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 #include "qemu/osdep.h"
  25 #include "qapi/error.h"
  26 #include "qemu-common.h"
  27 #include "qemu/error-report.h"
  28 #include "block/block_int.h"
  29 #include "sysemu/block-backend.h"
  30 #include "qemu/module.h"
  31 #include "qemu/bswap.h"
  32 #include <zlib.h>
  33 #include "qapi/qmp/qerror.h"
  34 #include "qapi/qmp/qstring.h"
  35 #include "crypto/block.h"
  36 #include "migration/blocker.h"
  37 #include "block/crypto.h"
  38
  39 /**************************************************************/
  40 /* QEMU COW block driver with compression and encryption support */
  41
  42 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  43 #define QCOW_VERSION 1
  44
  45 #define QCOW_CRYPT_NONE 0
  46 #define QCOW_CRYPT_AES  1
  47
  48 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
  49
  50 typedef struct QCowHeader {
  51     uint32_t magic;
  52     uint32_t version;
  53     uint64_t backing_file_offset;
  54     uint32_t backing_file_size;
  55     uint32_t mtime;
  56     uint64_t size; /* in bytes */
  57     uint8_t cluster_bits;
  58     uint8_t l2_bits;
  59     uint16_t padding;
  60     uint32_t crypt_method;
  61     uint64_t l1_table_offset;
  62 } QEMU_PACKED QCowHeader;
  63
  64 #define L2_CACHE_SIZE 16
  65
  66 typedef struct BDRVQcowState {
  67     int cluster_bits;
  68     int cluster_size;
  69     int cluster_sectors;
  70     int l2_bits;
  71     int l2_size;
  72     unsigned int l1_size;
  73     uint64_t cluster_offset_mask;
  74     uint64_t l1_table_offset;
  75     uint64_t *l1_table;
  76     uint64_t *l2_cache;
  77     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
  78     uint32_t l2_cache_counts[L2_CACHE_SIZE];
  79     uint8_t *cluster_cache;
  80     uint8_t *cluster_data;
  81     uint64_t cluster_cache_offset;
  82     QCryptoBlock *crypto; /* Disk encryption format driver */
  83     uint32_t crypt_method_header;
  84     CoMutex lock;
  85     Error *migration_blocker;
  86 } BDRVQcowState;
  87
  88 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
  89
  90 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
  91 {
  92     const QCowHeader *cow_header = (const void *)buf;
  93
  94     if (buf_size >= sizeof(QCowHeader) &&
  95         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
  96         be32_to_cpu(cow_header->version) == QCOW_VERSION)
  97         return 100;
  98     else
  99         return 0;
 100 }
 101
 102 static QemuOptsList qcow_runtime_opts = {
 103     .name = "qcow",
 104     .head = QTAILQ_HEAD_INITIALIZER(qcow_runtime_opts.head),
 105     .desc = {
 106         BLOCK_CRYPTO_OPT_DEF_QCOW_KEY_SECRET("encrypt."),
 107         { /* end of list */ }
 108     },
 109 };
 110
 111 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
 112                      Error **errp)
 113 {
 114     BDRVQcowState *s = bs->opaque;
 115     unsigned int len, i, shift;
 116     int ret;
 117     QCowHeader header;
 118     Error *local_err = NULL;
 119     QCryptoBlockOpenOptions *crypto_opts = NULL;
 120     unsigned int cflags = 0;
 121     QDict *encryptopts = NULL;
 122     const char *encryptfmt;
 123
 124     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
 125     encryptfmt = qdict_get_try_str(encryptopts, "format");
 126
 127     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 128                                false, errp);
 129     if (!bs->file) {
 130         ret = -EINVAL;
 131         goto fail;
 132     }
 133
 134     ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
 135     if (ret < 0) {
 136         goto fail;
 137     }
 138     be32_to_cpus(&header.magic);
 139     be32_to_cpus(&header.version);
 140     be64_to_cpus(&header.backing_file_offset);
 141     be32_to_cpus(&header.backing_file_size);
 142     be32_to_cpus(&header.mtime);
 143     be64_to_cpus(&header.size);
 144     be32_to_cpus(&header.crypt_method);
 145     be64_to_cpus(&header.l1_table_offset);
 146
 147     if (header.magic != QCOW_MAGIC) {
 148         error_setg(errp, "Image not in qcow format");
 149         ret = -EINVAL;
 150         goto fail;
 151     }
 152     if (header.version != QCOW_VERSION) {
 153         error_setg(errp, "Unsupported qcow version %" PRIu32, header.version);
 154         ret = -ENOTSUP;
 155         goto fail;
 156     }
 157
 158     if (header.size <= 1) {
 159         error_setg(errp, "Image size is too small (must be at least 2 bytes)");
 160         ret = -EINVAL;
 161         goto fail;
 162     }
 163     if (header.cluster_bits < 9 || header.cluster_bits > 16) {
 164         error_setg(errp, "Cluster size must be between 512 and 64k");
 165         ret = -EINVAL;
 166         goto fail;
 167     }
 168
 169     /* l2_bits specifies number of entries; storing a uint64_t in each entry,
 170      * so bytes = num_entries << 3. */
