1 /* -*- 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>
21 #include <linux/xattr.h>
22
23 #define DEVPTS_SUPER_MAGIC 0x1cd1
24
25 extern struct xattr_handler devpts_xattr_security_handler;
26
27 static struct xattr_handler *devpts_xattr_handlers[] = {
28 #ifdef CONFIG_DEVPTS_FS_SECURITY
29 &devpts_xattr_security_handler,
30 #endif
31 NULL
32 };
33
34 static struct inode_operations devpts_file_inode_operations = {
35 #ifdef CONFIG_DEVPTS_FS_XATTR
36 .setxattr = generic_setxattr,
37 .getxattr = generic_getxattr,
38 .listxattr = generic_listxattr,
39 .removexattr = generic_removexattr,
40 #endif
41 };
42
43 static struct vfsmount *devpts_mnt;
44 static struct dentry *devpts_root;
45
46 static struct {
47 int setuid;
48 int setgid;
49 uid_t uid;
50 gid_t gid;
51 umode_t mode;
52 } config = {.mode = 0600};
53
54 static int devpts_remount(struct super_block *sb, int *flags, char *data)
55 {
56 int setuid = 0;
57 int setgid = 0;
58 uid_t uid = 0;
59 gid_t gid = 0;
60 umode_t mode = 0600;
61 char *this_char;
62
63 this_char = NULL;
64 while ((this_char = strsep(&data, ",")) != NULL) {
65 int n;
66 char dummy;
67 if (!*this_char)
68 continue;
69 if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
70 setuid = 1;
71 uid = n;
72 } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
73 setgid = 1;
74 gid = n;
75 } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
76 mode = n & ~S_IFMT;
77 else {
78 printk("devpts: called with bogus options\n");
79 return -EINVAL;
80 }
81 }
82 config.setuid = setuid;
83 config.setgid = setgid;
84 config.uid = uid;
85 config.gid = gid;
86 config.mode = mode;
87
88 return 0;
89 }
90
91 static struct super_operations devpts_sops = {
92 .statfs = simple_statfs,
93 .remount_fs = devpts_remount,
94 };
95
96 static int
97 devpts_fill_super(struct super_block *s, void *data, int silent)
98 {
99 struct inode * inode;
100
101 s->s_blocksize = 1024;
102 s->s_blocksize_bits = 10;
103 s->s_magic = DEVPTS_SUPER_MAGIC;
104 s->s_op = &devpts_sops;
105 s->s_xattr = devpts_xattr_handlers;
106 s->s_time_gran = 1;
107
108 inode = new_inode(s);
109 if (!inode)
110 goto fail;
111 inode->i_ino = 1;
112 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
113 inode->i_blocks = 0;
114 inode->i_blksize = 1024;
115 inode->i_uid = inode->i_gid = 0;
116 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
117 inode->i_op = &simple_dir_inode_operations;
118 inode->i_fop = &simple_dir_operations;
119 inode->i_nlink = 2;
120
121 devpts_root = s->s_root = d_alloc_root(inode);
122 if (s->s_root)
123 return 0;
124
125 printk("devpts: get root dentry failed\n");
126 iput(inode);
127 fail:
128 return -ENOMEM;
129 }
130
131 static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
132 int flags, const char *dev_name, void *data)
133 {
134 return get_sb_single(fs_type, flags, data, devpts_fill_super);
135 }
136
137 static struct file_system_type devpts_fs_type = {
138 .owner = THIS_MODULE,
139 .name = "devpts",
140 .get_sb = devpts_get_sb,
141 .kill_sb = kill_anon_super,
142 };
143
144 /*
145 * The normal naming convention is simply /dev/pts/<number>; this conforms
146 * to the System V naming convention
147 */
148
149 static struct dentry *get_node(int num)
150 {
151 char s[12];
152 struct dentry *root = devpts_root;
153 down(&root->d_inode->i_sem);
154 return lookup_one_len(s, root, sprintf(s, "%d", num));
155 }
156
157 int devpts_pty_new(struct tty_struct *tty)
158 {
159 int number = tty->index;
160 struct tty_driver *driver = tty->driver;
161 dev_t device = MKDEV(driver->major, driver->minor_start+number);
162 struct dentry *dentry;
163 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
164
165 /* We're supposed to be given the slave end of a pty */
166 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
167 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
168
169 if (!inode)
170 return -ENOMEM;
171
172 inode->i_ino = number+2;
173 inode->i_blksize = 1024;
174 inode->i_uid = config.setuid ? config.uid : current->fsuid;
175 inode->i_gid = config.setgid ? config.gid : current->fsgid;
176 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
177 init_special_inode(inode, S_IFCHR|config.mode, device);
178 inode->i_op = &devpts_file_inode_operations;
179 inode->u.generic_ip = tty;
180
181 dentry = get_node(number);
182 if (!IS_ERR(dentry) && !dentry->d_inode)
183 d_instantiate(dentry, inode);
184
185 up(&devpts_root->d_inode->i_sem);
186
187 return 0;
188 }
189
190 struct tty_struct *devpts_get_tty(int number)
191 {
192 struct dentry *dentry = get_node(number);
193 struct tty_struct *tty;
194
195 tty = NULL;
196 if (!IS_ERR(dentry)) {
197 if (dentry->d_inode)
198 tty = dentry->d_inode->u.generic_ip;
199 dput(dentry);
200 }
201
202 up(&devpts_root->d_inode->i_sem);
203
204 return tty;
205 }
206
207 void devpts_pty_kill(int number)
208 {
209 struct dentry *dentry = get_node(number);
210
211 if (!IS_ERR(dentry)) {
212 struct inode *inode = dentry->d_inode;
213 if (inode) {
214 inode->i_nlink--;
215 d_delete(dentry);
216 dput(dentry);
217 }
218 dput(dentry);
219 }
220 up(&devpts_root->d_inode->i_sem);
221 }
222
223 static int __init init_devpts_fs(void)
224 {
225 int err = register_filesystem(&devpts_fs_type);
226 if (!err) {
227 devpts_mnt = kern_mount(&devpts_fs_type);
228 if (IS_ERR(devpts_mnt))
229 err = PTR_ERR(devpts_mnt);
230 }
231 return err;
232 }
233
234 static void __exit exit_devpts_fs(void)
235 {
236 unregister_filesystem(&devpts_fs_type);
237 mntput(devpts_mnt);
238 }
239
240 module_init(init_devpts_fs)
241 module_exit(exit_devpts_fs)
242 MODULE_LICENSE("GPL");
243
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