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
31 #define DEBUGFS_DEFAULT_MODE 0755
32
33 static struct vfsmount *debugfs_mount;
34 static int debugfs_mount_count;
35 static bool debugfs_registered;
36
debugfs_get_inode(struct super_block * sb,umode_t mode,dev_t dev,void * data,const struct file_operations * fops)37 static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
38 void *data, const struct file_operations *fops)
39
40 {
41 struct inode *inode = new_inode(sb);
42
43 if (inode) {
44 inode->i_ino = get_next_ino();
45 inode->i_mode = mode;
46 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 switch (mode & S_IFMT) {
48 default:
49 init_special_inode(inode, mode, dev);
50 break;
51 case S_IFREG:
52 inode->i_fop = fops ? fops : &debugfs_file_operations;
53 inode->i_private = data;
54 break;
55 case S_IFLNK:
56 inode->i_op = &debugfs_link_operations;
57 inode->i_fop = fops;
58 inode->i_private = data;
59 break;
60 case S_IFDIR:
61 inode->i_op = &simple_dir_inode_operations;
62 inode->i_fop = fops ? fops : &simple_dir_operations;
63 inode->i_private = data;
64
65 /* directory inodes start off with i_nlink == 2
66 * (for "." entry) */
67 inc_nlink(inode);
68 break;
69 }
70 }
71 return inode;
72 }
73
74 /* SMP-safe */
debugfs_mknod(struct inode * dir,struct dentry * dentry,umode_t mode,dev_t dev,void * data,const struct file_operations * fops)75 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
76 umode_t mode, dev_t dev, void *data,
77 const struct file_operations *fops)
78 {
79 struct inode *inode;
80 int error = -EPERM;
81
82 if (dentry->d_inode)
83 return -EEXIST;
84
85 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
86 if (inode) {
87 d_instantiate(dentry, inode);
88 dget(dentry);
89 error = 0;
90 }
91 return error;
92 }
93
debugfs_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode,void * data,const struct file_operations * fops)94 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode,
95 void *data, const struct file_operations *fops)
96 {
97 int res;
98
99 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
100 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
101 if (!res) {
102 inc_nlink(dir);
103 fsnotify_mkdir(dir, dentry);
104 }
105 return res;
106 }
107
debugfs_link(struct inode * dir,struct dentry * dentry,umode_t mode,void * data,const struct file_operations * fops)108 static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
109 void *data, const struct file_operations *fops)
110 {
111 mode = (mode & S_IALLUGO) | S_IFLNK;
112 return debugfs_mknod(dir, dentry, mode, 0, data, fops);
113 }
114
debugfs_create(struct inode * dir,struct dentry * dentry,umode_t mode,void * data,const struct file_operations * fops)115 static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
116 void *data, const struct file_operations *fops)
117 {
118 int res;
119
120 mode = (mode & S_IALLUGO) | S_IFREG;
121 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
122 if (!res)
123 fsnotify_create(dir, dentry);
124 return res;
125 }
126
debugfs_positive(struct dentry * dentry)127 static inline int debugfs_positive(struct dentry *dentry)
128 {
129 return dentry->d_inode && !d_unhashed(dentry);
130 }
131
132 struct debugfs_mount_opts {
133 uid_t uid;
134 gid_t gid;
135 umode_t mode;
136 };
137
138 enum {
139 Opt_uid,
140 Opt_gid,
141 Opt_mode,
142 Opt_err
143 };
144
145 static const match_table_t tokens = {
146 {Opt_uid, "uid=%u"},
147 {Opt_gid, "gid=%u"},
148 {Opt_mode, "mode=%o"},
149 {Opt_err, NULL}
150 };
151
152 struct debugfs_fs_info {
153 struct debugfs_mount_opts mount_opts;
154 };
155
debugfs_parse_options(char * data,struct debugfs_mount_opts * opts)156 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
157 {
158 substring_t args[MAX_OPT_ARGS];
159 int option;
160 int token;
161 char *p;
162
