[lp-wan] YANG security section

[Laurent Toutain <[e-mail]>]

Hi lpwaners,

I'm working on the security section of the SCHC YANG draft. It is here a
first attempt to reflect what we discussed during the meeting.

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# Security Considerations

The YANG module specified in this document defines a schema for data that
is designed to be accessed via network management protocols such as NETCONF
{{!RFC6241}} or RESTCONF {{!RFC8040}}. The lowest NETCONF layer is the
secure transport layer, and the mandatory-to-implement secure transport is
Secure Shell (SSH) {{!RFC6242}}. The lowest RESTCONF layer is HTTPS, and
the mandatory-to-implement secure transport is TLS
{{!RFC8446}}.

The Network Configuration Access Control Model (NACM) {{!RFC8341}} provides
the means to restrict access for particular NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.

This data model formalizes the rules elements described in {{RFC8724}} for
compression and fragmentation. As explained in the architecture document
{{I-D.ietf-lpwan-architecture}}, a rule can be read, created, updated or
deleted in response to a management request. These actions can be done
between two instances of SCHC or between a SCHC instance and a rule
repository.

~~~~~
                     create
          (-------)  read   +=======+ *
          ( rules )<------->|Rule   |<--|-------->
          (-------)  update |Manager|   NETCONF, RESTCONF or CORECONF
             . read  delete +=======+   request
             .
          +-------+
      <===| R & D |<===
      ===>| C & F |===>
          +-------+
~~~~~

The rule contains some sensible informations such as the application IPv6
address. An attacker by changing a rule content may block the communication
or intercept the traffic. Therefore, the identity of the requester must be
validated. This can be done through certificates or access lists.

The full tree is sensible
----

We need also to discuss that point on the architecture draft.

Laurent