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 __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 | */ |
45 | static int debugfs_setattr(struct mnt_idmap *idmap, |
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(what: LOCKDOWN_DEBUGFS); |
52 | if (ret) |
53 | return ret; |
54 | } |
55 | return simple_setattr(&nop_mnt_idmap, dentry, ia); |
56 | } |
57 | |
58 | static const struct inode_operations debugfs_file_inode_operations = { |
59 | .setattr = debugfs_setattr, |
60 | }; |
61 | static const struct inode_operations debugfs_dir_inode_operations = { |
62 | .lookup = simple_lookup, |
63 | .setattr = debugfs_setattr, |
64 | }; |
65 | static const struct inode_operations debugfs_symlink_inode_operations = { |
66 | .get_link = simple_get_link, |
67 | .setattr = debugfs_setattr, |
68 | }; |
69 | |
70 | static 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 | simple_inode_init_ts(inode); |
76 | } |
77 | return inode; |
78 | } |
79 | |
80 | struct debugfs_mount_opts { |
81 | kuid_t uid; |
82 | kgid_t gid; |
83 | umode_t mode; |
84 | /* Opt_* bitfield. */ |
85 | unsigned int opts; |
86 | }; |
87 | |
88 | enum { |
89 | Opt_uid, |
90 | Opt_gid, |
91 | Opt_mode, |
92 | Opt_err |
93 | }; |
94 | |
95 | static const match_table_t tokens = { |
96 | {Opt_uid, "uid=%u" }, |
97 | {Opt_gid, "gid=%u" }, |
98 | {Opt_mode, "mode=%o" }, |
99 | {Opt_err, NULL} |
100 | }; |
101 | |
102 | struct debugfs_fs_info { |
103 | struct debugfs_mount_opts mount_opts; |
104 | }; |
105 | |
106 | static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) |
107 | { |
108 | substring_t args[MAX_OPT_ARGS]; |
109 | int option; |
110 | int token; |
111 | kuid_t uid; |
112 | kgid_t gid; |
113 | char *p; |
114 | |
115 | opts->opts = 0; |
116 | opts->mode = DEBUGFS_DEFAULT_MODE; |
117 | |
118 | while ((p = strsep(&data, "," )) != NULL) { |
119 | if (!*p) |
120 | continue; |
121 | |
122 | token = match_token(p, table: tokens, args); |
123 | switch (token) { |
124 | case Opt_uid: |
125 | if (match_int(&args[0], result: &option)) |
126 | return -EINVAL; |
127 | uid = make_kuid(current_user_ns(), uid: option); |
128 | if (!uid_valid(uid)) |
129 | return -EINVAL; |
130 | opts->uid = uid; |
131 | break; |
132 | case Opt_gid: |
133 | if (match_int(&args[0], result: &option)) |
134 | return -EINVAL; |
135 | gid = make_kgid(current_user_ns(), gid: option); |
136 | if (!gid_valid(gid)) |
137 | return -EINVAL; |
138 | opts->gid = gid; |
139 | break; |
140 | case Opt_mode: |
141 | if (match_octal(&args[0], result: &option)) |
142 | return -EINVAL; |
143 | opts->mode = option & S_IALLUGO; |
144 | break; |
145 | /* |
146 | * We might like to report bad mount options here; |
147 | * but traditionally debugfs has ignored all mount options |
148 | */ |
149 | } |
150 | |
151 | opts->opts |= BIT(token); |
152 | } |
153 | |
154 | return 0; |
155 | } |
156 | |
157 | static void _debugfs_apply_options(struct super_block *sb, bool remount) |
158 | { |
159 | struct debugfs_fs_info *fsi = sb->s_fs_info; |
160 | struct inode *inode = d_inode(dentry: sb->s_root); |
161 | struct debugfs_mount_opts *opts = &fsi->mount_opts; |
162 | |
163 | /* |
164 | * On remount, only reset mode/uid/gid if they were provided as mount |
165 | * options. |
166 | */ |
167 | |
168 | if (!remount || opts->opts & BIT(Opt_mode)) { |
169 | inode->i_mode &= ~S_IALLUGO; |
170 | inode->i_mode |= opts->mode; |
171 | } |
172 | |
173 | if (!remount || opts->opts & BIT(Opt_uid)) |
174 | inode->i_uid = opts->uid; |
175 | |
176 | if (!remount || opts->opts & BIT(Opt_gid)) |
177 | inode->i_gid = opts->gid; |
178 | } |
179 | |
180 | static void debugfs_apply_options(struct super_block *sb) |
181 | { |
182 | _debugfs_apply_options(sb, remount: false); |
183 | } |
184 | |
185 | static void debugfs_apply_options_remount(struct super_block *sb) |
186 | { |
187 | _debugfs_apply_options(sb, remount: true); |
188 | } |
189 | |
190 | static int debugfs_remount(struct super_block *sb, int *flags, char *data) |
191 | { |
192 | int err; |
193 | struct debugfs_fs_info *fsi = sb->s_fs_info; |
194 | |
195 | sync_filesystem(sb); |
196 | err = debugfs_parse_options(data, opts: &fsi->mount_opts); |
197 | if (err) |
198 | goto fail; |
199 | |
