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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * inode.c - part of debugfs, a tiny little debug file system
4 *
5 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2004 IBM Inc.
7 *
8 * debugfs is for people to use instead of /proc or /sys.
9 * See ./Documentation/core-api/kernel-api.rst for more details.
10 */
11
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/mount.h>
15#include <linux/pagemap.h>
16#include <linux/init.h>
17#include <linux/kobject.h>
18#include <linux/namei.h>
19#include <linux/debugfs.h>
20#include <linux/fsnotify.h>
21#include <linux/string.h>
22#include <linux/seq_file.h>
23#include <linux/parser.h>
24#include <linux/magic.h>
25#include <linux/slab.h>
26
27#include "internal.h"
28
29#define DEBUGFS_DEFAULT_MODE 0700
30
31static struct vfsmount *debugfs_mount;
32static int debugfs_mount_count;
33static bool debugfs_registered;
34
35static struct inode *debugfs_get_inode(struct super_block *sb)
36{
37 struct inode *inode = new_inode(sb);
38 if (inode) {
39 inode->i_ino = get_next_ino();
40 inode->i_atime = inode->i_mtime =
41 inode->i_ctime = current_time(inode);
42 }
43 return inode;
44}
45
46struct debugfs_mount_opts {
47 kuid_t uid;
48 kgid_t gid;
49 umode_t mode;
50};
51
52enum {
53 Opt_uid,
54 Opt_gid,
55 Opt_mode,
56 Opt_err
57};
58
59static const match_table_t tokens = {
60 {Opt_uid, "uid=%u"},
61 {Opt_gid, "gid=%u"},
62 {Opt_mode, "mode=%o"},
63 {Opt_err, NULL}
64};
65
66struct debugfs_fs_info {
67 struct debugfs_mount_opts mount_opts;
68};
69
70static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
71{
72 substring_t args[MAX_OPT_ARGS];
73 int option;
74 int token;
75 kuid_t uid;
76 kgid_t gid;
77 char *p;
78
79 opts->mode = DEBUGFS_DEFAULT_MODE;
80
81 while ((p = strsep(&data, ",")) != NULL) {
82 if (!*p)
83 continue;
84
85 token = match_token(p, tokens, args);
86 switch (token) {
87 case Opt_uid:
88 if (match_int(&args[0], &option))
89 return -EINVAL;
90 uid = make_kuid(current_user_ns(), option);
91 if (!uid_valid(uid))
92 return -EINVAL;
93 opts->uid = uid;
94 break;
95 case Opt_gid:
96 if (match_int(&args[0], &option))
97 return -EINVAL;
98 gid = make_kgid(current_user_ns(), option);
99 if (!gid_valid(gid))
100 return -EINVAL;
101 opts->gid = gid;
102 break;
103 case Opt_mode:
104 if (match_octal(&args[0], &option))
105 return -EINVAL;
106 opts->mode = option & S_IALLUGO;
107 break;
108 /*
109 * We might like to report bad mount options here;
110 * but traditionally debugfs has ignored all mount options
111 */
112 }
113 }
114
115 return 0;
116}
117
118static int debugfs_apply_options(struct super_block *sb)
119{
120 struct debugfs_fs_info *fsi = sb->s_fs_info;
121 struct inode *inode = d_inode(sb->s_root);
122 struct debugfs_mount_opts *opts = &fsi->mount_opts;
123
124 inode->i_mode &= ~S_IALLUGO;
125 inode->i_mode |= opts->mode;
126
127 inode->i_uid = opts->uid;
128 inode->i_gid = opts->gid;
129
130 return 0;
131}
132
133static int debugfs_remount(struct super_block *sb, int *flags, char *data)
134{
135 int err;
136 struct debugfs_fs_info *fsi = sb->s_fs_info;
137
138 sync_filesystem(sb);
139 err = debugfs_parse_options(data, &fsi->mount_opts);
140 if (err)
141 goto fail;
142
143 debugfs_apply_options(sb);
144
145fail:
146 return err;
147}
148
149static int debugfs_show_options(struct seq_file *m, struct dentry *root)
150{
151 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
152 struct debugfs_mount_opts *opts = &fsi->mount_opts;
153
154 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
155 seq_printf(m, ",uid=%u",
156 from_kuid_munged(&init_user_ns, opts->uid));
157 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
158 seq_printf(m, ",gid=%u",
159 from_kgid_munged(&init_user_ns, opts->gid));
160 if (opts->mode != DEBUGFS_DEFAULT_MODE)
161 seq_printf(m, ",mode=%o", opts->mode);
162
163 return 0;
164}
165
166static void debugfs_evict_inode(struct inode *inode)
167{
168 truncate_inode_pages_final(&inode->i_data);
169 clear_inode(inode);
170 if (S_ISLNK(inode->i_mode))
171 kfree(inode->i_link);
172}
173
174static const struct super_operations debugfs_super_operations = {
175 .statfs = simple_statfs,
176 .remount_fs = debugfs_remount,
177 .show_options = debugfs_show_options,
178 .evict_inode = debugfs_evict_inode,
179};
180
181static void debugfs_release_dentry(struct dentry *dentry)
182{
183 void *fsd = dentry->d_fsdata;
184
185 if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
186 kfree(dentry->d_fsdata);
187}
188
189static struct vfsmount *debugfs_automount(struct path *path)
190{
191 debugfs_automount_t f;
192 f = (debugfs_automount_t)path->dentry->d_fsdata;
193 return f(path->dentry, d_inode(path->dentry)->i_private);
194}
195
196static const struct dentry_operations debugfs_dops = {
197 .d_delete = always_delete_dentry,
198 .d_release = debugfs_release_dentry,
199 .d_automount = debugfs_automount,
200};
201
202static int debug_fill_super(struct super_block *sb, void *data, int silent)
203{
204 static const struct tree_descr debug_files[] = {{""}};
205 struct debugfs_fs_info *fsi;
206 int err;
207
208 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
209 sb->s_fs_info = fsi;
210 if (!fsi) {
211 err = -ENOMEM;
212 goto fail;
213 }
214
215 err = debugfs_parse_options(data, &fsi->mount_opts);
216 if (err)
217 goto fail;
218
219 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
220 if (err)
221 goto fail;
222
223 sb->s_op = &debugfs_super_operations;
224 sb->s_d_op = &debugfs_dops;
225
226 debugfs_apply_options(sb);
227
228 return 0;
229
230fail:
231 kfree(fsi);
232 sb->s_fs_info = NULL;
233 return err;
234}
235
236static struct dentry *debug_mount(struct file_system_type *fs_type,
237 int flags, const char *dev_name,
238 void *data)
239{
240 return mount_single(fs_type, flags, data, debug_fill_super);
241}
242
243static struct file_system_type debug_fs_type = {
244 .owner = THIS_MODULE,
245 .name = "debugfs",
246 .mount = debug_mount,
247 .kill_sb = kill_litter_super,
248};
249MODULE_ALIAS_FS("debugfs");
250
251/**
252 * debugfs_lookup() - look up an existing debugfs file
253 * @name: a pointer to a string containing the name of the file to look up.
