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