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authorMounir IDRASSI <mounir.idrassi@idrix.fr>2023-06-04 16:25:55 +0200
committerMounir IDRASSI <mounir.idrassi@idrix.fr>2023-06-04 16:25:55 +0200
commit22466535f1b9cbe1bd98363cfa98f7f796bc408a (patch)
tree7ee1c59af8e16b57953a86f8837fe465e418f60a /src/Format/InPlace.c
parent3c68349a39877c5420c727cd53143ab442963759 (diff)
downloadVeraCrypt-22466535f1b9cbe1bd98363cfa98f7f796bc408a.tar.gz
VeraCrypt-22466535f1b9cbe1bd98363cfa98f7f796bc408a.zip
Windows: Possible workaround for logarithmic slowdown for Encrypt-In-Place on large volumes (relates to #1063)
We replace absolute file pointer moving by relative moving with respect to current position. This was implemented as a workaround to address the performance issues related to in-place encryption. When using SetFilePointerEx() with FILE_BEGIN as the reference point, reaching the end of large drives during in-place encryption can cause significant slowdowns. By moving the file pointer relatively, these performance issues are mitigated.
Diffstat (limited to 'src/Format/InPlace.c')
-rw-r--r--src/Format/InPlace.c72
1 files changed, 51 insertions, 21 deletions
diff --git a/src/Format/InPlace.c b/src/Format/InPlace.c
index f6166dab..4549cc53 100644
--- a/src/Format/InPlace.c
+++ b/src/Format/InPlace.c
@@ -593,7 +593,7 @@ int EncryptPartitionInPlaceBegin (volatile FORMAT_VOL_PARAMETERS *volParams, vol
offset.QuadPart = TC_VOLUME_DATA_OFFSET + dataAreaSize;
- if (!SetFilePointerEx (dev, offset, NULL, FILE_BEGIN))
+ if (!MoveFilePointer (dev, offset))
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -639,7 +639,7 @@ int EncryptPartitionInPlaceBegin (volatile FORMAT_VOL_PARAMETERS *volParams, vol
offset.QuadPart += TC_HIDDEN_VOLUME_HEADER_OFFSET;
- if (!SetFilePointerEx (dev, offset, NULL, FILE_BEGIN))
+ if (!MoveFilePointer (dev, offset))
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -916,7 +916,7 @@ inplace_enc_read:
offset.QuadPart = masterCryptoInfo->EncryptedAreaStart.Value - workChunkSize - TC_VOLUME_DATA_OFFSET;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1007,14 +1007,14 @@ inplace_enc_read:
memcpy (wipeRandCharsUpdate, wipeBuffer, sizeof (wipeRandCharsUpdate));
}
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| WriteFile (dev, wipeBuffer, workChunkSize, &n, NULL) == 0)
{
// Write error
dwError = GetLastError();
// Undo failed write operation
- if (workChunkSize > TC_VOLUME_DATA_OFFSET && SetFilePointerEx (dev, offset, NULL, FILE_BEGIN))
+ if (workChunkSize > TC_VOLUME_DATA_OFFSET && MoveFilePointer (dev, offset))
{
DecryptDataUnits ((byte *) buf, &unitNo, workChunkSize / ENCRYPTION_DATA_UNIT_SIZE, masterCryptoInfo);
WriteFile (dev, buf + TC_VOLUME_DATA_OFFSET, workChunkSize - TC_VOLUME_DATA_OFFSET, &n, NULL);
@@ -1034,7 +1034,7 @@ inplace_enc_read:
offset.QuadPart = masterCryptoInfo->EncryptedAreaStart.Value - workChunkSize;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1046,7 +1046,7 @@ inplace_enc_read:
dwError = GetLastError();
// Undo failed write operation
- if (workChunkSize > TC_VOLUME_DATA_OFFSET && SetFilePointerEx (dev, offset, NULL, FILE_BEGIN))
+ if (workChunkSize > TC_VOLUME_DATA_OFFSET && MoveFilePointer (dev, offset))
{
DecryptDataUnits ((byte *) buf, &unitNo, workChunkSize / ENCRYPTION_DATA_UNIT_SIZE, masterCryptoInfo);
WriteFile (dev, buf + TC_VOLUME_DATA_OFFSET, workChunkSize - TC_VOLUME_DATA_OFFSET, &n, NULL);
@@ -1148,7 +1148,7 @@ inplace_enc_read:
offset.QuadPart = TC_VOLUME_HEADER_OFFSET;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| !WriteEffectiveVolumeHeader (TRUE, dev, (byte *) header))
{
nStatus = ERR_OS_ERROR;
@@ -1207,7 +1207,7 @@ inplace_enc_read:
offset.QuadPart += TC_HIDDEN_VOLUME_HEADER_OFFSET;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| !WriteEffectiveVolumeHeader (TRUE, dev, (byte *) header))
{
nStatus = ERR_OS_ERROR;
@@ -1544,7 +1544,7 @@ int DecryptPartitionInPlace (volatile FORMAT_VOL_PARAMETERS *volParams, volatile
offset.QuadPart = workChunkStartByteOffset;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1578,7 +1578,7 @@ int DecryptPartitionInPlace (volatile FORMAT_VOL_PARAMETERS *volParams, volatile
for (tmpSectorCount = workChunkSize / sectorSize; tmpSectorCount > 0; --tmpSectorCount)
{
- if (SetFilePointerEx (dev, tmpSectorOffset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, tmpSectorOffset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1640,7 +1640,7 @@ int DecryptPartitionInPlace (volatile FORMAT_VOL_PARAMETERS *volParams, volatile