254 * @parent: a pointer to the parent dentry of the file.
255 *
256 * This function will return a pointer to a dentry if it succeeds. If the file
257 * doesn't exist or an error occurs, %NULL will be returned. The returned
258 * dentry must be passed to dput() when it is no longer needed.
259 *
260 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
261 * returned.
262 */
263struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
264{
265 struct dentry *dentry;
266
267 if (IS_ERR(parent))
268 return NULL;
269
270 if (!parent)
271 parent = debugfs_mount->mnt_root;
272
273 dentry = lookup_one_len_unlocked(name, parent, strlen(name));
274 if (IS_ERR(dentry))
275 return NULL;
276 if (!d_really_is_positive(dentry)) {
277 dput(dentry);
278 return NULL;
279 }
280 return dentry;
281}
282EXPORT_SYMBOL_GPL(debugfs_lookup);
283
284static struct dentry *start_creating(const char *name, struct dentry *parent)
285{
286 struct dentry *dentry;
287 int error;
288
289 pr_debug("debugfs: creating file '%s'\n",name);
290
291 if (IS_ERR(parent))
292 return parent;
293
294 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
295 &debugfs_mount_count);
296 if (error)
297 return ERR_PTR(error);
298
299 /* If the parent is not specified, we create it in the root.
300 * We need the root dentry to do this, which is in the super
301 * block. A pointer to that is in the struct vfsmount that we
302 * have around.
303 */
304 if (!parent)
305 parent = debugfs_mount->mnt_root;
306
307 inode_lock(d_inode(parent));
308 dentry = lookup_one_len(name, parent, strlen(name));
309 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
310 dput(dentry);
311 dentry = ERR_PTR(-EEXIST);
312 }
313
314 if (IS_ERR(dentry)) {
315 inode_unlock(d_inode(parent));
316 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
317 }
318
319 return dentry;
320}
321
322static struct dentry *failed_creating(struct dentry *dentry)
323{
324 inode_unlock(d_inode(dentry->d_parent));
325 dput(dentry);
326 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
327 return NULL;
328}
329
330static struct dentry *end_creating(struct dentry *dentry)
331{
332 inode_unlock(d_inode(dentry->d_parent));
333 return dentry;
334}
335
336static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
337 struct dentry *parent, void *data,
338 const struct file_operations *proxy_fops,
339 const struct file_operations *real_fops)
340{
341 struct dentry *dentry;
342 struct inode *inode;
343
344 if (!(mode & S_IFMT))
345 mode |= S_IFREG;
346 BUG_ON(!S_ISREG(mode));
347 dentry = start_creating(name, parent);
348
349 if (IS_ERR(dentry))
350 return NULL;
351
352 inode = debugfs_get_inode(dentry->d_sb);
353 if (unlikely(!inode))
354 return failed_creating(dentry);
355
356 inode->i_mode = mode;
357 inode->i_private = data;
358
359 inode->i_fop = proxy_fops;
360 dentry->d_fsdata = (void *)((unsigned long)real_fops |
361 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
362
363 d_instantiate(dentry, inode);
364 fsnotify_create(d_inode(dentry->d_parent), dentry);
365 return end_creating(dentry);
366}
367
368/**
369 * debugfs_create_file - create a file in the debugfs filesystem
370 * @name: a pointer to a string containing the name of the file to create.
371 * @mode: the permission that the file should have.
372 * @parent: a pointer to the parent dentry for this file. This should be a
373 * directory dentry if set. If this parameter is NULL, then the
374 * file will be created in the root of the debugfs filesystem.
375 * @data: a pointer to something that the caller will want to get to later
376 * on. The inode.i_private pointer will point to this value on
377 * the open() call.
378 * @fops: a pointer to a struct file_operations that should be used for
379 * this file.
380 *
381 * This is the basic "create a file" function for debugfs. It allows for a
382 * wide range of flexibility in creating a file, or a directory (if you want
383 * to create a directory, the debugfs_create_dir() function is
384 * recommended to be used instead.)
385 *
386 * This function will return a pointer to a dentry if it succeeds. This
387 * pointer must be passed to the debugfs_remove() function when the file is
388 * to be removed (no automatic cleanup happens if your module is unloaded,
389 * you are responsible here.) If an error occurs, %NULL will be returned.
390 *
391 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
392 * returned.
393 */
394struct dentry *debugfs_create_file(const char *name, umode_t mode,
395 struct dentry *parent, void *data,
396 const struct file_operations *fops)
397{
398
399 return __debugfs_create_file(name, mode, parent, data,
400 fops ? &debugfs_full_proxy_file_operations :
401 &debugfs_noop_file_operations,
402 fops);
403}
404EXPORT_SYMBOL_GPL(debugfs_create_file);
405
406/**
407 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
408 * @name: a pointer to a string containing the name of the file to create.
409 * @mode: the permission that the file should have.
410 * @parent: a pointer to the parent dentry for this file. This should be a
411 * directory dentry if set. If this parameter is NULL, then the
412 * file will be created in the root of the debugfs filesystem.
413 * @data: a pointer to something that the caller will want to get to later
414 * on. The inode.i_private pointer will point to this value on
415 * the open() call.
416 * @fops: a pointer to a struct file_operations that should be used for
417 * this file.
418 *
419 * debugfs_create_file_unsafe() is completely analogous to
420 * debugfs_create_file(), the only difference being that the fops
421 * handed it will not get protected against file removals by the
422 * debugfs core.
423 *
424 * It is your responsibility to protect your struct file_operation
425 * methods against file removals by means of debugfs_use_file_start()
426 * and debugfs_use_file_finish(). ->open() is still protected by
427 * debugfs though.
428 *
429 * Any struct file_operations defined by means of
430 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
431 * thus, may be used here.
432 */
433struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
434 struct dentry *parent, void *data,
435 const struct file_operations *fops)
436{
437
438 return __debugfs_create_file(name, mode, parent, data,
439 fops ? &debugfs_open_proxy_file_operations :
440 &debugfs_noop_file_operations,
441 fops);
442}
443EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
444
445/**
446 * debugfs_create_file_size - create a file in the debugfs filesystem
447 * @name: a pointer to a string containing the name of the file to create.
