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
33static DEFINE_RWLOCK(proc_subdir_lock);
34
35struct kmem_cache *proc_dir_entry_cache __ro_after_init;
36
37void 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
46static 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
56static 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
62static 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
68static 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
90static 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
118static 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
136static 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
153static 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 */
162static 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
182static 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
193static 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 */
201int proc_alloc_inum(unsigned int *inum)
202{
203	int i;
204
205	i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
206			   GFP_KERNEL);
207	if (i < 0)
208		return i;
209
210	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
211	return 0;
212}
213
214void proc_free_inum(unsigned int inum)
215{
216	ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
217}
218
219static 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
229static int proc_misc_d_delete(const struct dentry *dentry)
230{
231	return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
232}
233
234static 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 */
243struct 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
263struct 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 */
283int 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
324int 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 */
340static const struct file_operations proc_dir_operations = {
341	.llseek			= generic_file_llseek,
342	.read			= generic_read_dir,
343	.iterate_shared		= proc_readdir,
344};
345
346static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
347{
348	return 0;
349}
350
351const 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 */
359static 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 */
366struct 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;
384out_free_inum:
385	proc_free_inum(dp->low_ino);
386out_free_entry:
387	pde_free(dp);
388	return NULL;
389}
390
391static 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
454out:
455	return ent;
456}
457
458struct 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->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
468		if (ent->data) {
469			strcpy((char*)ent->data,dest);
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}
479EXPORT_SYMBOL(proc_symlink);
480
481struct 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}
501EXPORT_SYMBOL_GPL(_proc_mkdir);
502
503struct 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}
508EXPORT_SYMBOL_GPL(proc_mkdir_data);
509
510struct 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}
515EXPORT_SYMBOL(proc_mkdir_mode);
516
517struct 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}
522EXPORT_SYMBOL(proc_mkdir);
523
524struct 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}
538EXPORT_SYMBOL(proc_create_mount_point);
539
540struct 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
560static 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
566struct 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}
579EXPORT_SYMBOL(proc_create_data);
580
581struct 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}
587EXPORT_SYMBOL(proc_create);
588
589static 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
598static 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
607static 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
615struct 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}
629EXPORT_SYMBOL(proc_create_seq_private);
630
631static 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
638static 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
646struct 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}
659EXPORT_SYMBOL(proc_create_single_data);
660
661void proc_set_size(struct proc_dir_entry *de, loff_t size)
662{
663	de->size = size;
664}
665EXPORT_SYMBOL(proc_set_size);
666
667void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
668{
669	de->uid = uid;
670	de->gid = gid;
671}
672EXPORT_SYMBOL(proc_set_user);
673
674void 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 */
685void 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}
722EXPORT_SYMBOL(remove_proc_entry);
723
724int 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}
780EXPORT_SYMBOL(remove_proc_subtree);
781
782void *proc_get_parent_data(const struct inode *inode)
783{
784	struct proc_dir_entry *de = PDE(inode);
785	return de->parent->data;
786}
787EXPORT_SYMBOL_GPL(proc_get_parent_data);
788
789void proc_remove(struct proc_dir_entry *de)
790{
791	if (de)
792		remove_proc_subtree(de->name, de->parent);
793}
794EXPORT_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 */
801ssize_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