bootmain.cpp

外国开源的硬盘加密软件

/*
 Copyright (c) 2008-2009 TrueCrypt Foundation. All rights reserved.

 Governed by the TrueCrypt License 2.6 the full text of which is contained
 in the file License.txt included in TrueCrypt binary and source code
 distribution packages.
*/

#include "Crc.h"
#include "Crypto.h"
#include "Password.h"
#include "Volumes.h"

#include "Platform.h"
#include "Bios.h"
#include "BootConfig.h"
#include "BootMain.h"
#include "BootDefs.h"
#include "BootCommon.h"
#include "BootConsoleIo.h"
#include "BootDebug.h"
#include "BootDiskIo.h"
#include "BootEncryptedIo.h"
#include "BootMemory.h"
#include "BootStrings.h"
#include "IntFilter.h"


static void InitScreen ()
{
	ClearScreen();

	const char *title =
#ifndef TC_WINDOWS_BOOT_RESCUE_DISK_MODE
		" TrueCrypt Boot Loader "
#else
		" TrueCrypt Rescue Disk "
#endif
		VERSION_STRING;

	Print (title);
	PrintRepeatedChar (' ', title[26] ? 8 : 9);
	Print ("Copyright (C) 2008-2009 TrueCrypt Foundation\r\n");

	PrintRepeatedChar ('\xDC', TC_BIOS_MAX_CHARS_PER_LINE);

#ifndef TC_WINDOWS_BOOT_RESCUE_DISK_MODE
	if (CustomUserMessage[0])
	{
		PrintEndl();
		Print (CustomUserMessage);
	}
#endif

	PrintEndl (2);
}


static void PrintMainMenu ()
{
	if (PreventBootMenu)
		return;

	Print ("    Keyboard Controls:\r\n");
	Print ("    [Esc]  ");

#ifndef TC_WINDOWS_BOOT_RESCUE_DISK_MODE

	Print ((BootSectorFlags & TC_BOOT_CFG_MASK_HIDDEN_OS_CREATION_PHASE) != TC_HIDDEN_OS_CREATION_PHASE_NONE
		? "Boot Non-Hidden System (Boot Manager)"
		: "Skip Authentication (Boot Manager)");
	
#else // TC_WINDOWS_BOOT_RESCUE_DISK_MODE

	Print ("Skip Authentication (Boot Manager)");
	Print ("\r\n    [F8]   "); Print ("Repair Options");

#endif // TC_WINDOWS_BOOT_RESCUE_DISK_MODE

	PrintEndl (3);
}


static bool IsMenuKey (byte scanCode)
{
#ifdef TC_WINDOWS_BOOT_RESCUE_DISK_MODE
	return scanCode == TC_MENU_KEY_REPAIR;
#else
	return false;
#endif
}


static bool AskYesNo (const char *message)
{
	Print (message);
	Print ("? (y/n): ");
	while (true)
	{
		switch (GetKeyboardChar())
		{
		case 'y':
		case 'Y':
		case 'z':
		case 'Z':
			Print ("y\r\n");
			return true;

		case 'n':
		case 'N':
			Print ("n\r\n");
			return false;

		default:
			Beep();
		}
	}
}


static int AskSelection (const char *options[], size_t optionCount)
{
	for (int i = 0; i < optionCount; ++i)
	{
		Print ("["); Print (i + 1); Print ("]    ");
		Print (options[i]);
		PrintEndl();
	}
	Print ("[Esc]  Cancel\r\n\r\n");

	Print ("To select, press 1-9: ");

	char str;

	while (true)
	{
		if (GetString (&str, 1) == 0)
			return 0;

		if (str >= '1' && str <= optionCount + '0')
			return str - '0';

		Beep();
		PrintBackspace();
	}
}


static byte AskPassword (Password &password)
{
	size_t pos = 0;
	byte scanCode;
	byte asciiCode;

	Print ("Enter password");
	Print (PreventNormalSystemBoot ? " for hidden system:\r\n" : ": ");

	while (true)
	{
		asciiCode = GetKeyboardChar (&scanCode);

		switch (scanCode)
		{
		case TC_BIOS_KEY_ENTER:
			ClearBiosKeystrokeBuffer();
			PrintEndl();

			password.Length = pos;
			return scanCode;

		case TC_BIOS_KEY_BACKSPACE:
			if (pos > 0)
			{
				if (pos < MAX_PASSWORD)
					PrintBackspace();
				else
					PrintCharAtCursor (' ');