200 | debugfs_apply_options_remount(sb); |
201 | |
202 | fail: |
203 | return err; |
204 | } |
205 | |
206 | static int debugfs_show_options(struct seq_file *m, struct dentry *root) |
207 | { |
208 | struct debugfs_fs_info *fsi = root->d_sb->s_fs_info; |
209 | struct debugfs_mount_opts *opts = &fsi->mount_opts; |
210 | |
211 | if (!uid_eq(left: opts->uid, GLOBAL_ROOT_UID)) |
212 | seq_printf(m, ",uid=%u" , |
213 | from_kuid_munged(&init_user_ns, opts->uid)); |
214 | if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) |
215 | seq_printf(m, ",gid=%u" , |
216 | from_kgid_munged(&init_user_ns, opts->gid)); |
217 | if (opts->mode != DEBUGFS_DEFAULT_MODE) |
218 | seq_printf(m, ",mode=%o" , opts->mode); |
219 | |
220 | return 0; |
221 | } |
222 | |
223 | static void debugfs_free_inode(struct inode *inode) |
224 | { |
225 | if (S_ISLNK(inode->i_mode)) |
226 | kfree(objp: inode->i_link); |
227 | free_inode_nonrcu(inode); |
228 | } |
229 | |
230 | static const struct super_operations debugfs_super_operations = { |
231 | .statfs = simple_statfs, |
232 | .remount_fs = debugfs_remount, |
233 | .show_options = debugfs_show_options, |
234 | .free_inode = debugfs_free_inode, |
235 | }; |
236 | |
237 | static void debugfs_release_dentry(struct dentry *dentry) |
238 | { |
239 | struct debugfs_fsdata *fsd = dentry->d_fsdata; |
240 | |
241 | if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) |
242 | return; |
243 | |
244 | /* check it wasn't a dir (no fsdata) or automount (no real_fops) */ |
245 | if (fsd && fsd->real_fops) { |
246 | WARN_ON(!list_empty(&fsd->cancellations)); |
247 | mutex_destroy(lock: &fsd->cancellations_mtx); |
248 | } |
249 | |
250 | kfree(objp: fsd); |
251 | } |
252 | |
253 | static struct vfsmount *debugfs_automount(struct path *path) |
254 | { |
255 | struct debugfs_fsdata *fsd = path->dentry->d_fsdata; |
256 | |
257 | return fsd->automount(path->dentry, d_inode(dentry: path->dentry)->i_private); |
258 | } |
259 | |
260 | static const struct dentry_operations debugfs_dops = { |
261 | .d_delete = always_delete_dentry, |
262 | .d_release = debugfs_release_dentry, |
263 | .d_automount = debugfs_automount, |
264 | }; |
265 | |
266 | static int debug_fill_super(struct super_block *sb, void *data, int silent) |
267 | { |
268 | static const struct tree_descr debug_files[] = {{"" }}; |
269 | struct debugfs_fs_info *fsi; |
270 | int err; |
271 | |
272 | fsi = kzalloc(size: sizeof(struct debugfs_fs_info), GFP_KERNEL); |
273 | sb->s_fs_info = fsi; |
274 | if (!fsi) { |
275 | err = -ENOMEM; |
276 | goto fail; |
277 | } |
278 | |
279 | err = debugfs_parse_options(data, opts: &fsi->mount_opts); |
280 | if (err) |
281 | goto fail; |
282 | |
283 | err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); |
284 | if (err) |
285 | goto fail; |
286 | |
287 | sb->s_op = &debugfs_super_operations; |
288 | sb->s_d_op = &debugfs_dops; |
289 | |
290 | debugfs_apply_options(sb); |
291 | |
292 | return 0; |
293 | |
294 | fail: |
295 | kfree(objp: fsi); |
296 | sb->s_fs_info = NULL; |
297 | return err; |
298 | } |
299 | |
300 | static struct dentry *debug_mount(struct file_system_type *fs_type, |
301 | int flags, const char *dev_name, |
302 | void *data) |
303 | { |
304 | if (!(debugfs_allow & DEBUGFS_ALLOW_API)) |
305 | return ERR_PTR(error: -EPERM); |
306 | |
307 | return mount_single(fs_type, flags, data, fill_super: debug_fill_super); |
308 | } |
309 | |
310 | static struct file_system_type debug_fs_type = { |
311 | .owner = THIS_MODULE, |
312 | .name = "debugfs" , |
313 | .mount = debug_mount, |
314 | .kill_sb = kill_litter_super, |
315 | }; |
316 | MODULE_ALIAS_FS("debugfs" ); |
317 | |
318 | /** |
319 | * debugfs_lookup() - look up an existing debugfs file |
320 | * @name: a pointer to a string containing the name of the file to look up. |
321 | * @parent: a pointer to the parent dentry of the file. |
322 | * |
323 | * This function will return a pointer to a dentry if it succeeds. If the file |
324 | * doesn't exist or an error occurs, %NULL will be returned. The returned |
325 | * dentry must be passed to dput() when it is no longer needed. |
326 | * |
327 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
328 | * returned. |
329 | */ |
