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 #define NR_SECTS(p)     ({ __le32 __a = get_unaligned(&p->nr_sects);    \
  36                                 le32_to_cpu(__a); \
  37                         })
  38
  39 #define START_SECT(p)   ({ __le32 __a = get_unaligned(&p->start_sect);  \
  40                                 le32_to_cpu(__a); \
  41                         })
  42
  43 static inline int is_extended_partition(struct partition *p)
  44 {
  45         return (SYS_IND(p) == DOS_EXTENDED_PARTITION ||
  46                 SYS_IND(p) == WIN98_EXTENDED_PARTITION ||
  47                 SYS_IND(p) == LINUX_EXTENDED_PARTITION);
  48 }
  49
  50 #define MSDOS_LABEL_MAGIC1      0x55
  51 #define MSDOS_LABEL_MAGIC2      0xAA
  52
  53 static inline int
  54 msdos_magic_present(unsigned char *p)
  55 {
  56         return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2);
  57 }
  58
  59 /* Value is EBCDIC 'IBMA' */
  60 #define AIX_LABEL_MAGIC1        0xC9
  61 #define AIX_LABEL_MAGIC2        0xC2
  62 #define AIX_LABEL_MAGIC3        0xD4
  63 #define AIX_LABEL_MAGIC4        0xC1
  64 static int aix_magic_present(unsigned char *p, struct block_device *bdev)
  65 {
  66         struct partition *pt = (struct partition *) (p + 0x1be);
  67         Sector sect;
  68         unsigned char *d;
  69         int slot, ret = 0;
  70
  71         if (!(p[0] == AIX_LABEL_MAGIC1 &&
  72                 p[1] == AIX_LABEL_MAGIC2 &&
  73                 p[2] == AIX_LABEL_MAGIC3 &&
  74                 p[3] == AIX_LABEL_MAGIC4))
  75                 return 0;
  76         /* Assume the partition table is valid if Linux partitions exists */
  77         for (slot = 1; slot <= 4; slot++, pt++) {
  78                 if (pt->sys_ind == LINUX_SWAP_PARTITION ||
  79                         pt->sys_ind == LINUX_RAID_PARTITION ||
  80                         pt->sys_ind == LINUX_DATA_PARTITION ||
  81                         pt->sys_ind == LINUX_LVM_PARTITION ||
  82                         is_extended_partition(pt))
  83                         return 0;
  84         }
  85         d = read_dev_sector(bdev, 7, &sect);
  86         if (d) {
  87                 if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
  88                         ret = 1;
  89                 put_dev_sector(sect);
  90         };
  91         return ret;
  92 }
  93
  94 /*
  95  * Create devices for each logical partition in an extended partition.
  96  * The logical partitions form a linked list, with each entry being
  97  * a partition table with two entries.  The first entry
  98  * is the real data partition (with a start relative to the partition
  99  * table start).  The second is a pointer to the next logical partition
 100  * (with a start relative to the entire extended partition).
 101  * We do not create a Linux partition for the partition tables, but
 102  * only for the actual data partitions.
 103  */
 104
 105 static void
 106 parse_extended(struct parsed_partitions *state, struct block_device *bdev,
 107                         u32 first_sector, u32 first_size)
 108 {
 109         struct partition *p;
 110         Sector sect;
 111         unsigned char *data;
 112         u32 this_sector, this_size;
 113         int sector_size = bdev_hardsect_size(bdev) / 512;
 114         int loopct = 0;         /* number of links followed
 115                                    without finding a data partition */
 116         int i;
 117
 118         this_sector = first_sector;
 119         this_size = first_size;
 120
 121         while (1) {
 122                 if (++loopct > 100)
 123                         return;
 124                 if (state->next == state->limit)
 125                         return;
 126                 data = read_dev_sector(bdev, this_sector, &sect);
 127                 if (!data)
 128                         return;
 129
 130                 if (!msdos_magic_present(data + 510))
 131                         goto done;
 132
 133                 p = (struct partition *) (data + 0x1be);
 134
 135                 /*
 136                  * Usually, the first entry is the real data partition,
 137                  * the 2nd entry is the next extended partition, or empty,
 138                  * and the 3rd and 4th entries are unused.
