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certificate_manager.go
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certificate_manager.go
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// Copyright 2017 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
package security
import (
"crypto/tls"
"os"
"os/signal"
"path/filepath"
"syscall"
"github.com/cockroachdb/cockroach/pkg/util/log"
"github.com/cockroachdb/cockroach/pkg/util/metric"
"github.com/cockroachdb/cockroach/pkg/util/stop"
"github.com/cockroachdb/cockroach/pkg/util/syncutil"
"golang.org/x/net/context"
"github.com/pkg/errors"
)
var (
metaCAExpiration = metric.Metadata{
Name: "security.certificate.expiration.ca",
Help: "Expiration timestamp for the CA certificate. 0 means no certificate or error."}
metaNodeExpiration = metric.Metadata{
Name: "security.certificate.expiration.node",
Help: "Expiration timestamp for the node certificate. 0 means no certificate or error."}
)
// CertificateManager lives for the duration of the process and manages certificates and keys.
// It reloads all certificates when triggered and construct tls.Config objects for
// servers or clients.
//
// Important note: Load() performs some sanity checks (file pairs match, CA certs don't disappear),
// but these are by no means complete. Completeness is not required as nodes restarting have
// no fallback if invalid certs/keys are present.
type CertificateManager struct {
// Certificate directory is not modified after initialization.
certsDir string
// The metrics struct is initialized at init time and metrics do their
// own locking.
certMetrics CertificateMetrics
// mu protects all remaining fields.
mu syncutil.RWMutex
// If false, this is the first load. Needed to ensure we do not drop certain certs.
initialized bool
// Set of certs. These are swapped in during Load(), and never mutated afterwards.
caCert *CertInfo
nodeCert *CertInfo
clientCerts map[string]*CertInfo
// TLS configs. Initialized lazily. Wiped on every successful Load().
// Server-side config.
serverConfig *tls.Config
// Client-side config for the cockroach node.
// All other client tls.Config objects are built as requested and not cached.
clientConfig *tls.Config
}
// CertificateMetrics holds metrics about the various certificates.
// These are initialized when the certificate manager is created and updated
// on reload.
type CertificateMetrics struct {
CAExpiration *metric.Gauge
NodeExpiration *metric.Gauge
}
func makeCertificateManager(certsDir string) *CertificateManager {
cm := &CertificateManager{certsDir: os.ExpandEnv(certsDir)}
// Initialize metrics:
cm.certMetrics = CertificateMetrics{
CAExpiration: metric.NewGauge(metaCAExpiration),
NodeExpiration: metric.NewGauge(metaNodeExpiration),
}
return cm
}
// NewCertificateManager creates a new certificate manager.
func NewCertificateManager(certsDir string) (*CertificateManager, error) {
cm := makeCertificateManager(certsDir)
return cm, cm.LoadCertificates()
}
// NewCertificateManagerFirstRun creates a new certificate manager.
// The certsDir is created if it does not exist.
// This should only be called when generating certificates, the server has
// no business creating the certs directory.
func NewCertificateManagerFirstRun(certsDir string) (*CertificateManager, error) {
cm := makeCertificateManager(certsDir)
if err := NewCertificateLoader(cm.certsDir).MaybeCreateCertsDir(); err != nil {
return nil, err
}
return cm, cm.LoadCertificates()
}
// Metrics returns the metrics struct.
func (cm *CertificateManager) Metrics() CertificateMetrics {
return cm.certMetrics
}
// RegisterSignalHandler registers a signal handler for SIGHUP, triggering a
// refresh of the certificates directory on notification.
func (cm *CertificateManager) RegisterSignalHandler(stopper *stop.Stopper) {
// Setup signal handler.
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, syscall.SIGHUP)
go func() {
for {
select {
case <-stopper.ShouldStop():
signal.Stop(sigs)
return
case sig := <-sigs:
log.Infof(context.Background(), "received signal %q, triggering certificate reload", sig)
if err := cm.LoadCertificates(); err != nil {
log.Warningf(context.Background(), "could not reload certificates: %v", err)
} else {
log.Info(context.Background(), "successfully reloaded certificates")
}
}
}
}()
}
// CACertPath returns the expected file path for the CA certificate.
func (cm *CertificateManager) CACertPath() string {
return filepath.Join(cm.certsDir, "ca"+certExtension)
}
// NodeCertPath returns the expected file path for the node certificate.
func (cm *CertificateManager) NodeCertPath() string {
return filepath.Join(cm.certsDir, "node"+certExtension)
}
// NodeKeyPath returns the expected file path for the node key.
func (cm *CertificateManager) NodeKeyPath() string {
return filepath.Join(cm.certsDir, "node"+keyExtension)
}
// ClientCertPath returns the expected file path for the user's certificate.
func (cm *CertificateManager) ClientCertPath(user string) string {
return filepath.Join(cm.certsDir, "client."+user+certExtension)
}
// ClientKeyPath returns the expected file path for the user's key.
func (cm *CertificateManager) ClientKeyPath(user string) string {
return filepath.Join(cm.certsDir, "client."+user+keyExtension)
}
// CACert returns the CA cert. May be nil.
