Windows: enhancements to the mechanism preserving file timestamps, especially for keyfiles.

author: Mounir IDRASSI <mounir.idrassi@idrix.fr> 2019-12-08 22:51:49 +0100
committer: Mounir IDRASSI <mounir.idrassi@idrix.fr> 2019-12-08 23:42:47 +0100
commit: 5e96a5c44c3c78a901d77297517fa4842a297eb9 (patch)
tree: c96c1f8cfc13c9435d26d31d267a5a125493349d /src
parent: 7f1e21e6a1103fd4a488ddbe63571c6ffecb38ca (diff)
download: VeraCrypt-5e96a5c44c3c78a901d77297517fa4842a297eb9.tar.gz
VeraCrypt-5e96a5c44c3c78a901d77297517fa4842a297eb9.zip
8 files changed, 138 insertions, 78 deletions
diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index 47578b27..5a837865 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -11238,10 +11238,8 @@ int OpenVolume (OpenVolumeContext *context, const wchar_t *volumePath, Password
 	else
 		StringCbCopyW (szCFDevice, sizeof(szCFDevice), szDiskFile);
 
-	if (preserveTimestamps)
-		write = TRUE;
 
-	context->HostFileHandle = CreateFile (szCFDevice, GENERIC_READ | (write ? GENERIC_WRITE : 0), FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
+	context->HostFileHandle = CreateFile (szCFDevice, GENERIC_READ | (write ? GENERIC_WRITE : (!context->IsDevice && preserveTimestamps? FILE_WRITE_ATTRIBUTES : 0)), FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
 
 	if (context->HostFileHandle == INVALID_HANDLE_VALUE)
 	{
@@ -11263,6 +11261,13 @@ int OpenVolume (OpenVolumeContext *context, const wchar_t *volumePath, Password
 	// Remember the container modification/creation date and time
 	if (!context->IsDevice && preserveTimestamps)
 	{
+		// ensure that Last Access and Last Write timestamps are not modified
+		FILETIME ftLastAccessTime;
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+		SetFileTime (context->HostFileHandle, NULL, &ftLastAccessTime, NULL);
+
 		if (GetFileTime (context->HostFileHandle, &context->CreationTime, &context->LastAccessTime, &context->LastWriteTime) == 0)
 			context->TimestampsValid = FALSE;
 		else
diff --git a/src/Common/Format.c b/src/Common/Format.c
index bd33f754..82c4df55 100644
--- a/src/Common/Format.c
+++ b/src/Common/Format.c
@@ -350,6 +350,19 @@ begin_format:
 			nStatus = ERR_OS_ERROR;
 			goto error;
 		}
+		else if (volParams->hiddenVol && bPreserveTimestamp)
+		{
+			// ensure that Last Access and Last Write timestamps are not modified
+			ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+			ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+			SetFileTime (dev, NULL, &ftLastAccessTime, NULL);
+
+			if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
+				bTimeStampValid = FALSE;
+			else
+				bTimeStampValid = TRUE;
+		}
 
 		DisableFileCompression (dev);
 
@@ -380,14 +393,6 @@ begin_format:
 		}
 	}
 
-	if (volParams->hiddenVol && !volParams->bDevice && bPreserveTimestamp)
-	{
-		if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
-			bTimeStampValid = FALSE;
-		else
-			bTimeStampValid = TRUE;
-	}
-
 	if (volParams->hwndDlg && volParams->bGuiMode) KillTimer (volParams->hwndDlg, TIMER_ID_RANDVIEW);
 
 	/* Volume header */
diff --git a/src/Common/Keyfiles.c b/src/Common/Keyfiles.c
index 686f3ca8..174aed92 100644
--- a/src/Common/Keyfiles.c
+++ b/src/Common/Keyfiles.c
@@ -149,50 +149,41 @@ void KeyFileCloneAll (KeyFile *firstKeyFile, KeyFile **outputKeyFile)
 
 static BOOL KeyFileProcess (unsigned __int8 *keyPool, unsigned __int32 keyPoolSize, KeyFile *keyFile)
 {
-	FILE *f;
 	unsigned __int8 buffer[64 * 1024];
 	unsigned __int32 crc = 0xffffffff;
 	unsigned __int32 writePos = 0;
-	size_t bytesRead, totalRead = 0;
+	DWORD bytesRead, totalRead = 0;
 	int status = TRUE;
-
 	HANDLE src;
-	FILETIME ftCreationTime;
-	FILETIME ftLastWriteTime;
-	FILETIME ftLastAccessTime;
-
-	BOOL bTimeStampValid = FALSE;
+	BOOL bReadStatus = FALSE;
 
