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/*
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) 2013-2017 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 "Platform.h"
#include "BootMemory.h"
#include "BootConfig.h"
#include "BootConsoleIo.h"
#include "BootDebug.h"
#include "BootDefs.h"
#include "BootDiskIo.h"
#include "BootEncryptedIo.h"
#include "BootStrings.h"
#include "IntFilter.h"
static uint32 OriginalInt13Handler;
static uint32 OriginalInt15Handler;
static Registers IntRegisters;
bool Int13Filter ()
{
CheckStack();
Registers regs;
memcpy (®s, &IntRegisters, sizeof (regs));
__asm sti
static int ReEntryCount = -1;
++ReEntryCount;
byte function = (byte) (regs.AX >> 8);
#ifdef TC_TRACE_INT13
DisableScreenOutput();
PrintHex (function);
Print (" EN:"); Print (ReEntryCount);
Print (" SS:"); PrintHex (regs.SS);
uint16 spdbg;
__asm mov spdbg, sp
PrintChar (' ');
PrintHex (spdbg);
PrintChar ('<'); PrintHex (TC_BOOT_LOADER_STACK_TOP);
#endif
bool passOriginalRequest = true;
switch (function)
{
case 0x2: // Read sectors
case 0x3: // Write sectors
{
byte drive = (byte) regs.DX;
ChsAddress chs;
chs.Cylinder = ((regs.CX << 2) & 0x300) | (regs.CX >> 8);
chs.Head = regs.DX >> 8;
chs.Sector = regs.CX & 0x3f;
byte sectorCount = (byte) regs.AX;
#ifdef TC_TRACE_INT13
PrintVal (": Drive", drive - TC_FIRST_BIOS_DRIVE, false);
Print (" Chs: "); Print (chs);
#endif
uint64 sector;
if (drive == BootDrive)
{
if (!BootDriveGeometryValid)
TC_THROW_FATAL_EXCEPTION;
ChsToLba (BootDriveGeometry, chs, sector);
#ifdef TC_TRACE_INT13
PrintVal (" Sec", sector.LowPart, false);
#endif
}
#ifdef TC_TRACE_INT13
PrintVal (" Count", sectorCount, false);
Print (" Buf: "); PrintHex (regs.ES); PrintChar (':'); PrintHex (regs.BX);
PrintEndl();
#endif
if (ReEntryCount == 0 && drive == EncryptedVirtualPartition.Drive)
{
BiosResult result;
if (function == 0x3)
result = WriteEncryptedSectors (regs.ES, regs.BX, drive, sector, sectorCount);
else
result = ReadEncryptedSectors (regs.ES, regs.BX, drive, sector, sectorCount);
__asm cli
memcpy (&IntRegisters, ®s, sizeof (regs));
IntRegisters.AX = (uint16) result << 8;
if (result == BiosResultSuccess)
{
IntRegisters.AX |= sectorCount;
IntRegisters.Flags &= ~TC_X86_CARRY_FLAG;
}
else
IntRegisters.Flags |= TC_X86_CARRY_FLAG;
passOriginalRequest = false;
}
}
break;
case 0x42: // Read sectors LBA
case 0x43: // Write sectors LBA
{
byte drive = (byte) regs.DX;
BiosLbaPacket lba;
CopyMemory (regs.DS, regs.SI, (byte *) &lba, sizeof (lba));
#ifdef TC_TRACE_INT13
PrintVal (": Drive", drive - TC_FIRST_BIOS_DRIVE, false);
PrintVal (" Sec", lba.Sector.LowPart, false);
PrintVal (" Count", lba.SectorCount, false);
PrintVal (" Buf", lba.Buffer, false, true);
PrintEndl();
#endif
if (ReEntryCount == 0 && drive == EncryptedVirtualPartition.Drive)
{
BiosResult result;
uint16 segment = (uint16) (lba.Buffer >> 16);
uint16 offset = (uint16) lba.Buffer;
if (function == 0x43)
result = WriteEncryptedSectors (segment, offset, drive, lba.Sector, lba.SectorCount);
else
