f2be44d4491ffcf978e2e12e09484735360e9ebd
[linux-2.6.git] / fs / devpts / inode.c
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
22 #define DEVPTS_SUPER_MAGIC 0x1cd1
23
24 static struct vfsmount *devpts_mnt;
25 static struct dentry *devpts_root;
26
27 static struct {
28         int setuid;
29         int setgid;
30         uid_t   uid;
31         gid_t   gid;
32         umode_t mode;
33 } config = {.mode = 0600};
34
35 static 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
72 static struct super_operations devpts_sops = {
73         .statfs         = simple_statfs,
74         .remount_fs     = devpts_remount,
75 };
76
77 static int
78 devpts_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;
86         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);
107 fail:
108         return -ENOMEM;
109 }
110
111 static 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
117 static 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
129 static 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
137 int 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);
158         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
169 struct 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
186 void 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
202 static 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
213 static void __exit exit_devpts_fs(void)
214 {
215         unregister_filesystem(&devpts_fs_type);
216         mntput(devpts_mnt);
217 }
218
219 module_init(init_devpts_fs)
220 module_exit(exit_devpts_fs)
221 MODULE_LICENSE("GPL");