1 // SPDX-License-Identifier: GPL-2.0-only
3 * proc/fs/generic.c --- generic routines for the proc-fs
5 * This file contains generic proc-fs routines for handling
6 * directories and files.
8 * Copyright (C) 1991, 1992 Linus Torvalds.
9 * Copyright (C) 1997 Theodore Ts'o
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>
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>
33 static DEFINE_RWLOCK(proc_subdir_lock);
35 struct kmem_cache *proc_dir_entry_cache __ro_after_init;
37 void pde_free(struct proc_dir_entry *pde)
39 if (S_ISLNK(pde->mode))
41 if (pde->name != pde->inline_name)
43 kmem_cache_free(proc_dir_entry_cache, pde);
46 static int proc_match(const char *name, struct proc_dir_entry *de, unsigned int len)
48 if (len < de->namelen)
50 if (len > de->namelen)
53 return memcmp(name, de->name, len);
56 static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir)
58 return rb_entry_safe(rb_first(&dir->subdir), struct proc_dir_entry,
62 static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir)
64 return rb_entry_safe(rb_next(&dir->subdir_node), struct proc_dir_entry,
68 static struct proc_dir_entry *pde_subdir_find(struct proc_dir_entry *dir,
72 struct rb_node *node = dir->subdir.rb_node;
75 struct proc_dir_entry *de = rb_entry(node,
76 struct proc_dir_entry,
78 int result = proc_match(name, de, len);
83 node = node->rb_right;
90 static bool pde_subdir_insert(struct proc_dir_entry *dir,
91 struct proc_dir_entry *de)
93 struct rb_root *root = &dir->subdir;
94 struct rb_node **new = &root->rb_node, *parent = NULL;
96 /* Figure out where to put new node */
98 struct proc_dir_entry *this = rb_entry(*new,
99 struct proc_dir_entry,
101 int result = proc_match(de->name, this, de->namelen);
105 new = &(*new)->rb_left;
107 new = &(*new)->rb_right;
112 /* Add new node and rebalance tree. */
113 rb_link_node(&de->subdir_node, parent, new);
114 rb_insert_color(&de->subdir_node, root);
118 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
120 struct inode *inode = d_inode(dentry);
121 struct proc_dir_entry *de = PDE(inode);
124 error = setattr_prepare(dentry, iattr);
128 setattr_copy(inode, iattr);
129 mark_inode_dirty(inode);
131 proc_set_user(de, inode->i_uid, inode->i_gid);
132 de->mode = inode->i_mode;
136 static int proc_getattr(const struct path *path, struct kstat *stat,
137 u32 request_mask, unsigned int query_flags)
139 struct inode *inode = d_inode(path->dentry);
140 struct proc_dir_entry *de = PDE(inode);
142 nlink_t nlink = READ_ONCE(de->nlink);
144 set_nlink(inode, nlink);
148 generic_fillattr(inode, stat);
152 static const struct inode_operations proc_file_inode_operations = {
153 .setattr = proc_notify_change,
157 * This function parses a name such as "tty/driver/serial", and
158 * returns the struct proc_dir_entry for "/proc/tty/driver", and
159 * returns "serial" in residual.
161 static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
162 const char **residual)
164 const char *cp = name, *next;
165 struct proc_dir_entry *de;
172 next = strchr(cp, '/');
176 de = pde_subdir_find(de, cp, next - cp);
178 WARN(1, "name '%s'\n", name);
188 static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
189 const char **residual)
193 read_lock(&proc_subdir_lock);
194 rv = __xlate_proc_name(name, ret, residual);
195 read_unlock(&proc_subdir_lock);
199 static DEFINE_IDA(proc_inum_ida);
201 #define PROC_DYNAMIC_FIRST 0xF0000000U
204 * Return an inode number between PROC_DYNAMIC_FIRST and
205 * 0xffffffff, or zero on failure.
