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         printk(" %s%d: <solaris:", state->name, origin);
 217         if (le32_to_cpu(v->v_version) != 1) {
 218                 printk("  cannot handle version %d vtoc>\n",
 219                         le32_to_cpu(v->v_version));
 220                 put_dev_sector(sect);
 221                 return;
 222         }
 223         /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
 224         max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
 225         for (i=0; i<max_nparts && state->next<state->limit; i++) {
 226                 struct solaris_x86_slice *s = &v->v_slice[i];
 227                 if (s->s_size == 0)
 228                         continue;
 229                 printk(" [s%d]", i);
 230                 /* solaris partitions are relative to current MS-DOS
 231                  * one; must add the offset of the current partition */
 232                 put_partition(state, state->next++,
 233                                  le32_to_cpu(s->s_start)+offset,
 234                                  le32_to_cpu(s->s_size));
 235         }
 236         put_dev_sector(sect);
 237         printk(" >\n");
 238 #endif
 239 }
 240
 241 #if defined(CONFIG_BSD_DISKLABEL)
 242 /*
 243  * Create devices for BSD partitions listed in a disklabel, under a
 244  * dos-like partition. See parse_extended() for more information.
 245  */
 246 static void parse_bsd(struct parsed_partitions *state,
 247                       sector_t offset, sector_t size, int origin, char *flavour,
 248                       int max_partitions)
 249 {
 250         Sector sect;
 251         struct bsd_disklabel *l;
 252         struct bsd_partition *p;
 253
 254         l = read_part_sector(state, offset + 1, &sect);
 255         if (!l)
 256                 return;
 257         if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
 258                 put_dev_sector(sect);
 259                 return;
 260         }
 261         printk(" %s%d: <%s:", state->name, origin, flavour);
 262
 263         if (le16_to_cpu(l->d_npartitions) < max_partitions)
 264                 max_partitions = le16_to_cpu(l->d_npartitions);
 265         for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
 266                 sector_t bsd_start, bsd_size;
 267
 268                 if (state->next == state->limit)
 269                         break;
 270                 if (p->p_fstype == BSD_FS_UNUSED)
 271                         continue;
 272                 bsd_start = le32_to_cpu(p->p_offset);
 273                 bsd_size = le32_to_cpu(p->p_size);
 274                 if (offset == bsd_start && size == bsd_size)
 275                         /* full parent partition, we have it already */
 276                         continue;
 277                 if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
 278                         printk("bad subpartition - ignored\n");
 279                         continue;
 280                 }
 281                 put_partition(state, state->next++, bsd_start, bsd_size);
 282         }
 283         put_dev_sector(sect);
 284         if (le16_to_cpu(l->d_npartitions) > max_partitions)
 285                 printk(" (ignored %d more)",
 286                        le16_to_cpu(l->d_npartitions) - max_partitions);
 287         printk(" >\n");
 288 }
 289 #endif
 290
 291 static void parse_freebsd(struct parsed_partitions *state,
 292                           sector_t offset, sector_t size, int origin)
 293 {
 294 #ifdef CONFIG_BSD_DISKLABEL
 295         parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
 296 #endif
 297 }
 298
 299 static void parse_netbsd(struct parsed_partitions *state,
 300                          sector_t offset, sector_t size, int origin)
 301 {
 302 #ifdef CONFIG_BSD_DISKLABEL
 303         parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
 304 #endif
 305 }
 306
 307 static void parse_openbsd(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, "openbsd",
 312                   OPENBSD_MAXPARTITIONS);
 313 #endif
 314 }
 315
 316 /*
 317  * Create devices for Unixware partitions listed in a disklabel, under a
 318  * dos-like partition. See parse_extended() for more information.
 319  */
 320 static void parse_unixware(struct parsed_partitions *state,
 321                            sector_t offset, sector_t size, int origin)
 322 {
 323 #ifdef CONFIG_UNIXWARE_DISKLABEL
 324         Sector sect;
 325         struct unixware_disklabel *l;
 326         struct unixware_slice *p;
 327
 328         l = read_part_sector(state, offset + 29, &sect);
 329         if (!l)
 330                 return;
 331         if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
 332             le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
 333                 put_dev_sector(sect);
 334                 return;
 335         }
 336         printk(" %s%d: <unixware:", state->name, origin);
 337         p = &l->vtoc.v_slice[1];
 338         /* I omit the 0th slice as it is the same as whole disk. */
 339         while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
 340                 if (state->next == state->limit)
 341                         break;
 342
 343                 if (p->s_label != UNIXWARE_FS_UNUSED)
 344                         put_partition(state, state->next++,
 345                                       le32_to_cpu(p->start_sect),
 346                                       le32_to_cpu(p->nr_sects));
 347                 p++;
 348         }
 349         put_dev_sector(sect);
 350         printk(" >\n");
 351 #endif
 352 }
 353
 354 /*
 355  * Minix 2.0.0/2.0.2 subpartition support.
