chromeos/cert_loader.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chromeos/cert_loader.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/chromeos/chromeos_version.h"
  10 #include "base/message_loop/message_loop_proxy.h"
  11 #include "base/observer_list.h"
  12 #include "base/sequenced_task_runner.h"
  13 #include "base/strings/string_number_conversions.h"
  14 #include "base/task_runner_util.h"
  15 #include "base/threading/worker_pool.h"
  16 #include "chromeos/dbus/cryptohome_client.h"
  17 #include "chromeos/dbus/dbus_thread_manager.h"
  18 #include "crypto/encryptor.h"
  19 #include "crypto/nss_util.h"
  20 #include "crypto/sha2.h"
  21 #include "crypto/symmetric_key.h"
  22 #include "net/cert/nss_cert_database.h"
  23
  24 namespace chromeos {
  25
  26 namespace {
  27
  28 const int64 kInitialRequestDelayMs = 100;
  29 const int64 kMaxRequestDelayMs = 300000; // 5 minutes
  30
  31 // Calculates the delay before running next attempt to initiatialize the TPM
  32 // token, if |last_delay| was the last or initial delay.
  33 base::TimeDelta GetNextRequestDelayMs(base::TimeDelta last_delay) {
  34   // This implements an exponential backoff, as we don't know in which order of
  35   // magnitude the TPM token changes it's state.
  36   base::TimeDelta next_delay = last_delay * 2;
  37
  38   // Cap the delay to prevent an overflow. This threshold is arbitrarily chosen.
  39   const base::TimeDelta max_delay =
  40       base::TimeDelta::FromMilliseconds(kMaxRequestDelayMs);
  41   if (next_delay > max_delay)
  42     next_delay = max_delay;
  43   return next_delay;
  44 }
  45
  46 void LoadNSSCertificates(net::CertificateList* cert_list) {
  47   net::NSSCertDatabase::GetInstance()->ListCerts(cert_list);
  48 }
  49
  50 void CallOpenPersistentNSSDB() {
  51   // Called from crypto_task_runner_.
  52   VLOG(1) << "CallOpenPersistentNSSDB";
  53
  54   // Ensure we've opened the user's key/certificate database.
  55   if (base::chromeos::IsRunningOnChromeOS())
  56     crypto::OpenPersistentNSSDB();
  57   crypto::EnableTPMTokenForNSS();
  58 }
  59
  60 }  // namespace
  61
  62 static CertLoader* g_cert_loader = NULL;
  63
  64 // static
  65 void CertLoader::Initialize() {
  66   CHECK(!g_cert_loader);
  67   g_cert_loader = new CertLoader();
  68 }
  69
  70 // static
  71 void CertLoader::Shutdown() {
  72   CHECK(g_cert_loader);
  73   delete g_cert_loader;
  74   g_cert_loader = NULL;
  75 }
  76
  77 // static
  78 CertLoader* CertLoader::Get() {
  79   CHECK(g_cert_loader) << "CertLoader::Get() called before Initialize()";
  80   return g_cert_loader;
  81 }
  82
  83 // static
  84 bool CertLoader::IsInitialized() {
  85   return g_cert_loader;
  86 }
  87
  88 CertLoader::CertLoader()
  89     : initialize_tpm_for_test_(false),
  90       certificates_requested_(false),
  91       certificates_loaded_(false),
  92       certificates_update_required_(false),
  93       certificates_update_running_(false),
  94       tpm_token_state_(TPM_STATE_UNKNOWN),
  95       tpm_request_delay_(
  96           base::TimeDelta::FromMilliseconds(kInitialRequestDelayMs)),
  97       initialize_token_factory_(this),
  98       update_certificates_factory_(this) {
  99   if (LoginState::IsInitialized())
 100     LoginState::Get()->AddObserver(this);
 101 }
 102
 103 void CertLoader::InitializeTPMForTest() {
 104   initialize_tpm_for_test_ = true;
 105 }
 106
 107 void CertLoader::SetCryptoTaskRunner(
 108     const scoped_refptr<base::SequencedTaskRunner>& crypto_task_runner) {
 109   crypto_task_runner_ = crypto_task_runner;
 110   MaybeRequestCertificates();
 111 }
 112
 113 void CertLoader::SetSlowTaskRunnerForTest(
 114     const scoped_refptr<base::TaskRunner>& task_runner) {
 115   slow_task_runner_for_test_ = task_runner;
 116 }
 117
 118 CertLoader::~CertLoader() {
 119   net::CertDatabase::GetInstance()->RemoveObserver(this);
 120   if (LoginState::IsInitialized())
 121     LoginState::Get()->RemoveObserver(this);
 122 }
 123
 124 void CertLoader::AddObserver(CertLoader::Observer* observer) {
 125   observers_.AddObserver(observer);
 126 }
 127
 128 void CertLoader::RemoveObserver(CertLoader::Observer* observer) {
 129   observers_.RemoveObserver(observer);
 130 }
 131
 132 bool CertLoader::CertificatesLoading() const {
 133   return certificates_requested_ && !certificates_loaded_;
 134 }
 135
 136 bool CertLoader::IsHardwareBacked() const {
 137   return !tpm_token_name_.empty();
 138 }
 139
 140 void CertLoader::MaybeRequestCertificates() {
 141   CHECK(thread_checker_.CalledOnValidThread());
 142
 143   // This is the entry point to the TPM token initialization process,
 144   // which we should do at most once.
