Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * fs/kernfs/dir.c - kernfs directory implementation
4 : *
5 : * Copyright (c) 2001-3 Patrick Mochel
6 : * Copyright (c) 2007 SUSE Linux Products GmbH
7 : * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8 : */
9 :
10 : #include <linux/sched.h>
11 : #include <linux/fs.h>
12 : #include <linux/namei.h>
13 : #include <linux/idr.h>
14 : #include <linux/slab.h>
15 : #include <linux/security.h>
16 : #include <linux/hash.h>
17 :
18 : #include "kernfs-internal.h"
19 :
20 : DEFINE_MUTEX(kernfs_mutex);
21 : static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */
22 : static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */
23 : static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */
24 :
25 : #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
26 :
27 34388 : static bool kernfs_active(struct kernfs_node *kn)
28 : {
29 103164 : lockdep_assert_held(&kernfs_mutex);
30 34388 : return atomic_read(&kn->active) >= 0;
31 : }
32 :
33 7986 : static bool kernfs_lockdep(struct kernfs_node *kn)
34 : {
35 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
36 7986 : return kn->flags & KERNFS_LOCKDEP;
37 : #else
38 : return false;
39 : #endif
40 : }
41 :
42 0 : static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen)
43 : {
44 0 : if (!kn)
45 0 : return strlcpy(buf, "(null)", buflen);
46 :
47 0 : return strlcpy(buf, kn->parent ? kn->name : "/", buflen);
48 : }
49 :
50 : /* kernfs_node_depth - compute depth from @from to @to */
51 640 : static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to)
52 : {
53 320 : size_t depth = 0;
54 :
55 1874 : while (to->parent && to != from) {
56 1234 : depth++;
57 1234 : to = to->parent;
58 : }
59 640 : return depth;
60 : }
61 :
62 320 : static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
63 : struct kernfs_node *b)
64 : {
65 320 : size_t da, db;
66 320 : struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b);
67 :
68 320 : if (ra != rb)
69 : return NULL;
70 :
71 320 : da = kernfs_depth(ra->kn, a);
72 320 : db = kernfs_depth(rb->kn, b);
73 :
74 320 : while (da > db) {
75 0 : a = a->parent;
76 0 : da--;
77 : }
78 937 : while (db > da) {
79 617 : b = b->parent;
80 617 : db--;
81 : }
82 :
83 : /* worst case b and a will be the same at root */
84 320 : while (b != a) {
85 0 : b = b->parent;
86 0 : a = a->parent;
87 : }
88 :
89 : return a;
90 : }
91 :
92 : /**
93 : * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to,
94 : * where kn_from is treated as root of the path.
95 : * @kn_from: kernfs node which should be treated as root for the path
96 : * @kn_to: kernfs node to which path is needed
97 : * @buf: buffer to copy the path into
98 : * @buflen: size of @buf
99 : *
100 : * We need to handle couple of scenarios here:
101 : * [1] when @kn_from is an ancestor of @kn_to at some level
102 : * kn_from: /n1/n2/n3
103 : * kn_to: /n1/n2/n3/n4/n5
104 : * result: /n4/n5
105 : *
106 : * [2] when @kn_from is on a different hierarchy and we need to find common
107 : * ancestor between @kn_from and @kn_to.
108 : * kn_from: /n1/n2/n3/n4
109 : * kn_to: /n1/n2/n5
110 : * result: /../../n5
111 : * OR
112 : * kn_from: /n1/n2/n3/n4/n5 [depth=5]
113 : * kn_to: /n1/n2/n3 [depth=3]
114 : * result: /../..
115 : *
116 : * [3] when @kn_to is NULL result will be "(null)"
117 : *
118 : * Returns the length of the full path. If the full length is equal to or
119 : * greater than @buflen, @buf contains the truncated path with the trailing
120 : * '\0'. On error, -errno is returned.
121 : */
122 898 : static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
123 : struct kernfs_node *kn_from,
124 : char *buf, size_t buflen)
125 : {
126 898 : struct kernfs_node *kn, *common;
127 898 : const char parent_str[] = "/..";
128 898 : size_t depth_from, depth_to, len = 0;
129 898 : int i, j;
130 :
131 898 : if (!kn_to)
132 0 : return strlcpy(buf, "(null)", buflen);
133 :
134 898 : if (!kn_from)
135 0 : kn_from = kernfs_root(kn_to)->kn;
136 :
137 898 : if (kn_from == kn_to)
138 578 : return strlcpy(buf, "/", buflen);
139 :
140 320 : if (!buf)
141 : return -EINVAL;
142 :
143 320 : common = kernfs_common_ancestor(kn_from, kn_to);
144 320 : if (WARN_ON(!common))
145 : return -EINVAL;
146 :
147 937 : depth_to = kernfs_depth(common, kn_to);
148 320 : depth_from = kernfs_depth(common, kn_from);
149 :
150 320 : buf[0] = '\0';
151 :
152 320 : for (i = 0; i < depth_from; i++)
153 0 : len += strlcpy(buf + len, parent_str,
154 : len < buflen ? buflen - len : 0);
155 :
156 : /* Calculate how many bytes we need for the rest */
157 937 : for (i = depth_to - 1; i >= 0; i--) {
158 953 : for (kn = kn_to, j = 0; j < i; j++)
159 336 : kn = kn->parent;
160 617 : len += strlcpy(buf + len, "/",
161 : len < buflen ? buflen - len : 0);
162 617 : len += strlcpy(buf + len, kn->name,
163 : len < buflen ? buflen - len : 0);
164 : }
165 :
166 320 : return len;
167 : }
168 :
169 : /**
170 : * kernfs_name - obtain the name of a given node
171 : * @kn: kernfs_node of interest
172 : * @buf: buffer to copy @kn's name into
173 : * @buflen: size of @buf
174 : *
175 : * Copies the name of @kn into @buf of @buflen bytes. The behavior is
176 : * similar to strlcpy(). It returns the length of @kn's name and if @buf
177 : * isn't long enough, it's filled upto @buflen-1 and nul terminated.
178 : *
179 : * Fills buffer with "(null)" if @kn is NULL.
180 : *
181 : * This function can be called from any context.
182 : */
183 0 : int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
184 : {
185 0 : unsigned long flags;
186 0 : int ret;
187 :
188 0 : spin_lock_irqsave(&kernfs_rename_lock, flags);
189 0 : ret = kernfs_name_locked(kn, buf, buflen);
190 0 : spin_unlock_irqrestore(&kernfs_rename_lock, flags);
191 0 : return ret;
192 : }
193 :
194 : /**
195 : * kernfs_path_from_node - build path of node @to relative to @from.
196 : * @from: parent kernfs_node relative to which we need to build the path
197 : * @to: kernfs_node of interest
198 : * @buf: buffer to copy @to's path into
199 : * @buflen: size of @buf
200 : *
201 : * Builds @to's path relative to @from in @buf. @from and @to must
202 : * be on the same kernfs-root. If @from is not parent of @to, then a relative
203 : * path (which includes '..'s) as needed to reach from @from to @to is
204 : * returned.
205 : *
206 : * Returns the length of the full path. If the full length is equal to or
207 : * greater than @buflen, @buf contains the truncated path with the trailing
208 : * '\0'. On error, -errno is returned.
209 : */
210 898 : int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from,
211 : char *buf, size_t buflen)
212 : {
213 898 : unsigned long flags;
214 898 : int ret;
215 :
216 898 : spin_lock_irqsave(&kernfs_rename_lock, flags);
217 898 : ret = kernfs_path_from_node_locked(to, from, buf, buflen);
218 898 : spin_unlock_irqrestore(&kernfs_rename_lock, flags);
219 898 : return ret;
220 : }
221 : EXPORT_SYMBOL_GPL(kernfs_path_from_node);
222 :
223 : /**
224 : * pr_cont_kernfs_name - pr_cont name of a kernfs_node
225 : * @kn: kernfs_node of interest
226 : *
227 : * This function can be called from any context.
