remoting/host/win/elevated_controller.cc

   1 // Copyright (c) 2012 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 "remoting/host/win/elevated_controller.h"
   6
   7 #include "base/file_util.h"
   8 #include "base/file_version_info.h"
   9 #include "base/json/json_reader.h"
  10 #include "base/json/json_writer.h"
  11 #include "base/logging.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/path_service.h"
  14 #include "base/process/memory.h"
  15 #include "base/strings/utf_string_conversions.h"
  16 #include "base/values.h"
  17 #include "base/win/scoped_handle.h"
  18 #include "remoting/host/branding.h"
  19 #include "remoting/host/usage_stats_consent.h"
  20 #include "remoting/host/verify_config_window_win.h"
  21 #include "remoting/host/win/core_resource.h"
  22 #include "remoting/host/win/security_descriptor.h"
  23
  24 namespace remoting {
  25
  26 namespace {
  27
  28 // The maximum size of the configuration file. "1MB ought to be enough" for any
  29 // reasonable configuration we will ever need. 1MB is low enough to make
  30 // the probability of out of memory situation fairly low. OOM is still possible
  31 // and we will crash if it occurs.
  32 const size_t kMaxConfigFileSize = 1024 * 1024;
  33
  34 // The host configuration file name.
  35 const base::FilePath::CharType kConfigFileName[] = FILE_PATH_LITERAL("host.json");
  36
  37 // The unprivileged configuration file name.
  38 const base::FilePath::CharType kUnprivilegedConfigFileName[] =
  39     FILE_PATH_LITERAL("host_unprivileged.json");
  40
  41 // The extension for the temporary file.
  42 const base::FilePath::CharType kTempFileExtension[] = FILE_PATH_LITERAL("json~");
  43
  44 // The host configuration file security descriptor that enables full access to
  45 // Local System and built-in administrators only.
  46 const char kConfigFileSecurityDescriptor[] =
  47     "O:BAG:BAD:(A;;GA;;;SY)(A;;GA;;;BA)";
  48
  49 const char kUnprivilegedConfigFileSecurityDescriptor[] =
  50     "O:BAG:BAD:(A;;GA;;;SY)(A;;GA;;;BA)(A;;GR;;;AU)";
  51
  52 // Configuration keys.
  53 const char kHostId[] = "host_id";
  54 const char kXmppLogin[] = "xmpp_login";
  55 const char kHostOwner[] = "host_owner";
  56 const char kHostSecretHash[] = "host_secret_hash";
  57
  58 // The configuration keys that cannot be specified in UpdateConfig().
  59 const char* const kReadonlyKeys[] = { kHostId, kHostOwner, kXmppLogin };
  60
  61 // The configuration keys whose values may be read by GetConfig().
  62 const char* const kUnprivilegedConfigKeys[] = { kHostId, kXmppLogin };
  63
  64 // Determines if the client runs in the security context that allows performing
  65 // administrative tasks (i.e. the user belongs to the adminstrators group and
  66 // the client runs elevated).
  67 bool IsClientAdmin() {
  68   HRESULT hr = CoImpersonateClient();
  69   if (FAILED(hr)) {
  70     return false;
  71   }
  72
  73   SID_IDENTIFIER_AUTHORITY nt_authority = SECURITY_NT_AUTHORITY;
  74   PSID administrators_group = NULL;
  75   BOOL result = AllocateAndInitializeSid(&nt_authority,
  76                                          2,
  77                                          SECURITY_BUILTIN_DOMAIN_RID,
  78                                          DOMAIN_ALIAS_RID_ADMINS,
  79                                          0, 0, 0, 0, 0, 0,
  80                                          &administrators_group);
  81   if (result) {
  82     if (!CheckTokenMembership(NULL, administrators_group, &result)) {
  83       result = false;
  84     }
  85     FreeSid(administrators_group);
  86   }
  87
  88   hr = CoRevertToSelf();
  89   CHECK(SUCCEEDED(hr));
  90
  91   return !!result;
  92 }
  93
  94 // Reads and parses the configuration file up to |kMaxConfigFileSize| in
  95 // size.
  96 HRESULT ReadConfig(const base::FilePath& filename,
  97                    scoped_ptr<base::DictionaryValue>* config_out) {
  98
  99   // Read raw data from the configuration file.
