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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 : :
39 : : /*
40 : : * Don't allow access attributes to be changed whilst the kernel is locked down
41 : : * so that we can use the file mode as part of a heuristic to determine whether
42 : : * to lock down individual files.
43 : : */
44 : 0 : static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
45 : : {
46 : 0 : int ret = security_locked_down(LOCKDOWN_DEBUGFS);
47 : :
48 [ # # # # ]: 0 : if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
49 : : return ret;
50 : 0 : return simple_setattr(dentry, ia);
51 : : }
52 : :
53 : : static const struct inode_operations debugfs_file_inode_operations = {
54 : : .setattr = debugfs_setattr,
55 : : };
56 : : static const struct inode_operations debugfs_dir_inode_operations = {
57 : : .lookup = simple_lookup,
58 : : .setattr = debugfs_setattr,
59 : : };
60 : : static const struct inode_operations debugfs_symlink_inode_operations = {
61 : : .get_link = simple_get_link,
62 : : .setattr = debugfs_setattr,
63 : : };
64 : :
65 : 2154936 : static struct inode *debugfs_get_inode(struct super_block *sb)
66 : : {
67 : 2154936 : struct inode *inode = new_inode(sb);
68 [ + - ]: 2154936 : if (inode) {
69 : 2154936 : inode->i_ino = get_next_ino();
70 : 2154936 : inode->i_atime = inode->i_mtime =
71 : : inode->i_ctime = current_time(inode);
72 : : }
73 : 2154936 : return inode;
74 : : }
75 : :
76 : : struct debugfs_mount_opts {
77 : : kuid_t uid;
78 : : kgid_t gid;
79 : : umode_t mode;
80 : : };
81 : :
82 : : enum {
83 : : Opt_uid,
84 : : Opt_gid,
85 : : Opt_mode,
86 : : Opt_err
87 : : };
88 : :
89 : : static const match_table_t tokens = {
90 : : {Opt_uid, "uid=%u"},
91 : : {Opt_gid, "gid=%u"},
92 : : {Opt_mode, "mode=%o"},
93 : : {Opt_err, NULL}
94 : : };
95 : :
96 : : struct debugfs_fs_info {
97 : : struct debugfs_mount_opts mount_opts;
98 : : };
99 : :
100 : 808 : static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
101 : : {
102 : : substring_t args[MAX_OPT_ARGS];
103 : : int option;
104 : : int token;
105 : : kuid_t uid;
106 : : kgid_t gid;
107 : : char *p;
108 : :
109 : 808 : opts->mode = DEBUGFS_DEFAULT_MODE;
110 : :
111 [ - + ]: 1616 : while ((p = strsep(&data, ",")) != NULL) {
112 [ # # ]: 0 : if (!*p)
113 : 0 : continue;
114 : :
115 : 0 : token = match_token(p, tokens, args);
116 [ # # # # ]: 0 : switch (token) {
117 : : case Opt_uid:
118 [ # # ]: 0 : if (match_int(&args[0], &option))
119 : : return -EINVAL;
120 : 0 : uid = make_kuid(current_user_ns(), option);
121 [ # # ]: 0 : if (!uid_valid(uid))
122 : : return -EINVAL;
123 : 0 : opts->uid = uid;
124 : 0 : break;
125 : : case Opt_gid:
126 [ # # ]: 0 : if (match_int(&args[0], &option))
127 : : return -EINVAL;
128 : 0 : gid = make_kgid(current_user_ns(), option);
129 [ # # ]: 0 : if (!gid_valid(gid))
130 : : return -EINVAL;
131 : 0 : opts->gid = gid;
132 : 0 : break;
133 : : case Opt_mode:
134 [ # # ]: 0 : if (match_octal(&args[0], &option))
135 : : return -EINVAL;
136 : 0 : opts->mode = option & S_IALLUGO;
137 : 0 : break;
138 : : /*
139 : : * We might like to report bad mount options here;
140 : : * but traditionally debugfs has ignored all mount options
141 : : */
142 : : }
143 : : }
144 : :
145 : : return 0;
146 : : }
147 : :
148 : : static int debugfs_apply_options(struct super_block *sb)
149 : : {
150 : 808 : struct debugfs_fs_info *fsi = sb->s_fs_info;
151 : 808 : struct inode *inode = d_inode(sb->s_root);
152 : : struct debugfs_mount_opts *opts = &fsi->mount_opts;
153 : :
154 : 808 : inode->i_mode &= ~S_IALLUGO;
155 : 808 : inode->i_mode |= opts->mode;
156 : :
157 : 808 : inode->i_uid = opts->uid;
158 : 808 : inode->i_gid = opts->gid;
159 : :
160 : : return 0;
161 : : }
162 : :
163 : 404 : static int debugfs_remount(struct super_block *sb, int *flags, char *data)
