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>
27 #include <linux/bug.h>
29 #include <linux/uaccess.h>
33 static void proc_evict_inode(struct inode *inode)
35 struct proc_dir_entry *de;
36 struct ctl_table_header *head;
37 struct proc_inode *ei = PROC_I(inode);
39 truncate_inode_pages_final(&inode->i_data);
42 /* Stop tracking associated processes */
44 proc_pid_evict_inode(ei);
48 /* Let go of any associated proc directory entry */
57 RCU_INIT_POINTER(ei->sysctl, NULL);
58 proc_sys_evict_inode(inode, head);
62 static struct kmem_cache *proc_inode_cachep __ro_after_init;
63 static struct kmem_cache *pde_opener_cache __ro_after_init;
65 static struct inode *proc_alloc_inode(struct super_block *sb)
67 struct proc_inode *ei;
69 ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
74 ei->op.proc_get_link = NULL;
77 ei->sysctl_entry = NULL;
78 INIT_HLIST_NODE(&ei->sibling_inodes);
80 return &ei->vfs_inode;
83 static void proc_free_inode(struct inode *inode)
85 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
88 static void init_once(void *foo)
90 struct proc_inode *ei = (struct proc_inode *) foo;
92 inode_init_once(&ei->vfs_inode);
95 void __init proc_init_kmemcache(void)
97 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
98 sizeof(struct proc_inode),
99 0, (SLAB_RECLAIM_ACCOUNT|
100 SLAB_MEM_SPREAD|SLAB_ACCOUNT|
104 kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
105 SLAB_ACCOUNT|SLAB_PANIC, NULL);
106 proc_dir_entry_cache = kmem_cache_create_usercopy(
107 "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
108 offsetof(struct proc_dir_entry, inline_name),
109 SIZEOF_PDE_INLINE_NAME, NULL);
110 BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
113 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
116 struct proc_inode *ei;
117 struct hlist_node *node;
118 struct super_block *old_sb = NULL;
122 struct super_block *sb;
123 node = hlist_first_rcu(inodes);
126 ei = hlist_entry(node, struct proc_inode, sibling_inodes);
128 hlist_del_init_rcu(&ei->sibling_inodes);
131 inode = &ei->vfs_inode;
133 if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
135 inode = igrab(inode);
139 deactivate_super(old_sb);
142 if (unlikely(!inode)) {
147 if (S_ISDIR(inode->i_mode)) {
148 struct dentry *dir = d_find_any_alias(inode);
154 struct dentry *dentry;
155 while ((dentry = d_find_alias(inode))) {
156 d_invalidate(dentry);
166 deactivate_super(old_sb);
169 static inline const char *hidepid2str(enum proc_hidepid v)
172 case HIDEPID_OFF: return "off";
173 case HIDEPID_NO_ACCESS: return "noaccess";
174 case HIDEPID_INVISIBLE: return "invisible";
175 case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
177 WARN_ONCE(1, "bad hide_pid value: %d\n", v);
181 static int proc_show_options(struct seq_file *seq, struct dentry *root)
183 struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
185 if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
186 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
187 if (fs_info->hide_pid != HIDEPID_OFF)
188 seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
189 if (fs_info->pidonly != PROC_PIDONLY_OFF)
190 seq_printf(seq, ",subset=pid");
195 const struct super_operations proc_sops = {
196 .alloc_inode = proc_alloc_inode,
197 .free_inode = proc_free_inode,
198 .drop_inode = generic_delete_inode,
199 .evict_inode = proc_evict_inode,
200 .statfs = simple_statfs,
201 .show_options = proc_show_options,
204 enum {BIAS = -1U<<31};
206 static inline int use_pde(struct proc_dir_entry *pde)
208 return likely(atomic_inc_unless_negative(&pde->in_use));
211 static void unuse_pde(struct proc_dir_entry *pde)
213 if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
214 complete(pde->pde_unload_completion);
217 /* pde is locked on entry, unlocked on exit */
218 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
219 __releases(&pde->pde_unload_lock)
222 * close() (proc_reg_release()) can't delete an entry and proceed:
223 * ->release hook needs to be available at the right moment.
225 * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
226 * "struct file" needs to be available at the right moment.
228 * Therefore, first process to enter this function does ->release() and
229 * signals its completion to the other process which does nothing.