 145   if (certificates_requested_ || !crypto_task_runner_.get())
 146     return;
 147
 148   if (!LoginState::IsInitialized())
 149     return;
 150
 151   bool request_certificates = LoginState::Get()->IsUserLoggedIn() ||
 152       LoginState::Get()->IsInSafeMode();
 153
 154   VLOG(1) << "RequestCertificates: " << request_certificates;
 155   if (!request_certificates)
 156     return;
 157
 158   certificates_requested_ = true;
 159
 160   // Ensure we only initialize the TPM token once.
 161   DCHECK_EQ(tpm_token_state_, TPM_STATE_UNKNOWN);
 162   if (!initialize_tpm_for_test_ && !base::chromeos::IsRunningOnChromeOS())
 163     tpm_token_state_ = TPM_DISABLED;
 164
 165   // Treat TPM as disabled for guest users since they do not store certs.
 166   if (LoginState::Get()->IsGuestUser())
 167     tpm_token_state_ = TPM_DISABLED;
 168
 169   InitializeTokenAndLoadCertificates();
 170 }
 171
 172 void CertLoader::InitializeTokenAndLoadCertificates() {
 173   CHECK(thread_checker_.CalledOnValidThread());
 174   VLOG(1) << "InitializeTokenAndLoadCertificates: " << tpm_token_state_;
 175
 176   switch (tpm_token_state_) {
 177     case TPM_STATE_UNKNOWN: {
 178       crypto_task_runner_->PostTaskAndReply(
 179           FROM_HERE,
 180           base::Bind(&CallOpenPersistentNSSDB),
 181           base::Bind(&CertLoader::OnPersistentNSSDBOpened,
 182                      initialize_token_factory_.GetWeakPtr()));
 183       return;
 184     }
 185     case TPM_DB_OPENED: {
 186       DBusThreadManager::Get()->GetCryptohomeClient()->TpmIsEnabled(
 187           base::Bind(&CertLoader::OnTpmIsEnabled,
 188                      initialize_token_factory_.GetWeakPtr()));
 189       return;
 190     }
 191     case TPM_DISABLED: {
 192       // TPM is disabled, so proceed with empty tpm token name.
 193       StartLoadCertificates();
 194       return;
 195     }
 196     case TPM_ENABLED: {
 197       DBusThreadManager::Get()->GetCryptohomeClient()->Pkcs11IsTpmTokenReady(
 198           base::Bind(&CertLoader::OnPkcs11IsTpmTokenReady,
 199                      initialize_token_factory_.GetWeakPtr()));
 200       return;
 201     }
 202     case TPM_TOKEN_READY: {
 203       // Retrieve token_name_ and user_pin_ here since they will never change
 204       // and CryptohomeClient calls are not thread safe.
