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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
4282d606 SRRH |
2 | /* |
3 | * inode.c - part of tracefs, a pseudo file system for activating tracing | |
4 | * | |
5 | * Based on debugfs by: Greg Kroah-Hartman <greg@kroah.com> | |
6 | * | |
7 | * Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com> | |
8 | * | |
4282d606 | 9 | * tracefs is the file system that is used by the tracing infrastructure. |
4282d606 SRRH |
10 | */ |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/fs.h> | |
14 | #include <linux/mount.h> | |
cc31004a | 15 | #include <linux/kobject.h> |
4282d606 SRRH |
16 | #include <linux/namei.h> |
17 | #include <linux/tracefs.h> | |
18 | #include <linux/fsnotify.h> | |
bf8e6021 | 19 | #include <linux/security.h> |
4282d606 SRRH |
20 | #include <linux/seq_file.h> |
21 | #include <linux/parser.h> | |
22 | #include <linux/magic.h> | |
23 | #include <linux/slab.h> | |
ba37ff75 | 24 | #include "internal.h" |
4282d606 SRRH |
25 | |
26 | #define TRACEFS_DEFAULT_MODE 0700 | |
ba37ff75 | 27 | static struct kmem_cache *tracefs_inode_cachep __ro_after_init; |
4282d606 SRRH |
28 | |
29 | static struct vfsmount *tracefs_mount; | |
30 | static int tracefs_mount_count; | |
31 | static bool tracefs_registered; | |
32 | ||
ba37ff75 AK |
33 | static struct inode *tracefs_alloc_inode(struct super_block *sb) |
34 | { | |
35 | struct tracefs_inode *ti; | |
36 | ||
37 | ti = kmem_cache_alloc(tracefs_inode_cachep, GFP_KERNEL); | |
38 | if (!ti) | |
39 | return NULL; | |
40 | ||
41 | ti->flags = 0; | |
42 | ||
43 | return &ti->vfs_inode; | |
44 | } | |
45 | ||
46 | static void tracefs_free_inode(struct inode *inode) | |
47 | { | |
48 | kmem_cache_free(tracefs_inode_cachep, get_tracefs(inode)); | |
49 | } | |
50 | ||
4282d606 SRRH |
51 | static ssize_t default_read_file(struct file *file, char __user *buf, |
52 | size_t count, loff_t *ppos) | |
53 | { | |
54 | return 0; | |
55 | } | |
56 | ||
57 | static ssize_t default_write_file(struct file *file, const char __user *buf, | |
58 | size_t count, loff_t *ppos) | |
59 | { | |
60 | return count; | |
61 | } | |
62 | ||
63 | static const struct file_operations tracefs_file_operations = { | |
64 | .read = default_read_file, | |
65 | .write = default_write_file, | |
66 | .open = simple_open, | |
67 | .llseek = noop_llseek, | |
68 | }; | |
69 | ||
eae47358 SRRH |
70 | static struct tracefs_dir_ops { |
71 | int (*mkdir)(const char *name); | |
72 | int (*rmdir)(const char *name); | |
5248ee85 | 73 | } tracefs_ops __ro_after_init; |
eae47358 SRRH |
74 | |
75 | static char *get_dname(struct dentry *dentry) | |
76 | { | |
77 | const char *dname; | |
78 | char *name; | |
79 | int len = dentry->d_name.len; | |
80 | ||
81 | dname = dentry->d_name.name; | |
82 | name = kmalloc(len + 1, GFP_KERNEL); | |
83 | if (!name) | |
84 | return NULL; | |
85 | memcpy(name, dname, len); | |
86 | name[len] = 0; | |
87 | return name; | |
88 | } | |
89 | ||
c54bd91e | 90 | static int tracefs_syscall_mkdir(struct mnt_idmap *idmap, |
549c7297 CB |
91 | struct inode *inode, struct dentry *dentry, |
92 | umode_t mode) | |
eae47358 SRRH |
93 | { |
94 | char *name; | |
95 | int ret; | |
96 | ||
97 | name = get_dname(dentry); | |
98 | if (!name) | |
99 | return -ENOMEM; | |
100 | ||
101 | /* | |
102 | * The mkdir call can call the generic functions that create | |
103 | * the files within the tracefs system. It is up to the individual | |
104 | * mkdir routine to handle races. | |
105 | */ | |
