constellation/internal/watcher/validator.go
2022-11-02 23:29:04 +01:00

147 lines
4.8 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package watcher
import (
"encoding/asn1"
"encoding/hex"
"fmt"
"path/filepath"
"strconv"
"sync"
"github.com/edgelesssys/constellation/v2/internal/atls"
"github.com/edgelesssys/constellation/v2/internal/attestation/aws"
"github.com/edgelesssys/constellation/v2/internal/attestation/azure/snp"
"github.com/edgelesssys/constellation/v2/internal/attestation/azure/trustedlaunch"
"github.com/edgelesssys/constellation/v2/internal/attestation/gcp"
"github.com/edgelesssys/constellation/v2/internal/attestation/qemu"
"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
"github.com/edgelesssys/constellation/v2/internal/constants"
"github.com/edgelesssys/constellation/v2/internal/file"
"github.com/edgelesssys/constellation/v2/internal/logger"
)
// Updatable implements an updatable atls.Validator.
type Updatable struct {
log *logger.Logger
mux sync.Mutex
newValidator newValidatorFunc
fileHandler file.Handler
csp cloudprovider.Provider
azureCVM bool
atls.Validator
}
// NewValidator initializes a new updatable validator.
func NewValidator(log *logger.Logger, csp string, fileHandler file.Handler, azureCVM bool) (*Updatable, error) {
var newValidator newValidatorFunc
switch cloudprovider.FromString(csp) {
case cloudprovider.AWS:
newValidator = func(m map[uint32][]byte, e []uint32, _ []byte, _ bool, log *logger.Logger) atls.Validator {
return aws.NewValidator(m, e, log)
}
case cloudprovider.Azure:
if azureCVM {
newValidator = func(m map[uint32][]byte, e []uint32, idkeydigest []byte, enforceIdKeyDigest bool, log *logger.Logger) atls.Validator {
return snp.NewValidator(m, e, idkeydigest, enforceIdKeyDigest, log)
}
} else {
newValidator = func(m map[uint32][]byte, e []uint32, idkeydigest []byte, enforceIdKeyDigest bool, log *logger.Logger) atls.Validator {
return trustedlaunch.NewValidator(m, e, log)
}
}
case cloudprovider.GCP:
newValidator = func(m map[uint32][]byte, e []uint32, _ []byte, _ bool, log *logger.Logger) atls.Validator {
return gcp.NewValidator(m, e, log)
}
case cloudprovider.QEMU:
newValidator = func(m map[uint32][]byte, e []uint32, _ []byte, _ bool, log *logger.Logger) atls.Validator {
return qemu.NewValidator(m, e, log)
}
default:
return nil, fmt.Errorf("unknown cloud service provider: %q", csp)
}
u := &Updatable{
log: log,
newValidator: newValidator,
fileHandler: fileHandler,
csp: cloudprovider.FromString(csp),
azureCVM: azureCVM,
}
if err := u.Update(); err != nil {
return nil, err
}
return u, nil
}
// Validate calls the validators Validate method, and prevents any updates during the call.
func (u *Updatable) Validate(attDoc []byte, nonce []byte) ([]byte, error) {
u.mux.Lock()
defer u.mux.Unlock()
return u.Validator.Validate(attDoc, nonce)
}
// OID returns the validators Object Identifier.
func (u *Updatable) OID() asn1.ObjectIdentifier {
return u.Validator.OID()
}
// Update switches out the underlying validator.
func (u *Updatable) Update() error {
u.mux.Lock()
defer u.mux.Unlock()
u.log.Infof("Updating expected measurements")
var measurements map[uint32][]byte
if err := u.fileHandler.ReadJSON(filepath.Join(constants.ServiceBasePath, constants.MeasurementsFilename), &measurements); err != nil {
return err
}
u.log.Debugf("New measurements: %v", measurements)
var enforced []uint32
if err := u.fileHandler.ReadJSON(filepath.Join(constants.ServiceBasePath, constants.EnforcedPCRsFilename), &enforced); err != nil {
return err
}
u.log.Debugf("Enforced PCRs: %v", enforced)
var idkeydigest []byte
var enforceIDKeyDigest bool
if u.csp == cloudprovider.Azure && u.azureCVM {
u.log.Infof("Updating encforceIdKeyDigest value")
enforceRaw, err := u.fileHandler.Read(filepath.Join(constants.ServiceBasePath, constants.EnforceIDKeyDigestFilename))
if err != nil {
return err
}
enforceIDKeyDigest, err = strconv.ParseBool(string(enforceRaw))
if err != nil {
return fmt.Errorf("parsing content of EnforceIdKeyDigestFilename: %s: %w", enforceRaw, err)
}
u.log.Debugf("New encforceIdKeyDigest value: %v", enforceIDKeyDigest)
u.log.Infof("Updating expected idkeydigest")
idkeydigestRaw, err := u.fileHandler.Read(filepath.Join(constants.ServiceBasePath, constants.IDKeyDigestFilename))
if err != nil {
return err
}
idkeydigest, err = hex.DecodeString(string(idkeydigestRaw))
if err != nil {
return fmt.Errorf("parsing hexstring: %s: %w", idkeydigestRaw, err)
}
u.log.Debugf("New idkeydigest: %x", idkeydigest)
}
u.Validator = u.newValidator(measurements, enforced, idkeydigest, enforceIDKeyDigest, u.log)
return nil
}
type newValidatorFunc func(measurements map[uint32][]byte, enforcedPCRs []uint32, idkeydigest []byte, enforceIdKeyDigest bool, log *logger.Logger) atls.Validator