block/partitions/efi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /************************************************************
   3  * EFI GUID Partition Table handling
   4  *
   5  * http://www.uefi.org/specs/
   6  * http://www.intel.com/technology/efi/
   7  *
   8  * efi.[ch] by Matt Domsch <Matt_Domsch@dell.com>
   9  *   Copyright 2000,2001,2002,2004 Dell Inc.
  10  *
  11  * TODO:
  12  *
  13  * Changelog:
  14  * Mon August 5th, 2013 Davidlohr Bueso <davidlohr@hp.com>
  15  * - detect hybrid MBRs, tighter pMBR checking & cleanups.
  16  *
  17  * Mon Nov 09 2004 Matt Domsch <Matt_Domsch@dell.com>
  18  * - test for valid PMBR and valid PGPT before ever reading
  19  *   AGPT, allow override with 'gpt' kernel command line option.
  20  * - check for first/last_usable_lba outside of size of disk
  21  *
  22  * Tue  Mar 26 2002 Matt Domsch <Matt_Domsch@dell.com>
  23  * - Ported to 2.5.7-pre1 and 2.5.7-dj2
  24  * - Applied patch to avoid fault in alternate header handling
  25  * - cleaned up find_valid_gpt
  26  * - On-disk structure and copy in memory is *always* LE now -
  27  *   swab fields as needed
  28  * - remove print_gpt_header()
  29  * - only use first max_p partition entries, to keep the kernel minor number
  30  *   and partition numbers tied.
  31  *
  32  * Mon  Feb 04 2002 Matt Domsch <Matt_Domsch@dell.com>
  33  * - Removed __PRIPTR_PREFIX - not being used
  34  *
  35  * Mon  Jan 14 2002 Matt Domsch <Matt_Domsch@dell.com>
  36  * - Ported to 2.5.2-pre11 + library crc32 patch Linus applied
  37  *
  38  * Thu Dec 6 2001 Matt Domsch <Matt_Domsch@dell.com>
  39  * - Added compare_gpts().
  40  * - moved le_efi_guid_to_cpus() back into this file.  GPT is the only
  41  *   thing that keeps EFI GUIDs on disk.
  42  * - Changed gpt structure names and members to be simpler and more Linux-like.
  43  *
  44  * Wed Oct 17 2001 Matt Domsch <Matt_Domsch@dell.com>
  45  * - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck
  46  *
  47  * Wed Oct 10 2001 Matt Domsch <Matt_Domsch@dell.com>
  48  * - Changed function comments to DocBook style per Andreas Dilger suggestion.
  49  *
  50  * Mon Oct 08 2001 Matt Domsch <Matt_Domsch@dell.com>
  51  * - Change read_lba() to use the page cache per Al Viro's work.
  52  * - print u64s properly on all architectures
  53  * - fixed debug_printk(), now Dprintk()
  54  *
  55  * Mon Oct 01 2001 Matt Domsch <Matt_Domsch@dell.com>
  56  * - Style cleanups
  57  * - made most functions static
  58  * - Endianness addition
  59  * - remove test for second alternate header, as it's not per spec,
  60  *   and is unnecessary.  There's now a method to read/write the last
  61  *   sector of an odd-sized disk from user space.  No tools have ever
  62  *   been released which used this code, so it's effectively dead.
  63  * - Per Asit Mallick of Intel, added a test for a valid PMBR.
  64  * - Added kernel command line option 'gpt' to override valid PMBR test.
  65  *
  66  * Wed Jun  6 2001 Martin Wilck <Martin.Wilck@Fujitsu-Siemens.com>
  67  * - added devfs volume UUID support (/dev/volumes/uuids) for
  68  *   mounting file systems by the partition GUID.
  69  *
  70  * Tue Dec  5 2000 Matt Domsch <Matt_Domsch@dell.com>
  71  * - Moved crc32() to linux/lib, added efi_crc32().
