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 "qemu-common.h"
  28 #include "block/block_int.h"
  29 #include "qemu/module.h"
  30 #include "qemu/bswap.h"
  31 #include <zlib.h>
  32
  33 /* Maximum compressed block size */
  34 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)
  35
  36 typedef struct BDRVCloopState {
  37     CoMutex lock;
  38     uint32_t block_size;
  39     uint32_t n_blocks;
  40     uint64_t *offsets;
  41     uint32_t sectors_per_block;
  42     uint32_t current_block;
  43     uint8_t *compressed_block;
  44     uint8_t *uncompressed_block;
  45     z_stream zstream;
  46 } BDRVCloopState;
  47
  48 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  49 {
  50     const char *magic_version_2_0 = "#!/bin/sh\n"
  51         "#V2.0 Format\n"
  52         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  53     int length = strlen(magic_version_2_0);
  54     if (length > buf_size) {
  55         length = buf_size;
  56     }
  57     if (!memcmp(magic_version_2_0, buf, length)) {
  58         return 2;
  59     }
  60     return 0;
  61 }
  62
  63 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
  64                       Error **errp)
  65 {
  66     BDRVCloopState *s = bs->opaque;
  67     uint32_t offsets_size, max_compressed_block_size = 1, i;
  68     int ret;
  69
  70     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
  71                                false, errp);
  72     if (!bs->file) {
  73         return -EINVAL;
  74     }
  75
  76     if (!bdrv_is_read_only(bs)) {
  77         error_report("Opening cloop images without an explicit read-only=on "
  78                      "option is deprecated. Future versions will refuse to "
  79                      "open the image instead of automatically marking the "
  80                      "image read-only.");
  81         ret = bdrv_set_read_only(bs, true, errp);
  82         if (ret < 0) {
  83             return ret;
  84         }
  85     }
  86
  87     /* read header */
  88     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
  89     if (ret < 0) {
  90         return ret;
  91     }
  92     s->block_size = be32_to_cpu(s->block_size);
  93     if (s->block_size % 512) {
  94         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  95                    s->block_size);
  96         return -EINVAL;
  97     }
  98     if (s->block_size == 0) {
  99         error_setg(errp, "block_size cannot be zero");
 100         return -EINVAL;
 101     }
 102
 103     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
 104      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
 105      * need a buffer this big.
 106      */
 107     if (s->block_size > MAX_BLOCK_SIZE) {
 108         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
 109                    s->block_size,
 110                    MAX_BLOCK_SIZE / (1024 * 1024));
 111         return -EINVAL;
 112     }
 113
 114     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
 115     if (ret < 0) {
 116         return ret;
 117     }
 118     s->n_blocks = be32_to_cpu(s->n_blocks);
 119
 120     /* read offsets */
 121     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 122         /* Prevent integer overflow */
 123         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 124                    s->n_blocks,
 125                    (UINT32_MAX - 1) / sizeof(uint64_t));
 126         return -EINVAL;
 127     }
 128     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 129     if (offsets_size > 512 * 1024 * 1024) {
 130         /* Prevent ridiculous offsets_size which causes memory allocation to
 131          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 132          * offsets[] limit supports 16 TB images at 256 KB block size.
 133          */
 134         error_setg(errp, "image requires too many offsets, "
 135                    "try increasing block size");
 136         return -EINVAL;
 137     }
 138
 139     s->offsets = g_try_malloc(offsets_size);
 140     if (s->offsets == NULL) {
 141         error_setg(errp, "Could not allocate offsets table");
 142         return -ENOMEM;
 143     }
 144
 145     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
 146     if (ret < 0) {
 147         goto fail;
 148     }
 149
 150     for (i = 0; i < s->n_blocks + 1; i++) {
 151         uint64_t size;
 152
 153         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 154         if (i == 0) {
 155             continue;
 156         }
 157
 158         if (s->offsets[i] < s->offsets[i - 1]) {
 159             error_setg(errp, "offsets not monotonically increasing at "
 160                        "index %" PRIu32 ", image file is corrupt", i);
 161             ret = -EINVAL;
 162             goto fail;
 163         }
 164
 165         size = s->offsets[i] - s->offsets[i - 1];
 166
 167         /* Compressed blocks should be smaller than the uncompressed block size
 168          * but maybe compression performed poorly so the compressed block is
 169          * actually bigger.  Clamp down on unrealistic values to prevent
 170          * ridiculous s->compressed_block allocation.
