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cli: Generalize PCRs to Measurements in preparation for TDX

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This commit is contained in:
Nils Hanke 2023-03-22 13:40:02 +01:00 committed by Malte Poll
parent 7e5e3b9d2e
commit c507bd7d95
3 changed files with 17 additions and 17 deletions
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30
cli/internal/cloudcmd/validators.go
View File

@ -24,23 +24,23 @@ func NewValidator(cmd *cobra.Command, config config.AttestationCfg, log debugLog
return choose.Validator(config, warnLogger{cmd: cmd, log: log})
}
// UpdateInitPCRs sets the owner and cluster PCR values.
func UpdateInitPCRs(config config.AttestationCfg, ownerID, clusterID string) error {
// UpdateInitMeasurements sets the owner and cluster measurement values.
func UpdateInitMeasurements(config config.AttestationCfg, ownerID, clusterID string) error {
m := config.GetMeasurements()
if err := updatePCR(m, uint32(measurements.PCRIndexOwnerID), ownerID); err != nil {
if err := updateMeasurement(m, uint32(measurements.PCRIndexOwnerID), ownerID); err != nil {
return err
}
return updatePCR(m, uint32(measurements.PCRIndexClusterID), clusterID)
return updateMeasurement(m, uint32(measurements.PCRIndexClusterID), clusterID)
}
// updatePCR adds a new entry to the measurements of v, or removes the key if the input is an empty string.
// updateMeasurement adds a new entry to the measurements of v, or removes the key if the input is an empty string.
//
// When adding, the input is first decoded from hex or base64.
// We then calculate the expected PCR by hashing the input using SHA256,
// appending expected PCR for initialization, and then hashing once more.
func updatePCR(m measurements.M, pcrIndex uint32, encoded string) error {
// We then calculate the expected measurement by hashing the input using SHA256,
// appending expected measurement for initialization, and then hashing once more.
func updateMeasurement(m measurements.M, measurementIdx uint32, encoded string) error {
if encoded == "" {
delete(m, pcrIndex)
delete(m, measurementIdx)
return nil
}
@ -53,14 +53,14 @@ func updatePCR(m measurements.M, pcrIndex uint32, encoded string) error {
return fmt.Errorf("input [%s] could neither be hex decoded (%w) nor base64 decoded (%w)", encoded, hexErr, err)
}
}
// new_pcr_value := hash(old_pcr_value || data_to_extend)
// new_measurement_value := hash(old_pcr_value || data_to_extend)
// Since we use the TPM2_PCR_Event call to extend the PCR, data_to_extend is the hash of our input
hashedInput := sha256.Sum256(decoded)
oldExpected := m[pcrIndex].Expected
expectedPcr := sha256.Sum256(append(oldExpected[:], hashedInput[:]...))
m[pcrIndex] = measurements.Measurement{
Expected: expectedPcr[:],
ValidationOpt: m[pcrIndex].ValidationOpt,
oldExpected := m[measurementIdx].Expected
expectedMeasurement := sha256.Sum256(append(oldExpected[:], hashedInput[:]...))
m[measurementIdx] = measurements.Measurement{
Expected: expectedMeasurement[:],
ValidationOpt: m[measurementIdx].ValidationOpt,
}
return nil
}

2
cli/internal/cloudcmd/validators_test.go
View File

@ -114,7 +114,7 @@ func TestValidatorUpdateInitPCRs(t *testing.T) {
t.Run(name, func(t *testing.T) {
assert := assert.New(t)
err := UpdateInitPCRs(tc.config, tc.ownerID, tc.clusterID)
err := UpdateInitMeasurements(tc.config, tc.ownerID, tc.clusterID)
if tc.wantErr {
assert.Error(err)

2
cli/internal/cmd/verify.go
View File

@ -94,7 +94,7 @@ func (c *verifyCmd) verify(cmd *cobra.Command, fileHandler file.Handler, verifyC
conf.UpdateMAAURL(flags.maaURL)
c.log.Debugf("Updating expected PCRs")
attConfig := conf.GetAttestationConfig()
if err := cloudcmd.UpdateInitPCRs(attConfig, flags.ownerID, flags.clusterID); err != nil {
if err := cloudcmd.UpdateInitMeasurements(attConfig, flags.ownerID, flags.clusterID); err != nil {
return fmt.Errorf("updating expected PCRs: %w", err)
}