xref: /linux/fs/proc/generic.c (revision 26ba30221c03364d6ed9910be8da4c1fd871b07b) 
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 	if (S_ISDIR(de->mode))
116 		dir->nlink++;
117 	return true;
118 }
119 
120 static int proc_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
121 		struct iattr *iattr)
122 {
123 	struct inode *inode = d_inode(dentry);
124 	struct proc_dir_entry *de = PDE(inode);
125 	int error;
126 
127 	error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
128 	if (error)
129 		return error;
130 
131 	setattr_copy(&nop_mnt_idmap, inode, iattr);
132 
133 	proc_set_user(de, inode->i_uid, inode->i_gid);
134 	de->mode = inode->i_mode;
135 	return 0;
136 }
137 
138 static int proc_getattr(struct mnt_idmap *idmap,
139 			const struct path *path, struct kstat *stat,
140 			u32 request_mask, unsigned int query_flags)
141 {
142 	struct inode *inode = d_inode(path->dentry);
143 	struct proc_dir_entry *de = PDE(inode);
144 	if (de) {
145 		nlink_t nlink = READ_ONCE(de->nlink);
146 		if (nlink > 0) {
147 			set_nlink(inode, nlink);
148 		}
149 	}
150 
151 	generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
152 	return 0;
153 }
154 
155 static const struct inode_operations proc_file_inode_operations = {
156 	.setattr	= proc_setattr,
157 };
158 
159 /*
160  * This function parses a name such as "tty/driver/serial", and
161  * returns the struct proc_dir_entry for "/proc/tty/driver", and
162  * returns "serial" in residual.
163  */
164 static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
165 			     const char **residual)
166 {
167 	const char     		*cp = name, *next;
168 	struct proc_dir_entry	*de;
169 
170 	de = *ret ?: &proc_root;
171 	while ((next = strchr(cp, '/')) != NULL) {
172 		de = pde_subdir_find(de, cp, next - cp);
173 		if (!de) {
174 			WARN(1, "name '%s'\n", name);
175 			return -ENOENT;
176 		}
177 		cp = next + 1;
178 	}
179 	*residual = cp;
180 	*ret = de;
181 	return 0;
182 }
183 
184 static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
185 			   const char **residual)
186 {
187 	int rv;
188 
189 	read_lock(&proc_subdir_lock);
190 	rv = __xlate_proc_name(name, ret, residual);
191 	read_unlock(&proc_subdir_lock);
192 	return rv;
193 }
194 
195 static DEFINE_IDA(proc_inum_ida);
196 
197 #define PROC_DYNAMIC_FIRST 0xF0000000U
198 
199 /*
200  * Return an inode number between PROC_DYNAMIC_FIRST and
201  * 0xffffffff, or zero on failure.
202  */
203 int proc_alloc_inum(unsigned int *inum)
204 {
205 	int i;
206 
207 	i = ida_alloc_max(&proc_inum_ida, UINT_MAX - PROC_DYNAMIC_FIRST,
208 			  GFP_KERNEL);
209 	if (i < 0)
210 		return i;
211 
212 	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
213 	return 0;
214 }
215 
216 void proc_free_inum(unsigned int inum)
217 {
218 	ida_free(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
219 }
220 
221 static int proc_misc_d_revalidate(struct inode *dir, const struct qstr *name,
222 				  struct dentry *dentry, unsigned int flags)
223 {
224 	if (flags & LOOKUP_RCU)
225 		return -ECHILD;
226 
227 	if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
228 		return 0; /* revalidate */
229 	return 1;
230 }
231 
232 static int proc_misc_d_delete(const struct dentry *dentry)
233 {
234 	return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
235 }
236 
237 static const struct dentry_operations proc_misc_dentry_ops = {
238 	.d_revalidate	= proc_misc_d_revalidate,
239 	.d_delete	= proc_misc_d_delete,
240 };
241 
242 /*
243  * Don't create negative dentries here, return -ENOENT by hand
244  * instead.
