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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
31#define DEBUGFS_DEFAULT_MODE 0700
32
33static struct vfsmount *debugfs_mount;
34static int debugfs_mount_count;
35static bool debugfs_registered;
36
37static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
38 void *data, const struct file_operations *fops)
39
40{
41 struct inode *inode = new_inode(sb);
42
43 if (inode) {
44 inode->i_ino = get_next_ino();
45 inode->i_mode = mode;
46 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 switch (mode & S_IFMT) {
48 default:
49 init_special_inode(inode, mode, dev);
50 break;
51 case S_IFREG:
52 inode->i_fop = fops ? fops : &debugfs_file_operations;
53 inode->i_private = data;
54 break;
55 case S_IFLNK:
56 inode->i_op = &debugfs_link_operations;
57 inode->i_private = data;
58 break;
59 case S_IFDIR:
60 inode->i_op = &simple_dir_inode_operations;
61 inode->i_fop = &simple_dir_operations;
62
63 /* directory inodes start off with i_nlink == 2
64 * (for "." entry) */
65 inc_nlink(inode);
66 break;
67 }
68 }
69 return inode;
70}
71
72/* SMP-safe */
73static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
74 umode_t mode, dev_t dev, void *data,
75 const struct file_operations *fops)
76{
77 struct inode *inode;
78 int error = -EPERM;
79
80 if (dentry->d_inode)
81 return -EEXIST;
82
83 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
84 if (inode) {
85 d_instantiate(dentry, inode);
86 dget(dentry);
87 error = 0;
88 }
89 return error;
90}
91
92static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
93{
94 int res;
95
96 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
97 res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
98 if (!res) {
99 inc_nlink(dir);
100 fsnotify_mkdir(dir, dentry);
101 }
102 return res;
103}
104
105static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
106 void *data)
107{
108 mode = (mode & S_IALLUGO) | S_IFLNK;
109 return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
110}
111
112static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
113 void *data, const struct file_operations *fops)
114{
115 int res;
116
117 mode = (mode & S_IALLUGO) | S_IFREG;
118 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
119 if (!res)
120 fsnotify_create(dir, dentry);
121 return res;
122}
123
124static inline int debugfs_positive(struct dentry *dentry)
125{
126 return dentry->d_inode && !d_unhashed(dentry);
127}
128
129struct debugfs_mount_opts {
130 kuid_t uid;
131 kgid_t gid;
132 umode_t mode;
133};
134
135enum {
136 Opt_uid,
137 Opt_gid,
138 Opt_mode,
139 Opt_err
140};
141
142static const match_table_t tokens = {
143 {Opt_uid, "uid=%u"},
144 {Opt_gid, "gid=%u"},
145 {Opt_mode, "mode=%o"},
146 {Opt_err, NULL}
147};
148
149struct debugfs_fs_info {
150 struct debugfs_mount_opts mount_opts;
151};
152
153static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
154{
155 substring_t args[MAX_OPT_ARGS];
156 int option;
157 int token;
158 kuid_t uid;
159 kgid_t gid;
160 char *p;
161
162 opts->mode = DEBUGFS_DEFAULT_MODE;
163
164 while ((p = strsep(&data, ",")) != NULL) {
165 if (!*p)
166 continue;
167
168 token = match_token(p, tokens, args);
169 switch (token) {
170 case Opt_uid:
171 if (match_int(&args[0], &option))
172 return -EINVAL;
173 uid = make_kuid(current_user_ns(), option);
174 if (!uid_valid(uid))
175 return -EINVAL;
176 opts->uid = uid;
177 break;
178 case Opt_gid:
179 if (match_int(&args[0], &option))
180 return -EINVAL;
181 gid = make_kgid(current_user_ns(), option);
182 if (!gid_valid(gid))
183 return -EINVAL;
184 opts->gid = gid;
185 break;
186 case Opt_mode:
187 if (match_octal(&args[0], &option))
188 return -EINVAL;
189 opts->mode = option & S_IALLUGO;
190 break;
191 /*
192 * We might like to report bad mount options here;
193 * but traditionally debugfs has ignored all mount options
194 */
195 }
196 }
197
198 return 0;
199}
200
201static int debugfs_apply_options(struct super_block *sb)
202{
203 struct debugfs_fs_info *fsi = sb->s_fs_info;
204 struct inode *inode = sb->s_root->d_inode;
205 struct debugfs_mount_opts *opts = &fsi->mount_opts;
206
207 inode->i_mode &= ~S_IALLUGO;
208 inode->i_mode |= opts->mode;
209
210 inode->i_uid = opts->uid;
211 inode->i_gid = opts->gid;
212
213 return 0;
214}
215
216static int debugfs_remount(struct super_block *sb, int *flags, char *data)
217{
218 int err;
219 struct debugfs_fs_info *fsi = sb->s_fs_info;
220
221 sync_filesystem(sb);
222 err = debugfs_parse_options(data, &fsi->mount_opts);
223 if (err)
224 goto fail;
225
226 debugfs_apply_options(sb);
227
228fail:
229 return err;
230}
231
232static int debugfs_show_options(struct seq_file *m, struct dentry *root)
233{
234 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
235 struct debugfs_mount_opts *opts = &fsi->mount_opts;
236
237 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
238 seq_printf(m, ",uid=%u",
239 from_kuid_munged(&init_user_ns, opts->uid));
240 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
241 seq_printf(m, ",gid=%u",
242 from_kgid_munged(&init_user_ns, opts->gid));
243 if (opts->mode != DEBUGFS_DEFAULT_MODE)
244 seq_printf(m, ",mode=%o", opts->mode);
245
246 return 0;
247}
248
249static const struct super_operations debugfs_super_operations = {
250 .statfs = simple_statfs,
251 .remount_fs = debugfs_remount,
252 .show_options = debugfs_show_options,
253};
254
