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efi.c
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1 /************************************************************
2  * EFI GUID Partition Table handling
3  *
4  * http://www.uefi.org/specs/
5  * http://www.intel.com/technology/efi/
6  *
7  * efi.[ch] by Matt Domsch <[email protected]>
8  * Copyright 2000,2001,2002,2004 Dell Inc.
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23  *
24  *
25  * TODO:
26  *
27  * Changelog:
28  * Mon Nov 09 2004 Matt Domsch <[email protected]>
29  * - test for valid PMBR and valid PGPT before ever reading
30  * AGPT, allow override with 'gpt' kernel command line option.
31  * - check for first/last_usable_lba outside of size of disk
32  *
33  * Tue Mar 26 2002 Matt Domsch <[email protected]>
34  * - Ported to 2.5.7-pre1 and 2.5.7-dj2
35  * - Applied patch to avoid fault in alternate header handling
36  * - cleaned up find_valid_gpt
37  * - On-disk structure and copy in memory is *always* LE now -
38  * swab fields as needed
39  * - remove print_gpt_header()
40  * - only use first max_p partition entries, to keep the kernel minor number
41  * and partition numbers tied.
42  *
43  * Mon Feb 04 2002 Matt Domsch <[email protected]>
44  * - Removed __PRIPTR_PREFIX - not being used
45  *
46  * Mon Jan 14 2002 Matt Domsch <[email protected]>
47  * - Ported to 2.5.2-pre11 + library crc32 patch Linus applied
48  *
49  * Thu Dec 6 2001 Matt Domsch <[email protected]>
50  * - Added compare_gpts().
51  * - moved le_efi_guid_to_cpus() back into this file. GPT is the only
52  * thing that keeps EFI GUIDs on disk.
53  * - Changed gpt structure names and members to be simpler and more Linux-like.
54  *
55  * Wed Oct 17 2001 Matt Domsch <[email protected]>
56  * - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck
57  *
58  * Wed Oct 10 2001 Matt Domsch <[email protected]>
59  * - Changed function comments to DocBook style per Andreas Dilger suggestion.
60  *
61  * Mon Oct 08 2001 Matt Domsch <[email protected]>
62  * - Change read_lba() to use the page cache per Al Viro's work.
63  * - print u64s properly on all architectures
64  * - fixed debug_printk(), now Dprintk()
65  *
66  * Mon Oct 01 2001 Matt Domsch <[email protected]>
67  * - Style cleanups
68  * - made most functions static
69  * - Endianness addition
70  * - remove test for second alternate header, as it's not per spec,
71  * and is unnecessary. There's now a method to read/write the last
72  * sector of an odd-sized disk from user space. No tools have ever
73  * been released which used this code, so it's effectively dead.
74  * - Per Asit Mallick of Intel, added a test for a valid PMBR.
75  * - Added kernel command line option 'gpt' to override valid PMBR test.
76  *
77  * Wed Jun 6 2001 Martin Wilck <[email protected]>
78  * - added devfs volume UUID support (/dev/volumes/uuids) for
79  * mounting file systems by the partition GUID.
80  *
81  * Tue Dec 5 2000 Matt Domsch <[email protected]>
82  * - Moved crc32() to linux/lib, added efi_crc32().
83  *
84  * Thu Nov 30 2000 Matt Domsch <[email protected]>
85  * - Replaced Intel's CRC32 function with an equivalent
86  * non-license-restricted version.
87  *
88  * Wed Oct 25 2000 Matt Domsch <[email protected]>
89  * - Fixed the last_lba() call to return the proper last block
90  *
91  * Thu Oct 12 2000 Matt Domsch <[email protected]>
92  * - Thanks to Andries Brouwer for his debugging assistance.
93  * - Code works, detects all the partitions.
94  *
95  ************************************************************/
96 #include <linux/crc32.h>
97 #include <linux/ctype.h>
98 #include <linux/math64.h>
99 #include <linux/slab.h>
100 #include "check.h"
101 #include "efi.h"
102 
103 /* This allows a kernel command line option 'gpt' to override
104  * the test for invalid PMBR. Not __initdata because reloading
105  * the partition tables happens after init too.
