block/cloop.c

   1 /*
   2  * QEMU Block driver for CLOOP images
   3  *
   4  * Copyright (c) 2004 Johannes E. Schindelin
   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 "block/block_int.h"
  28 #include "qemu/module.h"
  29 #include "qemu/bswap.h"
  30 #include <zlib.h>
  31
  32 /* Maximum compressed block size */
  33 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)
  34
  35 typedef struct BDRVCloopState {
  36     CoMutex lock;
  37     uint32_t block_size;
  38     uint32_t n_blocks;
  39     uint64_t *offsets;
  40     uint32_t sectors_per_block;
  41     uint32_t current_block;
  42     uint8_t *compressed_block;
  43     uint8_t *uncompressed_block;
  44     z_stream zstream;
  45 } BDRVCloopState;
  46
  47 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  48 {
  49     const char *magic_version_2_0 = "#!/bin/sh\n"
  50         "#V2.0 Format\n"
  51         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  52     int length = strlen(magic_version_2_0);
  53     if (length > buf_size) {
  54         length = buf_size;
  55     }
  56     if (!memcmp(magic_version_2_0, buf, length)) {
  57         return 2;
  58     }
  59     return 0;
  60 }
  61
  62 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
  63                       Error **errp)
  64 {
  65     BDRVCloopState *s = bs->opaque;
  66     uint32_t offsets_size, max_compressed_block_size = 1, i;
  67     int ret;
  68
  69     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
  70                                false, errp);
  71     if (!bs->file) {
  72         return -EINVAL;
  73     }
  74
  75     ret = bdrv_set_read_only(bs, true, errp);
  76     if (ret < 0) {
  77         return ret;
  78     }
  79
  80     /* read header */
  81     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
  82     if (ret < 0) {
  83         return ret;
  84     }
  85     s->block_size = be32_to_cpu(s->block_size);
  86     if (s->block_size % 512) {
  87         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  88                    s->block_size);
  89         return -EINVAL;
  90     }
  91     if (s->block_size == 0) {
  92         error_setg(errp, "block_size cannot be zero");
  93         return -EINVAL;
  94     }
  95
  96     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  97      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
  98      * need a buffer this big.
  99      */
 100     if (s->block_size > MAX_BLOCK_SIZE) {
 101         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
 102                    s->block_size,
 103                    MAX_BLOCK_SIZE / (1024 * 1024));
 104         return -EINVAL;
 105     }
 106
 107     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
 108     if (ret < 0) {
 109         return ret;
 110     }
 111     s->n_blocks = be32_to_cpu(s->n_blocks);
 112
 113     /* read offsets */
 114     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 115         /* Prevent integer overflow */
 116         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 117                    s->n_blocks,
 118                    (UINT32_MAX - 1) / sizeof(uint64_t));
 119         return -EINVAL;
 120     }
 121     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 122     if (offsets_size > 512 * 1024 * 1024) {
 123         /* Prevent ridiculous offsets_size which causes memory allocation to
 124          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 125          * offsets[] limit supports 16 TB images at 256 KB block size.
 126          */
 127         error_setg(errp, "image requires too many offsets, "
 128                    "try increasing block size");
 129         return -EINVAL;
 130     }
 131
 132     s->offsets = g_try_malloc(offsets_size);
 133     if (s->offsets == NULL) {
 134         error_setg(errp, "Could not allocate offsets table");
 135         return -ENOMEM;
 136     }
 137
 138     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
 139     if (ret < 0) {
 140         goto fail;
 141     }
 142
 143     for (i = 0; i < s->n_blocks + 1; i++) {
 144         uint64_t size;
 145
 146         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 147         if (i == 0) {
 148             continue;
 149         }
 150
 151         if (s->offsets[i] < s->offsets[i - 1]) {
 152             error_setg(errp, "offsets not monotonically increasing at "
 153                        "index %" PRIu32 ", image file is corrupt", i);
 154             ret = -EINVAL;
 155             goto fail;
 156         }
 157
 158         size = s->offsets[i] - s->offsets[i - 1];
 159
 160         /* Compressed blocks should be smaller than the uncompressed block size
 161          * but maybe compression performed poorly so the compressed block is
 162          * actually bigger.  Clamp down on unrealistic values to prevent
 163          * ridiculous s->compressed_block allocation.