163 opts->mode = DEBUGFS_DEFAULT_MODE;
164
165 while ((p = strsep(&data, ",")) != NULL) {
166 if (!*p)
167 continue;
168
169 token = match_token(p, tokens, args);
170 switch (token) {
171 case Opt_uid:
172 if (match_int(&args[0], &option))
173 return -EINVAL;
174 opts->uid = option;
175 break;
176 case Opt_gid:
177 if (match_octal(&args[0], &option))
178 return -EINVAL;
179 opts->gid = option;
180 break;
181 case Opt_mode:
182 if (match_octal(&args[0], &option))
183 return -EINVAL;
184 opts->mode = option & S_IALLUGO;
185 break;
186 /*
187 * We might like to report bad mount options here;
188 * but traditionally debugfs has ignored all mount options
189 */
190 }
191 }
192
193 return 0;
194 }
195
debugfs_apply_options(struct super_block * sb)196 static int debugfs_apply_options(struct super_block *sb)
197 {
198 struct debugfs_fs_info *fsi = sb->s_fs_info;
199 struct inode *inode = sb->s_root->d_inode;
200 struct debugfs_mount_opts *opts = &fsi->mount_opts;
201
202 inode->i_mode &= ~S_IALLUGO;
203 inode->i_mode |= opts->mode;
204
205 inode->i_uid = opts->uid;
206 inode->i_gid = opts->gid;
207
208 return 0;
209 }
210
debugfs_remount(struct super_block * sb,int * flags,char * data)211 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
212 {
213 int err;
214 struct debugfs_fs_info *fsi = sb->s_fs_info;
215
216 err = debugfs_parse_options(data, &fsi->mount_opts);
217 if (err)
218 goto fail;
219
220 debugfs_apply_options(sb);
221
222 fail:
223 return err;
224 }
225
debugfs_show_options(struct seq_file * m,struct dentry * root)226 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
227 {
228 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
229 struct debugfs_mount_opts *opts = &fsi->mount_opts;
230
231 if (opts->uid != 0)
232 seq_printf(m, ",uid=%u", opts->uid);
233 if (opts->gid != 0)
234 seq_printf(m, ",gid=%u", opts->gid);
235 if (opts->mode != DEBUGFS_DEFAULT_MODE)
236 seq_printf(m, ",mode=%o", opts->mode);
237
238 return 0;
239 }
240
241 static const struct super_operations debugfs_super_operations = {
242 .statfs = simple_statfs,
243 .remount_fs = debugfs_remount,
244 .show_options = debugfs_show_options,
245 };
246
debug_fill_super(struct super_block * sb,void * data,int silent)247 static int debug_fill_super(struct super_block *sb, void *data, int silent)
248 {
249 static struct tree_descr debug_files[] = {{""}};
250 struct debugfs_fs_info *fsi;
251 int err;
252
253 save_mount_options(sb, data);
254
255 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
256 sb->s_fs_info = fsi;
257 if (!fsi) {
258 err = -ENOMEM;
259 goto fail;
260 }
261
262 err = debugfs_parse_options(data, &fsi->mount_opts);
263 if (err)
264 goto fail;
265
266 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
267 if (err)
268 goto fail;
269
270 sb->s_op = &debugfs_super_operations;
271
272 debugfs_apply_options(sb);
273
274 return 0;
275
276 fail:
277 kfree(fsi);
278 sb->s_fs_info = NULL;
279 return err;
280 }
281
debug_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)282 static struct dentry *debug_mount(struct file_system_type *fs_type,
283 int flags, const char *dev_name,
284 void *data)
285 {
286 return mount_single(fs_type, flags, data, debug_fill_super);
287 }
288
289 static struct file_system_type debug_fs_type = {
290 .owner = THIS_MODULE,
291 .name = "debugfs",
292 .mount = debug_mount,
293 .kill_sb = kill_litter_super,
294 };
295
debugfs_create_by_name(const char * name,umode_t mode,struct dentry * parent,struct dentry ** dentry,void * data,const struct file_operations * fops)296 static int debugfs_create_by_name(const char *name, umode_t mode,
297 struct dentry *parent,
298 struct dentry **dentry,
299 void *data,
300 const struct file_operations *fops)
301 {
302 int error = 0;
303
304 /* If the parent is not specified, we create it in the root.
