
"lsr-cha...@ietf.org<mailto:lsr-cha...@ietf.org>" 
<lsr-cha...@ietf.org<mailto:lsr-cha...@ietf.org>>, 
"lsr@ietf.org<mailto:lsr@ietf.org>" <lsr@ietf.org<mailto:lsr@ietf.org>>, The 
IESG <i...@ietf.org<mailto:i...@ietf.org>>
Subject: Roman Danyliw’s DISCUSS on draft-ietf-ospf-yang-26
Resent-From: <alias-boun...@ietf.org<mailto:alias-boun...@ietf.org>>
Resent-To: Yingzhen Qu 
<yingzhen.i...@gmail.com<mailto:yingzhen.i...@gmail.com>>, Christian Hopps 
<cho...@chopps.org<mailto:cho...@chopps.org>>, Acee Lindem 
<a...@cisco.com<mailto:a...@cisco.com>>
Resent-Date: Wednesday, August 21, 2019 at 11:08 AM

[It looks like the datatracker didn’t send out the text to Roman’s DISCUSS.  I 
didn’t receive it, nor do I see it in the mail archive.  So I’m pasting it 
here. — Alvaro.]

- - - - - - - - - - -
DISCUSS
- - - - - - - - - - -

A “discuss to discuss”.  Per the convention outlined in 
https://trac.ietf.org/trac/ops/wiki/yang-security-guidelines, thank you for 
clearly noting the implication of not securing these nodes properly.

Furthermore, following the convention, I would have expected Section 4 to have 
enumerated the sensitive writeable/creatable/deletable data nodes; and the 
sensitive readable nodes individually.  For a model this large, I can imagine 
that individual enumeration would be a long list.

It doesn’t make sense to talk about every configurable leaf so the section 
describes the general problems that can ensue if OSPF protocol configuration is 
compromised. We could go into classes of writeable nodes but I question what 
benefit that would actually have.

[Roman]  It was thinking this would be the case.  I don’t think we need the 
specificity.


In the case of read operations, the text opens with saying that “some of the 
readable data nodes ...” and later says “The exposure of the ... LSDB will 
expose the detailed topology ...”.  Can you help me understand which part of 
ietf-ospf.yang is the LSDB and which parts refer to “some of the readable 
nodes”?  Is there are a difference, or is this text asserting that all parts of 
the modules are sensitive and need access control?

The LSDB refers to the instance, area, virtual link, sham-link, and interface 
Link State DataBases (LSDB).

             /ospf/database
            /ospf/areas/area[area-id]/database
            /ospf/virtual-links/virtual-link[transit-area-id router-id]/database
            /ospf/areas/area[area-id]/interfaces/interface[name]/database
            /ospf/area/area[area-id]/sham-links/sham-link[local-id 
remote-id]/database

[Roman] Thanks for this clarification.  IMO, it wouldn’t hurt to enumerate this 
list as being part of the LSDB (this is not DISCUS-level feedback)

All parts are sensitive. The LSDB is more so since it gives visibility beyond 
the network device itself.

[Roman]  I agree with “all parts are sensitive” assessment without enumerating 
the individual nodes of the model.  The conflict for me is that the opening 
sentence of this discussion is a much weaker statement of “Some of the readable 
data nodes in the ietf-ospf.yang module may be considered sensitive or 
vulnerable in some network environments.  It is thus important to control read 
access (e.g., via get, get-config, or notification) to these data nodes.”  
Would it be a problem to say something on the order of “The readable data nodes 
in the ietf-ospf.yang module are sensitive. Thus, it is thus important to 
control read access … to them.”?  This edit make clear that “all parts are 
sensitive”.

A related line of questioning for the write operation.  The text opens with 
saying that “There are a number of data nodes defined in ietf-ospf.yang ... 
[and that] [w]rite operations ... to these nodes without proper protection can 
have a negative effect on the network operations ... [and] ... the ability to 
modify OSPF configuration” is problematic.  Can you help me understand which 
parts of the text is the “OSPF configuration” vs. “there are number of data 
nodes ...”?  If there isn’t a different, is the text asserting that all parts 
of the modules are sensitive and need access control?

This is alludes to the “config true” nodes which comprise OSPF configuration. I 
guess this is a repeat of your first comment.

[Roman] Exactly.  The text wasn’t clear on whether you meant part of all of the 
model should have access control  Would a similar approach to the above be 
possible here too – say deleting the sentence “These data nodes may be 
considered sensitive of vulnerable in some network environments.”  By making 
this edit, the text will then read that all of the write operations are 
sensitive.

Regards,
Roman

Thanks,
Acee


- - - - - - - - - - -
COMMENT
- - - - - - - - - - -

(1) Idnits returned a seemingly valid few reference issues:

  ** Downref: Normative reference to an Experimental RFC: RFC 1765

  ** Downref: Normative reference to an Experimental RFC: RFC 4973

(2) Editorial
-- Section 4.  Isn’t RFC8341, “the Network Configuration Access Control Model” 
rather than the “NETCONF access control model”?

-- Section 4.  Typo.  s/specificationn/specification/

-- Section 4.  Remove the duplicate instance of the phrase “for legacy 
implementations that do not support key-chains”.

-- Section 4.  Typo.  s/The OSPF YANG module support/the OSPF YANG module 
supports/

Alvaro Retana
_______________________________________________
Lsr mailing list
Lsr@ietf.org
https://www.ietf.org/mailman/listinfo/lsr

Reply via email to