xref: /linux/fs/proc/generic.c (revision 8ca4fc323d2e4ab9dabbdd57633af40b0c7e6af9) 
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 user_namespace *mnt_userns,
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(&init_user_ns, dentry, iattr);
126 	if (error)
127 		return error;
128 
129 	setattr_copy(&init_user_ns, inode, iattr);
130 	mark_inode_dirty(inode);
131 
132 	proc_set_user(de, inode->i_uid, inode->i_gid);
133 	de->mode = inode->i_mode;
134 	return 0;
135 }
136 
137 static int proc_getattr(struct user_namespace *mnt_userns,
138 			const struct path *path, struct kstat *stat,
139 			u32 request_mask, unsigned int query_flags)
140 {
141 	struct inode *inode = d_inode(path->dentry);
142 	struct proc_dir_entry *de = PDE(inode);
143 	if (de) {
144 		nlink_t nlink = READ_ONCE(de->nlink);
145 		if (nlink > 0) {
146 			set_nlink(inode, nlink);
147 		}
148 	}
149 
150 	generic_fillattr(&init_user_ns, inode, stat);
151 	return 0;
152 }
153 
154 static const struct inode_operations proc_file_inode_operations = {
155 	.setattr	= proc_notify_change,
156 };
157 
158 /*
159  * This function parses a name such as "tty/driver/serial", and
160  * returns the struct proc_dir_entry for "/proc/tty/driver", and
161  * returns "serial" in residual.
162  */
163 static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
164 			     const char **residual)
165 {
166 	const char     		*cp = name, *next;
167 	struct proc_dir_entry	*de;
168 
169 	de = *ret ?: &proc_root;
170 	while ((next = strchr(cp, '/')) != NULL) {
171 		de = pde_subdir_find(de, cp, next - cp);
172 		if (!de) {
173 			WARN(1, "name '%s'\n", name);
174 			return -ENOENT;
175 		}
176 		cp = next + 1;
177 	}
178 	*residual = cp;
179 	*ret = de;
180 	return 0;
181 }
182 
183 static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
184 			   const char **residual)
185 {
186 	int rv;
187 
188 	read_lock(&proc_subdir_lock);
189 	rv = __xlate_proc_name(name, ret, residual);
190 	read_unlock(&proc_subdir_lock);
191 	return rv;
192 }
193 
194 static DEFINE_IDA(proc_inum_ida);
195 
196 #define PROC_DYNAMIC_FIRST 0xF0000000U
197 
198 /*
199  * Return an inode number between PROC_DYNAMIC_FIRST and
200  * 0xffffffff, or zero on failure.
201  */
202 int proc_alloc_inum(unsigned int *inum)
203 {
204 	int i;
205 
206 	i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
207 			   GFP_KERNEL);
208 	if (i < 0)
209 		return i;
210 
211 	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
212 	return 0;
213 }
214 
215 void proc_free_inum(unsigned int inum)
216 {
217 	ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
218 }
219 
220 static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
221 {
222 	if (flags & LOOKUP_RCU)
223 		return -ECHILD;
224 
225 	if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
226 		return 0; /* revalidate */
227 	return 1;
228 }
229 
230 static int proc_misc_d_delete(const struct dentry *dentry)
231 {
232 	return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
233 }
234 
235 static const struct dentry_operations proc_misc_dentry_ops = {
236 	.d_revalidate	= proc_misc_d_revalidate,
237 	.d_delete	= proc_misc_d_delete,
238 };
239 
240 /*
241  * Don't create negative dentries here, return -ENOENT by hand
242  * instead.