 100   base::win::ScopedHandle file(
 101       CreateFileW(filename.value().c_str(),
 102                   GENERIC_READ,
 103                   FILE_SHARE_READ | FILE_SHARE_WRITE,
 104                   NULL,
 105                   OPEN_EXISTING,
 106                   FILE_FLAG_SEQUENTIAL_SCAN,
 107                   NULL));
 108
 109   if (!file.IsValid()) {
 110     DWORD error = GetLastError();
 111     PLOG(ERROR) << "Failed to open '" << filename.value() << "'";
 112     return HRESULT_FROM_WIN32(error);
 113   }
 114
 115   scoped_ptr<char[]> buffer(new char[kMaxConfigFileSize]);
 116   DWORD size = kMaxConfigFileSize;
 117   if (!::ReadFile(file, &buffer[0], size, &size, NULL)) {
 118     DWORD error = GetLastError();
 119     PLOG(ERROR) << "Failed to read '" << filename.value() << "'";
 120     return HRESULT_FROM_WIN32(error);
 121   }
 122
 123   // Parse the JSON configuration, expecting it to contain a dictionary.
 124   std::string file_content(buffer.get(), size);
 125   scoped_ptr<base::Value> value(
 126       base::JSONReader::Read(file_content, base::JSON_ALLOW_TRAILING_COMMAS));
 127
 128   base::DictionaryValue* dictionary;
 129   if (value.get() == NULL || !value->GetAsDictionary(&dictionary)) {
 130     LOG(ERROR) << "Failed to read '" << filename.value() << "'.";
 131     return E_FAIL;
 132   }
 133
 134   value.release();
 135   config_out->reset(dictionary);
 136   return S_OK;
 137 }
 138
 139 base::FilePath GetTempLocationFor(const base::FilePath& filename) {
 140   return filename.ReplaceExtension(kTempFileExtension);
 141 }
 142
 143 // Writes a config file to a temporary location.
 144 HRESULT WriteConfigFileToTemp(const base::FilePath& filename,
 145                               const char* security_descriptor,
 146                               const char* content,
 147                               size_t length) {
 148   // Create the security descriptor for the configuration file.
 149   ScopedSd sd = ConvertSddlToSd(security_descriptor);
 150   if (!sd) {
 151     DWORD error = GetLastError();
 152     PLOG(ERROR)
 153         << "Failed to create a security descriptor for the configuration file";
 154     return HRESULT_FROM_WIN32(error);
 155   }
 156
 157   SECURITY_ATTRIBUTES security_attributes = {0};
 158   security_attributes.nLength = sizeof(security_attributes);
 159   security_attributes.lpSecurityDescriptor = sd.get();
 160   security_attributes.bInheritHandle = FALSE;
 161
 162   // Create a temporary file and write configuration to it.
 163   base::FilePath tempname = GetTempLocationFor(filename);
 164   base::win::ScopedHandle file(
 165       CreateFileW(tempname.value().c_str(),
 166                   GENERIC_WRITE,
 167                   0,
 168                   &security_attributes,
 169                   CREATE_ALWAYS,
 170                   FILE_FLAG_SEQUENTIAL_SCAN,
 171                   NULL));
 172
 173   if (!file.IsValid()) {
 174     DWORD error = GetLastError();
 175     PLOG(ERROR) << "Failed to create '" << filename.value() << "'";
 176     return HRESULT_FROM_WIN32(error);
 177   }
 178
 179   DWORD written;
 180   if (!WriteFile(file, content, static_cast<DWORD>(length), &written, NULL)) {
 181     DWORD error = GetLastError();
 182     PLOG(ERROR) << "Failed to write to '" << filename.value() << "'";
 183     return HRESULT_FROM_WIN32(error);
 184   }
 185
 186   return S_OK;
 187 }
 188
 189 // Moves a config file from its temporary location to its permanent location.
 190 HRESULT MoveConfigFileFromTemp(const base::FilePath& filename) {
 191   // Now that the configuration is stored successfully replace the actual
 192   // configuration file.
 193   base::FilePath tempname = GetTempLocationFor(filename);
 194   if (!MoveFileExW(tempname.value().c_str(),
 195                    filename.value().c_str(),
 196                    MOVEFILE_REPLACE_EXISTING)) {
 197       DWORD error = GetLastError();
 198       PLOG(ERROR) << "Failed to rename '" << tempname.value() << "' to '"
 199                   << filename.value() << "'";
 200       return HRESULT_FROM_WIN32(error);
 201   }
 202
 203   return S_OK;
 204 }
 205
 206 // Writes the configuration file up to |kMaxConfigFileSize| in size.
