src/liblzma/common/index_hash.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       index_hash.c
   4 /// \brief      Validates Index by using a hash function
   5 //
   6 //  Copyright (C) 2008 Lasse Collin
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2.1 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include "common.h"
  21 #include "index.h"
  22 #include "check.h"
  23
  24
  25 typedef struct {
  26         /// Sum of the Total Size fields
  27         lzma_vli total_size;
  28
  29         /// Sum of the Uncompressed Size fields
  30         lzma_vli uncompressed_size;
  31
  32         /// Number of Records
  33         lzma_vli count;
  34
  35         /// Size of the List of Index Records as bytes
  36         lzma_vli index_list_size;
  37
  38         /// Check calculated from Total Sizes and Uncompressed Sizes.
  39         lzma_check check;
  40
  41 } lzma_index_hash_info;
  42
  43
  44 struct lzma_index_hash_s {
  45         enum {
  46                 SEQ_BLOCK,
  47                 SEQ_COUNT,
  48                 SEQ_TOTAL,
  49                 SEQ_UNCOMPRESSED,
  50                 SEQ_PADDING_INIT,
  51                 SEQ_PADDING,
  52                 SEQ_CRC32,
  53         } sequence;
  54
  55         /// Information collected while decoding the actual Blocks.
  56         lzma_index_hash_info blocks;
  57
  58         /// Information collected from the Index field.
  59         lzma_index_hash_info records;
  60
  61         /// Number of Records not fully decoded
  62         lzma_vli remaining;
  63
  64         /// Total Size currently being read from an Index Record.
  65         lzma_vli total_size;
  66
  67         /// Uncompressed Size currently being read from an Index Record.
  68         lzma_vli uncompressed_size;
  69
  70         /// Position in variable-length integers when decoding them from
  71         /// the List of Records.
  72         size_t pos;
  73
  74         /// CRC32 of the Index
  75         uint32_t crc32;
  76 };
  77
  78
  79 extern LZMA_API lzma_index_hash *
  80 lzma_index_hash_init(lzma_index_hash *index_hash, lzma_allocator *allocator)
  81 {
  82         if (index_hash == NULL) {
  83                 index_hash = lzma_alloc(sizeof(lzma_index_hash), allocator);
  84                 if (index_hash == NULL)
  85                         return NULL;
  86         }
  87
  88         index_hash->sequence = SEQ_BLOCK;
  89         index_hash->blocks.total_size = 0;
  90         index_hash->blocks.uncompressed_size = 0;
  91         index_hash->blocks.count = 0;
  92         index_hash->blocks.index_list_size = 0;
  93         index_hash->records.total_size = 0;
  94         index_hash->records.uncompressed_size = 0;
  95         index_hash->records.count = 0;
  96         index_hash->records.index_list_size = 0;
  97         index_hash->total_size = 0;
  98         index_hash->uncompressed_size = 0;
  99         index_hash->pos = 0;
 100         index_hash->crc32 = 0;
 101
 102         // These cannot fail because LZMA_CHECK_BEST is known to be supported.
 103         (void)lzma_check_init(&index_hash->blocks.check, LZMA_CHECK_BEST);
 104         (void)lzma_check_init(&index_hash->records.check, LZMA_CHECK_BEST);
 105
 106         return index_hash;
 107 }
 108
 109
 110 extern LZMA_API void
 111 lzma_index_hash_end(lzma_index_hash *index_hash, lzma_allocator *allocator)
 112 {
 113         lzma_free(index_hash, allocator);
 114         return;
 115 }
 116
 117
 118 extern LZMA_API lzma_vli
 119 lzma_index_hash_size(const lzma_index_hash *index_hash)
 120 {
 121         // Get the size of the Index from ->blocks instead of ->records for
 122         // cases where application wants to know the Index Size before
 123         // decoding the Index.
 124         return index_size(index_hash->blocks.count,
 125                         index_hash->blocks.index_list_size);
 126 }
 127
 128
 129 /// Updates the sizes and the hash without any validation.
