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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
40static struct file_system_type squashfs_fs_type;
41static const struct super_operations squashfs_super_ops;
42
43enum Opt_errors {
44 Opt_errors_continue,
45 Opt_errors_panic,
46};
47
48enum squashfs_param {
49 Opt_errors,
50 Opt_threads,
51};
52
53struct squashfs_mount_opts {
54 enum Opt_errors errors;
55 const struct squashfs_decompressor_thread_ops *thread_ops;
56 int thread_num;
57};
58
59static const struct constant_table squashfs_param_errors[] = {
60 {"continue", Opt_errors_continue },
61 {"panic", Opt_errors_panic },
62 {}
63};
64
65static const struct fs_parameter_spec squashfs_fs_parameters[] = {
66 fsparam_enum("errors", Opt_errors, squashfs_param_errors),
67 fsparam_string("threads", Opt_threads),
68 {}
69};
70
71
72static int squashfs_parse_param_threads_str(const char *str, struct squashfs_mount_opts *opts)
73{
74#ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
75 if (strcmp(str, "single") == 0) {
76 opts->thread_ops = &squashfs_decompressor_single;
77 return 0;
78 }
79 if (strcmp(str, "multi") == 0) {
80 opts->thread_ops = &squashfs_decompressor_multi;
81 return 0;
82 }
83 if (strcmp(str, "percpu") == 0) {
84 opts->thread_ops = &squashfs_decompressor_percpu;
85 return 0;
86 }
87#endif
88 return -EINVAL;
89}
90
91static int squashfs_parse_param_threads_num(const char *str, struct squashfs_mount_opts *opts)
92{
93#ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
94 int ret;
95 unsigned long num;
96
97 ret = kstrtoul(str, 0, &num);
98 if (ret != 0)
99 return -EINVAL;
100 if (num > 1) {
101 opts->thread_ops = &squashfs_decompressor_multi;
102 if (num > opts->thread_ops->max_decompressors())
103 return -EINVAL;
104 opts->thread_num = (int)num;
105 return 0;
106 }
107#ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
108 if (num == 1) {
109 opts->thread_ops = &squashfs_decompressor_single;
110 opts->thread_num = 1;
111 return 0;
112 }
113#endif
114#endif /* !CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS */
115 return -EINVAL;
116}
117
118static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_opts *opts)
119{
120 int ret = squashfs_parse_param_threads_str(str, opts);
121
122 if (ret == 0)
123 return ret;
124 return squashfs_parse_param_threads_num(str, opts);
125}
126
127static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
128{
129 struct squashfs_mount_opts *opts = fc->fs_private;
130 struct fs_parse_result result;
131 int opt;
132
133 opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
134 if (opt < 0)
135 return opt;
136
137 switch (opt) {
138 case Opt_errors:
139 opts->errors = result.uint_32;
140 break;
141 case Opt_threads:
142 if (squashfs_parse_param_threads(param->string, opts) != 0)
143 return -EINVAL;
144 break;
145 default:
146 return -EINVAL;
147 }
148
149 return 0;
150}
151
152static const struct squashfs_decompressor *supported_squashfs_filesystem(
153 struct fs_context *fc,
154 short major, short minor, short id)
155{
156 const struct squashfs_decompressor *decompressor;
157
158 if (major < SQUASHFS_MAJOR) {
159 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
160 "filesystems are unsupported", major, minor);
161 return NULL;
162 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
163 errorf(fc, "Major/Minor mismatch, trying to mount newer "
164 "%d.%d filesystem", major, minor);
165 errorf(fc, "Please update your kernel");
166 return NULL;
167 }
168
169 decompressor = squashfs_lookup_decompressor(id);
170 if (!decompressor->supported) {
171 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
172 decompressor->name);
173 return NULL;
174 }
175
176 return decompressor;
177}
178
179
180static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
181{
182 struct squashfs_mount_opts *opts = fc->fs_private;
183 struct squashfs_sb_info *msblk;
184 struct squashfs_super_block *sblk = NULL;
185 struct inode *root;
186 long long root_inode;
187 unsigned short flags;
188 unsigned int fragments;
189 u64 lookup_table_start, xattr_id_table_start, next_table;
190 int err;
191
192 TRACE("Entered squashfs_fill_superblock\n");
193
194 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