// Callers should check for an internal Error field.
func (cm *CertificateManager) CACert() *CertInfo {
cm.mu.RLock()
defer cm.mu.RUnlock()
return cm.caCert
}
// checkCertIsValid returns an error if the passed cert is missing or has an error.
func checkCertIsValid(cert *CertInfo) error {
if cert == nil {
return errors.New("not found")
}
return cert.Error
}
// NodeCert returns the Node cert. May be nil.
// Callers should check for an internal Error field.
func (cm *CertificateManager) NodeCert() *CertInfo {
cm.mu.RLock()
defer cm.mu.RUnlock()
return cm.nodeCert
}
// ClientCerts returns the Client certs.
// Callers should check for internal Error fields.
func (cm *CertificateManager) ClientCerts() map[string]*CertInfo {
cm.mu.RLock()
defer cm.mu.RUnlock()
return cm.clientCerts
}
// LoadCertificates creates a CertificateLoader to load all certs and keys.
// Upon success, it swaps the existing certificates for the new ones.
func (cm *CertificateManager) LoadCertificates() error {
cl := NewCertificateLoader(cm.certsDir)
if err := cl.Load(); err != nil {
return errors.Wrapf(err, "problem loading certs directory %s", cm.certsDir)
}
var caCert, nodeCert *CertInfo
clientCerts := make(map[string]*CertInfo)
for _, ci := range cl.Certificates() {
switch ci.FileUsage {
case CAPem:
caCert = ci
case NodePem:
nodeCert = ci
case ClientPem:
clientCerts[ci.Name] = ci
}
}
cm.mu.Lock()
defer cm.mu.Unlock()
if cm.initialized {
// If we ran before, make sure we don't reload with missing/bad certificates.
if err := checkCertIsValid(caCert); checkCertIsValid(cm.caCert) == nil && err != nil {
return errors.Wrap(err, "reload would lose valid CA cert")
}
if err := checkCertIsValid(nodeCert); checkCertIsValid(cm.nodeCert) == nil && err != nil {
return errors.Wrap(err, "reload would lose valid node cert")
}
}
// Swap everything.
cm.caCert = caCert
cm.nodeCert = nodeCert
cm.clientCerts = clientCerts
cm.initialized = true
cm.serverConfig = nil
cm.clientConfig = nil
cm.updateMetricsLocked()
return nil
}
// updateMetricsLocked updates the values on the certificate metrics.
// The metrics may not exist (eg: in tests that build their own CertificateManager).
// If the corresponding certificate is missing or invalid (Error != nil), we reset the
// metric to zero.
// cm.mu must be held to protect the certificates. Metrics do their own atomicity.
func (cm *CertificateManager) updateMetricsLocked() {
// CA certificate expiration.
if cm.certMetrics.CAExpiration != nil {
if cm.caCert != nil && cm.caCert.Error == nil {
cm.certMetrics.CAExpiration.Update(cm.caCert.ExpirationTime.Unix())
} else {
cm.certMetrics.CAExpiration.Update(0)
}
}
// Node certificate expiration.
// TODO(marc): we need to examine the entire certificate chain here, if the CA cert
// used to sign the node cert expires sooner, then that is the expiration time to report.
if cm.certMetrics.NodeExpiration != nil {
if cm.nodeCert != nil && cm.nodeCert.Error == nil {
cm.certMetrics.NodeExpiration.Update(cm.nodeCert.ExpirationTime.Unix())
} else {
cm.certMetrics.NodeExpiration.Update(0)
}
}
}
// GetServerTLSConfig returns a server TLS config with a callback to fetch the
// latest TLS config. We still attempt to get the config to make sure
// the initial call has a valid config loaded.
func (cm *CertificateManager) GetServerTLSConfig() (*tls.Config, error) {
if _, err := cm.GetEmbeddedServerTLSConfig(nil); err != nil {
return nil, err
}
return &tls.Config{
GetConfigForClient: cm.GetEmbeddedServerTLSConfig,
}, nil
}
// GetEmbeddedServerTLSConfig returns the most up-to-date server tls.Config.
