xref: /qemu/block/cloop.c (revision 9277d81f)
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);
315