  72  *
  73  * Thu Nov 30 2000 Matt Domsch <Matt_Domsch@dell.com>
  74  * - Replaced Intel's CRC32 function with an equivalent
  75  *   non-license-restricted version.
  76  *
  77  * Wed Oct 25 2000 Matt Domsch <Matt_Domsch@dell.com>
  78  * - Fixed the last_lba() call to return the proper last block
  79  *
  80  * Thu Oct 12 2000 Matt Domsch <Matt_Domsch@dell.com>
  81  * - Thanks to Andries Brouwer for his debugging assistance.
  82  * - Code works, detects all the partitions.
  83  *
  84  ************************************************************/
  85 #include <linux/kernel.h>
  86 #include <linux/crc32.h>
  87 #include <linux/ctype.h>
  88 #include <linux/math64.h>
  89 #include <linux/slab.h>
  90 #include "check.h"
  91 #include "efi.h"
  92
  93 /* This allows a kernel command line option 'gpt' to override
  94  * the test for invalid PMBR.  Not __initdata because reloading
  95  * the partition tables happens after init too.
  96  */
  97 static int force_gpt;
  98 static int __init
  99 force_gpt_fn(char *str)
 100 {
 101         force_gpt = 1;
 102         return 1;
 103 }
 104 __setup("gpt", force_gpt_fn);
 105
 106
 107 /**
 108  * efi_crc32() - EFI version of crc32 function
 109  * @buf: buffer to calculate crc32 of
 110  * @len: length of buf
 111  *
 112  * Description: Returns EFI-style CRC32 value for @buf
 113  *
 114  * This function uses the little endian Ethernet polynomial
 115  * but seeds the function with ~0, and xor's with ~0 at the end.
 116  * Note, the EFI Specification, v1.02, has a reference to
 117  * Dr. Dobbs Journal, May 1994 (actually it's in May 1992).
 118  */
 119 static inline u32
 120 efi_crc32(const void *buf, unsigned long len)
 121 {
 122         return (crc32(~0L, buf, len) ^ ~0L);
 123 }
 124
 125 /**
 126  * last_lba(): return number of last logical block of device
 127  * @bdev: block device
 128  *
 129  * Description: Returns last LBA value on success, 0 on error.
 130  * This is stored (by sd and ide-geometry) in
 131  *  the part[0] entry for this disk, and is the number of
 132  *  physical sectors available on the disk.
 133  */
 134 static u64 last_lba(struct block_device *bdev)
 135 {
 136         if (!bdev || !bdev->bd_inode)
 137                 return 0;
 138         return div_u64(bdev->bd_inode->i_size,
 139                        bdev_logical_block_size(bdev)) - 1ULL;
 140 }
 141
 142 static inline int pmbr_part_valid(gpt_mbr_record *part)
 143 {
 144         if (part->os_type != EFI_PMBR_OSTYPE_EFI_GPT)
 145                 goto invalid;
 146
 147         /* set to 0x00000001 (i.e., the LBA of the GPT Partition Header) */
 148         if (le32_to_cpu(part->starting_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA)
 149                 goto invalid;
 150
 151         return GPT_MBR_PROTECTIVE;
 152 invalid:
 153         return 0;
 154 }
 155
 156 /**
 157  * is_pmbr_valid(): test Protective MBR for validity
 158  * @mbr: pointer to a legacy mbr structure
 159  * @total_sectors: amount of sectors in the device
 160  *
 161  * Description: Checks for a valid protective or hybrid
 162  * master boot record (MBR). The validity of a pMBR depends
 163  * on all of the following properties:
 164  *  1) MSDOS signature is in the last two bytes of the MBR
 165  *  2) One partition of type 0xEE is found
 166  *
 167  * In addition, a hybrid MBR will have up to three additional
 168  * primary partitions, which point to the same space that's
 169  * marked out by up to three GPT partitions.
