Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * fs/libfs.c
4 : * Library for filesystems writers.
5 : */
6 :
7 : #include <linux/blkdev.h>
8 : #include <linux/export.h>
9 : #include <linux/pagemap.h>
10 : #include <linux/slab.h>
11 : #include <linux/cred.h>
12 : #include <linux/mount.h>
13 : #include <linux/vfs.h>
14 : #include <linux/quotaops.h>
15 : #include <linux/mutex.h>
16 : #include <linux/namei.h>
17 : #include <linux/exportfs.h>
18 : #include <linux/writeback.h>
19 : #include <linux/buffer_head.h> /* sync_mapping_buffers */
20 : #include <linux/fs_context.h>
21 : #include <linux/pseudo_fs.h>
22 : #include <linux/fsnotify.h>
23 : #include <linux/unicode.h>
24 : #include <linux/fscrypt.h>
25 :
26 : #include <linux/uaccess.h>
27 :
28 : #include "internal.h"
29 :
30 0 : int simple_getattr(struct user_namespace *mnt_userns, const struct path *path,
31 : struct kstat *stat, u32 request_mask,
32 : unsigned int query_flags)
33 : {
34 0 : struct inode *inode = d_inode(path->dentry);
35 0 : generic_fillattr(&init_user_ns, inode, stat);
36 0 : stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
37 0 : return 0;
38 : }
39 : EXPORT_SYMBOL(simple_getattr);
40 :
41 0 : int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
42 : {
43 0 : buf->f_type = dentry->d_sb->s_magic;
44 0 : buf->f_bsize = PAGE_SIZE;
45 0 : buf->f_namelen = NAME_MAX;
46 0 : return 0;
47 : }
48 : EXPORT_SYMBOL(simple_statfs);
49 :
50 : /*
51 : * Retaining negative dentries for an in-memory filesystem just wastes
52 : * memory and lookup time: arrange for them to be deleted immediately.
53 : */
54 0 : int always_delete_dentry(const struct dentry *dentry)
55 : {
56 0 : return 1;
57 : }
58 : EXPORT_SYMBOL(always_delete_dentry);
59 :
60 : const struct dentry_operations simple_dentry_operations = {
61 : .d_delete = always_delete_dentry,
62 : };
63 : EXPORT_SYMBOL(simple_dentry_operations);
64 :
65 : /*
66 : * Lookup the data. This is trivial - if the dentry didn't already
67 : * exist, we know it is negative. Set d_op to delete negative dentries.
68 : */
69 3 : struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
70 : {
71 3 : if (dentry->d_name.len > NAME_MAX)
72 : return ERR_PTR(-ENAMETOOLONG);
73 3 : if (!dentry->d_sb->s_d_op)
74 3 : d_set_d_op(dentry, &simple_dentry_operations);
75 3 : d_add(dentry, NULL);
76 3 : return NULL;
77 : }
78 : EXPORT_SYMBOL(simple_lookup);
79 :
80 0 : int dcache_dir_open(struct inode *inode, struct file *file)
81 : {
82 0 : file->private_data = d_alloc_cursor(file->f_path.dentry);
83 :
84 0 : return file->private_data ? 0 : -ENOMEM;
85 : }
86 : EXPORT_SYMBOL(dcache_dir_open);
87 :
88 0 : int dcache_dir_close(struct inode *inode, struct file *file)
89 : {
90 0 : dput(file->private_data);
91 0 : return 0;
92 : }
93 : EXPORT_SYMBOL(dcache_dir_close);
94 :
95 : /* parent is locked at least shared */
96 : /*
97 : * Returns an element of siblings' list.
98 : * We are looking for <count>th positive after <p>; if
99 : * found, dentry is grabbed and returned to caller.
100 : * If no such element exists, NULL is returned.
101 : */
102 0 : static struct dentry *scan_positives(struct dentry *cursor,
103 : struct list_head *p,
104 : loff_t count,
105 : struct dentry *last)
106 : {
107 0 : struct dentry *dentry = cursor->d_parent, *found = NULL;
108 :
109 0 : spin_lock(&dentry->d_lock);
110 0 : while ((p = p->next) != &dentry->d_subdirs) {
111 0 : struct dentry *d = list_entry(p, struct dentry, d_child);
112 : // we must at least skip cursors, to avoid livelocks
113 0 : if (d->d_flags & DCACHE_DENTRY_CURSOR)
114 0 : continue;
115 0 : if (simple_positive(d) && !--count) {
116 0 : spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
117 0 : if (simple_positive(d))
118 : found = dget_dlock(d);
119 0 : spin_unlock(&d->d_lock);
120 0 : if (likely(found))
121 : break;
122 : count = 1;
123 : }
124 0 : if (need_resched()) {
125 0 : list_move(&cursor->d_child, p);
126 0 : p = &cursor->d_child;
127 0 : spin_unlock(&dentry->d_lock);
128 0 : cond_resched();
129 0 : spin_lock(&dentry->d_lock);
130 : }
131 : }
132 0 : spin_unlock(&dentry->d_lock);
133 0 : dput(last);
134 0 : return found;
135 : }
136 :
137 0 : loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
138 : {
139 0 : struct dentry *dentry = file->f_path.dentry;
140 0 : switch (whence) {
141 : case 1:
142 0 : offset += file->f_pos;
143 : fallthrough;
144 : case 0:
145 0 : if (offset >= 0)
146 : break;
147 : fallthrough;
148 : default:
149 : return -EINVAL;
150 : }
151 0 : if (offset != file->f_pos) {
152 0 : struct dentry *cursor = file->private_data;
153 0 : struct dentry *to = NULL;
154 :
155 0 : inode_lock_shared(dentry->d_inode);
156 :
157 0 : if (offset > 2)
158 0 : to = scan_positives(cursor, &dentry->d_subdirs,
159 : offset - 2, NULL);
160 0 : spin_lock(&dentry->d_lock);
161 0 : if (to)
162 0 : list_move(&cursor->d_child, &to->d_child);
163 : else
164 0 : list_del_init(&cursor->d_child);
165 0 : spin_unlock(&dentry->d_lock);
166 0 : dput(to);
167 :
168 0 : file->f_pos = offset;
169 :
170 0 : inode_unlock_shared(dentry->d_inode);
171 : }
172 : return offset;
173 : }
174 : EXPORT_SYMBOL(dcache_dir_lseek);
175 :
176 : /* Relationship between i_mode and the DT_xxx types */
177 : static inline unsigned char dt_type(struct inode *inode)
178 : {
179 0 : return (inode->i_mode >> 12) & 15;
180 : }
181 :
182 : /*
183 : * Directory is locked and all positive dentries in it are safe, since
184 : * for ramfs-type trees they can't go away without unlink() or rmdir(),
185 : * both impossible due to the lock on directory.
