xref: /openbmc/qemu/block/qcow.c (revision 764a6ee9)
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 "qemu/memalign.h"
36 #include <zlib.h>
37 #include "qapi/qmp/qdict.h"
38 #include "qapi/qmp/qstring.h"
39 #include "qapi/qobject-input-visitor.h"
40 #include "qapi/qapi-visit-block-core.h"
41 #include "crypto/block.h"
42 #include "migration/blocker.h"
43 #include "crypto.h"
44 
45 /**************************************************************/
46 /* QEMU COW block driver with compression and encryption support */
47 
48 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
49 #define QCOW_VERSION 1
50 
51 #define QCOW_CRYPT_NONE 0
52 #define QCOW_CRYPT_AES  1
53 
54 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
55 
56 typedef struct QCowHeader {
57     uint32_t magic;
58     uint32_t version;
59     uint64_t backing_file_offset;
60     uint32_t backing_file_size;
61     uint32_t mtime;
62     uint64_t size; /* in bytes */
63     uint8_t cluster_bits;
64     uint8_t l2_bits;
65     uint16_t padding;
66     uint32_t crypt_method;
67     uint64_t l1_table_offset;
68 } QEMU_PACKED QCowHeader;
69 
70 #define L2_CACHE_SIZE 16
71 
72 typedef struct BDRVQcowState {
73     int cluster_bits;
74     int cluster_size;
75     int l2_bits;
76     int l2_size;
77     unsigned int l1_size;
78     uint64_t cluster_offset_mask;
79     uint64_t l1_table_offset;
80     uint64_t *l1_table;
81     uint64_t *l2_cache;
82     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
83     uint32_t l2_cache_counts[L2_CACHE_SIZE];
84     uint8_t *cluster_cache;
85     uint8_t *cluster_data;
86     uint64_t cluster_cache_offset;
87     QCryptoBlock *crypto; /* Disk encryption format driver */
88     uint32_t crypt_method_header;
89     CoMutex lock;
90     Error *migration_blocker;
91 } BDRVQcowState;
92 
93 static QemuOptsList qcow_create_opts;
94 
95 static int coroutine_fn GRAPH_RDLOCK
96 decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
97 
98 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
99 {
100     const QCowHeader *cow_header = (const void *)buf;
101 
102     if (buf_size >= sizeof(QCowHeader) &&
103         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
104         be32_to_cpu(cow_header->version) == QCOW_VERSION)
105         return 100;
106     else
107         return 0;
108 }
109 
110 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
111                      Error **errp)
112 {
113     BDRVQcowState *s = bs->opaque;
114     unsigned int len, i, shift;
115     int ret;
116     QCowHeader header;
117     QCryptoBlockOpenOptions *crypto_opts = NULL;
118     unsigned int cflags = 0;
119     QDict *encryptopts = NULL;
120     const char *encryptfmt;
121 
122     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
123     encryptfmt = qdict_get_try_str(encryptopts, "format");
124 
125     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
126     if (ret < 0) {
127         goto fail_unlocked;
128     }
129 
130     bdrv_graph_rdlock_main_loop();
131 
132     ret = bdrv_pread(bs->file, 0, sizeof(header), &header, 0);
133     if (ret < 0) {
134         goto fail;
135     }
136     header.magic = be32_to_cpu(header.magic);
137     header.version = be32_to_cpu(header.version);
138     header.backing_file_offset = be64_to_cpu(header.backing_file_offset);
139     header.backing_file_size = be32_to_cpu(header.backing_file_size);
140     header.mtime = be32_to_cpu(header.mtime);
141     header.size = be64_to_cpu(header.size);
142     header.crypt_method = be32_to_cpu(header.crypt_method);
143     header.l1_table_offset = be64_to_cpu(header.l1_table_offset);
144 
145     if (header.magic != QCOW_MAGIC) {
146         error_setg(errp, "Image not in qcow format");
147         ret = -EINVAL;
148         goto fail;
149     }
150     if (header.version != QCOW_VERSION) {
151         error_setg(errp, "qcow (v%d) does not support qcow version %" PRIu32,
152                    QCOW_VERSION, header.version);
153         if (header.version == 2 || header.version == 3) {
154             error_append_hint(errp, "Try the 'qcow2' driver instead.\n");
155         }
156 
157         ret = -ENOTSUP;
158         goto fail;
159     }
160 
161     if (header.size <= 1) {
162         error_setg(errp, "Image size is too small (must be at least 2 bytes)");
163         ret = -EINVAL;
164         goto fail;
165     }
166     if (header.cluster_bits < 9 || header.cluster_bits > 16) {
167         error_setg(errp, "Cluster size must be between 512 and 64k");
168         ret = -EINVAL;
169         goto fail;
170     }
171 
172     /* l2_bits specifies number of entries; storing a uint64_t in each entry,
173      * so bytes = num_entries << 3. */
174     if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
175         error_setg(errp, "L2 table size must be between 512 and 64k");
176         ret = -EINVAL;
177         goto fail;
178     }
179 
180     s->crypt_method_header = header.crypt_method;
181     if (s->crypt_method_header) {
182         if (bdrv_uses_whitelist() &&
183             s->crypt_method_header == QCOW_CRYPT_AES) {
184             error_setg(errp,
185                        "Use of AES-CBC encrypted qcow images is no longer "
186                        "supported in system emulators");
187             error_append_hint(errp,
188                               "You can use 'qemu-img convert' to convert your "
189                               "image to an alternative supported format, such "
