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12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/mount.h>
15#include <linux/pagemap.h>
16#include <linux/init.h>
17#include <linux/kobject.h>
18#include <linux/namei.h>
19#include <linux/debugfs.h>
20#include <linux/fsnotify.h>
21#include <linux/string.h>
22#include <linux/seq_file.h>
23#include <linux/parser.h>
24#include <linux/magic.h>
25#include <linux/slab.h>
26
27#include "internal.h"
28
29#define DEBUGFS_DEFAULT_MODE 0700
30
31static struct vfsmount *debugfs_mount;
32static int debugfs_mount_count;
33static bool debugfs_registered;
34
35static struct inode *debugfs_get_inode(struct super_block *sb)
36{
37 struct inode *inode = new_inode(sb);
38 if (inode) {
39 inode->i_ino = get_next_ino();
40 inode->i_atime = inode->i_mtime =
41 inode->i_ctime = current_time(inode);
42 }
43 return inode;
44}
45
46struct debugfs_mount_opts {
47 kuid_t uid;
48 kgid_t gid;
49 umode_t mode;
50};
51
52enum {
53 Opt_uid,
54 Opt_gid,
55 Opt_mode,
56 Opt_err
57};
58
59static const match_table_t tokens = {
60 {Opt_uid, "uid=%u"},
61 {Opt_gid, "gid=%u"},
62 {Opt_mode, "mode=%o"},
63 {Opt_err, NULL}
64};
65
66struct debugfs_fs_info {
67 struct debugfs_mount_opts mount_opts;
68};
69
70static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
71{
72 substring_t args[MAX_OPT_ARGS];
73 int option;
74 int token;
75 kuid_t uid;
76 kgid_t gid;
77 char *p;
78
79 opts->mode = DEBUGFS_DEFAULT_MODE;
80
81 while ((p = strsep(&data, ",")) != NULL) {
82 if (!*p)
83 continue;
84
85 token = match_token(p, tokens, args);
86 switch (token) {
87 case Opt_uid:
88 if (match_int(&args[0], &option))
89 return -EINVAL;
90 uid = make_kuid(current_user_ns(), option);
91 if (!uid_valid(uid))
92 return -EINVAL;
93 opts->uid = uid;
94 break;
95 case Opt_gid:
96 if (match_int(&args[0], &option))
97 return -EINVAL;
98 gid = make_kgid(current_user_ns(), option);
99 if (!gid_valid(gid))
100 return -EINVAL;
101 opts->gid = gid;
102 break;
103 case Opt_mode:
104 if (match_octal(&args[0], &option))
105 return -EINVAL;
106 opts->mode = option & S_IALLUGO;
107 break;
108
109
110
111
112 }
113 }
114
115 return 0;
116}
117
118static int debugfs_apply_options(struct super_block *sb)
119{
120 struct debugfs_fs_info *fsi = sb->s_fs_info;
121 struct inode *inode = d_inode(sb->s_root);
122 struct debugfs_mount_opts *opts = &fsi->mount_opts;
123
124 inode->i_mode &= ~S_IALLUGO;
125 inode->i_mode |= opts->mode;
126
127 inode->i_uid = opts->uid;
128 inode->i_gid = opts->gid;
129
130 return 0;
131}
132
133static int debugfs_remount(struct super_block *sb, int *flags, char *data)
134{
135 int err;
136 struct debugfs_fs_info *fsi = sb->s_fs_info;
137
138 sync_filesystem(sb);
139 err = debugfs_parse_options(data, &fsi->mount_opts);
140 if (err)
141 goto fail;
142
143 debugfs_apply_options(sb);
144
145fail:
146 return err;
147}
148
149static int debugfs_show_options(struct seq_file *m, struct dentry *root)
150{
151 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
152 struct debugfs_mount_opts *opts = &fsi->mount_opts;
153
154 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
155 seq_printf(m, ",uid=%u",
156 from_kuid_munged(&init_user_ns, opts->uid));
157 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
158 seq_printf(m, ",gid=%u",
159 from_kgid_munged(&init_user_ns, opts->gid));
160 if (opts->mode != DEBUGFS_DEFAULT_MODE)
161 seq_printf(m, ",mode=%o", opts->mode);
162
163 return 0;
164}
165
166static void debugfs_evict_inode(struct inode *inode)
167{
168 truncate_inode_pages_final(&inode->i_data);
169 clear_inode(inode);
170 if (S_ISLNK(inode->i_mode))
171 kfree(inode->i_link);
172}
173
174static const struct super_operations debugfs_super_operations = {
175 .statfs = simple_statfs,
176 .remount_fs = debugfs_remount,