186 : */
187 :
188 0 : int dcache_readdir(struct file *file, struct dir_context *ctx)
189 : {
190 0 : struct dentry *dentry = file->f_path.dentry;
191 0 : struct dentry *cursor = file->private_data;
192 0 : struct list_head *anchor = &dentry->d_subdirs;
193 0 : struct dentry *next = NULL;
194 : struct list_head *p;
195 :
196 0 : if (!dir_emit_dots(file, ctx))
197 : return 0;
198 :
199 0 : if (ctx->pos == 2)
200 : p = anchor;
201 0 : else if (!list_empty(&cursor->d_child))
202 : p = &cursor->d_child;
203 : else
204 : return 0;
205 :
206 0 : while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
207 0 : if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
208 0 : d_inode(next)->i_ino, dt_type(d_inode(next))))
209 : break;
210 0 : ctx->pos++;
211 0 : p = &next->d_child;
212 : }
213 0 : spin_lock(&dentry->d_lock);
214 0 : if (next)
215 0 : list_move_tail(&cursor->d_child, &next->d_child);
216 : else
217 0 : list_del_init(&cursor->d_child);
218 0 : spin_unlock(&dentry->d_lock);
219 0 : dput(next);
220 :
221 0 : return 0;
222 : }
223 : EXPORT_SYMBOL(dcache_readdir);
224 :
225 0 : ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
226 : {
227 0 : return -EISDIR;
228 : }
229 : EXPORT_SYMBOL(generic_read_dir);
230 :
231 : const struct file_operations simple_dir_operations = {
232 : .open = dcache_dir_open,
233 : .release = dcache_dir_close,
234 : .llseek = dcache_dir_lseek,
235 : .read = generic_read_dir,
236 : .iterate_shared = dcache_readdir,
237 : .fsync = noop_fsync,
238 : };
239 : EXPORT_SYMBOL(simple_dir_operations);
240 :
241 : const struct inode_operations simple_dir_inode_operations = {
242 : .lookup = simple_lookup,
243 : };
244 : EXPORT_SYMBOL(simple_dir_inode_operations);
245 :
246 0 : static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
247 : {
248 0 : struct dentry *child = NULL;
249 0 : struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
250 :
251 0 : spin_lock(&parent->d_lock);
252 0 : while ((p = p->next) != &parent->d_subdirs) {
253 0 : struct dentry *d = container_of(p, struct dentry, d_child);
254 0 : if (simple_positive(d)) {
255 0 : spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
256 0 : if (simple_positive(d))
257 : child = dget_dlock(d);
258 0 : spin_unlock(&d->d_lock);
259 0 : if (likely(child))
260 : break;
261 : }
262 : }
263 0 : spin_unlock(&parent->d_lock);
264 0 : dput(prev);
265 0 : return child;
266 : }
267 :
268 0 : void simple_recursive_removal(struct dentry *dentry,
269 : void (*callback)(struct dentry *))
270 : {
271 : struct dentry *this = dget(dentry);
272 0 : while (true) {
273 0 : struct dentry *victim = NULL, *child;
274 0 : struct inode *inode = this->d_inode;
275 :
276 0 : inode_lock(inode);
277 0 : if (d_is_dir(this))
278 0 : inode->i_flags |= S_DEAD;
279 0 : while ((child = find_next_child(this, victim)) == NULL) {
280 : // kill and ascend
281 : // update metadata while it's still locked
282 0 : inode->i_ctime = current_time(inode);
283 0 : clear_nlink(inode);
284 0 : inode_unlock(inode);
285 0 : victim = this;
286 0 : this = this->d_parent;
287 0 : inode = this->d_inode;
288 0 : inode_lock(inode);
289 0 : if (simple_positive(victim)) {
290 0 : d_invalidate(victim); // avoid lost mounts
291 0 : if (d_is_dir(victim))
292 0 : fsnotify_rmdir(inode, victim);
293 : else
294 0 : fsnotify_unlink(inode, victim);
295 0 : if (callback)
296 0 : callback(victim);
297 0 : dput(victim); // unpin it
298 : }
299 0 : if (victim == dentry) {
300 0 : inode->i_ctime = inode->i_mtime =
301 : current_time(inode);
302 0 : if (d_is_dir(dentry))
303 0 : drop_nlink(inode);
304 0 : inode_unlock(inode);
305 0 : dput(dentry);
306 0 : return;
307 : }
308 : }
309 0 : inode_unlock(inode);
310 0 : this = child;
311 : }
312 : }
313 : EXPORT_SYMBOL(simple_recursive_removal);
314 :
315 : static const struct super_operations simple_super_operations = {
316 : .statfs = simple_statfs,
317 : };
318 :
319 7 : static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
320 : {
321 7 : struct pseudo_fs_context *ctx = fc->fs_private;
322 : struct inode *root;
323 :
324 7 : s->s_maxbytes = MAX_LFS_FILESIZE;
325 7 : s->s_blocksize = PAGE_SIZE;
326 7 : s->s_blocksize_bits = PAGE_SHIFT;
327 7 : s->s_magic = ctx->magic;
328 7 : s->s_op = ctx->ops ?: &simple_super_operations;
329 7 : s->s_xattr = ctx->xattr;
330 7 : s->s_time_gran = 1;
331 7 : root = new_inode(s);
332 7 : if (!root)
333 : return -ENOMEM;
334 :
335 : /*
336 : * since this is the first inode, make it number 1. New inodes created
337 : * after this must take care not to collide with it (by passing
338 : * max_reserved of 1 to iunique).