 130 static lzma_ret
 131 hash_append(lzma_index_hash_info *info, lzma_vli total_size,
 132                 lzma_vli uncompressed_size)
 133 {
 134         info->total_size += total_size;
 135         info->uncompressed_size += uncompressed_size;
 136         info->index_list_size += lzma_vli_size(total_size_encode(total_size))
 137                         + lzma_vli_size(uncompressed_size);
 138         ++info->count;
 139
 140         const lzma_vli sizes[2] = { total_size, uncompressed_size };
 141         lzma_check_update(&info->check, LZMA_CHECK_BEST,
 142                         (const uint8_t *)(sizes), sizeof(sizes));
 143
 144         return LZMA_OK;
 145 }
 146
 147
 148 extern LZMA_API lzma_ret
 149 lzma_index_hash_append(lzma_index_hash *index_hash, lzma_vli total_size,
 150                 lzma_vli uncompressed_size)
 151 {
 152         // Validate the arguments.
 153         if (index_hash->sequence != SEQ_BLOCK || total_size == 0 ||
 154                         total_size > LZMA_VLI_VALUE_MAX || (total_size & 3)
 155                         || uncompressed_size > LZMA_VLI_VALUE_MAX)
 156                 return LZMA_PROG_ERROR;
 157
 158         // Update the hash.
 159         return_if_error(hash_append(&index_hash->blocks,
 160                         total_size, uncompressed_size));
 161
 162         // Validate the properties of *info are still in allowed limits.
 163         if (index_hash->blocks.total_size > LZMA_VLI_VALUE_MAX
 164                         || index_hash->blocks.uncompressed_size
 165                                 > LZMA_VLI_VALUE_MAX
 166                         || index_size(index_hash->blocks.count,
 167                                         index_hash->blocks.index_list_size)
 168                                 > LZMA_BACKWARD_SIZE_MAX
 169                         || index_stream_size(index_hash->blocks.total_size,
 170                                         index_hash->blocks.count,
 171                                         index_hash->blocks.index_list_size)
 172                                 > LZMA_VLI_VALUE_MAX)
 173                 return LZMA_DATA_ERROR;
 174
 175         return LZMA_OK;
 176 }
 177
 178
 179 extern LZMA_API lzma_ret
 180 lzma_index_hash_decode(lzma_index_hash *index_hash, const uint8_t *in,
 181                 size_t *in_pos, size_t in_size)
 182 {
 183         // Catch zero input buffer here, because in contrast to Index encoder
 184         // and decoder functions, applications call this function directly
 185         // instead of via lzma_code(), which does the buffer checking.
 186         if (*in_pos >= in_size)
 187                 return LZMA_BUF_ERROR;
 188
 189         // NOTE: This function has many similarities to index_encode() and
 190         // index_decode() functions found from index_encoder.c and
 191         // index_decoder.c. See the comments especially in index_encoder.c.
 192         const size_t in_start = *in_pos;
 193         lzma_ret ret = LZMA_OK;
 194
 195         while (*in_pos < in_size)
 196         switch (index_hash->sequence) {
 197         case SEQ_BLOCK:
 198                 // Check the Index Indicator is present.
 199                 if (in[(*in_pos)++] != 0x00)
 200                         return LZMA_DATA_ERROR;
 201
 202                 index_hash->sequence = SEQ_COUNT;
 203                 break;
 204
 205         case SEQ_COUNT: {
 206                 ret = lzma_vli_decode(&index_hash->remaining,
 207                                 &index_hash->pos, in, in_pos, in_size);
 208                 if (ret != LZMA_STREAM_END)
 209                         goto out;
 210
 211                 // The count must match the count of the Blocks decoded.
 212                 if (index_hash->remaining != index_hash->blocks.count)
 213                         return LZMA_DATA_ERROR;
 214
 215                 ret = LZMA_OK;
 216                 index_hash->pos = 0;
 217
 218                 // Handle the special case when there are no Blocks.