255static int debug_fill_super(struct super_block *sb, void *data, int silent)
256{
257 static struct tree_descr debug_files[] = {{""}};
258 struct debugfs_fs_info *fsi;
259 int err;
260
261 save_mount_options(sb, data);
262
263 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
264 sb->s_fs_info = fsi;
265 if (!fsi) {
266 err = -ENOMEM;
267 goto fail;
268 }
269
270 err = debugfs_parse_options(data, &fsi->mount_opts);
271 if (err)
272 goto fail;
273
274 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
275 if (err)
276 goto fail;
277
278 sb->s_op = &debugfs_super_operations;
279
280 debugfs_apply_options(sb);
281
282 return 0;
283
284fail:
285 kfree(fsi);
286 sb->s_fs_info = NULL;
287 return err;
288}
289
290static struct dentry *debug_mount(struct file_system_type *fs_type,
291 int flags, const char *dev_name,
292 void *data)
293{
294 return mount_single(fs_type, flags, data, debug_fill_super);
295}
296
297static struct file_system_type debug_fs_type = {
298 .owner = THIS_MODULE,
299 .name = "debugfs",
300 .mount = debug_mount,
301 .kill_sb = kill_litter_super,
302};
303MODULE_ALIAS_FS("debugfs");
304
305static struct dentry *__create_file(const char *name, umode_t mode,
306 struct dentry *parent, void *data,
307 const struct file_operations *fops)
308{
309 struct dentry *dentry = NULL;
310 int error;
311
312 pr_debug("debugfs: creating file '%s'\n",name);
313
314 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
315 &debugfs_mount_count);
316 if (error)
317 goto exit;
318
319 /* If the parent is not specified, we create it in the root.
320 * We need the root dentry to do this, which is in the super
321 * block. A pointer to that is in the struct vfsmount that we
322 * have around.
323 */
324 if (!parent)
325 parent = debugfs_mount->mnt_root;
326
327 mutex_lock(&parent->d_inode->i_mutex);
328 dentry = lookup_one_len(name, parent, strlen(name));
329 if (!IS_ERR(dentry)) {
330 switch (mode & S_IFMT) {
331 case S_IFDIR:
332 error = debugfs_mkdir(parent->d_inode, dentry, mode);
333
334 break;
335 case S_IFLNK:
336 error = debugfs_link(parent->d_inode, dentry, mode,
337 data);
338 break;
339 default:
340 error = debugfs_create(parent->d_inode, dentry, mode,
341 data, fops);
342 break;
343 }
344 dput(dentry);
345 } else
346 error = PTR_ERR(dentry);
347 mutex_unlock(&parent->d_inode->i_mutex);
348
349 if (error) {
350 dentry = NULL;
351 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
352 }
353exit:
354 return dentry;
355}
356
357/**
358 * debugfs_create_file - create a file in the debugfs filesystem
359 * @name: a pointer to a string containing the name of the file to create.
360 * @mode: the permission that the file should have.
361 * @parent: a pointer to the parent dentry for this file. This should be a
362 * directory dentry if set. If this parameter is NULL, then the
363 * file will be created in the root of the debugfs filesystem.
364 * @data: a pointer to something that the caller will want to get to later
365 * on. The inode.i_private pointer will point to this value on
366 * the open() call.
367 * @fops: a pointer to a struct file_operations that should be used for
368 * this file.
369 *
370 * This is the basic "create a file" function for debugfs. It allows for a
371 * wide range of flexibility in creating a file, or a directory (if you want
372 * to create a directory, the debugfs_create_dir() function is
373 * recommended to be used instead.)
374 *
375 * This function will return a pointer to a dentry if it succeeds. This
376 * pointer must be passed to the debugfs_remove() function when the file is
377 * to be removed (no automatic cleanup happens if your module is unloaded,
378 * you are responsible here.) If an error occurs, %NULL will be returned.
379 *
380 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
381 * returned.
382 */
383struct dentry *debugfs_create_file(const char *name, umode_t mode,
384 struct dentry *parent, void *data,
385 const struct file_operations *fops)
386{
387 switch (mode & S_IFMT) {
388 case S_IFREG:
389 case 0:
390 break;
391 default:
392 BUG();
393 }
394
395 return __create_file(name, mode, parent, data, fops);
396}
397EXPORT_SYMBOL_GPL(debugfs_create_file);
398
399/**
400 * debugfs_create_dir - create a directory in the debugfs filesystem
401 * @name: a pointer to a string containing the name of the directory to
402 * create.
403 * @parent: a pointer to the parent dentry for this file. This should be a
404 * directory dentry if set. If this parameter is NULL, then the
405 * directory will be created in the root of the debugfs filesystem.
406 *
407 * This function creates a directory in debugfs with the given name.
408 *
409 * This function will return a pointer to a dentry if it succeeds. This
410 * pointer must be passed to the debugfs_remove() function when the file is
411 * to be removed (no automatic cleanup happens if your module is unloaded,
412 * you are responsible here.) If an error occurs, %NULL will be returned.
413 *
414 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
415 * returned.
416 */
417struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
418{
419 return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
420 parent, NULL, NULL);
421}
422EXPORT_SYMBOL_GPL(debugfs_create_dir);
423
424/**
425 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
426 * @name: a pointer to a string containing the name of the symbolic link to
427 * create.