339 : */
340 7 : root->i_ino = 1;
341 7 : root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
342 7 : root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
343 7 : s->s_root = d_make_root(root);
344 7 : if (!s->s_root)
345 : return -ENOMEM;
346 7 : s->s_d_op = ctx->dops;
347 7 : return 0;
348 : }
349 :
350 7 : static int pseudo_fs_get_tree(struct fs_context *fc)
351 : {
352 7 : return get_tree_nodev(fc, pseudo_fs_fill_super);
353 : }
354 :
355 7 : static void pseudo_fs_free(struct fs_context *fc)
356 : {
357 7 : kfree(fc->fs_private);
358 7 : }
359 :
360 : static const struct fs_context_operations pseudo_fs_context_ops = {
361 : .free = pseudo_fs_free,
362 : .get_tree = pseudo_fs_get_tree,
363 : };
364 :
365 : /*
366 : * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
367 : * will never be mountable)
368 : */
369 7 : struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
370 : unsigned long magic)
371 : {
372 : struct pseudo_fs_context *ctx;
373 :
374 7 : ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
375 7 : if (likely(ctx)) {
376 7 : ctx->magic = magic;
377 7 : fc->fs_private = ctx;
378 7 : fc->ops = &pseudo_fs_context_ops;
379 7 : fc->sb_flags |= SB_NOUSER;
380 7 : fc->global = true;
381 : }
382 7 : return ctx;
383 : }
384 : EXPORT_SYMBOL(init_pseudo);
385 :
386 0 : int simple_open(struct inode *inode, struct file *file)
387 : {
388 0 : if (inode->i_private)
389 0 : file->private_data = inode->i_private;
390 0 : return 0;
391 : }
392 : EXPORT_SYMBOL(simple_open);
393 :
394 0 : int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
395 : {
396 0 : struct inode *inode = d_inode(old_dentry);
397 :
398 0 : inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
399 0 : inc_nlink(inode);
400 0 : ihold(inode);
401 0 : dget(dentry);
402 0 : d_instantiate(dentry, inode);
403 0 : return 0;
404 : }
405 : EXPORT_SYMBOL(simple_link);
406 :
407 0 : int simple_empty(struct dentry *dentry)
408 : {
409 : struct dentry *child;
410 0 : int ret = 0;
411 :
412 0 : spin_lock(&dentry->d_lock);
413 0 : list_for_each_entry(child, &dentry->d_subdirs, d_child) {
414 0 : spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
415 0 : if (simple_positive(child)) {
416 0 : spin_unlock(&child->d_lock);
417 : goto out;
418 : }
419 0 : spin_unlock(&child->d_lock);
420 : }
421 : ret = 1;
422 : out:
423 0 : spin_unlock(&dentry->d_lock);
424 0 : return ret;
425 : }
426 : EXPORT_SYMBOL(simple_empty);
427 :
428 0 : int simple_unlink(struct inode *dir, struct dentry *dentry)
429 : {
430 0 : struct inode *inode = d_inode(dentry);
431 :
432 0 : inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
433 0 : drop_nlink(inode);
434 0 : dput(dentry);
435 0 : return 0;
436 : }
437 : EXPORT_SYMBOL(simple_unlink);
438 :
439 0 : int simple_rmdir(struct inode *dir, struct dentry *dentry)
440 : {
441 0 : if (!simple_empty(dentry))
442 : return -ENOTEMPTY;
443 :
444 0 : drop_nlink(d_inode(dentry));
445 0 : simple_unlink(dir, dentry);
446 0 : drop_nlink(dir);
447 0 : return 0;
448 : }
449 : EXPORT_SYMBOL(simple_rmdir);
450 :
451 0 : int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
452 : struct inode *new_dir, struct dentry *new_dentry)
453 : {
454 0 : bool old_is_dir = d_is_dir(old_dentry);
455 0 : bool new_is_dir = d_is_dir(new_dentry);
456 :
457 0 : if (old_dir != new_dir && old_is_dir != new_is_dir) {
458 0 : if (old_is_dir) {
459 0 : drop_nlink(old_dir);
460 0 : inc_nlink(new_dir);
461 : } else {
462 0 : drop_nlink(new_dir);
463 0 : inc_nlink(old_dir);
464 : }
465 : }
466 0 : old_dir->i_ctime = old_dir->i_mtime =
467 0 : new_dir->i_ctime = new_dir->i_mtime =
468 0 : d_inode(old_dentry)->i_ctime =
469 0 : d_inode(new_dentry)->i_ctime = current_time(old_dir);
470 :
471 0 : return 0;
472 : }
473 : EXPORT_SYMBOL_GPL(simple_rename_exchange);
474 :
475 0 : int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
476 : struct dentry *old_dentry, struct inode *new_dir,
477 : struct dentry *new_dentry, unsigned int flags)
478 : {
479 0 : struct inode *inode = d_inode(old_dentry);
480 0 : int they_are_dirs = d_is_dir(old_dentry);
481 :
482 0 : if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
483 : return -EINVAL;
484 :
485 0 : if (flags & RENAME_EXCHANGE)
486 0 : return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
487 :
488 0 : if (!simple_empty(new_dentry))
489 : return -ENOTEMPTY;
490 :
491 0 : if (d_really_is_positive(new_dentry)) {
492 0 : simple_unlink(new_dir, new_dentry);
493 0 : if (they_are_dirs) {
494 0 : drop_nlink(d_inode(new_dentry));
495 0 : drop_nlink(old_dir);
496 : }
497 0 : } else if (they_are_dirs) {
498 0 : drop_nlink(old_dir);
499 0 : inc_nlink(new_dir);
500 : }
501 :
502 0 : old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
503 0 : new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
504 :
505 0 : return 0;
506 : }
507 : EXPORT_SYMBOL(simple_rename);
508 :
509 : /**
510 : * simple_setattr - setattr for simple filesystem
511 : * @mnt_userns: user namespace of the target mount
512 : * @dentry: dentry
513 : * @iattr: iattr structure
514 : *
515 : * Returns 0 on success, -error on failure.
516 : *
517 : * simple_setattr is a simple ->setattr implementation without a proper
518 : * implementation of size changes.
519 : *
520 : * It can either be used for in-memory filesystems or special files
521 : * on simple regular filesystems. Anything that needs to change on-disk
522 : * or wire state on size changes needs its own setattr method.
523 : */
524 0 : int simple_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
525 : struct iattr *iattr)
526 : {
527 0 : struct inode *inode = d_inode(dentry);
528 : int error;
529 :
530 0 : error = setattr_prepare(mnt_userns, dentry, iattr);
531 0 : if (error)
532 : return error;
533 :
534 0 : if (iattr->ia_valid & ATTR_SIZE)
535 0 : truncate_setsize(inode, iattr->ia_size);
536 0 : setattr_copy(mnt_userns, inode, iattr);
537 0 : mark_inode_dirty(inode);
538 0 : return 0;
539 : }
540 : EXPORT_SYMBOL(simple_setattr);
541 :
542 0 : static int simple_readpage(struct file *file, struct page *page)
543 : {
544 0 : clear_highpage(page);
545 0 : flush_dcache_page(page);
546 0 : SetPageUptodate(page);
547 0 : unlock_page(page);
548 0 : return 0;
549 : }
550 :
551 0 : int simple_write_begin(struct file *file, struct address_space *mapping,
552 : loff_t pos, unsigned len, unsigned flags,
553 : struct page **pagep, void **fsdata)
554 : {
555 : struct page *page;
556 : pgoff_t index;
557 :
558 0 : index = pos >> PAGE_SHIFT;
559 :
560 0 : page = grab_cache_page_write_begin(mapping, index, flags);
561 0 : if (!page)
562 : return -ENOMEM;
563 :
564 0 : *pagep = page;
565 :
566 0 : if (!PageUptodate(page) && (len != PAGE_SIZE)) {
567 0 : unsigned from = pos & (PAGE_SIZE - 1);
568 :
569 0 : zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
570 : }
571 : return 0;
572 : }
573 : EXPORT_SYMBOL(simple_write_begin);
574 :
575 : /**
576 : * simple_write_end - .write_end helper for non-block-device FSes
577 : * @file: See .write_end of address_space_operations
578 : * @mapping: "
579 : * @pos: "
580 : * @len: "
581 : * @copied: "
582 : * @page: "
583 : * @fsdata: "
584 : *
585 : * simple_write_end does the minimum needed for updating a page after writing is
586 : * done. It has the same API signature as the .write_end of
587 : * address_space_operations vector. So it can just be set onto .write_end for
588 : * FSes that don't need any other processing. i_mutex is assumed to be held.
