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   1 /*
   2  * integrity.c
   3  *
   4  * WIM files can optionally contain an array of SHA1 message digests at the end,
   5  * one digest for each 1 MB of the file.  This file implements the checking of
   6  * the digests, and the writing of the digests for new WIM files.
   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 Lesser General Public License as published by the Free
  16  * Software Foundation; either version 2.1 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 Lesser General Public License for more
  22  * details.
  23  *
  24  * You should have received a copy of the GNU Lesser General Public License
  25  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  26  */
  27
  28 #include "wimlib_internal.h"
  29 #include "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 /*
  37  * Verifies the integrity of a WIM.
  38  *
  39  * @fp:            FILE* of the WIM, currently positioned at the end of the header.
  40  * @num_bytes:     Number of bytes to verify the integrity of.
  41  * @chunk_size:    Chunk size per SHA1 message digest.
  42  * @sha1sums:      Array of SHA1 message digests; 20 bytes each, one per chunk.
  43  * @show_progress: Nonzero if the percent complete is to be printed after every
  44  *                      chunk.
  45  * @status:        On success, set to WIM_INTEGRITY_OK or WIM_INTEGRITY_NOT_OK
  46  *                      based on whether the WIM is intact or not.
  47  */
  48 static int verify_integrity(FILE *fp, u64 num_bytes, u32 chunk_size,
  49                             const u8 *sha1sums, int show_progress,
  50                             int *status)
  51 {
  52         char  *chunk_buf;
  53         u8     resblock[SHA1_HASH_SIZE];
  54         u64    bytes_remaining;
  55         size_t bytes_to_read;
  56         uint   percent_done;
  57         int    ret;
  58
  59         chunk_buf = MALLOC(chunk_size);
  60         if (!chunk_buf) {
  61                 ERROR("Failed to allocate %u byte buffer for integrity chunks",
  62                       chunk_size);
  63                 return WIMLIB_ERR_NOMEM;
  64         }
  65         bytes_remaining = num_bytes;
  66         while (bytes_remaining != 0) {
  67                 if (show_progress) {
  68                         percent_done = (num_bytes - bytes_remaining) * 100 /
  69                                         num_bytes;
  70                         printf("Verifying integrity of WIM (%"PRIu64" bytes "
  71                                         "remaining, %u%% done)       \r",
  72                                         bytes_remaining, percent_done);
  73                         fflush(stdout);
  74                 }
  75                 bytes_to_read = min(chunk_size, bytes_remaining);
  76                 if (fread(chunk_buf, 1, bytes_to_read, fp) != bytes_to_read) {
  77                         if (feof(fp)) {
  78                                 ERROR("Unexpected EOF while verifying "
  79                                       "integrity of WIM");
  80                         } else {
  81                                 ERROR_WITH_ERRNO("File stream error while "
  82                                                  "verifying integrity of WIM");
  83                         }
  84                         ret = WIMLIB_ERR_READ;
  85                         goto verify_integrity_error;
  86                 }
  87                 sha1_buffer(chunk_buf, bytes_to_read, resblock);
  88                 if (!hashes_equal(resblock, sha1sums)) {
  89                         *status = WIM_INTEGRITY_NOT_OK;
  90                         goto verify_integrity_done;
  91                 }
  92                 sha1sums += SHA1_HASH_SIZE;
  93                 bytes_remaining -= bytes_to_read;
  94         }
  95         *status = WIM_INTEGRITY_OK;
  96 verify_integrity_done:
  97         ret = 0;
  98 verify_integrity_error:
  99         FREE(chunk_buf);
 100         if (show_progress)
 101                 putchar('\n');
 102         return ret;
 103 }
 104
 105 /*
 106  * Verifies the integrity of the WIM.
 107  *
 108  * @show_progress: Nonzero if the percent complete is to be printed after every
 109  *                      chunk.
 110  * @status:        On success, set to WIM_INTEGRITY_OK, WIM_INTEGRITY_NOT_OK,
 111  *                      or WIM_INTEGRITY_NONEXISTENT.
 112  *
 113  * Returns: 0, WIMLIB_ERR_INVALID_INTEGRITY_TABLE, WIMLIB_ERR_NOMEM, or
 114  * WIMLIB_ERR_READ.  If nonzero, the boolean pointed to by @ok is not changed.
