1 /** @file
2 Decode a hard disk partitioned with the legacy MBR found on most PC's
3
4 MBR - Master Boot Record is in the first sector of a partitioned hard disk.
5 The MBR supports four partitions per disk. The MBR also contains legacy
6 code that is not run on an EFI system. The legacy code reads the
7 first sector of the active partition into memory and
8
9 BPB - BIOS Parameter Block is in the first sector of a FAT file system.
10 The BPB contains information about the FAT file system. The BPB is
11 always on the first sector of a media. The first sector also contains
12 the legacy boot strap code.
13
14 Copyright (c) 2014, Hewlett-Packard Development Company, L.P.<BR>
15 Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
16 This program and the accompanying materials
17 are licensed and made available under the terms and conditions of the BSD License
18 which accompanies this distribution. The full text of the license may be found at
19 http://opensource.org/licenses/bsd-license.php
20
21 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
22 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
23
24 **/
25
26 #include "Partition.h"
27
28 /**
29 Test to see if the Mbr buffer is a valid MBR.
30
31 @param Mbr Parent Handle.
32 @param LastLba Last Lba address on the device.
33
34 @retval TRUE Mbr is a Valid MBR.
35 @retval FALSE Mbr is not a Valid MBR.
36
37 **/
38 BOOLEAN
PartitionValidMbr(IN MASTER_BOOT_RECORD * Mbr,IN EFI_LBA LastLba)39 PartitionValidMbr (
40 IN MASTER_BOOT_RECORD *Mbr,
41 IN EFI_LBA LastLba
42 )
43 {
44 UINT32 StartingLBA;
45 UINT32 EndingLBA;
46 UINT32 NewEndingLBA;
47 INTN Index1;
48 INTN Index2;
49 BOOLEAN MbrValid;
50
51 if (Mbr->Signature != MBR_SIGNATURE) {
52 return FALSE;
53 }
54 //
55 // The BPB also has this signature, so it can not be used alone.
56 //
57 MbrValid = FALSE;
58 for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) {
59 if (Mbr->Partition[Index1].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) {
60 continue;
61 }
62
63 MbrValid = TRUE;
64 StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA);
65 EndingLBA = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1;
66 if (EndingLBA > LastLba) {
67 //
68 // Compatibility Errata:
69 // Some systems try to hide drive space with their INT 13h driver
70 // This does not hide space from the OS driver. This means the MBR
71 // that gets created from DOS is smaller than the MBR created from
72 // a real OS (NT & Win98). This leads to BlockIo->LastBlock being
73 // wrong on some systems FDISKed by the OS.
74 //
75 // return FALSE since no block devices on a system are implemented
76 // with INT 13h
77 //
78
79 DEBUG((EFI_D_INFO, "PartitionValidMbr: Bad MBR partition size EndingLBA(%1x) > LastLBA(%1x)\n", EndingLBA, LastLba));
80
81 return FALSE;
82 }
83
84 for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {
85 if (Mbr->Partition[Index2].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) {
86 continue;
87 }
88
89 NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1;
90 if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) {
91 //
92 // This region overlaps with the Index1'th region
93 //
94 return FALSE;
95 }
96 }
97 }
98 //
99 // None of the regions overlapped so MBR is O.K.
100 //
101 return MbrValid;
102 }
103
104
105 /**
106 Install child handles if the Handle supports MBR format.
107
108 @param[in] This Calling context.
109 @param[in] Handle Parent Handle.
110 @param[in] DiskIo Parent DiskIo interface.
111 @param[in] DiskIo2 Parent DiskIo2 interface.
112 @param[in] BlockIo Parent BlockIo interface.
113 @param[in] BlockIo2 Parent BlockIo2 interface.
114 @param[in] DevicePath Parent Device Path.
115
116 @retval EFI_SUCCESS A child handle was added.
117 @retval EFI_MEDIA_CHANGED Media change was detected.
118 @retval Others MBR partition was not found.
119
120 **/
121 EFI_STATUS
PartitionInstallMbrChildHandles(IN EFI_DRIVER_BINDING_PROTOCOL * This,IN EFI_HANDLE Handle,IN EFI_DISK_IO_PROTOCOL * DiskIo,IN EFI_DISK_IO2_PROTOCOL * DiskIo2,IN EFI_BLOCK_IO_PROTOCOL * BlockIo,IN EFI_BLOCK_IO2_PROTOCOL * BlockIo2,IN EFI_DEVICE_PATH_PROTOCOL * DevicePath)122 PartitionInstallMbrChildHandles (
123 IN EFI_DRIVER_BINDING_PROTOCOL *This,
124 IN EFI_HANDLE Handle,
125 IN EFI_DISK_IO_PROTOCOL *DiskIo,
126 IN EFI_DISK_IO2_PROTOCOL *DiskIo2,
127 IN EFI_BLOCK_IO_PROTOCOL *BlockIo,
128 IN EFI_BLOCK_IO2_PROTOCOL *BlockIo2,
129 IN EFI_DEVICE_PATH_PROTOCOL *DevicePath
130 )
131 {
132 EFI_STATUS Status;
133 MASTER_BOOT_RECORD *Mbr;
134 UINT32 ExtMbrStartingLba;
135 UINT32 Index;
136 HARDDRIVE_DEVICE_PATH HdDev;
137 HARDDRIVE_DEVICE_PATH ParentHdDev;
138 EFI_STATUS Found;
139 EFI_DEVICE_PATH_PROTOCOL *DevicePathNode;
140 EFI_DEVICE_PATH_PROTOCOL *LastDevicePathNode;
141 UINT32 BlockSize;
142 UINT32 MediaId;
143 EFI_LBA LastBlock;
144
145 Found = EFI_NOT_FOUND;
146
147 BlockSize = BlockIo->Media->BlockSize;
148 MediaId = BlockIo->Media->MediaId;
149 LastBlock = BlockIo->Media->LastBlock;
150
151 Mbr = AllocatePool (BlockSize);
152 if (Mbr == NULL) {
153 return Found;
154 }
155
156 Status = DiskIo->ReadDisk (
157 DiskIo,
158 MediaId,
159 0,
160 BlockSize,
161 Mbr
162 );
163 if (EFI_ERROR (Status)) {
164 Found = Status;
165 goto Done;
166 }
167 if (!PartitionValidMbr (Mbr, LastBlock)) {
168 goto Done;
169 }
170 //
171 // We have a valid mbr - add each partition
172 //
173 //
174 // Get starting and ending LBA of the parent block device.