589 : * Block based filesystems should use generic_write_end().
590 : * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
591 : * is not called, so a filesystem that actually does store data in .write_inode
592 : * should extend on what's done here with a call to mark_inode_dirty() in the
593 : * case that i_size has changed.
594 : *
595 : * Use *ONLY* with simple_readpage()
596 : */
597 0 : static int simple_write_end(struct file *file, struct address_space *mapping,
598 : loff_t pos, unsigned len, unsigned copied,
599 : struct page *page, void *fsdata)
600 : {
601 0 : struct inode *inode = page->mapping->host;
602 0 : loff_t last_pos = pos + copied;
603 :
604 : /* zero the stale part of the page if we did a short copy */
605 0 : if (!PageUptodate(page)) {
606 0 : if (copied < len) {
607 0 : unsigned from = pos & (PAGE_SIZE - 1);
608 :
609 0 : zero_user(page, from + copied, len - copied);
610 : }
611 : SetPageUptodate(page);
612 : }
613 : /*
614 : * No need to use i_size_read() here, the i_size
615 : * cannot change under us because we hold the i_mutex.
616 : */
617 0 : if (last_pos > inode->i_size)
618 0 : i_size_write(inode, last_pos);
619 :
620 0 : set_page_dirty(page);
621 0 : unlock_page(page);
622 0 : put_page(page);
623 :
624 0 : return copied;
625 : }
626 :
627 : /*
628 : * Provides ramfs-style behavior: data in the pagecache, but no writeback.
629 : */
630 : const struct address_space_operations ram_aops = {
631 : .readpage = simple_readpage,
632 : .write_begin = simple_write_begin,
633 : .write_end = simple_write_end,
634 : .dirty_folio = noop_dirty_folio,
635 : };
636 : EXPORT_SYMBOL(ram_aops);
637 :
638 : /*
639 : * the inodes created here are not hashed. If you use iunique to generate
640 : * unique inode values later for this filesystem, then you must take care
641 : * to pass it an appropriate max_reserved value to avoid collisions.
642 : */
643 0 : int simple_fill_super(struct super_block *s, unsigned long magic,
644 : const struct tree_descr *files)
645 : {
646 : struct inode *inode;
647 : struct dentry *root;
648 : struct dentry *dentry;
649 : int i;
650 :
651 0 : s->s_blocksize = PAGE_SIZE;
652 0 : s->s_blocksize_bits = PAGE_SHIFT;
653 0 : s->s_magic = magic;
654 0 : s->s_op = &simple_super_operations;
655 0 : s->s_time_gran = 1;
656 :
657 0 : inode = new_inode(s);
658 0 : if (!inode)
659 : return -ENOMEM;
660 : /*
661 : * because the root inode is 1, the files array must not contain an
662 : * entry at index 1
663 : */
664 0 : inode->i_ino = 1;
665 0 : inode->i_mode = S_IFDIR | 0755;
666 0 : inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
667 0 : inode->i_op = &simple_dir_inode_operations;
668 0 : inode->i_fop = &simple_dir_operations;
669 0 : set_nlink(inode, 2);
670 0 : root = d_make_root(inode);
671 0 : if (!root)
672 : return -ENOMEM;
673 0 : for (i = 0; !files->name || files->name[0]; i++, files++) {
674 0 : if (!files->name)
675 0 : continue;
676 :
677 : /* warn if it tries to conflict with the root inode */
678 0 : if (unlikely(i == 1))
679 0 : printk(KERN_WARNING "%s: %s passed in a files array"
680 : "with an index of 1!\n", __func__,
681 : s->s_type->name);
682 :
683 0 : dentry = d_alloc_name(root, files->name);
684 0 : if (!dentry)
685 : goto out;
686 0 : inode = new_inode(s);
687 0 : if (!inode) {
688 0 : dput(dentry);
689 0 : goto out;
690 : }
691 0 : inode->i_mode = S_IFREG | files->mode;
692 0 : inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
693 0 : inode->i_fop = files->ops;
694 0 : inode->i_ino = i;
695 0 : d_add(dentry, inode);
696 : }
697 0 : s->s_root = root;
698 0 : return 0;
699 : out:
700 0 : d_genocide(root);
701 0 : shrink_dcache_parent(root);
702 0 : dput(root);
703 0 : return -ENOMEM;
704 : }
705 : EXPORT_SYMBOL(simple_fill_super);
706 :
707 : static DEFINE_SPINLOCK(pin_fs_lock);
708 :
709 1 : int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
710 : {
711 1 : struct vfsmount *mnt = NULL;
712 1 : spin_lock(&pin_fs_lock);
713 1 : if (unlikely(!*mount)) {
714 1 : spin_unlock(&pin_fs_lock);
715 1 : mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
716 1 : if (IS_ERR(mnt))
717 0 : return PTR_ERR(mnt);
718 1 : spin_lock(&pin_fs_lock);
719 1 : if (!*mount)
720 1 : *mount = mnt;
721 : }
722 1 : mntget(*mount);
723 1 : ++*count;
724 1 : spin_unlock(&pin_fs_lock);
725 1 : mntput(mnt);
726 1 : return 0;
727 : }
728 : EXPORT_SYMBOL(simple_pin_fs);
729 :
730 0 : void simple_release_fs(struct vfsmount **mount, int *count)
731 : {
732 : struct vfsmount *mnt;
733 0 : spin_lock(&pin_fs_lock);
734 0 : mnt = *mount;
735 0 : if (!--*count)
736 0 : *mount = NULL;
737 0 : spin_unlock(&pin_fs_lock);
738 0 : mntput(mnt);
739 0 : }
740 : EXPORT_SYMBOL(simple_release_fs);
741 :
742 : /**
743 : * simple_read_from_buffer - copy data from the buffer to user space
744 : * @to: the user space buffer to read to
745 : * @count: the maximum number of bytes to read
746 : * @ppos: the current position in the buffer
747 : * @from: the buffer to read from
748 : * @available: the size of the buffer
749 : *
750 : * The simple_read_from_buffer() function reads up to @count bytes from the
751 : * buffer @from at offset @ppos into the user space address starting at @to.
752 : *
753 : * On success, the number of bytes read is returned and the offset @ppos is
754 : * advanced by this number, or negative value is returned on error.
