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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 = DEFAULT_DEBUGFS_ALLOW_BITS;
39
40
41
42
43
44
45static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
46{
47 int ret = security_locked_down(LOCKDOWN_DEBUGFS);
48
49 if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
50 return ret;
51 return simple_setattr(dentry, ia);
52}
53
54static const struct inode_operations debugfs_file_inode_operations = {
55 .setattr = debugfs_setattr,
56};
57static const struct inode_operations debugfs_dir_inode_operations = {
58 .lookup = simple_lookup,
59 .setattr = debugfs_setattr,
60};
61static const struct inode_operations debugfs_symlink_inode_operations = {
62 .get_link = simple_get_link,
63 .setattr = debugfs_setattr,
64};
65
66static struct inode *debugfs_get_inode(struct super_block *sb)
67{
68 struct inode *inode = new_inode(sb);
69 if (inode) {
70 inode->i_ino = get_next_ino();
71 inode->i_atime = inode->i_mtime =
72 inode->i_ctime = current_time(inode);
73 }
74 return inode;
75}
76
77struct debugfs_mount_opts {
78 kuid_t uid;
79 kgid_t gid;
80 umode_t mode;
81};
82
83enum {
84 Opt_uid,
85 Opt_gid,
86 Opt_mode,
87 Opt_err
88};
89
90static const match_table_t tokens = {
91 {Opt_uid, "uid=%u"},
92 {Opt_gid, "gid=%u"},
93 {Opt_mode, "mode=%o"},
94 {Opt_err, NULL}
95};
96
97struct debugfs_fs_info {
98 struct debugfs_mount_opts mount_opts;
99};
100
101static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
102{
103 substring_t args[MAX_OPT_ARGS];
104 int option;
105 int token;
106 kuid_t uid;
107 kgid_t gid;
108 char *p;
109
110 opts->mode = DEBUGFS_DEFAULT_MODE;
111
112 while ((p = strsep(&data, ",")) != NULL) {
113 if (!*p)
114 continue;
115
116 token = match_token(p, tokens, args);
117 switch (token) {
118 case Opt_uid:
119 if (match_int(&args[0], &option))
120 return -EINVAL;
121 uid = make_kuid(current_user_ns(), option);
122 if (!uid_valid(uid))
123 return -EINVAL;
124 opts->uid = uid;
125 break;
126 case Opt_gid:
127 if (match_int(&args[0], &option))
128 return -EINVAL;
129 gid = make_kgid(current_user_ns(), option);
130 if (!gid_valid(gid))
131 return -EINVAL;
132 opts->gid = gid;
133 break;
134 case Opt_mode:
135 if (match_octal(&args[0], &option))
136 return -EINVAL;
137 opts->mode = option & S_IALLUGO;
138 break;
139
140
141
142
143 }
144 }
145
146 return 0;
147}
148
149static int debugfs_apply_options(struct super_block *sb)
150{
151 struct debugfs_fs_info *fsi = sb->s_fs_info;
152 struct inode *inode = d_inode(sb->s_root);
153 struct debugfs_mount_opts *opts = &fsi->mount_opts;
154
155 inode->i_mode &= ~S_IALLUGO;
156 inode->i_mode |= opts->mode;
157
158 inode->i_uid = opts->uid;
159 inode->i_gid = opts->gid;
160
161 return 0;
162}
163
164static int debugfs_remount(struct super_block *sb, int *flags, char *data)
165{
166 int err;
167 struct debugfs_fs_info *fsi = sb->s_fs_info;
168
169 sync_filesystem(sb);
170 err = debugfs_parse_options(data, &fsi->mount_opts);
171 if (err)
172 goto fail;
173
174 debugfs_apply_options(sb);
175
176fail:
177 return err;
178}
179
180static int debugfs_show_options(struct seq_file *m, struct dentry *root)
181{
182 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
183 struct debugfs_mount_opts *opts = &fsi->mount_opts;
184
185 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
186 seq_printf(m, ",uid=%u",
187 from_kuid_munged(&init_user_ns, opts->uid));
188 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
189 seq_printf(m, ",gid=%u",
190 from_kgid_munged(&init_user_ns, opts->gid));
191 if (opts->mode != DEBUGFS_DEFAULT_MODE)
192 seq_printf(m, ",mode=%o", opts->mode);
193
194 return 0;
195}
196
197static void debugfs_free_inode(struct inode *inode)
198{
199 if (S_ISLNK(inode->i_mode))
200 kfree(inode->i_link);
201 free_inode_nonrcu(inode);
202}
203
204static const struct super_operations debugfs_super_operations = {
205 .statfs = simple_statfs,
206 .remount_fs = debugfs_remount,
207 .show_options = debugfs_show_options,
208 .free_inode = debugfs_free_inode,
209};
210
211static void debugfs_release_dentry(struct dentry *dentry)
212{
213 void *fsd = dentry->d_fsdata;