-	/* Remember the last access time of the keyfile. It will be preserved in order to prevent
-	an adversary from determining which file may have been used as keyfile. */
 	src = CreateFile (keyFile->FileName,
-		GENERIC_READ | GENERIC_WRITE,
+		GENERIC_READ | FILE_WRITE_ATTRIBUTES,
 		FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
 
 	if (src != INVALID_HANDLE_VALUE)
 	{
-		if (GetFileTime ((HANDLE) src, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime))
-			bTimeStampValid = TRUE;
-	}
+		/* We tell Windows not to update the Last Access timestamp in order to prevent
+		an adversary from determining which file may have been used as keyfile. */
+		FILETIME ftLastAccessTime;
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
 
-	finally_do_arg (HANDLE, src,
+		SetFileTime (src, NULL, &ftLastAccessTime, NULL);
+	}
+	else
 	{
-		if (finally_arg != INVALID_HANDLE_VALUE)
-			CloseHandle (finally_arg);
-	});
-
-	f = _wfopen (keyFile->FileName, L"rb");
-	if (f == NULL) return FALSE;
+		/* try to open without FILE_WRITE_ATTRIBUTES in case we are in a ReadOnly filesystem (e.g. CD)                                                                                                                                                                                                                                         */
+		src = CreateFile (keyFile->FileName,
+			GENERIC_READ,
+			FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
+		if (src == INVALID_HANDLE_VALUE)
+			return FALSE;
+	}
 
-	while ((bytesRead = fread (buffer, 1, sizeof (buffer), f)) > 0)
+	while ((bReadStatus = ReadFile (src, buffer, sizeof (buffer), &bytesRead, NULL)) && (bytesRead > 0))
 	{
-		size_t i;
-
-		if (ferror (f))
-		{
-			status = FALSE;
-			goto close;
-		}
+		DWORD i;
 
 		for (i = 0; i < bytesRead; i++)
 		{
@@ -211,7 +202,7 @@ static BOOL KeyFileProcess (unsigned __int8 *keyPool, unsigned __int32 keyPoolSi
 		}
 	}
 
-	if (ferror (f))
+	if (!bReadStatus)
 	{
 		status = FALSE;
 	}
@@ -223,13 +214,9 @@ static BOOL KeyFileProcess (unsigned __int8 *keyPool, unsigned __int32 keyPoolSi
 
 close:
 	DWORD err = GetLastError();
-	fclose (f);
 
-	if (bTimeStampValid && !IsFileOnReadOnlyFilesystem (keyFile->FileName))
-	{
-		// Restore the keyfile timestamp
-		SetFileTime (src, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime);
-	}
+	CloseHandle (src);
+	burn (buffer, sizeof (buffer));
 
 	SetLastError (err);
 	return status;
diff --git a/src/Common/Password.c b/src/Common/Password.c
index ca0dd468..f2413b6d 100644
--- a/src/Common/Password.c
+++ b/src/Common/Password.c
@@ -224,6 +224,19 @@ int ChangePwd (const wchar_t *lpszVolume, Password *oldPassword, int old_pkcs5,
 
 	if (dev == INVALID_HANDLE_VALUE)
 		goto error;
+	else if (!bDevice && bPreserveTimestamp)
+	{
+		// ensure that Last Access and Last Write timestamps are not modified
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+		SetFileTime (dev, NULL, &ftLastAccessTime, NULL);
+
+		if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
+			bTimeStampValid = FALSE;
+		else
+			bTimeStampValid = TRUE;
+	}
 
 	if (bDevice)
 	{
@@ -313,13 +326,6 @@ int ChangePwd (const wchar_t *lpszVolume, Password *oldPassword, int old_pkcs5,
 
 	SetRandomPoolEnrichedByUserStatus (FALSE); /* force the display of the random enriching dialog */
 