448 * @mode: the permission that the file should have.
449 * @parent: a pointer to the parent dentry for this file. This should be a
450 * directory dentry if set. If this parameter is NULL, then the
451 * file will be created in the root of the debugfs filesystem.
452 * @data: a pointer to something that the caller will want to get to later
453 * on. The inode.i_private pointer will point to this value on
454 * the open() call.
455 * @fops: a pointer to a struct file_operations that should be used for
456 * this file.
457 * @file_size: initial file size
458 *
459 * This is the basic "create a file" function for debugfs. It allows for a
460 * wide range of flexibility in creating a file, or a directory (if you want
461 * to create a directory, the debugfs_create_dir() function is
462 * recommended to be used instead.)
463 *
464 * This function will return a pointer to a dentry if it succeeds. This
465 * pointer must be passed to the debugfs_remove() function when the file is
466 * to be removed (no automatic cleanup happens if your module is unloaded,
467 * you are responsible here.) If an error occurs, %NULL will be returned.
468 *
469 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
470 * returned.
471 */
472struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
473 struct dentry *parent, void *data,
474 const struct file_operations *fops,
475 loff_t file_size)
476{
477 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
478
479 if (de)
480 d_inode(de)->i_size = file_size;
481 return de;
482}
483EXPORT_SYMBOL_GPL(debugfs_create_file_size);
484
485/**
486 * debugfs_create_dir - create a directory in the debugfs filesystem
487 * @name: a pointer to a string containing the name of the directory to
488 * create.
489 * @parent: a pointer to the parent dentry for this file. This should be a
490 * directory dentry if set. If this parameter is NULL, then the
491 * directory will be created in the root of the debugfs filesystem.
492 *
493 * This function creates a directory in debugfs with the given name.
494 *
495 * This function will return a pointer to a dentry if it succeeds. This
496 * pointer must be passed to the debugfs_remove() function when the file is
497 * to be removed (no automatic cleanup happens if your module is unloaded,
498 * you are responsible here.) If an error occurs, %NULL will be returned.
499 *
500 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
501 * returned.
502 */
503struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
504{
505 struct dentry *dentry = start_creating(name, parent);
506 struct inode *inode;
507
508 if (IS_ERR(dentry))
509 return NULL;
510
511 inode = debugfs_get_inode(dentry->d_sb);
512 if (unlikely(!inode))
513 return failed_creating(dentry);
514
515 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
516 inode->i_op = &simple_dir_inode_operations;
517 inode->i_fop = &simple_dir_operations;
518
519 /* directory inodes start off with i_nlink == 2 (for "." entry) */
520 inc_nlink(inode);
521 d_instantiate(dentry, inode);
522 inc_nlink(d_inode(dentry->d_parent));
523 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
524 return end_creating(dentry);
525}
526EXPORT_SYMBOL_GPL(debugfs_create_dir);
527
528/**
529 * debugfs_create_automount - create automount point in the debugfs filesystem
530 * @name: a pointer to a string containing the name of the file to create.
531 * @parent: a pointer to the parent dentry for this file. This should be a
532 * directory dentry if set. If this parameter is NULL, then the
533 * file will be created in the root of the debugfs filesystem.
534 * @f: function to be called when pathname resolution steps on that one.
535 * @data: opaque argument to pass to f().
536 *
537 * @f should return what ->d_automount() would.
538 */
539struct dentry *debugfs_create_automount(const char *name,
540 struct dentry *parent,
541 debugfs_automount_t f,
542 void *data)
543{
544 struct dentry *dentry = start_creating(name, parent);
545 struct inode *inode;
546
547 if (IS_ERR(dentry))
548 return NULL;
549
550 inode = debugfs_get_inode(dentry->d_sb);
551 if (unlikely(!inode))
552 return failed_creating(dentry);
553
554 make_empty_dir_inode(inode);
555 inode->i_flags |= S_AUTOMOUNT;
556 inode->i_private = data;
557 dentry->d_fsdata = (void *)f;
558 /* directory inodes start off with i_nlink == 2 (for "." entry) */
559 inc_nlink(inode);
560 d_instantiate(dentry, inode);
561 inc_nlink(d_inode(dentry->d_parent));
562 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
563 return end_creating(dentry);
564}
565EXPORT_SYMBOL(debugfs_create_automount);
566
567/**
568 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
569 * @name: a pointer to a string containing the name of the symbolic link to
570 * create.
571 * @parent: a pointer to the parent dentry for this symbolic link. This
572 * should be a directory dentry if set. If this parameter is NULL,
573 * then the symbolic link will be created in the root of the debugfs
574 * filesystem.
575 * @target: a pointer to a string containing the path to the target of the
576 * symbolic link.
577 *
578 * This function creates a symbolic link with the given name in debugfs that
579 * links to the given target path.
580 *
581 * This function will return a pointer to a dentry if it succeeds. This
582 * pointer must be passed to the debugfs_remove() function when the symbolic
583 * link is to be removed (no automatic cleanup happens if your module is
584 * unloaded, you are responsible here.) If an error occurs, %NULL will be
585 * returned.
586 *
587 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
588 * returned.
589 */
590struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
591 const char *target)
592{
593 struct dentry *dentry;
594 struct inode *inode;
595 char *link = kstrdup(target, GFP_KERNEL);
596 if (!link)
597 return NULL;
598
599 dentry = start_creating(name, parent);
600 if (IS_ERR(dentry)) {
601 kfree(link);
602 return NULL;
603 }
604
605 inode = debugfs_get_inode(dentry->d_sb);
606 if (unlikely(!inode)) {
607 kfree(link);
608 return failed_creating(dentry);
609 }
610 inode->i_mode = S_IFLNK | S_IRWXUGO;
611 inode->i_op = &simple_symlink_inode_operations;
612 inode->i_link = link;
613 d_instantiate(dentry, inode);
614 return end_creating(dentry);
615}
616EXPORT_SYMBOL_GPL(debugfs_create_symlink);
617
618static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent)
619{
620 struct debugfs_fsdata *fsd;
621
622 simple_unlink(d_inode(parent), dentry);
623 d_delete(dentry);
624
625 /*
626 * Paired with the closing smp_mb() implied by a successful
627 * cmpxchg() in debugfs_file_get(): either
628 * debugfs_file_get() must see a dead dentry or we must see a
629 * debugfs_fsdata instance at ->d_fsdata here (or both).
