xref: /linux/fs/proc/generic.c (revision 06a130e42a5bfc84795464bff023bff4c16f58c5) 
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 mnt_idmap *idmap,
119 			      struct dentry *dentry, struct iattr *iattr)
120 {
121 	struct inode *inode = d_inode(dentry);
122 	struct proc_dir_entry *de = PDE(inode);
123 	int error;
124 
125 	error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
126 	if (error)
127 		return error;
128 
129 	setattr_copy(&nop_mnt_idmap, inode, iattr);
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(struct mnt_idmap *idmap,
137 			const struct path *path, struct kstat *stat,
138 			u32 request_mask, unsigned int query_flags)
139 {
140 	struct inode *inode = d_inode(path->dentry);
141 	struct proc_dir_entry *de = PDE(inode);
142 	if (de) {
143 		nlink_t nlink = READ_ONCE(de->nlink);
144 		if (nlink > 0) {
145 			set_nlink(inode, nlink);
146 		}
147 	}
148 
149 	generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
150 	return 0;
151 }
152 
153 static const struct inode_operations proc_file_inode_operations = {
154 	.setattr	= proc_notify_change,
155 };
156 
157 /*
158  * This function parses a name such as "tty/driver/serial", and
159  * returns the struct proc_dir_entry for "/proc/tty/driver", and
160  * returns "serial" in residual.
161  */
162 static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
163 			     const char **residual)
164 {
165 	const char     		*cp = name, *next;
166 	struct proc_dir_entry	*de;
167 
168 	de = *ret ?: &proc_root;
169 	while ((next = strchr(cp, '/')) != NULL) {
170 		de = pde_subdir_find(de, cp, next - cp);
171 		if (!de) {
172 			WARN(1, "name '%s'\n", name);
173 			return -ENOENT;
174 		}
175 		cp = next + 1;
176 	}
177 	*residual = cp;
178 	*ret = de;
179 	return 0;
180 }
181 
182 static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
183 			   const char **residual)
184 {
185 	int rv;
186 
187 	read_lock(&proc_subdir_lock);
188 	rv = __xlate_proc_name(name, ret, residual);
189 	read_unlock(&proc_subdir_lock);
190 	return rv;
191 }
192 
193 static DEFINE_IDA(proc_inum_ida);
194 
195 #define PROC_DYNAMIC_FIRST 0xF0000000U
196 
197 /*
198  * Return an inode number between PROC_DYNAMIC_FIRST and
199  * 0xffffffff, or zero on failure.
200  */
201 int proc_alloc_inum(unsigned int *inum)
202 {
203 	int i;
204 
205 	i = ida_alloc_max(&proc_inum_ida, UINT_MAX - PROC_DYNAMIC_FIRST,
206 			  GFP_KERNEL);
207 	if (i < 0)
208 		return i;
209 
210 	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
211 	return 0;
212 }
213 
214 void proc_free_inum(unsigned int inum)
215 {
216 	ida_free(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
217 }
218 
219 static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
220 {
221 	if (flags & LOOKUP_RCU)
222 		return -ECHILD;
223 
224 	if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
225 		return 0; /* revalidate */
226 	return 1;
227 }
228 
229 static int proc_misc_d_delete(const struct dentry *dentry)
230 {
231 	return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
232 }
233 
234 static const struct dentry_operations proc_misc_dentry_ops = {
235 	.d_revalidate	= proc_misc_d_revalidate,
236 	.d_delete	= proc_misc_d_delete,
237 };
238 
239 /*
240  * Don't create negative dentries here, return -ENOENT by hand
241  * instead.
242  */
243 struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
244 			      struct proc_dir_entry *de)
245 {
246 	struct inode *inode;
247 
248 	read_lock(&proc_subdir_lock);
249 	de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
250 	if (de) {
251 		pde_get(de);
252 		read_unlock(&proc_subdir_lock);
253 		inode = proc_get_inode(dir->i_sb, de);
254 		if (!inode)
255 			return ERR_PTR(-ENOMEM);
256 		d_set_d_op(dentry, de->proc_dops);
257 		return d_splice_alias(inode, dentry);
258 	}
259 	read_unlock(&proc_subdir_lock);
260 	return ERR_PTR(-ENOENT);
261 }
262 
263 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
264 		unsigned int flags)
265 {
266 	struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb);
267 
268 	if (fs_info->pidonly == PROC_PIDONLY_ON)
269 		return ERR_PTR(-ENOENT);
270 
271 	return proc_lookup_de(dir, dentry, PDE(dir));
272 }
273 
274 /*
275  * This returns non-zero if at EOF, so that the /proc
276  * root directory can use this and check if it should
277  * continue with the <pid> entries..