305 * We need the root dentry to do this, which is in the super
306 * block. A pointer to that is in the struct vfsmount that we
307 * have around.
308 */
309 if (!parent)
310 parent = debugfs_mount->mnt_root;
311
312 *dentry = NULL;
313 mutex_lock(&parent->d_inode->i_mutex);
314 *dentry = lookup_one_len(name, parent, strlen(name));
315 if (!IS_ERR(*dentry)) {
316 switch (mode & S_IFMT) {
317 case S_IFDIR:
318 error = debugfs_mkdir(parent->d_inode, *dentry, mode,
319 data, fops);
320 break;
321 case S_IFLNK:
322 error = debugfs_link(parent->d_inode, *dentry, mode,
323 data, fops);
324 break;
325 default:
326 error = debugfs_create(parent->d_inode, *dentry, mode,
327 data, fops);
328 break;
329 }
330 dput(*dentry);
331 } else
332 error = PTR_ERR(*dentry);
333 mutex_unlock(&parent->d_inode->i_mutex);
334
335 return error;
336 }
337
338 /**
339 * debugfs_create_file - create a file in the debugfs filesystem
340 * @name: a pointer to a string containing the name of the file to create.
341 * @mode: the permission that the file should have.
342 * @parent: a pointer to the parent dentry for this file. This should be a
343 * directory dentry if set. If this paramater is NULL, then the
344 * file will be created in the root of the debugfs filesystem.
345 * @data: a pointer to something that the caller will want to get to later
346 * on. The inode.i_private pointer will point to this value on
347 * the open() call.
348 * @fops: a pointer to a struct file_operations that should be used for
349 * this file.
350 *
351 * This is the basic "create a file" function for debugfs. It allows for a
352 * wide range of flexibility in creating a file, or a directory (if you want
353 * to create a directory, the debugfs_create_dir() function is
354 * recommended to be used instead.)
355 *
356 * This function will return a pointer to a dentry if it succeeds. This
357 * pointer must be passed to the debugfs_remove() function when the file is
358 * to be removed (no automatic cleanup happens if your module is unloaded,
359 * you are responsible here.) If an error occurs, %NULL will be returned.
360 *
361 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
362 * returned.
363 */
debugfs_create_file(const char * name,umode_t mode,struct dentry * parent,void * data,const struct file_operations * fops)364 struct dentry *debugfs_create_file(const char *name, umode_t mode,
365 struct dentry *parent, void *data,
366 const struct file_operations *fops)
367 {
368 struct dentry *dentry = NULL;
369 int error;
370
371 pr_debug("debugfs: creating file '%s'\n",name);
372
373 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
374 &debugfs_mount_count);
375 if (error)
376 goto exit;
377
378 error = debugfs_create_by_name(name, mode, parent, &dentry,
379 data, fops);
380 if (error) {
381 dentry = NULL;
382 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
383 goto exit;
384 }
385 exit:
386 return dentry;
387 }
388 EXPORT_SYMBOL_GPL(debugfs_create_file);
389
390 /**
391 * debugfs_create_dir - create a directory in the debugfs filesystem
392 * @name: a pointer to a string containing the name of the directory to
393 * create.
394 * @parent: a pointer to the parent dentry for this file. This should be a
395 * directory dentry if set. If this paramater is NULL, then the
396 * directory will be created in the root of the debugfs filesystem.
397 *
398 * This function creates a directory in debugfs with the given name.
399 *
400 * This function will return a pointer to a dentry if it succeeds. This
401 * pointer must be passed to the debugfs_remove() function when the file is
402 * to be removed (no automatic cleanup happens if your module is unloaded,
403 * you are responsible here.) If an error occurs, %NULL will be returned.