 170  *
 171  * Returns 0 upon invalid MBR, or GPT_MBR_PROTECTIVE or
 172  * GPT_MBR_HYBRID depending on the device layout.
 173  */
 174 static int is_pmbr_valid(legacy_mbr *mbr, sector_t total_sectors)
 175 {
 176         uint32_t sz = 0;
 177         int i, part = 0, ret = 0; /* invalid by default */
 178
 179         if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
 180                 goto done;
 181
 182         for (i = 0; i < 4; i++) {
 183                 ret = pmbr_part_valid(&mbr->partition_record[i]);
 184                 if (ret == GPT_MBR_PROTECTIVE) {
 185                         part = i;
 186                         /*
 187                          * Ok, we at least know that there's a protective MBR,
 188                          * now check if there are other partition types for
 189                          * hybrid MBR.
 190                          */
 191                         goto check_hybrid;
 192                 }
 193         }
 194
 195         if (ret != GPT_MBR_PROTECTIVE)
 196                 goto done;
 197 check_hybrid:
 198         for (i = 0; i < 4; i++)
 199                 if ((mbr->partition_record[i].os_type !=
 200                         EFI_PMBR_OSTYPE_EFI_GPT) &&
 201                     (mbr->partition_record[i].os_type != 0x00))
 202                         ret = GPT_MBR_HYBRID;
 203
 204         /*
 205          * Protective MBRs take up the lesser of the whole disk
 206          * or 2 TiB (32bit LBA), ignoring the rest of the disk.
 207          * Some partitioning programs, nonetheless, choose to set
 208          * the size to the maximum 32-bit limitation, disregarding
 209          * the disk size.
 210          *
 211          * Hybrid MBRs do not necessarily comply with this.
 212          *
 213          * Consider a bad value here to be a warning to support dd'ing
 214          * an image from a smaller disk to a larger disk.
 215          */
 216         if (ret == GPT_MBR_PROTECTIVE) {
 217                 sz = le32_to_cpu(mbr->partition_record[part].size_in_lba);
 218                 if (sz != (uint32_t) total_sectors - 1 && sz != 0xFFFFFFFF)
 219                         pr_debug("GPT: mbr size in lba (%u) different than whole disk (%u).\n",
 220                                  sz, min_t(uint32_t,
 221                                            total_sectors - 1, 0xFFFFFFFF));
 222         }
 223 done:
 224         return ret;
 225 }
 226
 227 /**
 228  * read_lba(): Read bytes from disk, starting at given LBA
 229  * @state: disk parsed partitions
 230  * @lba: the Logical Block Address of the partition table
 231  * @buffer: destination buffer
 232  * @count: bytes to read
 233  *
 234  * Description: Reads @count bytes from @state->bdev into @buffer.
 235  * Returns number of bytes read on success, 0 on error.
 236  */
 237 static size_t read_lba(struct parsed_partitions *state,
 238                        u64 lba, u8 *buffer, size_t count)
 239 {
 240         size_t totalreadcount = 0;
 241         struct block_device *bdev = state->bdev;
 242         sector_t n = lba * (bdev_logical_block_size(bdev) / 512);
 243
 244         if (!buffer || lba > last_lba(bdev))
 245                 return 0;
 246
 247         while (count) {
 248                 int copied = 512;
 249                 Sector sect;
 250                 unsigned char *data = read_part_sector(state, n++, &sect);
 251                 if (!data)
 252                         break;
 253                 if (copied > count)
 254                         copied = count;
 255                 memcpy(buffer, data, copied);
 256                 put_dev_sector(sect);
 257                 buffer += copied;
 258                 totalreadcount +=copied;
 259                 count -= copied;
 260         }
 261         return totalreadcount;
 262 }
 263
 264 /**
 265  * alloc_read_gpt_entries(): reads partition entries from disk
 266  * @state: disk parsed partitions
 267  * @gpt: GPT header
 268  *
 269  * Description: Returns ptes on success,  NULL on error.
