YANG Module for Basic Challenge-Response-based Remote Attestation Procedures
draft-birkholz-yang-basic-remote-attestation-00

TBD                                                          H. Birkholz
Internet-Draft                                            Fraunhofer SIT
Intended status: Standards Track                                M. Eckel
Expires: January 4, 2019                                          Huawei
                                                             S. Bhandari
                                                               B. Sulzen
                                                                 E. Voit
                                                                   Cisco
                                                             G. Fedorkow
                                                                 Juniper
                                                           July 03, 2018

   YANG Module for Basic Challenge-Response-based Remote Attestation
                               Procedures
            draft-birkholz-yang-basic-remote-attestation-00

Abstract

   This document defines YANG RPC and a minimal datastore required to
   retrieve integrity evidence about software from the device running
   the YANG datastore.  The module presented requires a TPM 2.0 and
   corresponding Trusted Software Stack included in the system entity
   the YANG datastore is running on.

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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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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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 January 4, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   2
   2.  The YANG Module for Basic Remote Attestation Procedures . . .   2
     2.1.  Tree format . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  Raw Format  . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   5.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .  17
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  17
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   This document is based on the terminology defined in
   [I-D.birkholz-attestation-terminology] and uses the interaction model
   and information elements defined in Reference Interaction Model for
   Challenge/Response-based Remote Attestation Procedures.

1.1.  Requirements notation

   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 RFC
   2119, BCP 14 [RFC2119].

2.  The YANG Module for Basic Remote Attestation Procedures

2.1.  Tree format

<CODE BEGINS>
module: basic-remote-attestation
  +--rw rats-support-structures
     +--rw supported-algos*           uint16
     +--rw endorsement-certificate    binary

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  rpcs:
    +---x tpm2-challenge-repsonse-attestation
    |  +---w input
    |  |  +---w tpm2-attestation-challenge
    |  |  |  +---w pcr-list* []
    |  |  |  |  +---w pcr
    |  |  |  |     +---w pcr-numbers*                  uint8
    |  |  |  |     +---w (algo-registry-type)
    |  |  |  |        +--:(tcg)
    |  |  |  |        |  +---w tcg-hash-algo-id?       uint16
    |  |  |  |        +--:(ietf)
    |  |  |  |           +---w ietf-ni-hash-algo-id?   uint8
    |  |  |  +---w nonce-value                   binary
    |  |  |  +---w (signature-identifier-type)
    |  |  |  |  +--:(TPM_ALG_ID)
    |  |  |  |  |  +---w TPM_ALG_ID-value?       uint16
    |  |  |  |  +--:(COSE_Algorithm)
    |  |  |  |     +---w COSE_Algorithm-value?   int32
    |  |  |  +---w (key-identifier)?
    |  |  |     +--:(public-key)
    |  |  |     |  +---w pub-key-id?             binary
    |  |  |     +--:(uuid)
    |  |  |        +---w uuid-value?             binary
    |  |  +---w location?                     string
    |  +--ro output
    |     +--ro tpm2-attestation-response* [location]
    |        +--ro location          string
    |        +--ro tpms-attest
    |        |  +--ro pcrdigest?            binary
    |        |  +--ro pcrdigest-length?     uint32
    |        |  +--ro tpms-attest-result?   binary
    |        +--ro tpmt-signature?   binary
    +---x basic-trust-establishment
    |  +---w input
    |  |  +---w nonce-value                   binary
    |  |  +---w pcr-list* []
    |  |  |  +---w pcr
    |  |  |     +---w pcr-numbers*                  uint8
    |  |  |     +---w (algo-registry-type)
    |  |  |        +--:(tcg)
    |  |  |        |  +---w tcg-hash-algo-id?       uint16
    |  |  |        +--:(ietf)
    |  |  |           +---w ietf-ni-hash-algo-id?   uint8
    |  |  +---w (signature-identifier-type)
    |  |  |  +--:(TPM_ALG_ID)
    |  |  |  |  +---w TPM_ALG_ID-value?       uint16
    |  |  |  +--:(COSE_Algorithm)
    |  |  |     +---w COSE_Algorithm-value?   int32