404 *
405 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
406 * returned.
407 */
debugfs_create_dir(const char * name,struct dentry * parent)408 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
409 {
410 return debugfs_create_file(name,
411 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
412 parent, NULL, NULL);
413 }
414 EXPORT_SYMBOL_GPL(debugfs_create_dir);
415
416 /**
417 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
418 * @name: a pointer to a string containing the name of the symbolic link to
419 * create.
420 * @parent: a pointer to the parent dentry for this symbolic link. This
421 * should be a directory dentry if set. If this paramater is NULL,
422 * then the symbolic link will be created in the root of the debugfs
423 * filesystem.
424 * @target: a pointer to a string containing the path to the target of the
425 * symbolic link.
426 *
427 * This function creates a symbolic link with the given name in debugfs that
428 * links to the given target path.
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 symbolic
432 * link is to be removed (no automatic cleanup happens if your module is
433 * unloaded, you are responsible here.) If an error occurs, %NULL will be
434 * returned.
435 *
436 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
437 * returned.
438 */
debugfs_create_symlink(const char * name,struct dentry * parent,const char * target)439 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
440 const char *target)
441 {
442 struct dentry *result;
443 char *link;
444
445 link = kstrdup(target, GFP_KERNEL);
446 if (!link)
447 return NULL;
448
449 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
450 NULL);
451 if (!result)
452 kfree(link);
453 return result;
454 }
455 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
456
__debugfs_remove(struct dentry * dentry,struct dentry * parent)457 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
458 {
459 int ret = 0;
460
461 if (debugfs_positive(dentry)) {
462 if (dentry->d_inode) {
463 dget(dentry);
464 switch (dentry->d_inode->i_mode & S_IFMT) {
465 case S_IFDIR:
466 ret = simple_rmdir(parent->d_inode, dentry);
467 break;
468 case S_IFLNK:
469 kfree(dentry->d_inode->i_private);
470 /* fall through */
471 default:
472 simple_unlink(parent->d_inode, dentry);
473 break;
474 }
475 if (!ret)
476 d_delete(dentry);
477 dput(dentry);
478 }
479 }
480 return ret;
481 }
482
483 /**
484 * debugfs_remove - removes a file or directory from the debugfs filesystem
485 * @dentry: a pointer to a the dentry of the file or directory to be
486 * removed.
487 *
488 * This function removes a file or directory in debugfs that was previously
489 * created with a call to another debugfs function (like
490 * debugfs_create_file() or variants thereof.)
491 *
492 * This function is required to be called in order for the file to be
493 * removed, no automatic cleanup of files will happen when a module is
494 * removed, you are responsible here.
495 */
debugfs_remove(struct dentry * dentry)496 void debugfs_remove(struct dentry *dentry)
497 {
498 struct dentry *parent;
499 int ret;
500
501 if (!dentry)
502 return;
503
504 parent = dentry->d_parent;
505 if (!parent || !parent->d_inode)
506 return;
507
508 mutex_lock(&parent->d_inode->i_mutex);
509 ret = __debugfs_remove(dentry, parent);
510 mutex_unlock(&parent->d_inode->i_mutex);
511 if (!ret)
512 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
513 }
514 EXPORT_SYMBOL_GPL(debugfs_remove);
515
516 /**
517 * debugfs_remove_recursive - recursively removes a directory
518 * @dentry: a pointer to a the dentry of the directory to be removed.
519 *
520 * This function recursively removes a directory tree in debugfs that
521 * was previously created with a call to another debugfs function
522 * (like debugfs_create_file() or variants thereof.)
523 *
524 * This function is required to be called in order for the file to be
525 * removed, no automatic cleanup of files will happen when a module is
526 * removed, you are responsible here.
