1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * super.c
9 */
10
11 /*
12 * This file implements code to read the superblock, read and initialise
13 * in-memory structures at mount time, and all the VFS glue code to register
14 * the filesystem.
15 */
16
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19 #include <linux/blkdev.h>
20 #include <linux/fs.h>
21 #include <linux/fs_context.h>
22 #include <linux/fs_parser.h>
23 #include <linux/vfs.h>
24 #include <linux/slab.h>
25 #include <linux/mutex.h>
26 #include <linux/seq_file.h>
27 #include <linux/pagemap.h>
28 #include <linux/init.h>
29 #include <linux/module.h>
30 #include <linux/magic.h>
31 #include <linux/xattr.h>
32
33 #include "squashfs_fs.h"
34 #include "squashfs_fs_sb.h"
35 #include "squashfs_fs_i.h"
36 #include "squashfs.h"
37 #include "decompressor.h"
38 #include "xattr.h"
39
40 static struct file_system_type squashfs_fs_type;
41 static const struct super_operations squashfs_super_ops;
42
43 enum Opt_errors {
44 Opt_errors_continue,
45 Opt_errors_panic,
46 };
47
48 enum squashfs_param {
49 Opt_errors,
50 };
51
52 struct squashfs_mount_opts {
53 enum Opt_errors errors;
54 };
55
56 static const struct constant_table squashfs_param_errors[] = {
57 {"continue", Opt_errors_continue },
58 {"panic", Opt_errors_panic },
59 {}
60 };
61
62 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
63 fsparam_enum("errors", Opt_errors, squashfs_param_errors),
64 {}
65 };
66
squashfs_parse_param(struct fs_context * fc,struct fs_parameter * param)67 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
68 {
69 struct squashfs_mount_opts *opts = fc->fs_private;
70 struct fs_parse_result result;
71 int opt;
72
73 opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
74 if (opt < 0)
75 return opt;
76
77 switch (opt) {
78 case Opt_errors:
79 opts->errors = result.uint_32;
80 break;
81 default:
82 return -EINVAL;
83 }
84
85 return 0;
86 }
87
supported_squashfs_filesystem(struct fs_context * fc,short major,short minor,short id)88 static const struct squashfs_decompressor *supported_squashfs_filesystem(
89 struct fs_context *fc,
90 short major, short minor, short id)
91 {
92 const struct squashfs_decompressor *decompressor;
93
94 if (major < SQUASHFS_MAJOR) {
95 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
96 "filesystems are unsupported", major, minor);
97 return NULL;
98 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
99 errorf(fc, "Major/Minor mismatch, trying to mount newer "
100 "%d.%d filesystem", major, minor);
101 errorf(fc, "Please update your kernel");
102 return NULL;
103 }
104
105 decompressor = squashfs_lookup_decompressor(id);
106 if (!decompressor->supported) {
107 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
108 decompressor->name);
109 return NULL;
110 }
111
112 return decompressor;
113 }
114
115
squashfs_fill_super(struct super_block * sb,struct fs_context * fc)116 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
117 {
118 struct squashfs_mount_opts *opts = fc->fs_private;
119 struct squashfs_sb_info *msblk;
120 struct squashfs_super_block *sblk = NULL;
121 struct inode *root;
122 long long root_inode;
123 unsigned short flags;
124 unsigned int fragments;
125 u64 lookup_table_start, xattr_id_table_start, next_table;
126 int err;
127
128 TRACE("Entered squashfs_fill_superblock\n");
129
130 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
131 if (sb->s_fs_info == NULL) {
132 ERROR("Failed to allocate squashfs_sb_info\n");
133 return -ENOMEM;
134 }
135 msblk = sb->s_fs_info;
136
137 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
138
139 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
140 msblk->devblksize_log2 = ffz(~msblk->devblksize);
141
142 mutex_init(&msblk->meta_index_mutex);
143
144 /*
145 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
146 * are not beyond filesystem end. But as we're using
147 * squashfs_read_table here to read the superblock (including the value
148 * of bytes_used) we need to set it to an initial sensible dummy value
149 */
150 msblk->bytes_used = sizeof(*sblk);
151 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
152
153 if (IS_ERR(sblk)) {
154 errorf(fc, "unable to read squashfs_super_block");
155 err = PTR_ERR(sblk);
156 sblk = NULL;
157 goto failed_mount;
158 }
159
160 err = -EINVAL;
161
162 /* Check it is a SQUASHFS superblock */
163 sb->s_magic = le32_to_cpu(sblk->s_magic);
164 if (sb->s_magic != SQUASHFS_MAGIC) {
165 if (!(fc->sb_flags & SB_SILENT))
166 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
167 sb->s_bdev);
168 goto failed_mount;
169 }
170
171 /* Check the MAJOR & MINOR versions and lookup compression type */
172 msblk->decompressor = supported_squashfs_filesystem(
173 fc,
174 le16_to_cpu(sblk->s_major),
175 le16_to_cpu(sblk->s_minor),
176 le16_to_cpu(sblk->compression));
177 if (msblk->decompressor == NULL)
178 goto failed_mount;
179
180 /* Check the filesystem does not extend beyond the end of the
181 block device */
182 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
183 if (msblk->bytes_used < 0 ||
184 msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
185 goto failed_mount;
186
187 /* Check block size for sanity */
188 msblk->block_size = le32_to_cpu(sblk->block_size);
189 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
190 goto insanity;
191
192 /*
193 * Check the system page size is not larger than the filesystem
194 * block size (by default 128K). This is currently not supported.