330 | struct dentry *debugfs_lookup(const char *name, struct dentry *parent) |
331 | { |
332 | struct dentry *dentry; |
333 | |
334 | if (!debugfs_initialized() || IS_ERR_OR_NULL(ptr: name) || IS_ERR(ptr: parent)) |
335 | return NULL; |
336 | |
337 | if (!parent) |
338 | parent = debugfs_mount->mnt_root; |
339 | |
340 | dentry = lookup_positive_unlocked(name, parent, strlen(name)); |
341 | if (IS_ERR(ptr: dentry)) |
342 | return NULL; |
343 | return dentry; |
344 | } |
345 | EXPORT_SYMBOL_GPL(debugfs_lookup); |
346 | |
347 | static struct dentry *start_creating(const char *name, struct dentry *parent) |
348 | { |
349 | struct dentry *dentry; |
350 | int error; |
351 | |
352 | if (!(debugfs_allow & DEBUGFS_ALLOW_API)) |
353 | return ERR_PTR(error: -EPERM); |
354 | |
355 | if (!debugfs_initialized()) |
356 | return ERR_PTR(error: -ENOENT); |
357 | |
358 | pr_debug("creating file '%s'\n" , name); |
359 | |
360 | if (IS_ERR(ptr: parent)) |
361 | return parent; |
362 | |
363 | error = simple_pin_fs(&debug_fs_type, mount: &debugfs_mount, |
364 | count: &debugfs_mount_count); |
365 | if (error) { |
366 | pr_err("Unable to pin filesystem for file '%s'\n" , name); |
367 | return ERR_PTR(error); |
368 | } |
369 | |
370 | /* If the parent is not specified, we create it in the root. |
371 | * We need the root dentry to do this, which is in the super |
372 | * block. A pointer to that is in the struct vfsmount that we |
373 | * have around. |
374 | */ |
375 | if (!parent) |
376 | parent = debugfs_mount->mnt_root; |
377 | |
378 | inode_lock(inode: d_inode(dentry: parent)); |
379 | if (unlikely(IS_DEADDIR(d_inode(parent)))) |
380 | dentry = ERR_PTR(error: -ENOENT); |
381 | else |
382 | dentry = lookup_one_len(name, parent, strlen(name)); |
383 | if (!IS_ERR(ptr: dentry) && d_really_is_positive(dentry)) { |
384 | if (d_is_dir(dentry)) |
385 | pr_err("Directory '%s' with parent '%s' already present!\n" , |
386 | name, parent->d_name.name); |
387 | else |
388 | pr_err("File '%s' in directory '%s' already present!\n" , |
389 | name, parent->d_name.name); |
390 | dput(dentry); |
391 | dentry = ERR_PTR(error: -EEXIST); |
392 | } |
393 | |
394 | if (IS_ERR(ptr: dentry)) { |
395 | inode_unlock(inode: d_inode(dentry: parent)); |
396 | simple_release_fs(mount: &debugfs_mount, count: &debugfs_mount_count); |
397 | } |
398 | |
399 | return dentry; |
400 | } |
401 | |
402 | static struct dentry *failed_creating(struct dentry *dentry) |
403 | { |
404 | inode_unlock(inode: d_inode(dentry: dentry->d_parent)); |
405 | dput(dentry); |
406 | simple_release_fs(mount: &debugfs_mount, count: &debugfs_mount_count); |
407 | return ERR_PTR(error: -ENOMEM); |
408 | } |
409 | |
410 | static struct dentry *end_creating(struct dentry *dentry) |
411 | { |
412 | inode_unlock(inode: d_inode(dentry: dentry->d_parent)); |
413 | return dentry; |
414 | } |
415 | |
416 | static struct dentry *__debugfs_create_file(const char *name, umode_t mode, |
417 | struct dentry *parent, void *data, |
418 | const struct file_operations *proxy_fops, |
419 | const struct file_operations *real_fops) |
420 | { |
421 | struct dentry *dentry; |
422 | struct inode *inode; |
423 | |
424 | if (!(mode & S_IFMT)) |
425 | mode |= S_IFREG; |
426 | BUG_ON(!S_ISREG(mode)); |
427 | dentry = start_creating(name, parent); |
428 | |
429 | if (IS_ERR(ptr: dentry)) |
430 | return dentry; |
431 | |
432 | if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { |
433 | failed_creating(dentry); |
434 | return ERR_PTR(error: -EPERM); |
435 | } |
436 | |
437 | inode = debugfs_get_inode(sb: dentry->d_sb); |
438 | if (unlikely(!inode)) { |
439 | pr_err("out of free dentries, can not create file '%s'\n" , |
440 | name); |
441 | return failed_creating(dentry); |
442 | } |
443 | |
444 | inode->i_mode = mode; |
445 | inode->i_private = data; |
446 | |
447 | inode->i_op = &debugfs_file_inode_operations; |
448 | inode->i_fop = proxy_fops; |
449 | dentry->d_fsdata = (void *)((unsigned long)real_fops | |
450 | DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); |
451 | |
452 | d_instantiate(dentry, inode); |
453 | fsnotify_create(dir: d_inode(dentry: dentry->d_parent), dentry); |
454 | return end_creating(dentry); |
455 | } |
456 | |
457 | /** |