result = ReadEncryptedSectors (segment, offset, drive, lba.Sector, lba.SectorCount);
__asm cli
memcpy (&IntRegisters, ®s, sizeof (regs));
IntRegisters.AX = (IntRegisters.AX & 0xff) | ((uint16) result << 8);
if (result == BiosResultSuccess)
IntRegisters.Flags &= ~TC_X86_CARRY_FLAG;
else
IntRegisters.Flags |= TC_X86_CARRY_FLAG;
passOriginalRequest = false;
}
}
break;
default:
#ifdef TC_TRACE_INT13
PrintEndl();
#endif
break;
}
#ifdef TC_TRACE_INT13
EnableScreenOutput();
#endif
--ReEntryCount;
return passOriginalRequest;
}
#define TC_MAX_MEMORY_MAP_SIZE 80
BiosMemoryMapEntry BiosMemoryMap[TC_MAX_MEMORY_MAP_SIZE];
static size_t BiosMemoryMapSize;
static void CreateBootLoaderMemoryMapEntry (BiosMemoryMapEntry *newMapEntry, uint32 bootLoaderStart)
{
newMapEntry->Type = 0x2;
newMapEntry->BaseAddress.HighPart = 0;
newMapEntry->BaseAddress.LowPart = bootLoaderStart;
newMapEntry->Length.HighPart = 0;
newMapEntry->Length.LowPart = TC_BOOT_MEMORY_REQUIRED * 1024UL;
}
static bool CreateNewBiosMemoryMap ()
{
// Create a new BIOS memory map presenting the memory area of the loader as reserved
BiosMemoryMapSize = 0;
BiosMemoryMapEntry entry;
BiosMemoryMapEntry *newMapEntry = BiosMemoryMap;
const BiosMemoryMapEntry *mapEnd = BiosMemoryMap + TC_MAX_MEMORY_MAP_SIZE;
uint64 bootLoaderStart;
bootLoaderStart.HighPart = 0;
uint16 codeSeg;
__asm mov codeSeg, cs
bootLoaderStart.LowPart = GetLinearAddress (codeSeg, 0);
uint64 bootLoaderEnd;
bootLoaderEnd.HighPart = 0;
bootLoaderEnd.LowPart = bootLoaderStart.LowPart + TC_BOOT_MEMORY_REQUIRED * 1024UL;
bool loaderEntryInserted = false;
if (GetFirstBiosMemoryMapEntry (entry))
{
do
{
uint64 entryEnd = entry.BaseAddress + entry.Length;
if (entry.Type == 0x1 && RegionsIntersect (bootLoaderStart, TC_BOOT_MEMORY_REQUIRED * 1024UL, entry.BaseAddress, entryEnd - 1))
{
// Free map entry covers the boot loader area
if (entry.BaseAddress < bootLoaderStart)
{
// Create free entry below the boot loader area
if (newMapEntry >= mapEnd)
goto mapOverflow;
*newMapEntry = entry;
newMapEntry->Length = bootLoaderStart - entry.BaseAddress;
++newMapEntry;
}
if (!loaderEntryInserted)
{
// Create reserved entry for the boot loader if it has not been done yet
if (newMapEntry >= mapEnd)
goto mapOverflow;
CreateBootLoaderMemoryMapEntry (newMapEntry, bootLoaderStart.LowPart);
++newMapEntry;
loaderEntryInserted = true;
}
if (bootLoaderEnd < entryEnd)
{
// Create free entry above the boot loader area
if (newMapEntry >= mapEnd)
goto mapOverflow;
newMapEntry->Type = 0x1;
newMapEntry->BaseAddress = bootLoaderEnd;
newMapEntry->Length = entryEnd - bootLoaderEnd;
++newMapEntry;
}
}
else
{
if (newMapEntry >= mapEnd)
goto mapOverflow;
if (!loaderEntryInserted && entry.BaseAddress > bootLoaderStart)
{
// Create reserved entry for the boot loader if it has not been done yet
CreateBootLoaderMemoryMapEntry (newMapEntry, bootLoaderStart.LowPart);
++newMapEntry;
loaderEntryInserted = true;
}
// Copy map entry
*newMapEntry++ = entry;
}
} while (GetNextBiosMemoryMapEntry (entry));
}
BiosMemoryMapSize = newMapEntry - BiosMemoryMap;
return true;
mapOverflow:
