1571c8d6c2322368ef0a8d57e753a3944c2390cf
[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/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");