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;
37 truncate_inode_pages_final(&inode->i_data);
40 /* Stop tracking associated processes */
41 put_pid(PROC_I(inode)->pid);
43 /* Let go of any associated proc directory entry */
48 head = PROC_I(inode)->sysctl;
50 RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL);
51 proc_sys_evict_inode(inode, head);
55 static struct kmem_cache *proc_inode_cachep __ro_after_init;
56 static struct kmem_cache *pde_opener_cache __ro_after_init;
58 static struct inode *proc_alloc_inode(struct super_block *sb)
60 struct proc_inode *ei;
62 ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
67 ei->op.proc_get_link = NULL;
70 ei->sysctl_entry = NULL;
72 return &ei->vfs_inode;
75 static void proc_free_inode(struct inode *inode)
77 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
80 static void init_once(void *foo)
82 struct proc_inode *ei = (struct proc_inode *) foo;
84 inode_init_once(&ei->vfs_inode);
87 void __init proc_init_kmemcache(void)
89 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
90 sizeof(struct proc_inode),
91 0, (SLAB_RECLAIM_ACCOUNT|
92 SLAB_MEM_SPREAD|SLAB_ACCOUNT|
96 kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
97 SLAB_ACCOUNT|SLAB_PANIC, NULL);
98 proc_dir_entry_cache = kmem_cache_create_usercopy(
99 "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
100 offsetof(struct proc_dir_entry, inline_name),
101 SIZEOF_PDE_INLINE_NAME, NULL);
102 BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
105 static int proc_show_options(struct seq_file *seq, struct dentry *root)
107 struct super_block *sb = root->d_sb;
108 struct pid_namespace *pid = sb->s_fs_info;
110 if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
111 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
112 if (pid->hide_pid != HIDEPID_OFF)
113 seq_printf(seq, ",hidepid=%u", pid->hide_pid);
118 const struct super_operations proc_sops = {
119 .alloc_inode = proc_alloc_inode,
120 .free_inode = proc_free_inode,
121 .drop_inode = generic_delete_inode,
122 .evict_inode = proc_evict_inode,
123 .statfs = simple_statfs,
124 .show_options = proc_show_options,
127 enum {BIAS = -1U<<31};
129 static inline int use_pde(struct proc_dir_entry *pde)
131 return likely(atomic_inc_unless_negative(&pde->in_use));
134 static void unuse_pde(struct proc_dir_entry *pde)
136 if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
137 complete(pde->pde_unload_completion);
140 /* pde is locked on entry, unlocked on exit */
141 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
144 * close() (proc_reg_release()) can't delete an entry and proceed:
145 * ->release hook needs to be available at the right moment.
147 * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
148 * "struct file" needs to be available at the right moment.
150 * Therefore, first process to enter this function does ->release() and
151 * signals its completion to the other process which does nothing.
154 /* somebody else is doing that, just wait */
155 DECLARE_COMPLETION_ONSTACK(c);
157 spin_unlock(&pde->pde_unload_lock);
158 wait_for_completion(&c);
161 struct completion *c;
163 pdeo->closing = true;
164 spin_unlock(&pde->pde_unload_lock);
166 pde->proc_fops->release(file_inode(file), file);
167 spin_lock(&pde->pde_unload_lock);
168 /* After ->release. */
171 spin_unlock(&pde->pde_unload_lock);
174 kmem_cache_free(pde_opener_cache, pdeo);
178 void proc_entry_rundown(struct proc_dir_entry *de)
180 DECLARE_COMPLETION_ONSTACK(c);
181 /* Wait until all existing callers into module are done. */
182 de->pde_unload_completion = &c;
183 if (atomic_add_return(BIAS, &de->in_use) != BIAS)
184 wait_for_completion(&c);
186 /* ->pde_openers list can't grow from now on. */
188 spin_lock(&de->pde_unload_lock);
189 while (!list_empty(&de->pde_openers)) {
190 struct pde_opener *pdeo;
191 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
192 close_pdeo(de, pdeo);
193 spin_lock(&de->pde_unload_lock);
195 spin_unlock(&de->pde_unload_lock);
198 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
200 struct proc_dir_entry *pde = PDE(file_inode(file));
203 loff_t (*llseek)(struct file *, loff_t, int);
204 llseek = pde->proc_fops->llseek;
206 llseek = default_llseek;
207 rv = llseek(file, offset, whence);
213 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
215 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
216 struct proc_dir_entry *pde = PDE(file_inode(file));
219 read = pde->proc_fops->read;
221 rv = read(file, buf, count, ppos);
227 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
229 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