-	if (!bDevice && bPreserveTimestamp)
-	{
-		if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
-			bTimeStampValid = FALSE;
-		else
-			bTimeStampValid = TRUE;
-	}
 
 	for (volumeType = TC_VOLUME_TYPE_NORMAL; volumeType < TC_VOLUME_TYPE_COUNT; volumeType++)
 	{
diff --git a/src/Driver/Ntvol.c b/src/Driver/Ntvol.c
index c3344fd0..e88105ca 100644
--- a/src/Driver/Ntvol.c
+++ b/src/Driver/Ntvol.c
@@ -303,7 +303,7 @@ NTSTATUS TCOpenVolume (PDEVICE_OBJECT DeviceObject,
 	if (mount->bMountReadOnly || ntStatus == STATUS_ACCESS_DENIED)
 	{
 		ntStatus = ZwCreateFile (&Extension->hDeviceFile,
-			GENERIC_READ | SYNCHRONIZE,
+			GENERIC_READ | (!bRawDevice && mount->bPreserveTimestamp? FILE_WRITE_ATTRIBUTES : 0) | SYNCHRONIZE,
 			&oaFileAttributes,
 			&IoStatusBlock,
 			NULL,
@@ -318,6 +318,26 @@ NTSTATUS TCOpenVolume (PDEVICE_OBJECT DeviceObject,
 			NULL,
 			0);
 
+		if (!NT_SUCCESS (ntStatus) && !bRawDevice && mount->bPreserveTimestamp)
+		{
+			/* try again without FILE_WRITE_ATTRIBUTES */
+			ntStatus = ZwCreateFile (&Extension->hDeviceFile,
+				GENERIC_READ | SYNCHRONIZE,
+				&oaFileAttributes,
+				&IoStatusBlock,
+				NULL,
+				FILE_ATTRIBUTE_NORMAL |
+				FILE_ATTRIBUTE_SYSTEM,
+				exclusiveAccess ? FILE_SHARE_READ : FILE_SHARE_READ | FILE_SHARE_WRITE,
+				FILE_OPEN,
+				FILE_RANDOM_ACCESS |
+				FILE_WRITE_THROUGH |
+				(disableBuffering ? FILE_NO_INTERMEDIATE_BUFFERING : 0) |
+				FILE_SYNCHRONOUS_IO_NONALERT,
+				NULL,
+				0);
+		}
+
 		if (NT_SUCCESS (ntStatus) && !mount->bMountReadOnly)
 			mount->VolumeMountedReadOnlyAfterAccessDenied = TRUE;
 
@@ -362,6 +382,18 @@ NTSTATUS TCOpenVolume (PDEVICE_OBJECT DeviceObject,
 				Extension->fileLastWriteTime = FileBasicInfo.LastWriteTime;
 				Extension->fileLastChangeTime = FileBasicInfo.ChangeTime;
 				Extension->bTimeStampValid = TRUE;
+
+				// we tell the system not to update LastAccessTime, LastWriteTime, and ChangeTime
+				FileBasicInfo.CreationTime.QuadPart = 0;
+				FileBasicInfo.LastAccessTime.QuadPart = -1;
+				FileBasicInfo.LastWriteTime.QuadPart = -1;
+				FileBasicInfo.ChangeTime.QuadPart = -1;
+
+				ZwSetInformationFile (Extension->hDeviceFile,
+					&IoStatusBlock,
+					&FileBasicInfo,
+					sizeof (FileBasicInfo),
+					FileBasicInformation);
 			}
 
 			ntStatus = ZwQueryInformationFile (Extension->hDeviceFile,
diff --git a/src/ExpandVolume/ExpandVolume.c b/src/ExpandVolume/ExpandVolume.c
index ec78a36f..8db2b573 100644
--- a/src/ExpandVolume/ExpandVolume.c
+++ b/src/ExpandVolume/ExpandVolume.c
@@ -535,6 +535,27 @@ static int ExpandVolume (HWND hwndDlg, wchar_t *lpszVolume, Password *pVolumePas
 
 	if (dev == INVALID_HANDLE_VALUE)
 		goto error;
+	else if (!bDevice && bPreserveTimestamp)
+	{
+		// ensure that Last Access and Last Time timestamps are not modified
+		// in order to preserve plausible deniability of hidden volumes (last password change time is stored in the volume header).
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+		SetFileTime (dev, NULL, &ftLastAccessTime, NULL);
+
+		/* Remember the container modification/creation date and time, (used to reset file date and time of
+		file-hosted volumes after password change (or attempt to), in order to preserve plausible deniability
+		of hidden volumes (last password change time is stored in the volume header). */
+
+		if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
+		{
+			bTimeStampValid = FALSE;
+			MessageBoxW (hwndDlg, GetString ("GETFILETIME_FAILED_PW"), lpszTitle, MB_OK | MB_ICONEXCLAMATION);
+		}
+		else
+			bTimeStampValid = TRUE;
+	}
 
 	if (bDevice)
 	{
@@ -628,20 +649,6 @@ static int ExpandVolume (HWND hwndDlg, wchar_t *lpszVolume, Password *pVolumePas
 		goto error;
 	}
 
