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