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     bdrv_graph_rdlock_main_loop();
  71     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
  72     bdrv_graph_rdunlock_main_loop();
  73     if (ret < 0) {
  74         return ret;
  75     }
  76
  77     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  78     if (ret < 0) {
  79         return ret;
  80     }
  81
  82     /* read header */
  83     ret = bdrv_pread(bs->file, 128, 4, &s->block_size, 0);
  84     if (ret < 0) {
  85         return ret;
  86     }
  87     s->block_size = be32_to_cpu(s->block_size);
  88     if (s->block_size % 512) {
  89         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  90                    s->block_size);
  91         return -EINVAL;
  92     }
  93     if (s->block_size == 0) {
  94         error_setg(errp, "block_size cannot be zero");
  95         return -EINVAL;
  96     }
  97
  98     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  99      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
 100      * need a buffer this big.
 101      */
 102     if (s->block_size > MAX_BLOCK_SIZE) {
 103         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
 104                    s->block_size,
 105                    MAX_BLOCK_SIZE / (1024 * 1024));
 106         return -EINVAL;
 107     }
 108
 109     ret = bdrv_pread(bs->file, 128 + 4, 4, &s->n_blocks, 0);
 110     if (ret < 0) {
 111         return ret;
 112     }
 113     s->n_blocks = be32_to_cpu(s->n_blocks);
 114
 115     /* read offsets */
 116     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 117         /* Prevent integer overflow */
 118         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 119                    s->n_blocks,
 120                    (UINT32_MAX - 1) / sizeof(uint64_t));
 121         return -EINVAL;
 122     }
 123     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 124     if (offsets_size > 512 * 1024 * 1024) {
 125         /* Prevent ridiculous offsets_size which causes memory allocation to
 126          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 127          * offsets[] limit supports 16 TB images at 256 KB block size.
 128          */
 129         error_setg(errp, "image requires too many offsets, "
 130                    "try increasing block size");
 131         return -EINVAL;
 132     }
 133
 134     s->offsets = g_try_malloc(offsets_size);
 135     if (s->offsets == NULL) {
 136         error_setg(errp, "Could not allocate offsets table");
 137         return -ENOMEM;
 138     }
 139
 140     ret = bdrv_pread(bs->file, 128 + 4 + 4, offsets_size, s->offsets, 0);
 141     if (ret < 0) {
 142         goto fail;
 143     }
 144
 145     for (i = 0; i < s->n_blocks + 1; i++) {
 146         uint64_t size;
 147
 148         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 149         if (i == 0) {
 150             continue;
 151         }
 152
 153         if (s->offsets[i] < s->offsets[i - 1]) {
 154             error_setg(errp, "offsets not monotonically increasing at "
 155                        "index %" PRIu32 ", image file is corrupt", i);
 156             ret = -EINVAL;
 157             goto fail;
 158         }
 159
 160         size = s->offsets[i] - s->offsets[i - 1];
 161
 162         /* Compressed blocks should be smaller than the uncompressed block size
 163          * but maybe compression performed poorly so the compressed block is
 164          * actually bigger.  Clamp down on unrealistic values to prevent
 165          * ridiculous s->compressed_block allocation.