245  */
246 struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
247 			      struct proc_dir_entry *de)
248 {
249 	struct inode *inode;
250 
251 	read_lock(&proc_subdir_lock);
252 	de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
253 	if (de) {
254 		pde_get(de);
255 		read_unlock(&proc_subdir_lock);
256 		inode = proc_get_inode(dir->i_sb, de);
257 		if (!inode)
258 			return ERR_PTR(-ENOMEM);
259 		if (de->flags & PROC_ENTRY_FORCE_LOOKUP)
260 			return d_splice_alias_ops(inode, dentry,
261 						  &proc_net_dentry_ops);
262 		return d_splice_alias_ops(inode, dentry,
263 					  &proc_misc_dentry_ops);
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 	struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb);
273 
274 	if (fs_info->pidonly == PROC_PIDONLY_ON)
275 		return ERR_PTR(-ENOENT);
276 
277 	return proc_lookup_de(dir, dentry, PDE(dir));
278 }
279 
280 /*
281  * This returns non-zero if at EOF, so that the /proc
282  * root directory can use this and check if it should
283  * continue with the <pid> entries..
284  *
285  * Note that the VFS-layer doesn't care about the return
286  * value of the readdir() call, as long as it's non-negative
287  * for success..
288  */
289 int proc_readdir_de(struct file *file, struct dir_context *ctx,
290 		    struct proc_dir_entry *de)
291 {
292 	int i;
293 
294 	if (!dir_emit_dots(file, ctx))
295 		return 0;
296 
297 	i = ctx->pos - 2;
298 	read_lock(&proc_subdir_lock);
299 	de = pde_subdir_first(de);
300 	for (;;) {
301 		if (!de) {
302 			read_unlock(&proc_subdir_lock);
303 			return 0;
304 		}
305 		if (!i)
306 			break;
307 		de = pde_subdir_next(de);
308 		i--;
309 	}
310 
311 	do {
312 		struct proc_dir_entry *next;
313 		pde_get(de);
314 		read_unlock(&proc_subdir_lock);
315 		if (!dir_emit(ctx, de->name, de->namelen,
316 			    de->low_ino, de->mode >> 12)) {
317 			pde_put(de);
318 			return 0;
319 		}
320 		ctx->pos++;
321 		read_lock(&proc_subdir_lock);
322 		next = pde_subdir_next(de);
323 		pde_put(de);
324 		de = next;
325 	} while (de);
326 	read_unlock(&proc_subdir_lock);
327 	return 1;
328 }
329 
330 int proc_readdir(struct file *file, struct dir_context *ctx)
331 {
332 	struct inode *inode = file_inode(file);
333 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
334 
335 	if (fs_info->pidonly == PROC_PIDONLY_ON)
336 		return 1;
337 
338 	return proc_readdir_de(file, ctx, PDE(inode));
339 }
340 
341 /*
342  * These are the generic /proc directory operations. They
343  * use the in-memory "struct proc_dir_entry" tree to parse
344  * the /proc directory.
345  */
346 static const struct file_operations proc_dir_operations = {
347 	.llseek			= generic_file_llseek,
348 	.read			= generic_read_dir,
349 	.iterate_shared		= proc_readdir,
350 };
351 
352 static int proc_net_d_revalidate(struct inode *dir, const struct qstr *name,
353 				 struct dentry *dentry, unsigned int flags)
354 {
355 	return 0;
356 }
357 
358 const struct dentry_operations proc_net_dentry_ops = {
359 	.d_revalidate	= proc_net_d_revalidate,
360 	.d_delete	= always_delete_dentry,
361 };
362 
363 /*
364  * proc directories can do almost nothing..