 139                  * However, DRDOS sometimes has the extended partition as
 140                  * the first entry (when the data partition is empty),
 141                  * and OS/2 seems to use all four entries.
 142                  */
 143
 144                 /*
 145                  * First process the data partition(s)
 146                  */
 147                 for (i=0; i<4; i++, p++) {
 148                         u32 offs, size, next;
 149                         if (!NR_SECTS(p) || is_extended_partition(p))
 150                                 continue;
 151
 152                         /* Check the 3rd and 4th entries -
 153                            these sometimes contain random garbage */
 154                         offs = START_SECT(p)*sector_size;
 155                         size = NR_SECTS(p)*sector_size;
 156                         next = this_sector + offs;
 157                         if (i >= 2) {
 158                                 if (offs + size > this_size)
 159                                         continue;
 160                                 if (next < first_sector)
 161                                         continue;
 162                                 if (next + size > first_sector + first_size)
 163                                         continue;
 164                         }
 165
 166                         put_partition(state, state->next, next, size);
 167                         if (SYS_IND(p) == LINUX_RAID_PARTITION)
 168                                 state->parts[state->next].flags = ADDPART_FLAG_RAID;
 169                         loopct = 0;
 170                         if (++state->next == state->limit)
 171                                 goto done;
 172                 }
 173                 /*
 174                  * Next, process the (first) extended partition, if present.
 175                  * (So far, there seems to be no reason to make
 176                  *  parse_extended()  recursive and allow a tree
 177                  *  of extended partitions.)
 178                  * It should be a link to the next logical partition.
 179                  */
 180                 p -= 4;
 181                 for (i=0; i<4; i++, p++)
 182                         if (NR_SECTS(p) && is_extended_partition(p))
 183                                 break;
 184                 if (i == 4)
 185                         goto done;       /* nothing left to do */
 186
 187                 this_sector = first_sector + START_SECT(p) * sector_size;
 188                 this_size = NR_SECTS(p) * sector_size;
 189                 put_dev_sector(sect);
 190         }
 191 done:
 192         put_dev_sector(sect);
 193 }
 194
 195 /* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
 196    indicates linux swap.  Be careful before believing this is Solaris. */
 197
 198 static void
 199 parse_solaris_x86(struct parsed_partitions *state, struct block_device *bdev,
 200                         u32 offset, u32 size, int origin)
 201 {
 202 #ifdef CONFIG_SOLARIS_X86_PARTITION
 203         Sector sect;
 204         struct solaris_x86_vtoc *v;
 205         int i;
 206         short max_nparts;
 207
 208         v = (struct solaris_x86_vtoc *)read_dev_sector(bdev, offset+1, &sect);
 209         if (!v)
 210                 return;
 211         if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
 212                 put_dev_sector(sect);
 213                 return;
 214         }
 215         printk(" %s%d: <solaris:", state->name, origin);
 216         if (le32_to_cpu(v->v_version) != 1) {
 217                 printk("  cannot handle version %d vtoc>\n",
 218                         le32_to_cpu(v->v_version));
 219                 put_dev_sector(sect);
 220                 return;
 221         }
 222         /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
 223         max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
 224         for (i=0; i<max_nparts && state->next<state->limit; i++) {
 225                 struct solaris_x86_slice *s = &v->v_slice[i];
 226                 if (s->s_size == 0)
 227                         continue;
 228                 printk(" [s%d]", i);
 229                 /* solaris partitions are relative to current MS-DOS
 230                  * one; must add the offset of the current partition */
 231                 put_partition(state, state->next++,
 232                                  le32_to_cpu(s->s_start)+offset,
 233                                  le32_to_cpu(s->s_size));
 234         }
 235         put_dev_sector(sect);
 236         printk(" >\n");
 237 #endif
 238 }
 239
 240 #if defined(CONFIG_BSD_DISKLABEL)
 241 /*
 242  * Create devices for BSD partitions listed in a disklabel, under a
 243  * dos-like partition. See parse_extended() for more information.
