Internet DRAFT - draft-friel-anima-brski-cloud

draft-friel-anima-brski-cloud







Network Working Group                                           O. Friel
Internet-Draft                                                     Cisco
Intended status: Standards Track                          R. Shekh-Yusef
Expires: 3 November 2020                                           Avaya
                                                           M. Richardson
                                                Sandelman Software Works
                                                              2 May 2020


                         BRSKI Cloud Registrar
                    draft-friel-anima-brski-cloud-02

Abstract

   This document specifies the behaviour of a BRSKI Cloud Registrar, and
   how a pledge can interact with a BRSKI Cloud Registrar when
   bootstrapping.

Status of This Memo

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   This Internet-Draft will expire on 3 November 2020.

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   provided without warranty as described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Target use cases  . . . . . . . . . . . . . . . . . . . .   3
   2.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Interested Parties  . . . . . . . . . . . . . . . . . . .   4
     2.2.  Network Connectivity  . . . . . . . . . . . . . . . . . .   5
   3.  Initial Voucher Request . . . . . . . . . . . . . . . . . . .   5
     3.1.  Cloud Registrar Discovery . . . . . . . . . . . . . . . .   5
     3.2.  Pledge - Cloud Registrar TLS Establishment Details  . . .   5
     3.3.  Pledge Requests Voucher from the Cloud Registrar  . . . .   5
   4.  Cloud Registrar Voucher Request Operation . . . . . . . . . .   6
     4.1.  Pledge Ownership Lookup . . . . . . . . . . . . . . . . .   6
   5.  Voucher Request Redirected to Local Domain Registrar  . . . .   6
     5.1.  Pledge handling of Redirect . . . . . . . . . . . . . . .   7
   6.  Voucher Request Handled by Cloud Registrar  . . . . . . . . .   7
   7.  Protocol Details  . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Voucher Request Redirected to Local Domain Registrar  . .   7
     7.2.  Voucher Request Handled by Cloud Registrar  . . . . . . .   8
   8.  Pledge Certificate Identity Considerations  . . . . . . . . .   9
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  10
   11. Informative References  . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Bootstrapping Remote Secure Key Infrastructures (BRSKI)
   [I-D.ietf-anima-bootstrapping-keyinfra] specifies automated
   bootstrapping of an Autonomic Control Plane.  BRSKI Section 2.7
   describes how a pledge "MAY contact a well known URI of a cloud
   registrar if a local registrar cannot be discovered or if the
   pledge's target use cases do not include a local registrar".

   This document further specifies use of a BRSKI cloud registrar and
   clarifies operations that are not sufficiently specified in BRSKI.

   Two high level deployment models are documented here:

   *  Local Domain Registrar Discovery: the cloud registrar is used by
      the pledge to discover the local domain registrar.  The cloud
      registrar redirects the pledge to the local domain registrar, and
      the pledge completes bootstrap against the local domain registrar.

   *  Cloud Registrar Based Boostrap: there is no local domain registrar
      and the pledge completes boostrap using the cloud registrar.  As
      part of boostrap, the cloud registrar may need to tell the client
      the domain to use for accessing services.



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   These deployment models facilitate multiple use cases including:

   *  A pledge is bootstrapping in a remote location and needs to
      contact a cloud registrar in order to discover the address of its
      local domain.

   *  A pledge can connect to a manufacturer hosted cloud service or the
      same software running on-premise.  The systems might not be
      discoverable locally.

   *  A pledge needs to connect to a third-party hosted registrar
      service, because there is no local registrar service available.

   *  A pledge needs to discover the deployment model in use by the
      pledge operator, which might include going into some local
      configuration mode.

1.1.  Target use cases

   An end user unboxes a device, and connects it to a local network
   (using a cable).  The device should join a (owner domain) Registrar
   operated by the end user's organization, which is not physically
   present on the local network.

   The end user is at their home office, while the device belongs to
   their work.  Or the end user is at a small satellite office which
   lacks correctly trained IT personnel.

   The end user's organization operates an (owner domain) Registrar at
   their head-quarters, or in a hosted data center.  A registrar may
   also be operated on behalf of the owner through an outsourced IT
   arrangement.