 171     if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
 172         error_setg(errp, "L2 table size must be between 512 and 64k");
 173         ret = -EINVAL;
 174         goto fail;
 175     }
 176
 177     s->crypt_method_header = header.crypt_method;
 178     if (s->crypt_method_header) {
 179         if (bdrv_uses_whitelist() &&
 180             s->crypt_method_header == QCOW_CRYPT_AES) {
 181             error_setg(errp,
 182                        "Use of AES-CBC encrypted qcow images is no longer "
 183                        "supported in system emulators");
 184             error_append_hint(errp,
 185                               "You can use 'qemu-img convert' to convert your "
 186                               "image to an alternative supported format, such "
 187                               "as unencrypted qcow, or raw with the LUKS "
 188                               "format instead.\n");
 189             ret = -ENOSYS;
 190             goto fail;
 191         }
 192         if (s->crypt_method_header == QCOW_CRYPT_AES) {
 193             if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
 194                 error_setg(errp,
 195                            "Header reported 'aes' encryption format but "
 196                            "options specify '%s'", encryptfmt);
 197                 ret = -EINVAL;
 198                 goto fail;
 199             }
 200             qdict_del(encryptopts, "format");
 201             crypto_opts = block_crypto_open_opts_init(
 202                 Q_CRYPTO_BLOCK_FORMAT_QCOW, encryptopts, errp);
 203             if (!crypto_opts) {
 204                 ret = -EINVAL;
 205                 goto fail;
 206             }
 207
 208             if (flags & BDRV_O_NO_IO) {
 209                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 210             }
 211             s->crypto = qcrypto_block_open(crypto_opts, "encrypt.",
 212                                            NULL, NULL, cflags, errp);
 213             if (!s->crypto) {
 214                 ret = -EINVAL;
 215                 goto fail;
 216             }
 217         } else {
 218             error_setg(errp, "invalid encryption method in qcow header");
 219             ret = -EINVAL;
 220             goto fail;
 221         }
 222         bs->encrypted = true;
 223     } else {
 224         if (encryptfmt) {
 225             error_setg(errp, "No encryption in image header, but options "
 226                        "specified format '%s'", encryptfmt);
 227             ret = -EINVAL;
 228             goto fail;
 229         }
 230     }
 231     s->cluster_bits = header.cluster_bits;
 232     s->cluster_size = 1 << s->cluster_bits;
 233     s->cluster_sectors = 1 << (s->cluster_bits - 9);
 234     s->l2_bits = header.l2_bits;
 235     s->l2_size = 1 << s->l2_bits;
 236     bs->total_sectors = header.size / 512;
 237     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
 238
 239     /* read the level 1 table */
 240     shift = s->cluster_bits + s->l2_bits;
 241     if (header.size > UINT64_MAX - (1LL << shift)) {
 242         error_setg(errp, "Image too large");
 243         ret = -EINVAL;
 244         goto fail;
 245     } else {
 246         uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
 247         if (l1_size > INT_MAX / sizeof(uint64_t)) {
 248             error_setg(errp, "Image too large");
 249             ret = -EINVAL;
 250             goto fail;
 251         }
 252         s->l1_size = l1_size;
 253     }
 254
 255     s->l1_table_offset = header.l1_table_offset;
 256     s->l1_table = g_try_new(uint64_t, s->l1_size);
 257     if (s->l1_table == NULL) {
 258         error_setg(errp, "Could not allocate memory for L1 table");
 259         ret = -ENOMEM;
 260         goto fail;
 261     }
 262
 263     ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
 264                s->l1_size * sizeof(uint64_t));
 265     if (ret < 0) {
 266         goto fail;
 267     }
 268
 269     for(i = 0;i < s->l1_size; i++) {
 270         be64_to_cpus(&s->l1_table[i]);
 271     }
 272
 273     /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
 274     s->l2_cache =
 275         qemu_try_blockalign(bs->file->bs,
 276                             s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 277     if (s->l2_cache == NULL) {
 278         error_setg(errp, "Could not allocate L2 table cache");
 279         ret = -ENOMEM;
 280         goto fail;
 281     }
 282     s->cluster_cache = g_malloc(s->cluster_size);
 283     s->cluster_data = g_malloc(s->cluster_size);
 284     s->cluster_cache_offset = -1;
 285
 286     /* read the backing file name */
 287     if (header.backing_file_offset != 0) {
 288         len = header.backing_file_size;
 289         if (len > 1023 || len >= sizeof(bs->backing_file)) {
 290             error_setg(errp, "Backing file name too long");