755 : **/
756 0 : ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
757 : const void *from, size_t available)
758 : {
759 0 : loff_t pos = *ppos;
760 : size_t ret;
761 :
762 0 : if (pos < 0)
763 : return -EINVAL;
764 0 : if (pos >= available || !count)
765 : return 0;
766 0 : if (count > available - pos)
767 0 : count = available - pos;
768 0 : ret = copy_to_user(to, from + pos, count);
769 0 : if (ret == count)
770 : return -EFAULT;
771 0 : count -= ret;
772 0 : *ppos = pos + count;
773 0 : return count;
774 : }
775 : EXPORT_SYMBOL(simple_read_from_buffer);
776 :
777 : /**
778 : * simple_write_to_buffer - copy data from user space to the buffer
779 : * @to: the buffer to write to
780 : * @available: the size of the buffer
781 : * @ppos: the current position in the buffer
782 : * @from: the user space buffer to read from
783 : * @count: the maximum number of bytes to read
784 : *
785 : * The simple_write_to_buffer() function reads up to @count bytes from the user
786 : * space address starting at @from into the buffer @to at offset @ppos.
787 : *
788 : * On success, the number of bytes written is returned and the offset @ppos is
789 : * advanced by this number, or negative value is returned on error.
790 : **/
791 0 : ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
792 : const void __user *from, size_t count)
793 : {
794 0 : loff_t pos = *ppos;
795 : size_t res;
796 :
797 0 : if (pos < 0)
798 : return -EINVAL;
799 0 : if (pos >= available || !count)
800 : return 0;
801 0 : if (count > available - pos)
802 0 : count = available - pos;
803 0 : res = copy_from_user(to + pos, from, count);
804 0 : if (res == count)
805 : return -EFAULT;
806 0 : count -= res;
807 0 : *ppos = pos + count;
808 0 : return count;
809 : }
810 : EXPORT_SYMBOL(simple_write_to_buffer);
811 :
812 : /**
813 : * memory_read_from_buffer - copy data from the buffer
814 : * @to: the kernel space buffer to read to
815 : * @count: the maximum number of bytes to read
816 : * @ppos: the current position in the buffer
817 : * @from: the buffer to read from
818 : * @available: the size of the buffer
819 : *
820 : * The memory_read_from_buffer() function reads up to @count bytes from the
821 : * buffer @from at offset @ppos into the kernel space address starting at @to.
822 : *
823 : * On success, the number of bytes read is returned and the offset @ppos is
824 : * advanced by this number, or negative value is returned on error.
825 : **/
826 0 : ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
827 : const void *from, size_t available)
828 : {
829 0 : loff_t pos = *ppos;
830 :
831 0 : if (pos < 0)
832 : return -EINVAL;
833 0 : if (pos >= available)
834 : return 0;
835 0 : if (count > available - pos)
836 0 : count = available - pos;
837 0 : memcpy(to, from + pos, count);
838 0 : *ppos = pos + count;
839 :
840 0 : return count;
841 : }
842 : EXPORT_SYMBOL(memory_read_from_buffer);
843 :
844 : /*
845 : * Transaction based IO.
846 : * The file expects a single write which triggers the transaction, and then
847 : * possibly a read which collects the result - which is stored in a
848 : * file-local buffer.
849 : */
850 :
851 0 : void simple_transaction_set(struct file *file, size_t n)
852 : {
853 0 : struct simple_transaction_argresp *ar = file->private_data;
854 :
855 0 : BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
856 :
857 : /*
858 : * The barrier ensures that ar->size will really remain zero until
859 : * ar->data is ready for reading.
860 : */
861 0 : smp_mb();
862 0 : ar->size = n;
863 0 : }
864 : EXPORT_SYMBOL(simple_transaction_set);
865 :
866 0 : char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
867 : {
868 : struct simple_transaction_argresp *ar;
869 : static DEFINE_SPINLOCK(simple_transaction_lock);
870 :
871 0 : if (size > SIMPLE_TRANSACTION_LIMIT - 1)
872 : return ERR_PTR(-EFBIG);
873 :
874 0 : ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
875 0 : if (!ar)
876 : return ERR_PTR(-ENOMEM);
877 :
878 0 : spin_lock(&simple_transaction_lock);
879 :
880 : /* only one write allowed per open */
881 0 : if (file->private_data) {
882 0 : spin_unlock(&simple_transaction_lock);
883 0 : free_page((unsigned long)ar);
884 0 : return ERR_PTR(-EBUSY);
885 : }
886 :
887 0 : file->private_data = ar;
888 :
889 0 : spin_unlock(&simple_transaction_lock);
890 :
891 0 : if (copy_from_user(ar->data, buf, size))
892 : return ERR_PTR(-EFAULT);
893 :
894 0 : return ar->data;
895 : }
896 : EXPORT_SYMBOL(simple_transaction_get);
897 :
898 0 : ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
899 : {
900 0 : struct simple_transaction_argresp *ar = file->private_data;
901 :
902 0 : if (!ar)
903 : return 0;
904 0 : return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
905 : }
906 : EXPORT_SYMBOL(simple_transaction_read);
907 :
908 0 : int simple_transaction_release(struct inode *inode, struct file *file)
909 : {
910 0 : free_page((unsigned long)file->private_data);
911 0 : return 0;
912 : }
913 : EXPORT_SYMBOL(simple_transaction_release);
914 :
915 : /* Simple attribute files */
916 :
917 : struct simple_attr {
918 : int (*get)(void *, u64 *);
919 : int (*set)(void *, u64);
920 : char get_buf[24]; /* enough to store a u64 and "\n\0" */
921 : char set_buf[24];
922 : void *data;
923 : const char *fmt; /* format for read operation */
924 : struct mutex mutex; /* protects access to these buffers */
925 : };
926 :
927 : /* simple_attr_open is called by an actual attribute open file operation
928 : * to set the attribute specific access operations. */
929 0 : int simple_attr_open(struct inode *inode, struct file *file,
930 : int (*get)(void *, u64 *), int (*set)(void *, u64),
931 : const char *fmt)
932 : {
933 : struct simple_attr *attr;
934 :
935 0 : attr = kzalloc(sizeof(*attr), GFP_KERNEL);
936 0 : if (!attr)
937 : return -ENOMEM;
938 :
939 0 : attr->get = get;
940 0 : attr->set = set;
941 0 : attr->data = inode->i_private;
942 0 : attr->fmt = fmt;
943 0 : mutex_init(&attr->mutex);
944 :
945 0 : file->private_data = attr;
946 :
947 0 : return nonseekable_open(inode, file);
948 : }
949 : EXPORT_SYMBOL_GPL(simple_attr_open);
950 :
951 0 : int simple_attr_release(struct inode *inode, struct file *file)
952 : {
953 0 : kfree(file->private_data);
954 0 : return 0;
955 : }
956 : EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
957 :
958 : /* read from the buffer that is filled with the get function */
959 0 : ssize_t simple_attr_read(struct file *file, char __user *buf,
960 : size_t len, loff_t *ppos)
961 : {
962 : struct simple_attr *attr;
963 : size_t size;
964 : ssize_t ret;
965 :
966 0 : attr = file->private_data;
967 :
968 0 : if (!attr->get)
969 : return -EACCES;
970 :
971 0 : ret = mutex_lock_interruptible(&attr->mutex);
972 0 : if (ret)
973 : return ret;
974 :
975 0 : if (*ppos && attr->get_buf[0]) {
976 : /* continued read */
977 0 : size = strlen(attr->get_buf);
978 : } else {
979 : /* first read */
980 : u64 val;
981 0 : ret = attr->get(attr->data, &val);
982 0 : if (ret)
