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/fs.h>
20 #include <linux/fs_context.h>
21 #include <linux/fs_parser.h>
22 #include <linux/vfs.h>
23 #include <linux/slab.h>
24 #include <linux/mutex.h>
25 #include <linux/seq_file.h>
26 #include <linux/pagemap.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/magic.h>
30 #include <linux/xattr.h>
31
32 #include "squashfs_fs.h"
33 #include "squashfs_fs_sb.h"
34 #include "squashfs_fs_i.h"
35 #include "squashfs.h"
36 #include "decompressor.h"
37 #include "xattr.h"
38
39 static struct file_system_type squashfs_fs_type;
40 static const struct super_operations squashfs_super_ops;
41
42 enum Opt_errors {
43 Opt_errors_continue,
44 Opt_errors_panic,
45 };
46
47 enum squashfs_param {
48 Opt_errors,
49 };
50
51 struct squashfs_mount_opts {
52 enum Opt_errors errors;
53 };
54
55 static const struct constant_table squashfs_param_errors[] = {
56 {"continue", Opt_errors_continue },
57 {"panic", Opt_errors_panic },
58 {}
59 };
60
61 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
62 fsparam_enum("errors", Opt_errors, squashfs_param_errors),
63 {}
64 };
65
squashfs_parse_param(struct fs_context * fc,struct fs_parameter * param)66 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
67 {
68 struct squashfs_mount_opts *opts = fc->fs_private;
69 struct fs_parse_result result;
70 int opt;
71
72 opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
73 if (opt < 0)
74 return opt;
75
76 switch (opt) {
77 case Opt_errors:
78 opts->errors = result.uint_32;
79 break;
80 default:
81 return -EINVAL;
82 }
83
84 return 0;
85 }
86
supported_squashfs_filesystem(struct fs_context * fc,short major,short minor,short id)87 static const struct squashfs_decompressor *supported_squashfs_filesystem(
88 struct fs_context *fc,
89 short major, short minor, short id)
90 {
91 const struct squashfs_decompressor *decompressor;
92
93 if (major < SQUASHFS_MAJOR) {
94 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
95 "filesystems are unsupported", major, minor);
96 return NULL;
97 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
98 errorf(fc, "Major/Minor mismatch, trying to mount newer "
99 "%d.%d filesystem", major, minor);
100 errorf(fc, "Please update your kernel");
101 return NULL;
102 }
103
104 decompressor = squashfs_lookup_decompressor(id);
105 if (!decompressor->supported) {
106 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
107 decompressor->name);
108 return NULL;
109 }
110
111 return decompressor;
112 }
113
114
squashfs_fill_super(struct super_block * sb,struct fs_context * fc)115 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
116 {
117 struct squashfs_mount_opts *opts = fc->fs_private;
118 struct squashfs_sb_info *msblk;
119 struct squashfs_super_block *sblk = NULL;
120 struct inode *root;
121 long long root_inode;
122 unsigned short flags;
123 unsigned int fragments;
124 u64 lookup_table_start, xattr_id_table_start, next_table;
125 int err;
126
127 TRACE("Entered squashfs_fill_superblock\n");
128
129 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
130 if (sb->s_fs_info == NULL) {
131 ERROR("Failed to allocate squashfs_sb_info\n");
132 return -ENOMEM;
133 }
134 msblk = sb->s_fs_info;
135
136 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
137
138 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
139 msblk->devblksize_log2 = ffz(~msblk->devblksize);
140
141 mutex_init(&msblk->meta_index_mutex);
142
143 /*
144 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
145 * are not beyond filesystem end. But as we're using
146 * squashfs_read_table here to read the superblock (including the value
147 * of bytes_used) we need to set it to an initial sensible dummy value
148 */
149 msblk->bytes_used = sizeof(*sblk);
150 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
151
152 if (IS_ERR(sblk)) {
153 errorf(fc, "unable to read squashfs_super_block");
154 err = PTR_ERR(sblk);
155 sblk = NULL;
156 goto failed_mount;
157 }
158
159 err = -EINVAL;
160
161 /* Check it is a SQUASHFS superblock */
162 sb->s_magic = le32_to_cpu(sblk->s_magic);
163 if (sb->s_magic != SQUASHFS_MAGIC) {
164 if (!(fc->sb_flags & SB_SILENT))
165 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
166 sb->s_bdev);
167 goto failed_mount;
168 }
169
170 /* Check the MAJOR & MINOR versions and lookup compression type */
171 msblk->decompressor = supported_squashfs_filesystem(
172 fc,
173 le16_to_cpu(sblk->s_major),
174 le16_to_cpu(sblk->s_minor),
175 le16_to_cpu(sblk->compression));
176 if (msblk->decompressor == NULL)
177 goto failed_mount;
178
179 /* Check the filesystem does not extend beyond the end of the
180 block device */
181 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
182 if (msblk->bytes_used < 0 || msblk->bytes_used >
183 i_size_read(sb->s_bdev->bd_inode))
184 goto failed_mount;
185
186 /* Check block size for sanity */
187 msblk->block_size = le32_to_cpu(sblk->block_size);
188 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
189 goto insanity;
190
191 /*
192 * Check the system page size is not larger than the filesystem
193 * block size (by default 128K). This is currently not supported.