175 //
176 LastDevicePathNode = NULL;
177 ZeroMem (&ParentHdDev, sizeof (ParentHdDev));
178 DevicePathNode = DevicePath;
179 while (!IsDevicePathEnd (DevicePathNode)) {
180 LastDevicePathNode = DevicePathNode;
181 DevicePathNode = NextDevicePathNode (DevicePathNode);
182 }
183
184 if (LastDevicePathNode != NULL) {
185 if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH &&
186 DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP
187 ) {
188 CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev));
189 } else {
190 LastDevicePathNode = NULL;
191 }
192 }
193
194 ZeroMem (&HdDev, sizeof (HdDev));
195 HdDev.Header.Type = MEDIA_DEVICE_PATH;
196 HdDev.Header.SubType = MEDIA_HARDDRIVE_DP;
197 SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));
198 HdDev.MBRType = MBR_TYPE_PCAT;
199 HdDev.SignatureType = SIGNATURE_TYPE_MBR;
200
201 if (LastDevicePathNode == NULL) {
202 //
203 // This is a MBR, add each partition
204 //
205 for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
206 if (Mbr->Partition[Index].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) {
207 //
208 // Don't use null MBR entries
209 //
210 continue;
211 }
212
213 if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) {
214 //
215 // This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.
216 // We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating
217 // this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format
218 // that corrupted the GPT partition.
219 //
220 continue;
221 }
222
223 HdDev.PartitionNumber = Index + 1;
224 HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA);
225 HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA);
226 CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (Mbr->UniqueMbrSignature));
227
228 Status = PartitionInstallChildHandle (
229 This,
230 Handle,
231 DiskIo,
232 DiskIo2,
233 BlockIo,
234 BlockIo2,
235 DevicePath,
236 (EFI_DEVICE_PATH_PROTOCOL *) &HdDev,
237 HdDev.PartitionStart,
238 HdDev.PartitionStart + HdDev.PartitionSize - 1,
239 MBR_SIZE,
240 (BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION)
241 );
242
243 if (!EFI_ERROR (Status)) {
244 Found = EFI_SUCCESS;
245 }
246 }
247 } else {
248 //
249 // It's an extended partition. Follow the extended partition
250 // chain to get all the logical drives
251 //
252 Index = 0;
253 ExtMbrStartingLba = 0;
254
255 do {
256
257 Status = DiskIo->ReadDisk (
258 DiskIo,
259 MediaId,
260 MultU64x32 (ExtMbrStartingLba, BlockSize),
261 BlockSize,
262 Mbr
263 );
264 if (EFI_ERROR (Status)) {
265 Found = Status;
266 goto Done;
267 }
268
269 if (UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA) == 0) {
270 break;
271 }
272
273 if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) ||
274 (Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) {
275 ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA);
276 continue;
277 }
278 HdDev.PartitionNumber = ++Index;
279 HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart;
280 HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA);
281 if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) ||
282 (HdDev.PartitionStart <= ParentHdDev.PartitionStart)) {
283 break;
284 }
285
286 //
287 // The signature in EBR(Extended Boot Record) should always be 0.
288 //
289 *((UINT32 *) &HdDev.Signature[0]) = 0;
290
291 Status = PartitionInstallChildHandle (
292 This,
293 Handle,
294 DiskIo,
295 DiskIo2,
296 BlockIo,
297 BlockIo2,
298 DevicePath,
299 (EFI_DEVICE_PATH_PROTOCOL *) &HdDev,
300 HdDev.PartitionStart - ParentHdDev.PartitionStart,
301 HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1,
302 MBR_SIZE,
303 (BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION)
304 );
305 if (!EFI_ERROR (Status)) {
306 Found = EFI_SUCCESS;
307 }
308
309 if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) &&
310 (Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION)
311 ) {
312 break;
313 }
314
315 ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA);
316 //
317 // Don't allow partition to be self referencing
318 //
319 if (ExtMbrStartingLba == 0) {
320 break;
321 }
322 } while (ExtMbrStartingLba < ParentHdDev.PartitionSize);
323 }
324
325 Done:
326 FreePool (Mbr);
327
328 return Found;
329 }
330