block/qcow.c

   1 /*
   2  * Block driver for the QCOW format
   3  *
   4  * Copyright (c) 2004-2006 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "qapi/error.h"
  27 #include "qemu/error-report.h"
  28 #include "block/block_int.h"
  29 #include "block/qdict.h"
  30 #include "sysemu/block-backend.h"
  31 #include "qemu/module.h"
  32 #include "qemu/option.h"
  33 #include "qemu/bswap.h"
  34 #include <zlib.h>
  35 #include "qapi/qmp/qdict.h"
  36 #include "qapi/qmp/qstring.h"
  37 #include "qapi/qobject-input-visitor.h"
  38 #include "qapi/qapi-visit-block-core.h"
  39 #include "crypto/block.h"
  40 #include "migration/blocker.h"
  41 #include "crypto.h"
  42
  43 /**************************************************************/
  44 /* QEMU COW block driver with compression and encryption support */
  45
  46 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  47 #define QCOW_VERSION 1
  48
  49 #define QCOW_CRYPT_NONE 0
  50 #define QCOW_CRYPT_AES  1
  51
  52 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
  53
  54 typedef struct QCowHeader {
  55     uint32_t magic;
  56     uint32_t version;
  57     uint64_t backing_file_offset;
  58     uint32_t backing_file_size;
  59     uint32_t mtime;
  60     uint64_t size; /* in bytes */
  61     uint8_t cluster_bits;
  62     uint8_t l2_bits;
  63     uint16_t padding;
  64     uint32_t crypt_method;
  65     uint64_t l1_table_offset;
  66 } QEMU_PACKED QCowHeader;
  67
  68 #define L2_CACHE_SIZE 16
  69
  70 typedef struct BDRVQcowState {
  71     int cluster_bits;
  72     int cluster_size;
  73     int l2_bits;
  74     int l2_size;
  75     unsigned int l1_size;
  76     uint64_t cluster_offset_mask;
  77     uint64_t l1_table_offset;
  78     uint64_t *l1_table;
  79     uint64_t *l2_cache;
  80     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
  81     uint32_t l2_cache_counts[L2_CACHE_SIZE];
  82     uint8_t *cluster_cache;
  83     uint8_t *cluster_data;
  84     uint64_t cluster_cache_offset;
  85     QCryptoBlock *crypto; /* Disk encryption format driver */
  86     uint32_t crypt_method_header;
  87     CoMutex lock;
  88     Error *migration_blocker;
  89 } BDRVQcowState;
  90
  91 static QemuOptsList qcow_create_opts;
  92
  93 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
  94
  95 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
  96 {
  97     const QCowHeader *cow_header = (const void *)buf;
  98
  99     if (buf_size >= sizeof(QCowHeader) &&
 100         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
 101         be32_to_cpu(cow_header->version) == QCOW_VERSION)
 102         return 100;
 103     else
 104         return 0;
 105 }
 106
 107 static QemuOptsList qcow_runtime_opts = {
 108     .name = "qcow",
 109     .head = QTAILQ_HEAD_INITIALIZER(qcow_runtime_opts.head),
 110     .desc = {
 111         BLOCK_CRYPTO_OPT_DEF_QCOW_KEY_SECRET("encrypt."),
 112         { /* end of list */ }
 113     },
 114 };
 115
 116 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
 117                      Error **errp)
 118 {
 119     BDRVQcowState *s = bs->opaque;
 120     unsigned int len, i, shift;
 121     int ret;
 122     QCowHeader header;
 123     Error *local_err = NULL;
 124     QCryptoBlockOpenOptions *crypto_opts = NULL;
 125     unsigned int cflags = 0;
 126     QDict *encryptopts = NULL;
 127     const char *encryptfmt;
 128
 129     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
 130     encryptfmt = qdict_get_try_str(encryptopts, "format");
 131
 132     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 133                                false, errp);
 134     if (!bs->file) {
 135         ret = -EINVAL;
 136         goto fail;
 137     }
 138
 139     ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
 140     if (ret < 0) {
 141         goto fail;
 142     }
 143     header.magic = be32_to_cpu(header.magic);
 144     header.version = be32_to_cpu(header.version);
 145     header.backing_file_offset = be64_to_cpu(header.backing_file_offset);
 146     header.backing_file_size = be32_to_cpu(header.backing_file_size);
 147     header.mtime = be32_to_cpu(header.mtime);
 148     header.size = be64_to_cpu(header.size);
 149     header.crypt_method = be32_to_cpu(header.crypt_method);
 150     header.l1_table_offset = be64_to_cpu(header.l1_table_offset);
 151
 152     if (header.magic != QCOW_MAGIC) {
 153         error_setg(errp, "Image not in qcow format");
 154         ret = -EINVAL;
 155         goto fail;
 156     }
 157     if (header.version != QCOW_VERSION) {
 158         error_setg(errp, "Unsupported qcow version %" PRIu32, header.version);
 159         ret = -ENOTSUP;
 160         goto fail;
 161     }
 162
 163     if (header.size <= 1) {
 164         error_setg(errp, "Image size is too small (must be at least 2 bytes)");
 165         ret = -EINVAL;
 166         goto fail;
 167     }
 168     if (header.cluster_bits < 9 || header.cluster_bits > 16) {
 169         error_setg(errp, "Cluster size must be between 512 and 64k");
 170         ret = -EINVAL;
 171         goto fail;
 172     }
 173
 174     /* l2_bits specifies number of entries; storing a uint64_t in each entry,
 175      * so bytes = num_entries << 3. */
 176     if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
 177         error_setg(errp, "L2 table size must be between 512 and 64k");
 178         ret = -EINVAL;
 179         goto fail;
 180     }
 181
 182     s->crypt_method_header = header.crypt_method;
 183     if (s->crypt_method_header) {
 184         if (bdrv_uses_whitelist() &&
 185             s->crypt_method_header == QCOW_CRYPT_AES) {
 186             error_setg(errp,
 187                        "Use of AES-CBC encrypted qcow images is no longer "
 188                        "supported in system emulators");