243  */
244 struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
245 			      struct proc_dir_entry *de)
246 {
247 	struct inode *inode;
248 
249 	read_lock(&proc_subdir_lock);
250 	de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
251 	if (de) {
252 		pde_get(de);
253 		read_unlock(&proc_subdir_lock);
254 		inode = proc_get_inode(dir->i_sb, de);
255 		if (!inode)
256 			return ERR_PTR(-ENOMEM);
257 		d_set_d_op(dentry, de->proc_dops);
258 		return d_splice_alias(inode, dentry);
259 	}
260 	read_unlock(&proc_subdir_lock);
261 	return ERR_PTR(-ENOENT);
262 }
263 
264 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
265 		unsigned int flags)
266 {
267 	struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb);
268 
269 	if (fs_info->pidonly == PROC_PIDONLY_ON)
270 		return ERR_PTR(-ENOENT);
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 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
329 
330 	if (fs_info->pidonly == PROC_PIDONLY_ON)
331 		return 1;
332 
333 	return proc_readdir_de(file, ctx, PDE(inode));
334 }
335 
336 /*
337  * These are the generic /proc directory operations. They
338  * use the in-memory "struct proc_dir_entry" tree to parse
339  * the /proc directory.
340  */
341 static const struct file_operations proc_dir_operations = {
342 	.llseek			= generic_file_llseek,
343 	.read			= generic_read_dir,
344 	.iterate_shared		= proc_readdir,
345 };
346 
347 static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
348 {
349 	return 0;
350 }
351 
352 const struct dentry_operations proc_net_dentry_ops = {
353 	.d_revalidate	= proc_net_d_revalidate,
354 	.d_delete	= always_delete_dentry,
355 };
356 
357 /*
358  * proc directories can do almost nothing..
359  */
360 static const struct inode_operations proc_dir_inode_operations = {
361 	.lookup		= proc_lookup,
362 	.getattr	= proc_getattr,
363 	.setattr	= proc_notify_change,
364 };
365 
366 /* returns the registered entry, or frees dp and returns NULL on failure */
367 struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
368 		struct proc_dir_entry *dp)
369 {
370 	if (proc_alloc_inum(&dp->low_ino))
371 		goto out_free_entry;
372 
373 	write_lock(&proc_subdir_lock);
374 	dp->parent = dir;
375 	if (pde_subdir_insert(dir, dp) == false) {
376 		WARN(1, "proc_dir_entry '%s/%s' already registered\n",
377 		     dir->name, dp->name);
378 		write_unlock(&proc_subdir_lock);
379 		goto out_free_inum;
380 	}
381 	dir->nlink++;
382 	write_unlock(&proc_subdir_lock);
383 
384 	return dp;
385 out_free_inum:
386 	proc_free_inum(dp->low_ino);
387 out_free_entry:
388 	pde_free(dp);
389 	return NULL;
390 }
391 
392 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
393 					  const char *name,
394 					  umode_t mode,
395 					  nlink_t nlink)
396 {
397 	struct proc_dir_entry *ent = NULL;
398 	const char *fn;
399 	struct qstr qstr;
400 
401 	if (xlate_proc_name(name, parent, &fn) != 0)
402 		goto out;
403 	qstr.name = fn;
404 	qstr.len = strlen(fn);
405 	if (qstr.len == 0 || qstr.len >= 256) {
406 		WARN(1, "name len %u\n", qstr.len);
407 		return NULL;
408 	}
409 	if (qstr.len == 1 && fn[0] == '.') {
410 		WARN(1, "name '.'\n");
411 		return NULL;
412 	}
413 	if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
414 		WARN(1, "name '..'\n");
415 		return NULL;
416 	}
417 	if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
418 		WARN(1, "create '/proc/%s' by hand\n", qstr.name);
419 		return NULL;
420 	}
421 	if (is_empty_pde(*parent)) {
422 		WARN(1, "attempt to add to permanently empty directory");
423 		return NULL;
424 	}
425 
426 	ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
