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1/*
2 * proc/fs/generic.c --- generic routines for the proc-fs
3 *
4 * This file contains generic proc-fs routines for handling
5 * directories and files.
6 *
7 * Copyright (C) 1991, 1992 Linus Torvalds.
8 * Copyright (C) 1997 Theodore Ts'o
9 */
10
11#include <linux/errno.h>
12#include <linux/time.h>
13#include <linux/proc_fs.h>
14#include <linux/stat.h>
15#include <linux/mm.h>
16#include <linux/module.h>
17#include <linux/slab.h>
18#include <linux/mount.h>
19#include <linux/init.h>
20#include <linux/idr.h>
21#include <linux/namei.h>
22#include <linux/bitops.h>
23#include <linux/spinlock.h>
24#include <linux/completion.h>
25#include <asm/uaccess.h>
26
27#include "internal.h"
28
29DEFINE_SPINLOCK(proc_subdir_lock);
30
31static int proc_match(unsigned int len, const char *name, struct proc_dir_entry *de)
32{
33 if (de->namelen != len)
34 return 0;
35 return !memcmp(name, de->name, len);
36}
37
38/* buffer size is one page but our output routines use some slack for overruns */
39#define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
40
41static ssize_t
42__proc_file_read(struct file *file, char __user *buf, size_t nbytes,
43 loff_t *ppos)
44{
45 struct inode * inode = file->f_path.dentry->d_inode;
46 char *page;
47 ssize_t retval=0;
48 int eof=0;
49 ssize_t n, count;
50 char *start;
51 struct proc_dir_entry * dp;
52 unsigned long long pos;
53
54 /*
55 * Gaah, please just use "seq_file" instead. The legacy /proc
56 * interfaces cut loff_t down to off_t for reads, and ignore
57 * the offset entirely for writes..
58 */
59 pos = *ppos;
60 if (pos > MAX_NON_LFS)
61 return 0;
62 if (nbytes > MAX_NON_LFS - pos)
63 nbytes = MAX_NON_LFS - pos;
64
65 dp = PDE(inode);
66 if (!(page = (char*) __get_free_page(GFP_TEMPORARY)))
67 return -ENOMEM;
68
69 while ((nbytes > 0) && !eof) {
70 count = min_t(size_t, PROC_BLOCK_SIZE, nbytes);
71
72 start = NULL;
73 if (dp->read_proc) {
74 /*
75 * How to be a proc read function
76 * ------------------------------
77 * Prototype:
78 * int f(char *buffer, char **start, off_t offset,
79 * int count, int *peof, void *dat)
80 *
81 * Assume that the buffer is "count" bytes in size.
82 *
83 * If you know you have supplied all the data you
84 * have, set *peof.
85 *
86 * You have three ways to return data:
87 * 0) Leave *start = NULL. (This is the default.)
88 * Put the data of the requested offset at that
89 * offset within the buffer. Return the number (n)
90 * of bytes there are from the beginning of the
91 * buffer up to the last byte of data. If the
92 * number of supplied bytes (= n - offset) is
93 * greater than zero and you didn't signal eof
94 * and the reader is prepared to take more data
95 * you will be called again with the requested
96 * offset advanced by the number of bytes
97 * absorbed. This interface is useful for files
98 * no larger than the buffer.
99 * 1) Set *start = an unsigned long value less than
100 * the buffer address but greater than zero.
101 * Put the data of the requested offset at the
102 * beginning of the buffer. Return the number of
103 * bytes of data placed there. If this number is
104 * greater than zero and you didn't signal eof
105 * and the reader is prepared to take more data
106 * you will be called again with the requested
107 * offset advanced by *start. This interface is
108 * useful when you have a large file consisting
109 * of a series of blocks which you want to count
110 * and return as wholes.
111 * (Hack by Paul.Russell@rustcorp.com.au)
112 * 2) Set *start = an address within the buffer.
113 * Put the data of the requested offset at *start.
114 * Return the number of bytes of data placed there.
115 * If this number is greater than zero and you
116 * didn't signal eof and the reader is prepared to
117 * take more data you will be called again with the
118 * requested offset advanced by the number of bytes
119 * absorbed.
120 */
121 n = dp->read_proc(page, &start, *ppos,
122 count, &eof, dp->data);
123 } else
124 break;
125
126 if (n == 0) /* end of file */
127 break;
128 if (n < 0) { /* error */
129 if (retval == 0)
130 retval = n;
131 break;
132 }
133
134 if (start == NULL) {
135 if (n > PAGE_SIZE) {
136 printk(KERN_ERR
137 "proc_file_read: Apparent buffer overflow!\n");
138 n = PAGE_SIZE;
139 }
140 n -= *ppos;
141 if (n <= 0)
142 break;
143 if (n > count)
144 n = count;
145 start = page + *ppos;
146 } else if (start < page) {
147 if (n > PAGE_SIZE) {
148 printk(KERN_ERR
149 "proc_file_read: Apparent buffer overflow!\n");
150 n = PAGE_SIZE;
151 }
152 if (n > count) {
153 /*
154 * Don't reduce n because doing so might
155 * cut off part of a data block.