 205       DBusThreadManager::Get()->GetCryptohomeClient()->Pkcs11GetTpmTokenInfo(
 206           base::Bind(&CertLoader::OnPkcs11GetTpmTokenInfo,
 207                      initialize_token_factory_.GetWeakPtr()));
 208       return;
 209     }
 210     case TPM_TOKEN_INFO_RECEIVED: {
 211       base::PostTaskAndReplyWithResult(
 212           crypto_task_runner_.get(),
 213           FROM_HERE,
 214           base::Bind(
 215               &crypto::InitializeTPMToken, tpm_token_name_, tpm_user_pin_),
 216           base::Bind(&CertLoader::OnTPMTokenInitialized,
 217                      initialize_token_factory_.GetWeakPtr()));
 218       return;
 219     }
 220     case TPM_TOKEN_INITIALIZED: {
 221       StartLoadCertificates();
 222       return;
 223     }
 224   }
 225 }
 226
 227 void CertLoader::RetryTokenInitializationLater() {
 228   CHECK(thread_checker_.CalledOnValidThread());
 229   LOG(WARNING) << "Retry token initialization later.";
 230   base::MessageLoop::current()->PostDelayedTask(
 231       FROM_HERE,
 232       base::Bind(&CertLoader::InitializeTokenAndLoadCertificates,
 233                  initialize_token_factory_.GetWeakPtr()),
 234       tpm_request_delay_);
 235   tpm_request_delay_ = GetNextRequestDelayMs(tpm_request_delay_);
 236 }
 237
 238 void CertLoader::OnPersistentNSSDBOpened() {
 239   VLOG(1) << "PersistentNSSDBOpened";
 240   tpm_token_state_ = TPM_DB_OPENED;
 241   InitializeTokenAndLoadCertificates();
 242 }
 243
 244 // This is copied from chrome/common/net/x509_certificate_model_nss.cc.
 245 // For background see this discussion on dev-tech-crypto.lists.mozilla.org:
 246 // http://web.archiveorange.com/archive/v/6JJW7E40sypfZGtbkzxX
 247 //
 248 // NOTE: This function relies on the convention that the same PKCS#11 ID
 249 // is shared between a certificate and its associated private and public
 250 // keys.  I tried to implement this with PK11_GetLowLevelKeyIDForCert(),
 251 // but that always returns NULL on Chrome OS for me.
 252
 253 // static
 254 std::string CertLoader::GetPkcs11IdForCert(const net::X509Certificate& cert) {
 255   CERTCertificateStr* cert_handle = cert.os_cert_handle();
 256   SECKEYPrivateKey *priv_key =
 257       PK11_FindKeyByAnyCert(cert_handle, NULL /* wincx */);
 258   if (!priv_key)
 259     return std::string();
 260
 261   // Get the CKA_ID attribute for a key.
 262   SECItem* sec_item = PK11_GetLowLevelKeyIDForPrivateKey(priv_key);
 263   std::string pkcs11_id;
 264   if (sec_item) {
 265     pkcs11_id = base::HexEncode(sec_item->data, sec_item->len);
 266     SECITEM_FreeItem(sec_item, PR_TRUE);
 267   }
 268   SECKEY_DestroyPrivateKey(priv_key);
 269
 270   return pkcs11_id;
 271 }
 272
 273 void CertLoader::OnTpmIsEnabled(DBusMethodCallStatus call_status,
 274                                 bool tpm_is_enabled) {
 275   VLOG(1) << "OnTpmIsEnabled: " << tpm_is_enabled;
 276
 277   if (call_status == DBUS_METHOD_CALL_SUCCESS && tpm_is_enabled)
 278     tpm_token_state_ = TPM_ENABLED;
 279   else
 280     tpm_token_state_ = TPM_DISABLED;
 281
 282   InitializeTokenAndLoadCertificates();
 283 }
 284
 285 void CertLoader::OnPkcs11IsTpmTokenReady(DBusMethodCallStatus call_status,
 286                                          bool is_tpm_token_ready) {
 287   VLOG(1) << "OnPkcs11IsTpmTokenReady: " << is_tpm_token_ready;
 288
 289   if (call_status == DBUS_METHOD_CALL_FAILURE || !is_tpm_token_ready) {
 290     RetryTokenInitializationLater();
 291     return;
 292   }
 293
 294   tpm_token_state_ = TPM_TOKEN_READY;
 295   InitializeTokenAndLoadCertificates();
 296 }
 297
 298 void CertLoader::OnPkcs11GetTpmTokenInfo(DBusMethodCallStatus call_status,
 299                                          const std::string& token_name,
 300                                          const std::string& user_pin) {
 301   VLOG(1) << "OnPkcs11GetTpmTokenInfo: " << token_name;
 302
 303   if (call_status == DBUS_METHOD_CALL_FAILURE) {
 304     RetryTokenInitializationLater();
 305     return;
 306   }
 307
 308   tpm_token_name_ = token_name;
 309   // TODO(stevenjb): The network code expects a slot ID, not a label. See
 310   // crbug.com/201101. For now, use a hard coded, well known slot instead.
