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
nr_sects(struct partition * p)36 static inline sector_t nr_sects(struct partition *p)
37 {
38 return (sector_t)get_unaligned_le32(&p->nr_sects);
39 }
40
start_sect(struct partition * p)41 static inline sector_t start_sect(struct partition *p)
42 {
43 return (sector_t)get_unaligned_le32(&p->start_sect);
44 }
45
is_extended_partition(struct partition * p)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
msdos_magic_present(unsigned char * p)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
aix_magic_present(struct parsed_partitions * state,unsigned char * p)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, §);
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
parse_extended(struct parsed_partitions * state,sector_t first_sector,sector_t first_size)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, §);
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 }
193 done:
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
parse_solaris_x86(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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, §);
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 */
parse_bsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin,char * flavour,int max_partitions)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, §);
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
parse_freebsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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
parse_netbsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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
parse_openbsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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 */
parse_unixware(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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, §);
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 */
parse_minix(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)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, §);
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;
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
msdos_partition(struct parsed_partitions * state)432 int 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, §);
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