mount options: fix devpts
[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 #include <linux/parser.h>
22 #include <linux/fsnotify.h>
23 #include <linux/seq_file.h>
24
25 #define DEVPTS_SUPER_MAGIC 0x1cd1
26
27 #define DEVPTS_DEFAULT_MODE 0600
28
29 static struct vfsmount *devpts_mnt;
30 static struct dentry *devpts_root;
31
32 static struct {
33         int setuid;
34         int setgid;
35         uid_t   uid;
36         gid_t   gid;
37         umode_t mode;
38 } config = {.mode = DEVPTS_DEFAULT_MODE};
39
40 enum {
41         Opt_uid, Opt_gid, Opt_mode,
42         Opt_err
43 };
44
45 static match_table_t tokens = {
46         {Opt_uid, "uid=%u"},
47         {Opt_gid, "gid=%u"},
48         {Opt_mode, "mode=%o"},
49         {Opt_err, NULL}
50 };
51
52 static int devpts_remount(struct super_block *sb, int *flags, char *data)
53 {
54         char *p;
55
56         config.setuid  = 0;
57         config.setgid  = 0;
58         config.uid     = 0;
59         config.gid     = 0;
60         config.mode    = DEVPTS_DEFAULT_MODE;
61
62         while ((p = strsep(&data, ",")) != NULL) {
63                 substring_t args[MAX_OPT_ARGS];
64                 int token;
65                 int option;
66
67                 if (!*p)
68                         continue;
69
70                 token = match_token(p, tokens, args);
71                 switch (token) {
72                 case Opt_uid:
73                         if (match_int(&args[0], &option))
74                                 return -EINVAL;
75                         config.uid = option;
76                         config.setuid = 1;
77                         break;
78                 case Opt_gid:
79                         if (match_int(&args[0], &option))
80                                 return -EINVAL;
81                         config.gid = option;
82                         config.setgid = 1;
83                         break;
84                 case Opt_mode:
85                         if (match_octal(&args[0], &option))
86                                 return -EINVAL;
87                         config.mode = option & S_IALLUGO;
88                         break;
89                 default:
90                         printk(KERN_ERR "devpts: called with bogus options\n");
91                         return -EINVAL;
92                 }
93         }
94
95         return 0;
96 }
97
98 static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
99 {
100         if (config.setuid)
101                 seq_printf(seq, ",uid=%u", config.uid);
102         if (config.setgid)
103                 seq_printf(seq, ",gid=%u", config.gid);
104         seq_printf(seq, ",mode=%03o", config.mode);
105
106         return 0;
107 }
108
109 static const struct super_operations devpts_sops = {
110         .statfs         = simple_statfs,
111         .remount_fs     = devpts_remount,
112         .show_options   = devpts_show_options,
113 };
114
115 static int
116 devpts_fill_super(struct super_block *s, void *data, int silent)
117 {
118         struct inode * inode;
119
120         s->s_blocksize = 1024;
121         s->s_blocksize_bits = 10;
122         s->s_magic = DEVPTS_SUPER_MAGIC;
123         s->s_op = &devpts_sops;
124         s->s_time_gran = 1;
125
126         inode = new_inode(s);
127         if (!inode)
128                 goto fail;
129         inode->i_ino = 1;
130         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
131         inode->i_blocks = 0;
132         inode->i_uid = inode->i_gid = 0;
133         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
134         inode->i_op = &simple_dir_inode_operations;
135         inode->i_fop = &simple_dir_operations;
136         inode->i_nlink = 2;
137
138         devpts_root = s->s_root = d_alloc_root(inode);
139         if (s->s_root)
140                 return 0;
141         
142         printk("devpts: get root dentry failed\n");
143         iput(inode);
144 fail:
145         return -ENOMEM;
146 }
147
148 static int devpts_get_sb(struct file_system_type *fs_type,
149         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
150 {
151         return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
152 }
153
154 static struct file_system_type devpts_fs_type = {
155         .owner          = THIS_MODULE,
156         .name           = "devpts",
157         .get_sb         = devpts_get_sb,
158         .kill_sb        = kill_anon_super,
159 };
160
161 /*
162  * The normal naming convention is simply /dev/pts/<number>; this conforms
163  * to the System V naming convention
164  */
165
166 static struct dentry *get_node(int num)
167 {
168         char s[12];
169         struct dentry *root = devpts_root;
170         mutex_lock(&root->d_inode->i_mutex);
171         return lookup_one_len(s, root, sprintf(s, "%d", num));
172 }
173
174 int devpts_pty_new(struct tty_struct *tty)
175 {
176         int number = tty->index;
177         struct tty_driver *driver = tty->driver;
178         dev_t device = MKDEV(driver->major, driver->minor_start+number);
179         struct dentry *dentry;
180         struct inode *inode = new_inode(devpts_mnt->mnt_sb);
181
182         /* We're supposed to be given the slave end of a pty */
183         BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
184         BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
185
186         if (!inode)
187                 return -ENOMEM;
188
189         inode->i_ino = number+2;
190         inode->i_uid = config.setuid ? config.uid : current->fsuid;
191         inode->i_gid = config.setgid ? config.gid : current->fsgid;
192         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
193         init_special_inode(inode, S_IFCHR|config.mode, device);
194         inode->i_private = tty;
195
196         dentry = get_node(number);
197         if (!IS_ERR(dentry) && !dentry->d_inode) {
198                 d_instantiate(dentry, inode);
199                 fsnotify_create(devpts_root->d_inode, dentry);
200         }
201
202         mutex_unlock(&devpts_root->d_inode->i_mutex);
203
204         return 0;
205 }
206
207 struct tty_struct *devpts_get_tty(int number)
208 {
209         struct dentry *dentry = get_node(number);
210         struct tty_struct *tty;
211
212         tty = NULL;
213         if (!IS_ERR(dentry)) {
214                 if (dentry->d_inode)
215                         tty = dentry->d_inode->i_private;
216                 dput(dentry);
217         }
218
219         mutex_unlock(&devpts_root->d_inode->i_mutex);
220
221         return tty;
222 }
223
224 void devpts_pty_kill(int number)
225 {
226         struct dentry *dentry = get_node(number);
227
228         if (!IS_ERR(dentry)) {
229                 struct inode *inode = dentry->d_inode;
230                 if (inode) {
231                         inode->i_nlink--;
232                         d_delete(dentry);
233                         dput(dentry);
234                 }
235                 dput(dentry);
236         }
237         mutex_unlock(&devpts_root->d_inode->i_mutex);
238 }
239
240 static int __init init_devpts_fs(void)
241 {
242         int err = register_filesystem(&devpts_fs_type);
243         if (!err) {
244                 devpts_mnt = kern_mount(&devpts_fs_type);
245                 if (IS_ERR(devpts_mnt))
246                         err = PTR_ERR(devpts_mnt);
247         }
248         return err;
249 }
250
251 static void __exit exit_devpts_fs(void)
252 {
253         unregister_filesystem(&devpts_fs_type);
254         mntput(devpts_mnt);
255 }
256
257 module_init(init_devpts_fs)
258 module_exit(exit_devpts_fs)
259 MODULE_LICENSE("GPL");