190                               "as unencrypted qcow, or raw with the LUKS "
191                               "format instead.\n");
192             ret = -ENOSYS;
193             goto fail;
194         }
195         if (s->crypt_method_header == QCOW_CRYPT_AES) {
196             if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
197                 error_setg(errp,
198                            "Header reported 'aes' encryption format but "
199                            "options specify '%s'", encryptfmt);
200                 ret = -EINVAL;
201                 goto fail;
202             }
203             qdict_put_str(encryptopts, "format", "qcow");
204             crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
205             if (!crypto_opts) {
206                 ret = -EINVAL;
207                 goto fail;
208             }
209 
210             if (flags & BDRV_O_NO_IO) {
211                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
212             }
213             s->crypto = qcrypto_block_open(crypto_opts, "encrypt.",
214                                            NULL, NULL, cflags, errp);
215             if (!s->crypto) {
216                 ret = -EINVAL;
217                 goto fail;
218             }
219         } else {
220             error_setg(errp, "invalid encryption method in qcow header");
221             ret = -EINVAL;
222             goto fail;
223         }
224         bs->encrypted = true;
225     } else {
226         if (encryptfmt) {
227             error_setg(errp, "No encryption in image header, but options "
228                        "specified format '%s'", encryptfmt);
229             ret = -EINVAL;
230             goto fail;
231         }
232     }
233     s->cluster_bits = header.cluster_bits;
234     s->cluster_size = 1 << s->cluster_bits;
235     s->l2_bits = header.l2_bits;
236     s->l2_size = 1 << s->l2_bits;
237     bs->total_sectors = header.size / 512;
238     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
239 
240     /* read the level 1 table */
241     shift = s->cluster_bits + s->l2_bits;
242     if (header.size > UINT64_MAX - (1LL << shift)) {
243         error_setg(errp, "Image too large");
244         ret = -EINVAL;
245         goto fail;
246     } else {
247         uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
248         if (l1_size > INT_MAX / sizeof(uint64_t)) {
249             error_setg(errp, "Image too large");
250             ret = -EINVAL;
251             goto fail;
252         }
253         s->l1_size = l1_size;
254     }
255 
256     s->l1_table_offset = header.l1_table_offset;
257     s->l1_table = g_try_new(uint64_t, s->l1_size);
258     if (s->l1_table == NULL) {
259         error_setg(errp, "Could not allocate memory for L1 table");
260         ret = -ENOMEM;
261         goto fail;
262     }
263 
264     ret = bdrv_pread(bs->file, s->l1_table_offset,
265                      s->l1_size * sizeof(uint64_t), s->l1_table, 0);
266     if (ret < 0) {
267         goto fail;
268     }
269 
270     for(i = 0;i < s->l1_size; i++) {
271         s->l1_table[i] = be64_to_cpu(s->l1_table[i]);
272     }
273 
274     /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
275     s->l2_cache =
276         qemu_try_blockalign(bs->file->bs,
277                             s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
278     if (s->l2_cache == NULL) {
279         error_setg(errp, "Could not allocate L2 table cache");
280         ret = -ENOMEM;
281         goto fail;
282     }
283     s->cluster_cache = g_malloc(s->cluster_size);
284     s->cluster_data = g_malloc(s->cluster_size);
285     s->cluster_cache_offset = -1;
286 
287     /* read the backing file name */
288     if (header.backing_file_offset != 0) {
289         len = header.backing_file_size;
290         if (len > 1023 || len >= sizeof(bs->backing_file)) {
291             error_setg(errp, "Backing file name too long");
292             ret = -EINVAL;
293             goto fail;
294         }
295         ret = bdrv_pread(bs->file, header.backing_file_offset, len,
296                          bs->auto_backing_file, 0);
297         if (ret < 0) {
298             goto fail;
299         }
300         bs->auto_backing_file[len] = '\0';
301         pstrcpy(bs->backing_file, sizeof(bs->backing_file),
302                 bs->auto_backing_file);
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 
310     ret = migrate_add_blocker_normal(&s->migration_blocker, errp);
311     if (ret < 0) {
312         goto fail;
313     }
314 
315     qobject_unref(encryptopts);
316     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
317     qemu_co_mutex_init(&s->lock);
318     bdrv_graph_rdunlock_main_loop();
319     return 0;
320 
321 fail:
322     bdrv_graph_rdunlock_main_loop();
323 fail_unlocked:
324     g_free(s->l1_table);
325     qemu_vfree(s->l2_cache);
326     g_free(s->cluster_cache);
327     g_free(s->cluster_data);
328     qcrypto_block_free(s->crypto);
329     qobject_unref(encryptopts);
330     qapi_free_QCryptoBlockOpenOptions(crypto_opts);
331     return ret;
332 }
333 
334 
335 /* We have nothing to do for QCOW reopen, stubs just return
336  * success */
337 static int qcow_reopen_prepare(BDRVReopenState *state,
338                                BlockReopenQueue *queue, Error **errp)
339 {
340     return 0;
341 }
342 
343 
344 /* 'allocate' is:
345  *
346  * 0 to not allocate.