 189             error_append_hint(errp,
 190                               "You can use 'qemu-img convert' to convert your "
 191                               "image to an alternative supported format, such "
 192                               "as unencrypted qcow, or raw with the LUKS "
 193                               "format instead.\n");
 194             ret = -ENOSYS;
 195             goto fail;
 196         }
 197         if (s->crypt_method_header == QCOW_CRYPT_AES) {
 198             if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
 199                 error_setg(errp,
 200                            "Header reported 'aes' encryption format but "
 201                            "options specify '%s'", encryptfmt);
 202                 ret = -EINVAL;
 203                 goto fail;
 204             }
 205             qdict_put_str(encryptopts, "format", "qcow");
 206             crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
 207             if (!crypto_opts) {
 208                 ret = -EINVAL;
 209                 goto fail;
 210             }
 211
 212             if (flags & BDRV_O_NO_IO) {
 213                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 214             }
 215             s->crypto = qcrypto_block_open(crypto_opts, "encrypt.",
 216                                            NULL, NULL, cflags, 1, errp);
 217             if (!s->crypto) {
 218                 ret = -EINVAL;
 219                 goto fail;
 220             }
 221         } else {
 222             error_setg(errp, "invalid encryption method in qcow header");
 223             ret = -EINVAL;
 224             goto fail;
 225         }
 226         bs->encrypted = true;
 227     } else {
 228         if (encryptfmt) {
 229             error_setg(errp, "No encryption in image header, but options "
 230                        "specified format '%s'", encryptfmt);
 231             ret = -EINVAL;
 232             goto fail;
 233         }
 234     }
 235     s->cluster_bits = header.cluster_bits;
 236     s->cluster_size = 1 << s->cluster_bits;
 237     s->l2_bits = header.l2_bits;
 238     s->l2_size = 1 << s->l2_bits;
 239     bs->total_sectors = header.size / 512;
 240     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
 241
 242     /* read the level 1 table */
 243     shift = s->cluster_bits + s->l2_bits;
 244     if (header.size > UINT64_MAX - (1LL << shift)) {
 245         error_setg(errp, "Image too large");
 246         ret = -EINVAL;
 247         goto fail;
 248     } else {
 249         uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
 250         if (l1_size > INT_MAX / sizeof(uint64_t)) {
 251             error_setg(errp, "Image too large");
 252             ret = -EINVAL;
 253             goto fail;
 254         }
 255         s->l1_size = l1_size;
 256     }
 257
 258     s->l1_table_offset = header.l1_table_offset;
 259     s->l1_table = g_try_new(uint64_t, s->l1_size);
 260     if (s->l1_table == NULL) {
 261         error_setg(errp, "Could not allocate memory for L1 table");
 262         ret = -ENOMEM;
 263         goto fail;
 264     }
 265
 266     ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
 267                s->l1_size * sizeof(uint64_t));
 268     if (ret < 0) {
 269         goto fail;
 270     }
 271
 272     for(i = 0;i < s->l1_size; i++) {
 273         s->l1_table[i] = be64_to_cpu(s->l1_table[i]);
 274     }
 275
 276     /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
 277     s->l2_cache =
 278         qemu_try_blockalign(bs->file->bs,
 279                             s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 280     if (s->l2_cache == NULL) {
 281         error_setg(errp, "Could not allocate L2 table cache");
 282         ret = -ENOMEM;
 283         goto fail;
 284     }
 285     s->cluster_cache = g_malloc(s->cluster_size);
 286     s->cluster_data = g_malloc(s->cluster_size);
 287     s->cluster_cache_offset = -1;
 288
 289     /* read the backing file name */
 290     if (header.backing_file_offset != 0) {
 291         len = header.backing_file_size;
 292         if (len > 1023 || len >= sizeof(bs->backing_file)) {
 293             error_setg(errp, "Backing file name too long");
 294             ret = -EINVAL;
 295             goto fail;
 296         }
 297         ret = bdrv_pread(bs->file, header.backing_file_offset,
 298                    bs->backing_file, len);
 299         if (ret < 0) {
 300             goto fail;
 301         }
 302         bs->backing_file[len] = '\0';
 303     }
 304
 305     /* Disable migration when qcow images are used */
 306     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
 307                "does not support live migration",
 308                bdrv_get_device_or_node_name(bs));
 309     ret = migrate_add_blocker(s->migration_blocker, &local_err);
 310     if (local_err) {
 311         error_propagate(errp, local_err);
 312         error_free(s->migration_blocker);
 313         goto fail;
 314     }
 315
 316     qobject_unref(encryptopts);
 317     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
 318     qemu_co_mutex_init(&s->lock);
 319     return 0;
 320
 321  fail:
 322     g_free(s->l1_table);
 323     qemu_vfree(s->l2_cache);
 324     g_free(s->cluster_cache);
 325     g_free(s->cluster_data);
 326     qcrypto_block_free(s->crypto);
 327     qobject_unref(encryptopts);
 328     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
 329     return ret;
 330 }
 331
 332
 333 /* We have nothing to do for QCOW reopen, stubs just return
 334  * success */
 335 static int qcow_reopen_prepare(BDRVReopenState *state,
 336                                BlockReopenQueue *queue, Error **errp)
 337 {
 338     return 0;
 339 }
 340
 341
 342 /* 'allocate' is:
 343  *
 344  * 0 to not allocate.