 270  * Allocates space for PTEs based on information found in @gpt.
 271  * Notes: remember to free pte when you're done!
 272  */
 273 static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state,
 274                                          gpt_header *gpt)
 275 {
 276         size_t count;
 277         gpt_entry *pte;
 278
 279         if (!gpt)
 280                 return NULL;
 281
 282         count = (size_t)le32_to_cpu(gpt->num_partition_entries) *
 283                 le32_to_cpu(gpt->sizeof_partition_entry);
 284         if (!count)
 285                 return NULL;
 286         pte = kmalloc(count, GFP_KERNEL);
 287         if (!pte)
 288                 return NULL;
 289
 290         if (read_lba(state, le64_to_cpu(gpt->partition_entry_lba),
 291                         (u8 *) pte, count) < count) {
 292                 kfree(pte);
 293                 pte=NULL;
 294                 return NULL;
 295         }
 296         return pte;
 297 }
 298
 299 /**
 300  * alloc_read_gpt_header(): Allocates GPT header, reads into it from disk
 301  * @state: disk parsed partitions
 302  * @lba: the Logical Block Address of the partition table
 303  *
 304  * Description: returns GPT header on success, NULL on error.   Allocates
 305  * and fills a GPT header starting at @ from @state->bdev.
 306  * Note: remember to free gpt when finished with it.
 307  */
 308 static gpt_header *alloc_read_gpt_header(struct parsed_partitions *state,
 309                                          u64 lba)
 310 {
 311         gpt_header *gpt;
 312         unsigned ssz = bdev_logical_block_size(state->bdev);
 313
 314         gpt = kmalloc(ssz, GFP_KERNEL);
 315         if (!gpt)
 316                 return NULL;
 317
 318         if (read_lba(state, lba, (u8 *) gpt, ssz) < ssz) {
 319                 kfree(gpt);
 320                 gpt=NULL;
 321                 return NULL;
 322         }
 323
 324         return gpt;
 325 }
 326
 327 /**
 328  * is_gpt_valid() - tests one GPT header and PTEs for validity
 329  * @state: disk parsed partitions
 330  * @lba: logical block address of the GPT header to test
 331  * @gpt: GPT header ptr, filled on return.
 332  * @ptes: PTEs ptr, filled on return.
 333  *
 334  * Description: returns 1 if valid,  0 on error.
 335  * If valid, returns pointers to newly allocated GPT header and PTEs.
 336  */
 337 static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
 338                         gpt_header **gpt, gpt_entry **ptes)
 339 {
 340         u32 crc, origcrc;
 341         u64 lastlba, pt_size;
 342
 343         if (!ptes)
 344                 return 0;
 345         if (!(*gpt = alloc_read_gpt_header(state, lba)))
 346                 return 0;
 347
 348         /* Check the GUID Partition Table signature */
 349         if (le64_to_cpu((*gpt)->signature) != GPT_HEADER_SIGNATURE) {
 350                 pr_debug("GUID Partition Table Header signature is wrong:"
 351                          "%lld != %lld\n",
 352                          (unsigned long long)le64_to_cpu((*gpt)->signature),
 353                          (unsigned long long)GPT_HEADER_SIGNATURE);
 354                 goto fail;
 355         }
 356
 357         /* Check the GUID Partition Table header size is too big */
 358         if (le32_to_cpu((*gpt)->header_size) >
 359                         bdev_logical_block_size(state->bdev)) {
 360                 pr_debug("GUID Partition Table Header size is too large: %u > %u\n",
 361                         le32_to_cpu((*gpt)->header_size),
 362                         bdev_logical_block_size(state->bdev));
 363                 goto fail;
 364         }
 365
 366         /* Check the GUID Partition Table header size is too small */
 367         if (le32_to_cpu((*gpt)->header_size) < sizeof(gpt_header)) {
 368                 pr_debug("GUID Partition Table Header size is too small: %u < %zu\n",
 369                         le32_to_cpu((*gpt)->header_size),
 370                         sizeof(gpt_header));
 371                 goto fail;
 372         }
 373
 374         /* Check the GUID Partition Table CRC */
 375         origcrc = le32_to_cpu((*gpt)->header_crc32);
 376         (*gpt)->header_crc32 = 0;
 377         crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));
 378
 379         if (crc != origcrc) {
 380                 pr_debug("GUID Partition Table Header CRC is wrong: %x != %x\n",
 381                          crc, origcrc);
 382                 goto fail;
 383         }
 384         (*gpt)->header_crc32 = cpu_to_le32(origcrc);
 385
 386         /* Check that the my_lba entry points to the LBA that contains
 387          * the GUID Partition Table */
 388         if (le64_to_cpu((*gpt)->my_lba) != lba) {
 389                 pr_debug("GPT my_lba incorrect: %lld != %lld\n",
 390                          (unsigned long long)le64_to_cpu((*gpt)->my_lba),
 391                          (unsigned long long)lba);
 392                 goto fail;
 393         }
 394
 395         /* Check the first_usable_lba and last_usable_lba are
 396          * within the disk.
