mirror of
https://github.com/ultravioletrs/cocos.git
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COCOS-326 - Add vTPM support to CoCoS (#376)
* manager, cli and agent vtpm support * rebase and changed atls for vtpm * deleted unused code * changed chekproto.yaml script so it find the manager proto file correctly * fixe manager proto version * fix agent tests * fix server agent test * fix attestation test * fix attestation test gofumpt * created dummy RWC for TPM * fix comment * add default PCR values * rebase main * fix rust ci and missing header * changed embedded attestation to VMPL 2 * fix unused impot * fix pkg test * address attestation type * fix agent attestation test * add prc15 check * fix comments * fix cli tests * add doc * add mock for LeveledQuoteProvider when SEV-SNP device is not found Signed-off-by: Sammy Oina <sammyoina@gmail.com> * fix manager reading attestation policy * refactor PCR value checks and update attestation policy values Signed-off-by: Sammy Oina <sammyoina@gmail.com> * fix tests for sev and grpc --------- Signed-off-by: Sammy Oina <sammyoina@gmail.com> Co-authored-by: Sammy Oina <sammyoina@gmail.com>
This commit is contained in:
Danko Miladinovic
committed by
GitHub
GitHub
parent
fa26573643
commit
67f939fc66
@@ -0,0 +1,307 @@
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// Copyright (c) Ultraviolet
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// SPDX-License-Identifier: Apache-2.0
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package vtpm
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import (
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"bytes"
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"crypto"
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"crypto/sha256"
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"crypto/sha512"
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"crypto/x509"
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"encoding/hex"
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"fmt"
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"io"
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"os"
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"strconv"
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"github.com/absmach/magistrala/pkg/errors"
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"github.com/google/go-sev-guest/abi"
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"github.com/google/go-tpm-tools/client"
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"github.com/google/go-tpm-tools/proto/attest"
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"github.com/google/go-tpm-tools/proto/tpm"
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"github.com/google/go-tpm-tools/server"
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"github.com/google/go-tpm/legacy/tpm2"
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"github.com/google/go-tpm/tpmutil"
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config "github.com/ultravioletrs/cocos/pkg/attestation"
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"github.com/ultravioletrs/cocos/pkg/attestation/quoteprovider"
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"golang.org/x/crypto/sha3"
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"google.golang.org/protobuf/proto"
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)
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const (
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eventLog = "/sys/kernel/security/tpm0/binary_bios_measurements"
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Nonce = 32
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PCR15 = 15
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Hash256 = 32
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Hash384 = 48
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)
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var (
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ExternalTPM io.ReadWriteCloser
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ErrNoHashAlgo = errors.New("hash algo is not supported")
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)
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type tpmWrapper struct {
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io.ReadWriteCloser
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}
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func (et tpmWrapper) EventLog() ([]byte, error) {
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return os.ReadFile(eventLog)
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}
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func OpenTpm() (io.ReadWriteCloser, error) {
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if ExternalTPM != nil {
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return tpmWrapper{ExternalTPM}, nil
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}
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tw := tpmWrapper{}
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var err error
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tw.ReadWriteCloser, err = tpm2.OpenTPM("/dev/tpmrm0")
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if os.IsNotExist(err) {
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tw.ReadWriteCloser, err = tpm2.OpenTPM("/dev/tpm0")
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}
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return tw, err
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}
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func ExtendPCR(pcrIndex int, value []byte) error {
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rwc, err := OpenTpm()
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if err != nil {
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return err
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}
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defer rwc.Close()
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fixedSha256Hash := sha3.Sum256(value)
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if err := tpm2.PCRExtend(rwc, tpmutil.Handle(pcrIndex), tpm2.AlgSHA256, fixedSha256Hash[:], ""); err != nil {
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return err
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}
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fixedSha384Hash := sha3.Sum384(value)
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if err := tpm2.PCRExtend(rwc, tpmutil.Handle(pcrIndex), tpm2.AlgSHA384, fixedSha384Hash[:], ""); err != nil {
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return err
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}
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return nil