 345  *
 346  * 1 to allocate a normal cluster (for sector-aligned byte offsets 'n_start'
 347  * to 'n_end' within the cluster)
 348  *
 349  * 2 to allocate a compressed cluster of size
 350  * 'compressed_size'. 'compressed_size' must be > 0 and <
 351  * cluster_size
 352  *
 353  * return 0 if not allocated, 1 if *result is assigned, and negative
 354  * errno on failure.
 355  */
 356 static int get_cluster_offset(BlockDriverState *bs,
 357                               uint64_t offset, int allocate,
 358                               int compressed_size,
 359                               int n_start, int n_end, uint64_t *result)
 360 {
 361     BDRVQcowState *s = bs->opaque;
 362     int min_index, i, j, l1_index, l2_index, ret;
 363     int64_t l2_offset;
 364     uint64_t *l2_table, cluster_offset, tmp;
 365     uint32_t min_count;
 366     int new_l2_table;
 367
 368     *result = 0;
 369     l1_index = offset >> (s->l2_bits + s->cluster_bits);
 370     l2_offset = s->l1_table[l1_index];
 371     new_l2_table = 0;
 372     if (!l2_offset) {
 373         if (!allocate)
 374             return 0;
 375         /* allocate a new l2 entry */
 376         l2_offset = bdrv_getlength(bs->file->bs);
 377         if (l2_offset < 0) {
 378             return l2_offset;
 379         }
 380         /* round to cluster size */
 381         l2_offset = QEMU_ALIGN_UP(l2_offset, s->cluster_size);
 382         /* update the L1 entry */
 383         s->l1_table[l1_index] = l2_offset;
 384         tmp = cpu_to_be64(l2_offset);
 385         BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
 386         ret = bdrv_pwrite_sync(bs->file,
 387                                s->l1_table_offset + l1_index * sizeof(tmp),
 388                                &tmp, sizeof(tmp));
 389         if (ret < 0) {
 390             return ret;
 391         }
 392         new_l2_table = 1;
 393     }
 394     for(i = 0; i < L2_CACHE_SIZE; i++) {
 395         if (l2_offset == s->l2_cache_offsets[i]) {
 396             /* increment the hit count */
 397             if (++s->l2_cache_counts[i] == 0xffffffff) {
 398                 for(j = 0; j < L2_CACHE_SIZE; j++) {
 399                     s->l2_cache_counts[j] >>= 1;
 400                 }
 401             }
 402             l2_table = s->l2_cache + (i << s->l2_bits);
 403             goto found;
 404         }
 405     }
 406     /* not found: load a new entry in the least used one */
 407     min_index = 0;
 408     min_count = 0xffffffff;
 409     for(i = 0; i < L2_CACHE_SIZE; i++) {
 410         if (s->l2_cache_counts[i] < min_count) {
 411             min_count = s->l2_cache_counts[i];
 412             min_index = i;
 413         }
 414     }
 415     l2_table = s->l2_cache + (min_index << s->l2_bits);
 416     BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
 417     if (new_l2_table) {
 418         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
 419         ret = bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
 420                                s->l2_size * sizeof(uint64_t));
 421         if (ret < 0) {
 422             return ret;
 423         }
 424     } else {
 425         ret = bdrv_pread(bs->file, l2_offset, l2_table,
 426                          s->l2_size * sizeof(uint64_t));
 427         if (ret < 0) {
 428             return ret;
 429         }
 430     }
 431     s->l2_cache_offsets[min_index] = l2_offset;
 432     s->l2_cache_counts[min_index] = 1;
 433  found:
 434     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 435     cluster_offset = be64_to_cpu(l2_table[l2_index]);
 436     if (!cluster_offset ||
 437         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
 438         if (!allocate)
 439             return 0;
 440         BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
 441         assert(QEMU_IS_ALIGNED(n_start | n_end, BDRV_SECTOR_SIZE));
 442         /* allocate a new cluster */
 443         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
 444             (n_end - n_start) < s->cluster_size) {
 445             /* if the cluster is already compressed, we must
 446                decompress it in the case it is not completely
 447                overwritten */
 448             if (decompress_cluster(bs, cluster_offset) < 0) {
 449                 return -EIO;
 450             }
 451             cluster_offset = bdrv_getlength(bs->file->bs);
 452             if ((int64_t) cluster_offset < 0) {
 453                 return cluster_offset;
 454             }
 455             cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
 456             /* write the cluster content */
 457             BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
 458             ret = bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
 459                               s->cluster_size);
 460             if (ret < 0) {
 461                 return ret;
 462             }
 463         } else {
 464             cluster_offset = bdrv_getlength(bs->file->bs);
 465             if ((int64_t) cluster_offset < 0) {
 466                 return cluster_offset;
 467             }
 468             if (allocate == 1) {
 469                 /* round to cluster size */
 470                 cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