 291             ret = -EINVAL;
 292             goto fail;
 293         }
 294         ret = bdrv_pread(bs->file, header.backing_file_offset,
 295                    bs->backing_file, len);
 296         if (ret < 0) {
 297             goto fail;
 298         }
 299         bs->backing_file[len] = '\0';
 300     }
 301
 302     /* Disable migration when qcow images are used */
 303     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
 304                "does not support live migration",
 305                bdrv_get_device_or_node_name(bs));
 306     ret = migrate_add_blocker(s->migration_blocker, &local_err);
 307     if (local_err) {
 308         error_propagate(errp, local_err);
 309         error_free(s->migration_blocker);
 310         goto fail;
 311     }
 312
 313     QDECREF(encryptopts);
 314     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
 315     qemu_co_mutex_init(&s->lock);
 316     return 0;
 317
 318  fail:
 319     g_free(s->l1_table);
 320     qemu_vfree(s->l2_cache);
 321     g_free(s->cluster_cache);
 322     g_free(s->cluster_data);
 323     qcrypto_block_free(s->crypto);
 324     QDECREF(encryptopts);
 325     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
 326     return ret;
 327 }
 328
 329
 330 /* We have nothing to do for QCOW reopen, stubs just return
 331  * success */
 332 static int qcow_reopen_prepare(BDRVReopenState *state,
 333                                BlockReopenQueue *queue, Error **errp)
 334 {
 335     return 0;
 336 }
 337
 338
 339 /* 'allocate' is:
 340  *
 341  * 0 to not allocate.
 342  *
 343  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
 344  * 'n_end')
 345  *
 346  * 2 to allocate a compressed cluster of size
 347  * 'compressed_size'. 'compressed_size' must be > 0 and <
 348  * cluster_size
 349  *
 350  * return 0 if not allocated.
 351  */
 352 static uint64_t get_cluster_offset(BlockDriverState *bs,
 353                                    uint64_t offset, int allocate,
 354                                    int compressed_size,
 355                                    int n_start, int n_end)
 356 {
 357     BDRVQcowState *s = bs->opaque;
 358     int min_index, i, j, l1_index, l2_index;
 359     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
 360     uint32_t min_count;
 361     int new_l2_table;
 362
 363     l1_index = offset >> (s->l2_bits + s->cluster_bits);
 364     l2_offset = s->l1_table[l1_index];
 365     new_l2_table = 0;
 366     if (!l2_offset) {
 367         if (!allocate)
 368             return 0;
 369         /* allocate a new l2 entry */
 370         l2_offset = bdrv_getlength(bs->file->bs);
 371         /* round to cluster size */
 372         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
 373         /* update the L1 entry */
 374         s->l1_table[l1_index] = l2_offset;
 375         tmp = cpu_to_be64(l2_offset);
 376         if (bdrv_pwrite_sync(bs->file,
 377                 s->l1_table_offset + l1_index * sizeof(tmp),
 378                 &tmp, sizeof(tmp)) < 0)
 379             return 0;
 380         new_l2_table = 1;
 381     }
 382     for(i = 0; i < L2_CACHE_SIZE; i++) {
 383         if (l2_offset == s->l2_cache_offsets[i]) {
 384             /* increment the hit count */
 385             if (++s->l2_cache_counts[i] == 0xffffffff) {
 386                 for(j = 0; j < L2_CACHE_SIZE; j++) {
 387                     s->l2_cache_counts[j] >>= 1;
 388                 }
 389             }
 390             l2_table = s->l2_cache + (i << s->l2_bits);
 391             goto found;
 392         }
 393     }
 394     /* not found: load a new entry in the least used one */
 395     min_index = 0;
 396     min_count = 0xffffffff;
 397     for(i = 0; i < L2_CACHE_SIZE; i++) {
 398         if (s->l2_cache_counts[i] < min_count) {
 399             min_count = s->l2_cache_counts[i];
 400             min_index = i;
 401         }
 402     }
 403     l2_table = s->l2_cache + (min_index << s->l2_bits);
 404     if (new_l2_table) {
 405         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
 406         if (bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
 407                 s->l2_size * sizeof(uint64_t)) < 0)
 408             return 0;
 409     } else {
 410         if (bdrv_pread(bs->file, l2_offset, l2_table,
 411                        s->l2_size * sizeof(uint64_t)) !=
 412             s->l2_size * sizeof(uint64_t))
 413             return 0;
 414     }
 415     s->l2_cache_offsets[min_index] = l2_offset;
 416     s->l2_cache_counts[min_index] = 1;
 417  found:
 418     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 419     cluster_offset = be64_to_cpu(l2_table[l2_index]);
 420     if (!cluster_offset ||
 421         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
 422         if (!allocate)
 423             return 0;
 424         /* allocate a new cluster */
