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   1 /*
   2  * integrity.c
   3  *
   4  * WIM files can optionally contain a table of SHA1 message digests at the end,
   5  * one digest for each chunk of the file of some specified size (often 10 MB).
   6  * This file implements the checking and writing of this table.
   7  */
   8
   9 /*
  10  * Copyright (C) 2012, 2013 Eric Biggers
  11  *
  12  * This file is part of wimlib, a library for working with WIM files.
  13  *
  14  * wimlib is free software; you can redistribute it and/or modify it under the
  15  * terms of the GNU General Public License as published by the Free
  16  * Software Foundation; either version 3 of the License, or (at your option)
  17  * any later version.
  18  *
  19  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  20  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  21  * A PARTICULAR PURPOSE. See the GNU General Public License for more
  22  * details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  26  */
  27
  28 #ifdef HAVE_CONFIG_H
  29 #  include "config.h"
  30 #endif
  31
  32 #include "wimlib/assert.h"
  33 #include "wimlib/endianness.h"
  34 #include "wimlib/error.h"
  35 #include "wimlib/file_io.h"
  36 #include "wimlib/integrity.h"
  37 #include "wimlib/resource.h"
  38 #include "wimlib/sha1.h"
  39 #include "wimlib/wim.h"
  40
  41 /* Size, in bytes, of each SHA1-summed chunk, when wimlib writes integrity
  42  * information. */
  43 #define INTEGRITY_CHUNK_SIZE 10485760
  44
  45 /* Only use a different chunk size for compatiblity with an existing integrity
  46  * table if the chunk size is between these two numbers. */
  47 #define INTEGRITY_MIN_CHUNK_SIZE 4096
  48 #define INTEGRITY_MAX_CHUNK_SIZE 134217728
  49
  50 struct integrity_table {
  51         u32 size;
  52         u32 num_entries;
  53         u32 chunk_size;
  54         u8  sha1sums[][20];
  55 } _packed_attribute;
  56
  57 static int
  58 calculate_chunk_sha1(int in_fd, size_t this_chunk_size,
  59                      off_t offset, u8 sha1_md[])
  60 {
  61         u8 buf[BUFFER_SIZE];
  62         SHA_CTX ctx;
  63         size_t bytes_remaining;
  64         size_t bytes_to_read;
  65         size_t bytes_read;
  66
  67         bytes_remaining = this_chunk_size;
  68         sha1_init(&ctx);
  69         do {
  70                 bytes_to_read = min(bytes_remaining, sizeof(buf));
  71                 bytes_read = full_pread(in_fd, buf, bytes_to_read, offset);
  72                 if (bytes_read != bytes_to_read) {
  73                         ERROR_WITH_ERRNO("Read error while calculating "
  74                                          "integrity checksums");
  75                         return WIMLIB_ERR_READ;
  76                 }
  77                 sha1_update(&ctx, buf, bytes_read);
  78                 bytes_remaining -= bytes_read;
  79                 offset += bytes_read;
  80         } while (bytes_remaining);
  81         sha1_final(sha1_md, &ctx);
  82         return 0;
  83 }
  84
  85
  86 /*
  87  * read_integrity_table: -  Reads the integrity table from a WIM file.
  88  *
  89  * @res_entry:
  90  *      The resource entry that specifies the location of the integrity table.
  91  *      The integrity table must exist (i.e. res_entry->offset must not be 0).
  92  *
  93  * @in_fd:
  94  *      File descriptor to the WIM file, opened for reading.
  95  *
  96  * @num_checked_bytes:
  97  *      Number of bytes of data that should be checked by the integrity table.
  98  *
  99  * @table ret:
 100  *      On success, a pointer to an in-memory structure containing the integrity
 101  *      information is written to this location.
 102  *
 103  * Returns 0 on success; nonzero on failure.  The possible error codes are:
 104  *
 105  *     * WIMLIB_ERR_INVALID_INTEGRITY_TABLE:  The integrity table is invalid.
 106  *     * WIMLIB_ERR_NOMEM:  Could not allocate memory to store the integrity
 107  *                          data.
 108  *     * WIMLIB_ERR_READ:   Could not read the integrity data from the WIM file.