156 */
157 printk(KERN_WARNING
158 "proc_file_read: Read count exceeded\n");
159 }
160 } else /* start >= page */ {
161 unsigned long startoff = (unsigned long)(start - page);
162 if (n > (PAGE_SIZE - startoff)) {
163 printk(KERN_ERR
164 "proc_file_read: Apparent buffer overflow!\n");
165 n = PAGE_SIZE - startoff;
166 }
167 if (n > count)
168 n = count;
169 }
170
171 n -= copy_to_user(buf, start < page ? page : start, n);
172 if (n == 0) {
173 if (retval == 0)
174 retval = -EFAULT;
175 break;
176 }
177
178 *ppos += start < page ? (unsigned long)start : n;
179 nbytes -= n;
180 buf += n;
181 retval += n;
182 }
183 free_page((unsigned long) page);
184 return retval;
185}
186
187static ssize_t
188proc_file_read(struct file *file, char __user *buf, size_t nbytes,
189 loff_t *ppos)
190{
191 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
192 ssize_t rv = -EIO;
193
194 spin_lock(&pde->pde_unload_lock);
195 if (!pde->proc_fops) {
196 spin_unlock(&pde->pde_unload_lock);
197 return rv;
198 }
199 pde->pde_users++;
200 spin_unlock(&pde->pde_unload_lock);
201
202 rv = __proc_file_read(file, buf, nbytes, ppos);
203
204 pde_users_dec(pde);
205 return rv;
206}
207
208static ssize_t
209proc_file_write(struct file *file, const char __user *buffer,
210 size_t count, loff_t *ppos)
211{
212 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
213 ssize_t rv = -EIO;
214
215 if (pde->write_proc) {
216 spin_lock(&pde->pde_unload_lock);
217 if (!pde->proc_fops) {
218 spin_unlock(&pde->pde_unload_lock);
219 return rv;
220 }
221 pde->pde_users++;
222 spin_unlock(&pde->pde_unload_lock);
223
224 /* FIXME: does this routine need ppos? probably... */
225 rv = pde->write_proc(file, buffer, count, pde->data);
226 pde_users_dec(pde);
227 }
228 return rv;
229}
230
231
232static loff_t
233proc_file_lseek(struct file *file, loff_t offset, int orig)
234{
235 loff_t retval = -EINVAL;
236 switch (orig) {
237 case 1:
238 offset += file->f_pos;
239 /* fallthrough */
240 case 0:
241 if (offset < 0 || offset > MAX_NON_LFS)
242 break;
243 file->f_pos = retval = offset;
244 }
245 return retval;
246}
247
248static const struct file_operations proc_file_operations = {
249 .llseek = proc_file_lseek,
250 .read = proc_file_read,
251 .write = proc_file_write,
252};
253
254static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
255{
256 struct inode *inode = dentry->d_inode;
257 struct proc_dir_entry *de = PDE(inode);
258 int error;
259
260 error = inode_change_ok(inode, iattr);
261 if (error)
262 return error;
263
264 if ((iattr->ia_valid & ATTR_SIZE) &&
265 iattr->ia_size != i_size_read(inode)) {
266 error = vmtruncate(inode, iattr->ia_size);
267 if (error)
268 return error;
269 }
270
271 setattr_copy(inode, iattr);
272 mark_inode_dirty(inode);
273
274 de->uid = inode->i_uid;
275 de->gid = inode->i_gid;
276 de->mode = inode->i_mode;
277 return 0;
278}
279
280static int proc_getattr(struct vfsmount *mnt, struct dentry *dentry,
281 struct kstat *stat)
282{
283 struct inode *inode = dentry->d_inode;
284 struct proc_dir_entry *de = PROC_I(inode)->pde;
285 if (de && de->nlink)
286 inode->i_nlink = de->nlink;
287
288 generic_fillattr(inode, stat);
289 return 0;
290}
291
292static const struct inode_operations proc_file_inode_operations = {
293 .setattr = proc_notify_change,
294};
295
296/*
297 * This function parses a name such as "tty/driver/serial", and
298 * returns the struct proc_dir_entry for "/proc/tty/driver", and
299 * returns "serial" in residual.
300 */
301static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
302 const char **residual)
303{
304 const char *cp = name, *next;
305 struct proc_dir_entry *de;
306 unsigned int len;
307
308 de = *ret;
309 if (!de)
310 de = &proc_root;
311
312 while (1) {
313 next = strchr(cp, '/');
314 if (!next)
315 break;
316
317 len = next - cp;
318 for (de = de->subdir; de ; de = de->next) {
319 if (proc_match(len, cp, de))
320 break;
321 }
322 if (!de) {
323 WARN(1, "name '%s'\n", name);
324 return -ENOENT;
325 }
326 cp += len + 1;
327 }
328 *residual = cp;
329 *ret = de;
330 return 0;
331}
332
333static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
334 const char **residual)
335{
336 int rv;
337
338 spin_lock(&proc_subdir_lock);
339 rv = __xlate_proc_name(name, ret, residual);
340 spin_unlock(&proc_subdir_lock);
341 return rv;
342}
343
344static DEFINE_IDA(proc_inum_ida);
345static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
346
347#define PROC_DYNAMIC_FIRST 0xF0000000U
348
349/*
350 * Return an inode number between PROC_DYNAMIC_FIRST and
351 * 0xffffffff, or zero on failure.