365  */
366 static const struct inode_operations proc_dir_inode_operations = {
367 	.lookup		= proc_lookup,
368 	.getattr	= proc_getattr,
369 	.setattr	= proc_setattr,
370 };
371 
372 static void pde_set_flags(struct proc_dir_entry *pde)
373 {
374 	const struct proc_ops *proc_ops = pde->proc_ops;
375 
376 	if (!proc_ops)
377 		return;
378 
379 	if (proc_ops->proc_flags & PROC_ENTRY_PERMANENT)
380 		pde->flags |= PROC_ENTRY_PERMANENT;
381 	if (proc_ops->proc_read_iter)
382 		pde->flags |= PROC_ENTRY_proc_read_iter;
383 #ifdef CONFIG_COMPAT
384 	if (proc_ops->proc_compat_ioctl)
385 		pde->flags |= PROC_ENTRY_proc_compat_ioctl;
386 #endif
387 	if (proc_ops->proc_lseek)
388 		pde->flags |= PROC_ENTRY_proc_lseek;
389 }
390 
391 /* returns the registered entry, or frees dp and returns NULL on failure */
392 struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
393 		struct proc_dir_entry *dp)
394 {
395 	if (proc_alloc_inum(&dp->low_ino))
396 		goto out_free_entry;
397 
398 	if (!S_ISDIR(dp->mode))
399 		pde_set_flags(dp);
400 
401 	write_lock(&proc_subdir_lock);
402 	dp->parent = dir;
403 	if (pde_subdir_insert(dir, dp) == false) {
404 		WARN(1, "proc_dir_entry '%s/%s' already registered\n",
405 		     dir->name, dp->name);
406 		write_unlock(&proc_subdir_lock);
407 		goto out_free_inum;
408 	}
409 	write_unlock(&proc_subdir_lock);
410 
411 	return dp;
412 out_free_inum:
413 	proc_free_inum(dp->low_ino);
414 out_free_entry:
415 	pde_free(dp);
416 	return NULL;
417 }
418 
419 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
420 					  const char *name,
421 					  umode_t mode,
422 					  nlink_t nlink)
423 {
424 	struct proc_dir_entry *ent = NULL;
425 	const char *fn;
426 	struct qstr qstr;
427 
428 	if (xlate_proc_name(name, parent, &fn) != 0)
429 		goto out;
430 	qstr.name = fn;
431 	qstr.len = strnlen(fn, NAME_MAX + 1);
432 	if (qstr.len == 0) {
433 		WARN(1, "empty name\n");
434 		return NULL;
435 	}
436 	if (qstr.len > NAME_MAX) {
437 		WARN(1, "name too long\n");
438 		return NULL;
439 	}
440 	if (qstr.len == 1 && fn[0] == '.') {
441 		WARN(1, "name '.'\n");
442 		return NULL;
443 	}
444 	if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
445 		WARN(1, "name '..'\n");
446 		return NULL;
447 	}
448 	if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
449 		WARN(1, "create '/proc/%s' by hand\n", qstr.name);
450 		return NULL;
451 	}
452 	if (is_empty_pde(*parent)) {
453 		WARN(1, "attempt to add to permanently empty directory");
454 		return NULL;
455 	}
456 
457 	ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
458 	if (!ent)
459 		goto out;
460 
461 	if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
462 		ent->name = ent->inline_name;
463 	} else {
464 		ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
465 		if (!ent->name) {
466 			pde_free(ent);
467 			return NULL;
468 		}
469 	}
470 
471 	memcpy(ent->name, fn, qstr.len + 1);
472 	ent->namelen = qstr.len;
473 	ent->mode = mode;
474 	ent->nlink = nlink;
475 	ent->subdir = RB_ROOT;
476 	refcount_set(&ent->refcnt, 1);
477 	spin_lock_init(&ent->pde_unload_lock);
478 	INIT_LIST_HEAD(&ent->pde_openers);
479 	proc_set_user(ent, (*parent)->uid, (*parent)->gid);
480 
481 	/* Revalidate everything under /proc/${pid}/net */
