xref: /linux/fs/proc/generic.c (revision 8a79db5e83a5d52c74e6f3c40d6f312cf899213e) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * proc/fs/generic.c --- generic routines for the proc-fs
4  *
5  * This file contains generic proc-fs routines for handling
6  * directories and files.
7  *
8  * Copyright (C) 1991, 1992 Linus Torvalds.
9  * Copyright (C) 1997 Theodore Ts'o
10  */
11 
12 #include <linux/cache.h>
13 #include <linux/errno.h>
14 #include <linux/time.h>
15 #include <linux/proc_fs.h>
16 #include <linux/stat.h>
17 #include <linux/mm.h>
18 #include <linux/module.h>
19 #include <linux/namei.h>
20 #include <linux/slab.h>
21 #include <linux/printk.h>
22 #include <linux/mount.h>
23 #include <linux/init.h>
24 #include <linux/idr.h>
25 #include <linux/bitops.h>
26 #include <linux/spinlock.h>
27 #include <linux/completion.h>
28 #include <linux/uaccess.h>
29 #include <linux/seq_file.h>
30 
31 #include "internal.h"
32 
33 static DEFINE_RWLOCK(proc_subdir_lock);
34 
35 struct kmem_cache *proc_dir_entry_cache __ro_after_init;
36 
37 void pde_free(struct proc_dir_entry *pde)
38 {
39 	if (S_ISLNK(pde->mode))
40 		kfree(pde->data);
41 	if (pde->name != pde->inline_name)
42 		kfree(pde->name);
43 	kmem_cache_free(proc_dir_entry_cache, pde);
44 }
45 
46 static int proc_match(const char *name, struct proc_dir_entry *de, unsigned int len)
47 {
48 	if (len < de->namelen)
49 		return -1;
50 	if (len > de->namelen)
51 		return 1;
52 
53 	return memcmp(name, de->name, len);
54 }
55 
56 static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir)
57 {
58 	return rb_entry_safe(rb_first(&dir->subdir), struct proc_dir_entry,
59 			     subdir_node);
60 }
61 
62 static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir)
63 {
64 	return rb_entry_safe(rb_next(&dir->subdir_node), struct proc_dir_entry,
65 			     subdir_node);
66 }
67 
68 static struct proc_dir_entry *pde_subdir_find(struct proc_dir_entry *dir,
69 					      const char *name,
70 					      unsigned int len)
71 {
72 	struct rb_node *node = dir->subdir.rb_node;
73 
74 	while (node) {
75 		struct proc_dir_entry *de = rb_entry(node,
76 						     struct proc_dir_entry,
77 						     subdir_node);
78 		int result = proc_match(name, de, len);
79 
80 		if (result < 0)
81 			node = node->rb_left;
82 		else if (result > 0)
83 			node = node->rb_right;
84 		else
85 			return de;
86 	}
87 	return NULL;
88 }
89 
90 static bool pde_subdir_insert(struct proc_dir_entry *dir,
91 			      struct proc_dir_entry *de)
92 {
93 	struct rb_root *root = &dir->subdir;
94 	struct rb_node **new = &root->rb_node, *parent = NULL;
95 
96 	/* Figure out where to put new node */
97 	while (*new) {
98 		struct proc_dir_entry *this = rb_entry(*new,
99 						       struct proc_dir_entry,
100 						       subdir_node);
101 		int result = proc_match(de->name, this, de->namelen);
102 
103 		parent = *new;
104 		if (result < 0)
105 			new = &(*new)->rb_left;
106 		else if (result > 0)
107 			new = &(*new)->rb_right;
108 		else
109 			return false;
110 	}
111 
112 	/* Add new node and rebalance tree. */
113 	rb_link_node(&de->subdir_node, parent, new);
114 	rb_insert_color(&de->subdir_node, root);
115 	return true;
116 }
117 
118 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
119 {
120 	struct inode *inode = d_inode(dentry);
121 	struct proc_dir_entry *de = PDE(inode);
122 	int error;
123 
124 	error = setattr_prepare(dentry, iattr);
125 	if (error)
126 		return error;
127 
128 	setattr_copy(inode, iattr);
129 	mark_inode_dirty(inode);
130 
131 	proc_set_user(de, inode->i_uid, inode->i_gid);
132 	de->mode = inode->i_mode;
133 	return 0;
134 }
135 
136 static int proc_getattr(const struct path *path, struct kstat *stat,
137 			u32 request_mask, unsigned int query_flags)
138 {
139 	struct inode *inode = d_inode(path->dentry);
140 	struct proc_dir_entry *de = PDE(inode);
141 	if (de) {
142 		nlink_t nlink = READ_ONCE(de->nlink);
143 		if (nlink > 0) {
144 			set_nlink(inode, nlink);
145 		}
146 	}
147 
148 	generic_fillattr(inode, stat);
149 	return 0;
150 }
151 
152 static const struct inode_operations proc_file_inode_operations = {
153 	.setattr	= proc_notify_change,
154 };
155 
156 /*
157  * This function parses a name such as "tty/driver/serial", and
158  * returns the struct proc_dir_entry for "/proc/tty/driver", and
159  * returns "serial" in residual.
