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Versions: (draft-kwatsen-netconf-trust-anchors) 00 01 02 03 04 05 06 07

NETCONF Working Group                                          K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                             H. Birkholz
Expires: May 4, 2020                                      Fraunhofer SIT
                                                        November 1, 2019


                   A YANG Data Model for a Truststore
                  draft-ietf-netconf-trust-anchors-07

Abstract

   This document defines a YANG 1.1 data model for configuring global
   sets of X.509 certificates, SSH host-keys, raw public keys, and PSKs
   (pairwise-symmetric or pre-shared keys) that can be referenced by
   other data models for trust.  While the SSH host-keys are uniquely
   for the SSH protocol, certificates, raw public keys, and PSKs may
   have multiple uses, including authenticating protocol peers and
   verifying signatures.

Editorial Note (To be removed by RFC Editor)

   This draft contains many placeholder values that need to be replaced
   with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.  No other RFC
   Editor instructions are specified elsewhere in this document.

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements:

   o  "XXXX" --> the assigned RFC value for this draft

   o  "YYYY" --> the assigned RFC value for draft-ietf-netconf-crypto-
      types

   Artwork in this document contains placeholder values for the date of
   publication of this draft.  Please apply the following replacement:

   o  "2019-11-02" --> the publication date of this draft

   The following Appendix section is to be removed prior to publication:

   o  Appendix A.  Change Log








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Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 4, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Tree Diagram Notation . . . . . . . . . . . . . . . . . .   3
   2.  The Trust Anchors Model . . . . . . . . . . . . . . . . . . .   3
     2.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   8
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .   9
     4.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  10
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     5.2.  Informative References  . . . . . . . . . . . . . . . . .  10



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   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  12
     A.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  13
     A.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  13
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   This document defines a YANG 1.1 [RFC7950] data model for configuring
   global sets of X.509 certificates, SSH host-keys, raw public keys,
   and PSKs (pairwise-symmetric or pre-shared keys) that can be
   referenced by other data models for trust.  While the SSH host-keys
   are uniquely for the SSH protocol, certificates, raw public keys, and
   PSKs may have multiple uses, including authenticating protocol peers
   and verifying signatures.

   This document in compliant with Network Management Datastore
   Architecture (NMDA) [RFC8342].  For instance, to support trust
   anchors installed during manufacturing, it is expected that such data
   would appear only in <operational>.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  Tree Diagram Notation

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

2.  The Trust Anchors Model

2.1.  Tree Diagram

   The following tree diagram provides an overview of the "ietf-
   truststore" module.

   module: ietf-truststore
     +--rw truststore



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        +--rw certificates* [name] {x509-certificates}?
        |  +--rw name           string
        |  +--rw description?   string
        |  +--rw certificate* [name]
        |     +--rw name                      string
        |     +--rw cert                      trust-anchor-cert-cms
        |     +---n certificate-expiration
        |        +-- expiration-date    yang:date-and-time
        +--rw host-keys* [name] {ssh-host-keys}?
        |  +--rw name           string
        |  +--rw description?   string
        |  +--rw host-key* [name]
        |     +--rw name        string
        |     +--rw host-key    ct:ssh-host-key
        +--rw psks* [name] {psks}?
        |  +--rw name           string
        |  +--rw description?   string
        |  +--rw psk* [name]
        |     +--rw name    string
        |     +--rw psk     ct:psk
        +--rw raw-public-keys* [name] {raw-public-keys}?
           +--rw name              string
           +--rw description?      string
           +--rw raw-public-key* [name]
              +--rw name              string
              +--rw raw-public-key    ct:raw-public-key

     grouping local-or-truststore-certs-grouping
       +-- (local-or-truststore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- cert*                     trust-anchor-cert-cms
          |     +---n certificate-expiration
          |        +-- expiration-date    yang:date-and-time
          +--:(truststore) {truststore-supported,x509-certificates}?
             +-- truststore-reference?   ts:certificates-ref
     grouping local-or-truststore-host-keys-grouping
       +-- (local-or-truststore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- host-key*   ct:ssh-host-key
          +--:(truststore) {truststore-supported,ssh-host-keys}?
             +-- truststore-reference?   ts:host-keys-ref
     grouping local-or-truststore-psks-grouping
       +-- (local-or-truststore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- psk*   ct:psk



