linux/block/partitions/msdos.c
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   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
  37static inline sector_t nr_sects(struct partition *p)
  38{
  39        return (sector_t)get_unaligned_le32(&p->nr_sects);
  40}
  41
  42static inline sector_t start_sect(struct partition *p)
  43{
  44        return (sector_t)get_unaligned_le32(&p->start_sect);
  45}
  46
  47static 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
  57static inline int
  58msdos_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
  68static 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
  98static 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
 120static 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                        if (!nr_sects(p) || is_extended_partition(p))
 165                                continue;
 166
 167                        /* Check the 3rd and 4th entries -
 168                           these sometimes contain random garbage */
 169                        offs = start_sect(p)*sector_size;
 170                        size = nr_sects(p)*sector_size;
 171                        next = this_sector + offs;
 172                        if (i >= 2) {
 173                                if (offs + size > this_size)
 174                                        continue;
 175                                if (next < first_sector)
 176                                        continue;
 177                                if (next + size > first_sector + first_size)
 178                                        continue;
 179                        }
 180
 181                        put_partition(state, state->next, next, size);
 182                        set_info(state, state->next, disksig);
 183                        if (SYS_IND(p) == LINUX_RAID_PARTITION)
 184                                state->parts[state->next].flags = ADDPART_FLAG_RAID;
 185                        loopct = 0;
 186                        if (++state->next == state->limit)
 187                                goto done;
 188                }
 189                /*
 190                 * Next, process the (first) extended partition, if present.
 191                 * (So far, there seems to be no reason to make
 192                 *  parse_extended()  recursive and allow a tree
 193                 *  of extended partitions.)
 194                 * It should be a link to the next logical partition.
 195                 */
 196                p -= 4;
 197                for (i=0; i<4; i++, p++)
 198                        if (nr_sects(p) && is_extended_partition(p))
 199                                break;
 200                if (i == 4)
 201                        goto done;       /* nothing left to do */
 202
 203                this_sector = first_sector + start_sect(p) * sector_size;
 204                this_size = nr_sects(p) * sector_size;
 205                put_dev_sector(sect);
 206        }
 207done:
 208        put_dev_sector(sect);
 209}
 210
 211/* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
 212   indicates linux swap.  Be careful before believing this is Solaris. */
 213
 214static void parse_solaris_x86(struct parsed_partitions *state,
 215                              sector_t offset, sector_t size, int origin)
 216{
 217#ifdef CONFIG_SOLARIS_X86_PARTITION
 218        Sector sect;
 219        struct solaris_x86_vtoc *v;
 220        int i;
 221        short max_nparts;
 222
 223        v = read_part_sector(state, offset + 1, &sect);
 224        if (!v)
 225                return;
 226        if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
 227                put_dev_sector(sect);
 228                return;
 229        }
 230        {
 231                char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
 232
 233                snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
 234                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 235        }
 236        if (le32_to_cpu(v->v_version) != 1) {
 237                char tmp[64];
 238
 239                snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
 240                         le32_to_cpu(v->v_version));
 241                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 242                put_dev_sector(sect);
 243                return;
 244        }
 245        /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
 246        max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
 247        for (i=0; i<max_nparts && state->next<state->limit; i++) {
 248                struct solaris_x86_slice *s = &v->v_slice[i];
 249                char tmp[3 + 10 + 1 + 1];
 250
 251                if (s->s_size == 0)
 252                        continue;
 253                snprintf(tmp, sizeof(tmp), " [s%d]", i);
 254                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 255                /* solaris partitions are relative to current MS-DOS
 256                 * one; must add the offset of the current partition */
 257                put_partition(state, state->next++,
 258                                 le32_to_cpu(s->s_start)+offset,
 259                                 le32_to_cpu(s->s_size));
 260        }
 261        put_dev_sector(sect);
 262        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
 263#endif
 264}
 265
 266#if defined(CONFIG_BSD_DISKLABEL)
 267/*
 268 * Create devices for BSD partitions listed in a disklabel, under a
 269 * dos-like partition. See parse_extended() for more information.