 244  */
 245 static void
 246 parse_bsd(struct parsed_partitions *state, struct block_device *bdev,
 247                 u32 offset, u32 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 = (struct bsd_disklabel *)read_dev_sector(bdev, 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                 u32 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
 292 parse_freebsd(struct parsed_partitions *state, struct block_device *bdev,
 293                 u32 offset, u32 size, int origin)
 294 {
 295 #ifdef CONFIG_BSD_DISKLABEL
 296         parse_bsd(state, bdev, offset, size, origin,
 297                         "bsd", BSD_MAXPARTITIONS);
 298 #endif
 299 }
 300
 301 static void
 302 parse_netbsd(struct parsed_partitions *state, struct block_device *bdev,
 303                 u32 offset, u32 size, int origin)
 304 {
 305 #ifdef CONFIG_BSD_DISKLABEL
 306         parse_bsd(state, bdev, offset, size, origin,
 307                         "netbsd", BSD_MAXPARTITIONS);
 308 #endif
 309 }
 310
 311 static void
 312 parse_openbsd(struct parsed_partitions *state, struct block_device *bdev,
 313                 u32 offset, u32 size, int origin)
 314 {
 315 #ifdef CONFIG_BSD_DISKLABEL
 316         parse_bsd(state, bdev, offset, size, origin,
 317                         "openbsd", OPENBSD_MAXPARTITIONS);
 318 #endif
 319 }
 320
 321 /*
 322  * Create devices for Unixware partitions listed in a disklabel, under a
 323  * dos-like partition. See parse_extended() for more information.
 324  */
 325 static void
 326 parse_unixware(struct parsed_partitions *state, struct block_device *bdev,
 327                 u32 offset, u32 size, int origin)
 328 {
 329 #ifdef CONFIG_UNIXWARE_DISKLABEL
 330         Sector sect;
 331         struct unixware_disklabel *l;
 332         struct unixware_slice *p;
 333
 334         l = (struct unixware_disklabel *)read_dev_sector(bdev, offset+29, &sect);
 335         if (!l)
 336                 return;
 337         if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
 338             le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
 339                 put_dev_sector(sect);
 340                 return;
 341         }
 342         printk(" %s%d: <unixware:", state->name, origin);
 343         p = &l->vtoc.v_slice[1];
 344         /* I omit the 0th slice as it is the same as whole disk. */
 345         while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
 346                 if (state->next == state->limit)
 347                         break;
 348
 349                 if (p->s_label != UNIXWARE_FS_UNUSED)
 350                         put_partition(state, state->next++,
 351                                                 START_SECT(p), NR_SECTS(p));
 352                 p++;
 353         }
 354         put_dev_sector(sect);
 355         printk(" >\n");
 356 #endif
 357 }
 358
 359 /*
 360  * Minix 2.0.0/2.0.2 subpartition support.