 397          */
 398         lastlba = last_lba(state->bdev);
 399         if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
 400                 pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
 401                          (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba),
 402                          (unsigned long long)lastlba);
 403                 goto fail;
 404         }
 405         if (le64_to_cpu((*gpt)->last_usable_lba) > lastlba) {
 406                 pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
 407                          (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
 408                          (unsigned long long)lastlba);
 409                 goto fail;
 410         }
 411         if (le64_to_cpu((*gpt)->last_usable_lba) < le64_to_cpu((*gpt)->first_usable_lba)) {
 412                 pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
 413                          (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
 414                          (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba));
 415                 goto fail;
 416         }
 417         /* Check that sizeof_partition_entry has the correct value */
 418         if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
 419                 pr_debug("GUID Partition Entry Size check failed.\n");
 420                 goto fail;
 421         }
 422
 423         /* Sanity check partition table size */
 424         pt_size = (u64)le32_to_cpu((*gpt)->num_partition_entries) *
 425                 le32_to_cpu((*gpt)->sizeof_partition_entry);
 426         if (pt_size > KMALLOC_MAX_SIZE) {
 427                 pr_debug("GUID Partition Table is too large: %llu > %lu bytes\n",
 428                          (unsigned long long)pt_size, KMALLOC_MAX_SIZE);
 429                 goto fail;
 430         }
 431
 432         if (!(*ptes = alloc_read_gpt_entries(state, *gpt)))
 433                 goto fail;
 434
 435         /* Check the GUID Partition Entry Array CRC */
 436         crc = efi_crc32((const unsigned char *) (*ptes), pt_size);
 437
 438         if (crc != le32_to_cpu((*gpt)->partition_entry_array_crc32)) {
 439                 pr_debug("GUID Partition Entry Array CRC check failed.\n");
 440                 goto fail_ptes;
 441         }
 442
 443         /* We're done, all's well */
 444         return 1;
 445
 446  fail_ptes:
 447         kfree(*ptes);
 448         *ptes = NULL;
 449  fail:
 450         kfree(*gpt);
 451         *gpt = NULL;
 452         return 0;
 453 }
 454
 455 /**
 456  * is_pte_valid() - tests one PTE for validity
 457  * @pte:pte to check
 458  * @lastlba: last lba of the disk
 459  *
 460  * Description: returns 1 if valid,  0 on error.
 461  */
 462 static inline int
 463 is_pte_valid(const gpt_entry *pte, const u64 lastlba)
 464 {
 465         if ((!efi_guidcmp(pte->partition_type_guid, NULL_GUID)) ||
 466             le64_to_cpu(pte->starting_lba) > lastlba         ||
 467             le64_to_cpu(pte->ending_lba)   > lastlba)
 468                 return 0;
 469         return 1;
 470 }
 471
 472 /**
 473  * compare_gpts() - Search disk for valid GPT headers and PTEs
 474  * @pgpt: primary GPT header
 475  * @agpt: alternate GPT header
 476  * @lastlba: last LBA number
 477  *
 478  * Description: Returns nothing.  Sanity checks pgpt and agpt fields
 479  * and prints warnings on discrepancies.
