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 "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     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
  70     if (ret < 0) {
  71         return ret;
  72     }
  73
  74     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  75     if (ret < 0) {
  76         return ret;
  77     }
  78
  79     /* read header */
  80     ret = bdrv_pread(bs->file, 128, 4, &s->block_size, 0);
  81     if (ret < 0) {
  82         return ret;
  83     }
  84     s->block_size = be32_to_cpu(s->block_size);
  85     if (s->block_size % 512) {
  86         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  87                    s->block_size);
  88         return -EINVAL;
  89     }
  90     if (s->block_size == 0) {
  91         error_setg(errp, "block_size cannot be zero");
  92         return -EINVAL;
  93     }
  94
  95     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  96      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
  97      * need a buffer this big.
  98      */
  99     if (s->block_size > MAX_BLOCK_SIZE) {
 100         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
 101                    s->block_size,
 102                    MAX_BLOCK_SIZE / (1024 * 1024));
 103         return -EINVAL;
 104     }
 105
 106     ret = bdrv_pread(bs->file, 128 + 4, 4, &s->n_blocks, 0);
 107     if (ret < 0) {
 108         return ret;
 109     }
 110     s->n_blocks = be32_to_cpu(s->n_blocks);
 111
 112     /* read offsets */
 113     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 114         /* Prevent integer overflow */
 115         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 116                    s->n_blocks,
 117                    (UINT32_MAX - 1) / sizeof(uint64_t));
 118         return -EINVAL;
 119     }
 120     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 121     if (offsets_size > 512 * 1024 * 1024) {
 122         /* Prevent ridiculous offsets_size which causes memory allocation to
 123          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 124          * offsets[] limit supports 16 TB images at 256 KB block size.
 125          */
 126         error_setg(errp, "image requires too many offsets, "
 127                    "try increasing block size");
 128         return -EINVAL;
 129     }
 130
 131     s->offsets = g_try_malloc(offsets_size);
 132     if (s->offsets == NULL) {
 133         error_setg(errp, "Could not allocate offsets table");
 134         return -ENOMEM;
 135     }
 136
 137     ret = bdrv_pread(bs->file, 128 + 4 + 4, offsets_size, s->offsets, 0);
 138     if (ret < 0) {
 139         goto fail;
 140     }
 141
 142     for (i = 0; i < s->n_blocks + 1; i++) {
 143         uint64_t size;
 144
 145         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 146         if (i == 0) {
 147             continue;
 148         }
 149
 150         if (s->offsets[i] < s->offsets[i - 1]) {
 151             error_setg(errp, "offsets not monotonically increasing at "
 152                        "index %" PRIu32 ", image file is corrupt", i);
 153             ret = -EINVAL;
 154             goto fail;
 155         }
 156
 157         size = s->offsets[i] - s->offsets[i - 1];
 158
 159         /* Compressed blocks should be smaller than the uncompressed block size
 160          * but maybe compression performed poorly so the compressed block is
 161          * actually bigger.  Clamp down on unrealistic values to prevent
 162          * ridiculous s->compressed_block allocation.
 163          */
 164         if (size > 2 * MAX_BLOCK_SIZE) {
 165             error_setg(errp, "invalid compressed block size at index %" PRIu32
 166                        ", image file is corrupt", i);
 167             ret = -EINVAL;
 168             goto fail;
 169         }
 170
 171         if (size > max_compressed_block_size) {
 172             max_compressed_block_size = size;
 173         }
 174     }
 175
 176     /* initialize zlib engine */
 177     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 178     if (s->compressed_block == NULL) {
 179         error_setg(errp, "Could not allocate compressed_block");
 180         ret = -ENOMEM;
 181         goto fail;
 182     }
 183
 184     s->uncompressed_block = g_try_malloc(s->block_size);
 185     if (s->uncompressed_block == NULL) {
 186         error_setg(errp, "Could not allocate uncompressed_block");
 187         ret = -ENOMEM;
 188         goto fail;
 189     }
 190
 191     if (inflateInit(&s->zstream) != Z_OK) {
 192         ret = -EINVAL;
 193         goto fail;
 194     }
 195     s->current_block = s->n_blocks;
 196
 197     s->sectors_per_block = s->block_size/512;
 198     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 199     qemu_co_mutex_init(&s->lock);
 200     return 0;
 201
 202 fail:
 203     g_free(s->offsets);
 204     g_free(s->compressed_block);
 205     g_free(s->uncompressed_block);
 206     return ret;
 207 }
 208
 209 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 210 {
 211     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 212 }
 213
 214 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 215 {
 216     BDRVCloopState *s = bs->opaque;
 217
 218     if (s->current_block != block_num) {
 219         int ret;
 220         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 221
 222         ret = bdrv_pread(bs->file, s->offsets[block_num], bytes,
 223                          s->compressed_block, 0);
 224         if (ret < 0) {
 225             return -1;
 226         }
 227
 228         s->zstream.next_in = s->compressed_block;
 229         s->zstream.avail_in = bytes;
 230         s->zstream.next_out = s->uncompressed_block;
 231         s->zstream.avail_out = s->block_size;
 232         ret = inflateReset(&s->zstream);
 233         if (ret != Z_OK) {
 234             return -1;
 235         }
 236         ret = inflate(&s->zstream, Z_FINISH);
 237         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 238             return -1;
 239         }
 240
 241         s->current_block = block_num;
 242     }
 243     return 0;
 244 }
 245
 246 static int coroutine_fn
 247 cloop_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 248                 QEMUIOVector *qiov, BdrvRequestFlags flags)
 249 {
 250     BDRVCloopState *s = bs->opaque;
 251     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 252     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 253     int ret, i;
 254
 255     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 256     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 257
 258     qemu_co_mutex_lock(&s->lock);
 259
 260     for (i = 0; i < nb_sectors; i++) {
 261         void *data;
 262         uint32_t sector_offset_in_block =
 263             ((sector_num + i) % s->sectors_per_block),
 264             block_num = (sector_num + i) / s->sectors_per_block;
 265         if (cloop_read_block(bs, block_num) != 0) {
 266             ret = -EIO;
 267             goto fail;
 268         }
 269
 270         data = s->uncompressed_block + sector_offset_in_block * 512;
 271         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 272     }
 273
 274     ret = 0;
 275 fail:
 276     qemu_co_mutex_unlock(&s->lock);
 277
 278     return ret;
 279 }
 280
 281 static void cloop_close(BlockDriverState *bs)
 282 {
 283     BDRVCloopState *s = bs->opaque;
 284     g_free(s->offsets);
 285     g_free(s->compressed_block);
 286     g_free(s->uncompressed_block);
 287     inflateEnd(&s->zstream);
 288 }
 289
 290 static BlockDriver bdrv_cloop = {
 291     .format_name    = "cloop",
 292     .instance_size  = sizeof(BDRVCloopState),
 293     .bdrv_probe     = cloop_probe,
 294     .bdrv_open      = cloop_open,
 295     .bdrv_child_perm     = bdrv_default_perms,
 296     .bdrv_refresh_limits = cloop_refresh_limits,
 297     .bdrv_co_preadv = cloop_co_preadv,
 298     .bdrv_close     = cloop_close,
 299     .is_format      = true,
 300 };
 301
 302 static void bdrv_cloop_init(void)
 303 {
 304     bdrv_register(&bdrv_cloop);
 305 }
 306
 307 block_init(bdrv_cloop_init);