Line data Source code
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 :
35 : static struct vfsmount *debugfs_mount;
36 : static int debugfs_mount_count;
37 : static bool debugfs_registered;
38 : static unsigned int debugfs_allow = 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 : */
45 0 : static int debugfs_setattr(struct user_namespace *mnt_userns,
46 : struct dentry *dentry, struct iattr *ia)
47 : {
48 0 : int ret = security_locked_down(LOCKDOWN_DEBUGFS);
49 :
50 0 : if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
51 : return ret;
52 0 : return simple_setattr(&init_user_ns, dentry, ia);
53 : }
54 :
55 : static const struct inode_operations debugfs_file_inode_operations = {
56 : .setattr = debugfs_setattr,
57 : };
58 : static const struct inode_operations debugfs_dir_inode_operations = {
59 : .lookup = simple_lookup,
60 : .setattr = debugfs_setattr,
61 : };
62 : static const struct inode_operations debugfs_symlink_inode_operations = {
63 : .get_link = simple_get_link,
64 : .setattr = debugfs_setattr,
65 : };
66 :
67 2068 : static struct inode *debugfs_get_inode(struct super_block *sb)
68 : {
69 2068 : struct inode *inode = new_inode(sb);
70 2068 : if (inode) {
71 2068 : inode->i_ino = get_next_ino();
72 2068 : inode->i_atime = inode->i_mtime =
73 2068 : inode->i_ctime = current_time(inode);
74 : }
75 2068 : return inode;
76 : }
77 :
78 : struct debugfs_mount_opts {
79 : kuid_t uid;
80 : kgid_t gid;
81 : umode_t mode;
82 : };
83 :
84 : enum {
85 : Opt_uid,
86 : Opt_gid,
87 : Opt_mode,
88 : Opt_err
89 : };
90 :
91 : static const match_table_t tokens = {
92 : {Opt_uid, "uid=%u"},
93 : {Opt_gid, "gid=%u"},
94 : {Opt_mode, "mode=%o"},
95 : {Opt_err, NULL}
96 : };
97 :
98 : struct debugfs_fs_info {
99 : struct debugfs_mount_opts mount_opts;
100 : };
101 :
102 2 : static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
103 : {
104 2 : substring_t args[MAX_OPT_ARGS];
105 2 : int option;
106 2 : int token;
107 2 : kuid_t uid;
108 2 : kgid_t gid;
109 2 : char *p;
110 :
111 2 : opts->mode = DEBUGFS_DEFAULT_MODE;
112 :
113 2 : while ((p = strsep(&data, ",")) != NULL) {
114 0 : if (!*p)
115 0 : continue;
116 :
117 0 : token = match_token(p, tokens, args);
118 0 : switch (token) {
119 0 : case Opt_uid:
120 0 : if (match_int(&args[0], &option))
121 : return -EINVAL;
122 0 : uid = make_kuid(current_user_ns(), option);
123 0 : if (!uid_valid(uid))
124 : return -EINVAL;
125 0 : opts->uid = uid;
126 0 : break;
127 0 : case Opt_gid:
128 0 : if (match_int(&args[0], &option))
129 : return -EINVAL;
130 0 : gid = make_kgid(current_user_ns(), option);
131 0 : if (!gid_valid(gid))
132 : return -EINVAL;
133 0 : opts->gid = gid;
134 0 : break;
135 0 : case Opt_mode:
136 0 : if (match_octal(&args[0], &option))
137 : return -EINVAL;
138 0 : opts->mode = option & S_IALLUGO;
139 0 : break;
140 : /*
141 : * We might like to report bad mount options here;
142 : * but traditionally debugfs has ignored all mount options
143 : */
144 : }
145 : }
146 :
147 : return 0;
148 : }
149 :
150 2 : static int debugfs_apply_options(struct super_block *sb)
151 : {
152 2 : struct debugfs_fs_info *fsi = sb->s_fs_info;
153 2 : struct inode *inode = d_inode(sb->s_root);
154 2 : struct debugfs_mount_opts *opts = &fsi->mount_opts;
155 :
156 2 : inode->i_mode &= ~S_IALLUGO;
157 2 : inode->i_mode |= opts->mode;
158 :
159 2 : inode->i_uid = opts->uid;
160 2 : inode->i_gid = opts->gid;
161 :
162 2 : return 0;
163 : }
164 :
165 1 : static int debugfs_remount(struct super_block *sb, int *flags, char *data)
166 : {
167 1 : int err;
