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
37 static struct file_system_type squashfs_fs_type;
38 static const struct super_operations squashfs_super_ops;
39
supported_squashfs_filesystem(struct fs_context * fc,short major,short minor,short id)40 static 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
squashfs_fill_super(struct super_block * sb,struct fs_context * fc)68 static 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 msblk->ids = le16_to_cpu(sblk->no_ids);
170 flags = le16_to_cpu(sblk->flags);
171
172 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
173 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
174 ? "un" : "");
175 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
176 ? "un" : "");
177 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
178 TRACE("Block size %d\n", msblk->block_size);
179 TRACE("Number of inodes %d\n", msblk->inodes);
180 TRACE("Number of fragments %d\n", msblk->fragments);
181 TRACE("Number of ids %d\n", msblk->ids);
182 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
183 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
184 TRACE("sblk->fragment_table_start %llx\n",
185 (u64) le64_to_cpu(sblk->fragment_table_start));
186 TRACE("sblk->id_table_start %llx\n",
187 (u64) le64_to_cpu(sblk->id_table_start));
188
189 sb->s_maxbytes = MAX_LFS_FILESIZE;
190 sb->s_time_min = 0;
191 sb->s_time_max = U32_MAX;
192 sb->s_flags |= SB_RDONLY;
193 sb->s_op = &squashfs_super_ops;
194
195 err = -ENOMEM;
196
197 msblk->block_cache = squashfs_cache_init("metadata",
198 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
199 if (msblk->block_cache == NULL)
200 goto failed_mount;
201
202 /* Allocate read_page block */
203 msblk->read_page = squashfs_cache_init("data",
204 squashfs_max_decompressors(), msblk->block_size);
205 if (msblk->read_page == NULL) {
206 errorf(fc, "Failed to allocate read_page block");
207 goto failed_mount;
208 }
209
210 msblk->stream = squashfs_decompressor_setup(sb, flags);
211 if (IS_ERR(msblk->stream)) {
212 err = PTR_ERR(msblk->stream);
213 msblk->stream = NULL;
214 goto insanity;
215 }
216
217 /* Handle xattrs */
218 sb->s_xattr = squashfs_xattr_handlers;
219 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
220 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
221 next_table = msblk->bytes_used;
222 goto allocate_id_index_table;
223 }
224
225 /* Allocate and read xattr id lookup table */
226 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
227 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
228 if (IS_ERR(msblk->xattr_id_table)) {
229 errorf(fc, "unable to read xattr id index table");
230 err = PTR_ERR(msblk->xattr_id_table);
231 msblk->xattr_id_table = NULL;
232 if (err != -ENOTSUPP)
233 goto failed_mount;
234 }
235 next_table = msblk->xattr_table;
236
237 allocate_id_index_table:
238 /* Allocate and read id index table */
239 msblk->id_table = squashfs_read_id_index_table(sb,
240 le64_to_cpu(sblk->id_table_start), next_table, msblk->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
267 handle_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
290 check_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
329 insanity:
330 errorf(fc, "squashfs image failed sanity check");
331 failed_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
squashfs_get_tree(struct fs_context * fc)346 static int squashfs_get_tree(struct fs_context *fc)
347 {
348 return get_tree_bdev(fc, squashfs_fill_super);
349 }
350
squashfs_reconfigure(struct fs_context * fc)351 static 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
358 static const struct fs_context_operations squashfs_context_ops = {
359 .get_tree = squashfs_get_tree,
360 .reconfigure = squashfs_reconfigure,
361 };
362
squashfs_init_fs_context(struct fs_context * fc)363 static int squashfs_init_fs_context(struct fs_context *fc)
364 {
365 fc->ops = &squashfs_context_ops;
366 return 0;
367 }
368
squashfs_statfs(struct dentry * dentry,struct kstatfs * buf)369 static 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
squashfs_put_super(struct super_block * sb)390 static 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
408 static struct kmem_cache *squashfs_inode_cachep;
409
410
init_once(void * foo)411 static void init_once(void *foo)
412 {
413 struct squashfs_inode_info *ei = foo;
414
415 inode_init_once(&ei->vfs_inode);
416 }
417
418
init_inodecache(void)419 static 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
destroy_inodecache(void)430 static 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
init_squashfs_fs(void)441 static 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
exit_squashfs_fs(void)460 static void __exit exit_squashfs_fs(void)
461 {
462 unregister_filesystem(&squashfs_fs_type);
463 destroy_inodecache();
464 }
465
466
squashfs_alloc_inode(struct super_block * sb)467 static 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
squashfs_free_inode(struct inode * inode)476 static void squashfs_free_inode(struct inode *inode)
477 {
478 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
479 }
480
481 static 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 };
488 MODULE_ALIAS_FS("squashfs");
489
490 static 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
497 module_init(init_squashfs_fs);
498 module_exit(exit_squashfs_fs);
499 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
500 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
501 MODULE_LICENSE("GPL");
502