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/printk.h>
17 #include <linux/file.h>
18 #include <linux/limits.h>
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/sysctl.h>
22 #include <linux/seq_file.h>
23 #include <linux/slab.h>
24 #include <linux/mount.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;
37 truncate_inode_pages(&inode->i_data, 0);
40 /* Stop tracking associated processes */
41 put_pid(PROC_I(inode)->pid);
43 /* Let go of any associated proc directory entry */
44 de = PROC_I(inode)->pde;
47 head = PROC_I(inode)->sysctl;
49 rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
50 sysctl_head_put(head);
52 /* Release any associated namespace */
53 ns_ops = PROC_I(inode)->ns_ops;
54 ns = PROC_I(inode)->ns;
59 static struct kmem_cache * proc_inode_cachep;
61 static struct inode *proc_alloc_inode(struct super_block *sb)
63 struct proc_inode *ei;
66 ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
71 ei->op.proc_get_link = NULL;
74 ei->sysctl_entry = NULL;
77 inode = &ei->vfs_inode;
78 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
82 static void proc_i_callback(struct rcu_head *head)
84 struct inode *inode = container_of(head, struct inode, i_rcu);
85 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
88 static void proc_destroy_inode(struct inode *inode)
90 call_rcu(&inode->i_rcu, proc_i_callback);
93 static void init_once(void *foo)
95 struct proc_inode *ei = (struct proc_inode *) foo;
97 inode_init_once(&ei->vfs_inode);
100 void __init proc_init_inodecache(void)
102 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
103 sizeof(struct proc_inode),
104 0, (SLAB_RECLAIM_ACCOUNT|
105 SLAB_MEM_SPREAD|SLAB_PANIC),
109 static int proc_show_options(struct seq_file *seq, struct dentry *root)
111 struct super_block *sb = root->d_sb;
112 struct pid_namespace *pid = sb->s_fs_info;
114 if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
115 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
116 if (pid->hide_pid != 0)
117 seq_printf(seq, ",hidepid=%u", pid->hide_pid);
122 static const struct super_operations proc_sops = {
123 .alloc_inode = proc_alloc_inode,
124 .destroy_inode = proc_destroy_inode,
125 .drop_inode = generic_delete_inode,
126 .evict_inode = proc_evict_inode,
127 .statfs = simple_statfs,
128 .remount_fs = proc_remount,
129 .show_options = proc_show_options,
132 enum {BIAS = -1U<<31};
134 static inline int use_pde(struct proc_dir_entry *pde)
136 return atomic_inc_unless_negative(&pde->in_use);
139 static void unuse_pde(struct proc_dir_entry *pde)
141 if (atomic_dec_return(&pde->in_use) == BIAS)
142 complete(pde->pde_unload_completion);
146 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
149 /* somebody else is doing that, just wait */
150 DECLARE_COMPLETION_ONSTACK(c);
152 spin_unlock(&pde->pde_unload_lock);
153 wait_for_completion(&c);
154 spin_lock(&pde->pde_unload_lock);
158 spin_unlock(&pde->pde_unload_lock);
160 pde->proc_fops->release(file_inode(file), file);
161 spin_lock(&pde->pde_unload_lock);
162 list_del_init(&pdeo->lh);
169 void proc_entry_rundown(struct proc_dir_entry *de)
171 DECLARE_COMPLETION_ONSTACK(c);
172 /* Wait until all existing callers into module are done. */
173 de->pde_unload_completion = &c;
174 if (atomic_add_return(BIAS, &de->in_use) != BIAS)
175 wait_for_completion(&c);
177 spin_lock(&de->pde_unload_lock);
178 while (!list_empty(&de->pde_openers)) {
179 struct pde_opener *pdeo;
180 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
181 close_pdeo(de, pdeo);
183 spin_unlock(&de->pde_unload_lock);
186 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
188 struct proc_dir_entry *pde = PDE(file_inode(file));
191 loff_t (*llseek)(struct file *, loff_t, int);
192 llseek = pde->proc_fops->llseek;
194 llseek = default_llseek;
195 rv = llseek(file, offset, whence);
201 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
203 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
204 struct proc_dir_entry *pde = PDE(file_inode(file));
207 read = pde->proc_fops->read;
209 rv = read(file, buf, count, ppos);
215 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
217 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
218 struct proc_dir_entry *pde = PDE(file_inode(file));
221 write = pde->proc_fops->write;
223 rv = write(file, buf, count, ppos);
229 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
231 struct proc_dir_entry *pde = PDE(file_inode(file));
232 unsigned int rv = DEFAULT_POLLMASK;
233 unsigned int (*poll)(struct file *, struct poll_table_struct *);
235 poll = pde->proc_fops->poll;
237 rv = poll(file, pts);
243 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
245 struct proc_dir_entry *pde = PDE(file_inode(file));
247 long (*ioctl)(struct file *, unsigned int, unsigned long);
249 ioctl = pde->proc_fops->unlocked_ioctl;
251 rv = ioctl(file, cmd, arg);
258 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
260 struct proc_dir_entry *pde = PDE(file_inode(file));
262 long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
264 compat_ioctl = pde->proc_fops->compat_ioctl;
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_inode(file));
277 int (*mmap)(struct file *, struct vm_area_struct *);
279 mmap = pde->proc_fops->mmap;
281 rv = mmap(file, vma);
287 static int proc_reg_open(struct inode *inode, struct file *file)
289 struct proc_dir_entry *pde = PDE(inode);
291 int (*open)(struct inode *, struct file *);
292 int (*release)(struct inode *, struct file *);
293 struct pde_opener *pdeo;
296 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
297 * sequence. ->release won't be called because ->proc_fops will be
298 * cleared. Depending on complexity of ->release, consequences vary.