106  */
107 static int force_gpt;
108 static int __init
109 force_gpt_fn(char *str)
110 {
111  force_gpt = 1;
112  return 1;
113 }
114 __setup("gpt", force_gpt_fn);
115 
116 
129 static inline u32
130 efi_crc32(const void *buf, unsigned long len)
131 {
132  return (crc32(~0L, buf, len) ^ ~0L);
133 }
134 
144 static u64 last_lba(struct block_device *bdev)
145 {
146  if (!bdev || !bdev->bd_inode)
147  return 0;
148  return div_u64(bdev->bd_inode->i_size,
149  bdev_logical_block_size(bdev)) - 1ULL;
150 }
151 
152 static inline int
153 pmbr_part_valid(struct partition *part)
154 {
155  if (part->sys_ind == EFI_PMBR_OSTYPE_EFI_GPT &&
156  le32_to_cpu(part->start_sect) == 1UL)
157  return 1;
158  return 0;
159 }
160 
170 static int
171 is_pmbr_valid(legacy_mbr *mbr)
172 {
173  int i;
174  if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
175  return 0;
176  for (i = 0; i < 4; i++)
177  if (pmbr_part_valid(&mbr->partition_record[i]))
178  return 1;
179  return 0;
180 }
181 
192 static size_t read_lba(struct parsed_partitions *state,
193  u64 lba, u8 *buffer, size_t count)
194 {
195  size_t totalreadcount = 0;
196  struct block_device *bdev = state->bdev;
197  sector_t n = lba * (bdev_logical_block_size(bdev) / 512);
198 
199  if (!buffer || lba > last_lba(bdev))
200  return 0;
201 
202  while (count) {
203  int copied = 512;
204  Sector sect;
205  unsigned char *data = read_part_sector(state, n++, &sect);
206  if (!data)
207  break;
208  if (copied > count)
209  copied = count;
210  memcpy(buffer, data, copied);
211  put_dev_sector(sect);
212  buffer += copied;
213  totalreadcount +=copied;
214  count -= copied;
215  }
216  return totalreadcount;
217 }
218 
228 static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state,
229  gpt_header *gpt)
230 {
231  size_t count;
232  gpt_entry *pte;
233 
234  if (!gpt)
235  return NULL;
236 
237  count = le32_to_cpu(gpt->num_partition_entries) *
238  le32_to_cpu(gpt->sizeof_partition_entry);
239  if (!count)
240  return NULL;
241  pte = kzalloc(count, GFP_KERNEL);
242  if (!pte)
243  return NULL;
244 
245  if (read_lba(state, le64_to_cpu(gpt->partition_entry_lba),
246  (u8 *) pte,
247  count) < count) {
248  kfree(pte);
249  pte=NULL;
250  return NULL;
251  }
252  return pte;
253 }
254 
264 static gpt_header *alloc_read_gpt_header(struct parsed_partitions *state,
265  u64 lba)
266 {
267  gpt_header *gpt;
268  unsigned ssz = bdev_logical_block_size(state->bdev);
269 
270  gpt = kzalloc(ssz, GFP_KERNEL);
271  if (!gpt)
272  return NULL;
273 
274  if (read_lba(state, lba, (u8 *) gpt, ssz) < ssz) {
275  kfree(gpt);
276  gpt=NULL;
277  return NULL;
278  }
279 
280  return gpt;
281 }
282 
293 static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
294  gpt_header **gpt, gpt_entry **ptes)
295 {
296  u32 crc, origcrc;
297  u64 lastlba;
298 
299  if (!ptes)
300  return 0;
301  if (!(*gpt = alloc_read_gpt_header(state, lba)))
302  return 0;
303 
304  /* Check the GUID Partition Table signature */
305  if (le64_to_cpu((*gpt)->signature) != GPT_HEADER_SIGNATURE) {
306  pr_debug("GUID Partition Table Header signature is wrong:"
307  "%lld != %lld\n",
308  (unsigned long long)le64_to_cpu((*gpt)->signature),