347  *
348  * 1 to allocate a normal cluster (for sector-aligned byte offsets 'n_start'
349  * to 'n_end' within the cluster)
350  *
351  * 2 to allocate a compressed cluster of size
352  * 'compressed_size'. 'compressed_size' must be > 0 and <
353  * cluster_size
354  *
355  * return 0 if not allocated, 1 if *result is assigned, and negative
356  * errno on failure.
357  */
358 static int coroutine_fn GRAPH_RDLOCK
359 get_cluster_offset(BlockDriverState *bs, uint64_t offset, int allocate,
360                    int compressed_size, int n_start, int n_end,
361                    uint64_t *result)
362 {
363     BDRVQcowState *s = bs->opaque;
364     int min_index, i, j, l1_index, l2_index, ret;
365     int64_t l2_offset;
366     uint64_t *l2_table, cluster_offset, tmp;
367     uint32_t min_count;
368     int new_l2_table;
369 
370     *result = 0;
371     l1_index = offset >> (s->l2_bits + s->cluster_bits);
372     l2_offset = s->l1_table[l1_index];
373     new_l2_table = 0;
374     if (!l2_offset) {
375         if (!allocate)
376             return 0;
377         /* allocate a new l2 entry */
378         l2_offset = bdrv_co_getlength(bs->file->bs);
379         if (l2_offset < 0) {
380             return l2_offset;
381         }
382         /* round to cluster size */
383         l2_offset = QEMU_ALIGN_UP(l2_offset, s->cluster_size);
384         /* update the L1 entry */
385         s->l1_table[l1_index] = l2_offset;
386         tmp = cpu_to_be64(l2_offset);
387         BLKDBG_CO_EVENT(bs->file, BLKDBG_L1_UPDATE);
388         ret = bdrv_co_pwrite_sync(bs->file,
389                                   s->l1_table_offset + l1_index * sizeof(tmp),
390                                   sizeof(tmp), &tmp, 0);
391         if (ret < 0) {
392             return ret;
393         }
394         new_l2_table = 1;
395     }
396     for(i = 0; i < L2_CACHE_SIZE; i++) {
397         if (l2_offset == s->l2_cache_offsets[i]) {
398             /* increment the hit count */
399             if (++s->l2_cache_counts[i] == 0xffffffff) {
400                 for(j = 0; j < L2_CACHE_SIZE; j++) {
401                     s->l2_cache_counts[j] >>= 1;
402                 }
403             }
404             l2_table = s->l2_cache + (i << s->l2_bits);
405             goto found;
406         }
407     }
408     /* not found: load a new entry in the least used one */
409     min_index = 0;
410     min_count = 0xffffffff;
411     for(i = 0; i < L2_CACHE_SIZE; i++) {
412         if (s->l2_cache_counts[i] < min_count) {
413             min_count = s->l2_cache_counts[i];
414             min_index = i;
415         }
416     }
417     l2_table = s->l2_cache + (min_index << s->l2_bits);
418     BLKDBG_CO_EVENT(bs->file, BLKDBG_L2_LOAD);
419     if (new_l2_table) {
420         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
421         ret = bdrv_co_pwrite_sync(bs->file, l2_offset,
422                                   s->l2_size * sizeof(uint64_t), l2_table, 0);
423         if (ret < 0) {
424             return ret;
425         }
426     } else {
427         ret = bdrv_co_pread(bs->file, l2_offset,
428                             s->l2_size * sizeof(uint64_t), l2_table, 0);
429         if (ret < 0) {
430             return ret;
431         }
432     }
433     s->l2_cache_offsets[min_index] = l2_offset;
434     s->l2_cache_counts[min_index] = 1;
435  found:
436     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
437     cluster_offset = be64_to_cpu(l2_table[l2_index]);
438     if (!cluster_offset ||
439         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
440         if (!allocate)
441             return 0;
442         BLKDBG_CO_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
443         assert(QEMU_IS_ALIGNED(n_start | n_end, BDRV_SECTOR_SIZE));
444         /* allocate a new cluster */
445         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
446             (n_end - n_start) < s->cluster_size) {
447             /* if the cluster is already compressed, we must
448                decompress it in the case it is not completely
449                overwritten */
450             if (decompress_cluster(bs, cluster_offset) < 0) {
451                 return -EIO;
452             }
453             cluster_offset = bdrv_co_getlength(bs->file->bs);
454             if ((int64_t) cluster_offset < 0) {
455                 return cluster_offset;
456             }
457             cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
458             /* write the cluster content */
459             BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_AIO);
460             ret = bdrv_co_pwrite(bs->file, cluster_offset, s->cluster_size,
461                                  s->cluster_cache, 0);
462             if (ret < 0) {
463                 return ret;
464             }
465         } else {
466             cluster_offset = bdrv_co_getlength(bs->file->bs);
467             if ((int64_t) cluster_offset < 0) {
468                 return cluster_offset;
469             }
470             if (allocate == 1) {
471                 /* round to cluster size */
472                 cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
473                 if (cluster_offset + s->cluster_size > INT64_MAX) {
474                     return -E2BIG;
475                 }
476                 ret = bdrv_co_truncate(bs->file,
477                                        cluster_offset + s->cluster_size,
478                                        false, PREALLOC_MODE_OFF, 0, NULL);
479                 if (ret < 0) {