				--pos;
			}
			continue;

		default:
			if (scanCode == TC_BIOS_KEY_ESC || IsMenuKey (scanCode))
			{
				burn (password.Text, sizeof (password.Text));
				ClearBiosKeystrokeBuffer();

				PrintEndl();
				return scanCode;
			}
		}

		if (!IsPrintable (asciiCode) || pos == MAX_PASSWORD)
		{
			Beep();
			continue;
		}

		password.Text[pos++] = asciiCode;
		if (pos < MAX_PASSWORD)
			PrintChar ('*');
		else
			PrintCharAtCursor ('*');
	}
}


static void ExecuteBootSector (byte drive, byte *sectorBuffer)
{
	Print ("Booting...\r\n");
	CopyMemory (sectorBuffer, 0x0000, 0x7c00, TC_LB_SIZE);

	BootStarted = true;

	uint32 addr = 0x7c00;
	__asm
	{
		cli
		mov dl, drive	// Boot drive
		mov dh, 0
		xor ax, ax
		mov si, ax
		mov ds, ax
		mov es, ax
		mov ss, ax
		mov sp, 0x7c00
		sti

		jmp cs:addr
	}
}


static bool OpenVolume (byte drive, Password &password, CRYPTO_INFO **cryptoInfo, uint32 *headerSaltCrc32, bool skipNormal, bool skipHidden)
{
	int volumeType;
	bool hiddenVolume;
	uint64 headerSec;
	
	AcquireSectorBuffer();

	for (volumeType = 1; volumeType <= 2; ++volumeType)
	{
		hiddenVolume = (volumeType == 2);

		if (hiddenVolume)
		{
			if (skipHidden || PartitionFollowingActive.Drive != drive || PartitionFollowingActive.SectorCount <= ActivePartition.SectorCount)
				continue;

			headerSec = PartitionFollowingActive.StartSector + TC_HIDDEN_VOLUME_HEADER_OFFSET / TC_LB_SIZE;
		}
		else
		{
			if (skipNormal)
				continue;

			headerSec.HighPart = 0;
			headerSec.LowPart = TC_BOOT_VOLUME_HEADER_SECTOR;
		}

		if (ReadSectors (SectorBuffer, drive, headerSec, 1) != BiosResultSuccess)
			continue;

		if (ReadVolumeHeader (!hiddenVolume, (char *) SectorBuffer, &password, cryptoInfo, nullptr) == ERR_SUCCESS)
		{
			// Prevent opening a non-system hidden volume
			if (hiddenVolume && !((*cryptoInfo)->HeaderFlags & TC_HEADER_FLAG_ENCRYPTED_SYSTEM))
			{
				crypto_close (*cryptoInfo);
				continue;
			}

			if (headerSaltCrc32)
				*headerSaltCrc32 = GetCrc32 (SectorBuffer, PKCS5_SALT_SIZE);

			break;
		}
	}

	ReleaseSectorBuffer();
	return volumeType != 3;
}


static bool CheckMemoryRequirements ()
{
	uint16 codeSeg;
	__asm mov codeSeg, cs
	if (codeSeg == TC_BOOT_LOADER_LOWMEM_SEGMENT)
	{
		PrintError ("BIOS reserved too much memory: ", true, false);

		uint16 memFree;
		__asm
		{
			push es
			xor ax, ax
			mov es, ax
			mov ax, es:[0x413]
			mov memFree, ax
			pop es
		}

		Print (memFree);
		PrintEndl();
		Print (TC_BOOT_STR_UPGRADE_BIOS);

		return false;
	}

	return true;
}


static bool MountVolume (byte drive, byte &exitKey, bool skipNormal, bool skipHidden)
{
	BootArguments *bootArguments = (BootArguments *) TC_BOOT_LOADER_ARGS_OFFSET;
	int incorrectPasswordCount = 0;

	EraseMemory (bootArguments, sizeof (*bootArguments));