458 | * debugfs_create_file - create a file in the debugfs filesystem |
459 | * @name: a pointer to a string containing the name of the file to create. |
460 | * @mode: the permission that the file should have. |
461 | * @parent: a pointer to the parent dentry for this file. This should be a |
462 | * directory dentry if set. If this parameter is NULL, then the |
463 | * file will be created in the root of the debugfs filesystem. |
464 | * @data: a pointer to something that the caller will want to get to later |
465 | * on. The inode.i_private pointer will point to this value on |
466 | * the open() call. |
467 | * @fops: a pointer to a struct file_operations that should be used for |
468 | * this file. |
469 | * |
470 | * This is the basic "create a file" function for debugfs. It allows for a |
471 | * wide range of flexibility in creating a file, or a directory (if you want |
472 | * to create a directory, the debugfs_create_dir() function is |
473 | * recommended to be used instead.) |
474 | * |
475 | * This function will return a pointer to a dentry if it succeeds. This |
476 | * pointer must be passed to the debugfs_remove() function when the file is |
477 | * to be removed (no automatic cleanup happens if your module is unloaded, |
478 | * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be |
479 | * returned. |
480 | * |
481 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
482 | * returned. |
483 | * |
484 | * NOTE: it's expected that most callers should _ignore_ the errors returned |
485 | * by this function. Other debugfs functions handle the fact that the "dentry" |
486 | * passed to them could be an error and they don't crash in that case. |
487 | * Drivers should generally work fine even if debugfs fails to init anyway. |
488 | */ |
489 | struct dentry *debugfs_create_file(const char *name, umode_t mode, |
490 | struct dentry *parent, void *data, |
491 | const struct file_operations *fops) |
492 | { |
493 | |
494 | return __debugfs_create_file(name, mode, parent, data, |
495 | proxy_fops: fops ? &debugfs_full_proxy_file_operations : |
496 | &debugfs_noop_file_operations, |
497 | real_fops: fops); |
498 | } |
499 | EXPORT_SYMBOL_GPL(debugfs_create_file); |
500 | |
501 | /** |
502 | * debugfs_create_file_unsafe - create a file in the debugfs filesystem |
503 | * @name: a pointer to a string containing the name of the file to create. |
504 | * @mode: the permission that the file should have. |
505 | * @parent: a pointer to the parent dentry for this file. This should be a |
506 | * directory dentry if set. If this parameter is NULL, then the |
507 | * file will be created in the root of the debugfs filesystem. |
508 | * @data: a pointer to something that the caller will want to get to later |
509 | * on. The inode.i_private pointer will point to this value on |
510 | * the open() call. |
511 | * @fops: a pointer to a struct file_operations that should be used for |
512 | * this file. |
513 | * |
514 | * debugfs_create_file_unsafe() is completely analogous to |
515 | * debugfs_create_file(), the only difference being that the fops |
516 | * handed it will not get protected against file removals by the |
517 | * debugfs core. |
518 | * |
519 | * It is your responsibility to protect your struct file_operation |
520 | * methods against file removals by means of debugfs_file_get() |
521 | * and debugfs_file_put(). ->open() is still protected by |
522 | * debugfs though. |
523 | * |
524 | * Any struct file_operations defined by means of |
525 | * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and |
526 | * thus, may be used here. |
527 | */ |
528 | struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, |
529 | struct dentry *parent, void *data, |
530 | const struct file_operations *fops) |
531 | { |
532 | |
533 | return __debugfs_create_file(name, mode, parent, data, |
534 | proxy_fops: fops ? &debugfs_open_proxy_file_operations : |
535 | &debugfs_noop_file_operations, |
536 | real_fops: fops); |
537 | } |
538 | EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); |
539 | |
540 | /** |
541 | * debugfs_create_file_size - create a file in the debugfs filesystem |
542 | * @name: a pointer to a string containing the name of the file to create. |