 311   const char kHardcodedTpmSlot[] = "0";
 312   tpm_token_slot_ = kHardcodedTpmSlot;
 313   tpm_user_pin_ = user_pin;
 314   tpm_token_state_ = TPM_TOKEN_INFO_RECEIVED;
 315
 316   InitializeTokenAndLoadCertificates();
 317 }
 318
 319 void CertLoader::OnTPMTokenInitialized(bool success) {
 320   VLOG(1) << "OnTPMTokenInitialized: " << success;
 321   if (!success) {
 322     RetryTokenInitializationLater();
 323     return;
 324   }
 325   tpm_token_state_ = TPM_TOKEN_INITIALIZED;
 326   InitializeTokenAndLoadCertificates();
 327 }
 328
 329 void CertLoader::StartLoadCertificates() {
 330   DCHECK(!certificates_loaded_ && !certificates_update_running_);
 331   net::CertDatabase::GetInstance()->AddObserver(this);
 332   LoadCertificates();
 333 }
 334
 335 void CertLoader::LoadCertificates() {
 336   CHECK(thread_checker_.CalledOnValidThread());
 337   VLOG(1) << "LoadCertificates: " << certificates_update_running_;
 338
 339   if (certificates_update_running_) {
 340     certificates_update_required_ = true;
 341     return;
 342   }
 343
 344   net::CertificateList* cert_list = new net::CertificateList;
 345   certificates_update_running_ = true;
 346   certificates_update_required_ = false;
 347
 348   base::TaskRunner* task_runner = slow_task_runner_for_test_.get();
 349   if (!task_runner)
 350     task_runner = base::WorkerPool::GetTaskRunner(true /* task is slow */);
 351   task_runner->PostTaskAndReply(
 352       FROM_HERE,
 353       base::Bind(LoadNSSCertificates, cert_list),
 354       base::Bind(&CertLoader::UpdateCertificates,
 355                  update_certificates_factory_.GetWeakPtr(),
 356                  base::Owned(cert_list)));
 357 }
 358
 359 void CertLoader::UpdateCertificates(net::CertificateList* cert_list) {
 360   CHECK(thread_checker_.CalledOnValidThread());
 361   DCHECK(certificates_update_running_);
 362   VLOG(1) << "UpdateCertificates: " << cert_list->size();
 363
 364   // Ignore any existing certificates.
 365   cert_list_.swap(*cert_list);
 366
 367   bool initial_load = !certificates_loaded_;
 368   certificates_loaded_ = true;
 369   NotifyCertificatesLoaded(initial_load);
 370
 371   certificates_update_running_ = false;
 372   if (certificates_update_required_)
 373     LoadCertificates();
 374 }
 375
 376 void CertLoader::NotifyCertificatesLoaded(bool initial_load) {
 377   FOR_EACH_OBSERVER(Observer, observers_,
 378                     OnCertificatesLoaded(cert_list_, initial_load));
 379 }
 380
 381 void CertLoader::OnCertTrustChanged(const net::X509Certificate* cert) {
 382 }
 383
 384 void CertLoader::OnCertAdded(const net::X509Certificate* cert) {
 385   VLOG(1) << "OnCertAdded";
 386   LoadCertificates();
 387 }
 388
 389 void CertLoader::OnCertRemoved(const net::X509Certificate* cert) {
 390   VLOG(1) << "OnCertRemoved";
 391   LoadCertificates();
 392 }
 393
 394 void CertLoader::LoggedInStateChanged() {
 395   VLOG(1) << "LoggedInStateChanged";
 396   MaybeRequestCertificates();
 397 }
 398
 399 }  // namespace chromeos