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_version_info.h"
   8 #include "base/files/file_util.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.Get(), &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.Get(), content, static_cast<DWORD>(length), &written,
 181                  NULL)) {
 182     DWORD error = GetLastError();
 183     PLOG(ERROR) << "Failed to write to '" << filename.value() << "'";
 184     return HRESULT_FROM_WIN32(error);
 185   }
 186
 187   return S_OK;
 188 }
 189
 190 // Moves a config file from its temporary location to its permanent location.
 191 HRESULT MoveConfigFileFromTemp(const base::FilePath& filename) {
 192   // Now that the configuration is stored successfully replace the actual
 193   // configuration file.
 194   base::FilePath tempname = GetTempLocationFor(filename);
 195   if (!MoveFileExW(tempname.value().c_str(),
 196                    filename.value().c_str(),
 197                    MOVEFILE_REPLACE_EXISTING)) {
 198       DWORD error = GetLastError();
 199       PLOG(ERROR) << "Failed to rename '" << tempname.value() << "' to '"
 200                   << filename.value() << "'";
 201       return HRESULT_FROM_WIN32(error);
 202   }
 203
 204   return S_OK;
 205 }
 206
 207 // Writes the configuration file up to |kMaxConfigFileSize| in size.
 208 HRESULT WriteConfig(const char* content, size_t length, HWND owner_window) {
 209   if (length > kMaxConfigFileSize) {
 210       return E_FAIL;
 211   }
 212
 213   // Extract the configuration data that the user will verify.
 214   scoped_ptr<base::Value> config_value(base::JSONReader::Read(content));
 215   if (!config_value.get()) {
 216     return E_FAIL;
 217   }
 218   base::DictionaryValue* config_dict = NULL;
 219   if (!config_value->GetAsDictionary(&config_dict)) {
 220     return E_FAIL;
 221   }
 222   std::string email;
 223   if (!config_dict->GetString(kHostOwner, &email)) {
 224     if (!config_dict->GetString(kXmppLogin, &email)) {
 225       return E_FAIL;
 226     }
 227   }
 228   std::string host_id, host_secret_hash;
 229   if (!config_dict->GetString(kHostId, &host_id) ||
 230       !config_dict->GetString(kHostSecretHash, &host_secret_hash)) {
 231     return E_FAIL;
 232   }
 233
 234   // Ask the user to verify the configuration (unless the client is admin
 235   // already).
 236   if (!IsClientAdmin()) {
 237     remoting::VerifyConfigWindowWin verify_win(email, host_id,
 238                                                host_secret_hash);
 239     DWORD error = verify_win.DoModal(owner_window);
 240     if (error != ERROR_SUCCESS) {
 241       return HRESULT_FROM_WIN32(error);
 242     }
 243   }
 244
 245   // Extract the unprivileged fields from the configuration.
 246   base::DictionaryValue unprivileged_config_dict;
 247   for (int i = 0; i < arraysize(kUnprivilegedConfigKeys); ++i) {
 248     const char* key = kUnprivilegedConfigKeys[i];
 249     base::string16 value;
 250     if (config_dict->GetString(key, &value)) {
 251       unprivileged_config_dict.SetString(key, value);
 252     }
 253   }
 254   std::string unprivileged_config_str;
 255   base::JSONWriter::Write(&unprivileged_config_dict, &unprivileged_config_str);
 256
 257   // Write the full configuration file to a temporary location.
 258   base::FilePath full_config_file_path =
 259       remoting::GetConfigDir().Append(kConfigFileName);
 260   HRESULT hr = WriteConfigFileToTemp(full_config_file_path,
 261                                      kConfigFileSecurityDescriptor,
 262                                      content,
 263                                      length);
 264   if (FAILED(hr)) {
 265     return hr;
 266   }
 267
 268   // Write the unprivileged configuration file to a temporary location.
 269   base::FilePath unprivileged_config_file_path =
 270       remoting::GetConfigDir().Append(kUnprivilegedConfigFileName);
 271   hr = WriteConfigFileToTemp(unprivileged_config_file_path,
 272                              kUnprivilegedConfigFileSecurityDescriptor,
 273                              unprivileged_config_str.data(),
 274                              unprivileged_config_str.size());
 275   if (FAILED(hr)) {
 276     return hr;
 277   }
 278
 279   // Move the full configuration file to its permanent location.
 280   hr = MoveConfigFileFromTemp(full_config_file_path);
 281   if (FAILED(hr)) {
 282     return hr;
 283   }
 284
 285   // Move the unprivileged configuration file to its permanent location.
