1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * fs/partitions/msdos.c
4 *
5 * Code extracted from drivers/block/genhd.c
6 * Copyright (C) 1991-1998 Linus Torvalds
7 *
8 * Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
9 * in the early extended-partition checks and added DM partitions
10 *
11 * Support for DiskManager v6.0x added by Mark Lord,
12 * with information provided by OnTrack. This now works for linux fdisk
13 * and LILO, as well as loadlin and bootln. Note that disks other than
14 * /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1).
15 *
16 * More flexible handling of extended partitions - aeb, 950831
17 *
18 * Check partition table on IDE disks for common CHS translations
19 *
20 * Re-organised Feb 1998 Russell King
21 */
22 #include <linux/msdos_fs.h>
23
24 #include "check.h"
25 #include "msdos.h"
26 #include "efi.h"
27 #include "aix.h"
28
29 /*
30 * Many architectures don't like unaligned accesses, while
31 * the nr_sects and start_sect partition table entries are
32 * at a 2 (mod 4) address.
33 */
34 #include <asm/unaligned.h>
35
36 #define SYS_IND(p) get_unaligned(&p->sys_ind)
37
nr_sects(struct partition * p)38 static inline sector_t nr_sects(struct partition *p)
39 {
40 return (sector_t)get_unaligned_le32(&p->nr_sects);
41 }
42
start_sect(struct partition * p)43 static inline sector_t start_sect(struct partition *p)
44 {
45 return (sector_t)get_unaligned_le32(&p->start_sect);
46 }
47
is_extended_partition(struct partition * p)48 static inline int is_extended_partition(struct partition *p)
49 {
50 return (SYS_IND(p) == DOS_EXTENDED_PARTITION ||
51 SYS_IND(p) == WIN98_EXTENDED_PARTITION ||
52 SYS_IND(p) == LINUX_EXTENDED_PARTITION);
53 }
54
55 #define MSDOS_LABEL_MAGIC1 0x55
56 #define MSDOS_LABEL_MAGIC2 0xAA
57
58 static inline int
msdos_magic_present(unsigned char * p)59 msdos_magic_present(unsigned char *p)
60 {
61 return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2);
62 }
63
64 /* Value is EBCDIC 'IBMA' */
65 #define AIX_LABEL_MAGIC1 0xC9
66 #define AIX_LABEL_MAGIC2 0xC2
67 #define AIX_LABEL_MAGIC3 0xD4
68 #define AIX_LABEL_MAGIC4 0xC1
aix_magic_present(struct parsed_partitions * state,unsigned char * p)69 static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
70 {
71 struct partition *pt = (struct partition *) (p + 0x1be);
72 Sector sect;
73 unsigned char *d;
74 int slot, ret = 0;
75
76 if (!(p[0] == AIX_LABEL_MAGIC1 &&
77 p[1] == AIX_LABEL_MAGIC2 &&
78 p[2] == AIX_LABEL_MAGIC3 &&
79 p[3] == AIX_LABEL_MAGIC4))
80 return 0;
81 /* Assume the partition table is valid if Linux partitions exists */
82 for (slot = 1; slot <= 4; slot++, pt++) {
83 if (pt->sys_ind == LINUX_SWAP_PARTITION ||
84 pt->sys_ind == LINUX_RAID_PARTITION ||
85 pt->sys_ind == LINUX_DATA_PARTITION ||
86 pt->sys_ind == LINUX_LVM_PARTITION ||
87 is_extended_partition(pt))
88 return 0;
89 }
90 d = read_part_sector(state, 7, §);
91 if (d) {
92 if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
93 ret = 1;
94 put_dev_sector(sect);
95 }
96 return ret;
97 }
98
set_info(struct parsed_partitions * state,int slot,u32 disksig)99 static void set_info(struct parsed_partitions *state, int slot,
100 u32 disksig)
101 {
102 struct partition_meta_info *info = &state->parts[slot].info;
103
104 snprintf(info->uuid, sizeof(info->uuid), "%08x-%02x", disksig,
105 slot);
106 info->volname[0] = 0;
107 state->parts[slot].has_info = true;
108 }
109
110 /*
111 * Create devices for each logical partition in an extended partition.
