1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/proc/inode.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
8 #include <linux/cache.h>
9 #include <linux/time.h>
10 #include <linux/proc_fs.h>
11 #include <linux/kernel.h>
12 #include <linux/pid_namespace.h>
14 #include <linux/string.h>
15 #include <linux/stat.h>
16 #include <linux/completion.h>
17 #include <linux/poll.h>
18 #include <linux/printk.h>
19 #include <linux/file.h>
20 #include <linux/limits.h>
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/sysctl.h>
24 #include <linux/seq_file.h>
25 #include <linux/slab.h>
26 #include <linux/mount.h>
28 #include <linux/uaccess.h>
32 static void proc_evict_inode(struct inode *inode)
34 struct proc_dir_entry *de;
35 struct ctl_table_header *head;
36 struct proc_inode *ei = PROC_I(inode);
38 truncate_inode_pages_final(&inode->i_data);
41 /* Stop tracking associated processes */
43 proc_pid_evict_inode(ei);
47 /* Let go of any associated proc directory entry */
56 RCU_INIT_POINTER(ei->sysctl, NULL);
57 proc_sys_evict_inode(inode, head);
61 static struct kmem_cache *proc_inode_cachep __ro_after_init;
62 static struct kmem_cache *pde_opener_cache __ro_after_init;
64 static struct inode *proc_alloc_inode(struct super_block *sb)
66 struct proc_inode *ei;
68 ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
73 ei->op.proc_get_link = NULL;
76 ei->sysctl_entry = NULL;
77 INIT_HLIST_NODE(&ei->sibling_inodes);
79 return &ei->vfs_inode;
82 static void proc_free_inode(struct inode *inode)
84 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
87 static void init_once(void *foo)
89 struct proc_inode *ei = (struct proc_inode *) foo;
91 inode_init_once(&ei->vfs_inode);
94 void __init proc_init_kmemcache(void)
96 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
97 sizeof(struct proc_inode),
98 0, (SLAB_RECLAIM_ACCOUNT|
99 SLAB_MEM_SPREAD|SLAB_ACCOUNT|
103 kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
104 SLAB_ACCOUNT|SLAB_PANIC, NULL);
105 proc_dir_entry_cache = kmem_cache_create_usercopy(
106 "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
107 offsetof(struct proc_dir_entry, inline_name),
108 SIZEOF_PDE_INLINE_NAME, NULL);
109 BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
112 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
115 struct proc_inode *ei;
116 struct hlist_node *node;
117 struct super_block *old_sb = NULL;
121 struct super_block *sb;
122 node = hlist_first_rcu(inodes);
125 ei = hlist_entry(node, struct proc_inode, sibling_inodes);
127 hlist_del_init_rcu(&ei->sibling_inodes);
130 inode = &ei->vfs_inode;
132 if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
134 inode = igrab(inode);
138 deactivate_super(old_sb);
141 if (unlikely(!inode)) {
146 if (S_ISDIR(inode->i_mode)) {
147 struct dentry *dir = d_find_any_alias(inode);
153 struct dentry *dentry;
154 while ((dentry = d_find_alias(inode))) {
155 d_invalidate(dentry);
165 deactivate_super(old_sb);
168 static int proc_show_options(struct seq_file *seq, struct dentry *root)
170 struct super_block *sb = root->d_sb;
171 struct pid_namespace *pid = sb->s_fs_info;
173 if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
174 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
175 if (pid->hide_pid != HIDEPID_OFF)
176 seq_printf(seq, ",hidepid=%u", pid->hide_pid);
181 const struct super_operations proc_sops = {
182 .alloc_inode = proc_alloc_inode,
183 .free_inode = proc_free_inode,
184 .drop_inode = generic_delete_inode,
185 .evict_inode = proc_evict_inode,
186 .statfs = simple_statfs,
187 .show_options = proc_show_options,
190 enum {BIAS = -1U<<31};
192 static inline int use_pde(struct proc_dir_entry *pde)
194 return likely(atomic_inc_unless_negative(&pde->in_use));
197 static void unuse_pde(struct proc_dir_entry *pde)
199 if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
200 complete(pde->pde_unload_completion);
203 /* pde is locked on entry, unlocked on exit */
204 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
205 __releases(&pde->pde_unload_lock)
208 * close() (proc_reg_release()) can't delete an entry and proceed:
209 * ->release hook needs to be available at the right moment.
211 * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
212 * "struct file" needs to be available at the right moment.
214 * Therefore, first process to enter this function does ->release() and
215 * signals its completion to the other process which does nothing.