 471                 if (cluster_offset + s->cluster_size > INT64_MAX) {
 472                     return -E2BIG;
 473                 }
 474                 ret = bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
 475                                     PREALLOC_MODE_OFF, NULL);
 476                 if (ret < 0) {
 477                     return ret;
 478                 }
 479                 /* if encrypted, we must initialize the cluster
 480                    content which won't be written */
 481                 if (bs->encrypted &&
 482                     (n_end - n_start) < s->cluster_size) {
 483                     uint64_t start_offset;
 484                     assert(s->crypto);
 485                     start_offset = offset & ~(s->cluster_size - 1);
 486                     for (i = 0; i < s->cluster_size; i += BDRV_SECTOR_SIZE) {
 487                         if (i < n_start || i >= n_end) {
 488                             memset(s->cluster_data, 0x00, BDRV_SECTOR_SIZE);
 489                             if (qcrypto_block_encrypt(s->crypto,
 490                                                       start_offset + i,
 491                                                       s->cluster_data,
 492                                                       BDRV_SECTOR_SIZE,
 493                                                       NULL) < 0) {
 494                                 return -EIO;
 495                             }
 496                             BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
 497                             ret = bdrv_pwrite(bs->file,
 498                                               cluster_offset + i,
 499                                               s->cluster_data,
 500                                               BDRV_SECTOR_SIZE);
 501                             if (ret < 0) {
 502                                 return ret;
 503                             }
 504                         }
 505                     }
 506                 }
 507             } else if (allocate == 2) {
 508                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
 509                     (uint64_t)compressed_size << (63 - s->cluster_bits);
 510             }
 511         }
 512         /* update L2 table */
 513         tmp = cpu_to_be64(cluster_offset);
 514         l2_table[l2_index] = tmp;
 515         if (allocate == 2) {
 516             BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
 517         } else {
 518             BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
 519         }
 520         ret = bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
 521                                &tmp, sizeof(tmp));
 522         if (ret < 0) {
 523             return ret;
 524         }
 525     }
 526     *result = cluster_offset;
 527     return 1;
 528 }
 529
 530 static int coroutine_fn qcow_co_block_status(BlockDriverState *bs,
 531                                              bool want_zero,
 532                                              int64_t offset, int64_t bytes,
 533                                              int64_t *pnum, int64_t *map,
 534                                              BlockDriverState **file)
 535 {
 536     BDRVQcowState *s = bs->opaque;
 537     int index_in_cluster, ret;
 538     int64_t n;
 539     uint64_t cluster_offset;
 540
 541     qemu_co_mutex_lock(&s->lock);
 542     ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
 543     qemu_co_mutex_unlock(&s->lock);
 544     if (ret < 0) {
 545         return ret;
 546     }
 547     index_in_cluster = offset & (s->cluster_size - 1);
 548     n = s->cluster_size - index_in_cluster;
 549     if (n > bytes) {
 550         n = bytes;
 551     }
 552     *pnum = n;
 553     if (!cluster_offset) {
 554         return 0;
 555     }
 556     if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->crypto) {
 557         return BDRV_BLOCK_DATA;
 558     }
 559     *map = cluster_offset | index_in_cluster;
 560     *file = bs->file->bs;
 561     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
 562 }
 563
 564 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 565                              const uint8_t *buf, int buf_size)
 566 {
 567     z_stream strm1, *strm = &strm1;
 568     int ret, out_len;
 569
 570     memset(strm, 0, sizeof(*strm));
 571
 572     strm->next_in = (uint8_t *)buf;
 573     strm->avail_in = buf_size;
 574     strm->next_out = out_buf;
 575     strm->avail_out = out_buf_size;
 576
 577     ret = inflateInit2(strm, -12);
 578     if (ret != Z_OK)
 579         return -1;
 580     ret = inflate(strm, Z_FINISH);
 581     out_len = strm->next_out - out_buf;
 582     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 583         out_len != out_buf_size) {
 584         inflateEnd(strm);
 585         return -1;
 586     }
 587     inflateEnd(strm);
 588     return 0;
 589 }
 590
 591 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
 592 {
 593     BDRVQcowState *s = bs->opaque;
 594     int ret, csize;
 595     uint64_t coffset;
 596
 597     coffset = cluster_offset & s->cluster_offset_mask;
 598     if (s->cluster_cache_offset != coffset) {
 599         csize = cluster_offset >> (63 - s->cluster_bits);
 600         csize &= (s->cluster_size - 1);
 601         BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