195 */
196 if (PAGE_SIZE > msblk->block_size) {
197 errorf(fc, "Page size > filesystem block size (%d). This is "
198 "currently not supported!", msblk->block_size);
199 goto failed_mount;
200 }
201
202 /* Check block log for sanity */
203 msblk->block_log = le16_to_cpu(sblk->block_log);
204 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
205 goto failed_mount;
206
207 /* Check that block_size and block_log match */
208 if (msblk->block_size != (1 << msblk->block_log))
209 goto insanity;
210
211 /* Check the root inode for sanity */
212 root_inode = le64_to_cpu(sblk->root_inode);
213 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
214 goto insanity;
215
216 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
217 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
218 msblk->inodes = le32_to_cpu(sblk->inodes);
219 msblk->fragments = le32_to_cpu(sblk->fragments);
220 msblk->ids = le16_to_cpu(sblk->no_ids);
221 flags = le16_to_cpu(sblk->flags);
222
223 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
224 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
225 ? "un" : "");
226 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
227 ? "un" : "");
228 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
229 TRACE("Block size %d\n", msblk->block_size);
230 TRACE("Number of inodes %d\n", msblk->inodes);
231 TRACE("Number of fragments %d\n", msblk->fragments);
232 TRACE("Number of ids %d\n", msblk->ids);
233 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
234 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
235 TRACE("sblk->fragment_table_start %llx\n",
236 (u64) le64_to_cpu(sblk->fragment_table_start));
237 TRACE("sblk->id_table_start %llx\n",
238 (u64) le64_to_cpu(sblk->id_table_start));
239
240 sb->s_maxbytes = MAX_LFS_FILESIZE;
241 sb->s_time_min = 0;
242 sb->s_time_max = U32_MAX;
243 sb->s_flags |= SB_RDONLY;
244 sb->s_op = &squashfs_super_ops;
245
246 err = -ENOMEM;
247
248 msblk->block_cache = squashfs_cache_init("metadata",
249 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
250 if (msblk->block_cache == NULL)
251 goto failed_mount;
252
253 /* Allocate read_page block */
254 msblk->read_page = squashfs_cache_init("data",
255 squashfs_max_decompressors(), msblk->block_size);
256 if (msblk->read_page == NULL) {
257 errorf(fc, "Failed to allocate read_page block");
258 goto failed_mount;
259 }
260
261 msblk->stream = squashfs_decompressor_setup(sb, flags);
262 if (IS_ERR(msblk->stream)) {
263 err = PTR_ERR(msblk->stream);
264 msblk->stream = NULL;
265 goto insanity;
266 }
267
268 /* Handle xattrs */
269 sb->s_xattr = squashfs_xattr_handlers;
270 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
271 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
272 next_table = msblk->bytes_used;
273 goto allocate_id_index_table;
274 }
275
276 /* Allocate and read xattr id lookup table */
277 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
278 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
279 if (IS_ERR(msblk->xattr_id_table)) {
280 errorf(fc, "unable to read xattr id index table");
281 err = PTR_ERR(msblk->xattr_id_table);
282 msblk->xattr_id_table = NULL;
283 if (err != -ENOTSUPP)
284 goto failed_mount;
285 }
286 next_table = msblk->xattr_table;
287
288 allocate_id_index_table:
289 /* Allocate and read id index table */
290 msblk->id_table = squashfs_read_id_index_table(sb,
291 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
292 if (IS_ERR(msblk->id_table)) {
293 errorf(fc, "unable to read id index table");
294 err = PTR_ERR(msblk->id_table);
295 msblk->id_table = NULL;
296 goto failed_mount;
297 }
298 next_table = le64_to_cpu(msblk->id_table[0]);
299
300 /* Handle inode lookup table */
301 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
302 if (lookup_table_start == SQUASHFS_INVALID_BLK)
303 goto handle_fragments;
304
305 /* Allocate and read inode lookup table */
306 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
