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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- linux-c -*- --------------------------------------------------------- *
2 *
3 * linux/fs/devpts/inode.c
4 *
5 * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
6 *
7 * This file is part of the Linux kernel and is made available under
8 * the terms of the GNU General Public License, version 2, or at your
9 * option, any later version, incorporated herein by reference.
10 *
11 * ------------------------------------------------------------------------- */
12
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/fs.h>
16#include <linux/sched.h>
17#include <linux/namei.h>
18#include <linux/mount.h>
19#include <linux/tty.h>
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070020#include <linux/mutex.h>
21#include <linux/idr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/devpts_fs.h>
Domen Puncer7a673c62006-03-23 03:00:59 -080023#include <linux/parser.h>
Florin Malita3972b7f2007-05-08 00:24:18 -070024#include <linux/fsnotify.h>
Miklos Szeredib87a2672008-02-08 04:21:41 -080025#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
27#define DEVPTS_SUPER_MAGIC 0x1cd1
28
Miklos Szeredib87a2672008-02-08 04:21:41 -080029#define DEVPTS_DEFAULT_MODE 0600
30
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070031extern int pty_limit; /* Config limit on Unix98 ptys */
32static DEFINE_IDR(allocated_ptys);
33static DEFINE_MUTEX(allocated_ptys_lock);
34
Linus Torvalds1da177e2005-04-16 15:20:36 -070035static struct vfsmount *devpts_mnt;
36static struct dentry *devpts_root;
37
38static struct {
39 int setuid;
40 int setgid;
41 uid_t uid;
42 gid_t gid;
43 umode_t mode;
Miklos Szeredib87a2672008-02-08 04:21:41 -080044} config = {.mode = DEVPTS_DEFAULT_MODE};
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
Domen Puncer7a673c62006-03-23 03:00:59 -080046enum {
47 Opt_uid, Opt_gid, Opt_mode,
48 Opt_err
49};
50
51static match_table_t tokens = {
52 {Opt_uid, "uid=%u"},
53 {Opt_gid, "gid=%u"},
54 {Opt_mode, "mode=%o"},
55 {Opt_err, NULL}
56};
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058static int devpts_remount(struct super_block *sb, int *flags, char *data)
59{
Domen Puncer7a673c62006-03-23 03:00:59 -080060 char *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
Domen Puncer7a673c62006-03-23 03:00:59 -080062 config.setuid = 0;
63 config.setgid = 0;
64 config.uid = 0;
65 config.gid = 0;
Miklos Szeredib87a2672008-02-08 04:21:41 -080066 config.mode = DEVPTS_DEFAULT_MODE;
Domen Puncer7a673c62006-03-23 03:00:59 -080067
68 while ((p = strsep(&data, ",")) != NULL) {
69 substring_t args[MAX_OPT_ARGS];
70 int token;
71 int option;
72
73 if (!*p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 continue;
Domen Puncer7a673c62006-03-23 03:00:59 -080075
76 token = match_token(p, tokens, args);
77 switch (token) {
78 case Opt_uid:
79 if (match_int(&args[0], &option))
80 return -EINVAL;
81 config.uid = option;
82 config.setuid = 1;
83 break;
84 case Opt_gid:
85 if (match_int(&args[0], &option))
86 return -EINVAL;
87 config.gid = option;
88 config.setgid = 1;
89 break;
90 case Opt_mode:
91 if (match_octal(&args[0], &option))
92 return -EINVAL;
Miklos Szeredib87a2672008-02-08 04:21:41 -080093 config.mode = option & S_IALLUGO;
Domen Puncer7a673c62006-03-23 03:00:59 -080094 break;
95 default:
96 printk(KERN_ERR "devpts: called with bogus options\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 return -EINVAL;
98 }
99 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
101 return 0;
102}
103
Miklos Szeredib87a2672008-02-08 04:21:41 -0800104static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
105{
106 if (config.setuid)
107 seq_printf(seq, ",uid=%u", config.uid);
108 if (config.setgid)
109 seq_printf(seq, ",gid=%u", config.gid);
110 seq_printf(seq, ",mode=%03o", config.mode);
111
112 return 0;
113}
114
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800115static const struct super_operations devpts_sops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 .statfs = simple_statfs,
117 .remount_fs = devpts_remount,
Miklos Szeredib87a2672008-02-08 04:21:41 -0800118 .show_options = devpts_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119};
120
121static int
122devpts_fill_super(struct super_block *s, void *data, int silent)
123{
124 struct inode * inode;
125
126 s->s_blocksize = 1024;
127 s->s_blocksize_bits = 10;
128 s->s_magic = DEVPTS_SUPER_MAGIC;
129 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 s->s_time_gran = 1;
131
132 inode = new_inode(s);
133 if (!inode)
134 goto fail;
135 inode->i_ino = 1;
136 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
137 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 inode->i_uid = inode->i_gid = 0;
139 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
140 inode->i_op = &simple_dir_inode_operations;
