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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/fs_context.h>
18#include <linux/fs_parser.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/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_fs_info {
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_source,
93};
94
95static const struct fs_parameter_spec debugfs_param_specs[] = {
96 fsparam_gid ("gid", Opt_gid),
97 fsparam_u32oct ("mode", Opt_mode),
98 fsparam_uid ("uid", Opt_uid),
99 fsparam_string ("source", Opt_source),
100 {}
101};
102
103static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
104{
105 struct debugfs_fs_info *opts = fc->s_fs_info;
106 struct fs_parse_result result;
107 int opt;
108
109 opt = fs_parse(fc, debugfs_param_specs, param, &result);
110 if (opt < 0) {
111 /*
112 * We might like to report bad mount options here; but
113 * traditionally debugfs has ignored all mount options
114 */
115 if (opt == -ENOPARAM)
116 return 0;
117
118 return opt;
119 }
120
121 switch (opt) {
122 case Opt_uid:
123 opts->uid = result.uid;
124 break;
125 case Opt_gid:
126 opts->gid = result.gid;
127 break;
128 case Opt_mode:
129 opts->mode = result.uint_32 & S_IALLUGO;
130 break;
131 case Opt_source:
132 if (fc->source)
133 return invalfc(fc, "Multiple sources specified");
134 fc->source = param->string;
135 param->string = NULL;
136 break;
137 /*
138 * We might like to report bad mount options here;
139 * but traditionally debugfs has ignored all mount options
140 */
141 }
142
143 opts->opts |= BIT(opt);
144
145 return 0;
146}
147
148static void _debugfs_apply_options(struct super_block *sb, bool remount)
149{
150 struct debugfs_fs_info *fsi = sb->s_fs_info;
151 struct inode *inode = d_inode(sb->s_root);
152
153 /*
154 * On remount, only reset mode/uid/gid if they were provided as mount
155 * options.
156 */
157
158 if (!remount || fsi->opts & BIT(Opt_mode)) {
159 inode->i_mode &= ~S_IALLUGO;
160 inode->i_mode |= fsi->mode;
161 }
162
163 if (!remount || fsi->opts & BIT(Opt_uid))
164 inode->i_uid = fsi->uid;
165
166 if (!remount || fsi->opts & BIT(Opt_gid))
167 inode->i_gid = fsi->gid;
168}
169
170static void debugfs_apply_options(struct super_block *sb)
171{
172 _debugfs_apply_options(sb, false);
173}
174
175static void debugfs_apply_options_remount(struct super_block *sb)
176{
177 _debugfs_apply_options(sb, true);
178}
179
180static int debugfs_reconfigure(struct fs_context *fc)
181{
182 struct super_block *sb = fc->root->d_sb;
183 struct debugfs_fs_info *sb_opts = sb->s_fs_info;
184 struct debugfs_fs_info *new_opts = fc->s_fs_info;
185
186 sync_filesystem(sb);
187
188 /* structure copy of new mount options to sb */
189 *sb_opts = *new_opts;
190 debugfs_apply_options_remount(sb);
191
192 return 0;
193}
194
195static int debugfs_show_options(struct seq_file *m, struct dentry *root)
196{
197 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
198
199 if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
200 seq_printf(m, ",uid=%u",
201 from_kuid_munged(&init_user_ns, fsi->uid));
202 if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
203 seq_printf(m, ",gid=%u",
204 from_kgid_munged(&init_user_ns, fsi->gid));
205 if (fsi->mode != DEBUGFS_DEFAULT_MODE)
206 seq_printf(m, ",mode=%o", fsi->mode);
207
208 return 0;
209}
210
211static void debugfs_free_inode(struct inode *inode)
212{
213 if (S_ISLNK(inode->i_mode))
214 kfree(inode->i_link);
215 free_inode_nonrcu(inode);
216}
217
218static const struct super_operations debugfs_super_operations = {
219 .statfs = simple_statfs,
220 .show_options = debugfs_show_options,
221 .free_inode = debugfs_free_inode,
222};
223
224static void debugfs_release_dentry(struct dentry *dentry)
225{
226 struct debugfs_fsdata *fsd = dentry->d_fsdata;
227
228 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