112 * The logical partitions form a linked list, with each entry being
113 * a partition table with two entries. The first entry
114 * is the real data partition (with a start relative to the partition
115 * table start). The second is a pointer to the next logical partition
116 * (with a start relative to the entire extended partition).
117 * We do not create a Linux partition for the partition tables, but
118 * only for the actual data partitions.
119 */
120
parse_extended(struct parsed_partitions * state,sector_t first_sector,sector_t first_size,u32 disksig)121 static void parse_extended(struct parsed_partitions *state,
122 sector_t first_sector, sector_t first_size,
123 u32 disksig)
124 {
125 struct partition *p;
126 Sector sect;
127 unsigned char *data;
128 sector_t this_sector, this_size;
129 sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
130 int loopct = 0; /* number of links followed
131 without finding a data partition */
132 int i;
133
134 this_sector = first_sector;
135 this_size = first_size;
136
137 while (1) {
138 if (++loopct > 100)
139 return;
140 if (state->next == state->limit)
141 return;
142 data = read_part_sector(state, this_sector, §);
143 if (!data)
144 return;
145
146 if (!msdos_magic_present(data + 510))
147 goto done;
148
149 p = (struct partition *) (data + 0x1be);
150
151 /*
152 * Usually, the first entry is the real data partition,
153 * the 2nd entry is the next extended partition, or empty,
154 * and the 3rd and 4th entries are unused.
155 * However, DRDOS sometimes has the extended partition as
156 * the first entry (when the data partition is empty),
157 * and OS/2 seems to use all four entries.
158 */
159
160 /*
161 * First process the data partition(s)
162 */
163 for (i = 0; i < 4; i++, p++) {
164 sector_t offs, size, next;
165
166 if (!nr_sects(p) || is_extended_partition(p))
167 continue;
168
169 /* Check the 3rd and 4th entries -
170 these sometimes contain random garbage */
171 offs = start_sect(p)*sector_size;
172 size = nr_sects(p)*sector_size;
173 next = this_sector + offs;
174 if (i >= 2) {
175 if (offs + size > this_size)
176 continue;
177 if (next < first_sector)
178 continue;
179 if (next + size > first_sector + first_size)
180 continue;
181 }
182
183 put_partition(state, state->next, next, size);
184 set_info(state, state->next, disksig);
185 if (SYS_IND(p) == LINUX_RAID_PARTITION)
186 state->parts[state->next].flags = ADDPART_FLAG_RAID;
187 loopct = 0;
188 if (++state->next == state->limit)
189 goto done;
190 }
191 /*
192 * Next, process the (first) extended partition, if present.
193 * (So far, there seems to be no reason to make
194 * parse_extended() recursive and allow a tree
195 * of extended partitions.)
196 * It should be a link to the next logical partition.