size_t overSize = 0;
while (GetNextBiosMemoryMapEntry (entry))
{
++overSize;
}
PrintErrorNoEndl ("MMP:");
Print (overSize);
PrintEndl();
return false;
}
bool Int15Filter ()
{
CheckStack();
#ifdef TC_TRACE_INT15
DisableScreenOutput();
Print ("15-");
PrintHex (IntRegisters.AX);
Print (" SS:"); PrintHex (IntRegisters.SS);
uint16 spdbg;
__asm mov spdbg, sp
PrintChar (' ');
PrintHex (spdbg);
PrintChar ('<'); PrintHex (TC_BOOT_LOADER_STACK_TOP);
Print (" EAX:"); PrintHex (IntRegisters.EAX);
Print (" EBX:"); PrintHex (IntRegisters.EBX);
Print (" ECX:"); PrintHex (IntRegisters.ECX);
Print (" EDX:"); PrintHex (IntRegisters.EDX);
Print (" DI:"); PrintHex (IntRegisters.DI);
PrintEndl();
#endif
if (IntRegisters.EBX >= BiosMemoryMapSize)
{
IntRegisters.Flags |= TC_X86_CARRY_FLAG;
IntRegisters.EBX = 0;
IntRegisters.AX = -1;
}
else
{
CopyMemory ((byte *) &BiosMemoryMap[IntRegisters.EBX], IntRegisters.ES, IntRegisters.DI, sizeof (BiosMemoryMap[0]));
IntRegisters.Flags &= ~TC_X86_CARRY_FLAG;
IntRegisters.EAX = 0x534D4150UL;
++IntRegisters.EBX;
if (IntRegisters.EBX >= BiosMemoryMapSize)
IntRegisters.EBX = 0;
IntRegisters.ECX = sizeof (BiosMemoryMap[0]);
}
if (IntRegisters.EBX == 0 && !(BootSectorFlags & TC_BOOT_CFG_FLAG_WINDOWS_VISTA_OR_LATER))
{
// Uninstall filter when the modified map has been issued three times to prevent
// problems with hardware drivers on some notebooks running Windows XP.
static int CompleteMapIssueCount = 0;
if (++CompleteMapIssueCount >= 3)
{
__asm
{
cli
push es
lea si, OriginalInt15Handler
xor ax, ax
mov es, ax
mov di, 0x15 * 4
mov ax, [si]
mov es:[di], ax
mov ax, [si + 2]
mov es:[di + 2], ax
pop es
sti
}
}
}
#ifdef TC_TRACE_INT15
BiosMemoryMapEntry entry;
CopyMemory (IntRegisters.ES, IntRegisters.DI, (byte *) &entry, sizeof (entry));
PrintHex (entry.Type); PrintChar (' ');
PrintHex (entry.BaseAddress); PrintChar (' ');
PrintHex (entry.Length); PrintChar (' ');
PrintHex (entry.BaseAddress + entry.Length); PrintEndl();
Print ("EAX:"); PrintHex (IntRegisters.EAX);
Print (" EBX:"); PrintHex (IntRegisters.EBX);
Print (" ECX:"); PrintHex (IntRegisters.ECX);
Print (" EDX:"); PrintHex (IntRegisters.EDX);
Print (" DI:"); PrintHex (IntRegisters.DI);
Print (" FL:"); PrintHex (IntRegisters.Flags);
PrintEndl (2);
#endif
#ifdef TC_TRACE_INT15
EnableScreenOutput();
#endif
return false;
}
void IntFilterEntry ()
{
// No automatic variables should be used in this scope as SS may change
static uint16 OrigStackPointer;
static uint16 OrigStackSegment;
__asm
{
pushf
pushad
cli
mov cs:IntRegisters.DI, di
lea di, cs:IntRegisters.EAX
TC_ASM_EMIT4 (66,2E,89,05) // mov [cs:di], eax
lea di, cs:IntRegisters.EBX
TC_ASM_EMIT4 (66,2E,89,1D) // mov [cs:di], ebx
lea di, cs:IntRegisters.ECX
TC_ASM_EMIT4 (66,2E,89,0D) // mov [cs:di], ecx
lea di, cs:IntRegisters.EDX
TC_ASM_EMIT4 (66,2E,89,15) // mov [cs:di], edx
mov ax, [bp + 8]
mov cs:IntRegisters.Flags, ax
mov cs:IntRegisters.SI, si
mov si, [bp + 2] // Int number
mov cs:IntRegisters.DS, ds
mov cs:IntRegisters.ES, es
mov cs:IntRegisters.SS, ss
