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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 #include "wimlib/write.h"
  41
  42 /* Size, in bytes, of each SHA1-summed chunk, when wimlib writes integrity
  43  * information. */
  44 #define INTEGRITY_CHUNK_SIZE 10485760
  45
  46 /* Only use a different chunk size for compatiblity with an existing integrity
  47  * table if the chunk size is between these two numbers. */
  48 #define INTEGRITY_MIN_CHUNK_SIZE 4096
  49 #define INTEGRITY_MAX_CHUNK_SIZE 134217728
  50
  51 struct integrity_table {
  52         u32 size;
  53         u32 num_entries;
  54         u32 chunk_size;
  55         u8  sha1sums[][20];
  56 } _packed_attribute;
  57
  58 static int
  59 calculate_chunk_sha1(struct filedes *in_fd, size_t this_chunk_size,
  60                      off_t offset, u8 sha1_md[])
  61 {
  62         u8 buf[BUFFER_SIZE];
  63         SHA_CTX ctx;
  64         size_t bytes_remaining;
  65         size_t bytes_to_read;
  66         int ret;
  67
  68         bytes_remaining = this_chunk_size;
  69         sha1_init(&ctx);
  70         do {
  71                 bytes_to_read = min(bytes_remaining, sizeof(buf));
  72                 ret = full_pread(in_fd, buf, bytes_to_read, offset);
  73                 if (ret) {
  74                         ERROR_WITH_ERRNO("Read error while calculating "
  75                                          "integrity checksums");
  76                         return ret;
  77                 }
  78                 sha1_update(&ctx, buf, bytes_to_read);
  79                 bytes_remaining -= bytes_to_read;
  80                 offset += bytes_to_read;
  81         } while (bytes_remaining);
  82         sha1_final(sha1_md, &ctx);
  83         return 0;
  84 }
  85
  86
  87 /*
  88  * read_integrity_table: -  Reads the integrity table from a WIM file.
  89  *
  90  * @wim:
  91  *      WIMStruct for the WIM file; @wim->hdr.integrity_table_reshdr specifies
  92  *      the location of the integrity table.  @wim->in_fd is expected to be a
  93  *      seekable file descriptor to the WIM file opened for reading.
  94  *
  95  * @num_checked_bytes:
  96  *      Number of bytes of data that should be checked by the integrity table.
  97  *
  98  * @table_ret:
  99  *      On success, a pointer to an in-memory structure containing the integrity
 100  *      information is written to this location.
 101  *
 102  * Return values:
 103  *      WIMLIB_ERR_SUCCESS (0)
 104  *      WIMLIB_ERR_INVALID_INTEGRITY_TABLE
 105  *      WIMLIB_ERR_NOMEM
 106  *      WIMLIB_ERR_READ
 107  *      WIMLIB_ERR_UNEXPECTED_END_OF_FILE
 108  */
 109 static int
 110 read_integrity_table(WIMStruct *wim, u64 num_checked_bytes,
 111                      struct integrity_table **table_ret)
 112 {
 113         void *buf;
 114         struct integrity_table *table;
 115         int ret;
 116
 117         if (wim->hdr.integrity_table_reshdr.uncompressed_size < 8)
 118                 goto invalid;
 119
 120         DEBUG("Reading integrity table.");
 121
 122         ret = wim_reshdr_to_data(&wim->hdr.integrity_table_reshdr, wim, &buf);
 123         if (ret)
 124                 return ret;
 125         table = buf;
 126
 127         table->size        = le32_to_cpu(table->size);
 128         table->num_entries = le32_to_cpu(table->num_entries);
 129         table->chunk_size  = le32_to_cpu(table->chunk_size);
 130
 131         DEBUG("table->size = %u, table->num_entries = %u, "
 132               "table->chunk_size = %u",
 133               table->size, table->num_entries, table->chunk_size);
 134
 135         if (table->size != wim->hdr.integrity_table_reshdr.uncompressed_size ||
 136             table->size != (u64)table->num_entries * SHA1_HASH_SIZE + 12 ||
 137             table->chunk_size == 0 ||
 138             table->num_entries != DIV_ROUND_UP(num_checked_bytes, table->chunk_size))
 139         {
 140                 FREE(table);
 141                 goto invalid;
 142         }
 143
 144         *table_ret = table;
 145         return 0;
 146
 147 invalid:
 148         ERROR("Integrity table is invalid");
 149         return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 150 }
 151
 152 /*
 153  * calculate_integrity_table():
 154  *
 155  * Calculates an integrity table for the data in a file beginning at offset 208
 156  * (WIM_HEADER_DISK_SIZE).
