chrome/browser/chromeos/login/easy_unlock/easy_unlock_create_keys_operation.cc

   1 // Copyright 2014 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 "chrome/browser/chromeos/login/easy_unlock/easy_unlock_create_keys_operation.h"
   6
   7 #include <string>
   8
   9 #include "base/bind.h"
  10 #include "base/logging.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/strings/string_util.h"
  13 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h"
  14 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_types.h"
  15 #include "chromeos/cryptohome/homedir_methods.h"
  16 #include "chromeos/cryptohome/system_salt_getter.h"
  17 #include "chromeos/dbus/dbus_thread_manager.h"
  18 #include "chromeos/dbus/easy_unlock_client.h"
  19 #include "chromeos/login/auth/key.h"
  20 #include "components/proximity_auth/cryptauth/base64url.h"
  21 #include "crypto/encryptor.h"
  22 #include "crypto/random.h"
  23 #include "crypto/symmetric_key.h"
  24 #include "google_apis/gaia/gaia_auth_util.h"
  25 #include "third_party/cros_system_api/dbus/service_constants.h"
  26
  27 namespace chromeos {
  28
  29 namespace {
  30
  31 const int kUserKeyByteSize = 16;
  32 const int kSessionKeyByteSize = 16;
  33
  34 const int kEasyUnlockKeyRevision = 1;
  35 const int kEasyUnlockKeyPrivileges =
  36     cryptohome::PRIV_MOUNT | cryptohome::PRIV_ADD | cryptohome::PRIV_REMOVE;
  37
  38 }  // namespace
  39
  40 /////////////////////////////////////////////////////////////////////////////
  41 // EasyUnlockCreateKeysOperation::ChallengeCreator
  42
  43 class EasyUnlockCreateKeysOperation::ChallengeCreator {
  44  public:
  45   typedef base::Callback<void (bool success)> ChallengeCreatedCallback;
  46   ChallengeCreator(const std::string& user_key,
  47                    const std::string& session_key,
  48                    const std::string& tpm_pub_key,
  49                    EasyUnlockDeviceKeyData* device,
  50                    const ChallengeCreatedCallback& callback);
  51   ~ChallengeCreator();
  52
  53   void Start();
  54
  55   const std::string& user_key() const { return user_key_; }
  56
  57  private:
  58   void OnEcKeyPairGenerated(const std::string& ec_public_key,
  59                             const std::string& ec_private_key);
  60   void OnEskGenerated(const std::string& esk);
  61   void OnTPMPublicKeyWrapped(const std::string& wrapped_key);
  62
  63   void WrapTPMPublicKey();
  64   void GeneratePayload();
  65   void OnPayloadMessageGenerated(const std::string& payload_message);
  66   void OnPayloadGenerated(const std::string& payload);
  67
  68   void OnChallengeGenerated(const std::string& challenge);
  69
  70   const std::string user_key_;
  71   const std::string session_key_;
  72   const std::string tpm_pub_key_;
  73   std::string wrapped_tpm_pub_key_;
  74   EasyUnlockDeviceKeyData* device_;
  75   ChallengeCreatedCallback callback_;
  76
  77   std::string ec_public_key_;
  78   std::string esk_;
  79
  80   // Owned by DBusThreadManager
  81   chromeos::EasyUnlockClient* easy_unlock_client_;
  82
  83   base::WeakPtrFactory<ChallengeCreator> weak_ptr_factory_;
  84
  85   DISALLOW_COPY_AND_ASSIGN(ChallengeCreator);
  86 };
  87
  88 EasyUnlockCreateKeysOperation::ChallengeCreator::ChallengeCreator(
  89     const std::string& user_key,
  90     const std::string& session_key,
  91     const std::string& tpm_pub_key,
  92     EasyUnlockDeviceKeyData* device,
  93     const ChallengeCreatedCallback& callback)
  94     : user_key_(user_key),
  95       session_key_(session_key),
  96       tpm_pub_key_(tpm_pub_key),
  97       device_(device),
  98       callback_(callback),
  99       easy_unlock_client_(