177 .show_options = debugfs_show_options,
178 .evict_inode = debugfs_evict_inode,
179};
180
181static void debugfs_release_dentry(struct dentry *dentry)
182{
183 void *fsd = dentry->d_fsdata;
184
185 if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
186 kfree(dentry->d_fsdata);
187}
188
189static struct vfsmount *debugfs_automount(struct path *path)
190{
191 debugfs_automount_t f;
192 f = (debugfs_automount_t)path->dentry->d_fsdata;
193 return f(path->dentry, d_inode(path->dentry)->i_private);
194}
195
196static const struct dentry_operations debugfs_dops = {
197 .d_delete = always_delete_dentry,
198 .d_release = debugfs_release_dentry,
199 .d_automount = debugfs_automount,
200};
201
202static int debug_fill_super(struct super_block *sb, void *data, int silent)
203{
204 static const struct tree_descr debug_files[] = {{""}};
205 struct debugfs_fs_info *fsi;
206 int err;
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");
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262
263struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
264{
265 struct dentry *dentry;
266
267 if (IS_ERR(parent))
268 return NULL;
269
270 if (!parent)
271 parent = debugfs_mount->mnt_root;
272
273 dentry = lookup_one_len_unlocked(name, parent, strlen(name));
274 if (IS_ERR(dentry))
275 return NULL;
276 if (!d_really_is_positive(dentry)) {
277 dput(dentry);
278 return NULL;
279 }
280 return dentry;
281}
282EXPORT_SYMBOL_GPL(debugfs_lookup);
283
284static struct dentry *start_creating(const char *name, struct dentry *parent)
285{
286 struct dentry *dentry;
287 int error;
288
289 pr_debug("debugfs: creating file '%s'\n",name);
290
291 if (IS_ERR(parent))
292 return parent;
293
294 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
295 &debugfs_mount_count);
296 if (error)
297 return ERR_PTR(error);
298
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303
304 if (!parent)
305 parent = debugfs_mount->mnt_root;
306
307 inode_lock(d_inode(parent));
308 dentry = lookup_one_len(name, parent, strlen(name));
309 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
310 dput(dentry);
311 dentry = ERR_PTR(-EEXIST);
312 }
313
314 if (IS_ERR(dentry)) {
315 inode_unlock(d_inode(parent));
316 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
317 }
318
319 return dentry;
320}
321
322static struct dentry *failed_creating(struct dentry *dentry)
323{
324 inode_unlock(d_inode(dentry->d_parent));
325 dput(dentry);
326 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
327 return NULL;
328}
329
330static struct dentry *end_creating(struct dentry *dentry)
331{
332 inode_unlock(d_inode(dentry->d_parent));
333 return dentry;
334}
335
336static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
337 struct dentry *parent, void *data,
338 const struct file_operations *proxy_fops,
339 const struct file_operations *real_fops)
340{
341 struct dentry *dentry;
342 struct inode *inode;
343
344 if (!(mode & S_IFMT))
345 mode |= S_IFREG;
346 BUG_ON(!S_ISREG(mode));
347 dentry = start_creating(name, parent);
348
349 if (IS_ERR(dentry))
350 return NULL;
351
352 inode = debugfs_get_inode(dentry->d_sb);
353 if (unlikely(!inode))
354 return failed_creating(dentry);
355
356 inode->i_mode = mode;
357 inode->i_private = data;
358
359 inode->i_fop = proxy_fops;
360 dentry->d_fsdata = (void *)((unsigned long)real_fops |
361 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
362
363 d_instantiate(dentry, inode);
364 fsnotify_create(d_inode(dentry->d_parent), dentry);
365 return end_creating(dentry);
366}
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394struct dentry *debugfs_create_file(const char *name, umode_t mode,
395 struct dentry *parent, void *data,
396 const struct file_operations *fops)
397{
398
399 return __debugfs_create_file(name, mode, parent, data,
400 fops ? &debugfs_full_proxy_file_operations :