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}
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func Attest(teeNonce []byte, vTPMNonce []byte, teeAttestaion bool) ([]byte, error) {
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attestation, err := fetchVTPMQuote(vTPMNonce)
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if err != nil {
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return []byte{}, err
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}
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if teeAttestaion {
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attestation, err = addTEEAttestation(attestation, teeNonce)
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if err != nil {
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return []byte{}, err
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}
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}
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return marshalQuote(attestation)
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}
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func FetchATLSQuote(pubKey, teeNonce, vTPMNonce []byte) ([]byte, error) {
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attestation, err := fetchVTPMQuote(vTPMNonce)
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if err != nil {
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return []byte{}, err
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}
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reportData, err := createTEEAttestationReportNonce(pubKey, attestation.GetAkPub(), teeNonce)
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if err != nil {
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return []byte{}, err
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}
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attestation, err = addTEEAttestation(attestation, reportData)
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if err != nil {
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return []byte{}, err
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}
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return marshalQuote(attestation)
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}
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func VTPMVerify(quote []byte, pubKeyTLS []byte, teeNonce []byte, vtpmNonce []byte) error {
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attestation := &attest.Attestation{}
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err := proto.Unmarshal(quote, attestation)
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if err != nil {
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return fmt.Errorf("fail to unmarshal quote: %v", err)
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}
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ak := attestation.GetAkPub()
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pub, err := tpm2.DecodePublic(ak)
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if err != nil {
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return err
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}
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cryptoPub, err := pub.Key()
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if err != nil {
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return err
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}
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reportData, err := createTEEAttestationReportNonce(pubKeyTLS, ak, teeNonce)
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if err != nil {
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return fmt.Errorf("fail to calculate report data: %v", err)
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}
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if err := quoteprovider.VerifyAttestationReportTLS(attestation.GetSevSnpAttestation(), reportData); err != nil {
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return fmt.Errorf("failed to verify TEE attestation report: %v", err)
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}
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_, err = server.VerifyAttestation(attestation, server.VerifyOpts{Nonce: vtpmNonce, TrustedAKs: []crypto.PublicKey{cryptoPub}})
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if err != nil {
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return fmt.Errorf("verifying attestation: %w", err)
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}
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s256, s384 := calculatePCRTLSKey(pubKeyTLS)
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if err := checkExpectedPCRValues(attestation, s256, s384); err != nil {
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return fmt.Errorf("PCR values do not match expected PCR values: %w", err)
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}
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return nil
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}
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func publicKeyToBytes(pubKey interface{}) ([]byte, error) {
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derBytes, err := x509.MarshalPKIXPublicKey(pubKey)
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if err != nil {
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return nil, err
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}
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return derBytes, nil
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}
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func createTEEAttestationReportNonce(pubKeyTLS []byte, ak []byte, nonce []byte) ([]byte, error) {
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pub, err := tpm2.DecodePublic(ak)
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if err != nil {
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return []byte{}, err
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}
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cryptoPub, err := pub.Key()
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if err != nil {
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return []byte{}, err
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}
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pubKeyBytes, err := publicKeyToBytes(cryptoPub)
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if err != nil {
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return []byte{}, err
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}
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reportData := append(append(pubKeyTLS, pubKeyBytes...), nonce...)