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    |  |  +---w location?                     string
    |  +--ro output
    |     +--ro attestation-certificates* [location]
    |        +--ro location                   string
    |        +--ro attestation-certificate?   binary
    |        +--ro (key-identifier)?
    |           +--:(public-key)
    |           |  +--ro pub-key-id?          binary
    |           +--:(uuid)
    |              +--ro uuid-value?          binary
    +---x log-retrieval
       +---w input
       |  +---w (index-type)?
       |  |  +--:(last-entry)
       |  |  |  +---w last-entry-value?   binary
       |  |  +--:(index)
       |  |     +---w index-number?       uint64
       |  +---w measurement-log-type      identityref
       |  +---w pcr-list* []
       |  |  +---w pcr
       |  |     +---w pcr-numbers*                  uint8
       |  |     +---w (algo-registry-type)
       |  |        +--:(tcg)
       |  |        |  +---w tcg-hash-algo-id?       uint16
       |  |        +--:(ietf)
       |  |           +---w ietf-ni-hash-algo-id?   uint8
       |  +---w chunk-size?               uint64
       |  +---w location?                 string
       +--ro output
          +--ro system-event-logs
             +--ro node-data* [node-location]
                +--ro node-location    string
                +--ro up-time?         uint32
                +--ro log-result
                   +--ro (log-type)
                      +--:(bios)
                      |  +--ro bios-event-logs
                      |     +--ro bios-event-entry* [event-number]
                      |        +--ro event-number    uint32
                      |        +--ro event-type?     uint32
                      |        +--ro pcr-index?      uint16
                      |        +--ro digest-list* []
                      |        |  +--ro (algo-registry-type)
                      |        |  |  +--:(tcg)
                      |        |  |  |  +--ro tcg-hash-algo-id?       uint16
                      |        |  |  +--:(ietf)
                      |        |  |     +--ro ietf-ni-hash-algo-id?   uint8
                      |        |  +--ro digest*                       binary

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                      |        +--ro event-size?     uint32
                      |        +--ro event-data*     uint8
                      +--:(ima)
                         +--ro ima-event-logs
                            +--ro ima-event-entry* [event-number]
                               +--ro event-number               uint64
                               +--ro ima-template?              string
                               +--ro filename-hint?             string
                               +--ro filedata-hash?             binary
                               +--ro template-hash-algorithm?   string
                               +--ro template-hash?             binary
                               +--ro pcr-index?                 uint16
                               +--ro signature?                 binary
<CODE ENDS>

2.2.  Raw Format

<CODE BEGINS>
module ietf-basic-remote-attestation {
  namespace "urn:ietf:params:xml:ns:yang:ietf-basic-remote-attestation";
  prefix "yang-brat";
  organization
   "Fraunhofer SIT";
  contact
   "Henk Birkholz
    Fraunhofer Institute for Secure Information Technology
    Email: henk.birkholz@sit.fraunhofer.de";
  description
    "A YANG module to enable a TPM 2.0 based remote attestation
     procedure.
     Copyright (C) Fraunhofer SIT (2018).";
  revision "2018-06-15" {
  description
    "Initial version";
  reference
    "draft-birkholz-yang-basic-remote-attestation";
  }

  grouping hash-algo {
    description
      "A selector for the hashing algorithm";
    choice algo-registry-type {
      mandatory true;
      description
        "Unfortunately, both IETF and TCG have registries here.
        Choose your weapon wisely.";
      case tcg {
        description

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          "you chose the east door, the tcg space opens up to
          you.";
        leaf tcg-hash-algo-id {
          type uint16;
          description
            "This is an index referencing the TCG Algorithm
            Registry based on TPM_ALG_ID.";
        }
      }
      case ietf {
        description
          "you chose the west door, the ietf space opens up to
          you.";
        leaf ietf-ni-hash-algo-id {
          type uint8;
          description
            "This is an index referencing the Named Information
             Hash Algorithm Registry.";
        }
      }
    }
  }

  grouping hash {
    description
      "The hash value including hash-algo identifer";
    list hash-digests {
      description
        "The list of hashes.";
      container hash-digest {
        description
          "A hash value based on a hash algorithm registered by an
          SDO.";
        uses hash-algo;
        leaf hash-value {
          type binary;
          description
            "The binary representaion of the hash value.";
        }
      }
    }
  }

  grouping nonce {
    description
      "A nonce to show freshness and counter replays.";
    leaf nonce-value {
      type binary;

