remoting/host/win/chromoting_module.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 "remoting/host/win/chromoting_module.h"
   6
   7 #include "base/lazy_instance.h"
   8 #include "base/logging.h"
   9 #include "base/message_loop/message_loop.h"
  10 #include "base/run_loop.h"
  11 #include "base/strings/utf_string_conversions.h"
  12 #include "base/win/scoped_handle.h"
  13 #include "base/win/windows_version.h"
  14 #include "remoting/base/auto_thread_task_runner.h"
  15 #include "remoting/base/typed_buffer.h"
  16 #include "remoting/host/host_exit_codes.h"
  17 #include "remoting/host/win/rdp_desktop_session.h"
  18
  19 namespace remoting {
  20
  21 namespace {
  22
  23 // Holds a reference to the task runner used by the module.
  24 base::LazyInstance<scoped_refptr<AutoThreadTaskRunner> > g_module_task_runner =
  25     LAZY_INSTANCE_INITIALIZER;
  26
  27 // Lowers the process integrity level such that it does not exceed |max_level|.
  28 // |max_level| is expected to be one of SECURITY_MANDATORY_XXX constants.
  29 bool LowerProcessIntegrityLevel(DWORD max_level) {
  30   HANDLE temp_handle;
  31   if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY | TOKEN_WRITE,
  32                         &temp_handle)) {
  33     PLOG(ERROR) << "OpenProcessToken() failed";
  34     return false;
  35   }
  36   base::win::ScopedHandle token(temp_handle);
  37
  38   TypedBuffer<TOKEN_MANDATORY_LABEL> mandatory_label;
  39   DWORD length = 0;
  40
  41   // Get the size of the buffer needed to hold the mandatory label.
  42   BOOL result = GetTokenInformation(token.Get(), TokenIntegrityLevel,
  43                                     mandatory_label.get(), length, &length);
  44   if (!result && GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
  45     // Allocate a buffer that is large enough.
  46     TypedBuffer<TOKEN_MANDATORY_LABEL> buffer(length);
  47     mandatory_label.Swap(buffer);
  48
  49     // Get the the mandatory label.
  50     result = GetTokenInformation(token.Get(), TokenIntegrityLevel,
  51                                  mandatory_label.get(), length, &length);
  52   }
  53   if (!result) {
  54     PLOG(ERROR) << "Failed to get the mandatory label";
  55     return false;
  56   }
  57
  58   // Read the current integrity level.
  59   DWORD sub_authority_count =
  60       *GetSidSubAuthorityCount(mandatory_label->Label.Sid);
  61   DWORD* current_level = GetSidSubAuthority(mandatory_label->Label.Sid,
  62                                             sub_authority_count - 1);
  63
  64   // Set the integrity level to |max_level| if needed.
  65   if (*current_level > max_level) {
  66     *current_level = max_level;
  67     if (!SetTokenInformation(token.Get(), TokenIntegrityLevel,
  68                              mandatory_label.get(), length)) {
  69       PLOG(ERROR) << "Failed to set the mandatory label";
  70       return false;
  71     }
  72   }
  73
  74   return true;
  75 }
  76
  77 }  // namespace
  78
  79 ChromotingModule::ChromotingModule(
  80     ATL::_ATL_OBJMAP_ENTRY* classes,
  81     ATL::_ATL_OBJMAP_ENTRY* classes_end)
  82     : classes_(classes),
  83       classes_end_(classes_end) {
  84   // Don't do anything if COM initialization failed.
  85   if (!com_initializer_.succeeded())
  86     return;
  87
  88   ATL::_AtlComModule.ExecuteObjectMain(true);
  89 }
  90
  91 ChromotingModule::~ChromotingModule() {
  92   // Don't do anything if COM initialization failed.