207 int proc_alloc_inum(unsigned int *inum)
211 i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
216 *inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
220 void proc_free_inum(unsigned int inum)
222 ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
225 static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
227 if (flags & LOOKUP_RCU)
230 if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
231 return 0; /* revalidate */
235 static int proc_misc_d_delete(const struct dentry *dentry)
237 return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
240 static const struct dentry_operations proc_misc_dentry_ops = {
241 .d_revalidate = proc_misc_d_revalidate,
242 .d_delete = proc_misc_d_delete,
246 * Don't create negative dentries here, return -ENOENT by hand
249 struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
250 struct proc_dir_entry *de)
254 read_lock(&proc_subdir_lock);
255 de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len);
258 read_unlock(&proc_subdir_lock);
259 inode = proc_get_inode(dir->i_sb, de);
261 return ERR_PTR(-ENOMEM);
262 d_set_d_op(dentry, de->proc_dops);
263 return d_splice_alias(inode, dentry);
265 read_unlock(&proc_subdir_lock);
266 return ERR_PTR(-ENOENT);
269 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
272 return proc_lookup_de(dir, dentry, PDE(dir));
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..
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
284 int proc_readdir_de(struct file *file, struct dir_context *ctx,
285 struct proc_dir_entry *de)
289 if (!dir_emit_dots(file, ctx))
293 read_lock(&proc_subdir_lock);
294 de = pde_subdir_first(de);
297 read_unlock(&proc_subdir_lock);
302 de = pde_subdir_next(de);
307 struct proc_dir_entry *next;
309 read_unlock(&proc_subdir_lock);
310 if (!dir_emit(ctx, de->name, de->namelen,
311 de->low_ino, de->mode >> 12)) {
316 read_lock(&proc_subdir_lock);
317 next = pde_subdir_next(de);
321 read_unlock(&proc_subdir_lock);
325 int proc_readdir(struct file *file, struct dir_context *ctx)
327 struct inode *inode = file_inode(file);
329 return proc_readdir_de(file, ctx, PDE(inode));
333 * These are the generic /proc directory operations. They
334 * use the in-memory "struct proc_dir_entry" tree to parse
335 * the /proc directory.
337 static const struct file_operations proc_dir_operations = {
338 .llseek = generic_file_llseek,
339 .read = generic_read_dir,
340 .iterate_shared = proc_readdir,
344 * proc directories can do almost nothing..
346 static const struct inode_operations proc_dir_inode_operations = {
347 .lookup = proc_lookup,
348 .getattr = proc_getattr,
349 .setattr = proc_notify_change,
352 /* returns the registered entry, or frees dp and returns NULL on failure */
353 struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
354 struct proc_dir_entry *dp)
356 if (proc_alloc_inum(&dp->low_ino))
359 write_lock(&proc_subdir_lock);
361 if (pde_subdir_insert(dir, dp) == false) {
362 WARN(1, "proc_dir_entry '%s/%s' already registered\n",
363 dir->name, dp->name);
364 write_unlock(&proc_subdir_lock);
368 write_unlock(&proc_subdir_lock);
372 proc_free_inum(dp->low_ino);
378 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
383 struct proc_dir_entry *ent = NULL;
387 if (xlate_proc_name(name, parent, &fn) != 0)
390 qstr.len = strlen(fn);
391 if (qstr.len == 0 || qstr.len >= 256) {
392 WARN(1, "name len %u\n", qstr.len);
395 if (qstr.len == 1 && fn[0] == '.') {
396 WARN(1, "name '.'\n");
399 if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
400 WARN(1, "name '..'\n");
403 if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
404 WARN(1, "create '/proc/%s' by hand\n", qstr.name);
