1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * fs/partitions/msdos.c 4 * 5 * Code extracted from drivers/block/genhd.c 6 * Copyright (C) 1991-1998 Linus Torvalds 7 * 8 * Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug 9 * in the early extended-partition checks and added DM partitions 10 * 11 * Support for DiskManager v6.0x added by Mark Lord, 12 * with information provided by OnTrack. This now works for linux fdisk 13 * and LILO, as well as loadlin and bootln. Note that disks other than 14 * /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1). 15 * 16 * More flexible handling of extended partitions - aeb, 950831 17 * 18 * Check partition table on IDE disks for common CHS translations 19 * 20 * Re-organised Feb 1998 Russell King 21 */ 22 #include <linux/msdos_fs.h> 23 24 #include "check.h" 25 #include "msdos.h" 26 #include "efi.h" 27 #include "aix.h" 28 29 /* 30 * Many architectures don't like unaligned accesses, while 31 * the nr_sects and start_sect partition table entries are 32 * at a 2 (mod 4) address. 33 */ 34 #include <asm/unaligned.h> 35 36 #define SYS_IND(p) get_unaligned(&p->sys_ind) 37 38 static inline sector_t nr_sects(struct partition *p) 39 { 40 return (sector_t)get_unaligned_le32(&p->nr_sects); 41 } 42 43 static inline sector_t start_sect(struct partition *p) 44 { 45 return (sector_t)get_unaligned_le32(&p->start_sect); 46 } 47 48 static inline int is_extended_partition(struct partition *p) 49 { 50 return (SYS_IND(p) == DOS_EXTENDED_PARTITION || 51 SYS_IND(p) == WIN98_EXTENDED_PARTITION || 52 SYS_IND(p) == LINUX_EXTENDED_PARTITION); 53 } 54 55 #define MSDOS_LABEL_MAGIC1 0x55 56 #define MSDOS_LABEL_MAGIC2 0xAA 57 58 static inline int 59 msdos_magic_present(unsigned char *p) 60 { 61 return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2); 62 } 63 64 /* Value is EBCDIC 'IBMA' */ 65 #define AIX_LABEL_MAGIC1 0xC9 66 #define AIX_LABEL_MAGIC2 0xC2 67 #define AIX_LABEL_MAGIC3 0xD4 68 #define AIX_LABEL_MAGIC4 0xC1 69 static int aix_magic_present(struct parsed_partitions *state, unsigned char *p) 70 { 71 struct partition *pt = (struct partition *) (p + 0x1be); 72 Sector sect; 73 unsigned char *d; 74 int slot, ret = 0; 75 76 if (!(p[0] == AIX_LABEL_MAGIC1 && 77 p[1] == AIX_LABEL_MAGIC2 && 78 p[2] == AIX_LABEL_MAGIC3 && 79 p[3] == AIX_LABEL_MAGIC4)) 80 return 0; 81 /* Assume the partition table is valid if Linux partitions exists */ 82 for (slot = 1; slot <= 4; slot++, pt++) { 83 if (pt->sys_ind == LINUX_SWAP_PARTITION || 84 pt->sys_ind == LINUX_RAID_PARTITION || 85 pt->sys_ind == LINUX_DATA_PARTITION || 86 pt->sys_ind == LINUX_LVM_PARTITION || 87 is_extended_partition(pt)) 88 return 0; 89 } 90 d = read_part_sector(state, 7, §); 91 if (d) { 92 if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M') 93 ret = 1; 94 put_dev_sector(sect); 95 } 96 return ret; 97 } 98 99 static void set_info(struct parsed_partitions *state, int slot, 100 u32 disksig) 101 { 102 struct partition_meta_info *info = &state->parts[slot].info; 103 104 snprintf(info->uuid, sizeof(info->uuid), "%08x-%02x", disksig, 105 slot); 106 info->volname[0] = 0; 107 state->parts[slot].has_info = true; 108 } 109 110 /* 111 * Create devices for each logical partition in an extended partition. 112 * The logical partitions form a linked list, with each entry being 113 * a partition table with two entries. The first entry 114 * is the real data partition (with a start relative to the partition 115 * table start). The second is a pointer to the next logical partition 116 * (with a start relative to the entire extended partition). 