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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[WIM_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 "
  62                                 "chunks\n", 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!\n");
  80                         } else {
  81                                 ERROR("File stream error while verifying "
  82                                                 "integrity of WIM: %m\n");
  83                         }
  84                         ret = WIMLIB_ERR_READ;
  85                         goto verify_integrity_error;
  86                 }
  87                 sha1_buffer(chunk_buf, bytes_to_read, resblock);
  88                 if (memcmp(resblock, sha1sums, WIM_HASH_SIZE) != 0) {
  89                         *status = WIM_INTEGRITY_NOT_OK;
  90                         goto verify_integrity_done;
  91                 }
  92                 sha1sums += WIM_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.\n");
 135                 *status = WIM_INTEGRITY_NONEXISTENT;
 136                 return 0;
 137         }
 138         ctype = wim_resource_compression_type(w, res_entry);
 139         if (res_entry->original_size < 12) {
 140                 ERROR("Integrity table resource is too short!\n");
 141                 return WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 142         }
 143
 144         /* Read the integrity table into memory. */
 145         buf = MALLOC(res_entry->original_size);
 146         if (!buf) {
 147                 ERROR("Out of memory (needed %zu bytes for integrity table)!\n",
 148                                                 res_entry->original_size);
 149                 ret = WIMLIB_ERR_NOMEM;
 150                 goto check_integrity_error;
 151         }
 152         ret = read_full_resource(w->fp, res_entry->size, res_entry->original_size,
 153                                  res_entry->offset, ctype, buf);
 154         if (ret != 0) {
 155                 ERROR("Failed to read integrity table (size = %"PRIu64", "
 156                                 "original_size = %"PRIu64", offset = "
 157                                 "%"PRIu64", ctype = %d\n",
 158                                 (u64)res_entry->size, res_entry->original_size,
 159                                 res_entry->offset, ctype);
 160                 goto check_integrity_error;
 161         }
 162
 163         p = get_u32(buf, &integrity_table_size);
 164         p = get_u32(p, &num_entries);
 165         p = get_u32(p, &chunk_size);
 166
 167         /* p now points to the array of SHA1 message digests for the WIM. */
 168
 169         /* Make sure the integrity table is the right size. */
 170         if (integrity_table_size != res_entry->original_size) {
 171                 ERROR("Inconsistent integrity table sizes: header says %u "
 172                                 "bytes but resource entry says "
 173                                 "%"PRIu64" bytes\n", integrity_table_size,
 174                                 res_entry->original_size);
 175
 176                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 177                 goto check_integrity_error;
 178         }
 179
 180         DEBUG("integrity_table_size = %u, num_entries = %u, chunk_size = %u\n",
 181                         integrity_table_size, num_entries, chunk_size);
 182
 183
 184         expected_size = num_entries * WIM_HASH_SIZE + 12;
 185
 186         if (integrity_table_size != expected_size) {
 187                 ERROR("Integrity table is %u bytes, but expected %"PRIu64" "
 188                                 "bytes to hold %u entries!\n",
 189                                 integrity_table_size,
 190                                 expected_size, num_entries);
 191                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 192                 goto check_integrity_error;
 193         }
 194
 195         end_lookup_table_offset = w->hdr.lookup_table_res_entry.offset +
 196                                   w->hdr.lookup_table_res_entry.size;
 197
 198         bytes_to_check = end_lookup_table_offset - WIM_HEADER_DISK_SIZE;
 199
 200         expected_num_entries = bytes_to_check / chunk_size +
 201                                (bytes_to_check % chunk_size != 0);
 202
 203         if (num_entries != expected_num_entries) {
 204                 ERROR("%"PRIu64 " entries would be required to checksum "
 205                         "the %"PRIu64" bytes from the end of the header to the\n"
 206                         "end of the lookup table with a chunk size of %u, but "
 207                         "there were only %u entries!\n",
 208                         expected_num_entries, bytes_to_check, chunk_size,
 209                         num_entries);
 210                 ret = WIMLIB_ERR_INVALID_INTEGRITY_TABLE;
 211                 goto check_integrity_error;
 212         }
 213
 214         /* The integrity checking starts after the header, so seek to the offset
 215          * in the WIM after the header. */
 216
 217         if (fseeko(w->fp, WIM_HEADER_DISK_SIZE, SEEK_SET) != 0) {
 218                 ERROR("Failed to seek to byte %u of WIM to check "
 219                                 "integrity: %m\n", WIM_HEADER_DISK_SIZE);
 220                 ret = WIMLIB_ERR_READ;
 221                 goto check_integrity_error;
 222         }
 223         /* call verify_integrity(), which does the actual checking of the SHA1
 224          * message digests. */
 225         ret = verify_integrity(w->fp, bytes_to_check, chunk_size, p,
 226                                show_progress, status);
 227 check_integrity_error:
 228         FREE(buf);
 229         return ret;
 230 }
 231
 232 /*
 233  * Writes integrity information to the output stream for a WIM file being
 234  * written.