5955102c | 106 | inode_unlock(inode); |
eae47358 | 107 | ret = tracefs_ops.mkdir(name); |
5955102c | 108 | inode_lock(inode); |
eae47358 SRRH |
109 | |
110 | kfree(name); | |
111 | ||
112 | return ret; | |
113 | } | |
114 | ||
115 | static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry) | |
116 | { | |
117 | char *name; | |
118 | int ret; | |
119 | ||
120 | name = get_dname(dentry); | |
121 | if (!name) | |
122 | return -ENOMEM; | |
123 | ||
124 | /* | |
125 | * The rmdir call can call the generic functions that create | |
126 | * the files within the tracefs system. It is up to the individual | |
127 | * rmdir routine to handle races. | |
128 | * This time we need to unlock not only the parent (inode) but | |
129 | * also the directory that is being deleted. | |
130 | */ | |
5955102c | 131 | inode_unlock(inode); |
ee34c52c | 132 | inode_unlock(d_inode(dentry)); |
eae47358 SRRH |
133 | |
134 | ret = tracefs_ops.rmdir(name); | |
135 | ||
5955102c | 136 | inode_lock_nested(inode, I_MUTEX_PARENT); |
ee34c52c | 137 | inode_lock(d_inode(dentry)); |
eae47358 SRRH |
138 | |
139 | kfree(name); | |
140 | ||
141 | return ret; | |
142 | } | |
143 | ||
144 | static const struct inode_operations tracefs_dir_inode_operations = { | |
145 | .lookup = simple_lookup, | |
146 | .mkdir = tracefs_syscall_mkdir, | |
147 | .rmdir = tracefs_syscall_rmdir, | |
148 | }; | |
149 | ||
2c6b6b10 | 150 | struct inode *tracefs_get_inode(struct super_block *sb) |
4282d606 SRRH |
151 | { |
152 | struct inode *inode = new_inode(sb); | |
153 | if (inode) { | |
154 | inode->i_ino = get_next_ino(); | |
079cf91e | 155 | simple_inode_init_ts(inode); |
4282d606 SRRH |
156 | } |
157 | return inode; | |
158 | } | |
159 | ||
160 | struct tracefs_mount_opts { | |
161 | kuid_t uid; | |
162 | kgid_t gid; | |
163 | umode_t mode; | |
47311db8 BN |
164 | /* Opt_* bitfield. */ |
165 | unsigned int opts; | |
4282d606 SRRH |
166 | }; |
167 | ||
168 | enum { | |
169 | Opt_uid, | |
170 | Opt_gid, | |
171 | Opt_mode, | |
172 | Opt_err | |
173 | }; | |
174 | ||
175 | static const match_table_t tokens = { | |
176 | {Opt_uid, "uid=%u"}, | |
177 | {Opt_gid, "gid=%u"}, | |
178 | {Opt_mode, "mode=%o"}, | |
179 | {Opt_err, NULL} | |
180 | }; | |
181 | ||
182 | struct tracefs_fs_info { | |
183 | struct tracefs_mount_opts mount_opts; | |
184 | }; | |
185 | ||
48b27b6b SRV |
186 | static void change_gid(struct dentry *dentry, kgid_t gid) |
187 | { | |
188 | if (!dentry->d_inode) | |
189 | return; | |
190 | dentry->d_inode->i_gid = gid; | |
191 | } | |
192 | ||
193 | /* | |
194 | * Taken from d_walk, but without he need for handling renames. | |
195 | * Nothing can be renamed while walking the list, as tracefs | |
196 | * does not support renames. This is only called when mounting | |
197 | * or remounting the file system, to set all the files to | |
198 | * the given gid. | |
199 | */ | |
200 | static void set_gid(struct dentry *parent, kgid_t gid) | |
201 | { | |
202 | struct dentry *this_parent; | |
203 | struct list_head *next; | |
204 | ||
205 | this_parent = parent; | |
206 | spin_lock(&this_parent->d_lock); | |
207 | ||
208 | change_gid(this_parent, gid); | |
209 | repeat: | |
210 | next = this_parent->d_subdirs.next; | |
211 | resume: | |
212 | while (next != &this_parent->d_subdirs) { | |
213 | struct list_head *tmp = next; | |
214 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); | |
215 | next = tmp->next; | |
216 | ||
217 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
218 | ||
219 | change_gid(dentry, gid); | |