195 if (sb->s_fs_info == NULL) {
196 ERROR("Failed to allocate squashfs_sb_info\n");
197 return -ENOMEM;
198 }
199 msblk = sb->s_fs_info;
200 msblk->thread_ops = opts->thread_ops;
201
202 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
203
204 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
205 msblk->devblksize_log2 = ffz(~msblk->devblksize);
206
207 mutex_init(&msblk->meta_index_mutex);
208
209 /*
210 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
211 * are not beyond filesystem end. But as we're using
212 * squashfs_read_table here to read the superblock (including the value
213 * of bytes_used) we need to set it to an initial sensible dummy value
214 */
215 msblk->bytes_used = sizeof(*sblk);
216 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
217
218 if (IS_ERR(sblk)) {
219 errorf(fc, "unable to read squashfs_super_block");
220 err = PTR_ERR(sblk);
221 sblk = NULL;
222 goto failed_mount;
223 }
224
225 err = -EINVAL;
226
227 /* Check it is a SQUASHFS superblock */
228 sb->s_magic = le32_to_cpu(sblk->s_magic);
229 if (sb->s_magic != SQUASHFS_MAGIC) {
230 if (!(fc->sb_flags & SB_SILENT))
231 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
232 sb->s_bdev);
233 goto failed_mount;
234 }
235
236 if (opts->thread_num == 0) {
237 msblk->max_thread_num = msblk->thread_ops->max_decompressors();
238 } else {
239 msblk->max_thread_num = opts->thread_num;
240 }
241
242 /* Check the MAJOR & MINOR versions and lookup compression type */
243 msblk->decompressor = supported_squashfs_filesystem(
244 fc,
245 le16_to_cpu(sblk->s_major),
246 le16_to_cpu(sblk->s_minor),
247 le16_to_cpu(sblk->compression));
248 if (msblk->decompressor == NULL)
249 goto failed_mount;
250
251 /* Check the filesystem does not extend beyond the end of the
252 block device */
253 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
254 if (msblk->bytes_used < 0 ||
255 msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
256 goto failed_mount;
257
258 /* Check block size for sanity */
259 msblk->block_size = le32_to_cpu(sblk->block_size);
260 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
261 goto insanity;
262
263 /*
264 * Check the system page size is not larger than the filesystem
265 * block size (by default 128K). This is currently not supported.
266 */
267 if (PAGE_SIZE > msblk->block_size) {
268 errorf(fc, "Page size > filesystem block size (%d). This is "
269 "currently not supported!", msblk->block_size);
270 goto failed_mount;
271 }
272
273 /* Check block log for sanity */
274 msblk->block_log = le16_to_cpu(sblk->block_log);
275 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
276 goto failed_mount;
277
278 /* Check that block_size and block_log match */
279 if (msblk->block_size != (1 << msblk->block_log))
280 goto insanity;
281
282 /* Check the root inode for sanity */
283 root_inode = le64_to_cpu(sblk->root_inode);
284 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
285 goto insanity;
286
287 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
288 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
289 msblk->inodes = le32_to_cpu(sblk->inodes);
290 msblk->fragments = le32_to_cpu(sblk->fragments);
291 msblk->ids = le16_to_cpu(sblk->no_ids);
292 flags = le16_to_cpu(sblk->flags);
293
294 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
295 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
296 ? "un" : "");
297 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
298 ? "un" : "");
299 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
300 TRACE("Block size %d\n", msblk->block_size);
301 TRACE("Number of inodes %d\n", msblk->inodes);
302 TRACE("Number of fragments %d\n", msblk->fragments);
303 TRACE("Number of ids %d\n", msblk->ids);
304 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
305 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
306 TRACE("sblk->fragment_table_start %llx\n",
307 (u64) le64_to_cpu(sblk->fragment_table_start));
308 TRACE("sblk->id_table_start %llx\n",
309 (u64) le64_to_cpu(sblk->id_table_start));
310
311 sb->s_maxbytes = MAX_LFS_FILESIZE;
312 sb->s_time_min = 0;
313 sb->s_time_max = U32_MAX;
314 sb->s_flags |= SB_RDONLY;
315 sb->s_op = &squashfs_super_ops;
316
317 err = -ENOMEM;
318