 286   hr = MoveConfigFileFromTemp(unprivileged_config_file_path);
 287   if (FAILED(hr)) {
 288     return hr;
 289   }
 290
 291   return S_OK;
 292 }
 293
 294 } // namespace
 295
 296 ElevatedController::ElevatedController() : owner_window_(NULL) {
 297 }
 298
 299 HRESULT ElevatedController::FinalConstruct() {
 300   return S_OK;
 301 }
 302
 303 void ElevatedController::FinalRelease() {
 304 }
 305
 306 STDMETHODIMP ElevatedController::GetConfig(BSTR* config_out) {
 307   base::FilePath config_dir = remoting::GetConfigDir();
 308
 309   // Read the unprivileged part of host configuration.
 310   scoped_ptr<base::DictionaryValue> config;
 311   HRESULT hr = ReadConfig(config_dir.Append(kUnprivilegedConfigFileName),
 312                           &config);
 313   if (FAILED(hr)) {
 314     return hr;
 315   }
 316
 317   // Convert the config back to a string and return it to the caller.
 318   std::string file_content;
 319   base::JSONWriter::Write(config.get(), &file_content);
 320
 321   *config_out = ::SysAllocString(base::UTF8ToUTF16(file_content).c_str());
 322   if (config_out == NULL) {
 323     return E_OUTOFMEMORY;
 324   }
 325
 326   return S_OK;
 327 }
 328
 329 STDMETHODIMP ElevatedController::GetVersion(BSTR* version_out) {
 330   // Report the product version number of the daemon controller binary as
 331   // the host version.
 332   HMODULE binary = base::GetModuleFromAddress(
 333       reinterpret_cast<void*>(&ReadConfig));
 334   scoped_ptr<FileVersionInfo> version_info(
 335       FileVersionInfo::CreateFileVersionInfoForModule(binary));
 336
 337   base::string16 version;
 338   if (version_info.get()) {
 339     version = version_info->product_version();
 340   }
 341
 342   *version_out = ::SysAllocString(version.c_str());
 343   if (version_out == NULL) {
 344     return E_OUTOFMEMORY;
 345   }
 346
 347   return S_OK;
 348 }
 349
 350 STDMETHODIMP ElevatedController::SetConfig(BSTR config) {
 351   // Determine the config directory path and create it if necessary.
 352   base::FilePath config_dir = remoting::GetConfigDir();
 353   if (!base::CreateDirectory(config_dir)) {
 354     return HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED);
 355   }
 356
 357   std::string file_content = base::UTF16ToUTF8(
 358     base::string16(static_cast<base::char16*>(config), ::SysStringLen(config)));
 359
 360   return WriteConfig(file_content.c_str(), file_content.size(), owner_window_);
 361 }
 362
 363 STDMETHODIMP ElevatedController::SetOwnerWindow(LONG_PTR window_handle) {
 364   owner_window_ = reinterpret_cast<HWND>(window_handle);
 365   return S_OK;
 366 }
 367
 368 STDMETHODIMP ElevatedController::StartDaemon() {
 369   ScopedScHandle service;
 370   HRESULT hr = OpenService(&service);
 371   if (FAILED(hr)) {
 372     return hr;
 373   }
 374
 375   // Change the service start type to 'auto'.
 376   if (!::ChangeServiceConfigW(service.Get(),
 377                               SERVICE_NO_CHANGE,
 378                               SERVICE_AUTO_START,
 379                               SERVICE_NO_CHANGE,
 380                               NULL,
 381                               NULL,
 382                               NULL,
 383                               NULL,
 384                               NULL,
 385                               NULL,
 386                               NULL)) {
 387     DWORD error = GetLastError();
 388     PLOG(ERROR) << "Failed to change the '" << kWindowsServiceName
 389                 << "'service start type to 'auto'";
 390     return HRESULT_FROM_WIN32(error);
 391   }
 392
 393   // Start the service.
 394   if (!StartService(service.Get(), 0, NULL)) {
 395     DWORD error = GetLastError();
 396     if (error != ERROR_SERVICE_ALREADY_RUNNING) {
 397       PLOG(ERROR) << "Failed to start the '" << kWindowsServiceName
 398                   << "'service";
 399
 400       return HRESULT_FROM_WIN32(error);
 401     }
 402   }
 403
 404   return S_OK;
 405 }
 406
 407 STDMETHODIMP ElevatedController::StopDaemon() {
 408   ScopedScHandle service;
 409   HRESULT hr = OpenService(&service);
 410   if (FAILED(hr)) {
 411     return hr;
 412   }
 413
 414   // Change the service start type to 'manual'.
