qemu/block/cloop.c
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   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 "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
  35typedef 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
  47static 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
  62static 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    ret = bdrv_apply_auto_read_only(bs, NULL, errp);
  70    if (ret < 0) {
  71        return ret;
  72    }
  73
  74    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
  75                               BDRV_CHILD_IMAGE, false, errp);
  76    if (!bs->file) {
  77        return -EINVAL;
  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
 203fail:
 204    g_free(s->offsets);
 205    g_free(s->compressed_block);
 206    g_free(s->uncompressed_block);
 207    return ret;
 208}
 209
 210static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 211{
 212    bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 213}
 214
 215static 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
 247static int coroutine_fn
 248cloop_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(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 257    assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 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;
 276fail:
 277    qemu_co_mutex_unlock(&s->lock);
 278
 279    return ret;
 280}
 281
 282static 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
 291static 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_default_perms,
 297    .bdrv_refresh_limits = cloop_refresh_limits,
 298    .bdrv_co_preadv = cloop_co_preadv,
 299    .bdrv_close     = cloop_close,
 300    .is_format      = true,
 301};
 302
 303static void bdrv_cloop_init(void)
 304{
 305    bdrv_register(&bdrv_cloop);
 306}
 307
 308block_init(bdrv_cloop_init);
 309