307 lookup_table_start, next_table, msblk->inodes);
308 if (IS_ERR(msblk->inode_lookup_table)) {
309 errorf(fc, "unable to read inode lookup table");
310 err = PTR_ERR(msblk->inode_lookup_table);
311 msblk->inode_lookup_table = NULL;
312 goto failed_mount;
313 }
314 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
315
316 sb->s_export_op = &squashfs_export_ops;
317
318 handle_fragments:
319 fragments = msblk->fragments;
320 if (fragments == 0)
321 goto check_directory_table;
322
323 msblk->fragment_cache = squashfs_cache_init("fragment",
324 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
325 if (msblk->fragment_cache == NULL) {
326 err = -ENOMEM;
327 goto failed_mount;
328 }
329
330 /* Allocate and read fragment index table */
331 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
332 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
333 if (IS_ERR(msblk->fragment_index)) {
334 errorf(fc, "unable to read fragment index table");
335 err = PTR_ERR(msblk->fragment_index);
336 msblk->fragment_index = NULL;
337 goto failed_mount;
338 }
339 next_table = le64_to_cpu(msblk->fragment_index[0]);
340
341 check_directory_table:
342 /* Sanity check directory_table */
343 if (msblk->directory_table > next_table) {
344 err = -EINVAL;
345 goto insanity;
346 }
347
348 /* Sanity check inode_table */
349 if (msblk->inode_table >= msblk->directory_table) {
350 err = -EINVAL;
351 goto insanity;
352 }
353
354 /* allocate root */
355 root = new_inode(sb);
356 if (!root) {
357 err = -ENOMEM;
358 goto failed_mount;
359 }
360
361 err = squashfs_read_inode(root, root_inode);
362 if (err) {
363 make_bad_inode(root);
364 iput(root);
365 goto failed_mount;
366 }
367 insert_inode_hash(root);
368
369 sb->s_root = d_make_root(root);
370 if (sb->s_root == NULL) {
371 ERROR("Root inode create failed\n");
372 err = -ENOMEM;
373 goto failed_mount;
374 }
375
376 TRACE("Leaving squashfs_fill_super\n");
377 kfree(sblk);
378 return 0;
379
380 insanity:
381 errorf(fc, "squashfs image failed sanity check");
382 failed_mount:
383 squashfs_cache_delete(msblk->block_cache);
384 squashfs_cache_delete(msblk->fragment_cache);
385 squashfs_cache_delete(msblk->read_page);
386 squashfs_decompressor_destroy(msblk);
387 kfree(msblk->inode_lookup_table);
388 kfree(msblk->fragment_index);
389 kfree(msblk->id_table);
390 kfree(msblk->xattr_id_table);
391 kfree(sb->s_fs_info);
392 sb->s_fs_info = NULL;
393 kfree(sblk);
394 return err;
395 }
396
squashfs_get_tree(struct fs_context * fc)397 static int squashfs_get_tree(struct fs_context *fc)
398 {
399 return get_tree_bdev(fc, squashfs_fill_super);
400 }
401
squashfs_reconfigure(struct fs_context * fc)402 static int squashfs_reconfigure(struct fs_context *fc)
403 {
404 struct super_block *sb = fc->root->d_sb;
405 struct squashfs_sb_info *msblk = sb->s_fs_info;
406 struct squashfs_mount_opts *opts = fc->fs_private;
407
408 sync_filesystem(fc->root->d_sb);
409 fc->sb_flags |= SB_RDONLY;
410
411 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
412
413 return 0;
414 }
415
squashfs_free_fs_context(struct fs_context * fc)416 static void squashfs_free_fs_context(struct fs_context *fc)
417 {
418 kfree(fc->fs_private);
419 }
420
421 static const struct fs_context_operations squashfs_context_ops = {
422 .get_tree = squashfs_get_tree,
423 .free = squashfs_free_fs_context,
424 .parse_param = squashfs_parse_param,
425 .reconfigure = squashfs_reconfigure,
426 };
427
squashfs_show_options(struct seq_file * s,struct dentry * root)428 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
429 {
430 struct super_block *sb = root->d_sb;
431 struct squashfs_sb_info *msblk = sb->s_fs_info;
432
433 if (msblk->panic_on_errors)
434 seq_puts(s, ",errors=panic");
435 else
436 seq_puts(s, ",errors=continue");
437
438 return 0;
439 }
440
squashfs_init_fs_context(struct fs_context * fc)441 static int squashfs_init_fs_context(struct fs_context *fc)
442 {