168 1 : struct debugfs_fs_info *fsi = sb->s_fs_info;
169 :
170 1 : sync_filesystem(sb);
171 1 : err = debugfs_parse_options(data, &fsi->mount_opts);
172 1 : if (err)
173 0 : goto fail;
174 :
175 1 : debugfs_apply_options(sb);
176 :
177 1 : fail:
178 1 : return err;
179 : }
180 :
181 285 : static int debugfs_show_options(struct seq_file *m, struct dentry *root)
182 : {
183 285 : struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
184 285 : struct debugfs_mount_opts *opts = &fsi->mount_opts;
185 :
186 285 : if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
187 0 : seq_printf(m, ",uid=%u",
188 : from_kuid_munged(&init_user_ns, opts->uid));
189 285 : if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
190 0 : seq_printf(m, ",gid=%u",
191 : from_kgid_munged(&init_user_ns, opts->gid));
192 285 : if (opts->mode != DEBUGFS_DEFAULT_MODE)
193 0 : seq_printf(m, ",mode=%o", opts->mode);
194 :
195 285 : return 0;
196 : }
197 :
198 0 : static void debugfs_free_inode(struct inode *inode)
199 : {
200 0 : if (S_ISLNK(inode->i_mode))
201 0 : kfree(inode->i_link);
202 0 : free_inode_nonrcu(inode);
203 0 : }
204 :
205 : static const struct super_operations debugfs_super_operations = {
206 : .statfs = simple_statfs,
207 : .remount_fs = debugfs_remount,
208 : .show_options = debugfs_show_options,
209 : .free_inode = debugfs_free_inode,
210 : };
211 :
212 145 : static void debugfs_release_dentry(struct dentry *dentry)
213 : {
214 145 : void *fsd = dentry->d_fsdata;
215 :
216 145 : if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
217 145 : kfree(dentry->d_fsdata);
218 145 : }
219 :
220 0 : static struct vfsmount *debugfs_automount(struct path *path)
221 : {
222 0 : debugfs_automount_t f;
223 0 : f = (debugfs_automount_t)path->dentry->d_fsdata;
224 0 : return f(path->dentry, d_inode(path->dentry)->i_private);
225 : }
226 :
227 : static const struct dentry_operations debugfs_dops = {
228 : .d_delete = always_delete_dentry,
229 : .d_release = debugfs_release_dentry,
230 : .d_automount = debugfs_automount,
231 : };
232 :
233 1 : static int debug_fill_super(struct super_block *sb, void *data, int silent)
234 : {
235 1 : static const struct tree_descr debug_files[] = {{""}};
236 1 : struct debugfs_fs_info *fsi;
237 1 : int err;
238 :
239 1 : fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
240 1 : sb->s_fs_info = fsi;
241 1 : if (!fsi) {
242 0 : err = -ENOMEM;
243 0 : goto fail;
244 : }
245 :
246 1 : err = debugfs_parse_options(data, &fsi->mount_opts);
247 1 : if (err)
248 0 : goto fail;
249 :
250 1 : err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
251 1 : if (err)
252 0 : goto fail;
253 :
254 1 : sb->s_op = &debugfs_super_operations;
255 1 : sb->s_d_op = &debugfs_dops;
256 :
257 1 : debugfs_apply_options(sb);
258 :
259 1 : return 0;
260 :
261 0 : fail:
262 0 : kfree(fsi);
263 0 : sb->s_fs_info = NULL;
264 0 : return err;
265 : }
266 :
267 2 : static struct dentry *debug_mount(struct file_system_type *fs_type,
268 : int flags, const char *dev_name,
269 : void *data)
270 : {
271 2 : if (!(debugfs_allow & DEBUGFS_ALLOW_API))
272 2 : return ERR_PTR(-EPERM);
273 :
274 2 : return mount_single(fs_type, flags, data, debug_fill_super);
275 : }
276 :
277 : static struct file_system_type debug_fs_type = {
278 : .owner = THIS_MODULE,
279 : .name = "debugfs",
280 : .mount = debug_mount,
281 : .kill_sb = kill_litter_super,
282 : };
283 : MODULE_ALIAS_FS("debugfs");
284 :
285 : /**
286 : * debugfs_lookup() - look up an existing debugfs file
287 : * @name: a pointer to a string containing the name of the file to look up.