228 : */
229 0 : void pr_cont_kernfs_name(struct kernfs_node *kn)
230 : {
231 0 : unsigned long flags;
232 :
233 0 : spin_lock_irqsave(&kernfs_rename_lock, flags);
234 :
235 0 : kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf));
236 0 : pr_cont("%s", kernfs_pr_cont_buf);
237 :
238 0 : spin_unlock_irqrestore(&kernfs_rename_lock, flags);
239 0 : }
240 :
241 : /**
242 : * pr_cont_kernfs_path - pr_cont path of a kernfs_node
243 : * @kn: kernfs_node of interest
244 : *
245 : * This function can be called from any context.
246 : */
247 0 : void pr_cont_kernfs_path(struct kernfs_node *kn)
248 : {
249 0 : unsigned long flags;
250 0 : int sz;
251 :
252 0 : spin_lock_irqsave(&kernfs_rename_lock, flags);
253 :
254 0 : sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf,
255 : sizeof(kernfs_pr_cont_buf));
256 0 : if (sz < 0) {
257 0 : pr_cont("(error)");
258 0 : goto out;
259 : }
260 :
261 0 : if (sz >= sizeof(kernfs_pr_cont_buf)) {
262 0 : pr_cont("(name too long)");
263 0 : goto out;
264 : }
265 :
266 0 : pr_cont("%s", kernfs_pr_cont_buf);
267 :
268 0 : out:
269 0 : spin_unlock_irqrestore(&kernfs_rename_lock, flags);
270 0 : }
271 :
272 : /**
273 : * kernfs_get_parent - determine the parent node and pin it
274 : * @kn: kernfs_node of interest
275 : *
276 : * Determines @kn's parent, pins and returns it. This function can be
277 : * called from any context.
278 : */
279 95 : struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
280 : {
281 95 : struct kernfs_node *parent;
282 95 : unsigned long flags;
283 :
284 95 : spin_lock_irqsave(&kernfs_rename_lock, flags);
285 95 : parent = kn->parent;
286 95 : kernfs_get(parent);
287 95 : spin_unlock_irqrestore(&kernfs_rename_lock, flags);
288 :
289 95 : return parent;
290 : }
291 :
292 : /**
293 : * kernfs_name_hash
294 : * @name: Null terminated string to hash
295 : * @ns: Namespace tag to hash
296 : *
297 : * Returns 31 bit hash of ns + name (so it fits in an off_t )
298 : */
299 12345 : static unsigned int kernfs_name_hash(const char *name, const void *ns)
300 : {
301 12345 : unsigned long hash = init_name_hash(ns);
302 12345 : unsigned int len = strlen(name);
303 141114 : while (len--)
304 128769 : hash = partial_name_hash(*name++, hash);
305 12345 : hash = end_name_hash(hash);
306 12345 : hash &= 0x7fffffffU;
307 : /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
308 12345 : if (hash < 2)
309 0 : hash += 2;
310 12345 : if (hash >= INT_MAX)
311 : hash = INT_MAX - 1;
312 12345 : return hash;
313 : }
314 :
315 38182 : static int kernfs_name_compare(unsigned int hash, const char *name,
316 : const void *ns, const struct kernfs_node *kn)
317 : {
318 38182 : if (hash < kn->hash)
319 : return -1;
320 17819 : if (hash > kn->hash)
321 : return 1;
322 2285 : if (ns < kn->ns)
323 : return -1;
324 2285 : if (ns > kn->ns)
325 : return 1;
326 2285 : return strcmp(name, kn->name);
327 : }
328 :
329 27240 : static int kernfs_sd_compare(const struct kernfs_node *left,
330 : const struct kernfs_node *right)
331 : {
332 27240 : return kernfs_name_compare(left->hash, left->name, left->ns, right);
333 : }
334 :
335 : /**
336 : * kernfs_link_sibling - link kernfs_node into sibling rbtree
337 : * @kn: kernfs_node of interest
338 : *
339 : * Link @kn into its sibling rbtree which starts from
340 : * @kn->parent->dir.children.
341 : *
342 : * Locking:
343 : * mutex_lock(kernfs_mutex)
344 : *
345 : * RETURNS:
346 : * 0 on susccess -EEXIST on failure.
347 : */
348 8509 : static int kernfs_link_sibling(struct kernfs_node *kn)
349 : {
350 8509 : struct rb_node **node = &kn->parent->dir.children.rb_node;
351 8509 : struct rb_node *parent = NULL;
352 :
353 35749 : while (*node) {
354 27240 : struct kernfs_node *pos;
355 27240 : int result;
356 :
357 27240 : pos = rb_to_kn(*node);
358 27240 : parent = *node;
359 27240 : result = kernfs_sd_compare(kn, pos);
360 27240 : if (result < 0)
361 15281 : node = &pos->rb.rb_left;
362 11959 : else if (result > 0)
363 11959 : node = &pos->rb.rb_right;
364 : else
365 : return -EEXIST;
366 : }
367 :
368 : /* add new node and rebalance the tree */
369 8509 : rb_link_node(&kn->rb, parent, node);
370 8509 : rb_insert_color(&kn->rb, &kn->parent->dir.children);
371 :
372 : /* successfully added, account subdir number */
373 8509 : if (kernfs_type(kn) == KERNFS_DIR)
374 781 : kn->parent->dir.subdirs++;
375 :
376 : return 0;
377 : }
378 :
379 : /**
380 : * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
381 : * @kn: kernfs_node of interest
382 : *
383 : * Try to unlink @kn from its sibling rbtree which starts from
384 : * kn->parent->dir.children. Returns %true if @kn was actually
385 : * removed, %false if @kn wasn't on the rbtree.
386 : *
387 : * Locking:
388 : * mutex_lock(kernfs_mutex)
389 : */
390 971 : static bool kernfs_unlink_sibling(struct kernfs_node *kn)
391 : {
392 971 : if (RB_EMPTY_NODE(&kn->rb))
393 : return false;
394 :
395 971 : if (kernfs_type(kn) == KERNFS_DIR)
396 139 : kn->parent->dir.subdirs--;
397 :
398 971 : rb_erase(&kn->rb, &kn->parent->dir.children);
399 971 : RB_CLEAR_NODE(&kn->rb);
400 971 : return true;
401 : }
402 :
403 : /**
404 : * kernfs_get_active - get an active reference to kernfs_node
405 : * @kn: kernfs_node to get an active reference to
406 : *
407 : * Get an active reference of @kn. This function is noop if @kn
408 : * is NULL.
409 : *
410 : * RETURNS:
411 : * Pointer to @kn on success, NULL on failure.
412 : */
413 2665 : struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
414 : {
415 2665 : if (unlikely(!kn))
416 : return NULL;
417 :
418 5330 : if (!atomic_inc_unless_negative(&kn->active))
419 : return NULL;
420 :
421 2665 : if (kernfs_lockdep(kn))
422 2510 : rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
423 : return kn;
424 : }
425 :
426 : /**
427 : * kernfs_put_active - put an active reference to kernfs_node
428 : * @kn: kernfs_node to put an active reference to
429 : *
430 : * Put an active reference to @kn. This function is noop if @kn
431 : * is NULL.
432 : */
433 3022 : void kernfs_put_active(struct kernfs_node *kn)
434 : {
435 3022 : int v;
436 :
437 3022 : if (unlikely(!kn))
438 : return;
439 :
440 3022 : if (kernfs_lockdep(kn))
441 2712 : rwsem_release(&kn->dep_map, _RET_IP_);
442 3022 : v = atomic_dec_return(&kn->active);
443 3022 : if (likely(v != KN_DEACTIVATED_BIAS))
444 : return;
445 :
446 108 : wake_up_all(&kernfs_root(kn)->deactivate_waitq);
447 : }
448 :
449 : /**
450 : * kernfs_drain - drain kernfs_node
451 : * @kn: kernfs_node to drain
452 : *
453 : * Drain existing usages and nuke all existing mmaps of @kn. Mutiple
454 : * removers may invoke this function concurrently on @kn and all will
455 : * return after draining is complete.