407 if (is_empty_pde(*parent)) {
408 WARN(1, "attempt to add to permanently empty directory");
412 ent = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
416 if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
417 ent->name = ent->inline_name;
419 ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
426 memcpy(ent->name, fn, qstr.len + 1);
427 ent->namelen = qstr.len;
430 ent->subdir = RB_ROOT;
431 refcount_set(&ent->refcnt, 1);
432 spin_lock_init(&ent->pde_unload_lock);
433 INIT_LIST_HEAD(&ent->pde_openers);
434 proc_set_user(ent, (*parent)->uid, (*parent)->gid);
436 ent->proc_dops = &proc_misc_dentry_ops;
442 struct proc_dir_entry *proc_symlink(const char *name,
443 struct proc_dir_entry *parent, const char *dest)
445 struct proc_dir_entry *ent;
447 ent = __proc_create(&parent, name,
448 (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
451 ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
453 strcpy((char*)ent->data,dest);
454 ent->proc_iops = &proc_link_inode_operations;
455 ent = proc_register(parent, ent);
463 EXPORT_SYMBOL(proc_symlink);
465 struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
466 struct proc_dir_entry *parent, void *data)
468 struct proc_dir_entry *ent;
471 mode = S_IRUGO | S_IXUGO;
473 ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
476 ent->proc_fops = &proc_dir_operations;
477 ent->proc_iops = &proc_dir_inode_operations;
478 ent = proc_register(parent, ent);
482 EXPORT_SYMBOL_GPL(proc_mkdir_data);
484 struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
485 struct proc_dir_entry *parent)
487 return proc_mkdir_data(name, mode, parent, NULL);
489 EXPORT_SYMBOL(proc_mkdir_mode);
491 struct proc_dir_entry *proc_mkdir(const char *name,
492 struct proc_dir_entry *parent)
494 return proc_mkdir_data(name, 0, parent, NULL);
496 EXPORT_SYMBOL(proc_mkdir);
498 struct proc_dir_entry *proc_create_mount_point(const char *name)
500 umode_t mode = S_IFDIR | S_IRUGO | S_IXUGO;
501 struct proc_dir_entry *ent, *parent = NULL;
503 ent = __proc_create(&parent, name, mode, 2);
506 ent->proc_fops = NULL;
507 ent->proc_iops = NULL;
508 ent = proc_register(parent, ent);
512 EXPORT_SYMBOL(proc_create_mount_point);
514 struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,
515 struct proc_dir_entry **parent, void *data)
517 struct proc_dir_entry *p;
519 if ((mode & S_IFMT) == 0)
521 if ((mode & S_IALLUGO) == 0)
523 if (WARN_ON_ONCE(!S_ISREG(mode)))
526 p = __proc_create(parent, name, mode, 1);
528 p->proc_iops = &proc_file_inode_operations;
534 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
535 struct proc_dir_entry *parent,
536 const struct file_operations *proc_fops, void *data)
538 struct proc_dir_entry *p;
540 BUG_ON(proc_fops == NULL);
542 p = proc_create_reg(name, mode, &parent, data);
545 p->proc_fops = proc_fops;
546 return proc_register(parent, p);
548 EXPORT_SYMBOL(proc_create_data);
550 struct proc_dir_entry *proc_create(const char *name, umode_t mode,
551 struct proc_dir_entry *parent,
552 const struct file_operations *proc_fops)
554 return proc_create_data(name, mode, parent, proc_fops, NULL);
556 EXPORT_SYMBOL(proc_create);
558 static int proc_seq_open(struct inode *inode, struct file *file)
560 struct proc_dir_entry *de = PDE(inode);
563 return seq_open_private(file, de->seq_ops, de->state_size);
564 return seq_open(file, de->seq_ops);
567 static int proc_seq_release(struct inode *inode, struct file *file)
569 struct proc_dir_entry *de = PDE(inode);
572 return seq_release_private(inode, file);
573 return seq_release(inode, file);
576 static const struct file_operations proc_seq_fops = {
577 .open = proc_seq_open,