288 : * @parent: a pointer to the parent dentry of the file.
289 : *
290 : * This function will return a pointer to a dentry if it succeeds. If the file
291 : * doesn't exist or an error occurs, %NULL will be returned. The returned
292 : * dentry must be passed to dput() when it is no longer needed.
293 : *
294 : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
295 : * returned.
296 : */
297 0 : struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
298 : {
299 0 : struct dentry *dentry;
300 :
301 0 : if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
302 : return NULL;
303 :
304 0 : if (!parent)
305 0 : parent = debugfs_mount->mnt_root;
306 :
307 0 : dentry = lookup_positive_unlocked(name, parent, strlen(name));
308 0 : if (IS_ERR(dentry))
309 0 : return NULL;
310 : return dentry;
311 : }
312 : EXPORT_SYMBOL_GPL(debugfs_lookup);
313 :
314 2068 : static struct dentry *start_creating(const char *name, struct dentry *parent)
315 : {
316 2068 : struct dentry *dentry;
317 2068 : int error;
318 :
319 2068 : if (!(debugfs_allow & DEBUGFS_ALLOW_API))
320 2068 : return ERR_PTR(-EPERM);
321 :
322 2068 : if (!debugfs_initialized())
323 2068 : return ERR_PTR(-ENOENT);
324 :
325 2068 : pr_debug("creating file '%s'\n", name);
326 :
327 2068 : if (IS_ERR(parent))
328 : return parent;
329 :
330 2068 : error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
331 : &debugfs_mount_count);
332 2068 : if (error) {
333 0 : pr_err("Unable to pin filesystem for file '%s'\n", name);
334 0 : return ERR_PTR(error);
335 : }
336 :
337 : /* If the parent is not specified, we create it in the root.
338 : * We need the root dentry to do this, which is in the super
339 : * block. A pointer to that is in the struct vfsmount that we
340 : * have around.
341 : */
342 2068 : if (!parent)
343 17 : parent = debugfs_mount->mnt_root;
344 :
345 2068 : inode_lock(d_inode(parent));
346 2068 : if (unlikely(IS_DEADDIR(d_inode(parent))))
347 2068 : dentry = ERR_PTR(-ENOENT);
348 : else
349 2068 : dentry = lookup_one_len(name, parent, strlen(name));
350 2068 : if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
351 0 : if (d_is_dir(dentry))
352 0 : pr_err("Directory '%s' with parent '%s' already present!\n",
353 : name, parent->d_name.name);
354 : else
355 0 : pr_err("File '%s' in directory '%s' already present!\n",
356 : name, parent->d_name.name);
357 0 : dput(dentry);
358 0 : dentry = ERR_PTR(-EEXIST);
359 : }
360 :
361 2068 : if (IS_ERR(dentry)) {
362 0 : inode_unlock(d_inode(parent));
363 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
364 : }
365 :
366 : return dentry;
367 : }
368 :
369 0 : static struct dentry *failed_creating(struct dentry *dentry)
370 : {
371 0 : inode_unlock(d_inode(dentry->d_parent));
372 0 : dput(dentry);
373 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
374 0 : return ERR_PTR(-ENOMEM);
375 : }
376 :
377 2068 : static struct dentry *end_creating(struct dentry *dentry)
378 : {
379 2068 : inode_unlock(d_inode(dentry->d_parent));
380 2068 : return dentry;
381 : }
382 :
383 982 : static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
384 : struct dentry *parent, void *data,
385 : const struct file_operations *proxy_fops,
386 : const struct file_operations *real_fops)
387 : {
388 982 : struct dentry *dentry;
389 982 : struct inode *inode;
390 :
391 982 : if (!(mode & S_IFMT))
392 982 : mode |= S_IFREG;
393 982 : BUG_ON(!S_ISREG(mode));
394 982 : dentry = start_creating(name, parent);
395 :
396 982 : if (IS_ERR(dentry))
397 : return dentry;
398 :
399 982 : if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
400 0 : failed_creating(dentry);
401 0 : return ERR_PTR(-EPERM);
402 : }
403 :
404 982 : inode = debugfs_get_inode(dentry->d_sb);
405 982 : if (unlikely(!inode)) {
406 0 : pr_err("out of free dentries, can not create file '%s'\n",
407 : name);
408 0 : return failed_creating(dentry);
409 : }
410 :
411 982 : inode->i_mode = mode;
412 982 : inode->i_private = data;
413 :
414 982 : inode->i_op = &debugfs_file_inode_operations;
415 982 : inode->i_fop = proxy_fops;
416 982 : dentry->d_fsdata = (void *)((unsigned long)real_fops |
417 : DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
418 :
419 982 : d_instantiate(dentry, inode);
420 982 : fsnotify_create(d_inode(dentry->d_parent), dentry);
421 982 : return end_creating(dentry);
422 : }
423 :
424 : /**
425 : * debugfs_create_file - create a file in the debugfs filesystem
426 : * @name: a pointer to a string containing the name of the file to create.