543 | * @mode: the permission that the file should have. |
544 | * @parent: a pointer to the parent dentry for this file. This should be a |
545 | * directory dentry if set. If this parameter is NULL, then the |
546 | * file will be created in the root of the debugfs filesystem. |
547 | * @data: a pointer to something that the caller will want to get to later |
548 | * on. The inode.i_private pointer will point to this value on |
549 | * the open() call. |
550 | * @fops: a pointer to a struct file_operations that should be used for |
551 | * this file. |
552 | * @file_size: initial file size |
553 | * |
554 | * This is the basic "create a file" function for debugfs. It allows for a |
555 | * wide range of flexibility in creating a file, or a directory (if you want |
556 | * to create a directory, the debugfs_create_dir() function is |
557 | * recommended to be used instead.) |
558 | */ |
559 | void debugfs_create_file_size(const char *name, umode_t mode, |
560 | struct dentry *parent, void *data, |
561 | const struct file_operations *fops, |
562 | loff_t file_size) |
563 | { |
564 | struct dentry *de = debugfs_create_file(name, mode, parent, data, fops); |
565 | |
566 | if (!IS_ERR(ptr: de)) |
567 | d_inode(dentry: de)->i_size = file_size; |
568 | } |
569 | EXPORT_SYMBOL_GPL(debugfs_create_file_size); |
570 | |
571 | /** |
572 | * debugfs_create_dir - create a directory in the debugfs filesystem |
573 | * @name: a pointer to a string containing the name of the directory to |
574 | * create. |
575 | * @parent: a pointer to the parent dentry for this file. This should be a |
576 | * directory dentry if set. If this parameter is NULL, then the |
577 | * directory will be created in the root of the debugfs filesystem. |
578 | * |
579 | * This function creates a directory in debugfs with the given name. |
580 | * |
581 | * This function will return a pointer to a dentry if it succeeds. This |
582 | * pointer must be passed to the debugfs_remove() function when the file is |
583 | * to be removed (no automatic cleanup happens if your module is unloaded, |
584 | * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be |
585 | * returned. |
586 | * |
587 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
588 | * returned. |
589 | * |
590 | * NOTE: it's expected that most callers should _ignore_ the errors returned |
591 | * by this function. Other debugfs functions handle the fact that the "dentry" |
592 | * passed to them could be an error and they don't crash in that case. |
593 | * Drivers should generally work fine even if debugfs fails to init anyway. |
594 | */ |
595 | struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) |
596 | { |
597 | struct dentry *dentry = start_creating(name, parent); |
598 | struct inode *inode; |
599 | |
600 | if (IS_ERR(ptr: dentry)) |
601 | return dentry; |
602 | |
603 | if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { |
604 | failed_creating(dentry); |
605 | return ERR_PTR(error: -EPERM); |
606 | } |
607 | |
608 | inode = debugfs_get_inode(sb: dentry->d_sb); |
609 | if (unlikely(!inode)) { |
610 | pr_err("out of free dentries, can not create directory '%s'\n" , |
611 | name); |
612 | return failed_creating(dentry); |
613 | } |
614 | |
615 | inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; |
616 | inode->i_op = &debugfs_dir_inode_operations; |
617 | inode->i_fop = &simple_dir_operations; |
618 | |
619 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ |
620 | inc_nlink(inode); |
621 | d_instantiate(dentry, inode); |
622 | inc_nlink(inode: d_inode(dentry: dentry->d_parent)); |
623 | fsnotify_mkdir(dir: d_inode(dentry: dentry->d_parent), dentry); |
624 | return end_creating(dentry); |
625 | } |
626 | EXPORT_SYMBOL_GPL(debugfs_create_dir); |
627 | |
628 | /** |
629 | * debugfs_create_automount - create automount point in the debugfs filesystem |
630 | * @name: a pointer to a string containing the name of the file to create. |
631 | * @parent: a pointer to the parent dentry for this file. This should be a |
632 | * directory dentry if set. If this parameter is NULL, then the |
633 | * file will be created in the root of the debugfs filesystem. |
634 | * @f: function to be called when pathname resolution steps on that one. |