 602         ret = bdrv_pread(bs->file, coffset, s->cluster_data, csize);
 603         if (ret != csize)
 604             return -1;
 605         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 606                               s->cluster_data, csize) < 0) {
 607             return -1;
 608         }
 609         s->cluster_cache_offset = coffset;
 610     }
 611     return 0;
 612 }
 613
 614 static void qcow_refresh_limits(BlockDriverState *bs, Error **errp)
 615 {
 616     /* At least encrypted images require 512-byte alignment. Apply the
 617      * limit universally, rather than just on encrypted images, as
 618      * it's easier to let the block layer handle rounding than to
 619      * audit this code further. */
 620     bs->bl.request_alignment = BDRV_SECTOR_SIZE;
 621 }
 622
 623 static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
 624                                        uint64_t bytes, QEMUIOVector *qiov,
 625                                        int flags)
 626 {
 627     BDRVQcowState *s = bs->opaque;
 628     int offset_in_cluster;
 629     int ret = 0, n;
 630     uint64_t cluster_offset;
 631     struct iovec hd_iov;
 632     QEMUIOVector hd_qiov;
 633     uint8_t *buf;
 634     void *orig_buf;
 635
 636     assert(!flags);
 637     if (qiov->niov > 1) {
 638         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 639         if (buf == NULL) {
 640             return -ENOMEM;
 641         }
 642     } else {
 643         orig_buf = NULL;
 644         buf = (uint8_t *)qiov->iov->iov_base;
 645     }
 646
 647     qemu_co_mutex_lock(&s->lock);
 648
 649     while (bytes != 0) {
 650         /* prepare next request */
 651         ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
 652         if (ret < 0) {
 653             break;
 654         }
 655         offset_in_cluster = offset & (s->cluster_size - 1);
 656         n = s->cluster_size - offset_in_cluster;
 657         if (n > bytes) {
 658             n = bytes;
 659         }
 660
 661         if (!cluster_offset) {
 662             if (bs->backing) {
 663                 /* read from the base image */
 664                 hd_iov.iov_base = (void *)buf;
 665                 hd_iov.iov_len = n;
 666                 qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 667                 qemu_co_mutex_unlock(&s->lock);
 668                 /* qcow2 emits this on bs->file instead of bs->backing */
 669                 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
 670                 ret = bdrv_co_preadv(bs->backing, offset, n, &hd_qiov, 0);
 671                 qemu_co_mutex_lock(&s->lock);
 672                 if (ret < 0) {
 673                     break;
 674                 }
 675             } else {
 676                 /* Note: in this case, no need to wait */
 677                 memset(buf, 0, n);
 678             }
 679         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 680             /* add AIO support for compressed blocks ? */
 681             if (decompress_cluster(bs, cluster_offset) < 0) {
 682                 ret = -EIO;
 683                 break;
 684             }
 685             memcpy(buf, s->cluster_cache + offset_in_cluster, n);
 686         } else {
 687             if ((cluster_offset & 511) != 0) {
 688                 ret = -EIO;
 689                 break;
 690             }
 691             hd_iov.iov_base = (void *)buf;
 692             hd_iov.iov_len = n;
 693             qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 694             qemu_co_mutex_unlock(&s->lock);
 695             BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
 696             ret = bdrv_co_preadv(bs->file, cluster_offset + offset_in_cluster,
 697                                  n, &hd_qiov, 0);
 698             qemu_co_mutex_lock(&s->lock);
 699             if (ret < 0) {
 700                 break;
 701             }
 702             if (bs->encrypted) {
 703                 assert(s->crypto);
 704                 if (qcrypto_block_decrypt(s->crypto,
 705                                           offset, buf, n, NULL) < 0) {
 706                     ret = -EIO;
 707                     break;
 708                 }
 709             }
 710         }
 711         ret = 0;
 712
 713         bytes -= n;
 714         offset += n;
 715         buf += n;
 716     }
 717
 718     qemu_co_mutex_unlock(&s->lock);
 719
 720     if (qiov->niov > 1) {
 721         qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
 722         qemu_vfree(orig_buf);
 723     }
 724
 725     return ret;
 726 }
 727
 728 static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
 729                                         uint64_t bytes, QEMUIOVector *qiov,
 730                                         int flags)
 731 {
 732     BDRVQcowState *s = bs->opaque;
 733     int offset_in_cluster;
 734     uint64_t cluster_offset;
 735     int ret = 0, n;
 736     struct iovec hd_iov;
 737     QEMUIOVector hd_qiov;
 738     uint8_t *buf;
 739     void *orig_buf;
 740
 741     assert(!flags);
 742     s->cluster_cache_offset = -1; /* disable compressed cache */
 743
 744     /* We must always copy the iov when encrypting, so we
 745      * don't modify the original data buffer during encryption */
 746     if (bs->encrypted || qiov->niov > 1) {
