Internet DRAFT - draft-deng-teep-cvmp

draft-deng-teep-cvmp







Internet Engineering Task Force                                  J. Deng
Internet-Draft                                                          
Intended status: Informational                                     G. Yu
Expires: 3 June 2024                                     1 December 2023


     Confidential Virtual Machine Provisioning in Cloud Environment
                        draft-deng-teep-cvmp-01

Abstract

   This document specifies the procedures of provisioning confidential
   virtual machine in the cloud environment.

Status of This Memo

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   This Internet-Draft will expire on 3 June 2024.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Procedures of CVM Provisioning in Cloud Environment . . . . .   3
     3.1.  Feature Acquirement . . . . . . . . . . . . . . . . . . .   4
     3.2.  CVM Creation  . . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Key Provisioning  . . . . . . . . . . . . . . . . . . . .   5
       3.3.1.  Policy Setup  . . . . . . . . . . . . . . . . . . . .   5
       3.3.2.  Key Allocation  . . . . . . . . . . . . . . . . . . .   6
       3.3.3.  Key Acquirement . . . . . . . . . . . . . . . . . . .   6
       3.3.4.  Key Update  . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  CVM Management  . . . . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
     5.1.  Communication Security Between Key Agent and Key
           Server  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Communication Security Between Cloud Tenant and Key
           Server  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   8
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Confidential computing protects workload and data in use leveraging
   hardware-based security technology.  Confidential virtual machine
   (CVM) in the cloud environment is one use case of confidential
   computing.  There is an increasing adoption of CVMs in the cloud.
   CVM allows a cloud tenant to protect the sensitive workload and data,
   and manage the cryptography keys independently from the cloud service
   providers.

   When adopting CVMs in the cloud, the CVM features, CVM provisioning
   and management of cryptography keys, etc. depend on different
   hardware.  Common CVM provisioning procedures and requirements are
   needed.  This document specifies the procedures of provisioning CVMs
   in the cloud environment and the requirements.

2.  Terms

   The following terms are used in this document.

   *  CVM Platform: CVM Platform is provided and maintained by cloud
      service provider.  It provides interfaces for cloud tenant to
      create and manage CVM instances on the cloud.  It receives the CVM



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      related requests from cloud tenant and interacts with cloud
      resource manager to perform CVM creation, decommission, update,
      migration etc. on the cloud infrastructure.

   *  Key Agent: Key Agent is the component within a CVM instance that
      interacts with Key Server to allocate, acquire and update security
      keys, and also provides and update Security Version Number (SVN)
      of the CVM.

   *  Security Version Number (SVN): SVN represents the security
      features of the hardware of CVM.

   *  Key Server: Key Server authenticates Key Agent, responds to Key
      Agent's requests to generate, update and return security keys, and
      update CVM's SVN.

   *  Security Key(SK): SK is allocated by Key Server under the request
      of Key Agent.  SK is used by CVM instance to encrypt sensitive
      data.

   *  KeyID: KeyID identifies a security key.

3.  Procedures of CVM Provisioning in Cloud Environment

   The procedures of CVM provisioning in Cloud Environment includes the
   following:

   *  Feature Acquirement: Cloud Tenant acquires the CVM related
      features that are provided by CVM Platform.

   *  CVM Creation: Cloud tenant requests CVM instance(s) with selected
      features and CVM platform creates the requested CVM instance(s),
      and returns the results to the cloud tenant.

   *  Key Provisioning: the Key Agent in CVM instance obtains and
      updates security keys bounded to the CVM through communication
      with the Key Server.

   *  CVM management: Cloud tenant performs various management tasks on
      CVM instances, such as CVM updates, live migration, CVM
      decommission etc., through interacting with CVM Platform










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3.1.  Feature Acquirement

   Before creating a CVM instance, Cloud Tenant acquires the supported
   CVM features from CVM platform.  Figure 1 shows example feature
   acquirement between Cloud Tenant and CVM Platform.  CVMFeatureRequest
   message is sent by Cloud Tenant to CVM Platform requesting the
   supported CVM features.  CVM returns CVMFeatureResponse carrying a
   list of supported features, which may include:

   *  SecureBoot: whether secure boot is supported.

   *  LiveMigration: whether live migration is supported.

   *  AuxilaryFirmware: whether allows Cloud Tenant to specify firmware
      to be used.

   *  BIOS: whether allows Cloud Tenant to customize BIOS.

   *  SVN: whether allows Cloud Tenant to specifies SVN.

   +--------+                     +----------+
   | Cloud  |                     |   CVM    |
   | Tenant |                     | Platform |
   +--------+                     +----------+
           |                              |
           |                              |
           |      CVMFeatureRequest       |
           |----------------------------->|
           |                              |
           |                              |
           |      CVMFeatureResponse      |
           |<-----------------------------|
           |                              |

                     Figure 1: CVM feature acquirement

3.2.  CVM Creation

   Figure 2 shows that Cloud Tenant requests to create CVM instance(s)
   and CVM Platform responds with the creation result.  In the
   CVMCreateRequest message requesting CVM creation, Client tenant
   provides the requested features.  The features are described as in
   Section 3.1.  CVM Platform returns with CVMCreateResponse.  If the
   creation is successful, in CVMCreateResponse message, CVM Platform
   indicated successful CVM creation and returns information on the
   features requested by Cloud Tenant.