630 */
631 smp_mb();
632 fsd = READ_ONCE(dentry->d_fsdata);
633 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
634 return;
635 if (!refcount_dec_and_test(&fsd->active_users))
636 wait_for_completion(&fsd->active_users_drained);
637}
638
639static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
640{
641 int ret = 0;
642
643 if (simple_positive(dentry)) {
644 dget(dentry);
645 if (!d_is_reg(dentry)) {
646 if (d_is_dir(dentry))
647 ret = simple_rmdir(d_inode(parent), dentry);
648 else
649 simple_unlink(d_inode(parent), dentry);
650 if (!ret)
651 d_delete(dentry);
652 } else {
653 __debugfs_remove_file(dentry, parent);
654 }
655 dput(dentry);
656 }
657 return ret;
658}
659
660/**
661 * debugfs_remove - removes a file or directory from the debugfs filesystem
662 * @dentry: a pointer to a the dentry of the file or directory to be
663 * removed. If this parameter is NULL or an error value, nothing
664 * will be done.
665 *
666 * This function removes a file or directory in debugfs that was previously
667 * created with a call to another debugfs function (like
668 * debugfs_create_file() or variants thereof.)
669 *
670 * This function is required to be called in order for the file to be
671 * removed, no automatic cleanup of files will happen when a module is
672 * removed, you are responsible here.
673 */
674void debugfs_remove(struct dentry *dentry)
675{
676 struct dentry *parent;
677 int ret;
678
679 if (IS_ERR_OR_NULL(dentry))
680 return;
681
682 parent = dentry->d_parent;
683 inode_lock(d_inode(parent));
684 ret = __debugfs_remove(dentry, parent);
685 inode_unlock(d_inode(parent));
686 if (!ret)
687 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
688}
689EXPORT_SYMBOL_GPL(debugfs_remove);
690
691/**
692 * debugfs_remove_recursive - recursively removes a directory
693 * @dentry: a pointer to a the dentry of the directory to be removed. If this
694 * parameter is NULL or an error value, nothing will be done.
695 *
696 * This function recursively removes a directory tree in debugfs that
697 * was previously created with a call to another debugfs function
698 * (like debugfs_create_file() or variants thereof.)
699 *
700 * This function is required to be called in order for the file to be
701 * removed, no automatic cleanup of files will happen when a module is
702 * removed, you are responsible here.
703 */
704void debugfs_remove_recursive(struct dentry *dentry)
705{
706 struct dentry *child, *parent;
707
708 if (IS_ERR_OR_NULL(dentry))
709 return;
710
711 parent = dentry;
712 down:
713 inode_lock(d_inode(parent));
714 loop:
715 /*
716 * The parent->d_subdirs is protected by the d_lock. Outside that
717 * lock, the child can be unlinked and set to be freed which can
718 * use the d_u.d_child as the rcu head and corrupt this list.
719 */
720 spin_lock(&parent->d_lock);
721 list_for_each_entry(child, &parent->d_subdirs, d_child) {
722 if (!simple_positive(child))
723 continue;
724
725 /* perhaps simple_empty(child) makes more sense */
726 if (!list_empty(&child->d_subdirs)) {
727 spin_unlock(&parent->d_lock);
728 inode_unlock(d_inode(parent));
729 parent = child;
730 goto down;
731 }
732
733 spin_unlock(&parent->d_lock);
734
735 if (!__debugfs_remove(child, parent))
736 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
737
738 /*
739 * The parent->d_lock protects agaist child from unlinking
740 * from d_subdirs. When releasing the parent->d_lock we can
741 * no longer trust that the next pointer is valid.
742 * Restart the loop. We'll skip this one with the
743 * simple_positive() check.
744 */
745 goto loop;
746 }
747 spin_unlock(&parent->d_lock);
748
749 inode_unlock(d_inode(parent));
750 child = parent;
751 parent = parent->d_parent;
752 inode_lock(d_inode(parent));
753
754 if (child != dentry)
755 /* go up */
756 goto loop;
757
758 if (!__debugfs_remove(child, parent))
759 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
760 inode_unlock(d_inode(parent));
761}
762EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
763
764/**
765 * debugfs_rename - rename a file/directory in the debugfs filesystem
766 * @old_dir: a pointer to the parent dentry for the renamed object. This
767 * should be a directory dentry.
768 * @old_dentry: dentry of an object to be renamed.
769 * @new_dir: a pointer to the parent dentry where the object should be
770 * moved. This should be a directory dentry.
771 * @new_name: a pointer to a string containing the target name.
772 *
773 * This function renames a file/directory in debugfs. The target must not
774 * exist for rename to succeed.
775 *
776 * This function will return a pointer to old_dentry (which is updated to
777 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
778 * returned.
779 *
780 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
781 * returned.
782 */
783struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
784 struct dentry *new_dir, const char *new_name)
785{
786 int error;
787 struct dentry *dentry = NULL, *trap;
788 struct name_snapshot old_name;
789
790 trap = lock_rename(new_dir, old_dir);
791 /* Source or destination directories don't exist? */
792 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
793 goto exit;
794 /* Source does not exist, cyclic rename, or mountpoint? */
795 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
796 d_mountpoint(old_dentry))
797 goto exit;
798 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
799 /* Lookup failed, cyclic rename or target exists? */
800 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
801 goto exit;
802
803 take_dentry_name_snapshot(&old_name, old_dentry);
804
805 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
806 dentry, 0);
807 if (error) {
808 release_dentry_name_snapshot(&old_name);
809 goto exit;
810 }
811 d_move(old_dentry, dentry);
812 fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
813 d_is_dir(old_dentry),
814 NULL, old_dentry);
815 release_dentry_name_snapshot(&old_name);
816 unlock_rename(new_dir, old_dir);
817 dput(dentry);
818 return old_dentry;
819exit:
820 if (dentry && !IS_ERR(dentry))
821 dput(dentry);
822 unlock_rename(new_dir, old_dir);
823 return NULL;
824}
825EXPORT_SYMBOL_GPL(debugfs_rename);
826
827/**
828 * debugfs_initialized - Tells whether debugfs has been registered
829 */
830bool debugfs_initialized(void)
831{
832 return debugfs_registered;
833}
834EXPORT_SYMBOL_GPL(debugfs_initialized);
835
836static int __init debugfs_init(void)
837{
838 int retval;
839
840 retval = sysfs_create_mount_point(kernel_kobj, "debug");
841 if (retval)
842 return retval;
843
844 retval = register_filesystem(&debug_fs_type);
845 if (retval)
846 sysfs_remove_mount_point(kernel_kobj, "debug");
847 else
848 debugfs_registered = true;
849
850 return retval;
851}
852core_initcall(debugfs_init);
853
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * inode.c - part of debugfs, a tiny little debug file system
4 *
5 * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2004 IBM Inc.