427 	if (!ent)
428 		goto out;
429 
430 	if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
431 		ent->name = ent->inline_name;
432 	} else {
433 		ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
434 		if (!ent->name) {
435 			pde_free(ent);
436 			return NULL;
437 		}
438 	}
439 
440 	memcpy(ent->name, fn, qstr.len + 1);
441 	ent->namelen = qstr.len;
442 	ent->mode = mode;
443 	ent->nlink = nlink;
444 	ent->subdir = RB_ROOT;
445 	refcount_set(&ent->refcnt, 1);
446 	spin_lock_init(&ent->pde_unload_lock);
447 	INIT_LIST_HEAD(&ent->pde_openers);
448 	proc_set_user(ent, (*parent)->uid, (*parent)->gid);
449 
450 	ent->proc_dops = &proc_misc_dentry_ops;
451 	/* Revalidate everything under /proc/${pid}/net */
452 	if ((*parent)->proc_dops == &proc_net_dentry_ops)
453 		pde_force_lookup(ent);
454 
455 out:
456 	return ent;
457 }
458 
459 struct proc_dir_entry *proc_symlink(const char *name,
460 		struct proc_dir_entry *parent, const char *dest)
461 {
462 	struct proc_dir_entry *ent;
463 
464 	ent = __proc_create(&parent, name,
465 			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
466 
467 	if (ent) {
468 		ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
469 		if (ent->data) {
470 			strcpy((char*)ent->data,dest);
471 			ent->proc_iops = &proc_link_inode_operations;
472 			ent = proc_register(parent, ent);
473 		} else {
474 			pde_free(ent);
475 			ent = NULL;
476 		}
477 	}
478 	return ent;
479 }
480 EXPORT_SYMBOL(proc_symlink);
481 
482 struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode,
483 		struct proc_dir_entry *parent, void *data, bool force_lookup)
484 {
485 	struct proc_dir_entry *ent;
486 
487 	if (mode == 0)
488 		mode = S_IRUGO | S_IXUGO;
489 
490 	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
491 	if (ent) {
492 		ent->data = data;
493 		ent->proc_dir_ops = &proc_dir_operations;
494 		ent->proc_iops = &proc_dir_inode_operations;
495 		if (force_lookup) {
496 			pde_force_lookup(ent);
497 		}
498 		ent = proc_register(parent, ent);
499 	}
500 	return ent;
501 }
502 EXPORT_SYMBOL_GPL(_proc_mkdir);
503 
504 struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
505 		struct proc_dir_entry *parent, void *data)
506 {
507 	return _proc_mkdir(name, mode, parent, data, false);
508 }
509 EXPORT_SYMBOL_GPL(proc_mkdir_data);
510 
511 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
512 				       struct proc_dir_entry *parent)
513 {
514 	return proc_mkdir_data(name, mode, parent, NULL);
515 }
516 EXPORT_SYMBOL(proc_mkdir_mode);
517 
518 struct proc_dir_entry *proc_mkdir(const char *name,
519 		struct proc_dir_entry *parent)
520 {
521 	return proc_mkdir_data(name, 0, parent, NULL);
522 }
523 EXPORT_SYMBOL(proc_mkdir);
524 
525 struct proc_dir_entry *proc_create_mount_point(const char *name)
526 {
527 	umode_t mode = S_IFDIR | S_IRUGO | S_IXUGO;
528 	struct proc_dir_entry *ent, *parent = NULL;
529 
530 	ent = __proc_create(&parent, name, mode, 2);
531 	if (ent) {
532 		ent->data = NULL;
533 		ent->proc_dir_ops = NULL;
534 		ent->proc_iops = NULL;
535 		ent = proc_register(parent, ent);
536 	}
537 	return ent;
538 }
539 EXPORT_SYMBOL(proc_create_mount_point);
540 
541 struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
542 		struct proc_dir_entry **parent, void *data)
543 {
544 	struct proc_dir_entry *p;
545 
546 	if ((mode & S_IFMT) == 0)
547 		mode |= S_IFREG;
548 	if ((mode & S_IALLUGO) == 0)
549 		mode |= S_IRUGO;
550 	if (WARN_ON_ONCE(!S_ISREG(mode)))
551 		return NULL;
552 
553 	p = __proc_create(parent, name, mode, 1);
554 	if (p) {
555 		p->proc_iops = &proc_file_inode_operations;
556 		p->data = data;
