-/*

- Derived from source code of TrueCrypt 7.1a, which is

- Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed

- by the TrueCrypt License 3.0.

-

- Modifications and additions to the original source code (contained in this file)

- and all other portions of this file are Copyright (c) 2013-2016 IDRIX

- and are governed by the Apache License 2.0 the full text of which is

- contained in the file License.txt included in VeraCrypt binary and source

- code distribution packages.

-*/

-

-#include "Bios.h"

-#include "BootConsoleIo.h"

-#include "BootConfig.h"

-#include "BootDebug.h"

-#include "BootDefs.h"

-#include "BootDiskIo.h"

-#include "BootStrings.h"

-

-

-byte SectorBuffer[TC_LB_SIZE];

-

-#ifdef TC_BOOT_DEBUG_ENABLED

-static bool SectorBufferInUse = false;

-

-void AcquireSectorBuffer ()

-{

- if (SectorBufferInUse)

- TC_THROW_FATAL_EXCEPTION;

-

- SectorBufferInUse = true;

-}

-

-

-void ReleaseSectorBuffer ()

-{

- SectorBufferInUse = false;

-}

-

-#endif

-

-

-bool IsLbaSupported (byte drive)

-{

- static byte CachedDrive = TC_INVALID_BIOS_DRIVE;

- static bool CachedStatus;

- uint16 result = 0;

-

- if (CachedDrive == drive)

- goto ret;

-

- __asm

- {

- mov bx, 0x55aa

- mov dl, drive

- mov ah, 0x41

- int 0x13

- jc err

- mov result, bx

- err:

- }

-

- CachedDrive = drive;

- CachedStatus = (result == 0xaa55);

-ret:

- return CachedStatus;

-}

-

-

-void PrintDiskError (BiosResult error, bool write, byte drive, const uint64 *sector, const ChsAddress *chs)

-{

- PrintEndl();

- Print (write ? "Write" : "Read"); Print (" error:");

- Print (error);

- Print (" Drive:");

- Print (drive ^ 0x80);

-

- if (sector)

- {

- Print (" Sector:");

- Print (*sector);

- }

-

- if (chs)

- {

- Print (" CHS:");

- Print (*chs);

- }

-

- PrintEndl();

- Beep();

-}

-

-

-void Print (const ChsAddress &chs)

-{

- Print (chs.Cylinder);

- PrintChar ('/');

- Print (chs.Head);

- PrintChar ('/');

- Print (chs.Sector);

-}

-

-

-void PrintSectorCountInMB (const uint64 &sectorCount)

-{

- Print (sectorCount >> (TC_LB_SIZE_BIT_SHIFT_DIVISOR + 2)); Print (" MB ");

-}

-

-

-BiosResult ReadWriteSectors (bool write, uint16 bufferSegment, uint16 bufferOffset, byte drive, const ChsAddress &chs, byte sectorCount, bool silent)

-{

- CheckStack();

-

- byte cylinderLow = (byte) chs.Cylinder;

- byte sector = chs.Sector;

- sector |= byte (chs.Cylinder >> 2) & 0xc0;

- byte function = write ? 0x03 : 0x02;

-

- BiosResult result;

- byte tryCount = TC_MAX_BIOS_DISK_IO_RETRIES;

-

- do

- {

- result = BiosResultSuccess;

-

- __asm

- {

- push es

- mov ax, bufferSegment

- mov es, ax

- mov bx, bufferOffset

- mov dl, drive

- mov ch, cylinderLow

- mov si, chs

- mov dh, [si].Head

- mov cl, sector

- mov al, sectorCount

- mov ah, function

- int 0x13

- jnc ok // If CF=0, ignore AH to prevent issues caused by potential bugs in BIOSes

- mov result, ah

- ok:

- pop es

- }

-

- if (result == BiosResultEccCorrected)

- result = BiosResultSuccess;