456 : */
457 971 : static void kernfs_drain(struct kernfs_node *kn)
458 : __releases(&kernfs_mutex) __acquires(&kernfs_mutex)
459 : {
460 971 : struct kernfs_root *root = kernfs_root(kn);
461 :
462 2913 : lockdep_assert_held(&kernfs_mutex);
463 971 : WARN_ON_ONCE(kernfs_active(kn));
464 :
465 971 : mutex_unlock(&kernfs_mutex);
466 :
467 971 : if (kernfs_lockdep(kn)) {
468 830 : rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
469 830 : if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
470 971 : lock_contended(&kn->dep_map, _RET_IP_);
471 : }
472 :
473 : /* but everyone should wait for draining */
474 971 : wait_event(root->deactivate_waitq,
475 : atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
476 :
477 971 : if (kernfs_lockdep(kn)) {
478 830 : lock_acquired(&kn->dep_map, _RET_IP_);
479 830 : rwsem_release(&kn->dep_map, _RET_IP_);
480 : }
481 :
482 971 : kernfs_drain_open_files(kn);
483 :
484 971 : mutex_lock(&kernfs_mutex);
485 971 : }
486 :
487 : /**
488 : * kernfs_get - get a reference count on a kernfs_node
489 : * @kn: the target kernfs_node
490 : */
491 14008 : void kernfs_get(struct kernfs_node *kn)
492 : {
493 14008 : if (kn) {
494 14008 : WARN_ON(!atomic_read(&kn->count));
495 14008 : atomic_inc(&kn->count);
496 : }
497 14008 : }
498 : EXPORT_SYMBOL_GPL(kernfs_get);
499 :
500 : /**
501 : * kernfs_put - put a reference count on a kernfs_node
502 : * @kn: the target kernfs_node
503 : *
504 : * Put a reference count of @kn and destroy it if it reached zero.
505 : */
506 4824 : void kernfs_put(struct kernfs_node *kn)
507 : {
508 4824 : struct kernfs_node *parent;
509 4824 : struct kernfs_root *root;
510 :
511 9359 : if (!kn || !atomic_dec_and_test(&kn->count))
512 3853 : return;
513 1942 : root = kernfs_root(kn);
514 971 : repeat:
515 : /*
516 : * Moving/renaming is always done while holding reference.
517 : * kn->parent won't change beneath us.
518 : */
519 971 : parent = kn->parent;
520 :
521 971 : WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
522 : "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
523 : parent ? parent->name : "", kn->name, atomic_read(&kn->active));
524 :
525 971 : if (kernfs_type(kn) == KERNFS_LINK)
526 2 : kernfs_put(kn->symlink.target_kn);
527 :
528 971 : kfree_const(kn->name);
529 :
530 971 : if (kn->iattr) {
531 27 : simple_xattrs_free(&kn->iattr->xattrs);
532 27 : kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
533 : }
534 971 : spin_lock(&kernfs_idr_lock);
535 971 : idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
536 971 : spin_unlock(&kernfs_idr_lock);
537 971 : kmem_cache_free(kernfs_node_cache, kn);
538 :
539 971 : kn = parent;
540 971 : if (kn) {
541 1942 : if (atomic_dec_and_test(&kn->count))
542 0 : goto repeat;
543 : } else {
544 : /* just released the root kn, free @root too */
545 0 : idr_destroy(&root->ino_idr);
546 0 : kfree(root);
547 : }
548 : }
549 : EXPORT_SYMBOL_GPL(kernfs_put);
550 :
551 20544 : static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
552 : {
553 20544 : struct kernfs_node *kn;
554 :
555 20544 : if (flags & LOOKUP_RCU)
556 : return -ECHILD;
557 :
558 : /* Always perform fresh lookup for negatives */
559 20544 : if (d_really_is_negative(dentry))
560 0 : goto out_bad_unlocked;
561 :
562 20544 : kn = kernfs_dentry_node(dentry);
563 20544 : mutex_lock(&kernfs_mutex);
564 :
565 : /* The kernfs node has been deactivated */
566 20544 : if (!kernfs_active(kn))
567 0 : goto out_bad;
568 :
569 : /* The kernfs node has been moved? */
570 41088 : if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
571 0 : goto out_bad;
572 :
573 : /* The kernfs node has been renamed */
574 20544 : if (strcmp(dentry->d_name.name, kn->name) != 0)
575 0 : goto out_bad;
576 :
577 : /* The kernfs node has been moved to a different namespace */
578 20544 : if (kn->parent && kernfs_ns_enabled(kn->parent) &&
579 40 : kernfs_info(dentry->d_sb)->ns != kn->ns)
580 0 : goto out_bad;
581 :
582 20544 : mutex_unlock(&kernfs_mutex);
583 20544 : return 1;
584 0 : out_bad:
585 0 : mutex_unlock(&kernfs_mutex);
586 : out_bad_unlocked:
587 : return 0;
588 : }
589 :
590 : const struct dentry_operations kernfs_dops = {
591 : .d_revalidate = kernfs_dop_revalidate,
592 : };
593 :
594 : /**
595 : * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
596 : * @dentry: the dentry in question
597 : *
598 : * Return the kernfs_node associated with @dentry. If @dentry is not a
599 : * kernfs one, %NULL is returned.
600 : *
601 : * While the returned kernfs_node will stay accessible as long as @dentry
602 : * is accessible, the returned node can be in any state and the caller is
603 : * fully responsible for determining what's accessible.
604 : */
605 0 : struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
606 : {
607 0 : if (dentry->d_sb->s_op == &kernfs_sops)
608 0 : return kernfs_dentry_node(dentry);
609 : return NULL;
610 : }
611 :
612 8512 : static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
613 : struct kernfs_node *parent,
614 : const char *name, umode_t mode,
615 : kuid_t uid, kgid_t gid,
616 : unsigned flags)
617 : {
618 8512 : struct kernfs_node *kn;
619 8512 : u32 id_highbits;
620 8512 : int ret;
621 :
622 8512 : name = kstrdup_const(name, GFP_KERNEL);
623 8512 : if (!name)
624 : return NULL;
625 :
626 8512 : kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
627 8512 : if (!kn)
628 0 : goto err_out1;
629 :
630 8512 : idr_preload(GFP_KERNEL);
631 8512 : spin_lock(&kernfs_idr_lock);
632 8512 : ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
633 8512 : if (ret >= 0 && ret < root->last_id_lowbits)
634 0 : root->id_highbits++;
635 8512 : id_highbits = root->id_highbits;
636 8512 : root->last_id_lowbits = ret;
637 8512 : spin_unlock(&kernfs_idr_lock);
638 8512 : idr_preload_end();
639 8512 : if (ret < 0)
640 0 : goto err_out2;
641 :
642 8512 : kn->id = (u64)id_highbits << 32 | ret;
643 :
644 8512 : atomic_set(&kn->count, 1);
645 8512 : atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
646 8512 : RB_CLEAR_NODE(&kn->rb);
647 :
648 8512 : kn->name = name;
649 8512 : kn->mode = mode;
650 8512 : kn->flags = flags;
651 :
652 8512 : if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) {
653 0 : struct iattr iattr = {
654 : .ia_valid = ATTR_UID | ATTR_GID,
655 : .ia_uid = uid,
656 : .ia_gid = gid,
657 : };
658 :
659 0 : ret = __kernfs_setattr(kn, &iattr);
660 0 : if (ret < 0)
661 0 : goto err_out3;
662 : }
663 :
664 8512 : if (parent) {
665 8509 : ret = security_kernfs_init_security(parent, kn);
666 8509 : if (ret)
667 0 : goto err_out3;
668 : }
669 :
670 : return kn;
671 :
672 0 : err_out3:
673 0 : idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
674 0 : err_out2:
675 0 : kmem_cache_free(kernfs_node_cache, kn);
676 0 : err_out1:
677 0 : kfree_const(name);
678 0 : return NULL;
679 : }
680 :
681 8509 : struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
682 : const char *name, umode_t mode,
683 : kuid_t uid, kgid_t gid,
684 : unsigned flags)
685 : {
686 8509 : struct kernfs_node *kn;
687 :
688 16989 : kn = __kernfs_new_node(kernfs_root(parent), parent,
689 : name, mode, uid, gid, flags);
690 8509 : if (kn) {
691 8509 : kernfs_get(parent);
692 8509 : kn->parent = parent;
693 : }
694 8509 : return kn;
695 : }
696 :
697 : /*
698 : * kernfs_find_and_get_node_by_id - get kernfs_node from node id
699 : * @root: the kernfs root
700 : * @id: the target node id
701 : *
702 : * @id's lower 32bits encode ino and upper gen. If the gen portion is
703 : * zero, all generations are matched.
