Update Windows It2Me to allow remote users to interact with elevated windows

remoting/host/it2me/it2me_native_messaging_host_main.cc

Index: remoting/host/it2me/it2me_native_messaging_host_main.cc
diff --git a/remoting/host/it2me/it2me_native_messaging_host_main.cc b/remoting/host/it2me/it2me_native_messaging_host_main.cc
index 3c9671941c0a4e4219c8403aba8ba47bb69a6808..6729ad66a4eabf30d89681aebdc7da1cf19b3dee 100644
--- a/remoting/host/it2me/it2me_native_messaging_host_main.cc
+++ b/remoting/host/it2me/it2me_native_messaging_host_main.cc
@@ -37,6 +37,9 @@
 
 #if defined(OS_WIN)
 #include <commctrl.h>
+
+#include "remoting/host/switches.h"
+#include "remoting/host/win/elevation_helpers.h"
 #endif  // defined(OS_WIN)
 
 namespace remoting {
@@ -90,28 +93,75 @@ int StartIt2MeNativeMessagingHost() {
   // single-threaded.
   net::EnableSSLServerSockets();
 
+  base::File read_file;
+  base::File write_file;
+  bool needs_elevation = false;
+
 #if defined(OS_WIN)
-  // GetStdHandle() returns pseudo-handles for stdin and stdout even if
-  // the hosting executable specifies "Windows" subsystem. However the returned
-  // handles are invalid in that case unless standard input and output are
-  // redirected to a pipe or file.
-  base::File read_file(GetStdHandle(STD_INPUT_HANDLE));
-  base::File write_file(GetStdHandle(STD_OUTPUT_HANDLE));
-
-  // After the native messaging channel starts the native messaging reader
-  // will keep doing blocking read operations on the input named pipe.
-  // If any other thread tries to perform any operation on STDIN, it will also
-  // block because the input named pipe is synchronous (non-overlapped).
-  // It is pretty common for a DLL to query the device info (GetFileType) of
-  // the STD* handles at startup. So any LoadLibrary request can potentially
-  // be blocked. To prevent that from happening we close STDIN and STDOUT
-  // handles as soon as we retrieve the corresponding file handles.
-  SetStdHandle(STD_INPUT_HANDLE, nullptr);
-  SetStdHandle(STD_OUTPUT_HANDLE, nullptr);
+
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+
+  if (command_line->HasSwitch(kElevateSwitchName)) {
+#if defined(OFFICIAL_BUILD)
+    // Unofficial builds won't have 'UiAccess' since it requires signing.
+    CHECK(CurrentProcessHasUiAccess());

[Sergey Ulanov, 2016/09/02 23:21:14]

Do we actually need to crash the process in this case? Maybe just log an error?

[joedow, 2016/09/06 22:51:59]

I chose to use a CHECK here as this functionality only works on official builds
which we don't generally run in debug mode.  I'd really hate to miss this
problem because It2Me appeared to work but was silently failing.

I made this decision before we decided to use a policy to control the behavior
though, I think it is now more likely that we would test without the policy set
and miss this bug and then start seeing crashes after we ship.  I will change
this to a log statement to make it easier to debug.

+#endif  // defined(OFFICIAL_BUILD)
+
+    // The UiAccess binary should always have the "input" and "output" switches
+    // specified, they represent the name of the named pipes that should be used
+    // in place of stdin and stdout.
+    DCHECK(command_line->HasSwitch(kInputSwitchName));
+    DCHECK(command_line->HasSwitch(kOutputSwitchName));
+
+    // presubmit: allow wstring
+    std::wstring input_pipe_name =
+        command_line->GetSwitchValueNative(kInputSwitchName);
+    // presubmit: allow wstring
+    std::wstring output_pipe_name =
+        command_line->GetSwitchValueNative(kOutputSwitchName);
+
+    // A NULL SECURITY_ATTRIBUTES signifies that the handle can't be inherited.
+    read_file =
+        base::File(CreateFile(input_pipe_name.c_str(), GENERIC_READ, 0, nullptr,
+                              OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr));
+    if (!read_file.IsValid()) {
+      PLOG(ERROR) << "CreateFile failed on '" << input_pipe_name << "'";
+      return kInitializationFailed;
+    }
+
+    write_file = base::File(CreateFile(output_pipe_name.c_str(), GENERIC_WRITE,
+                                       0, nullptr, OPEN_EXISTING,
+                                       FILE_ATTRIBUTE_NORMAL, nullptr));
+    if (!write_file.IsValid()) {
+      PLOG(ERROR) << "CreateFile failed on '" << output_pipe_name << "'";
+      return kInitializationFailed;
+    }
+  } else {
+    needs_elevation = true;
+
+    // GetStdHandle() returns pseudo-handles for stdin and stdout even if
+    // the hosting executable specifies "Windows" subsystem. However the
+    // returned  handles are invalid in that case unless standard input and
+    // output are redirected to a pipe or file.
+    read_file = base::File(GetStdHandle(STD_INPUT_HANDLE));
+    write_file = base::File(GetStdHandle(STD_OUTPUT_HANDLE));
+
+    // After the native messaging channel starts the native messaging reader
+    // will keep doing blocking read operations on the input named pipe.
+    // If any other thread tries to perform any operation on STDIN, it will also
+    // block because the input named pipe is synchronous (non-overlapped).
+    // It is pretty common for a DLL to query the device info (GetFileType) of
+    // the STD* handles at startup. So any LoadLibrary request can potentially
+    // be blocked. To prevent that from happening we close STDIN and STDOUT
+    // handles as soon as we retrieve the corresponding file handles.
+    SetStdHandle(STD_INPUT_HANDLE, nullptr);
+    SetStdHandle(STD_OUTPUT_HANDLE, nullptr);
+  }
 #elif defined(OS_POSIX)
   // The files are automatically closed.
-  base::File read_file(STDIN_FILENO);
-  base::File write_file(STDOUT_FILENO);
+  read_file = base::File(STDIN_FILENO);
+  write_file = base::File(STDOUT_FILENO);
 #else
 #error Not implemented.
 #endif
@@ -132,7 +182,8 @@ int StartIt2MeNativeMessagingHost() {
       ChromotingHostContext::Create(new remoting::AutoThreadTaskRunner(
           message_loop.task_runner(), run_loop.QuitClosure()));
   std::unique_ptr<extensions::NativeMessageHost> host(
-      new It2MeNativeMessagingHost(std::move(context), std::move(factory)));
+      new It2MeNativeMessagingHost(needs_elevation, /*policy_service=*/nullptr,
+                                   std::move(context), std::move(factory)));
 
   host->Start(native_messaging_pipe.get());