NETCONF Working Group K. Watsen Internet-Draft Juniper Networks Intended status: Standards Track June 4, 2018 Expires: December 6, 2018 YANG Data Model for Global Trust Anchors draft-ietf-netconf-trust-anchors-00 Abstract This document defines a YANG 1.1 data model for configuring global sets of X.509 certificates and SSH host-keys that can be referenced by other data models for trust. While the SSH host-keys are uniquely for the SSH protocol, the X.509 certificates 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 "2018-06-04" --> the publication date of this draft The following Appendix section is to be removed prior to publication: o Appendix A. Change Log 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 Watsen Expires December 6, 2018 [Page 1] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 December 6, 2018. Copyright Notice Copyright (c) 2018 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 . . . . . . . . . . . . . . . . . . . . . . 4 2.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 7 3. Security Considerations . . . . . . . . . . . . . . . . . . . 12 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 4.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 12 4.2. The YANG Module Names Registry . . . . . . . . . . . . . 13 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.1. Normative References . . . . . . . . . . . . . . . . . . 13 5.2. Informative References . . . . . . . . . . . . . . . . . 13 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 15 A.1. I-D to 00 . . . . . . . . . . . . . . . . . . . . . . . . 15 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15 Watsen Expires December 6, 2018 [Page 2] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 1. Introduction This document defines a YANG 1.1 [RFC7950] data model for configuring global sets of X.509 certificates and SSH host-keys that can be referenced by other data models for trust. While the SSH host-keys are uniquely for the SSH protocol, the X.509 certificates may be used for 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 may appear only in . 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-trust- anchors" module. Watsen Expires December 6, 2018 [Page 3] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 module: ietf-trust-anchors +--rw trust-anchors +--rw pinned-certificates* [name] | +--rw name string | +--rw description? string | +--rw pinned-certificate* [name] | +--rw name string | +--rw cert ct:trust-anchor-cert-cms | +---n certificate-expiration | +-- expiration-date? yang:date-and-time +--rw pinned-host-keys* [name] +--rw name string +--rw description? string +--rw pinned-host-key* [name] +--rw name string +--rw host-key ct:ssh-host-key 2.2. Example Usage The following example illustrates trust anchors in 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 five sets of pinned certificates and one set of pinned host keys. manufacturers-root-ca-certs 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. Manufacturer Root CA cert 1 base64encodedvalue== Manufacturer Root CA cert 2 base64encodedvalue== Watsen Expires December 6, 2018 [Page 4] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 explicitly-trusted-server-certs Specific server authentication certificates for explicitly trusted servers. These are needed for server certificates that are not signed by a pinned CA. Fred Flintstone base64encodedvalue== explicitly-trusted-server-ca-certs 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. ca.example.com base64encodedvalue== explicitly-trusted-client-certs Specific client authentication certificates for explicitly trusted clients. These are needed for client certificates that are not signed by a pinned CA. George Jetson base64encodedvalue== explicitly-trusted-client-ca-certs Trust anchors (i.e. CA certs) that are used to authenticate Watsen Expires December 6, 2018 [Page 5] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 client connections. Clients are authenticated if their certificate has a chain of trust to one of these CA certificates. ca.example.com base64encodedvalue== common-ca-certs Trusted certificates to authenticate common HTTPS servers. These certificates are similar to those that might be shipped with a web browser. ex-certificate-authority base64encodedvalue== explicitly-trusted-ssh-host-keys Trusted SSH host keys used to authenticate SSH servers. These host keys would be analogous to those stored in a known_hosts file in OpenSSH. corp-fw1 base64encodedvalue== The following example illustrates the "certificate-expiration" notification in use with the NETCONF protocol. Watsen Expires December 6, 2018 [Page 6] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 [Note: '\' line wrapping for formatting only] 2018-05-25T00:01:00Z explicitly-trusted-client-certs George Jetson 2018-08-05T14:18:53-05:00 2.3. YANG Module This YANG module imports modules from [RFC6536], [RFC6991] and [I-D.ietf-netconf-crypto-types]. file "ietf-trust-anchors@2018-06-04.yang" module ietf-trust-anchors { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-trust-anchors"; prefix "ta"; import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } import ietf-crypto-types { prefix ct; reference "RFC YYYY: Common YANG Data Types for Cryptography"; } organization "IETF NETCONF (Network Configuration) Working Group"; Watsen Expires December 6, 2018 [Page 7] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 contact "WG Web: WG List: Author: Kent Watsen "; description "This module defines a data model for configuring global trust anchors used by other data models. The data model enables the configuration of sets of trust anchors. This data model supports configuring trust anchors for both X.509 certificates and SSH host keys. Copyright (c) 2018 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision "2018-06-04" { description "Initial version"; reference "RFC XXXX: YANG Data Model for Global Trust Anchors"; } /************************************************************/ /* Typedefs for leafrefs to commonly referenced objects */ /************************************************************/ typedef pinned-certificates-ref { type leafref { path "/ta:trust-anchors/ta:pinned-certificates/ta:name"; require-instance false; } description "This typedef enables importing modules to easily define a leafref to a 'pinned-certificates' object. The require Watsen Expires December 6, 2018 [Page 8] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 instance attribute is false to enable the referencing of pinned certificates that exist only in ."; reference "RFC 8342: Network Management Datastore Architecture (NMDA)"; } typedef pinned-host-keys-ref { type leafref { path "/ta:trust-anchors/ta:pinned-host-keys/ta:name"; require-instance false; } description "This typedef enables importing modules to easily define a leafref to a 'pinned-host-keys' object. The require instance attribute is false to enable the referencing of pinned host keys that exist only in ."; reference "RFC 8342: Network Management Datastore Architecture (NMDA)"; } /*********************************/ /* Protocol accessible nodes */ /*********************************/ container trust-anchors { description "Contains sets of X.509 certificates and SSH host keys."; list pinned-certificates { key name; description "A list of pinned certificates. These certificates can be used by a server to authenticate clients, or by a client to authenticate servers. Each list of pinned certificates SHOULD be specific to a purpose, as the list as a whole may be referenced by other modules. For instance, a NETCONF server's configuration might use a specific list of pinned certificates for when authenticating NETCONF client connections."; leaf name { type string; description "An arbitrary name for this list of pinned certificates."; } leaf description { type string; Watsen Expires December 6, 2018 [Page 9] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 description "An arbitrary description for this list of pinned certificates."; } list pinned-certificate { key name; description "A pinned certificate."; leaf name { type string; description "An arbitrary name for this pinned certificate. The name must be unique across all lists of pinned certificates (not just this list) so that leafrefs from another module can resolve to unique values."; } leaf cert { type ct:trust-anchor-cert-cms; mandatory true; description "The binary certificate data for this pinned certificate."; reference "RFC YYYY: Common YANG Data Types for Cryptography"; } notification certificate-expiration { description "A notification indicating that the configured trust anchor is either about to expire or has already expired. When to send notifications is an implementation specific decision, but it is RECOMMENDED that a notification be sent once a month for 3 months, then once a week for four weeks, and then once a day thereafter until the issue is resolved."; leaf expiration-date { type yang:date-and-time; //mandatory true; description "Identifies the expiration date on the certificate."; } } } } list pinned-host-keys { key name; description "A list of pinned host keys. These pinned host-keys can Watsen Expires December 6, 2018 [Page 10] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 be used by clients to authenticate SSH servers. Each list of pinned host keys SHOULD be specific to a purpose, so the list as a whole may be referenced by other modules. For instance, a NETCONF client's configuration might point to a specific list of pinned host keys for when authenticating specific SSH servers."; leaf name { type string; description "An arbitrary name for this list of pinned SSH host keys."; } leaf description { type string; description "An arbitrary description for this list of pinned SSH host keys."; } list pinned-host-key { key name; description "A pinned host key."; leaf name { type string; description "An arbitrary name for this pinned host-key. Must be unique across all lists of pinned host-keys (not just this list) so that a leafref to it from another module can resolve to unique values."; } leaf host-key { type ct:ssh-host-key; mandatory true; description "The binary public key data for this pinned host key."; reference "RFC YYYY: Common YANG Data Types for Cryptography"; } } } } } Watsen Expires December 6, 2018 [Page 11] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 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) [RFC6536] 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. However, no NACM annotations are applied as the data SHOULD be editable by users other than a designated 'recovery session'. 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-trust-anchors Registrant Contact: The NETCONF WG of the IETF. XML: N/A, the requested URI is an XML namespace. Watsen Expires December 6, 2018 [Page 12] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 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-trust-anchors namespace: urn:ietf:params:xml:ns:yang:ietf-trust-anchors prefix: ta reference: RFC XXXX 5. References 5.1. Normative References [I-D.ietf-netconf-crypto-types] Watsen, K., "Common YANG Data Types for Cryptography", draft-ietf-netconf-crypto-types-00 (work in progress), June 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . Watsen Expires December 6, 2018 [Page 13] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [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, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [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, . Watsen Expires December 6, 2018 [Page 14] Internet-Draft YANG Data Model for Global Trust Anchors June 2018 Appendix A. Change Log A.1. I-D to 00 o Now imports and uses the crypto-types module. o FIXME o FIXME o FIXME: added notification example... Acknowledgements The authors would like to thank for following for lively discussions on list and in the halls (ordered by last name): Martin Bjorklund, Balazs Kovacs, Eric Voit, and Liang Xia. Author's Address Kent Watsen Juniper Networks EMail: kwatsen@juniper.net Watsen Expires December 6, 2018 [Page 15]