VeraCrypt
aboutsummaryrefslogtreecommitdiff
path: root/src/Boot/Windows/BootDiskIo.cpp
blob: 84e888e093a9a44ed2503c62ffb2353e2d333641 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
/*
 Copyright (c) 2008-2011 TrueCrypt Developers Association. All rights reserved.

 Governed by the TrueCrypt License 3.0 the full text of which is contained in
 the file License.txt included in TrueCrypt 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;
}