constellation/internal/watcher/validator.go

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package watcher
import (
"encoding/asn1"
"fmt"
"path/filepath"
"sync"
"github.com/edgelesssys/constellation/internal/atls"
"github.com/edgelesssys/constellation/internal/attestation/azure"
"github.com/edgelesssys/constellation/internal/attestation/gcp"
"github.com/edgelesssys/constellation/internal/attestation/qemu"
"github.com/edgelesssys/constellation/internal/cloud/cloudprovider"
"github.com/edgelesssys/constellation/internal/constants"
"github.com/edgelesssys/constellation/internal/file"
"github.com/edgelesssys/constellation/internal/logger"
)
// Updatable implements an updatable atls.Validator.
type Updatable struct {
log *logger.Logger
mux sync.Mutex
newValidator newValidatorFunc
fileHandler file.Handler
atls.Validator
}
// NewValidator initializes a new updatable validator.
func NewValidator(log *logger.Logger, csp string, fileHandler file.Handler) (*Updatable, error) {
var newValidator newValidatorFunc
switch cloudprovider.FromString(csp) {
case cloudprovider.Azure:
newValidator = func(m map[uint32][]byte, e []uint32) atls.Validator { return azure.NewValidator(m, e) }
case cloudprovider.GCP:
newValidator = func(m map[uint32][]byte, e []uint32) atls.Validator { return gcp.NewValidator(m, e) }
case cloudprovider.QEMU:
newValidator = func(m map[uint32][]byte, e []uint32) atls.Validator { return qemu.NewValidator(m, e) }
default:
return nil, fmt.Errorf("unknown cloud service provider: %q", csp)
}
u := &Updatable{
log: log,
newValidator: newValidator,
fileHandler: fileHandler,
}
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)
u.Validator = u.newValidator(measurements, enforced)
u.Validator.AddLogger(u.log)
return nil
}
type newValidatorFunc func(measurements map[uint32][]byte, enforcedPCRs []uint32) atls.Validator