From 22466535f1b9cbe1bd98363cfa98f7f796bc408a Mon Sep 17 00:00:00 2001 From: Mounir IDRASSI Date: Sun, 4 Jun 2023 16:25:55 +0200 Subject: 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. --- src/Format/InPlace.c | 72 +++++++++++++++++++++++++++++++++++++--------------- src/Format/InPlace.h | 1 + 2 files changed, 52 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; diff --git a/src/Format/InPlace.h b/src/Format/InPlace.h index 717a8ed3..f2d97bed 100644 --- a/src/Format/InPlace.h +++ b/src/Format/InPlace.h @@ -43,6 +43,7 @@ static int DismountFileSystem (HWND hwndDlg, HANDLE dev, int driveLetter, BOOL b static int ConcealNTFS (HANDLE dev); BOOL SaveNonSysInPlaceEncSettings (int delta, WipeAlgorithmId wipeAlgorithm, BOOL bDecrypting); static void ExportProgressStats (__int64 bytesDone, __int64 totalSize); +BOOL MoveFilePointer (HANDLE dev, LARGE_INTEGER offset); int ZeroUnreadableSectors (HANDLE dev, LARGE_INTEGER startOffset, int64 size, int sectorSize, uint64 *zeroedSectorCount); static int OpenBackupHeader (HANDLE dev, const wchar_t *devicePath, Password *password, int pkcs5, int pim, PCRYPTO_INFO *retCryptoInfo, CRYPTO_INFO *headerCryptoInfo, __int64 deviceSize); BOOL MoveClustersBeforeThreshold (HANDLE volumeHandle, PWSTR volumeDevicePath, int64 clusterThreshold); -- cgit v1.2.3