117 * We do not create a Linux partition for the partition tables, but 118 * only for the actual data partitions. 119 */ 120 121 static void parse_extended(struct parsed_partitions *state, 122 sector_t first_sector, sector_t first_size, 123 u32 disksig) 124 { 125 struct partition *p; 126 Sector sect; 127 unsigned char *data; 128 sector_t this_sector, this_size; 129 sector_t sector_size = bdev_logical_block_size(state->bdev) / 512; 130 int loopct = 0; /* number of links followed 131 without finding a data partition */ 132 int i; 133 134 this_sector = first_sector; 135 this_size = first_size; 136 137 while (1) { 138 if (++loopct > 100) 139 return; 140 if (state->next == state->limit) 141 return; 142 data = read_part_sector(state, this_sector, §); 143 if (!data) 144 return; 145 146 if (!msdos_magic_present(data + 510)) 147 goto done; 148 149 p = (struct partition *) (data + 0x1be); 150 151 /* 152 * Usually, the first entry is the real data partition, 153 * the 2nd entry is the next extended partition, or empty, 154 * and the 3rd and 4th entries are unused. 155 * However, DRDOS sometimes has the extended partition as 156 * the first entry (when the data partition is empty), 157 * and OS/2 seems to use all four entries. 158 */ 159 160 /* 161 * First process the data partition(s) 162 */ 163 for (i = 0; i < 4; i++, p++) { 164 sector_t offs, size, next; 165 166 if (!nr_sects(p) || is_extended_partition(p)) 167 continue; 168 169 /* Check the 3rd and 4th entries - 170 these sometimes contain random garbage */ 171 offs = start_sect(p)*sector_size; 172 size = nr_sects(p)*sector_size; 173 next = this_sector + offs; 174 if (i >= 2) { 175 if (offs + size > this_size) 176 continue; 177 if (next < first_sector) 178 continue; 179 if (next + size > first_sector + first_size) 180 continue; 181 } 182 183 put_partition(state, state->next, next, size); 184 set_info(state, state->next, disksig); 185 if (SYS_IND(p) == LINUX_RAID_PARTITION) 186 state->parts[state->next].flags = ADDPART_FLAG_RAID; 187 loopct = 0; 188 if (++state->next == state->limit) 189 goto done; 190 } 191 /* 192 * Next, process the (first) extended partition, if present. 193 * (So far, there seems to be no reason to make 194 * parse_extended() recursive and allow a tree 195 * of extended partitions.) 196 * It should be a link to the next logical partition. 197 */ 198 p -= 4; 199 for (i = 0; i < 4; i++, p++) 200 if (nr_sects(p) && is_extended_partition(p)) 201 break; 202 if (i == 4) 203 goto done; /* nothing left to do */ 204 205 this_sector = first_sector + start_sect(p) * sector_size; 206 this_size = nr_sects(p) * sector_size; 207 put_dev_sector(sect); 208 } 209 done: 210 put_dev_sector(sect); 211 } 212 213 /* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also 214 indicates linux swap. Be careful before believing this is Solaris. */ 215 216 static void parse_solaris_x86(struct parsed_partitions *state, 217 sector_t offset, sector_t size, int origin) 218 { 219 #ifdef CONFIG_SOLARIS_X86_PARTITION 220 Sector sect; 221 struct solaris_x86_vtoc *v; 222 int i; 223 short max_nparts; 224 225 v = read_part_sector(state, offset + 1, §); 226 if (!v) 227 return; 228 if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) { 229 put_dev_sector(sect); 230 return; 231 } 232 { 233 char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1]; 234 235 snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin); 236 