 207 HRESULT WriteConfig(const char* content, size_t length, HWND owner_window) {
 208   if (length > kMaxConfigFileSize) {
 209       return E_FAIL;
 210   }
 211
 212   // Extract the configuration data that the user will verify.
 213   scoped_ptr<base::Value> config_value(base::JSONReader::Read(content));
 214   if (!config_value.get()) {
 215     return E_FAIL;
 216   }
 217   base::DictionaryValue* config_dict = NULL;
 218   if (!config_value->GetAsDictionary(&config_dict)) {
 219     return E_FAIL;
 220   }
 221   std::string email;
 222   if (!config_dict->GetString(kHostOwner, &email)) {
 223     if (!config_dict->GetString(kXmppLogin, &email)) {
 224       return E_FAIL;
 225     }
 226   }
 227   std::string host_id, host_secret_hash;
 228   if (!config_dict->GetString(kHostId, &host_id) ||
 229       !config_dict->GetString(kHostSecretHash, &host_secret_hash)) {
 230     return E_FAIL;
 231   }
 232
 233   // Ask the user to verify the configuration (unless the client is admin
 234   // already).
 235   if (!IsClientAdmin()) {
 236     remoting::VerifyConfigWindowWin verify_win(email, host_id,
 237                                                host_secret_hash);
 238     DWORD error = verify_win.DoModal(owner_window);
 239     if (error != ERROR_SUCCESS) {
 240       return HRESULT_FROM_WIN32(error);
 241     }
 242   }
 243
 244   // Extract the unprivileged fields from the configuration.
 245   base::DictionaryValue unprivileged_config_dict;
 246   for (int i = 0; i < arraysize(kUnprivilegedConfigKeys); ++i) {
 247     const char* key = kUnprivilegedConfigKeys[i];
 248     base::string16 value;
 249     if (config_dict->GetString(key, &value)) {
 250       unprivileged_config_dict.SetString(key, value);
 251     }
 252   }
 253   std::string unprivileged_config_str;
 254   base::JSONWriter::Write(&unprivileged_config_dict, &unprivileged_config_str);
 255
 256   // Write the full configuration file to a temporary location.
 257   base::FilePath full_config_file_path =
 258       remoting::GetConfigDir().Append(kConfigFileName);
 259   HRESULT hr = WriteConfigFileToTemp(full_config_file_path,
 260                                      kConfigFileSecurityDescriptor,
 261                                      content,
 262                                      length);
 263   if (FAILED(hr)) {
 264     return hr;
 265   }
 266
 267   // Write the unprivileged configuration file to a temporary location.
 268   base::FilePath unprivileged_config_file_path =
 269       remoting::GetConfigDir().Append(kUnprivilegedConfigFileName);
 270   hr = WriteConfigFileToTemp(unprivileged_config_file_path,
 271                              kUnprivilegedConfigFileSecurityDescriptor,
 272                              unprivileged_config_str.data(),
 273                              unprivileged_config_str.size());
 274   if (FAILED(hr)) {
 275     return hr;
 276   }
 277
 278   // Move the full configuration file to its permanent location.
 279   hr = MoveConfigFileFromTemp(full_config_file_path);
 280   if (FAILED(hr)) {
 281     return hr;
 282   }
 283
 284   // Move the unprivileged configuration file to its permanent location.
 285   hr = MoveConfigFileFromTemp(unprivileged_config_file_path);
 286   if (FAILED(hr)) {
 287     return hr;
 288   }
 289
 290   return S_OK;
 291 }
 292
 293 } // namespace
 294
 295 ElevatedController::ElevatedController() : owner_window_(NULL) {
 296 }
 297
 298 HRESULT ElevatedController::FinalConstruct() {
 299   return S_OK;
 300 }
 301
 302 void ElevatedController::FinalRelease() {
 303 }
 304
 305 STDMETHODIMP ElevatedController::GetConfig(BSTR* config_out) {
 306   base::FilePath config_dir = remoting::GetConfigDir();
 307
 308   // Read the unprivileged part of host configuration.
