1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/inode.c
*
* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/devpts_fs.h>
#include <linux/parser.h>
#define DEVPTS_SUPER_MAGIC 0x1cd1
static struct vfsmount *devpts_mnt;
static struct dentry *devpts_root;
static struct {
int setuid;
int setgid;
uid_t uid;
gid_t gid;
umode_t mode;
} config = {.mode = 0600};
enum {
Opt_uid, Opt_gid, Opt_mode,
Opt_err
};
static match_table_t tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
{Opt_err, NULL}
};
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
char *p;
config.setuid = 0;
config.setgid = 0;
config.uid = 0;
config.gid = 0;
config.mode = 0600;
while ((p = strsep(&data, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
int token;
int option;
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
config.uid = option;
config.setuid = 1;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
config.gid = option;
config.setgid = 1;
break;
case Opt_mode:
if (match_octal(&args[0], &option))
return -EINVAL;
config.mode = option & ~S_IFMT;
break;
default:
printk(KERN_ERR "devpts: called with bogus options\n");
return -EINVAL;
}
}
return 0;
}
static const struct super_operations devpts_sops = {
.statfs = simple_statfs,
.remount_fs = devpts_remount,
};
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
struct inode * inode;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = DEVPTS_SUPER_MAGIC;
s->s_op = &devpts_sops;
s->s_time_gran = 1;
inode = new_inode(s);
if (!inode)
goto fail;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_blocks = 0;
inode->i_uid = inode->i_gid = 0;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_nlink = 2;
devpts_root = s->s_root = d_alloc_root(inode);
if (s->s_root)
return 0;
printk("devpts: get root dentry failed\n");
iput(inode);
fail:
return -ENOMEM;
}
static int devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
}
static struct file_system_type devpts_fs_type = {
.owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
.kill_sb = kill_anon_super,
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
static struct dentry *get_node(int num)
{
char s[12];
struct dentry *root = devpts_root;
mutex_lock(&root->d_inode->i_mutex);
return lookup_one_len(s, root, sprintf(s, "%d", num));
}
int devpts_pty_new(struct tty_struct *tty)
{
int number = tty->index;
struct tty_driver *driver = tty->driver;
dev_t device = MKDEV(driver->major, driver->minor_start+number);
struct dentry *dentry;
struct inode *inode = new_inode(devpts_mnt->mnt_sb);
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
if (!inode)
return -ENOMEM;
inode->i_ino = number+2;
inode->i_uid = config.setuid ? config.uid : current->fsuid;
inode->i_gid = config.setgid ? config.gid : current->fsgid;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
init_special_inode(inode, S_IFCHR|config.mode, device);
inode->i_private = tty;
dentry = get_node(number);
if (!IS_ERR(dentry) && !dentry->d_inode)
d_instantiate(dentry, inode);
mutex_unlock(&devpts_root->d_inode->i_mutex);
return 0;
}
struct tty_struct *devpts_get_tty(int number)
{
struct dentry *dentry = get_node(number);
struct tty_struct *tty;
tty = NULL;
if (!IS_ERR(dentry)) {
if (dentry->d_inode)
tty = dentry->d_inode->i_private;
dput(dentry);
}
mutex_unlock(&devpts_root->d_inode->i_mutex);
return tty;
}
void devpts_pty_kill(int number)
{
struct dentry *dentry = get_node(number);
if (!IS_ERR(dentry)) {
struct inode *inode = dentry->d_inode;
if (inode) {
inode->i_nlink--;
d_delete(dentry);
dput(dentry);
}
dput(dentry);
}
mutex_unlock(&devpts_root->d_inode->i_mutex);
}
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts_mnt = kern_mount(&devpts_fs_type);
if (IS_ERR(devpts_mnt))
err = PTR_ERR(devpts_mnt);
}
return err;
}
static void __exit exit_devpts_fs(void)
{
unregister_filesystem(&devpts_fs_type);
mntput(devpts_mnt);
}
module_init(init_devpts_fs)
module_exit(exit_devpts_fs)
MODULE_LICENSE("GPL");
|
