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