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
  22 #include <linux/config.h>
  23
  24 #include "check.h"
  25 #include "msdos.h"
  26 #include "efi.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 #define NR_SECTS(p)     ({ __typeof__(p->nr_sects) __a =        \
  37                                 get_unaligned(&p->nr_sects);    \
  38                                 le32_to_cpu(__a); \
  39                         })
  40
  41 #define START_SECT(p)   ({ __typeof__(p->start_sect) __a =      \
  42                                 get_unaligned(&p->start_sect);  \
  43                                 le32_to_cpu(__a); \
  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 /*
  63  * Create devices for each logical partition in an extended partition.
  64  * The logical partitions form a linked list, with each entry being
  65  * a partition table with two entries.  The first entry
  66  * is the real data partition (with a start relative to the partition
  67  * table start).  The second is a pointer to the next logical partition
  68  * (with a start relative to the entire extended partition).
  69  * We do not create a Linux partition for the partition tables, but
  70  * only for the actual data partitions.
  71  */
  72
  73 static void
  74 parse_extended(struct parsed_partitions *state, struct block_device *bdev,
  75                         u32 first_sector, u32 first_size)
  76 {
  77         struct partition *p;
  78         Sector sect;
  79         unsigned char *data;
  80         u32 this_sector, this_size;
  81         int sector_size = bdev_hardsect_size(bdev) / 512;
  82         int loopct = 0;         /* number of links followed
  83                                    without finding a data partition */
  84         int i;
  85
  86         this_sector = first_sector;
  87         this_size = first_size;
  88
  89         while (1) {
  90                 if (++loopct > 100)
  91                         return;
  92                 if (state->next == state->limit)
  93                         return;
  94                 data = read_dev_sector(bdev, this_sector, &sect);
  95                 if (!data)
  96                         return;
  97
  98                 if (!msdos_magic_present(data + 510))
  99                         goto done;
 100
 101                 p = (struct partition *) (data + 0x1be);
 102
 103                 /*
 104                  * Usually, the first entry is the real data partition,
 105                  * the 2nd entry is the next extended partition, or empty,
 106                  * and the 3rd and 4th entries are unused.
 107                  * However, DRDOS sometimes has the extended partition as
 108                  * the first entry (when the data partition is empty),
 109                  * and OS/2 seems to use all four entries.
 110                  */
 111
 112                 /*
 113                  * First process the data partition(s)
 114                  */
 115                 for (i=0; i<4; i++, p++) {
 116                         u32 offs, size, next;
 117                         if (!NR_SECTS(p) || is_extended_partition(p))
 118                                 continue;
 119
 120                         /* Check the 3rd and 4th entries -
 121                            these sometimes contain random garbage */
 122                         offs = START_SECT(p)*sector_size;
 123                         size = NR_SECTS(p)*sector_size;
 124                         next = this_sector + offs;
 125                         if (i >= 2) {
 126                                 if (offs + size > this_size)
 127                                         continue;
 128                                 if (next < first_sector)
 129                                         continue;
 130                                 if (next + size > first_sector + first_size)
 131                                         continue;
 132                         }
 133
 134                         put_partition(state, state->next, next, size);
 135                         if (SYS_IND(p) == LINUX_RAID_PARTITION)
 136                                 state->parts[state->next].flags = 1;
 137                         loopct = 0;
 138                         if (++state->next == state->limit)
 139                                 goto done;
 140                 }
 141                 /*
 142                  * Next, process the (first) extended partition, if present.
 143                  * (So far, there seems to be no reason to make
 144                  *  parse_extended()  recursive and allow a tree
 145                  *  of extended partitions.)
 146                  * It should be a link to the next logical partition.