offset.QuadPart = workChunkStartByteOffset - TC_VOLUME_DATA_OFFSET;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1724,7 +1724,7 @@ int DecryptPartitionInPlace (volatile FORMAT_VOL_PARAMETERS *volParams, volatile
offset.QuadPart <= deviceSize - sectorSize;
offset.QuadPart += sectorSize)
{
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -1864,7 +1864,7 @@ int FastVolumeHeaderUpdate (HANDLE dev, CRYPTO_INFO *headerCryptoInfo, CRYPTO_IN
offset.QuadPart = deviceSize - TC_VOLUME_HEADER_GROUP_SIZE;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| !ReadEffectiveVolumeHeader (TRUE, dev, header, &n) || n < TC_VOLUME_HEADER_EFFECTIVE_SIZE)
{
nStatus = ERR_OS_ERROR;
@@ -1913,7 +1913,7 @@ int FastVolumeHeaderUpdate (HANDLE dev, CRYPTO_INFO *headerCryptoInfo, CRYPTO_IN
EncryptBuffer (header + HEADER_ENCRYPTED_DATA_OFFSET, HEADER_ENCRYPTED_DATA_SIZE, pCryptoInfo);
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| !WriteEffectiveVolumeHeader (TRUE, dev, header))
{
nStatus = ERR_OS_ERROR;
@@ -2092,7 +2092,7 @@ static int ConcealNTFS (HANDLE dev)
offset.QuadPart = 0;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
return ERR_OS_ERROR;
if (ReadFile (dev, buf, TC_INITIAL_NTFS_CONCEAL_PORTION_SIZE, &nbrBytesProcessed, NULL) == 0)
@@ -2103,7 +2103,7 @@ static int ConcealNTFS (HANDLE dev)
offset.QuadPart = 0;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0)
+ if (MoveFilePointer (dev, offset) == 0)
return ERR_OS_ERROR;
if (WriteFile (dev, buf, TC_INITIAL_NTFS_CONCEAL_PORTION_SIZE, &nbrBytesProcessed, NULL) == 0)
@@ -2122,7 +2122,7 @@ static int ConcealNTFS (HANDLE dev)
{
Sleep (1);
}
- while (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ while (MoveFilePointer (dev, offset) == 0
|| WriteFile (dev, buf, TC_INITIAL_NTFS_CONCEAL_PORTION_SIZE, &nbrBytesProcessed2, NULL) == 0);
SetLastError (dwError);
@@ -2198,6 +2198,35 @@ BOOL SaveNonSysInPlaceEncSettings (int delta, WipeAlgorithmId newWipeAlgorithm,
return SaveBufferToFile (str, GetConfigPath (TC_APPD_FILENAME_NONSYS_INPLACE_ENC), (DWORD) strlen(str), FALSE, FALSE);
}
+// This function moves the file pointer to the given offset. It first retrieves the current
+// file position using SetFilePointerEx() with FILE_CURRENT as the reference point, and then
+// calculates the difference between the current position and the desired position. Subsequently,
+// it moves the file pointer by the difference calculated using SetFilePointerEx() again.
+//
+// This approach of moving the file pointer relatively (instead of absolutely) was implemented
+// as a workaround to address the performance issues related to in-place encryption. When using
+// SetFilePointerEx() with FILE_BEGIN as the reference point, reaching the end of large drives
+// during in-place encryption can cause significant slowdowns. By moving the file pointer
+// relatively, these performance issues are mitigated.
+BOOL MoveFilePointer (HANDLE dev, LARGE_INTEGER offset)
+{
+ LARGE_INTEGER currOffset;
+ LARGE_INTEGER diffOffset;
+
+ currOffset.QuadPart = 0;
+ if (SetFilePointerEx (dev, currOffset, &currOffset, FILE_CURRENT) == 0)
+ return FALSE;
+
+ diffOffset.QuadPart = offset.QuadPart - currOffset.QuadPart;
+ if (diffOffset.QuadPart == 0)
+ return TRUE;
+
+ // Moves the file pointer by the difference between current and desired positions
+ if (SetFilePointerEx (dev, diffOffset, NULL, FILE_CURRENT) == 0)
+ return FALSE;
+
+ return TRUE;
+}
// Repairs damaged sectors (i.e. those with read errors) by zeroing them.
// Note that this operating fails if there are any write errors.
@@ -2217,7 +2246,7 @@ int ZeroUnreadableSectors (HANDLE dev, LARGE_INTEGER startOffset, int64 size, in
if (!sectorBuffer)
return ERR_OUTOFMEMORY;
- if (SetFilePointerEx (dev, startOffset, NULL, FILE_BEGIN) == 0)
+ if (!MoveFilePointer(dev, workOffset))
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -2230,7 +2259,8 @@ int ZeroUnreadableSectors (HANDLE dev, LARGE_INTEGER startOffset, int64 size, in
{
memset (sectorBuffer, 0, sectorSize);
- if (SetFilePointerEx (dev, workOffset, NULL, FILE_BEGIN) == 0)
+ // If ReadFile failed, move back to start of the unreadable sector
+ if (MoveFilePointer (dev, workOffset) == 0)
{
nStatus = ERR_OS_ERROR;
goto closing_seq;
@@ -2281,7 +2311,7 @@ static int OpenBackupHeader (HANDLE dev, const wchar_t *devicePath, Password *pa
offset.QuadPart = deviceSize - TC_VOLUME_HEADER_GROUP_SIZE;
- if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+ if (MoveFilePointer (dev, offset) == 0
|| !ReadEffectiveVolumeHeader (TRUE, dev, (byte *) header, &n) || n < TC_VOLUME_HEADER_EFFECTIVE_SIZE)
{
nStatus = ERR_OS_ERROR;