// Compiler assumes SS == DS - use our stack if this condition is not met
mov ax, ss
mov bx, cs
cmp ax, bx
jz stack_ok
mov cs:OrigStackPointer, sp
mov cs:OrigStackSegment, ss
mov ax, cs
mov ss, ax
mov sp, TC_BOOT_LOADER_STACK_TOP
stack_ok:
// DS = CS
push ds
push es
mov ax, cs
mov ds, ax
mov es, ax
push si // Int number
// Filter request
cmp si, 0x15
je filter15
cmp si, 0x13
jne $
call Int13Filter
jmp s0
filter15:
call Int15Filter
s0:
pop si // Int number
pop es
pop ds
// Restore original SS:SP if our stack is empty
cli
mov bx, TC_BOOT_LOADER_STACK_TOP
cmp bx, sp
jnz stack_in_use
mov ss, cs:OrigStackSegment
mov sp, cs:OrigStackPointer
stack_in_use:
test ax, ax // passOriginalRequest
jnz pass_request
// Return results of filtered request
popad
popf
mov ax, cs:IntRegisters.Flags
mov [bp + 8], ax
leave
lea di, cs:IntRegisters.EAX
TC_ASM_EMIT4 (66,2E,8B,05) // mov eax, [cs:di]
lea di, cs:IntRegisters.EBX
TC_ASM_EMIT4 (66,2E,8B,1D) // mov ebx, [cs:di]
lea di, cs:IntRegisters.ECX
TC_ASM_EMIT4 (66,2E,8B,0D) // mov ecx, [cs:di]
lea di, cs:IntRegisters.EDX
TC_ASM_EMIT4 (66,2E,8B,15) // mov edx, [cs:di]
mov di, cs:IntRegisters.DI
mov si, cs:IntRegisters.SI
mov es, cs:IntRegisters.ES
mov ds, cs:IntRegisters.DS
sti
add sp, 2
iret
// Pass original request
pass_request:
sti
cmp si, 0x15
je pass15
cmp si, 0x13
jne $
popad
popf
leave
add sp, 2
jmp cs:OriginalInt13Handler
pass15:
popad
popf
leave
add sp, 2
jmp cs:OriginalInt15Handler
}
}
void Int13FilterEntry ()
{
__asm
{
leave
push 0x13
jmp IntFilterEntry
}
}
static void Int15FilterEntry ()
{
__asm
{
pushf
cmp ax, 0xe820 // Get system memory map
je filter
popf
leave
jmp cs:OriginalInt15Handler
filter:
leave
push 0x15
jmp IntFilterEntry
}
}
bool InstallInterruptFilters ()
{
#ifndef TC_WINDOWS_BOOT_RESCUE_DISK_MODE
// If the filters have already been installed, it usually indicates stack corruption
// and a consequent reentry of this routine without a system reset.
uint32 currentInt13Handler;
CopyMemory (0, 0x13 * 4, ¤tInt13Handler, sizeof (currentInt13Handler));
if (currentInt13Handler == (uint32) Int13FilterEntry)
{
PrintError ("Memory corrupted");
Print (TC_BOOT_STR_UPGRADE_BIOS);
GetKeyboardChar();
return true;
}
#endif
if (!CreateNewBiosMemoryMap())
return false;
__asm
{
cli
push es
// Save original INT 13 handler
xor ax, ax
mov es, ax
mov si, 0x13 * 4
lea di, OriginalInt13Handler
mov ax, es:[si]
mov [di], ax
mov ax, es:[si + 2]
mov [di + 2], ax
// Install INT 13 filter
lea ax, Int13FilterEntry
mov es:[si], ax
mov es:[si + 2], cs
// Save original INT 15 handler
mov si, 0x15 * 4
lea di, OriginalInt15Handler
mov ax, es:[si]
mov [di], ax
mov ax, es:[si + 2]
mov [di + 2], ax
// Install INT 15 filter
lea ax, Int15FilterEntry
mov es:[si], ax
mov es:[si + 2], cs
// If the BIOS does not support system memory map (INT15 0xe820),
// set amount of available memory to CS:0000 - 0:0000
cmp BiosMemoryMapSize, 1
jg mem_map_ok
mov ax, cs
shr ax, 10 - 4 // CS * 16 / 1024
mov es:[0x413], ax // = KBytes available
mem_map_ok:
pop es
sti
}
return true;
}
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