 147                  */
 148                 p -= 4;
 149                 for (i=0; i<4; i++, p++)
 150                         if (NR_SECTS(p) && is_extended_partition(p))
 151                                 break;
 152                 if (i == 4)
 153                         goto done;       /* nothing left to do */
 154
 155                 this_sector = first_sector + START_SECT(p) * sector_size;
 156                 this_size = NR_SECTS(p) * sector_size;
 157                 put_dev_sector(sect);
 158         }
 159 done:
 160         put_dev_sector(sect);
 161 }
 162
 163 /* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
 164    indicates linux swap.  Be careful before believing this is Solaris. */
 165
 166 static void
 167 parse_solaris_x86(struct parsed_partitions *state, struct block_device *bdev,
 168                         u32 offset, u32 size, int origin)
 169 {
 170 #ifdef CONFIG_SOLARIS_X86_PARTITION
 171         Sector sect;
 172         struct solaris_x86_vtoc *v;
 173         int i;
 174
 175         v = (struct solaris_x86_vtoc *)read_dev_sector(bdev, offset+1, &sect);
 176         if (!v)
 177                 return;
 178         if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
 179                 put_dev_sector(sect);
 180                 return;
 181         }
 182         printk(" %s%d: <solaris:", state->name, origin);
 183         if (le32_to_cpu(v->v_version) != 1) {
 184                 printk("  cannot handle version %d vtoc>\n",
 185                         le32_to_cpu(v->v_version));
 186                 put_dev_sector(sect);
 187                 return;
 188         }
 189         for (i=0; i<SOLARIS_X86_NUMSLICE && state->next<state->limit; i++) {
 190                 struct solaris_x86_slice *s = &v->v_slice[i];
 191                 if (s->s_size == 0)
 192                         continue;
 193                 printk(" [s%d]", i);
 194                 /* solaris partitions are relative to current MS-DOS
 195                  * one; must add the offset of the current partition */
 196                 put_partition(state, state->next++,
 197                                  le32_to_cpu(s->s_start)+offset,
 198                                  le32_to_cpu(s->s_size));
 199         }
 200         put_dev_sector(sect);
 201         printk(" >\n");
 202 #endif
 203 }
 204
 205 #if defined(CONFIG_BSD_DISKLABEL)
 206 /*
 207  * Create devices for BSD partitions listed in a disklabel, under a
 208  * dos-like partition. See parse_extended() for more information.
 209  */
 210 static void
 211 parse_bsd(struct parsed_partitions *state, struct block_device *bdev,
 212                 u32 offset, u32 size, int origin, char *flavour,
 213                 int max_partitions)
 214 {
 215         Sector sect;
 216         struct bsd_disklabel *l;
 217         struct bsd_partition *p;
 218
 219         l = (struct bsd_disklabel *)read_dev_sector(bdev, offset+1, &sect);
 220         if (!l)
 221                 return;
 222         if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
 223                 put_dev_sector(sect);
 224                 return;
 225         }
 226         printk(" %s%d: <%s:", state->name, origin, flavour);
 227
 228         if (le16_to_cpu(l->d_npartitions) < max_partitions)
 229                 max_partitions = le16_to_cpu(l->d_npartitions);
 230         for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
 231                 u32 bsd_start, bsd_size;
 232
 233                 if (state->next == state->limit)
 234                         break;
 235                 if (p->p_fstype == BSD_FS_UNUSED)
 236                         continue;
 237                 bsd_start = le32_to_cpu(p->p_offset);
 238                 bsd_size = le32_to_cpu(p->p_size);
 239                 if (offset == bsd_start && size == bsd_size)
 240                         /* full parent partition, we have it already */
 241                         continue;
 242                 if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
 243                         printk("bad subpartition - ignored\n");
 244                         continue;
 245                 }
 246                 put_partition(state, state->next++, bsd_start, bsd_size);
 247         }
 248         put_dev_sector(sect);
 249         if (le16_to_cpu(l->d_npartitions) > max_partitions)
 250                 printk(" (ignored %d more)",