480                     return ret;
481                 }
482                 /* if encrypted, we must initialize the cluster
483                    content which won't be written */
484                 if (bs->encrypted &&
485                     (n_end - n_start) < s->cluster_size) {
486                     uint64_t start_offset;
487                     assert(s->crypto);
488                     start_offset = offset & ~(s->cluster_size - 1);
489                     for (i = 0; i < s->cluster_size; i += BDRV_SECTOR_SIZE) {
490                         if (i < n_start || i >= n_end) {
491                             memset(s->cluster_data, 0x00, BDRV_SECTOR_SIZE);
492                             if (qcrypto_block_encrypt(s->crypto,
493                                                       start_offset + i,
494                                                       s->cluster_data,
495                                                       BDRV_SECTOR_SIZE,
496                                                       NULL) < 0) {
497                                 return -EIO;
498                             }
499                             BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_AIO);
500                             ret = bdrv_co_pwrite(bs->file, cluster_offset + i,
501                                                  BDRV_SECTOR_SIZE,
502                                                  s->cluster_data, 0);
503                             if (ret < 0) {
504                                 return ret;
505                             }
506                         }
507                     }
508                 }
509             } else if (allocate == 2) {
510                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
511                     (uint64_t)compressed_size << (63 - s->cluster_bits);
512             }
513         }
514         /* update L2 table */
515         tmp = cpu_to_be64(cluster_offset);
516         l2_table[l2_index] = tmp;
517         if (allocate == 2) {
518             BLKDBG_CO_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
519         } else {
520             BLKDBG_CO_EVENT(bs->file, BLKDBG_L2_UPDATE);
521         }
522         ret = bdrv_co_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
523                                   sizeof(tmp), &tmp, 0);
524         if (ret < 0) {
525             return ret;
526         }
527     }
528     *result = cluster_offset;
529     return 1;
530 }
531 
532 static int coroutine_fn GRAPH_RDLOCK
533 qcow_co_block_status(BlockDriverState *bs, bool want_zero,
534                      int64_t offset, int64_t bytes, int64_t *pnum,
535                      int64_t *map, BlockDriverState **file)
536 {
537     BDRVQcowState *s = bs->opaque;
538     int index_in_cluster, ret;
539     int64_t n;
540     uint64_t cluster_offset;
541 
542     qemu_co_mutex_lock(&s->lock);
543     ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
544     qemu_co_mutex_unlock(&s->lock);
545     if (ret < 0) {
546         return ret;
547     }
548     index_in_cluster = offset & (s->cluster_size - 1);
549     n = s->cluster_size - index_in_cluster;
550     if (n > bytes) {
551         n = bytes;
552     }
553     *pnum = n;
554     if (!cluster_offset) {
555         return 0;
556     }
557     if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
558         return BDRV_BLOCK_DATA | BDRV_BLOCK_COMPRESSED;
559     }
560     if (s->crypto) {
561         return BDRV_BLOCK_DATA;
562     }
563     *map = cluster_offset | index_in_cluster;
564     *file = bs->file->bs;
565     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
566 }
567 
568 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
569                              const uint8_t *buf, int buf_size)
570 {
571     z_stream strm1, *strm = &strm1;
572     int ret, out_len;
573 
574     memset(strm, 0, sizeof(*strm));
575 
576     strm->next_in = (uint8_t *)buf;
577     strm->avail_in = buf_size;
578     strm->next_out = out_buf;
579     strm->avail_out = out_buf_size;
580 
581     ret = inflateInit2(strm, -12);
582     if (ret != Z_OK)
583         return -1;
584     ret = inflate(strm, Z_FINISH);
585     out_len = strm->next_out - out_buf;
586     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
587         out_len != out_buf_size) {
588         inflateEnd(strm);
589         return -1;
590     }
591     inflateEnd(strm);
592     return 0;
593 }
594 
595 static int coroutine_fn GRAPH_RDLOCK
596 decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
597 {
598     BDRVQcowState *s = bs->opaque;
599     int ret, csize;
600     uint64_t coffset;
601 
602     coffset = cluster_offset & s->cluster_offset_mask;
603     if (s->cluster_cache_offset != coffset) {
604         csize = cluster_offset >> (63 - s->cluster_bits);
605         csize &= (s->cluster_size - 1);
606         BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
607         ret = bdrv_co_pread(bs->file, coffset, csize, s->cluster_data, 0);
608         if (ret < 0)
609             return -1;
610         if (decompress_buffer(s->cluster_cache, s->cluster_size,
611                               s->cluster_data, csize) < 0) {
612             return -1;
613         }
614         s->cluster_cache_offset = coffset;
615     }
616     return 0;
617 }
618 
619 static void qcow_refresh_limits(BlockDriverState *bs, Error **errp)
620 {
621     /* At least encrypted images require 512-byte alignment. Apply the
622      * limit universally, rather than just on encrypted images, as