 425         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
 426             (n_end - n_start) < s->cluster_sectors) {
 427             /* if the cluster is already compressed, we must
 428                decompress it in the case it is not completely
 429                overwritten */
 430             if (decompress_cluster(bs, cluster_offset) < 0)
 431                 return 0;
 432             cluster_offset = bdrv_getlength(bs->file->bs);
 433             cluster_offset = (cluster_offset + s->cluster_size - 1) &
 434                 ~(s->cluster_size - 1);
 435             /* write the cluster content */
 436             if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
 437                             s->cluster_size) !=
 438                 s->cluster_size)
 439                 return -1;
 440         } else {
 441             cluster_offset = bdrv_getlength(bs->file->bs);
 442             if (allocate == 1) {
 443                 /* round to cluster size */
 444                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
 445                     ~(s->cluster_size - 1);
 446                 bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
 447                               PREALLOC_MODE_OFF, NULL);
 448                 /* if encrypted, we must initialize the cluster
 449                    content which won't be written */
 450                 if (bs->encrypted &&
 451                     (n_end - n_start) < s->cluster_sectors) {
 452                     uint64_t start_sect;
 453                     assert(s->crypto);
 454                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
 455                     for(i = 0; i < s->cluster_sectors; i++) {
 456                         if (i < n_start || i >= n_end) {
 457                             Error *err = NULL;
 458                             memset(s->cluster_data, 0x00, 512);
 459                             if (qcrypto_block_encrypt(s->crypto, start_sect + i,
 460                                                       s->cluster_data,
 461                                                       BDRV_SECTOR_SIZE,
 462                                                       &err) < 0) {
 463                                 error_free(err);
 464                                 errno = EIO;
 465                                 return -1;
 466                             }
 467                             if (bdrv_pwrite(bs->file,
 468                                             cluster_offset + i * 512,
 469                                             s->cluster_data, 512) != 512)
 470                                 return -1;
 471                         }
 472                     }
 473                 }
 474             } else if (allocate == 2) {
 475                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
 476                     (uint64_t)compressed_size << (63 - s->cluster_bits);
 477             }
 478         }
 479         /* update L2 table */
 480         tmp = cpu_to_be64(cluster_offset);
 481         l2_table[l2_index] = tmp;
 482         if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
 483                 &tmp, sizeof(tmp)) < 0)
 484             return 0;
 485     }
 486     return cluster_offset;
 487 }
 488
 489 static int64_t coroutine_fn qcow_co_get_block_status(BlockDriverState *bs,
 490         int64_t sector_num, int nb_sectors, int *pnum, BlockDriverState **file)
 491 {
 492     BDRVQcowState *s = bs->opaque;
 493     int index_in_cluster, n;
 494     uint64_t cluster_offset;
 495
 496     qemu_co_mutex_lock(&s->lock);
 497     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 498     qemu_co_mutex_unlock(&s->lock);
 499     index_in_cluster = sector_num & (s->cluster_sectors - 1);
 500     n = s->cluster_sectors - index_in_cluster;
 501     if (n > nb_sectors)
 502         n = nb_sectors;
 503     *pnum = n;
 504     if (!cluster_offset) {
 505         return 0;
 506     }
 507     if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->crypto) {
 508         return BDRV_BLOCK_DATA;
 509     }
 510     cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
 511     *file = bs->file->bs;
 512     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | cluster_offset;
 513 }
 514
 515 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 516                              const uint8_t *buf, int buf_size)
 517 {
 518     z_stream strm1, *strm = &strm1;
 519     int ret, out_len;
 520
 521     memset(strm, 0, sizeof(*strm));
 522
 523     strm->next_in = (uint8_t *)buf;
 524     strm->avail_in = buf_size;
 525     strm->next_out = out_buf;
 526     strm->avail_out = out_buf_size;
 527
 528     ret = inflateInit2(strm, -12);
 529     if (ret != Z_OK)
 530         return -1;
 531     ret = inflate(strm, Z_FINISH);
 532     out_len = strm->next_out - out_buf;
