contrib/xz/src/liblzma/common/index_hash.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       index_hash.c
   4 /// \brief      Validates Index by using a hash function
   5 //
   6 //  Author:     Lasse Collin
   7 //
   8 //  This file has been put into the public domain.
   9 //  You can do whatever you want with this file.
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #include "common.h"
  14 #include "index.h"
  15 #include "check.h"
  16
  17
  18 typedef struct {
  19         /// Sum of the Block sizes (including Block Padding)
  20         lzma_vli blocks_size;
  21
  22         /// Sum of the Uncompressed Size fields
  23         lzma_vli uncompressed_size;
  24
  25         /// Number of Records
  26         lzma_vli count;
  27
  28         /// Size of the List of Index Records as bytes
  29         lzma_vli index_list_size;
  30
  31         /// Check calculated from Unpadded Sizes and Uncompressed Sizes.
  32         lzma_check_state check;
  33
  34 } lzma_index_hash_info;
  35
  36
  37 struct lzma_index_hash_s {
  38         enum {
  39                 SEQ_BLOCK,
  40                 SEQ_COUNT,
  41                 SEQ_UNPADDED,
  42                 SEQ_UNCOMPRESSED,
  43                 SEQ_PADDING_INIT,
  44                 SEQ_PADDING,
  45                 SEQ_CRC32,
  46         } sequence;
  47
  48         /// Information collected while decoding the actual Blocks.
  49         lzma_index_hash_info blocks;
  50
  51         /// Information collected from the Index field.
  52         lzma_index_hash_info records;
  53
  54         /// Number of Records not fully decoded
  55         lzma_vli remaining;
  56
  57         /// Unpadded Size currently being read from an Index Record.
  58         lzma_vli unpadded_size;
  59
  60         /// Uncompressed Size currently being read from an Index Record.
  61         lzma_vli uncompressed_size;
  62
  63         /// Position in variable-length integers when decoding them from
  64         /// the List of Records.
  65         size_t pos;
  66
  67         /// CRC32 of the Index
  68         uint32_t crc32;
  69 };
  70
  71
  72 extern LZMA_API(lzma_index_hash *)
  73 lzma_index_hash_init(lzma_index_hash *index_hash, lzma_allocator *allocator)
  74 {
  75         if (index_hash == NULL) {
  76                 index_hash = lzma_alloc(sizeof(lzma_index_hash), allocator);
  77                 if (index_hash == NULL)
  78                         return NULL;
  79         }
  80
  81         index_hash->sequence = SEQ_BLOCK;
  82         index_hash->blocks.blocks_size = 0;
  83         index_hash->blocks.uncompressed_size = 0;
  84         index_hash->blocks.count = 0;
  85         index_hash->blocks.index_list_size = 0;
  86         index_hash->records.blocks_size = 0;
  87         index_hash->records.uncompressed_size = 0;
  88         index_hash->records.count = 0;
  89         index_hash->records.index_list_size = 0;
  90         index_hash->unpadded_size = 0;
  91         index_hash->uncompressed_size = 0;
  92         index_hash->pos = 0;
  93         index_hash->crc32 = 0;
  94
  95         // These cannot fail because LZMA_CHECK_BEST is known to be supported.
  96         (void)lzma_check_init(&index_hash->blocks.check, LZMA_CHECK_BEST);
  97         (void)lzma_check_init(&index_hash->records.check, LZMA_CHECK_BEST);
  98
  99         return index_hash;
 100 }
 101
 102
 103 extern LZMA_API(void)
 104 lzma_index_hash_end(lzma_index_hash *index_hash, lzma_allocator *allocator)
 105 {
 106         lzma_free(index_hash, allocator);
 107         return;
 108 }
 109
 110
 111 extern LZMA_API(lzma_vli)
 112 lzma_index_hash_size(const lzma_index_hash *index_hash)
 113 {
 114         // Get the size of the Index from ->blocks instead of ->records for
 115         // cases where application wants to know the Index Size before
 116         // decoding the Index.
 117         return index_size(index_hash->blocks.count,
 118                         index_hash->blocks.index_list_size);
 119 }
 120
 121
 122 /// Updates the sizes and the hash without any validation.