 166          */
 167         if (size > 2 * MAX_BLOCK_SIZE) {
 168             error_setg(errp, "invalid compressed block size at index %" PRIu32
 169                        ", image file is corrupt", i);
 170             ret = -EINVAL;
 171             goto fail;
 172         }
 173
 174         if (size > max_compressed_block_size) {
 175             max_compressed_block_size = size;
 176         }
 177     }
 178
 179     /* initialize zlib engine */
 180     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
 181     if (s->compressed_block == NULL) {
 182         error_setg(errp, "Could not allocate compressed_block");
 183         ret = -ENOMEM;
 184         goto fail;
 185     }
 186
 187     s->uncompressed_block = g_try_malloc(s->block_size);
 188     if (s->uncompressed_block == NULL) {
 189         error_setg(errp, "Could not allocate uncompressed_block");
 190         ret = -ENOMEM;
 191         goto fail;
 192     }
 193
 194     if (inflateInit(&s->zstream) != Z_OK) {
 195         ret = -EINVAL;
 196         goto fail;
 197     }
 198     s->current_block = s->n_blocks;
 199
 200     s->sectors_per_block = s->block_size/512;
 201     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 202     qemu_co_mutex_init(&s->lock);
 203     return 0;
 204
 205 fail:
 206     g_free(s->offsets);
 207     g_free(s->compressed_block);
 208     g_free(s->uncompressed_block);
 209     return ret;
 210 }
 211
 212 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 213 {
 214     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 215 }
 216
 217 static int coroutine_fn GRAPH_RDLOCK
 218 cloop_read_block(BlockDriverState *bs, int block_num)
 219 {
 220     BDRVCloopState *s = bs->opaque;
 221
 222     if (s->current_block != block_num) {
 223         int ret;
 224         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 225
 226         ret = bdrv_co_pread(bs->file, s->offsets[block_num], bytes,
 227                             s->compressed_block, 0);
 228         if (ret < 0) {
 229             return -1;
 230         }
 231
 232         s->zstream.next_in = s->compressed_block;
 233         s->zstream.avail_in = bytes;
 234         s->zstream.next_out = s->uncompressed_block;
 235         s->zstream.avail_out = s->block_size;
 236         ret = inflateReset(&s->zstream);
 237         if (ret != Z_OK) {
 238             return -1;
 239         }
 240         ret = inflate(&s->zstream, Z_FINISH);
 241         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 242             return -1;
 243         }
 244
 245         s->current_block = block_num;
 246     }
 247     return 0;
 248 }
 249
 250 static int coroutine_fn GRAPH_RDLOCK
 251 cloop_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 252                 QEMUIOVector *qiov, BdrvRequestFlags flags)
 253 {
 254     BDRVCloopState *s = bs->opaque;
 255     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 256     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 257     int ret, i;
 258
 259     assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
 260     assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
 261
 262     qemu_co_mutex_lock(&s->lock);
 263
 264     for (i = 0; i < nb_sectors; i++) {
 265         void *data;
 266         uint32_t sector_offset_in_block =
 267             ((sector_num + i) % s->sectors_per_block),
 268             block_num = (sector_num + i) / s->sectors_per_block;
 269         if (cloop_read_block(bs, block_num) != 0) {
 270             ret = -EIO;
 271             goto fail;
 272         }
 273
 274         data = s->uncompressed_block + sector_offset_in_block * 512;
 275         qemu_iovec_from_buf(qiov, i * 512, data, 512);
 276     }
 277
 278     ret = 0;
 279 fail:
 280     qemu_co_mutex_unlock(&s->lock);
 281
 282     return ret;
 283 }
 284
 285 static void cloop_close(BlockDriverState *bs)
 286 {
 287     BDRVCloopState *s = bs->opaque;
 288     g_free(s->offsets);
 289     g_free(s->compressed_block);
 290     g_free(s->uncompressed_block);
 291     inflateEnd(&s->zstream);
 292 }
 293
 294 static BlockDriver bdrv_cloop = {
 295     .format_name    = "cloop",
 296     .instance_size  = sizeof(BDRVCloopState),
 297     .bdrv_probe     = cloop_probe,
 298     .bdrv_open      = cloop_open,
 299     .bdrv_child_perm     = bdrv_default_perms,
 300     .bdrv_refresh_limits = cloop_refresh_limits,
 301     .bdrv_co_preadv = cloop_co_preadv,
 302     .bdrv_close     = cloop_close,
 303     .is_format      = true,
 304 };
 305
 306 static void bdrv_cloop_init(void)
 307 {
 308     bdrv_register(&bdrv_cloop);
 309 }
 310
 311 block_init(bdrv_cloop_init);