 533     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 534         out_len != out_buf_size) {
 535         inflateEnd(strm);
 536         return -1;
 537     }
 538     inflateEnd(strm);
 539     return 0;
 540 }
 541
 542 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
 543 {
 544     BDRVQcowState *s = bs->opaque;
 545     int ret, csize;
 546     uint64_t coffset;
 547
 548     coffset = cluster_offset & s->cluster_offset_mask;
 549     if (s->cluster_cache_offset != coffset) {
 550         csize = cluster_offset >> (63 - s->cluster_bits);
 551         csize &= (s->cluster_size - 1);
 552         ret = bdrv_pread(bs->file, coffset, s->cluster_data, csize);
 553         if (ret != csize)
 554             return -1;
 555         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 556                               s->cluster_data, csize) < 0) {
 557             return -1;
 558         }
 559         s->cluster_cache_offset = coffset;
 560     }
 561     return 0;
 562 }
 563
 564 static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
 565                          int nb_sectors, QEMUIOVector *qiov)
 566 {
 567     BDRVQcowState *s = bs->opaque;
 568     int index_in_cluster;
 569     int ret = 0, n;
 570     uint64_t cluster_offset;
 571     struct iovec hd_iov;
 572     QEMUIOVector hd_qiov;
 573     uint8_t *buf;
 574     void *orig_buf;
 575     Error *err = NULL;
 576
 577     if (qiov->niov > 1) {
 578         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 579         if (buf == NULL) {
 580             return -ENOMEM;
 581         }
 582     } else {
 583         orig_buf = NULL;
 584         buf = (uint8_t *)qiov->iov->iov_base;
 585     }
 586
 587     qemu_co_mutex_lock(&s->lock);
 588
 589     while (nb_sectors != 0) {
 590         /* prepare next request */
 591         cluster_offset = get_cluster_offset(bs, sector_num << 9,
 592                                                  0, 0, 0, 0);
 593         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 594         n = s->cluster_sectors - index_in_cluster;
 595         if (n > nb_sectors) {
 596             n = nb_sectors;
 597         }
 598
 599         if (!cluster_offset) {
 600             if (bs->backing) {
 601                 /* read from the base image */
 602                 hd_iov.iov_base = (void *)buf;
 603                 hd_iov.iov_len = n * 512;
 604                 qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 605                 qemu_co_mutex_unlock(&s->lock);
 606                 ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
 607                 qemu_co_mutex_lock(&s->lock);
 608                 if (ret < 0) {
 609                     goto fail;
 610                 }
 611             } else {
 612                 /* Note: in this case, no need to wait */
 613                 memset(buf, 0, 512 * n);
 614             }
 615         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 616             /* add AIO support for compressed blocks ? */
 617             if (decompress_cluster(bs, cluster_offset) < 0) {
 618                 goto fail;
 619             }
 620             memcpy(buf,
 621                    s->cluster_cache + index_in_cluster * 512, 512 * n);
 622         } else {
 623             if ((cluster_offset & 511) != 0) {
 624                 goto fail;
 625             }
 626             hd_iov.iov_base = (void *)buf;
 627             hd_iov.iov_len = n * 512;
 628             qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 629             qemu_co_mutex_unlock(&s->lock);
 630             ret = bdrv_co_readv(bs->file,
 631                                 (cluster_offset >> 9) + index_in_cluster,
 632                                 n, &hd_qiov);
 633             qemu_co_mutex_lock(&s->lock);
 634             if (ret < 0) {
 635                 break;
 636             }
 637             if (bs->encrypted) {
 638                 assert(s->crypto);
 639                 if (qcrypto_block_decrypt(s->crypto, sector_num, buf,
 640                                           n * BDRV_SECTOR_SIZE, &err) < 0) {
 641                     goto fail;
 642                 }
 643             }
 644         }
 645         ret = 0;
 646
 647         nb_sectors -= n;
 648         sector_num += n;
 649         buf += n * 512;
 650     }
 651
 652 done:
 653     qemu_co_mutex_unlock(&s->lock);
 654
 655     if (qiov->niov > 1) {
 656         qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
 657         qemu_vfree(orig_buf);
 658     }
 659
 660     return ret;
 661
 662 fail:
 663     error_free(err);
 664     ret = -EIO;
 665     goto done;
 666 }
 667
 668 static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
 669                           int nb_sectors, QEMUIOVector *qiov)
 670 {
 671     BDRVQcowState *s = bs->opaque;
 672     int index_in_cluster;
 673     uint64_t cluster_offset;