635 | * @data: opaque argument to pass to f(). |
636 | * |
637 | * @f should return what ->d_automount() would. |
638 | */ |
639 | struct dentry *debugfs_create_automount(const char *name, |
640 | struct dentry *parent, |
641 | debugfs_automount_t f, |
642 | void *data) |
643 | { |
644 | struct dentry *dentry = start_creating(name, parent); |
645 | struct debugfs_fsdata *fsd; |
646 | struct inode *inode; |
647 | |
648 | if (IS_ERR(ptr: dentry)) |
649 | return dentry; |
650 | |
651 | fsd = kzalloc(size: sizeof(*fsd), GFP_KERNEL); |
652 | if (!fsd) { |
653 | failed_creating(dentry); |
654 | return ERR_PTR(error: -ENOMEM); |
655 | } |
656 | |
657 | fsd->automount = f; |
658 | |
659 | if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { |
660 | failed_creating(dentry); |
661 | kfree(objp: fsd); |
662 | return ERR_PTR(error: -EPERM); |
663 | } |
664 | |
665 | inode = debugfs_get_inode(sb: dentry->d_sb); |
666 | if (unlikely(!inode)) { |
667 | pr_err("out of free dentries, can not create automount '%s'\n" , |
668 | name); |
669 | kfree(objp: fsd); |
670 | return failed_creating(dentry); |
671 | } |
672 | |
673 | make_empty_dir_inode(inode); |
674 | inode->i_flags |= S_AUTOMOUNT; |
675 | inode->i_private = data; |
676 | dentry->d_fsdata = fsd; |
677 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ |
678 | inc_nlink(inode); |
679 | d_instantiate(dentry, inode); |
680 | inc_nlink(inode: d_inode(dentry: dentry->d_parent)); |
681 | fsnotify_mkdir(dir: d_inode(dentry: dentry->d_parent), dentry); |
682 | return end_creating(dentry); |
683 | } |
684 | EXPORT_SYMBOL(debugfs_create_automount); |
685 | |
686 | /** |
687 | * debugfs_create_symlink- create a symbolic link in the debugfs filesystem |
688 | * @name: a pointer to a string containing the name of the symbolic link to |
689 | * create. |
690 | * @parent: a pointer to the parent dentry for this symbolic link. This |
691 | * should be a directory dentry if set. If this parameter is NULL, |
692 | * then the symbolic link will be created in the root of the debugfs |
693 | * filesystem. |
694 | * @target: a pointer to a string containing the path to the target of the |
695 | * symbolic link. |
696 | * |
697 | * This function creates a symbolic link with the given name in debugfs that |
698 | * links to the given target path. |
699 | * |
700 | * This function will return a pointer to a dentry if it succeeds. This |
701 | * pointer must be passed to the debugfs_remove() function when the symbolic |
702 | * link is to be removed (no automatic cleanup happens if your module is |
703 | * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR) |
704 | * will be returned. |
705 | * |
706 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
707 | * returned. |
708 | */ |
709 | struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, |
710 | const char *target) |
711 | { |
712 | struct dentry *dentry; |
713 | struct inode *inode; |
714 | char *link = kstrdup(s: target, GFP_KERNEL); |
715 | if (!link) |
716 | return ERR_PTR(error: -ENOMEM); |
717 | |
718 | dentry = start_creating(name, parent); |
719 | if (IS_ERR(ptr: dentry)) { |
720 | kfree(objp: link); |
721 | return dentry; |
722 | } |
723 | |
724 | inode = debugfs_get_inode(sb: dentry->d_sb); |
725 | if (unlikely(!inode)) { |
726 | pr_err("out of free dentries, can not create symlink '%s'\n" , |
727 | name); |
728 | kfree(objp: link); |
729 | return failed_creating(dentry); |
730 | } |
731 | inode->i_mode = S_IFLNK | S_IRWXUGO; |
732 | inode->i_op = &debugfs_symlink_inode_operations; |
733 | inode->i_link = link; |
734 | d_instantiate(dentry, inode); |
735 | return end_creating(dentry); |
736 | } |
737 | EXPORT_SYMBOL_GPL(debugfs_create_symlink); |
738 | |
739 | static void __debugfs_file_removed(struct dentry *dentry) |
740 | { |
741 | struct debugfs_fsdata *fsd; |
742 | |
743 | /* |
744 | * Paired with the closing smp_mb() implied by a successful |
745 | * cmpxchg() in debugfs_file_get(): either |
746 | * debugfs_file_get() must see a dead dentry or we must see a |
747 | * debugfs_fsdata instance at ->d_fsdata here (or both). |
748 | */ |
749 | smp_mb(); |
750 | fsd = READ_ONCE(dentry->d_fsdata); |
751 | if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) |