2.  Architecture

   The high level architecture is illustrated in Figure 1.

   The pledge connects to the cloud registrar during bootstrap.

   The cloud registrar may redirect the pledge to a local/owner
   registrar in order to complete bootstrap against the local registrar.

   If the cloud registrar handles the bootstrap process itself without
   redirecting the pledge to a local registrar, the cloud registrar may
   need to inform the pledge what domain to use for accessing services
   once bootstrap is complete.





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   Finally, when bootstrapping against a local/owner registrar, this
   registrar may interact with a backend CA to assist in issuing
   certificates to the pledge.  The mechanisms and protocols by which
   the registrar interacts with the CA are transparent to the pledge and
   are out-of-scope of this document.

   The architecture illustrates shows the cloud registrar and MASA as
   being logically separate entities.  The two functions could of course
   be integrated into a single service.

   XXX NONCE-less voucher.  If the Cloud Registrar issues a voucher
   directly, while it may include a nonce, because that nonce does not
   go through the Owner, which means that the MASA has no audit trail
   that the pledge really connected to the Owner Registrar.

   TWO CHOICES: 1.  Cloud Registrar redirects to Owner Registrar 2.
   Cloud Registrar returns VOUCHER pinning Owner Register.

   |<--------------OWNER------------------------>|     MANUFACTURER

    On-site                Cloud
   +--------+                                         +-----------+
   | Pledge |---------------------------------------->| Cloud     |
   +--------+                                         | Registrar |
       |                                              +---+  +----+
       |                                                  |??|
       |                 +-----------+                +---+  +----+
       +---------------->|  Owner    |--------------->|   MASA    |
       |   VR-sign(N)    | Registrar |sign(VR-sign(N))+-----------+
       |                 +-----------+
       |                       |    +-----------+
       |                       +--->|    CA     |
       |                            +-----------+
       |
       |                 +-----------+
       +---------------->| Services  |
                         +-----------+

                     Figure 1: High Level Architecture

2.1.  Interested Parties

   1.  OEM - Equipment manufacturer.  Operate the MASA.

   2.  Network operator.  Operate the Local Registrar.  Often operated
       by end owner (company), or by outsourced IT entity.

   3.  Network integrator.  They operate ?Cloud Registrar?.



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2.2.  Network Connectivity

   The assumption is that the pledge already has network connectivity
   prior to connecting to the cloud registrar.  The pledge must have an
   IP address, must be able to make DNBS queries, and must be able to
   send HTTP requests to the cloud registrar.  The pledge operator has
   already connected the pledge to the network, and the mechanism by
   which this has happened is out of scope of this document.

3.  Initial Voucher Request

3.1.  Cloud Registrar Discovery

   BRSKI defines how a pledge MAY contact a well known URI of a cloud
   registrar if a local registrar cannot be discovered.  Additionally,
   certain pledge types may never attempt to discover a local registrar
   and may automatically bootstrap against a cloud registrar.  The
   details of the URI are manufacturer specific, with BRSKI giving the
   example "brski-registrar.manufacturer.example.com".

3.2.  Pledge - Cloud Registrar TLS Establishment Details

   The pledge MUST use an Implicit Trust Anchor database (see [RFC7030])
   to authenticate the cloud registrar service as described in
   [RFC6125].  The pledge MUST NOT establish a provisional TLS
   connection (see BRSKI section 5.1) with the cloud registrar.

   The cloud registrar MUST validate the identity of the pledge by
   sending a TLS CertificateRequest message to the pledge during TLS
   session establishment.  The cloud registrar MAY include a
   certificate_authorities field in the message to specify the set of
   allowed IDevID issuing CAs that pledges may use when establishing
   connections with the cloud registrar.

   The cloud registrar MAY only allow connections from pledges that have
   an IDevID that is signed by one of a specific set of CAs, e.g.
   IDevIDs issued by certain manufacturers.

   The cloud registrar MAY allow pledges to connect using self-signed
   identity certificates or using Raw Public Key [RFC7250] certificates.