220 | ||
221 | if (!list_empty(&dentry->d_subdirs)) { | |
222 | spin_unlock(&this_parent->d_lock); | |
223 | spin_release(&dentry->d_lock.dep_map, _RET_IP_); | |
224 | this_parent = dentry; | |
225 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); | |
226 | goto repeat; | |
227 | } | |
228 | spin_unlock(&dentry->d_lock); | |
229 | } | |
230 | /* | |
231 | * All done at this level ... ascend and resume the search. | |
232 | */ | |
233 | rcu_read_lock(); | |
234 | ascend: | |
235 | if (this_parent != parent) { | |
236 | struct dentry *child = this_parent; | |
237 | this_parent = child->d_parent; | |
238 | ||
239 | spin_unlock(&child->d_lock); | |
240 | spin_lock(&this_parent->d_lock); | |
241 | ||
242 | /* go into the first sibling still alive */ | |
243 | do { | |
244 | next = child->d_child.next; | |
245 | if (next == &this_parent->d_subdirs) | |
246 | goto ascend; | |
247 | child = list_entry(next, struct dentry, d_child); | |
248 | } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); | |
249 | rcu_read_unlock(); | |
250 | goto resume; | |
251 | } | |
252 | rcu_read_unlock(); | |
253 | spin_unlock(&this_parent->d_lock); | |
254 | return; | |
255 | } | |
256 | ||
4282d606 SRRH |
257 | static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts) |
258 | { | |
259 | substring_t args[MAX_OPT_ARGS]; | |
260 | int option; | |
261 | int token; | |
262 | kuid_t uid; | |
263 | kgid_t gid; | |
264 | char *p; | |
265 | ||
47311db8 | 266 | opts->opts = 0; |
4282d606 SRRH |
267 | opts->mode = TRACEFS_DEFAULT_MODE; |
268 | ||
269 | while ((p = strsep(&data, ",")) != NULL) { | |
270 | if (!*p) | |
271 | continue; | |
272 | ||
273 | token = match_token(p, tokens, args); | |
274 | switch (token) { | |
275 | case Opt_uid: | |
276 | if (match_int(&args[0], &option)) | |
277 | return -EINVAL; | |
278 | uid = make_kuid(current_user_ns(), option); | |
279 | if (!uid_valid(uid)) | |
280 | return -EINVAL; | |
281 | opts->uid = uid; | |
282 | break; | |
283 | case Opt_gid: | |
284 | if (match_int(&args[0], &option)) | |
285 | return -EINVAL; | |
286 | gid = make_kgid(current_user_ns(), option); | |
287 | if (!gid_valid(gid)) | |
288 | return -EINVAL; | |
289 | opts->gid = gid; | |
290 | break; | |
291 | case Opt_mode: | |
292 | if (match_octal(&args[0], &option)) | |
293 | return -EINVAL; | |
294 | opts->mode = option & S_IALLUGO; | |
295 | break; | |
296 | /* | |
297 | * We might like to report bad mount options here; | |
298 | * but traditionally tracefs has ignored all mount options | |
299 | */ | |
300 | } | |
47311db8 BN |
301 | |
302 | opts->opts |= BIT(token); | |
4282d606 SRRH |
303 | } |
304 | ||
305 | return 0; | |
306 | } | |
307 | ||
47311db8 | 308 | static int tracefs_apply_options(struct super_block *sb, bool remount) |
4282d606 SRRH |
309 | { |
310 | struct tracefs_fs_info *fsi = sb->s_fs_info; | |
ee34c52c | 311 | struct inode *inode = d_inode(sb->s_root); |
4282d606 | 312 | struct tracefs_mount_opts *opts = &fsi->mount_opts; |
08662977 | 313 | umode_t tmp_mode; |
4282d606 | 314 | |
47311db8 BN |
315 | /* |
316 | * On remount, only reset mode/uid/gid if they were provided as mount | |
317 | * options. | |
318 | */ | |
319 | ||
320 | if (!remount || opts->opts & BIT(Opt_mode)) { | |
08662977 SG |
321 | tmp_mode = READ_ONCE(inode->i_mode) & ~S_IALLUGO; |
322 | tmp_mode |= opts->mode; | |
323 | WRITE_ONCE(inode->i_mode, tmp_mode); | |
47311db8 | 324 | } |
4282d606 | 325 | |
47311db8 BN |
326 | if (!remount || opts->opts & BIT(Opt_uid)) |
327 | inode->i_uid = opts->uid; | |