752 | return; |
753 | |
754 | /* if this was the last reference, we're done */ |
755 | if (refcount_dec_and_test(r: &fsd->active_users)) |
756 | return; |
757 | |
758 | /* |
759 | * If there's still a reference, the code that obtained it can |
760 | * be in different states: |
761 | * - The common case of not using cancellations, or already |
762 | * after debugfs_leave_cancellation(), where we just need |
763 | * to wait for debugfs_file_put() which signals the completion; |
764 | * - inside a cancellation section, i.e. between |
765 | * debugfs_enter_cancellation() and debugfs_leave_cancellation(), |
766 | * in which case we need to trigger the ->cancel() function, |
767 | * and then wait for debugfs_file_put() just like in the |
768 | * previous case; |
769 | * - before debugfs_enter_cancellation() (but obviously after |
770 | * debugfs_file_get()), in which case we may not see the |
771 | * cancellation in the list on the first round of the loop, |
772 | * but debugfs_enter_cancellation() signals the completion |
773 | * after adding it, so this code gets woken up to call the |
774 | * ->cancel() function. |
775 | */ |
776 | while (refcount_read(r: &fsd->active_users)) { |
777 | struct debugfs_cancellation *c; |
778 | |
779 | /* |
780 | * Lock the cancellations. Note that the cancellations |
781 | * structs are meant to be on the stack, so we need to |
782 | * ensure we either use them here or don't touch them, |
783 | * and debugfs_leave_cancellation() will wait for this |
784 | * to be finished processing before exiting one. It may |
785 | * of course win and remove the cancellation, but then |
786 | * chances are we never even got into this bit, we only |
787 | * do if the refcount isn't zero already. |
788 | */ |
789 | mutex_lock(&fsd->cancellations_mtx); |
790 | while ((c = list_first_entry_or_null(&fsd->cancellations, |
791 | typeof(*c), list))) { |
792 | list_del_init(entry: &c->list); |
793 | c->cancel(dentry, c->cancel_data); |
794 | } |
795 | mutex_unlock(lock: &fsd->cancellations_mtx); |
796 | |
797 | wait_for_completion(&fsd->active_users_drained); |
798 | } |
799 | } |
800 | |
801 | static void remove_one(struct dentry *victim) |
802 | { |
803 | if (d_is_reg(dentry: victim)) |
804 | __debugfs_file_removed(dentry: victim); |
805 | simple_release_fs(mount: &debugfs_mount, count: &debugfs_mount_count); |
806 | } |
807 | |
808 | /** |
809 | * debugfs_remove - recursively removes a directory |
810 | * @dentry: a pointer to a the dentry of the directory to be removed. If this |
811 | * parameter is NULL or an error value, nothing will be done. |
812 | * |
813 | * This function recursively removes a directory tree in debugfs that |
814 | * was previously created with a call to another debugfs function |
815 | * (like debugfs_create_file() or variants thereof.) |
816 | * |
817 | * This function is required to be called in order for the file to be |
818 | * removed, no automatic cleanup of files will happen when a module is |
819 | * removed, you are responsible here. |
820 | */ |
821 | void debugfs_remove(struct dentry *dentry) |
822 | { |
823 | if (IS_ERR_OR_NULL(ptr: dentry)) |
824 | return; |
825 | |
826 | simple_pin_fs(&debug_fs_type, mount: &debugfs_mount, count: &debugfs_mount_count); |
827 | simple_recursive_removal(dentry, callback: remove_one); |
828 | simple_release_fs(mount: &debugfs_mount, count: &debugfs_mount_count); |
829 | } |
830 | EXPORT_SYMBOL_GPL(debugfs_remove); |
831 | |
832 | /** |
833 | * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it |
834 | * @name: a pointer to a string containing the name of the item to look up. |
835 | * @parent: a pointer to the parent dentry of the item. |
836 | * |
837 | * This is the equlivant of doing something like |
838 | * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting |
839 | * handled for the directory being looked up. |
840 | */ |
841 | void debugfs_lookup_and_remove(const char *name, struct dentry *parent) |
842 | { |
843 | struct dentry *dentry; |
844 | |
845 | dentry = debugfs_lookup(name, parent); |
846 | if (!dentry) |
847 | return; |
848 | |
849 | debugfs_remove(dentry); |
850 | dput(dentry); |
851 | } |
852 | EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); |