 415   if (!::ChangeServiceConfigW(service.Get(),
 416                               SERVICE_NO_CHANGE,
 417                               SERVICE_DEMAND_START,
 418                               SERVICE_NO_CHANGE,
 419                               NULL,
 420                               NULL,
 421                               NULL,
 422                               NULL,
 423                               NULL,
 424                               NULL,
 425                               NULL)) {
 426     DWORD error = GetLastError();
 427     PLOG(ERROR) << "Failed to change the '" << kWindowsServiceName
 428                 << "'service start type to 'manual'";
 429     return HRESULT_FROM_WIN32(error);
 430   }
 431
 432   // Stop the service.
 433   SERVICE_STATUS status;
 434   if (!ControlService(service.Get(), SERVICE_CONTROL_STOP, &status)) {
 435     DWORD error = GetLastError();
 436     if (error != ERROR_SERVICE_NOT_ACTIVE) {
 437       PLOG(ERROR) << "Failed to stop the '" << kWindowsServiceName
 438                   << "'service";
 439       return HRESULT_FROM_WIN32(error);
 440     }
 441   }
 442
 443   return S_OK;
 444 }
 445
 446 STDMETHODIMP ElevatedController::UpdateConfig(BSTR config) {
 447   // Parse the config.
 448   std::string config_str = base::UTF16ToUTF8(
 449     base::string16(static_cast<base::char16*>(config), ::SysStringLen(config)));
 450   scoped_ptr<base::Value> config_value(base::JSONReader::Read(config_str));
 451   if (!config_value.get()) {
 452     return E_FAIL;
 453   }
 454   base::DictionaryValue* config_dict = NULL;
 455   if (!config_value->GetAsDictionary(&config_dict)) {
 456     return E_FAIL;
 457   }
 458   // Check for bad keys.
 459   for (int i = 0; i < arraysize(kReadonlyKeys); ++i) {
 460     if (config_dict->HasKey(kReadonlyKeys[i])) {
 461       return HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED);
 462     }
 463   }
 464   // Get the old config.
 465   base::FilePath config_dir = remoting::GetConfigDir();
 466   scoped_ptr<base::DictionaryValue> config_old;
 467   HRESULT hr = ReadConfig(config_dir.Append(kConfigFileName), &config_old);
 468   if (FAILED(hr)) {
 469     return hr;
 470   }
 471   // Merge items from the given config into the old config.
 472   config_old->MergeDictionary(config_dict);
 473   // Write the updated config.
 474   std::string config_updated_str;
 475   base::JSONWriter::Write(config_old.get(), &config_updated_str);
 476   return WriteConfig(config_updated_str.c_str(), config_updated_str.size(),
 477                      owner_window_);
 478 }
 479
 480 STDMETHODIMP ElevatedController::GetUsageStatsConsent(BOOL* allowed,
 481                                                          BOOL* set_by_policy) {
 482   bool local_allowed;
 483   bool local_set_by_policy;
 484   if (remoting::GetUsageStatsConsent(&local_allowed, &local_set_by_policy)) {
 485     *allowed = local_allowed;
 486     *set_by_policy = local_set_by_policy;
 487     return S_OK;
 488   } else {
 489     return E_FAIL;
 490   }
 491 }
 492
 493 STDMETHODIMP ElevatedController::SetUsageStatsConsent(BOOL allowed) {
 494   if (remoting::SetUsageStatsConsent(!!allowed)) {
 495     return S_OK;
 496   } else {
 497     return E_FAIL;
 498   }
 499 }
 500
 501 HRESULT ElevatedController::OpenService(ScopedScHandle* service_out) {
 502   DWORD error;
 503
 504   ScopedScHandle scmanager(
 505       ::OpenSCManagerW(NULL, SERVICES_ACTIVE_DATABASE,
 506                        SC_MANAGER_CONNECT | SC_MANAGER_ENUMERATE_SERVICE));
 507   if (!scmanager.IsValid()) {
 508     error = GetLastError();
 509     PLOG(ERROR) << "Failed to connect to the service control manager";
 510
 511     return HRESULT_FROM_WIN32(error);
 512   }
 513
 514   DWORD desired_access = SERVICE_CHANGE_CONFIG | SERVICE_QUERY_STATUS |
 515                          SERVICE_START | SERVICE_STOP;
 516   ScopedScHandle service(
 517       ::OpenServiceW(scmanager.Get(), kWindowsServiceName, desired_access));
 518   if (!service.IsValid()) {
 519     error = GetLastError();
 520     PLOG(ERROR) << "Failed to open to the '" << kWindowsServiceName
 521                 << "' service";
 522
 523     return HRESULT_FROM_WIN32(error);
 524   }
 525
 526   service_out->Set(service.Take());
 527   return S_OK;
 528 }
 529
 530 } // namespace remoting