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