strlcat(state->pp_buf, tmp, PAGE_SIZE); 237 } 238 if (le32_to_cpu(v->v_version) != 1) { 239 char tmp[64]; 240 241 snprintf(tmp, sizeof(tmp), " cannot handle version %d vtoc>\n", 242 le32_to_cpu(v->v_version)); 243 strlcat(state->pp_buf, tmp, PAGE_SIZE); 244 put_dev_sector(sect); 245 return; 246 } 247 /* Ensure we can handle previous case of VTOC with 8 entries gracefully */ 248 max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8; 249 for (i = 0; i < max_nparts && state->next < state->limit; i++) { 250 struct solaris_x86_slice *s = &v->v_slice[i]; 251 char tmp[3 + 10 + 1 + 1]; 252 253 if (s->s_size == 0) 254 continue; 255 snprintf(tmp, sizeof(tmp), " [s%d]", i); 256 strlcat(state->pp_buf, tmp, PAGE_SIZE); 257 /* solaris partitions are relative to current MS-DOS 258 * one; must add the offset of the current partition */ 259 put_partition(state, state->next++, 260 le32_to_cpu(s->s_start)+offset, 261 le32_to_cpu(s->s_size)); 262 } 263 put_dev_sector(sect); 264 strlcat(state->pp_buf, " >\n", PAGE_SIZE); 265 #endif 266 } 267 268 #if defined(CONFIG_BSD_DISKLABEL) 269 /* 270 * Create devices for BSD partitions listed in a disklabel, under a 271 * dos-like partition. See parse_extended() for more information. 272 */ 273 static void parse_bsd(struct parsed_partitions *state, 274 sector_t offset, sector_t size, int origin, char *flavour, 275 int max_partitions) 276 { 277 Sector sect; 278 struct bsd_disklabel *l; 279 struct bsd_partition *p; 280 char tmp[64]; 281 282 l = read_part_sector(state, offset + 1, §); 283 if (!l) 284 return; 285 if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) { 286 put_dev_sector(sect); 287 return; 288 } 289 290 snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour); 291 strlcat(state->pp_buf, tmp, PAGE_SIZE); 292 293 if (le16_to_cpu(l->d_npartitions) < max_partitions) 294 max_partitions = le16_to_cpu(l->d_npartitions); 295 for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) { 296 sector_t bsd_start, bsd_size; 297 298 if (state->next == state->limit) 299 break; 300 if (p->p_fstype == BSD_FS_UNUSED) 301 continue; 302 bsd_start = le32_to_cpu(p->p_offset); 303 bsd_size = le32_to_cpu(p->p_size); 304 if (memcmp(flavour, "bsd\0", 4) == 0) 305 bsd_start += offset; 306 if (offset == bsd_start && size == bsd_size) 307 /* full parent partition, we have it already */ 308 continue; 309 if (offset > bsd_start || offset+size < bsd_start+bsd_size) { 310 strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE); 311 continue; 312 } 313 put_partition(state, state->next++, bsd_start, bsd_size); 314 } 315 put_dev_sector(sect); 316 if (le16_to_cpu(l->d_npartitions) > max_partitions) { 317 snprintf(tmp, sizeof(tmp), " (ignored %d more)", 318 le16_to_cpu(l->d_npartitions) - max_partitions); 319 strlcat(state->pp_buf, tmp, PAGE_SIZE); 320 } 321 strlcat(state->pp_buf, " >\n", PAGE_SIZE); 322 } 323 #endif 324 325 static void parse_freebsd(struct parsed_partitions *state, 326 sector_t offset, sector_t size, int origin) 327 { 328 #ifdef CONFIG_BSD_DISKLABEL 329 parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS); 330 #endif 331 } 332 333 static void parse_netbsd(struct parsed_partitions *state, 334 sector_t offset, sector_t size, int origin) 335 { 336 #ifdef CONFIG_BSD_DISKLABEL 337 parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS); 338 #endif 339 } 340 341 static void parse_openbsd(struct parsed_partitions *state, 342 sector_t offset, sector_t size, int origin) 343 { 344 #ifdef CONFIG_BSD_DISKLABEL 345 parse_bsd(state, offset, size, origin, "openbsd", 346 OPENBSD_MAXPARTITIONS); 347 #endif 348 } 349 350 /* 351 * Create devices for Unixware partitions listed in a disklabel, under a 352 * dos-like partition. See parse_extended() for more information. 