 309   scoped_ptr<base::DictionaryValue> config;
 310   HRESULT hr = ReadConfig(config_dir.Append(kUnprivilegedConfigFileName),
 311                           &config);
 312   if (FAILED(hr)) {
 313     return hr;
 314   }
 315
 316   // Convert the config back to a string and return it to the caller.
 317   std::string file_content;
 318   base::JSONWriter::Write(config.get(), &file_content);
 319
 320   *config_out = ::SysAllocString(base::UTF8ToUTF16(file_content).c_str());
 321   if (config_out == NULL) {
 322     return E_OUTOFMEMORY;
 323   }
 324
 325   return S_OK;
 326 }
 327
 328 STDMETHODIMP ElevatedController::GetVersion(BSTR* version_out) {
 329   // Report the product version number of the daemon controller binary as
 330   // the host version.
 331   HMODULE binary = base::GetModuleFromAddress(
 332       reinterpret_cast<void*>(&ReadConfig));
 333   scoped_ptr<FileVersionInfo> version_info(
 334       FileVersionInfo::CreateFileVersionInfoForModule(binary));
 335
 336   base::string16 version;
 337   if (version_info.get()) {
 338     version = version_info->product_version();
 339   }
 340
 341   *version_out = ::SysAllocString(version.c_str());
 342   if (version_out == NULL) {
 343     return E_OUTOFMEMORY;
 344   }
 345
 346   return S_OK;
 347 }
 348
 349 STDMETHODIMP ElevatedController::SetConfig(BSTR config) {
 350   // Determine the config directory path and create it if necessary.
 351   base::FilePath config_dir = remoting::GetConfigDir();
 352   if (!base::CreateDirectory(config_dir)) {
 353     return HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED);
 354   }
 355
 356   std::string file_content = base::UTF16ToUTF8(
 357     base::string16(static_cast<base::char16*>(config), ::SysStringLen(config)));
 358
 359   return WriteConfig(file_content.c_str(), file_content.size(), owner_window_);
 360 }
 361
 362 STDMETHODIMP ElevatedController::SetOwnerWindow(LONG_PTR window_handle) {
 363   owner_window_ = reinterpret_cast<HWND>(window_handle);
 364   return S_OK;
 365 }
 366
 367 STDMETHODIMP ElevatedController::StartDaemon() {
 368   ScopedScHandle service;
 369   HRESULT hr = OpenService(&service);
 370   if (FAILED(hr)) {
 371     return hr;
 372   }
 373
 374   // Change the service start type to 'auto'.
 375   if (!::ChangeServiceConfigW(service,
 376                               SERVICE_NO_CHANGE,
 377                               SERVICE_AUTO_START,
 378                               SERVICE_NO_CHANGE,
 379                               NULL,
 380                               NULL,
 381                               NULL,
 382                               NULL,
 383                               NULL,
 384                               NULL,
 385                               NULL)) {
 386     DWORD error = GetLastError();
 387     PLOG(ERROR) << "Failed to change the '" << kWindowsServiceName
 388                 << "'service start type to 'auto'";
 389     return HRESULT_FROM_WIN32(error);
 390   }
 391
 392   // Start the service.
 393   if (!StartService(service, 0, NULL)) {
 394     DWORD error = GetLastError();
 395     if (error != ERROR_SERVICE_ALREADY_RUNNING) {
 396       PLOG(ERROR) << "Failed to start the '" << kWindowsServiceName
 397                   << "'service";
 398
 399       return HRESULT_FROM_WIN32(error);
 400     }
 401   }
 402
 403   return S_OK;
 404 }
 405
 406 STDMETHODIMP ElevatedController::StopDaemon() {
 407   ScopedScHandle service;
 408   HRESULT hr = OpenService(&service);
 409   if (FAILED(hr)) {
 410     return hr;
 411   }
 412
 413   // Change the service start type to 'manual'.
 414   if (!::ChangeServiceConfigW(service,
 415                               SERVICE_NO_CHANGE,
 416                               SERVICE_DEMAND_START,
 417                               SERVICE_NO_CHANGE,
 418                               NULL,
 419                               NULL,
 420                               NULL,
 421                               NULL,
 422                               NULL,
 423                               NULL,
 424                               NULL)) {
 425     DWORD error = GetLastError();
 426     PLOG(ERROR) << "Failed to change the '" << kWindowsServiceName
 427                 << "'service start type to 'manual'";
 428     return HRESULT_FROM_WIN32(error);
 429   }
 430
 431   // Stop the service.