  93   if (!com_initializer_.succeeded())
  94     return;
  95
  96   Term();
  97   ATL::_AtlComModule.ExecuteObjectMain(false);
  98 }
  99
 100 // static
 101 scoped_refptr<AutoThreadTaskRunner> ChromotingModule::task_runner() {
 102   return g_module_task_runner.Get();
 103 }
 104
 105 bool ChromotingModule::Run() {
 106   // Don't do anything if COM initialization failed.
 107   if (!com_initializer_.succeeded())
 108     return false;
 109
 110   // Register class objects.
 111   HRESULT result = RegisterClassObjects(CLSCTX_LOCAL_SERVER,
 112                                         REGCLS_MULTIPLEUSE | REGCLS_SUSPENDED);
 113   if (FAILED(result)) {
 114     LOG(ERROR) << "Failed to register class objects, result=0x"
 115                << std::hex << result << std::dec << ".";
 116     return false;
 117   }
 118
 119   // Arrange to run |message_loop| until no components depend on it.
 120   base::MessageLoopForUI message_loop;
 121   base::RunLoop run_loop;
 122   g_module_task_runner.Get() = new AutoThreadTaskRunner(
 123       message_loop.task_runner(), run_loop.QuitClosure());
 124
 125   // Start accepting activations.
 126   result = CoResumeClassObjects();
 127   if (FAILED(result)) {
 128     LOG(ERROR) << "CoResumeClassObjects() failed, result=0x"
 129                << std::hex << result << std::dec << ".";
 130     return false;
 131   }
 132
 133   // Run the loop until the module lock counter reaches zero.
 134   run_loop.Run();
 135
 136   // Unregister class objects.
 137   result = RevokeClassObjects();
 138   if (FAILED(result)) {
 139     LOG(ERROR) << "Failed to unregister class objects, result=0x"
 140                << std::hex << result << std::dec << ".";
 141     return false;
 142   }
 143
 144   return true;
 145 }
 146
 147 LONG ChromotingModule::Unlock() {
 148   LONG count = ATL::CAtlModuleT<ChromotingModule>::Unlock();
 149
 150   if (!count) {
 151     // Stop accepting activations.
 152     HRESULT hr = CoSuspendClassObjects();
 153     CHECK(SUCCEEDED(hr));
 154
 155     // Release the message loop reference, causing the message loop to exit.
 156     g_module_task_runner.Get() = nullptr;
 157   }
 158
 159   return count;
 160 }
 161
 162 HRESULT ChromotingModule::RegisterClassObjects(DWORD class_context,
 163                                                DWORD flags) {
 164   for (ATL::_ATL_OBJMAP_ENTRY* i = classes_; i != classes_end_; ++i) {
 165     HRESULT result = i->RegisterClassObject(class_context, flags);
 166     if (FAILED(result))
 167       return result;
 168   }
 169
 170   return S_OK;
 171 }
 172
 173 HRESULT ChromotingModule::RevokeClassObjects() {
 174   for (ATL::_ATL_OBJMAP_ENTRY* i = classes_; i != classes_end_; ++i) {
 175     HRESULT result = i->RevokeClassObject();
 176     if (FAILED(result))
 177       return result;
 178   }
 179
 180   return S_OK;
 181 }
 182
 183 // RdpClient entry point.
 184 int RdpDesktopSessionMain() {
 185   // Lower the integrity level to medium, which is the lowest level at which
 186   // the RDP ActiveX control can run.
 187   if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
 188     if (!LowerProcessIntegrityLevel(SECURITY_MANDATORY_MEDIUM_RID))
 189       return kInitializationFailed;
 190   }
 191
 192   ATL::_ATL_OBJMAP_ENTRY rdp_client_entry[] = {
 193     OBJECT_ENTRY(__uuidof(RdpDesktopSession), RdpDesktopSession)
 194   };
 195
 196   ChromotingModule module(rdp_client_entry, rdp_client_entry + 1);
 197   return module.Run() ? kSuccessExitCode : kInitializationFailed;
 198 }
 199
 200 } // namespace remoting