Do not allow copy/paste at all inside NVDA's UI while in secure mode …

…(e.g. when NVDA is running on the secure desktop -- lock screen -- windows logon). To do this, Only in the NVDA process itself, and only in secure mode, nvdaHelperRemote hooks the OpenClipboard Windows API function and forces it to return false, and does not call the original OpenClipboard. This simply denies access to the clipboard for NVDA's process. Fixes #1421.

nvdaHelper/remote/injection.cpp

@@ -39,6 +39,7 @@ HWINEVENTHOOK inprocWinEventHookID=0;
 set<HHOOK> inprocCurrentWindowsHooks;
 long tlsIndex_inThreadInjectionID=0;
 bool isProcessExiting=false;
+bool isSecureModeNVDAProcess=false;
 
 //Code executed in-process
 
@@ -72,6 +73,14 @@ void killRunningWindowsHooks() {
 	}
 }
 
+//A replacement OpenClipboard function to disable the use of the clipboard in a secure mode NVDA process
+//Simply returns false without calling the original OpenClipboard
+typedef BOOL(WINAPI *OpenClipboard_funcType)(HWND);
+OpenClipboard_funcType real_OpenClipboard=NULL;
+BOOL WINAPI fake_OpenClipboard(HWND hwndOwner) {
+	return false;
+}
+
 //A thread function that runs while  NVDA is injected in a process.
 //Note that a mutex is used to make sure that there is never more than one copy of this thread in a given process at any given time.
 //I.e. Another copy of NVDA is started  while the first is still running.
@@ -113,6 +122,8 @@ DWORD WINAPI inprocMgrThreadFunc(LPVOID data) {
 		}
 		//Initialize API hooking
 		apiHook_initialize();
+	//Fore secure mode NVDA process, hook OpenClipboard to disable usage of the clipboard
+	if(isSecureModeNVDAProcess) real_OpenClipboard=apiHook_hookFunction_safe("USER32.dll",OpenClipboard,fake_OpenClipboard);
 		//Initialize in-process subsystems
 		inProcess_initialize();
 		//Enable all registered API hooks
@@ -253,7 +264,12 @@ DWORD outprocMgrThreadID=0;
 BOOL outprocInitialized=FALSE;
 HANDLE injectionDoneEvent=NULL;
 
-BOOL injection_initialize() {
+/**
+ * Initializes the out-of-process code for NVDAHelper 
+ * @param secureMode 1 specifies that NVDA is running in seucre mode, 0 says not.
+ */ 
+BOOL injection_initialize(int secureMode) {
+	if(secureMode) isSecureModeNVDAProcess=true;
 	if(outprocInitialized) {
 		MessageBox(NULL,L"Already initialized",L"nvdaHelperRemote (injection_initialize)",0);
 		return FALSE;

source/NVDAHelper.py

@@ -200,7 +200,7 @@ def initialize():
 		log.critical("Error loading nvdaHelperRemote.dll: %s" % WinError())
 		return
 	_remoteLib=CDLL("nvdaHelperRemote",handle=h)
-	if _remoteLib.injection_initialize() == 0:
+	if _remoteLib.injection_initialize(globalVars.appArgs.secure) == 0:
 		raise RuntimeError("Error initializing NVDAHelperRemote")
 	if os.environ.get('PROCESSOR_ARCHITEW6432')=='AMD64':
 		_remoteLoader64=RemoteLoader64()