319 msblk->block_cache = squashfs_cache_init("metadata",
320 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
321 if (msblk->block_cache == NULL)
322 goto failed_mount;
323
324 /* Allocate read_page block */
325 msblk->read_page = squashfs_cache_init("data",
326 msblk->max_thread_num, msblk->block_size);
327 if (msblk->read_page == NULL) {
328 errorf(fc, "Failed to allocate read_page block");
329 goto failed_mount;
330 }
331
332 msblk->stream = squashfs_decompressor_setup(sb, flags);
333 if (IS_ERR(msblk->stream)) {
334 err = PTR_ERR(msblk->stream);
335 msblk->stream = NULL;
336 goto insanity;
337 }
338
339 /* Handle xattrs */
340 sb->s_xattr = squashfs_xattr_handlers;
341 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
342 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
343 next_table = msblk->bytes_used;
344 goto allocate_id_index_table;
345 }
346
347 /* Allocate and read xattr id lookup table */
348 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
349 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
350 if (IS_ERR(msblk->xattr_id_table)) {
351 errorf(fc, "unable to read xattr id index table");
352 err = PTR_ERR(msblk->xattr_id_table);
353 msblk->xattr_id_table = NULL;
354 if (err != -ENOTSUPP)
355 goto failed_mount;
356 }
357 next_table = msblk->xattr_table;
358
359allocate_id_index_table:
360 /* Allocate and read id index table */
361 msblk->id_table = squashfs_read_id_index_table(sb,
362 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
363 if (IS_ERR(msblk->id_table)) {
364 errorf(fc, "unable to read id index table");
365 err = PTR_ERR(msblk->id_table);
366 msblk->id_table = NULL;
367 goto failed_mount;
368 }
369 next_table = le64_to_cpu(msblk->id_table[0]);
370
371 /* Handle inode lookup table */
372 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
373 if (lookup_table_start == SQUASHFS_INVALID_BLK)
374 goto handle_fragments;
375
376 /* Allocate and read inode lookup table */
377 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
378 lookup_table_start, next_table, msblk->inodes);
379 if (IS_ERR(msblk->inode_lookup_table)) {
380 errorf(fc, "unable to read inode lookup table");
381 err = PTR_ERR(msblk->inode_lookup_table);
382 msblk->inode_lookup_table = NULL;
383 goto failed_mount;
384 }
385 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
386
387 sb->s_export_op = &squashfs_export_ops;
388
389handle_fragments:
390 fragments = msblk->fragments;
391 if (fragments == 0)
392 goto check_directory_table;
393
394 msblk->fragment_cache = squashfs_cache_init("fragment",
395 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
396 if (msblk->fragment_cache == NULL) {
397 err = -ENOMEM;
398 goto failed_mount;
399 }
400
401 /* Allocate and read fragment index table */
402 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
403 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
404 if (IS_ERR(msblk->fragment_index)) {
405 errorf(fc, "unable to read fragment index table");
406 err = PTR_ERR(msblk->fragment_index);
407 msblk->fragment_index = NULL;
408 goto failed_mount;
409 }
410 next_table = le64_to_cpu(msblk->fragment_index[0]);
411
412check_directory_table:
413 /* Sanity check directory_table */
414 if (msblk->directory_table > next_table) {
415 err = -EINVAL;
416 goto insanity;
417 }
418
419 /* Sanity check inode_table */
420 if (msblk->inode_table >= msblk->directory_table) {
421 err = -EINVAL;
422 goto insanity;
423 }
424
425 /* allocate root */
426 root = new_inode(sb);
427 if (!root) {
428 err = -ENOMEM;
429 goto failed_mount;
430 }
431
432 err = squashfs_read_inode(root, root_inode);
433 if (err) {
434 make_bad_inode(root);
435 iput(root);
436 goto failed_mount;
437 }
438 insert_inode_hash(root);
439
440 sb->s_root = d_make_root(root);
441 if (sb->s_root == NULL) {
442 ERROR("Root inode create failed\n");
443 err = -ENOMEM;
444 goto failed_mount;
445 }
446
447 TRACE("Leaving squashfs_fill_super\n");
448 kfree(sblk);
449 return 0;
450
451insanity:
452 errorf(fc, "squashfs image failed sanity check");
453failed_mount:
454 squashfs_cache_delete(msblk->block_cache);
455 squashfs_cache_delete(msblk->fragment_cache);
456 squashfs_cache_delete(msblk->read_page);
457 msblk->thread_ops->destroy(msblk);
458 kfree(msblk->inode_lookup_table);