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          +--:(truststore) {truststore-supported,psks}?
             +-- truststore-reference?   ts:psks-ref
     grouping local-or-truststore-raw-pub-keys-grouping
       +-- (local-or-truststore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- raw-public-key*   ct:raw-public-key
          +--:(truststore) {truststore-supported,raw-public-keys}?
             +-- truststore-reference?   ts:raw-public-keys-ref
     grouping truststore-grouping
       +-- certificates* [name] {x509-certificates}?
       |  +-- name?          string
       |  +-- description?   string
       |  +-- certificate* [name]
       |     +-- name?                     string
       |     +-- cert                      trust-anchor-cert-cms
       |     +---n certificate-expiration
       |        +-- expiration-date    yang:date-and-time
       +-- host-keys* [name] {ssh-host-keys}?
       |  +-- name?          string
       |  +-- description?   string
       |  +-- host-key* [name]
       |     +-- name?       string
       |     +-- host-key    ct:ssh-host-key
       +-- psks* [name] {psks}?
       |  +-- name?          string
       |  +-- description?   string
       |  +-- psk* [name]
       |     +-- name?   string
       |     +-- psk     ct:psk
       +-- raw-public-keys* [name] {raw-public-keys}?
          +-- name?             string
          +-- description?      string
          +-- raw-public-key* [name]
             +-- name?             string
             +-- raw-public-key    ct:raw-public-key

2.2.  Example Usage

   The following example illustrates trust anchors in <operational> as
   described by Section 5.3 in [RFC8342].  This datastore view
   illustrates data set by the manufacturing process alongside
   conventional configuration.  This trust anchors instance has six sets
   of pinned certificates and one set of pinned host keys.

   <truststore
      xmlns="urn:ietf:params:xml:ns:yang:ietf-truststore"
      xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin">



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     <!-- Manufacturer's trusted root CA certs -->
     <certificates or:origin="or:system">
       <name>manufacturers-root-ca-certs</name>
       <description>
         Certificates built into the device for authenticating
         manufacturer-signed objects, such as TLS server certificates,
         vouchers, etc.  Note, though listed here, these are not
         configurable; any attempt to do so will be denied.
       </description>
       <certificate>
         <name>Manufacturer Root CA cert 1</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
       <certificate>
         <name>Manufacturer Root CA cert 2</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>

     <!-- specific end-entity certs for authenticating servers -->
     <certificates or:origin="or:intended">
       <name>explicitly-trusted-server-certs</name>
       <description>
         Specific server authentication certificates for explicitly
         trusted servers.  These are needed for server certificates
         that are not signed by a CA.
       </description>
       <certificate>
         <name>Fred Flintstone</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>

     <!-- trusted CA certs for authenticating servers -->
     <certificates or:origin="or:intended">
       <name>explicitly-trusted-server-ca-certs</name>
       <description>
         Trust anchors (i.e. CA certs) that are used to authenticate
         server connections.  Servers are authenticated if their
         certificate has a chain of trust to one of these CA
         certificates.
       </description>
       <certificate>
         <name>ca.example.com</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>




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     <!-- specific end-entity certs for authenticating clients -->
     <certificates or:origin="or:intended">
       <name>explicitly-trusted-client-certs</name>
       <description>
         Specific client authentication certificates for explicitly
         trusted clients.  These are needed for client certificates
         that are not signed by a CA.
       </description>
       <certificate>
         <name>George Jetson</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>

     <!-- trusted CA certs for authenticating clients -->
     <certificates or:origin="or:intended">
       <name>explicitly-trusted-client-ca-certs</name>
       <description>
         Trust anchors (i.e. CA certs) that are used to authenticate
         client connections.  Clients are authenticated if their
         certificate has a chain of trust to one of these CA
         certificates.
       </description>
       <certificate>
         <name>ca.example.com</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>

     <!-- trusted CA certs for random HTTPS servers on Internet -->
     <certificates or:origin="or:system">
       <name>common-ca-certs</name>
       <description>
         Trusted certificates to authenticate common HTTPS servers.
         These certificates are similar to those that might be
         shipped with a web browser.
       </description>
       <certificate>
         <name>ex-certificate-authority</name>
         <cert>base64encodedvalue==</cert>
       </certificate>
     </certificates>

     <!-- specific SSH host keys for authenticating clients -->
     <host-keys or:origin="or:intended">
       <name>explicitly-trusted-ssh-host-keys</name>
       <description>
         Trusted SSH host keys used to authenticate SSH servers.



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         These host keys would be analogous to those stored in
         a known_hosts file in OpenSSH.
       </description>
       <host-key>
         <name>corp-fw1</name>
         <host-key>base64encodedvalue==</host-key>
       </host-key>
     </host-keys>

   </truststore>

   The following example illustrates the "certificate-expiration"
   notification in use with the NETCONF protocol.