229 return;
230
231 /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
232 if (fsd && (fsd->real_fops || fsd->short_fops)) {
233 WARN_ON(!list_empty(&fsd->cancellations));
234 mutex_destroy(&fsd->cancellations_mtx);
235 }
236
237 kfree(fsd);
238}
239
240static struct vfsmount *debugfs_automount(struct path *path)
241{
242 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
243
244 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
245}
246
247static const struct dentry_operations debugfs_dops = {
248 .d_delete = always_delete_dentry,
249 .d_release = debugfs_release_dentry,
250 .d_automount = debugfs_automount,
251};
252
253static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)
254{
255 static const struct tree_descr debug_files[] = {{""}};
256 int err;
257
258 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
259 if (err)
260 return err;
261
262 sb->s_op = &debugfs_super_operations;
263 sb->s_d_op = &debugfs_dops;
264
265 debugfs_apply_options(sb);
266
267 return 0;
268}
269
270static int debugfs_get_tree(struct fs_context *fc)
271{
272 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
273 return -EPERM;
274
275 return get_tree_single(fc, debugfs_fill_super);
276}
277
278static void debugfs_free_fc(struct fs_context *fc)
279{
280 kfree(fc->s_fs_info);
281}
282
283static const struct fs_context_operations debugfs_context_ops = {
284 .free = debugfs_free_fc,
285 .parse_param = debugfs_parse_param,
286 .get_tree = debugfs_get_tree,
287 .reconfigure = debugfs_reconfigure,
288};
289
290static int debugfs_init_fs_context(struct fs_context *fc)
291{
292 struct debugfs_fs_info *fsi;
293
294 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
295 if (!fsi)
296 return -ENOMEM;
297
298 fsi->mode = DEBUGFS_DEFAULT_MODE;
299
300 fc->s_fs_info = fsi;
301 fc->ops = &debugfs_context_ops;
302 return 0;
303}
304
305static struct file_system_type debug_fs_type = {
306 .owner = THIS_MODULE,
307 .name = "debugfs",
308 .init_fs_context = debugfs_init_fs_context,
309 .parameters = debugfs_param_specs,
310 .kill_sb = kill_litter_super,
311};
312MODULE_ALIAS_FS("debugfs");
313
314/**
315 * debugfs_lookup() - look up an existing debugfs file
316 * @name: a pointer to a string containing the name of the file to look up.
317 * @parent: a pointer to the parent dentry of the file.
318 *
319 * This function will return a pointer to a dentry if it succeeds. If the file
320 * doesn't exist or an error occurs, %NULL will be returned. The returned
321 * dentry must be passed to dput() when it is no longer needed.
322 *
323 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
324 * returned.
325 */
326struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
327{
328 struct dentry *dentry;
329
330 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
331 return NULL;
332
333 if (!parent)
334 parent = debugfs_mount->mnt_root;
335
336 dentry = lookup_positive_unlocked(name, parent, strlen(name));
337 if (IS_ERR(dentry))
338 return NULL;
339 return dentry;
340}
341EXPORT_SYMBOL_GPL(debugfs_lookup);
342
343static struct dentry *start_creating(const char *name, struct dentry *parent)
344{
345 struct dentry *dentry;
346 int error;
347
348 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
349 return ERR_PTR(-EPERM);
350
351 if (!debugfs_initialized())
352 return ERR_PTR(-ENOENT);
353
354 pr_debug("creating file '%s'\n", name);
355
356 if (IS_ERR(parent))
357 return parent;
358
359 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
360 &debugfs_mount_count);
361 if (error) {
362 pr_err("Unable to pin filesystem for file '%s'\n", name);
363 return ERR_PTR(error);
364 }
365
366 /* If the parent is not specified, we create it in the root.
367 * We need the root dentry to do this, which is in the super
368 * block. A pointer to that is in the struct vfsmount that we
369 * have around.
