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