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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>
20#include <linux/devpts_fs.h>
Domen Puncer7a673c62006-03-23 03:00:59 -080021#include <linux/parser.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
23#define DEVPTS_SUPER_MAGIC 0x1cd1
24
Linus Torvalds1da177e2005-04-16 15:20:36 -070025static struct vfsmount *devpts_mnt;
26static struct dentry *devpts_root;
27
28static struct {
29 int setuid;
30 int setgid;
31 uid_t uid;
32 gid_t gid;
33 umode_t mode;
34} config = {.mode = 0600};
35
Domen Puncer7a673c62006-03-23 03:00:59 -080036enum {
37 Opt_uid, Opt_gid, Opt_mode,
38 Opt_err
39};
40
41static match_table_t tokens = {
42 {Opt_uid, "uid=%u"},
43 {Opt_gid, "gid=%u"},
44 {Opt_mode, "mode=%o"},
45 {Opt_err, NULL}
46};
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048static int devpts_remount(struct super_block *sb, int *flags, char *data)
49{
Domen Puncer7a673c62006-03-23 03:00:59 -080050 char *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
Domen Puncer7a673c62006-03-23 03:00:59 -080052 config.setuid = 0;
53 config.setgid = 0;
54 config.uid = 0;
55 config.gid = 0;
56 config.mode = 0600;
57
58 while ((p = strsep(&data, ",")) != NULL) {
59 substring_t args[MAX_OPT_ARGS];
60 int token;
61 int option;
62
63 if (!*p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 continue;
Domen Puncer7a673c62006-03-23 03:00:59 -080065
66 token = match_token(p, tokens, args);
67 switch (token) {
68 case Opt_uid:
69 if (match_int(&args[0], &option))
70 return -EINVAL;
71 config.uid = option;
72 config.setuid = 1;
73 break;
74 case Opt_gid:
75 if (match_int(&args[0], &option))
76 return -EINVAL;
77 config.gid = option;
78 config.setgid = 1;
79 break;
80 case Opt_mode:
81 if (match_octal(&args[0], &option))
82 return -EINVAL;
83 config.mode = option & ~S_IFMT;
84 break;
85 default:
86 printk(KERN_ERR "devpts: called with bogus options\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 return -EINVAL;
88 }
89 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
91 return 0;
92}
93
94static struct super_operations devpts_sops = {
95 .statfs = simple_statfs,
96 .remount_fs = devpts_remount,
97};
98
99static int
100devpts_fill_super(struct super_block *s, void *data, int silent)
101{
102 struct inode * inode;
103
104 s->s_blocksize = 1024;
105 s->s_blocksize_bits = 10;
106 s->s_magic = DEVPTS_SUPER_MAGIC;
107 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 s->s_time_gran = 1;
109
110 inode = new_inode(s);
111 if (!inode)
112 goto fail;
113 inode->i_ino = 1;
114 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
115 inode->i_blocks = 0;
116 inode->i_blksize = 1024;
117 inode->i_uid = inode->i_gid = 0;
118 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
119 inode->i_op = &simple_dir_inode_operations;
120 inode->i_fop = &simple_dir_operations;
121 inode->i_nlink = 2;
122
123 devpts_root = s->s_root = d_alloc_root(inode);
124 if (s->s_root)
125 return 0;
126
127 printk("devpts: get root dentry failed\n");
128 iput(inode);
129fail:
130 return -ENOMEM;
131}
132
David Howells454e2392006-06-23 02:02:57 -0700133static int devpts_get_sb(struct file_system_type *fs_type,
134 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
David Howells454e2392006-06-23 02:02:57 -0700136 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137}
138
139static struct file_system_type devpts_fs_type = {
140 .owner = THIS_MODULE,
141 .name = "devpts",
142 .get_sb = devpts_get_sb,
143 .kill_sb = kill_anon_super,
144};
145
146/*
147 * The normal naming convention is simply /dev/pts/<number>; this conforms
148 * to the System V naming convention
149 */
150
151static struct dentry *get_node(int num)
152{
153 char s[12];
154 struct dentry *root = devpts_root;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800155 mutex_lock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 return lookup_one_len(s, root, sprintf(s, "%d", num));
157}
158
159int devpts_pty_new(struct tty_struct *tty)
160{
161 int number = tty->index;
162 struct tty_driver *driver = tty->driver;
163 dev_t device = MKDEV(driver->major, driver->minor_start+number);
164 struct dentry *dentry;
165 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
166
167 /* We're supposed to be given the slave end of a pty */
168 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
169 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
170
171 if (!inode)
172 return -ENOMEM;
173
174 inode->i_ino = number+2;
175 inode->i_blksize = 1024;
176 inode->i_uid = config.setuid ? config.uid : current->fsuid;
177 inode->i_gid = config.setgid ? config.gid : current->fsgid;
178 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
179 init_special_inode(inode, S_IFCHR|config.mode, device);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 inode->u.generic_ip = tty;
181
182 dentry = get_node(number);
183 if (!IS_ERR(dentry) && !dentry->d_inode)
184 d_instantiate(dentry, inode);
185
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800186 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188 return 0;
189}
190
191struct tty_struct *devpts_get_tty(int number)
192{
193 struct dentry *dentry = get_node(number);
194 struct tty_struct *tty;
195
196 tty = NULL;
197 if (!IS_ERR(dentry)) {
198 if (dentry->d_inode)
199 tty = dentry->d_inode->u.generic_ip;
200 dput(dentry);
201 }
202
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800203 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
205 return tty;
206}
207
208void devpts_pty_kill(int number)
209{
210 struct dentry *dentry = get_node(number);
211
212 if (!IS_ERR(dentry)) {
213 struct inode *inode = dentry->d_inode;
214 if (inode) {
215 inode->i_nlink--;
216 d_delete(dentry);
217 dput(dentry);
218 }
219 dput(dentry);
220 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800221 mutex_unlock(&devpts_root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222}
223
224static int __init init_devpts_fs(void)
225{
226 int err = register_filesystem(&devpts_fs_type);
227 if (!err) {
228 devpts_mnt = kern_mount(&devpts_fs_type);
229 if (IS_ERR(devpts_mnt))
230 err = PTR_ERR(devpts_mnt);
231 }
232 return err;
233}
234
235static void __exit exit_devpts_fs(void)
236{
237 unregister_filesystem(&devpts_fs_type);
238 mntput(devpts_mnt);
239}
240
241module_init(init_devpts_fs)
242module_exit(exit_devpts_fs)
243MODULE_LICENSE("GPL");