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 - 2013, 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 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 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 UINTN Index; 136 HARDDRIVE_DEVICE_PATH HdDev; 137 HARDDRIVE_DEVICE_PATH ParentHdDev; 138 EFI_STATUS Found; 139 UINT32 PartitionNumber; 140 EFI_DEVICE_PATH_PROTOCOL *DevicePathNode; 141 EFI_DEVICE_PATH_PROTOCOL *LastDevicePathNode; 142 UINT32 BlockSize; 143 UINT32 MediaId; 144 EFI_LBA LastBlock; 145 146 Found = EFI_NOT_FOUND; 147 148 BlockSize = BlockIo->Media->BlockSize; 149 MediaId = BlockIo->Media->MediaId; 150 LastBlock = BlockIo->Media->LastBlock; 151 152 Mbr = AllocatePool (BlockSize); 153 if (Mbr == NULL) { 154 return Found; 155 } 156 157 Status = DiskIo->ReadDisk ( 158 DiskIo, 159 MediaId, 160 0, 161 BlockSize, 162 Mbr 163 ); 164 if (EFI_ERROR (Status)) { 165 Found = Status; 166 goto Done; 167 } 168 if (!PartitionValidMbr (Mbr, LastBlock)) { 169 goto Done; 170 } 171 // 172 // We have a valid mbr - add each partition 173 // 174 // 175 // Get starting and ending LBA of the parent block device. 176 // 177 LastDevicePathNode = NULL; 178 ZeroMem (&ParentHdDev, sizeof (ParentHdDev)); 179 DevicePathNode = DevicePath; 180 while (!IsDevicePathEnd (DevicePathNode)) { 181 LastDevicePathNode = DevicePathNode; 182 DevicePathNode = NextDevicePathNode (DevicePathNode); 183 } 184 185 if (LastDevicePathNode != NULL) { 186 if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH && 187 DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP 188 ) { 189 CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev)); 190 } else { 191 LastDevicePathNode = NULL; 192 } 193 } 194 195 PartitionNumber = 1; 196 197 ZeroMem (&HdDev, sizeof (HdDev)); 198 HdDev.Header.Type = MEDIA_DEVICE_PATH; 199 HdDev.Header.SubType = MEDIA_HARDDRIVE_DP; 200 SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev)); 201 HdDev.MBRType = MBR_TYPE_PCAT; 202 HdDev.SignatureType = SIGNATURE_TYPE_MBR; 203 204 if (LastDevicePathNode == NULL) { 205 // 206 // This is a MBR, add each partition 207 // 208 for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) { 209 if (Mbr->Partition[Index].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) { 210 // 211 // Don't use null MBR entries 212 // 213 continue; 214 } 215 216 if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) { 217 // 218 // This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here. 219 // We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating 220 // this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format 221 // that corrupted the GPT partition. 222 // 223 continue; 224 } 225 226 HdDev.PartitionNumber = PartitionNumber ++; 227 HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA); 228 HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA); 229 CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (Mbr->UniqueMbrSignature)); 230 231 Status = PartitionInstallChildHandle ( 232 This, 233 Handle, 234 DiskIo, 235 DiskIo2, 236 BlockIo, 237 BlockIo2, 238 DevicePath, 239 (EFI_DEVICE_PATH_PROTOCOL *) &HdDev, 240 HdDev.PartitionStart, 241 HdDev.PartitionStart + HdDev.PartitionSize - 1, 242 MBR_SIZE, 243 (BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION) 244 ); 245 246 if (!EFI_ERROR (Status)) { 247 Found = EFI_SUCCESS; 248 } 249 } 250 } else { 251 // 252 // It's an extended partition. Follow the extended partition 253 // chain to get all the logical drives 254 // 255 ExtMbrStartingLba = 0; 256 257 do { 258 259 Status = DiskIo->ReadDisk ( 260 DiskIo, 261 MediaId, 262 MultU64x32 (ExtMbrStartingLba, BlockSize), 263 BlockSize, 264 Mbr 265 ); 266 if (EFI_ERROR (Status)) { 267 Found = Status; 268 goto Done; 269 } 270 271 if (UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA) == 0) { 272 break; 273 } 274 275 if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) || 276 (Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) { 277 ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA); 278 continue; 279 } 280 HdDev.PartitionNumber = PartitionNumber ++; 281 HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart; 282 HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA); 283 if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) || 284 (HdDev.PartitionStart <= ParentHdDev.PartitionStart)) { 285 break; 286 } 287 288 // 289 // The signature in EBR(Extended Boot Record) should always be 0. 290 // 291 *((UINT32 *) &HdDev.Signature[0]) = 0; 292 293 Status = PartitionInstallChildHandle ( 294 This, 295 Handle, 296 DiskIo, 297 DiskIo2, 298 BlockIo, 299 BlockIo2, 300 DevicePath, 301 (EFI_DEVICE_PATH_PROTOCOL *) &HdDev, 302 HdDev.PartitionStart - ParentHdDev.PartitionStart, 303 HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1, 304 MBR_SIZE, 305 (BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION) 306 ); 307 if (!EFI_ERROR (Status)) { 308 Found = EFI_SUCCESS; 309 } 310 311 if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) && 312 (Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION) 313 ) { 314 break; 315 } 316 317 ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA); 318 // 319 // Don't allow partition to be self referencing 320 // 321 if (ExtMbrStartingLba == 0) { 322 break; 323 } 324 } while (ExtMbrStartingLba < ParentHdDev.PartitionSize); 325 } 326 327 Done: 328 FreePool (Mbr); 329 330 return Found; 331 } 332