 747         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 748         if (buf == NULL) {
 749             return -ENOMEM;
 750         }
 751         qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
 752     } else {
 753         orig_buf = NULL;
 754         buf = (uint8_t *)qiov->iov->iov_base;
 755     }
 756
 757     qemu_co_mutex_lock(&s->lock);
 758
 759     while (bytes != 0) {
 760         offset_in_cluster = offset & (s->cluster_size - 1);
 761         n = s->cluster_size - offset_in_cluster;
 762         if (n > bytes) {
 763             n = bytes;
 764         }
 765         ret = get_cluster_offset(bs, offset, 1, 0, offset_in_cluster,
 766                                  offset_in_cluster + n, &cluster_offset);
 767         if (ret < 0) {
 768             break;
 769         }
 770         if (!cluster_offset || (cluster_offset & 511) != 0) {
 771             ret = -EIO;
 772             break;
 773         }
 774         if (bs->encrypted) {
 775             assert(s->crypto);
 776             if (qcrypto_block_encrypt(s->crypto, offset, buf, n, NULL) < 0) {
 777                 ret = -EIO;
 778                 break;
 779             }
 780         }
 781
 782         hd_iov.iov_base = (void *)buf;
 783         hd_iov.iov_len = n;
 784         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 785         qemu_co_mutex_unlock(&s->lock);
 786         BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
 787         ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,
 788                               n, &hd_qiov, 0);
 789         qemu_co_mutex_lock(&s->lock);
 790         if (ret < 0) {
 791             break;
 792         }
 793         ret = 0;
 794
 795         bytes -= n;
 796         offset += n;
 797         buf += n;
 798     }
 799     qemu_co_mutex_unlock(&s->lock);
 800
 801     qemu_vfree(orig_buf);
 802
 803     return ret;
 804 }
 805
 806 static void qcow_close(BlockDriverState *bs)
 807 {
 808     BDRVQcowState *s = bs->opaque;
 809
 810     qcrypto_block_free(s->crypto);
 811     s->crypto = NULL;
 812     g_free(s->l1_table);
 813     qemu_vfree(s->l2_cache);
 814     g_free(s->cluster_cache);
 815     g_free(s->cluster_data);
 816
 817     migrate_del_blocker(s->migration_blocker);
 818     error_free(s->migration_blocker);
 819 }
 820
 821 static int coroutine_fn qcow_co_create(BlockdevCreateOptions *opts,
 822                                        Error **errp)
 823 {
 824     BlockdevCreateOptionsQcow *qcow_opts;
 825     int header_size, backing_filename_len, l1_size, shift, i;
 826     QCowHeader header;
 827     uint8_t *tmp;
 828     int64_t total_size = 0;
 829     int ret;
 830     BlockDriverState *bs;
 831     BlockBackend *qcow_blk;
 832     QCryptoBlock *crypto = NULL;
 833
 834     assert(opts->driver == BLOCKDEV_DRIVER_QCOW);
 835     qcow_opts = &opts->u.qcow;
 836
 837     /* Sanity checks */
 838     total_size = qcow_opts->size;
 839     if (total_size == 0) {
 840         error_setg(errp, "Image size is too small, cannot be zero length");
 841         return -EINVAL;
 842     }
 843
 844     if (qcow_opts->has_encrypt &&
 845         qcow_opts->encrypt->format != Q_CRYPTO_BLOCK_FORMAT_QCOW)
 846     {
 847         error_setg(errp, "Unsupported encryption format");
 848         return -EINVAL;
 849     }
 850
 851     /* Create BlockBackend to write to the image */
 852     bs = bdrv_open_blockdev_ref(qcow_opts->file, errp);
 853     if (bs == NULL) {
 854         return -EIO;
 855     }
 856
 857     qcow_blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
 858     ret = blk_insert_bs(qcow_blk, bs, errp);
 859     if (ret < 0) {
 860         goto exit;
 861     }
 862     blk_set_allow_write_beyond_eof(qcow_blk, true);
 863
 864     /* Create image format */
 865     ret = blk_truncate(qcow_blk, 0, PREALLOC_MODE_OFF, errp);
 866     if (ret < 0) {
 867         goto exit;
 868     }
 869
 870     memset(&header, 0, sizeof(header));
 871     header.magic = cpu_to_be32(QCOW_MAGIC);
 872     header.version = cpu_to_be32(QCOW_VERSION);
 873     header.size = cpu_to_be64(total_size);
 874     header_size = sizeof(header);
 875     backing_filename_len = 0;
 876     if (qcow_opts->has_backing_file) {
 877         if (strcmp(qcow_opts->backing_file, "fat:")) {
 878             header.backing_file_offset = cpu_to_be64(header_size);
 879             backing_filename_len = strlen(qcow_opts->backing_file);
 880             header.backing_file_size = cpu_to_be32(backing_filename_len);
 881             header_size += backing_filename_len;
 882         } else {
 883             /* special backing file for vvfat */
 884             qcow_opts->has_backing_file = false;
 885         }
 886         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 887                                     unmodified sectors */
 888         header.l2_bits = 12; /* 32 KB L2 tables */
 889     } else {
 890         header.cluster_bits = 12; /* 4 KB clusters */
 891         header.l2_bits = 9; /* 4 KB L2 tables */
 892     }
 893     header_size = (header_size + 7) & ~7;
 894     shift = header.cluster_bits + header.l2_bits;
 895     l1_size = (total_size + (1LL << shift) - 1) >> shift;
 896
 897     header.l1_table_offset = cpu_to_be64(header_size);
 898
 899     if (qcow_opts->has_encrypt) {