 480  *
 481  */
 482 static void
 483 compare_gpts(gpt_header *pgpt, gpt_header *agpt, u64 lastlba)
 484 {
 485         int error_found = 0;
 486         if (!pgpt || !agpt)
 487                 return;
 488         if (le64_to_cpu(pgpt->my_lba) != le64_to_cpu(agpt->alternate_lba)) {
 489                 pr_warn("GPT:Primary header LBA != Alt. header alternate_lba\n");
 490                 pr_warn("GPT:%lld != %lld\n",
 491                        (unsigned long long)le64_to_cpu(pgpt->my_lba),
 492                        (unsigned long long)le64_to_cpu(agpt->alternate_lba));
 493                 error_found++;
 494         }
 495         if (le64_to_cpu(pgpt->alternate_lba) != le64_to_cpu(agpt->my_lba)) {
 496                 pr_warn("GPT:Primary header alternate_lba != Alt. header my_lba\n");
 497                 pr_warn("GPT:%lld != %lld\n",
 498                        (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
 499                        (unsigned long long)le64_to_cpu(agpt->my_lba));
 500                 error_found++;
 501         }
 502         if (le64_to_cpu(pgpt->first_usable_lba) !=
 503             le64_to_cpu(agpt->first_usable_lba)) {
 504                 pr_warn("GPT:first_usable_lbas don't match.\n");
 505                 pr_warn("GPT:%lld != %lld\n",
 506                        (unsigned long long)le64_to_cpu(pgpt->first_usable_lba),
 507                        (unsigned long long)le64_to_cpu(agpt->first_usable_lba));
 508                 error_found++;
 509         }
 510         if (le64_to_cpu(pgpt->last_usable_lba) !=
 511             le64_to_cpu(agpt->last_usable_lba)) {
 512                 pr_warn("GPT:last_usable_lbas don't match.\n");
 513                 pr_warn("GPT:%lld != %lld\n",
 514                        (unsigned long long)le64_to_cpu(pgpt->last_usable_lba),
 515                        (unsigned long long)le64_to_cpu(agpt->last_usable_lba));
 516                 error_found++;
 517         }
 518         if (efi_guidcmp(pgpt->disk_guid, agpt->disk_guid)) {
 519                 pr_warn("GPT:disk_guids don't match.\n");
 520                 error_found++;
 521         }
 522         if (le32_to_cpu(pgpt->num_partition_entries) !=
 523             le32_to_cpu(agpt->num_partition_entries)) {
 524                 pr_warn("GPT:num_partition_entries don't match: "
 525                        "0x%x != 0x%x\n",
 526                        le32_to_cpu(pgpt->num_partition_entries),
 527                        le32_to_cpu(agpt->num_partition_entries));
 528                 error_found++;
 529         }
 530         if (le32_to_cpu(pgpt->sizeof_partition_entry) !=
 531             le32_to_cpu(agpt->sizeof_partition_entry)) {
 532                 pr_warn("GPT:sizeof_partition_entry values don't match: "
 533                        "0x%x != 0x%x\n",
 534                        le32_to_cpu(pgpt->sizeof_partition_entry),
 535                        le32_to_cpu(agpt->sizeof_partition_entry));
 536                 error_found++;
 537         }
 538         if (le32_to_cpu(pgpt->partition_entry_array_crc32) !=
 539             le32_to_cpu(agpt->partition_entry_array_crc32)) {
 540                 pr_warn("GPT:partition_entry_array_crc32 values don't match: "