428 * @parent: a pointer to the parent dentry for this symbolic link. This
429 * should be a directory dentry if set. If this parameter is NULL,
430 * then the symbolic link will be created in the root of the debugfs
431 * filesystem.
432 * @target: a pointer to a string containing the path to the target of the
433 * symbolic link.
434 *
435 * This function creates a symbolic link with the given name in debugfs that
436 * links to the given target path.
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 symbolic
440 * link is to be removed (no automatic cleanup happens if your module is
441 * unloaded, you are responsible here.) If an error occurs, %NULL 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_symlink(const char *name, struct dentry *parent,
448 const char *target)
449{
450 struct dentry *result;
451 char *link;
452
453 link = kstrdup(target, GFP_KERNEL);
454 if (!link)
455 return NULL;
456
457 result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
458 if (!result)
459 kfree(link);
460 return result;
461}
462EXPORT_SYMBOL_GPL(debugfs_create_symlink);
463
464static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
465{
466 int ret = 0;
467
468 if (debugfs_positive(dentry)) {
469 if (dentry->d_inode) {
470 dget(dentry);
471 switch (dentry->d_inode->i_mode & S_IFMT) {
472 case S_IFDIR:
473 ret = simple_rmdir(parent->d_inode, dentry);
474 break;
475 case S_IFLNK:
476 kfree(dentry->d_inode->i_private);
477 /* fall through */
478 default:
479 simple_unlink(parent->d_inode, dentry);
480 break;
481 }
482 if (!ret)
483 d_delete(dentry);
484 dput(dentry);
485 }
486 }
487 return ret;
488}
489
490/**
491 * debugfs_remove - removes a file or directory from the debugfs filesystem
492 * @dentry: a pointer to a the dentry of the file or directory to be
493 * removed.
494 *
495 * This function removes a file or directory in debugfs that was previously
496 * created with a call to another debugfs function (like
497 * debugfs_create_file() or variants thereof.)
498 *
499 * This function is required to be called in order for the file to be
500 * removed, no automatic cleanup of files will happen when a module is
501 * removed, you are responsible here.
502 */
503void debugfs_remove(struct dentry *dentry)
504{
505 struct dentry *parent;
506 int ret;
507
508 if (IS_ERR_OR_NULL(dentry))
509 return;
510
511 parent = dentry->d_parent;
512 if (!parent || !parent->d_inode)
513 return;
514
515 mutex_lock(&parent->d_inode->i_mutex);
516 ret = __debugfs_remove(dentry, parent);
517 mutex_unlock(&parent->d_inode->i_mutex);
518 if (!ret)
519 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
520}
521EXPORT_SYMBOL_GPL(debugfs_remove);
522
523/**
524 * debugfs_remove_recursive - recursively removes a directory
525 * @dentry: a pointer to a the dentry of the directory to be removed.
526 *
527 * This function recursively removes a directory tree in debugfs that
528 * was previously created with a call to another debugfs function
529 * (like debugfs_create_file() or variants thereof.)
530 *
531 * This function is required to be called in order for the file to be
532 * removed, no automatic cleanup of files will happen when a module is
533 * removed, you are responsible here.
534 */
535void debugfs_remove_recursive(struct dentry *dentry)
536{
537 struct dentry *child, *next, *parent;
538
539 if (IS_ERR_OR_NULL(dentry))
540 return;
541
542 parent = dentry->d_parent;
543 if (!parent || !parent->d_inode)
544 return;
545
546 parent = dentry;
547 down:
548 mutex_lock(&parent->d_inode->i_mutex);
549 list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
550 if (!debugfs_positive(child))
551 continue;
552
553 /* perhaps simple_empty(child) makes more sense */
554 if (!list_empty(&child->d_subdirs)) {
555 mutex_unlock(&parent->d_inode->i_mutex);
556 parent = child;
557 goto down;
558 }
559 up:
560 if (!__debugfs_remove(child, parent))
561 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
562 }
563
564 mutex_unlock(&parent->d_inode->i_mutex);
565 child = parent;
566 parent = parent->d_parent;
567 mutex_lock(&parent->d_inode->i_mutex);
568
569 if (child != dentry) {
570 next = list_next_entry(child, d_u.d_child);
571 goto up;
572 }
573
574 if (!__debugfs_remove(child, parent))
575 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
576 mutex_unlock(&parent->d_inode->i_mutex);
577}
578EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
579
580/**
581 * debugfs_rename - rename a file/directory in the debugfs filesystem
582 * @old_dir: a pointer to the parent dentry for the renamed object. This
583 * should be a directory dentry.
584 * @old_dentry: dentry of an object to be renamed.
585 * @new_dir: a pointer to the parent dentry where the object should be
586 * moved. This should be a directory dentry.
587 * @new_name: a pointer to a string containing the target name.
588 *
589 * This function renames a file/directory in debugfs. The target must not
590 * exist for rename to succeed.
591 *
592 * This function will return a pointer to old_dentry (which is updated to
593 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
594 * returned.
595 *
596 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
597 * returned.