427 : * @mode: the permission that the file should have.
428 : * @parent: a pointer to the parent dentry for this file. This should be a
429 : * directory dentry if set. If this parameter is NULL, then the
430 : * file will be created in the root of the debugfs filesystem.
431 : * @data: a pointer to something that the caller will want to get to later
432 : * on. The inode.i_private pointer will point to this value on
433 : * the open() call.
434 : * @fops: a pointer to a struct file_operations that should be used for
435 : * this file.
436 : *
437 : * This is the basic "create a file" function for debugfs. It allows for a
438 : * wide range of flexibility in creating a file, or a directory (if you want
439 : * to create a directory, the debugfs_create_dir() function is
440 : * recommended to be used instead.)
441 : *
442 : * This function will return a pointer to a dentry if it succeeds. This
443 : * pointer must be passed to the debugfs_remove() function when the file is
444 : * to be removed (no automatic cleanup happens if your module is unloaded,
445 : * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
446 : * returned.
447 : *
448 : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
449 : * returned.
450 : */
451 973 : struct dentry *debugfs_create_file(const char *name, umode_t mode,
452 : struct dentry *parent, void *data,
453 : const struct file_operations *fops)
454 : {
455 :
456 973 : return __debugfs_create_file(name, mode, parent, data,
457 : fops ? &debugfs_full_proxy_file_operations :
458 : &debugfs_noop_file_operations,
459 : fops);
460 : }
461 : EXPORT_SYMBOL_GPL(debugfs_create_file);
462 :
463 : /**
464 : * debugfs_create_file_unsafe - create a file in the debugfs filesystem
465 : * @name: a pointer to a string containing the name of the file to create.
466 : * @mode: the permission that the file should have.
467 : * @parent: a pointer to the parent dentry for this file. This should be a
468 : * directory dentry if set. If this parameter is NULL, then the
469 : * file will be created in the root of the debugfs filesystem.
470 : * @data: a pointer to something that the caller will want to get to later
471 : * on. The inode.i_private pointer will point to this value on
472 : * the open() call.
473 : * @fops: a pointer to a struct file_operations that should be used for
474 : * this file.
475 : *
476 : * debugfs_create_file_unsafe() is completely analogous to
477 : * debugfs_create_file(), the only difference being that the fops
478 : * handed it will not get protected against file removals by the
479 : * debugfs core.
480 : *
481 : * It is your responsibility to protect your struct file_operation
482 : * methods against file removals by means of debugfs_file_get()
483 : * and debugfs_file_put(). ->open() is still protected by
484 : * debugfs though.
485 : *
486 : * Any struct file_operations defined by means of
487 : * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
488 : * thus, may be used here.
489 : */
490 9 : struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
491 : struct dentry *parent, void *data,
492 : const struct file_operations *fops)
493 : {
494 :
495 9 : return __debugfs_create_file(name, mode, parent, data,
496 : fops ? &debugfs_open_proxy_file_operations :
497 : &debugfs_noop_file_operations,
498 : fops);
499 : }
500 : EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
501 :
502 : /**
503 : * debugfs_create_file_size - create a file in the debugfs filesystem
504 : * @name: a pointer to a string containing the name of the file to create.
505 : * @mode: the permission that the file should have.
506 : * @parent: a pointer to the parent dentry for this file. This should be a
507 : * directory dentry if set. If this parameter is NULL, then the
508 : * file will be created in the root of the debugfs filesystem.
