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-common.h"
   25: #include "block_int.h"
   26: #include <zlib.h>
   27: #include "aes.h"
   28: 
   29: /**************************************************************/
   30: /* QEMU COW block driver with compression and encryption support */
   31: 
   32: #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
   33: #define QCOW_VERSION 1
   34: 
   35: #define QCOW_CRYPT_NONE 0
   36: #define QCOW_CRYPT_AES  1
   37: 
   38: #define QCOW_OFLAG_COMPRESSED (1LL << 63)
   39: 
   40: typedef struct QCowHeader {
   41:     uint32_t magic;
   42:     uint32_t version;
   43:     uint64_t backing_file_offset;
   44:     uint32_t backing_file_size;
   45:     uint32_t mtime;
   46:     uint64_t size; /* in bytes */
   47:     uint8_t cluster_bits;
   48:     uint8_t l2_bits;
   49:     uint32_t crypt_method;
   50:     uint64_t l1_table_offset;
   51: } QCowHeader;
   52: 
   53: #define L2_CACHE_SIZE 16
   54: 
   55: typedef struct BDRVQcowState {
   56:     BlockDriverState *hd;
   57:     int cluster_bits;
   58:     int cluster_size;
   59:     int cluster_sectors;
   60:     int l2_bits;
   61:     int l2_size;
   62:     int l1_size;
   63:     uint64_t cluster_offset_mask;
   64:     uint64_t l1_table_offset;
   65:     uint64_t *l1_table;
   66:     uint64_t *l2_cache;
   67:     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
   68:     uint32_t l2_cache_counts[L2_CACHE_SIZE];
   69:     uint8_t *cluster_cache;
   70:     uint8_t *cluster_data;
   71:     uint64_t cluster_cache_offset;
   72:     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
   73:     uint32_t crypt_method_header;
   74:     AES_KEY aes_encrypt_key;
   75:     AES_KEY aes_decrypt_key;
   76: } BDRVQcowState;
   77: 
   78: static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
   79: 
   80: static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
   81: {
   82:     const QCowHeader *cow_header = (const void *)buf;
   83: 
   84:     if (buf_size >= sizeof(QCowHeader) &&
   85:         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
   86:         be32_to_cpu(cow_header->version) == QCOW_VERSION)
   87:         return 100;
   88:     else
   89:         return 0;
   90: }
   91: 
   92: static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
   93: {
   94:     BDRVQcowState *s = bs->opaque;
   95:     int len, i, shift, ret;
   96:     QCowHeader header;
   97: 
   98:     ret = bdrv_file_open(&s->hd, filename, flags);
   99:     if (ret < 0)
  100:         return ret;
  101:     if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
  102:         goto fail;
  103:     be32_to_cpus(&header.magic);
  104:     be32_to_cpus(&header.version);
  105:     be64_to_cpus(&header.backing_file_offset);
  106:     be32_to_cpus(&header.backing_file_size);
  107:     be32_to_cpus(&header.mtime);
  108:     be64_to_cpus(&header.size);
  109:     be32_to_cpus(&header.crypt_method);
  110:     be64_to_cpus(&header.l1_table_offset);
  111: 
  112:     if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
  113:         goto fail;
  114:     if (header.size <= 1 || header.cluster_bits < 9)
  115:         goto fail;
  116:     if (header.crypt_method > QCOW_CRYPT_AES)
  117:         goto fail;
  118:     s->crypt_method_header = header.crypt_method;
  119:     if (s->crypt_method_header)
  120:         bs->encrypted = 1;
  121:     s->cluster_bits = header.cluster_bits;
  122:     s->cluster_size = 1 << s->cluster_bits;
  123:     s->cluster_sectors = 1 << (s->cluster_bits - 9);
  124:     s->l2_bits = header.l2_bits;
  125:     s->l2_size = 1 << s->l2_bits;
  126:     bs->total_sectors = header.size / 512;
  127:     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
  128: 
  129:     /* read the level 1 table */
  130:     shift = s->cluster_bits + s->l2_bits;
  131:     s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
  132: 
  133:     s->l1_table_offset = header.l1_table_offset;
