2 * linux/fs/proc/inode.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
7 #include <linux/time.h>
8 #include <linux/proc_fs.h>
9 #include <linux/kernel.h>
10 #include <linux/pid_namespace.h>
12 #include <linux/string.h>
13 #include <linux/stat.h>
14 #include <linux/completion.h>
15 #include <linux/poll.h>
16 #include <linux/file.h>
17 #include <linux/limits.h>
18 #include <linux/init.h>
19 #include <linux/module.h>
20 #include <linux/sysctl.h>
21 #include <linux/seq_file.h>
22 #include <linux/slab.h>
23 #include <linux/mount.h>
25 #include <asm/system.h>
26 #include <asm/uaccess.h>
30 static void proc_evict_inode(struct inode *inode)
32 struct proc_dir_entry *de;
33 struct ctl_table_header *head;
34 const struct proc_ns_operations *ns_ops;
36 truncate_inode_pages(&inode->i_data, 0);
39 /* Stop tracking associated processes */
40 put_pid(PROC_I(inode)->pid);
42 /* Let go of any associated proc directory entry */
43 de = PROC_I(inode)->pde;
46 head = PROC_I(inode)->sysctl;
48 rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
49 sysctl_head_put(head);
51 /* Release any associated namespace */
52 ns_ops = PROC_I(inode)->ns_ops;
53 if (ns_ops && ns_ops->put)
54 ns_ops->put(PROC_I(inode)->ns);
57 static struct kmem_cache * proc_inode_cachep;
59 static struct inode *proc_alloc_inode(struct super_block *sb)
61 struct proc_inode *ei;
64 ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
69 ei->op.proc_get_link = NULL;
72 ei->sysctl_entry = NULL;
75 inode = &ei->vfs_inode;
76 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
80 static void proc_i_callback(struct rcu_head *head)
82 struct inode *inode = container_of(head, struct inode, i_rcu);
83 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
86 static void proc_destroy_inode(struct inode *inode)
88 call_rcu(&inode->i_rcu, proc_i_callback);
91 static void init_once(void *foo)
93 struct proc_inode *ei = (struct proc_inode *) foo;
95 inode_init_once(&ei->vfs_inode);
98 void __init proc_init_inodecache(void)
100 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
101 sizeof(struct proc_inode),
102 0, (SLAB_RECLAIM_ACCOUNT|
103 SLAB_MEM_SPREAD|SLAB_PANIC),
107 static int proc_show_options(struct seq_file *seq, struct dentry *root)
109 struct super_block *sb = root->d_sb;
110 struct pid_namespace *pid = sb->s_fs_info;
113 seq_printf(seq, ",gid=%lu", (unsigned long)pid->pid_gid);
114 if (pid->hide_pid != 0)
115 seq_printf(seq, ",hidepid=%u", pid->hide_pid);
120 static const struct super_operations proc_sops = {
121 .alloc_inode = proc_alloc_inode,
122 .destroy_inode = proc_destroy_inode,
123 .drop_inode = generic_delete_inode,
124 .evict_inode = proc_evict_inode,
125 .statfs = simple_statfs,
126 .remount_fs = proc_remount,
127 .show_options = proc_show_options,
130 static void __pde_users_dec(struct proc_dir_entry *pde)
133 if (pde->pde_unload_completion && pde->pde_users == 0)
134 complete(pde->pde_unload_completion);
137 void pde_users_dec(struct proc_dir_entry *pde)
139 spin_lock(&pde->pde_unload_lock);
140 __pde_users_dec(pde);
141 spin_unlock(&pde->pde_unload_lock);
144 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
146 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
148 loff_t (*llseek)(struct file *, loff_t, int);
150 spin_lock(&pde->pde_unload_lock);
152 * remove_proc_entry() is going to delete PDE (as part of module
153 * cleanup sequence). No new callers into module allowed.
155 if (!pde->proc_fops) {
156 spin_unlock(&pde->pde_unload_lock);
160 * Bump refcount so that remove_proc_entry will wail for ->llseek to
165 * Save function pointer under lock, to protect against ->proc_fops
166 * NULL'ifying right after ->pde_unload_lock is dropped.