 109  */
 110 static int
 111 read_integrity_table(const struct resource_entry *res_entry,
 112                      int in_fd,
 113                      u64 num_checked_bytes,
 114                      struct integrity_table **table_ret)
 115 {
 116         struct integrity_table *table;
 117         int ret;
 118         u64 expected_size;
 119         u64 expected_num_entries;
 120
 121         if (resource_is_compressed(res_entry)) {
 122                 ERROR("Didn't expect a compressed integrity table");
 123                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 124         }
 125
 126         if (res_entry->size < 8 || res_entry->size  > 0xffffffff) {
 127                 ERROR("Integrity table resource header is invalid");
 128                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 129         }
 130
 131         /* Read the integrity table into memory. */
 132         table = MALLOC((size_t)res_entry->size);
 133         if (table == NULL) {
 134                 ERROR("Can't allocate %zu bytes for integrity table",
 135                       (size_t)res_entry->size);
 136                 return WIMLIB_ERR_NOMEM;
 137         }
 138
 139         if (full_pread(in_fd, table, res_entry->size,
 140                        res_entry->offset) != res_entry->size)
 141         {
 142                 ERROR("Failed to read integrity table (size = %zu, "
 143                       " offset = %"PRIu64")",
 144                       (size_t)res_entry->size, res_entry->offset);
 145                 ret = WIMLIB_ERR_READ;
 146                 goto out_free_table;
 147         }
 148
 149         table->size        = le32_to_cpu(table->size);
 150         table->num_entries = le32_to_cpu(table->num_entries);
 151         table->chunk_size  = le32_to_cpu(table->chunk_size);
 152
 153         if (table->size != res_entry->size) {
 154                 ERROR("Inconsistent integrity table sizes: Table header says "
 155                       "%u bytes but resource entry says %u bytes",
 156                       table->size, (unsigned)res_entry->size);
 157                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 158                 goto out_free_table;
 159         }
 160
 161         DEBUG("table->size = %u, table->num_entries = %u, "
 162               "table->chunk_size = %u",
 163               table->size, table->num_entries, table->chunk_size);
 164
 165         expected_size = (u64)table->num_entries * SHA1_HASH_SIZE + 12;
 166
 167         if (table->size != expected_size) {
 168                 ERROR("Integrity table is %u bytes, but expected %"PRIu64" "
 169                       "bytes to hold %u entries",
 170                       table->size, expected_size, table->num_entries);
 171                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 172                 goto out_free_table;
 173         }
 174
 175         if (table->chunk_size == 0) {
 176                 ERROR("Cannot use integrity chunk size of 0");
 177                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 178                 goto out_free_table;
 179         }
 180
 181         expected_num_entries = DIV_ROUND_UP(num_checked_bytes, table->chunk_size);
 182
 183         if (table->num_entries != expected_num_entries) {
 184                 ERROR("%"PRIu64" integrity table entries would be required "
 185                       "to checksum the %"PRIu64" bytes from the end of the "
 186                       "header to the",
 187                       expected_num_entries, num_checked_bytes);
 188                 ERROR("end of the lookup table with a chunk size of %u, but "
 189                       "there were only %u entries",
 190                       table->chunk_size, table->num_entries);
 191                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 192                 goto out_free_table;
 193         }
 194         *table_ret = table;
 195         ret = 0;
 196         goto out;
 197 out_free_table:
 198         FREE(table);
 199 out:
 200         return ret;
 201 }
 202
 203 /*
 204  * calculate_integrity_table():
 205  *
 206  * Calculates an integrity table for the data in a file beginning at offset 208
 207  * (WIM_HEADER_DISK_SIZE).
 208  *
 209  * @in_fd:
 210  *      File descriptor for the file to be checked, opened for reading.  Does
 211  *      not need to be at any specific location in the file.
 212  *
 213  * @new_check_end:
 214  *      Offset of byte after the last byte to be checked.
 215  *
 216  * @old_table:
 217  *      If non-NULL, a pointer to the table containing the previously calculated
 218  *      integrity data for a prefix of this file.
 219  *
 220  * @old_check_end:
 221  *      If @old_table is non-NULL, the byte after the last byte that was checked
 222  *      in the old table.  Must be less than or equal to new_check_end.
 223  *
 224  * @progress_func:
 225  *      If non-NULL, a progress function that will be called after every
 226  *      calculated chunk.
 227  *
 228  * @integrity_table_ret:
 229  *      On success, a pointer to the calculated integrity table is written into
 230  *      this location.
 231  *
 232  * Returns 0 on success; nonzero on failure.