459 kfree(msblk->fragment_index);
460 kfree(msblk->id_table);
461 kfree(msblk->xattr_id_table);
462 kfree(sb->s_fs_info);
463 sb->s_fs_info = NULL;
464 kfree(sblk);
465 return err;
466}
467
468static int squashfs_get_tree(struct fs_context *fc)
469{
470 return get_tree_bdev(fc, squashfs_fill_super);
471}
472
473static int squashfs_reconfigure(struct fs_context *fc)
474{
475 struct super_block *sb = fc->root->d_sb;
476 struct squashfs_sb_info *msblk = sb->s_fs_info;
477 struct squashfs_mount_opts *opts = fc->fs_private;
478
479 sync_filesystem(fc->root->d_sb);
480 fc->sb_flags |= SB_RDONLY;
481
482 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
483
484 return 0;
485}
486
487static void squashfs_free_fs_context(struct fs_context *fc)
488{
489 kfree(fc->fs_private);
490}
491
492static const struct fs_context_operations squashfs_context_ops = {
493 .get_tree = squashfs_get_tree,
494 .free = squashfs_free_fs_context,
495 .parse_param = squashfs_parse_param,
496 .reconfigure = squashfs_reconfigure,
497};
498
499static int squashfs_show_options(struct seq_file *s, struct dentry *root)
500{
501 struct super_block *sb = root->d_sb;
502 struct squashfs_sb_info *msblk = sb->s_fs_info;
503
504 if (msblk->panic_on_errors)
505 seq_puts(s, ",errors=panic");
506 else
507 seq_puts(s, ",errors=continue");
508
509#ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
510 if (msblk->thread_ops == &squashfs_decompressor_single) {
511 seq_puts(s, ",threads=single");
512 return 0;
513 }
514 if (msblk->thread_ops == &squashfs_decompressor_percpu) {
515 seq_puts(s, ",threads=percpu");
516 return 0;
517 }
518#endif
519#ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
520 seq_printf(s, ",threads=%d", msblk->max_thread_num);
521#endif
522 return 0;
523}
524
525static int squashfs_init_fs_context(struct fs_context *fc)
526{
527 struct squashfs_mount_opts *opts;
528
529 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
530 if (!opts)
531 return -ENOMEM;
532
533#ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
534 opts->thread_ops = &squashfs_decompressor_single;
535#elif defined(CONFIG_SQUASHFS_DECOMP_MULTI)
536 opts->thread_ops = &squashfs_decompressor_multi;
537#elif defined(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU)
538 opts->thread_ops = &squashfs_decompressor_percpu;
539#else
540#error "fail: unknown squashfs decompression thread mode?"
541#endif
542 opts->thread_num = 0;
543 fc->fs_private = opts;
544 fc->ops = &squashfs_context_ops;
545 return 0;
546}
547
548static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
549{
550 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
551 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
552
553 TRACE("Entered squashfs_statfs\n");
554
555 buf->f_type = SQUASHFS_MAGIC;
556 buf->f_bsize = msblk->block_size;
557 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
558 buf->f_bfree = buf->f_bavail = 0;
559 buf->f_files = msblk->inodes;
560 buf->f_ffree = 0;
561 buf->f_namelen = SQUASHFS_NAME_LEN;
562 buf->f_fsid = u64_to_fsid(id);
563
564 return 0;
565}
566
567
568static void squashfs_put_super(struct super_block *sb)
569{
570 if (sb->s_fs_info) {
571 struct squashfs_sb_info *sbi = sb->s_fs_info;
572 squashfs_cache_delete(sbi->block_cache);
573 squashfs_cache_delete(sbi->fragment_cache);
574 squashfs_cache_delete(sbi->read_page);
575 sbi->thread_ops->destroy(sbi);
576 kfree(sbi->id_table);
577 kfree(sbi->fragment_index);
578 kfree(sbi->meta_index);
579 kfree(sbi->inode_lookup_table);
580 kfree(sbi->xattr_id_table);
581 kfree(sb->s_fs_info);
582 sb->s_fs_info = NULL;
583 }
584}
585
586static struct kmem_cache *squashfs_inode_cachep;
587
588
589static void init_once(void *foo)
590{
591 struct squashfs_inode_info *ei = foo;
592
593 inode_init_once(&ei->vfs_inode);
594}
595
596
597static int __init init_inodecache(void)
598{
599 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
600 sizeof(struct squashfs_inode_info), 0,
601 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
602 init_once);
603
604 return squashfs_inode_cachep ? 0 : -ENOMEM;
605}
606
607
608static void destroy_inodecache(void)
609{
610 /*
611 * Make sure all delayed rcu free inodes are flushed before we
612 * destroy cache.