230 struct proc_dir_entry *pde = PDE(file_inode(file));
233 write = pde->proc_fops->write;
235 rv = write(file, buf, count, ppos);
241 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
243 struct proc_dir_entry *pde = PDE(file_inode(file));
244 __poll_t rv = DEFAULT_POLLMASK;
245 __poll_t (*poll)(struct file *, struct poll_table_struct *);
247 poll = pde->proc_fops->poll;
249 rv = poll(file, pts);
255 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
257 struct proc_dir_entry *pde = PDE(file_inode(file));
259 long (*ioctl)(struct file *, unsigned int, unsigned long);
261 ioctl = pde->proc_fops->unlocked_ioctl;
263 rv = ioctl(file, cmd, arg);
270 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
272 struct proc_dir_entry *pde = PDE(file_inode(file));
274 long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
276 compat_ioctl = pde->proc_fops->compat_ioctl;
278 rv = compat_ioctl(file, cmd, arg);
285 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
287 struct proc_dir_entry *pde = PDE(file_inode(file));
289 int (*mmap)(struct file *, struct vm_area_struct *);
291 mmap = pde->proc_fops->mmap;
293 rv = mmap(file, vma);
300 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
301 unsigned long len, unsigned long pgoff,
304 struct proc_dir_entry *pde = PDE(file_inode(file));
305 unsigned long rv = -EIO;
308 typeof(proc_reg_get_unmapped_area) *get_area;
310 get_area = pde->proc_fops->get_unmapped_area;
313 get_area = current->mm->get_unmapped_area;
317 rv = get_area(file, orig_addr, len, pgoff, flags);
325 static int proc_reg_open(struct inode *inode, struct file *file)
327 struct proc_dir_entry *pde = PDE(inode);
329 int (*open)(struct inode *, struct file *);
330 int (*release)(struct inode *, struct file *);
331 struct pde_opener *pdeo;
335 * 1) PDE's ->release hook will be called no matter what
336 * either normally by close()/->release, or forcefully by
337 * rmmod/remove_proc_entry.
339 * 2) rmmod isn't blocked by opening file in /proc and sitting on
340 * the descriptor (including "rmmod foo </proc/foo" scenario).
342 * Save every "struct file" with custom ->release hook.
347 release = pde->proc_fops->release;
349 pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
356 open = pde->proc_fops->open;
358 rv = open(inode, file);
362 /* To know what to release. */
364 pdeo->closing = false;
366 spin_lock(&pde->pde_unload_lock);
367 list_add(&pdeo->lh, &pde->pde_openers);
368 spin_unlock(&pde->pde_unload_lock);
370 kmem_cache_free(pde_opener_cache, pdeo);
378 static int proc_reg_release(struct inode *inode, struct file *file)
380 struct proc_dir_entry *pde = PDE(inode);
381 struct pde_opener *pdeo;
382 spin_lock(&pde->pde_unload_lock);
383 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
384 if (pdeo->file == file) {
385 close_pdeo(pde, pdeo);
389 spin_unlock(&pde->pde_unload_lock);
393 static const struct file_operations proc_reg_file_ops = {
394 .llseek = proc_reg_llseek,
395 .read = proc_reg_read,
396 .write = proc_reg_write,
397 .poll = proc_reg_poll,
398 .unlocked_ioctl = proc_reg_unlocked_ioctl,
400 .compat_ioctl = proc_reg_compat_ioctl,
402 .mmap = proc_reg_mmap,
403 .get_unmapped_area = proc_reg_get_unmapped_area,
404 .open = proc_reg_open,
405 .release = proc_reg_release,
409 static const struct file_operations proc_reg_file_ops_no_compat = {
410 .llseek = proc_reg_llseek,
411 .read = proc_reg_read,
412 .write = proc_reg_write,
413 .poll = proc_reg_poll,
414 .unlocked_ioctl = proc_reg_unlocked_ioctl,
415 .mmap = proc_reg_mmap,
416 .get_unmapped_area = proc_reg_get_unmapped_area,
417 .open = proc_reg_open,
418 .release = proc_reg_release,
422 static void proc_put_link(void *p)
427 static const char *proc_get_link(struct dentry *dentry,
429 struct delayed_call *done)
431 struct proc_dir_entry *pde = PDE(inode);
433 return ERR_PTR(-EINVAL);
434 set_delayed_call(done, proc_put_link, pde);
438 const struct inode_operations proc_link_inode_operations = {
439 .get_link = proc_get_link,
442 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
444 struct inode *inode = new_inode_pseudo(sb);
447 inode->i_ino = de->low_ino;
448 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
449 PROC_I(inode)->pde = de;
451 if (is_empty_pde(de)) {
452 make_empty_dir_inode(inode);
456 inode->i_mode = de->mode;
457 inode->i_uid = de->uid;
458 inode->i_gid = de->gid;
461 inode->i_size = de->size;
463 set_nlink(inode, de->nlink);
464 WARN_ON(!de->proc_iops);
465 inode->i_op = de->proc_iops;
467 if (S_ISREG(inode->i_mode)) {
469 if (!de->proc_fops->compat_ioctl)
471 &proc_reg_file_ops_no_compat;
474 inode->i_fop = &proc_reg_file_ops;
476 inode->i_fop = de->proc_fops;