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>
11 #include <linux/string.h>
12 #include <linux/stat.h>
13 #include <linux/completion.h>
14 #include <linux/poll.h>
15 #include <linux/file.h>
16 #include <linux/limits.h>
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/sysctl.h>
20 #include <linux/slab.h>
22 #include <asm/system.h>
23 #include <asm/uaccess.h>
27 static void proc_evict_inode(struct inode *inode)
29 struct proc_dir_entry *de;
30 struct ctl_table_header *head;
31 const struct proc_ns_operations *ns_ops;
33 truncate_inode_pages(&inode->i_data, 0);
36 /* Stop tracking associated processes */
37 put_pid(PROC_I(inode)->pid);
39 /* Let go of any associated proc directory entry */
40 de = PROC_I(inode)->pde;
43 head = PROC_I(inode)->sysctl;
45 rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
46 sysctl_head_put(head);
48 /* Release any associated namespace */
49 ns_ops = PROC_I(inode)->ns_ops;
50 if (ns_ops && ns_ops->put)
51 ns_ops->put(PROC_I(inode)->ns);
54 static struct kmem_cache * proc_inode_cachep;
56 static struct inode *proc_alloc_inode(struct super_block *sb)
58 struct proc_inode *ei;
61 ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
66 ei->op.proc_get_link = NULL;
69 ei->sysctl_entry = NULL;
72 inode = &ei->vfs_inode;
73 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
77 static void proc_i_callback(struct rcu_head *head)
79 struct inode *inode = container_of(head, struct inode, i_rcu);
80 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
83 static void proc_destroy_inode(struct inode *inode)
85 call_rcu(&inode->i_rcu, proc_i_callback);
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_inodecache(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_PANIC),
104 static const struct super_operations proc_sops = {
105 .alloc_inode = proc_alloc_inode,
106 .destroy_inode = proc_destroy_inode,
107 .drop_inode = generic_delete_inode,
108 .evict_inode = proc_evict_inode,
109 .statfs = simple_statfs,
112 static void __pde_users_dec(struct proc_dir_entry *pde)
115 if (pde->pde_unload_completion && pde->pde_users == 0)
116 complete(pde->pde_unload_completion);
119 void pde_users_dec(struct proc_dir_entry *pde)
121 spin_lock(&pde->pde_unload_lock);
122 __pde_users_dec(pde);
123 spin_unlock(&pde->pde_unload_lock);
126 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
128 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
130 loff_t (*llseek)(struct file *, loff_t, int);
132 spin_lock(&pde->pde_unload_lock);
134 * remove_proc_entry() is going to delete PDE (as part of module
135 * cleanup sequence). No new callers into module allowed.
137 if (!pde->proc_fops) {
138 spin_unlock(&pde->pde_unload_lock);
142 * Bump refcount so that remove_proc_entry will wail for ->llseek to
147 * Save function pointer under lock, to protect against ->proc_fops
148 * NULL'ifying right after ->pde_unload_lock is dropped.
150 llseek = pde->proc_fops->llseek;
151 spin_unlock(&pde->pde_unload_lock);
154 llseek = default_llseek;
155 rv = llseek(file, offset, whence);
161 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
163 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
165 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
167 spin_lock(&pde->pde_unload_lock);
168 if (!pde->proc_fops) {
169 spin_unlock(&pde->pde_unload_lock);
173 read = pde->proc_fops->read;
174 spin_unlock(&pde->pde_unload_lock);
177 rv = read(file, buf, count, ppos);
183 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
185 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
187 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
189 spin_lock(&pde->pde_unload_lock);
190 if (!pde->proc_fops) {
191 spin_unlock(&pde->pde_unload_lock);
195 write = pde->proc_fops->write;
196 spin_unlock(&pde->pde_unload_lock);
199 rv = write(file, buf, count, ppos);
205 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
207 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
208 unsigned int rv = DEFAULT_POLLMASK;
209 unsigned int (*poll)(struct file *, struct poll_table_struct *);
211 spin_lock(&pde->pde_unload_lock);
212 if (!pde->proc_fops) {
213 spin_unlock(&pde->pde_unload_lock);
217 poll = pde->proc_fops->poll;
218 spin_unlock(&pde->pde_unload_lock);
221 rv = poll(file, pts);
227 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
229 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
231 long (*ioctl)(struct file *, unsigned int, unsigned long);
233 spin_lock(&pde->pde_unload_lock);
234 if (!pde->proc_fops) {
235 spin_unlock(&pde->pde_unload_lock);
239 ioctl = pde->proc_fops->unlocked_ioctl;
240 spin_unlock(&pde->pde_unload_lock);
243 rv = ioctl(file, cmd, arg);
250 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
252 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
254 long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
256 spin_lock(&pde->pde_unload_lock);
257 if (!pde->proc_fops) {
258 spin_unlock(&pde->pde_unload_lock);
262 compat_ioctl = pde->proc_fops->compat_ioctl;
263 spin_unlock(&pde->pde_unload_lock);
266 rv = compat_ioctl(file, cmd, arg);
273 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
275 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
277 int (*mmap)(struct file *, struct vm_area_struct *);
279 spin_lock(&pde->pde_unload_lock);
280 if (!pde->proc_fops) {
281 spin_unlock(&pde->pde_unload_lock);
285 mmap = pde->proc_fops->mmap;
286 spin_unlock(&pde->pde_unload_lock);
289 rv = mmap(file, vma);
295 static int proc_reg_open(struct inode *inode, struct file *file)
297 struct proc_dir_entry *pde = PDE(inode);
299 int (*open)(struct inode *, struct file *);
300 int (*release)(struct inode *, struct file *);
301 struct pde_opener *pdeo;
304 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
305 * sequence. ->release won't be called because ->proc_fops will be
306 * cleared. Depending on complexity of ->release, consequences vary.