401 &debugfs_noop_file_operations,
402 fops);
403}
404EXPORT_SYMBOL_GPL(debugfs_create_file);
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433struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
434 struct dentry *parent, void *data,
435 const struct file_operations *fops)
436{
437
438 return __debugfs_create_file(name, mode, parent, data,
439 fops ? &debugfs_open_proxy_file_operations :
440 &debugfs_noop_file_operations,
441 fops);
442}
443EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
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472struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
473 struct dentry *parent, void *data,
474 const struct file_operations *fops,
475 loff_t file_size)
476{
477 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
478
479 if (de)
480 d_inode(de)->i_size = file_size;
481 return de;
482}
483EXPORT_SYMBOL_GPL(debugfs_create_file_size);
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503struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
504{
505 struct dentry *dentry = start_creating(name, parent);
506 struct inode *inode;
507
508 if (IS_ERR(dentry))
509 return NULL;
510
511 inode = debugfs_get_inode(dentry->d_sb);
512 if (unlikely(!inode))
513 return failed_creating(dentry);
514
515 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
516 inode->i_op = &simple_dir_inode_operations;
517 inode->i_fop = &simple_dir_operations;
518
519
520 inc_nlink(inode);
521 d_instantiate(dentry, inode);
522 inc_nlink(d_inode(dentry->d_parent));
523 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
524 return end_creating(dentry);
525}
526EXPORT_SYMBOL_GPL(debugfs_create_dir);
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539struct dentry *debugfs_create_automount(const char *name,
540 struct dentry *parent,
541 debugfs_automount_t f,
542 void *data)
543{
544 struct dentry *dentry = start_creating(name, parent);
545 struct inode *inode;
546
547 if (IS_ERR(dentry))
548 return NULL;
549
550 inode = debugfs_get_inode(dentry->d_sb);
551 if (unlikely(!inode))
552 return failed_creating(dentry);
553
554 make_empty_dir_inode(inode);
555 inode->i_flags |= S_AUTOMOUNT;
556 inode->i_private = data;
557 dentry->d_fsdata = (void *)f;
558
559 inc_nlink(inode);
560 d_instantiate(dentry, inode);
561 inc_nlink(d_inode(dentry->d_parent));
562 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
563 return end_creating(dentry);
564}
565EXPORT_SYMBOL(debugfs_create_automount);
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590struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
591 const char *target)
592{
593 struct dentry *dentry;
594 struct inode *inode;
595 char *link = kstrdup(target, GFP_KERNEL);
596 if (!link)
597 return NULL;
598
599 dentry = start_creating(name, parent);
600 if (IS_ERR(dentry)) {
601 kfree(link);
602 return NULL;
603 }
604
605 inode = debugfs_get_inode(dentry->d_sb);
606 if (unlikely(!inode)) {
607 kfree(link);
608 return failed_creating(dentry);
609 }
610 inode->i_mode = S_IFLNK | S_IRWXUGO;
611 inode->i_op = &simple_symlink_inode_operations;
612 inode->i_link = link;
613 d_instantiate(dentry, inode);
614 return end_creating(dentry);
615}
616EXPORT_SYMBOL_GPL(debugfs_create_symlink);
617
618static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent)
619{
620 struct debugfs_fsdata *fsd;
621
622 simple_unlink(d_inode(parent), dentry);
623 d_delete(dentry);
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631 smp_mb();
632 fsd = READ_ONCE(dentry->d_fsdata);
633 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
634 return;
635 if (!refcount_dec_and_test(&fsd->active_users))
636 wait_for_completion(&fsd->active_users_drained);
637}
638
639static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
640{
641 int ret = 0;
642