353 */ 354 static void parse_unixware(struct parsed_partitions *state, 355 sector_t offset, sector_t size, int origin) 356 { 357 #ifdef CONFIG_UNIXWARE_DISKLABEL 358 Sector sect; 359 struct unixware_disklabel *l; 360 struct unixware_slice *p; 361 362 l = read_part_sector(state, offset + 29, §); 363 if (!l) 364 return; 365 if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC || 366 le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) { 367 put_dev_sector(sect); 368 return; 369 } 370 { 371 char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1]; 372 373 snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin); 374 strlcat(state->pp_buf, tmp, PAGE_SIZE); 375 } 376 p = &l->vtoc.v_slice[1]; 377 /* I omit the 0th slice as it is the same as whole disk. */ 378 while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) { 379 if (state->next == state->limit) 380 break; 381 382 if (p->s_label != UNIXWARE_FS_UNUSED) 383 put_partition(state, state->next++, 384 le32_to_cpu(p->start_sect), 385 le32_to_cpu(p->nr_sects)); 386 p++; 387 } 388 put_dev_sector(sect); 389 strlcat(state->pp_buf, " >\n", PAGE_SIZE); 390 #endif 391 } 392 393 /* 394 * Minix 2.0.0/2.0.2 subpartition support. 395 * Anand Krishnamurthy <anandk@wiproge.med.ge.com> 396 * Rajeev V. Pillai <rajeevvp@yahoo.com> 397 */ 398 static void parse_minix(struct parsed_partitions *state, 399 sector_t offset, sector_t size, int origin) 400 { 401 #ifdef CONFIG_MINIX_SUBPARTITION 402 Sector sect; 403 unsigned char *data; 404 struct partition *p; 405 int i; 406 407 data = read_part_sector(state, offset, §); 408 if (!data) 409 return; 410 411 p = (struct partition *)(data + 0x1be); 412 413 /* The first sector of a Minix partition can have either 414 * a secondary MBR describing its subpartitions, or 415 * the normal boot sector. */ 416 if (msdos_magic_present(data + 510) && 417 SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */ 418 char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1]; 419 420 snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin); 421 strlcat(state->pp_buf, tmp, PAGE_SIZE); 422 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) { 423 if (state->next == state->limit) 424 break; 425 /* add each partition in use */ 426 if (SYS_IND(p) == MINIX_PARTITION) 427 put_partition(state, state->next++, 428 start_sect(p), nr_sects(p)); 429 } 430 strlcat(state->pp_buf, " >\n", PAGE_SIZE); 431 } 432 put_dev_sector(sect); 433 #endif /* CONFIG_MINIX_SUBPARTITION */ 434 } 435 436 static struct { 437 unsigned char id; 438 void (*parse)(struct parsed_partitions *, sector_t, sector_t, int); 439 } subtypes[] = { 440 {FREEBSD_PARTITION, parse_freebsd}, 441 {NETBSD_PARTITION, parse_netbsd}, 442 {OPENBSD_PARTITION, parse_openbsd}, 443 {MINIX_PARTITION, parse_minix}, 444 {UNIXWARE_PARTITION, parse_unixware}, 445 {SOLARIS_X86_PARTITION, parse_solaris_x86}, 446 {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86}, 447 {0, NULL}, 448 }; 449 450 int msdos_partition(struct parsed_partitions *state) 451 { 452 sector_t sector_size = bdev_logical_block_size(state->bdev) / 512; 453 Sector sect; 454 unsigned char *data; 455 struct partition *p; 456 struct fat_boot_sector *fb; 457 int slot; 458 u32 disksig; 459 460 data = read_part_sector(state, 0, §); 