482 	if ((*parent)->flags & PROC_ENTRY_FORCE_LOOKUP)
483 		pde_force_lookup(ent);
484 
485 out:
486 	return ent;
487 }
488 
489 struct proc_dir_entry *proc_symlink(const char *name,
490 		struct proc_dir_entry *parent, const char *dest)
491 {
492 	struct proc_dir_entry *ent;
493 
494 	ent = __proc_create(&parent, name,
495 			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
496 
497 	if (ent) {
498 		ent->size = strlen(dest);
499 		ent->data = kmemdup(dest, ent->size + 1, GFP_KERNEL);
500 		if (ent->data) {
501 			ent->proc_iops = &proc_link_inode_operations;
502 			ent = proc_register(parent, ent);
503 		} else {
504 			pde_free(ent);
505 			ent = NULL;
506 		}
507 	}
508 	return ent;
509 }
510 EXPORT_SYMBOL(proc_symlink);
511 
512 struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
513 		struct proc_dir_entry *parent, void *data, bool force_lookup)
514 {
515 	struct proc_dir_entry *ent;
516 
517 	if (mode == 0)
518 		mode = S_IRUGO | S_IXUGO;
519 
520 	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
521 	if (ent) {
522 		ent->data = data;
523 		ent->proc_dir_ops = &proc_dir_operations;
524 		ent->proc_iops = &proc_dir_inode_operations;
525 		if (force_lookup) {
526 			pde_force_lookup(ent);
527 		}
528 		ent = proc_register(parent, ent);
529 	}
530 	return ent;
531 }
532 EXPORT_SYMBOL_GPL(_proc_mkdir);
533 
534 struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
535 		struct proc_dir_entry *parent, void *data)
536 {
537 	return _proc_mkdir(name, mode, parent, data, false);
538 }
539 EXPORT_SYMBOL_GPL(proc_mkdir_data);
540 
541 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
542 				       struct proc_dir_entry *parent)
543 {
544 	return proc_mkdir_data(name, mode, parent, NULL);
545 }
546 EXPORT_SYMBOL(proc_mkdir_mode);
547 
548 struct proc_dir_entry *proc_mkdir(const char *name,
549 		struct proc_dir_entry *parent)
550 {
551 	return proc_mkdir_data(name, 0, parent, NULL);
552 }
553 EXPORT_SYMBOL(proc_mkdir);
554 
555 struct proc_dir_entry *proc_create_mount_point(const char *name)
556 {
557 	umode_t mode = S_IFDIR | S_IRUGO | S_IXUGO;
558 	struct proc_dir_entry *ent, *parent = NULL;
559 
560 	ent = __proc_create(&parent, name, mode, 2);
561 	if (ent) {
562 		ent->data = NULL;
563 		ent->proc_dir_ops = NULL;
564 		ent->proc_iops = NULL;
565 		ent = proc_register(parent, ent);
566 	}
567 	return ent;
568 }
569 EXPORT_SYMBOL(proc_create_mount_point);
570 
571 struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
572 		struct proc_dir_entry **parent, void *data)
573 {
574 	struct proc_dir_entry *p;
575 
576 	if ((mode & S_IFMT) == 0)
577 		mode |= S_IFREG;
578 	if ((mode & S_IALLUGO) == 0)
579 		mode |= S_IRUGO;
580 	if (WARN_ON_ONCE(!S_ISREG(mode)))
581 		return NULL;
582 
583 	p = __proc_create(parent, name, mode, 1);
584 	if (p) {
585 		p->proc_iops = &proc_file_inode_operations;
586 		p->data = data;
587 	}
588 	return p;
589 }
590 
591 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
592 		struct proc_dir_entry *parent,
593 		const struct proc_ops *proc_ops, void *data)
594 {
595 	struct proc_dir_entry *p;
596 
597 	p = proc_create_reg(name, mode, &parent, data);
598 	if (!p)
599 		return NULL;
600 	p->proc_ops = proc_ops;
601 	return proc_register(parent, p);
602 }