 233  */
 234 static int
 235 calculate_integrity_table(int in_fd,
 236                           off_t new_check_end,
 237                           const struct integrity_table *old_table,
 238                           off_t old_check_end,
 239                           wimlib_progress_func_t progress_func,
 240                           struct integrity_table **integrity_table_ret)
 241 {
 242         int ret;
 243         size_t chunk_size = INTEGRITY_CHUNK_SIZE;
 244
 245         /* If an old table is provided, set the chunk size to be compatible with
 246          * the old chunk size, unless the old chunk size was weird. */
 247         if (old_table != NULL) {
 248                 if (old_table->num_entries == 0 ||
 249                     old_table->chunk_size < INTEGRITY_MIN_CHUNK_SIZE ||
 250                     old_table->chunk_size > INTEGRITY_MAX_CHUNK_SIZE)
 251                         old_table = NULL;
 252                 else
 253                         chunk_size = old_table->chunk_size;
 254         }
 255
 256
 257         u64 old_check_bytes = old_check_end - WIM_HEADER_DISK_SIZE;
 258         u64 new_check_bytes = new_check_end - WIM_HEADER_DISK_SIZE;
 259
 260         u32 old_num_chunks = DIV_ROUND_UP(old_check_bytes, chunk_size);
 261         u32 new_num_chunks = DIV_ROUND_UP(new_check_bytes, chunk_size);
 262
 263         size_t old_last_chunk_size = MODULO_NONZERO(old_check_bytes, chunk_size);
 264         size_t new_last_chunk_size = MODULO_NONZERO(new_check_bytes, chunk_size);
 265
 266         size_t new_table_size = 12 + new_num_chunks * SHA1_HASH_SIZE;
 267
 268         struct integrity_table *new_table = MALLOC(new_table_size);
 269         if (!new_table)
 270                 return WIMLIB_ERR_NOMEM;
 271         new_table->num_entries = new_num_chunks;
 272         new_table->size = new_table_size;
 273         new_table->chunk_size = chunk_size;
 274
 275         u64 offset = WIM_HEADER_DISK_SIZE;
 276         union wimlib_progress_info progress;
 277
 278         if (progress_func) {
 279                 progress.integrity.total_bytes      = new_check_bytes;
 280                 progress.integrity.total_chunks     = new_num_chunks;
 281                 progress.integrity.completed_chunks = 0;
 282                 progress.integrity.completed_bytes  = 0;
 283                 progress.integrity.chunk_size       = chunk_size;
 284                 progress.integrity.filename         = NULL;
 285                 progress_func(WIMLIB_PROGRESS_MSG_CALC_INTEGRITY,
 286                               &progress);
 287         }
 288
 289         for (u32 i = 0; i < new_num_chunks; i++) {
 290                 size_t this_chunk_size;
 291                 if (i == new_num_chunks - 1)
 292                         this_chunk_size = new_last_chunk_size;
 293                 else
 294                         this_chunk_size = chunk_size;
 295                 if (old_table &&
 296                     ((this_chunk_size == chunk_size && i < old_num_chunks - 1) ||
 297                       (i == old_num_chunks - 1 && this_chunk_size == old_last_chunk_size)))
 298                 {
 299                         /* Can use SHA1 message digest from old integrity table
 300                          * */
 301                         copy_hash(new_table->sha1sums[i], old_table->sha1sums[i]);
 302                 } else {
 303                         /* Calculate the SHA1 message digest of this chunk */
 304                         ret = calculate_chunk_sha1(in_fd, this_chunk_size,
 305                                                    offset, new_table->sha1sums[i]);
 306                         if (ret) {
 307                                 FREE(new_table);
 308                                 return ret;
 309                         }
 310                 }
 311                 offset += this_chunk_size;
 312                 if (progress_func) {
 313                         progress.integrity.completed_chunks++;
 314                         progress.integrity.completed_bytes += this_chunk_size;
 315                         progress_func(WIMLIB_PROGRESS_MSG_CALC_INTEGRITY,
 316                                       &progress);
 317                 }
 318         }
 319         *integrity_table_ret = new_table;
 320         return 0;
 321 }
 322
 323 /*
 324  * write_integrity_table():
 325  *
 326  * Writes a WIM integrity table (a list of SHA1 message digests of raw 10 MiB
 327  * chunks of the file).
 328  *
 329  * This function can optionally re-use entries from an older integrity table.
 330  * To do this, make @integrity_res_entry point to the resource entry for the
 331  * older table (note: this is an input-output parameter), and set
 332  * @old_lookup_table_end to the offset of the byte directly following the last
 333  * byte checked by the old table.  If the old integrity table is invalid or
 334  * cannot be read, a warning is printed and the integrity information is
 335  * re-calculated.