7 * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
8 *
9 * debugfs is for people to use instead of /proc or /sys.
10 * See ./Documentation/core-api/kernel-api.rst for more details.
11 */
12
13#define pr_fmt(fmt) "debugfs: " fmt
14
15#include <linux/module.h>
16#include <linux/fs.h>
17#include <linux/mount.h>
18#include <linux/pagemap.h>
19#include <linux/init.h>
20#include <linux/kobject.h>
21#include <linux/namei.h>
22#include <linux/debugfs.h>
23#include <linux/fsnotify.h>
24#include <linux/string.h>
25#include <linux/seq_file.h>
26#include <linux/parser.h>
27#include <linux/magic.h>
28#include <linux/slab.h>
29#include <linux/security.h>
30
31#include "internal.h"
32
33#define DEBUGFS_DEFAULT_MODE 0700
34
35static struct vfsmount *debugfs_mount;
36static int debugfs_mount_count;
37static bool debugfs_registered;
38static unsigned int debugfs_allow = DEFAULT_DEBUGFS_ALLOW_BITS;
39
40/*
41 * Don't allow access attributes to be changed whilst the kernel is locked down
42 * so that we can use the file mode as part of a heuristic to determine whether
43 * to lock down individual files.
44 */
45static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
46{
47 int ret = security_locked_down(LOCKDOWN_DEBUGFS);
48
49 if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
50 return ret;
51 return simple_setattr(dentry, ia);
52}
53
54static const struct inode_operations debugfs_file_inode_operations = {
55 .setattr = debugfs_setattr,
56};
57static const struct inode_operations debugfs_dir_inode_operations = {
58 .lookup = simple_lookup,
59 .setattr = debugfs_setattr,
60};
61static const struct inode_operations debugfs_symlink_inode_operations = {
62 .get_link = simple_get_link,
63 .setattr = debugfs_setattr,
64};
65
66static struct inode *debugfs_get_inode(struct super_block *sb)
67{
68 struct inode *inode = new_inode(sb);
69 if (inode) {
70 inode->i_ino = get_next_ino();
71 inode->i_atime = inode->i_mtime =
72 inode->i_ctime = current_time(inode);
73 }
74 return inode;
75}
76
77struct debugfs_mount_opts {
78 kuid_t uid;
79 kgid_t gid;
80 umode_t mode;
81};
82
83enum {
84 Opt_uid,
85 Opt_gid,
86 Opt_mode,
87 Opt_err
88};
89
90static const match_table_t tokens = {
91 {Opt_uid, "uid=%u"},
92 {Opt_gid, "gid=%u"},
93 {Opt_mode, "mode=%o"},
94 {Opt_err, NULL}
95};
96
97struct debugfs_fs_info {
98 struct debugfs_mount_opts mount_opts;
99};
100
101static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
102{
103 substring_t args[MAX_OPT_ARGS];
104 int option;
105 int token;
106 kuid_t uid;
107 kgid_t gid;
108 char *p;
109
110 opts->mode = DEBUGFS_DEFAULT_MODE;
111
112 while ((p = strsep(&data, ",")) != NULL) {
113 if (!*p)
114 continue;
115
116 token = match_token(p, tokens, args);
117 switch (token) {
118 case Opt_uid:
119 if (match_int(&args[0], &option))
120 return -EINVAL;
121 uid = make_kuid(current_user_ns(), option);
122 if (!uid_valid(uid))
123 return -EINVAL;
124 opts->uid = uid;
125 break;
126 case Opt_gid:
127 if (match_int(&args[0], &option))
128 return -EINVAL;
129 gid = make_kgid(current_user_ns(), option);
130 if (!gid_valid(gid))
131 return -EINVAL;
132 opts->gid = gid;
133 break;
134 case Opt_mode:
135 if (match_octal(&args[0], &option))
136 return -EINVAL;
137 opts->mode = option & S_IALLUGO;
138 break;
139 /*
140 * We might like to report bad mount options here;
141 * but traditionally debugfs has ignored all mount options
142 */
143 }
144 }
145
146 return 0;
147}
148
149static int debugfs_apply_options(struct super_block *sb)
150{
151 struct debugfs_fs_info *fsi = sb->s_fs_info;
152 struct inode *inode = d_inode(sb->s_root);
153 struct debugfs_mount_opts *opts = &fsi->mount_opts;
154
155 inode->i_mode &= ~S_IALLUGO;
156 inode->i_mode |= opts->mode;
157
158 inode->i_uid = opts->uid;
159 inode->i_gid = opts->gid;
160
161 return 0;
162}
163
164static int debugfs_remount(struct super_block *sb, int *flags, char *data)
165{
166 int err;
167 struct debugfs_fs_info *fsi = sb->s_fs_info;
168
169 sync_filesystem(sb);
170 err = debugfs_parse_options(data, &fsi->mount_opts);
171 if (err)
172 goto fail;
173
174 debugfs_apply_options(sb);
175
176fail:
177 return err;
178}
179
180static int debugfs_show_options(struct seq_file *m, struct dentry *root)
181{
182 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
183 struct debugfs_mount_opts *opts = &fsi->mount_opts;
184
185 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
186 seq_printf(m, ",uid=%u",
187 from_kuid_munged(&init_user_ns, opts->uid));
188 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
189 seq_printf(m, ",gid=%u",
190 from_kgid_munged(&init_user_ns, opts->gid));
191 if (opts->mode != DEBUGFS_DEFAULT_MODE)
192 seq_printf(m, ",mode=%o", opts->mode);
193
194 return 0;
195}
196
197static void debugfs_free_inode(struct inode *inode)
198{
199 if (S_ISLNK(inode->i_mode))
200 kfree(inode->i_link);
201 free_inode_nonrcu(inode);
202}
203
204static const struct super_operations debugfs_super_operations = {
205 .statfs = simple_statfs,
206 .remount_fs = debugfs_remount,
207 .show_options = debugfs_show_options,
208 .free_inode = debugfs_free_inode,
209};
210
211static void debugfs_release_dentry(struct dentry *dentry)
212{
213 void *fsd = dentry->d_fsdata;
214
215 if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
216 kfree(dentry->d_fsdata);
217}
218
219static struct vfsmount *debugfs_automount(struct path *path)
220{
221 debugfs_automount_t f;
222 f = (debugfs_automount_t)path->dentry->d_fsdata;
223 return f(path->dentry, d_inode(path->dentry)->i_private);
224}
225
226static const struct dentry_operations debugfs_dops = {
227 .d_delete = always_delete_dentry,
228 .d_release = debugfs_release_dentry,
229 .d_automount = debugfs_automount,
230};
231
232static int debug_fill_super(struct super_block *sb, void *data, int silent)
233{
234 static const struct tree_descr debug_files[] = {{""}};
235 struct debugfs_fs_info *fsi;
236 int err;
237
238 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
239 sb->s_fs_info = fsi;
240 if (!fsi) {
241 err = -ENOMEM;
242 goto fail;
243 }
244
245 err = debugfs_parse_options(data, &fsi->mount_opts);
246 if (err)
247 goto fail;
248
249 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
250 if (err)
251 goto fail;
252
253 sb->s_op = &debugfs_super_operations;
254 sb->s_d_op = &debugfs_dops;
255
256 debugfs_apply_options(sb);
257
258 return 0;
259
260fail:
261 kfree(fsi);
262 sb->s_fs_info = NULL;
263 return err;
264}
265
266static struct dentry *debug_mount(struct file_system_type *fs_type,
267 int flags, const char *dev_name,
268 void *data)
269{
270 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
271 return ERR_PTR(-EPERM);
272
273 return mount_single(fs_type, flags, data, debug_fill_super);
274}
275
276static struct file_system_type debug_fs_type = {
277 .owner = THIS_MODULE,
278 .name = "debugfs",
279 .mount = debug_mount,
280 .kill_sb = kill_litter_super,
281};
282MODULE_ALIAS_FS("debugfs");
283
284/**
285 * debugfs_lookup() - look up an existing debugfs file
286 * @name: a pointer to a string containing the name of the file to look up.