309  (unsigned long long)GPT_HEADER_SIGNATURE);
310  goto fail;
311  }
312 
313  /* Check the GUID Partition Table header size */
314  if (le32_to_cpu((*gpt)->header_size) >
315  bdev_logical_block_size(state->bdev)) {
316  pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
317  le32_to_cpu((*gpt)->header_size),
318  bdev_logical_block_size(state->bdev));
319  goto fail;
320  }
321 
322  /* Check the GUID Partition Table CRC */
323  origcrc = le32_to_cpu((*gpt)->header_crc32);
324  (*gpt)->header_crc32 = 0;
325  crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));
326 
327  if (crc != origcrc) {
328  pr_debug("GUID Partition Table Header CRC is wrong: %x != %x\n",
329  crc, origcrc);
330  goto fail;
331  }
332  (*gpt)->header_crc32 = cpu_to_le32(origcrc);
333 
334  /* Check that the my_lba entry points to the LBA that contains
335  * the GUID Partition Table */
336  if (le64_to_cpu((*gpt)->my_lba) != lba) {
337  pr_debug("GPT my_lba incorrect: %lld != %lld\n",
338  (unsigned long long)le64_to_cpu((*gpt)->my_lba),
339  (unsigned long long)lba);
340  goto fail;
341  }
342 
343  /* Check the first_usable_lba and last_usable_lba are
344  * within the disk.
345  */
346  lastlba = last_lba(state->bdev);
347  if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
348  pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
349  (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba),
350  (unsigned long long)lastlba);
351  goto fail;
352  }
353  if (le64_to_cpu((*gpt)->last_usable_lba) > lastlba) {
354  pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
355  (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
356  (unsigned long long)lastlba);
357  goto fail;
358  }
359 
360  /* Check that sizeof_partition_entry has the correct value */
361  if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
362  pr_debug("GUID Partitition Entry Size check failed.\n");
363  goto fail;
364  }
365 
366  if (!(*ptes = alloc_read_gpt_entries(state, *gpt)))
367  goto fail;
368 
369  /* Check the GUID Partition Entry Array CRC */
370  crc = efi_crc32((const unsigned char *) (*ptes),
371  le32_to_cpu((*gpt)->num_partition_entries) *
372  le32_to_cpu((*gpt)->sizeof_partition_entry));
373 
374  if (crc != le32_to_cpu((*gpt)->partition_entry_array_crc32)) {
375  pr_debug("GUID Partitition Entry Array CRC check failed.\n");
376  goto fail_ptes;
377  }
378 
379  /* We're done, all's well */
380  return 1;
381 
382  fail_ptes:
383  kfree(*ptes);
384  *ptes = NULL;
385  fail:
386  kfree(*gpt);
387  *gpt = NULL;
388  return 0;
389 }
390 
398 static inline int
399 is_pte_valid(const gpt_entry *pte, const u64 lastlba)
400 {
401  if ((!efi_guidcmp(pte->partition_type_guid, NULL_GUID)) ||
402  le64_to_cpu(pte->starting_lba) > lastlba ||
403  le64_to_cpu(pte->ending_lba) > lastlba)
404  return 0;
405  return 1;
406 }
407 
417 static void
418 compare_gpts(gpt_header *pgpt, gpt_header *agpt, u64 lastlba)
419 {
420  int error_found = 0;
421  if (!pgpt || !agpt)
422  return;
423  if (le64_to_cpu(pgpt->my_lba) != le64_to_cpu(agpt->alternate_lba)) {
425  "GPT:Primary header LBA != Alt. header alternate_lba\n");
426  printk(KERN_WARNING "GPT:%lld != %lld\n",
427  (unsigned long long)le64_to_cpu(pgpt->my_lba),