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      mandatory true;
      description
        "This nonce SHOULD be generated via a registered
        cryptographic-strength algorithm. In consequence, the length
        of the nonce depends on the hash algorithm used. The algorithm
        used in this case is independent from the hash algorithm used to
        create the hash-value in the response of the attestor.";
    }
  }

  grouping pcr-selection {
    description
      "A Verifier can request one or more PCR values uses its
      individually created AC. The corresponding selection filter is
      represented in this grouping. Requesting a PCR value that is not in
      scope of the AC used, detailed exposure via error msg should be
      avoided.";
    list pcr-list {
      description
        "For each PCR in this list an individual list of banks (hash-algo)
        can be requested. It depends on the datastore, if every bank in
        this grouping is included per PCR (crude), or if each requested
        bank set is returned for each PCR individually (elegant).";
      container pcr {
        description
          "The composite of a PCR number and corresponding bank numbers.";
        leaf-list pcr-numbers {
           type uint8;
           description
             "The number of the PCR. At the moment this is limited
             32";
        }
        uses hash-algo;
      }
    }
  }

  grouping pcr-selector {
    description
      "A Verifier can request the generation of an attestation
      certificate (a signed public attestation key
      (non-migratable, tpm-resident) wrt one or more PCR values.
      The corresponding creation input is represented in this grouping.
      Requesting a PCR value that is not supported results in an error,
      detailed exposure via error msg should be avoided.";
    list pcr-list {
      description
        "For each PCR in this list an individual hash-algo can be

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        requested.";
      container pcr {
        description
          "The composite of a PCR number and corresponding bank numbers.";
        leaf-list pcr-numbers {
           type uint8;
           description
             "The numbers of the PCRs that are associated with
             the created key. At the moment the highest number is 32";
        }
        uses hash-algo;
      }
    }
  }

  grouping signature-scheme {
    description
      "The signature scheme used to sign the evidence.";
    choice signature-identifier-type {
      mandatory true;
      description
        "There are multiple ways to reference a signature type.
        This used to select the signature algo to sign the quote
        information response.";
      case TPM_ALG_ID {
        description
          "This references the indices of table 9 in the TPM 2.0 structure specification.";
        leaf TPM_ALG_ID-value {
          type uint16;
          description
            "The TPM Algo ID.";
        }
      }
      case COSE_Algorithm {
        description
          "This references the IANA COSE Algorithms Registry indices. Every index of this
          registry to be used must be mapable to a TPM_ALG_ID value.";
        leaf COSE_Algorithm-value {
          type int32;
          description
            "The TPM Algo ID.";
        }
      }
    }
  }

  grouping attestation-key-identifier {
    description

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      "A selector for a suitable key identifier.";
    choice key-identifier {
      description
        "Identifier for the attestation key to use for signing
        attestation evidence.";
      case public-key {
        leaf pub-key-id {
          type binary;
          description
            "The value of the identifier for the public key.";
        }
      }
      case uuid {
        description
          "Use a YANG agent generated (and maintained) attestation
          key UUID.";
        leaf uuid-value {
          type binary;
          description
            "The UUID identifying the corresponding public key.";
        }
      }
    }
  }

 grouping node-location {
   description
     "In a distributed system get the data from a specific node
      identified by the location. If this field is not specified
      data associated with each node forming the system will be
      returned.";
   leaf location {
      type string;
      description
      "Location of the node or All";
   }

 }
  identity log-type {
    description
      "The type of logs available.";
  }

  identity bios {
    base log-type;
    description
      "Measurement log created by the BIOS/UEFI.";
  }