	// Open volume header
	while (true)
	{
		exitKey = AskPassword (bootArguments->BootPassword);

		if (exitKey != TC_BIOS_KEY_ENTER)
			return false;

		if (OpenVolume (BootDrive, bootArguments->BootPassword, &BootCryptoInfo, &bootArguments->HeaderSaltCrc32, skipNormal, skipHidden))
			break;

		if (GetShiftFlags() & TC_BIOS_SHIFTMASK_CAPSLOCK)
			Print ("Warning: Caps Lock is on.\r\n");

		Print ("Incorrect password.\r\n\r\n");

		if (++incorrectPasswordCount == 4)
		{
#ifdef TC_WINDOWS_BOOT_RESCUE_DISK_MODE
			Print ("The key data may be damaged. Use 'Repair Options' > 'Restore key data'.\r\n\r\n");
#else
			Print ("If you are sure the password is correct, the key data may be damaged. Boot your\r\n"
				   "TrueCrypt Rescue Disk and select 'Repair Options' > 'Restore key data'.\r\n\r\n");
#endif
		}
	}

	// Setup boot arguments
	bootArguments->BootLoaderVersion = VERSION_NUM;
	bootArguments->CryptoInfoOffset = (uint16) BootCryptoInfo;
	bootArguments->CryptoInfoLength = sizeof (*BootCryptoInfo);
	
	if (BootCryptoInfo->hiddenVolume)
		bootArguments->HiddenSystemPartitionStart = PartitionFollowingActive.StartSector << TC_LB_SIZE_BIT_SHIFT_DIVISOR;

	TC_SET_BOOT_ARGUMENTS_SIGNATURE	(bootArguments->Signature);

	// Setup virtual encrypted partition
	if (BootCryptoInfo->EncryptedAreaLength.HighPart != 0 || BootCryptoInfo->EncryptedAreaLength.LowPart != 0)
	{
		EncryptedVirtualPartition.Drive = BootDrive;

		EncryptedVirtualPartition.StartSector = BootCryptoInfo->EncryptedAreaStart >> TC_LB_SIZE_BIT_SHIFT_DIVISOR;
		
		HiddenVolumeStartUnitNo = EncryptedVirtualPartition.StartSector;
		HiddenVolumeStartSector = PartitionFollowingActive.StartSector;
		HiddenVolumeStartSector += EncryptedVirtualPartition.StartSector;

		EncryptedVirtualPartition.SectorCount = BootCryptoInfo->EncryptedAreaLength >> TC_LB_SIZE_BIT_SHIFT_DIVISOR;

		EncryptedVirtualPartition.EndSector = EncryptedVirtualPartition.SectorCount - 1;
		EncryptedVirtualPartition.EndSector += EncryptedVirtualPartition.StartSector;
	}
	else
	{
		// Drive not encrypted
		EncryptedVirtualPartition.Drive = TC_INVALID_BIOS_DRIVE;
	}

	return true;
}


static byte BootEncryptedDrive ()
{
	BootArguments *bootArguments = (BootArguments *) TC_BOOT_LOADER_ARGS_OFFSET;
	byte exitKey;
	BootCryptoInfo = NULL;

	if (!GetActiveAndFollowingPartition (BootDrive))
		goto err;

	if (!MountVolume (BootDrive, exitKey, PreventNormalSystemBoot, false))
		return exitKey;
	
	if (!CheckMemoryRequirements ())
		goto err;

	if (BootCryptoInfo->hiddenVolume)
	{
		EncryptedVirtualPartition = ActivePartition;
		bootArguments->DecoySystemPartitionStart = ActivePartition.StartSector << TC_LB_SIZE_BIT_SHIFT_DIVISOR;
	}

	if (!InstallInterruptFilters())
		goto err;

	bootArguments->BootArgumentsCrc32 = GetCrc32 ((byte *) bootArguments, (byte *) &bootArguments->BootArgumentsCrc32 - (byte *) bootArguments);

	while (true)
	{
		// Execute boot sector of the active partition
		if (ReadSectors (SectorBuffer, ActivePartition.Drive, ActivePartition.StartSector, 1) == BiosResultSuccess)
		{
			if (*(uint16 *) (SectorBuffer + 510) != 0xaa55)
			{
				PrintError (TC_BOOT_STR_NO_BOOT_PARTITION);
				GetKeyboardChar();
			}