603 EXPORT_SYMBOL(proc_create_data);
604 
605 struct proc_dir_entry *proc_create(const char *name, umode_t mode,
606 				   struct proc_dir_entry *parent,
607 				   const struct proc_ops *proc_ops)
608 {
609 	return proc_create_data(name, mode, parent, proc_ops, NULL);
610 }
611 EXPORT_SYMBOL(proc_create);
612 
613 static int proc_seq_open(struct inode *inode, struct file *file)
614 {
615 	struct proc_dir_entry *de = PDE(inode);
616 
617 	if (de->state_size)
618 		return seq_open_private(file, de->seq_ops, de->state_size);
619 	return seq_open(file, de->seq_ops);
620 }
621 
622 static int proc_seq_release(struct inode *inode, struct file *file)
623 {
624 	struct proc_dir_entry *de = PDE(inode);
625 
626 	if (de->state_size)
627 		return seq_release_private(inode, file);
628 	return seq_release(inode, file);
629 }
630 
631 static const struct proc_ops proc_seq_ops = {
632 	/* not permanent -- can call into arbitrary seq_operations */
633 	.proc_open	= proc_seq_open,
634 	.proc_read_iter	= seq_read_iter,
635 	.proc_lseek	= seq_lseek,
636 	.proc_release	= proc_seq_release,
637 };
638 
639 struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
640 		struct proc_dir_entry *parent, const struct seq_operations *ops,
641 		unsigned int state_size, void *data)
642 {
643 	struct proc_dir_entry *p;
644 
645 	p = proc_create_reg(name, mode, &parent, data);
646 	if (!p)
647 		return NULL;
648 	p->proc_ops = &proc_seq_ops;
649 	p->seq_ops = ops;
650 	p->state_size = state_size;
651 	return proc_register(parent, p);
652 }
653 EXPORT_SYMBOL(proc_create_seq_private);
654 
655 static int proc_single_open(struct inode *inode, struct file *file)
656 {
657 	struct proc_dir_entry *de = PDE(inode);
658 
659 	return single_open(file, de->single_show, de->data);
660 }
661 
662 static const struct proc_ops proc_single_ops = {
663 	/* not permanent -- can call into arbitrary ->single_show */
664 	.proc_open	= proc_single_open,
665 	.proc_read_iter = seq_read_iter,
666 	.proc_lseek	= seq_lseek,
667 	.proc_release	= single_release,
668 };
669 
670 struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
671 		struct proc_dir_entry *parent,
672 		int (*show)(struct seq_file *, void *), void *data)
673 {
674 	struct proc_dir_entry *p;
675 
676 	p = proc_create_reg(name, mode, &parent, data);
677 	if (!p)
678 		return NULL;
679 	p->proc_ops = &proc_single_ops;
680 	p->single_show = show;
681 	return proc_register(parent, p);
682 }
683 EXPORT_SYMBOL(proc_create_single_data);
684 
685 void proc_set_size(struct proc_dir_entry *de, loff_t size)
686 {
687 	de->size = size;
688 }
689 EXPORT_SYMBOL(proc_set_size);
690 
691 void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
692 {
693 	de->uid = uid;
694 	de->gid = gid;
695 }
696 EXPORT_SYMBOL(proc_set_user);
697 
698 void pde_put(struct proc_dir_entry *pde)
699 {
700 	if (refcount_dec_and_test(&pde->refcnt)) {
701 		proc_free_inum(pde->low_ino);
702 		pde_free(pde);
703 	}
704 }
705 
706 static void pde_erase(struct proc_dir_entry *pde, struct proc_dir_entry *parent)
707 {
708 	rb_erase(&pde->subdir_node, &parent->subdir);
709 	RB_CLEAR_NODE(&pde->subdir_node);
710 	if (S_ISDIR(pde->mode))
711 		parent->nlink--;
712 }
713 
714 /*
715  * Remove a /proc entry and free it if it's not currently in use.