160  */
161 static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
162 			     const char **residual)
163 {
164 	const char     		*cp = name, *next;
165 	struct proc_dir_entry	*de;
166 
167 	de = *ret;
168 	if (!de)
169 		de = &proc_root;
170 
171 	while (1) {
172 		next = strchr(cp, '/');
173 		if (!next)
174 			break;
175 
176 		de = pde_subdir_find(de, cp, next - cp);
177 		if (!de) {
178 			WARN(1, "name '%s'\n", name);
179 			return -ENOENT;
180 		}
181 		cp = next + 1;
182 	}
183 	*residual = cp;
184 	*ret = de;
185 	return 0;
186 }
187 
188 static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
189 			   const char **residual)
190 {
191 	int rv;
192 
193 	read_lock(&proc_subdir_lock);
194 	rv = __xlate_proc_name(name, ret, residual);
195 	read_unlock(&proc_subdir_lock);
196 	return rv;
197 }
198 
199 static DEFINE_IDA(proc_inum_ida);
200 
201 #define PROC_DYNAMIC_FIRST 0xF0000000U
202 
203 /*
204  * Return an inode number between PROC_DYNAMIC_FIRST and
205  * 0xffffffff, or zero on failure.
206  */
207 int proc_alloc_inum(unsigned int *inum)
208 {
209 	int i;
210 
211 	i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
212 			   GFP_KERNEL);
213 	if (i < 0)
214 		return i;
215 
216 	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
217 	return 0;
218 }
219 
220 void proc_free_inum(unsigned int inum)
221 {
222 	ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
223 }
224 
225 static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
226 {
227 	if (flags & LOOKUP_RCU)
228 		return -ECHILD;
229 
230 	if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
231 		return 0; /* revalidate */
232 	return 1;
233 }
234 
235 static int proc_misc_d_delete(const struct dentry *dentry)
236 {
237 	return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
238 }
239 
240 static const struct dentry_operations proc_misc_dentry_ops = {
241 	.d_revalidate	= proc_misc_d_revalidate,
242 	.d_delete	= proc_misc_d_delete,
243 };
244 
245 /*
246  * Don't create negative dentries here, return -ENOENT by hand
247  * instead.
248  */
249 struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
250 			      struct proc_dir_entry *de)
251 {
252 	struct inode *inode;
253 
254 	read_lock(&proc_subdir_lock);
255 	de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
256 	if (de) {
257 		pde_get(de);
258 		read_unlock(&proc_subdir_lock);
259 		inode = proc_get_inode(dir->i_sb, de);
260 		if (!inode)
261 			return ERR_PTR(-ENOMEM);
262 		d_set_d_op(dentry, de->proc_dops);
263 		return d_splice_alias(inode, dentry);
264 	}
265 	read_unlock(&proc_subdir_lock);
266 	return ERR_PTR(-ENOENT);
267 }
268 
269 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
270 		unsigned int flags)
271 {
272 	return proc_lookup_de(dir, dentry, PDE(dir));
273 }
274 
275 /*
276  * This returns non-zero if at EOF, so that the /proc
277  * root directory can use this and check if it should
278  * continue with the <pid> entries..