598 */
599struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
600 struct dentry *new_dir, const char *new_name)
601{
602 int error;
603 struct dentry *dentry = NULL, *trap;
604 const char *old_name;
605
606 trap = lock_rename(new_dir, old_dir);
607 /* Source or destination directories don't exist? */
608 if (!old_dir->d_inode || !new_dir->d_inode)
609 goto exit;
610 /* Source does not exist, cyclic rename, or mountpoint? */
611 if (!old_dentry->d_inode || old_dentry == trap ||
612 d_mountpoint(old_dentry))
613 goto exit;
614 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
615 /* Lookup failed, cyclic rename or target exists? */
616 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
617 goto exit;
618
619 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
620
621 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
622 dentry);
623 if (error) {
624 fsnotify_oldname_free(old_name);
625 goto exit;
626 }
627 d_move(old_dentry, dentry);
628 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
629 S_ISDIR(old_dentry->d_inode->i_mode),
630 NULL, old_dentry);
631 fsnotify_oldname_free(old_name);
632 unlock_rename(new_dir, old_dir);
633 dput(dentry);
634 return old_dentry;
635exit:
636 if (dentry && !IS_ERR(dentry))
637 dput(dentry);
638 unlock_rename(new_dir, old_dir);
639 return NULL;
640}
641EXPORT_SYMBOL_GPL(debugfs_rename);
642
643/**
644 * debugfs_initialized - Tells whether debugfs has been registered
645 */
646bool debugfs_initialized(void)
647{
648 return debugfs_registered;
649}
650EXPORT_SYMBOL_GPL(debugfs_initialized);
651
652
653static struct kobject *debug_kobj;
654
655static int __init debugfs_init(void)
656{
657 int retval;
658
659 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
660 if (!debug_kobj)
661 return -EINVAL;
662
663 retval = register_filesystem(&debug_fs_type);
664 if (retval)
665 kobject_put(debug_kobj);
666 else
667 debugfs_registered = true;
668
669 return retval;
670}
671core_initcall(debugfs_init);
672
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 mnt_idmap *idmap,
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(&nop_mnt_idmap, 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 simple_inode_init_ts(inode);
76 }
77 return inode;
78}
79
80struct debugfs_mount_opts {
81 kuid_t uid;
82 kgid_t gid;
83 umode_t mode;
84 /* Opt_* bitfield. */
85 unsigned int opts;
86};
87
88enum {
89 Opt_uid,
90 Opt_gid,
91 Opt_mode,
92 Opt_err
93};
94
95static const match_table_t tokens = {
96 {Opt_uid, "uid=%u"},
97 {Opt_gid, "gid=%u"},
98 {Opt_mode, "mode=%o"},
99 {Opt_err, NULL}
100};
101
102struct debugfs_fs_info {
103 struct debugfs_mount_opts mount_opts;
104};
105
106static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
107{
108 substring_t args[MAX_OPT_ARGS];
109 int option;
110 int token;
111 kuid_t uid;
112 kgid_t gid;
113 char *p;
114
115 opts->opts = 0;
116 opts->mode = DEBUGFS_DEFAULT_MODE;
117
118 while ((p = strsep(&data, ",")) != NULL) {
119 if (!*p)
120 continue;
121
122 token = match_token(p, tokens, args);
123 switch (token) {
124 case Opt_uid:
125 if (match_int(&args[0], &option))
126 return -EINVAL;
127 uid = make_kuid(current_user_ns(), option);
128 if (!uid_valid(uid))
129 return -EINVAL;
130 opts->uid = uid;
131 break;
132 case Opt_gid:
133 if (match_int(&args[0], &option))
134 return -EINVAL;
135 gid = make_kgid(current_user_ns(), option);
136 if (!gid_valid(gid))
137 return -EINVAL;
138 opts->gid = gid;
139 break;
140 case Opt_mode:
141 if (match_octal(&args[0], &option))
142 return -EINVAL;
143 opts->mode = option & S_IALLUGO;
144 break;
145 /*
146 * We might like to report bad mount options here;
147 * but traditionally debugfs has ignored all mount options
148 */
149 }
150
151 opts->opts |= BIT(token);
152 }
153
154 return 0;
155}
156
157static void _debugfs_apply_options(struct super_block *sb, bool remount)
158{
159 struct debugfs_fs_info *fsi = sb->s_fs_info;
160 struct inode *inode = d_inode(sb->s_root);
161 struct debugfs_mount_opts *opts = &fsi->mount_opts;
162
163 /*
164 * On remount, only reset mode/uid/gid if they were provided as mount
165 * options.