 115  */
 116 int check_wim_integrity(WIMStruct *w, int show_progress, int *status)
 117 {
 118
 119         struct resource_entry *res_entry;
 120         int ctype;
 121         u8 *buf = NULL;
 122         int ret;
 123         u32 integrity_table_size;
 124         u32 num_entries;
 125         u32 chunk_size;
 126         const u8 *p;
 127         u64 expected_size;
 128         u64 end_lookup_table_offset;
 129         u64 bytes_to_check;
 130         u64 expected_num_entries;
 131
 132         res_entry = &w->hdr.integrity;
 133         if (res_entry->size == 0) {
 134                 DEBUG("No integrity information.");
 135                 *status = WIM_INTEGRITY_NONEXISTENT;
 136                 return 0;
 137         }
 138         if (res_entry->original_size < 12) {
 139                 ERROR("Integrity table is too short");
 140                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 141         }
 142         if (res_entry->flags & WIM_RESHDR_FLAG_COMPRESSED) {
 143                 ERROR("Didn't expect a compressed integrity table");
 144                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 145         }
 146
 147         /* Read the integrity table into memory. */
 148         buf = MALLOC(res_entry->original_size);
 149         if (!buf) {
 150                 ERROR("Out of memory (needed %zu bytes for integrity table)",
 151                       res_entry->original_size);
 152                 ret = WIMLIB_ERR_NOMEM;
 153                 goto out;
 154         }
 155         ret = read_uncompressed_resource(w->fp, res_entry->offset,
 156                                          res_entry->original_size, buf);
 157         if (ret != 0) {
 158                 ERROR("Failed to read integrity table (size = %"PRIu64", "
 159                       "original_size = %"PRIu64", offset = "
 160                       "%"PRIu64")",
 161                       (u64)res_entry->size, res_entry->original_size,
 162                       res_entry->offset);
 163                 goto out;
 164         }
 165
 166         p = get_u32(buf, &integrity_table_size);
 167         p = get_u32(p, &num_entries);
 168         p = get_u32(p, &chunk_size);
 169
 170         /* p now points to the array of SHA1 message digests for the WIM. */
 171
 172         /* Make sure the integrity table is the right size. */
 173         if (integrity_table_size != res_entry->original_size) {
 174                 ERROR("Inconsistent integrity table sizes: header says %u "
 175                       "bytes but resource entry says "
 176                       "%"PRIu64" bytes",
 177                       integrity_table_size, res_entry->original_size);
 178                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 179                 goto out;
 180         }
 181
 182         DEBUG("integrity_table_size = %u, num_entries = %u, chunk_size = %u",
 183               integrity_table_size, num_entries, chunk_size);
 184
 185
 186         expected_size = num_entries * SHA1_HASH_SIZE + 12;
 187
 188         if (integrity_table_size != expected_size) {
 189                 ERROR("Integrity table is %u bytes, but expected %"PRIu64" "
 190                       "bytes to hold %u entries",
 191                       integrity_table_size, expected_size, num_entries);
 192                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 193                 goto out;
 194         }
 195
 196         if (chunk_size == 0) {
 197                 ERROR("Cannot use integrity chunk size of 0");
 198                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 199                 goto out;
 200         }
 201
 202         end_lookup_table_offset = w->hdr.lookup_table_res_entry.offset +
 203                                   w->hdr.lookup_table_res_entry.size;
 204
 205         bytes_to_check = end_lookup_table_offset - WIM_HEADER_DISK_SIZE;
 206
 207         expected_num_entries = (bytes_to_check + chunk_size - 1) / chunk_size;
 208
 209         if (num_entries != expected_num_entries) {
 210                 ERROR("%"PRIu64" entries would be required to checksum "
 211                       "the %"PRIu64" bytes from the end of the header to the",
 212                       expected_num_entries, bytes_to_check);
 213                 ERROR("end of the lookup table with a chunk size of %u, but "
 214                       "there were only %u entries", chunk_size, num_entries);
 215                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 216                 goto out;
 217         }
 218
 219         /* The integrity checking starts after the header, so seek to the offset
 220          * in the WIM after the header. */
 221
 222         if (fseeko(w->fp, WIM_HEADER_DISK_SIZE, SEEK_SET) != 0) {
 223                 ERROR_WITH_ERRNO("Failed to seek to byte %u of WIM to check "
 224                                  "integrity", WIM_HEADER_DISK_SIZE);
 225                 ret = WIMLIB_ERR_READ;
 226                 goto out;
 227         }
 228         /* call verify_integrity(), which does the actual checking of the SHA1
 229          * message digests. */
 230         ret = verify_integrity(w->fp, bytes_to_check, chunk_size, p,
 231                                show_progress, status);
 232 out:
 233         FREE(buf);
 234         return ret;
 235 }
 236
 237 /*
 238  * Writes integrity information to the output stream for a WIM file being
 239  * written.