279  *
280  * Note that the VFS-layer doesn't care about the return
281  * value of the readdir() call, as long as it's non-negative
282  * for success..
283  */
284 int proc_readdir_de(struct file *file, struct dir_context *ctx,
285 		    struct proc_dir_entry *de)
286 {
287 	int i;
288 
289 	if (!dir_emit_dots(file, ctx))
290 		return 0;
291 
292 	i = ctx->pos - 2;
293 	read_lock(&proc_subdir_lock);
294 	de = pde_subdir_first(de);
295 	for (;;) {
296 		if (!de) {
297 			read_unlock(&proc_subdir_lock);
298 			return 0;
299 		}
300 		if (!i)
301 			break;
302 		de = pde_subdir_next(de);
303 		i--;
304 	}
305 
306 	do {
307 		struct proc_dir_entry *next;
308 		pde_get(de);
309 		read_unlock(&proc_subdir_lock);
310 		if (!dir_emit(ctx, de->name, de->namelen,
311 			    de->low_ino, de->mode >> 12)) {
312 			pde_put(de);
313 			return 0;
314 		}
315 		ctx->pos++;
316 		read_lock(&proc_subdir_lock);
317 		next = pde_subdir_next(de);
318 		pde_put(de);
319 		de = next;
320 	} while (de);
321 	read_unlock(&proc_subdir_lock);
322 	return 1;
323 }
324 
325 int proc_readdir(struct file *file, struct dir_context *ctx)
326 {
327 	struct inode *inode = file_inode(file);
328 
329 	return proc_readdir_de(file, ctx, PDE(inode));
330 }
331 
332 /*
333  * These are the generic /proc directory operations. They
334  * use the in-memory "struct proc_dir_entry" tree to parse
335  * the /proc directory.
336  */
337 static const struct file_operations proc_dir_operations = {
338 	.llseek			= generic_file_llseek,
339 	.read			= generic_read_dir,
340 	.iterate_shared		= proc_readdir,
341 };
342 
343 /*
344  * proc directories can do almost nothing..
345  */
346 static const struct inode_operations proc_dir_inode_operations = {
347 	.lookup		= proc_lookup,
348 	.getattr	= proc_getattr,
349 	.setattr	= proc_notify_change,
350 };
351 
352 /* returns the registered entry, or frees dp and returns NULL on failure */
353 struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
354 		struct proc_dir_entry *dp)
355 {
356 	if (proc_alloc_inum(&dp->low_ino))
357 		goto out_free_entry;
358 
359 	write_lock(&proc_subdir_lock);
360 	dp->parent = dir;
361 	if (pde_subdir_insert(dir, dp) == false) {
362 		WARN(1, "proc_dir_entry '%s/%s' already registered\n",
363 		     dir->name, dp->name);
364 		write_unlock(&proc_subdir_lock);
365 		goto out_free_inum;
366 	}
367 	dir->nlink++;
368 	write_unlock(&proc_subdir_lock);
369 
370 	return dp;
371 out_free_inum:
372 	proc_free_inum(dp->low_ino);
373 out_free_entry:
374 	pde_free(dp);
375 	return NULL;
376 }
377 
378 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
379 					  const char *name,
380 					  umode_t mode,
381 					  nlink_t nlink)
382 {
383 	struct proc_dir_entry *ent = NULL;
384 	const char *fn;
385 	struct qstr qstr;
386 
387 	if (xlate_proc_name(name, parent, &fn) != 0)
388 		goto out;
389 	qstr.name = fn;
390 	qstr.len = strlen(fn);
391 	if (qstr.len == 0 || qstr.len >= 256) {
392 		WARN(1, "name len %u\n", qstr.len);
393 		return NULL;
394 	}
395 	if (qstr.len == 1 && fn[0] == '.') {
396 		WARN(1, "name '.'\n");
397 		return NULL;
398 	}
399 	if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
400 		WARN(1, "name '..'\n");
401 		return NULL;
402 	}
403 	if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
404 		WARN(1, "create '/proc/%s' by hand\n", qstr.name);