 251                        le16_to_cpu(l->d_npartitions) - max_partitions);
 252         printk(" >\n");
 253 }
 254 #endif
 255
 256 static void
 257 parse_freebsd(struct parsed_partitions *state, struct block_device *bdev,
 258                 u32 offset, u32 size, int origin)
 259 {
 260 #ifdef CONFIG_BSD_DISKLABEL
 261         parse_bsd(state, bdev, offset, size, origin,
 262                         "bsd", BSD_MAXPARTITIONS);
 263 #endif
 264 }
 265
 266 static void
 267 parse_netbsd(struct parsed_partitions *state, struct block_device *bdev,
 268                 u32 offset, u32 size, int origin)
 269 {
 270 #ifdef CONFIG_BSD_DISKLABEL
 271         parse_bsd(state, bdev, offset, size, origin,
 272                         "netbsd", BSD_MAXPARTITIONS);
 273 #endif
 274 }
 275
 276 static void
 277 parse_openbsd(struct parsed_partitions *state, struct block_device *bdev,
 278                 u32 offset, u32 size, int origin)
 279 {
 280 #ifdef CONFIG_BSD_DISKLABEL
 281         parse_bsd(state, bdev, offset, size, origin,
 282                         "openbsd", OPENBSD_MAXPARTITIONS);
 283 #endif
 284 }
 285
 286 /*
 287  * Create devices for Unixware partitions listed in a disklabel, under a
 288  * dos-like partition. See parse_extended() for more information.
 289  */
 290 static void
 291 parse_unixware(struct parsed_partitions *state, struct block_device *bdev,
 292                 u32 offset, u32 size, int origin)
 293 {
 294 #ifdef CONFIG_UNIXWARE_DISKLABEL
 295         Sector sect;
 296         struct unixware_disklabel *l;
 297         struct unixware_slice *p;
 298
 299         l = (struct unixware_disklabel *)read_dev_sector(bdev, offset+29, &sect);
 300         if (!l)
 301                 return;
 302         if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
 303             le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
 304                 put_dev_sector(sect);
 305                 return;
 306         }
 307         printk(" %s%d: <unixware:", state->name, origin);
 308         p = &l->vtoc.v_slice[1];
 309         /* I omit the 0th slice as it is the same as whole disk. */
 310         while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
 311                 if (state->next == state->limit)
 312                         break;
 313
 314                 if (p->s_label != UNIXWARE_FS_UNUSED)
 315                         put_partition(state, state->next++,
 316                                                 START_SECT(p), NR_SECTS(p));
 317                 p++;
 318         }
 319         put_dev_sector(sect);
 320         printk(" >\n");
 321 #endif
 322 }
 323
 324 /*
 325  * Minix 2.0.0/2.0.2 subpartition support.
 326  * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
 327  * Rajeev V. Pillai    <rajeevvp@yahoo.com>
 328  */
 329 static void
 330 parse_minix(struct parsed_partitions *state, struct block_device *bdev,
 331                 u32 offset, u32 size, int origin)
 332 {
 333 #ifdef CONFIG_MINIX_SUBPARTITION
 334         Sector sect;
 335         unsigned char *data;
 336         struct partition *p;
 337         int i;
 338
 339         data = read_dev_sector(bdev, offset, &sect);
 340         if (!data)
 341                 return;
 342
 343         p = (struct partition *)(data + 0x1be);
 344
 345         /* The first sector of a Minix partition can have either
 346          * a secondary MBR describing its subpartitions, or
 347          * the normal boot sector. */
 348         if (msdos_magic_present (data + 510) &&
 349             SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
 350
 351                 printk(" %s%d: <minix:", state->name, origin);
 352                 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 353                         if (state->next == state->limit)
 354                                 break;
 355                         /* add each partition in use */
 356                         if (SYS_IND(p) == MINIX_PARTITION)
 357                                 put_partition(state, state->next++,
 358                                               START_SECT(p), NR_SECTS(p));
 359                 }
 360                 printk(" >\n");
 361         }
 362         put_dev_sector(sect);
 363 #endif /* CONFIG_MINIX_SUBPARTITION */
 364 }
 365
 366 static struct {
 367         unsigned char id;