164 : : {
165 : : int err;
166 : 404 : struct debugfs_fs_info *fsi = sb->s_fs_info;
167 : :
168 : 404 : sync_filesystem(sb);
169 : 404 : err = debugfs_parse_options(data, &fsi->mount_opts);
170 [ + - ]: 404 : if (err)
171 : : goto fail;
172 : :
173 : : debugfs_apply_options(sb);
174 : :
175 : : fail:
176 : 404 : return err;
177 : : }
178 : :
179 : 54806 : static int debugfs_show_options(struct seq_file *m, struct dentry *root)
180 : : {
181 : 54806 : struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
182 : 54806 : struct debugfs_mount_opts *opts = &fsi->mount_opts;
183 : :
184 [ - + ]: 54806 : if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
185 : 0 : seq_printf(m, ",uid=%u",
186 : : from_kuid_munged(&init_user_ns, opts->uid));
187 [ - + ]: 54806 : if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
188 : 0 : seq_printf(m, ",gid=%u",
189 : : from_kgid_munged(&init_user_ns, opts->gid));
190 [ - + ]: 54806 : if (opts->mode != DEBUGFS_DEFAULT_MODE)
191 : 0 : seq_printf(m, ",mode=%o", opts->mode);
192 : :
193 : 54806 : return 0;
194 : : }
195 : :
196 : 0 : static void debugfs_free_inode(struct inode *inode)
197 : : {
198 [ # # ]: 0 : if (S_ISLNK(inode->i_mode))
199 : 0 : kfree(inode->i_link);
200 : 0 : free_inode_nonrcu(inode);
201 : 0 : }
202 : :
203 : : static const struct super_operations debugfs_super_operations = {
204 : : .statfs = simple_statfs,
205 : : .remount_fs = debugfs_remount,
206 : : .show_options = debugfs_show_options,
207 : : .free_inode = debugfs_free_inode,
208 : : };
209 : :
210 : 99788 : static void debugfs_release_dentry(struct dentry *dentry)
211 : : {
212 : 99788 : void *fsd = dentry->d_fsdata;
213 : :
214 [ + - ]: 99788 : if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
215 : 99788 : kfree(dentry->d_fsdata);
216 : 99788 : }
217 : :
218 : 0 : static struct vfsmount *debugfs_automount(struct path *path)
219 : : {
220 : : debugfs_automount_t f;
221 : 0 : f = (debugfs_automount_t)path->dentry->d_fsdata;
222 : 0 : return f(path->dentry, d_inode(path->dentry)->i_private);
223 : : }
224 : :
225 : : static const struct dentry_operations debugfs_dops = {
226 : : .d_delete = always_delete_dentry,
227 : : .d_release = debugfs_release_dentry,
228 : : .d_automount = debugfs_automount,
229 : : };
230 : :
231 : 404 : static int debug_fill_super(struct super_block *sb, void *data, int silent)
232 : : {
233 : : static const struct tree_descr debug_files[] = {{""}};
234 : : struct debugfs_fs_info *fsi;
235 : : int err;
236 : :
237 : 404 : fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
238 : 404 : sb->s_fs_info = fsi;
239 [ + - ]: 404 : if (!fsi) {
240 : : err = -ENOMEM;
241 : : goto fail;
242 : : }
243 : :
244 : 404 : err = debugfs_parse_options(data, &fsi->mount_opts);
245 [ + - ]: 404 : if (err)
246 : : goto fail;
247 : :
248 : 404 : err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
249 [ + - ]: 404 : if (err)
250 : : goto fail;
251 : :
252 : 404 : sb->s_op = &debugfs_super_operations;
253 : 404 : sb->s_d_op = &debugfs_dops;
254 : :
255 : : debugfs_apply_options(sb);
256 : :
257 : 404 : return 0;
258 : :
259 : : fail:
260 : 0 : kfree(fsi);
261 : 0 : sb->s_fs_info = NULL;
262 : 0 : return err;
263 : : }
264 : :
265 : 808 : static struct dentry *debug_mount(struct file_system_type *fs_type,
266 : : int flags, const char *dev_name,
267 : : void *data)
268 : : {
269 : 808 : return mount_single(fs_type, flags, data, debug_fill_super);
270 : : }
271 : :
272 : : static struct file_system_type debug_fs_type = {
273 : : .owner = THIS_MODULE,
274 : : .name = "debugfs",
275 : : .mount = debug_mount,
276 : : .kill_sb = kill_litter_super,
277 : : };
278 : : MODULE_ALIAS_FS("debugfs");
279 : :
280 : : /**
281 : : * debugfs_lookup() - look up an existing debugfs file
282 : : * @name: a pointer to a string containing the name of the file to look up.