983 : goto out;
984 :
985 0 : size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
986 : attr->fmt, (unsigned long long)val);
987 : }
988 :
989 0 : ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
990 : out:
991 0 : mutex_unlock(&attr->mutex);
992 0 : return ret;
993 : }
994 : EXPORT_SYMBOL_GPL(simple_attr_read);
995 :
996 : /* interpret the buffer as a number to call the set function with */
997 0 : ssize_t simple_attr_write(struct file *file, const char __user *buf,
998 : size_t len, loff_t *ppos)
999 : {
1000 : struct simple_attr *attr;
1001 : unsigned long long val;
1002 : size_t size;
1003 : ssize_t ret;
1004 :
1005 0 : attr = file->private_data;
1006 0 : if (!attr->set)
1007 : return -EACCES;
1008 :
1009 0 : ret = mutex_lock_interruptible(&attr->mutex);
1010 0 : if (ret)
1011 : return ret;
1012 :
1013 0 : ret = -EFAULT;
1014 0 : size = min(sizeof(attr->set_buf) - 1, len);
1015 0 : if (copy_from_user(attr->set_buf, buf, size))
1016 : goto out;
1017 :
1018 0 : attr->set_buf[size] = '\0';
1019 0 : ret = kstrtoull(attr->set_buf, 0, &val);
1020 0 : if (ret)
1021 : goto out;
1022 0 : ret = attr->set(attr->data, val);
1023 0 : if (ret == 0)
1024 0 : ret = len; /* on success, claim we got the whole input */
1025 : out:
1026 0 : mutex_unlock(&attr->mutex);
1027 0 : return ret;
1028 : }
1029 : EXPORT_SYMBOL_GPL(simple_attr_write);
1030 :
1031 : /**
1032 : * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
1033 : * @sb: filesystem to do the file handle conversion on
1034 : * @fid: file handle to convert
1035 : * @fh_len: length of the file handle in bytes
1036 : * @fh_type: type of file handle
1037 : * @get_inode: filesystem callback to retrieve inode
1038 : *
1039 : * This function decodes @fid as long as it has one of the well-known
1040 : * Linux filehandle types and calls @get_inode on it to retrieve the
1041 : * inode for the object specified in the file handle.
1042 : */
1043 0 : struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
1044 : int fh_len, int fh_type, struct inode *(*get_inode)
1045 : (struct super_block *sb, u64 ino, u32 gen))
1046 : {
1047 0 : struct inode *inode = NULL;
1048 :
1049 0 : if (fh_len < 2)
1050 : return NULL;
1051 :
1052 0 : switch (fh_type) {
1053 : case FILEID_INO32_GEN:
1054 : case FILEID_INO32_GEN_PARENT:
1055 0 : inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
1056 0 : break;
1057 : }
1058 :
1059 0 : return d_obtain_alias(inode);
1060 : }
1061 : EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
1062 :
1063 : /**
1064 : * generic_fh_to_parent - generic helper for the fh_to_parent export operation
1065 : * @sb: filesystem to do the file handle conversion on
1066 : * @fid: file handle to convert
1067 : * @fh_len: length of the file handle in bytes
1068 : * @fh_type: type of file handle
1069 : * @get_inode: filesystem callback to retrieve inode
1070 : *
1071 : * This function decodes @fid as long as it has one of the well-known
1072 : * Linux filehandle types and calls @get_inode on it to retrieve the
1073 : * inode for the _parent_ object specified in the file handle if it
1074 : * is specified in the file handle, or NULL otherwise.
1075 : */
1076 0 : struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
1077 : int fh_len, int fh_type, struct inode *(*get_inode)
1078 : (struct super_block *sb, u64 ino, u32 gen))
1079 : {
1080 0 : struct inode *inode = NULL;
1081 :
1082 0 : if (fh_len <= 2)
1083 : return NULL;
1084 :
1085 0 : switch (fh_type) {
1086 : case FILEID_INO32_GEN_PARENT:
1087 0 : inode = get_inode(sb, fid->i32.parent_ino,
1088 : (fh_len > 3 ? fid->i32.parent_gen : 0));
1089 0 : break;
1090 : }
1091 :
1092 0 : return d_obtain_alias(inode);
1093 : }
1094 : EXPORT_SYMBOL_GPL(generic_fh_to_parent);
1095 :
1096 : /**
1097 : * __generic_file_fsync - generic fsync implementation for simple filesystems
1098 : *
1099 : * @file: file to synchronize
1100 : * @start: start offset in bytes
1101 : * @end: end offset in bytes (inclusive)
1102 : * @datasync: only synchronize essential metadata if true
1103 : *
1104 : * This is a generic implementation of the fsync method for simple
1105 : * filesystems which track all non-inode metadata in the buffers list
1106 : * hanging off the address_space structure.
1107 : */
1108 0 : int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
1109 : int datasync)
1110 : {
1111 0 : struct inode *inode = file->f_mapping->host;
1112 : int err;
1113 : int ret;
1114 :
1115 0 : err = file_write_and_wait_range(file, start, end);
1116 0 : if (err)
1117 : return err;
1118 :
1119 0 : inode_lock(inode);
1120 0 : ret = sync_mapping_buffers(inode->i_mapping);
1121 0 : if (!(inode->i_state & I_DIRTY_ALL))
1122 : goto out;
1123 0 : if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
1124 : goto out;
1125 :
1126 0 : err = sync_inode_metadata(inode, 1);
1127 0 : if (ret == 0)
1128 0 : ret = err;
1129 :
1130 : out:
1131 0 : inode_unlock(inode);
1132 : /* check and advance again to catch errors after syncing out buffers */
1133 0 : err = file_check_and_advance_wb_err(file);
1134 0 : if (ret == 0)
1135 0 : ret = err;
1136 : return ret;
1137 : }
1138 : EXPORT_SYMBOL(__generic_file_fsync);
1139 :
1140 : /**
1141 : * generic_file_fsync - generic fsync implementation for simple filesystems
1142 : * with flush
1143 : * @file: file to synchronize
1144 : * @start: start offset in bytes
1145 : * @end: end offset in bytes (inclusive)
1146 : * @datasync: only synchronize essential metadata if true
1147 : *
1148 : */
1149 :
1150 0 : int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1151 : int datasync)
1152 : {
1153 0 : struct inode *inode = file->f_mapping->host;
1154 : int err;
1155 :
1156 0 : err = __generic_file_fsync(file, start, end, datasync);
1157 0 : if (err)
1158 : return err;
1159 0 : return blkdev_issue_flush(inode->i_sb->s_bdev);
1160 : }
1161 : EXPORT_SYMBOL(generic_file_fsync);
1162 :
1163 : /**
1164 : * generic_check_addressable - Check addressability of file system
1165 : * @blocksize_bits: log of file system block size
1166 : * @num_blocks: number of blocks in file system
1167 : *
1168 : * Determine whether a file system with @num_blocks blocks (and a
1169 : * block size of 2**@blocksize_bits) is addressable by the sector_t
1170 : * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1171 : */
1172 0 : int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1173 : {
1174 0 : u64 last_fs_block = num_blocks - 1;
1175 0 : u64 last_fs_page =
1176 0 : last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1177 :
1178 0 : if (unlikely(num_blocks == 0))
1179 : return 0;
1180 :
1181 0 : if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1182 : return -EINVAL;
1183 :
1184 0 : if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1185 : (last_fs_page > (pgoff_t)(~0ULL))) {
1186 : return -EFBIG;
1187 : }
1188 0 : return 0;
1189 : }
1190 : EXPORT_SYMBOL(generic_check_addressable);
1191 :
1192 : /*
1193 : * No-op implementation of ->fsync for in-memory filesystems.