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  identity ima {
    base log-type;
    description
      "Measurement log created by IMA.";
  }

  grouping log-identifier {
    description
      "Identifier for type of log to be retrieved.";
    leaf measurement-log-type {
      type identityref {
        base log-type;
      }
      mandatory true;
      description
        "The corresponding log type identity.";
    }
  }

grouping boot-event-log {
  description
    "Defines an event log corresponding to the event that extended the PCR";
  leaf event-number {
      type uint32;
      description
  "Unique event number of this event";
  }
  leaf event-type {
      type uint32;
      description
  "log event type";
  }
  leaf pcr-index {
     type uint16;
     description
 "Defines the PCR index that this event extended";
  }
  list digest-list {
    description "Hash of event data";
    uses hash-algo;
    leaf-list digest {
      type binary;
      description
      "The hash of the event data";
    }
  }
   leaf event-size {

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     type uint32;
     description
     "Size of the event data";
   }
   leaf-list event-data {
     type uint8;
     description
     "the event data size determined by event-size";
   }
}

 grouping ima-event {
   description
     "Defines an hash log extend event for IMA measurements";
   leaf event-number {
       type uint64;
       description
  "Unique number for this event for sequencing";
     }
   leaf ima-template {
     type string;
     description
     "Name of the template used for event logs
     for e.g. ima, ima-ng";
   }
   leaf filename-hint {
       type string;
       description
   "File that was measured";
   }
   leaf filedata-hash {
       type binary;
       description
    "Hash of filedata";
   }
  leaf template-hash-algorithm {
    type string;
    description
     "Algorithm used for template-hash";
   }
   leaf template-hash {
  type binary;
  description
   " hash(filedata-hash, filename-hint)";
   }
   leaf pcr-index {
      type uint16;
      description

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  "Defines the PCR index that this event extended";
   }
   leaf signature {
     type binary;
     description
     "The file signature";
   }
 }

  grouping bios-event-log {
    description
    "Measurement log created by the BIOS/UEFI.";
    list bios-event-entry {
      key event-number;
       description
       "Ordered list of TCG described event log
        that extended the PCRs in the order they
        were logged";
        uses boot-event-log;
     }
  }

  grouping ima-event-log {
    list ima-event-entry {
      key event-number;
      description
      "Ordered list of ima event logs by event-number";
       uses ima-event;
    }
    description
      "Measurement log created by IMA.";
  }

  grouping event-logs {
    description
      "A selector for the log and its type.";
    choice log-type {
      mandatory true;
      description
        "Event log type determines the event logs content.";
      case bios {
        description
          "BIOS/UEFI event logs";
        container bios-event-logs {
          description
            "This is an index referencing the TCG Algorithm
            Registry based on TPM_ALG_ID.";
          uses bios-event-log;

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        }
      }
      case ima {
        description
          "IMA event logs";
        container ima-event-logs {
          description
            "This is an index referencing the TCG Algorithm
            Registry based on TPM_ALG_ID.";
          uses ima-event-log;
        }
      }
    }
  }

  rpc tpm2-challenge-repsonse-attestation {
    description
      "This RPC accepts the input for TSS commands of the managed device.
      ComponentIndex from the hardware manager YANG module to refer to
      dedicated TPM in composite devices, e.g. smart NICs, is still a
      TODO.";
    input {
      container tpm2-attestation-challenge {
        description
          "This container includes every information element defined
           in the reference challenge-response interaction model for
           remote attestation. Corresponding values are based on
           TPM 2.0 structure definitions";
        uses pcr-selection;
        uses nonce;
        uses signature-scheme;
        uses attestation-key-identifier;
      }
      uses node-location;
    }
    output {
      list tpm2-attestation-response {
        key location;
        description
          "The binary output of TPM2b_Quote. An TPMS_ATTEST structure
          including a length, encapsulated in a signature";
        uses node-location;
        container tpms-attest {
          leaf pcrdigest {
            type binary;
            description
              "split out value of TPMS_QUOTE_INFO for convenience";