218 /* somebody else is doing that, just wait */
219 DECLARE_COMPLETION_ONSTACK(c);
221 spin_unlock(&pde->pde_unload_lock);
222 wait_for_completion(&c);
225 struct completion *c;
227 pdeo->closing = true;
228 spin_unlock(&pde->pde_unload_lock);
230 pde->proc_ops->proc_release(file_inode(file), file);
231 spin_lock(&pde->pde_unload_lock);
232 /* After ->release. */
235 spin_unlock(&pde->pde_unload_lock);
238 kmem_cache_free(pde_opener_cache, pdeo);
242 void proc_entry_rundown(struct proc_dir_entry *de)
244 DECLARE_COMPLETION_ONSTACK(c);
245 /* Wait until all existing callers into module are done. */
246 de->pde_unload_completion = &c;
247 if (atomic_add_return(BIAS, &de->in_use) != BIAS)
248 wait_for_completion(&c);
250 /* ->pde_openers list can't grow from now on. */
252 spin_lock(&de->pde_unload_lock);
253 while (!list_empty(&de->pde_openers)) {
254 struct pde_opener *pdeo;
255 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
256 close_pdeo(de, pdeo);
257 spin_lock(&de->pde_unload_lock);
259 spin_unlock(&de->pde_unload_lock);
262 static loff_t pde_lseek(struct proc_dir_entry *pde, struct file *file, loff_t offset, int whence)
264 typeof_member(struct proc_ops, proc_lseek) lseek;
266 lseek = pde->proc_ops->proc_lseek;
268 lseek = default_llseek;
269 return lseek(file, offset, whence);
272 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
274 struct proc_dir_entry *pde = PDE(file_inode(file));
277 if (pde_is_permanent(pde)) {
278 return pde_lseek(pde, file, offset, whence);
279 } else if (use_pde(pde)) {
280 rv = pde_lseek(pde, file, offset, whence);
286 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
288 typeof_member(struct proc_ops, proc_read) read;
290 read = pde->proc_ops->proc_read;
292 return read(file, buf, count, ppos);
296 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
298 struct proc_dir_entry *pde = PDE(file_inode(file));
301 if (pde_is_permanent(pde)) {
302 return pde_read(pde, file, buf, count, ppos);
303 } else if (use_pde(pde)) {
304 rv = pde_read(pde, file, buf, count, ppos);
310 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
312 typeof_member(struct proc_ops, proc_write) write;
314 write = pde->proc_ops->proc_write;
316 return write(file, buf, count, ppos);
320 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
322 struct proc_dir_entry *pde = PDE(file_inode(file));
325 if (pde_is_permanent(pde)) {
326 return pde_write(pde, file, buf, count, ppos);
327 } else if (use_pde(pde)) {
328 rv = pde_write(pde, file, buf, count, ppos);
334 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
336 typeof_member(struct proc_ops, proc_poll) poll;
338 poll = pde->proc_ops->proc_poll;
340 return poll(file, pts);
341 return DEFAULT_POLLMASK;
344 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
346 struct proc_dir_entry *pde = PDE(file_inode(file));
347 __poll_t rv = DEFAULT_POLLMASK;
349 if (pde_is_permanent(pde)) {
350 return pde_poll(pde, file, pts);
351 } else if (use_pde(pde)) {
352 rv = pde_poll(pde, file, pts);
358 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
360 typeof_member(struct proc_ops, proc_ioctl) ioctl;
362 ioctl = pde->proc_ops->proc_ioctl;
364 return ioctl(file, cmd, arg);
368 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
370 struct proc_dir_entry *pde = PDE(file_inode(file));
373 if (pde_is_permanent(pde)) {
374 return pde_ioctl(pde, file, cmd, arg);
375 } else if (use_pde(pde)) {
376 rv = pde_ioctl(pde, file, cmd, arg);
383 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
385 typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
387 compat_ioctl = pde->proc_ops->proc_compat_ioctl;
389 return compat_ioctl(file, cmd, arg);
393 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
395 struct proc_dir_entry *pde = PDE(file_inode(file));
397 if (pde_is_permanent(pde)) {
398 return pde_compat_ioctl(pde, file, cmd, arg);
399 } else if (use_pde(pde)) {
400 rv = pde_compat_ioctl(pde, file, cmd, arg);
407 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
409 typeof_member(struct proc_ops, proc_mmap) mmap;
411 mmap = pde->proc_ops->proc_mmap;
413 return mmap(file, vma);
417 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
419 struct proc_dir_entry *pde = PDE(file_inode(file));
422 if (pde_is_permanent(pde)) {
423 return pde_mmap(pde, file, vma);
424 } else if (use_pde(pde)) {
425 rv = pde_mmap(pde, file, vma);
432 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
433 unsigned long len, unsigned long pgoff,
436 typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
438 get_area = pde->proc_ops->proc_get_unmapped_area;
441 get_area = current->mm->get_unmapped_area;
444 return get_area(file, orig_addr, len, pgoff, flags);
449 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
450 unsigned long len, unsigned long pgoff,
453 struct proc_dir_entry *pde = PDE(file_inode(file));
454 unsigned long rv = -EIO;
456 if (pde_is_permanent(pde)) {
457 return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
458 } else if (use_pde(pde)) {
459 rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
465 static int proc_reg_open(struct inode *inode, struct file *file)
467 struct proc_dir_entry *pde = PDE(inode);
469 typeof_member(struct proc_ops, proc_open) open;
470 typeof_member(struct proc_ops, proc_release) release;
471 struct pde_opener *pdeo;
473 if (pde_is_permanent(pde)) {
474 open = pde->proc_ops->proc_open;
476 rv = open(inode, file);
482 * 1) PDE's ->release hook will be called no matter what
483 * either normally by close()/->release, or forcefully by
484 * rmmod/remove_proc_entry.