-	if (!bDevice && bPreserveTimestamp)
-	{
-		/* Remember the container modification/creation date and time, (used to reset file date and time of
-		file-hosted volumes after password change (or attempt to), in order to preserve plausible deniability
-		of hidden volumes (last password change time is stored in the volume header). */
-
-		if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
-		{
-			bTimeStampValid = FALSE;
-			MessageBoxW (hwndDlg, GetString ("GETFILETIME_FAILED_PW"), lpszTitle, MB_OK | MB_ICONEXCLAMATION);
-		}
-		else
-			bTimeStampValid = TRUE;
-	}
 
 	// Seek the volume header
 	headerOffset.QuadPart = TC_VOLUME_HEADER_OFFSET;
diff --git a/src/Format/Tcformat.c b/src/Format/Tcformat.c
index dba64c20..013e27ca 100644
--- a/src/Format/Tcformat.c
+++ b/src/Format/Tcformat.c
@@ -3313,6 +3313,12 @@ BOOL IsSparseFile (HWND hwndDlg)
 
 	if (bPreserveTimestamp)
 	{
+		FILETIME ftLastAccessTime;
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+		SetFileTime (hFile, NULL, &ftLastAccessTime, NULL);
+
 		if (GetFileTime (hFile, NULL, &ftLastAccessTime, NULL) == 0)
 			bTimeStampValid = FALSE;
 		else
@@ -3352,6 +3358,12 @@ BOOL GetFileVolSize (HWND hwndDlg, unsigned __int64 *size)
 
 	if (bPreserveTimestamp)
 	{
+		FILETIME ftLastAccessTime;
+		ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+		ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+		SetFileTime (hFile, NULL, &ftLastAccessTime, NULL);
+
 		if (GetFileTime (hFile, NULL, &ftLastAccessTime, NULL) == 0)
 			bTimeStampValid = FALSE;
 		else
diff --git a/src/Mount/Mount.c b/src/Mount/Mount.c
index 54dc8158..9130eaee 100644
--- a/src/Mount/Mount.c
+++ b/src/Mount/Mount.c
@@ -10861,6 +10861,21 @@ int RestoreVolumeHeader (HWND hwndDlg, const wchar_t *lpszVolume)
 			nStatus = ERR_OS_ERROR;
 			goto error;
 		}
+		else if (!bDevice && bPreserveTimestamp)
+		{
+			// ensure that Last Access timestamp is not modified
+			ftLastAccessTime.dwHighDateTime = 0xFFFFFFFF;
+			ftLastAccessTime.dwLowDateTime = 0xFFFFFFFF;
+
+			SetFileTime (dev, NULL, &ftLastAccessTime, NULL);
+
+			/* Remember the container modification/creation date and time. */
+
+			if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
+				bTimeStampValid = FALSE;
+			else
+				bTimeStampValid = TRUE;
+		}
 
 		// Determine volume host size
 		if (bDevice)
@@ -10931,15 +10946,6 @@ int RestoreVolumeHeader (HWND hwndDlg, const wchar_t *lpszVolume)
 			hostSize = fileSize.QuadPart;
 		}
 
-		if (!bDevice && bPreserveTimestamp)
-		{
-			/* Remember the container modification/creation date and time. */
-
-			if (GetFileTime ((HANDLE) dev, &ftCreationTime, &ftLastAccessTime, &ftLastWriteTime) == 0)
-				bTimeStampValid = FALSE;
-			else
-				bTimeStampValid = TRUE;
-		}
 
 		/* Read the volume header from the backup file */
 		char buffer[TC_VOLUME_HEADER_GROUP_SIZE];
author	Mounir IDRASSI <mounir.idrassi@idrix.fr>	2019-12-08 22:51:49 +0100
committer	Mounir IDRASSI <mounir.idrassi@idrix.fr>	2019-12-08 23:42:47 +0100
commit	5e96a5c44c3c78a901d77297517fa4842a297eb9 (patch)
tree	c96c1f8cfc13c9435d26d31d267a5a125493349d /src
parent	7f1e21e6a1103fd4a488ddbe63571c6ffecb38ca (diff)
download	VeraCrypt-5e96a5c44c3c78a901d77297517fa4842a297eb9.tar.gz VeraCrypt-5e96a5c44c3c78a901d77297517fa4842a297eb9.zip