 674     int ret = 0, n;
 675     struct iovec hd_iov;
 676     QEMUIOVector hd_qiov;
 677     uint8_t *buf;
 678     void *orig_buf;
 679
 680     s->cluster_cache_offset = -1; /* disable compressed cache */
 681
 682     /* We must always copy the iov when encrypting, so we
 683      * don't modify the original data buffer during encryption */
 684     if (bs->encrypted || qiov->niov > 1) {
 685         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 686         if (buf == NULL) {
 687             return -ENOMEM;
 688         }
 689         qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
 690     } else {
 691         orig_buf = NULL;
 692         buf = (uint8_t *)qiov->iov->iov_base;
 693     }
 694
 695     qemu_co_mutex_lock(&s->lock);
 696
 697     while (nb_sectors != 0) {
 698
 699         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 700         n = s->cluster_sectors - index_in_cluster;
 701         if (n > nb_sectors) {
 702             n = nb_sectors;
 703         }
 704         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
 705                                             index_in_cluster,
 706                                             index_in_cluster + n);
 707         if (!cluster_offset || (cluster_offset & 511) != 0) {
 708             ret = -EIO;
 709             break;
 710         }
 711         if (bs->encrypted) {
 712             Error *err = NULL;
 713             assert(s->crypto);
 714             if (qcrypto_block_encrypt(s->crypto, sector_num, buf,
 715                                       n * BDRV_SECTOR_SIZE, &err) < 0) {
 716                 error_free(err);
 717                 ret = -EIO;
 718                 break;
 719             }
 720         }
 721
 722         hd_iov.iov_base = (void *)buf;
 723         hd_iov.iov_len = n * 512;
 724         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 725         qemu_co_mutex_unlock(&s->lock);
 726         ret = bdrv_co_writev(bs->file,
 727                              (cluster_offset >> 9) + index_in_cluster,
 728                              n, &hd_qiov);
 729         qemu_co_mutex_lock(&s->lock);
 730         if (ret < 0) {
 731             break;
 732         }
 733         ret = 0;
 734
 735         nb_sectors -= n;
 736         sector_num += n;
 737         buf += n * 512;
 738     }
 739     qemu_co_mutex_unlock(&s->lock);
 740
 741     qemu_vfree(orig_buf);
 742
 743     return ret;
 744 }
 745
 746 static void qcow_close(BlockDriverState *bs)
 747 {
 748     BDRVQcowState *s = bs->opaque;
 749
 750     qcrypto_block_free(s->crypto);
 751     s->crypto = NULL;
 752     g_free(s->l1_table);
 753     qemu_vfree(s->l2_cache);
 754     g_free(s->cluster_cache);
 755     g_free(s->cluster_data);
 756
 757     migrate_del_blocker(s->migration_blocker);
 758     error_free(s->migration_blocker);
 759 }
 760
 761 static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
 762 {
 763     int header_size, backing_filename_len, l1_size, shift, i;
 764     QCowHeader header;
 765     uint8_t *tmp;
 766     int64_t total_size = 0;
 767     char *backing_file = NULL;
 768     Error *local_err = NULL;
 769     int ret;
 770     BlockBackend *qcow_blk;
 771     char *encryptfmt = NULL;
 772     QDict *options;
 773     QDict *encryptopts = NULL;
 774     QCryptoBlockCreateOptions *crypto_opts = NULL;
 775     QCryptoBlock *crypto = NULL;
 776
 777     /* Read out options */
 778     total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 779                           BDRV_SECTOR_SIZE);
 780     if (total_size == 0) {
 781         error_setg(errp, "Image size is too small, cannot be zero length");
 782         ret = -EINVAL;
 783         goto cleanup;
 784     }
 785
 786     backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
 787     encryptfmt = qemu_opt_get_del(opts, BLOCK_OPT_ENCRYPT_FORMAT);
 788     if (encryptfmt) {
 789         if (qemu_opt_get(opts, BLOCK_OPT_ENCRYPT)) {
 790             error_setg(errp, "Options " BLOCK_OPT_ENCRYPT " and "
 791                        BLOCK_OPT_ENCRYPT_FORMAT " are mutually exclusive");
 792             ret = -EINVAL;
 793             goto cleanup;
 794         }
 795     } else if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
 796         encryptfmt = g_strdup("aes");
 797     }
 798
 799     ret = bdrv_create_file(filename, opts, &local_err);
 800     if (ret < 0) {
 801         error_propagate(errp, local_err);
 802         goto cleanup;
 803     }
 804
 805     qcow_blk = blk_new_open(filename, NULL, NULL,
 806                             BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
 807                             &local_err);
 808     if (qcow_blk == NULL) {
 809         error_propagate(errp, local_err);
 810         ret = -EIO;
 811         goto cleanup;
 812     }
 813
 814     blk_set_allow_write_beyond_eof(qcow_blk, true);