214
215 if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
216 kfree(dentry->d_fsdata);
217}
218
219static struct vfsmount *debugfs_automount(struct path *path)
220{
221 debugfs_automount_t f;
222 f = (debugfs_automount_t)path->dentry->d_fsdata;
223 return f(path->dentry, d_inode(path->dentry)->i_private);
224}
225
226static const struct dentry_operations debugfs_dops = {
227 .d_delete = always_delete_dentry,
228 .d_release = debugfs_release_dentry,
229 .d_automount = debugfs_automount,
230};
231
232static int debug_fill_super(struct super_block *sb, void *data, int silent)
233{
234 static const struct tree_descr debug_files[] = {{""}};
235 struct debugfs_fs_info *fsi;
236 int err;
237
238 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
239 sb->s_fs_info = fsi;
240 if (!fsi) {
241 err = -ENOMEM;
242 goto fail;
243 }
244
245 err = debugfs_parse_options(data, &fsi->mount_opts);
246 if (err)
247 goto fail;
248
249 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
250 if (err)
251 goto fail;
252
253 sb->s_op = &debugfs_super_operations;
254 sb->s_d_op = &debugfs_dops;
255
256 debugfs_apply_options(sb);
257
258 return 0;
259
260fail:
261 kfree(fsi);
262 sb->s_fs_info = NULL;
263 return err;
264}
265
266static struct dentry *debug_mount(struct file_system_type *fs_type,
267 int flags, const char *dev_name,
268 void *data)
269{
270 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
271 return ERR_PTR(-EPERM);
272
273 return mount_single(fs_type, flags, data, debug_fill_super);
274}
275
276static struct file_system_type debug_fs_type = {
277 .owner = THIS_MODULE,
278 .name = "debugfs",
279 .mount = debug_mount,
280 .kill_sb = kill_litter_super,
281};
282MODULE_ALIAS_FS("debugfs");
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295
296struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
297{
298 struct dentry *dentry;
299
300 if (IS_ERR(parent))
301 return NULL;
302
303 if (!parent)
304 parent = debugfs_mount->mnt_root;
305
306 dentry = lookup_positive_unlocked(name, parent, strlen(name));
307 if (IS_ERR(dentry))
308 return NULL;
309 return dentry;
310}
311EXPORT_SYMBOL_GPL(debugfs_lookup);
312
313static struct dentry *start_creating(const char *name, struct dentry *parent)
314{
315 struct dentry *dentry;
316 int error;
317
318 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
319 return ERR_PTR(-EPERM);
320
321 pr_debug("creating file '%s'\n", name);
322
323 if (IS_ERR(parent))
324 return parent;
325
326 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
327 &debugfs_mount_count);
328 if (error) {
329 pr_err("Unable to pin filesystem for file '%s'\n", name);
330 return ERR_PTR(error);
331 }
332
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337
338 if (!parent)
339 parent = debugfs_mount->mnt_root;
340
341 inode_lock(d_inode(parent));
342 if (unlikely(IS_DEADDIR(d_inode(parent))))
343 dentry = ERR_PTR(-ENOENT);
344 else
345 dentry = lookup_one_len(name, parent, strlen(name));
346 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
347 if (d_is_dir(dentry))
348 pr_err("Directory '%s' with parent '%s' already present!\n",
349 name, parent->d_name.name);
350 else
351 pr_err("File '%s' in directory '%s' already present!\n",
352 name, parent->d_name.name);
353 dput(dentry);
354 dentry = ERR_PTR(-EEXIST);
355 }
356
357 if (IS_ERR(dentry)) {
358 inode_unlock(d_inode(parent));
359 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
360 }
361
362 return dentry;
363}
364
365static struct dentry *failed_creating(struct dentry *dentry)
366{
367 inode_unlock(d_inode(dentry->d_parent));
368 dput(dentry);
369 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
370 return ERR_PTR(-ENOMEM);
371}
372
373static struct dentry *end_creating(struct dentry *dentry)
374{
375 inode_unlock(d_inode(dentry->d_parent));
376 return dentry;
377}
378
379static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
380 struct dentry *parent, void *data,
381 const struct file_operations *proxy_fops,
382 const struct file_operations *real_fops)
383{
384 struct dentry *dentry;
385 struct inode *inode;
386
387 if (!(mode & S_IFMT))
388 mode |= S_IFREG;