851e99eb | 328 | |
47311db8 BN |
329 | if (!remount || opts->opts & BIT(Opt_gid)) { |
330 | /* Set all the group ids to the mount option */ | |
331 | set_gid(sb->s_root, opts->gid); | |
332 | } | |
4282d606 SRRH |
333 | |
334 | return 0; | |
335 | } | |
336 | ||
337 | static int tracefs_remount(struct super_block *sb, int *flags, char *data) | |
338 | { | |
339 | int err; | |
340 | struct tracefs_fs_info *fsi = sb->s_fs_info; | |
341 | ||
342 | sync_filesystem(sb); | |
343 | err = tracefs_parse_options(data, &fsi->mount_opts); | |
344 | if (err) | |
345 | goto fail; | |
346 | ||
47311db8 | 347 | tracefs_apply_options(sb, true); |
4282d606 SRRH |
348 | |
349 | fail: | |
350 | return err; | |
351 | } | |
352 | ||
353 | static int tracefs_show_options(struct seq_file *m, struct dentry *root) | |
354 | { | |
355 | struct tracefs_fs_info *fsi = root->d_sb->s_fs_info; | |
356 | struct tracefs_mount_opts *opts = &fsi->mount_opts; | |
357 | ||
358 | if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) | |
359 | seq_printf(m, ",uid=%u", | |
360 | from_kuid_munged(&init_user_ns, opts->uid)); | |
361 | if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) | |
362 | seq_printf(m, ",gid=%u", | |
363 | from_kgid_munged(&init_user_ns, opts->gid)); | |
364 | if (opts->mode != TRACEFS_DEFAULT_MODE) | |
365 | seq_printf(m, ",mode=%o", opts->mode); | |
366 | ||
367 | return 0; | |
368 | } | |
369 | ||
370 | static const struct super_operations tracefs_super_operations = { | |
ba37ff75 AK |
371 | .alloc_inode = tracefs_alloc_inode, |
372 | .free_inode = tracefs_free_inode, | |
373 | .drop_inode = generic_delete_inode, | |
4282d606 SRRH |
374 | .statfs = simple_statfs, |
375 | .remount_fs = tracefs_remount, | |
376 | .show_options = tracefs_show_options, | |
377 | }; | |
378 | ||
27152bce AK |
379 | static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode) |
380 | { | |
381 | struct tracefs_inode *ti; | |
382 | ||
383 | if (!dentry || !inode) | |
384 | return; | |
385 | ||
386 | ti = get_tracefs(inode); | |
387 | if (ti && ti->flags & TRACEFS_EVENT_INODE) | |
5790b1fb | 388 | eventfs_set_ei_status_free(ti, dentry); |
27152bce AK |
389 | iput(inode); |
390 | } | |
391 | ||
392 | static const struct dentry_operations tracefs_dentry_operations = { | |
393 | .d_iput = tracefs_dentry_iput, | |
394 | }; | |
395 | ||
4282d606 SRRH |
396 | static int trace_fill_super(struct super_block *sb, void *data, int silent) |
397 | { | |
cda37124 | 398 | static const struct tree_descr trace_files[] = {{""}}; |
4282d606 SRRH |
399 | struct tracefs_fs_info *fsi; |
400 | int err; | |
401 | ||
4282d606 SRRH |
402 | fsi = kzalloc(sizeof(struct tracefs_fs_info), GFP_KERNEL); |
403 | sb->s_fs_info = fsi; | |
404 | if (!fsi) { | |
405 | err = -ENOMEM; | |
406 | goto fail; | |
407 | } | |
408 | ||
409 | err = tracefs_parse_options(data, &fsi->mount_opts); | |
410 | if (err) | |
411 | goto fail; | |
412 | ||
413 | err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files); | |
414 | if (err) | |
415 | goto fail; | |
416 | ||
417 | sb->s_op = &tracefs_super_operations; | |
27152bce | 418 | sb->s_d_op = &tracefs_dentry_operations; |
4282d606 | 419 | |
47311db8 | 420 | tracefs_apply_options(sb, false); |
4282d606 SRRH |
421 | |
422 | return 0; | |
423 | ||
424 | fail: | |
425 | kfree(fsi); | |
426 | sb->s_fs_info = NULL; | |
427 | return err; | |
428 | } | |
429 | ||
430 | static struct dentry *trace_mount(struct file_system_type *fs_type, | |
431 | int flags, const char *dev_name, | |