283 : : * @parent: a pointer to the parent dentry of the file.
284 : : *
285 : : * This function will return a pointer to a dentry if it succeeds. If the file
286 : : * doesn't exist or an error occurs, %NULL will be returned. The returned
287 : : * dentry must be passed to dput() when it is no longer needed.
288 : : *
289 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
290 : : * returned.
291 : : */
292 : 1212 : struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
293 : : {
294 : : struct dentry *dentry;
295 : :
296 [ + - ]: 1212 : if (IS_ERR(parent))
297 : : return NULL;
298 : :
299 [ + - ]: 1212 : if (!parent)
300 : 1212 : parent = debugfs_mount->mnt_root;
301 : :
302 : 1212 : dentry = lookup_one_len_unlocked(name, parent, strlen(name));
303 [ + - ]: 1212 : if (IS_ERR(dentry))
304 : : return NULL;
305 [ + + ]: 1212 : if (!d_really_is_positive(dentry)) {
306 : 404 : dput(dentry);
307 : 404 : return NULL;
308 : : }
309 : : return dentry;
310 : : }
311 : : EXPORT_SYMBOL_GPL(debugfs_lookup);
312 : :
313 : 2154936 : static struct dentry *start_creating(const char *name, struct dentry *parent)
314 : : {
315 : : struct dentry *dentry;
316 : : int error;
317 : :
318 : : pr_debug("creating file '%s'\n", name);
319 : :
320 [ + - ]: 2154936 : if (IS_ERR(parent))
321 : : return parent;
322 : :
323 : 2154936 : error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
324 : : &debugfs_mount_count);
325 [ - + ]: 2154936 : if (error) {
326 : 0 : pr_err("Unable to pin filesystem for file '%s'\n", name);
327 : 0 : return ERR_PTR(error);
328 : : }
329 : :
330 : : /* If the parent is not specified, we create it in the root.
331 : : * We need the root dentry to do this, which is in the super
332 : : * block. A pointer to that is in the struct vfsmount that we
333 : : * have around.
334 : : */
335 [ + + ]: 2154936 : if (!parent)
336 : 14544 : parent = debugfs_mount->mnt_root;
337 : :
338 : : inode_lock(d_inode(parent));
339 : 2154936 : dentry = lookup_one_len(name, parent, strlen(name));
340 [ + - - + ]: 4309872 : if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
341 [ # # ]: 0 : if (d_is_dir(dentry))
342 : 0 : pr_err("Directory '%s' with parent '%s' already present!\n",
343 : : name, parent->d_name.name);
344 : : else
345 : 0 : pr_err("File '%s' in directory '%s' already present!\n",
346 : : name, parent->d_name.name);
347 : 0 : dput(dentry);
348 : : dentry = ERR_PTR(-EEXIST);
349 : : }
350 : :
351 [ - + ]: 2154936 : if (IS_ERR(dentry)) {
352 : : inode_unlock(d_inode(parent));
353 : 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
354 : : }
355 : :
356 : 2154936 : return dentry;
357 : : }
358 : :
359 : 0 : static struct dentry *failed_creating(struct dentry *dentry)
360 : : {
361 : 0 : inode_unlock(d_inode(dentry->d_parent));
362 : 0 : dput(dentry);
363 : 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
364 : 0 : return ERR_PTR(-ENOMEM);
365 : : }
366 : :
367 : : static struct dentry *end_creating(struct dentry *dentry)
368 : : {
369 : 2154936 : inode_unlock(d_inode(dentry->d_parent));
370 : : return dentry;
371 : : }
372 : :
373 : 1294012 : static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
374 : : struct dentry *parent, void *data,
375 : : const struct file_operations *proxy_fops,
376 : : const struct file_operations *real_fops)
377 : : {
378 : : struct dentry *dentry;
379 : : struct inode *inode;
380 : :
381 [ + + ]: 1294012 : if (!(mode & S_IFMT))
382 : 1288760 : mode |= S_IFREG;
383 [ - + ]: 1294012 : BUG_ON(!S_ISREG(mode));
384 : 1294012 : dentry = start_creating(name, parent);
385 : :
386 [ + - ]: 1294012 : if (IS_ERR(dentry))
387 : : return dentry;
388 : :
389 : 1294012 : inode = debugfs_get_inode(dentry->d_sb);
390 [ - + ]: 1294012 : if (unlikely(!inode)) {
391 : 0 : pr_err("out of free dentries, can not create file '%s'\n",
392 : : name);
393 : 0 : return failed_creating(dentry);
394 : : }
395 : :
396 : 1294012 : inode->i_mode = mode;
397 : 1294012 : inode->i_private = data;
398 : :
399 : 1294012 : inode->i_op = &debugfs_file_inode_operations;
400 : 1294012 : inode->i_fop = proxy_fops;
401 : 1294012 : dentry->d_fsdata = (void *)((unsigned long)real_fops |
402 : : DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
403 : :
404 : 1294012 : d_instantiate(dentry, inode);
405 : 2588024 : fsnotify_create(d_inode(dentry->d_parent), dentry);
406 : 1294012 : return end_creating(dentry);
407 : : }
408 : :
409 : : /**
410 : : * debugfs_create_file - create a file in the debugfs filesystem
411 : : * @name: a pointer to a string containing the name of the file to create.