 336  *
 337  * @fd:
 338  *      File descriptor to the WIM file, opened read-write, positioned at the
 339  *      location at which the integrity table is to be written.
 340  *
 341  * @integrity_res_entry:
 342  *      Resource entry which will be set to point to the integrity table on
 343  *      success.  In addition, if @old_lookup_table_end != 0, this initially
 344  *      must point to the resource entry for the old integrity table for the
 345  *      WIM.
 346  *
 347  * @new_lookup_table_end:
 348  *      The offset of the byte directly following the lookup table in the WIM
 349  *      being written.
 350  *
 351  * @old_lookup_table_end:
 352  *      If nonzero, the offset of the byte directly following the old lookup
 353  *      table in the WIM.
 354  *
 355  * @progress_func
 356  *      If non-NULL, a progress function that will be called after every
 357  *      calculated chunk.
 358  *
 359  * Returns:
 360  *      0 on success, nonzero on failure.  The possible error codes are:
 361  *         * WIMLIB_ERR_WRITE:  Could not write the integrity table.
 362  *         * WIMLIB_ERR_READ:   Could not read a chunk of data that needed
 363  *                              to be checked.
 364  */
 365 int
 366 write_integrity_table(int fd,
 367                       struct resource_entry *integrity_res_entry,
 368                       off_t new_lookup_table_end,
 369                       off_t old_lookup_table_end,
 370                       wimlib_progress_func_t progress_func)
 371 {
 372         struct integrity_table *old_table;
 373         struct integrity_table *new_table;
 374         int ret;
 375         off_t cur_offset;
 376         u32 new_table_size;
 377
 378         wimlib_assert(old_lookup_table_end <= new_lookup_table_end);
 379
 380         cur_offset = filedes_offset(fd);
 381         if (cur_offset == -1)
 382                 return WIMLIB_ERR_WRITE;
 383
 384         if (integrity_res_entry->offset == 0 || old_lookup_table_end == 0) {
 385                 old_table = NULL;
 386         } else {
 387                 ret = read_integrity_table(integrity_res_entry, fd,
 388                                            old_lookup_table_end - WIM_HEADER_DISK_SIZE,
 389                                            &old_table);
 390                 if (ret == WIMLIB_ERR_INVALID_INTEGRITY_TABLE) {
 391                         WARNING("Old integrity table is invalid! "
 392                                 "Ignoring it");
 393                 } else if (ret != 0) {
 394                         WARNING("Can't read old integrity table! "
 395                                 "Ignoring it");
 396                 }
 397         }
 398
 399         ret = calculate_integrity_table(fd, new_lookup_table_end,
 400                                         old_table, old_lookup_table_end,
 401                                         progress_func, &new_table);
 402         if (ret)
 403                 goto out_free_old_table;
 404
 405         new_table_size = new_table->size;
 406
 407         new_table->size        = cpu_to_le32(new_table->size);
 408         new_table->num_entries = cpu_to_le32(new_table->num_entries);
 409         new_table->chunk_size  = cpu_to_le32(new_table->chunk_size);
 410
 411         if (full_write(fd, new_table, new_table_size) != new_table_size) {
 412                 ERROR_WITH_ERRNO("Failed to write WIM integrity table");
 413                 ret = WIMLIB_ERR_WRITE;
 414         } else {
 415                 integrity_res_entry->offset        = cur_offset;
 416                 integrity_res_entry->size          = new_table_size;
 417                 integrity_res_entry->original_size = new_table_size;
 418                 integrity_res_entry->flags         = 0;
 419                 ret = 0;
 420         }
 421         FREE(new_table);
 422 out_free_old_table:
 423         FREE(old_table);
 424         return ret;
 425 }
 426
 427 /*
 428  * verify_integrity():
 429  *
 430  * Checks a WIM for consistency with the integrity table.
 431  *
 432  * @in_fd:
 433  *      File descriptor to the WIM file, opened for reading.
 434  *
 435  * @table:
 436  *      The integrity table for the WIM, read into memory.
 437  *
 438  * @bytes_to_check:
 439  *      Number of bytes in the WIM that need to be checked (offset of end of the
 440  *      lookup table minus offset of end of the header).
 441  *
 442  * @progress_func
 443  *      If non-NULL, a progress function that will be called after every
 444  *      verified chunk.
 445  *
 446  * Returns:
 447  *      > 0 (WIMLIB_ERR_*) on error
 448  *      0 (WIM_INTEGRITY_OK) if the integrity was checked successfully and there
 449  *      were no inconsistencies.