370 */
371 if (!parent)
372 parent = debugfs_mount->mnt_root;
373
374 inode_lock(d_inode(parent));
375 if (unlikely(IS_DEADDIR(d_inode(parent))))
376 dentry = ERR_PTR(-ENOENT);
377 else
378 dentry = lookup_one_len(name, parent, strlen(name));
379 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
380 if (d_is_dir(dentry))
381 pr_err("Directory '%s' with parent '%s' already present!\n",
382 name, parent->d_name.name);
383 else
384 pr_err("File '%s' in directory '%s' already present!\n",
385 name, parent->d_name.name);
386 dput(dentry);
387 dentry = ERR_PTR(-EEXIST);
388 }
389
390 if (IS_ERR(dentry)) {
391 inode_unlock(d_inode(parent));
392 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
393 }
394
395 return dentry;
396}
397
398static struct dentry *failed_creating(struct dentry *dentry)
399{
400 inode_unlock(d_inode(dentry->d_parent));
401 dput(dentry);
402 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
403 return ERR_PTR(-ENOMEM);
404}
405
406static struct dentry *end_creating(struct dentry *dentry)
407{
408 inode_unlock(d_inode(dentry->d_parent));
409 return dentry;
410}
411
412static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
413 struct dentry *parent, void *data,
414 const struct file_operations *proxy_fops,
415 const void *real_fops)
416{
417 struct dentry *dentry;
418 struct inode *inode;
419
420 if (!(mode & S_IFMT))
421 mode |= S_IFREG;
422 BUG_ON(!S_ISREG(mode));
423 dentry = start_creating(name, parent);
424
425 if (IS_ERR(dentry))
426 return dentry;
427
428 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
429 failed_creating(dentry);
430 return ERR_PTR(-EPERM);
431 }
432
433 inode = debugfs_get_inode(dentry->d_sb);
434 if (unlikely(!inode)) {
435 pr_err("out of free dentries, can not create file '%s'\n",
436 name);
437 return failed_creating(dentry);
438 }
439
440 inode->i_mode = mode;
441 inode->i_private = data;
442
443 inode->i_op = &debugfs_file_inode_operations;
444 inode->i_fop = proxy_fops;
445 dentry->d_fsdata = (void *)((unsigned long)real_fops |
446 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
447
448 d_instantiate(dentry, inode);
449 fsnotify_create(d_inode(dentry->d_parent), dentry);
450 return end_creating(dentry);
451}
452
453struct dentry *debugfs_create_file_full(const char *name, umode_t mode,
454 struct dentry *parent, void *data,
455 const struct file_operations *fops)
456{
457 if (WARN_ON((unsigned long)fops &
458 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
459 return ERR_PTR(-EINVAL);
460
461 return __debugfs_create_file(name, mode, parent, data,
462 fops ? &debugfs_full_proxy_file_operations :
463 &debugfs_noop_file_operations,
464 fops);
465}
466EXPORT_SYMBOL_GPL(debugfs_create_file_full);
467
468struct dentry *debugfs_create_file_short(const char *name, umode_t mode,
469 struct dentry *parent, void *data,
470 const struct debugfs_short_fops *fops)
471{
472 if (WARN_ON((unsigned long)fops &
473 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
474 return ERR_PTR(-EINVAL);
475
476 return __debugfs_create_file(name, mode, parent, data,
477 fops ? &debugfs_full_short_proxy_file_operations :
478 &debugfs_noop_file_operations,
479 fops);
480}
481EXPORT_SYMBOL_GPL(debugfs_create_file_short);
482
483/**
484 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
485 * @name: a pointer to a string containing the name of the file to create.
486 * @mode: the permission that the file should have.
487 * @parent: a pointer to the parent dentry for this file. This should be a
488 * directory dentry if set. If this parameter is NULL, then the
489 * file will be created in the root of the debugfs filesystem.
490 * @data: a pointer to something that the caller will want to get to later
491 * on. The inode.i_private pointer will point to this value on
492 * the open() call.
493 * @fops: a pointer to a struct file_operations that should be used for
494 * this file.
495 *
496 * debugfs_create_file_unsafe() is completely analogous to
497 * debugfs_create_file(), the only difference being that the fops
498 * handed it will not get protected against file removals by the
499 * debugfs core.
500 *
501 * It is your responsibility to protect your struct file_operation
502 * methods against file removals by means of debugfs_file_get()
503 * and debugfs_file_put(). ->open() is still protected by
504 * debugfs though.
505 *
506 * Any struct file_operations defined by means of
507 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
508 * thus, may be used here.
509 */
510struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
511 struct dentry *parent, void *data,
512 const struct file_operations *fops)
513{
514
515 return __debugfs_create_file(name, mode, parent, data,
516 fops ? &debugfs_open_proxy_file_operations :
517 &debugfs_noop_file_operations,
518 fops);
519}
520EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
521
522/**
523 * debugfs_create_file_size - create a file in the debugfs filesystem
524 * @name: a pointer to a string containing the name of the file to create.
525 * @mode: the permission that the file should have.
526 * @parent: a pointer to the parent dentry for this file. This should be a
527 * directory dentry if set. If this parameter is NULL, then the
528 * file will be created in the root of the debugfs filesystem.
529 * @data: a pointer to something that the caller will want to get to later
530 * on. The inode.i_private pointer will point to this value on
531 * the open() call.
532 * @fops: a pointer to a struct file_operations that should be used for
533 * this file.