704 : *
705 : * RETURNS:
706 : * NULL on failure. Return a kernfs node with reference counter incremented
707 : */
708 0 : struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
709 : u64 id)
710 : {
711 0 : struct kernfs_node *kn;
712 0 : ino_t ino = kernfs_id_ino(id);
713 0 : u32 gen = kernfs_id_gen(id);
714 :
715 0 : spin_lock(&kernfs_idr_lock);
716 :
717 0 : kn = idr_find(&root->ino_idr, (u32)ino);
718 0 : if (!kn)
719 0 : goto err_unlock;
720 :
721 0 : if (sizeof(ino_t) >= sizeof(u64)) {
722 : /* we looked up with the low 32bits, compare the whole */
723 0 : if (kernfs_ino(kn) != ino)
724 0 : goto err_unlock;
725 : } else {
726 : /* 0 matches all generations */
727 : if (unlikely(gen && kernfs_gen(kn) != gen))
728 : goto err_unlock;
729 : }
730 :
731 : /*
732 : * ACTIVATED is protected with kernfs_mutex but it was clear when
733 : * @kn was added to idr and we just wanna see it set. No need to
734 : * grab kernfs_mutex.
735 : */
736 0 : if (unlikely(!(kn->flags & KERNFS_ACTIVATED) ||
737 : !atomic_inc_not_zero(&kn->count)))
738 0 : goto err_unlock;
739 :
740 0 : spin_unlock(&kernfs_idr_lock);
741 0 : return kn;
742 0 : err_unlock:
743 0 : spin_unlock(&kernfs_idr_lock);
744 0 : return NULL;
745 : }
746 :
747 : /**
748 : * kernfs_add_one - add kernfs_node to parent without warning
749 : * @kn: kernfs_node to be added
750 : *
751 : * The caller must already have initialized @kn->parent. This
752 : * function increments nlink of the parent's inode if @kn is a
753 : * directory and link into the children list of the parent.
754 : *
755 : * RETURNS:
756 : * 0 on success, -EEXIST if entry with the given name already
757 : * exists.
758 : */
759 8509 : int kernfs_add_one(struct kernfs_node *kn)
760 : {
761 8509 : struct kernfs_node *parent = kn->parent;
762 8509 : struct kernfs_iattrs *ps_iattr;
763 8509 : bool has_ns;
764 8509 : int ret;
765 :
766 8509 : mutex_lock(&kernfs_mutex);
767 :
768 8509 : ret = -EINVAL;
769 8509 : has_ns = kernfs_ns_enabled(parent);
770 8509 : if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
771 : has_ns ? "required" : "invalid", parent->name, kn->name))
772 0 : goto out_unlock;
773 :
774 8509 : if (kernfs_type(parent) != KERNFS_DIR)
775 0 : goto out_unlock;
776 :
777 8509 : ret = -ENOENT;
778 8509 : if (parent->flags & KERNFS_EMPTY_DIR)
779 0 : goto out_unlock;
780 :
781 8509 : if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent))
782 0 : goto out_unlock;
783 :
784 8509 : kn->hash = kernfs_name_hash(kn->name, kn->ns);
785 :
786 8509 : ret = kernfs_link_sibling(kn);
787 8509 : if (ret)
788 0 : goto out_unlock;
789 :
790 : /* Update timestamps on the parent */
791 8509 : ps_iattr = parent->iattr;
792 8509 : if (ps_iattr) {
793 10 : ktime_get_real_ts64(&ps_iattr->ia_ctime);
794 10 : ps_iattr->ia_mtime = ps_iattr->ia_ctime;
795 : }
796 :
797 8509 : mutex_unlock(&kernfs_mutex);
798 :
799 : /*
800 : * Activate the new node unless CREATE_DEACTIVATED is requested.
801 : * If not activated here, the kernfs user is responsible for
802 : * activating the node with kernfs_activate(). A node which hasn't
803 : * been activated is not visible to userland and its removal won't
804 : * trigger deactivation.
805 : */
806 17018 : if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
807 7645 : kernfs_activate(kn);
808 : return 0;
809 :
810 0 : out_unlock:
811 0 : mutex_unlock(&kernfs_mutex);
812 0 : return ret;
813 : }
814 :
815 : /**
816 : * kernfs_find_ns - find kernfs_node with the given name
817 : * @parent: kernfs_node to search under
818 : * @name: name to look for
819 : * @ns: the namespace tag to use
820 : *
821 : * Look for kernfs_node with name @name under @parent. Returns pointer to
822 : * the found kernfs_node on success, %NULL on failure.
823 : */
824 3836 : static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
825 : const unsigned char *name,
826 : const void *ns)
827 : {
828 3836 : struct rb_node *node = parent->dir.children.rb_node;
829 3836 : bool has_ns = kernfs_ns_enabled(parent);
830 3836 : unsigned int hash;
831 :
832 11508 : lockdep_assert_held(&kernfs_mutex);
833 :
834 3836 : if (has_ns != (bool)ns) {
835 0 : WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
836 : has_ns ? "required" : "invalid", parent->name, name);
837 0 : return NULL;
838 : }
839 :
840 3836 : hash = kernfs_name_hash(name, ns);
841 12493 : while (node) {
842 10942 : struct kernfs_node *kn;
843 10942 : int result;
844 :
845 10942 : kn = rb_to_kn(node);
846 10942 : result = kernfs_name_compare(hash, name, ns, kn);
847 10942 : if (result < 0)
848 5082 : node = node->rb_left;
849 5860 : else if (result > 0)
850 3575 : node = node->rb_right;
851 : else
852 2285 : return kn;
853 : }
854 : return NULL;
855 : }
856 :
857 0 : static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
858 : const unsigned char *path,
859 : const void *ns)
860 : {
861 0 : size_t len;
862 0 : char *p, *name;
863 :
864 0 : lockdep_assert_held(&kernfs_mutex);
865 :
866 : /* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
867 0 : spin_lock_irq(&kernfs_rename_lock);
868 :
869 0 : len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
870 :
871 0 : if (len >= sizeof(kernfs_pr_cont_buf)) {
872 0 : spin_unlock_irq(&kernfs_rename_lock);
873 0 : return NULL;
874 : }
875 :
876 0 : p = kernfs_pr_cont_buf;
877 :
878 0 : while ((name = strsep(&p, "/")) && parent) {
879 0 : if (*name == '\0')
880 0 : continue;
881 0 : parent = kernfs_find_ns(parent, name, ns);
882 : }
883 :
884 0 : spin_unlock_irq(&kernfs_rename_lock);
885 :
886 0 : return parent;
887 : }
888 :
889 : /**
890 : * kernfs_find_and_get_ns - find and get kernfs_node with the given name
891 : * @parent: kernfs_node to search under
892 : * @name: name to look for
893 : * @ns: the namespace tag to use
894 : *
895 : * Look for kernfs_node with name @name under @parent and get a reference
896 : * if found. This function may sleep and returns pointer to the found
897 : * kernfs_node on success, %NULL on failure.