389 BUG_ON(!S_ISREG(mode));
390 dentry = start_creating(name, parent);
391
392 if (IS_ERR(dentry))
393 return dentry;
394
395 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
396 failed_creating(dentry);
397 return ERR_PTR(-EPERM);
398 }
399
400 inode = debugfs_get_inode(dentry->d_sb);
401 if (unlikely(!inode)) {
402 pr_err("out of free dentries, can not create file '%s'\n",
403 name);
404 return failed_creating(dentry);
405 }
406
407 inode->i_mode = mode;
408 inode->i_private = data;
409
410 inode->i_op = &debugfs_file_inode_operations;
411 inode->i_fop = proxy_fops;
412 dentry->d_fsdata = (void *)((unsigned long)real_fops |
413 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
414
415 d_instantiate(dentry, inode);
416 fsnotify_create(d_inode(dentry->d_parent), dentry);
417 return end_creating(dentry);
418}
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447struct dentry *debugfs_create_file(const char *name, umode_t mode,
448 struct dentry *parent, void *data,
449 const struct file_operations *fops)
450{
451
452 return __debugfs_create_file(name, mode, parent, data,
453 fops ? &debugfs_full_proxy_file_operations :
454 &debugfs_noop_file_operations,
455 fops);
456}
457EXPORT_SYMBOL_GPL(debugfs_create_file);
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486struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
487 struct dentry *parent, void *data,
488 const struct file_operations *fops)
489{
490
491 return __debugfs_create_file(name, mode, parent, data,
492 fops ? &debugfs_open_proxy_file_operations :
493 &debugfs_noop_file_operations,
494 fops);
495}
496EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
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517void debugfs_create_file_size(const char *name, umode_t mode,
518 struct dentry *parent, void *data,
519 const struct file_operations *fops,
520 loff_t file_size)
521{
522 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
523
524 if (de)
525 d_inode(de)->i_size = file_size;
526}
527EXPORT_SYMBOL_GPL(debugfs_create_file_size);
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548struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
549{
550 struct dentry *dentry = start_creating(name, parent);
551 struct inode *inode;
552
553 if (IS_ERR(dentry))
554 return dentry;
555
556 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
557 failed_creating(dentry);
558 return ERR_PTR(-EPERM);
559 }
560
561 inode = debugfs_get_inode(dentry->d_sb);
562 if (unlikely(!inode)) {
563 pr_err("out of free dentries, can not create directory '%s'\n",
564 name);
565 return failed_creating(dentry);
566 }
567
568 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
569 inode->i_op = &debugfs_dir_inode_operations;
570 inode->i_fop = &simple_dir_operations;
571
572
573 inc_nlink(inode);
574 d_instantiate(dentry, inode);
575 inc_nlink(d_inode(dentry->d_parent));
576 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
577 return end_creating(dentry);
578}
579EXPORT_SYMBOL_GPL(debugfs_create_dir);
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592struct dentry *debugfs_create_automount(const char *name,
593 struct dentry *parent,
594 debugfs_automount_t f,
595 void *data)
596{
597 struct dentry *dentry = start_creating(name, parent);
598 struct inode *inode;
599
600 if (IS_ERR(dentry))
601 return dentry;
602
603 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
604 failed_creating(dentry);
605 return ERR_PTR(-EPERM);
606 }
607
608 inode = debugfs_get_inode(dentry->d_sb);
609 if (unlikely(!inode)) {
610 pr_err("out of free dentries, can not create automount '%s'\n",
611 name);
612 return failed_creating(dentry);
613 }
614
615 make_empty_dir_inode(inode);
616 inode->i_flags |= S_AUTOMOUNT;
617 inode->i_private = data;
618 dentry->d_fsdata = (void *)f;
619
620 inc_nlink(inode);
621 d_instantiate(dentry, inode);
622 inc_nlink(d_inode(dentry->d_parent));
623 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
624 return end_creating(dentry);
625}
626EXPORT_SYMBOL(debugfs_create_automount);
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651struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