 100           chromeos::DBusThreadManager::Get()->GetEasyUnlockClient()),
 101       weak_ptr_factory_(this) {
 102 }
 103
 104 EasyUnlockCreateKeysOperation::ChallengeCreator::~ChallengeCreator() {
 105 }
 106
 107 void EasyUnlockCreateKeysOperation::ChallengeCreator::Start() {
 108   easy_unlock_client_->GenerateEcP256KeyPair(
 109       base::Bind(&ChallengeCreator::OnEcKeyPairGenerated,
 110                  weak_ptr_factory_.GetWeakPtr()));
 111 }
 112
 113 void EasyUnlockCreateKeysOperation::ChallengeCreator::OnEcKeyPairGenerated(
 114     const std::string& ec_private_key,
 115     const std::string& ec_public_key) {
 116   if (ec_private_key.empty() || ec_public_key.empty()) {
 117     LOG(ERROR) << "Easy unlock failed to generate ec key pair.";
 118     callback_.Run(false);
 119     return;
 120   }
 121
 122   std::string device_pub_key;
 123   if (!proximity_auth::Base64UrlDecode(device_->public_key, &device_pub_key)) {
 124     LOG(ERROR) << "Easy unlock failed to decode device public key.";
 125     callback_.Run(false);
 126     return;
 127   }
 128
 129   ec_public_key_ = ec_public_key;
 130   easy_unlock_client_->PerformECDHKeyAgreement(
 131       ec_private_key,
 132       device_pub_key,
 133       base::Bind(&ChallengeCreator::OnEskGenerated,
 134                  weak_ptr_factory_.GetWeakPtr()));
 135 }
 136
 137 void EasyUnlockCreateKeysOperation::ChallengeCreator::OnEskGenerated(
 138     const std::string& esk) {
 139   if (esk.empty()) {
 140     LOG(ERROR) << "Easy unlock failed to generate challenge esk.";
 141     callback_.Run(false);
 142     return;
 143   }
 144
 145   esk_ = esk;
 146   WrapTPMPublicKey();
 147 }
 148
 149 void EasyUnlockCreateKeysOperation::ChallengeCreator::WrapTPMPublicKey() {
 150   easy_unlock_client_->WrapPublicKey(
 151       easy_unlock::kKeyAlgorithmRSA,
 152       tpm_pub_key_,
 153       base::Bind(&ChallengeCreator::OnTPMPublicKeyWrapped,
 154                  weak_ptr_factory_.GetWeakPtr()));
 155 }
 156
 157 void EasyUnlockCreateKeysOperation::ChallengeCreator::OnTPMPublicKeyWrapped(
 158     const std::string& wrapped_key) {
 159   if (wrapped_key.empty()) {
 160     LOG(ERROR) << "Unable to wrap RSA key";
 161     callback_.Run(false);
 162     return;
 163   }
 164   wrapped_tpm_pub_key_ = wrapped_key;
 165   GeneratePayload();
 166 }
 167
 168 void EasyUnlockCreateKeysOperation::ChallengeCreator::GeneratePayload() {
 169   // Work around to get HeaderAndBody bytes to use as challenge payload.
 170   EasyUnlockClient::CreateSecureMessageOptions options;
 171   options.key = esk_;
 172   options.verification_key_id = wrapped_tpm_pub_key_;
 173   options.encryption_type = easy_unlock::kEncryptionTypeAES256CBC;
 174   options.signature_type = easy_unlock::kSignatureTypeHMACSHA256;
 175
 176   easy_unlock_client_->CreateSecureMessage(
 177       session_key_,
 178       options,
 179       base::Bind(&ChallengeCreator::OnPayloadMessageGenerated,
 180                  weak_ptr_factory_.GetWeakPtr()));
 181 }
 182
 183 void
 184 EasyUnlockCreateKeysOperation::ChallengeCreator::OnPayloadMessageGenerated(
 185     const std::string& payload_message) {
 186   EasyUnlockClient::UnwrapSecureMessageOptions options;
 187   options.key = esk_;
 188   options.encryption_type = easy_unlock::kEncryptionTypeAES256CBC;
 189   options.signature_type = easy_unlock::kSignatureTypeHMACSHA256;
 190
 191   easy_unlock_client_->UnwrapSecureMessage(
 192       payload_message,
 193       options,
 194       base::Bind(&ChallengeCreator::OnPayloadGenerated,
 195                  weak_ptr_factory_.GetWeakPtr()));
 196 }
 197
 198 void EasyUnlockCreateKeysOperation::ChallengeCreator::OnPayloadGenerated(
 199     const std::string& payload) {