534 * @file_size: initial file size
535 *
536 * This is the basic "create a file" function for debugfs. It allows for a
537 * wide range of flexibility in creating a file, or a directory (if you want
538 * to create a directory, the debugfs_create_dir() function is
539 * recommended to be used instead.)
540 */
541void debugfs_create_file_size(const char *name, umode_t mode,
542 struct dentry *parent, void *data,
543 const struct file_operations *fops,
544 loff_t file_size)
545{
546 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
547
548 if (!IS_ERR(de))
549 d_inode(de)->i_size = file_size;
550}
551EXPORT_SYMBOL_GPL(debugfs_create_file_size);
552
553/**
554 * debugfs_create_dir - create a directory in the debugfs filesystem
555 * @name: a pointer to a string containing the name of the directory to
556 * create.
557 * @parent: a pointer to the parent dentry for this file. This should be a
558 * directory dentry if set. If this parameter is NULL, then the
559 * directory will be created in the root of the debugfs filesystem.
560 *
561 * This function creates a directory in debugfs with the given name.
562 *
563 * This function will return a pointer to a dentry if it succeeds. This
564 * pointer must be passed to the debugfs_remove() function when the file is
565 * to be removed (no automatic cleanup happens if your module is unloaded,
566 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
567 * returned.
568 *
569 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
570 * returned.
571 *
572 * NOTE: it's expected that most callers should _ignore_ the errors returned
573 * by this function. Other debugfs functions handle the fact that the "dentry"
574 * passed to them could be an error and they don't crash in that case.
575 * Drivers should generally work fine even if debugfs fails to init anyway.
576 */
577struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
578{
579 struct dentry *dentry = start_creating(name, parent);
580 struct inode *inode;
581
582 if (IS_ERR(dentry))
583 return dentry;
584
585 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
586 failed_creating(dentry);
587 return ERR_PTR(-EPERM);
588 }
589
590 inode = debugfs_get_inode(dentry->d_sb);
591 if (unlikely(!inode)) {
592 pr_err("out of free dentries, can not create directory '%s'\n",
593 name);
594 return failed_creating(dentry);
595 }
596
597 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
598 inode->i_op = &debugfs_dir_inode_operations;
599 inode->i_fop = &simple_dir_operations;
600
601 /* directory inodes start off with i_nlink == 2 (for "." entry) */
602 inc_nlink(inode);
603 d_instantiate(dentry, inode);
604 inc_nlink(d_inode(dentry->d_parent));
605 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
606 return end_creating(dentry);
607}
608EXPORT_SYMBOL_GPL(debugfs_create_dir);
609
610/**
611 * debugfs_create_automount - create automount point in the debugfs filesystem
612 * @name: a pointer to a string containing the name of the file to create.
613 * @parent: a pointer to the parent dentry for this file. This should be a
614 * directory dentry if set. If this parameter is NULL, then the
615 * file will be created in the root of the debugfs filesystem.
616 * @f: function to be called when pathname resolution steps on that one.
617 * @data: opaque argument to pass to f().
618 *
619 * @f should return what ->d_automount() would.
620 */
621struct dentry *debugfs_create_automount(const char *name,
622 struct dentry *parent,
623 debugfs_automount_t f,
624 void *data)
625{
626 struct dentry *dentry = start_creating(name, parent);
627 struct debugfs_fsdata *fsd;
628 struct inode *inode;
629
630 if (IS_ERR(dentry))
631 return dentry;
632
633 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
634 if (!fsd) {
635 failed_creating(dentry);
636 return ERR_PTR(-ENOMEM);
637 }
638
639 fsd->automount = f;
640
641 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
642 failed_creating(dentry);
643 kfree(fsd);
644 return ERR_PTR(-EPERM);
645 }
646
647 inode = debugfs_get_inode(dentry->d_sb);
648 if (unlikely(!inode)) {
649 pr_err("out of free dentries, can not create automount '%s'\n",
650 name);
651 kfree(fsd);
652 return failed_creating(dentry);
653 }
654
655 make_empty_dir_inode(inode);
656 inode->i_flags |= S_AUTOMOUNT;
657 inode->i_private = data;
658 dentry->d_fsdata = fsd;
659 /* directory inodes start off with i_nlink == 2 (for "." entry) */
660 inc_nlink(inode);
661 d_instantiate(dentry, inode);
662 inc_nlink(d_inode(dentry->d_parent));
663 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
664 return end_creating(dentry);
665}
666EXPORT_SYMBOL(debugfs_create_automount);
667
668/**
669 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
670 * @name: a pointer to a string containing the name of the symbolic link to
671 * create.
