constellation/cli/internal/cloudcmd/validators.go
2023-05-17 11:37:26 +02:00

126 lines
4.1 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package cloudcmd
import (
"crypto/sha256"
"crypto/sha512"
"encoding/base64"
"encoding/hex"
"fmt"
"github.com/edgelesssys/constellation/v2/internal/atls"
"github.com/edgelesssys/constellation/v2/internal/attestation/choose"
"github.com/edgelesssys/constellation/v2/internal/attestation/measurements"
"github.com/edgelesssys/constellation/v2/internal/config"
"github.com/edgelesssys/constellation/v2/internal/variant"
"github.com/spf13/cobra"
)
// NewValidator creates a new Validator.
func NewValidator(cmd *cobra.Command, config config.AttestationCfg, log debugLog) (atls.Validator, error) {
return choose.Validator(config, warnLogger{cmd: cmd, log: log})
}
// UpdateInitMeasurements sets the owner and cluster measurement values.
func UpdateInitMeasurements(config config.AttestationCfg, ownerID, clusterID string) error {
m := config.GetMeasurements()
switch config.GetVariant() {
case variant.AWSNitroTPM{}, variant.AzureTrustedLaunch{}, variant.AzureSEVSNP{}, variant.GCPSEVES{}, variant.QEMUVTPM{}:
if err := updateMeasurementTPM(m, uint32(measurements.PCRIndexOwnerID), ownerID); err != nil {
return err
}
return updateMeasurementTPM(m, uint32(measurements.PCRIndexClusterID), clusterID)
case variant.QEMUTDX{}:
// Measuring ownerID is currently not implemented for Constellation
// Since adding support for measuring ownerID to TDX would require additional code changes,
// the current implementation does not support it, but can be changed if we decide to add support in the future
return updateMeasurementTDX(m, uint32(measurements.TDXIndexClusterID), clusterID)
default:
return fmt.Errorf("selecting attestation variant: unknown attestation variant")
}
}
func updateMeasurementTDX(m measurements.M, measurementIdx uint32, encoded string) error {
if encoded == "" {
delete(m, measurementIdx)
return nil
}
decoded, err := decodeMeasurement(encoded)
if err != nil {
return err
}
// new_measurement_value := hash(old_measurement_value || data_to_extend)
// Since we use the DG.MR.RTMR.EXTEND call to extend the register, data_to_extend is the hash of our input
hashedInput := sha512.Sum384(decoded)
oldExpected := m[measurementIdx].Expected
expectedMeasurementSum := sha512.Sum384(append(oldExpected[:], hashedInput[:]...))
m[measurementIdx] = measurements.Measurement{
Expected: expectedMeasurementSum[:],
ValidationOpt: m[measurementIdx].ValidationOpt,
}
return nil
}
func updateMeasurementTPM(m measurements.M, measurementIdx uint32, encoded string) error {
if encoded == "" {
delete(m, measurementIdx)
return nil
}
decoded, err := decodeMeasurement(encoded)
if err != nil {
return err
}
// new_pcr_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[measurementIdx].Expected
expectedMeasurement := sha256.Sum256(append(oldExpected[:], hashedInput[:]...))
m[measurementIdx] = measurements.Measurement{
Expected: expectedMeasurement[:],
ValidationOpt: m[measurementIdx].ValidationOpt,
}
return nil
}
func decodeMeasurement(encoded string) ([]byte, error) {
decoded, err := hex.DecodeString(encoded)
if err != nil {
hexErr := err
decoded, err = base64.StdEncoding.DecodeString(encoded)
if err != nil {
return nil, fmt.Errorf("input [%s] could neither be hex decoded (%w) nor base64 decoded (%w)", encoded, hexErr, err)
}
}
return decoded, nil
}
// warnLogger implements logging of warnings for validators.
type warnLogger struct {
cmd *cobra.Command
log debugLog
}
// Infof messages are reduced to debug messages, since we don't want
// the extra info when using the CLI without setting the debug flag.
func (wl warnLogger) Infof(fmtStr string, args ...any) {
wl.log.Debugf(fmtStr, args...)
}
// Warnf prints a formatted warning from the validator.
func (wl warnLogger) Warnf(fmtStr string, args ...any) {
wl.cmd.PrintErrf("Warning: %s\n", fmt.Sprintf(fmtStr, args...))
}
type debugLog interface {
Debugf(format string, args ...any)
Sync()
}