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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 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);
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