613 */
614 rcu_barrier();
615 kmem_cache_destroy(squashfs_inode_cachep);
616}
617
618
619static int __init init_squashfs_fs(void)
620{
621 int err = init_inodecache();
622
623 if (err)
624 return err;
625
626 err = register_filesystem(&squashfs_fs_type);
627 if (err) {
628 destroy_inodecache();
629 return err;
630 }
631
632 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
633
634 return 0;
635}
636
637
638static void __exit exit_squashfs_fs(void)
639{
640 unregister_filesystem(&squashfs_fs_type);
641 destroy_inodecache();
642}
643
644
645static struct inode *squashfs_alloc_inode(struct super_block *sb)
646{
647 struct squashfs_inode_info *ei =
648 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
649
650 return ei ? &ei->vfs_inode : NULL;
651}
652
653
654static void squashfs_free_inode(struct inode *inode)
655{
656 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
657}
658
659static struct file_system_type squashfs_fs_type = {
660 .owner = THIS_MODULE,
661 .name = "squashfs",
662 .init_fs_context = squashfs_init_fs_context,
663 .parameters = squashfs_fs_parameters,
664 .kill_sb = kill_block_super,
665 .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
666};
667MODULE_ALIAS_FS("squashfs");
668
669static const struct super_operations squashfs_super_ops = {
670 .alloc_inode = squashfs_alloc_inode,
671 .free_inode = squashfs_free_inode,
672 .statfs = squashfs_statfs,
673 .put_super = squashfs_put_super,
674 .show_options = squashfs_show_options,
675};
676
677module_init(init_squashfs_fs);
678module_exit(exit_squashfs_fs);
679MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
680MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
681MODULE_LICENSE("GPL");
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/vfs.h>
22#include <linux/slab.h>
23#include <linux/mutex.h>
24#include <linux/pagemap.h>
25#include <linux/init.h>
26#include <linux/module.h>
27#include <linux/magic.h>
28#include <linux/xattr.h>
29
30#include "squashfs_fs.h"
31#include "squashfs_fs_sb.h"
32#include "squashfs_fs_i.h"
33#include "squashfs.h"
34#include "decompressor.h"
35#include "xattr.h"
36
37static struct file_system_type squashfs_fs_type;
38static const struct super_operations squashfs_super_ops;
39
40static const struct squashfs_decompressor *supported_squashfs_filesystem(
41 struct fs_context *fc,
42 short major, short minor, short id)
43{
44 const struct squashfs_decompressor *decompressor;
45
46 if (major < SQUASHFS_MAJOR) {
47 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
48 "filesystems are unsupported", major, minor);
49 return NULL;
50 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
51 errorf(fc, "Major/Minor mismatch, trying to mount newer "
52 "%d.%d filesystem", major, minor);
53 errorf(fc, "Please update your kernel");
54 return NULL;
55 }
56
57 decompressor = squashfs_lookup_decompressor(id);
58 if (!decompressor->supported) {
59 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
60 decompressor->name);
61 return NULL;
62 }
63
64 return decompressor;
65}
66
67
68static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
69{
70 struct squashfs_sb_info *msblk;
71 struct squashfs_super_block *sblk = NULL;
72 struct inode *root;
73 long long root_inode;
74 unsigned short flags;
75 unsigned int fragments;
76 u64 lookup_table_start, xattr_id_table_start, next_table;
77 int err;
78
79 TRACE("Entered squashfs_fill_superblock\n");
80
81 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
82 if (sb->s_fs_info == NULL) {
83 ERROR("Failed to allocate squashfs_sb_info\n");
84 return -ENOMEM;
85 }
86 msblk = sb->s_fs_info;
87
88 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
89 msblk->devblksize_log2 = ffz(~msblk->devblksize);
90
91 mutex_init(&msblk->meta_index_mutex);
92
93 /*
94 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
95 * are not beyond filesystem end. But as we're using
96 * squashfs_read_table here to read the superblock (including the value