 240  *
 241  * @end_header_offset is the offset of the byte after the header, which is the
 242  *      beginning of the region that is checksummed.
 243  *
 244  * @end_lookup_table_offset is the offset of the byte after the lookup table,
 245  *      which is the end of the region that is checksummed.
 246  */
 247 int write_integrity_table(FILE *out, u64 end_header_offset,
 248                           u64 end_lookup_table_offset, int show_progress)
 249 {
 250         u64   bytes_to_check;
 251         u64   bytes_remaining;
 252         u8   *buf;
 253         u8   *p;
 254         char *chunk_buf;
 255         u32   num_entries;
 256         u32   integrity_table_size;
 257         int   ret;
 258
 259         DEBUG("Writing integrity table");
 260         if (fseeko(out, end_header_offset, SEEK_SET) != 0) {
 261                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" of WIM to "
 262                                  "calculate integrity data", end_header_offset);
 263                 return WIMLIB_ERR_WRITE;
 264         }
 265
 266         bytes_to_check = end_lookup_table_offset - end_header_offset;
 267         num_entries = bytes_to_check / INTEGRITY_CHUNK_SIZE +
 268                         (bytes_to_check % INTEGRITY_CHUNK_SIZE != 0);
 269         integrity_table_size = num_entries * SHA1_HASH_SIZE + 3 * sizeof(u32);
 270
 271         DEBUG("integrity table size = %u", integrity_table_size);
 272
 273
 274         buf = MALLOC(integrity_table_size);
 275         if (!buf) {
 276                 ERROR("Failed to allocate %u bytes for integrity table",
 277                       integrity_table_size);
 278                 return WIMLIB_ERR_NOMEM;
 279         }
 280
 281         p = put_u32(buf, integrity_table_size);
 282         p = put_u32(p, num_entries);
 283         p = put_u32(p, INTEGRITY_CHUNK_SIZE);
 284
 285         chunk_buf = MALLOC(INTEGRITY_CHUNK_SIZE);
 286         if (!chunk_buf) {
 287                 ERROR("Failed to allocate %u bytes for integrity chunk buffer",
 288                       INTEGRITY_CHUNK_SIZE);
 289                 ret = WIMLIB_ERR_NOMEM;
 290                 goto err2;
 291         }
 292
 293         bytes_remaining = bytes_to_check;
 294
 295         DEBUG("Bytes to check = %"PRIu64, bytes_to_check);
 296
 297         while (bytes_remaining != 0) {
 298
 299                 uint percent_done = (bytes_to_check - bytes_remaining) *
 300                                     100 / bytes_to_check;
 301
 302                 if (show_progress) {
 303                         printf("Calculating integrity checksums for WIM "
 304                                         "(%"PRIu64" bytes remaining, %u%% "
 305                                         "done)      \r",
 306                                         bytes_remaining, percent_done);
 307                         fflush(stdout);
 308                 }
 309
 310
 311                 size_t bytes_to_read = min(INTEGRITY_CHUNK_SIZE, bytes_remaining);
 312                 size_t bytes_read = fread(chunk_buf, 1, bytes_to_read, out);
 313                 if (bytes_read != bytes_to_read) {
 314                         if (feof(out)) {
 315                                 ERROR("Unexpected EOF while calculating "
 316                                       "integrity checksums");
 317                         } else {
 318                                 ERROR_WITH_ERRNO("File stream error while "
 319                                                  "calculating integrity "
 320                                                  "checksums");
 321                         }
 322                         ret = WIMLIB_ERR_READ;
 323                         goto err2;
 324                 }
 325                 sha1_buffer(chunk_buf, bytes_read, p);
 326                 p += SHA1_HASH_SIZE;
 327                 bytes_remaining -= bytes_read;
 328         }
 329         if (show_progress)
 330                 puts("Calculating integrity checksums for WIM "
 331                                 "(0 bytes remaining, 100% done)"
 332                                 "                       ");
 333
 334         if (fseeko(out, 0, SEEK_END) != 0) {
 335                 ERROR_WITH_ERRNO("Failed to seek to end of WIM to write "
 336                                  "integrity table");
 337                 ret = WIMLIB_ERR_WRITE;
 338                 goto err1;
 339         }
 340
 341         if (fwrite(buf, 1, integrity_table_size, out) != integrity_table_size) {
 342                 ERROR_WITH_ERRNO("Failed to write integrity table to end of "
 343                                  "WIM");
 344                 ret = WIMLIB_ERR_WRITE;
 345                 goto err1;
 346         }
 347         ret = 0;
 348 err1:
 349         FREE(chunk_buf);
 350 err2:
 351         FREE(buf);
 352         return ret;
 353 }