197 */
198 p -= 4;
199 for (i = 0; i < 4; i++, p++)
200 if (nr_sects(p) && is_extended_partition(p))
201 break;
202 if (i == 4)
203 goto done; /* nothing left to do */
204
205 this_sector = first_sector + start_sect(p) * sector_size;
206 this_size = nr_sects(p) * sector_size;
207 put_dev_sector(sect);
208 }
209 done:
210 put_dev_sector(sect);
211 }
212
213 /* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
214 indicates linux swap. Be careful before believing this is Solaris. */
215
parse_solaris_x86(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)216 static void parse_solaris_x86(struct parsed_partitions *state,
217 sector_t offset, sector_t size, int origin)
218 {
219 #ifdef CONFIG_SOLARIS_X86_PARTITION
220 Sector sect;
221 struct solaris_x86_vtoc *v;
222 int i;
223 short max_nparts;
224
225 v = read_part_sector(state, offset + 1, §);
226 if (!v)
227 return;
228 if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
229 put_dev_sector(sect);
230 return;
231 }
232 {
233 char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
234
235 snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
236 strlcat(state->pp_buf, tmp, PAGE_SIZE);
237 }
238 if (le32_to_cpu(v->v_version) != 1) {
239 char tmp[64];
240
241 snprintf(tmp, sizeof(tmp), " cannot handle version %d vtoc>\n",
242 le32_to_cpu(v->v_version));
243 strlcat(state->pp_buf, tmp, PAGE_SIZE);
244 put_dev_sector(sect);
245 return;
246 }
247 /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
248 max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
249 for (i = 0; i < max_nparts && state->next < state->limit; i++) {
250 struct solaris_x86_slice *s = &v->v_slice[i];
251 char tmp[3 + 10 + 1 + 1];
252
253 if (s->s_size == 0)
254 continue;
255 snprintf(tmp, sizeof(tmp), " [s%d]", i);
256 strlcat(state->pp_buf, tmp, PAGE_SIZE);
257 /* solaris partitions are relative to current MS-DOS
258 * one; must add the offset of the current partition */
259 put_partition(state, state->next++,
260 le32_to_cpu(s->s_start)+offset,
261 le32_to_cpu(s->s_size));
262 }
263 put_dev_sector(sect);
264 strlcat(state->pp_buf, " >\n", PAGE_SIZE);
265 #endif
266 }
267
268 #if defined(CONFIG_BSD_DISKLABEL)
269 /*
270 * Create devices for BSD partitions listed in a disklabel, under a
271 * dos-like partition. See parse_extended() for more information.
272 */
parse_bsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin,char * flavour,int max_partitions)273 static void parse_bsd(struct parsed_partitions *state,
274 sector_t offset, sector_t size, int origin, char *flavour,
275 int max_partitions)
276 {
277 Sector sect;
278 struct bsd_disklabel *l;
279 struct bsd_partition *p;
280 char tmp[64];
281
282 l = read_part_sector(state, offset + 1, §);
283 if (!l)
284 return;
285 if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
286 put_dev_sector(sect);
287 return;
288 }
289
290 snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
291 strlcat(state->pp_buf, tmp, PAGE_SIZE);
292
293 if (le16_to_cpu(l->d_npartitions) < max_partitions)
294 max_partitions = le16_to_cpu(l->d_npartitions);
295 for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
296 sector_t bsd_start, bsd_size;
297
298 if (state->next == state->limit)
299 break;
300 if (p->p_fstype == BSD_FS_UNUSED)
301 continue;
302 bsd_start = le32_to_cpu(p->p_offset);
303 bsd_size = le32_to_cpu(p->p_size);
304 /* FreeBSD has relative offset if C partition offset is zero */
305 if (memcmp(flavour, "bsd\0", 4) == 0 &&
306 le32_to_cpu(l->d_partitions[2].p_offset) == 0)
307 bsd_start += offset;
308 if (offset == bsd_start && size == bsd_size)
309 /* full parent partition, we have it already */
310 continue;
311 if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
312 strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
313 continue;
314 }
315 put_partition(state, state->next++, bsd_start, bsd_size);
316 }
317 put_dev_sector(sect);
318 if (le16_to_cpu(l->d_npartitions) > max_partitions) {
319 snprintf(tmp, sizeof(tmp), " (ignored %d more)",
320 le16_to_cpu(l->d_npartitions) - max_partitions);
321 strlcat(state->pp_buf, tmp, PAGE_SIZE);
322 }
323 strlcat(state->pp_buf, " >\n", PAGE_SIZE);
324 }
325 #endif
326
parse_freebsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)327 static void parse_freebsd(struct parsed_partitions *state,
328 sector_t offset, sector_t size, int origin)
329 {
330 #ifdef CONFIG_BSD_DISKLABEL
331 parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
332 #endif
333 }
334
parse_netbsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)335 static void parse_netbsd(struct parsed_partitions *state,
336 sector_t offset, sector_t size, int origin)
337 {
338 #ifdef CONFIG_BSD_DISKLABEL
339 parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
340 #endif
341 }
342
parse_openbsd(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)343 static void parse_openbsd(struct parsed_partitions *state,
344 sector_t offset, sector_t size, int origin)
345 {
346 #ifdef CONFIG_BSD_DISKLABEL
347 parse_bsd(state, offset, size, origin, "openbsd",
348 OPENBSD_MAXPARTITIONS);
349 #endif
350 }
351
352 /*
353 * Create devices for Unixware partitions listed in a disklabel, under a
354 * dos-like partition. See parse_extended() for more information.