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          }
          leaf pcrdigest-length {
            type uint32;
            description
              "split out length of digest for convenience";
          }
          leaf tpms-attest-result {
            type binary;
            description
              "The complete TPM generate structure including signature.";
          }
          description
            "A composite of value and length and list of selected
            pcrs (original name: [type]attested)";
        }
        leaf tpmt-signature {
          type binary;
          description
             "split out value of the signature for convenience";
        }
      }
    }
  }

  rpc basic-trust-establishment {
    description
      "This RPC creates a tpm-resident, non-migratable key to be used
      in TPM_Quote commands, an attestation certificate.";
    input {
      uses nonce;
      uses pcr-selector;
      uses signature-scheme;
      uses node-location;
    }
    output {
      list attestation-certificates {
        key location;
        uses node-location;
        leaf attestation-certificate {
          type binary;
          description
            "An individual signed public attestation according to requested
            capabilities.";
        }
        uses attestation-key-identifier;
        description
          "Attestation Certificate data of a node in a distributed system
          identified by the location";

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      }
    }
  }

  rpc log-retrieval {
    description
      "Logs Entries are either identified via indices or via providing
      the last line received. The number of lines returned can be limited.
      The type of log is a choice that can be
      augmented.";
    input {
      choice index-type {
        case last-entry {
          leaf last-entry-value {
            type binary;
            description
              "Content of the last entry requested.";
          }
          description
            "The last entry of the log already retrieved";
        }
        case index {
          leaf index-number {
            type uint64;
            description
              "The numeric index number";
          }
          description
            "Numeric index of the last log entry retrieved.";
        }
        description
          "Last-line or index.";
      }
      uses log-identifier;
      uses pcr-selection;
      leaf chunk-size {
        type uint64;
        description
         "The number of log entries to be returned. If omitted, it means all of them.";
      }
      uses node-location;
    }
    output {
      container system-event-logs {
        list node-data {
          key node-location;
          description
            "Event logs of a node in a distributed system

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             identified by the location";
          leaf node-location {
            type string;
            description
              "Location of the node in the distributed system";
          }
          leaf up-time {
            type uint32;
            description
              "Uptime in seconds of this node reporting its data";
          }
          container log-result {
            description
              "The requested entries of the corresponding log.";
          uses event-logs;
          }
        }
        description
          "The requested data of the measurement event logs";
      }
    }
  }

  container rats-support-structures {
    leaf-list supported-algos {
      type uint16;
      description
        "Supported TPM_ALG_ID values for the TPM in question.
        Will include ComponentIndex soon.";
    }
    leaf endorsement-certificate {
      type binary;
      description
        "The signed pulic endorsement key (EK) and corresponding claims
         (EK Certificate). In a TPM 2.0 the EK Certificate resides in a
         well-defined NVRAM location by the TPM vednor.";
    }
    description
      "Basic information elements to enable RATS.";
  }
}
<CODE ENDS>

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3.  Security Considerations

   There are always some.

4.  Acknowledgements

   Not yet.

5.  Change Log

   No changes yet.

6.  References

6.1.  Normative References

   [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>.

6.2.  Informative References

   [I-D.birkholz-attestation-terminology]
              Birkholz, H., Wiseman, M., and H. Tschofenig, "Reference
              Terminology for Remote Attestation Procedures", draft-
              birkholz-attestation-terminology-01 (work in progress),
              January 2018.

Authors' Addresses

   Henk Birkholz
   Fraunhofer SIT
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   Email: henk.birkholz@sit.fraunhofer.de

   Michael Eckel
   Huawei Technologies
   Feldbergstrasse 78
   Darmstadt  64293
   Germany

   Email: michael.eckel@huawei.com

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Internet-Draft                    BRAT                         July 2018

   Shwetha Bhandari
   Cisco Systems

   Email: shwethab@cisco.com

   Bill Sulzen
   Cisco Systems

   Email: bsulzen@cisco.com

   Eric Voit
   Cisco Systems

   Email: evoit@cisco.com

   Guy C. Fedorkow
   Juniper Networks
   10 Technology Park Drive
   Westford, Massachusetts  01886

   Email: gfedorkow@juniper.de

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