509 : * @data: a pointer to something that the caller will want to get to later
510 : * on. The inode.i_private pointer will point to this value on
511 : * the open() call.
512 : * @fops: a pointer to a struct file_operations that should be used for
513 : * this file.
514 : * @file_size: initial file size
515 : *
516 : * This is the basic "create a file" function for debugfs. It allows for a
517 : * wide range of flexibility in creating a file, or a directory (if you want
518 : * to create a directory, the debugfs_create_dir() function is
519 : * recommended to be used instead.)
520 : */
521 0 : void debugfs_create_file_size(const char *name, umode_t mode,
522 : struct dentry *parent, void *data,
523 : const struct file_operations *fops,
524 : loff_t file_size)
525 : {
526 0 : struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
527 :
528 0 : if (de)
529 0 : d_inode(de)->i_size = file_size;
530 0 : }
531 : EXPORT_SYMBOL_GPL(debugfs_create_file_size);
532 :
533 : /**
534 : * debugfs_create_dir - create a directory in the debugfs filesystem
535 : * @name: a pointer to a string containing the name of the directory to
536 : * create.
537 : * @parent: a pointer to the parent dentry for this file. This should be a
538 : * directory dentry if set. If this parameter is NULL, then the
539 : * directory will be created in the root of the debugfs filesystem.
540 : *
541 : * This function creates a directory in debugfs with the given name.
542 : *
543 : * This function will return a pointer to a dentry if it succeeds. This
544 : * pointer must be passed to the debugfs_remove() function when the file is
545 : * to be removed (no automatic cleanup happens if your module is unloaded,
546 : * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
547 : * returned.
548 : *
549 : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
550 : * returned.
551 : */
552 130 : struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
553 : {
554 130 : struct dentry *dentry = start_creating(name, parent);
555 130 : struct inode *inode;
556 :
557 130 : if (IS_ERR(dentry))
558 : return dentry;
559 :
560 130 : if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
561 0 : failed_creating(dentry);
562 0 : return ERR_PTR(-EPERM);
563 : }
564 :
565 130 : inode = debugfs_get_inode(dentry->d_sb);
566 130 : if (unlikely(!inode)) {
567 0 : pr_err("out of free dentries, can not create directory '%s'\n",
568 : name);
569 0 : return failed_creating(dentry);
570 : }
571 :
572 130 : inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
573 130 : inode->i_op = &debugfs_dir_inode_operations;
574 130 : inode->i_fop = &simple_dir_operations;
575 :
576 : /* directory inodes start off with i_nlink == 2 (for "." entry) */
577 130 : inc_nlink(inode);
578 130 : d_instantiate(dentry, inode);
579 130 : inc_nlink(d_inode(dentry->d_parent));
580 130 : fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
581 130 : return end_creating(dentry);
582 : }
583 : EXPORT_SYMBOL_GPL(debugfs_create_dir);
584 :
585 : /**
586 : * debugfs_create_automount - create automount point in the debugfs filesystem
587 : * @name: a pointer to a string containing the name of the file to create.
588 : * @parent: a pointer to the parent dentry for this file. This should be a
589 : * directory dentry if set. If this parameter is NULL, then the
590 : * file will be created in the root of the debugfs filesystem.
591 : * @f: function to be called when pathname resolution steps on that one.
592 : * @data: opaque argument to pass to f().
593 : *
594 : * @f should return what ->d_automount() would.
595 : */
596 1 : struct dentry *debugfs_create_automount(const char *name,
597 : struct dentry *parent,
598 : debugfs_automount_t f,
599 : void *data)
600 : {
601 1 : struct dentry *dentry = start_creating(name, parent);
602 1 : struct inode *inode;
603 :
604 1 : if (IS_ERR(dentry))
605 : return dentry;
606 :
607 1 : if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
608 0 : failed_creating(dentry);
609 0 : return ERR_PTR(-EPERM);
610 : }
611 :
612 1 : inode = debugfs_get_inode(dentry->d_sb);
613 1 : if (unlikely(!inode)) {
614 0 : pr_err("out of free dentries, can not create automount '%s'\n",
615 : name);
616 0 : return failed_creating(dentry);
617 : }
618 :
619 1 : make_empty_dir_inode(inode);
620 1 : inode->i_flags |= S_AUTOMOUNT;
621 1 : inode->i_private = data;
622 1 : dentry->d_fsdata = (void *)f;
623 : /* directory inodes start off with i_nlink == 2 (for "." entry) */
624 1 : inc_nlink(inode);
625 1 : d_instantiate(dentry, inode);
626 1 : inc_nlink(d_inode(dentry->d_parent));
627 1 : fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
628 1 : return end_creating(dentry);
629 : }
630 : EXPORT_SYMBOL(debugfs_create_automount);
631 :
632 : /**
633 : * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
634 : * @name: a pointer to a string containing the name of the symbolic link to
635 : * create.