 123 static lzma_ret
 124 hash_append(lzma_index_hash_info *info, lzma_vli unpadded_size,
 125                 lzma_vli uncompressed_size)
 126 {
 127         info->blocks_size += vli_ceil4(unpadded_size);
 128         info->uncompressed_size += uncompressed_size;
 129         info->index_list_size += lzma_vli_size(unpadded_size)
 130                         + lzma_vli_size(uncompressed_size);
 131         ++info->count;
 132
 133         const lzma_vli sizes[2] = { unpadded_size, uncompressed_size };
 134         lzma_check_update(&info->check, LZMA_CHECK_BEST,
 135                         (const uint8_t *)(sizes), sizeof(sizes));
 136
 137         return LZMA_OK;
 138 }
 139
 140
 141 extern LZMA_API(lzma_ret)
 142 lzma_index_hash_append(lzma_index_hash *index_hash, lzma_vli unpadded_size,
 143                 lzma_vli uncompressed_size)
 144 {
 145         // Validate the arguments.
 146         if (index_hash->sequence != SEQ_BLOCK
 147                         || unpadded_size < UNPADDED_SIZE_MIN
 148                         || unpadded_size > UNPADDED_SIZE_MAX
 149                         || uncompressed_size > LZMA_VLI_MAX)
 150                 return LZMA_PROG_ERROR;
 151
 152         // Update the hash.
 153         return_if_error(hash_append(&index_hash->blocks,
 154                         unpadded_size, uncompressed_size));
 155
 156         // Validate the properties of *info are still in allowed limits.
 157         if (index_hash->blocks.blocks_size > LZMA_VLI_MAX
 158                         || index_hash->blocks.uncompressed_size > LZMA_VLI_MAX
 159                         || index_size(index_hash->blocks.count,
 160                                         index_hash->blocks.index_list_size)
 161                                 > LZMA_BACKWARD_SIZE_MAX
 162                         || index_stream_size(index_hash->blocks.blocks_size,
 163                                         index_hash->blocks.count,
 164                                         index_hash->blocks.index_list_size)
 165                                 > LZMA_VLI_MAX)
 166                 return LZMA_DATA_ERROR;
 167
 168         return LZMA_OK;
 169 }
 170
 171
 172 extern LZMA_API(lzma_ret)
 173 lzma_index_hash_decode(lzma_index_hash *index_hash, const uint8_t *in,
 174                 size_t *in_pos, size_t in_size)
 175 {
 176         // Catch zero input buffer here, because in contrast to Index encoder
 177         // and decoder functions, applications call this function directly
 178         // instead of via lzma_code(), which does the buffer checking.
 179         if (*in_pos >= in_size)
 180                 return LZMA_BUF_ERROR;
 181
 182         // NOTE: This function has many similarities to index_encode() and
 183         // index_decode() functions found from index_encoder.c and
 184         // index_decoder.c. See the comments especially in index_encoder.c.
 185         const size_t in_start = *in_pos;
 186         lzma_ret ret = LZMA_OK;
 187
 188         while (*in_pos < in_size)
 189         switch (index_hash->sequence) {
 190         case SEQ_BLOCK:
 191                 // Check the Index Indicator is present.
 192                 if (in[(*in_pos)++] != 0x00)
 193                         return LZMA_DATA_ERROR;
 194
 195                 index_hash->sequence = SEQ_COUNT;
 196                 break;
 197
 198         case SEQ_COUNT: {
 199                 ret = lzma_vli_decode(&index_hash->remaining,
 200                                 &index_hash->pos, in, in_pos, in_size);
 201                 if (ret != LZMA_STREAM_END)
 202                         goto out;
 203
 204                 // The count must match the count of the Blocks decoded.
 205                 if (index_hash->remaining != index_hash->blocks.count)
 206                         return LZMA_DATA_ERROR;
 207
 208                 ret = LZMA_OK;
 209                 index_hash->pos = 0;
 210
 211                 // Handle the special case when there are no Blocks.