 432   SERVICE_STATUS status;
 433   if (!ControlService(service, SERVICE_CONTROL_STOP, &status)) {
 434     DWORD error = GetLastError();
 435     if (error != ERROR_SERVICE_NOT_ACTIVE) {
 436       PLOG(ERROR) << "Failed to stop the '" << kWindowsServiceName
 437                   << "'service";
 438       return HRESULT_FROM_WIN32(error);
 439     }
 440   }
 441
 442   return S_OK;
 443 }
 444
 445 STDMETHODIMP ElevatedController::UpdateConfig(BSTR config) {
 446   // Parse the config.
 447   std::string config_str = base::UTF16ToUTF8(
 448     base::string16(static_cast<base::char16*>(config), ::SysStringLen(config)));
 449   scoped_ptr<base::Value> config_value(base::JSONReader::Read(config_str));
 450   if (!config_value.get()) {
 451     return E_FAIL;
 452   }
 453   base::DictionaryValue* config_dict = NULL;
 454   if (!config_value->GetAsDictionary(&config_dict)) {
 455     return E_FAIL;
 456   }
 457   // Check for bad keys.
 458   for (int i = 0; i < arraysize(kReadonlyKeys); ++i) {
 459     if (config_dict->HasKey(kReadonlyKeys[i])) {
 460       return HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED);
 461     }
 462   }
 463   // Get the old config.
 464   base::FilePath config_dir = remoting::GetConfigDir();
 465   scoped_ptr<base::DictionaryValue> config_old;
 466   HRESULT hr = ReadConfig(config_dir.Append(kConfigFileName), &config_old);
 467   if (FAILED(hr)) {
 468     return hr;
 469   }
 470   // Merge items from the given config into the old config.
 471   config_old->MergeDictionary(config_dict);
 472   // Write the updated config.
 473   std::string config_updated_str;
 474   base::JSONWriter::Write(config_old.get(), &config_updated_str);
 475   return WriteConfig(config_updated_str.c_str(), config_updated_str.size(),
 476                      owner_window_);
 477 }
 478
 479 STDMETHODIMP ElevatedController::GetUsageStatsConsent(BOOL* allowed,
 480                                                          BOOL* set_by_policy) {
 481   bool local_allowed;
 482   bool local_set_by_policy;
 483   if (remoting::GetUsageStatsConsent(&local_allowed, &local_set_by_policy)) {
 484     *allowed = local_allowed;
 485     *set_by_policy = local_set_by_policy;
 486     return S_OK;
 487   } else {
 488     return E_FAIL;
 489   }
 490 }
 491
 492 STDMETHODIMP ElevatedController::SetUsageStatsConsent(BOOL allowed) {
 493   if (remoting::SetUsageStatsConsent(!!allowed)) {
 494     return S_OK;
 495   } else {
 496     return E_FAIL;
 497   }
 498 }
 499
 500 HRESULT ElevatedController::OpenService(ScopedScHandle* service_out) {
 501   DWORD error;
 502
 503   ScopedScHandle scmanager(
 504       ::OpenSCManagerW(NULL, SERVICES_ACTIVE_DATABASE,
 505                        SC_MANAGER_CONNECT | SC_MANAGER_ENUMERATE_SERVICE));
 506   if (!scmanager.IsValid()) {
 507     error = GetLastError();
 508     PLOG(ERROR) << "Failed to connect to the service control manager";
 509
 510     return HRESULT_FROM_WIN32(error);
 511   }
 512
 513   DWORD desired_access = SERVICE_CHANGE_CONFIG | SERVICE_QUERY_STATUS |
 514                          SERVICE_START | SERVICE_STOP;
 515   ScopedScHandle service(
 516       ::OpenServiceW(scmanager, kWindowsServiceName, desired_access));
 517   if (!service.IsValid()) {
 518     error = GetLastError();
 519     PLOG(ERROR) << "Failed to open to the '" << kWindowsServiceName
 520                 << "' service";
 521
 522     return HRESULT_FROM_WIN32(error);
 523   }
 524
 525   service_out->Set(service.Take());
 526   return S_OK;
 527 }
 528
 529 } // namespace remoting