 541                        "0x%x != 0x%x\n",
 542                        le32_to_cpu(pgpt->partition_entry_array_crc32),
 543                        le32_to_cpu(agpt->partition_entry_array_crc32));
 544                 error_found++;
 545         }
 546         if (le64_to_cpu(pgpt->alternate_lba) != lastlba) {
 547                 pr_warn("GPT:Primary header thinks Alt. header is not at the end of the disk.\n");
 548                 pr_warn("GPT:%lld != %lld\n",
 549                         (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
 550                         (unsigned long long)lastlba);
 551                 error_found++;
 552         }
 553
 554         if (le64_to_cpu(agpt->my_lba) != lastlba) {
 555                 pr_warn("GPT:Alternate GPT header not at the end of the disk.\n");
 556                 pr_warn("GPT:%lld != %lld\n",
 557                         (unsigned long long)le64_to_cpu(agpt->my_lba),
 558                         (unsigned long long)lastlba);
 559                 error_found++;
 560         }
 561
 562         if (error_found)
 563                 pr_warn("GPT: Use GNU Parted to correct GPT errors.\n");
 564         return;
 565 }
 566
 567 /**
 568  * find_valid_gpt() - Search disk for valid GPT headers and PTEs
 569  * @state: disk parsed partitions
 570  * @gpt: GPT header ptr, filled on return.
 571  * @ptes: PTEs ptr, filled on return.
 572  *
 573  * Description: Returns 1 if valid, 0 on error.
 574  * If valid, returns pointers to newly allocated GPT header and PTEs.
 575  * Validity depends on PMBR being valid (or being overridden by the
 576  * 'gpt' kernel command line option) and finding either the Primary
 577  * GPT header and PTEs valid, or the Alternate GPT header and PTEs
 578  * valid.  If the Primary GPT header is not valid, the Alternate GPT header
 579  * is not checked unless the 'gpt' kernel command line option is passed.
 580  * This protects against devices which misreport their size, and forces
 581  * the user to decide to use the Alternate GPT.
 582  */
 583 static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
 584                           gpt_entry **ptes)
 585 {
 586         int good_pgpt = 0, good_agpt = 0, good_pmbr = 0;
 587         gpt_header *pgpt = NULL, *agpt = NULL;
 588         gpt_entry *pptes = NULL, *aptes = NULL;
 589         legacy_mbr *legacymbr;
 590         sector_t total_sectors = i_size_read(state->bdev->bd_inode) >> 9;
 591         u64 lastlba;
 592
 593         if (!ptes)
 594                 return 0;
 595
 596         lastlba = last_lba(state->bdev);
 597         if (!force_gpt) {
 598                 /* This will be added to the EFI Spec. per Intel after v1.02. */
 599                 legacymbr = kzalloc(sizeof(*legacymbr), GFP_KERNEL);
 600                 if (!legacymbr)
 601                         goto fail;
 602
 603                 read_lba(state, 0, (u8 *)legacymbr, sizeof(*legacymbr));
 604                 good_pmbr = is_pmbr_valid(legacymbr, total_sectors);
 605                 kfree(legacymbr);
 606
 607                 if (!good_pmbr)
 608                         goto fail;
 609
 610                 pr_debug("Device has a %s MBR\n",
 611                          good_pmbr == GPT_MBR_PROTECTIVE ?