 270 */
 271static void parse_bsd(struct parsed_partitions *state,
 272                      sector_t offset, sector_t size, int origin, char *flavour,
 273                      int max_partitions)
 274{
 275        Sector sect;
 276        struct bsd_disklabel *l;
 277        struct bsd_partition *p;
 278        char tmp[64];
 279
 280        l = read_part_sector(state, offset + 1, &sect);
 281        if (!l)
 282                return;
 283        if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
 284                put_dev_sector(sect);
 285                return;
 286        }
 287
 288        snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
 289        strlcat(state->pp_buf, tmp, PAGE_SIZE);
 290
 291        if (le16_to_cpu(l->d_npartitions) < max_partitions)
 292                max_partitions = le16_to_cpu(l->d_npartitions);
 293        for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
 294                sector_t bsd_start, bsd_size;
 295
 296                if (state->next == state->limit)
 297                        break;
 298                if (p->p_fstype == BSD_FS_UNUSED)
 299                        continue;
 300                bsd_start = le32_to_cpu(p->p_offset);
 301                bsd_size = le32_to_cpu(p->p_size);
 302                if (offset == bsd_start && size == bsd_size)
 303                        /* full parent partition, we have it already */
 304                        continue;
 305                if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
 306                        strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
 307                        continue;
 308                }
 309                put_partition(state, state->next++, bsd_start, bsd_size);
 310        }
 311        put_dev_sector(sect);
 312        if (le16_to_cpu(l->d_npartitions) > max_partitions) {
 313                snprintf(tmp, sizeof(tmp), " (ignored %d more)",
 314                         le16_to_cpu(l->d_npartitions) - max_partitions);
 315                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 316        }
 317        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
 318}
 319#endif
 320
 321static void parse_freebsd(struct parsed_partitions *state,
 322                          sector_t offset, sector_t size, int origin)
 323{
 324#ifdef CONFIG_BSD_DISKLABEL
 325        parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
 326#endif
 327}
 328
 329static void parse_netbsd(struct parsed_partitions *state,
 330                         sector_t offset, sector_t size, int origin)
 331{
 332#ifdef CONFIG_BSD_DISKLABEL
 333        parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
 334#endif
 335}
 336
 337static void parse_openbsd(struct parsed_partitions *state,
 338                          sector_t offset, sector_t size, int origin)
 339{
 340#ifdef CONFIG_BSD_DISKLABEL
 341        parse_bsd(state, offset, size, origin, "openbsd",
 342                  OPENBSD_MAXPARTITIONS);
 343#endif
 344}
 345
 346/*
 347 * Create devices for Unixware partitions listed in a disklabel, under a
 348 * dos-like partition. See parse_extended() for more information.
 349 */
 350static void parse_unixware(struct parsed_partitions *state,
 351                           sector_t offset, sector_t size, int origin)
 352{
 353#ifdef CONFIG_UNIXWARE_DISKLABEL
 354        Sector sect;
 355        struct unixware_disklabel *l;
 356        struct unixware_slice *p;
 357
 358        l = read_part_sector(state, offset + 29, &sect);
 359        if (!l)
 360                return;
 361        if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
 362            le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
 363                put_dev_sector(sect);
 364                return;
 365        }
 366        {
 367                char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
 368
 369                snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
 370                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 371        }
 372        p = &l->vtoc.v_slice[1];
 373        /* I omit the 0th slice as it is the same as whole disk. */
 374        while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
 375                if (state->next == state->limit)
 376                        break;
 377
 378                if (p->s_label != UNIXWARE_FS_UNUSED)
 379                        put_partition(state, state->next++,
 380                                      le32_to_cpu(p->start_sect),
 381                                      le32_to_cpu(p->nr_sects));
 382                p++;
 383        }
 384        put_dev_sector(sect);
 385        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
 386#endif
 387}
 388
 389/*
 390 * Minix 2.0.0/2.0.2 subpartition support.
 391 * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
 392 * Rajeev V. Pillai    <rajeevvp@yahoo.com>
 393 */
 394static void parse_minix(struct parsed_partitions *state,
 395                        sector_t offset, sector_t size, int origin)
 396{
 397#ifdef CONFIG_MINIX_SUBPARTITION
 398        Sector sect;
 399        unsigned char *data;
 400        struct partition *p;
 401        int i;
 402
 403        data = read_part_sector(state, offset, &sect);
 404        if (!data)
 405                return;
 406
 407        p = (struct partition *)(data + 0x1be);
 408
 409        /* The first sector of a Minix partition can have either
 410         * a secondary MBR describing its subpartitions, or
 411         * the normal boot sector. */
 412        if (msdos_magic_present (data + 510) &&
 413            SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
 414                char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
 415
 416                snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
 417                strlcat(state->pp_buf, tmp, PAGE_SIZE);
 418                for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 419                        if (state->next == state->limit)
 420                                break;
 421                        /* add each partition in use */
 422                        if (SYS_IND(p) == MINIX_PARTITION)
 423                                put_partition(state, state->next++,
 424                                              start_sect(p), nr_sects(p));
 425                }
 426                strlcat(state->pp_buf, " >\n", PAGE_SIZE);
 427        }
 428        put_dev_sector(sect);
 429#endif /* CONFIG_MINIX_SUBPARTITION */
 430}
 431
 432static struct {
 433        unsigned char id;
 434        void (*parse)(struct parsed_partitions *, sector_t, sector_t, int);
 435} subtypes[] = {
 436        {FREEBSD_PARTITION, parse_freebsd},
 437        {NETBSD_PARTITION, parse_netbsd},
 438        {OPENBSD_PARTITION, parse_openbsd},
 439        {MINIX_PARTITION, parse_minix},
 440        {UNIXWARE_PARTITION, parse_unixware},
 441        {SOLARIS_X86_PARTITION, parse_solaris_x86},
 442        {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
 443        {0, NULL},
 444};
 445
 446int msdos_partition(struct parsed_partitions *state)
 447{
 448        sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
 449        Sector sect;
 450        unsigned char *data;
 451        struct partition *p;
 452        struct fat_boot_sector *fb;
 453        int slot;
 454        u32 disksig;
 455
 456        data = read_part_sector(state, 0, &sect);
 457        if (!data)
 458                return -1;
 459
 460        /*
 461         * Note order! (some AIX disks, e.g. unbootable kind,
 462         * have no MSDOS 55aa)
 463         */
 464        if (aix_magic_present(state, data)) {
 465                put_dev_sector(sect);
 466#ifdef CONFIG_AIX_PARTITION
 467                return aix_partition(state);
 468#else
 469                strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
 470                return 0;
 471#endif
 472        }
 473
 474        if (!msdos_magic_present(data + 510)) {
 475                put_dev_sector(sect);
 476                return 0;
 477        }
 478
 479        /*
 480         * Now that the 55aa signature is present, this is probably
 481         * either the boot sector of a FAT filesystem or a DOS-type
 482         * partition table. Reject this in case the boot indicator
 483         * is not 0 or 0x80.