405 		return NULL;
406 	}
407 	if (is_empty_pde(*parent)) {
408 		WARN(1, "attempt to add to permanently empty directory");
409 		return NULL;
410 	}
411 
412 	ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
413 	if (!ent)
414 		goto out;
415 
416 	if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
417 		ent->name = ent->inline_name;
418 	} else {
419 		ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
420 		if (!ent->name) {
421 			pde_free(ent);
422 			return NULL;
423 		}
424 	}
425 
426 	memcpy(ent->name, fn, qstr.len + 1);
427 	ent->namelen = qstr.len;
428 	ent->mode = mode;
429 	ent->nlink = nlink;
430 	ent->subdir = RB_ROOT;
431 	refcount_set(&ent->refcnt, 1);
432 	spin_lock_init(&ent->pde_unload_lock);
433 	INIT_LIST_HEAD(&ent->pde_openers);
434 	proc_set_user(ent, (*parent)->uid, (*parent)->gid);
435 
436 	ent->proc_dops = &proc_misc_dentry_ops;
437 
438 out:
439 	return ent;
440 }
441 
442 struct proc_dir_entry *proc_symlink(const char *name,
443 		struct proc_dir_entry *parent, const char *dest)
444 {
445 	struct proc_dir_entry *ent;
446 
447 	ent = __proc_create(&parent, name,
448 			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
449 
450 	if (ent) {
451 		ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
452 		if (ent->data) {
453 			strcpy((char*)ent->data,dest);
454 			ent->proc_iops = &proc_link_inode_operations;
455 			ent = proc_register(parent, ent);
456 		} else {
457 			pde_free(ent);
458 			ent = NULL;
459 		}
460 	}
461 	return ent;
462 }
463 EXPORT_SYMBOL(proc_symlink);
464 
465 struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
466 		struct proc_dir_entry *parent, void *data)
467 {
468 	struct proc_dir_entry *ent;
469 
470 	if (mode == 0)
471 		mode = S_IRUGO | S_IXUGO;
472 
473 	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
474 	if (ent) {
475 		ent->data = data;
476 		ent->proc_fops = &proc_dir_operations;
477 		ent->proc_iops = &proc_dir_inode_operations;
478 		ent = proc_register(parent, ent);
479 	}
480 	return ent;
481 }
482 EXPORT_SYMBOL_GPL(proc_mkdir_data);
483 
484 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
485 				       struct proc_dir_entry *parent)
486 {
487 	return proc_mkdir_data(name, mode, parent, NULL);
488 }
489 EXPORT_SYMBOL(proc_mkdir_mode);
490 
491 struct proc_dir_entry *proc_mkdir(const char *name,
492 		struct proc_dir_entry *parent)
493 {
494 	return proc_mkdir_data(name, 0, parent, NULL);
495 }
496 EXPORT_SYMBOL(proc_mkdir);
497 
498 struct proc_dir_entry *proc_create_mount_point(const char *name)
499 {
500 	umode_t mode = S_IFDIR | S_IRUGO | S_IXUGO;
501 	struct proc_dir_entry *ent, *parent = NULL;
502 
503 	ent = __proc_create(&parent, name, mode, 2);
504 	if (ent) {
505 		ent->data = NULL;
506 		ent->proc_fops = NULL;
507 		ent->proc_iops = NULL;
508 		ent = proc_register(parent, ent);
509 	}
510 	return ent;
511 }
512 EXPORT_SYMBOL(proc_create_mount_point);
513 
514 struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
515 		struct proc_dir_entry **parent, void *data)
516 {
517 	struct proc_dir_entry *p;
518 
519 	if ((mode & S_IFMT) == 0)
520 		mode |= S_IFREG;
521 	if ((mode & S_IALLUGO) == 0)
522 		mode |= S_IRUGO;
523 	if (WARN_ON_ONCE(!S_ISREG(mode)))
524 		return NULL;
525 
526 	p = __proc_create(parent, name, mode, 1);
527 	if (p) {
528 		p->proc_iops = &proc_file_inode_operations;