898 : */
899 98 : struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
900 : const char *name, const void *ns)
901 : {
902 98 : struct kernfs_node *kn;
903 :
904 98 : mutex_lock(&kernfs_mutex);
905 98 : kn = kernfs_find_ns(parent, name, ns);
906 98 : kernfs_get(kn);
907 98 : mutex_unlock(&kernfs_mutex);
908 :
909 98 : return kn;
910 : }
911 : EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
912 :
913 : /**
914 : * kernfs_walk_and_get_ns - find and get kernfs_node with the given path
915 : * @parent: kernfs_node to search under
916 : * @path: path to look for
917 : * @ns: the namespace tag to use
918 : *
919 : * Look for kernfs_node with path @path under @parent and get a reference
920 : * if found. This function may sleep and returns pointer to the found
921 : * kernfs_node on success, %NULL on failure.
922 : */
923 0 : struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
924 : const char *path, const void *ns)
925 : {
926 0 : struct kernfs_node *kn;
927 :
928 0 : mutex_lock(&kernfs_mutex);
929 0 : kn = kernfs_walk_ns(parent, path, ns);
930 0 : kernfs_get(kn);
931 0 : mutex_unlock(&kernfs_mutex);
932 :
933 0 : return kn;
934 : }
935 :
936 : /**
937 : * kernfs_create_root - create a new kernfs hierarchy
938 : * @scops: optional syscall operations for the hierarchy
939 : * @flags: KERNFS_ROOT_* flags
940 : * @priv: opaque data associated with the new directory
941 : *
942 : * Returns the root of the new hierarchy on success, ERR_PTR() value on
943 : * failure.
944 : */
945 3 : struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
946 : unsigned int flags, void *priv)
947 : {
948 3 : struct kernfs_root *root;
949 3 : struct kernfs_node *kn;
950 :
951 3 : root = kzalloc(sizeof(*root), GFP_KERNEL);
952 3 : if (!root)
953 3 : return ERR_PTR(-ENOMEM);
954 :
955 3 : idr_init(&root->ino_idr);
956 3 : INIT_LIST_HEAD(&root->supers);
957 :
958 : /*
959 : * On 64bit ino setups, id is ino. On 32bit, low 32bits are ino.
960 : * High bits generation. The starting value for both ino and
961 : * genenration is 1. Initialize upper 32bit allocation
962 : * accordingly.
963 : */
964 3 : if (sizeof(ino_t) >= sizeof(u64))
965 3 : root->id_highbits = 0;
966 : else
967 : root->id_highbits = 1;
968 :
969 6 : kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO,
970 3 : GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
971 : KERNFS_DIR);
972 3 : if (!kn) {
973 0 : idr_destroy(&root->ino_idr);
974 0 : kfree(root);
975 0 : return ERR_PTR(-ENOMEM);
976 : }
977 :
978 3 : kn->priv = priv;
979 3 : kn->dir.root = root;
980 :
981 3 : root->syscall_ops = scops;
982 3 : root->flags = flags;
983 3 : root->kn = kn;
984 3 : init_waitqueue_head(&root->deactivate_waitq);
985 :
986 3 : if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
987 1 : kernfs_activate(kn);
988 :
989 : return root;
990 : }
991 :
992 : /**
993 : * kernfs_destroy_root - destroy a kernfs hierarchy
994 : * @root: root of the hierarchy to destroy
995 : *
996 : * Destroy the hierarchy anchored at @root by removing all existing
997 : * directories and destroying @root.
998 : */
999 0 : void kernfs_destroy_root(struct kernfs_root *root)
1000 : {
1001 0 : kernfs_remove(root->kn); /* will also free @root */
1002 0 : }
1003 :
1004 : /**
1005 : * kernfs_create_dir_ns - create a directory
1006 : * @parent: parent in which to create a new directory
1007 : * @name: name of the new directory
1008 : * @mode: mode of the new directory
1009 : * @uid: uid of the new directory
1010 : * @gid: gid of the new directory
1011 : * @priv: opaque data associated with the new directory
1012 : * @ns: optional namespace tag of the directory
1013 : *
1014 : * Returns the created node on success, ERR_PTR() value on failure.
1015 : */
1016 778 : struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
1017 : const char *name, umode_t mode,
1018 : kuid_t uid, kgid_t gid,
1019 : void *priv, const void *ns)
1020 : {
1021 778 : struct kernfs_node *kn;
1022 778 : int rc;
1023 :
1024 : /* allocate */
1025 778 : kn = kernfs_new_node(parent, name, mode | S_IFDIR,
1026 : uid, gid, KERNFS_DIR);
1027 778 : if (!kn)
1028 778 : return ERR_PTR(-ENOMEM);
1029 :
1030 778 : kn->dir.root = parent->dir.root;
1031 778 : kn->ns = ns;
1032 778 : kn->priv = priv;
1033 :
1034 : /* link in */
1035 778 : rc = kernfs_add_one(kn);
1036 778 : if (!rc)
1037 : return kn;
1038 :
1039 0 : kernfs_put(kn);
1040 0 : return ERR_PTR(rc);
1041 : }
1042 :
1043 : /**
1044 : * kernfs_create_empty_dir - create an always empty directory
1045 : * @parent: parent in which to create a new directory
1046 : * @name: name of the new directory
1047 : *
1048 : * Returns the created node on success, ERR_PTR() value on failure.
