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