 356  * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
 357  * Rajeev V. Pillai    <rajeevvp@yahoo.com>
 358  */
 359 static void parse_minix(struct parsed_partitions *state,
 360                         sector_t offset, sector_t size, int origin)
 361 {
 362 #ifdef CONFIG_MINIX_SUBPARTITION
 363         Sector sect;
 364         unsigned char *data;
 365         struct partition *p;
 366         int i;
 367
 368         data = read_part_sector(state, offset, &sect);
 369         if (!data)
 370                 return;
 371
 372         p = (struct partition *)(data + 0x1be);
 373
 374         /* The first sector of a Minix partition can have either
 375          * a secondary MBR describing its subpartitions, or
 376          * the normal boot sector. */
 377         if (msdos_magic_present (data + 510) &&
 378             SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
 379
 380                 printk(" %s%d: <minix:", state->name, origin);
 381                 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 382                         if (state->next == state->limit)
 383                                 break;
 384                         /* add each partition in use */
 385                         if (SYS_IND(p) == MINIX_PARTITION)
 386                                 put_partition(state, state->next++,
 387                                               start_sect(p), nr_sects(p));
 388                 }
 389                 printk(" >\n");
 390         }
 391         put_dev_sector(sect);
 392 #endif /* CONFIG_MINIX_SUBPARTITION */
 393 }
 394
 395 static struct {
 396         unsigned char id;
 397         void (*parse)(struct parsed_partitions *, sector_t, sector_t, int);
 398 } subtypes[] = {
 399         {FREEBSD_PARTITION, parse_freebsd},
 400         {NETBSD_PARTITION, parse_netbsd},
 401         {OPENBSD_PARTITION, parse_openbsd},
 402         {MINIX_PARTITION, parse_minix},
 403         {UNIXWARE_PARTITION, parse_unixware},
 404         {SOLARIS_X86_PARTITION, parse_solaris_x86},
 405         {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
 406         {0, NULL},
 407 };
 408
 409 int msdos_partition(struct parsed_partitions *state)
 410 {
 411         sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
 412         Sector sect;
 413         unsigned char *data;
 414         struct partition *p;
 415         struct fat_boot_sector *fb;
 416         int slot;
 417
 418         data = read_part_sector(state, 0, &sect);
 419         if (!data)
 420                 return -1;
 421         if (!msdos_magic_present(data + 510)) {
 422                 put_dev_sector(sect);
 423                 return 0;
 424         }
 425
 426         if (aix_magic_present(state, data)) {
 427                 put_dev_sector(sect);
 428                 printk( " [AIX]");
 429                 return 0;
 430         }
 431
 432         /*
 433          * Now that the 55aa signature is present, this is probably
 434          * either the boot sector of a FAT filesystem or a DOS-type
 435          * partition table. Reject this in case the boot indicator
 436          * is not 0 or 0x80.
 437          */
 438         p = (struct partition *) (data + 0x1be);
 439         for (slot = 1; slot <= 4; slot++, p++) {
 440                 if (p->boot_ind != 0 && p->boot_ind != 0x80) {
 441                         /*
 442                          * Even without a valid boot inidicator value
 443                          * its still possible this is valid FAT filesystem
 444                          * without a partition table.
 445                          */
 446                         fb = (struct fat_boot_sector *) data;
 447                         if (slot == 1 && fb->reserved && fb->fats
 448                                 && fat_valid_media(fb->media)) {
 449                                 printk("\n");
 450                                 put_dev_sector(sect);
 451                                 return 1;
 452                         } else {
 453                                 put_dev_sector(sect);
 454                                 return 0;
 455                         }
 456                 }
 457         }
 458
 459 #ifdef CONFIG_EFI_PARTITION
 460         p = (struct partition *) (data + 0x1be);
 461         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 462                 /* If this is an EFI GPT disk, msdos should ignore it. */
 463                 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
 464                         put_dev_sector(sect);
 465                         return 0;
 466                 }
 467         }
 468 #endif
 469         p = (struct partition *) (data + 0x1be);
 470
 471         /*
 472          * Look for partitions in two passes:
 473          * First find the primary and DOS-type extended partitions.
 474          * On the second pass look inside *BSD, Unixware and Solaris partitions.
 475          */
 476
 477         state->next = 5;
 478         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 479                 sector_t start = start_sect(p)*sector_size;
 480                 sector_t size = nr_sects(p)*sector_size;
 481                 if (!size)
 482                         continue;
 483                 if (is_extended_partition(p)) {
 484                         /*
 485                          * prevent someone doing mkfs or mkswap on an
 486                          * extended partition, but leave room for LILO
 487                          * FIXME: this uses one logical sector for > 512b
 488                          * sector, although it may not be enough/proper.
 489                          */
 490                         sector_t n = 2;
 491                         n = min(size, max(sector_size, n));
 492                         put_partition(state, slot, start, n);
 493
 494                         printk(" <");
 495                         parse_extended(state, start, size);
 496                         printk(" >");
 497                         continue;
 498                 }
 499                 put_partition(state, slot, start, size);
 500                 if (SYS_IND(p) == LINUX_RAID_PARTITION)
 501                         state->parts[slot].flags = ADDPART_FLAG_RAID;
 502                 if (SYS_IND(p) == DM6_PARTITION)
 503                         printk("[DM]");
 504                 if (SYS_IND(p) == EZD_PARTITION)
 505                         printk("[EZD]");
 506         }
 507
 508         printk("\n");
 509
 510         /* second pass - output for each on a separate line */
 511         p = (struct partition *) (0x1be + data);
 512         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 513                 unsigned char id = SYS_IND(p);
 514                 int n;
 515
 516                 if (!nr_sects(p))
 517                         continue;
 518
 519                 for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
 520                         ;
 521
 522                 if (!subtypes[n].parse)
 523                         continue;
 524                 subtypes[n].parse(state, start_sect(p) * sector_size,
 525                                   nr_sects(p) * sector_size, slot);
 526         }
 527         put_dev_sector(sect);
 528         return 1;
 529 }