412 : : * @mode: the permission that the file should have.
413 : : * @parent: a pointer to the parent dentry for this file. This should be a
414 : : * directory dentry if set. If this parameter is NULL, then the
415 : : * file will be created in the root of the debugfs filesystem.
416 : : * @data: a pointer to something that the caller will want to get to later
417 : : * on. The inode.i_private pointer will point to this value on
418 : : * the open() call.
419 : : * @fops: a pointer to a struct file_operations that should be used for
420 : : * this file.
421 : : *
422 : : * This is the basic "create a file" function for debugfs. It allows for a
423 : : * wide range of flexibility in creating a file, or a directory (if you want
424 : : * to create a directory, the debugfs_create_dir() function is
425 : : * recommended to be used instead.)
426 : : *
427 : : * This function will return a pointer to a dentry if it succeeds. This
428 : : * pointer must be passed to the debugfs_remove() function when the file is
429 : : * to be removed (no automatic cleanup happens if your module is unloaded,
430 : : * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
431 : : * returned.
432 : : *
433 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
434 : : * returned.
435 : : */
436 : 1134836 : struct dentry *debugfs_create_file(const char *name, umode_t mode,
437 : : struct dentry *parent, void *data,
438 : : const struct file_operations *fops)
439 : : {
440 : :
441 [ # # - + ]: 1134836 : return __debugfs_create_file(name, mode, parent, data,
442 : : fops ? &debugfs_full_proxy_file_operations :
443 : : &debugfs_noop_file_operations,
444 : : fops);
445 : : }
446 : : EXPORT_SYMBOL_GPL(debugfs_create_file);
447 : :
448 : : /**
449 : : * debugfs_create_file_unsafe - create a file in the debugfs filesystem
450 : : * @name: a pointer to a string containing the name of the file to create.
451 : : * @mode: the permission that the file should have.
452 : : * @parent: a pointer to the parent dentry for this file. This should be a
453 : : * directory dentry if set. If this parameter is NULL, then the
454 : : * file will be created in the root of the debugfs filesystem.
455 : : * @data: a pointer to something that the caller will want to get to later
456 : : * on. The inode.i_private pointer will point to this value on
457 : : * the open() call.
458 : : * @fops: a pointer to a struct file_operations that should be used for
459 : : * this file.
460 : : *
461 : : * debugfs_create_file_unsafe() is completely analogous to
462 : : * debugfs_create_file(), the only difference being that the fops
463 : : * handed it will not get protected against file removals by the
464 : : * debugfs core.
465 : : *
466 : : * It is your responsibility to protect your struct file_operation
467 : : * methods against file removals by means of debugfs_file_get()
468 : : * and debugfs_file_put(). ->open() is still protected by
469 : : * debugfs though.
470 : : *
471 : : * Any struct file_operations defined by means of
472 : : * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
473 : : * thus, may be used here.
474 : : */
475 : 159176 : struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
476 : : struct dentry *parent, void *data,
477 : : const struct file_operations *fops)
478 : : {
479 : :
480 [ - + ]: 159176 : return __debugfs_create_file(name, mode, parent, data,
481 : : fops ? &debugfs_open_proxy_file_operations :
482 : : &debugfs_noop_file_operations,
483 : : fops);
484 : : }
485 : : EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
486 : :
487 : : /**
488 : : * debugfs_create_file_size - create a file in the debugfs filesystem
489 : : * @name: a pointer to a string containing the name of the file to create.