-

- // Some BIOSes report I/O errors prematurely in some cases

- } while (result != BiosResultSuccess && --tryCount != 0);

-

- if (!silent && result != BiosResultSuccess)

- PrintDiskError (result, write, drive, nullptr, &chs);

-

- return result;

-}

-

-

-BiosResult ReadWriteSectors (bool write, byte *buffer, byte drive, const ChsAddress &chs, byte sectorCount, bool silent)

-{

- uint16 codeSeg;

- __asm mov codeSeg, cs

- return ReadWriteSectors (write, codeSeg, (uint16) buffer, drive, chs, sectorCount, silent);

-}

-

-

-BiosResult ReadSectors (byte *buffer, byte drive, const ChsAddress &chs, byte sectorCount, bool silent)

-{

- return ReadWriteSectors (false, buffer, drive, chs, sectorCount, silent);

-}

-

-

-BiosResult WriteSectors (byte *buffer, byte drive, const ChsAddress &chs, byte sectorCount, bool silent)

-{

- return ReadWriteSectors (true, buffer, drive, chs, sectorCount, silent);

-}

-

-

-static BiosResult ReadWriteSectors (bool write, BiosLbaPacket &dapPacket, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- CheckStack();

-

- if (!IsLbaSupported (drive))

- {

- DriveGeometry geometry;

-

- BiosResult result = GetDriveGeometry (drive, geometry, silent);

- if (result != BiosResultSuccess)

- return result;

-

- ChsAddress chs;

- LbaToChs (geometry, sector, chs);

- return ReadWriteSectors (write, (uint16) (dapPacket.Buffer >> 16), (uint16) dapPacket.Buffer, drive, chs, sectorCount, silent);

- }

-

- dapPacket.Size = sizeof (dapPacket);

- dapPacket.Reserved = 0;

- dapPacket.SectorCount = sectorCount;

- dapPacket.Sector = sector;

-

- byte function = write ? 0x43 : 0x42;

-

- BiosResult result;

- byte tryCount = TC_MAX_BIOS_DISK_IO_RETRIES;

-

- do

- {

- result = BiosResultSuccess;

-

- __asm

- {

- mov bx, 0x55aa

- mov dl, drive

- mov si, [dapPacket]

- mov ah, function

- xor al, al

- int 0x13

- jnc ok // If CF=0, ignore AH to prevent issues caused by potential bugs in BIOSes

- mov result, ah

- ok:

- }

-

- if (result == BiosResultEccCorrected)

- result = BiosResultSuccess;

-

- // Some BIOSes report I/O errors prematurely in some cases

- } while (result != BiosResultSuccess && --tryCount != 0);

-

- if (!silent && result != BiosResultSuccess)

- PrintDiskError (result, write, drive, &sector);

-

- return result;

-}

-

-

-static BiosResult ReadWriteSectors (bool write, byte *buffer, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- BiosLbaPacket dapPacket;

- dapPacket.Buffer = (uint32) buffer;

- return ReadWriteSectors (write, dapPacket, drive, sector, sectorCount, silent);

-}

-

-

-BiosResult ReadWriteSectors (bool write, uint16 bufferSegment, uint16 bufferOffset, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- BiosLbaPacket dapPacket;

- dapPacket.Buffer = ((uint32) bufferSegment << 16) | bufferOffset;

- return ReadWriteSectors (write, dapPacket, drive, sector, sectorCount, silent);

-}

-

-BiosResult ReadSectors (uint16 bufferSegment, uint16 bufferOffset, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- return ReadWriteSectors (false, bufferSegment, bufferOffset, drive, sector, sectorCount, silent);

-}

-

-

-BiosResult ReadSectors (byte *buffer, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- BiosResult result;

- uint16 codeSeg;

- __asm mov codeSeg, cs

-

- result = ReadSectors (BootStarted ? codeSeg : TC_BOOT_LOADER_ALT_SEGMENT, (uint16) buffer, drive, sector, sectorCount, silent);