623      * it's easier to let the block layer handle rounding than to
624      * audit this code further. */
625     bs->bl.request_alignment = BDRV_SECTOR_SIZE;
626 }
627 
628 static int coroutine_fn GRAPH_RDLOCK
629 qcow_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
630                QEMUIOVector *qiov, BdrvRequestFlags flags)
631 {
632     BDRVQcowState *s = bs->opaque;
633     int offset_in_cluster;
634     int ret = 0, n;
635     uint64_t cluster_offset;
636     uint8_t *buf;
637     void *orig_buf;
638 
639     if (qiov->niov > 1) {
640         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
641         if (buf == NULL) {
642             return -ENOMEM;
643         }
644     } else {
645         orig_buf = NULL;
646         buf = (uint8_t *)qiov->iov->iov_base;
647     }
648 
649     qemu_co_mutex_lock(&s->lock);
650 
651     while (bytes != 0) {
652         /* prepare next request */
653         ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
654         if (ret < 0) {
655             break;
656         }
657         offset_in_cluster = offset & (s->cluster_size - 1);
658         n = s->cluster_size - offset_in_cluster;
659         if (n > bytes) {
660             n = bytes;
661         }
662 
663         if (!cluster_offset) {
664             if (bs->backing) {
665                 /* read from the base image */
666                 qemu_co_mutex_unlock(&s->lock);
667                 /* qcow2 emits this on bs->file instead of bs->backing */
668                 BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
669                 ret = bdrv_co_pread(bs->backing, offset, n, buf, 0);
670                 qemu_co_mutex_lock(&s->lock);
671                 if (ret < 0) {
672                     break;
673                 }
674             } else {
675                 /* Note: in this case, no need to wait */
676                 memset(buf, 0, n);
677             }
678         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
679             /* add AIO support for compressed blocks ? */
680             if (decompress_cluster(bs, cluster_offset) < 0) {
681                 ret = -EIO;
682                 break;
683             }
684             memcpy(buf, s->cluster_cache + offset_in_cluster, n);
685         } else {
686             if ((cluster_offset & 511) != 0) {
687                 ret = -EIO;
688                 break;
689             }
690             qemu_co_mutex_unlock(&s->lock);
691             BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_AIO);
692             ret = bdrv_co_pread(bs->file, cluster_offset + offset_in_cluster,
693                                 n, buf, 0);
694             qemu_co_mutex_lock(&s->lock);
695             if (ret < 0) {
696                 break;
697             }
698             if (bs->encrypted) {
699                 assert(s->crypto);
700                 if (qcrypto_block_decrypt(s->crypto,
701                                           offset, buf, n, NULL) < 0) {
702                     ret = -EIO;
703                     break;
704                 }
705             }
706         }
707         ret = 0;
708 
709         bytes -= n;
710         offset += n;
711         buf += n;
712     }
713 
714     qemu_co_mutex_unlock(&s->lock);
715 
716     if (qiov->niov > 1) {
717         qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
718         qemu_vfree(orig_buf);
719     }
720 
721     return ret;
722 }
723 
724 static int coroutine_fn GRAPH_RDLOCK
725 qcow_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
726                 QEMUIOVector *qiov, BdrvRequestFlags flags)
727 {
728     BDRVQcowState *s = bs->opaque;
729     int offset_in_cluster;
730     uint64_t cluster_offset;
731     int ret = 0, n;
732     uint8_t *buf;
733     void *orig_buf;
734 
735     s->cluster_cache_offset = -1; /* disable compressed cache */
736 
737     /* We must always copy the iov when encrypting, so we
738      * don't modify the original data buffer during encryption */
739     if (bs->encrypted || qiov->niov > 1) {
740         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
741         if (buf == NULL) {
742             return -ENOMEM;
743         }
744         qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
745     } else {
746         orig_buf = NULL;
747         buf = (uint8_t *)qiov->iov->iov_base;
748     }
749 
750     qemu_co_mutex_lock(&s->lock);
751 
752     while (bytes != 0) {
753         offset_in_cluster = offset & (s->cluster_size - 1);
754         n = s->cluster_size - offset_in_cluster;
755         if (n > bytes) {
756             n = bytes;
757         }
758         ret = get_cluster_offset(bs, offset, 1, 0, offset_in_cluster,
759                                  offset_in_cluster + n, &cluster_offset);
760         if (ret < 0) {
761             break;
762         }
763         if (!cluster_offset || (cluster_offset & 511) != 0) {
764             ret = -EIO;
765             break;
766         }
767         if (bs->encrypted) {
768             assert(s->crypto);
769             if (qcrypto_block_encrypt(s->crypto, offset, buf, n, NULL) < 0) {
770                 ret = -EIO;
771                 break;
772             }
773         }
774 
775         qemu_co_mutex_unlock(&s->lock);
776         BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_AIO);
777         ret = bdrv_co_pwrite(bs->file, cluster_offset + offset_in_cluster,
778                              n, buf, 0);
779         qemu_co_mutex_lock(&s->lock);
780         if (ret < 0) {
781             break;