278  *
279  * Note that the VFS-layer doesn't care about the return
280  * value of the readdir() call, as long as it's non-negative
281  * for success..
282  */
283 int proc_readdir_de(struct file *file, struct dir_context *ctx,
284 		    struct proc_dir_entry *de)
285 {
286 	int i;
287 
288 	if (!dir_emit_dots(file, ctx))
289 		return 0;
290 
291 	i = ctx->pos - 2;
292 	read_lock(&proc_subdir_lock);
293 	de = pde_subdir_first(de);
294 	for (;;) {
295 		if (!de) {
296 			read_unlock(&proc_subdir_lock);
297 			return 0;
298 		}
299 		if (!i)
300 			break;
301 		de = pde_subdir_next(de);
302 		i--;
303 	}
304 
305 	do {
306 		struct proc_dir_entry *next;
307 		pde_get(de);
308 		read_unlock(&proc_subdir_lock);
309 		if (!dir_emit(ctx, de->name, de->namelen,
310 			    de->low_ino, de->mode >> 12)) {
311 			pde_put(de);
312 			return 0;
313 		}
314 		ctx->pos++;
315 		read_lock(&proc_subdir_lock);
316 		next = pde_subdir_next(de);
317 		pde_put(de);
318 		de = next;
319 	} while (de);
320 	read_unlock(&proc_subdir_lock);
321 	return 1;
322 }
323 
324 int proc_readdir(struct file *file, struct dir_context *ctx)
325 {
326 	struct inode *inode = file_inode(file);
327 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
328 
329 	if (fs_info->pidonly == PROC_PIDONLY_ON)
330 		return 1;
331 
332 	return proc_readdir_de(file, ctx, PDE(inode));
333 }
334 
335 /*
336  * These are the generic /proc directory operations. They
337  * use the in-memory "struct proc_dir_entry" tree to parse
338  * the /proc directory.
339  */
340 static const struct file_operations proc_dir_operations = {
341 	.llseek			= generic_file_llseek,
342 	.read			= generic_read_dir,
343 	.iterate_shared		= proc_readdir,
344 };
345 
346 static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
347 {
348 	return 0;
349 }
350 
351 const struct dentry_operations proc_net_dentry_ops = {
352 	.d_revalidate	= proc_net_d_revalidate,
353 	.d_delete	= always_delete_dentry,
354 };
355 
356 /*
357  * proc directories can do almost nothing..
358  */
359 static const struct inode_operations proc_dir_inode_operations = {
360 	.lookup		= proc_lookup,
361 	.getattr	= proc_getattr,
362 	.setattr	= proc_notify_change,
363 };
364 
365 /* returns the registered entry, or frees dp and returns NULL on failure */
366 struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
367 		struct proc_dir_entry *dp)
368 {
369 	if (proc_alloc_inum(&dp->low_ino))
370 		goto out_free_entry;
371 
372 	write_lock(&proc_subdir_lock);
373 	dp->parent = dir;
374 	if (pde_subdir_insert(dir, dp) == false) {
375 		WARN(1, "proc_dir_entry '%s/%s' already registered\n",
376 		     dir->name, dp->name);
377 		write_unlock(&proc_subdir_lock);
378 		goto out_free_inum;
379 	}
380 	dir->nlink++;
381 	write_unlock(&proc_subdir_lock);
382 
383 	return dp;
384 out_free_inum:
385 	proc_free_inum(dp->low_ino);
386 out_free_entry:
387 	pde_free(dp);
388 	return NULL;
389 }
390 
391 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
392 					  const char *name,
393 					  umode_t mode,
394 					  nlink_t nlink)
395 {
396 	struct proc_dir_entry *ent = NULL;
397 	const char *fn;
398 	struct qstr qstr;
399 
400 	if (xlate_proc_name(name, parent, &fn) != 0)
401 		goto out;
402 	qstr.name = fn;
403 	qstr.len = strlen(fn);
404 	if (qstr.len == 0 || qstr.len >= 256) {
405 		WARN(1, "name len %u\n", qstr.len);
406 		return NULL;
407 	}
408 	if (qstr.len == 1 && fn[0] == '.') {
409 		WARN(1, "name '.'\n");
410 		return NULL;
411 	}
412 	if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
413 		WARN(1, "name '..'\n");
414 		return NULL;
415 	}
416 	if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
417 		WARN(1, "create '/proc/%s' by hand\n", qstr.name);