428  (unsigned long long)le64_to_cpu(agpt->alternate_lba));
429  error_found++;
430  }
431  if (le64_to_cpu(pgpt->alternate_lba) != le64_to_cpu(agpt->my_lba)) {
433  "GPT:Primary header alternate_lba != Alt. header my_lba\n");
434  printk(KERN_WARNING "GPT:%lld != %lld\n",
435  (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
436  (unsigned long long)le64_to_cpu(agpt->my_lba));
437  error_found++;
438  }
439  if (le64_to_cpu(pgpt->first_usable_lba) !=
440  le64_to_cpu(agpt->first_usable_lba)) {
441  printk(KERN_WARNING "GPT:first_usable_lbas don't match.\n");
442  printk(KERN_WARNING "GPT:%lld != %lld\n",
443  (unsigned long long)le64_to_cpu(pgpt->first_usable_lba),
444  (unsigned long long)le64_to_cpu(agpt->first_usable_lba));
445  error_found++;
446  }
447  if (le64_to_cpu(pgpt->last_usable_lba) !=
448  le64_to_cpu(agpt->last_usable_lba)) {
449  printk(KERN_WARNING "GPT:last_usable_lbas don't match.\n");
450  printk(KERN_WARNING "GPT:%lld != %lld\n",
451  (unsigned long long)le64_to_cpu(pgpt->last_usable_lba),
452  (unsigned long long)le64_to_cpu(agpt->last_usable_lba));
453  error_found++;
454  }
455  if (efi_guidcmp(pgpt->disk_guid, agpt->disk_guid)) {
456  printk(KERN_WARNING "GPT:disk_guids don't match.\n");
457  error_found++;
458  }
459  if (le32_to_cpu(pgpt->num_partition_entries) !=
460  le32_to_cpu(agpt->num_partition_entries)) {
461  printk(KERN_WARNING "GPT:num_partition_entries don't match: "
462  "0x%x != 0x%x\n",
463  le32_to_cpu(pgpt->num_partition_entries),
464  le32_to_cpu(agpt->num_partition_entries));
465  error_found++;
466  }
467  if (le32_to_cpu(pgpt->sizeof_partition_entry) !=
468  le32_to_cpu(agpt->sizeof_partition_entry)) {
470  "GPT:sizeof_partition_entry values don't match: "
471  "0x%x != 0x%x\n",
472  le32_to_cpu(pgpt->sizeof_partition_entry),
473  le32_to_cpu(agpt->sizeof_partition_entry));
474  error_found++;
475  }
476  if (le32_to_cpu(pgpt->partition_entry_array_crc32) !=
477  le32_to_cpu(agpt->partition_entry_array_crc32)) {
479  "GPT:partition_entry_array_crc32 values don't match: "
480  "0x%x != 0x%x\n",
481  le32_to_cpu(pgpt->partition_entry_array_crc32),
482  le32_to_cpu(agpt->partition_entry_array_crc32));
483  error_found++;
484  }
485  if (le64_to_cpu(pgpt->alternate_lba) != lastlba) {
487  "GPT:Primary header thinks Alt. header is not at the end of the disk.\n");
488  printk(KERN_WARNING "GPT:%lld != %lld\n",
489  (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
490  (unsigned long long)lastlba);
491  error_found++;
492  }
493 
494  if (le64_to_cpu(agpt->my_lba) != lastlba) {
496  "GPT:Alternate GPT header not at the end of the disk.\n");
497  printk(KERN_WARNING "GPT:%lld != %lld\n",
498  (unsigned long long)le64_to_cpu(agpt->my_lba),
499  (unsigned long long)lastlba);
500  error_found++;
501  }
502 
503  if (error_found)
505  "GPT: Use GNU Parted to correct GPT errors.\n");
506  return;
507 }
508 
524 static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
525  gpt_entry **ptes)
526 {
527  int good_pgpt = 0, good_agpt = 0, good_pmbr = 0;
528  gpt_header *pgpt = NULL, *agpt = NULL;
529  gpt_entry *pptes = NULL, *aptes = NULL;
530  legacy_mbr *legacymbr;
531  u64 lastlba;
532 
533  if (!ptes)