355 */
parse_unixware(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)356 static void parse_unixware(struct parsed_partitions *state,
357 sector_t offset, sector_t size, int origin)
358 {
359 #ifdef CONFIG_UNIXWARE_DISKLABEL
360 Sector sect;
361 struct unixware_disklabel *l;
362 struct unixware_slice *p;
363
364 l = read_part_sector(state, offset + 29, §);
365 if (!l)
366 return;
367 if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
368 le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
369 put_dev_sector(sect);
370 return;
371 }
372 {
373 char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
374
375 snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
376 strlcat(state->pp_buf, tmp, PAGE_SIZE);
377 }
378 p = &l->vtoc.v_slice[1];
379 /* I omit the 0th slice as it is the same as whole disk. */
380 while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
381 if (state->next == state->limit)
382 break;
383
384 if (p->s_label != UNIXWARE_FS_UNUSED)
385 put_partition(state, state->next++,
386 le32_to_cpu(p->start_sect),
387 le32_to_cpu(p->nr_sects));
388 p++;
389 }
390 put_dev_sector(sect);
391 strlcat(state->pp_buf, " >\n", PAGE_SIZE);
392 #endif
393 }
394
395 /*
396 * Minix 2.0.0/2.0.2 subpartition support.
397 * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
398 * Rajeev V. Pillai <rajeevvp@yahoo.com>
399 */
parse_minix(struct parsed_partitions * state,sector_t offset,sector_t size,int origin)400 static void parse_minix(struct parsed_partitions *state,
401 sector_t offset, sector_t size, int origin)
402 {
403 #ifdef CONFIG_MINIX_SUBPARTITION
404 Sector sect;
405 unsigned char *data;
406 struct partition *p;
407 int i;
408
409 data = read_part_sector(state, offset, §);
410 if (!data)
411 return;
412
413 p = (struct partition *)(data + 0x1be);
414
415 /* The first sector of a Minix partition can have either
416 * a secondary MBR describing its subpartitions, or
417 * the normal boot sector. */
418 if (msdos_magic_present(data + 510) &&
419 SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
420 char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
421
422 snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
423 strlcat(state->pp_buf, tmp, PAGE_SIZE);
424 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
425 if (state->next == state->limit)
426 break;
427 /* add each partition in use */
428 if (SYS_IND(p) == MINIX_PARTITION)
429 put_partition(state, state->next++,
430 start_sect(p), nr_sects(p));
431 }
432 strlcat(state->pp_buf, " >\n", PAGE_SIZE);
433 }
434 put_dev_sector(sect);
435 #endif /* CONFIG_MINIX_SUBPARTITION */
436 }
437
438 static struct {
439 unsigned char id;
440 void (*parse)(struct parsed_partitions *, sector_t, sector_t, int);
441 } subtypes[] = {
442 {FREEBSD_PARTITION, parse_freebsd},
443 {NETBSD_PARTITION, parse_netbsd},
444 {OPENBSD_PARTITION, parse_openbsd},
445 {MINIX_PARTITION, parse_minix},
446 {UNIXWARE_PARTITION, parse_unixware},
447 {SOLARIS_X86_PARTITION, parse_solaris_x86},
448 {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
449 {0, NULL},
450 };
451
msdos_partition(struct parsed_partitions * state)452 int msdos_partition(struct parsed_partitions *state)
453 {
454 sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
455 Sector sect;
456 unsigned char *data;
457 struct partition *p;
458 struct fat_boot_sector *fb;
459 int slot;
460 u32 disksig;
461
462 data = read_part_sector(state, 0, §);
463 if (!data)
464 return -1;
465
466 /*
467 * Note order! (some AIX disks, e.g. unbootable kind,
468 * have no MSDOS 55aa)
469 */
470 if (aix_magic_present(state, data)) {
471 put_dev_sector(sect);
472 #ifdef CONFIG_AIX_PARTITION
473 return aix_partition(state);
474 #else
475 strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
476 return 0;
477 #endif
478 }
479
480 if (!msdos_magic_present(data + 510)) {
481 put_dev_sector(sect);
482 return 0;
483 }
484
485 /*
486 * Now that the 55aa signature is present, this is probably
487 * either the boot sector of a FAT filesystem or a DOS-type
488 * partition table. Reject this in case the boot indicator
489 * is not 0 or 0x80.