418 		return NULL;
419 	}
420 	if (is_empty_pde(*parent)) {
421 		WARN(1, "attempt to add to permanently empty directory");
422 		return NULL;
423 	}
424 
425 	ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
426 	if (!ent)
427 		goto out;
428 
429 	if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
430 		ent->name = ent->inline_name;
431 	} else {
432 		ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
433 		if (!ent->name) {
434 			pde_free(ent);
435 			return NULL;
436 		}
437 	}
438 
439 	memcpy(ent->name, fn, qstr.len + 1);
440 	ent->namelen = qstr.len;
441 	ent->mode = mode;
442 	ent->nlink = nlink;
443 	ent->subdir = RB_ROOT;
444 	refcount_set(&ent->refcnt, 1);
445 	spin_lock_init(&ent->pde_unload_lock);
446 	INIT_LIST_HEAD(&ent->pde_openers);
447 	proc_set_user(ent, (*parent)->uid, (*parent)->gid);
448 
449 	ent->proc_dops = &proc_misc_dentry_ops;
450 	/* Revalidate everything under /proc/${pid}/net */
451 	if ((*parent)->proc_dops == &proc_net_dentry_ops)
452 		pde_force_lookup(ent);
453 
454 out:
455 	return ent;
456 }
457 
458 struct proc_dir_entry *proc_symlink(const char *name,
459 		struct proc_dir_entry *parent, const char *dest)
460 {
461 	struct proc_dir_entry *ent;
462 
463 	ent = __proc_create(&parent, name,
464 			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
465 
466 	if (ent) {
467 		ent->size = strlen(dest);
468 		ent->data = kmemdup(dest, ent->size + 1, GFP_KERNEL);
469 		if (ent->data) {
470 			ent->proc_iops = &proc_link_inode_operations;
471 			ent = proc_register(parent, ent);
472 		} else {
473 			pde_free(ent);
474 			ent = NULL;
475 		}
476 	}
477 	return ent;
478 }
479 EXPORT_SYMBOL(proc_symlink);
480 
481 struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
482 		struct proc_dir_entry *parent, void *data, bool force_lookup)
483 {
484 	struct proc_dir_entry *ent;
485 
486 	if (mode == 0)
487 		mode = S_IRUGO | S_IXUGO;
488 
489 	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
490 	if (ent) {
491 		ent->data = data;
492 		ent->proc_dir_ops = &proc_dir_operations;
493 		ent->proc_iops = &proc_dir_inode_operations;
494 		if (force_lookup) {
495 			pde_force_lookup(ent);
496 		}
497 		ent = proc_register(parent, ent);
498 	}
499 	return ent;
500 }
501 EXPORT_SYMBOL_GPL(_proc_mkdir);
502 
503 struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
504 		struct proc_dir_entry *parent, void *data)
505 {
506 	return _proc_mkdir(name, mode, parent, data, false);
507 }
508 EXPORT_SYMBOL_GPL(proc_mkdir_data);
509 
510 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
511 				       struct proc_dir_entry *parent)
512 {
513 	return proc_mkdir_data(name, mode, parent, NULL);
514 }
515 EXPORT_SYMBOL(proc_mkdir_mode);
516 
517 struct proc_dir_entry *proc_mkdir(const char *name,
518 		struct proc_dir_entry *parent)
519 {
520 	return proc_mkdir_data(name, 0, parent, NULL);
521 }
522 EXPORT_SYMBOL(proc_mkdir);
523 
524 struct proc_dir_entry *proc_create_mount_point(const char *name)
525 {
526 	umode_t mode = S_IFDIR | S_IRUGO | S_IXUGO;
527 	struct proc_dir_entry *ent, *parent = NULL;
528 
529 	ent = __proc_create(&parent, name, mode, 2);
530 	if (ent) {
531 		ent->data = NULL;
532 		ent->proc_dir_ops = NULL;
533 		ent->proc_iops = NULL;
534 		ent = proc_register(parent, ent);
535 	}
536 	return ent;
537 }
538 EXPORT_SYMBOL(proc_create_mount_point);
539 
540 struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
541 		struct proc_dir_entry **parent, void *data)
542 {
543 	struct proc_dir_entry *p;
544 
545 	if ((mode & S_IFMT) == 0)
546 		mode |= S_IFREG;
547 	if ((mode & S_IALLUGO) == 0)
548 		mode |= S_IRUGO;
549 	if (WARN_ON_ONCE(!S_ISREG(mode)))
550 		return NULL;
551 
552 	p = __proc_create(parent, name, mode, 1);