529 		p->data = data;
530 	}
531 	return p;
532 }
533 
534 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
535 		struct proc_dir_entry *parent,
536 		const struct file_operations *proc_fops, void *data)
537 {
538 	struct proc_dir_entry *p;
539 
540 	BUG_ON(proc_fops == NULL);
541 
542 	p = proc_create_reg(name, mode, &parent, data);
543 	if (!p)
544 		return NULL;
545 	p->proc_fops = proc_fops;
546 	return proc_register(parent, p);
547 }
548 EXPORT_SYMBOL(proc_create_data);
549 
550 struct proc_dir_entry *proc_create(const char *name, umode_t mode,
551 				   struct proc_dir_entry *parent,
552 				   const struct file_operations *proc_fops)
553 {
554 	return proc_create_data(name, mode, parent, proc_fops, NULL);
555 }
556 EXPORT_SYMBOL(proc_create);
557 
558 static int proc_seq_open(struct inode *inode, struct file *file)
559 {
560 	struct proc_dir_entry *de = PDE(inode);
561 
562 	if (de->state_size)
563 		return seq_open_private(file, de->seq_ops, de->state_size);
564 	return seq_open(file, de->seq_ops);
565 }
566 
567 static int proc_seq_release(struct inode *inode, struct file *file)
568 {
569 	struct proc_dir_entry *de = PDE(inode);
570 
571 	if (de->state_size)
572 		return seq_release_private(inode, file);
573 	return seq_release(inode, file);
574 }
575 
576 static const struct file_operations proc_seq_fops = {
577 	.open		= proc_seq_open,
578 	.read		= seq_read,
579 	.llseek		= seq_lseek,
580 	.release	= proc_seq_release,
581 };
582 
583 struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
584 		struct proc_dir_entry *parent, const struct seq_operations *ops,
585 		unsigned int state_size, void *data)
586 {
587 	struct proc_dir_entry *p;
588 
589 	p = proc_create_reg(name, mode, &parent, data);
590 	if (!p)
591 		return NULL;
592 	p->proc_fops = &proc_seq_fops;
593 	p->seq_ops = ops;
594 	p->state_size = state_size;
595 	return proc_register(parent, p);
596 }
597 EXPORT_SYMBOL(proc_create_seq_private);
598 
599 static int proc_single_open(struct inode *inode, struct file *file)
600 {
601 	struct proc_dir_entry *de = PDE(inode);
602 
603 	return single_open(file, de->single_show, de->data);
604 }
605 
606 static const struct file_operations proc_single_fops = {
607 	.open		= proc_single_open,
608 	.read		= seq_read,
609 	.llseek		= seq_lseek,
610 	.release	= single_release,
611 };
612 
613 struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
614 		struct proc_dir_entry *parent,
615 		int (*show)(struct seq_file *, void *), void *data)
616 {
617 	struct proc_dir_entry *p;
618 
619 	p = proc_create_reg(name, mode, &parent, data);
620 	if (!p)
621 		return NULL;
622 	p->proc_fops = &proc_single_fops;
623 	p->single_show = show;
624 	return proc_register(parent, p);
625 }
626 EXPORT_SYMBOL(proc_create_single_data);
627 
628 void proc_set_size(struct proc_dir_entry *de, loff_t size)
629 {
630 	de->size = size;
631 }
632 EXPORT_SYMBOL(proc_set_size);
633 
634 void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
635 {
636 	de->uid = uid;
637 	de->gid = gid;
638 }
639 EXPORT_SYMBOL(proc_set_user);
640 
641 void pde_put(struct proc_dir_entry *pde)
642 {
643 	if (refcount_dec_and_test(&pde->refcnt)) {
644 		proc_free_inum(pde->low_ino);
645 		pde_free(pde);
646 	}
647 }
648 
649 /*
650  * Remove a /proc entry and free it if it's not currently in use.