97 * of bytes_used) we need to set it to an initial sensible dummy value
98 */
99 msblk->bytes_used = sizeof(*sblk);
100 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
101
102 if (IS_ERR(sblk)) {
103 errorf(fc, "unable to read squashfs_super_block");
104 err = PTR_ERR(sblk);
105 sblk = NULL;
106 goto failed_mount;
107 }
108
109 err = -EINVAL;
110
111 /* Check it is a SQUASHFS superblock */
112 sb->s_magic = le32_to_cpu(sblk->s_magic);
113 if (sb->s_magic != SQUASHFS_MAGIC) {
114 if (!(fc->sb_flags & SB_SILENT))
115 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
116 sb->s_bdev);
117 goto failed_mount;
118 }
119
120 /* Check the MAJOR & MINOR versions and lookup compression type */
121 msblk->decompressor = supported_squashfs_filesystem(
122 fc,
123 le16_to_cpu(sblk->s_major),
124 le16_to_cpu(sblk->s_minor),
125 le16_to_cpu(sblk->compression));
126 if (msblk->decompressor == NULL)
127 goto failed_mount;
128
129 /* Check the filesystem does not extend beyond the end of the
130 block device */
131 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
132 if (msblk->bytes_used < 0 || msblk->bytes_used >
133 i_size_read(sb->s_bdev->bd_inode))
134 goto failed_mount;
135
136 /* Check block size for sanity */
137 msblk->block_size = le32_to_cpu(sblk->block_size);
138 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
139 goto insanity;
140
141 /*
142 * Check the system page size is not larger than the filesystem
143 * block size (by default 128K). This is currently not supported.
144 */
145 if (PAGE_SIZE > msblk->block_size) {
146 errorf(fc, "Page size > filesystem block size (%d). This is "
147 "currently not supported!", msblk->block_size);
148 goto failed_mount;
149 }
150
151 /* Check block log for sanity */
152 msblk->block_log = le16_to_cpu(sblk->block_log);
153 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
154 goto failed_mount;
155
156 /* Check that block_size and block_log match */
157 if (msblk->block_size != (1 << msblk->block_log))
158 goto insanity;
159
160 /* Check the root inode for sanity */
161 root_inode = le64_to_cpu(sblk->root_inode);
162 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
163 goto insanity;
164
165 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
166 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
167 msblk->inodes = le32_to_cpu(sblk->inodes);
168 msblk->fragments = le32_to_cpu(sblk->fragments);
169 flags = le16_to_cpu(sblk->flags);
170
171 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
172 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
173 ? "un" : "");
174 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
175 ? "un" : "");
176 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
177 TRACE("Block size %d\n", msblk->block_size);
178 TRACE("Number of inodes %d\n", msblk->inodes);
179 TRACE("Number of fragments %d\n", msblk->fragments);
180 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
181 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
182 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
183 TRACE("sblk->fragment_table_start %llx\n",
184 (u64) le64_to_cpu(sblk->fragment_table_start));
185 TRACE("sblk->id_table_start %llx\n",
186 (u64) le64_to_cpu(sblk->id_table_start));
187
188 sb->s_maxbytes = MAX_LFS_FILESIZE;
189 sb->s_time_min = 0;
190 sb->s_time_max = U32_MAX;
191 sb->s_flags |= SB_RDONLY;
192 sb->s_op = &squashfs_super_ops;
193
194 err = -ENOMEM;
195
196 msblk->block_cache = squashfs_cache_init("metadata",
197 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
198 if (msblk->block_cache == NULL)
199 goto failed_mount;
200
201 /* Allocate read_page block */
202 msblk->read_page = squashfs_cache_init("data",
203 squashfs_max_decompressors(), msblk->block_size);
204 if (msblk->read_page == NULL) {
205 errorf(fc, "Failed to allocate read_page block");
206 goto failed_mount;
207 }
208
209 msblk->stream = squashfs_decompressor_setup(sb, flags);