557 	}
558 	return p;
559 }
560 
561 static inline void pde_set_flags(struct proc_dir_entry *pde)
562 {
563 	if (pde->proc_ops->proc_flags & PROC_ENTRY_PERMANENT)
564 		pde->flags |= PROC_ENTRY_PERMANENT;
565 }
566 
567 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
568 		struct proc_dir_entry *parent,
569 		const struct proc_ops *proc_ops, void *data)
570 {
571 	struct proc_dir_entry *p;
572 
573 	p = proc_create_reg(name, mode, &parent, data);
574 	if (!p)
575 		return NULL;
576 	p->proc_ops = proc_ops;
577 	pde_set_flags(p);
578 	return proc_register(parent, p);
579 }
580 EXPORT_SYMBOL(proc_create_data);
581 
582 struct proc_dir_entry *proc_create(const char *name, umode_t mode,
583 				   struct proc_dir_entry *parent,
584 				   const struct proc_ops *proc_ops)
585 {
586 	return proc_create_data(name, mode, parent, proc_ops, NULL);
587 }
588 EXPORT_SYMBOL(proc_create);
589 
590 static int proc_seq_open(struct inode *inode, struct file *file)
591 {
592 	struct proc_dir_entry *de = PDE(inode);
593 
594 	if (de->state_size)
595 		return seq_open_private(file, de->seq_ops, de->state_size);
596 	return seq_open(file, de->seq_ops);
597 }
598 
599 static int proc_seq_release(struct inode *inode, struct file *file)
600 {
601 	struct proc_dir_entry *de = PDE(inode);
602 
603 	if (de->state_size)
604 		return seq_release_private(inode, file);
605 	return seq_release(inode, file);
606 }
607 
608 static const struct proc_ops proc_seq_ops = {
609 	/* not permanent -- can call into arbitrary seq_operations */
610 	.proc_open	= proc_seq_open,
611 	.proc_read_iter	= seq_read_iter,
612 	.proc_lseek	= seq_lseek,
613 	.proc_release	= proc_seq_release,
614 };
615 
616 struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
617 		struct proc_dir_entry *parent, const struct seq_operations *ops,
618 		unsigned int state_size, void *data)
619 {
620 	struct proc_dir_entry *p;
621 
622 	p = proc_create_reg(name, mode, &parent, data);
623 	if (!p)
624 		return NULL;
625 	p->proc_ops = &proc_seq_ops;
626 	p->seq_ops = ops;
627 	p->state_size = state_size;
628 	return proc_register(parent, p);
629 }
630 EXPORT_SYMBOL(proc_create_seq_private);
631 
632 static int proc_single_open(struct inode *inode, struct file *file)
633 {
634 	struct proc_dir_entry *de = PDE(inode);
635 
636 	return single_open(file, de->single_show, de->data);
637 }
638 
639 static const struct proc_ops proc_single_ops = {
640 	/* not permanent -- can call into arbitrary ->single_show */
641 	.proc_open	= proc_single_open,
642 	.proc_read_iter = seq_read_iter,
643 	.proc_lseek	= seq_lseek,
644 	.proc_release	= single_release,
645 };
646 
647 struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
648 		struct proc_dir_entry *parent,
649 		int (*show)(struct seq_file *, void *), void *data)
650 {
651 	struct proc_dir_entry *p;
652 
653 	p = proc_create_reg(name, mode, &parent, data);
654 	if (!p)
655 		return NULL;
656 	p->proc_ops = &proc_single_ops;
657 	p->single_show = show;
658 	return proc_register(parent, p);
659 }
660 EXPORT_SYMBOL(proc_create_single_data);
661 
662 void proc_set_size(struct proc_dir_entry *de, loff_t size)
663 {
664 	de->size = size;
665 }
666 EXPORT_SYMBOL(proc_set_size);
667 
668 void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
669 {
670 	de->uid = uid;
671 	de->gid = gid;
672 }
673 EXPORT_SYMBOL(proc_set_user);
674 
675 void pde_put(struct proc_dir_entry *pde)
676 {
677 	if (refcount_dec_and_test(&pde->refcnt)) {
678 		proc_free_inum(pde->low_ino);
679 		pde_free(pde);
680 	}
681 }
682 
683 /*
684  * Remove a /proc entry and free it if it's not currently in use.