287 * @parent: a pointer to the parent dentry of the file.
288 *
289 * This function will return a pointer to a dentry if it succeeds. If the file
290 * doesn't exist or an error occurs, %NULL will be returned. The returned
291 * dentry must be passed to dput() when it is no longer needed.
292 *
293 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
294 * returned.
295 */
296struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
297{
298 struct dentry *dentry;
299
300 if (IS_ERR(parent))
301 return NULL;
302
303 if (!parent)
304 parent = debugfs_mount->mnt_root;
305
306 dentry = lookup_positive_unlocked(name, parent, strlen(name));
307 if (IS_ERR(dentry))
308 return NULL;
309 return dentry;
310}
311EXPORT_SYMBOL_GPL(debugfs_lookup);
312
313static struct dentry *start_creating(const char *name, struct dentry *parent)
314{
315 struct dentry *dentry;
316 int error;
317
318 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
319 return ERR_PTR(-EPERM);
320
321 pr_debug("creating file '%s'\n", name);
322
323 if (IS_ERR(parent))
324 return parent;
325
326 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
327 &debugfs_mount_count);
328 if (error) {
329 pr_err("Unable to pin filesystem for file '%s'\n", name);
330 return ERR_PTR(error);
331 }
332
333 /* If the parent is not specified, we create it in the root.
334 * We need the root dentry to do this, which is in the super
335 * block. A pointer to that is in the struct vfsmount that we
336 * have around.
337 */
338 if (!parent)
339 parent = debugfs_mount->mnt_root;
340
341 inode_lock(d_inode(parent));
342 if (unlikely(IS_DEADDIR(d_inode(parent))))
343 dentry = ERR_PTR(-ENOENT);
344 else
345 dentry = lookup_one_len(name, parent, strlen(name));
346 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
347 if (d_is_dir(dentry))
348 pr_err("Directory '%s' with parent '%s' already present!\n",
349 name, parent->d_name.name);
350 else
351 pr_err("File '%s' in directory '%s' already present!\n",
352 name, parent->d_name.name);
353 dput(dentry);
354 dentry = ERR_PTR(-EEXIST);
355 }
356
357 if (IS_ERR(dentry)) {
358 inode_unlock(d_inode(parent));
359 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
360 }
361
362 return dentry;
363}
364
365static struct dentry *failed_creating(struct dentry *dentry)
366{
367 inode_unlock(d_inode(dentry->d_parent));
368 dput(dentry);
369 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
370 return ERR_PTR(-ENOMEM);
371}
372
373static struct dentry *end_creating(struct dentry *dentry)
374{
375 inode_unlock(d_inode(dentry->d_parent));
376 return dentry;
377}
378
379static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
380 struct dentry *parent, void *data,
381 const struct file_operations *proxy_fops,
382 const struct file_operations *real_fops)
383{
384 struct dentry *dentry;
385 struct inode *inode;
386
387 if (!(mode & S_IFMT))
388 mode |= S_IFREG;
389 BUG_ON(!S_ISREG(mode));
390 dentry = start_creating(name, parent);
391
392 if (IS_ERR(dentry))
393 return dentry;
394
395 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
396 failed_creating(dentry);
397 return ERR_PTR(-EPERM);
398 }
399
400 inode = debugfs_get_inode(dentry->d_sb);
401 if (unlikely(!inode)) {
402 pr_err("out of free dentries, can not create file '%s'\n",
403 name);
404 return failed_creating(dentry);
405 }
406
407 inode->i_mode = mode;
408 inode->i_private = data;
409
410 inode->i_op = &debugfs_file_inode_operations;
411 inode->i_fop = proxy_fops;
412 dentry->d_fsdata = (void *)((unsigned long)real_fops |
413 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
414
415 d_instantiate(dentry, inode);
416 fsnotify_create(d_inode(dentry->d_parent), dentry);
417 return end_creating(dentry);
418}
419
420/**
421 * debugfs_create_file - create a file in the debugfs filesystem
422 * @name: a pointer to a string containing the name of the file to create.
423 * @mode: the permission that the file should have.
424 * @parent: a pointer to the parent dentry for this file. This should be a
425 * directory dentry if set. If this parameter is NULL, then the
426 * file will be created in the root of the debugfs filesystem.
427 * @data: a pointer to something that the caller will want to get to later
428 * on. The inode.i_private pointer will point to this value on
429 * the open() call.
430 * @fops: a pointer to a struct file_operations that should be used for
431 * this file.
432 *
433 * This is the basic "create a file" function for debugfs. It allows for a
434 * wide range of flexibility in creating a file, or a directory (if you want
435 * to create a directory, the debugfs_create_dir() function is
436 * recommended to be used instead.)
