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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.

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This commit is contained in:
Mounir IDRASSI
2019-12-10 00:44:47 +01:00
parent 5eaa204d83
commit f9d95ef2c8
3 changed files with 34 additions and 2 deletions
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25
src/Common/Format.c
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@@ -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;
}
}
}

1
src/Common/Format.h
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@@ -38,6 +38,7 @@ typedef struct
unsigned int clusterSize;
BOOL sparseFileSwitch;
BOOL quickFormat;
BOOL fastCreateFile;
DWORD sectorSize;
int *realClusterSize;
Password *password;