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-common.h"
  25 #include "block/block_int.h"
  26 #include "qemu/module.h"
  27 #include <zlib.h>
  28
  29 /* Maximum compressed block size */
  30 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)
  31
  32 typedef struct BDRVCloopState {
  33     CoMutex lock;
  34     uint32_t block_size;
  35     uint32_t n_blocks;
  36     uint64_t *offsets;
  37     uint32_t sectors_per_block;
  38     uint32_t current_block;
  39     uint8_t *compressed_block;
  40     uint8_t *uncompressed_block;
  41     z_stream zstream;
  42 } BDRVCloopState;
  43
  44 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
  45 {
  46     const char *magic_version_2_0 = "#!/bin/sh\n"
  47         "#V2.0 Format\n"
  48         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
  49     int length = strlen(magic_version_2_0);
  50     if (length > buf_size) {
  51         length = buf_size;
  52     }
  53     if (!memcmp(magic_version_2_0, buf, length)) {
  54         return 2;
  55     }
  56     return 0;
  57 }
  58
  59 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
  60                       Error **errp)
  61 {
  62     BDRVCloopState *s = bs->opaque;
  63     uint32_t offsets_size, max_compressed_block_size = 1, i;
  64     int ret;
  65
  66     bs->read_only = 1;
  67
  68     /* read header */
  69     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
  70     if (ret < 0) {
  71         return ret;
  72     }
  73     s->block_size = be32_to_cpu(s->block_size);
  74     if (s->block_size % 512) {
  75         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
  76                    s->block_size);
  77         return -EINVAL;
  78     }
  79     if (s->block_size == 0) {
  80         error_setg(errp, "block_size cannot be zero");
  81         return -EINVAL;
  82     }
  83
  84     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
  85      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
  86      * need a buffer this big.
  87      */
  88     if (s->block_size > MAX_BLOCK_SIZE) {
  89         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
  90                    s->block_size,
  91                    MAX_BLOCK_SIZE / (1024 * 1024));
  92         return -EINVAL;
  93     }
  94
  95     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
  96     if (ret < 0) {
  97         return ret;
  98     }
  99     s->n_blocks = be32_to_cpu(s->n_blocks);
 100
 101     /* read offsets */
 102     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
 103         /* Prevent integer overflow */
 104         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
 105                    s->n_blocks,
 106                    (UINT32_MAX - 1) / sizeof(uint64_t));
 107         return -EINVAL;
 108     }
 109     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
 110     if (offsets_size > 512 * 1024 * 1024) {
 111         /* Prevent ridiculous offsets_size which causes memory allocation to
 112          * fail or overflows bdrv_pread() size.  In practice the 512 MB
 113          * offsets[] limit supports 16 TB images at 256 KB block size.
 114          */
 115         error_setg(errp, "image requires too many offsets, "
 116                    "try increasing block size");
 117         return -EINVAL;
 118     }
 119     s->offsets = g_malloc(offsets_size);
 120
 121     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
 122     if (ret < 0) {
 123         goto fail;
 124     }
 125
 126     for (i = 0; i < s->n_blocks + 1; i++) {
 127         uint64_t size;
 128
 129         s->offsets[i] = be64_to_cpu(s->offsets[i]);
 130         if (i == 0) {
 131             continue;
 132         }
 133
 134         if (s->offsets[i] < s->offsets[i - 1]) {
 135             error_setg(errp, "offsets not monotonically increasing at "
 136                        "index %" PRIu32 ", image file is corrupt", i);
 137             ret = -EINVAL;
 138             goto fail;
 139         }
 140
 141         size = s->offsets[i] - s->offsets[i - 1];
 142
 143         /* Compressed blocks should be smaller than the uncompressed block size
 144          * but maybe compression performed poorly so the compressed block is
 145          * actually bigger.  Clamp down on unrealistic values to prevent
 146          * ridiculous s->compressed_block allocation.