432 | void *data) | |
433 | { | |
434 | return mount_single(fs_type, flags, data, trace_fill_super); | |
435 | } | |
436 | ||
437 | static struct file_system_type trace_fs_type = { | |
438 | .owner = THIS_MODULE, | |
439 | .name = "tracefs", | |
440 | .mount = trace_mount, | |
441 | .kill_sb = kill_litter_super, | |
442 | }; | |
443 | MODULE_ALIAS_FS("tracefs"); | |
444 | ||
2c6b6b10 | 445 | struct dentry *tracefs_start_creating(const char *name, struct dentry *parent) |
4282d606 SRRH |
446 | { |
447 | struct dentry *dentry; | |
448 | int error; | |
449 | ||
450 | pr_debug("tracefs: creating file '%s'\n",name); | |
451 | ||
452 | error = simple_pin_fs(&trace_fs_type, &tracefs_mount, | |
453 | &tracefs_mount_count); | |
454 | if (error) | |
455 | return ERR_PTR(error); | |
456 | ||
457 | /* If the parent is not specified, we create it in the root. | |
458 | * We need the root dentry to do this, which is in the super | |
459 | * block. A pointer to that is in the struct vfsmount that we | |
460 | * have around. | |
461 | */ | |
462 | if (!parent) | |
463 | parent = tracefs_mount->mnt_root; | |
464 | ||
ee34c52c SRV |
465 | inode_lock(d_inode(parent)); |
466 | if (unlikely(IS_DEADDIR(d_inode(parent)))) | |
a3d1e7eb AV |
467 | dentry = ERR_PTR(-ENOENT); |
468 | else | |
469 | dentry = lookup_one_len(name, parent, strlen(name)); | |
ee34c52c | 470 | if (!IS_ERR(dentry) && d_inode(dentry)) { |
4282d606 SRRH |
471 | dput(dentry); |
472 | dentry = ERR_PTR(-EEXIST); | |
473 | } | |
d227c3ae DB |
474 | |
475 | if (IS_ERR(dentry)) { | |
ee34c52c | 476 | inode_unlock(d_inode(parent)); |
d227c3ae DB |
477 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); |
478 | } | |
479 | ||
4282d606 SRRH |
480 | return dentry; |
481 | } | |
482 | ||
2c6b6b10 | 483 | struct dentry *tracefs_failed_creating(struct dentry *dentry) |
4282d606 | 484 | { |
ee34c52c | 485 | inode_unlock(d_inode(dentry->d_parent)); |
4282d606 SRRH |
486 | dput(dentry); |
487 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
488 | return NULL; | |
489 | } | |
490 | ||
2c6b6b10 | 491 | struct dentry *tracefs_end_creating(struct dentry *dentry) |
4282d606 | 492 | { |
ee34c52c | 493 | inode_unlock(d_inode(dentry->d_parent)); |
4282d606 SRRH |
494 | return dentry; |
495 | } | |
496 | ||
a3760079 AK |
497 | /** |
498 | * eventfs_start_creating - start the process of creating a dentry | |
499 | * @name: Name of the file created for the dentry | |
500 | * @parent: The parent dentry where this dentry will be created | |
501 | * | |
502 | * This is a simple helper function for the dynamically created eventfs | |
503 | * files. When the directory of the eventfs files are accessed, their | |
504 | * dentries are created on the fly. This function is used to start that | |
505 | * process. | |
506 | */ | |
507 | struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) | |
508 | { | |
509 | struct dentry *dentry; | |
510 | int error; | |
511 | ||
fc456122 SRG |
512 | /* Must always have a parent. */ |
513 | if (WARN_ON_ONCE(!parent)) | |
514 | return ERR_PTR(-EINVAL); | |
515 | ||
a3760079 AK |
516 | error = simple_pin_fs(&trace_fs_type, &tracefs_mount, |
517 | &tracefs_mount_count); | |
518 | if (error) | |
519 | return ERR_PTR(error); | |
520 | ||
a3760079 AK |
521 | if (unlikely(IS_DEADDIR(parent->d_inode))) |
522 | dentry = ERR_PTR(-ENOENT); | |
523 | else | |
524 | dentry = lookup_one_len(name, parent, strlen(name)); | |
525 | ||
526 | if (!IS_ERR(dentry) && dentry->d_inode) { | |
527 | dput(dentry); | |
528 | dentry = ERR_PTR(-EEXIST); | |