 815
 816     ret = blk_truncate(qcow_blk, 0, PREALLOC_MODE_OFF, errp);
 817     if (ret < 0) {
 818         goto exit;
 819     }
 820
 821     memset(&header, 0, sizeof(header));
 822     header.magic = cpu_to_be32(QCOW_MAGIC);
 823     header.version = cpu_to_be32(QCOW_VERSION);
 824     header.size = cpu_to_be64(total_size);
 825     header_size = sizeof(header);
 826     backing_filename_len = 0;
 827     if (backing_file) {
 828         if (strcmp(backing_file, "fat:")) {
 829             header.backing_file_offset = cpu_to_be64(header_size);
 830             backing_filename_len = strlen(backing_file);
 831             header.backing_file_size = cpu_to_be32(backing_filename_len);
 832             header_size += backing_filename_len;
 833         } else {
 834             /* special backing file for vvfat */
 835             g_free(backing_file);
 836             backing_file = NULL;
 837         }
 838         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 839                                     unmodified sectors */
 840         header.l2_bits = 12; /* 32 KB L2 tables */
 841     } else {
 842         header.cluster_bits = 12; /* 4 KB clusters */
 843         header.l2_bits = 9; /* 4 KB L2 tables */
 844     }
 845     header_size = (header_size + 7) & ~7;
 846     shift = header.cluster_bits + header.l2_bits;
 847     l1_size = (total_size + (1LL << shift) - 1) >> shift;
 848
 849     header.l1_table_offset = cpu_to_be64(header_size);
 850
 851     options = qemu_opts_to_qdict(opts, NULL);
 852     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
 853     QDECREF(options);
 854     if (encryptfmt) {
 855         if (!g_str_equal(encryptfmt, "aes")) {
 856             error_setg(errp, "Unknown encryption format '%s', expected 'aes'",
 857                        encryptfmt);
 858             ret = -EINVAL;
 859             goto exit;
 860         }
 861         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 862
 863         crypto_opts = block_crypto_create_opts_init(
 864             Q_CRYPTO_BLOCK_FORMAT_QCOW, encryptopts, errp);
 865         if (!crypto_opts) {
 866             ret = -EINVAL;
 867             goto exit;
 868         }
 869
 870         crypto = qcrypto_block_create(crypto_opts, "encrypt.",
 871                                       NULL, NULL, NULL, errp);
 872         if (!crypto) {
 873             ret = -EINVAL;
 874             goto exit;
 875         }
 876     } else {
 877         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 878     }
 879
 880     /* write all the data */
 881     ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header), 0);
 882     if (ret != sizeof(header)) {
 883         goto exit;
 884     }
 885
 886     if (backing_file) {
 887         ret = blk_pwrite(qcow_blk, sizeof(header),
 888                          backing_file, backing_filename_len, 0);
 889         if (ret != backing_filename_len) {
 890             goto exit;
 891         }
 892     }
 893
 894     tmp = g_malloc0(BDRV_SECTOR_SIZE);
 895     for (i = 0; i < DIV_ROUND_UP(sizeof(uint64_t) * l1_size, BDRV_SECTOR_SIZE);
 896          i++) {
 897         ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
 898                          tmp, BDRV_SECTOR_SIZE, 0);
 899         if (ret != BDRV_SECTOR_SIZE) {
 900             g_free(tmp);
 901             goto exit;
 902         }
 903     }
 904
 905     g_free(tmp);
 906     ret = 0;
 907 exit:
 908     blk_unref(qcow_blk);
 909 cleanup:
 910     QDECREF(encryptopts);
 911     g_free(encryptfmt);
 912     qcrypto_block_free(crypto);
 913     qapi_free_QCryptoBlockCreateOptions(crypto_opts);
 914     g_free(backing_file);
 915     return ret;
 916 }
 917
 918 static int qcow_make_empty(BlockDriverState *bs)
 919 {
 920     BDRVQcowState *s = bs->opaque;
 921     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
 922     int ret;
 923
 924     memset(s->l1_table, 0, l1_length);
 925     if (bdrv_pwrite_sync(bs->file, s->l1_table_offset, s->l1_table,
 926             l1_length) < 0)
 927         return -1;
 928     ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length,
 929                         PREALLOC_MODE_OFF, NULL);
 930     if (ret < 0)
 931         return ret;
 932
 933     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 934     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
 935     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
 936
 937     return 0;
 938 }
 939
 940 /* XXX: put compressed sectors first, then all the cluster aligned
 941    tables to avoid losing bytes in alignment */
 942 static coroutine_fn int
 943 qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 944                            uint64_t bytes, QEMUIOVector *qiov)
 945 {
 946     BDRVQcowState *s = bs->opaque;
 947     QEMUIOVector hd_qiov;
 948     struct iovec iov;
 949     z_stream strm;