 484         */
 485        p = (struct partition *) (data + 0x1be);
 486        for (slot = 1; slot <= 4; slot++, p++) {
 487                if (p->boot_ind != 0 && p->boot_ind != 0x80) {
 488                        /*
 489                         * Even without a valid boot inidicator value
 490                         * its still possible this is valid FAT filesystem
 491                         * without a partition table.
 492                         */
 493                        fb = (struct fat_boot_sector *) data;
 494                        if (slot == 1 && fb->reserved && fb->fats
 495                                && fat_valid_media(fb->media)) {
 496                                strlcat(state->pp_buf, "\n", PAGE_SIZE);
 497                                put_dev_sector(sect);
 498                                return 1;
 499                        } else {
 500                                put_dev_sector(sect);
 501                                return 0;
 502                        }
 503                }
 504        }
 505
 506#ifdef CONFIG_EFI_PARTITION
 507        p = (struct partition *) (data + 0x1be);
 508        for (slot = 1 ; slot <= 4 ; slot++, p++) {
 509                /* If this is an EFI GPT disk, msdos should ignore it. */
 510                if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
 511                        put_dev_sector(sect);
 512                        return 0;
 513                }
 514        }
 515#endif
 516        p = (struct partition *) (data + 0x1be);
 517
 518        disksig = le32_to_cpup((__le32 *)(data + 0x1b8));
 519
 520        /*
 521         * Look for partitions in two passes:
 522         * First find the primary and DOS-type extended partitions.
 523         * On the second pass look inside *BSD, Unixware and Solaris partitions.
 524         */
 525
 526        state->next = 5;
 527        for (slot = 1 ; slot <= 4 ; slot++, p++) {
 528                sector_t start = start_sect(p)*sector_size;
 529                sector_t size = nr_sects(p)*sector_size;
 530                if (!size)
 531                        continue;
 532                if (is_extended_partition(p)) {
 533                        /*
 534                         * prevent someone doing mkfs or mkswap on an
 535                         * extended partition, but leave room for LILO
 536                         * FIXME: this uses one logical sector for > 512b
 537                         * sector, although it may not be enough/proper.
 538                         */
 539                        sector_t n = 2;
 540                        n = min(size, max(sector_size, n));
 541                        put_partition(state, slot, start, n);
 542
 543                        strlcat(state->pp_buf, " <", PAGE_SIZE);
 544                        parse_extended(state, start, size, disksig);
 545                        strlcat(state->pp_buf, " >", PAGE_SIZE);
 546                        continue;
 547                }
 548                put_partition(state, slot, start, size);
 549                set_info(state, slot, disksig);
 550                if (SYS_IND(p) == LINUX_RAID_PARTITION)
 551                        state->parts[slot].flags = ADDPART_FLAG_RAID;
 552                if (SYS_IND(p) == DM6_PARTITION)
 553                        strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
 554                if (SYS_IND(p) == EZD_PARTITION)
 555                        strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
 556        }
 557
 558        strlcat(state->pp_buf, "\n", PAGE_SIZE);
 559
 560        /* second pass - output for each on a separate line */
 561        p = (struct partition *) (0x1be + data);
 562        for (slot = 1 ; slot <= 4 ; slot++, p++) {
 563                unsigned char id = SYS_IND(p);
 564                int n;
 565
 566                if (!nr_sects(p))
 567                        continue;
 568
 569                for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
 570                        ;
 571
 572                if (!subtypes[n].parse)
 573                        continue;
 574                subtypes[n].parse(state, start_sect(p) * sector_size,
 575                                  nr_sects(p) * sector_size, slot);
 576        }
 577        put_dev_sector(sect);
 578        return 1;
 579}
 580
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