 361  * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
 362  * Rajeev V. Pillai    <rajeevvp@yahoo.com>
 363  */
 364 static void
 365 parse_minix(struct parsed_partitions *state, struct block_device *bdev,
 366                 u32 offset, u32 size, int origin)
 367 {
 368 #ifdef CONFIG_MINIX_SUBPARTITION
 369         Sector sect;
 370         unsigned char *data;
 371         struct partition *p;
 372         int i;
 373
 374         data = read_dev_sector(bdev, offset, &sect);
 375         if (!data)
 376                 return;
 377
 378         p = (struct partition *)(data + 0x1be);
 379
 380         /* The first sector of a Minix partition can have either
 381          * a secondary MBR describing its subpartitions, or
 382          * the normal boot sector. */
 383         if (msdos_magic_present (data + 510) &&
 384             SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
 385
 386                 printk(" %s%d: <minix:", state->name, origin);
 387                 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 388                         if (state->next == state->limit)
 389                                 break;
 390                         /* add each partition in use */
 391                         if (SYS_IND(p) == MINIX_PARTITION)
 392                                 put_partition(state, state->next++,
 393                                               START_SECT(p), NR_SECTS(p));
 394                 }
 395                 printk(" >\n");
 396         }
 397         put_dev_sector(sect);
 398 #endif /* CONFIG_MINIX_SUBPARTITION */
 399 }
 400
 401 static struct {
 402         unsigned char id;
 403         void (*parse)(struct parsed_partitions *, struct block_device *,
 404                         u32, u32, int);
 405 } subtypes[] = {
 406         {FREEBSD_PARTITION, parse_freebsd},
 407         {NETBSD_PARTITION, parse_netbsd},
 408         {OPENBSD_PARTITION, parse_openbsd},
 409         {MINIX_PARTITION, parse_minix},
 410         {UNIXWARE_PARTITION, parse_unixware},
 411         {SOLARIS_X86_PARTITION, parse_solaris_x86},
 412         {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
 413         {0, NULL},
 414 };
 415
 416 int msdos_partition(struct parsed_partitions *state, struct block_device *bdev)
 417 {
 418         int sector_size = bdev_hardsect_size(bdev) / 512;
 419         Sector sect;
 420         unsigned char *data;
 421         struct partition *p;
 422         struct fat_boot_sector *fb;
 423         int slot;
 424
 425         data = read_dev_sector(bdev, 0, &sect);
 426         if (!data)
 427                 return -1;
 428         if (!msdos_magic_present(data + 510)) {
 429                 put_dev_sector(sect);
 430                 return 0;
 431         }
 432
 433         if (aix_magic_present(data, bdev)) {
 434                 put_dev_sector(sect);
 435                 printk( " [AIX]");
 436                 return 0;
 437         }
 438
 439         /*
 440          * Now that the 55aa signature is present, this is probably
 441          * either the boot sector of a FAT filesystem or a DOS-type
 442          * partition table. Reject this in case the boot indicator
 443          * is not 0 or 0x80.
 444          */
 445         p = (struct partition *) (data + 0x1be);
 446         for (slot = 1; slot <= 4; slot++, p++) {
 447                 if (p->boot_ind != 0 && p->boot_ind != 0x80) {
 448                         /*
 449                          * Even without a valid boot inidicator value
 450                          * its still possible this is valid FAT filesystem
 451                          * without a partition table.
 452                          */
 453                         fb = (struct fat_boot_sector *) data;
 454                         if (slot == 1 && fb->reserved && fb->fats
 455                                 && fat_valid_media(fb->media)) {
 456                                 printk("\n");
 457                                 put_dev_sector(sect);
 458                                 return 1;
 459                         } else {
 460                                 put_dev_sector(sect);
 461                                 return 0;
 462                         }
 463                 }
 464         }
 465
 466 #ifdef CONFIG_EFI_PARTITION
 467         p = (struct partition *) (data + 0x1be);
 468         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 469                 /* If this is an EFI GPT disk, msdos should ignore it. */
 470                 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
 471                         put_dev_sector(sect);
 472                         return 0;
 473                 }
 474         }
 475 #endif
 476         p = (struct partition *) (data + 0x1be);
 477
 478         /*
 479          * Look for partitions in two passes:
 480          * First find the primary and DOS-type extended partitions.
 481          * On the second pass look inside *BSD, Unixware and Solaris partitions.
 482          */
 483
 484         state->next = 5;
 485         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 486                 u32 start = START_SECT(p)*sector_size;
 487                 u32 size = NR_SECTS(p)*sector_size;
 488                 if (!size)
 489                         continue;
 490                 if (is_extended_partition(p)) {
 491                         /* prevent someone doing mkfs or mkswap on an
 492                            extended partition, but leave room for LILO */
 493                         put_partition(state, slot, start, size == 1 ? 1 : 2);
 494                         printk(" <");
 495                         parse_extended(state, bdev, 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 = 1;
 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, bdev, START_SECT(p)*sector_size,
 525                                                 NR_SECTS(p)*sector_size, slot);
 526         }
 527         put_dev_sector(sect);
 528         return 1;
 529 }