300 * We can't wait for mercy when close will be done for real, it's
301 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
302 * by hand in remove_proc_entry(). For this, save opener's credentials
305 pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
313 open = pde->proc_fops->open;
314 release = pde->proc_fops->release;
317 rv = open(inode, file);
319 if (rv == 0 && release) {
320 /* To know what to release. */
322 /* Strictly for "too late" ->release in proc_reg_release(). */
323 spin_lock(&pde->pde_unload_lock);
324 list_add(&pdeo->lh, &pde->pde_openers);
325 spin_unlock(&pde->pde_unload_lock);
333 static int proc_reg_release(struct inode *inode, struct file *file)
335 struct proc_dir_entry *pde = PDE(inode);
336 struct pde_opener *pdeo;
337 spin_lock(&pde->pde_unload_lock);
338 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
339 if (pdeo->file == file) {
340 close_pdeo(pde, pdeo);
344 spin_unlock(&pde->pde_unload_lock);
348 static const struct file_operations proc_reg_file_ops = {
349 .llseek = proc_reg_llseek,
350 .read = proc_reg_read,
351 .write = proc_reg_write,
352 .poll = proc_reg_poll,
353 .unlocked_ioctl = proc_reg_unlocked_ioctl,
355 .compat_ioctl = proc_reg_compat_ioctl,
357 .mmap = proc_reg_mmap,
358 .open = proc_reg_open,
359 .release = proc_reg_release,
363 static const struct file_operations proc_reg_file_ops_no_compat = {
364 .llseek = proc_reg_llseek,
365 .read = proc_reg_read,
366 .write = proc_reg_write,
367 .poll = proc_reg_poll,
368 .unlocked_ioctl = proc_reg_unlocked_ioctl,
369 .mmap = proc_reg_mmap,
370 .open = proc_reg_open,
371 .release = proc_reg_release,
375 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
377 struct inode *inode = new_inode_pseudo(sb);
380 inode->i_ino = de->low_ino;
381 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
382 PROC_I(inode)->pde = de;
385 inode->i_mode = de->mode;
386 inode->i_uid = de->uid;
387 inode->i_gid = de->gid;
390 inode->i_size = de->size;
392 set_nlink(inode, de->nlink);
393 WARN_ON(!de->proc_iops);
394 inode->i_op = de->proc_iops;
396 if (S_ISREG(inode->i_mode)) {
398 if (!de->proc_fops->compat_ioctl)
400 &proc_reg_file_ops_no_compat;
403 inode->i_fop = &proc_reg_file_ops;
405 inode->i_fop = de->proc_fops;
413 int proc_fill_super(struct super_block *s)
415 struct inode *root_inode;
417 s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
418 s->s_blocksize = 1024;
419 s->s_blocksize_bits = 10;
420 s->s_magic = PROC_SUPER_MAGIC;
421 s->s_op = &proc_sops;
425 root_inode = proc_get_inode(s, &proc_root);
427 pr_err("proc_fill_super: get root inode failed\n");
431 s->s_root = d_make_root(root_inode);
433 pr_err("proc_fill_super: allocate dentry failed\n");
437 return proc_setup_self(s);