490 */
491 p = (struct partition *) (data + 0x1be);
492 for (slot = 1; slot <= 4; slot++, p++) {
493 if (p->boot_ind != 0 && p->boot_ind != 0x80) {
494 /*
495 * Even without a valid boot inidicator value
496 * its still possible this is valid FAT filesystem
497 * without a partition table.
498 */
499 fb = (struct fat_boot_sector *) data;
500 if (slot == 1 && fb->reserved && fb->fats
501 && fat_valid_media(fb->media)) {
502 strlcat(state->pp_buf, "\n", PAGE_SIZE);
503 put_dev_sector(sect);
504 return 1;
505 } else {
506 put_dev_sector(sect);
507 return 0;
508 }
509 }
510 }
511
512 #ifdef CONFIG_EFI_PARTITION
513 p = (struct partition *) (data + 0x1be);
514 for (slot = 1 ; slot <= 4 ; slot++, p++) {
515 /* If this is an EFI GPT disk, msdos should ignore it. */
516 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
517 put_dev_sector(sect);
518 return 0;
519 }
520 }
521 #endif
522 p = (struct partition *) (data + 0x1be);
523
524 disksig = le32_to_cpup((__le32 *)(data + 0x1b8));
525
526 /*
527 * Look for partitions in two passes:
528 * First find the primary and DOS-type extended partitions.
529 * On the second pass look inside *BSD, Unixware and Solaris partitions.
530 */
531
532 state->next = 5;
533 for (slot = 1 ; slot <= 4 ; slot++, p++) {
534 sector_t start = start_sect(p)*sector_size;
535 sector_t size = nr_sects(p)*sector_size;
536
537 if (!size)
538 continue;
539 if (is_extended_partition(p)) {
540 /*
541 * prevent someone doing mkfs or mkswap on an
542 * extended partition, but leave room for LILO
543 * FIXME: this uses one logical sector for > 512b
544 * sector, although it may not be enough/proper.
545 */
546 sector_t n = 2;
547
548 n = min(size, max(sector_size, n));
549 put_partition(state, slot, start, n);
550
551 strlcat(state->pp_buf, " <", PAGE_SIZE);
552 parse_extended(state, start, size, disksig);
553 strlcat(state->pp_buf, " >", PAGE_SIZE);
554 continue;
555 }
556 put_partition(state, slot, start, size);
557 set_info(state, slot, disksig);
558 if (SYS_IND(p) == LINUX_RAID_PARTITION)
559 state->parts[slot].flags = ADDPART_FLAG_RAID;
560 if (SYS_IND(p) == DM6_PARTITION)
561 strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
562 if (SYS_IND(p) == EZD_PARTITION)
563 strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
564 }
565
566 strlcat(state->pp_buf, "\n", PAGE_SIZE);
567
568 /* second pass - output for each on a separate line */
569 p = (struct partition *) (0x1be + data);
570 for (slot = 1 ; slot <= 4 ; slot++, p++) {
571 unsigned char id = SYS_IND(p);
572 int n;
573
574 if (!nr_sects(p))
575 continue;
576
577 for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
578 ;
579
580 if (!subtypes[n].parse)
581 continue;
582 subtypes[n].parse(state, start_sect(p) * sector_size,
583 nr_sects(p) * sector_size, slot);
584 }
585 put_dev_sector(sect);
586 return 1;
587 }
588