168 llseek = pde->proc_fops->llseek;
169 spin_unlock(&pde->pde_unload_lock);
172 llseek = default_llseek;
173 rv = llseek(file, offset, whence);
179 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
181 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
183 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
185 spin_lock(&pde->pde_unload_lock);
186 if (!pde->proc_fops) {
187 spin_unlock(&pde->pde_unload_lock);
191 read = pde->proc_fops->read;
192 spin_unlock(&pde->pde_unload_lock);
195 rv = read(file, buf, count, ppos);
201 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
203 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
205 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
207 spin_lock(&pde->pde_unload_lock);
208 if (!pde->proc_fops) {
209 spin_unlock(&pde->pde_unload_lock);
213 write = pde->proc_fops->write;
214 spin_unlock(&pde->pde_unload_lock);
217 rv = write(file, buf, count, ppos);
223 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
225 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
226 unsigned int rv = DEFAULT_POLLMASK;
227 unsigned int (*poll)(struct file *, struct poll_table_struct *);
229 spin_lock(&pde->pde_unload_lock);
230 if (!pde->proc_fops) {
231 spin_unlock(&pde->pde_unload_lock);
235 poll = pde->proc_fops->poll;
236 spin_unlock(&pde->pde_unload_lock);
239 rv = poll(file, pts);
245 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
247 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
249 long (*ioctl)(struct file *, unsigned int, unsigned long);
251 spin_lock(&pde->pde_unload_lock);
252 if (!pde->proc_fops) {
253 spin_unlock(&pde->pde_unload_lock);
257 ioctl = pde->proc_fops->unlocked_ioctl;
258 spin_unlock(&pde->pde_unload_lock);
261 rv = ioctl(file, cmd, arg);
268 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
270 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
272 long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
274 spin_lock(&pde->pde_unload_lock);
275 if (!pde->proc_fops) {
276 spin_unlock(&pde->pde_unload_lock);
280 compat_ioctl = pde->proc_fops->compat_ioctl;
281 spin_unlock(&pde->pde_unload_lock);
284 rv = compat_ioctl(file, cmd, arg);
291 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
293 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
295 int (*mmap)(struct file *, struct vm_area_struct *);
297 spin_lock(&pde->pde_unload_lock);
298 if (!pde->proc_fops) {
299 spin_unlock(&pde->pde_unload_lock);
303 mmap = pde->proc_fops->mmap;
304 spin_unlock(&pde->pde_unload_lock);
307 rv = mmap(file, vma);
313 static int proc_reg_open(struct inode *inode, struct file *file)
315 struct proc_dir_entry *pde = PDE(inode);
317 int (*open)(struct inode *, struct file *);
318 int (*release)(struct inode *, struct file *);
319 struct pde_opener *pdeo;
322 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
323 * sequence. ->release won't be called because ->proc_fops will be
324 * cleared. Depending on complexity of ->release, consequences vary.
326 * We can't wait for mercy when close will be done for real, it's
327 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
328 * by hand in remove_proc_entry(). For this, save opener's credentials
331 pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);
335 spin_lock(&pde->pde_unload_lock);
336 if (!pde->proc_fops) {
337 spin_unlock(&pde->pde_unload_lock);
342 open = pde->proc_fops->open;
343 release = pde->proc_fops->release;
344 spin_unlock(&pde->pde_unload_lock);
347 rv = open(inode, file);
349 spin_lock(&pde->pde_unload_lock);
350 if (rv == 0 && release) {
351 /* To know what to release. */
354 /* Strictly for "too late" ->release in proc_reg_release(). */
355 pdeo->release = release;
356 list_add(&pdeo->lh, &pde->pde_openers);
359 __pde_users_dec(pde);
360 spin_unlock(&pde->pde_unload_lock);
364 static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde,
365 struct inode *inode, struct file *file)
367 struct pde_opener *pdeo;
369 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
370 if (pdeo->inode == inode && pdeo->file == file)
376 static int proc_reg_release(struct inode *inode, struct file *file)
378 struct proc_dir_entry *pde = PDE(inode);
380 int (*release)(struct inode *, struct file *);
381 struct pde_opener *pdeo;
383 spin_lock(&pde->pde_unload_lock);
384 pdeo = find_pde_opener(pde, inode, file);
385 if (!pde->proc_fops) {
387 * Can't simply exit, __fput() will think that everything is OK,
388 * and move on to freeing struct file. remove_proc_entry() will
389 * find slacker in opener's list and will try to do non-trivial
390 * things with struct file. Therefore, remove opener from list.
392 * But if opener is removed from list, who will ->release it?
396 spin_unlock(&pde->pde_unload_lock);
397 rv = pdeo->release(inode, file);
400 spin_unlock(&pde->pde_unload_lock);
404 release = pde->proc_fops->release;
409 spin_unlock(&pde->pde_unload_lock);
412 rv = release(inode, file);
418 static const struct file_operations proc_reg_file_ops = {
419 .llseek = proc_reg_llseek,
420 .read = proc_reg_read,
421 .write = proc_reg_write,
422 .poll = proc_reg_poll,
423 .unlocked_ioctl = proc_reg_unlocked_ioctl,
425 .compat_ioctl = proc_reg_compat_ioctl,
427 .mmap = proc_reg_mmap,
428 .open = proc_reg_open,
429 .release = proc_reg_release,
433 static const struct file_operations proc_reg_file_ops_no_compat = {
434 .llseek = proc_reg_llseek,
435 .read = proc_reg_read,
436 .write = proc_reg_write,
437 .poll = proc_reg_poll,
438 .unlocked_ioctl = proc_reg_unlocked_ioctl,
439 .mmap = proc_reg_mmap,
440 .open = proc_reg_open,
441 .release = proc_reg_release,
445 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
447 struct inode * inode;
449 inode = iget_locked(sb, de->low_ino);
452 if (inode->i_state & I_NEW) {
453 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
454 PROC_I(inode)->fd = 0;
455 PROC_I(inode)->pde = de;
458 inode->i_mode = de->mode;
459 inode->i_uid = de->uid;
460 inode->i_gid = de->gid;
463 inode->i_size = de->size;
465 set_nlink(inode, de->nlink);
467 inode->i_op = de->proc_iops;
469 if (S_ISREG(inode->i_mode)) {
471 if (!de->proc_fops->compat_ioctl)
473 &proc_reg_file_ops_no_compat;
476 inode->i_fop = &proc_reg_file_ops;
478 inode->i_fop = de->proc_fops;
481 unlock_new_inode(inode);
487 int proc_fill_super(struct super_block *s)
489 s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
490 s->s_blocksize = 1024;
491 s->s_blocksize_bits = 10;
492 s->s_magic = PROC_SUPER_MAGIC;
493 s->s_op = &proc_sops;
497 s->s_root = d_make_root(proc_get_inode(s, &proc_root));
501 printk("proc_read_super: get root inode failed\n");