1/*
2 *  linux/fs/proc/inode.c
3 *
4 *  Copyright (C) 1991, 1992  Linus Torvalds
5 */
6
7#include <linux/time.h>
8#include <linux/proc_fs.h>
9#include <linux/kernel.h>
10#include <linux/pid_namespace.h>
11#include <linux/mm.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>
25#include <linux/magic.h>
26#include <linux/namei.h>
27
28#include <asm/uaccess.h>
29
30#include "internal.h"
31
32static void proc_evict_inode(struct inode *inode)
33{
34	struct proc_dir_entry *de;
35	struct ctl_table_header *head;
36
37	truncate_inode_pages_final(&inode->i_data);
38	clear_inode(inode);
39
40	/* Stop tracking associated processes */
41	put_pid(PROC_I(inode)->pid);
42
43	/* Let go of any associated proc directory entry */
44	de = PDE(inode);
45	if (de)
46		pde_put(de);
47	head = PROC_I(inode)->sysctl;
48	if (head) {
49		RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL);
50		sysctl_head_put(head);
51	}
52}
53
54static struct kmem_cache * proc_inode_cachep;
55
56static struct inode *proc_alloc_inode(struct super_block *sb)
57{
58	struct proc_inode *ei;
59	struct inode *inode;
60
61	ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
62	if (!ei)
63		return NULL;
64	ei->pid = NULL;
65	ei->fd = 0;
66	ei->op.proc_get_link = NULL;
67	ei->pde = NULL;
68	ei->sysctl = NULL;
69	ei->sysctl_entry = NULL;
70	ei->ns_ops = NULL;
71	inode = &ei->vfs_inode;
72	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
73	return inode;
74}
75
76static void proc_i_callback(struct rcu_head *head)
77{
78	struct inode *inode = container_of(head, struct inode, i_rcu);
79	kmem_cache_free(proc_inode_cachep, PROC_I(inode));
80}
81
82static void proc_destroy_inode(struct inode *inode)
83{
84	call_rcu(&inode->i_rcu, proc_i_callback);
85}
86
87static void init_once(void *foo)
88{
89	struct proc_inode *ei = (struct proc_inode *) foo;
90
91	inode_init_once(&ei->vfs_inode);
92}
93
94void __init proc_init_inodecache(void)
95{
96	proc_inode_cachep = kmem_cache_create("proc_inode_cache",
97					     sizeof(struct proc_inode),
98					     0, (SLAB_RECLAIM_ACCOUNT|
99						SLAB_MEM_SPREAD|SLAB_PANIC),
100					     init_once);
101}
102
103static int proc_show_options(struct seq_file *seq, struct dentry *root)
104{
105	struct super_block *sb = root->d_sb;
106	struct pid_namespace *pid = sb->s_fs_info;
107
108	if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
109		seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
110	if (pid->hide_pid != 0)
111		seq_printf(seq, ",hidepid=%u", pid->hide_pid);
112
113	return 0;
114}
115
116static const struct super_operations proc_sops = {
117	.alloc_inode	= proc_alloc_inode,
118	.destroy_inode	= proc_destroy_inode,
119	.drop_inode	= generic_delete_inode,
120	.evict_inode	= proc_evict_inode,
121	.statfs		= simple_statfs,
122	.remount_fs	= proc_remount,
123	.show_options	= proc_show_options,
124};
125
126enum {BIAS = -1U<<31};
127
128static inline int use_pde(struct proc_dir_entry *pde)
129{
130	return atomic_inc_unless_negative(&pde->in_use);
131}
132
133static void unuse_pde(struct proc_dir_entry *pde)
134{
135	if (atomic_dec_return(&pde->in_use) == BIAS)
136		complete(pde->pde_unload_completion);
137}
138
139/* pde is locked */
140static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
141{
142	if (pdeo->closing) {
143		/* somebody else is doing that, just wait */
144		DECLARE_COMPLETION_ONSTACK(c);
145		pdeo->c = &c;
146		spin_unlock(&pde->pde_unload_lock);
147		wait_for_completion(&c);
148		spin_lock(&pde->pde_unload_lock);
149	} else {
150		struct file *file;
151		pdeo->closing = 1;
152		spin_unlock(&pde->pde_unload_lock);
153		file = pdeo->file;
154		pde->proc_fops->release(file_inode(file), file);
155		spin_lock(&pde->pde_unload_lock);
156		list_del_init(&pdeo->lh);
157		if (pdeo->c)
158			complete(pdeo->c);
159		kfree(pdeo);
160	}
161}
162
163void proc_entry_rundown(struct proc_dir_entry *de)
164{
165	DECLARE_COMPLETION_ONSTACK(c);
166	/* Wait until all existing callers into module are done. */
167	de->pde_unload_completion = &c;
168	if (atomic_add_return(BIAS, &de->in_use) != BIAS)
169		wait_for_completion(&c);
170
171	spin_lock(&de->pde_unload_lock);
172	while (!list_empty(&de->pde_openers)) {
173		struct pde_opener *pdeo;