166 */
167
168 if (!remount || opts->opts & BIT(Opt_mode)) {
169 inode->i_mode &= ~S_IALLUGO;
170 inode->i_mode |= opts->mode;
171 }
172
173 if (!remount || opts->opts & BIT(Opt_uid))
174 inode->i_uid = opts->uid;
175
176 if (!remount || opts->opts & BIT(Opt_gid))
177 inode->i_gid = opts->gid;
178}
179
180static void debugfs_apply_options(struct super_block *sb)
181{
182 _debugfs_apply_options(sb, false);
183}
184
185static void debugfs_apply_options_remount(struct super_block *sb)
186{
187 _debugfs_apply_options(sb, true);
188}
189
190static int debugfs_remount(struct super_block *sb, int *flags, char *data)
191{
192 int err;
193 struct debugfs_fs_info *fsi = sb->s_fs_info;
194
195 sync_filesystem(sb);
196 err = debugfs_parse_options(data, &fsi->mount_opts);
197 if (err)
198 goto fail;
199
200 debugfs_apply_options_remount(sb);
201
202fail:
203 return err;
204}
205
206static int debugfs_show_options(struct seq_file *m, struct dentry *root)
207{
208 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
209 struct debugfs_mount_opts *opts = &fsi->mount_opts;
210
211 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
212 seq_printf(m, ",uid=%u",
213 from_kuid_munged(&init_user_ns, opts->uid));
214 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
215 seq_printf(m, ",gid=%u",
216 from_kgid_munged(&init_user_ns, opts->gid));
217 if (opts->mode != DEBUGFS_DEFAULT_MODE)
218 seq_printf(m, ",mode=%o", opts->mode);
219
220 return 0;
221}
222
223static void debugfs_free_inode(struct inode *inode)
224{
225 if (S_ISLNK(inode->i_mode))
226 kfree(inode->i_link);
227 free_inode_nonrcu(inode);
228}
229
230static const struct super_operations debugfs_super_operations = {
231 .statfs = simple_statfs,
232 .remount_fs = debugfs_remount,
233 .show_options = debugfs_show_options,
234 .free_inode = debugfs_free_inode,
235};
236
237static void debugfs_release_dentry(struct dentry *dentry)
238{
239 struct debugfs_fsdata *fsd = dentry->d_fsdata;
240
241 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
242 return;
243
244 /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
245 if (fsd && fsd->real_fops) {
246 WARN_ON(!list_empty(&fsd->cancellations));
247 mutex_destroy(&fsd->cancellations_mtx);
248 }
249
250 kfree(fsd);
251}
252
253static struct vfsmount *debugfs_automount(struct path *path)
254{
255 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
256
257 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
258}
259
260static const struct dentry_operations debugfs_dops = {
261 .d_delete = always_delete_dentry,
262 .d_release = debugfs_release_dentry,
263 .d_automount = debugfs_automount,
264};
265
266static int debug_fill_super(struct super_block *sb, void *data, int silent)
267{
268 static const struct tree_descr debug_files[] = {{""}};
269 struct debugfs_fs_info *fsi;
270 int err;
271
272 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
273 sb->s_fs_info = fsi;
274 if (!fsi) {
275 err = -ENOMEM;
276 goto fail;
277 }
278
279 err = debugfs_parse_options(data, &fsi->mount_opts);
280 if (err)
281 goto fail;
282
283 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
284 if (err)
285 goto fail;
286
287 sb->s_op = &debugfs_super_operations;
288 sb->s_d_op = &debugfs_dops;
289
290 debugfs_apply_options(sb);
291
292 return 0;
293
294fail:
295 kfree(fsi);
296 sb->s_fs_info = NULL;
297 return err;
298}
299
300static struct dentry *debug_mount(struct file_system_type *fs_type,
301 int flags, const char *dev_name,
302 void *data)
303{
304 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
305 return ERR_PTR(-EPERM);
306
307 return mount_single(fs_type, flags, data, debug_fill_super);
308}
309
310static struct file_system_type debug_fs_type = {
311 .owner = THIS_MODULE,
312 .name = "debugfs",
313 .mount = debug_mount,
314 .kill_sb = kill_litter_super,
315};
316MODULE_ALIAS_FS("debugfs");
317
318/**
319 * debugfs_lookup() - look up an existing debugfs file
320 * @name: a pointer to a string containing the name of the file to look up.
321 * @parent: a pointer to the parent dentry of the file.
322 *
323 * This function will return a pointer to a dentry if it succeeds. If the file
324 * doesn't exist or an error occurs, %NULL will be returned. The returned
325 * dentry must be passed to dput() when it is no longer needed.
326 *
327 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
328 * returned.
329 */
330struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
331{
332 struct dentry *dentry;
333
334 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
335 return NULL;
336
337 if (!parent)
338 parent = debugfs_mount->mnt_root;
339
340 dentry = lookup_positive_unlocked(name, parent, strlen(name));
341 if (IS_ERR(dentry))
342 return NULL;
343 return dentry;
344}
345EXPORT_SYMBOL_GPL(debugfs_lookup);
346
347static struct dentry *start_creating(const char *name, struct dentry *parent)
348{
349 struct dentry *dentry;
350 int error;
351
352 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
353 return ERR_PTR(-EPERM);
354
355 if (!debugfs_initialized())
356 return ERR_PTR(-ENOENT);
357
358 pr_debug("creating file '%s'\n", name);
359
360 if (IS_ERR(parent))
361 return parent;
362
363 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
364 &debugfs_mount_count);
365 if (error) {
366 pr_err("Unable to pin filesystem for file '%s'\n", name);
367 return ERR_PTR(error);
368 }
369
370 /* If the parent is not specified, we create it in the root.
371 * We need the root dentry to do this, which is in the super
372 * block. A pointer to that is in the struct vfsmount that we
373 * have around.
374 */
375 if (!parent)
376 parent = debugfs_mount->mnt_root;
377
378 inode_lock(d_inode(parent));
379 if (unlikely(IS_DEADDIR(d_inode(parent))))
380 dentry = ERR_PTR(-ENOENT);
381 else
382 dentry = lookup_one_len(name, parent, strlen(name));
383 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
384 if (d_is_dir(dentry))
385 pr_err("Directory '%s' with parent '%s' already present!\n",
386 name, parent->d_name.name);
387 else
388 pr_err("File '%s' in directory '%s' already present!\n",
389 name, parent->d_name.name);
390 dput(dentry);
391 dentry = ERR_PTR(-EEXIST);
392 }
393
394 if (IS_ERR(dentry)) {
395 inode_unlock(d_inode(parent));
396 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
397 }
398
399 return dentry;
400}
401
402static struct dentry *failed_creating(struct dentry *dentry)
403{
404 inode_unlock(d_inode(dentry->d_parent));
405 dput(dentry);
406 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
407 return ERR_PTR(-ENOMEM);
408}
409
410static struct dentry *end_creating(struct dentry *dentry)
411{
412 inode_unlock(d_inode(dentry->d_parent));
413 return dentry;
414}
415
416static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
417 struct dentry *parent, void *data,
418 const struct file_operations *proxy_fops,
419 const struct file_operations *real_fops)
420{
421 struct dentry *dentry;
422 struct inode *inode;
423
424 if (!(mode & S_IFMT))
425 mode |= S_IFREG;
426 BUG_ON(!S_ISREG(mode));
427 dentry = start_creating(name, parent);
428
429 if (IS_ERR(dentry))
430 return dentry;
431
432 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
433 failed_creating(dentry);
434 return ERR_PTR(-EPERM);
435 }
436
437 inode = debugfs_get_inode(dentry->d_sb);
438 if (unlikely(!inode)) {
439 pr_err("out of free dentries, can not create file '%s'\n",
440 name);
441 return failed_creating(dentry);
442 }
443
444 inode->i_mode = mode;
445 inode->i_private = data;
446
447 inode->i_op = &debugfs_file_inode_operations;
448 inode->i_fop = proxy_fops;
449 dentry->d_fsdata = (void *)((unsigned long)real_fops |
450 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
451
452 d_instantiate(dentry, inode);
453 fsnotify_create(d_inode(dentry->d_parent), dentry);
454 return end_creating(dentry);
455}
456
457/**
458 * debugfs_create_file - create a file in the debugfs filesystem
459 * @name: a pointer to a string containing the name of the file to create.