527 */
debugfs_remove_recursive(struct dentry * dentry)528 void debugfs_remove_recursive(struct dentry *dentry)
529 {
530 struct dentry *child, *next, *parent;
531
532 if (!dentry)
533 return;
534
535 parent = dentry->d_parent;
536 if (!parent || !parent->d_inode)
537 return;
538
539 parent = dentry;
540 down:
541 mutex_lock(&parent->d_inode->i_mutex);
542 list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
543 if (!debugfs_positive(child))
544 continue;
545
546 /* perhaps simple_empty(child) makes more sense */
547 if (!list_empty(&child->d_subdirs)) {
548 mutex_unlock(&parent->d_inode->i_mutex);
549 parent = child;
550 goto down;
551 }
552 up:
553 if (!__debugfs_remove(child, parent))
554 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
555 }
556
557 mutex_unlock(&parent->d_inode->i_mutex);
558 child = parent;
559 parent = parent->d_parent;
560 mutex_lock(&parent->d_inode->i_mutex);
561
562 if (child != dentry) {
563 next = list_entry(child->d_u.d_child.next, struct dentry,
564 d_u.d_child);
565 goto up;
566 }
567
568 if (!__debugfs_remove(child, parent))
569 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
570 mutex_unlock(&parent->d_inode->i_mutex);
571 }
572 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
573
574 /**
575 * debugfs_rename - rename a file/directory in the debugfs filesystem
576 * @old_dir: a pointer to the parent dentry for the renamed object. This
577 * should be a directory dentry.
578 * @old_dentry: dentry of an object to be renamed.
579 * @new_dir: a pointer to the parent dentry where the object should be
580 * moved. This should be a directory dentry.
581 * @new_name: a pointer to a string containing the target name.
582 *
583 * This function renames a file/directory in debugfs. The target must not
584 * exist for rename to succeed.
585 *
586 * This function will return a pointer to old_dentry (which is updated to
587 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
588 * returned.
589 *
590 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
591 * returned.
592 */
debugfs_rename(struct dentry * old_dir,struct dentry * old_dentry,struct dentry * new_dir,const char * new_name)593 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
594 struct dentry *new_dir, const char *new_name)
595 {
596 int error;
597 struct dentry *dentry = NULL, *trap;
598 const char *old_name;
599
600 trap = lock_rename(new_dir, old_dir);
601 /* Source or destination directories don't exist? */
602 if (!old_dir->d_inode || !new_dir->d_inode)
603 goto exit;
604 /* Source does not exist, cyclic rename, or mountpoint? */
605 if (!old_dentry->d_inode || old_dentry == trap ||
606 d_mountpoint(old_dentry))
607 goto exit;
608 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
609 /* Lookup failed, cyclic rename or target exists? */
610 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
611 goto exit;
612
613 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
614
615 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
616 dentry);
617 if (error) {
618 fsnotify_oldname_free(old_name);
619 goto exit;
620 }
621 d_move(old_dentry, dentry);
622 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
623 S_ISDIR(old_dentry->d_inode->i_mode),
624 NULL, old_dentry);
625 fsnotify_oldname_free(old_name);
626 unlock_rename(new_dir, old_dir);
627 dput(dentry);
628 return old_dentry;
629 exit:
630 if (dentry && !IS_ERR(dentry))
631 dput(dentry);
632 unlock_rename(new_dir, old_dir);
633 return NULL;
634 }
635 EXPORT_SYMBOL_GPL(debugfs_rename);
636
637 /**
638 * debugfs_initialized - Tells whether debugfs has been registered
639 */
debugfs_initialized(void)640 bool debugfs_initialized(void)
641 {
642 return debugfs_registered;
643 }
644 EXPORT_SYMBOL_GPL(debugfs_initialized);
645
646
647 static struct kobject *debug_kobj;
648
debugfs_init(void)649 static int __init debugfs_init(void)
650 {
651 int retval;
652
653 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
654 if (!debug_kobj)
655 return -EINVAL;
656
657 retval = register_filesystem(&debug_fs_type);
658 if (retval)
659 kobject_put(debug_kobj);
660 else
661 debugfs_registered = true;
662
663 return retval;
664 }
665 core_initcall(debugfs_init);
666
667