194 */
195 if (PAGE_SIZE > msblk->block_size) {
196 errorf(fc, "Page size > filesystem block size (%d). This is "
197 "currently not supported!", msblk->block_size);
198 goto failed_mount;
199 }
200
201 /* Check block log for sanity */
202 msblk->block_log = le16_to_cpu(sblk->block_log);
203 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
204 goto failed_mount;
205
206 /* Check that block_size and block_log match */
207 if (msblk->block_size != (1 << msblk->block_log))
208 goto insanity;
209
210 /* Check the root inode for sanity */
211 root_inode = le64_to_cpu(sblk->root_inode);
212 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
213 goto insanity;
214
215 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
216 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
217 msblk->inodes = le32_to_cpu(sblk->inodes);
218 msblk->fragments = le32_to_cpu(sblk->fragments);
219 msblk->ids = le16_to_cpu(sblk->no_ids);
220 flags = le16_to_cpu(sblk->flags);
221
222 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
223 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
224 ? "un" : "");
225 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
226 ? "un" : "");
227 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
228 TRACE("Block size %d\n", msblk->block_size);
229 TRACE("Number of inodes %d\n", msblk->inodes);
230 TRACE("Number of fragments %d\n", msblk->fragments);
231 TRACE("Number of ids %d\n", msblk->ids);
232 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
233 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
234 TRACE("sblk->fragment_table_start %llx\n",
235 (u64) le64_to_cpu(sblk->fragment_table_start));
236 TRACE("sblk->id_table_start %llx\n",
237 (u64) le64_to_cpu(sblk->id_table_start));
238
239 sb->s_maxbytes = MAX_LFS_FILESIZE;
240 sb->s_time_min = 0;
241 sb->s_time_max = U32_MAX;
242 sb->s_flags |= SB_RDONLY;
243 sb->s_op = &squashfs_super_ops;
244
245 err = -ENOMEM;
246
247 msblk->block_cache = squashfs_cache_init("metadata",
248 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
249 if (msblk->block_cache == NULL)
250 goto failed_mount;
251
252 /* Allocate read_page block */
253 msblk->read_page = squashfs_cache_init("data",
254 squashfs_max_decompressors(), msblk->block_size);
255 if (msblk->read_page == NULL) {
256 errorf(fc, "Failed to allocate read_page block");
257 goto failed_mount;
258 }
259
260 if (msblk->devblksize == PAGE_SIZE) {
261 struct inode *cache = new_inode(sb);
262
263 if (cache == NULL)
264 goto failed_mount;
265
266 set_nlink(cache, 1);
267 cache->i_size = OFFSET_MAX;
268 mapping_set_gfp_mask(cache->i_mapping, GFP_NOFS);
269
270 msblk->cache_mapping = cache->i_mapping;
271 }
272
273 msblk->stream = squashfs_decompressor_setup(sb, flags);
274 if (IS_ERR(msblk->stream)) {
275 err = PTR_ERR(msblk->stream);
276 msblk->stream = NULL;
277 goto insanity;
278 }
279
280 /* Handle xattrs */
281 sb->s_xattr = squashfs_xattr_handlers;
282 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
283 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
284 next_table = msblk->bytes_used;
285 goto allocate_id_index_table;
286 }
287
288 /* Allocate and read xattr id lookup table */
289 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
290 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
291 if (IS_ERR(msblk->xattr_id_table)) {
292 errorf(fc, "unable to read xattr id index table");
293 err = PTR_ERR(msblk->xattr_id_table);
294 msblk->xattr_id_table = NULL;
295 if (err != -ENOTSUPP)
296 goto failed_mount;
297 }
298 next_table = msblk->xattr_table;
299
300 allocate_id_index_table:
301 /* Allocate and read id index table */
302 msblk->id_table = squashfs_read_id_index_table(sb,
303 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
304 if (IS_ERR(msblk->id_table)) {
305 errorf(fc, "unable to read id index table");
306 err = PTR_ERR(msblk->id_table);
307 msblk->id_table = NULL;
308 goto failed_mount;
309 }
310 next_table = le64_to_cpu(msblk->id_table[0]);
311
312 /* Handle inode lookup table */
313 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
314 if (lookup_table_start == SQUASHFS_INVALID_BLK)