3.3.  Pledge Requests Voucher from the Cloud Registrar

   After the pledge has established a full TLS connection with the cloud
   registrar and has verified the cloud registrar PKI identity, the
   pledge generates a voucher request message as outlined in BRSKI
   section 5.2, and sends the voucher request message to the cloud
   registrar.



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4.  Cloud Registrar Voucher Request Operation

   When the cloud registrar has verified the identity of the pledge,
   determined the pledge ownership and has received the voucher request,
   there are two main options for handling the request.

   *  the cloud registrar can redirect the voucher request to a local
      domain registrar

   *  the cloud registrar can handle the voucher request directly by
      either issuing a voucher or declining the request

4.1.  Pledge Ownership Lookup

   The cloud registrar needs some suitable mechanism for knowing the
   correct owner of a connecting pledge based on the presented identity
   certificate.  For example, if the pledge establishes TLS using an
   IDevID that is signed by a known manufacturing CA, the registrar
   could extract the serial number from the IDevID and use this to
   lookup a database of pledge IDevID serial numbers to owners.

   Alternatively, if the cloud registrar allows pledges to connect using
   self-signed certificates, the registrar could use the thumbprint of
   the self-signed certificate to lookup a database of pledge self-
   signed certificate thumbprints to owners.

   The mechanism by which the cloud registrar determines pledge
   ownership is out-of-scope of this document.

5.  Voucher Request Redirected to Local Domain Registrar

   Once the cloud registar has determined pledge ownership, the cloud
   registrar may redirect the pledge to the owner's local domain
   registrar in order to complete bootstrap.  Ownership registration
   will require the owner to register their local domain.  The mechanism
   by which pledge owners register their domain with the cloud registrar
   is out-of-scope of this document.

   The cloud registrar replies to the voucher request with a suitable
   HTTP 3xx response code as per [I-D.ietf-httpbis-bcp56bis], including
   the owner's local domain in the HTTP Location header.










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5.1.  Pledge handling of Redirect

   The pledge should complete BRSKI bootstrap as per standard BRSKI
   operation after following the HTTP redirect.  The pledge should
   establish a provisional TLS connection with specified local domain
   registrar.  The pledge should not use its Implicit Trust Anchor
   database for validating the local domain registrar identity.  The
   pledge should send a voucher request message via the local domain
   registrar.  When the pledge downloads a voucher, it can validate the
   TLS connection to the local domain registrar and continue with
   enrollment and bootstrap as per standard BRSKI operation.

6.  Voucher Request Handled by Cloud Registrar

   If the cloud registrar issues a voucher, it returns the voucher in a
   HTTP response with a suitable 2xx response code as per
   [I-D.ietf-httpbis-bcp56bis].

   Alternatively, it may redirect to the customers' Registration
   Authority (RA) with a 307 Temporary Redirect to locate the RA.  The
   client MUST POST its voucher request to the new location.

7.  Protocol Details

   [[ TODO ]] Missing detailed BRSKI steps e.g.  CSR attributes,
   logging, etc.

7.1.  Voucher Request Redirected to Local Domain Registrar

   This is FLOW ONE.  EXPLAIN APPLICABILITY.





















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   +--------+            +-----------+              +----------+
   | Pledge |            | Local     |              | Cloud RA |
   |        |            | Registrar |              |          |
   +--------+            +-----------+              +----------+
       |                                                 |
       | 1. Mutual-authenticated TLS                     |
       |<----------------------------------------------->|
       |                                                 |
       | 2. Voucher Request                              |
       |------------------------------------------------>|
       |                                                 |
       | 3. 307 Location: localra.example.com            |
       |<------------------------------------------------|
       |
       | 4. Provisional TLS   |                     +---------+
       |<-------------------->|                     |  MASA   |
       |                      |                     +---------+
       | 5. Voucher Request   |                          |
       |--------------------->| 6. Voucher Request       |
       |                      |------------------------->|
       |                      |                          |
       |                      | 7. Voucher Response      |
       |                      |<-------------------------|
       | 8. Voucher Response  |                          |
       |<---------------------|                          |
       |                      |                          |
       | 9. Validate TLS      |                          |
       |<-------------------->|                          |
       |                      |                          |
       | 10. etc.             |                          |
       |--------------------->|                          |

7.2.  Voucher Request Handled by Cloud Registrar

   The Voucher includes the EST domain to use for EST enroll.  It is
   assumed services are accessed at that domain too.  As trust is
   already established via the Voucher, the pledge does a full TLS
   handshake against the local RA indicated by the voucher response.