 219                 index_hash->sequence = index_hash->remaining == 0
 220                                 ? SEQ_PADDING_INIT : SEQ_TOTAL;
 221                 break;
 222         }
 223
 224         case SEQ_TOTAL:
 225         case SEQ_UNCOMPRESSED: {
 226                 lzma_vli *size = index_hash->sequence == SEQ_TOTAL
 227                                 ? &index_hash->total_size
 228                                 : &index_hash->uncompressed_size;
 229
 230                 ret = lzma_vli_decode(size, &index_hash->pos,
 231                                 in, in_pos, in_size);
 232                 if (ret != LZMA_STREAM_END)
 233                         goto out;
 234
 235                 ret = LZMA_OK;
 236                 index_hash->pos = 0;
 237
 238                 if (index_hash->sequence == SEQ_TOTAL) {
 239                         if (index_hash->total_size > TOTAL_SIZE_ENCODED_MAX)
 240                                 return LZMA_DATA_ERROR;
 241
 242                         index_hash->total_size = total_size_decode(
 243                                         index_hash->total_size);
 244
 245                         index_hash->sequence = SEQ_UNCOMPRESSED;
 246                 } else {
 247                         // Update the hash.
 248                         return_if_error(hash_append(&index_hash->records,
 249                                         index_hash->total_size,
 250                                         index_hash->uncompressed_size));
 251
 252                         // Verify that we don't go over the known sizes. Note
 253                         // that this validation is simpler than the one used
 254                         // in lzma_index_hash_append(), because here we know
 255                         // that values in index_hash->blocks are already
 256                         // validated and we are fine as long as we don't
 257                         // exceed them in index_hash->records.
 258                         if (index_hash->blocks.total_size
 259                                         < index_hash->records.total_size
 260                                         || index_hash->blocks.uncompressed_size
 261                                         < index_hash->records.uncompressed_size
 262                                         || index_hash->blocks.index_list_size
 263                                         < index_hash->records.index_list_size)
 264                                 return LZMA_DATA_ERROR;
 265
 266                         // Check if this was the last Record.
 267                         index_hash->sequence = --index_hash->remaining == 0
 268                                         ? SEQ_PADDING_INIT : SEQ_TOTAL;
 269                 }
 270
 271                 break;
 272         }
 273
 274         case SEQ_PADDING_INIT:
 275                 index_hash->pos = (LZMA_VLI_C(4) - index_size_unpadded(
 276                                 index_hash->records.count,
 277                                 index_hash->records.index_list_size)) & 3;
 278                 index_hash->sequence = SEQ_PADDING;
 279
 280         // Fall through
 281
 282         case SEQ_PADDING:
 283                 if (index_hash->pos > 0) {
 284                         --index_hash->pos;
 285                         if (in[(*in_pos)++] != 0x00)
 286                                 return LZMA_DATA_ERROR;
 287
 288                         break;
 289                 }
 290
 291                 // Compare the sizes.
 292                 if (index_hash->blocks.total_size
 293                                 != index_hash->records.total_size
 294                                 || index_hash->blocks.uncompressed_size
 295                                 != index_hash->records.uncompressed_size
 296                                 || index_hash->blocks.index_list_size
 297                                 != index_hash->records.index_list_size)
 298                         return LZMA_DATA_ERROR;
 299
 300                 // Finish the hashes and compare them.
 301                 lzma_check_finish(&index_hash->blocks.check, LZMA_CHECK_BEST);
 302                 lzma_check_finish(&index_hash->records.check, LZMA_CHECK_BEST);
 303                 if (memcmp(index_hash->blocks.check.buffer,
 304                                 index_hash->records.check.buffer,
 305                                 lzma_check_sizes[LZMA_CHECK_BEST]) != 0)
 306                         return LZMA_DATA_ERROR;
 307
 308                 // Finish the CRC32 calculation.
 309                 index_hash->crc32 = lzma_crc32(in + in_start,
 310                                 *in_pos - in_start, index_hash->crc32);
 311
 312                 index_hash->sequence = SEQ_CRC32;
 313
 314         // Fall through
 315
 316         case SEQ_CRC32:
 317                 do {
 318                         if (*in_pos == in_size)
 319                                 return LZMA_OK;
 320
 321                         if (((index_hash->crc32 >> (index_hash->pos * 8))
 322                                         & 0xFF) != in[(*in_pos)++])
 323                                 return LZMA_DATA_ERROR;
 324
 325                 } while (++index_hash->pos < 4);
 326
 327                 return LZMA_STREAM_END;
 328
 329         default:
 330                 assert(0);
 331                 return LZMA_PROG_ERROR;
 332         }
 333
 334 out:
 335         // Update the CRC32,
 336         index_hash->crc32 = lzma_crc32(in + in_start,
 337                         *in_pos - in_start, index_hash->crc32);
 338
 339         return ret;
 340 }