174		pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
175		close_pdeo(de, pdeo);
176	}
177	spin_unlock(&de->pde_unload_lock);
178}
179
180static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
181{
182	struct proc_dir_entry *pde = PDE(file_inode(file));
183	loff_t rv = -EINVAL;
184	if (use_pde(pde)) {
185		loff_t (*llseek)(struct file *, loff_t, int);
186		llseek = pde->proc_fops->llseek;
187		if (!llseek)
188			llseek = default_llseek;
189		rv = llseek(file, offset, whence);
190		unuse_pde(pde);
191	}
192	return rv;
193}
194
195static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
196{
197	ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
198	struct proc_dir_entry *pde = PDE(file_inode(file));
199	ssize_t rv = -EIO;
200	if (use_pde(pde)) {
201		read = pde->proc_fops->read;
202		if (read)
203			rv = read(file, buf, count, ppos);
204		unuse_pde(pde);
205	}
206	return rv;
207}
208
209static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
210{
211	ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
212	struct proc_dir_entry *pde = PDE(file_inode(file));
213	ssize_t rv = -EIO;
214	if (use_pde(pde)) {
215		write = pde->proc_fops->write;
216		if (write)
217			rv = write(file, buf, count, ppos);
218		unuse_pde(pde);
219	}
220	return rv;
221}
222
223static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
224{
225	struct proc_dir_entry *pde = PDE(file_inode(file));
226	unsigned int rv = DEFAULT_POLLMASK;
227	unsigned int (*poll)(struct file *, struct poll_table_struct *);
228	if (use_pde(pde)) {
229		poll = pde->proc_fops->poll;
230		if (poll)
231			rv = poll(file, pts);
232		unuse_pde(pde);
233	}
234	return rv;
235}
236
237static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
238{
239	struct proc_dir_entry *pde = PDE(file_inode(file));
240	long rv = -ENOTTY;
241	long (*ioctl)(struct file *, unsigned int, unsigned long);
242	if (use_pde(pde)) {
243		ioctl = pde->proc_fops->unlocked_ioctl;
244		if (ioctl)
245			rv = ioctl(file, cmd, arg);
246		unuse_pde(pde);
247	}
248	return rv;
249}
250
251#ifdef CONFIG_COMPAT
252static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
253{
254	struct proc_dir_entry *pde = PDE(file_inode(file));
255	long rv = -ENOTTY;
256	long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
257	if (use_pde(pde)) {
258		compat_ioctl = pde->proc_fops->compat_ioctl;
259		if (compat_ioctl)
260			rv = compat_ioctl(file, cmd, arg);
261		unuse_pde(pde);
262	}
263	return rv;
264}
265#endif
266
267static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
268{
269	struct proc_dir_entry *pde = PDE(file_inode(file));
270	int rv = -EIO;
271	int (*mmap)(struct file *, struct vm_area_struct *);
272	if (use_pde(pde)) {
273		mmap = pde->proc_fops->mmap;
274		if (mmap)
275			rv = mmap(file, vma);
276		unuse_pde(pde);
277	}
278	return rv;
279}
280
281static unsigned long
282proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
283			   unsigned long len, unsigned long pgoff,
284			   unsigned long flags)
285{
286	struct proc_dir_entry *pde = PDE(file_inode(file));
287	unsigned long rv = -EIO;
288
289	if (use_pde(pde)) {
290		typeof(proc_reg_get_unmapped_area) *get_area;
291
292		get_area = pde->proc_fops->get_unmapped_area;
293#ifdef CONFIG_MMU
294		if (!get_area)
295			get_area = current->mm->get_unmapped_area;
296#endif
297
298		if (get_area)
299			rv = get_area(file, orig_addr, len, pgoff, flags);
300		else
301			rv = orig_addr;
302		unuse_pde(pde);
303	}
304	return rv;
305}
306
307static int proc_reg_open(struct inode *inode, struct file *file)
308{
309	struct proc_dir_entry *pde = PDE(inode);
310	int rv = 0;
311	int (*open)(struct inode *, struct file *);
312	int (*release)(struct inode *, struct file *);
313	struct pde_opener *pdeo;
314
315	/*
316	 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
317	 * sequence. ->release won't be called because ->proc_fops will be
318	 * cleared. Depending on complexity of ->release, consequences vary.
319	 *
320	 * We can't wait for mercy when close will be done for real, it's
321	 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
322	 * by hand in remove_proc_entry(). For this, save opener's credentials
323	 * for later.