 171          */
 172         if (size > 2 * MAX_BLOCK_SIZE) {
 173             error_setg(errp, "invalid compressed block size at index %" PRIu32
 174                        ", image file is corrupt", i);
 175             ret = -EINVAL;
 176             goto fail;
 177         }
 178
 179         if (size > max_compressed_block_size) {
 180             max_compressed_block_size = size;
 181         }
 182     }
 183
 184     /* initialize zlib engine */
 185     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 186     if (s->compressed_block == NULL) {
 187         error_setg(errp, "Could not allocate compressed_block");
 188         ret = -ENOMEM;
 189         goto fail;
 190     }
 191
 192     s->uncompressed_block = g_try_malloc(s->block_size);
 193     if (s->uncompressed_block == NULL) {
 194         error_setg(errp, "Could not allocate uncompressed_block");
 195         ret = -ENOMEM;
 196         goto fail;
 197     }
 198
 199     if (inflateInit(&s->zstream) != Z_OK) {
 200         ret = -EINVAL;
 201         goto fail;
 202     }
 203     s->current_block = s->n_blocks;
 204
 205     s->sectors_per_block = s->block_size/512;
 206     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 207     qemu_co_mutex_init(&s->lock);
 208     return 0;
 209
 210 fail:
 211     g_free(s->offsets);
 212     g_free(s->compressed_block);
 213     g_free(s->uncompressed_block);
 214     return ret;
 215 }
 216
 217 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 218 {
 219     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 220 }
 221
 222 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 223 {
 224     BDRVCloopState *s = bs->opaque;
 225
 226     if (s->current_block != block_num) {
 227         int ret;
 228         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 229
 230         ret = bdrv_pread(bs->file, s->offsets[block_num],
 231                          s->compressed_block, bytes);
 232         if (ret != bytes) {
 233             return -1;
 234         }
 235
 236         s->zstream.next_in = s->compressed_block;
 237         s->zstream.avail_in = bytes;
 238         s->zstream.next_out = s->uncompressed_block;
 239         s->zstream.avail_out = s->block_size;
 240         ret = inflateReset(&s->zstream);
 241         if (ret != Z_OK) {
 242             return -1;
 243         }
 244         ret = inflate(&s->zstream, Z_FINISH);
 245         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 246             return -1;
 247         }
 248
 249         s->current_block = block_num;
 250     }
 251     return 0;
 252 }
 253
 254 static int coroutine_fn
 255 cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 256                 QEMUIOVector *qiov, int flags)
 257 {
 258     BDRVCloopState *s = bs->opaque;
 259     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 260     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 261     int ret, i;
 262
 263     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 264     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 265
 266     qemu_co_mutex_lock(&s->lock);
 267
 268     for (i = 0; i < nb_sectors; i++) {
 269         void *data;
 270         uint32_t sector_offset_in_block =
 271             ((sector_num + i) % s->sectors_per_block),
 272             block_num = (sector_num + i) / s->sectors_per_block;
 273         if (cloop_read_block(bs, block_num) != 0) {
 274             ret = -EIO;
 275             goto fail;
 276         }
 277
 278         data = s->uncompressed_block + sector_offset_in_block * 512;
 279         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 280     }
 281
 282     ret = 0;
 283 fail:
 284     qemu_co_mutex_unlock(&s->lock);
 285
 286     return ret;
 287 }
 288
 289 static void cloop_close(BlockDriverState *bs)
 290 {
 291     BDRVCloopState *s = bs->opaque;
 292     g_free(s->offsets);
 293     g_free(s->compressed_block);
 294     g_free(s->uncompressed_block);
 295     inflateEnd(&s->zstream);
 296 }
 297
 298 static BlockDriver bdrv_cloop = {
 299     .format_name    = "cloop",
 300     .instance_size  = sizeof(BDRVCloopState),
 301     .bdrv_probe     = cloop_probe,
 302     .bdrv_open      = cloop_open,
 303     .bdrv_child_perm     = bdrv_format_default_perms,
 304     .bdrv_refresh_limits = cloop_refresh_limits,
 305     .bdrv_co_preadv = cloop_co_preadv,
 306     .bdrv_close     = cloop_close,
 307 };
 308
 309 static void bdrv_cloop_init(void)
 310 {
 311     bdrv_register(&bdrv_cloop);
 312 }
 313
 314 block_init(bdrv_cloop_init);