782         }
783         ret = 0;
784 
785         bytes -= n;
786         offset += n;
787         buf += n;
788     }
789     qemu_co_mutex_unlock(&s->lock);
790 
791     qemu_vfree(orig_buf);
792 
793     return ret;
794 }
795 
796 static void qcow_close(BlockDriverState *bs)
797 {
798     BDRVQcowState *s = bs->opaque;
799 
800     qcrypto_block_free(s->crypto);
801     s->crypto = NULL;
802     g_free(s->l1_table);
803     qemu_vfree(s->l2_cache);
804     g_free(s->cluster_cache);
805     g_free(s->cluster_data);
806 
807     migrate_del_blocker(&s->migration_blocker);
808 }
809 
810 static int coroutine_fn GRAPH_UNLOCKED
811 qcow_co_create(BlockdevCreateOptions *opts, Error **errp)
812 {
813     BlockdevCreateOptionsQcow *qcow_opts;
814     int header_size, backing_filename_len, l1_size, shift, i;
815     QCowHeader header;
816     uint8_t *tmp;
817     int64_t total_size = 0;
818     int ret;
819     BlockDriverState *bs;
820     BlockBackend *qcow_blk;
821     QCryptoBlock *crypto = NULL;
822 
823     assert(opts->driver == BLOCKDEV_DRIVER_QCOW);
824     qcow_opts = &opts->u.qcow;
825 
826     /* Sanity checks */
827     total_size = qcow_opts->size;
828     if (total_size == 0) {
829         error_setg(errp, "Image size is too small, cannot be zero length");
830         return -EINVAL;
831     }
832 
833     if (qcow_opts->encrypt &&
834         qcow_opts->encrypt->format != QCRYPTO_BLOCK_FORMAT_QCOW)
835     {
836         error_setg(errp, "Unsupported encryption format");
837         return -EINVAL;
838     }
839 
840     /* Create BlockBackend to write to the image */
841     bs = bdrv_co_open_blockdev_ref(qcow_opts->file, errp);
842     if (bs == NULL) {
843         return -EIO;
844     }
845 
846     qcow_blk = blk_co_new_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE,
847                                   BLK_PERM_ALL, errp);
848     if (!qcow_blk) {
849         ret = -EPERM;
850         goto exit;
851     }
852     blk_set_allow_write_beyond_eof(qcow_blk, true);
853 
854     /* Create image format */
855     memset(&header, 0, sizeof(header));
856     header.magic = cpu_to_be32(QCOW_MAGIC);
857     header.version = cpu_to_be32(QCOW_VERSION);
858     header.size = cpu_to_be64(total_size);
859     header_size = sizeof(header);
860     backing_filename_len = 0;
861     if (qcow_opts->backing_file) {
862         if (strcmp(qcow_opts->backing_file, "fat:")) {
863             header.backing_file_offset = cpu_to_be64(header_size);
864             backing_filename_len = strlen(qcow_opts->backing_file);
865             header.backing_file_size = cpu_to_be32(backing_filename_len);
866             header_size += backing_filename_len;
867         } else {
868             /* special backing file for vvfat */
869             qcow_opts->backing_file = NULL;
870         }
871         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
872                                     unmodified sectors */
873         header.l2_bits = 12; /* 32 KB L2 tables */
874     } else {
875         header.cluster_bits = 12; /* 4 KB clusters */
876         header.l2_bits = 9; /* 4 KB L2 tables */
877     }
878     header_size = (header_size + 7) & ~7;
879     shift = header.cluster_bits + header.l2_bits;
880     l1_size = (total_size + (1LL << shift) - 1) >> shift;
881 
882     header.l1_table_offset = cpu_to_be64(header_size);
883 
884     if (qcow_opts->encrypt) {
885         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
886 
887         crypto = qcrypto_block_create(qcow_opts->encrypt, "encrypt.",
888                                       NULL, NULL, NULL, 0, errp);
889         if (!crypto) {
890             ret = -EINVAL;
891             goto exit;
892         }
893     } else {
894         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
895     }
896 
897     /* write all the data */
898     ret = blk_co_pwrite(qcow_blk, 0, sizeof(header), &header, 0);
899     if (ret < 0) {
900         goto exit;
901     }
902 
903     if (qcow_opts->backing_file) {
904         ret = blk_co_pwrite(qcow_blk, sizeof(header), backing_filename_len,
905                             qcow_opts->backing_file, 0);
906         if (ret < 0) {
907             goto exit;
908         }
909     }
910 
911     tmp = g_malloc0(BDRV_SECTOR_SIZE);
912     for (i = 0; i < DIV_ROUND_UP(sizeof(uint64_t) * l1_size, BDRV_SECTOR_SIZE);
913          i++) {
914         ret = blk_co_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
915                             BDRV_SECTOR_SIZE, tmp, 0);
916         if (ret < 0) {
917             g_free(tmp);
918             goto exit;
919         }
920     }
921 
922     g_free(tmp);
923     ret = 0;
924 exit:
925     blk_co_unref(qcow_blk);
926     bdrv_co_unref(bs);
927     qcrypto_block_free(crypto);
928     return ret;
929 }
930 
931 static int coroutine_fn GRAPH_UNLOCKED
932 qcow_co_create_opts(BlockDriver *drv, const char *filename,
933                     QemuOpts *opts, Error **errp)
934 {
935     BlockdevCreateOptions *create_options = NULL;
936     BlockDriverState *bs = NULL;
937     QDict *qdict = NULL;
938     Visitor *v;
939     const char *val;
940     int ret;
941     char *backing_fmt;
942 
943     static const QDictRenames opt_renames[] = {
944         { BLOCK_OPT_BACKING_FILE,       "backing-file" },
945         { BLOCK_OPT_ENCRYPT,            BLOCK_OPT_ENCRYPT_FORMAT },
946         { NULL, NULL },
947     };
948 
949     /*
950      * We can't actually store a backing format, but can check that
951      * the user's request made sense.