1049 : */
1050 3 : struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
1051 : const char *name)
1052 : {
1053 3 : struct kernfs_node *kn;
1054 3 : int rc;
1055 :
1056 : /* allocate */
1057 6 : kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR,
1058 3 : GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR);
1059 3 : if (!kn)
1060 3 : return ERR_PTR(-ENOMEM);
1061 :
1062 3 : kn->flags |= KERNFS_EMPTY_DIR;
1063 3 : kn->dir.root = parent->dir.root;
1064 3 : kn->ns = NULL;
1065 3 : kn->priv = NULL;
1066 :
1067 : /* link in */
1068 3 : rc = kernfs_add_one(kn);
1069 3 : if (!rc)
1070 : return kn;
1071 :
1072 0 : kernfs_put(kn);
1073 0 : return ERR_PTR(rc);
1074 : }
1075 :
1076 2720 : static struct dentry *kernfs_iop_lookup(struct inode *dir,
1077 : struct dentry *dentry,
1078 : unsigned int flags)
1079 : {
1080 2720 : struct dentry *ret;
1081 2720 : struct kernfs_node *parent = dir->i_private;
1082 2720 : struct kernfs_node *kn;
1083 2720 : struct inode *inode;
1084 2720 : const void *ns = NULL;
1085 :
1086 2720 : mutex_lock(&kernfs_mutex);
1087 :
1088 2720 : if (kernfs_ns_enabled(parent))
1089 6 : ns = kernfs_info(dir->i_sb)->ns;
1090 :
1091 2720 : kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
1092 :
1093 : /* no such entry */
1094 2720 : if (!kn || !kernfs_active(kn)) {
1095 1365 : ret = NULL;
1096 1365 : goto out_unlock;
1097 : }
1098 :
1099 : /* attach dentry and inode */
1100 1355 : inode = kernfs_get_inode(dir->i_sb, kn);
1101 1355 : if (!inode) {
1102 0 : ret = ERR_PTR(-ENOMEM);
1103 0 : goto out_unlock;
1104 : }
1105 :
1106 : /* instantiate and hash dentry */
1107 1355 : ret = d_splice_alias(inode, dentry);
1108 2720 : out_unlock:
1109 2720 : mutex_unlock(&kernfs_mutex);
1110 2720 : return ret;
1111 : }
1112 :
1113 104 : static int kernfs_iop_mkdir(struct user_namespace *mnt_userns,
1114 : struct inode *dir, struct dentry *dentry,
1115 : umode_t mode)
1116 : {
1117 104 : struct kernfs_node *parent = dir->i_private;
1118 104 : struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
1119 104 : int ret;
1120 :
1121 104 : if (!scops || !scops->mkdir)
1122 : return -EPERM;
1123 :
1124 100 : if (!kernfs_get_active(parent))
1125 : return -ENODEV;
1126 :
1127 100 : ret = scops->mkdir(parent, dentry->d_name.name, mode);
1128 :
1129 100 : kernfs_put_active(parent);
1130 100 : return ret;
1131 : }
1132 :
1133 55 : static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
1134 : {
1135 55 : struct kernfs_node *kn = kernfs_dentry_node(dentry);
1136 55 : struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
1137 55 : int ret;
1138 :
1139 55 : if (!scops || !scops->rmdir)
1140 : return -EPERM;
1141 :
1142 55 : if (!kernfs_get_active(kn))
1143 : return -ENODEV;
1144 :
1145 55 : ret = scops->rmdir(kn);
1146 :
1147 55 : kernfs_put_active(kn);
1148 55 : return ret;
1149 : }
1150 :
1151 0 : static int kernfs_iop_rename(struct user_namespace *mnt_userns,
1152 : struct inode *old_dir, struct dentry *old_dentry,
1153 : struct inode *new_dir, struct dentry *new_dentry,
1154 : unsigned int flags)
1155 : {
1156 0 : struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
1157 0 : struct kernfs_node *new_parent = new_dir->i_private;
1158 0 : struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
1159 0 : int ret;
1160 :
1161 0 : if (flags)
1162 : return -EINVAL;
1163 :
1164 0 : if (!scops || !scops->rename)
1165 : return -EPERM;
1166 :
1167 0 : if (!kernfs_get_active(kn))
1168 : return -ENODEV;
1169 :
1170 0 : if (!kernfs_get_active(new_parent)) {
1171 0 : kernfs_put_active(kn);
1172 0 : return -ENODEV;
1173 : }
1174 :
1175 0 : ret = scops->rename(kn, new_parent, new_dentry->d_name.name);
1176 :
1177 0 : kernfs_put_active(new_parent);
1178 0 : kernfs_put_active(kn);
1179 0 : return ret;
1180 : }
1181 :
1182 : const struct inode_operations kernfs_dir_iops = {
1183 : .lookup = kernfs_iop_lookup,
1184 : .permission = kernfs_iop_permission,
1185 : .setattr = kernfs_iop_setattr,
1186 : .getattr = kernfs_iop_getattr,
1187 : .listxattr = kernfs_iop_listxattr,
1188 :
1189 : .mkdir = kernfs_iop_mkdir,
1190 : .rmdir = kernfs_iop_rmdir,
1191 : .rename = kernfs_iop_rename,
1192 : };
1193 :
1194 10352 : static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
1195 : {
1196 10454 : struct kernfs_node *last;
1197 :
1198 10556 : while (true) {
1199 10454 : struct rb_node *rbn;
1200 :
1201 10454 : last = pos;
1202 :
1203 10454 : if (kernfs_type(pos) != KERNFS_DIR)
1204 : break;
1205 :
1206 1062 : rbn = rb_first(&pos->dir.children);
1207 1062 : if (!rbn)
1208 : break;
1209 :
1210 102 : pos = rb_to_kn(rbn);
1211 : }
1212 :
1213 10352 : return last;
1214 : }
1215 :
1216 : /**
1217 : * kernfs_next_descendant_post - find the next descendant for post-order walk
1218 : * @pos: the current position (%NULL to initiate traversal)
1219 : * @root: kernfs_node whose descendants to walk
1220 : *
1221 : * Find the next descendant to visit for post-order traversal of @root's
1222 : * descendants. @root is included in the iteration and the last node to be
1223 : * visited.
1224 : */
1225 18202 : static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
1226 : struct kernfs_node *root)
1227 : {
1228 18202 : struct rb_node *rbn;
1229 :
1230 54606 : lockdep_assert_held(&kernfs_mutex);
1231 :
1232 : /* if first iteration, visit leftmost descendant which may be root */
1233 18202 : if (!pos)
1234 8719 : return kernfs_leftmost_descendant(root);
1235 :
1236 : /* if we visited @root, we're done */
1237 9483 : if (pos == root)
1238 : return NULL;
1239 :
1240 : /* if there's an unvisited sibling, visit its leftmost descendant */
1241 764 : rbn = rb_next(&pos->rb);
1242 764 : if (rbn)
1243 662 : return kernfs_leftmost_descendant(rb_to_kn(rbn));
1244 :
1245 : /* no sibling left, visit parent */
1246 102 : return pos->parent;
1247 : }
1248 :
1249 : /**
1250 : * kernfs_activate - activate a node which started deactivated
1251 : * @kn: kernfs_node whose subtree is to be activated
1252 : *
1253 : * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
1254 : * needs to be explicitly activated. A node which hasn't been activated
1255 : * isn't visible to userland and deactivation is skipped during its
1256 : * removal. This is useful to construct atomic init sequences where
1257 : * creation of multiple nodes should either succeed or fail atomically.
1258 : *
1259 : * The caller is responsible for ensuring that this function is not called
1260 : * after kernfs_remove*() is invoked on @kn.
1261 : */
1262 7748 : void kernfs_activate(struct kernfs_node *kn)
1263 : {
1264 7748 : struct kernfs_node *pos;
1265 :
1266 7748 : mutex_lock(&kernfs_mutex);
1267 :
1268 7748 : pos = NULL;
1269 16260 : while ((pos = kernfs_next_descendant_post(pos, kn))) {
1270 8512 : if (pos->flags & KERNFS_ACTIVATED)
1271 0 : continue;
1272 :
1273 17024 : WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb));
1274 8512 : WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS);
1275 :
1276 8512 : atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
1277 8512 : pos->flags |= KERNFS_ACTIVATED;
1278 : }
1279 :
1280 7748 : mutex_unlock(&kernfs_mutex);
1281 7748 : }
1282 :
1283 971 : static void __kernfs_remove(struct kernfs_node *kn)
1284 : {
1285 971 : struct kernfs_node *pos;
1286 :
1287 2913 : lockdep_assert_held(&kernfs_mutex);
1288 :
1289 : /*
1290 : * Short-circuit if non-root @kn has already finished removal.
1291 : * This is for kernfs_remove_self() which plays with active ref
1292 : * after removal.
1293 : */
1294 971 : if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb)))
1295 : return;
1296 :
1297 : pr_debug("kernfs %s: removing\n", kn->name);
1298 :
1299 : /* prevent any new usage under @kn by deactivating all nodes */
1300 : pos = NULL;
1301 1942 : while ((pos = kernfs_next_descendant_post(pos, kn)))
1302 971 : if (kernfs_active(pos))
1303 2913 : atomic_add(KN_DEACTIVATED_BIAS, &pos->active);
1304 :
1305 : /* deactivate and unlink the subtree node-by-node */
1306 971 : do {
1307 971 : pos = kernfs_leftmost_descendant(kn);
1308 :
1309 : /*
1310 : * kernfs_drain() drops kernfs_mutex temporarily and @pos's
1311 : * base ref could have been put by someone else by the time
1312 : * the function returns. Make sure it doesn't go away
1313 : * underneath us.