 157  *
 158  * @in_fd:
 159  *      File descriptor for the file to be checked, opened for reading.  Does
 160  *      not need to be at any specific location in the file.
 161  *
 162  * @new_check_end:
 163  *      Offset of byte after the last byte to be checked.
 164  *
 165  * @old_table:
 166  *      If non-NULL, a pointer to the table containing the previously calculated
 167  *      integrity data for a prefix of this file.
 168  *
 169  * @old_check_end:
 170  *      If @old_table is non-NULL, the byte after the last byte that was checked
 171  *      in the old table.  Must be less than or equal to new_check_end.
 172  *
 173  * @progress_func:
 174  *      If non-NULL, a progress function that will be called after every
 175  *      calculated chunk.
 176  *
 177  * @integrity_table_ret:
 178  *      On success, a pointer to the calculated integrity table is written into
 179  *      this location.
 180  *
 181  * Return values:
 182  *      WIMLIB_ERR_SUCCESS (0)
 183  *      WIMLIB_ERR_NOMEM
 184  *      WIMLIB_ERR_READ
 185  *      WIMLIB_ERR_UNEXPECTED_END_OF_FILE
 186  */
 187 static int
 188 calculate_integrity_table(struct filedes *in_fd,
 189                           off_t new_check_end,
 190                           const struct integrity_table *old_table,
 191                           off_t old_check_end,
 192                           wimlib_progress_func_t progress_func,
 193                           struct integrity_table **integrity_table_ret)
 194 {
 195         int ret;
 196         size_t chunk_size = INTEGRITY_CHUNK_SIZE;
 197
 198         /* If an old table is provided, set the chunk size to be compatible with
 199          * the old chunk size, unless the old chunk size was weird. */
 200         if (old_table != NULL) {
 201                 if (old_table->num_entries == 0 ||
 202                     old_table->chunk_size < INTEGRITY_MIN_CHUNK_SIZE ||
 203                     old_table->chunk_size > INTEGRITY_MAX_CHUNK_SIZE)
 204                         old_table = NULL;
 205                 else
 206                         chunk_size = old_table->chunk_size;
 207         }
 208
 209
 210         u64 old_check_bytes = old_check_end - WIM_HEADER_DISK_SIZE;
 211         u64 new_check_bytes = new_check_end - WIM_HEADER_DISK_SIZE;
 212
 213         u32 old_num_chunks = DIV_ROUND_UP(old_check_bytes, chunk_size);
 214         u32 new_num_chunks = DIV_ROUND_UP(new_check_bytes, chunk_size);
 215
 216         size_t old_last_chunk_size = MODULO_NONZERO(old_check_bytes, chunk_size);
 217         size_t new_last_chunk_size = MODULO_NONZERO(new_check_bytes, chunk_size);
 218
 219         size_t new_table_size = 12 + new_num_chunks * SHA1_HASH_SIZE;
 220
 221         struct integrity_table *new_table = MALLOC(new_table_size);
 222         if (!new_table)
 223                 return WIMLIB_ERR_NOMEM;
 224         new_table->num_entries = new_num_chunks;
 225         new_table->size = new_table_size;
 226         new_table->chunk_size = chunk_size;
 227
 228         u64 offset = WIM_HEADER_DISK_SIZE;
 229         union wimlib_progress_info progress;
 230
 231         if (progress_func) {
 232                 progress.integrity.total_bytes      = new_check_bytes;
 233                 progress.integrity.total_chunks     = new_num_chunks;
 234                 progress.integrity.completed_chunks = 0;
 235                 progress.integrity.completed_bytes  = 0;
 236                 progress.integrity.chunk_size       = chunk_size;
 237                 progress.integrity.filename         = NULL;
 238                 progress_func(WIMLIB_PROGRESS_MSG_CALC_INTEGRITY,