352 */
353static unsigned int get_inode_number(void)
354{
355 unsigned int i;
356 int error;
357
358retry:
359 if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
360 return 0;
361
362 spin_lock(&proc_inum_lock);
363 error = ida_get_new(&proc_inum_ida, &i);
364 spin_unlock(&proc_inum_lock);
365 if (error == -EAGAIN)
366 goto retry;
367 else if (error)
368 return 0;
369
370 if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
371 spin_lock(&proc_inum_lock);
372 ida_remove(&proc_inum_ida, i);
373 spin_unlock(&proc_inum_lock);
374 return 0;
375 }
376 return PROC_DYNAMIC_FIRST + i;
377}
378
379static void release_inode_number(unsigned int inum)
380{
381 spin_lock(&proc_inum_lock);
382 ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
383 spin_unlock(&proc_inum_lock);
384}
385
386static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
387{
388 nd_set_link(nd, PDE(dentry->d_inode)->data);
389 return NULL;
390}
391
392static const struct inode_operations proc_link_inode_operations = {
393 .readlink = generic_readlink,
394 .follow_link = proc_follow_link,
395};
396
397/*
398 * As some entries in /proc are volatile, we want to
399 * get rid of unused dentries. This could be made
400 * smarter: we could keep a "volatile" flag in the
401 * inode to indicate which ones to keep.
402 */
403static int proc_delete_dentry(const struct dentry * dentry)
404{
405 return 1;
406}
407
408static const struct dentry_operations proc_dentry_operations =
409{
410 .d_delete = proc_delete_dentry,
411};
412
413/*
414 * Don't create negative dentries here, return -ENOENT by hand
415 * instead.
416 */
417struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
418 struct dentry *dentry)
419{
420 struct inode *inode = NULL;
421 int error = -ENOENT;
422
423 spin_lock(&proc_subdir_lock);
424 for (de = de->subdir; de ; de = de->next) {
425 if (de->namelen != dentry->d_name.len)
426 continue;
427 if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
428 pde_get(de);
429 spin_unlock(&proc_subdir_lock);
430 error = -EINVAL;
431 inode = proc_get_inode(dir->i_sb, de);
432 goto out_unlock;
433 }
434 }
435 spin_unlock(&proc_subdir_lock);
436out_unlock:
437
438 if (inode) {
439 d_set_d_op(dentry, &proc_dentry_operations);
440 d_add(dentry, inode);
441 return NULL;
442 }
443 if (de)
444 pde_put(de);
445 return ERR_PTR(error);
446}
447
448struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
449 struct nameidata *nd)
450{
451 return proc_lookup_de(PDE(dir), dir, dentry);
452}
453
454/*
455 * This returns non-zero if at EOF, so that the /proc
456 * root directory can use this and check if it should
457 * continue with the <pid> entries..
458 *
459 * Note that the VFS-layer doesn't care about the return
460 * value of the readdir() call, as long as it's non-negative
461 * for success..
462 */
463int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
464 filldir_t filldir)
465{
466 unsigned int ino;
467 int i;
468 struct inode *inode = filp->f_path.dentry->d_inode;
469 int ret = 0;
470
471 ino = inode->i_ino;
472 i = filp->f_pos;
473 switch (i) {
474 case 0:
475 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
476 goto out;
477 i++;
478 filp->f_pos++;
479 /* fall through */
480 case 1:
481 if (filldir(dirent, "..", 2, i,
482 parent_ino(filp->f_path.dentry),
483 DT_DIR) < 0)
484 goto out;
485 i++;
486 filp->f_pos++;
487 /* fall through */
488 default:
489 spin_lock(&proc_subdir_lock);
490 de = de->subdir;
491 i -= 2;
492 for (;;) {
493 if (!de) {
494 ret = 1;
495 spin_unlock(&proc_subdir_lock);
496 goto out;
497 }
498 if (!i)
499 break;
500 de = de->next;
501 i--;
502 }
503
504 do {
505 struct proc_dir_entry *next;
506
507 /* filldir passes info to user space */
508 pde_get(de);
509 spin_unlock(&proc_subdir_lock);
510 if (filldir(dirent, de->name, de->namelen, filp->f_pos,
511 de->low_ino, de->mode >> 12) < 0) {
512 pde_put(de);
513 goto out;
514 }
515 spin_lock(&proc_subdir_lock);
516 filp->f_pos++;
517 next = de->next;
518 pde_put(de);
519 de = next;
520 } while (de);
521 spin_unlock(&proc_subdir_lock);
522 }
523 ret = 1;
524out:
525 return ret;
526}
527
528int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
529{
530 struct inode *inode = filp->f_path.dentry->d_inode;
531
532 return proc_readdir_de(PDE(inode), filp, dirent, filldir);
533}
534
535/*
536 * These are the generic /proc directory operations. They
537 * use the in-memory "struct proc_dir_entry" tree to parse
538 * the /proc directory.
539 */
540static const struct file_operations proc_dir_operations = {
541 .llseek = generic_file_llseek,
542 .read = generic_read_dir,
543 .readdir = proc_readdir,
544};
545
546/*
547 * proc directories can do almost nothing..
