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