952      */
953     backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT);
954     if (backing_fmt && !bdrv_find_format(backing_fmt)) {
955         error_setg(errp, "unrecognized backing format '%s'", backing_fmt);
956         ret = -EINVAL;
957         goto fail;
958     }
959 
960     /* Parse options and convert legacy syntax */
961     qdict = qemu_opts_to_qdict_filtered(opts, NULL, &qcow_create_opts, true);
962 
963     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT);
964     if (val && !strcmp(val, "on")) {
965         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT, "qcow");
966     } else if (val && !strcmp(val, "off")) {
967         qdict_del(qdict, BLOCK_OPT_ENCRYPT);
968     }
969 
970     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT);
971     if (val && !strcmp(val, "aes")) {
972         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT, "qcow");
973     }
974 
975     if (!qdict_rename_keys(qdict, opt_renames, errp)) {
976         ret = -EINVAL;
977         goto fail;
978     }
979 
980     /* Create and open the file (protocol layer) */
981     ret = bdrv_co_create_file(filename, opts, errp);
982     if (ret < 0) {
983         goto fail;
984     }
985 
986     bs = bdrv_co_open(filename, NULL, NULL,
987                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
988     if (bs == NULL) {
989         ret = -EIO;
990         goto fail;
991     }
992 
993     /* Now get the QAPI type BlockdevCreateOptions */
994     qdict_put_str(qdict, "driver", "qcow");
995     qdict_put_str(qdict, "file", bs->node_name);
996 
997     v = qobject_input_visitor_new_flat_confused(qdict, errp);
998     if (!v) {
999         ret = -EINVAL;
1000         goto fail;
1001     }
1002 
1003     visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
1004     visit_free(v);
1005     if (!create_options) {
1006         ret = -EINVAL;
1007         goto fail;
1008     }
1009 
1010     /* Silently round up size */
1011     assert(create_options->driver == BLOCKDEV_DRIVER_QCOW);
1012     create_options->u.qcow.size =
1013         ROUND_UP(create_options->u.qcow.size, BDRV_SECTOR_SIZE);
1014 
1015     /* Create the qcow image (format layer) */
1016     ret = qcow_co_create(create_options, errp);
1017     if (ret < 0) {
1018         goto fail;
1019     }
1020 
1021     ret = 0;
1022 fail:
1023     g_free(backing_fmt);
1024     qobject_unref(qdict);
1025     bdrv_co_unref(bs);
1026     qapi_free_BlockdevCreateOptions(create_options);
1027     return ret;
1028 }
1029 
1030 static int GRAPH_RDLOCK qcow_make_empty(BlockDriverState *bs)
1031 {
1032     BDRVQcowState *s = bs->opaque;
1033     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
1034     int ret;
1035 
1036     memset(s->l1_table, 0, l1_length);
1037     if (bdrv_pwrite_sync(bs->file, s->l1_table_offset, l1_length, s->l1_table,
1038                          0) < 0)
1039         return -1;
1040     ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length, false,
1041                         PREALLOC_MODE_OFF, 0, NULL);
1042     if (ret < 0)
1043         return ret;
1044 
1045     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
1046     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
1047     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
1048 
1049     return 0;
1050 }
1051 
1052 /* XXX: put compressed sectors first, then all the cluster aligned
1053    tables to avoid losing bytes in alignment */
1054 static int coroutine_fn GRAPH_RDLOCK
1055 qcow_co_pwritev_compressed(BlockDriverState *bs, int64_t offset, int64_t bytes,
1056                            QEMUIOVector *qiov)
1057 {
1058     BDRVQcowState *s = bs->opaque;
1059     z_stream strm;
1060     int ret, out_len;
1061     uint8_t *buf, *out_buf;
1062     uint64_t cluster_offset;
1063 
1064     buf = qemu_blockalign(bs, s->cluster_size);
1065     if (bytes != s->cluster_size) {
1066         if (bytes > s->cluster_size ||
1067             offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS)
1068         {
1069             qemu_vfree(buf);
1070             return -EINVAL;
1071         }
1072         /* Zero-pad last write if image size is not cluster aligned */
1073         memset(buf + bytes, 0, s->cluster_size - bytes);
1074     }
1075     qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
