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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, [email protected], 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(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 
108 static 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++) {
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  }
193 done:
194  put_dev_sector(sect);
195 }
196 
197 /* [email protected]: Solaris has a nasty indicator: 0x82 which also
198  indicates linux swap. Be careful before believing this is Solaris. */
199 
200 static 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  */
257 static 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 
307 static 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 
315 static 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 
323 static 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  */
336 static 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 <[email protected]>
378  * Rajeev V. Pillai <[email protected]>
379  */
380 static 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 
418 static struct {
419  unsigned char id;
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 
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 }