672 * @parent: a pointer to the parent dentry for this symbolic link. This
673 * should be a directory dentry if set. If this parameter is NULL,
674 * then the symbolic link will be created in the root of the debugfs
675 * filesystem.
676 * @target: a pointer to a string containing the path to the target of the
677 * symbolic link.
678 *
679 * This function creates a symbolic link with the given name in debugfs that
680 * links to the given target path.
681 *
682 * This function will return a pointer to a dentry if it succeeds. This
683 * pointer must be passed to the debugfs_remove() function when the symbolic
684 * link is to be removed (no automatic cleanup happens if your module is
685 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
686 * will be returned.
687 *
688 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
689 * returned.
690 */
691struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
692 const char *target)
693{
694 struct dentry *dentry;
695 struct inode *inode;
696 char *link = kstrdup(target, GFP_KERNEL);
697 if (!link)
698 return ERR_PTR(-ENOMEM);
699
700 dentry = start_creating(name, parent);
701 if (IS_ERR(dentry)) {
702 kfree(link);
703 return dentry;
704 }
705
706 inode = debugfs_get_inode(dentry->d_sb);
707 if (unlikely(!inode)) {
708 pr_err("out of free dentries, can not create symlink '%s'\n",
709 name);
710 kfree(link);
711 return failed_creating(dentry);
712 }
713 inode->i_mode = S_IFLNK | S_IRWXUGO;
714 inode->i_op = &debugfs_symlink_inode_operations;
715 inode->i_link = link;
716 d_instantiate(dentry, inode);
717 return end_creating(dentry);
718}
719EXPORT_SYMBOL_GPL(debugfs_create_symlink);
720
721static void __debugfs_file_removed(struct dentry *dentry)
722{
723 struct debugfs_fsdata *fsd;
724
725 /*
726 * Paired with the closing smp_mb() implied by a successful
727 * cmpxchg() in debugfs_file_get(): either
728 * debugfs_file_get() must see a dead dentry or we must see a
729 * debugfs_fsdata instance at ->d_fsdata here (or both).
730 */
731 smp_mb();
732 fsd = READ_ONCE(dentry->d_fsdata);
733 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
734 return;
735
736 /* if this was the last reference, we're done */
737 if (refcount_dec_and_test(&fsd->active_users))
738 return;
739
740 /*
741 * If there's still a reference, the code that obtained it can
742 * be in different states:
743 * - The common case of not using cancellations, or already
744 * after debugfs_leave_cancellation(), where we just need
745 * to wait for debugfs_file_put() which signals the completion;
746 * - inside a cancellation section, i.e. between
747 * debugfs_enter_cancellation() and debugfs_leave_cancellation(),
748 * in which case we need to trigger the ->cancel() function,
749 * and then wait for debugfs_file_put() just like in the
750 * previous case;
751 * - before debugfs_enter_cancellation() (but obviously after
752 * debugfs_file_get()), in which case we may not see the
753 * cancellation in the list on the first round of the loop,
754 * but debugfs_enter_cancellation() signals the completion
755 * after adding it, so this code gets woken up to call the
756 * ->cancel() function.
757 */
758 while (refcount_read(&fsd->active_users)) {
759 struct debugfs_cancellation *c;
760
761 /*
762 * Lock the cancellations. Note that the cancellations
763 * structs are meant to be on the stack, so we need to
764 * ensure we either use them here or don't touch them,
765 * and debugfs_leave_cancellation() will wait for this
766 * to be finished processing before exiting one. It may
767 * of course win and remove the cancellation, but then
768 * chances are we never even got into this bit, we only
769 * do if the refcount isn't zero already.
770 */
771 mutex_lock(&fsd->cancellations_mtx);
772 while ((c = list_first_entry_or_null(&fsd->cancellations,
773 typeof(*c), list))) {
774 list_del_init(&c->list);
775 c->cancel(dentry, c->cancel_data);
776 }
777 mutex_unlock(&fsd->cancellations_mtx);
778
779 wait_for_completion(&fsd->active_users_drained);
780 }
781}
782
783static void remove_one(struct dentry *victim)
784{
785 if (d_is_reg(victim))
786 __debugfs_file_removed(victim);
787 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
788}
789
790/**
791 * debugfs_remove - recursively removes a directory
792 * @dentry: a pointer to a the dentry of the directory to be removed. If this
793 * parameter is NULL or an error value, nothing will be done.