529 | } | |
530 | ||
531 | if (IS_ERR(dentry)) | |
532 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
533 | ||
534 | return dentry; | |
535 | } | |
536 | ||
537 | /** | |
538 | * eventfs_failed_creating - clean up a failed eventfs dentry creation | |
539 | * @dentry: The dentry to clean up | |
540 | * | |
541 | * If after calling eventfs_start_creating(), a failure is detected, the | |
542 | * resources created by eventfs_start_creating() needs to be cleaned up. In | |
543 | * that case, this function should be called to perform that clean up. | |
544 | */ | |
545 | struct dentry *eventfs_failed_creating(struct dentry *dentry) | |
546 | { | |
547 | dput(dentry); | |
548 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
549 | return NULL; | |
550 | } | |
551 | ||
552 | /** | |
553 | * eventfs_end_creating - Finish the process of creating a eventfs dentry | |
554 | * @dentry: The dentry that has successfully been created. | |
555 | * | |
556 | * This function is currently just a place holder to match | |
557 | * eventfs_start_creating(). In case any synchronization needs to be added, | |
558 | * this function will be used to implement that without having to modify | |
559 | * the callers of eventfs_start_creating(). | |
560 | */ | |
561 | struct dentry *eventfs_end_creating(struct dentry *dentry) | |
562 | { | |
563 | return dentry; | |
564 | } | |
565 | ||
4282d606 SRRH |
566 | /** |
567 | * tracefs_create_file - create a file in the tracefs filesystem | |
568 | * @name: a pointer to a string containing the name of the file to create. | |
569 | * @mode: the permission that the file should have. | |
570 | * @parent: a pointer to the parent dentry for this file. This should be a | |
571 | * directory dentry if set. If this parameter is NULL, then the | |
572 | * file will be created in the root of the tracefs filesystem. | |
573 | * @data: a pointer to something that the caller will want to get to later | |
574 | * on. The inode.i_private pointer will point to this value on | |
575 | * the open() call. | |
576 | * @fops: a pointer to a struct file_operations that should be used for | |
577 | * this file. | |
578 | * | |
579 | * This is the basic "create a file" function for tracefs. It allows for a | |
580 | * wide range of flexibility in creating a file, or a directory (if you want | |
581 | * to create a directory, the tracefs_create_dir() function is | |
582 | * recommended to be used instead.) | |
583 | * | |
584 | * This function will return a pointer to a dentry if it succeeds. This | |
585 | * pointer must be passed to the tracefs_remove() function when the file is | |
586 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
587 | * you are responsible here.) If an error occurs, %NULL will be returned. | |
588 | * | |
589 | * If tracefs is not enabled in the kernel, the value -%ENODEV will be | |
590 | * returned. | |
591 | */ | |
592 | struct dentry *tracefs_create_file(const char *name, umode_t mode, | |
593 | struct dentry *parent, void *data, | |
594 | const struct file_operations *fops) | |
595 | { | |
596 | struct dentry *dentry; | |
597 | struct inode *inode; | |
598 | ||
bf8e6021 SRV |
599 | if (security_locked_down(LOCKDOWN_TRACEFS)) |
600 | return NULL; | |
601 | ||
4282d606 SRRH |
602 | if (!(mode & S_IFMT)) |
603 | mode |= S_IFREG; | |
604 | BUG_ON(!S_ISREG(mode)); | |
2c6b6b10 | 605 | dentry = tracefs_start_creating(name, parent); |
4282d606 SRRH |
606 | |
607 | if (IS_ERR(dentry)) | |
608 | return NULL; | |
609 | ||