315 goto handle_fragments;
316
317 /* Allocate and read inode lookup table */
318 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
319 lookup_table_start, next_table, msblk->inodes);
320 if (IS_ERR(msblk->inode_lookup_table)) {
321 errorf(fc, "unable to read inode lookup table");
322 err = PTR_ERR(msblk->inode_lookup_table);
323 msblk->inode_lookup_table = NULL;
324 goto failed_mount;
325 }
326 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
327
328 sb->s_export_op = &squashfs_export_ops;
329
330 handle_fragments:
331 fragments = msblk->fragments;
332 if (fragments == 0)
333 goto check_directory_table;
334
335 msblk->fragment_cache = squashfs_cache_init("fragment",
336 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
337 if (msblk->fragment_cache == NULL) {
338 err = -ENOMEM;
339 goto failed_mount;
340 }
341
342 /* Allocate and read fragment index table */
343 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
344 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
345 if (IS_ERR(msblk->fragment_index)) {
346 errorf(fc, "unable to read fragment index table");
347 err = PTR_ERR(msblk->fragment_index);
348 msblk->fragment_index = NULL;
349 goto failed_mount;
350 }
351 next_table = le64_to_cpu(msblk->fragment_index[0]);
352
353 check_directory_table:
354 /* Sanity check directory_table */
355 if (msblk->directory_table > next_table) {
356 err = -EINVAL;
357 goto insanity;
358 }
359
360 /* Sanity check inode_table */
361 if (msblk->inode_table >= msblk->directory_table) {
362 err = -EINVAL;
363 goto insanity;
364 }
365
366 /* allocate root */
367 root = new_inode(sb);
368 if (!root) {
369 err = -ENOMEM;
370 goto failed_mount;
371 }
372
373 err = squashfs_read_inode(root, root_inode);
374 if (err) {
375 make_bad_inode(root);
376 iput(root);
377 goto failed_mount;
378 }
379 insert_inode_hash(root);
380
381 sb->s_root = d_make_root(root);
382 if (sb->s_root == NULL) {
383 ERROR("Root inode create failed\n");
384 err = -ENOMEM;
385 goto failed_mount;
386 }
387
388 TRACE("Leaving squashfs_fill_super\n");
389 kfree(sblk);
390 return 0;
391
392 insanity:
393 errorf(fc, "squashfs image failed sanity check");
394 failed_mount:
395 squashfs_cache_delete(msblk->block_cache);
396 squashfs_cache_delete(msblk->fragment_cache);
397 squashfs_cache_delete(msblk->read_page);
398 squashfs_decompressor_destroy(msblk);
399 if (msblk->cache_mapping)
400 iput(msblk->cache_mapping->host);
401 kfree(msblk->inode_lookup_table);
402 kfree(msblk->fragment_index);
403 kfree(msblk->id_table);
404 kfree(msblk->xattr_id_table);
405 kfree(sb->s_fs_info);
406 sb->s_fs_info = NULL;
407 kfree(sblk);
408 return err;
409 }
410
squashfs_get_tree(struct fs_context * fc)411 static int squashfs_get_tree(struct fs_context *fc)
412 {
413 return get_tree_bdev(fc, squashfs_fill_super);
414 }
415
squashfs_reconfigure(struct fs_context * fc)416 static int squashfs_reconfigure(struct fs_context *fc)
417 {
418 struct super_block *sb = fc->root->d_sb;
419 struct squashfs_sb_info *msblk = sb->s_fs_info;
420 struct squashfs_mount_opts *opts = fc->fs_private;
421
422 sync_filesystem(fc->root->d_sb);
423 fc->sb_flags |= SB_RDONLY;
424
425 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
426
427 return 0;
428 }
429
squashfs_free_fs_context(struct fs_context * fc)430 static void squashfs_free_fs_context(struct fs_context *fc)
431 {
432 kfree(fc->fs_private);
433 }
434
435 static const struct fs_context_operations squashfs_context_ops = {
436 .get_tree = squashfs_get_tree,
437 .free = squashfs_free_fs_context,
438 .parse_param = squashfs_parse_param,
439 .reconfigure = squashfs_reconfigure,
440 };
441
squashfs_show_options(struct seq_file * s,struct dentry * root)442 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
443 {
444 struct super_block *sb = root->d_sb;
445 struct squashfs_sb_info *msblk = sb->s_fs_info;
446
447 if (msblk->panic_on_errors)
448 seq_puts(s, ",errors=panic");
449 else
450 seq_puts(s, ",errors=continue");
451
452 return 0;
453 }
454
squashfs_init_fs_context(struct fs_context * fc)455 static int squashfs_init_fs_context(struct fs_context *fc)