 147          */
 148         if (size > 2 * MAX_BLOCK_SIZE) {
 149             error_setg(errp, "invalid compressed block size at index %" PRIu32
 150                        ", image file is corrupt", i);
 151             ret = -EINVAL;
 152             goto fail;
 153         }
 154
 155         if (size > max_compressed_block_size) {
 156             max_compressed_block_size = size;
 157         }
 158     }
 159
 160     /* initialize zlib engine */
 161     s->compressed_block = g_malloc(max_compressed_block_size + 1);
 162     s->uncompressed_block = g_malloc(s->block_size);
 163     if (inflateInit(&s->zstream) != Z_OK) {
 164         ret = -EINVAL;
 165         goto fail;
 166     }
 167     s->current_block = s->n_blocks;
 168
 169     s->sectors_per_block = s->block_size/512;
 170     bs->total_sectors = s->n_blocks * s->sectors_per_block;
 171     qemu_co_mutex_init(&s->lock);
 172     return 0;
 173
 174 fail:
 175     g_free(s->offsets);
 176     g_free(s->compressed_block);
 177     g_free(s->uncompressed_block);
 178     return ret;
 179 }
 180
 181 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 182 {
 183     BDRVCloopState *s = bs->opaque;
 184
 185     if (s->current_block != block_num) {
 186         int ret;
 187         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
 188
 189         ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
 190                          bytes);
 191         if (ret != bytes) {
 192             return -1;
 193         }
 194
 195         s->zstream.next_in = s->compressed_block;
 196         s->zstream.avail_in = bytes;
 197         s->zstream.next_out = s->uncompressed_block;
 198         s->zstream.avail_out = s->block_size;
 199         ret = inflateReset(&s->zstream);
 200         if (ret != Z_OK) {
 201             return -1;
 202         }
 203         ret = inflate(&s->zstream, Z_FINISH);
 204         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
 205             return -1;
 206         }
 207
 208         s->current_block = block_num;
 209     }
 210     return 0;
 211 }
 212
 213 static int cloop_read(BlockDriverState *bs, int64_t sector_num,
 214                     uint8_t *buf, int nb_sectors)
 215 {
 216     BDRVCloopState *s = bs->opaque;
 217     int i;
 218
 219     for (i = 0; i < nb_sectors; i++) {
 220         uint32_t sector_offset_in_block =
 221             ((sector_num + i) % s->sectors_per_block),
 222             block_num = (sector_num + i) / s->sectors_per_block;
 223         if (cloop_read_block(bs, block_num) != 0) {
 224             return -1;
 225         }
 226         memcpy(buf + i * 512,
 227             s->uncompressed_block + sector_offset_in_block * 512, 512);
 228     }
 229     return 0;
 230 }
 231
 232 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
 233                                       uint8_t *buf, int nb_sectors)
 234 {
 235     int ret;
 236     BDRVCloopState *s = bs->opaque;
 237     qemu_co_mutex_lock(&s->lock);
 238     ret = cloop_read(bs, sector_num, buf, nb_sectors);
 239     qemu_co_mutex_unlock(&s->lock);
 240     return ret;
 241 }
 242
 243 static void cloop_close(BlockDriverState *bs)
 244 {
 245     BDRVCloopState *s = bs->opaque;
 246     g_free(s->offsets);
 247     g_free(s->compressed_block);
 248     g_free(s->uncompressed_block);
 249     inflateEnd(&s->zstream);
 250 }
 251
 252 static BlockDriver bdrv_cloop = {
 253     .format_name    = "cloop",
 254     .instance_size  = sizeof(BDRVCloopState),
 255     .bdrv_probe     = cloop_probe,
 256     .bdrv_open      = cloop_open,
 257     .bdrv_read      = cloop_co_read,
 258     .bdrv_close     = cloop_close,
 259 };
 260
 261 static void bdrv_cloop_init(void)
 262 {
 263     bdrv_register(&bdrv_cloop);
 264 }
 265
 266 block_init(bdrv_cloop_init);