643 if (simple_positive(dentry)) {
644 dget(dentry);
645 if (!d_is_reg(dentry)) {
646 if (d_is_dir(dentry))
647 ret = simple_rmdir(d_inode(parent), dentry);
648 else
649 simple_unlink(d_inode(parent), dentry);
650 if (!ret)
651 d_delete(dentry);
652 } else {
653 __debugfs_remove_file(dentry, parent);
654 }
655 dput(dentry);
656 }
657 return ret;
658}
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674void debugfs_remove(struct dentry *dentry)
675{
676 struct dentry *parent;
677 int ret;
678
679 if (IS_ERR_OR_NULL(dentry))
680 return;
681
682 parent = dentry->d_parent;
683 inode_lock(d_inode(parent));
684 ret = __debugfs_remove(dentry, parent);
685 inode_unlock(d_inode(parent));
686 if (!ret)
687 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
688}
689EXPORT_SYMBOL_GPL(debugfs_remove);
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704void debugfs_remove_recursive(struct dentry *dentry)
705{
706 struct dentry *child, *parent;
707
708 if (IS_ERR_OR_NULL(dentry))
709 return;
710
711 parent = dentry;
712 down:
713 inode_lock(d_inode(parent));
714 loop:
715
716
717
718
719
720 spin_lock(&parent->d_lock);
721 list_for_each_entry(child, &parent->d_subdirs, d_child) {
722 if (!simple_positive(child))
723 continue;
724
725
726 if (!list_empty(&child->d_subdirs)) {
727 spin_unlock(&parent->d_lock);
728 inode_unlock(d_inode(parent));
729 parent = child;
730 goto down;
731 }
732
733 spin_unlock(&parent->d_lock);
734
735 if (!__debugfs_remove(child, parent))
736 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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745 goto loop;
746 }
747 spin_unlock(&parent->d_lock);
748
749 inode_unlock(d_inode(parent));
750 child = parent;
751 parent = parent->d_parent;
752 inode_lock(d_inode(parent));
753
754 if (child != dentry)
755
756 goto loop;
757
758 if (!__debugfs_remove(child, parent))
759 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
760 inode_unlock(d_inode(parent));
761}
762EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
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783struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
784 struct dentry *new_dir, const char *new_name)
785{
786 int error;
787 struct dentry *dentry = NULL, *trap;
788 struct name_snapshot old_name;
789
790 trap = lock_rename(new_dir, old_dir);
791
792 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
793 goto exit;
794
795 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
796 d_mountpoint(old_dentry))
797 goto exit;
798 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
799
800 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
801 goto exit;
802
803 take_dentry_name_snapshot(&old_name, old_dentry);
804
805 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
806 dentry, 0);
807 if (error) {
808 release_dentry_name_snapshot(&old_name);
809 goto exit;
810 }
811 d_move(old_dentry, dentry);
812 fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
813 d_is_dir(old_dentry),
814 NULL, old_dentry);
815 release_dentry_name_snapshot(&old_name);
816 unlock_rename(new_dir, old_dir);
817 dput(dentry);
818 return old_dentry;
819exit:
820 if (dentry && !IS_ERR(dentry))
821 dput(dentry);
822 unlock_rename(new_dir, old_dir);
823 return NULL;
824}
825EXPORT_SYMBOL_GPL(debugfs_rename);
826
827
828
829
830bool debugfs_initialized(void)
831{
832 return debugfs_registered;
833}
834EXPORT_SYMBOL_GPL(debugfs_initialized);
835
836static int __init debugfs_init(void)
837{
838 int retval;
839
840 retval = sysfs_create_mount_point(kernel_kobj, "debug");
841 if (retval)
842 return retval;
843
844 retval = register_filesystem(&debug_fs_type);
845 if (retval)
846 sysfs_remove_mount_point(kernel_kobj, "debug");
847 else
848 debugfs_registered = true;
849
850 return retval;
851}
852core_initcall(debugfs_init);
853
854