456 {
457 struct squashfs_mount_opts *opts;
458
459 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
460 if (!opts)
461 return -ENOMEM;
462
463 fc->fs_private = opts;
464 fc->ops = &squashfs_context_ops;
465 return 0;
466 }
467
squashfs_statfs(struct dentry * dentry,struct kstatfs * buf)468 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
469 {
470 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
471 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
472
473 TRACE("Entered squashfs_statfs\n");
474
475 buf->f_type = SQUASHFS_MAGIC;
476 buf->f_bsize = msblk->block_size;
477 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
478 buf->f_bfree = buf->f_bavail = 0;
479 buf->f_files = msblk->inodes;
480 buf->f_ffree = 0;
481 buf->f_namelen = SQUASHFS_NAME_LEN;
482 buf->f_fsid = u64_to_fsid(id);
483
484 return 0;
485 }
486
487
squashfs_put_super(struct super_block * sb)488 static void squashfs_put_super(struct super_block *sb)
489 {
490 if (sb->s_fs_info) {
491 struct squashfs_sb_info *sbi = sb->s_fs_info;
492 squashfs_cache_delete(sbi->block_cache);
493 squashfs_cache_delete(sbi->fragment_cache);
494 squashfs_cache_delete(sbi->read_page);
495 squashfs_decompressor_destroy(sbi);
496 if (sbi->cache_mapping)
497 iput(sbi->cache_mapping->host);
498 kfree(sbi->id_table);
499 kfree(sbi->fragment_index);
500 kfree(sbi->meta_index);
501 kfree(sbi->inode_lookup_table);
502 kfree(sbi->xattr_id_table);
503 kfree(sb->s_fs_info);
504 sb->s_fs_info = NULL;
505 }
506 }
507
508 static struct kmem_cache *squashfs_inode_cachep;
509
510
init_once(void * foo)511 static void init_once(void *foo)
512 {
513 struct squashfs_inode_info *ei = foo;
514
515 inode_init_once(&ei->vfs_inode);
516 }
517
518
init_inodecache(void)519 static int __init init_inodecache(void)
520 {
521 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
522 sizeof(struct squashfs_inode_info), 0,
523 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
524 init_once);
525
526 return squashfs_inode_cachep ? 0 : -ENOMEM;
527 }
528
529
destroy_inodecache(void)530 static void destroy_inodecache(void)
531 {
532 /*
533 * Make sure all delayed rcu free inodes are flushed before we
534 * destroy cache.
535 */
536 rcu_barrier();
537 kmem_cache_destroy(squashfs_inode_cachep);
538 }
539
540
init_squashfs_fs(void)541 static int __init init_squashfs_fs(void)
542 {
543 int err = init_inodecache();
544
545 if (err)
546 return err;
547
548 err = register_filesystem(&squashfs_fs_type);
549 if (err) {
550 destroy_inodecache();
551 return err;
552 }
553
554 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
555
556 return 0;
557 }
558
559
exit_squashfs_fs(void)560 static void __exit exit_squashfs_fs(void)
561 {
562 unregister_filesystem(&squashfs_fs_type);
563 destroy_inodecache();
564 }
565
566
squashfs_alloc_inode(struct super_block * sb)567 static struct inode *squashfs_alloc_inode(struct super_block *sb)
568 {
569 struct squashfs_inode_info *ei =
570 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
571
572 return ei ? &ei->vfs_inode : NULL;
573 }
574
575
squashfs_free_inode(struct inode * inode)576 static void squashfs_free_inode(struct inode *inode)
577 {
578 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
579 }
580
581 static struct file_system_type squashfs_fs_type = {
582 .owner = THIS_MODULE,
583 .name = "squashfs",
584 .init_fs_context = squashfs_init_fs_context,
585 .parameters = squashfs_fs_parameters,
586 .kill_sb = kill_block_super,
587 .fs_flags = FS_REQUIRES_DEV
588 };
589 MODULE_ALIAS_FS("squashfs");
590
591 static const struct super_operations squashfs_super_ops = {
592 .alloc_inode = squashfs_alloc_inode,
593 .free_inode = squashfs_free_inode,
594 .statfs = squashfs_statfs,
595 .put_super = squashfs_put_super,
596 .show_options = squashfs_show_options,
597 };
598
599 module_init(init_squashfs_fs);
600 module_exit(exit_squashfs_fs);
601 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
602 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
603 MODULE_LICENSE("GPL");
604 MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
605