610 | inode = tracefs_get_inode(dentry->d_sb); | |
611 | if (unlikely(!inode)) | |
2c6b6b10 | 612 | return tracefs_failed_creating(dentry); |
4282d606 SRRH |
613 | |
614 | inode->i_mode = mode; | |
3ed270b1 | 615 | inode->i_fop = fops ? fops : &tracefs_file_operations; |
4282d606 | 616 | inode->i_private = data; |
ee7f3666 SRV |
617 | inode->i_uid = d_inode(dentry->d_parent)->i_uid; |
618 | inode->i_gid = d_inode(dentry->d_parent)->i_gid; | |
4282d606 | 619 | d_instantiate(dentry, inode); |
ee34c52c | 620 | fsnotify_create(d_inode(dentry->d_parent), dentry); |
2c6b6b10 | 621 | return tracefs_end_creating(dentry); |
4282d606 SRRH |
622 | } |
623 | ||
eae47358 SRRH |
624 | static struct dentry *__create_dir(const char *name, struct dentry *parent, |
625 | const struct inode_operations *ops) | |
626 | { | |
2c6b6b10 | 627 | struct dentry *dentry = tracefs_start_creating(name, parent); |
eae47358 SRRH |
628 | struct inode *inode; |
629 | ||
630 | if (IS_ERR(dentry)) | |
631 | return NULL; | |
632 | ||
633 | inode = tracefs_get_inode(dentry->d_sb); | |
634 | if (unlikely(!inode)) | |
2c6b6b10 | 635 | return tracefs_failed_creating(dentry); |
eae47358 | 636 | |
49d67e44 SRV |
637 | /* Do not set bits for OTH */ |
638 | inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP; | |
eae47358 SRRH |
639 | inode->i_op = ops; |
640 | inode->i_fop = &simple_dir_operations; | |
ee7f3666 SRV |
641 | inode->i_uid = d_inode(dentry->d_parent)->i_uid; |
642 | inode->i_gid = d_inode(dentry->d_parent)->i_gid; | |
eae47358 SRRH |
643 | |
644 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
645 | inc_nlink(inode); | |
646 | d_instantiate(dentry, inode); | |
ee34c52c SRV |
647 | inc_nlink(d_inode(dentry->d_parent)); |
648 | fsnotify_mkdir(d_inode(dentry->d_parent), dentry); | |
2c6b6b10 | 649 | return tracefs_end_creating(dentry); |
eae47358 SRRH |
650 | } |
651 | ||
4282d606 SRRH |
652 | /** |
653 | * tracefs_create_dir - create a directory in the tracefs filesystem | |
654 | * @name: a pointer to a string containing the name of the directory to | |
655 | * create. | |
656 | * @parent: a pointer to the parent dentry for this file. This should be a | |
657 | * directory dentry if set. If this parameter is NULL, then the | |
658 | * directory will be created in the root of the tracefs filesystem. | |
659 | * | |
660 | * This function creates a directory in tracefs with the given name. | |
661 | * | |
662 | * This function will return a pointer to a dentry if it succeeds. This | |
663 | * pointer must be passed to the tracefs_remove() function when the file is | |
664 | * to be removed. If an error occurs, %NULL will be returned. | |
665 | * | |
666 | * If tracing is not enabled in the kernel, the value -%ENODEV will be | |
667 | * returned. | |
668 | */ | |
669 | struct dentry *tracefs_create_dir(const char *name, struct dentry *parent) | |
670 | { | |
51aab5ff SRG |
671 | if (security_locked_down(LOCKDOWN_TRACEFS)) |
672 | return NULL; | |
673 | ||
eae47358 SRRH |
674 | return __create_dir(name, parent, &simple_dir_inode_operations); |
675 | } | |
4282d606 | 676 | |
eae47358 SRRH |
677 | /** |
678 | * tracefs_create_instance_dir - create the tracing instances directory | |
679 | * @name: The name of the instances directory to create | |
680 | * @parent: The parent directory that the instances directory will exist | |
681 | * @mkdir: The function to call when a mkdir is performed. | |
682 | * @rmdir: The function to call when a rmdir is performed. | |
683 | * | |
684 | * Only one instances directory is allowed. | |