308 * We can't wait for mercy when close will be done for real, it's
309 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
310 * by hand in remove_proc_entry(). For this, save opener's credentials
313 pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);
317 spin_lock(&pde->pde_unload_lock);
318 if (!pde->proc_fops) {
319 spin_unlock(&pde->pde_unload_lock);
324 open = pde->proc_fops->open;
325 release = pde->proc_fops->release;
326 spin_unlock(&pde->pde_unload_lock);
329 rv = open(inode, file);
331 spin_lock(&pde->pde_unload_lock);
332 if (rv == 0 && release) {
333 /* To know what to release. */
336 /* Strictly for "too late" ->release in proc_reg_release(). */
337 pdeo->release = release;
338 list_add(&pdeo->lh, &pde->pde_openers);
341 __pde_users_dec(pde);
342 spin_unlock(&pde->pde_unload_lock);
346 static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde,
347 struct inode *inode, struct file *file)
349 struct pde_opener *pdeo;
351 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
352 if (pdeo->inode == inode && pdeo->file == file)
358 static int proc_reg_release(struct inode *inode, struct file *file)
360 struct proc_dir_entry *pde = PDE(inode);
362 int (*release)(struct inode *, struct file *);
363 struct pde_opener *pdeo;
365 spin_lock(&pde->pde_unload_lock);
366 pdeo = find_pde_opener(pde, inode, file);
367 if (!pde->proc_fops) {
369 * Can't simply exit, __fput() will think that everything is OK,
370 * and move on to freeing struct file. remove_proc_entry() will
371 * find slacker in opener's list and will try to do non-trivial
372 * things with struct file. Therefore, remove opener from list.
374 * But if opener is removed from list, who will ->release it?
378 spin_unlock(&pde->pde_unload_lock);
379 rv = pdeo->release(inode, file);
382 spin_unlock(&pde->pde_unload_lock);
386 release = pde->proc_fops->release;
391 spin_unlock(&pde->pde_unload_lock);
394 rv = release(inode, file);
400 static const struct file_operations proc_reg_file_ops = {
401 .llseek = proc_reg_llseek,
402 .read = proc_reg_read,
403 .write = proc_reg_write,
404 .poll = proc_reg_poll,
405 .unlocked_ioctl = proc_reg_unlocked_ioctl,
407 .compat_ioctl = proc_reg_compat_ioctl,
409 .mmap = proc_reg_mmap,
410 .open = proc_reg_open,
411 .release = proc_reg_release,
415 static const struct file_operations proc_reg_file_ops_no_compat = {
416 .llseek = proc_reg_llseek,
417 .read = proc_reg_read,
418 .write = proc_reg_write,
419 .poll = proc_reg_poll,
420 .unlocked_ioctl = proc_reg_unlocked_ioctl,
421 .mmap = proc_reg_mmap,
422 .open = proc_reg_open,
423 .release = proc_reg_release,
427 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
429 struct inode * inode;
431 inode = iget_locked(sb, de->low_ino);
434 if (inode->i_state & I_NEW) {
435 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
436 PROC_I(inode)->fd = 0;
437 PROC_I(inode)->pde = de;
440 inode->i_mode = de->mode;
441 inode->i_uid = de->uid;
442 inode->i_gid = de->gid;
445 inode->i_size = de->size;
447 set_nlink(inode, de->nlink);
449 inode->i_op = de->proc_iops;
451 if (S_ISREG(inode->i_mode)) {
453 if (!de->proc_fops->compat_ioctl)
455 &proc_reg_file_ops_no_compat;
458 inode->i_fop = &proc_reg_file_ops;
460 inode->i_fop = de->proc_fops;
463 unlock_new_inode(inode);
469 int proc_fill_super(struct super_block *s)
471 struct inode * root_inode;
473 s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
474 s->s_blocksize = 1024;
475 s->s_blocksize_bits = 10;
476 s->s_magic = PROC_SUPER_MAGIC;
477 s->s_op = &proc_sops;
481 root_inode = proc_get_inode(s, &proc_root);
484 root_inode->i_uid = 0;
485 root_inode->i_gid = 0;
486 s->s_root = d_alloc_root(root_inode);
492 printk("proc_read_super: get root inode failed\n");