-

- // Alternative segment is used to prevent memory corruption caused by buggy BIOSes

- if (!BootStarted)

- CopyMemory (TC_BOOT_LOADER_ALT_SEGMENT, (uint16) buffer, buffer, sectorCount * TC_LB_SIZE);

-

- return result;

-}

-

-

-BiosResult WriteSectors (byte *buffer, byte drive, const uint64 &sector, uint16 sectorCount, bool silent)

-{

- return ReadWriteSectors (true, buffer, drive, sector, sectorCount, silent);

-}

-

-

-BiosResult GetDriveGeometry (byte drive, DriveGeometry &geometry, bool silent)

-{

- CheckStack();

-

- byte maxCylinderLow, maxHead, maxSector;

- BiosResult result;

- __asm

- {

- push es

- mov dl, drive

- mov ah, 0x08

- int 0x13

-

- mov result, ah

- mov maxCylinderLow, ch

- mov maxSector, cl

- mov maxHead, dh

- pop es

- }

-

- if (result == BiosResultSuccess)

- {

- geometry.Cylinders = (maxCylinderLow | (uint16 (maxSector & 0xc0) << 2)) + 1;

- geometry.Heads = maxHead + 1;

- geometry.Sectors = maxSector & ~0xc0;

- }

- else if (!silent)

- {

- Print ("Drive ");

- Print (drive ^ 0x80);

- Print (" not found: ");

- PrintErrorNoEndl ("");

- Print (result);

- PrintEndl();

- }

-

- return result;

-}

-

-

-void ChsToLba (const DriveGeometry &geometry, const ChsAddress &chs, uint64 &lba)

-{

- lba.HighPart = 0;

- lba.LowPart = (uint32 (chs.Cylinder) * geometry.Heads + chs.Head) * geometry.Sectors + chs.Sector - 1;

-}

-

-

-void LbaToChs (const DriveGeometry &geometry, const uint64 &lba, ChsAddress &chs)

-{

- chs.Sector = (byte) ((lba.LowPart % geometry.Sectors) + 1);

- uint32 ch = lba.LowPart / geometry.Sectors;

- chs.Head = (byte) (ch % geometry.Heads);

- chs.Cylinder = (uint16) (ch / geometry.Heads);

-}

-

-

-void PartitionEntryMBRToPartition (const PartitionEntryMBR &partEntry, Partition &partition)

-{

- partition.Active = partEntry.BootIndicator == 0x80;

- partition.EndSector.HighPart = 0;

- partition.EndSector.LowPart = partEntry.StartLBA + partEntry.SectorCountLBA - 1;

- partition.SectorCount.HighPart = 0;

- partition.SectorCount.LowPart = partEntry.SectorCountLBA;

- partition.StartSector.HighPart = 0;

- partition.StartSector.LowPart = partEntry.StartLBA;

- partition.Type = partEntry.Type;

-}

-

-

-BiosResult ReadWriteMBR (bool write, byte drive, bool silent)

-{

- uint64 mbrSector;

- mbrSector.HighPart = 0;

- mbrSector.LowPart = 0;

-

- if (write)

- return WriteSectors (SectorBuffer, drive, mbrSector, 1, silent);

-

- return ReadSectors (SectorBuffer, drive, mbrSector, 1, silent); // Uses alternative segment

-}

-

-

-BiosResult GetDrivePartitions (byte drive, Partition *partitionArray, size_t partitionArrayCapacity, size_t &partitionCount, bool activeOnly, Partition *findPartitionFollowingThis, bool silent)

-{

- Partition *followingPartition;

- Partition tmpPartition;

-

- if (findPartitionFollowingThis)

- {

- assert (partitionArrayCapacity == 1);

- partitionArrayCapacity = 0xff;

- followingPartition = partitionArray;

- partitionArray = &tmpPartition;

-

- followingPartition->Drive = TC_INVALID_BIOS_DRIVE;