685 | * | |
93a8c044 | 686 | * The instances directory is special as it allows for mkdir and rmdir |
eae47358 | 687 | * to be done by userspace. When a mkdir or rmdir is performed, the inode |
f2cc020d | 688 | * locks are released and the methods passed in (@mkdir and @rmdir) are |
eae47358 SRRH |
689 | * called without locks and with the name of the directory being created |
690 | * within the instances directory. | |
691 | * | |
692 | * Returns the dentry of the instances directory. | |
693 | */ | |
5248ee85 ZM |
694 | __init struct dentry *tracefs_create_instance_dir(const char *name, |
695 | struct dentry *parent, | |
eae47358 SRRH |
696 | int (*mkdir)(const char *name), |
697 | int (*rmdir)(const char *name)) | |
698 | { | |
699 | struct dentry *dentry; | |
700 | ||
701 | /* Only allow one instance of the instances directory. */ | |
702 | if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir)) | |
4282d606 SRRH |
703 | return NULL; |
704 | ||
eae47358 SRRH |
705 | dentry = __create_dir(name, parent, &tracefs_dir_inode_operations); |
706 | if (!dentry) | |
707 | return NULL; | |
4282d606 | 708 | |
eae47358 SRRH |
709 | tracefs_ops.mkdir = mkdir; |
710 | tracefs_ops.rmdir = rmdir; | |
4282d606 | 711 | |
eae47358 | 712 | return dentry; |
4282d606 SRRH |
713 | } |
714 | ||
a3d1e7eb | 715 | static void remove_one(struct dentry *victim) |
4282d606 | 716 | { |
a3d1e7eb | 717 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); |
4282d606 SRRH |
718 | } |
719 | ||
720 | /** | |
a3d1e7eb | 721 | * tracefs_remove - recursively removes a directory |
4282d606 SRRH |
722 | * @dentry: a pointer to a the dentry of the directory to be removed. |
723 | * | |
724 | * This function recursively removes a directory tree in tracefs that | |
725 | * was previously created with a call to another tracefs function | |
726 | * (like tracefs_create_file() or variants thereof.) | |
727 | */ | |
a3d1e7eb | 728 | void tracefs_remove(struct dentry *dentry) |
4282d606 | 729 | { |
4282d606 SRRH |
730 | if (IS_ERR_OR_NULL(dentry)) |
731 | return; | |
732 | ||
a3d1e7eb AV |
733 | simple_pin_fs(&trace_fs_type, &tracefs_mount, &tracefs_mount_count); |
734 | simple_recursive_removal(dentry, remove_one); | |
735 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
4282d606 SRRH |
736 | } |
737 | ||
738 | /** | |
739 | * tracefs_initialized - Tells whether tracefs has been registered | |
740 | */ | |
741 | bool tracefs_initialized(void) | |
742 | { | |
743 | return tracefs_registered; | |
744 | } | |
745 | ||
ba37ff75 AK |
746 | static void init_once(void *foo) |
747 | { | |
748 | struct tracefs_inode *ti = (struct tracefs_inode *) foo; | |
749 | ||
750 | inode_init_once(&ti->vfs_inode); | |
751 | } | |
752 | ||
4282d606 SRRH |
753 | static int __init tracefs_init(void) |
754 | { | |
755 | int retval; | |
756 | ||
ba37ff75 AK |
757 | tracefs_inode_cachep = kmem_cache_create("tracefs_inode_cache", |
758 | sizeof(struct tracefs_inode), | |
759 | 0, (SLAB_RECLAIM_ACCOUNT| | |
760 | SLAB_MEM_SPREAD| | |
761 | SLAB_ACCOUNT), | |
762 | init_once); | |
763 | if (!tracefs_inode_cachep) | |
764 | return -ENOMEM; | |
765 | ||
f9bb4882 EB |
766 | retval = sysfs_create_mount_point(kernel_kobj, "tracing"); |
767 | if (retval) | |
cc31004a SRRH |
768 | return -EINVAL; |
769 | ||
4282d606 SRRH |
770 | retval = register_filesystem(&trace_fs_type); |
771 | if (!retval) | |
772 | tracefs_registered = true; | |
773 | ||
774 | return retval; | |
775 | } | |
776 | core_initcall(tracefs_init); |