mirror of
https://github.com/edgelesssys/constellation.git
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131 lines
3.5 KiB
Go
131 lines
3.5 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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package watcher
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import (
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"context"
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"crypto/x509"
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"encoding/asn1"
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"fmt"
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"log/slog"
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"path/filepath"
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"sync"
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"github.com/edgelesssys/constellation/v2/internal/atls"
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"github.com/edgelesssys/constellation/v2/internal/attestation/choose"
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"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
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"github.com/edgelesssys/constellation/v2/internal/config"
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"github.com/edgelesssys/constellation/v2/internal/constants"
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"github.com/edgelesssys/constellation/v2/internal/file"
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)
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// Updatable implements an updatable atls.Validator.
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type Updatable struct {
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log *slog.Logger
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mux sync.Mutex
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fileHandler file.Handler
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variant variant.Variant
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cachedCerts cachedCerts
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atls.Validator
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}
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// NewValidator initializes a new updatable validator and performs an initial update (aka. initialization).
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func NewValidator(log *slog.Logger, variant variant.Variant, fileHandler file.Handler, cachedCerts cachedCerts) (*Updatable, error) {
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u := &Updatable{
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log: log,
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fileHandler: fileHandler,
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variant: variant,
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cachedCerts: cachedCerts,
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}
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err := u.Update()
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return u, err
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}
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type cachedCerts interface {
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SevSnpCerts() (ask *x509.Certificate, ark *x509.Certificate)
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}
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// Validate calls the validators Validate method, and prevents any updates during the call.
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func (u *Updatable) Validate(ctx context.Context, attDoc []byte, nonce []byte) ([]byte, error) {
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u.mux.Lock()
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defer u.mux.Unlock()
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return u.Validator.Validate(ctx, attDoc, nonce)
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}
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// OID returns the validators Object Identifier.
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func (u *Updatable) OID() asn1.ObjectIdentifier {
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u.mux.Lock()
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defer u.mux.Unlock()
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return u.Validator.OID()
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}
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// Update switches out the underlying validator.
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func (u *Updatable) Update() error {
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u.mux.Lock()
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defer u.mux.Unlock()
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u.log.Info("Updating expected measurements")
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data, err := u.fileHandler.Read(filepath.Join(constants.ServiceBasePath, constants.AttestationConfigFilename))
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if err != nil {
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return err
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}
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cfg, err := config.UnmarshalAttestationConfig(data, u.variant)
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if err != nil {
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return fmt.Errorf("unmarshaling config: %w", err)
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}
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u.log.Debug(fmt.Sprintf("New expected measurements: %s", cfg.GetMeasurements().String()))
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cfgWithCerts, err := u.configWithCerts(cfg)
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if err != nil {
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return fmt.Errorf("adding cached certificates: %w", err)
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}
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validator, err := choose.Validator(cfgWithCerts, u.log)
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if err != nil {
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return fmt.Errorf("choosing validator: %w", err)
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}
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u.Validator = validator
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return nil
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}
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// addCachedCerts adds the certificates cached by the validator to the attestation config, if applicable.
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func (u *Updatable) configWithCerts(cfg config.AttestationCfg) (config.AttestationCfg, error) {
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switch c := cfg.(type) {
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case *config.AzureSEVSNP:
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ask, err := u.getCachedAskCert()
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if err != nil {
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return nil, fmt.Errorf("getting cached ASK certificate: %w", err)
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}
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c.AMDSigningKey = config.Certificate(ask)
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return c, nil
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case *config.AWSSEVSNP:
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ask, err := u.getCachedAskCert()
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if err != nil {
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return nil, fmt.Errorf("getting cached ASK certificate: %w", err)
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}
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c.AMDSigningKey = config.Certificate(ask)
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return c, nil
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}
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return cfg, nil
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}
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// getCachedAskCert returns the cached SEV-SNP ASK certificate.
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func (u *Updatable) getCachedAskCert() (x509.Certificate, error) {
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if u.cachedCerts == nil {
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return x509.Certificate{}, fmt.Errorf("no cached certs available")
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}
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ask, _ := u.cachedCerts.SevSnpCerts()
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if ask == nil {
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return x509.Certificate{}, fmt.Errorf("no ASK available")
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}
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return *ask, nil
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}
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