From f9d95ef2c84ebc61e4e0c77f8b9f054c65abd7cd Mon Sep 17 00:00:00 2001
From: Mounir IDRASSI <mounir.idrassi@idrix.fr>
Date: Tue, 10 Dec 2019 00:44:47 +0100
Subject: Windows: Add switch /FastCreateFile for VeraCrypt Format.exe to
 speedup creation of large file container if quick format is selected. This
 switch comes with security issues since it will embed existing content on
 disk into the file container which may expose sensitive content to an
 attacker who has access to the file container.

---
 src/Common/Format.c   | 25 +++++++++++++++++++++++--
 src/Common/Format.h   |  1 +
 src/Format/Tcformat.c | 10 ++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/Common/Format.c b/src/Common/Format.c
index 82c4df55..4aaf8b32 100644
--- a/src/Common/Format.c
+++ b/src/Common/Format.c
@@ -369,8 +369,13 @@ begin_format:
 		if (!volParams->hiddenVol && !bInstantRetryOtherFilesys)
 		{
 			LARGE_INTEGER volumeSize;
+			BOOL speedupFileCreation = FALSE;
 			volumeSize.QuadPart = dataAreaSize + TC_VOLUME_HEADER_GROUP_SIZE;
 
+			// speedup for file creation only makes sens when using quick format
+			if (volParams->quickFormat && volParams->fastCreateFile)
+				speedupFileCreation = TRUE;
+
 			if (volParams->sparseFileSwitch && volParams->quickFormat)
 			{
 				// Create as sparse file container
@@ -384,12 +389,28 @@ begin_format:
 
 			// Preallocate the file
 			if (!SetFilePointerEx (dev, volumeSize, NULL, FILE_BEGIN)
-				|| !SetEndOfFile (dev)
-				|| SetFilePointer (dev, 0, NULL, FILE_BEGIN) != 0)
+				|| !SetEndOfFile (dev))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto error;
+			}
+
+			if (speedupFileCreation)
+			{
+				// accelerate file creation by telling Windows not to fill all file content with zeros
+				// this has security issues since it will put existing disk content into file container
+				// We use this mechanism only when switch /fastCreateFile specific and when quick format
+				// also specified and which is documented to have security issues.
+				// we don't check returned status because failure is not issue for us
+				SetFileValidData (dev, volumeSize.QuadPart);
+			}
+
+			if (SetFilePointer (dev, 0, NULL, FILE_BEGIN) != 0)
 			{
 				nStatus = ERR_OS_ERROR;
 				goto error;
 			}
+
 		}
 	}
 
diff --git a/src/Common/Format.h b/src/Common/Format.h
index 961ece7c..4ce1b8c7 100644
--- a/src/Common/Format.h
+++ b/src/Common/Format.h
@@ -38,6 +38,7 @@ typedef struct
 	unsigned int clusterSize;
 	BOOL sparseFileSwitch;
 	BOOL quickFormat;
+	BOOL fastCreateFile;
 	DWORD sectorSize;
 	int *realClusterSize;
 	Password *password;
diff --git a/src/Format/Tcformat.c b/src/Format/Tcformat.c
index 013e27ca..002b6c5c 100644
--- a/src/Format/Tcformat.c
+++ b/src/Format/Tcformat.c
@@ -250,6 +250,7 @@ int CmdVolumeFilesystem = FILESYS_NONE;
 unsigned __int64 CmdVolumeFileSize = 0;
 BOOL CmdSparseFileSwitch = FALSE;
 BOOL CmdQuickFormat = FALSE;
+BOOL CmdFastCreateFile = FALSE;
 
 BOOL bForceOperation = FALSE;
 
@@ -282,6 +283,7 @@ BOOL bDisplayPoolContents = TRUE;
 
 volatile BOOL bSparseFileSwitch = FALSE;
 volatile BOOL quickFormat = FALSE;
+volatile BOOL fastCreateFile = FALSE;
 volatile BOOL dynamicFormat = FALSE; /* this variable represents the sparse file flag. */
 volatile int fileSystem = FILESYS_NONE;
 volatile int clusterSize = 0;
@@ -2635,6 +2637,7 @@ static void __cdecl volTransformThreadFunction (void *hwndDlgArg)
 	volParams->clusterSize = clusterSize;
 	volParams->sparseFileSwitch = dynamicFormat;
 	volParams->quickFormat = quickFormat;
+	volParams->fastCreateFile = fastCreateFile;
 	volParams->sectorSize = GetFormatSectorSize();
 	volParams->realClusterSize = &realClusterSize;
 	volParams->password = &volumePassword;
@@ -6234,6 +6237,7 @@ BOOL CALLBACK MainDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
 				}
 
 				quickFormat = CmdQuickFormat;
+				fastCreateFile = CmdFastCreateFile;
 				dynamicFormat = CmdSparseFileSwitch;
 
 				if (!GetDiskFreeSpaceEx (root, &free, 0, 0))
@@ -8994,6 +8998,7 @@ void ExtractCommandLine (HWND hwndDlg, wchar_t *lpszCommandLine)
 				OptionForce,
 				OptionNoSizeCheck,
 				OptionQuickFormat,
+				OptionFastCreateFile,
 			};
 
 			argument args[]=
@@ -9016,6 +9021,7 @@ void ExtractCommandLine (HWND hwndDlg, wchar_t *lpszCommandLine)
 				{ OptionForce,					L"/force",			NULL, FALSE },
 				{ OptionNoSizeCheck,			L"/nosizecheck",	NULL, FALSE },
 				{ OptionQuickFormat,			L"/quick",	NULL, FALSE },
+				{ OptionFastCreateFile,			L"/fastcreatefile",	NULL, FALSE },
 
 				// Internal
 				{ CommandResumeSysEncLogOn,		L"/acsysenc",		L"/a", TRUE },
@@ -9372,6 +9378,10 @@ void ExtractCommandLine (HWND hwndDlg, wchar_t *lpszCommandLine)
 				CmdQuickFormat = TRUE;
 				break;
 
+			case OptionFastCreateFile:
+				CmdFastCreateFile = TRUE;
+				break;
+
 			case OptionHistory:
 				{
 					wchar_t szTmp[8] = {0};
-- 
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