 450  *      -1 (WIM_INTEGRITY_NOT_OK) if the WIM failed the integrity check.
 451  */
 452 static int
 453 verify_integrity(int in_fd, const tchar *filename,
 454                  const struct integrity_table *table,
 455                  u64 bytes_to_check,
 456                  wimlib_progress_func_t progress_func)
 457 {
 458         int ret;
 459         u64 offset = WIM_HEADER_DISK_SIZE;
 460         u8 sha1_md[SHA1_HASH_SIZE];
 461         union wimlib_progress_info progress;
 462
 463         if (progress_func) {
 464                 progress.integrity.total_bytes      = bytes_to_check;
 465                 progress.integrity.total_chunks     = table->num_entries;
 466                 progress.integrity.completed_chunks = 0;
 467                 progress.integrity.completed_bytes  = 0;
 468                 progress.integrity.chunk_size       = table->chunk_size;
 469                 progress.integrity.filename         = filename;
 470                 progress_func(WIMLIB_PROGRESS_MSG_VERIFY_INTEGRITY,
 471                               &progress);
 472         }
 473         for (u32 i = 0; i < table->num_entries; i++) {
 474                 size_t this_chunk_size;
 475                 if (i == table->num_entries - 1)
 476                         this_chunk_size = MODULO_NONZERO(bytes_to_check,
 477                                                          table->chunk_size);
 478                 else
 479                         this_chunk_size = table->chunk_size;
 480
 481                 ret = calculate_chunk_sha1(in_fd, this_chunk_size, offset, sha1_md);
 482                 if (ret)
 483                         return ret;
 484
 485                 if (!hashes_equal(sha1_md, table->sha1sums[i]))
 486                         return WIM_INTEGRITY_NOT_OK;
 487
 488                 offset += this_chunk_size;
 489                 if (progress_func) {
 490                         progress.integrity.completed_chunks++;
 491                         progress.integrity.completed_bytes += this_chunk_size;
 492                         progress_func(WIMLIB_PROGRESS_MSG_VERIFY_INTEGRITY,
 493                                       &progress);
 494                 }
 495         }
 496         return WIM_INTEGRITY_OK;
 497 }
 498
 499
 500 /*
 501  * check_wim_integrity():
 502  *
 503  * Verifies the integrity of the WIM by making sure the SHA1 message digests of
 504  * ~10 MiB chunks of the WIM match up with the values given in the integrity
 505  * table.
 506  *
 507  * @w:
 508  *      The WIM, opened for reading, and with the header already read.
 509  *
 510  * @progress_func
 511  *      If non-NULL, a progress function that will be called after every
 512  *      verified chunk.
 513  *
 514  * Returns:
 515  *      > 0 (WIMLIB_ERR_*) on error
 516  *      0 (WIM_INTEGRITY_OK) if the integrity was checked successfully and there
 517  *      were no inconsistencies.
 518  *      -1 (WIM_INTEGRITY_NOT_OK) if the WIM failed the integrity check.
 519  *      -2 (WIM_INTEGRITY_NONEXISTENT) if the WIM contains no integrity
 520  *      information.
 521  */
 522 int
 523 check_wim_integrity(WIMStruct *w, wimlib_progress_func_t progress_func)
 524 {
 525         int ret;
 526         u64 bytes_to_check;
 527         struct integrity_table *table;
 528         u64 end_lookup_table_offset;
 529
 530         if (w->hdr.integrity.offset == 0) {
 531                 DEBUG("No integrity information.");
 532                 return WIM_INTEGRITY_NONEXISTENT;
 533         }
 534
 535         end_lookup_table_offset = w->hdr.lookup_table_res_entry.offset +
 536                                   w->hdr.lookup_table_res_entry.size;
 537
 538         if (end_lookup_table_offset < WIM_HEADER_DISK_SIZE) {
 539                 ERROR("WIM lookup table ends before WIM header ends!");
 540                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 541         }
 542
 543         bytes_to_check = end_lookup_table_offset - WIM_HEADER_DISK_SIZE;
 544
 545         ret = read_integrity_table(&w->hdr.integrity, w->in_fd,
 546                                    bytes_to_check, &table);
 547         if (ret)
 548                 return ret;
 549         ret = verify_integrity(w->in_fd, w->filename, table,
 550                                bytes_to_check, progress_func);
 551         FREE(table);
 552         return ret;
 553 }