1314 : */
1315 971 : kernfs_get(pos);
1316 :
1317 : /*
1318 : * Drain iff @kn was activated. This avoids draining and
1319 : * its lockdep annotations for nodes which have never been
1320 : * activated and allows embedding kernfs_remove() in create
1321 : * error paths without worrying about draining.
1322 : */
1323 971 : if (kn->flags & KERNFS_ACTIVATED)
1324 971 : kernfs_drain(pos);
1325 : else
1326 0 : WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
1327 :
1328 : /*
1329 : * kernfs_unlink_sibling() succeeds once per node. Use it
1330 : * to decide who's responsible for cleanups.
1331 : */
1332 971 : if (!pos->parent || kernfs_unlink_sibling(pos)) {
1333 2913 : struct kernfs_iattrs *ps_iattr =
1334 971 : pos->parent ? pos->parent->iattr : NULL;
1335 :
1336 : /* update timestamps on the parent */
1337 971 : if (ps_iattr) {
1338 301 : ktime_get_real_ts64(&ps_iattr->ia_ctime);
1339 301 : ps_iattr->ia_mtime = ps_iattr->ia_ctime;
1340 : }
1341 :
1342 971 : kernfs_put(pos);
1343 : }
1344 :
1345 971 : kernfs_put(pos);
1346 971 : } while (pos != kn);
1347 : }
1348 :
1349 : /**
1350 : * kernfs_remove - remove a kernfs_node recursively
1351 : * @kn: the kernfs_node to remove
1352 : *
1353 : * Remove @kn along with all its subdirectories and files.
1354 : */
1355 139 : void kernfs_remove(struct kernfs_node *kn)
1356 : {
1357 139 : mutex_lock(&kernfs_mutex);
1358 139 : __kernfs_remove(kn);
1359 139 : mutex_unlock(&kernfs_mutex);
1360 139 : }
1361 :
1362 : /**
1363 : * kernfs_break_active_protection - break out of active protection
1364 : * @kn: the self kernfs_node
1365 : *
1366 : * The caller must be running off of a kernfs operation which is invoked
1367 : * with an active reference - e.g. one of kernfs_ops. Each invocation of
1368 : * this function must also be matched with an invocation of
1369 : * kernfs_unbreak_active_protection().
1370 : *
1371 : * This function releases the active reference of @kn the caller is
1372 : * holding. Once this function is called, @kn may be removed at any point
1373 : * and the caller is solely responsible for ensuring that the objects it
1374 : * dereferences are accessible.
1375 : */
1376 357 : void kernfs_break_active_protection(struct kernfs_node *kn)
1377 : {
1378 : /*
1379 : * Take out ourself out of the active ref dependency chain. If
1380 : * we're called without an active ref, lockdep will complain.
1381 : */
1382 357 : kernfs_put_active(kn);
1383 357 : }
1384 :
1385 : /**
1386 : * kernfs_unbreak_active_protection - undo kernfs_break_active_protection()
1387 : * @kn: the self kernfs_node
1388 : *
1389 : * If kernfs_break_active_protection() was called, this function must be
1390 : * invoked before finishing the kernfs operation. Note that while this
1391 : * function restores the active reference, it doesn't and can't actually
1392 : * restore the active protection - @kn may already or be in the process of
1393 : * being removed. Once kernfs_break_active_protection() is invoked, that
1394 : * protection is irreversibly gone for the kernfs operation instance.
1395 : *
1396 : * While this function may be called at any point after
1397 : * kernfs_break_active_protection() is invoked, its most useful location
1398 : * would be right before the enclosing kernfs operation returns.
1399 : */
1400 357 : void kernfs_unbreak_active_protection(struct kernfs_node *kn)
1401 : {
1402 : /*
1403 : * @kn->active could be in any state; however, the increment we do
1404 : * here will be undone as soon as the enclosing kernfs operation
1405 : * finishes and this temporary bump can't break anything. If @kn
1406 : * is alive, nothing changes. If @kn is being deactivated, the
1407 : * soon-to-follow put will either finish deactivation or restore
1408 : * deactivated state. If @kn is already removed, the temporary
1409 : * bump is guaranteed to be gone before @kn is released.
1410 : */
1411 357 : atomic_inc(&kn->active);
1412 357 : if (kernfs_lockdep(kn))
1413 202 : rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
1414 357 : }
1415 :
1416 : /**
1417 : * kernfs_remove_self - remove a kernfs_node from its own method
1418 : * @kn: the self kernfs_node to remove
1419 : *
1420 : * The caller must be running off of a kernfs operation which is invoked
1421 : * with an active reference - e.g. one of kernfs_ops. This can be used to
1422 : * implement a file operation which deletes itself.
1423 : *
1424 : * For example, the "delete" file for a sysfs device directory can be
1425 : * implemented by invoking kernfs_remove_self() on the "delete" file
1426 : * itself. This function breaks the circular dependency of trying to
1427 : * deactivate self while holding an active ref itself. It isn't necessary
1428 : * to modify the usual removal path to use kernfs_remove_self(). The
1429 : * "delete" implementation can simply invoke kernfs_remove_self() on self
1430 : * before proceeding with the usual removal path. kernfs will ignore later
1431 : * kernfs_remove() on self.
1432 : *
1433 : * kernfs_remove_self() can be called multiple times concurrently on the
1434 : * same kernfs_node. Only the first one actually performs removal and
1435 : * returns %true. All others will wait until the kernfs operation which
1436 : * won self-removal finishes and return %false. Note that the losers wait
1437 : * for the completion of not only the winning kernfs_remove_self() but also
1438 : * the whole kernfs_ops which won the arbitration. This can be used to
1439 : * guarantee, for example, all concurrent writes to a "delete" file to
1440 : * finish only after the whole operation is complete.
1441 : */
1442 0 : bool kernfs_remove_self(struct kernfs_node *kn)
1443 : {
1444 0 : bool ret;
1445 :
1446 0 : mutex_lock(&kernfs_mutex);
1447 0 : kernfs_break_active_protection(kn);
1448 :
1449 : /*
1450 : * SUICIDAL is used to arbitrate among competing invocations. Only
1451 : * the first one will actually perform removal. When the removal
1452 : * is complete, SUICIDED is set and the active ref is restored
1453 : * while holding kernfs_mutex. The ones which lost arbitration
1454 : * waits for SUICDED && drained which can happen only after the
1455 : * enclosing kernfs operation which executed the winning instance
1456 : * of kernfs_remove_self() finished.
1457 : */
1458 0 : if (!(kn->flags & KERNFS_SUICIDAL)) {
1459 0 : kn->flags |= KERNFS_SUICIDAL;
1460 0 : __kernfs_remove(kn);
1461 0 : kn->flags |= KERNFS_SUICIDED;
1462 0 : ret = true;
1463 : } else {
1464 0 : wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq;
1465 0 : DEFINE_WAIT(wait);
1466 :
1467 0 : while (true) {
1468 0 : prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE);
1469 :
1470 0 : if ((kn->flags & KERNFS_SUICIDED) &&
1471 0 : atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
1472 : break;
1473 :
1474 0 : mutex_unlock(&kernfs_mutex);
1475 0 : schedule();
1476 0 : mutex_lock(&kernfs_mutex);
1477 : }
1478 0 : finish_wait(waitq, &wait);
1479 0 : WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
1480 0 : ret = false;
1481 : }
1482 :
1483 : /*
1484 : * This must be done while holding kernfs_mutex; otherwise, waiting
1485 : * for SUICIDED && deactivated could finish prematurely.
1486 : */
1487 0 : kernfs_unbreak_active_protection(kn);
1488 :
1489 0 : mutex_unlock(&kernfs_mutex);
1490 0 : return ret;
1491 : }
1492 :
1493 : /**
1494 : * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
1495 : * @parent: parent of the target
1496 : * @name: name of the kernfs_node to remove
1497 : * @ns: namespace tag of the kernfs_node to remove
1498 : *
1499 : * Look for the kernfs_node with @name and @ns under @parent and remove it.