651  */
652 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
653 {
654 	struct proc_dir_entry *de = NULL;
655 	const char *fn = name;
656 	unsigned int len;
657 
658 	write_lock(&proc_subdir_lock);
659 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
660 		write_unlock(&proc_subdir_lock);
661 		return;
662 	}
663 	len = strlen(fn);
664 
665 	de = pde_subdir_find(parent, fn, len);
666 	if (de) {
667 		rb_erase(&de->subdir_node, &parent->subdir);
668 		if (S_ISDIR(de->mode)) {
669 			parent->nlink--;
670 		}
671 	}
672 	write_unlock(&proc_subdir_lock);
673 	if (!de) {
674 		WARN(1, "name '%s'\n", name);
675 		return;
676 	}
677 
678 	proc_entry_rundown(de);
679 
680 	WARN(pde_subdir_first(de),
681 	     "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
682 	     __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
683 	pde_put(de);
684 }
685 EXPORT_SYMBOL(remove_proc_entry);
686 
687 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
688 {
689 	struct proc_dir_entry *root = NULL, *de, *next;
690 	const char *fn = name;
691 	unsigned int len;
692 
693 	write_lock(&proc_subdir_lock);
694 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
695 		write_unlock(&proc_subdir_lock);
696 		return -ENOENT;
697 	}
698 	len = strlen(fn);
699 
700 	root = pde_subdir_find(parent, fn, len);
701 	if (!root) {
702 		write_unlock(&proc_subdir_lock);
703 		return -ENOENT;
704 	}
705 	rb_erase(&root->subdir_node, &parent->subdir);
706 
707 	de = root;
708 	while (1) {
709 		next = pde_subdir_first(de);
710 		if (next) {
711 			rb_erase(&next->subdir_node, &de->subdir);
712 			de = next;
713 			continue;
714 		}
715 		next = de->parent;
716 		if (S_ISDIR(de->mode))
717 			next->nlink--;
718 		write_unlock(&proc_subdir_lock);
719 
720 		proc_entry_rundown(de);
721 		if (de == root)
722 			break;
723 		pde_put(de);
724 
725 		write_lock(&proc_subdir_lock);
726 		de = next;
727 	}
728 	pde_put(root);
729 	return 0;
730 }
731 EXPORT_SYMBOL(remove_proc_subtree);
732 
733 void *proc_get_parent_data(const struct inode *inode)
734 {
735 	struct proc_dir_entry *de = PDE(inode);
736 	return de->parent->data;
737 }
738 EXPORT_SYMBOL_GPL(proc_get_parent_data);
739 
740 void proc_remove(struct proc_dir_entry *de)
741 {
742 	if (de)
743 		remove_proc_subtree(de->name, de->parent);
744 }
745 EXPORT_SYMBOL(proc_remove);
746 
747 void *PDE_DATA(const struct inode *inode)
748 {
749 	return __PDE_DATA(inode);
750 }
751 EXPORT_SYMBOL(PDE_DATA);
752 
753 /*
754  * Pull a user buffer into memory and pass it to the file's write handler if
755  * one is supplied.  The ->write() method is permitted to modify the
756  * kernel-side buffer.
757  */
758 ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
759 			  loff_t *_pos)
760 {
761 	struct proc_dir_entry *pde = PDE(file_inode(f));
762 	char *buf;
763 	int ret;
764 
765 	if (!pde->write)
766 		return -EACCES;
767 	if (size == 0 || size > PAGE_SIZE - 1)
768 		return -EINVAL;
769 	buf = memdup_user_nul(ubuf, size);
770 	if (IS_ERR(buf))
771 		return PTR_ERR(buf);
772 	ret = pde->write(f, buf, size);
773 	kfree(buf);
774 	return ret == 0 ? size : ret;
775 }
776