- followingPartition->StartSector.LowPart = 0xFFFFffffUL;

- }

-

- AcquireSectorBuffer();

- BiosResult result = ReadWriteMBR (false, drive, silent);

- ReleaseSectorBuffer();

-

- partitionCount = 0;

-

- MBR *mbr = (MBR *) SectorBuffer;

- if (result != BiosResultSuccess || mbr->Signature != 0xaa55)

- return result;

-

- PartitionEntryMBR mbrPartitions[4];

- memcpy (mbrPartitions, mbr->Partitions, sizeof (mbrPartitions));

- size_t partitionArrayPos = 0, partitionNumber;

-

- for (partitionNumber = 0;

- partitionNumber < array_capacity (mbrPartitions) && partitionArrayPos < partitionArrayCapacity;

- ++partitionNumber)

- {

- const PartitionEntryMBR &partEntry = mbrPartitions[partitionNumber];

-

- if (partEntry.SectorCountLBA > 0)

- {

- Partition &partition = partitionArray[partitionArrayPos];

- PartitionEntryMBRToPartition (partEntry, partition);

-

- if (activeOnly && !partition.Active)

- continue;

-

- partition.Drive = drive;

- partition.Number = partitionArrayPos;

-

- if (partEntry.Type == 0x5 || partEntry.Type == 0xf) // Extended partition

- {

- if (IsLbaSupported (drive))

- {

- // Find all extended partitions

- uint64 firstExtStartLBA = partition.StartSector;

- uint64 extStartLBA = partition.StartSector;

- MBR *extMbr = (MBR *) SectorBuffer;

-

- while (partitionArrayPos < partitionArrayCapacity &&

- (result = ReadSectors ((byte *) extMbr, drive, extStartLBA, 1, silent)) == BiosResultSuccess

- && extMbr->Signature == 0xaa55)

- {

- if (extMbr->Partitions[0].SectorCountLBA > 0)

- {

- Partition &logPart = partitionArray[partitionArrayPos];

- PartitionEntryMBRToPartition (extMbr->Partitions[0], logPart);

- logPart.Drive = drive;

-

- logPart.Number = partitionArrayPos;

- logPart.Primary = false;

-

- logPart.StartSector.LowPart += extStartLBA.LowPart;

- logPart.EndSector.LowPart += extStartLBA.LowPart;

-

- if (findPartitionFollowingThis)

- {

- if (logPart.StartSector.LowPart > findPartitionFollowingThis->EndSector.LowPart

- && logPart.StartSector.LowPart < followingPartition->StartSector.LowPart)

- {

- *followingPartition = logPart;

- }

- }

- else

- ++partitionArrayPos;

- }

-

- // Secondary extended

- if (extMbr->Partitions[1].Type != 0x5 && extMbr->Partitions[1].Type == 0xf

- || extMbr->Partitions[1].SectorCountLBA == 0)

- break;

-

- extStartLBA.LowPart = extMbr->Partitions[1].StartLBA + firstExtStartLBA.LowPart;

- }

- }

- }

- else

- {

- partition.Primary = true;

-

- if (findPartitionFollowingThis)

- {

- if (partition.StartSector.LowPart > findPartitionFollowingThis->EndSector.LowPart

- && partition.StartSector.LowPart < followingPartition->StartSector.LowPart)

- {

- *followingPartition = partition;

- }

- }

- else

- ++partitionArrayPos;

- }

- }

- }

-

- partitionCount = partitionArrayPos;

- return result;

-}

-

-

-bool GetActivePartition (byte drive)

-{

- size_t partCount;

-

- if (GetDrivePartitions (drive, &ActivePartition, 1, partCount, true) != BiosResultSuccess || partCount < 1)

- {

- ActivePartition.Drive = TC_INVALID_BIOS_DRIVE;

- PrintError (TC_BOOT_STR_NO_BOOT_PARTITION);

- return false;

- }

-

- return true;

-}