 164          */
 165         if (size > 2 * MAX_BLOCK_SIZE) {
 166             error_setg(errp, "invalid compressed block size at index %" PRIu32
 167                        ", image file is corrupt", i);
 168             ret = -EINVAL;
 169             goto fail;
 170         }
 171
 172         if (size > max_compressed_block_size) {
 173             max_compressed_block_size = size;
 174         }
 175     }
 176
 177     /* initialize zlib engine */
 178     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 179     if (s->compressed_block == NULL) {
 180         error_setg(errp, "Could not allocate compressed_block");
 181         ret = -ENOMEM;
 182         goto fail;
 183     }
 184
 185     s->uncompressed_block = g_try_malloc(s->block_size);
 186     if (s->uncompressed_block == NULL) {
 187         error_setg(errp, "Could not allocate uncompressed_block");
 188         ret = -ENOMEM;
 189         goto fail;
 190     }
 191
 192     if (inflateInit(&s->zstream) != Z_OK) {
 193         ret = -EINVAL;
 194         goto fail;
 195     }
 196     s->current_block = s->n_blocks;
 197
 198     s->sectors_per_block = s->block_size/512;
 199     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 200     qemu_co_mutex_init(&s->lock);
 201     return 0;
 202
 203 fail:
 204     g_free(s->offsets);
 205     g_free(s->compressed_block);
 206     g_free(s->uncompressed_block);
 207     return ret;
 208 }
 209
 210 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 211 {
 212     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 213 }
 214
 215 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 216 {
 217     BDRVCloopState *s = bs->opaque;
 218
 219     if (s->current_block != block_num) {
 220         int ret;
 221         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 222
 223         ret = bdrv_pread(bs->file, s->offsets[block_num],
 224                          s->compressed_block, bytes);
 225         if (ret != bytes) {
 226             return -1;
 227         }
 228
 229         s->zstream.next_in = s->compressed_block;
 230         s->zstream.avail_in = bytes;
 231         s->zstream.next_out = s->uncompressed_block;
 232         s->zstream.avail_out = s->block_size;
 233         ret = inflateReset(&s->zstream);
 234         if (ret != Z_OK) {
 235             return -1;
 236         }
 237         ret = inflate(&s->zstream, Z_FINISH);
 238         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 239             return -1;
 240         }
 241
 242         s->current_block = block_num;
 243     }
 244     return 0;
 245 }
 246
 247 static int coroutine_fn
 248 cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 249                 QEMUIOVector *qiov, int flags)
 250 {
 251     BDRVCloopState *s = bs->opaque;
 252     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 253     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 254     int ret, i;
 255
 256     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 257     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 258
 259     qemu_co_mutex_lock(&s->lock);
 260
 261     for (i = 0; i < nb_sectors; i++) {
 262         void *data;
 263         uint32_t sector_offset_in_block =
 264             ((sector_num + i) % s->sectors_per_block),
 265             block_num = (sector_num + i) / s->sectors_per_block;
 266         if (cloop_read_block(bs, block_num) != 0) {
 267             ret = -EIO;
 268             goto fail;
 269         }
 270
 271         data = s->uncompressed_block + sector_offset_in_block * 512;
 272         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 273     }
 274
 275     ret = 0;
 276 fail:
 277     qemu_co_mutex_unlock(&s->lock);
 278
 279     return ret;
 280 }
 281
 282 static void cloop_close(BlockDriverState *bs)
 283 {
 284     BDRVCloopState *s = bs->opaque;
 285     g_free(s->offsets);
 286     g_free(s->compressed_block);
 287     g_free(s->uncompressed_block);
 288     inflateEnd(&s->zstream);
 289 }
 290
 291 static BlockDriver bdrv_cloop = {
 292     .format_name    = "cloop",
 293     .instance_size  = sizeof(BDRVCloopState),
 294     .bdrv_probe     = cloop_probe,
 295     .bdrv_open      = cloop_open,
 296     .bdrv_child_perm     = bdrv_format_default_perms,
 297     .bdrv_refresh_limits = cloop_refresh_limits,
 298     .bdrv_co_preadv = cloop_co_preadv,
 299     .bdrv_close     = cloop_close,
 300 };
 301
 302 static void bdrv_cloop_init(void)
 303 {
 304     bdrv_register(&bdrv_cloop);
 305 }
 306
 307 block_init(bdrv_cloop_init);