   EXPLAIN APPLICABILITY.  NEEDS EXTENSTION to Voucher.











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   +--------+                                       +----------+
   | Pledge |                                       | Cloud RA |
   |        |                                       | / MASA   |
   +--------+                                       +----------+
       |                                                 |
       | 1. Full TLS                                     |
       |<----------------------------------------------->|
       |                                                 |
       | 2. Voucher Request                              |
       |------------------------------------------------>|
       |                                                 |
       | 3. Voucher Response  {localra:fqdn}             |
       |<------------------------------------------------|
       |                                                 |
       |                 +----------+                    |
       |                 | RFC7030  |                    |
       |                 |  EST     |                    |
       |                 | Registrar|                    |
       |                 +----------+                    |
       |                      |                          |
       | 4. Full TLS          |                          |
       |<-------------------->|                          |
       |                                                 |
       |     3a. /voucher_status POST  success           |
       |------------------------------------------------>|
       |     ON FAILURE 3b. /voucher_status POST         |
       |                                                 |
       | 5. EST Enrol         |                          |
       |--------------------->|                          |
       |                      |                          |
       | 6. Certificate       |                          |
       |<---------------------|                          |
       |                      |                          |
       | 7. /enrollstatus     |                          |
       |--------------------->|                          |

8.  Pledge Certificate Identity Considerations

   BRSKI section 5.9.2 specifies that the pledge MUST send a CSR
   Attributes request to the registrar.  The registrar MAY use this
   mechanism to instruct the pledge about the identities it should
   include in the CSR request it sends as part of enrollment.  The
   registrar may use this mechanism to tell the pledge what Subject or
   Subject Alternative Name identity information to include in its CSR
   request.  This can be useful if the Subject must have a specific
   value in order to complete enrollment with the CA.





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   For example, the pledge may only be aware of its IDevID Subject which
   includes a manufacturer serial number, but must include a specific
   fully qualified domain name in the CSR in order to complete domain
   ownership proofs required by the CA.  As another example, the
   registrar may deem the manufacturer serial number in an IDevID as
   personally identifiable information, and may want to specify a new
   random opaque identifier that the pledge should use in its CSR.

9.  IANA Considerations

   [[ TODO ]]

10.  Security Considerations

   [[ TODO ]]

11.  Informative References

   [IEEE802.1AR]
              IEEE, ., "Secure Device Identity", 2017.

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
              and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", Work in Progress, Internet-
              Draft, draft-ietf-anima-bootstrapping-keyinfra-41, 8 April
              2020, <http://www.ietf.org/internet-drafts/draft-ietf-
              anima-bootstrapping-keyinfra-41.txt>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://www.rfc-editor.org/info/rfc7030>.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
              2011, <https://www.rfc-editor.org/info/rfc6125>.

   [RFC7250]  Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
              Weiler, S., and T. Kivinen, "Using Raw Public Keys in
              Transport Layer Security (TLS) and Datagram Transport
              Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
              June 2014, <https://www.rfc-editor.org/info/rfc7250>.





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   [I-D.ietf-httpbis-bcp56bis]
              Nottingham, M., "Building Protocols with HTTP", Work in
              Progress, Internet-Draft, draft-ietf-httpbis-bcp56bis-09,
              1 November 2019, <http://www.ietf.org/internet-drafts/
              draft-ietf-httpbis-bcp56bis-09.txt>.

Authors' Addresses

   Owen Friel
   Cisco

   Email: ofriel@cisco.com


   Rifaat Shekh-Yusef
   Avaya

   Email: rifaat.ietf@gmail.com


   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca



























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