232 /* somebody else is doing that, just wait */
233 DECLARE_COMPLETION_ONSTACK(c);
235 spin_unlock(&pde->pde_unload_lock);
236 wait_for_completion(&c);
239 struct completion *c;
241 pdeo->closing = true;
242 spin_unlock(&pde->pde_unload_lock);
244 pde->proc_ops->proc_release(file_inode(file), file);
245 spin_lock(&pde->pde_unload_lock);
246 /* After ->release. */
249 spin_unlock(&pde->pde_unload_lock);
252 kmem_cache_free(pde_opener_cache, pdeo);
256 void proc_entry_rundown(struct proc_dir_entry *de)
258 DECLARE_COMPLETION_ONSTACK(c);
259 /* Wait until all existing callers into module are done. */
260 de->pde_unload_completion = &c;
261 if (atomic_add_return(BIAS, &de->in_use) != BIAS)
262 wait_for_completion(&c);
264 /* ->pde_openers list can't grow from now on. */
266 spin_lock(&de->pde_unload_lock);
267 while (!list_empty(&de->pde_openers)) {
268 struct pde_opener *pdeo;
269 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
270 close_pdeo(de, pdeo);
271 spin_lock(&de->pde_unload_lock);
273 spin_unlock(&de->pde_unload_lock);
276 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
278 struct proc_dir_entry *pde = PDE(file_inode(file));
281 if (pde_is_permanent(pde)) {
282 return pde->proc_ops->proc_lseek(file, offset, whence);
283 } else if (use_pde(pde)) {
284 rv = pde->proc_ops->proc_lseek(file, offset, whence);
290 static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
292 struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
295 if (pde_is_permanent(pde))
296 return pde->proc_ops->proc_read_iter(iocb, iter);
300 ret = pde->proc_ops->proc_read_iter(iocb, iter);
305 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
307 typeof_member(struct proc_ops, proc_read) read;
309 read = pde->proc_ops->proc_read;
311 return read(file, buf, count, ppos);
315 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
317 struct proc_dir_entry *pde = PDE(file_inode(file));
320 if (pde_is_permanent(pde)) {
321 return pde_read(pde, file, buf, count, ppos);
322 } else if (use_pde(pde)) {
323 rv = pde_read(pde, file, buf, count, ppos);
329 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
331 typeof_member(struct proc_ops, proc_write) write;
333 write = pde->proc_ops->proc_write;
335 return write(file, buf, count, ppos);
339 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
341 struct proc_dir_entry *pde = PDE(file_inode(file));
344 if (pde_is_permanent(pde)) {
345 return pde_write(pde, file, buf, count, ppos);
346 } else if (use_pde(pde)) {
347 rv = pde_write(pde, file, buf, count, ppos);
353 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
355 typeof_member(struct proc_ops, proc_poll) poll;
357 poll = pde->proc_ops->proc_poll;
359 return poll(file, pts);
360 return DEFAULT_POLLMASK;
363 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
365 struct proc_dir_entry *pde = PDE(file_inode(file));
366 __poll_t rv = DEFAULT_POLLMASK;
368 if (pde_is_permanent(pde)) {
369 return pde_poll(pde, file, pts);
370 } else if (use_pde(pde)) {
371 rv = pde_poll(pde, file, pts);
377 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
379 typeof_member(struct proc_ops, proc_ioctl) ioctl;
381 ioctl = pde->proc_ops->proc_ioctl;
383 return ioctl(file, cmd, arg);
387 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
389 struct proc_dir_entry *pde = PDE(file_inode(file));
392 if (pde_is_permanent(pde)) {
393 return pde_ioctl(pde, file, cmd, arg);
394 } else if (use_pde(pde)) {
395 rv = pde_ioctl(pde, file, cmd, arg);
402 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
404 typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
406 compat_ioctl = pde->proc_ops->proc_compat_ioctl;
408 return compat_ioctl(file, cmd, arg);
412 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
414 struct proc_dir_entry *pde = PDE(file_inode(file));
416 if (pde_is_permanent(pde)) {
417 return pde_compat_ioctl(pde, file, cmd, arg);
418 } else if (use_pde(pde)) {
419 rv = pde_compat_ioctl(pde, file, cmd, arg);
426 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
428 typeof_member(struct proc_ops, proc_mmap) mmap;
430 mmap = pde->proc_ops->proc_mmap;
432 return mmap(file, vma);
436 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
438 struct proc_dir_entry *pde = PDE(file_inode(file));
441 if (pde_is_permanent(pde)) {
442 return pde_mmap(pde, file, vma);
443 } else if (use_pde(pde)) {
444 rv = pde_mmap(pde, file, vma);
451 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
452 unsigned long len, unsigned long pgoff,
455 typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
457 get_area = pde->proc_ops->proc_get_unmapped_area;
460 get_area = current->mm->get_unmapped_area;
463 return get_area(file, orig_addr, len, pgoff, flags);
468 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
469 unsigned long len, unsigned long pgoff,
472 struct proc_dir_entry *pde = PDE(file_inode(file));
473 unsigned long rv = -EIO;
475 if (pde_is_permanent(pde)) {
476 return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
477 } else if (use_pde(pde)) {
478 rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
484 static int proc_reg_open(struct inode *inode, struct file *file)
486 struct proc_dir_entry *pde = PDE(inode);
488 typeof_member(struct proc_ops, proc_open) open;
489 typeof_member(struct proc_ops, proc_release) release;
490 struct pde_opener *pdeo;
492 if (pde_is_permanent(pde)) {
493 open = pde->proc_ops->proc_open;
495 rv = open(inode, file);
501 * 1) PDE's ->release hook will be called no matter what
502 * either normally by close()/->release, or forcefully by
503 * rmmod/remove_proc_entry.