490 : : * @mode: the permission that the file should have.
491 : : * @parent: a pointer to the parent dentry for this file. This should be a
492 : : * directory dentry if set. If this parameter is NULL, then the
493 : : * file will be created in the root of the debugfs filesystem.
494 : : * @data: a pointer to something that the caller will want to get to later
495 : : * on. The inode.i_private pointer will point to this value on
496 : : * the open() call.
497 : : * @fops: a pointer to a struct file_operations that should be used for
498 : : * this file.
499 : : * @file_size: initial file size
500 : : *
501 : : * This is the basic "create a file" function for debugfs. It allows for a
502 : : * wide range of flexibility in creating a file, or a directory (if you want
503 : : * to create a directory, the debugfs_create_dir() function is
504 : : * recommended to be used instead.)
505 : : *
506 : : * This function will return a pointer to a dentry if it succeeds. This
507 : : * pointer must be passed to the debugfs_remove() function when the file is
508 : : * to be removed (no automatic cleanup happens if your module is unloaded,
509 : : * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
510 : : * returned.
511 : : *
512 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
513 : : * returned.
514 : : */
515 : 0 : struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
516 : : struct dentry *parent, void *data,
517 : : const struct file_operations *fops,
518 : : loff_t file_size)
519 : : {
520 : : struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
521 : :
522 [ # # ]: 0 : if (de)
523 : 0 : d_inode(de)->i_size = file_size;
524 : 0 : return de;
525 : : }
526 : : EXPORT_SYMBOL_GPL(debugfs_create_file_size);
527 : :
528 : : /**
529 : : * debugfs_create_dir - create a directory in the debugfs filesystem
530 : : * @name: a pointer to a string containing the name of the directory to
531 : : * create.
532 : : * @parent: a pointer to the parent dentry for this file. This should be a
533 : : * directory dentry if set. If this parameter is NULL, then the
534 : : * directory will be created in the root of the debugfs filesystem.
535 : : *
536 : : * This function creates a directory in debugfs with the given name.
537 : : *
538 : : * This function will return a pointer to a dentry if it succeeds. This
539 : : * pointer must be passed to the debugfs_remove() function when the file is
540 : : * to be removed (no automatic cleanup happens if your module is unloaded,
541 : : * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
542 : : * returned.
543 : : *
544 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
545 : : * returned.
546 : : */
547 : 149884 : struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
548 : : {
549 : 149884 : struct dentry *dentry = start_creating(name, parent);
550 : : struct inode *inode;
551 : :
552 [ + - ]: 149884 : if (IS_ERR(dentry))
553 : : return dentry;
554 : :
555 : 149884 : inode = debugfs_get_inode(dentry->d_sb);
556 [ - + ]: 149884 : if (unlikely(!inode)) {
557 : 0 : pr_err("out of free dentries, can not create directory '%s'\n",
558 : : name);
559 : 0 : return failed_creating(dentry);
560 : : }
561 : :
562 : 149884 : inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
563 : 149884 : inode->i_op = &debugfs_dir_inode_operations;
564 : 149884 : inode->i_fop = &simple_dir_operations;
565 : :
566 : : /* directory inodes start off with i_nlink == 2 (for "." entry) */
567 : 149884 : inc_nlink(inode);
568 : 149884 : d_instantiate(dentry, inode);
569 : 299768 : inc_nlink(d_inode(dentry->d_parent));
570 : 299768 : fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
571 : 149884 : return end_creating(dentry);
572 : : }
573 : : EXPORT_SYMBOL_GPL(debugfs_create_dir);
574 : :
575 : : /**
576 : : * debugfs_create_automount - create automount point in the debugfs filesystem
577 : : * @name: a pointer to a string containing the name of the file to create.
578 : : * @parent: a pointer to the parent dentry for this file. This should be a
579 : : * directory dentry if set. If this parameter is NULL, then the
580 : : * file will be created in the root of the debugfs filesystem.
581 : : * @f: function to be called when pathname resolution steps on that one.
582 : : * @data: opaque argument to pass to f().
583 : : *
584 : : * @f should return what ->d_automount() would.