460 * @mode: the permission that the file should have.
461 * @parent: a pointer to the parent dentry for this file. This should be a
462 * directory dentry if set. If this parameter is NULL, then the
463 * file will be created in the root of the debugfs filesystem.
464 * @data: a pointer to something that the caller will want to get to later
465 * on. The inode.i_private pointer will point to this value on
466 * the open() call.
467 * @fops: a pointer to a struct file_operations that should be used for
468 * this file.
469 *
470 * This is the basic "create a file" function for debugfs. It allows for a
471 * wide range of flexibility in creating a file, or a directory (if you want
472 * to create a directory, the debugfs_create_dir() function is
473 * recommended to be used instead.)
474 *
475 * This function will return a pointer to a dentry if it succeeds. This
476 * pointer must be passed to the debugfs_remove() function when the file is
477 * to be removed (no automatic cleanup happens if your module is unloaded,
478 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
479 * returned.
480 *
481 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
482 * returned.
483 *
484 * NOTE: it's expected that most callers should _ignore_ the errors returned
485 * by this function. Other debugfs functions handle the fact that the "dentry"
486 * passed to them could be an error and they don't crash in that case.
487 * Drivers should generally work fine even if debugfs fails to init anyway.
488 */
489struct dentry *debugfs_create_file(const char *name, umode_t mode,
490 struct dentry *parent, void *data,
491 const struct file_operations *fops)
492{
493
494 return __debugfs_create_file(name, mode, parent, data,
495 fops ? &debugfs_full_proxy_file_operations :
496 &debugfs_noop_file_operations,
497 fops);
498}
499EXPORT_SYMBOL_GPL(debugfs_create_file);
500
501/**
502 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
503 * @name: a pointer to a string containing the name of the file to create.
504 * @mode: the permission that the file should have.
505 * @parent: a pointer to the parent dentry for this file. This should be a
506 * directory dentry if set. If this parameter is NULL, then the
507 * file will be created in the root of the debugfs filesystem.
508 * @data: a pointer to something that the caller will want to get to later
509 * on. The inode.i_private pointer will point to this value on
510 * the open() call.
511 * @fops: a pointer to a struct file_operations that should be used for
512 * this file.
513 *
514 * debugfs_create_file_unsafe() is completely analogous to
515 * debugfs_create_file(), the only difference being that the fops
516 * handed it will not get protected against file removals by the
517 * debugfs core.
518 *
519 * It is your responsibility to protect your struct file_operation
520 * methods against file removals by means of debugfs_file_get()
521 * and debugfs_file_put(). ->open() is still protected by
522 * debugfs though.
523 *
524 * Any struct file_operations defined by means of
525 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
526 * thus, may be used here.
527 */
528struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
529 struct dentry *parent, void *data,
530 const struct file_operations *fops)
531{
532
533 return __debugfs_create_file(name, mode, parent, data,
534 fops ? &debugfs_open_proxy_file_operations :
535 &debugfs_noop_file_operations,
536 fops);
537}
538EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
539
540/**
541 * debugfs_create_file_size - create a file in the debugfs filesystem
542 * @name: a pointer to a string containing the name of the file to create.
543 * @mode: the permission that the file should have.
544 * @parent: a pointer to the parent dentry for this file. This should be a
545 * directory dentry if set. If this parameter is NULL, then the
546 * file will be created in the root of the debugfs filesystem.
547 * @data: a pointer to something that the caller will want to get to later
548 * on. The inode.i_private pointer will point to this value on
549 * the open() call.
550 * @fops: a pointer to a struct file_operations that should be used for
551 * this file.
552 * @file_size: initial file size
553 *
554 * This is the basic "create a file" function for debugfs. It allows for a
555 * wide range of flexibility in creating a file, or a directory (if you want
556 * to create a directory, the debugfs_create_dir() function is
557 * recommended to be used instead.)
558 */
559void debugfs_create_file_size(const char *name, umode_t mode,
560 struct dentry *parent, void *data,
561 const struct file_operations *fops,
562 loff_t file_size)
563{
564 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
565
566 if (!IS_ERR(de))
567 d_inode(de)->i_size = file_size;
568}
569EXPORT_SYMBOL_GPL(debugfs_create_file_size);
570
571/**
572 * debugfs_create_dir - create a directory in the debugfs filesystem
573 * @name: a pointer to a string containing the name of the directory to
574 * create.