486 * 2) rmmod isn't blocked by opening file in /proc and sitting on
487 * the descriptor (including "rmmod foo </proc/foo" scenario).
489 * Save every "struct file" with custom ->release hook.
494 release = pde->proc_ops->proc_release;
496 pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
503 open = pde->proc_ops->proc_open;
505 rv = open(inode, file);
509 /* To know what to release. */
511 pdeo->closing = false;
513 spin_lock(&pde->pde_unload_lock);
514 list_add(&pdeo->lh, &pde->pde_openers);
515 spin_unlock(&pde->pde_unload_lock);
517 kmem_cache_free(pde_opener_cache, pdeo);
525 static int proc_reg_release(struct inode *inode, struct file *file)
527 struct proc_dir_entry *pde = PDE(inode);
528 struct pde_opener *pdeo;
530 if (pde_is_permanent(pde)) {
531 typeof_member(struct proc_ops, proc_release) release;
533 release = pde->proc_ops->proc_release;
535 return release(inode, file);
540 spin_lock(&pde->pde_unload_lock);
541 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
542 if (pdeo->file == file) {
543 close_pdeo(pde, pdeo);
547 spin_unlock(&pde->pde_unload_lock);
551 static const struct file_operations proc_reg_file_ops = {
552 .llseek = proc_reg_llseek,
553 .read = proc_reg_read,
554 .write = proc_reg_write,
555 .poll = proc_reg_poll,
556 .unlocked_ioctl = proc_reg_unlocked_ioctl,
558 .compat_ioctl = proc_reg_compat_ioctl,
560 .mmap = proc_reg_mmap,
561 .get_unmapped_area = proc_reg_get_unmapped_area,
562 .open = proc_reg_open,
563 .release = proc_reg_release,
567 static const struct file_operations proc_reg_file_ops_no_compat = {
568 .llseek = proc_reg_llseek,
569 .read = proc_reg_read,
570 .write = proc_reg_write,
571 .poll = proc_reg_poll,
572 .unlocked_ioctl = proc_reg_unlocked_ioctl,
573 .mmap = proc_reg_mmap,
574 .get_unmapped_area = proc_reg_get_unmapped_area,
575 .open = proc_reg_open,
576 .release = proc_reg_release,
580 static void proc_put_link(void *p)
585 static const char *proc_get_link(struct dentry *dentry,
587 struct delayed_call *done)
589 struct proc_dir_entry *pde = PDE(inode);
591 return ERR_PTR(-EINVAL);
592 set_delayed_call(done, proc_put_link, pde);
596 const struct inode_operations proc_link_inode_operations = {
597 .get_link = proc_get_link,
600 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
602 struct inode *inode = new_inode_pseudo(sb);
605 inode->i_ino = de->low_ino;
606 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
607 PROC_I(inode)->pde = de;
609 if (is_empty_pde(de)) {
610 make_empty_dir_inode(inode);
614 inode->i_mode = de->mode;
615 inode->i_uid = de->uid;
616 inode->i_gid = de->gid;
619 inode->i_size = de->size;
621 set_nlink(inode, de->nlink);
623 if (S_ISREG(inode->i_mode)) {
624 inode->i_op = de->proc_iops;
625 inode->i_fop = &proc_reg_file_ops;
627 if (!de->proc_ops->proc_compat_ioctl) {
628 inode->i_fop = &proc_reg_file_ops_no_compat;
631 } else if (S_ISDIR(inode->i_mode)) {
632 inode->i_op = de->proc_iops;
633 inode->i_fop = de->proc_dir_ops;
634 } else if (S_ISLNK(inode->i_mode)) {
635 inode->i_op = de->proc_iops;