1500 : * Returns 0 on success, -ENOENT if such entry doesn't exist.
1501 : */
1502 1018 : int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
1503 : const void *ns)
1504 : {
1505 1018 : struct kernfs_node *kn;
1506 :
1507 1018 : if (!parent) {
1508 0 : WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
1509 : name);
1510 0 : return -ENOENT;
1511 : }
1512 :
1513 1018 : mutex_lock(&kernfs_mutex);
1514 :
1515 1018 : kn = kernfs_find_ns(parent, name, ns);
1516 1018 : if (kn)
1517 832 : __kernfs_remove(kn);
1518 :
1519 1018 : mutex_unlock(&kernfs_mutex);
1520 :
1521 1018 : if (kn)
1522 : return 0;
1523 : else
1524 186 : return -ENOENT;
1525 : }
1526 :
1527 : /**
1528 : * kernfs_rename_ns - move and rename a kernfs_node
1529 : * @kn: target node
1530 : * @new_parent: new parent to put @sd under
1531 : * @new_name: new name
1532 : * @new_ns: new namespace tag
1533 : */
1534 0 : int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
1535 : const char *new_name, const void *new_ns)
1536 : {
1537 0 : struct kernfs_node *old_parent;
1538 0 : const char *old_name = NULL;
1539 0 : int error;
1540 :
1541 : /* can't move or rename root */
1542 0 : if (!kn->parent)
1543 : return -EINVAL;
1544 :
1545 0 : mutex_lock(&kernfs_mutex);
1546 :
1547 0 : error = -ENOENT;
1548 0 : if (!kernfs_active(kn) || !kernfs_active(new_parent) ||
1549 0 : (new_parent->flags & KERNFS_EMPTY_DIR))
1550 0 : goto out;
1551 :
1552 0 : error = 0;
1553 0 : if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
1554 0 : (strcmp(kn->name, new_name) == 0))
1555 0 : goto out; /* nothing to rename */
1556 :
1557 0 : error = -EEXIST;
1558 0 : if (kernfs_find_ns(new_parent, new_name, new_ns))
1559 0 : goto out;
1560 :
1561 : /* rename kernfs_node */
1562 0 : if (strcmp(kn->name, new_name) != 0) {
1563 0 : error = -ENOMEM;
1564 0 : new_name = kstrdup_const(new_name, GFP_KERNEL);
1565 0 : if (!new_name)
1566 0 : goto out;
1567 : } else {
1568 : new_name = NULL;
1569 : }
1570 :
1571 : /*
1572 : * Move to the appropriate place in the appropriate directories rbtree.
1573 : */
1574 0 : kernfs_unlink_sibling(kn);
1575 0 : kernfs_get(new_parent);
1576 :
1577 : /* rename_lock protects ->parent and ->name accessors */
1578 0 : spin_lock_irq(&kernfs_rename_lock);
1579 :
1580 0 : old_parent = kn->parent;
1581 0 : kn->parent = new_parent;
1582 :
1583 0 : kn->ns = new_ns;
1584 0 : if (new_name) {
1585 0 : old_name = kn->name;
1586 0 : kn->name = new_name;
1587 : }
1588 :
1589 0 : spin_unlock_irq(&kernfs_rename_lock);
1590 :
1591 0 : kn->hash = kernfs_name_hash(kn->name, kn->ns);
1592 0 : kernfs_link_sibling(kn);
1593 :
1594 0 : kernfs_put(old_parent);
1595 0 : kfree_const(old_name);
1596 :
1597 0 : error = 0;
1598 0 : out:
1599 0 : mutex_unlock(&kernfs_mutex);
1600 0 : return error;
1601 : }
1602 :
1603 : /* Relationship between mode and the DT_xxx types */
1604 934 : static inline unsigned char dt_type(struct kernfs_node *kn)
1605 : {
1606 934 : return (kn->mode >> 12) & 15;
1607 : }
1608 :
1609 289 : static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
1610 : {
1611 289 : kernfs_put(filp->private_data);
1612 289 : return 0;
1613 : }
1614 :
1615 1178 : static struct kernfs_node *kernfs_dir_pos(const void *ns,
1616 : struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
1617 : {
1618 1178 : if (pos) {
1619 934 : int valid = kernfs_active(pos) &&
1620 934 : pos->parent == parent && hash == pos->hash;
1621 934 : kernfs_put(pos);
1622 934 : if (!valid)
1623 0 : pos = NULL;
1624 : }
1625 1178 : if (!pos && (hash > 1) && (hash < INT_MAX)) {
1626 122 : struct rb_node *node = parent->dir.children.rb_node;
1627 400 : while (node) {
1628 278 : pos = rb_to_kn(node);
1629 :
1630 278 : if (hash < pos->hash)
1631 278 : node = node->rb_left;
1632 0 : else if (hash > pos->hash)
1633 0 : node = node->rb_right;
1634 : else
1635 : break;
1636 : }
1637 : }
1638 : /* Skip over entries which are dying/dead or in the wrong namespace */
1639 1178 : while (pos && (!kernfs_active(pos) || pos->ns != ns)) {
1640 0 : struct rb_node *node = rb_next(&pos->rb);
1641 0 : if (!node)
1642 : pos = NULL;
1643 : else
1644 0 : pos = rb_to_kn(node);
1645 : }
1646 1178 : return pos;
1647 : }
1648 :
1649 934 : static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
1650 : struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos)
1651 : {
1652 934 : pos = kernfs_dir_pos(ns, parent, ino, pos);
1653 934 : if (pos) {
1654 934 : do {
1655 934 : struct rb_node *node = rb_next(&pos->rb);
1656 934 : if (!node)
1657 : pos = NULL;
1658 : else
1659 829 : pos = rb_to_kn(node);
1660 829 : } while (pos && (!kernfs_active(pos) || pos->ns != ns));
1661 : }
1662 934 : return pos;
1663 : }
1664 :
1665 244 : static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
1666 : {
1667 244 : struct dentry *dentry = file->f_path.dentry;
1668 244 : struct kernfs_node *parent = kernfs_dentry_node(dentry);
1669 244 : struct kernfs_node *pos = file->private_data;
1670 244 : const void *ns = NULL;
1671 :
1672 244 : if (!dir_emit_dots(file, ctx))
1673 : return 0;
1674 244 : mutex_lock(&kernfs_mutex);
1675 :
1676 244 : if (kernfs_ns_enabled(parent))
1677 2 : ns = kernfs_info(dentry->d_sb)->ns;
1678 :
1679 244 : for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
1680 1178 : pos;
1681 934 : pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
1682 934 : const char *name = pos->name;
1683 934 : unsigned int type = dt_type(pos);
1684 934 : int len = strlen(name);
1685 934 : ino_t ino = kernfs_ino(pos);
1686 :
1687 934 : ctx->pos = pos->hash;
1688 934 : file->private_data = pos;
1689 934 : kernfs_get(pos);
1690 :
1691 934 : mutex_unlock(&kernfs_mutex);
1692 934 : if (!dir_emit(ctx, name, len, ino, type))
1693 : return 0;
1694 934 : mutex_lock(&kernfs_mutex);
1695 : }
1696 244 : mutex_unlock(&kernfs_mutex);
1697 244 : file->private_data = NULL;
1698 244 : ctx->pos = INT_MAX;
1699 244 : return 0;
1700 : }
1701 :
1702 : const struct file_operations kernfs_dir_fops = {
1703 : .read = generic_read_dir,
1704 : .iterate_shared = kernfs_fop_readdir,
1705 : .release = kernfs_dir_fop_release,
1706 : .llseek = generic_file_llseek,
1707 : };
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