548 */
549static const struct inode_operations proc_dir_inode_operations = {
550 .lookup = proc_lookup,
551 .getattr = proc_getattr,
552 .setattr = proc_notify_change,
553};
554
555static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
556{
557 unsigned int i;
558 struct proc_dir_entry *tmp;
559
560 i = get_inode_number();
561 if (i == 0)
562 return -EAGAIN;
563 dp->low_ino = i;
564
565 if (S_ISDIR(dp->mode)) {
566 if (dp->proc_iops == NULL) {
567 dp->proc_fops = &proc_dir_operations;
568 dp->proc_iops = &proc_dir_inode_operations;
569 }
570 dir->nlink++;
571 } else if (S_ISLNK(dp->mode)) {
572 if (dp->proc_iops == NULL)
573 dp->proc_iops = &proc_link_inode_operations;
574 } else if (S_ISREG(dp->mode)) {
575 if (dp->proc_fops == NULL)
576 dp->proc_fops = &proc_file_operations;
577 if (dp->proc_iops == NULL)
578 dp->proc_iops = &proc_file_inode_operations;
579 }
580
581 spin_lock(&proc_subdir_lock);
582
583 for (tmp = dir->subdir; tmp; tmp = tmp->next)
584 if (strcmp(tmp->name, dp->name) == 0) {
585 WARN(1, KERN_WARNING "proc_dir_entry '%s/%s' already registered\n",
586 dir->name, dp->name);
587 break;
588 }
589
590 dp->next = dir->subdir;
591 dp->parent = dir;
592 dir->subdir = dp;
593 spin_unlock(&proc_subdir_lock);
594
595 return 0;
596}
597
598static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
599 const char *name,
600 mode_t mode,
601 nlink_t nlink)
602{
603 struct proc_dir_entry *ent = NULL;
604 const char *fn = name;
605 unsigned int len;
606
607 /* make sure name is valid */
608 if (!name || !strlen(name)) goto out;
609
610 if (xlate_proc_name(name, parent, &fn) != 0)
611 goto out;
612
613 /* At this point there must not be any '/' characters beyond *fn */
614 if (strchr(fn, '/'))
615 goto out;
616
617 len = strlen(fn);
618
619 ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
620 if (!ent) goto out;
621
622 memset(ent, 0, sizeof(struct proc_dir_entry));
623 memcpy(ent->name, fn, len + 1);
624 ent->namelen = len;
625 ent->mode = mode;
626 ent->nlink = nlink;
627 atomic_set(&ent->count, 1);
628 ent->pde_users = 0;
629 spin_lock_init(&ent->pde_unload_lock);
630 ent->pde_unload_completion = NULL;
631 INIT_LIST_HEAD(&ent->pde_openers);
632 out:
633 return ent;
634}
635
636struct proc_dir_entry *proc_symlink(const char *name,
637 struct proc_dir_entry *parent, const char *dest)
638{
639 struct proc_dir_entry *ent;
640
641 ent = __proc_create(&parent, name,
642 (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
643
644 if (ent) {
645 ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
646 if (ent->data) {
647 strcpy((char*)ent->data,dest);
648 if (proc_register(parent, ent) < 0) {
649 kfree(ent->data);
650 kfree(ent);
651 ent = NULL;
652 }
653 } else {
654 kfree(ent);
655 ent = NULL;
656 }
657 }
658 return ent;
659}
660EXPORT_SYMBOL(proc_symlink);
661
662struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
663 struct proc_dir_entry *parent)
664{
665 struct proc_dir_entry *ent;
666
667 ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
668 if (ent) {
669 if (proc_register(parent, ent) < 0) {
670 kfree(ent);
671 ent = NULL;
672 }
673 }
674 return ent;
675}
676EXPORT_SYMBOL(proc_mkdir_mode);
677
678struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
679 struct proc_dir_entry *parent)
680{
681 struct proc_dir_entry *ent;
682
683 ent = __proc_create(&parent, name, S_IFDIR | S_IRUGO | S_IXUGO, 2);
684 if (ent) {
685 ent->data = net;
686 if (proc_register(parent, ent) < 0) {
687 kfree(ent);
688 ent = NULL;
689 }
690 }
691 return ent;
692}
693EXPORT_SYMBOL_GPL(proc_net_mkdir);
694
695struct proc_dir_entry *proc_mkdir(const char *name,
696 struct proc_dir_entry *parent)
697{
698 return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
699}
700EXPORT_SYMBOL(proc_mkdir);
701
702struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
703 struct proc_dir_entry *parent)
704{
705 struct proc_dir_entry *ent;
706 nlink_t nlink;
707
708 if (S_ISDIR(mode)) {
709 if ((mode & S_IALLUGO) == 0)
710 mode |= S_IRUGO | S_IXUGO;
711 nlink = 2;
712 } else {
713 if ((mode & S_IFMT) == 0)
714 mode |= S_IFREG;
715 if ((mode & S_IALLUGO) == 0)
716 mode |= S_IRUGO;
717 nlink = 1;
718 }
719
720 ent = __proc_create(&parent, name, mode, nlink);
721 if (ent) {
722 if (proc_register(parent, ent) < 0) {
723 kfree(ent);
724 ent = NULL;
725 }
726 }
727 return ent;
728}
729EXPORT_SYMBOL(create_proc_entry);
730
731struct proc_dir_entry *proc_create_data(const char *name, mode_t mode,
732 struct proc_dir_entry *parent,
733 const struct file_operations *proc_fops,
734 void *data)
735{
736 struct proc_dir_entry *pde;
737 nlink_t nlink;
738
739 if (S_ISDIR(mode)) {
740 if ((mode & S_IALLUGO) == 0)
741 mode |= S_IRUGO | S_IXUGO;
742 nlink = 2;
743 } else {
744 if ((mode & S_IFMT) == 0)
745 mode |= S_IFREG;
746 if ((mode & S_IALLUGO) == 0)
747 mode |= S_IRUGO;
748 nlink = 1;
749 }
750
751 pde = __proc_create(&parent, name, mode, nlink);
752 if (!pde)
753 goto out;
754 pde->proc_fops = proc_fops;
755 pde->data = data;
756 if (proc_register(parent, pde) < 0)
757 goto out_free;
758 return pde;
759out_free:
760 kfree(pde);
761out:
762 return NULL;
763}
764EXPORT_SYMBOL(proc_create_data);
765
766static void free_proc_entry(struct proc_dir_entry *de)
767{
768 release_inode_number(de->low_ino);
769
770 if (S_ISLNK(de->mode))
771 kfree(de->data);
772 kfree(de);
773}
774
775void pde_put(struct proc_dir_entry *pde)
776{
777 if (atomic_dec_and_test(&pde->count))
778 free_proc_entry(pde);
779}
780
781/*
782 * Remove a /proc entry and free it if it's not currently in use.