585 : : */
586 : 404 : struct dentry *debugfs_create_automount(const char *name,
587 : : struct dentry *parent,
588 : : debugfs_automount_t f,
589 : : void *data)
590 : : {
591 : 404 : struct dentry *dentry = start_creating(name, parent);
592 : : struct inode *inode;
593 : :
594 [ + - ]: 404 : if (IS_ERR(dentry))
595 : : return dentry;
596 : :
597 : 404 : inode = debugfs_get_inode(dentry->d_sb);
598 [ - + ]: 404 : if (unlikely(!inode)) {
599 : 0 : pr_err("out of free dentries, can not create automount '%s'\n",
600 : : name);
601 : 0 : return failed_creating(dentry);
602 : : }
603 : :
604 : 404 : make_empty_dir_inode(inode);
605 : 404 : inode->i_flags |= S_AUTOMOUNT;
606 : 404 : inode->i_private = data;
607 : 404 : dentry->d_fsdata = (void *)f;
608 : : /* directory inodes start off with i_nlink == 2 (for "." entry) */
609 : 404 : inc_nlink(inode);
610 : 404 : d_instantiate(dentry, inode);
611 : 808 : inc_nlink(d_inode(dentry->d_parent));
612 : 808 : fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
613 : 404 : return end_creating(dentry);
614 : : }
615 : : EXPORT_SYMBOL(debugfs_create_automount);
616 : :
617 : : /**
618 : : * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
619 : : * @name: a pointer to a string containing the name of the symbolic link to
620 : : * create.
621 : : * @parent: a pointer to the parent dentry for this symbolic link. This
622 : : * should be a directory dentry if set. If this parameter is NULL,
623 : : * then the symbolic link will be created in the root of the debugfs
624 : : * filesystem.
625 : : * @target: a pointer to a string containing the path to the target of the
626 : : * symbolic link.
627 : : *
628 : : * This function creates a symbolic link with the given name in debugfs that
629 : : * links to the given target path.
630 : : *
631 : : * This function will return a pointer to a dentry if it succeeds. This
632 : : * pointer must be passed to the debugfs_remove() function when the symbolic
633 : : * link is to be removed (no automatic cleanup happens if your module is
634 : : * unloaded, you are responsible here.) If an error occurs, %ERR_PTR(-ERROR)
635 : : * will be returned.
636 : : *
637 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
638 : : * returned.
639 : : */
640 : 710636 : struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
641 : : const char *target)
642 : : {
643 : : struct dentry *dentry;
644 : : struct inode *inode;
645 : 710636 : char *link = kstrdup(target, GFP_KERNEL);
646 [ + - ]: 710636 : if (!link)
647 : : return ERR_PTR(-ENOMEM);
648 : :
649 : 710636 : dentry = start_creating(name, parent);
650 [ - + ]: 710636 : if (IS_ERR(dentry)) {
651 : 0 : kfree(link);
652 : 0 : return dentry;
653 : : }
654 : :
655 : 710636 : inode = debugfs_get_inode(dentry->d_sb);
656 [ - + ]: 710636 : if (unlikely(!inode)) {
657 : 0 : pr_err("out of free dentries, can not create symlink '%s'\n",
658 : : name);
659 : 0 : kfree(link);
660 : 0 : return failed_creating(dentry);
661 : : }
662 : 710636 : inode->i_mode = S_IFLNK | S_IRWXUGO;
663 : 710636 : inode->i_op = &debugfs_symlink_inode_operations;
664 : 710636 : inode->i_link = link;
665 : 710636 : d_instantiate(dentry, inode);
666 : 710636 : return end_creating(dentry);
667 : : }
668 : : EXPORT_SYMBOL_GPL(debugfs_create_symlink);
669 : :
670 : 0 : static void __debugfs_file_removed(struct dentry *dentry)
671 : : {
672 : : struct debugfs_fsdata *fsd;
673 : :
674 : : /*
675 : : * Paired with the closing smp_mb() implied by a successful
676 : : * cmpxchg() in debugfs_file_get(): either
677 : : * debugfs_file_get() must see a dead dentry or we must see a
678 : : * debugfs_fsdata instance at ->d_fsdata here (or both).