685  */
686 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
687 {
688 	struct proc_dir_entry *de = NULL;
689 	const char *fn = name;
690 	unsigned int len;
691 
692 	write_lock(&proc_subdir_lock);
693 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
694 		write_unlock(&proc_subdir_lock);
695 		return;
696 	}
697 	len = strlen(fn);
698 
699 	de = pde_subdir_find(parent, fn, len);
700 	if (de) {
701 		if (unlikely(pde_is_permanent(de))) {
702 			WARN(1, "removing permanent /proc entry '%s'", de->name);
703 			de = NULL;
704 		} else {
705 			rb_erase(&de->subdir_node, &parent->subdir);
706 			if (S_ISDIR(de->mode))
707 				parent->nlink--;
708 		}
709 	}
710 	write_unlock(&proc_subdir_lock);
711 	if (!de) {
712 		WARN(1, "name '%s'\n", name);
713 		return;
714 	}
715 
716 	proc_entry_rundown(de);
717 
718 	WARN(pde_subdir_first(de),
719 	     "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
720 	     __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
721 	pde_put(de);
722 }
723 EXPORT_SYMBOL(remove_proc_entry);
724 
725 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
726 {
727 	struct proc_dir_entry *root = NULL, *de, *next;
728 	const char *fn = name;
729 	unsigned int len;
730 
731 	write_lock(&proc_subdir_lock);
732 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
733 		write_unlock(&proc_subdir_lock);
734 		return -ENOENT;
735 	}
736 	len = strlen(fn);
737 
738 	root = pde_subdir_find(parent, fn, len);
739 	if (!root) {
740 		write_unlock(&proc_subdir_lock);
741 		return -ENOENT;
742 	}
743 	if (unlikely(pde_is_permanent(root))) {
744 		write_unlock(&proc_subdir_lock);
745 		WARN(1, "removing permanent /proc entry '%s/%s'",
746 			root->parent->name, root->name);
747 		return -EINVAL;
748 	}
749 	rb_erase(&root->subdir_node, &parent->subdir);
750 
751 	de = root;
752 	while (1) {
753 		next = pde_subdir_first(de);
754 		if (next) {
755 			if (unlikely(pde_is_permanent(next))) {
756 				write_unlock(&proc_subdir_lock);
757 				WARN(1, "removing permanent /proc entry '%s/%s'",
758 					next->parent->name, next->name);
759 				return -EINVAL;
760 			}
761 			rb_erase(&next->subdir_node, &de->subdir);
762 			de = next;
763 			continue;
764 		}
765 		next = de->parent;
766 		if (S_ISDIR(de->mode))
767 			next->nlink--;
768 		write_unlock(&proc_subdir_lock);
769 
770 		proc_entry_rundown(de);
771 		if (de == root)
772 			break;
773 		pde_put(de);
774 
775 		write_lock(&proc_subdir_lock);
776 		de = next;
777 	}
778 	pde_put(root);
779 	return 0;
780 }
781 EXPORT_SYMBOL(remove_proc_subtree);
782 
783 void *proc_get_parent_data(const struct inode *inode)
784 {
785 	struct proc_dir_entry *de = PDE(inode);
786 	return de->parent->data;
787 }
788 EXPORT_SYMBOL_GPL(proc_get_parent_data);
789 
790 void proc_remove(struct proc_dir_entry *de)
791 {
792 	if (de)
793 		remove_proc_subtree(de->name, de->parent);
794 }
795 EXPORT_SYMBOL(proc_remove);
796 
797 /*
798  * Pull a user buffer into memory and pass it to the file's write handler if
799  * one is supplied.  The ->write() method is permitted to modify the
800  * kernel-side buffer.
801  */
802 ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
803 			  loff_t *_pos)
804 {
805 	struct proc_dir_entry *pde = PDE(file_inode(f));
806 	char *buf;
807 	int ret;
808 
809 	if (!pde->write)
810 		return -EACCES;
811 	if (size == 0 || size > PAGE_SIZE - 1)
812 		return -EINVAL;
813 	buf = memdup_user_nul(ubuf, size);
814 	if (IS_ERR(buf))
815 		return PTR_ERR(buf);
816 	ret = pde->write(f, buf, size);
817 	kfree(buf);
818 	return ret == 0 ? size : ret;
819 }
820