437 *
438 * This function will return a pointer to a dentry if it succeeds. This
439 * pointer must be passed to the debugfs_remove() function when the file is
440 * to be removed (no automatic cleanup happens if your module is unloaded,
441 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
442 * returned.
443 *
444 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
445 * returned.
446 */
447struct dentry *debugfs_create_file(const char *name, umode_t mode,
448 struct dentry *parent, void *data,
449 const struct file_operations *fops)
450{
451
452 return __debugfs_create_file(name, mode, parent, data,
453 fops ? &debugfs_full_proxy_file_operations :
454 &debugfs_noop_file_operations,
455 fops);
456}
457EXPORT_SYMBOL_GPL(debugfs_create_file);
458
459/**
460 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
461 * @name: a pointer to a string containing the name of the file to create.
462 * @mode: the permission that the file should have.
463 * @parent: a pointer to the parent dentry for this file. This should be a
464 * directory dentry if set. If this parameter is NULL, then the
465 * file will be created in the root of the debugfs filesystem.
466 * @data: a pointer to something that the caller will want to get to later
467 * on. The inode.i_private pointer will point to this value on
468 * the open() call.
469 * @fops: a pointer to a struct file_operations that should be used for
470 * this file.
471 *
472 * debugfs_create_file_unsafe() is completely analogous to
473 * debugfs_create_file(), the only difference being that the fops
474 * handed it will not get protected against file removals by the
475 * debugfs core.
476 *
477 * It is your responsibility to protect your struct file_operation
478 * methods against file removals by means of debugfs_file_get()
479 * and debugfs_file_put(). ->open() is still protected by
480 * debugfs though.
481 *
482 * Any struct file_operations defined by means of
483 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
484 * thus, may be used here.
485 */
486struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
487 struct dentry *parent, void *data,
488 const struct file_operations *fops)
489{
490
491 return __debugfs_create_file(name, mode, parent, data,
492 fops ? &debugfs_open_proxy_file_operations :
493 &debugfs_noop_file_operations,
494 fops);
495}
496EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
497
498/**
499 * debugfs_create_file_size - create a file in the debugfs filesystem
500 * @name: a pointer to a string containing the name of the file to create.
501 * @mode: the permission that the file should have.
502 * @parent: a pointer to the parent dentry for this file. This should be a
503 * directory dentry if set. If this parameter is NULL, then the
504 * file will be created in the root of the debugfs filesystem.
505 * @data: a pointer to something that the caller will want to get to later
506 * on. The inode.i_private pointer will point to this value on
507 * the open() call.
508 * @fops: a pointer to a struct file_operations that should be used for
509 * this file.
510 * @file_size: initial file size
511 *
512 * This is the basic "create a file" function for debugfs. It allows for a
513 * wide range of flexibility in creating a file, or a directory (if you want
514 * to create a directory, the debugfs_create_dir() function is
515 * recommended to be used instead.)
516 */
517void debugfs_create_file_size(const char *name, umode_t mode,
518 struct dentry *parent, void *data,
519 const struct file_operations *fops,
520 loff_t file_size)
521{
522 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
523
524 if (de)
525 d_inode(de)->i_size = file_size;
526}
527EXPORT_SYMBOL_GPL(debugfs_create_file_size);
528
529/**
530 * debugfs_create_dir - create a directory in the debugfs filesystem
531 * @name: a pointer to a string containing the name of the directory to
532 * create.
533 * @parent: a pointer to the parent dentry for this file. This should be a
534 * directory dentry if set. If this parameter is NULL, then the
535 * directory will be created in the root of the debugfs filesystem.
536 *
537 * This function creates a directory in debugfs with the given name.
538 *
539 * This function will return a pointer to a dentry if it succeeds. This
540 * pointer must be passed to the debugfs_remove() function when the file is
541 * to be removed (no automatic cleanup happens if your module is unloaded,
542 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
543 * returned.
544 *
545 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
546 * returned.
547 */
548struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
549{
550 struct dentry *dentry = start_creating(name, parent);
551 struct inode *inode;
552
553 if (IS_ERR(dentry))
554 return dentry;
555
556 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
557 failed_creating(dentry);
558 return ERR_PTR(-EPERM);
559 }
560
561 inode = debugfs_get_inode(dentry->d_sb);
562 if (unlikely(!inode)) {
563 pr_err("out of free dentries, can not create directory '%s'\n",
564 name);
565 return failed_creating(dentry);
566 }
567
568 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
569 inode->i_op = &debugfs_dir_inode_operations;
570 inode->i_fop = &simple_dir_operations;
571
572 /* directory inodes start off with i_nlink == 2 (for "." entry) */
573 inc_nlink(inode);
574 d_instantiate(dentry, inode);
575 inc_nlink(d_inode(dentry->d_parent));
576 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
577 return end_creating(dentry);
578}
579EXPORT_SYMBOL_GPL(debugfs_create_dir);
580
581/**
582 * debugfs_create_automount - create automount point in the debugfs filesystem
583 * @name: a pointer to a string containing the name of the file to create.
584 * @parent: a pointer to the parent dentry for this file. This should be a
585 * directory dentry if set. If this parameter is NULL, then the
586 * file will be created in the root of the debugfs filesystem.
587 * @f: function to be called when pathname resolution steps on that one.
588 * @data: opaque argument to pass to f().
589 *
590 * @f should return what ->d_automount() would.
591 */
592struct dentry *debugfs_create_automount(const char *name,
593 struct dentry *parent,
594 debugfs_automount_t f,
595 void *data)
596{
597 struct dentry *dentry = start_creating(name, parent);
598 struct inode *inode;
599
600 if (IS_ERR(dentry))
601 return dentry;
602
603 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
604 failed_creating(dentry);
605 return ERR_PTR(-EPERM);
606 }
607
608 inode = debugfs_get_inode(dentry->d_sb);
609 if (unlikely(!inode)) {
610 pr_err("out of free dentries, can not create automount '%s'\n",
611 name);
612 return failed_creating(dentry);
613 }
614
615 make_empty_dir_inode(inode);
616 inode->i_flags |= S_AUTOMOUNT;
617 inode->i_private = data;
618 dentry->d_fsdata = (void *)f;
619 /* directory inodes start off with i_nlink == 2 (for "." entry) */
620 inc_nlink(inode);
621 d_instantiate(dentry, inode);
622 inc_nlink(d_inode(dentry->d_parent));
623 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
624 return end_creating(dentry);
625}
626EXPORT_SYMBOL(debugfs_create_automount);
627
628/**
629 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
630 * @name: a pointer to a string containing the name of the symbolic link to
631 * create.