 900         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 901
 902         crypto = qcrypto_block_create(qcow_opts->encrypt, "encrypt.",
 903                                       NULL, NULL, NULL, errp);
 904         if (!crypto) {
 905             ret = -EINVAL;
 906             goto exit;
 907         }
 908     } else {
 909         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 910     }
 911
 912     /* write all the data */
 913     ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header), 0);
 914     if (ret != sizeof(header)) {
 915         goto exit;
 916     }
 917
 918     if (qcow_opts->has_backing_file) {
 919         ret = blk_pwrite(qcow_blk, sizeof(header),
 920                          qcow_opts->backing_file, backing_filename_len, 0);
 921         if (ret != backing_filename_len) {
 922             goto exit;
 923         }
 924     }
 925
 926     tmp = g_malloc0(BDRV_SECTOR_SIZE);
 927     for (i = 0; i < DIV_ROUND_UP(sizeof(uint64_t) * l1_size, BDRV_SECTOR_SIZE);
 928          i++) {
 929         ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
 930                          tmp, BDRV_SECTOR_SIZE, 0);
 931         if (ret != BDRV_SECTOR_SIZE) {
 932             g_free(tmp);
 933             goto exit;
 934         }
 935     }
 936
 937     g_free(tmp);
 938     ret = 0;
 939 exit:
 940     blk_unref(qcow_blk);
 941     bdrv_unref(bs);
 942     qcrypto_block_free(crypto);
 943     return ret;
 944 }
 945
 946 static int coroutine_fn qcow_co_create_opts(const char *filename,
 947                                             QemuOpts *opts, Error **errp)
 948 {
 949     BlockdevCreateOptions *create_options = NULL;
 950     BlockDriverState *bs = NULL;
 951     QDict *qdict;
 952     Visitor *v;
 953     const char *val;
 954     Error *local_err = NULL;
 955     int ret;
 956
 957     static const QDictRenames opt_renames[] = {
 958         { BLOCK_OPT_BACKING_FILE,       "backing-file" },
 959         { BLOCK_OPT_ENCRYPT,            BLOCK_OPT_ENCRYPT_FORMAT },
 960         { NULL, NULL },
 961     };
 962
 963     /* Parse options and convert legacy syntax */
 964     qdict = qemu_opts_to_qdict_filtered(opts, NULL, &qcow_create_opts, true);
 965
 966     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT);
 967     if (val && !strcmp(val, "on")) {
 968         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT, "qcow");
 969     } else if (val && !strcmp(val, "off")) {
 970         qdict_del(qdict, BLOCK_OPT_ENCRYPT);
 971     }
 972
 973     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT);
 974     if (val && !strcmp(val, "aes")) {
 975         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT, "qcow");
 976     }
 977
 978     if (!qdict_rename_keys(qdict, opt_renames, errp)) {
 979         ret = -EINVAL;
 980         goto fail;
 981     }
 982
 983     /* Create and open the file (protocol layer) */
 984     ret = bdrv_create_file(filename, opts, &local_err);
 985     if (ret < 0) {
 986         error_propagate(errp, local_err);
 987         goto fail;
 988     }
 989
 990     bs = bdrv_open(filename, NULL, NULL,
 991                    BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
 992     if (bs == NULL) {
 993         ret = -EIO;
 994         goto fail;
 995     }
 996
 997     /* Now get the QAPI type BlockdevCreateOptions */
 998     qdict_put_str(qdict, "driver", "qcow");
 999     qdict_put_str(qdict, "file", bs->node_name);
1000
1001     v = qobject_input_visitor_new_flat_confused(qdict, errp);
1002     if (!v) {
1003         ret = -EINVAL;
1004         goto fail;
1005     }
1006
1007     visit_type_BlockdevCreateOptions(v, NULL, &create_options, &local_err);
1008     visit_free(v);
1009
1010     if (local_err) {
1011         error_propagate(errp, local_err);
1012         ret = -EINVAL;
1013         goto fail;
1014     }
1015
1016     /* Silently round up size */
1017     assert(create_options->driver == BLOCKDEV_DRIVER_QCOW);
1018     create_options->u.qcow.size =
1019         ROUND_UP(create_options->u.qcow.size, BDRV_SECTOR_SIZE);
1020
1021     /* Create the qcow image (format layer) */
1022     ret = qcow_co_create(create_options, errp);
1023     if (ret < 0) {
1024         goto fail;
1025     }
1026
1027     ret = 0;
1028 fail:
1029     qobject_unref(qdict);
1030     bdrv_unref(bs);
1031     qapi_free_BlockdevCreateOptions(create_options);
1032     return ret;
1033 }
1034
1035 static int qcow_make_empty(BlockDriverState *bs)
1036 {
1037     BDRVQcowState *s = bs->opaque;
1038     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
1039     int ret;
1040
1041     memset(s->l1_table, 0, l1_length);
1042     if (bdrv_pwrite_sync(bs->file, s->l1_table_offset, s->l1_table,
1043             l1_length) < 0)
1044         return -1;
1045     ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length,
1046                         PREALLOC_MODE_OFF, NULL);
1047     if (ret < 0)
1048         return ret;
1049
1050     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
1051     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
1052     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
1053
1054     return 0;
1055 }
1056
1057 /* XXX: put compressed sectors first, then all the cluster aligned
1058    tables to avoid losing bytes in alignment */