636 : * @parent: a pointer to the parent dentry for this symbolic link. This
637 : * should be a directory dentry if set. If this parameter is NULL,
638 : * then the symbolic link will be created in the root of the debugfs
639 : * filesystem.
640 : * @target: a pointer to a string containing the path to the target of the
641 : * symbolic link.
642 : *
643 : * This function creates a symbolic link with the given name in debugfs that
644 : * links to the given target path.
645 : *
646 : * This function will return a pointer to a dentry if it succeeds. This
647 : * pointer must be passed to the debugfs_remove() function when the symbolic
648 : * link is to be removed (no automatic cleanup happens if your module is
649 : * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
650 : * will be returned.
651 : *
652 : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
653 : * returned.
654 : */
655 955 : struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
656 : const char *target)
657 : {
658 955 : struct dentry *dentry;
659 955 : struct inode *inode;
660 955 : char *link = kstrdup(target, GFP_KERNEL);
661 955 : if (!link)
662 955 : return ERR_PTR(-ENOMEM);
663 :
664 955 : dentry = start_creating(name, parent);
665 955 : if (IS_ERR(dentry)) {
666 0 : kfree(link);
667 0 : return dentry;
668 : }
669 :
670 955 : inode = debugfs_get_inode(dentry->d_sb);
671 955 : if (unlikely(!inode)) {
672 0 : pr_err("out of free dentries, can not create symlink '%s'\n",
673 : name);
674 0 : kfree(link);
675 0 : return failed_creating(dentry);
676 : }
677 955 : inode->i_mode = S_IFLNK | S_IRWXUGO;
678 955 : inode->i_op = &debugfs_symlink_inode_operations;
679 955 : inode->i_link = link;
680 955 : d_instantiate(dentry, inode);
681 955 : return end_creating(dentry);
682 : }
683 : EXPORT_SYMBOL_GPL(debugfs_create_symlink);
684 :
685 0 : static void __debugfs_file_removed(struct dentry *dentry)
686 : {
687 0 : struct debugfs_fsdata *fsd;
688 :
689 : /*
690 : * Paired with the closing smp_mb() implied by a successful
691 : * cmpxchg() in debugfs_file_get(): either
692 : * debugfs_file_get() must see a dead dentry or we must see a
693 : * debugfs_fsdata instance at ->d_fsdata here (or both).
694 : */
695 0 : smp_mb();
696 0 : fsd = READ_ONCE(dentry->d_fsdata);
697 0 : if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
698 : return;
699 0 : if (!refcount_dec_and_test(&fsd->active_users))
700 0 : wait_for_completion(&fsd->active_users_drained);
701 : }
702 :
703 0 : static void remove_one(struct dentry *victim)
704 : {
705 0 : if (d_is_reg(victim))
706 0 : __debugfs_file_removed(victim);
707 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
708 0 : }
709 :
710 : /**
711 : * debugfs_remove - recursively removes a directory
712 : * @dentry: a pointer to a the dentry of the directory to be removed. If this
713 : * parameter is NULL or an error value, nothing will be done.
714 : *
715 : * This function recursively removes a directory tree in debugfs that
716 : * was previously created with a call to another debugfs function
717 : * (like debugfs_create_file() or variants thereof.)
718 : *
719 : * This function is required to be called in order for the file to be
720 : * removed, no automatic cleanup of files will happen when a module is
721 : * removed, you are responsible here.
722 : */
723 0 : void debugfs_remove(struct dentry *dentry)
724 : {
725 0 : if (IS_ERR_OR_NULL(dentry))
726 : return;
727 :
728 0 : simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
729 0 : simple_recursive_removal(dentry, remove_one);
730 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
731 : }
732 : EXPORT_SYMBOL_GPL(debugfs_remove);
733 :
734 : /**
735 : * debugfs_rename - rename a file/directory in the debugfs filesystem
736 : * @old_dir: a pointer to the parent dentry for the renamed object. This
737 : * should be a directory dentry.