783 */
784void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
785{
786 struct proc_dir_entry **p;
787 struct proc_dir_entry *de = NULL;
788 const char *fn = name;
789 unsigned int len;
790
791 spin_lock(&proc_subdir_lock);
792 if (__xlate_proc_name(name, &parent, &fn) != 0) {
793 spin_unlock(&proc_subdir_lock);
794 return;
795 }
796 len = strlen(fn);
797
798 for (p = &parent->subdir; *p; p=&(*p)->next ) {
799 if (proc_match(len, fn, *p)) {
800 de = *p;
801 *p = de->next;
802 de->next = NULL;
803 break;
804 }
805 }
806 spin_unlock(&proc_subdir_lock);
807 if (!de) {
808 WARN(1, "name '%s'\n", name);
809 return;
810 }
811
812 spin_lock(&de->pde_unload_lock);
813 /*
814 * Stop accepting new callers into module. If you're
815 * dynamically allocating ->proc_fops, save a pointer somewhere.
816 */
817 de->proc_fops = NULL;
818 /* Wait until all existing callers into module are done. */
819 if (de->pde_users > 0) {
820 DECLARE_COMPLETION_ONSTACK(c);
821
822 if (!de->pde_unload_completion)
823 de->pde_unload_completion = &c;
824
825 spin_unlock(&de->pde_unload_lock);
826
827 wait_for_completion(de->pde_unload_completion);
828
829 spin_lock(&de->pde_unload_lock);
830 }
831
832 while (!list_empty(&de->pde_openers)) {
833 struct pde_opener *pdeo;
834
835 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
836 list_del(&pdeo->lh);
837 spin_unlock(&de->pde_unload_lock);
838 pdeo->release(pdeo->inode, pdeo->file);
839 kfree(pdeo);
840 spin_lock(&de->pde_unload_lock);
841 }
842 spin_unlock(&de->pde_unload_lock);
843
844 if (S_ISDIR(de->mode))
845 parent->nlink--;
846 de->nlink = 0;
847 WARN(de->subdir, KERN_WARNING "%s: removing non-empty directory "
848 "'%s/%s', leaking at least '%s'\n", __func__,
849 de->parent->name, de->name, de->subdir->name);
850 pde_put(de);
851}
852EXPORT_SYMBOL(remove_proc_entry);
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 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
136static 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 && de->nlink)
142 set_nlink(inode, de->nlink);
143
144 generic_fillattr(inode, stat);
145 return 0;
146}
147
148static const struct inode_operations proc_file_inode_operations = {
149 .setattr = proc_notify_change,
150};
151
152/*
153 * This function parses a name such as "tty/driver/serial", and
154 * returns the struct proc_dir_entry for "/proc/tty/driver", and
155 * returns "serial" in residual.
156 */
157static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
158 const char **residual)
159{
160 const char *cp = name, *next;
161 struct proc_dir_entry *de;
162 unsigned int len;
163
164 de = *ret;
165 if (!de)
166 de = &proc_root;
167
168 while (1) {
169 next = strchr(cp, '/');
170 if (!next)
171 break;
172
173 len = next - cp;
174 de = pde_subdir_find(de, cp, len);
175 if (!de) {
176 WARN(1, "name '%s'\n", name);
177 return -ENOENT;
178 }
179 cp += len + 1;
180 }
181 *residual = cp;
182 *ret = de;
183 return 0;
184}
185
186static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
187 const char **residual)
188{
189 int rv;
190
191 read_lock(&proc_subdir_lock);
192 rv = __xlate_proc_name(name, ret, residual);
193 read_unlock(&proc_subdir_lock);
194 return rv;
195}
196
197static DEFINE_IDA(proc_inum_ida);
198
199#define PROC_DYNAMIC_FIRST 0xF0000000U
200
201/*
202 * Return an inode number between PROC_DYNAMIC_FIRST and
203 * 0xffffffff, or zero on failure.