 200   if (payload.empty()) {
 201     LOG(ERROR) << "Easy unlock failed to generate challenge payload.";
 202     callback_.Run(false);
 203     return;
 204   }
 205
 206   EasyUnlockClient::CreateSecureMessageOptions options;
 207   options.key = esk_;
 208   options.decryption_key_id = ec_public_key_;
 209   options.encryption_type = easy_unlock::kEncryptionTypeAES256CBC;
 210   options.signature_type = easy_unlock::kSignatureTypeHMACSHA256;
 211
 212   easy_unlock_client_->CreateSecureMessage(
 213       payload,
 214       options,
 215       base::Bind(&ChallengeCreator::OnChallengeGenerated,
 216                  weak_ptr_factory_.GetWeakPtr()));
 217 }
 218
 219 void EasyUnlockCreateKeysOperation::ChallengeCreator::OnChallengeGenerated(
 220     const std::string& challenge) {
 221   if (challenge.empty()) {
 222     LOG(ERROR) << "Easy unlock failed to generate challenge.";
 223     callback_.Run(false);
 224     return;
 225   }
 226
 227   device_->challenge = challenge;
 228   callback_.Run(true);
 229 }
 230
 231 /////////////////////////////////////////////////////////////////////////////
 232 // EasyUnlockCreateKeysOperation
 233
 234 EasyUnlockCreateKeysOperation::EasyUnlockCreateKeysOperation(
 235     const UserContext& user_context,
 236     const std::string& tpm_public_key,
 237     const EasyUnlockDeviceKeyDataList& devices,
 238     const CreateKeysCallback& callback)
 239     : user_context_(user_context),
 240       tpm_public_key_(tpm_public_key),
 241       devices_(devices),
 242       callback_(callback),
 243       key_creation_index_(0),
 244       weak_ptr_factory_(this) {
 245   // Must have the secret and callback.
 246   DCHECK(!user_context_.GetKey()->GetSecret().empty());
 247   DCHECK(!callback_.is_null());
 248 }
 249
 250 EasyUnlockCreateKeysOperation::~EasyUnlockCreateKeysOperation() {
 251 }
 252
 253 void EasyUnlockCreateKeysOperation::Start() {
 254   key_creation_index_ = 0;
 255   CreateKeyForDeviceAtIndex(key_creation_index_);
 256 }
 257
 258 void EasyUnlockCreateKeysOperation::CreateKeyForDeviceAtIndex(size_t index) {
 259   DCHECK_GE(index, 0u);
 260   if (index == devices_.size()) {
 261     callback_.Run(true);
 262     return;
 263   }
 264
 265   std::string user_key;
 266   crypto::RandBytes(base::WriteInto(&user_key, kUserKeyByteSize + 1),
 267                     kUserKeyByteSize);
 268
 269   scoped_ptr<crypto::SymmetricKey> session_key(
 270       crypto::SymmetricKey::GenerateRandomKey(crypto::SymmetricKey::AES,
 271                                               kSessionKeyByteSize * 8));
 272
 273   std::string iv(kSessionKeyByteSize, ' ');
 274   crypto::Encryptor encryptor;
 275   if (!encryptor.Init(session_key.get(), crypto::Encryptor::CBC, iv)) {
 276     LOG(ERROR) << "Easy unlock failed to init encryptor for key creation.";
 277     callback_.Run(false);
 278     return;
 279   }
 280
 281   EasyUnlockDeviceKeyData* device = &devices_[index];
 282   if (!encryptor.Encrypt(user_key, &device->wrapped_secret)) {
 283     LOG(ERROR) << "Easy unlock failed to encrypt user key for key creation.";
 284     callback_.Run(false);
 285     return;
 286   }
 287
 288   std::string raw_session_key;
 289   session_key->GetRawKey(&raw_session_key);
 290
 291   challenge_creator_.reset(new ChallengeCreator(
 292       user_key,
 293       raw_session_key,
 294       tpm_public_key_,
 295       device,
 296       base::Bind(&EasyUnlockCreateKeysOperation::OnChallengeCreated,
 297                  weak_ptr_factory_.GetWeakPtr(),
 298                  index)));
 299   challenge_creator_->Start();
 300 }
 301
 302 void EasyUnlockCreateKeysOperation::OnChallengeCreated(size_t index,
 303                                                        bool success) {