553 	if (p) {
554 		p->proc_iops = &proc_file_inode_operations;
555 		p->data = data;
556 	}
557 	return p;
558 }
559 
560 static inline void pde_set_flags(struct proc_dir_entry *pde)
561 {
562 	if (pde->proc_ops->proc_flags & PROC_ENTRY_PERMANENT)
563 		pde->flags |= PROC_ENTRY_PERMANENT;
564 }
565 
566 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
567 		struct proc_dir_entry *parent,
568 		const struct proc_ops *proc_ops, void *data)
569 {
570 	struct proc_dir_entry *p;
571 
572 	p = proc_create_reg(name, mode, &parent, data);
573 	if (!p)
574 		return NULL;
575 	p->proc_ops = proc_ops;
576 	pde_set_flags(p);
577 	return proc_register(parent, p);
578 }
579 EXPORT_SYMBOL(proc_create_data);
580 
581 struct proc_dir_entry *proc_create(const char *name, umode_t mode,
582 				   struct proc_dir_entry *parent,
583 				   const struct proc_ops *proc_ops)
584 {
585 	return proc_create_data(name, mode, parent, proc_ops, NULL);
586 }
587 EXPORT_SYMBOL(proc_create);
588 
589 static int proc_seq_open(struct inode *inode, struct file *file)
590 {
591 	struct proc_dir_entry *de = PDE(inode);
592 
593 	if (de->state_size)
594 		return seq_open_private(file, de->seq_ops, de->state_size);
595 	return seq_open(file, de->seq_ops);
596 }
597 
598 static int proc_seq_release(struct inode *inode, struct file *file)
599 {
600 	struct proc_dir_entry *de = PDE(inode);
601 
602 	if (de->state_size)
603 		return seq_release_private(inode, file);
604 	return seq_release(inode, file);
605 }
606 
607 static const struct proc_ops proc_seq_ops = {
608 	/* not permanent -- can call into arbitrary seq_operations */
609 	.proc_open	= proc_seq_open,
610 	.proc_read_iter	= seq_read_iter,
611 	.proc_lseek	= seq_lseek,
612 	.proc_release	= proc_seq_release,
613 };
614 
615 struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
616 		struct proc_dir_entry *parent, const struct seq_operations *ops,
617 		unsigned int state_size, void *data)
618 {
619 	struct proc_dir_entry *p;
620 
621 	p = proc_create_reg(name, mode, &parent, data);
622 	if (!p)
623 		return NULL;
624 	p->proc_ops = &proc_seq_ops;
625 	p->seq_ops = ops;
626 	p->state_size = state_size;
627 	return proc_register(parent, p);
628 }
629 EXPORT_SYMBOL(proc_create_seq_private);
630 
631 static int proc_single_open(struct inode *inode, struct file *file)
632 {
633 	struct proc_dir_entry *de = PDE(inode);
634 
635 	return single_open(file, de->single_show, de->data);
636 }
637 
638 static const struct proc_ops proc_single_ops = {
639 	/* not permanent -- can call into arbitrary ->single_show */
640 	.proc_open	= proc_single_open,
641 	.proc_read_iter = seq_read_iter,
642 	.proc_lseek	= seq_lseek,
643 	.proc_release	= single_release,
644 };
645 
646 struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
647 		struct proc_dir_entry *parent,
648 		int (*show)(struct seq_file *, void *), void *data)
649 {
650 	struct proc_dir_entry *p;
651 
652 	p = proc_create_reg(name, mode, &parent, data);
653 	if (!p)
654 		return NULL;
655 	p->proc_ops = &proc_single_ops;
656 	p->single_show = show;
657 	return proc_register(parent, p);
658 }
659 EXPORT_SYMBOL(proc_create_single_data);
660 
661 void proc_set_size(struct proc_dir_entry *de, loff_t size)
662 {
663 	de->size = size;
664 }
665 EXPORT_SYMBOL(proc_set_size);
666 
667 void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
668 {
669 	de->uid = uid;
670 	de->gid = gid;
671 }
672 EXPORT_SYMBOL(proc_set_user);
673 
674 void pde_put(struct proc_dir_entry *pde)
675 {
676 	if (refcount_dec_and_test(&pde->refcnt)) {
677 		proc_free_inum(pde->low_ino);
678 		pde_free(pde);
679 	}
680 }
681 
682 /*
683  * Remove a /proc entry and free it if it's not currently in use.