679 : : */
680 : 0 : smp_mb();
681 : : fsd = READ_ONCE(dentry->d_fsdata);
682 [ # # ]: 0 : if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
683 : 0 : return;
684 [ # # ]: 0 : if (!refcount_dec_and_test(&fsd->active_users))
685 : 0 : wait_for_completion(&fsd->active_users_drained);
686 : : }
687 : :
688 : 0 : static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
689 : : {
690 : : int ret = 0;
691 : :
692 [ # # ]: 0 : if (simple_positive(dentry)) {
693 : : dget(dentry);
694 [ # # ]: 0 : if (d_is_dir(dentry)) {
695 : 0 : ret = simple_rmdir(d_inode(parent), dentry);
696 [ # # ]: 0 : if (!ret)
697 : 0 : fsnotify_rmdir(d_inode(parent), dentry);
698 : : } else {
699 : 0 : simple_unlink(d_inode(parent), dentry);
700 : 0 : fsnotify_unlink(d_inode(parent), dentry);
701 : : }
702 [ # # ]: 0 : if (!ret)
703 : 0 : d_delete(dentry);
704 [ # # ]: 0 : if (d_is_reg(dentry))
705 : 0 : __debugfs_file_removed(dentry);
706 : 0 : dput(dentry);
707 : : }
708 : 0 : return ret;
709 : : }
710 : :
711 : : /**
712 : : * debugfs_remove - removes a file or directory from the debugfs filesystem
713 : : * @dentry: a pointer to a the dentry of the file or directory to be
714 : : * removed. If this parameter is NULL or an error value, nothing
715 : : * will be done.
716 : : *
717 : : * This function removes a file or directory in debugfs that was previously
718 : : * created with a call to another debugfs function (like
719 : : * debugfs_create_file() or variants thereof.)
720 : : *
721 : : * This function is required to be called in order for the file to be
722 : : * removed, no automatic cleanup of files will happen when a module is
723 : : * removed, you are responsible here.
724 : : */
725 : 0 : void debugfs_remove(struct dentry *dentry)
726 : : {
727 : : struct dentry *parent;
728 : : int ret;
729 : :
730 [ # # ]: 0 : if (IS_ERR_OR_NULL(dentry))
731 : 0 : return;
732 : :
733 : 0 : parent = dentry->d_parent;
734 : : inode_lock(d_inode(parent));
735 : 0 : ret = __debugfs_remove(dentry, parent);
736 : : inode_unlock(d_inode(parent));
737 [ # # ]: 0 : if (!ret)
738 : 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
739 : : }
740 : : EXPORT_SYMBOL_GPL(debugfs_remove);
741 : :
742 : : /**
743 : : * debugfs_remove_recursive - recursively removes a directory
744 : : * @dentry: a pointer to a the dentry of the directory to be removed. If this
745 : : * parameter is NULL or an error value, nothing will be done.
746 : : *
747 : : * This function recursively removes a directory tree in debugfs that
748 : : * was previously created with a call to another debugfs function
749 : : * (like debugfs_create_file() or variants thereof.)
750 : : *
751 : : * This function is required to be called in order for the file to be
752 : : * removed, no automatic cleanup of files will happen when a module is
753 : : * removed, you are responsible here.
754 : : */
755 : 0 : void debugfs_remove_recursive(struct dentry *dentry)
756 : : {
757 : : struct dentry *child, *parent;
758 : :
759 [ # # ]: 0 : if (IS_ERR_OR_NULL(dentry))
760 : 0 : return;
761 : :
762 : : parent = dentry;
763 : : down:
764 : : inode_lock(d_inode(parent));
765 : : loop:
766 : : /*
767 : : * The parent->d_subdirs is protected by the d_lock. Outside that
768 : : * lock, the child can be unlinked and set to be freed which can
769 : : * use the d_u.d_child as the rcu head and corrupt this list.
770 : : */
771 : : spin_lock(&parent->d_lock);
772 [ # # ]: 0 : list_for_each_entry(child, &parent->d_subdirs, d_child) {
773 [ # # ]: 0 : if (!simple_positive(child))
774 : 0 : continue;
775 : :
776 : : /* perhaps simple_empty(child) makes more sense */
777 [ # # ]: 0 : if (!list_empty(&child->d_subdirs)) {
778 : : spin_unlock(&parent->d_lock);
779 : : inode_unlock(d_inode(parent));
780 : 0 : parent = child;
781 : 0 : goto down;
782 : : }
783 : :
784 : : spin_unlock(&parent->d_lock);
785 : :
786 [ # # ]: 0 : if (!__debugfs_remove(child, parent))
787 : 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
788 : :
789 : : /*
790 : : * The parent->d_lock protects agaist child from unlinking
791 : : * from d_subdirs. When releasing the parent->d_lock we can
792 : : * no longer trust that the next pointer is valid.
793 : : * Restart the loop. We'll skip this one with the
794 : : * simple_positive() check.
