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