580 .release = proc_seq_release,
583 struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
584 struct proc_dir_entry *parent, const struct seq_operations *ops,
585 unsigned int state_size, void *data)
587 struct proc_dir_entry *p;
589 p = proc_create_reg(name, mode, &parent, data);
592 p->proc_fops = &proc_seq_fops;
594 p->state_size = state_size;
595 return proc_register(parent, p);
597 EXPORT_SYMBOL(proc_create_seq_private);
599 static int proc_single_open(struct inode *inode, struct file *file)
601 struct proc_dir_entry *de = PDE(inode);
603 return single_open(file, de->single_show, de->data);
606 static const struct file_operations proc_single_fops = {
607 .open = proc_single_open,
610 .release = single_release,
613 struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
614 struct proc_dir_entry *parent,
615 int (*show)(struct seq_file *, void *), void *data)
617 struct proc_dir_entry *p;
619 p = proc_create_reg(name, mode, &parent, data);
622 p->proc_fops = &proc_single_fops;
623 p->single_show = show;
624 return proc_register(parent, p);
626 EXPORT_SYMBOL(proc_create_single_data);
628 void proc_set_size(struct proc_dir_entry *de, loff_t size)
632 EXPORT_SYMBOL(proc_set_size);
634 void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
639 EXPORT_SYMBOL(proc_set_user);
641 void pde_put(struct proc_dir_entry *pde)
643 if (refcount_dec_and_test(&pde->refcnt)) {
644 proc_free_inum(pde->low_ino);
650 * Remove a /proc entry and free it if it's not currently in use.
652 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
654 struct proc_dir_entry *de = NULL;
655 const char *fn = name;
658 write_lock(&proc_subdir_lock);
659 if (__xlate_proc_name(name, &parent, &fn) != 0) {
660 write_unlock(&proc_subdir_lock);
665 de = pde_subdir_find(parent, fn, len);
667 rb_erase(&de->subdir_node, &parent->subdir);
668 if (S_ISDIR(de->mode)) {
672 write_unlock(&proc_subdir_lock);
674 WARN(1, "name '%s'\n", name);
678 proc_entry_rundown(de);
680 WARN(pde_subdir_first(de),
681 "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n",
682 __func__, de->parent->name, de->name, pde_subdir_first(de)->name);
685 EXPORT_SYMBOL(remove_proc_entry);
687 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
689 struct proc_dir_entry *root = NULL, *de, *next;
690 const char *fn = name;
693 write_lock(&proc_subdir_lock);
694 if (__xlate_proc_name(name, &parent, &fn) != 0) {
695 write_unlock(&proc_subdir_lock);
700 root = pde_subdir_find(parent, fn, len);
702 write_unlock(&proc_subdir_lock);
705 rb_erase(&root->subdir_node, &parent->subdir);
709 next = pde_subdir_first(de);
711 rb_erase(&next->subdir_node, &de->subdir);
716 if (S_ISDIR(de->mode))
718 write_unlock(&proc_subdir_lock);
720 proc_entry_rundown(de);
725 write_lock(&proc_subdir_lock);
731 EXPORT_SYMBOL(remove_proc_subtree);
733 void *proc_get_parent_data(const struct inode *inode)
735 struct proc_dir_entry *de = PDE(inode);
736 return de->parent->data;
738 EXPORT_SYMBOL_GPL(proc_get_parent_data);
740 void proc_remove(struct proc_dir_entry *de)
743 remove_proc_subtree(de->name, de->parent);
745 EXPORT_SYMBOL(proc_remove);
747 void *PDE_DATA(const struct inode *inode)
749 return __PDE_DATA(inode);
751 EXPORT_SYMBOL(PDE_DATA);
754 * Pull a user buffer into memory and pass it to the file's write handler if
755 * one is supplied. The ->write() method is permitted to modify the
756 * kernel-side buffer.
758 ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
761 struct proc_dir_entry *pde = PDE(file_inode(f));
767 if (size == 0 || size > PAGE_SIZE - 1)
769 buf = memdup_user_nul(ubuf, size);
772 ret = pde->write(f, buf, size);
774 return ret == 0 ? size : ret;