   ========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========

   <notification
     xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2018-05-25T00:01:00Z</eventTime>
     <truststore xmlns="urn:ietf:params:xml:ns:yang:ietf-truststore">
       <certificates>
         <name>explicitly-trusted-client-certs</name>
         <certificate>
           <name>George Jetson</name>
           <certificate-expiration>
             <expiration-date>2018-08-05T14:18:53-05:00</expiration-dat\
   e>
           </certificate-expiration>
         </certificate>
       </certificates>
     </truststore>
   </notification>


2.3.  YANG Module

   This YANG module imports modules from [RFC8341] and
   [I-D.ietf-netconf-crypto-types].

   <CODE BEGINS> file "ietf-truststore@2019-11-02.yang"


   <CODE ENDS>








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3.  Security Considerations

   The YANG module defined in this document is designed to be accessed
   via YANG based management protocols, such as NETCONF [RFC6241] and
   RESTCONF [RFC8040].  Both of these protocols have mandatory-to-
   implement secure transport layers (e.g., SSH, TLS) with mutual
   authentication.

   The NETCONF access control model (NACM) [RFC8341] provides the means
   to restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      /: The entire data tree defined by this module is sensitive to
         write operations.  For instance, the addition or removal of any
         trust anchor may dramatically alter the implemented security
         policy.  For this reason, the NACM extension "default-deny-
         write" has been set for the entire data tree.

   None of the readable data nodes in this YANG module are considered
   sensitive or vulnerable in network environments.

   This module does not define any RPCs, actions, or notifications, and
   thus the security consideration for such is not provided here.

4.  IANA Considerations

4.1.  The IETF XML Registry

   This document registers one URI in the "ns" subregistry of the IETF
   XML Registry [RFC3688].  Following the format in [RFC3688], the
   following registration is requested:

      URI: urn:ietf:params:xml:ns:yang:ietf-truststore
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.








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4.2.  The YANG Module Names Registry

   This document registers one YANG module in the YANG Module Names
   registry [RFC6020].  Following the format in [RFC6020], the the
   following registration is requested:

      name:         ietf-truststore
      namespace:    urn:ietf:params:xml:ns:yang:ietf-truststore
      prefix:       ta
      reference:    RFC XXXX


5.  References

5.1.  Normative References

   [I-D.ietf-netconf-crypto-types]
              Watsen, K. and H. Wang, "Common YANG Data Types for
              Cryptography", draft-ietf-netconf-crypto-types-11 (work in
              progress), October 2019.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

5.2.  Informative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.







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   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.





























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Appendix A.  Change Log

A.1.  00 to 01

   o  Added features "x509-certificates" and "ssh-host-keys".

   o  Added nacm:default-deny-write to "trust-anchors" container.

A.2.  01 to 02

   o  Switched "list pinned-certificate" to use the "trust-anchor-cert-
      grouping" from crypto-types.  Effectively the same definition as
      before.

A.3.  02 to 03

   o  Updated copyright date, boilerplate template, affiliation, folding
      algorithm, and reformatted the YANG module.

A.4.  03 to 04

   o  Added groupings 'local-or-truststore-certs-grouping' and 'local-
      or-truststore-host-keys-grouping', matching similar definitions in
      the keystore draft.  Note new (and incomplete) "truststore" usage!

   o  Related to above, also added features 'truststore-supported' and
      'local-trust-anchors-supported'.

A.5.  04 to 05

   o  Renamed "trust-anchors" to "truststore"

   o  Removed "pinned." prefix everywhere, to match truststore rename

   o  Moved everything under a top-level 'grouping' to enable use in
      other contexts.

   o  Renamed feature from 'local-trust-anchors-supported' to 'local-
      definitions-supported' (same name used in keystore)

   o  Removed the "require-instance false" statement from the "*-ref"
      typedefs.

   o  Added missing "ssh-host-keys" and "x509-certificates" if-feature
      statements






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A.6.  05 to 06

   o  Editorial changes only.

A.7.  06 to 07

   o  Added Henk Birkholz as a co-author (thanks Henk!)

   o  Added PSKs and raw public keys to Truststore.

Acknowledgements

   The authors would like to thank for following for lively discussions
   on list and in the halls (ordered by last name): Martin Bjorklund,
   Nick Hancock, Balazs Kovacs, Eric Voit, and Liang Xia.

Authors' Addresses

   Kent Watsen
   Watsen Networks

   EMail: kent+ietf@watsen.net


   Henk Birkholz
   Fraunhofer SIT

   EMail: henk.birkholz@sit.fraunhofer.de























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