795 : : */
796 : : goto loop;
797 : : }
798 : : spin_unlock(&parent->d_lock);
799 : :
800 : : inode_unlock(d_inode(parent));
801 : : child = parent;
802 : 0 : parent = parent->d_parent;
803 : : inode_lock(d_inode(parent));
804 : :
805 [ # # ]: 0 : if (child != dentry)
806 : : /* go up */
807 : : goto loop;
808 : :
809 [ # # ]: 0 : if (!__debugfs_remove(child, parent))
810 : 0 : simple_release_fs(&debugfs_mount, &debugfs_mount_count);
811 : : inode_unlock(d_inode(parent));
812 : : }
813 : : EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
814 : :
815 : : /**
816 : : * debugfs_rename - rename a file/directory in the debugfs filesystem
817 : : * @old_dir: a pointer to the parent dentry for the renamed object. This
818 : : * should be a directory dentry.
819 : : * @old_dentry: dentry of an object to be renamed.
820 : : * @new_dir: a pointer to the parent dentry where the object should be
821 : : * moved. This should be a directory dentry.
822 : : * @new_name: a pointer to a string containing the target name.
823 : : *
824 : : * This function renames a file/directory in debugfs. The target must not
825 : : * exist for rename to succeed.
826 : : *
827 : : * This function will return a pointer to old_dentry (which is updated to
828 : : * reflect renaming) if it succeeds. If an error occurs, %NULL will be
829 : : * returned.
830 : : *
831 : : * If debugfs is not enabled in the kernel, the value -%ENODEV will be
832 : : * returned.
833 : : */
834 : 0 : struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
835 : : struct dentry *new_dir, const char *new_name)
836 : : {
837 : : int error;
838 : : struct dentry *dentry = NULL, *trap;
839 : : struct name_snapshot old_name;
840 : :
841 [ # # ]: 0 : if (IS_ERR(old_dir))
842 : : return old_dir;
843 [ # # ]: 0 : if (IS_ERR(new_dir))
844 : : return new_dir;
845 [ # # ]: 0 : if (IS_ERR_OR_NULL(old_dentry))
846 : : return old_dentry;
847 : :
848 : 0 : trap = lock_rename(new_dir, old_dir);
849 : : /* Source or destination directories don't exist? */
850 [ # # # # ]: 0 : if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
851 : : goto exit;
852 : : /* Source does not exist, cyclic rename, or mountpoint? */
853 [ # # # # : 0 : if (d_really_is_negative(old_dentry) || old_dentry == trap ||
# # ]
854 : : d_mountpoint(old_dentry))
855 : : goto exit;
856 : 0 : dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
857 : : /* Lookup failed, cyclic rename or target exists? */
858 [ # # # # : 0 : if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
# # ]
859 : : goto exit;
860 : :
861 : 0 : take_dentry_name_snapshot(&old_name, old_dentry);
862 : :
863 : 0 : error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
864 : : dentry, 0);
865 [ # # ]: 0 : if (error) {
866 : 0 : release_dentry_name_snapshot(&old_name);
867 : 0 : goto exit;
868 : : }
869 : 0 : d_move(old_dentry, dentry);
870 : 0 : fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
871 : : d_is_dir(old_dentry),
872 : : NULL, old_dentry);
873 : 0 : release_dentry_name_snapshot(&old_name);
874 : 0 : unlock_rename(new_dir, old_dir);
875 : 0 : dput(dentry);
876 : 0 : return old_dentry;
877 : : exit:
878 [ # # # # ]: 0 : if (dentry && !IS_ERR(dentry))
879 : 0 : dput(dentry);
880 : 0 : unlock_rename(new_dir, old_dir);
881 [ # # ]: 0 : if (IS_ERR(dentry))
882 : 0 : return dentry;
883 : : return ERR_PTR(-EINVAL);
884 : : }
885 : : EXPORT_SYMBOL_GPL(debugfs_rename);
886 : :
887 : : /**
888 : : * debugfs_initialized - Tells whether debugfs has been registered
889 : : */
890 : 808 : bool debugfs_initialized(void)
891 : : {
892 : 808 : return debugfs_registered;
893 : : }
894 : : EXPORT_SYMBOL_GPL(debugfs_initialized);
895 : :
896 : 404 : static int __init debugfs_init(void)
897 : : {
898 : : int retval;
899 : :
900 : 404 : retval = sysfs_create_mount_point(kernel_kobj, "debug");
901 [ + - ]: 404 : if (retval)
902 : : return retval;
903 : :
904 : 404 : retval = register_filesystem(&debug_fs_type);
905 [ - + ]: 404 : if (retval)
906 : 0 : sysfs_remove_mount_point(kernel_kobj, "debug");
907 : : else
908 : 404 : debugfs_registered = true;
909 : :
910 : 404 : return retval;
911 : : }
912 : : core_initcall(debugfs_init);
913 : :
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