204 */
205int proc_alloc_inum(unsigned int *inum)
206{
207 int i;
208
209 i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
210 GFP_KERNEL);
211 if (i < 0)
212 return i;
213
214 *inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
215 return 0;
216}
217
218void proc_free_inum(unsigned int inum)
219{
220 ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
221}
222
223static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
224{
225 if (flags & LOOKUP_RCU)
226 return -ECHILD;
227
228 if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
229 return 0; /* revalidate */
230 return 1;
231}
232
233static int proc_misc_d_delete(const struct dentry *dentry)
234{
235 return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
236}
237
238static const struct dentry_operations proc_misc_dentry_ops = {
239 .d_revalidate = proc_misc_d_revalidate,
240 .d_delete = proc_misc_d_delete,
241};
242
243/*
244 * Don't create negative dentries here, return -ENOENT by hand
245 * instead.
246 */
247struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
248 struct proc_dir_entry *de)
249{
250 struct inode *inode;
251
252 read_lock(&proc_subdir_lock);
253 de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
254 if (de) {
255 pde_get(de);
256 read_unlock(&proc_subdir_lock);
257 inode = proc_get_inode(dir->i_sb, de);
258 if (!inode)
259 return ERR_PTR(-ENOMEM);
260 d_set_d_op(dentry, de->proc_dops);
261 return d_splice_alias(inode, dentry);
262 }
263 read_unlock(&proc_subdir_lock);
264 return ERR_PTR(-ENOENT);
265}
266
267struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
268 unsigned int flags)
269{
270 return proc_lookup_de(dir, dentry, PDE(dir));
271}
272
273/*
274 * This returns non-zero if at EOF, so that the /proc
275 * root directory can use this and check if it should
276 * continue with the <pid> entries..
277 *
278 * Note that the VFS-layer doesn't care about the return
279 * value of the readdir() call, as long as it's non-negative
280 * for success..
281 */
282int proc_readdir_de(struct file *file, struct dir_context *ctx,
283 struct proc_dir_entry *de)
284{
285 int i;
286
287 if (!dir_emit_dots(file, ctx))
288 return 0;
289
290 i = ctx->pos - 2;
291 read_lock(&proc_subdir_lock);
292 de = pde_subdir_first(de);
293 for (;;) {
294 if (!de) {
295 read_unlock(&proc_subdir_lock);
296 return 0;
297 }
298 if (!i)
299 break;
300 de = pde_subdir_next(de);
301 i--;
302 }
303
304 do {
305 struct proc_dir_entry *next;
306 pde_get(de);
307 read_unlock(&proc_subdir_lock);
308 if (!dir_emit(ctx, de->name, de->namelen,
309 de->low_ino, de->mode >> 12)) {
310 pde_put(de);
311 return 0;
312 }
313 ctx->pos++;
314 read_lock(&proc_subdir_lock);
315 next = pde_subdir_next(de);
316 pde_put(de);
317 de = next;
318 } while (de);
319 read_unlock(&proc_subdir_lock);
320 return 1;
321}
322
323int proc_readdir(struct file *file, struct dir_context *ctx)
324{
325 struct inode *inode = file_inode(file);
326
327 return proc_readdir_de(file, ctx, PDE(inode));
328}
329
330/*
331 * These are the generic /proc directory operations. They
332 * use the in-memory "struct proc_dir_entry" tree to parse
333 * the /proc directory.
334 */
335static const struct file_operations proc_dir_operations = {
336 .llseek = generic_file_llseek,
337 .read = generic_read_dir,
338 .iterate_shared = proc_readdir,
339};
340
341/*
342 * proc directories can do almost nothing..