738 : * @old_dentry: dentry of an object to be renamed.
739 : * @new_dir: a pointer to the parent dentry where the object should be
740 : * moved. This should be a directory dentry.
741 : * @new_name: a pointer to a string containing the target name.
742 : *
743 : * This function renames a file/directory in debugfs. The target must not
744 : * exist for rename to succeed.
745 : *
746 : * This function will return a pointer to old_dentry (which is updated to
747 : * reflect renaming) if it succeeds. If an error occurs, %NULL will be
748 : * returned.
749 : *
750 : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
751 : * returned.
752 : */
753 0 : struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
754 : struct dentry *new_dir, const char *new_name)
755 : {
756 0 : int error;
757 0 : struct dentry *dentry = NULL, *trap;
758 0 : struct name_snapshot old_name;
759 :
760 0 : if (IS_ERR(old_dir))
761 : return old_dir;
762 0 : if (IS_ERR(new_dir))
763 : return new_dir;
764 0 : if (IS_ERR_OR_NULL(old_dentry))
765 : return old_dentry;
766 :
767 0 : trap = lock_rename(new_dir, old_dir);
768 : /* Source or destination directories don't exist? */
769 0 : if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
770 0 : goto exit;
771 : /* Source does not exist, cyclic rename, or mountpoint? */
772 0 : if (d_really_is_negative(old_dentry) || old_dentry == trap ||
773 0 : d_mountpoint(old_dentry))
774 0 : goto exit;
775 0 : dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
776 : /* Lookup failed, cyclic rename or target exists? */
777 0 : if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
778 0 : goto exit;
779 :
780 0 : take_dentry_name_snapshot(&old_name, old_dentry);
781 :
782 0 : error = simple_rename(&init_user_ns, d_inode(old_dir), old_dentry,
783 : d_inode(new_dir), dentry, 0);
784 0 : if (error) {
785 0 : release_dentry_name_snapshot(&old_name);
786 0 : goto exit;
787 : }
788 0 : d_move(old_dentry, dentry);
789 0 : fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
790 0 : d_is_dir(old_dentry),
791 : NULL, old_dentry);
792 0 : release_dentry_name_snapshot(&old_name);
793 0 : unlock_rename(new_dir, old_dir);
794 0 : dput(dentry);
795 0 : return old_dentry;
796 0 : exit:
797 0 : if (dentry && !IS_ERR(dentry))
798 0 : dput(dentry);
799 0 : unlock_rename(new_dir, old_dir);
800 0 : if (IS_ERR(dentry))
801 0 : return dentry;
802 0 : return ERR_PTR(-EINVAL);
803 : }
804 : EXPORT_SYMBOL_GPL(debugfs_rename);
805 :
806 : /**
807 : * debugfs_initialized - Tells whether debugfs has been registered
808 : */
809 2068 : bool debugfs_initialized(void)
810 : {
811 2068 : return debugfs_registered;
812 : }
813 : EXPORT_SYMBOL_GPL(debugfs_initialized);
814 :
815 0 : static int __init debugfs_kernel(char *str)
816 : {
817 0 : if (str) {
818 0 : if (!strcmp(str, "on"))
819 0 : debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
820 0 : else if (!strcmp(str, "no-mount"))
821 0 : debugfs_allow = DEBUGFS_ALLOW_API;
822 0 : else if (!strcmp(str, "off"))
823 0 : debugfs_allow = 0;
824 : }
825 :
826 0 : return 0;
827 : }
828 : early_param("debugfs", debugfs_kernel);
829 1 : static int __init debugfs_init(void)
830 : {
831 1 : int retval;
832 :
833 1 : if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
834 : return -EPERM;
835 :
836 1 : retval = sysfs_create_mount_point(kernel_kobj, "debug");
837 1 : if (retval)
838 : return retval;
839 :
840 1 : retval = register_filesystem(&debug_fs_type);
841 1 : if (retval)
842 0 : sysfs_remove_mount_point(kernel_kobj, "debug");
843 : else
844 1 : debugfs_registered = true;
845 :
846 : return retval;
847 : }
848 : core_initcall(debugfs_init);
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