1059 static coroutine_fn int
1060 qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
1061                            uint64_t bytes, QEMUIOVector *qiov)
1062 {
1063     BDRVQcowState *s = bs->opaque;
1064     QEMUIOVector hd_qiov;
1065     struct iovec iov;
1066     z_stream strm;
1067     int ret, out_len;
1068     uint8_t *buf, *out_buf;
1069     uint64_t cluster_offset;
1070
1071     buf = qemu_blockalign(bs, s->cluster_size);
1072     if (bytes != s->cluster_size) {
1073         if (bytes > s->cluster_size ||
1074             offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS)
1075         {
1076             qemu_vfree(buf);
1077             return -EINVAL;
1078         }
1079         /* Zero-pad last write if image size is not cluster aligned */
1080         memset(buf + bytes, 0, s->cluster_size - bytes);
1081     }
1082     qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
1083
1084     out_buf = g_malloc(s->cluster_size);
1085
1086     /* best compression, small window, no zlib header */
1087     memset(&strm, 0, sizeof(strm));
1088     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
1089                        Z_DEFLATED, -12,
1090                        9, Z_DEFAULT_STRATEGY);
1091     if (ret != 0) {
1092         ret = -EINVAL;
1093         goto fail;
1094     }
1095
1096     strm.avail_in = s->cluster_size;
1097     strm.next_in = (uint8_t *)buf;
1098     strm.avail_out = s->cluster_size;
1099     strm.next_out = out_buf;
1100
1101     ret = deflate(&strm, Z_FINISH);
1102     if (ret != Z_STREAM_END && ret != Z_OK) {
1103         deflateEnd(&strm);
1104         ret = -EINVAL;
1105         goto fail;
1106     }
1107     out_len = strm.next_out - out_buf;
1108
1109     deflateEnd(&strm);
1110
1111     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
1112         /* could not compress: write normal cluster */
1113         ret = qcow_co_pwritev(bs, offset, bytes, qiov, 0);
1114         if (ret < 0) {
1115             goto fail;
1116         }
1117         goto success;
1118     }
1119     qemu_co_mutex_lock(&s->lock);
1120     ret = get_cluster_offset(bs, offset, 2, out_len, 0, 0, &cluster_offset);
1121     qemu_co_mutex_unlock(&s->lock);
1122     if (ret < 0) {
1123         goto fail;
1124     }
1125     if (cluster_offset == 0) {
1126         ret = -EIO;
1127         goto fail;
1128     }
1129     cluster_offset &= s->cluster_offset_mask;
1130
1131     iov = (struct iovec) {
1132         .iov_base   = out_buf,
1133         .iov_len    = out_len,
1134     };
1135     qemu_iovec_init_external(&hd_qiov, &iov, 1);
1136     BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
1137     ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
1138     if (ret < 0) {
1139         goto fail;
1140     }
1141 success:
1142     ret = 0;
1143 fail:
1144     qemu_vfree(buf);
1145     g_free(out_buf);
1146     return ret;
1147 }
1148
1149 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
1150 {
1151     BDRVQcowState *s = bs->opaque;
1152     bdi->cluster_size = s->cluster_size;
1153     return 0;
1154 }
1155
1156 static QemuOptsList qcow_create_opts = {
1157     .name = "qcow-create-opts",
1158     .head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
1159     .desc = {
1160         {
1161             .name = BLOCK_OPT_SIZE,
1162             .type = QEMU_OPT_SIZE,
1163             .help = "Virtual disk size"
1164         },
1165         {
1166             .name = BLOCK_OPT_BACKING_FILE,
1167             .type = QEMU_OPT_STRING,
1168             .help = "File name of a base image"
1169         },
1170         {
1171             .name = BLOCK_OPT_ENCRYPT,
1172             .type = QEMU_OPT_BOOL,
1173             .help = "Encrypt the image with format 'aes'. (Deprecated "
1174                     "in favor of " BLOCK_OPT_ENCRYPT_FORMAT "=aes)",
1175         },
1176         {
1177             .name = BLOCK_OPT_ENCRYPT_FORMAT,
1178             .type = QEMU_OPT_STRING,
1179             .help = "Encrypt the image, format choices: 'aes'",
1180         },
1181         BLOCK_CRYPTO_OPT_DEF_QCOW_KEY_SECRET("encrypt."),
1182         { /* end of list */ }
1183     }
1184 };
1185
1186 static BlockDriver bdrv_qcow = {
1187     .format_name        = "qcow",
1188     .instance_size      = sizeof(BDRVQcowState),
1189     .bdrv_probe         = qcow_probe,
1190     .bdrv_open          = qcow_open,
1191     .bdrv_close         = qcow_close,
1192     .bdrv_child_perm        = bdrv_format_default_perms,
1193     .bdrv_reopen_prepare    = qcow_reopen_prepare,
1194     .bdrv_co_create         = qcow_co_create,
1195     .bdrv_co_create_opts    = qcow_co_create_opts,
1196     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
1197     .supports_backing       = true,
1198     .bdrv_refresh_limits    = qcow_refresh_limits,
1199
1200     .bdrv_co_preadv         = qcow_co_preadv,
1201     .bdrv_co_pwritev        = qcow_co_pwritev,
1202     .bdrv_co_block_status   = qcow_co_block_status,
1203
1204     .bdrv_make_empty        = qcow_make_empty,
1205     .bdrv_co_pwritev_compressed = qcow_co_pwritev_compressed,
1206     .bdrv_get_info          = qcow_get_info,
1207
1208     .create_opts            = &qcow_create_opts,
1209 };
1210
1211 static void bdrv_qcow_init(void)
1212 {
1213     bdrv_register(&bdrv_qcow);
1214 }
1215
1216 block_init(bdrv_qcow_init);