 235  *
 236  * @end_header_offset is the offset of the byte after the header, which is the
 237  *      beginning of the region that is checksummed.
 238  *
 239  * @end_lookup_table_offset is the offset of the byte after the lookup table,
 240  *      which is the end of the region that is checksummed.
 241  */
 242 int write_integrity_table(FILE *out, u64 end_header_offset,
 243                           u64 end_lookup_table_offset, int show_progress)
 244 {
 245         u64   bytes_to_check;
 246         u64   bytes_remaining;
 247         u8   *buf;
 248         u8   *p;
 249         char *chunk_buf;
 250         u32   num_entries;
 251         u32   integrity_table_size;
 252         int   ret;
 253
 254         DEBUG("Writing integrity table\n");
 255         if (fseeko(out, end_header_offset, SEEK_SET) != 0) {
 256                 ERROR("Failed to seek to byte %"PRIu64" of WIM "
 257                                 "to calculate integrity data: %m\n",
 258                                 end_header_offset);
 259                 return WIMLIB_ERR_WRITE;
 260         }
 261
 262         bytes_to_check = end_lookup_table_offset - end_header_offset;
 263         num_entries = bytes_to_check / INTEGRITY_CHUNK_SIZE +
 264                         (bytes_to_check % INTEGRITY_CHUNK_SIZE != 0);
 265         integrity_table_size = num_entries * WIM_HASH_SIZE + 3 * sizeof(u32);
 266
 267         DEBUG("integrity table size = %u\n", integrity_table_size);
 268
 269
 270         buf = MALLOC(integrity_table_size);
 271         if (!buf) {
 272                 ERROR("Failed to allocate %u bytes for integrity table!\n",
 273                                 integrity_table_size);
 274                 return WIMLIB_ERR_NOMEM;
 275         }
 276
 277         p = put_u32(buf, integrity_table_size);
 278         p = put_u32(p, num_entries);
 279         p = put_u32(p, INTEGRITY_CHUNK_SIZE);
 280
 281         chunk_buf = MALLOC(INTEGRITY_CHUNK_SIZE);
 282         if (!chunk_buf) {
 283                 ERROR("Failed to allocate %u bytes for integrity chunk "
 284                                 "buffer!\n", INTEGRITY_CHUNK_SIZE);
 285                 ret = WIMLIB_ERR_NOMEM;
 286                 goto err2;
 287         }
 288
 289         bytes_remaining = bytes_to_check;
 290
 291         DEBUG("Bytes to check = %"PRIu64"\n", bytes_to_check);
 292
 293         while (bytes_remaining != 0) {
 294
 295                 uint percent_done = (bytes_to_check - bytes_remaining) *
 296                                     100 / bytes_to_check;
 297
 298                 if (show_progress) {
 299                         printf("Calculating integrity checksums for WIM "
 300                                         "(%"PRIu64" bytes remaining, %u%% "
 301                                         "done)      \r",
 302                                         bytes_remaining, percent_done);
 303                         fflush(stdout);
 304                 }
 305
 306
 307                 size_t bytes_to_read = min(INTEGRITY_CHUNK_SIZE, bytes_remaining);
 308                 size_t bytes_read = fread(chunk_buf, 1, bytes_to_read, out);
 309                 if (bytes_read != bytes_to_read) {
 310                         if (feof(out)) {
 311                                 ERROR("Unexpected EOF while calculating "
 312                                                 "integrity checksums!\n");
 313                         } else {
 314                                 ERROR("File stream error while calculating "
 315                                                 "integrity checksums: %m\n");
 316                         }
 317                         ret = WIMLIB_ERR_READ;
 318                         goto err2;
 319                 }
 320                 sha1_buffer(chunk_buf, bytes_read, p);
 321                 p += WIM_HASH_SIZE;
 322                 bytes_remaining -= bytes_read;
 323         }
 324         if (show_progress)
 325                 puts("Calculating integrity checksums for WIM "
 326                                 "(0 bytes remaining, 100% done)"
 327                                 "                       ");
 328
 329         if (fseeko(out, 0, SEEK_END) != 0) {
 330                 ERROR("Failed to seek to end of WIM to write integrity "
 331                                 "table: %m\n");
 332                 ret = WIMLIB_ERR_WRITE;
 333                 goto err1;
 334         }
 335
 336         if (fwrite(buf, 1, integrity_table_size, out) != integrity_table_size) {
 337                 ERROR("Failed to write integrity table to end of WIM: %m\n");
 338                 ret = WIMLIB_ERR_WRITE;
 339                 goto err1;
 340         }
 341         ret = 0;
 342 err1:
 343         FREE(chunk_buf);
 344 err2:
 345         FREE(buf);
 346         return ret;
 347 }