From 409c0f79be069cd2cf3bdb31ddbbafd938f15791 Mon Sep 17 00:00:00 2001
From: Mounir IDRASSI <mounir.idrassi@idrix.fr>
Date: Sun, 3 Apr 2016 08:29:34 +0200
Subject: Windows: allow drag-n-drop of files and receiving Explorer restart
 message when VeraCrypt running as elevated process.

---
 src/Common/Dlgcode.c | 35 +++++++++++++++++++++++++++++++++++
 src/Common/Dlgcode.h |  1 +
 src/Mount/Mount.c    |  2 ++
 3 files changed, 38 insertions(+)

(limited to 'src')

diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index 2cf5bb8e..749caa40 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -248,6 +248,9 @@ typedef LSTATUS (STDAPICALLTYPE *SHDeleteKeyWPtr)(HKEY hkey, LPCWSTR pszSubKey);
 
 typedef HRESULT (STDAPICALLTYPE *SHStrDupWPtr)(LPCWSTR psz, LPWSTR *ppwsz);
 
+// ChangeWindowMessageFilter
+typedef BOOL (WINAPI *ChangeWindowMessageFilterPtr) (UINT, DWORD);
+
 ImageList_CreatePtr ImageList_CreateFn = NULL;
 ImageList_AddPtr ImageList_AddFn = NULL;
 
@@ -257,6 +260,7 @@ SetupInstallFromInfSectionWPtr SetupInstallFromInfSectionWFn = NULL;
 SetupOpenInfFileWPtr SetupOpenInfFileWFn = NULL;
 SHDeleteKeyWPtr SHDeleteKeyWFn = NULL;
 SHStrDupWPtr SHStrDupWFn = NULL;
+ChangeWindowMessageFilterPtr ChangeWindowMessageFilterFn = NULL;
 
 /* Windows dialog class */
 #define WINDOWS_DIALOG_CLASS L"#32770"
@@ -265,6 +269,16 @@ SHStrDupWPtr SHStrDupWFn = NULL;
 #define TC_DLG_CLASS L"VeraCryptCustomDlg"
 #define TC_SPLASH_CLASS L"VeraCryptSplashDlg"
 
+/* constant used by ChangeWindowMessageFilter calls */
+#ifndef MSGFLT_ADD
+#define MSGFLT_ADD	1
+#endif
+
+/* undocumented message sent during drag-n-drop */
+#ifndef WM_COPYGLOBALDATA
+#define WM_COPYGLOBALDATA 0x0049
+#endif
+
 /* Benchmarks */
 
 #ifndef SETUP
@@ -2603,6 +2617,19 @@ void InitApp (HINSTANCE hInstance, wchar_t *lpszCommandLine)
 	if (!SHDeleteKeyWFn || !SHStrDupWFn)
 		AbortProcess ("INIT_DLL");
 
+	if (IsOSAtLeast (WIN_VISTA))
+	{
+		/* Get ChangeWindowMessageFilter used to enable some messages bypasss UIPI (User Interface Privilege Isolation) */
+		ChangeWindowMessageFilterFn = (ChangeWindowMessageFilterPtr) GetProcAddress (GetModuleHandle (L"user32.dll"), "ChangeWindowMessageFilter");
+
+#ifndef SETUP
+		/* enable drag-n-drop when we are running elevated */
+		AllowMessageInUIPI (WM_DROPFILES);
+		AllowMessageInUIPI (WM_COPYDATA);
+		AllowMessageInUIPI (WM_COPYGLOBALDATA);
+#endif
+	}
+
 	/* Save the instance handle for later */
 	hInst = hInstance;
 
@@ -11575,3 +11602,11 @@ void ProcessEntropyEstimate (HWND hProgress, DWORD* pdwInitialValue, DWORD dwCou
 		0);
 	}
 }
+
+void AllowMessageInUIPI (UINT msg)
+{
+	if (ChangeWindowMessageFilterFn)
+	{
+		ChangeWindowMessageFilterFn (msg, MSGFLT_ADD);
+	}
+}
diff --git a/src/Common/Dlgcode.h b/src/Common/Dlgcode.h
index 20199924..ef00871e 100644
--- a/src/Common/Dlgcode.h
+++ b/src/Common/Dlgcode.h
@@ -500,6 +500,7 @@ HIMAGELIST  CreateImageList(int cx, int cy, UINT flags, int cInitial, int cGrow)
 int AddBitmapToImageList(HIMAGELIST himl, HBITMAP hbmImage, HBITMAP hbmMask);
 HRESULT VCStrDupW(LPCWSTR psz, LPWSTR *ppwsz);
 void ProcessEntropyEstimate (HWND hProgress, DWORD* pdwInitialValue, DWORD dwCounter, DWORD dwMaxLevel, DWORD* pdwEntropy);
+void AllowMessageInUIPI (UINT msg);
 
 #ifdef __cplusplus
 }
diff --git a/src/Mount/Mount.c b/src/Mount/Mount.c
index fbf631f8..0acf58dd 100644
--- a/src/Mount/Mount.c
+++ b/src/Mount/Mount.c
@@ -6547,6 +6547,8 @@ BOOL CALLBACK MainDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
 
 			taskBarCreatedMsg = RegisterWindowMessage (L"TaskbarCreated");
 
+			AllowMessageInUIPI (taskBarCreatedMsg);
+
 			SetFocus (GetDlgItem (hwndDlg, IDC_DRIVELIST));
 
 			/* Check system encryption status */
-- 
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