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-io.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     GLOBAL_STATE_CODE();
  71
  72     bdrv_graph_rdlock_main_loop();
  73     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
  74     bdrv_graph_rdunlock_main_loop();
  75     if (ret < 0) {
  76         return ret;
  77     }
  78
  79     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  80     if (ret < 0) {
  81         return ret;
  82     }
  83
  84     GRAPH_RDLOCK_GUARD_MAINLOOP();
  85
  86     /* read header */
  87     ret = bdrv_pread(bs->file, 128, 4, &s->block_size, 0);
  88     if (ret < 0) {
  89         return ret;
  90     }
  91     s->block_size = be32_to_cpu(s->block_size);
  92     if (s->block_size % 512) {
  93         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  94                    s->block_size);
  95         return -EINVAL;
  96     }
  97     if (s->block_size == 0) {
  98         error_setg(errp, "block_size cannot be zero");
  99         return -EINVAL;
 100     }
 101
 102     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
 103      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
 104      * need a buffer this big.
 105      */
 106     if (s->block_size > MAX_BLOCK_SIZE) {
 107         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
 108                    s->block_size,
 109                    MAX_BLOCK_SIZE / (1024 * 1024));
 110         return -EINVAL;
 111     }
 112
 113     ret = bdrv_pread(bs->file, 128 + 4, 4, &s->n_blocks, 0);
 114     if (ret < 0) {
 115         return ret;
 116     }
 117     s->n_blocks = be32_to_cpu(s->n_blocks);
 118
 119     /* read offsets */
 120     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 121         /* Prevent integer overflow */
 122         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 123                    s->n_blocks,
 124                    (UINT32_MAX - 1) / sizeof(uint64_t));
 125         return -EINVAL;
 126     }
 127     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 128     if (offsets_size > 512 * 1024 * 1024) {
 129         /* Prevent ridiculous offsets_size which causes memory allocation to
 130          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 131          * offsets[] limit supports 16 TB images at 256 KB block size.
 132          */
 133         error_setg(errp, "image requires too many offsets, "
 134                    "try increasing block size");
 135         return -EINVAL;
 136     }
 137
 138     s->offsets = g_try_malloc(offsets_size);
 139     if (s->offsets == NULL) {
 140         error_setg(errp, "Could not allocate offsets table");
 141         return -ENOMEM;
 142     }
 143
 144     ret = bdrv_pread(bs->file, 128 + 4 + 4, offsets_size, s->offsets, 0);
 145     if (ret < 0) {
 146         goto fail;
 147     }
 148
 149     for (i = 0; i < s->n_blocks + 1; i++) {
 150         uint64_t size;
 151
 152         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 153         if (i == 0) {
 154             continue;
 155         }
 156
 157         if (s->offsets[i] < s->offsets[i - 1]) {
 158             error_setg(errp, "offsets not monotonically increasing at "
 159                        "index %" PRIu32 ", image file is corrupt", i);
 160             ret = -EINVAL;
 161             goto fail;
 162         }
 163
 164         size = s->offsets[i] - s->offsets[i - 1];
 165
 166         /* Compressed blocks should be smaller than the uncompressed block size
 167          * but maybe compression performed poorly so the compressed block is
 168          * actually bigger.  Clamp down on unrealistic values to prevent
 169          * ridiculous s->compressed_block allocation.
 170          */
 171         if (size > 2 * MAX_BLOCK_SIZE) {
 172             error_setg(errp, "invalid compressed block size at index %" PRIu32
 173                        ", image file is corrupt", i);
 174             ret = -EINVAL;
 175             goto fail;
 176         }
 177
 178         if (size > max_compressed_block_size) {
 179             max_compressed_block_size = size;
 180         }
 181     }
 182
 183     /* initialize zlib engine */
 184     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 185     if (s->compressed_block == NULL) {
 186         error_setg(errp, "Could not allocate compressed_block");
 187         ret = -ENOMEM;
 188         goto fail;
 189     }
 190
 191     s->uncompressed_block = g_try_malloc(s->block_size);
 192     if (s->uncompressed_block == NULL) {
 193         error_setg(errp, "Could not allocate uncompressed_block");
 194         ret = -ENOMEM;
 195         goto fail;
 196     }
 197
 198     if (inflateInit(&s->zstream) != Z_OK) {
 199         ret = -EINVAL;
 200         goto fail;
 201     }
 202     s->current_block = s->n_blocks;
 203
 204     s->sectors_per_block = s->block_size/512;
 205     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 206     qemu_co_mutex_init(&s->lock);
 207     return 0;
 208
 209 fail:
 210     g_free(s->offsets);
 211     g_free(s->compressed_block);
 212     g_free(s->uncompressed_block);
 213     return ret;
 214 }
 215
 216 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 217 {
 218     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 219 }
 220
 221 static int coroutine_fn GRAPH_RDLOCK
 222 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_co_pread(bs->file, s->offsets[block_num], bytes,
 231                             s->compressed_block, 0);
 232         if (ret < 0) {
 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 GRAPH_RDLOCK
 255 cloop_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 256                 QEMUIOVector *qiov, BdrvRequestFlags 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(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 264     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 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_default_perms,
 304     .bdrv_refresh_limits = cloop_refresh_limits,
 305     .bdrv_co_preadv = cloop_co_preadv,
 306     .bdrv_close     = cloop_close,
 307     .is_format      = true,
 308 };
 309
 310 static void bdrv_cloop_init(void)
 311 {
 312     bdrv_register(&bdrv_cloop);
 313 }
 314
 315 block_init(bdrv_cloop_init);