343 */
344static const struct inode_operations proc_dir_inode_operations = {
345 .lookup = proc_lookup,
346 .getattr = proc_getattr,
347 .setattr = proc_notify_change,
348};
349
350/* returns the registered entry, or frees dp and returns NULL on failure */
351struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
352 struct proc_dir_entry *dp)
353{
354 if (proc_alloc_inum(&dp->low_ino))
355 goto out_free_entry;
356
357 write_lock(&proc_subdir_lock);
358 dp->parent = dir;
359 if (pde_subdir_insert(dir, dp) == false) {
360 WARN(1, "proc_dir_entry '%s/%s' already registered\n",
361 dir->name, dp->name);
362 write_unlock(&proc_subdir_lock);
363 goto out_free_inum;
364 }
365 write_unlock(&proc_subdir_lock);
366
367 return dp;
368out_free_inum:
369 proc_free_inum(dp->low_ino);
370out_free_entry:
371 pde_free(dp);
372 return NULL;
373}
374
375static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
376 const char *name,
377 umode_t mode,
378 nlink_t nlink)
379{
380 struct proc_dir_entry *ent = NULL;
381 const char *fn;
382 struct qstr qstr;
383
384 if (xlate_proc_name(name, parent, &fn) != 0)
385 goto out;
386 qstr.name = fn;
387 qstr.len = strlen(fn);
388 if (qstr.len == 0 || qstr.len >= 256) {
389 WARN(1, "name len %u\n", qstr.len);
390 return NULL;
391 }
392 if (qstr.len == 1 && fn[0] == '.') {
393 WARN(1, "name '.'\n");
394 return NULL;
395 }
396 if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
397 WARN(1, "name '..'\n");
398 return NULL;
399 }
400 if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
401 WARN(1, "create '/proc/%s' by hand\n", qstr.name);
402 return NULL;
403 }
404 if (is_empty_pde(*parent)) {
405 WARN(1, "attempt to add to permanently empty directory");
406 return NULL;
407 }
408
409 ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
410 if (!ent)
411 goto out;
412
413 if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
414 ent->name = ent->inline_name;
415 } else {
416 ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
417 if (!ent->name) {
418 pde_free(ent);
419 return NULL;
420 }
421 }
422
423 memcpy(ent->name, fn, qstr.len + 1);
424 ent->namelen = qstr.len;
425 ent->mode = mode;
426 ent->nlink = nlink;
427 ent->subdir = RB_ROOT;
428 refcount_set(&ent->refcnt, 1);
429 spin_lock_init(&ent->pde_unload_lock);
430 INIT_LIST_HEAD(&ent->pde_openers);
431 proc_set_user(ent, (*parent)->uid, (*parent)->gid);
432
433 ent->proc_dops = &proc_misc_dentry_ops;
434
435out:
436 return ent;
437}
438
439struct proc_dir_entry *proc_symlink(const char *name,
440 struct proc_dir_entry *parent, const char *dest)
441{
442 struct proc_dir_entry *ent;
443
444 ent = __proc_create(&parent, name,
445 (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
446
447 if (ent) {
448 ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
449 if (ent->data) {
450 strcpy((char*)ent->data,dest);
451 ent->proc_iops = &proc_link_inode_operations;
452 ent = proc_register(parent, ent);
453 } else {
454 pde_free(ent);
455 ent = NULL;
456 }
457 }
458 return ent;
459}
460EXPORT_SYMBOL(proc_symlink);
461
462struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
463 struct proc_dir_entry *parent, void *data)
464{
465 struct proc_dir_entry *ent;
466
467 if (mode == 0)
468 mode = S_IRUGO | S_IXUGO;
469
470 ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
471 if (ent) {
472 ent->data = data;
473 ent->proc_fops = &proc_dir_operations;
474 ent->proc_iops = &proc_dir_inode_operations;
475 parent->nlink++;
476 ent = proc_register(parent, ent);
477 if (!ent)
478 parent->nlink--;
479 }
480 return ent;
481}
482EXPORT_SYMBOL_GPL(proc_mkdir_data);
483
484struct 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}
489EXPORT_SYMBOL(proc_mkdir_mode);
490
491struct 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}
496EXPORT_SYMBOL(proc_mkdir);
497
498struct 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 parent->nlink++;
509 ent = proc_register(parent, ent);
510 if (!ent)
511 parent->nlink--;
512 }
513 return ent;
514}
515EXPORT_SYMBOL(proc_create_mount_point);
516
517struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
518 struct proc_dir_entry **parent, void *data)
519{
520 struct proc_dir_entry *p;
521
522 if ((mode & S_IFMT) == 0)
523 mode |= S_IFREG;
524 if ((mode & S_IALLUGO) == 0)
525 mode |= S_IRUGO;
526 if (WARN_ON_ONCE(!S_ISREG(mode)))
527 return NULL;
528
529 p = __proc_create(parent, name, mode, 1);
530 if (p) {
531 p->proc_iops = &proc_file_inode_operations;
532 p->data = data;
533 }
534 return p;
535}
536
537struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
538 struct proc_dir_entry *parent,
539 const struct file_operations *proc_fops, void *data)
540{
541 struct proc_dir_entry *p;
542
543 BUG_ON(proc_fops == NULL);
544
545 p = proc_create_reg(name, mode, &parent, data);
546 if (!p)
547 return NULL;
548 p->proc_fops = proc_fops;
549 return proc_register(parent, p);
550}
551EXPORT_SYMBOL(proc_create_data);
552
553struct proc_dir_entry *proc_create(const char *name, umode_t mode,
554 struct proc_dir_entry *parent,
555 const struct file_operations *proc_fops)
556{
557 return proc_create_data(name, mode, parent, proc_fops, NULL);
558}
559EXPORT_SYMBOL(proc_create);
560
561static int proc_seq_open(struct inode *inode, struct file *file)
562{
