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
  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
  36static inline sector_t nr_sects(struct partition *p)
  37{
  38        return (sector_t)get_unaligned_le32(&p->nr_sects);
  39}
  40
  41static inline sector_t start_sect(struct partition *p)
  42{
  43        return (sector_t)get_unaligned_le32(&p->start_sect);
  44}
  45
  46static 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
  56static inline int
  57msdos_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
  67static 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
 108static 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        }
 193done:
 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
 200static 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 */
 257static 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
 307static 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
 315static 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
 323static 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 */
 336static 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 */
 380static 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
 418static 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 
 432int 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}
 553
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