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   +--------+                 +----------+
   | Cloud  |                 |   CVM    |
   | Tenant |                 | Platform |
   +--------+                 +----------+
           |                           |
           |    CVMCreateRequest       |
           |-------------------------->|
           |                           |
           |  CVMCreateResponse        |
           |<--------------------------|
           |                           |

                      Figure 2: CVM instance creation

3.3.  Key Provisioning

   The key provisioning consists of Policy Setup, Key Allocation, Key
   Acquirement, and Key Update between Key Agent and Key Server.

   *  Policy Setup: Cloud Tenant provide Key Server with Keying Policy.

   *  Key Allocation: Key Agent requests Key Server to allocate a new
      security key.

   *  Key Acquirement: Key Agent obtains a pre-allocated security key by
      providing the KeyID to Key Server.

   *  Key Update: Key Agent updates its SVN with Key Server.

   The security considerations for the communication between Key Agent
   and Key Server are presented in Section 5.

3.3.1.  Policy Setup

   In Policy Setup, Cloud Tenant provides Key server with information
   needed for Key Allocation, Key Acquirement, and Key Update.  The
   information at least includes SVN, measurements, etc.  Figure 3 shows
   example Keying Policy setup between Key Agent and Key Server.













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           +--------+                        +--------+
           | Cloud  |                        |  Key   |
           | Tenant |                        | Server |
           +--------+                        +--------+
                   |                                 |
                   |  SetKeyPolicy                   |
                   |-------------------------------->|
                   |                                 |
                   |                 PolicyResponse  |
                   |<--------------------------------|
                   |                                 |

                         Figure 3: Key provisioning

3.3.2.  Key Allocation

   Figure 4 shows example key allocation.  Key Agent sends
   KeyAllocRequest message to Key Server to request a new security key.
   Key Server then allocates a KeyID, generates and saves a root key for
   Key Agent, derives a security key from the root key with input
   parameters including the SVN provided by Key Agent, and returns the
   KeyID and Security Key. Allocation usually occurs when CVM is started
   for the first time, and CVM needs to use Security Key for encryption.

           +--------+                        +--------+
           | Key    |                        |  Key   |
           | Agent  |                        | Server |
           +--------+                        +--------+
                   |                                 |
                   |  KeyAllocRequest                |
                   |-------------------------------->|
                   |                KeyAllocResponse |
                   |<--------------------------------|

                         Figure 4: Key provisioning

3.3.3.  Key Acquirement

   Figure 5 shows example key acquirement where Key Agent acquires a
   pre-allocated Security Key with the KeyID.











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           +--------+                        +--------+
           | Key    |                        |  Key   |
           | Agent  |                        | Server |
           +--------+                        +--------+
                   |                                 |
                   |  KeyAcquireRequest              |
                   |-------------------------------->|
                   |              KeyAcquireResponse |
                   |<--------------------------------|

                         Figure 5: Key provisioning

3.3.4.  Key Update

   Key Agent within a CVM may chose to update the minimal required SVN
   of the Key by sending KeyUpdateRequest to Key Server.  Key Server
   will only update the SVN if the old SVN with the Key Agent is lower
   than the target SVN.  After successful SVN update, a Key Agent with
   outdated SVN cannot acquire the Security Key with the pre-allocated
   KeyID.  A CVM which meets the requirement of minimum SVN can request
   the Key Server to re-allocate a new Security Key from the
   corresponding root key.  Figure 6 shows example key update.

           +--------+                        +--------+
           | Key    |                        |  Key   |
           | Agent  |                        | Server |
           +--------+                        +--------+
                   |                                 |
                   |  KeyUpdateRequest               |
                   |-------------------------------->|
                   |              KeyUpdateResponse  |
                   |<--------------------------------|

                            Figure 6: Key Update

3.4.  CVM Management

   This section presents the procedures for CVM management.

4.  IANA Considerations

   This memo includes no request to IANA.

5.  Security Considerations







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5.1.  Communication Security Between Key Agent and Key Server

   Key Agent and Key server are mutually authenticated and the
   communications between them are confidentially and integrity
   protected.  The security can leverage the attestation evidence in
   [RFC9334].  The messages can use CBOR and the security wrapper as in
   [RFC9052].

5.2.  Communication Security Between Cloud Tenant and Key Server

   This section considers the communication security between Cloud
   Tenant and Key Server.

6.  References

6.1.  Normative References

   [RFC9334]  Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote ATtestation procedureS (RATS)
              Architecture", RFC 9334, DOI 10.17487/RFC9334, January
              2023, <https://www.rfc-editor.org/info/rfc9334>.

   [RFC9052]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/info/rfc9052>.

Acknowledgements


Contributors


Authors' Addresses

   Juan Deng
   Email: dengjuan.deng@alibaba-inc.com


   Guorui Yu
   Email: ruogui.ygr@alibaba-inc.com










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