 212                 index_hash->sequence = index_hash->remaining == 0
 213                                 ? SEQ_PADDING_INIT : SEQ_UNPADDED;
 214                 break;
 215         }
 216
 217         case SEQ_UNPADDED:
 218         case SEQ_UNCOMPRESSED: {
 219                 lzma_vli *size = index_hash->sequence == SEQ_UNPADDED
 220                                 ? &index_hash->unpadded_size
 221                                 : &index_hash->uncompressed_size;
 222
 223                 ret = lzma_vli_decode(size, &index_hash->pos,
 224                                 in, in_pos, in_size);
 225                 if (ret != LZMA_STREAM_END)
 226                         goto out;
 227
 228                 ret = LZMA_OK;
 229                 index_hash->pos = 0;
 230
 231                 if (index_hash->sequence == SEQ_UNPADDED) {
 232                         if (index_hash->unpadded_size < UNPADDED_SIZE_MIN
 233                                         || index_hash->unpadded_size
 234                                                 > UNPADDED_SIZE_MAX)
 235                                 return LZMA_DATA_ERROR;
 236
 237                         index_hash->sequence = SEQ_UNCOMPRESSED;
 238                 } else {
 239                         // Update the hash.
 240                         return_if_error(hash_append(&index_hash->records,
 241                                         index_hash->unpadded_size,
 242                                         index_hash->uncompressed_size));
 243
 244                         // Verify that we don't go over the known sizes. Note
 245                         // that this validation is simpler than the one used
 246                         // in lzma_index_hash_append(), because here we know
 247                         // that values in index_hash->blocks are already
 248                         // validated and we are fine as long as we don't
 249                         // exceed them in index_hash->records.
 250                         if (index_hash->blocks.blocks_size
 251                                         < index_hash->records.blocks_size
 252                                         || index_hash->blocks.uncompressed_size
 253                                         < index_hash->records.uncompressed_size
 254                                         || index_hash->blocks.index_list_size
 255                                         < index_hash->records.index_list_size)
 256                                 return LZMA_DATA_ERROR;
 257
 258                         // Check if this was the last Record.
 259                         index_hash->sequence = --index_hash->remaining == 0
 260                                         ? SEQ_PADDING_INIT : SEQ_UNPADDED;
 261                 }
 262
 263                 break;
 264         }
 265
 266         case SEQ_PADDING_INIT:
 267                 index_hash->pos = (LZMA_VLI_C(4) - index_size_unpadded(
 268                                 index_hash->records.count,
 269                                 index_hash->records.index_list_size)) & 3;
 270                 index_hash->sequence = SEQ_PADDING;
 271
 272         // Fall through
 273
 274         case SEQ_PADDING:
 275                 if (index_hash->pos > 0) {
 276                         --index_hash->pos;
 277                         if (in[(*in_pos)++] != 0x00)
 278                                 return LZMA_DATA_ERROR;
 279
 280                         break;
 281                 }
 282
 283                 // Compare the sizes.
 284                 if (index_hash->blocks.blocks_size
 285                                 != index_hash->records.blocks_size
 286                                 || index_hash->blocks.uncompressed_size
 287                                 != index_hash->records.uncompressed_size
 288                                 || index_hash->blocks.index_list_size
 289                                 != index_hash->records.index_list_size)
 290                         return LZMA_DATA_ERROR;
 291
 292                 // Finish the hashes and compare them.
 293                 lzma_check_finish(&index_hash->blocks.check, LZMA_CHECK_BEST);
 294                 lzma_check_finish(&index_hash->records.check, LZMA_CHECK_BEST);
 295                 if (memcmp(index_hash->blocks.check.buffer.u8,
 296                                 index_hash->records.check.buffer.u8,
 297                                 lzma_check_size(LZMA_CHECK_BEST)) != 0)
 298                         return LZMA_DATA_ERROR;
 299
 300                 // Finish the CRC32 calculation.
 301                 index_hash->crc32 = lzma_crc32(in + in_start,
 302                                 *in_pos - in_start, index_hash->crc32);
 303
 304                 index_hash->sequence = SEQ_CRC32;
 305
 306         // Fall through
 307
 308         case SEQ_CRC32:
 309                 do {
 310                         if (*in_pos == in_size)
 311                                 return LZMA_OK;
 312
 313                         if (((index_hash->crc32 >> (index_hash->pos * 8))
 314                                         & 0xFF) != in[(*in_pos)++])
 315                                 return LZMA_DATA_ERROR;
 316
 317                 } while (++index_hash->pos < 4);
 318
 319                 return LZMA_STREAM_END;
 320
 321         default:
 322                 assert(0);
 323                 return LZMA_PROG_ERROR;
 324         }
 325
 326 out:
 327         // Update the CRC32,
 328         index_hash->crc32 = lzma_crc32(in + in_start,
 329                         *in_pos - in_start, index_hash->crc32);
 330
 331         return ret;
 332 }