853 | |
854 | /** |
855 | * debugfs_rename - rename a file/directory in the debugfs filesystem |
856 | * @old_dir: a pointer to the parent dentry for the renamed object. This |
857 | * should be a directory dentry. |
858 | * @old_dentry: dentry of an object to be renamed. |
859 | * @new_dir: a pointer to the parent dentry where the object should be |
860 | * moved. This should be a directory dentry. |
861 | * @new_name: a pointer to a string containing the target name. |
862 | * |
863 | * This function renames a file/directory in debugfs. The target must not |
864 | * exist for rename to succeed. |
865 | * |
866 | * This function will return a pointer to old_dentry (which is updated to |
867 | * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR) |
868 | * will be returned. |
869 | * |
870 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
871 | * returned. |
872 | */ |
873 | struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, |
874 | struct dentry *new_dir, const char *new_name) |
875 | { |
876 | int error; |
877 | struct dentry *dentry = NULL, *trap; |
878 | struct name_snapshot old_name; |
879 | |
880 | if (IS_ERR(ptr: old_dir)) |
881 | return old_dir; |
882 | if (IS_ERR(ptr: new_dir)) |
883 | return new_dir; |
884 | if (IS_ERR_OR_NULL(ptr: old_dentry)) |
885 | return old_dentry; |
886 | |
887 | trap = lock_rename(new_dir, old_dir); |
888 | /* Source or destination directories don't exist? */ |
889 | if (d_really_is_negative(dentry: old_dir) || d_really_is_negative(dentry: new_dir)) |
890 | goto exit; |
891 | /* Source does not exist, cyclic rename, or mountpoint? */ |
892 | if (d_really_is_negative(dentry: old_dentry) || old_dentry == trap || |
893 | d_mountpoint(dentry: old_dentry)) |
894 | goto exit; |
895 | dentry = lookup_one_len(new_name, new_dir, strlen(new_name)); |
896 | /* Lookup failed, cyclic rename or target exists? */ |
897 | if (IS_ERR(ptr: dentry) || dentry == trap || d_really_is_positive(dentry)) |
898 | goto exit; |
899 | |
900 | take_dentry_name_snapshot(&old_name, old_dentry); |
901 | |
902 | error = simple_rename(&nop_mnt_idmap, d_inode(dentry: old_dir), old_dentry, |
903 | d_inode(dentry: new_dir), dentry, 0); |
904 | if (error) { |
905 | release_dentry_name_snapshot(&old_name); |
906 | goto exit; |
907 | } |
908 | d_move(old_dentry, dentry); |
909 | fsnotify_move(old_dir: d_inode(dentry: old_dir), new_dir: d_inode(dentry: new_dir), old_name: &old_name.name, |
910 | isdir: d_is_dir(dentry: old_dentry), |
911 | NULL, moved: old_dentry); |
912 | release_dentry_name_snapshot(&old_name); |
913 | unlock_rename(new_dir, old_dir); |
914 | dput(dentry); |
915 | return old_dentry; |
916 | exit: |
917 | if (dentry && !IS_ERR(ptr: dentry)) |
918 | dput(dentry); |
919 | unlock_rename(new_dir, old_dir); |
920 | if (IS_ERR(ptr: dentry)) |
921 | return dentry; |
922 | return ERR_PTR(error: -EINVAL); |
923 | } |
924 | EXPORT_SYMBOL_GPL(debugfs_rename); |
925 | |
926 | /** |
927 | * debugfs_initialized - Tells whether debugfs has been registered |
928 | */ |
929 | bool debugfs_initialized(void) |
930 | { |
931 | return debugfs_registered; |
932 | } |
933 | EXPORT_SYMBOL_GPL(debugfs_initialized); |
934 | |
935 | static int __init debugfs_kernel(char *str) |
936 | { |
937 | if (str) { |
938 | if (!strcmp(str, "on" )) |
939 | debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT; |
940 | else if (!strcmp(str, "no-mount" )) |
941 | debugfs_allow = DEBUGFS_ALLOW_API; |
942 | else if (!strcmp(str, "off" )) |
943 | debugfs_allow = 0; |
944 | } |
945 | |
946 | return 0; |
947 | } |
948 | early_param("debugfs" , debugfs_kernel); |
949 | static int __init debugfs_init(void) |
950 | { |
951 | int retval; |
952 | |
953 | if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT)) |
954 | return -EPERM; |
955 | |
956 | retval = sysfs_create_mount_point(parent_kobj: kernel_kobj, name: "debug" ); |
957 | if (retval) |
958 | return retval; |
959 | |
960 | retval = register_filesystem(&debug_fs_type); |
961 | if (retval) |
962 | sysfs_remove_mount_point(parent_kobj: kernel_kobj, name: "debug" ); |
963 | else |
964 | debugfs_registered = true; |
965 | |
966 | return retval; |
967 | } |
968 | core_initcall(debugfs_init); |
969 | |