 612                                                 "protective" : "hybrid");
 613         }
 614
 615         good_pgpt = is_gpt_valid(state, GPT_PRIMARY_PARTITION_TABLE_LBA,
 616                                  &pgpt, &pptes);
 617         if (good_pgpt)
 618                 good_agpt = is_gpt_valid(state,
 619                                          le64_to_cpu(pgpt->alternate_lba),
 620                                          &agpt, &aptes);
 621         if (!good_agpt && force_gpt)
 622                 good_agpt = is_gpt_valid(state, lastlba, &agpt, &aptes);
 623
 624         /* The obviously unsuccessful case */
 625         if (!good_pgpt && !good_agpt)
 626                 goto fail;
 627
 628         compare_gpts(pgpt, agpt, lastlba);
 629
 630         /* The good cases */
 631         if (good_pgpt) {
 632                 *gpt  = pgpt;
 633                 *ptes = pptes;
 634                 kfree(agpt);
 635                 kfree(aptes);
 636                 if (!good_agpt)
 637                         pr_warn("Alternate GPT is invalid, using primary GPT.\n");
 638                 return 1;
 639         }
 640         else if (good_agpt) {
 641                 *gpt  = agpt;
 642                 *ptes = aptes;
 643                 kfree(pgpt);
 644                 kfree(pptes);
 645                 pr_warn("Primary GPT is invalid, using alternate GPT.\n");
 646                 return 1;
 647         }
 648
 649  fail:
 650         kfree(pgpt);
 651         kfree(agpt);
 652         kfree(pptes);
 653         kfree(aptes);
 654         *gpt = NULL;
 655         *ptes = NULL;
 656         return 0;
 657 }
 658
 659 /**
 660  * efi_partition(struct parsed_partitions *state)
 661  * @state: disk parsed partitions
 662  *
 663  * Description: called from check.c, if the disk contains GPT
 664  * partitions, sets up partition entries in the kernel.
 665  *
 666  * If the first block on the disk is a legacy MBR,
 667  * it will get handled by msdos_partition().
 668  * If it's a Protective MBR, we'll handle it here.
 669  *
 670  * We do not create a Linux partition for GPT, but
 671  * only for the actual data partitions.
 672  * Returns:
 673  * -1 if unable to read the partition table
 674  *  0 if this isn't our partition table
 675  *  1 if successful
 676  *
 677  */
 678 int efi_partition(struct parsed_partitions *state)
 679 {
 680         gpt_header *gpt = NULL;
 681         gpt_entry *ptes = NULL;
 682         u32 i;
 683         unsigned ssz = bdev_logical_block_size(state->bdev) / 512;
 684
 685         if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
 686                 kfree(gpt);
 687                 kfree(ptes);
 688                 return 0;
 689         }
 690
 691         pr_debug("GUID Partition Table is valid!  Yea!\n");
 692
 693         for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
 694                 struct partition_meta_info *info;
 695                 unsigned label_count = 0;
 696                 unsigned label_max;
 697                 u64 start = le64_to_cpu(ptes[i].starting_lba);
 698                 u64 size = le64_to_cpu(ptes[i].ending_lba) -
 699                            le64_to_cpu(ptes[i].starting_lba) + 1ULL;
 700
 701                 if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
 702                         continue;
 703
 704                 put_partition(state, i+1, start * ssz, size * ssz);
 705
 706                 /* If this is a RAID volume, tell md */
 707                 if (!efi_guidcmp(ptes[i].partition_type_guid, PARTITION_LINUX_RAID_GUID))
 708                         state->parts[i + 1].flags = ADDPART_FLAG_RAID;
 709
 710                 info = &state->parts[i + 1].info;
 711                 efi_guid_to_str(&ptes[i].unique_partition_guid, info->uuid);
 712
 713                 /* Naively convert UTF16-LE to 7 bits. */
 714                 label_max = min(ARRAY_SIZE(info->volname) - 1,
 715                                 ARRAY_SIZE(ptes[i].partition_name));
 716                 info->volname[label_max] = 0;
 717                 while (label_count < label_max) {
 718                         u8 c = ptes[i].partition_name[label_count] & 0xff;
 719                         if (c && !isprint(c))
 720                                 c = '!';
 721                         info->volname[label_count] = c;
 722                         label_count++;
 723                 }
 724                 state->parts[i + 1].has_info = true;
 725         }
 726         kfree(ptes);
 727         kfree(gpt);
 728         strlcat(state->pp_buf, "\n", PAGE_SIZE);
 729         return 1;
 730 }