 239                               &progress);
 240         }
 241
 242         for (u32 i = 0; i < new_num_chunks; i++) {
 243                 size_t this_chunk_size;
 244                 if (i == new_num_chunks - 1)
 245                         this_chunk_size = new_last_chunk_size;
 246                 else
 247                         this_chunk_size = chunk_size;
 248                 if (old_table &&
 249                     ((this_chunk_size == chunk_size && i < old_num_chunks - 1) ||
 250                       (i == old_num_chunks - 1 && this_chunk_size == old_last_chunk_size)))
 251                 {
 252                         /* Can use SHA1 message digest from old integrity table
 253                          * */
 254                         copy_hash(new_table->sha1sums[i], old_table->sha1sums[i]);
 255                 } else {
 256                         /* Calculate the SHA1 message digest of this chunk */
 257                         ret = calculate_chunk_sha1(in_fd, this_chunk_size,
 258                                                    offset, new_table->sha1sums[i]);
 259                         if (ret) {
 260                                 FREE(new_table);
 261                                 return ret;
 262                         }
 263                 }
 264                 offset += this_chunk_size;
 265                 if (progress_func) {
 266                         progress.integrity.completed_chunks++;
 267                         progress.integrity.completed_bytes += this_chunk_size;
 268                         progress_func(WIMLIB_PROGRESS_MSG_CALC_INTEGRITY,
 269                                       &progress);
 270                 }
 271         }
 272         *integrity_table_ret = new_table;
 273         return 0;
 274 }
 275
 276 /*
 277  * write_integrity_table():
 278  *
 279  * Writes a WIM integrity table (a list of SHA1 message digests of raw 10 MiB
 280  * chunks of the file).
 281  *
 282  * This function can optionally re-use entries from an older integrity table.
 283  * To do this, ensure that @wim->hdr.integrity_table_reshdr is the resource
 284  * header for the older table (note: this is an input-output parameter), and set
 285  * @old_lookup_table_end to the offset of the byte directly following the last
 286  * byte checked by the old table.  If the old integrity table is invalid or
 287  * cannot be read, a warning is printed and the integrity information is
 288  * re-calculated.
 289  *
 290  * @wim:
 291  *      WIMStruct for the WIM file.  @wim->out_fd must be a seekable descriptor
 292  *      to the new WIM file, opened read-write, positioned at the location at
 293  *      which the integrity table is to be written.  Furthermore,
 294  *      @wim->hdr.integrity is expected to be a resource entry which will be set
 295  *      to the integrity table information on success.  In addition, if
 296  *      @old_lookup_table_end != 0, @wim->hdr.integrity must initially contain
 297  *      information about the old integrity table, and @wim->in_fd must be a
 298  *      seekable descriptor to the original WIM file opened for reading.
 299  *
 300  * @new_lookup_table_end:
 301  *      The offset of the byte directly following the lookup table in the WIM
 302  *      being written.
 303  *
 304  * @old_lookup_table_end:
 305  *      If nonzero, the offset of the byte directly following the old lookup
 306  *      table in the WIM.
 307  *
 308  * @progress_func
 309  *      If non-NULL, a progress function that will be called after every
 310  *      calculated chunk.