 304   DCHECK_EQ(key_creation_index_, index);
 305
 306   if (!success) {
 307     LOG(ERROR) << "Easy unlock failed to create challenge for key creation.";
 308     callback_.Run(false);
 309     return;
 310   }
 311
 312   SystemSaltGetter::Get()->GetSystemSalt(
 313       base::Bind(&EasyUnlockCreateKeysOperation::OnGetSystemSalt,
 314                  weak_ptr_factory_.GetWeakPtr(),
 315                  index));
 316 }
 317
 318 void EasyUnlockCreateKeysOperation::OnGetSystemSalt(
 319     size_t index,
 320     const std::string& system_salt) {
 321   DCHECK_EQ(key_creation_index_, index);
 322   if (system_salt.empty()) {
 323     LOG(ERROR) << "Easy unlock failed to get system salt for key creation.";
 324     callback_.Run(false);
 325     return;
 326   }
 327
 328   Key user_key(challenge_creator_->user_key());
 329   user_key.Transform(Key::KEY_TYPE_SALTED_SHA256_TOP_HALF, system_salt);
 330
 331   EasyUnlockDeviceKeyData* device = &devices_[index];
 332   cryptohome::KeyDefinition key_def(
 333       user_key.GetSecret(),
 334       EasyUnlockKeyManager::GetKeyLabel(index),
 335       kEasyUnlockKeyPrivileges);
 336   key_def.revision = kEasyUnlockKeyRevision;
 337   key_def.provider_data.push_back(cryptohome::KeyDefinition::ProviderData(
 338       kEasyUnlockKeyMetaNameBluetoothAddress, device->bluetooth_address));
 339   key_def.provider_data.push_back(cryptohome::KeyDefinition::ProviderData(
 340       kEasyUnlockKeyMetaNamePsk, device->psk));
 341   key_def.provider_data.push_back(cryptohome::KeyDefinition::ProviderData(
 342       kEasyUnlockKeyMetaNamePubKey, device->public_key));
 343   key_def.provider_data.push_back(cryptohome::KeyDefinition::ProviderData(
 344       kEasyUnlockKeyMetaNameChallenge, device->challenge));
 345   key_def.provider_data.push_back(cryptohome::KeyDefinition::ProviderData(
 346       kEasyUnlockKeyMetaNameWrappedSecret, device->wrapped_secret));
 347
 348   // Add cryptohome key.
 349   std::string canonicalized =
 350       gaia::CanonicalizeEmail(user_context_.GetUserID());
 351   cryptohome::Identification id(canonicalized);
 352
 353   scoped_ptr<Key> auth_key(new Key(*user_context_.GetKey()));
 354   if (auth_key->GetKeyType() == Key::KEY_TYPE_PASSWORD_PLAIN)
 355     auth_key->Transform(Key::KEY_TYPE_SALTED_SHA256_TOP_HALF, system_salt);
 356
 357   cryptohome::Authorization auth(auth_key->GetSecret(), auth_key->GetLabel());
 358   cryptohome::HomedirMethods::GetInstance()->AddKeyEx(
 359       id,
 360       auth,
 361       key_def,
 362       true,  // clobber
 363       base::Bind(&EasyUnlockCreateKeysOperation::OnKeyCreated,
 364                  weak_ptr_factory_.GetWeakPtr(),
 365                  index,
 366                  user_key));
 367 }
 368
 369 void EasyUnlockCreateKeysOperation::OnKeyCreated(
 370     size_t index,
 371     const Key& user_key,
 372     bool success,
 373     cryptohome::MountError return_code) {
 374   DCHECK_EQ(key_creation_index_, index);
 375
 376   if (!success) {
 377     LOG(ERROR) << "Easy unlock failed to create key, code=" << return_code;
 378     callback_.Run(false);
 379     return;
 380   }
 381
 382   // If the key associated with the current context changed (i.e. in the case
 383   // the current signin flow was Easy signin), update the user context.
 384   if (user_context_.GetAuthFlow() == UserContext::AUTH_FLOW_EASY_UNLOCK &&
 385       user_context_.GetKey()->GetLabel() ==
 386           EasyUnlockKeyManager::GetKeyLabel(key_creation_index_)) {
 387     user_context_.SetKey(user_key);
 388   }
 389
 390   ++key_creation_index_;
 391   CreateKeyForDeviceAtIndex(key_creation_index_);
 392 }
 393
 394 }  // namespace chromeos