575 * @parent: a pointer to the parent dentry for this file. This should be a
576 * directory dentry if set. If this parameter is NULL, then the
577 * directory will be created in the root of the debugfs filesystem.
578 *
579 * This function creates a directory in debugfs with the given name.
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 file is
583 * to be removed (no automatic cleanup happens if your module is unloaded,
584 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
585 * returned.
586 *
587 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
588 * returned.
589 *
590 * NOTE: it's expected that most callers should _ignore_ the errors returned
591 * by this function. Other debugfs functions handle the fact that the "dentry"
592 * passed to them could be an error and they don't crash in that case.
593 * Drivers should generally work fine even if debugfs fails to init anyway.
594 */
595struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
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 directory '%s'\n",
611 name);
612 return failed_creating(dentry);
613 }
614
615 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
616 inode->i_op = &debugfs_dir_inode_operations;
617 inode->i_fop = &simple_dir_operations;
618
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_GPL(debugfs_create_dir);
627
628/**
629 * debugfs_create_automount - create automount point in the debugfs filesystem
630 * @name: a pointer to a string containing the name of the file to create.
631 * @parent: a pointer to the parent dentry for this file. This should be a
632 * directory dentry if set. If this parameter is NULL, then the
633 * file will be created in the root of the debugfs filesystem.
634 * @f: function to be called when pathname resolution steps on that one.
635 * @data: opaque argument to pass to f().
636 *
637 * @f should return what ->d_automount() would.
638 */
639struct dentry *debugfs_create_automount(const char *name,
640 struct dentry *parent,
641 debugfs_automount_t f,
642 void *data)
643{
644 struct dentry *dentry = start_creating(name, parent);
645 struct debugfs_fsdata *fsd;
646 struct inode *inode;
647
648 if (IS_ERR(dentry))
649 return dentry;
650
651 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
652 if (!fsd) {
653 failed_creating(dentry);
654 return ERR_PTR(-ENOMEM);
655 }
656
657 fsd->automount = f;
658
659 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
660 failed_creating(dentry);
661 kfree(fsd);
662 return ERR_PTR(-EPERM);
663 }
664
665 inode = debugfs_get_inode(dentry->d_sb);
666 if (unlikely(!inode)) {
667 pr_err("out of free dentries, can not create automount '%s'\n",
668 name);
669 kfree(fsd);
670 return failed_creating(dentry);
671 }
672
673 make_empty_dir_inode(inode);
674 inode->i_flags |= S_AUTOMOUNT;
675 inode->i_private = data;
676 dentry->d_fsdata = fsd;
677 /* directory inodes start off with i_nlink == 2 (for "." entry) */
678 inc_nlink(inode);
679 d_instantiate(dentry, inode);
680 inc_nlink(d_inode(dentry->d_parent));
681 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
682 return end_creating(dentry);
683}
684EXPORT_SYMBOL(debugfs_create_automount);
685
686/**
687 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
688 * @name: a pointer to a string containing the name of the symbolic link to
689 * create.
690 * @parent: a pointer to the parent dentry for this symbolic link. This
691 * should be a directory dentry if set. If this parameter is NULL,
692 * then the symbolic link will be created in the root of the debugfs
693 * filesystem.
694 * @target: a pointer to a string containing the path to the target of the
695 * symbolic link.
696 *
697 * This function creates a symbolic link with the given name in debugfs that
698 * links to the given target path.
699 *
700 * This function will return a pointer to a dentry if it succeeds. This
701 * pointer must be passed to the debugfs_remove() function when the symbolic
702 * link is to be removed (no automatic cleanup happens if your module is
703 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
704 * will be returned.
705 *
706 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
707 * returned.
708 */
709struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
710 const char *target)
711{
712 struct dentry *dentry;
713 struct inode *inode;
714 char *link = kstrdup(target, GFP_KERNEL);
715 if (!link)
716 return ERR_PTR(-ENOMEM);
717
718 dentry = start_creating(name, parent);
719 if (IS_ERR(dentry)) {
720 kfree(link);
721 return dentry;
722 }
723
724 inode = debugfs_get_inode(dentry->d_sb);
725 if (unlikely(!inode)) {
726 pr_err("out of free dentries, can not create symlink '%s'\n",
727 name);
728 kfree(link);
729 return failed_creating(dentry);
730 }
731 inode->i_mode = S_IFLNK | S_IRWXUGO;
732 inode->i_op = &debugfs_symlink_inode_operations;
733 inode->i_link = link;
734 d_instantiate(dentry, inode);
735 return end_creating(dentry);
736}
737EXPORT_SYMBOL_GPL(debugfs_create_symlink);
738
739static void __debugfs_file_removed(struct dentry *dentry)
740{
741 struct debugfs_fsdata *fsd;
742
743 /*
744 * Paired with the closing smp_mb() implied by a successful
745 * cmpxchg() in debugfs_file_get(): either
746 * debugfs_file_get() must see a dead dentry or we must see a
747 * debugfs_fsdata instance at ->d_fsdata here (or both).
748 */
749 smp_mb();
750 fsd = READ_ONCE(dentry->d_fsdata);
751 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
752 return;
753
754 /* if we hit zero, just wait for all to finish */
755 if (!refcount_dec_and_test(&fsd->active_users)) {
756 wait_for_completion(&fsd->active_users_drained);
757 return;
758 }
759
760 /* if we didn't hit zero, try to cancel any we can */
761 while (refcount_read(&fsd->active_users)) {
762 struct debugfs_cancellation *c;
763
764 /*
765 * Lock the cancellations. Note that the cancellations
766 * structs are meant to be on the stack, so we need to
767 * ensure we either use them here or don't touch them,
768 * and debugfs_leave_cancellation() will wait for this
769 * to be finished processing before exiting one. It may
770 * of course win and remove the cancellation, but then
771 * chances are we never even got into this bit, we only
772 * do if the refcount isn't zero already.