 950     int ret, out_len;
 951     uint8_t *buf, *out_buf;
 952     uint64_t cluster_offset;
 953
 954     buf = qemu_blockalign(bs, s->cluster_size);
 955     if (bytes != s->cluster_size) {
 956         if (bytes > s->cluster_size ||
 957             offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS)
 958         {
 959             qemu_vfree(buf);
 960             return -EINVAL;
 961         }
 962         /* Zero-pad last write if image size is not cluster aligned */
 963         memset(buf + bytes, 0, s->cluster_size - bytes);
 964     }
 965     qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
 966
 967     out_buf = g_malloc(s->cluster_size);
 968
 969     /* best compression, small window, no zlib header */
 970     memset(&strm, 0, sizeof(strm));
 971     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 972                        Z_DEFLATED, -12,
 973                        9, Z_DEFAULT_STRATEGY);
 974     if (ret != 0) {
 975         ret = -EINVAL;
 976         goto fail;
 977     }
 978
 979     strm.avail_in = s->cluster_size;
 980     strm.next_in = (uint8_t *)buf;
 981     strm.avail_out = s->cluster_size;
 982     strm.next_out = out_buf;
 983
 984     ret = deflate(&strm, Z_FINISH);
 985     if (ret != Z_STREAM_END && ret != Z_OK) {
 986         deflateEnd(&strm);
 987         ret = -EINVAL;
 988         goto fail;
 989     }
 990     out_len = strm.next_out - out_buf;
 991
 992     deflateEnd(&strm);
 993
 994     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 995         /* could not compress: write normal cluster */
 996         ret = qcow_co_writev(bs, offset >> BDRV_SECTOR_BITS,
 997                              bytes >> BDRV_SECTOR_BITS, qiov);
 998         if (ret < 0) {
 999             goto fail;
1000         }
1001         goto success;
1002     }
1003     qemu_co_mutex_lock(&s->lock);
1004     cluster_offset = get_cluster_offset(bs, offset, 2, out_len, 0, 0);
1005     qemu_co_mutex_unlock(&s->lock);
1006     if (cluster_offset == 0) {
1007         ret = -EIO;
1008         goto fail;
1009     }
1010     cluster_offset &= s->cluster_offset_mask;
1011
1012     iov = (struct iovec) {
1013         .iov_base   = out_buf,
1014         .iov_len    = out_len,
1015     };
1016     qemu_iovec_init_external(&hd_qiov, &iov, 1);
1017     ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
1018     if (ret < 0) {
1019         goto fail;
1020     }
1021 success:
1022     ret = 0;
1023 fail:
1024     qemu_vfree(buf);
1025     g_free(out_buf);
1026     return ret;
1027 }
1028
1029 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
1030 {
1031     BDRVQcowState *s = bs->opaque;
1032     bdi->cluster_size = s->cluster_size;
1033     return 0;
1034 }
1035
1036 static QemuOptsList qcow_create_opts = {
1037     .name = "qcow-create-opts",
1038     .head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
1039     .desc = {
1040         {
1041             .name = BLOCK_OPT_SIZE,
1042             .type = QEMU_OPT_SIZE,
1043             .help = "Virtual disk size"
1044         },
1045         {
1046             .name = BLOCK_OPT_BACKING_FILE,
1047             .type = QEMU_OPT_STRING,
1048             .help = "File name of a base image"
1049         },
1050         {
1051             .name = BLOCK_OPT_ENCRYPT,
1052             .type = QEMU_OPT_BOOL,
1053             .help = "Encrypt the image with format 'aes'. (Deprecated "
1054                     "in favor of " BLOCK_OPT_ENCRYPT_FORMAT "=aes)",
1055         },
1056         {
1057             .name = BLOCK_OPT_ENCRYPT_FORMAT,
1058             .type = QEMU_OPT_STRING,
1059             .help = "Encrypt the image, format choices: 'aes'",
1060         },
1061         BLOCK_CRYPTO_OPT_DEF_QCOW_KEY_SECRET("encrypt."),
1062         { /* end of list */ }
1063     }
1064 };
1065
1066 static BlockDriver bdrv_qcow = {
1067     .format_name        = "qcow",
1068     .instance_size      = sizeof(BDRVQcowState),
1069     .bdrv_probe         = qcow_probe,
1070     .bdrv_open          = qcow_open,
1071     .bdrv_close         = qcow_close,
1072     .bdrv_child_perm        = bdrv_format_default_perms,
1073     .bdrv_reopen_prepare    = qcow_reopen_prepare,
1074     .bdrv_create            = qcow_create,
1075     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
1076     .supports_backing       = true,
1077
1078     .bdrv_co_readv          = qcow_co_readv,
1079     .bdrv_co_writev         = qcow_co_writev,
1080     .bdrv_co_get_block_status   = qcow_co_get_block_status,
1081
1082     .bdrv_make_empty        = qcow_make_empty,
1083     .bdrv_co_pwritev_compressed = qcow_co_pwritev_compressed,
1084     .bdrv_get_info          = qcow_get_info,
1085
1086     .create_opts            = &qcow_create_opts,
1087 };
1088
1089 static void bdrv_qcow_init(void)
1090 {
1091     bdrv_register(&bdrv_qcow);
1092 }
1093
1094 block_init(bdrv_qcow_init);