block/partitions/msdos.c

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