1194 : */
1195 0 : int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1196 : {
1197 0 : return 0;
1198 : }
1199 : EXPORT_SYMBOL(noop_fsync);
1200 :
1201 0 : ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1202 : {
1203 : /*
1204 : * iomap based filesystems support direct I/O without need for
1205 : * this callback. However, it still needs to be set in
1206 : * inode->a_ops so that open/fcntl know that direct I/O is
1207 : * generally supported.
1208 : */
1209 0 : return -EINVAL;
1210 : }
1211 : EXPORT_SYMBOL_GPL(noop_direct_IO);
1212 :
1213 : /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1214 0 : void kfree_link(void *p)
1215 : {
1216 0 : kfree(p);
1217 0 : }
1218 : EXPORT_SYMBOL(kfree_link);
1219 :
1220 2 : struct inode *alloc_anon_inode(struct super_block *s)
1221 : {
1222 : static const struct address_space_operations anon_aops = {
1223 : .dirty_folio = noop_dirty_folio,
1224 : };
1225 2 : struct inode *inode = new_inode_pseudo(s);
1226 :
1227 2 : if (!inode)
1228 : return ERR_PTR(-ENOMEM);
1229 :
1230 2 : inode->i_ino = get_next_ino();
1231 2 : inode->i_mapping->a_ops = &anon_aops;
1232 :
1233 : /*
1234 : * Mark the inode dirty from the very beginning,
1235 : * that way it will never be moved to the dirty
1236 : * list because mark_inode_dirty() will think
1237 : * that it already _is_ on the dirty list.
1238 : */
1239 2 : inode->i_state = I_DIRTY;
1240 2 : inode->i_mode = S_IRUSR | S_IWUSR;
1241 2 : inode->i_uid = current_fsuid();
1242 2 : inode->i_gid = current_fsgid();
1243 2 : inode->i_flags |= S_PRIVATE;
1244 2 : inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1245 2 : return inode;
1246 : }
1247 : EXPORT_SYMBOL(alloc_anon_inode);
1248 :
1249 : /**
1250 : * simple_nosetlease - generic helper for prohibiting leases
1251 : * @filp: file pointer
1252 : * @arg: type of lease to obtain
1253 : * @flp: new lease supplied for insertion
1254 : * @priv: private data for lm_setup operation
1255 : *
1256 : * Generic helper for filesystems that do not wish to allow leases to be set.
1257 : * All arguments are ignored and it just returns -EINVAL.
1258 : */
1259 : int
1260 0 : simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1261 : void **priv)
1262 : {
1263 0 : return -EINVAL;
1264 : }
1265 : EXPORT_SYMBOL(simple_nosetlease);
1266 :
1267 : /**
1268 : * simple_get_link - generic helper to get the target of "fast" symlinks
1269 : * @dentry: not used here
1270 : * @inode: the symlink inode
1271 : * @done: not used here
1272 : *
1273 : * Generic helper for filesystems to use for symlink inodes where a pointer to
1274 : * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
1275 : * since as an optimization the path lookup code uses any non-NULL ->i_link
1276 : * directly, without calling ->get_link(). But ->get_link() still must be set,
1277 : * to mark the inode_operations as being for a symlink.
1278 : *
1279 : * Return: the symlink target
1280 : */
1281 0 : const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1282 : struct delayed_call *done)
1283 : {
1284 0 : return inode->i_link;
1285 : }
1286 : EXPORT_SYMBOL(simple_get_link);
1287 :
1288 : const struct inode_operations simple_symlink_inode_operations = {
1289 : .get_link = simple_get_link,
1290 : };
1291 : EXPORT_SYMBOL(simple_symlink_inode_operations);
1292 :
1293 : /*
1294 : * Operations for a permanently empty directory.
1295 : */
1296 0 : static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1297 : {
1298 0 : return ERR_PTR(-ENOENT);
1299 : }
1300 :
1301 0 : static int empty_dir_getattr(struct user_namespace *mnt_userns,
1302 : const struct path *path, struct kstat *stat,
1303 : u32 request_mask, unsigned int query_flags)
1304 : {
1305 0 : struct inode *inode = d_inode(path->dentry);
1306 0 : generic_fillattr(&init_user_ns, inode, stat);
1307 0 : return 0;
1308 : }
1309 :
1310 0 : static int empty_dir_setattr(struct user_namespace *mnt_userns,
1311 : struct dentry *dentry, struct iattr *attr)
1312 : {
1313 0 : return -EPERM;
1314 : }
1315 :
1316 0 : static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1317 : {
1318 0 : return -EOPNOTSUPP;
1319 : }
1320 :
1321 : static const struct inode_operations empty_dir_inode_operations = {
1322 : .lookup = empty_dir_lookup,
1323 : .permission = generic_permission,
1324 : .setattr = empty_dir_setattr,
1325 : .getattr = empty_dir_getattr,
1326 : .listxattr = empty_dir_listxattr,
1327 : };
1328 :
1329 0 : static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1330 : {
1331 : /* An empty directory has two entries . and .. at offsets 0 and 1 */
1332 0 : return generic_file_llseek_size(file, offset, whence, 2, 2);
1333 : }
1334 :
1335 0 : static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1336 : {
1337 0 : dir_emit_dots(file, ctx);
1338 0 : return 0;
1339 : }
1340 :
1341 : static const struct file_operations empty_dir_operations = {
1342 : .llseek = empty_dir_llseek,
1343 : .read = generic_read_dir,
1344 : .iterate_shared = empty_dir_readdir,
1345 : .fsync = noop_fsync,
1346 : };
1347 :
1348 :
1349 0 : void make_empty_dir_inode(struct inode *inode)
1350 : {
1351 0 : set_nlink(inode, 2);
1352 0 : inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1353 0 : inode->i_uid = GLOBAL_ROOT_UID;
1354 0 : inode->i_gid = GLOBAL_ROOT_GID;
1355 0 : inode->i_rdev = 0;
1356 0 : inode->i_size = 0;
1357 0 : inode->i_blkbits = PAGE_SHIFT;
1358 0 : inode->i_blocks = 0;
1359 :
1360 0 : inode->i_op = &empty_dir_inode_operations;
1361 0 : inode->i_opflags &= ~IOP_XATTR;
1362 0 : inode->i_fop = &empty_dir_operations;
1363 0 : }
1364 :
1365 0 : bool is_empty_dir_inode(struct inode *inode)
1366 : {
1367 0 : return (inode->i_fop == &empty_dir_operations) &&
1368 0 : (inode->i_op == &empty_dir_inode_operations);
1369 : }
1370 :
1371 : #if IS_ENABLED(CONFIG_UNICODE)
1372 : /*
1373 : * Determine if the name of a dentry should be casefolded.