652 const char *target)
653{
654 struct dentry *dentry;
655 struct inode *inode;
656 char *link = kstrdup(target, GFP_KERNEL);
657 if (!link)
658 return ERR_PTR(-ENOMEM);
659
660 dentry = start_creating(name, parent);
661 if (IS_ERR(dentry)) {
662 kfree(link);
663 return dentry;
664 }
665
666 inode = debugfs_get_inode(dentry->d_sb);
667 if (unlikely(!inode)) {
668 pr_err("out of free dentries, can not create symlink '%s'\n",
669 name);
670 kfree(link);
671 return failed_creating(dentry);
672 }
673 inode->i_mode = S_IFLNK | S_IRWXUGO;
674 inode->i_op = &debugfs_symlink_inode_operations;
675 inode->i_link = link;
676 d_instantiate(dentry, inode);
677 return end_creating(dentry);
678}
679EXPORT_SYMBOL_GPL(debugfs_create_symlink);
680
681static void __debugfs_file_removed(struct dentry *dentry)
682{
683 struct debugfs_fsdata *fsd;
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691 smp_mb();
692 fsd = READ_ONCE(dentry->d_fsdata);
693 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
694 return;
695 if (!refcount_dec_and_test(&fsd->active_users))
696 wait_for_completion(&fsd->active_users_drained);
697}
698
699static void remove_one(struct dentry *victim)
700{
701 if (d_is_reg(victim))
702 __debugfs_file_removed(victim);
703 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
704}
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719void debugfs_remove(struct dentry *dentry)
720{
721 if (IS_ERR_OR_NULL(dentry))
722 return;
723
724 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
725 simple_recursive_removal(dentry, remove_one);
726 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
727}
728EXPORT_SYMBOL_GPL(debugfs_remove);
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749struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
750 struct dentry *new_dir, const char *new_name)
751{
752 int error;
753 struct dentry *dentry = NULL, *trap;
754 struct name_snapshot old_name;
755
756 if (IS_ERR(old_dir))
757 return old_dir;
758 if (IS_ERR(new_dir))
759 return new_dir;
760 if (IS_ERR_OR_NULL(old_dentry))
761 return old_dentry;
762
763 trap = lock_rename(new_dir, old_dir);
764
765 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
766 goto exit;
767
768 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
769 d_mountpoint(old_dentry))
770 goto exit;
771 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
772
773 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
774 goto exit;
775
776 take_dentry_name_snapshot(&old_name, old_dentry);
777
778 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
779 dentry, 0);
780 if (error) {
781 release_dentry_name_snapshot(&old_name);
782 goto exit;
783 }
784 d_move(old_dentry, dentry);
785 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
786 d_is_dir(old_dentry),
787 NULL, old_dentry);
788 release_dentry_name_snapshot(&old_name);
789 unlock_rename(new_dir, old_dir);
790 dput(dentry);
791 return old_dentry;
792exit:
793 if (dentry && !IS_ERR(dentry))
794 dput(dentry);
795 unlock_rename(new_dir, old_dir);
796 if (IS_ERR(dentry))
797 return dentry;
798 return ERR_PTR(-EINVAL);
799}
800EXPORT_SYMBOL_GPL(debugfs_rename);
801
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805bool debugfs_initialized(void)
806{
807 return debugfs_registered;
808}
809EXPORT_SYMBOL_GPL(debugfs_initialized);
810
811static int __init debugfs_kernel(char *str)
812{
813 if (str) {
814 if (!strcmp(str, "on"))
815 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
816 else if (!strcmp(str, "no-mount"))
817 debugfs_allow = DEBUGFS_ALLOW_API;
818 else if (!strcmp(str, "off"))
819 debugfs_allow = 0;
820 }
821
822 return 0;
823}
824early_param("debugfs", debugfs_kernel);
825static int __init debugfs_init(void)
826{
827 int retval;
828
829 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
830 return -EPERM;
831
832 retval = sysfs_create_mount_point(kernel_kobj, "debug");
833 if (retval)
834 return retval;
835
836 retval = register_filesystem(&debug_fs_type);
837 if (retval)
838 sysfs_remove_mount_point(kernel_kobj, "debug");
839 else
840 debugfs_registered = true;
841
842 return retval;
843}
844core_initcall(debugfs_init);
845