 368         void (*parse)(struct parsed_partitions *, struct block_device *,
 369                         u32, u32, int);
 370 } subtypes[] = {
 371         {FREEBSD_PARTITION, parse_freebsd},
 372         {NETBSD_PARTITION, parse_netbsd},
 373         {OPENBSD_PARTITION, parse_openbsd},
 374         {MINIX_PARTITION, parse_minix},
 375         {UNIXWARE_PARTITION, parse_unixware},
 376         {SOLARIS_X86_PARTITION, parse_solaris_x86},
 377         {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
 378         {0, NULL},
 379 };
 380
 381 int msdos_partition(struct parsed_partitions *state, struct block_device *bdev)
 382 {
 383         int sector_size = bdev_hardsect_size(bdev) / 512;
 384         Sector sect;
 385         unsigned char *data;
 386         struct partition *p;
 387         int slot;
 388
 389         data = read_dev_sector(bdev, 0, &sect);
 390         if (!data)
 391                 return -1;
 392         if (!msdos_magic_present(data + 510)) {
 393                 put_dev_sector(sect);
 394                 return 0;
 395         }
 396
 397         /*
 398          * Now that the 55aa signature is present, this is probably
 399          * either the boot sector of a FAT filesystem or a DOS-type
 400          * partition table. Reject this in case the boot indicator
 401          * is not 0 or 0x80.
 402          */
 403         p = (struct partition *) (data + 0x1be);
 404         for (slot = 1; slot <= 4; slot++, p++) {
 405                 if (p->boot_ind != 0 && p->boot_ind != 0x80) {
 406                         put_dev_sector(sect);
 407                         return 0;
 408                 }
 409         }
 410
 411 #ifdef CONFIG_EFI_PARTITION
 412         p = (struct partition *) (data + 0x1be);
 413         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 414                 /* If this is an EFI GPT disk, msdos should ignore it. */
 415                 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
 416                         put_dev_sector(sect);
 417                         return 0;
 418                 }
 419         }
 420 #endif
 421         p = (struct partition *) (data + 0x1be);
 422
 423         /*
 424          * Look for partitions in two passes:
 425          * First find the primary and DOS-type extended partitions.
 426          * On the second pass look inside *BSD, Unixware and Solaris partitions.
 427          */
 428
 429         state->next = 5;
 430         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 431                 u32 start = START_SECT(p)*sector_size;
 432                 u32 size = NR_SECTS(p)*sector_size;
 433                 if (!size)
 434                         continue;
 435                 if (is_extended_partition(p)) {
 436                         /* prevent someone doing mkfs or mkswap on an
 437                            extended partition, but leave room for LILO */
 438                         put_partition(state, slot, start, size == 1 ? 1 : 2);
 439                         printk(" <");
 440                         parse_extended(state, bdev, start, size);
 441                         printk(" >");
 442                         continue;
 443                 }
 444                 put_partition(state, slot, start, size);
 445                 if (SYS_IND(p) == LINUX_RAID_PARTITION)
 446                         state->parts[slot].flags = 1;
 447                 if (SYS_IND(p) == DM6_PARTITION)
 448                         printk("[DM]");
 449                 if (SYS_IND(p) == EZD_PARTITION)
 450                         printk("[EZD]");
 451         }
 452
 453         printk("\n");
 454
 455         /* second pass - output for each on a separate line */
 456         p = (struct partition *) (0x1be + data);
 457         for (slot = 1 ; slot <= 4 ; slot++, p++) {
 458                 unsigned char id = SYS_IND(p);
 459                 int n;
 460
 461                 if (!NR_SECTS(p))
 462                         continue;
 463
 464                 for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
 465                         ;
 466
 467                 if (!subtypes[n].parse)
 468                         continue;
 469                 subtypes[n].parse(state, bdev, START_SECT(p)*sector_size,
 470                                                 NR_SECTS(p)*sector_size, slot);
 471         }
 472         put_dev_sector(sect);
 473         return 1;
 474 }