 311  *
 312  * Return values:
 313  *      WIMLIB_ERR_SUCCESS (0)
 314  *      WIMLIB_ERR_NOMEM
 315  *      WIMLIB_ERR_UNEXPECTED_END_OF_FILE
 316  *      WIMLIB_ERR_WRITE
 317  */
 318 int
 319 write_integrity_table(WIMStruct *wim,
 320                       off_t new_lookup_table_end,
 321                       off_t old_lookup_table_end,
 322                       wimlib_progress_func_t progress_func)
 323 {
 324         struct integrity_table *old_table;
 325         struct integrity_table *new_table;
 326         int ret;
 327         u32 new_table_size;
 328
 329         DEBUG("Writing integrity table "
 330               "(new_lookup_table_end=%"PRIu64", old_lookup_table_end=%"PRIu64")",
 331               new_lookup_table_end, old_lookup_table_end);
 332
 333         wimlib_assert(old_lookup_table_end <= new_lookup_table_end);
 334
 335         old_table = NULL;
 336         if (wim_has_integrity_table(wim) && old_lookup_table_end != 0) {
 337                 ret = read_integrity_table(wim,
 338                                            old_lookup_table_end - WIM_HEADER_DISK_SIZE,
 339                                            &old_table);
 340                 if (ret == WIMLIB_ERR_INVALID_INTEGRITY_TABLE) {
 341                         WARNING("Old integrity table is invalid! "
 342                                 "Ignoring it");
 343                 } else if (ret != 0) {
 344                         WARNING("Can't read old integrity table! "
 345                                 "Ignoring it");
 346                 }
 347         }
 348
 349         ret = calculate_integrity_table(&wim->out_fd, new_lookup_table_end,
 350                                         old_table, old_lookup_table_end,
 351                                         progress_func, &new_table);
 352         if (ret)
 353                 goto out_free_old_table;
 354
 355         new_table_size = new_table->size;
 356
 357         new_table->size        = cpu_to_le32(new_table->size);
 358         new_table->num_entries = cpu_to_le32(new_table->num_entries);
 359         new_table->chunk_size  = cpu_to_le32(new_table->chunk_size);
 360
 361         ret = write_wim_resource_from_buffer(new_table,
 362                                              new_table_size,
 363                                              0,
 364                                              &wim->out_fd,
 365                                              WIMLIB_COMPRESSION_TYPE_NONE,
 366                                              0,
 367                                              &wim->hdr.integrity_table_reshdr,
 368                                              NULL,
 369                                              0);
 370         FREE(new_table);
 371 out_free_old_table:
 372         FREE(old_table);
 373         DEBUG("ret=%d", ret);
 374         return ret;
 375 }
 376
 377 /*
 378  * verify_integrity():
 379  *
 380  * Checks a WIM for consistency with the integrity table.
 381  *
 382  * @in_fd:
 383  *      File descriptor to the WIM file, opened for reading.
 384  *
 385  * @table:
 386  *      The integrity table for the WIM, read into memory.
 387  *
 388  * @bytes_to_check:
 389  *      Number of bytes in the WIM that need to be checked (offset of end of the
 390  *      lookup table minus offset of end of the header).
 391  *
 392  * @progress_func
 393  *      If non-NULL, a progress function that will be called after every
 394  *      verified chunk.
 395  *
 396  * Returns:
 397  *      > 0 (WIMLIB_ERR_READ, WIMLIB_ERR_UNEXPECTED_END_OF_FILE) on error
 398  *      0 (WIM_INTEGRITY_OK) if the integrity was checked successfully and there
 399  *      were no inconsistencies.
 400  *      -1 (WIM_INTEGRITY_NOT_OK) if the WIM failed the integrity check.