  134:     s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
  135:     if (!s->l1_table)
  136:         goto fail;
  137:     if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
  138:         s->l1_size * sizeof(uint64_t))
  139:         goto fail;
  140:     for(i = 0;i < s->l1_size; i++) {
  141:         be64_to_cpus(&s->l1_table[i]);
  142:     }
  143:     /* alloc L2 cache */
  144:     s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
  145:     if (!s->l2_cache)
  146:         goto fail;
  147:     s->cluster_cache = qemu_malloc(s->cluster_size);
  148:     if (!s->cluster_cache)
  149:         goto fail;
  150:     s->cluster_data = qemu_malloc(s->cluster_size);
  151:     if (!s->cluster_data)
  152:         goto fail;
  153:     s->cluster_cache_offset = -1;
  154: 
  155:     /* read the backing file name */
  156:     if (header.backing_file_offset != 0) {
  157:         len = header.backing_file_size;
  158:         if (len > 1023)
  159:             len = 1023;
  160:         if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
  161:             goto fail;
  162:         bs->backing_file[len] = '\0';
  163:     }
  164:     return 0;
  165: 
  166:  fail:
  167:     qemu_free(s->l1_table);
  168:     qemu_free(s->l2_cache);
  169:     qemu_free(s->cluster_cache);
  170:     qemu_free(s->cluster_data);
  171:     bdrv_delete(s->hd);
  172:     return -1;
  173: }
  174: 
  175: static int qcow_set_key(BlockDriverState *bs, const char *key)
  176: {
  177:     BDRVQcowState *s = bs->opaque;
  178:     uint8_t keybuf[16];
  179:     int len, i;
  180: 
  181:     memset(keybuf, 0, 16);
  182:     len = strlen(key);
  183:     if (len > 16)
  184:         len = 16;
  185:     /* XXX: we could compress the chars to 7 bits to increase
  186:        entropy */
  187:     for(i = 0;i < len;i++) {
  188:         keybuf[i] = key[i];
  189:     }
  190:     s->crypt_method = s->crypt_method_header;
  191: 
  192:     if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
  193:         return -1;
  194:     if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
  195:         return -1;
  196: #if 0
  197:     /* test */
  198:     {
  199:         uint8_t in[16];
  200:         uint8_t out[16];
  201:         uint8_t tmp[16];
  202:         for(i=0;i<16;i++)
  203:             in[i] = i;
  204:         AES_encrypt(in, tmp, &s->aes_encrypt_key);
  205:         AES_decrypt(tmp, out, &s->aes_decrypt_key);
  206:         for(i = 0; i < 16; i++)
  207:             printf(" %02x", tmp[i]);
  208:         printf("\n");
  209:         for(i = 0; i < 16; i++)
  210:             printf(" %02x", out[i]);
  211:         printf("\n");
  212:     }
  213: #endif
  214:     return 0;
  215: }
  216: 
  217: /* The crypt function is compatible with the linux cryptoloop
  218:    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
  219:    supported */
  220: static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
  221:                             uint8_t *out_buf, const uint8_t *in_buf,
  222:                             int nb_sectors, int enc,
  223:                             const AES_KEY *key)
  224: {
  225:     union {
  226:         uint64_t ll[2];
  227:         uint8_t b[16];
  228:     } ivec;
  229:     int i;
  230: 
  231:     for(i = 0; i < nb_sectors; i++) {
  232:         ivec.ll[0] = cpu_to_le64(sector_num);
  233:         ivec.ll[1] = 0;
  234:         AES_cbc_encrypt(in_buf, out_buf, 512, key,
  235:                         ivec.b, enc);
  236:         sector_num++;
  237:         in_buf += 512;
  238:         out_buf += 512;
  239:     }
  240: }
  241: 
  242: /* 'allocate' is:
  243:  *
  244:  * 0 to not allocate.
  245:  *
  246:  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
  247:  * 'n_end')
  248:  *
  249:  * 2 to allocate a compressed cluster of size
  250:  * 'compressed_size'. 'compressed_size' must be > 0 and <
  251:  * cluster_size
  252:  *
  253:  * return 0 if not allocated.
