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->read_only = 1;
  70     bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
  71
  72     /* read header */
  73     ret = bdrv_pread(bs->file->bs, 128, &s->block_size, 4);
  74     if (ret < 0) {
  75         return ret;
  76     }
  77     s->block_size = be32_to_cpu(s->block_size);
  78     if (s->block_size % 512) {
  79         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  80                    s->block_size);
  81         return -EINVAL;
  82     }
  83     if (s->block_size == 0) {
  84         error_setg(errp, "block_size cannot be zero");
  85         return -EINVAL;
  86     }
  87
  88     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  89      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
  90      * need a buffer this big.
  91      */
  92     if (s->block_size > MAX_BLOCK_SIZE) {
  93         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
  94                    s->block_size,
  95                    MAX_BLOCK_SIZE / (1024 * 1024));
  96         return -EINVAL;
  97     }
  98
  99     ret = bdrv_pread(bs->file->bs, 128 + 4, &s->n_blocks, 4);
 100     if (ret < 0) {
 101         return ret;
 102     }
 103     s->n_blocks = be32_to_cpu(s->n_blocks);
 104
 105     /* read offsets */
 106     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 107         /* Prevent integer overflow */
 108         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 109                    s->n_blocks,
 110                    (UINT32_MAX - 1) / sizeof(uint64_t));
 111         return -EINVAL;
 112     }
 113     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 114     if (offsets_size > 512 * 1024 * 1024) {
 115         /* Prevent ridiculous offsets_size which causes memory allocation to
 116          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 117          * offsets[] limit supports 16 TB images at 256 KB block size.
 118          */
 119         error_setg(errp, "image requires too many offsets, "
 120                    "try increasing block size");
 121         return -EINVAL;
 122     }
 123
 124     s->offsets = g_try_malloc(offsets_size);
 125     if (s->offsets == NULL) {
 126         error_setg(errp, "Could not allocate offsets table");
 127         return -ENOMEM;
 128     }
 129
 130     ret = bdrv_pread(bs->file->bs, 128 + 4 + 4, s->offsets, offsets_size);
 131     if (ret < 0) {
 132         goto fail;
 133     }
 134
 135     for (i = 0; i < s->n_blocks + 1; i++) {
 136         uint64_t size;
 137
 138         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 139         if (i == 0) {
 140             continue;
 141         }
 142
 143         if (s->offsets[i] < s->offsets[i - 1]) {
 144             error_setg(errp, "offsets not monotonically increasing at "
 145                        "index %" PRIu32 ", image file is corrupt", i);
 146             ret = -EINVAL;
 147             goto fail;
 148         }
 149
 150         size = s->offsets[i] - s->offsets[i - 1];
 151
 152         /* Compressed blocks should be smaller than the uncompressed block size
 153          * but maybe compression performed poorly so the compressed block is
 154          * actually bigger.  Clamp down on unrealistic values to prevent
 155          * ridiculous s->compressed_block allocation.
 156          */
 157         if (size > 2 * MAX_BLOCK_SIZE) {
 158             error_setg(errp, "invalid compressed block size at index %" PRIu32
 159                        ", image file is corrupt", i);
 160             ret = -EINVAL;
 161             goto fail;
 162         }
 163
 164         if (size > max_compressed_block_size) {
 165             max_compressed_block_size = size;
 166         }
 167     }
 168
 169     /* initialize zlib engine */
 170     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 171     if (s->compressed_block == NULL) {
 172         error_setg(errp, "Could not allocate compressed_block");
 173         ret = -ENOMEM;
 174         goto fail;
 175     }
 176
 177     s->uncompressed_block = g_try_malloc(s->block_size);
 178     if (s->uncompressed_block == NULL) {
 179         error_setg(errp, "Could not allocate uncompressed_block");
 180         ret = -ENOMEM;
 181         goto fail;
 182     }
 183
 184     if (inflateInit(&s->zstream) != Z_OK) {
 185         ret = -EINVAL;
 186         goto fail;
 187     }
 188     s->current_block = s->n_blocks;
 189
 190     s->sectors_per_block = s->block_size/512;
 191     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 192     qemu_co_mutex_init(&s->lock);
 193     return 0;
 194
 195 fail:
 196     g_free(s->offsets);
 197     g_free(s->compressed_block);
 198     g_free(s->uncompressed_block);
 199     return ret;
 200 }
 201
 202 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 203 {
 204     BDRVCloopState *s = bs->opaque;
 205
 206     if (s->current_block != block_num) {
 207         int ret;
 208         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 209
 210         ret = bdrv_pread(bs->file->bs, s->offsets[block_num],
 211                          s->compressed_block, bytes);
 212         if (ret != bytes) {
 213             return -1;
 214         }
 215
 216         s->zstream.next_in = s->compressed_block;
 217         s->zstream.avail_in = bytes;
 218         s->zstream.next_out = s->uncompressed_block;
 219         s->zstream.avail_out = s->block_size;
 220         ret = inflateReset(&s->zstream);
 221         if (ret != Z_OK) {
 222             return -1;
 223         }
 224         ret = inflate(&s->zstream, Z_FINISH);
 225         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 226             return -1;
 227         }
 228
 229         s->current_block = block_num;
 230     }
 231     return 0;
 232 }
 233
 234 static int coroutine_fn
 235 cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 236                 QEMUIOVector *qiov, int flags)
 237 {
 238     BDRVCloopState *s = bs->opaque;
 239     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 240     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 241     int ret, i;
 242
 243     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 244     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 245
 246     qemu_co_mutex_lock(&s->lock);
 247
 248     for (i = 0; i < nb_sectors; i++) {
 249         void *data;
 250         uint32_t sector_offset_in_block =
 251             ((sector_num + i) % s->sectors_per_block),
 252             block_num = (sector_num + i) / s->sectors_per_block;
 253         if (cloop_read_block(bs, block_num) != 0) {
 254             ret = -EIO;
 255             goto fail;
 256         }
 257
 258         data = s->uncompressed_block + sector_offset_in_block * 512;
 259         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 260     }
 261
 262     ret = 0;
 263 fail:
 264     qemu_co_mutex_unlock(&s->lock);
 265
 266     return ret;
 267 }
 268
 269 static void cloop_close(BlockDriverState *bs)
 270 {
 271     BDRVCloopState *s = bs->opaque;
 272     g_free(s->offsets);
 273     g_free(s->compressed_block);
 274     g_free(s->uncompressed_block);
 275     inflateEnd(&s->zstream);
 276 }
 277
 278 static BlockDriver bdrv_cloop = {
 279     .format_name    = "cloop",
 280     .instance_size  = sizeof(BDRVCloopState),
 281     .bdrv_probe     = cloop_probe,
 282     .bdrv_open      = cloop_open,
 283     .bdrv_co_preadv = cloop_co_preadv,
 284     .bdrv_close     = cloop_close,
 285 };
 286
 287 static void bdrv_cloop_init(void)
 288 {
 289     bdrv_register(&bdrv_cloop);
 290 }
 291
 292 block_init(bdrv_cloop_init);