716  */
717 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
718 {
719 	struct proc_dir_entry *de = NULL;
720 	const char *fn = name;
721 	unsigned int len;
722 
723 	write_lock(&proc_subdir_lock);
724 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
725 		write_unlock(&proc_subdir_lock);
726 		return;
727 	}
728 	len = strlen(fn);
729 
730 	de = pde_subdir_find(parent, fn, len);
731 	if (de) {
732 		if (unlikely(pde_is_permanent(de))) {
733 			WARN(1, "removing permanent /proc entry '%s'", de->name);
734 			de = NULL;
735 		} else {
736 			pde_erase(de, parent);
737 		}
738 	}
739 	write_unlock(&proc_subdir_lock);
740 	if (!de) {
741 		WARN(1, "name '%s'\n", name);
742 		return;
743 	}
744 
745 	proc_entry_rundown(de);
746 
747 	WARN(pde_subdir_first(de),
748 	     "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
749 	     __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
750 	pde_put(de);
751 }
752 EXPORT_SYMBOL(remove_proc_entry);
753 
754 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
755 {
756 	struct proc_dir_entry *root = NULL, *de, *next;
757 	const char *fn = name;
758 	unsigned int len;
759 
760 	write_lock(&proc_subdir_lock);
761 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
762 		write_unlock(&proc_subdir_lock);
763 		return -ENOENT;
764 	}
765 	len = strlen(fn);
766 
767 	root = pde_subdir_find(parent, fn, len);
768 	if (!root) {
769 		write_unlock(&proc_subdir_lock);
770 		return -ENOENT;
771 	}
772 	if (unlikely(pde_is_permanent(root))) {
773 		write_unlock(&proc_subdir_lock);
774 		WARN(1, "removing permanent /proc entry '%s/%s'",
775 			root->parent->name, root->name);
776 		return -EINVAL;
777 	}
778 	pde_erase(root, parent);
779 
780 	de = root;
781 	while (1) {
782 		next = pde_subdir_first(de);
783 		if (next) {
784 			if (unlikely(pde_is_permanent(next))) {
785 				write_unlock(&proc_subdir_lock);
786 				WARN(1, "removing permanent /proc entry '%s/%s'",
787 					next->parent->name, next->name);
788 				return -EINVAL;
789 			}
790 			pde_erase(next, de);
791 			de = next;
792 			continue;
793 		}
794 		next = de->parent;
795 		write_unlock(&proc_subdir_lock);
796 
797 		proc_entry_rundown(de);
798 		if (de == root)
799 			break;
800 		pde_put(de);
801 
802 		write_lock(&proc_subdir_lock);
803 		de = next;
804 	}
805 	pde_put(root);
806 	return 0;
807 }
808 EXPORT_SYMBOL(remove_proc_subtree);
809 
810 void *proc_get_parent_data(const struct inode *inode)
811 {
812 	struct proc_dir_entry *de = PDE(inode);
813 	return de->parent->data;
814 }
815 EXPORT_SYMBOL_GPL(proc_get_parent_data);
816 
817 void proc_remove(struct proc_dir_entry *de)
818 {
819 	if (de)
820 		remove_proc_subtree(de->name, de->parent);
821 }
822 EXPORT_SYMBOL(proc_remove);
823 
824 /*
825  * Pull a user buffer into memory and pass it to the file's write handler if
826  * one is supplied.  The ->write() method is permitted to modify the
827  * kernel-side buffer.
828  */
829 ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
830 			  loff_t *_pos)
831 {
832 	struct proc_dir_entry *pde = PDE(file_inode(f));
833 	char *buf;
834 	int ret;
835 
836 	if (!pde->write)
837 		return -EACCES;
838 	if (size == 0 || size > PAGE_SIZE - 1)
839 		return -EINVAL;
840 	buf = memdup_user_nul(ubuf, size);
841 	if (IS_ERR(buf))
842 		return PTR_ERR(buf);
843 	ret = pde->write(f, buf, size);
844 	kfree(buf);
845 	return ret == 0 ? size : ret;
846 }
847 
848 /*
849  * Not exported to modules:
850  * modules' /proc files aren't permanent because modules aren't permanent.
851  */
852 void impl_proc_make_permanent(struct proc_dir_entry *pde)
853 {
854 	if (pde)
855 		pde_make_permanent(pde);
856 }
857