1076 
1077     out_buf = g_malloc(s->cluster_size);
1078 
1079     /* best compression, small window, no zlib header */
1080     memset(&strm, 0, sizeof(strm));
1081     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
1082                        Z_DEFLATED, -12,
1083                        9, Z_DEFAULT_STRATEGY);
1084     if (ret != 0) {
1085         ret = -EINVAL;
1086         goto fail;
1087     }
1088 
1089     strm.avail_in = s->cluster_size;
1090     strm.next_in = (uint8_t *)buf;
1091     strm.avail_out = s->cluster_size;
1092     strm.next_out = out_buf;
1093 
1094     ret = deflate(&strm, Z_FINISH);
1095     if (ret != Z_STREAM_END && ret != Z_OK) {
1096         deflateEnd(&strm);
1097         ret = -EINVAL;
1098         goto fail;
1099     }
1100     out_len = strm.next_out - out_buf;
1101 
1102     deflateEnd(&strm);
1103 
1104     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
1105         /* could not compress: write normal cluster */
1106         ret = qcow_co_pwritev(bs, offset, bytes, qiov, 0);
1107         if (ret < 0) {
1108             goto fail;
1109         }
1110         goto success;
1111     }
1112     qemu_co_mutex_lock(&s->lock);
1113     ret = get_cluster_offset(bs, offset, 2, out_len, 0, 0, &cluster_offset);
1114     qemu_co_mutex_unlock(&s->lock);
1115     if (ret < 0) {
1116         goto fail;
1117     }
1118     if (cluster_offset == 0) {
1119         ret = -EIO;
1120         goto fail;
1121     }
1122     cluster_offset &= s->cluster_offset_mask;
1123 
1124     BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
1125     ret = bdrv_co_pwrite(bs->file, cluster_offset, out_len, out_buf, 0);
1126     if (ret < 0) {
1127         goto fail;
1128     }
1129 success:
1130     ret = 0;
1131 fail:
1132     qemu_vfree(buf);
1133     g_free(out_buf);
1134     return ret;
1135 }
1136 
1137 static int coroutine_fn
1138 qcow_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
1139 {
1140     BDRVQcowState *s = bs->opaque;
1141     bdi->cluster_size = s->cluster_size;
1142     return 0;
1143 }
1144 
1145 static QemuOptsList qcow_create_opts = {
1146     .name = "qcow-create-opts",
1147     .head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
1148     .desc = {
1149         {
1150             .name = BLOCK_OPT_SIZE,
1151             .type = QEMU_OPT_SIZE,
1152             .help = "Virtual disk size"
1153         },
1154         {
1155             .name = BLOCK_OPT_BACKING_FILE,
1156             .type = QEMU_OPT_STRING,
1157             .help = "File name of a base image"
1158         },
1159         {
1160             .name = BLOCK_OPT_BACKING_FMT,
1161             .type = QEMU_OPT_STRING,
1162             .help = "Format of the backing image",
1163         },
1164         {
1165             .name = BLOCK_OPT_ENCRYPT,
1166             .type = QEMU_OPT_BOOL,
1167             .help = "Encrypt the image with format 'aes'. (Deprecated "
1168                     "in favor of " BLOCK_OPT_ENCRYPT_FORMAT "=aes)",
1169         },
1170         {
1171             .name = BLOCK_OPT_ENCRYPT_FORMAT,
1172             .type = QEMU_OPT_STRING,
1173             .help = "Encrypt the image, format choices: 'aes'",
1174         },
1175         BLOCK_CRYPTO_OPT_DEF_QCOW_KEY_SECRET("encrypt."),
1176         { /* end of list */ }
1177     }
1178 };
1179 
1180 static const char *const qcow_strong_runtime_opts[] = {
1181     "encrypt." BLOCK_CRYPTO_OPT_QCOW_KEY_SECRET,
1182 
1183     NULL
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_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     .is_format              = true,
1198     .supports_backing       = true,
1199     .bdrv_refresh_limits    = qcow_refresh_limits,
1200 
1201     .bdrv_co_preadv         = qcow_co_preadv,
1202     .bdrv_co_pwritev        = qcow_co_pwritev,
1203     .bdrv_co_block_status   = qcow_co_block_status,
1204 
1205     .bdrv_make_empty        = qcow_make_empty,
1206     .bdrv_co_pwritev_compressed = qcow_co_pwritev_compressed,
1207     .bdrv_co_get_info       = qcow_co_get_info,
1208 
1209     .create_opts            = &qcow_create_opts,
1210     .strong_runtime_opts    = qcow_strong_runtime_opts,
1211 };
1212 
1213 static void bdrv_qcow_init(void)
1214 {
1215     bdrv_register(&bdrv_qcow);
1216 }
1217 
1218 block_init(bdrv_qcow_init);
1219