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hash := sha3.Sum512(reportData)
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return hash[:], nil
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}
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func marshalQuote(attestation *attest.Attestation) ([]byte, error) {
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out, err := proto.Marshal(attestation)
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if err != nil {
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return []byte{}, fmt.Errorf("failed to marshal vTPM attestation report: %v", err)
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}
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return out, nil
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}
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func fetchVTPMQuote(nonce []byte) (*attest.Attestation, error) {
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rwc, err := OpenTpm()
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if err != nil {
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return nil, err
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}
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defer rwc.Close()
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attestationKey, err := client.AttestationKeyRSA(rwc)
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if err != nil {
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return nil, fmt.Errorf("failed to create attestation key: %v", err)
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}
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defer attestationKey.Close()
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var fixedNonce [Nonce]byte
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copy(fixedNonce[:], nonce)
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attestOpts := client.AttestOpts{}
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attestOpts.Nonce = fixedNonce[:]
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attestOpts.TCGEventLog, err = client.GetEventLog(rwc)
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if err != nil {
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return nil, fmt.Errorf("failed to retrieve TCG Event Log: %w", err)
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}
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attestation, err := attestationKey.Attest(attestOpts)
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if err != nil {
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return nil, fmt.Errorf("failed to collect attestation report: %v", err)
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}
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return attestation, nil
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}
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func addTEEAttestation(attestation *attest.Attestation, nonce []byte) (*attest.Attestation, error) {
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rawTeeAttestation, err := quoteprovider.FetchAttestation(nonce)
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if err != nil {
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return attestation, fmt.Errorf("failed to fetch TEE attestation report: %v", err)
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}
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extReport, err := abi.ReportCertsToProto(rawTeeAttestation)
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if err != nil {
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return attestation, fmt.Errorf("failed to export the TEE report: %v", err)
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}
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attestation.TeeAttestation = &attest.Attestation_SevSnpAttestation{
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SevSnpAttestation: extReport,
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}
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return attestation, nil
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}
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func checkExpectedPCRValues(attestation *attest.Attestation, ePcr256 []byte, ePcr384 []byte) error {
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quotes := attestation.GetQuotes()
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for i := range quotes {
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quote := quotes[i]
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var pcrMap map[string]string
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var pcr15 []byte
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switch quote.Pcrs.Hash {
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case tpm.HashAlgo_SHA256:
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pcrMap = config.AttestationPolicy.PcrConfig.PCRValues.Sha256
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pcr15 = ePcr256
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case tpm.HashAlgo_SHA384:
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pcrMap = config.AttestationPolicy.PcrConfig.PCRValues.Sha384
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pcr15 = ePcr384
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default:
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return errors.Wrap(ErrNoHashAlgo, fmt.Errorf("algo: %s", tpm.HashAlgo_name[int32(quote.Pcrs.Hash)]))
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}
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pcr15Index := uint32(15)
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if !bytes.Equal(quote.Pcrs.Pcrs[pcr15Index], pcr15) {
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return fmt.Errorf("for algo %s PCR[15] expected %s but found %s", tpm.HashAlgo_name[int32(quote.Pcrs.Hash)], hex.EncodeToString(pcr15), hex.EncodeToString(quote.Pcrs.Pcrs[pcr15Index]))
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}
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for i, v := range pcrMap {
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index, err := strconv.ParseInt(i, 10, 32)
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if err != nil {
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return fmt.Errorf("error converting PCR index to int32: %v\n", err)
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}
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value, err := hex.DecodeString(v)
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if err != nil {
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return fmt.Errorf("error converting PCR value to byte: %v\n", err)
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}
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if !bytes.Equal(quote.Pcrs.Pcrs[uint32(index)], value) {
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return fmt.Errorf("for algo %s PCR[%d] expected %s but found %s", tpm.HashAlgo_name[int32(quote.Pcrs.Hash)], index, hex.EncodeToString(value), hex.EncodeToString(quote.Pcrs.Pcrs[uint32(index)]))
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}
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}
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}
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return nil
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}
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// Return SHA256 and SHA384 values of the input public key.
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func calculatePCRTLSKey(pubKey []byte) ([]byte, []byte) {
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init256 := make([]byte, Hash256)
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init384 := make([]byte, Hash384)
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key256 := sha3.Sum256(pubKey)
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key384 := sha3.Sum384(pubKey)
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pcrValue256 := append(init256, key256[:]...)
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pcrValue384 := append(init384, key384[:]...)
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newPcr256 := sha256.Sum256(pcrValue256)
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newPcr384 := sha512.Sum384(pcrValue384)
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return newPcr256[:], newPcr384[:]
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}
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