210 if (IS_ERR(msblk->stream)) {
211 err = PTR_ERR(msblk->stream);
212 msblk->stream = NULL;
213 goto insanity;
214 }
215
216 /* Handle xattrs */
217 sb->s_xattr = squashfs_xattr_handlers;
218 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
219 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
220 next_table = msblk->bytes_used;
221 goto allocate_id_index_table;
222 }
223
224 /* Allocate and read xattr id lookup table */
225 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
226 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
227 if (IS_ERR(msblk->xattr_id_table)) {
228 errorf(fc, "unable to read xattr id index table");
229 err = PTR_ERR(msblk->xattr_id_table);
230 msblk->xattr_id_table = NULL;
231 if (err != -ENOTSUPP)
232 goto failed_mount;
233 }
234 next_table = msblk->xattr_table;
235
236allocate_id_index_table:
237 /* Allocate and read id index table */
238 msblk->id_table = squashfs_read_id_index_table(sb,
239 le64_to_cpu(sblk->id_table_start), next_table,
240 le16_to_cpu(sblk->no_ids));
241 if (IS_ERR(msblk->id_table)) {
242 errorf(fc, "unable to read id index table");
243 err = PTR_ERR(msblk->id_table);
244 msblk->id_table = NULL;
245 goto failed_mount;
246 }
247 next_table = le64_to_cpu(msblk->id_table[0]);
248
249 /* Handle inode lookup table */
250 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
251 if (lookup_table_start == SQUASHFS_INVALID_BLK)
252 goto handle_fragments;
253
254 /* Allocate and read inode lookup table */
255 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
256 lookup_table_start, next_table, msblk->inodes);
257 if (IS_ERR(msblk->inode_lookup_table)) {
258 errorf(fc, "unable to read inode lookup table");
259 err = PTR_ERR(msblk->inode_lookup_table);
260 msblk->inode_lookup_table = NULL;
261 goto failed_mount;
262 }
263 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
264
265 sb->s_export_op = &squashfs_export_ops;
266
267handle_fragments:
268 fragments = msblk->fragments;
269 if (fragments == 0)
270 goto check_directory_table;
271
272 msblk->fragment_cache = squashfs_cache_init("fragment",
273 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
274 if (msblk->fragment_cache == NULL) {
275 err = -ENOMEM;
276 goto failed_mount;
277 }
278
279 /* Allocate and read fragment index table */
280 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
281 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
282 if (IS_ERR(msblk->fragment_index)) {
283 errorf(fc, "unable to read fragment index table");
284 err = PTR_ERR(msblk->fragment_index);
285 msblk->fragment_index = NULL;
286 goto failed_mount;
287 }
288 next_table = le64_to_cpu(msblk->fragment_index[0]);
289
290check_directory_table:
291 /* Sanity check directory_table */
292 if (msblk->directory_table > next_table) {
293 err = -EINVAL;
294 goto insanity;
295 }
296
297 /* Sanity check inode_table */
298 if (msblk->inode_table >= msblk->directory_table) {
299 err = -EINVAL;
300 goto insanity;
301 }
302
303 /* allocate root */
304 root = new_inode(sb);
305 if (!root) {
306 err = -ENOMEM;
307 goto failed_mount;
308 }
309
310 err = squashfs_read_inode(root, root_inode);
311 if (err) {
312 make_bad_inode(root);
313 iput(root);
314 goto failed_mount;
315 }
316 insert_inode_hash(root);
317
318 sb->s_root = d_make_root(root);
319 if (sb->s_root == NULL) {
320 ERROR("Root inode create failed\n");
321 err = -ENOMEM;
322 goto failed_mount;
323 }
324
325 TRACE("Leaving squashfs_fill_super\n");
326 kfree(sblk);
327 return 0;
328
329insanity:
330 errorf(fc, "squashfs image failed sanity check");
331failed_mount:
332 squashfs_cache_delete(msblk->block_cache);
333 squashfs_cache_delete(msblk->fragment_cache);
334 squashfs_cache_delete(msblk->read_page);
335 squashfs_decompressor_destroy(msblk);
336 kfree(msblk->inode_lookup_table);
337 kfree(msblk->fragment_index);
338 kfree(msblk->id_table);
339 kfree(msblk->xattr_id_table);
340 kfree(sb->s_fs_info);
341 sb->s_fs_info = NULL;
342 kfree(sblk);