534  return 0;
535 
536  lastlba = last_lba(state->bdev);
537  if (!force_gpt) {
538  /* This will be added to the EFI Spec. per Intel after v1.02. */
539  legacymbr = kzalloc(sizeof (*legacymbr), GFP_KERNEL);
540  if (legacymbr) {
541  read_lba(state, 0, (u8 *) legacymbr,
542  sizeof (*legacymbr));
543  good_pmbr = is_pmbr_valid(legacymbr);
544  kfree(legacymbr);
545  }
546  if (!good_pmbr)
547  goto fail;
548  }
549 
550  good_pgpt = is_gpt_valid(state, GPT_PRIMARY_PARTITION_TABLE_LBA,
551  &pgpt, &pptes);
552  if (good_pgpt)
553  good_agpt = is_gpt_valid(state,
554  le64_to_cpu(pgpt->alternate_lba),
555  &agpt, &aptes);
556  if (!good_agpt && force_gpt)
557  good_agpt = is_gpt_valid(state, lastlba, &agpt, &aptes);
558 
559  /* The obviously unsuccessful case */
560  if (!good_pgpt && !good_agpt)
561  goto fail;
562 
563  compare_gpts(pgpt, agpt, lastlba);
564 
565  /* The good cases */
566  if (good_pgpt) {
567  *gpt = pgpt;
568  *ptes = pptes;
569  kfree(agpt);
570  kfree(aptes);
571  if (!good_agpt) {
573  "Alternate GPT is invalid, "
574  "using primary GPT.\n");
575  }
576  return 1;
577  }
578  else if (good_agpt) {
579  *gpt = agpt;
580  *ptes = aptes;
581  kfree(pgpt);
582  kfree(pptes);
584  "Primary GPT is invalid, using alternate GPT.\n");
585  return 1;
586  }
587 
588  fail:
589  kfree(pgpt);
590  kfree(agpt);
591  kfree(pptes);
592  kfree(aptes);
593  *gpt = NULL;
594  *ptes = NULL;
595  return 0;
596 }
597 
618 {
619  gpt_header *gpt = NULL;
620  gpt_entry *ptes = NULL;
621  u32 i;
622  unsigned ssz = bdev_logical_block_size(state->bdev) / 512;
623  u8 unparsed_guid[37];
624 
625  if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
626  kfree(gpt);
627  kfree(ptes);
628  return 0;
629  }
630 
631  pr_debug("GUID Partition Table is valid! Yea!\n");
632 
633  for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
634  struct partition_meta_info *info;
635  unsigned label_count = 0;
636  unsigned label_max;
637  u64 start = le64_to_cpu(ptes[i].starting_lba);
638  u64 size = le64_to_cpu(ptes[i].ending_lba) -
639  le64_to_cpu(ptes[i].starting_lba) + 1ULL;
640 
641  if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
642  continue;
643 
644  put_partition(state, i+1, start * ssz, size * ssz);
645 
646  /* If this is a RAID volume, tell md */
647  if (!efi_guidcmp(ptes[i].partition_type_guid,
649  state->parts[i + 1].flags = ADDPART_FLAG_RAID;
650 
651  info = &state->parts[i + 1].info;
652  /* Instead of doing a manual swap to big endian, reuse the
653  * common ASCII hex format as the interim.
654  */
655  efi_guid_unparse(&ptes[i].unique_partition_guid, unparsed_guid);
656  part_pack_uuid(unparsed_guid, info->uuid);
657 
658  /* Naively convert UTF16-LE to 7 bits. */
659  label_max = min(sizeof(info->volname) - 1,
660  sizeof(ptes[i].partition_name));
661  info->volname[label_max] = 0;
662  while (label_count < label_max) {
663  u8 c = ptes[i].partition_name[label_count] & 0xff;
664  if (c && !isprint(c))
665  c = '!';
666  info->volname[label_count] = c;
667  label_count++;
668  }
669  state->parts[i + 1].has_info = true;
670  }
671  kfree(ptes);
672  kfree(gpt);
673  strlcat(state->pp_buf, "\n", PAGE_SIZE);
674  return 1;
675 }