  254:  */
  255: static uint64_t get_cluster_offset(BlockDriverState *bs,
  256:                                    uint64_t offset, int allocate,
  257:                                    int compressed_size,
  258:                                    int n_start, int n_end)
  259: {
  260:     BDRVQcowState *s = bs->opaque;
  261:     int min_index, i, j, l1_index, l2_index;
  262:     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
  263:     uint32_t min_count;
  264:     int new_l2_table;
  265: 
  266:     l1_index = offset >> (s->l2_bits + s->cluster_bits);
  267:     l2_offset = s->l1_table[l1_index];
  268:     new_l2_table = 0;
  269:     if (!l2_offset) {
  270:         if (!allocate)
  271:             return 0;
  272:         /* allocate a new l2 entry */
  273:         l2_offset = bdrv_getlength(s->hd);
  274:         /* round to cluster size */
  275:         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
  276:         /* update the L1 entry */
  277:         s->l1_table[l1_index] = l2_offset;
  278:         tmp = cpu_to_be64(l2_offset);
  279:         if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
  280:                         &tmp, sizeof(tmp)) != sizeof(tmp))
  281:             return 0;
  282:         new_l2_table = 1;
  283:     }
  284:     for(i = 0; i < L2_CACHE_SIZE; i++) {
  285:         if (l2_offset == s->l2_cache_offsets[i]) {
  286:             /* increment the hit count */
  287:             if (++s->l2_cache_counts[i] == 0xffffffff) {
  288:                 for(j = 0; j < L2_CACHE_SIZE; j++) {
  289:                     s->l2_cache_counts[j] >>= 1;
  290:                 }
  291:             }
  292:             l2_table = s->l2_cache + (i << s->l2_bits);
  293:             goto found;
  294:         }
  295:     }
  296:     /* not found: load a new entry in the least used one */
  297:     min_index = 0;
  298:     min_count = 0xffffffff;
  299:     for(i = 0; i < L2_CACHE_SIZE; i++) {
  300:         if (s->l2_cache_counts[i] < min_count) {
  301:             min_count = s->l2_cache_counts[i];
  302:             min_index = i;
  303:         }
  304:     }
  305:     l2_table = s->l2_cache + (min_index << s->l2_bits);
  306:     if (new_l2_table) {
  307:         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
  308:         if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
  309:             s->l2_size * sizeof(uint64_t))
  310:             return 0;
  311:     } else {
  312:         if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
  313:             s->l2_size * sizeof(uint64_t))
  314:             return 0;
  315:     }
  316:     s->l2_cache_offsets[min_index] = l2_offset;
  317:     s->l2_cache_counts[min_index] = 1;
  318:  found:
  319:     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
  320:     cluster_offset = be64_to_cpu(l2_table[l2_index]);
  321:     if (!cluster_offset ||
  322:         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
  323:         if (!allocate)
  324:             return 0;
  325:         /* allocate a new cluster */
  326:         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
  327:             (n_end - n_start) < s->cluster_sectors) {
  328:             /* if the cluster is already compressed, we must
  329:                decompress it in the case it is not completely
  330:                overwritten */
  331:             if (decompress_cluster(s, cluster_offset) < 0)
  332:                 return 0;
  333:             cluster_offset = bdrv_getlength(s->hd);
  334:             cluster_offset = (cluster_offset + s->cluster_size - 1) &
  335:                 ~(s->cluster_size - 1);
  336:             /* write the cluster content */
  337:             if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) !=
  338:                 s->cluster_size)
  339:                 return -1;
  340:         } else {
  341:             cluster_offset = bdrv_getlength(s->hd);
  342:             if (allocate == 1) {
  343:                 /* round to cluster size */
  344:                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
  345:                     ~(s->cluster_size - 1);
  346:                 bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
  347:                 /* if encrypted, we must initialize the cluster
  348:                    content which won't be written */
  349:                 if (s->crypt_method &&
  350:                     (n_end - n_start) < s->cluster_sectors) {
  351:                     uint64_t start_sect;
  352:                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
  353:                     memset(s->cluster_data + 512, 0x00, 512);
  354:                     for(i = 0; i < s->cluster_sectors; i++) {
  355:                         if (i < n_start || i >= n_end) {
  356:                             encrypt_sectors(s, start_sect + i,
  357:                                             s->cluster_data,
  358:                                             s->cluster_data + 512, 1, 1,
  359:                                             &s->aes_encrypt_key);
  360:                             if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
  361:                                             s->cluster_data, 512) != 512)
  362:                                 return -1;
  363:                         }
  364:                     }
  365:                 }
  366:             } else {
  367:                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
  368:                     (uint64_t)compressed_size << (63 - s->cluster_bits);
  369:             }
  370:         }
  371:         /* update L2 table */
  372:         tmp = cpu_to_be64(cluster_offset);
  373:         l2_table[l2_index] = tmp;
  374:         if (bdrv_pwrite(s->hd,
  375:                         l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