343 return err;
344}
345
346static int squashfs_get_tree(struct fs_context *fc)
347{
348 return get_tree_bdev(fc, squashfs_fill_super);
349}
350
351static int squashfs_reconfigure(struct fs_context *fc)
352{
353 sync_filesystem(fc->root->d_sb);
354 fc->sb_flags |= SB_RDONLY;
355 return 0;
356}
357
358static const struct fs_context_operations squashfs_context_ops = {
359 .get_tree = squashfs_get_tree,
360 .reconfigure = squashfs_reconfigure,
361};
362
363static int squashfs_init_fs_context(struct fs_context *fc)
364{
365 fc->ops = &squashfs_context_ops;
366 return 0;
367}
368
369static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
370{
371 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
372 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
373
374 TRACE("Entered squashfs_statfs\n");
375
376 buf->f_type = SQUASHFS_MAGIC;
377 buf->f_bsize = msblk->block_size;
378 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
379 buf->f_bfree = buf->f_bavail = 0;
380 buf->f_files = msblk->inodes;
381 buf->f_ffree = 0;
382 buf->f_namelen = SQUASHFS_NAME_LEN;
383 buf->f_fsid.val[0] = (u32)id;
384 buf->f_fsid.val[1] = (u32)(id >> 32);
385
386 return 0;
387}
388
389
390static void squashfs_put_super(struct super_block *sb)
391{
392 if (sb->s_fs_info) {
393 struct squashfs_sb_info *sbi = sb->s_fs_info;
394 squashfs_cache_delete(sbi->block_cache);
395 squashfs_cache_delete(sbi->fragment_cache);
396 squashfs_cache_delete(sbi->read_page);
397 squashfs_decompressor_destroy(sbi);
398 kfree(sbi->id_table);
399 kfree(sbi->fragment_index);
400 kfree(sbi->meta_index);
401 kfree(sbi->inode_lookup_table);
402 kfree(sbi->xattr_id_table);
403 kfree(sb->s_fs_info);
404 sb->s_fs_info = NULL;
405 }
406}
407
408static struct kmem_cache *squashfs_inode_cachep;
409
410
411static void init_once(void *foo)
412{
413 struct squashfs_inode_info *ei = foo;
414
415 inode_init_once(&ei->vfs_inode);
416}
417
418
419static int __init init_inodecache(void)
420{
421 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
422 sizeof(struct squashfs_inode_info), 0,
423 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
424 init_once);
425
426 return squashfs_inode_cachep ? 0 : -ENOMEM;
427}
428
429
430static void destroy_inodecache(void)
431{
432 /*
433 * Make sure all delayed rcu free inodes are flushed before we
434 * destroy cache.
435 */
436 rcu_barrier();
437 kmem_cache_destroy(squashfs_inode_cachep);
438}
439
440
441static int __init init_squashfs_fs(void)
442{
443 int err = init_inodecache();
444
445 if (err)
446 return err;
447
448 err = register_filesystem(&squashfs_fs_type);
449 if (err) {
450 destroy_inodecache();
451 return err;
452 }
453
454 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
455
456 return 0;
457}
458
459
460static void __exit exit_squashfs_fs(void)
461{
462 unregister_filesystem(&squashfs_fs_type);
463 destroy_inodecache();
464}
465
466
467static struct inode *squashfs_alloc_inode(struct super_block *sb)
468{
469 struct squashfs_inode_info *ei =
470 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
471
472 return ei ? &ei->vfs_inode : NULL;
473}
474
475
476static void squashfs_free_inode(struct inode *inode)
477{
478 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
479}
480
481static struct file_system_type squashfs_fs_type = {
482 .owner = THIS_MODULE,
483 .name = "squashfs",
484 .init_fs_context = squashfs_init_fs_context,
485 .kill_sb = kill_block_super,
486 .fs_flags = FS_REQUIRES_DEV
487};
488MODULE_ALIAS_FS("squashfs");
489
490static const struct super_operations squashfs_super_ops = {
491 .alloc_inode = squashfs_alloc_inode,
492 .free_inode = squashfs_free_inode,
493 .statfs = squashfs_statfs,
494 .put_super = squashfs_put_super,
495};
496
497module_init(init_squashfs_fs);
498module_exit(exit_squashfs_fs);
499MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
500MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
501MODULE_LICENSE("GPL");