461 if (!data) 462 return -1; 463 464 /* 465 * Note order! (some AIX disks, e.g. unbootable kind, 466 * have no MSDOS 55aa) 467 */ 468 if (aix_magic_present(state, data)) { 469 put_dev_sector(sect); 470 #ifdef CONFIG_AIX_PARTITION 471 return aix_partition(state); 472 #else 473 strlcat(state->pp_buf, " [AIX]", PAGE_SIZE); 474 return 0; 475 #endif 476 } 477 478 if (!msdos_magic_present(data + 510)) { 479 put_dev_sector(sect); 480 return 0; 481 } 482 483 /* 484 * Now that the 55aa signature is present, this is probably 485 * either the boot sector of a FAT filesystem or a DOS-type 486 * partition table. Reject this in case the boot indicator 487 * is not 0 or 0x80. 488 */ 489 p = (struct partition *) (data + 0x1be); 490 for (slot = 1; slot <= 4; slot++, p++) { 491 if (p->boot_ind != 0 && p->boot_ind != 0x80) { 492 /* 493 * Even without a valid boot inidicator value 494 * its still possible this is valid FAT filesystem 495 * without a partition table. 496 */ 497 fb = (struct fat_boot_sector *) data; 498 if (slot == 1 && fb->reserved && fb->fats 499 && fat_valid_media(fb->media)) { 500 strlcat(state->pp_buf, "\n", PAGE_SIZE); 501 put_dev_sector(sect); 502 return 1; 503 } else { 504 put_dev_sector(sect); 505 return 0; 506 } 507 } 508 } 509 510 #ifdef CONFIG_EFI_PARTITION 511 p = (struct partition *) (data + 0x1be); 512 for (slot = 1 ; slot <= 4 ; slot++, p++) { 513 /* If this is an EFI GPT disk, msdos should ignore it. */ 514 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) { 515 put_dev_sector(sect); 516 return 0; 517 } 518 } 519 #endif 520 p = (struct partition *) (data + 0x1be); 521 522 disksig = le32_to_cpup((__le32 *)(data + 0x1b8)); 523 524 /* 525 * Look for partitions in two passes: 526 * First find the primary and DOS-type extended partitions. 527 * On the second pass look inside *BSD, Unixware and Solaris partitions. 528 */ 529 530 state->next = 5; 531 for (slot = 1 ; slot <= 4 ; slot++, p++) { 532 sector_t start = start_sect(p)*sector_size; 533 sector_t size = nr_sects(p)*sector_size; 534 535 if (!size) 536 continue; 537 if (is_extended_partition(p)) { 538 /* 539 * prevent someone doing mkfs or mkswap on an 540 * extended partition, but leave room for LILO 541 * FIXME: this uses one logical sector for > 512b 542 * sector, although it may not be enough/proper. 543 */ 544 sector_t n = 2; 545 546 n = min(size, max(sector_size, n)); 547 put_partition(state, slot, start, n); 548 549 strlcat(state->pp_buf, " <", PAGE_SIZE); 550 parse_extended(state, start, size, disksig); 551 strlcat(state->pp_buf, " >", PAGE_SIZE); 552 continue; 553 } 554 put_partition(state, slot, start, size); 555 set_info(state, slot, disksig); 556 if (SYS_IND(p) == LINUX_RAID_PARTITION) 557 state->parts[slot].flags = ADDPART_FLAG_RAID; 558 if (SYS_IND(p) == DM6_PARTITION) 559 strlcat(state->pp_buf, "[DM]", PAGE_SIZE); 560 if (SYS_IND(p) == EZD_PARTITION) 561 strlcat(state->pp_buf, "[EZD]", PAGE_SIZE); 562 } 563 564 strlcat(state->pp_buf, "\n", PAGE_SIZE); 565 566 /* second pass - output for each on a separate line */ 567 p = (struct partition *) (0x1be + data); 568 for (slot = 1 ; slot <= 4 ; slot++, p++) { 569 unsigned char id = SYS_IND(p); 570 int n; 571 572 if (!nr_sects(p)) 573 continue; 574 575 for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++) 576 ; 577 578 if (!subtypes[n].parse) 579 continue; 580 subtypes[n].parse(state, start_sect(p) * sector_size, 581 nr_sects(p) * sector_size, slot); 582 } 583 put_dev_sector(sect); 584 return 1; 585 } 586