632 * @parent: a pointer to the parent dentry for this symbolic link. This
633 * should be a directory dentry if set. If this parameter is NULL,
634 * then the symbolic link will be created in the root of the debugfs
635 * filesystem.
636 * @target: a pointer to a string containing the path to the target of the
637 * symbolic link.
638 *
639 * This function creates a symbolic link with the given name in debugfs that
640 * links to the given target path.
641 *
642 * This function will return a pointer to a dentry if it succeeds. This
643 * pointer must be passed to the debugfs_remove() function when the symbolic
644 * link is to be removed (no automatic cleanup happens if your module is
645 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
646 * will be returned.
647 *
648 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
649 * returned.
650 */
651struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
652 const char *target)
653{
654 struct dentry *dentry;
655 struct inode *inode;
656 char *link = kstrdup(target, GFP_KERNEL);
657 if (!link)
658 return ERR_PTR(-ENOMEM);
659
660 dentry = start_creating(name, parent);
661 if (IS_ERR(dentry)) {
662 kfree(link);
663 return dentry;
664 }
665
666 inode = debugfs_get_inode(dentry->d_sb);
667 if (unlikely(!inode)) {
668 pr_err("out of free dentries, can not create symlink '%s'\n",
669 name);
670 kfree(link);
671 return failed_creating(dentry);
672 }
673 inode->i_mode = S_IFLNK | S_IRWXUGO;
674 inode->i_op = &debugfs_symlink_inode_operations;
675 inode->i_link = link;
676 d_instantiate(dentry, inode);
677 return end_creating(dentry);
678}
679EXPORT_SYMBOL_GPL(debugfs_create_symlink);
680
681static void __debugfs_file_removed(struct dentry *dentry)
682{
683 struct debugfs_fsdata *fsd;
684
685 /*
686 * Paired with the closing smp_mb() implied by a successful
687 * cmpxchg() in debugfs_file_get(): either
688 * debugfs_file_get() must see a dead dentry or we must see a
689 * debugfs_fsdata instance at ->d_fsdata here (or both).
690 */
691 smp_mb();
692 fsd = READ_ONCE(dentry->d_fsdata);
693 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
694 return;
695 if (!refcount_dec_and_test(&fsd->active_users))
696 wait_for_completion(&fsd->active_users_drained);
697}
698
699static void remove_one(struct dentry *victim)
700{
701 if (d_is_reg(victim))
702 __debugfs_file_removed(victim);
703 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
704}
705
706/**
707 * debugfs_remove - recursively removes a directory
708 * @dentry: a pointer to a the dentry of the directory to be removed. If this
709 * parameter is NULL or an error value, nothing will be done.
710 *
711 * This function recursively removes a directory tree in debugfs that
712 * was previously created with a call to another debugfs function
713 * (like debugfs_create_file() or variants thereof.)
714 *
715 * This function is required to be called in order for the file to be
716 * removed, no automatic cleanup of files will happen when a module is
717 * removed, you are responsible here.
718 */
719void debugfs_remove(struct dentry *dentry)
720{
721 if (IS_ERR_OR_NULL(dentry))
722 return;
723
724 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
725 simple_recursive_removal(dentry, remove_one);
726 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
727}
728EXPORT_SYMBOL_GPL(debugfs_remove);
729
730/**
731 * debugfs_rename - rename a file/directory in the debugfs filesystem
732 * @old_dir: a pointer to the parent dentry for the renamed object. This
733 * should be a directory dentry.
734 * @old_dentry: dentry of an object to be renamed.
735 * @new_dir: a pointer to the parent dentry where the object should be
736 * moved. This should be a directory dentry.
737 * @new_name: a pointer to a string containing the target name.
738 *
739 * This function renames a file/directory in debugfs. The target must not
740 * exist for rename to succeed.
741 *
742 * This function will return a pointer to old_dentry (which is updated to
743 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
744 * returned.
745 *
746 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
747 * returned.
748 */
749struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
750 struct dentry *new_dir, const char *new_name)
751{
752 int error;
753 struct dentry *dentry = NULL, *trap;
754 struct name_snapshot old_name;
755
756 if (IS_ERR(old_dir))
757 return old_dir;
758 if (IS_ERR(new_dir))
759 return new_dir;
760 if (IS_ERR_OR_NULL(old_dentry))
761 return old_dentry;
762
763 trap = lock_rename(new_dir, old_dir);
764 /* Source or destination directories don't exist? */
765 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
766 goto exit;
767 /* Source does not exist, cyclic rename, or mountpoint? */
768 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
769 d_mountpoint(old_dentry))
770 goto exit;
771 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
772 /* Lookup failed, cyclic rename or target exists? */
773 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
774 goto exit;
775
776 take_dentry_name_snapshot(&old_name, old_dentry);
777
778 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
779 dentry, 0);
780 if (error) {
781 release_dentry_name_snapshot(&old_name);
782 goto exit;
783 }
784 d_move(old_dentry, dentry);
785 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
786 d_is_dir(old_dentry),
787 NULL, old_dentry);
788 release_dentry_name_snapshot(&old_name);
789 unlock_rename(new_dir, old_dir);
790 dput(dentry);
791 return old_dentry;
792exit:
793 if (dentry && !IS_ERR(dentry))
794 dput(dentry);
795 unlock_rename(new_dir, old_dir);
796 if (IS_ERR(dentry))
797 return dentry;
798 return ERR_PTR(-EINVAL);
799}
800EXPORT_SYMBOL_GPL(debugfs_rename);
801
802/**
803 * debugfs_initialized - Tells whether debugfs has been registered
804 */
805bool debugfs_initialized(void)
806{
807 return debugfs_registered;
808}
809EXPORT_SYMBOL_GPL(debugfs_initialized);
810
811static int __init debugfs_kernel(char *str)
812{
813 if (str) {
814 if (!strcmp(str, "on"))
815 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
816 else if (!strcmp(str, "no-mount"))
817 debugfs_allow = DEBUGFS_ALLOW_API;
818 else if (!strcmp(str, "off"))
819 debugfs_allow = 0;
820 }
821
822 return 0;
823}
824early_param("debugfs", debugfs_kernel);
825static int __init debugfs_init(void)
826{
827 int retval;
828
829 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
830 return -EPERM;
831
832 retval = sysfs_create_mount_point(kernel_kobj, "debug");
833 if (retval)
834 return retval;
835
836 retval = register_filesystem(&debug_fs_type);
837 if (retval)
838 sysfs_remove_mount_point(kernel_kobj, "debug");
839 else
840 debugfs_registered = true;
841
842 return retval;
843}
844core_initcall(debugfs_init);