 401  */
 402 static int
 403 verify_integrity(struct filedes *in_fd, const tchar *filename,
 404                  const struct integrity_table *table,
 405                  u64 bytes_to_check,
 406                  wimlib_progress_func_t progress_func)
 407 {
 408         int ret;
 409         u64 offset = WIM_HEADER_DISK_SIZE;
 410         u8 sha1_md[SHA1_HASH_SIZE];
 411         union wimlib_progress_info progress;
 412
 413         if (progress_func) {
 414                 progress.integrity.total_bytes      = bytes_to_check;
 415                 progress.integrity.total_chunks     = table->num_entries;
 416                 progress.integrity.completed_chunks = 0;
 417                 progress.integrity.completed_bytes  = 0;
 418                 progress.integrity.chunk_size       = table->chunk_size;
 419                 progress.integrity.filename         = filename;
 420                 progress_func(WIMLIB_PROGRESS_MSG_VERIFY_INTEGRITY,
 421                               &progress);
 422         }
 423         for (u32 i = 0; i < table->num_entries; i++) {
 424                 size_t this_chunk_size;
 425                 if (i == table->num_entries - 1)
 426                         this_chunk_size = MODULO_NONZERO(bytes_to_check,
 427                                                          table->chunk_size);
 428                 else
 429                         this_chunk_size = table->chunk_size;
 430
 431                 ret = calculate_chunk_sha1(in_fd, this_chunk_size, offset, sha1_md);
 432                 if (ret)
 433                         return ret;
 434
 435                 if (!hashes_equal(sha1_md, table->sha1sums[i]))
 436                         return WIM_INTEGRITY_NOT_OK;
 437
 438                 offset += this_chunk_size;
 439                 if (progress_func) {
 440                         progress.integrity.completed_chunks++;
 441                         progress.integrity.completed_bytes += this_chunk_size;
 442                         progress_func(WIMLIB_PROGRESS_MSG_VERIFY_INTEGRITY,
 443                                       &progress);
 444                 }
 445         }
 446         return WIM_INTEGRITY_OK;
 447 }
 448
 449
 450 /*
 451  * check_wim_integrity():
 452  *
 453  * Verifies the integrity of the WIM by making sure the SHA1 message digests of
 454  * ~10 MiB chunks of the WIM match up with the values given in the integrity
 455  * table.
 456  *
 457  * @wim:
 458  *      The WIM, opened for reading.
 459  *
 460  * @progress_func
 461  *      If non-NULL, a progress function that will be called after every
 462  *      verified chunk.
 463  *
 464  * Returns:
 465  *      > 0 (WIMLIB_ERR_INVALID_INTEGRITY_TABLE, WIMLIB_ERR_READ,
 466  *           WIMLIB_ERR_UNEXPECTED_END_OF_FILE) on error
 467  *      0 (WIM_INTEGRITY_OK) if the integrity was checked successfully and there
 468  *      were no inconsistencies.
 469  *      -1 (WIM_INTEGRITY_NOT_OK) if the WIM failed the integrity check.
 470  *      -2 (WIM_INTEGRITY_NONEXISTENT) if the WIM contains no integrity
 471  *      information.
 472  */
 473 int
 474 check_wim_integrity(WIMStruct *wim, wimlib_progress_func_t progress_func)
 475 {
 476         int ret;
 477         u64 bytes_to_check;
 478         struct integrity_table *table;
 479         u64 end_lookup_table_offset;
 480
 481         if (!wim_has_integrity_table(wim)) {
 482                 DEBUG("No integrity information.");
 483                 return WIM_INTEGRITY_NONEXISTENT;
 484         }
 485
 486         end_lookup_table_offset = wim->hdr.lookup_table_reshdr.offset_in_wim +
 487                                   wim->hdr.lookup_table_reshdr.size_in_wim;
 488
 489         if (end_lookup_table_offset < WIM_HEADER_DISK_SIZE) {
 490                 ERROR("WIM lookup table ends before WIM header ends!");
 491                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 492         }
 493
 494         bytes_to_check = end_lookup_table_offset - WIM_HEADER_DISK_SIZE;
 495
 496         ret = read_integrity_table(wim, bytes_to_check, &table);
 497         if (ret)
 498                 return ret;
 499         ret = verify_integrity(&wim->in_fd, wim->filename, table,
 500                                bytes_to_check, progress_func);
 501         FREE(table);
 502         return ret;
 503 }