// This is the callback set in tls.Config.GetConfigForClient. We currently
// ignore the ClientHelloInfo object.
func (cm *CertificateManager) GetEmbeddedServerTLSConfig(
_ *tls.ClientHelloInfo,
) (*tls.Config, error) {
cm.mu.Lock()
defer cm.mu.Unlock()
if cm.serverConfig != nil {
return cm.serverConfig, nil
}
if err := checkCertIsValid(cm.caCert); err != nil {
return nil, errors.Wrap(err, "problem with CA certificate")
}
if err := checkCertIsValid(cm.nodeCert); err != nil {
return nil, errors.Wrap(err, "problem with node certificate")
}
cfg, err := newServerTLSConfig(
cm.nodeCert.FileContents,
cm.nodeCert.KeyFileContents,
cm.caCert.FileContents)
if err != nil {
return nil, err
}
cm.serverConfig = cfg
return cfg, nil
}
// getClientCertsLocked returns the client cert/key for the specified user,
// or an error if not found.
// cm.mu must be held.
func (cm *CertificateManager) getClientCertsLocked(user string) (*CertInfo, error) {
ci := cm.clientCerts[user]
if err := checkCertIsValid(ci); err != nil {
return nil, errors.Wrapf(err, "problem with client cert for user %s", user)
}
return ci, nil
}
// getNodeClientCertsLocked returns the client cert/key for the node user.
// cm.mu must be held.
func (cm *CertificateManager) getNodeClientCertsLocked() (*CertInfo, error) {
if err := checkCertIsValid(cm.nodeCert); err != nil {
return nil, errors.Wrap(err, "problem with node certificate")
}
return cm.nodeCert, nil
}
// GetClientTLSConfig returns the most up-to-date server tls.Config.
// Returns the dual-purpose node certs if user == NodeUser.
func (cm *CertificateManager) GetClientTLSConfig(user string) (*tls.Config, error) {
cm.mu.Lock()
defer cm.mu.Unlock()
// We always need the CA cert.
if err := checkCertIsValid(cm.caCert); err != nil {
return nil, errors.Wrap(err, "problem with CA certificate")
}
if user != NodeUser {
clientCert, err := cm.getClientCertsLocked(user)
if err != nil {
return nil, err
}
cfg, err := newClientTLSConfig(
clientCert.FileContents,
clientCert.KeyFileContents,
cm.caCert.FileContents)
if err != nil {
return nil, err
}
return cfg, nil
}
// We're the node user:
// Return the cache config if we have one.
if cm.clientConfig != nil {
return cm.clientConfig, nil
}
clientCert, err := cm.getNodeClientCertsLocked()
if err != nil {
return nil, err
}
cfg, err := newClientTLSConfig(
clientCert.FileContents,
clientCert.KeyFileContents,
cm.caCert.FileContents)
if err != nil {
return nil, err
}
// Cache the config.
cm.clientConfig = cfg
return cfg, nil
}
// GetClientCertPaths returns the paths to the client cert and key.
// Returns the node cert and key if user == NodeUser.
func (cm *CertificateManager) GetClientCertPaths(user string) (string, string, error) {
var clientCert *CertInfo
var err error
cm.mu.RLock()
defer cm.mu.RUnlock()
if user == NodeUser {
clientCert, err = cm.getNodeClientCertsLocked()
} else {
clientCert, err = cm.getClientCertsLocked(user)
}
if err != nil {
return "", "", err
}
return filepath.Join(cm.certsDir, clientCert.Filename),
filepath.Join(cm.certsDir, clientCert.KeyFilename),
nil
}
// GetCACertPath returns the path to the CA certificate.
func (cm *CertificateManager) GetCACertPath() (string, error) {
cm.mu.RLock()
defer cm.mu.RUnlock()
if err := checkCertIsValid(cm.caCert); err != nil {
return "", errors.Wrap(err, "problem with CA certificate")
}
return filepath.Join(cm.certsDir, cm.caCert.Filename), nil
}
// ListCertificates returns all loaded certificates, or an error if not yet initialized.
func (cm *CertificateManager) ListCertificates() ([]*CertInfo, error) {
cm.mu.RLock()
defer cm.mu.RUnlock()
if !cm.initialized {
return nil, errors.New("certificate manager has not been initialized")
}
ret := make([]*CertInfo, 0, 2+len(cm.clientCerts))
if cm.caCert != nil {
ret = append(ret, cm.caCert)
}
if cm.nodeCert != nil {
ret = append(ret, cm.nodeCert)
}
if cm.clientCerts != nil {
for _, cert := range cm.clientCerts {
ret = append(ret, cert)
}
}
return ret, nil
}