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