794 *
795 * This function recursively removes a directory tree in debugfs that
796 * was previously created with a call to another debugfs function
797 * (like debugfs_create_file() or variants thereof.)
798 *
799 * This function is required to be called in order for the file to be
800 * removed, no automatic cleanup of files will happen when a module is
801 * removed, you are responsible here.
802 */
803void debugfs_remove(struct dentry *dentry)
804{
805 if (IS_ERR_OR_NULL(dentry))
806 return;
807
808 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
809 simple_recursive_removal(dentry, remove_one);
810 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
811}
812EXPORT_SYMBOL_GPL(debugfs_remove);
813
814/**
815 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
816 * @name: a pointer to a string containing the name of the item to look up.
817 * @parent: a pointer to the parent dentry of the item.
818 *
819 * This is the equlivant of doing something like
820 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
821 * handled for the directory being looked up.
822 */
823void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
824{
825 struct dentry *dentry;
826
827 dentry = debugfs_lookup(name, parent);
828 if (!dentry)
829 return;
830
831 debugfs_remove(dentry);
832 dput(dentry);
833}
834EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
835
836/**
837 * debugfs_rename - rename a file/directory in the debugfs filesystem
838 * @old_dir: a pointer to the parent dentry for the renamed object. This
839 * should be a directory dentry.
840 * @old_dentry: dentry of an object to be renamed.
841 * @new_dir: a pointer to the parent dentry where the object should be
842 * moved. This should be a directory dentry.
843 * @new_name: a pointer to a string containing the target name.
844 *
845 * This function renames a file/directory in debugfs. The target must not
846 * exist for rename to succeed.
847 *
848 * This function will return a pointer to old_dentry (which is updated to
849 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
850 * will be returned.
851 *
852 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
853 * returned.
854 */
855struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
856 struct dentry *new_dir, const char *new_name)
857{
858 int error;
859 struct dentry *dentry = NULL, *trap;
860 struct name_snapshot old_name;
861
862 if (IS_ERR(old_dir))
863 return old_dir;
864 if (IS_ERR(new_dir))
865 return new_dir;
866 if (IS_ERR_OR_NULL(old_dentry))
867 return old_dentry;
868
869 trap = lock_rename(new_dir, old_dir);
870 /* Source or destination directories don't exist? */
871 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
872 goto exit;
873 /* Source does not exist, cyclic rename, or mountpoint? */
874 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
875 d_mountpoint(old_dentry))
876 goto exit;
877 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
878 /* Lookup failed, cyclic rename or target exists? */
879 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
880 goto exit;
881
882 take_dentry_name_snapshot(&old_name, old_dentry);
883
884 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
885 d_inode(new_dir), dentry, 0);
886 if (error) {
887 release_dentry_name_snapshot(&old_name);
888 goto exit;
889 }
890 d_move(old_dentry, dentry);
891 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
892 d_is_dir(old_dentry),
893 NULL, old_dentry);
894 release_dentry_name_snapshot(&old_name);
895 unlock_rename(new_dir, old_dir);
896 dput(dentry);
897 return old_dentry;
898exit:
899 if (dentry && !IS_ERR(dentry))
900 dput(dentry);
901 unlock_rename(new_dir, old_dir);
902 if (IS_ERR(dentry))
903 return dentry;
904 return ERR_PTR(-EINVAL);
905}
906EXPORT_SYMBOL_GPL(debugfs_rename);
907
908/**
909 * debugfs_initialized - Tells whether debugfs has been registered
910 */
911bool debugfs_initialized(void)
912{
913 return debugfs_registered;
914}
915EXPORT_SYMBOL_GPL(debugfs_initialized);
916
917static int __init debugfs_kernel(char *str)
918{
919 if (str) {
920 if (!strcmp(str, "on"))
921 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
922 else if (!strcmp(str, "no-mount"))
923 debugfs_allow = DEBUGFS_ALLOW_API;
924 else if (!strcmp(str, "off"))
925 debugfs_allow = 0;
926 }
927
928 return 0;
929}
930early_param("debugfs", debugfs_kernel);
931static int __init debugfs_init(void)
932{
933 int retval;
934
935 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
936 return -EPERM;
937
938 retval = sysfs_create_mount_point(kernel_kobj, "debug");
939 if (retval)
940 return retval;
941
942 retval = register_filesystem(&debug_fs_type);
943 if (retval)
944 sysfs_remove_mount_point(kernel_kobj, "debug");
945 else
946 debugfs_registered = true;
947
948 return retval;
949}
950core_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