blob: f2be44d4491ffcf978e2e12e09484735360e9ebd [file] [log] [blame]
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
22#define DEVPTS_SUPER_MAGIC 0x1cd1
23
Linus Torvalds1da177e2005-04-16 15:20:36 -070024static struct vfsmount *devpts_mnt;
25static struct dentry *devpts_root;
26
27static struct {
28 int setuid;
29 int setgid;
30 uid_t uid;
31 gid_t gid;
32 umode_t mode;
33} config = {.mode = 0600};
34
35static int devpts_remount(struct super_block *sb, int *flags, char *data)
36{
37 int setuid = 0;
38 int setgid = 0;
39 uid_t uid = 0;
40 gid_t gid = 0;
41 umode_t mode = 0600;
42 char *this_char;
43
44 this_char = NULL;
45 while ((this_char = strsep(&data, ",")) != NULL) {
46 int n;
47 char dummy;
48 if (!*this_char)
49 continue;
50 if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
51 setuid = 1;
52 uid = n;
53 } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
54 setgid = 1;
55 gid = n;
56 } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
57 mode = n & ~S_IFMT;
58 else {
59 printk("devpts: called with bogus options\n");
60 return -EINVAL;
61 }
62 }
63 config.setuid = setuid;
64 config.setgid = setgid;
65 config.uid = uid;
66 config.gid = gid;
67 config.mode = mode;
68
69 return 0;
70}
71
72static struct super_operations devpts_sops = {
73 .statfs = simple_statfs,
74 .remount_fs = devpts_remount,
75};
76
77static int
78devpts_fill_super(struct super_block *s, void *data, int silent)
79{
80 struct inode * inode;
81
82 s->s_blocksize = 1024;
83 s->s_blocksize_bits = 10;
84 s->s_magic = DEVPTS_SUPER_MAGIC;
85 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 s->s_time_gran = 1;
87
88 inode = new_inode(s);
89 if (!inode)
90 goto fail;
91 inode->i_ino = 1;
92 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
93 inode->i_blocks = 0;
94 inode->i_blksize = 1024;
95 inode->i_uid = inode->i_gid = 0;
96 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
97 inode->i_op = &simple_dir_inode_operations;
98 inode->i_fop = &simple_dir_operations;
99 inode->i_nlink = 2;
100
101 devpts_root = s->s_root = d_alloc_root(inode);
102 if (s->s_root)
103 return 0;
104
105 printk("devpts: get root dentry failed\n");
106 iput(inode);
107fail:
108 return -ENOMEM;
109}
110
111static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
112 int flags, const char *dev_name, void *data)
113{
114 return get_sb_single(fs_type, flags, data, devpts_fill_super);
115}
116
117static struct file_system_type devpts_fs_type = {
118 .owner = THIS_MODULE,
119 .name = "devpts",
120 .get_sb = devpts_get_sb,
121 .kill_sb = kill_anon_super,
122};
123
124/*
125 * The normal naming convention is simply /dev/pts/<number>; this conforms
126 * to the System V naming convention
127 */
128
129static struct dentry *get_node(int num)
130{
131 char s[12];
132 struct dentry *root = devpts_root;
133 down(&root->d_inode->i_sem);
134 return lookup_one_len(s, root, sprintf(s, "%d", num));
135}
136
137int devpts_pty_new(struct tty_struct *tty)
138{
139 int number = tty->index;
140 struct tty_driver *driver = tty->driver;
141 dev_t device = MKDEV(driver->major, driver->minor_start+number);
142 struct dentry *dentry;
143 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
144
145 /* We're supposed to be given the slave end of a pty */
146 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
147 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
148
149 if (!inode)
150 return -ENOMEM;
151
152 inode->i_ino = number+2;
153 inode->i_blksize = 1024;
154 inode->i_uid = config.setuid ? config.uid : current->fsuid;
155 inode->i_gid = config.setgid ? config.gid : current->fsgid;
156 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
157 init_special_inode(inode, S_IFCHR|config.mode, device);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 inode->u.generic_ip = tty;
159
160 dentry = get_node(number);
161 if (!IS_ERR(dentry) && !dentry->d_inode)
162 d_instantiate(dentry, inode);
163
164 up(&devpts_root->d_inode->i_sem);
165
166 return 0;
167}
168
169struct tty_struct *devpts_get_tty(int number)
170{
171 struct dentry *dentry = get_node(number);
172 struct tty_struct *tty;
173
174 tty = NULL;
175 if (!IS_ERR(dentry)) {
176 if (dentry->d_inode)
177 tty = dentry->d_inode->u.generic_ip;
178 dput(dentry);
179 }
180
181 up(&devpts_root->d_inode->i_sem);
182
183 return tty;
184}
185
186void devpts_pty_kill(int number)
187{
188 struct dentry *dentry = get_node(number);
189
190 if (!IS_ERR(dentry)) {
191 struct inode *inode = dentry->d_inode;
192 if (inode) {
193 inode->i_nlink--;
194 d_delete(dentry);
195 dput(dentry);
196 }
197 dput(dentry);
198 }
199 up(&devpts_root->d_inode->i_sem);
200}
201
202static int __init init_devpts_fs(void)
203{
204 int err = register_filesystem(&devpts_fs_type);
205 if (!err) {
206 devpts_mnt = kern_mount(&devpts_fs_type);
207 if (IS_ERR(devpts_mnt))
208 err = PTR_ERR(devpts_mnt);
209 }
210 return err;
211}
212
213static void __exit exit_devpts_fs(void)
214{
215 unregister_filesystem(&devpts_fs_type);
216 mntput(devpts_mnt);
217}
218
219module_init(init_devpts_fs)
220module_exit(exit_devpts_fs)
221MODULE_LICENSE("GPL");