505 * 2) rmmod isn't blocked by opening file in /proc and sitting on
506 * the descriptor (including "rmmod foo </proc/foo" scenario).
508 * Save every "struct file" with custom ->release hook.
513 release = pde->proc_ops->proc_release;
515 pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
522 open = pde->proc_ops->proc_open;
524 rv = open(inode, file);
528 /* To know what to release. */
530 pdeo->closing = false;
532 spin_lock(&pde->pde_unload_lock);
533 list_add(&pdeo->lh, &pde->pde_openers);
534 spin_unlock(&pde->pde_unload_lock);
536 kmem_cache_free(pde_opener_cache, pdeo);
544 static int proc_reg_release(struct inode *inode, struct file *file)
546 struct proc_dir_entry *pde = PDE(inode);
547 struct pde_opener *pdeo;
549 if (pde_is_permanent(pde)) {
550 typeof_member(struct proc_ops, proc_release) release;
552 release = pde->proc_ops->proc_release;
554 return release(inode, file);
559 spin_lock(&pde->pde_unload_lock);
560 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
561 if (pdeo->file == file) {
562 close_pdeo(pde, pdeo);
566 spin_unlock(&pde->pde_unload_lock);
570 static const struct file_operations proc_reg_file_ops = {
571 .llseek = proc_reg_llseek,
572 .read = proc_reg_read,
573 .write = proc_reg_write,
574 .poll = proc_reg_poll,
575 .unlocked_ioctl = proc_reg_unlocked_ioctl,
576 .mmap = proc_reg_mmap,
577 .get_unmapped_area = proc_reg_get_unmapped_area,
578 .open = proc_reg_open,
579 .release = proc_reg_release,
582 static const struct file_operations proc_iter_file_ops = {
583 .llseek = proc_reg_llseek,
584 .read_iter = proc_reg_read_iter,
585 .write = proc_reg_write,
586 .splice_read = generic_file_splice_read,
587 .poll = proc_reg_poll,
588 .unlocked_ioctl = proc_reg_unlocked_ioctl,
589 .mmap = proc_reg_mmap,
590 .get_unmapped_area = proc_reg_get_unmapped_area,
591 .open = proc_reg_open,
592 .release = proc_reg_release,
596 static const struct file_operations proc_reg_file_ops_compat = {
597 .llseek = proc_reg_llseek,
598 .read = proc_reg_read,
599 .write = proc_reg_write,
600 .poll = proc_reg_poll,
601 .unlocked_ioctl = proc_reg_unlocked_ioctl,
602 .compat_ioctl = proc_reg_compat_ioctl,
603 .mmap = proc_reg_mmap,
604 .get_unmapped_area = proc_reg_get_unmapped_area,
605 .open = proc_reg_open,
606 .release = proc_reg_release,
609 static const struct file_operations proc_iter_file_ops_compat = {
610 .llseek = proc_reg_llseek,
611 .read_iter = proc_reg_read_iter,
612 .splice_read = generic_file_splice_read,
613 .write = proc_reg_write,
614 .poll = proc_reg_poll,
615 .unlocked_ioctl = proc_reg_unlocked_ioctl,
616 .compat_ioctl = proc_reg_compat_ioctl,
617 .mmap = proc_reg_mmap,
618 .get_unmapped_area = proc_reg_get_unmapped_area,
619 .open = proc_reg_open,
620 .release = proc_reg_release,
624 static void proc_put_link(void *p)
629 static const char *proc_get_link(struct dentry *dentry,
631 struct delayed_call *done)
633 struct proc_dir_entry *pde = PDE(inode);
635 return ERR_PTR(-EINVAL);
636 set_delayed_call(done, proc_put_link, pde);
640 const struct inode_operations proc_link_inode_operations = {
641 .get_link = proc_get_link,
644 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
646 struct inode *inode = new_inode(sb);
653 inode->i_ino = de->low_ino;
654 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
655 PROC_I(inode)->pde = de;
656 if (is_empty_pde(de)) {
657 make_empty_dir_inode(inode);
662 inode->i_mode = de->mode;
663 inode->i_uid = de->uid;
664 inode->i_gid = de->gid;
667 inode->i_size = de->size;
669 set_nlink(inode, de->nlink);
671 if (S_ISREG(inode->i_mode)) {
672 inode->i_op = de->proc_iops;
673 if (de->proc_ops->proc_read_iter)
674 inode->i_fop = &proc_iter_file_ops;
676 inode->i_fop = &proc_reg_file_ops;
678 if (de->proc_ops->proc_compat_ioctl) {
679 if (de->proc_ops->proc_read_iter)
680 inode->i_fop = &proc_iter_file_ops_compat;
682 inode->i_fop = &proc_reg_file_ops_compat;
685 } else if (S_ISDIR(inode->i_mode)) {
686 inode->i_op = de->proc_iops;
687 inode->i_fop = de->proc_dir_ops;
688 } else if (S_ISLNK(inode->i_mode)) {
689 inode->i_op = de->proc_iops;