  376:             return 0;
  377:     }
  378:     return cluster_offset;
  379: }
  380: 
  381: static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
  382:                              int nb_sectors, int *pnum)
  383: {
  384:     BDRVQcowState *s = bs->opaque;
  385:     int index_in_cluster, n;
  386:     uint64_t cluster_offset;
  387: 
  388:     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
  389:     index_in_cluster = sector_num & (s->cluster_sectors - 1);
  390:     n = s->cluster_sectors - index_in_cluster;
  391:     if (n > nb_sectors)
  392:         n = nb_sectors;
  393:     *pnum = n;
  394:     return (cluster_offset != 0);
  395: }
  396: 
  397: static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
  398:                              const uint8_t *buf, int buf_size)
  399: {
  400:     z_stream strm1, *strm = &strm1;
  401:     int ret, out_len;
  402: 
  403:     memset(strm, 0, sizeof(*strm));
  404: 
  405:     strm->next_in = (uint8_t *)buf;
  406:     strm->avail_in = buf_size;
  407:     strm->next_out = out_buf;
  408:     strm->avail_out = out_buf_size;
  409: 
  410:     ret = inflateInit2(strm, -12);
  411:     if (ret != Z_OK)
  412:         return -1;
  413:     ret = inflate(strm, Z_FINISH);
  414:     out_len = strm->next_out - out_buf;
  415:     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
  416:         out_len != out_buf_size) {
  417:         inflateEnd(strm);
  418:         return -1;
  419:     }
  420:     inflateEnd(strm);
  421:     return 0;
  422: }
  423: 
  424: static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
  425: {
  426:     int ret, csize;
  427:     uint64_t coffset;
  428: 
  429:     coffset = cluster_offset & s->cluster_offset_mask;
  430:     if (s->cluster_cache_offset != coffset) {
  431:         csize = cluster_offset >> (63 - s->cluster_bits);
  432:         csize &= (s->cluster_size - 1);
  433:         ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
  434:         if (ret != csize)
  435:             return -1;
  436:         if (decompress_buffer(s->cluster_cache, s->cluster_size,
  437:                               s->cluster_data, csize) < 0) {
  438:             return -1;
  439:         }
  440:         s->cluster_cache_offset = coffset;
  441:     }
  442:     return 0;
  443: }
  444: 
  445: #if 0
  446: 
  447: static int qcow_read(BlockDriverState *bs, int64_t sector_num,
  448:                      uint8_t *buf, int nb_sectors)
  449: {
  450:     BDRVQcowState *s = bs->opaque;
  451:     int ret, index_in_cluster, n;
  452:     uint64_t cluster_offset;
  453: 
  454:     while (nb_sectors > 0) {
  455:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
  456:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
  457:         n = s->cluster_sectors - index_in_cluster;
  458:         if (n > nb_sectors)
  459:             n = nb_sectors;
  460:         if (!cluster_offset) {
  461:             if (bs->backing_hd) {
  462:                 /* read from the base image */
  463:                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
  464:                 if (ret < 0)
  465:                     return -1;
  466:             } else {
  467:                 memset(buf, 0, 512 * n);
  468:             }
  469:         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
  470:             if (decompress_cluster(s, cluster_offset) < 0)
  471:                 return -1;
  472:             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
  473:         } else {
  474:             ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
  475:             if (ret != n * 512)
  476:                 return -1;
  477:             if (s->crypt_method) {
  478:                 encrypt_sectors(s, sector_num, buf, buf, n, 0,
  479:                                 &s->aes_decrypt_key);
  480:             }
  481:         }
  482:         nb_sectors -= n;
  483:         sector_num += n;
  484:         buf += n * 512;
  485:     }
  486:     return 0;
  487: }
  488: #endif
  489: 
  490: static int qcow_write(BlockDriverState *bs, int64_t sector_num,
  491:                      const uint8_t *buf, int nb_sectors)
  492: {
  493:     BDRVQcowState *s = bs->opaque;
  494:     int ret, index_in_cluster, n;
  495:     uint64_t cluster_offset;
  496: 
  497:     while (nb_sectors > 0) {
  498:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
  499:         n = s->cluster_sectors - index_in_cluster;
  500:         if (n > nb_sectors)
  501:             n = nb_sectors;
  502:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
  503:                                             index_in_cluster,
  504:                                             index_in_cluster + n);
  505:         if (!cluster_offset)
  506:             return -1;
  507:         if (s->crypt_method) {
  508:             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
  509:                             &s->aes_encrypt_key);
  510:             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
  511:                               s->cluster_data, n * 512);
  512:         } else {
  513:             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
  514:         }
  515:         if (ret != n * 512)
  516:             return -1;
  517:         nb_sectors -= n;
  518:         sector_num += n;
  519:         buf += n * 512;
  520:     }
  521:     s->cluster_cache_offset = -1; /* disable compressed cache */
  522:     return 0;
  523: }
  524: 
  525: typedef struct QCowAIOCB {
  526:     BlockDriverAIOCB common;
  527:     int64_t sector_num;
  528:     uint8_t *buf;
  529:     int nb_sectors;
  530:     int n;
  531:     uint64_t cluster_offset;
  532:     uint8_t *cluster_data;
  533:     BlockDriverAIOCB *hd_aiocb;
  534: } QCowAIOCB;
  535: 
  536: static void qcow_aio_read_cb(void *opaque, int ret)
  537: {