			ExecuteBootSector (ActivePartition.Drive, SectorBuffer);
		}

		GetKeyboardChar();
	}

err:
	if (BootCryptoInfo)
	{
		crypto_close (BootCryptoInfo);
		BootCryptoInfo = NULL;
	}

	EncryptedVirtualPartition.Drive = TC_INVALID_BIOS_DRIVE;
	EraseMemory ((void *) TC_BOOT_LOADER_ARGS_OFFSET, sizeof (BootArguments));

	byte scanCode;
	GetKeyboardChar (&scanCode);
	return scanCode;
}


static void BootMenu ()
{
	BiosResult result;
	Partition partitions[16];
	Partition bootablePartitions[9];
	size_t partitionCount;
	size_t bootablePartitionCount = 0;

	for (byte drive = TC_FIRST_BIOS_DRIVE; drive <= TC_LAST_BIOS_DRIVE; ++drive)
	{
		if (GetDrivePartitions (drive, partitions, array_capacity (partitions), partitionCount, false, nullptr, true) == BiosResultSuccess)
		{
			for (size_t i = 0; i < partitionCount; ++i)
			{
				const Partition &partition = partitions[i];
				result = ReadSectors (SectorBuffer, drive, partition.StartSector, 1);

				if (result == BiosResultSuccess && *(uint16 *) (SectorBuffer + TC_LB_SIZE - 2) == 0xaa55)
				{
					// Windows writes boot loader on all NTFS/FAT filesytems it creates and, therefore,
					// NTFS/FAT partitions must have the boot indicator set to be considered bootable.
					if (!partition.Active
						&& (*(uint32 *) (SectorBuffer + 3) == 0x5346544e  // 'NTFS'
							|| *(uint32 *) (SectorBuffer + 3) == 0x41465845	&& SectorBuffer[7] == 'T' // 'exFAT'
							|| *(uint16 *) (SectorBuffer + 54) == 0x4146 && SectorBuffer[56] == 'T' // 'FAT'
							|| *(uint16 *) (SectorBuffer + 82) == 0x4146 && SectorBuffer[84] == 'T'))
					{
						continue;
					}

					// Bootable sector found
					if (bootablePartitionCount < array_capacity (bootablePartitions))
						bootablePartitions[bootablePartitionCount++] = partition;
				}
			}
		}
	}

	if (bootablePartitionCount < 1)
	{
		PrintError (TC_BOOT_STR_NO_BOOT_PARTITION);
		GetKeyboardChar();
		return;
	}

	char partChar;
	while (true)
	{
		InitScreen();
		Print ("Bootable Partitions:\r\n");
		PrintRepeatedChar ('\xC4', 20);
		Print ("\r\n");

		for (size_t i = 0; i < bootablePartitionCount; ++i)
		{
			const Partition &partition = bootablePartitions[i];
			Print ("["); Print (i + 1); Print ("]    ");
			Print ("Drive: "); Print (partition.Drive - TC_FIRST_BIOS_DRIVE);
			Print (", Partition: "); Print (partition.Number + 1);
			Print (", Size: "); PrintSectorCountInMB (partition.SectorCount); PrintEndl();
		}

		if (bootablePartitionCount == 1)
		{
			// There's only one bootable partition so we'll boot it directly instead of showing boot manager
			partChar = '1';
		}
		else
		{
			Print ("[Esc]  Cancel\r\n\r\n");
			Print ("Press 1-9 to select partition: ");

			if (GetString (&partChar, 1) == 0)
				return;

			PrintEndl();

			if (partChar < '1' || partChar > '0' + bootablePartitionCount)
			{
				Beep();
				continue;
			}
		}

		const Partition &partition = bootablePartitions[partChar - '0' - 1];

		if (ReadSectors (SectorBuffer, partition.Drive, partition.StartSector, 1) == BiosResultSuccess)
		{
			ExecuteBootSector (partition.Drive, SectorBuffer);
		}
	}
}


#ifndef TC_WINDOWS_BOOT_RESCUE_DISK_MODE

static bool CopyActivePartitionToHiddenVolume (byte drive, byte &exitKey)
{
	bool status = false;

	uint64 sectorsRemaining;
	uint64 sectorOffset;
	sectorOffset.LowPart = 0;