773 */
774 mutex_lock(&fsd->cancellations_mtx);
775 while ((c = list_first_entry_or_null(&fsd->cancellations,
776 typeof(*c), list))) {
777 list_del_init(&c->list);
778 c->cancel(dentry, c->cancel_data);
779 }
780 mutex_unlock(&fsd->cancellations_mtx);
781
782 wait_for_completion(&fsd->active_users_drained);
783 }
784}
785
786static void remove_one(struct dentry *victim)
787{
788 if (d_is_reg(victim))
789 __debugfs_file_removed(victim);
790 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
791}
792
793/**
794 * debugfs_remove - recursively removes a directory
795 * @dentry: a pointer to a the dentry of the directory to be removed. If this
796 * parameter is NULL or an error value, nothing will be done.
797 *
798 * This function recursively removes a directory tree in debugfs that
799 * was previously created with a call to another debugfs function
800 * (like debugfs_create_file() or variants thereof.)
801 *
802 * This function is required to be called in order for the file to be
803 * removed, no automatic cleanup of files will happen when a module is
804 * removed, you are responsible here.
805 */
806void debugfs_remove(struct dentry *dentry)
807{
808 if (IS_ERR_OR_NULL(dentry))
809 return;
810
811 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
812 simple_recursive_removal(dentry, remove_one);
813 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
814}
815EXPORT_SYMBOL_GPL(debugfs_remove);
816
817/**
818 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
819 * @name: a pointer to a string containing the name of the item to look up.
820 * @parent: a pointer to the parent dentry of the item.
821 *
822 * This is the equlivant of doing something like
823 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
824 * handled for the directory being looked up.
825 */
826void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
827{
828 struct dentry *dentry;
829
830 dentry = debugfs_lookup(name, parent);
831 if (!dentry)
832 return;
833
834 debugfs_remove(dentry);
835 dput(dentry);
836}
837EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
838
839/**
840 * debugfs_rename - rename a file/directory in the debugfs filesystem
841 * @old_dir: a pointer to the parent dentry for the renamed object. This
842 * should be a directory dentry.
843 * @old_dentry: dentry of an object to be renamed.
844 * @new_dir: a pointer to the parent dentry where the object should be
845 * moved. This should be a directory dentry.
846 * @new_name: a pointer to a string containing the target name.
847 *
848 * This function renames a file/directory in debugfs. The target must not
849 * exist for rename to succeed.
850 *
851 * This function will return a pointer to old_dentry (which is updated to
852 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
853 * will be returned.
854 *
855 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
856 * returned.
857 */
858struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
859 struct dentry *new_dir, const char *new_name)
860{
861 int error;
862 struct dentry *dentry = NULL, *trap;
863 struct name_snapshot old_name;
864
865 if (IS_ERR(old_dir))
866 return old_dir;
867 if (IS_ERR(new_dir))
868 return new_dir;
869 if (IS_ERR_OR_NULL(old_dentry))
870 return old_dentry;
871
872 trap = lock_rename(new_dir, old_dir);
873 /* Source or destination directories don't exist? */
874 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
875 goto exit;
876 /* Source does not exist, cyclic rename, or mountpoint? */
877 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
878 d_mountpoint(old_dentry))
879 goto exit;
880 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
881 /* Lookup failed, cyclic rename or target exists? */
882 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
883 goto exit;
884
885 take_dentry_name_snapshot(&old_name, old_dentry);
886
887 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
888 d_inode(new_dir), dentry, 0);
889 if (error) {
890 release_dentry_name_snapshot(&old_name);
891 goto exit;
892 }
893 d_move(old_dentry, dentry);
894 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
895 d_is_dir(old_dentry),
896 NULL, old_dentry);
897 release_dentry_name_snapshot(&old_name);
898 unlock_rename(new_dir, old_dir);
899 dput(dentry);
900 return old_dentry;
901exit:
902 if (dentry && !IS_ERR(dentry))
903 dput(dentry);
904 unlock_rename(new_dir, old_dir);
905 if (IS_ERR(dentry))
906 return dentry;
907 return ERR_PTR(-EINVAL);
908}
909EXPORT_SYMBOL_GPL(debugfs_rename);
910
911/**
912 * debugfs_initialized - Tells whether debugfs has been registered
913 */
914bool debugfs_initialized(void)
915{
916 return debugfs_registered;
917}
918EXPORT_SYMBOL_GPL(debugfs_initialized);
919
920static int __init debugfs_kernel(char *str)
921{
922 if (str) {
923 if (!strcmp(str, "on"))
924 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
925 else if (!strcmp(str, "no-mount"))
926 debugfs_allow = DEBUGFS_ALLOW_API;
927 else if (!strcmp(str, "off"))
928 debugfs_allow = 0;
929 }
930
931 return 0;
932}
933early_param("debugfs", debugfs_kernel);
934static int __init debugfs_init(void)
935{
936 int retval;
937
938 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
939 return -EPERM;
940
941 retval = sysfs_create_mount_point(kernel_kobj, "debug");
942 if (retval)
943 return retval;
944
945 retval = register_filesystem(&debug_fs_type);
946 if (retval)
947 sysfs_remove_mount_point(kernel_kobj, "debug");
948 else
949 debugfs_registered = true;
950
951 return retval;
952}
953core_initcall(debugfs_init);