1374 : *
1375 : * Return: if names will need casefolding
1376 : */
1377 : static bool needs_casefold(const struct inode *dir)
1378 : {
1379 : return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding;
1380 : }
1381 :
1382 : /**
1383 : * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
1384 : * @dentry: dentry whose name we are checking against
1385 : * @len: len of name of dentry
1386 : * @str: str pointer to name of dentry
1387 : * @name: Name to compare against
1388 : *
1389 : * Return: 0 if names match, 1 if mismatch, or -ERRNO
1390 : */
1391 : static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
1392 : const char *str, const struct qstr *name)
1393 : {
1394 : const struct dentry *parent = READ_ONCE(dentry->d_parent);
1395 : const struct inode *dir = READ_ONCE(parent->d_inode);
1396 : const struct super_block *sb = dentry->d_sb;
1397 : const struct unicode_map *um = sb->s_encoding;
1398 : struct qstr qstr = QSTR_INIT(str, len);
1399 : char strbuf[DNAME_INLINE_LEN];
1400 : int ret;
1401 :
1402 : if (!dir || !needs_casefold(dir))
1403 : goto fallback;
1404 : /*
1405 : * If the dentry name is stored in-line, then it may be concurrently
1406 : * modified by a rename. If this happens, the VFS will eventually retry
1407 : * the lookup, so it doesn't matter what ->d_compare() returns.
1408 : * However, it's unsafe to call utf8_strncasecmp() with an unstable
1409 : * string. Therefore, we have to copy the name into a temporary buffer.
1410 : */
1411 : if (len <= DNAME_INLINE_LEN - 1) {
1412 : memcpy(strbuf, str, len);
1413 : strbuf[len] = 0;
1414 : qstr.name = strbuf;
1415 : /* prevent compiler from optimizing out the temporary buffer */
1416 : barrier();
1417 : }
1418 : ret = utf8_strncasecmp(um, name, &qstr);
1419 : if (ret >= 0)
1420 : return ret;
1421 :
1422 : if (sb_has_strict_encoding(sb))
1423 : return -EINVAL;
1424 : fallback:
1425 : if (len != name->len)
1426 : return 1;
1427 : return !!memcmp(str, name->name, len);
1428 : }
1429 :
1430 : /**
1431 : * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
1432 : * @dentry: dentry of the parent directory
1433 : * @str: qstr of name whose hash we should fill in
1434 : *
1435 : * Return: 0 if hash was successful or unchanged, and -EINVAL on error
1436 : */
1437 : static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
1438 : {
1439 : const struct inode *dir = READ_ONCE(dentry->d_inode);
1440 : struct super_block *sb = dentry->d_sb;
1441 : const struct unicode_map *um = sb->s_encoding;
1442 : int ret = 0;
1443 :
1444 : if (!dir || !needs_casefold(dir))
1445 : return 0;
1446 :
1447 : ret = utf8_casefold_hash(um, dentry, str);
1448 : if (ret < 0 && sb_has_strict_encoding(sb))
1449 : return -EINVAL;
1450 : return 0;
1451 : }
1452 :
1453 : static const struct dentry_operations generic_ci_dentry_ops = {
1454 : .d_hash = generic_ci_d_hash,
1455 : .d_compare = generic_ci_d_compare,
1456 : };
1457 : #endif
1458 :
1459 : #ifdef CONFIG_FS_ENCRYPTION
1460 : static const struct dentry_operations generic_encrypted_dentry_ops = {
1461 : .d_revalidate = fscrypt_d_revalidate,
1462 : };
1463 : #endif
1464 :
1465 : #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1466 : static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
1467 : .d_hash = generic_ci_d_hash,
1468 : .d_compare = generic_ci_d_compare,
1469 : .d_revalidate = fscrypt_d_revalidate,
1470 : };
1471 : #endif
1472 :
1473 : /**
1474 : * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
1475 : * @dentry: dentry to set ops on
1476 : *
1477 : * Casefolded directories need d_hash and d_compare set, so that the dentries
1478 : * contained in them are handled case-insensitively. Note that these operations
1479 : * are needed on the parent directory rather than on the dentries in it, and
1480 : * while the casefolding flag can be toggled on and off on an empty directory,
1481 : * dentry_operations can't be changed later. As a result, if the filesystem has
1482 : * casefolding support enabled at all, we have to give all dentries the
1483 : * casefolding operations even if their inode doesn't have the casefolding flag
1484 : * currently (and thus the casefolding ops would be no-ops for now).
1485 : *
1486 : * Encryption works differently in that the only dentry operation it needs is
1487 : * d_revalidate, which it only needs on dentries that have the no-key name flag.
1488 : * The no-key flag can't be set "later", so we don't have to worry about that.
1489 : *
1490 : * Finally, to maximize compatibility with overlayfs (which isn't compatible
1491 : * with certain dentry operations) and to avoid taking an unnecessary
1492 : * performance hit, we use custom dentry_operations for each possible
1493 : * combination rather than always installing all operations.
1494 : */
1495 0 : void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
1496 : {
1497 : #ifdef CONFIG_FS_ENCRYPTION
1498 : bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
1499 : #endif
1500 : #if IS_ENABLED(CONFIG_UNICODE)
1501 : bool needs_ci_ops = dentry->d_sb->s_encoding;
1502 : #endif
1503 : #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1504 : if (needs_encrypt_ops && needs_ci_ops) {
1505 : d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
1506 : return;
1507 : }
1508 : #endif
1509 : #ifdef CONFIG_FS_ENCRYPTION
1510 : if (needs_encrypt_ops) {
1511 : d_set_d_op(dentry, &generic_encrypted_dentry_ops);
1512 : return;
1513 : }
1514 : #endif
1515 : #if IS_ENABLED(CONFIG_UNICODE)
1516 : if (needs_ci_ops) {
1517 : d_set_d_op(dentry, &generic_ci_dentry_ops);
1518 : return;
1519 : }
1520 : #endif
1521 0 : }
1522 : EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
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