563 struct proc_dir_entry *de = PDE(inode);
564
565 if (de->state_size)
566 return seq_open_private(file, de->seq_ops, de->state_size);
567 return seq_open(file, de->seq_ops);
568}
569
570static int proc_seq_release(struct inode *inode, struct file *file)
571{
572 struct proc_dir_entry *de = PDE(inode);
573
574 if (de->state_size)
575 return seq_release_private(inode, file);
576 return seq_release(inode, file);
577}
578
579static const struct file_operations proc_seq_fops = {
580 .open = proc_seq_open,
581 .read = seq_read,
582 .llseek = seq_lseek,
583 .release = proc_seq_release,
584};
585
586struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
587 struct proc_dir_entry *parent, const struct seq_operations *ops,
588 unsigned int state_size, void *data)
589{
590 struct proc_dir_entry *p;
591
592 p = proc_create_reg(name, mode, &parent, data);
593 if (!p)
594 return NULL;
595 p->proc_fops = &proc_seq_fops;
596 p->seq_ops = ops;
597 p->state_size = state_size;
598 return proc_register(parent, p);
599}
600EXPORT_SYMBOL(proc_create_seq_private);
601
602static int proc_single_open(struct inode *inode, struct file *file)
603{
604 struct proc_dir_entry *de = PDE(inode);
605
606 return single_open(file, de->single_show, de->data);
607}
608
609static const struct file_operations proc_single_fops = {
610 .open = proc_single_open,
611 .read = seq_read,
612 .llseek = seq_lseek,
613 .release = single_release,
614};
615
616struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
617 struct proc_dir_entry *parent,
618 int (*show)(struct seq_file *, void *), 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_fops = &proc_single_fops;
626 p->single_show = show;
627 return proc_register(parent, p);
628}
629EXPORT_SYMBOL(proc_create_single_data);
630
631void proc_set_size(struct proc_dir_entry *de, loff_t size)
632{
633 de->size = size;
634}
635EXPORT_SYMBOL(proc_set_size);
636
637void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
638{
639 de->uid = uid;
640 de->gid = gid;
641}
642EXPORT_SYMBOL(proc_set_user);
643
644void pde_put(struct proc_dir_entry *pde)
645{
646 if (refcount_dec_and_test(&pde->refcnt)) {
647 proc_free_inum(pde->low_ino);
648 pde_free(pde);
649 }
650}
651
652/*
653 * Remove a /proc entry and free it if it's not currently in use.
654 */
655void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
656{
657 struct proc_dir_entry *de = NULL;
658 const char *fn = name;
659 unsigned int len;
660
661 write_lock(&proc_subdir_lock);
662 if (__xlate_proc_name(name, &parent, &fn) != 0) {
663 write_unlock(&proc_subdir_lock);
664 return;
665 }
666 len = strlen(fn);
667
668 de = pde_subdir_find(parent, fn, len);
669 if (de)
670 rb_erase(&de->subdir_node, &parent->subdir);
671 write_unlock(&proc_subdir_lock);
672 if (!de) {
673 WARN(1, "name '%s'\n", name);
674 return;
675 }
676
677 proc_entry_rundown(de);
678
679 if (S_ISDIR(de->mode))
680 parent->nlink--;
681 de->nlink = 0;
682 WARN(pde_subdir_first(de),
683 "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
684 __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
685 pde_put(de);
686}
687EXPORT_SYMBOL(remove_proc_entry);
688
689int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
690{
691 struct proc_dir_entry *root = NULL, *de, *next;
692 const char *fn = name;
693 unsigned int len;
694
695 write_lock(&proc_subdir_lock);
696 if (__xlate_proc_name(name, &parent, &fn) != 0) {
697 write_unlock(&proc_subdir_lock);
698 return -ENOENT;
699 }
700 len = strlen(fn);
701
702 root = pde_subdir_find(parent, fn, len);
703 if (!root) {
704 write_unlock(&proc_subdir_lock);
705 return -ENOENT;
706 }
707 rb_erase(&root->subdir_node, &parent->subdir);
708
709 de = root;
710 while (1) {
711 next = pde_subdir_first(de);
712 if (next) {
713 rb_erase(&next->subdir_node, &de->subdir);
714 de = next;
715 continue;
716 }
717 write_unlock(&proc_subdir_lock);
718
719 proc_entry_rundown(de);
720 next = de->parent;
721 if (S_ISDIR(de->mode))
722 next->nlink--;
723 de->nlink = 0;
724 if (de == root)
725 break;
726 pde_put(de);
727
728 write_lock(&proc_subdir_lock);
729 de = next;
730 }
731 pde_put(root);
732 return 0;
733}
734EXPORT_SYMBOL(remove_proc_subtree);
735
736void *proc_get_parent_data(const struct inode *inode)
737{
738 struct proc_dir_entry *de = PDE(inode);
739 return de->parent->data;
740}
741EXPORT_SYMBOL_GPL(proc_get_parent_data);
742
743void proc_remove(struct proc_dir_entry *de)
744{
745 if (de)
746 remove_proc_subtree(de->name, de->parent);
747}
748EXPORT_SYMBOL(proc_remove);
749
750void *PDE_DATA(const struct inode *inode)
751{
752 return __PDE_DATA(inode);
753}
754EXPORT_SYMBOL(PDE_DATA);
755
756/*
757 * Pull a user buffer into memory and pass it to the file's write handler if
758 * one is supplied. The ->write() method is permitted to modify the
759 * kernel-side buffer.
760 */
761ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
762 loff_t *_pos)
763{
764 struct proc_dir_entry *pde = PDE(file_inode(f));
765 char *buf;
766 int ret;
767
768 if (!pde->write)
769 return -EACCES;
770 if (size == 0 || size > PAGE_SIZE - 1)
771 return -EINVAL;
772 buf = memdup_user_nul(ubuf, size);
773 if (IS_ERR(buf))
774 return PTR_ERR(buf);
775 ret = pde->write(f, buf, size);
776 kfree(buf);
777 return ret == 0 ? size : ret;
778}