324	 */
325	pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
326	if (!pdeo)
327		return -ENOMEM;
328
329	if (!use_pde(pde)) {
330		kfree(pdeo);
331		return -ENOENT;
332	}
333	open = pde->proc_fops->open;
334	release = pde->proc_fops->release;
335
336	if (open)
337		rv = open(inode, file);
338
339	if (rv == 0 && release) {
340		/* To know what to release. */
341		pdeo->file = file;
342		/* Strictly for "too late" ->release in proc_reg_release(). */
343		spin_lock(&pde->pde_unload_lock);
344		list_add(&pdeo->lh, &pde->pde_openers);
345		spin_unlock(&pde->pde_unload_lock);
346	} else
347		kfree(pdeo);
348
349	unuse_pde(pde);
350	return rv;
351}
352
353static int proc_reg_release(struct inode *inode, struct file *file)
354{
355	struct proc_dir_entry *pde = PDE(inode);
356	struct pde_opener *pdeo;
357	spin_lock(&pde->pde_unload_lock);
358	list_for_each_entry(pdeo, &pde->pde_openers, lh) {
359		if (pdeo->file == file) {
360			close_pdeo(pde, pdeo);
361			break;
362		}
363	}
364	spin_unlock(&pde->pde_unload_lock);
365	return 0;
366}
367
368static const struct file_operations proc_reg_file_ops = {
369	.llseek		= proc_reg_llseek,
370	.read		= proc_reg_read,
371	.write		= proc_reg_write,
372	.poll		= proc_reg_poll,
373	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
374#ifdef CONFIG_COMPAT
375	.compat_ioctl	= proc_reg_compat_ioctl,
376#endif
377	.mmap		= proc_reg_mmap,
378	.get_unmapped_area = proc_reg_get_unmapped_area,
379	.open		= proc_reg_open,
380	.release	= proc_reg_release,
381};
382
383#ifdef CONFIG_COMPAT
384static const struct file_operations proc_reg_file_ops_no_compat = {
385	.llseek		= proc_reg_llseek,
386	.read		= proc_reg_read,
387	.write		= proc_reg_write,
388	.poll		= proc_reg_poll,
389	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
390	.mmap		= proc_reg_mmap,
391	.get_unmapped_area = proc_reg_get_unmapped_area,
392	.open		= proc_reg_open,
393	.release	= proc_reg_release,
394};
395#endif
396
397static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
398{
399	struct proc_dir_entry *pde = PDE(d_inode(dentry));
400	if (unlikely(!use_pde(pde)))
401		return ERR_PTR(-EINVAL);
402	nd_set_link(nd, pde->data);
403	return pde;
404}
405
406static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
407{
408	unuse_pde(p);
409}
410
411const struct inode_operations proc_link_inode_operations = {
412	.readlink	= generic_readlink,
413	.follow_link	= proc_follow_link,
414	.put_link	= proc_put_link,
415};
416
417struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
418{
419	struct inode *inode = new_inode_pseudo(sb);
420
421	if (inode) {
422		inode->i_ino = de->low_ino;
423		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
424		PROC_I(inode)->pde = de;
425
426		if (is_empty_pde(de)) {
427			make_empty_dir_inode(inode);
428			return inode;
429		}
430		if (de->mode) {
431			inode->i_mode = de->mode;
432			inode->i_uid = de->uid;
433			inode->i_gid = de->gid;
434		}
435		if (de->size)
436			inode->i_size = de->size;
437		if (de->nlink)
438			set_nlink(inode, de->nlink);
439		WARN_ON(!de->proc_iops);
440		inode->i_op = de->proc_iops;
441		if (de->proc_fops) {
442			if (S_ISREG(inode->i_mode)) {
443#ifdef CONFIG_COMPAT
444				if (!de->proc_fops->compat_ioctl)
445					inode->i_fop =
446						&proc_reg_file_ops_no_compat;
447				else
448#endif
449					inode->i_fop = &proc_reg_file_ops;
450			} else {
451				inode->i_fop = de->proc_fops;
452			}
453		}
454	} else
455	       pde_put(de);
456	return inode;
457}
458
459int proc_fill_super(struct super_block *s)
460{
461	struct inode *root_inode;
462	int ret;
463
464	s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
465	s->s_blocksize = 1024;
466	s->s_blocksize_bits = 10;
467	s->s_magic = PROC_SUPER_MAGIC;
468	s->s_op = &proc_sops;
469	s->s_time_gran = 1;
470
471	pde_get(&proc_root);
472	root_inode = proc_get_inode(s, &proc_root);
473	if (!root_inode) {
474		pr_err("proc_fill_super: get root inode failed\n");
475		return -ENOMEM;
476	}
477
478	s->s_root = d_make_root(root_inode);
479	if (!s->s_root) {
480		pr_err("proc_fill_super: allocate dentry failed\n");
481		return -ENOMEM;
482	}
483
484	ret = proc_setup_self(s);
485	if (ret) {
486		return ret;
487	}
488	return proc_setup_thread_self(s);
489}
490