141 inode->i_fop = &simple_dir_operations;
142 inode->i_nlink = 2;
143
144 devpts_root = s->s_root = d_alloc_root(inode);
145 if (s->s_root)
146 return 0;
147
148 printk("devpts: get root dentry failed\n");
149 iput(inode);
150fail:
151 return -ENOMEM;
152}
153
David Howells454e2392006-06-23 02:02:57 -0700154static int devpts_get_sb(struct file_system_type *fs_type,
155 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156{
David Howells454e2392006-06-23 02:02:57 -0700157 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158}
159
160static struct file_system_type devpts_fs_type = {
161 .owner = THIS_MODULE,
162 .name = "devpts",
163 .get_sb = devpts_get_sb,
164 .kill_sb = kill_anon_super,
165};
166
167/*
168 * The normal naming convention is simply /dev/pts/<number>; this conforms
169 * to the System V naming convention
170 */
171
172static struct dentry *get_node(int num)
173{
174 char s[12];
175 struct dentry *root = devpts_root;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800176 mutex_lock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 return lookup_one_len(s, root, sprintf(s, "%d", num));
178}
179
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700180int devpts_new_index(void)
181{
182 int index;
183 int idr_ret;
184
185retry:
186 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
187 return -ENOMEM;
188 }
189
190 mutex_lock(&allocated_ptys_lock);
191 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
192 if (idr_ret < 0) {
193 mutex_unlock(&allocated_ptys_lock);
194 if (idr_ret == -EAGAIN)
195 goto retry;
196 return -EIO;
197 }
198
199 if (index >= pty_limit) {
200 idr_remove(&allocated_ptys, index);
201 mutex_unlock(&allocated_ptys_lock);
202 return -EIO;
203 }
204 mutex_unlock(&allocated_ptys_lock);
205 return index;
206}
207
208void devpts_kill_index(int idx)
209{
210 mutex_lock(&allocated_ptys_lock);
211 idr_remove(&allocated_ptys, idx);
212 mutex_unlock(&allocated_ptys_lock);
213}
214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215int devpts_pty_new(struct tty_struct *tty)
216{
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700217 int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 struct tty_driver *driver = tty->driver;
219 dev_t device = MKDEV(driver->major, driver->minor_start+number);
220 struct dentry *dentry;
221 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
222
223 /* We're supposed to be given the slave end of a pty */
224 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
225 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
226
227 if (!inode)
228 return -ENOMEM;
229
230 inode->i_ino = number+2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 inode->i_uid = config.setuid ? config.uid : current->fsuid;
232 inode->i_gid = config.setgid ? config.gid : current->fsgid;
233 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
234 init_special_inode(inode, S_IFCHR|config.mode, device);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700235 inode->i_private = tty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
237 dentry = get_node(number);
Florin Malita3972b7f2007-05-08 00:24:18 -0700238 if (!IS_ERR(dentry) && !dentry->d_inode) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 d_instantiate(dentry, inode);
Florin Malita3972b7f2007-05-08 00:24:18 -0700240 fsnotify_create(devpts_root->d_inode, dentry);
241 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800243 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244
245 return 0;
246}
247
248struct tty_struct *devpts_get_tty(int number)
249{
250 struct dentry *dentry = get_node(number);
251 struct tty_struct *tty;
252
253 tty = NULL;
254 if (!IS_ERR(dentry)) {
255 if (dentry->d_inode)
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700256 tty = dentry->d_inode->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 dput(dentry);
258 }
259
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800260 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
262 return tty;
263}
264
265void devpts_pty_kill(int number)
266{
267 struct dentry *dentry = get_node(number);
268
269 if (!IS_ERR(dentry)) {
270 struct inode *inode = dentry->d_inode;
271 if (inode) {
272 inode->i_nlink--;
273 d_delete(dentry);
274 dput(dentry);
275 }
276 dput(dentry);
277 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800278 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279}
280
281static int __init init_devpts_fs(void)
282{
283 int err = register_filesystem(&devpts_fs_type);
284 if (!err) {
285 devpts_mnt = kern_mount(&devpts_fs_type);
286 if (IS_ERR(devpts_mnt))
287 err = PTR_ERR(devpts_mnt);
288 }
289 return err;
290}
291
292static void __exit exit_devpts_fs(void)
293{
294 unregister_filesystem(&devpts_fs_type);
295 mntput(devpts_mnt);
296}
297
298module_init(init_devpts_fs)
299module_exit(exit_devpts_fs)
300MODULE_LICENSE("GPL");