684  */
685 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
686 {
687 	struct proc_dir_entry *de = NULL;
688 	const char *fn = name;
689 	unsigned int len;
690 
691 	write_lock(&proc_subdir_lock);
692 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
693 		write_unlock(&proc_subdir_lock);
694 		return;
695 	}
696 	len = strlen(fn);
697 
698 	de = pde_subdir_find(parent, fn, len);
699 	if (de) {
700 		if (unlikely(pde_is_permanent(de))) {
701 			WARN(1, "removing permanent /proc entry '%s'", de->name);
702 			de = NULL;
703 		} else {
704 			rb_erase(&de->subdir_node, &parent->subdir);
705 			if (S_ISDIR(de->mode))
706 				parent->nlink--;
707 		}
708 	}
709 	write_unlock(&proc_subdir_lock);
710 	if (!de) {
711 		WARN(1, "name '%s'\n", name);
712 		return;
713 	}
714 
715 	proc_entry_rundown(de);
716 
717 	WARN(pde_subdir_first(de),
718 	     "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
719 	     __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
720 	pde_put(de);
721 }
722 EXPORT_SYMBOL(remove_proc_entry);
723 
724 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
725 {
726 	struct proc_dir_entry *root = NULL, *de, *next;
727 	const char *fn = name;
728 	unsigned int len;
729 
730 	write_lock(&proc_subdir_lock);
731 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
732 		write_unlock(&proc_subdir_lock);
733 		return -ENOENT;
734 	}
735 	len = strlen(fn);
736 
737 	root = pde_subdir_find(parent, fn, len);
738 	if (!root) {
739 		write_unlock(&proc_subdir_lock);
740 		return -ENOENT;
741 	}
742 	if (unlikely(pde_is_permanent(root))) {
743 		write_unlock(&proc_subdir_lock);
744 		WARN(1, "removing permanent /proc entry '%s/%s'",
745 			root->parent->name, root->name);
746 		return -EINVAL;
747 	}
748 	rb_erase(&root->subdir_node, &parent->subdir);
749 
750 	de = root;
751 	while (1) {
752 		next = pde_subdir_first(de);
753 		if (next) {
754 			if (unlikely(pde_is_permanent(next))) {
755 				write_unlock(&proc_subdir_lock);
756 				WARN(1, "removing permanent /proc entry '%s/%s'",
757 					next->parent->name, next->name);
758 				return -EINVAL;
759 			}
760 			rb_erase(&next->subdir_node, &de->subdir);
761 			de = next;
762 			continue;
763 		}
764 		next = de->parent;
765 		if (S_ISDIR(de->mode))
766 			next->nlink--;
767 		write_unlock(&proc_subdir_lock);
768 
769 		proc_entry_rundown(de);
770 		if (de == root)
771 			break;
772 		pde_put(de);
773 
774 		write_lock(&proc_subdir_lock);
775 		de = next;
776 	}
777 	pde_put(root);
778 	return 0;
779 }
780 EXPORT_SYMBOL(remove_proc_subtree);
781 
782 void *proc_get_parent_data(const struct inode *inode)
783 {
784 	struct proc_dir_entry *de = PDE(inode);
785 	return de->parent->data;
786 }
787 EXPORT_SYMBOL_GPL(proc_get_parent_data);
788 
789 void proc_remove(struct proc_dir_entry *de)
790 {
791 	if (de)
792 		remove_proc_subtree(de->name, de->parent);
793 }
794 EXPORT_SYMBOL(proc_remove);
795 
796 /*
797  * Pull a user buffer into memory and pass it to the file's write handler if
798  * one is supplied.  The ->write() method is permitted to modify the
799  * kernel-side buffer.
800  */
801 ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
802 			  loff_t *_pos)
803 {
804 	struct proc_dir_entry *pde = PDE(file_inode(f));
805 	char *buf;
806 	int ret;
807 
808 	if (!pde->write)
809 		return -EACCES;
810 	if (size == 0 || size > PAGE_SIZE - 1)
811 		return -EINVAL;
812 	buf = memdup_user_nul(ubuf, size);
813 	if (IS_ERR(buf))
814 		return PTR_ERR(buf);
815 	ret = pde->write(f, buf, size);
816 	kfree(buf);
817 	return ret == 0 ? size : ret;
818 }
819