443 struct squashfs_mount_opts *opts;
444
445 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
446 if (!opts)
447 return -ENOMEM;
448
449 fc->fs_private = opts;
450 fc->ops = &squashfs_context_ops;
451 return 0;
452 }
453
squashfs_statfs(struct dentry * dentry,struct kstatfs * buf)454 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
455 {
456 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
457 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
458
459 TRACE("Entered squashfs_statfs\n");
460
461 buf->f_type = SQUASHFS_MAGIC;
462 buf->f_bsize = msblk->block_size;
463 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
464 buf->f_bfree = buf->f_bavail = 0;
465 buf->f_files = msblk->inodes;
466 buf->f_ffree = 0;
467 buf->f_namelen = SQUASHFS_NAME_LEN;
468 buf->f_fsid = u64_to_fsid(id);
469
470 return 0;
471 }
472
473
squashfs_put_super(struct super_block * sb)474 static void squashfs_put_super(struct super_block *sb)
475 {
476 if (sb->s_fs_info) {
477 struct squashfs_sb_info *sbi = sb->s_fs_info;
478 squashfs_cache_delete(sbi->block_cache);
479 squashfs_cache_delete(sbi->fragment_cache);
480 squashfs_cache_delete(sbi->read_page);
481 squashfs_decompressor_destroy(sbi);
482 kfree(sbi->id_table);
483 kfree(sbi->fragment_index);
484 kfree(sbi->meta_index);
485 kfree(sbi->inode_lookup_table);
486 kfree(sbi->xattr_id_table);
487 kfree(sb->s_fs_info);
488 sb->s_fs_info = NULL;
489 }
490 }
491
492 static struct kmem_cache *squashfs_inode_cachep;
493
494
init_once(void * foo)495 static void init_once(void *foo)
496 {
497 struct squashfs_inode_info *ei = foo;
498
499 inode_init_once(&ei->vfs_inode);
500 }
501
502
init_inodecache(void)503 static int __init init_inodecache(void)
504 {
505 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
506 sizeof(struct squashfs_inode_info), 0,
507 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
508 init_once);
509
510 return squashfs_inode_cachep ? 0 : -ENOMEM;
511 }
512
513
destroy_inodecache(void)514 static void destroy_inodecache(void)
515 {
516 /*
517 * Make sure all delayed rcu free inodes are flushed before we
518 * destroy cache.
519 */
520 rcu_barrier();
521 kmem_cache_destroy(squashfs_inode_cachep);
522 }
523
524
init_squashfs_fs(void)525 static int __init init_squashfs_fs(void)
526 {
527 int err = init_inodecache();
528
529 if (err)
530 return err;
531
532 err = register_filesystem(&squashfs_fs_type);
533 if (err) {
534 destroy_inodecache();
535 return err;
536 }
537
538 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
539
540 return 0;
541 }
542
543
exit_squashfs_fs(void)544 static void __exit exit_squashfs_fs(void)
545 {
546 unregister_filesystem(&squashfs_fs_type);
547 destroy_inodecache();
548 }
549
550
squashfs_alloc_inode(struct super_block * sb)551 static struct inode *squashfs_alloc_inode(struct super_block *sb)
552 {
553 struct squashfs_inode_info *ei =
554 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
555
556 return ei ? &ei->vfs_inode : NULL;
557 }
558
559
squashfs_free_inode(struct inode * inode)560 static void squashfs_free_inode(struct inode *inode)
561 {
562 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
563 }
564
565 static struct file_system_type squashfs_fs_type = {
566 .owner = THIS_MODULE,
567 .name = "squashfs",
568 .init_fs_context = squashfs_init_fs_context,
569 .parameters = squashfs_fs_parameters,
570 .kill_sb = kill_block_super,
571 .fs_flags = FS_REQUIRES_DEV
572 };
573 MODULE_ALIAS_FS("squashfs");
574
575 static const struct super_operations squashfs_super_ops = {
576 .alloc_inode = squashfs_alloc_inode,
577 .free_inode = squashfs_free_inode,
578 .statfs = squashfs_statfs,
579 .put_super = squashfs_put_super,
580 .show_options = squashfs_show_options,
581 };
582
583 module_init(init_squashfs_fs);
584 module_exit(exit_squashfs_fs);
585 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
586 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
587 MODULE_LICENSE("GPL");
588
