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1da177e4 LT |
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> | |
718a9163 SB |
20 | #include <linux/mutex.h> |
21 | #include <linux/idr.h> | |
1da177e4 | 22 | #include <linux/devpts_fs.h> |
7a673c6b | 23 | #include <linux/parser.h> |
3972b7f6 | 24 | #include <linux/fsnotify.h> |
b87a267e | 25 | #include <linux/seq_file.h> |
1da177e4 LT |
26 | |
27 | #define DEVPTS_SUPER_MAGIC 0x1cd1 | |
28 | ||
b87a267e MS |
29 | #define DEVPTS_DEFAULT_MODE 0600 |
30 | ||
718a9163 SB |
31 | extern int pty_limit; /* Config limit on Unix98 ptys */ |
32 | static DEFINE_IDR(allocated_ptys); | |
33 | static DEFINE_MUTEX(allocated_ptys_lock); | |
34 | ||
1da177e4 LT |
35 | static struct vfsmount *devpts_mnt; |
36 | static struct dentry *devpts_root; | |
37 | ||
38 | static struct { | |
39 | int setuid; | |
40 | int setgid; | |
41 | uid_t uid; | |
42 | gid_t gid; | |
43 | umode_t mode; | |
b87a267e | 44 | } config = {.mode = DEVPTS_DEFAULT_MODE}; |
1da177e4 | 45 | |
7a673c6b DP |
46 | enum { |
47 | Opt_uid, Opt_gid, Opt_mode, | |
48 | Opt_err | |
49 | }; | |
50 | ||
51 | static match_table_t tokens = { | |
52 | {Opt_uid, "uid=%u"}, | |
53 | {Opt_gid, "gid=%u"}, | |
54 | {Opt_mode, "mode=%o"}, | |
55 | {Opt_err, NULL} | |
56 | }; | |
57 | ||
1da177e4 LT |
58 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
59 | { | |
7a673c6b DP |
60 | char *p; |
61 | ||
62 | config.setuid = 0; | |
63 | config.setgid = 0; | |
64 | config.uid = 0; | |
65 | config.gid = 0; | |
b87a267e | 66 | config.mode = DEVPTS_DEFAULT_MODE; |
7a673c6b DP |
67 | |
68 | while ((p = strsep(&data, ",")) != NULL) { | |
69 | substring_t args[MAX_OPT_ARGS]; | |
70 | int token; | |
71 | int option; | |
72 | ||
73 | if (!*p) | |
1da177e4 | 74 | continue; |
7a673c6b DP |
75 | |
76 | token = match_token(p, tokens, args); | |
77 | switch (token) { | |
78 | case Opt_uid: | |
79 | if (match_int(&args[0], &option)) | |
80 | return -EINVAL; | |
81 | config.uid = option; | |
82 | config.setuid = 1; | |
83 | break; | |
84 | case Opt_gid: | |
85 | if (match_int(&args[0], &option)) | |
86 | return -EINVAL; | |
87 | config.gid = option; | |
88 | config.setgid = 1; | |
89 | break; | |
90 | case Opt_mode: | |
91 | if (match_octal(&args[0], &option)) | |
92 | return -EINVAL; | |
b87a267e | 93 | config.mode = option & S_IALLUGO; |
7a673c6b DP |
94 | break; |
95 | default: | |
96 | printk(KERN_ERR "devpts: called with bogus options\n"); | |
1da177e4 LT |
97 | return -EINVAL; |
98 | } | |
99 | } | |
1da177e4 LT |
100 | |
101 | return 0; | |
102 | } | |
103 | ||
b87a267e MS |
104 | static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) |
105 | { | |
106 | if (config.setuid) | |
107 | seq_printf(seq, ",uid=%u", config.uid); | |
108 | if (config.setgid) | |
109 | seq_printf(seq, ",gid=%u", config.gid); | |
110 | seq_printf(seq, ",mode=%03o", config.mode); | |
111 | ||
112 | return 0; | |
113 | } | |
114 | ||
ee9b6d61 | 115 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
116 | .statfs = simple_statfs, |
117 | .remount_fs = devpts_remount, | |
b87a267e | 118 | .show_options = devpts_show_options, |
1da177e4 LT |
119 | }; |
120 | ||
121 | static int | |
122 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
123 | { | |
124 | struct inode * inode; | |
125 | ||
126 | s->s_blocksize = 1024; | |
127 | s->s_blocksize_bits = 10; | |
128 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
129 | s->s_op = &devpts_sops; | |
1da177e4 LT |
130 | s->s_time_gran = 1; |
131 | ||
132 | inode = new_inode(s); | |
133 | if (!inode) | |
134 | goto fail; | |
135 | inode->i_ino = 1; | |
136 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
137 | inode->i_blocks = 0; | |
1da177e4 LT |
138 | inode->i_uid = inode->i_gid = 0; |
139 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; | |
140 | inode->i_op = &simple_dir_inode_operations; | |
141 | inode->i_fop = &simple_dir_operations; | |
142 | inode->i_nlink = 2; | |
143 | ||
144 | devpts_root = s->s_root = d_alloc_root(inode); | |
145 | if (s->s_root) | |
146 | return 0; | |
147 | ||
148 | printk("devpts: get root dentry failed\n"); | |
149 | iput(inode); | |
150 | fail: | |
151 | return -ENOMEM; | |
152 | } | |
153 | ||
454e2398 DH |
154 | static int devpts_get_sb(struct file_system_type *fs_type, |
155 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 156 | { |
454e2398 | 157 | return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); |
1da177e4 LT |
158 | } |
159 | ||
160 | static struct file_system_type devpts_fs_type = { | |
161 | .owner = THIS_MODULE, | |
162 | .name = "devpts", | |
163 | .get_sb = devpts_get_sb, | |
164 | .kill_sb = kill_anon_super, | |
165 | }; | |
166 | ||
167 | /* | |
168 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
169 | * to the System V naming convention | |
170 | */ | |
171 | ||
172 | static struct dentry *get_node(int num) | |
173 | { | |
174 | char s[12]; | |
175 | struct dentry *root = devpts_root; | |
1b1dcc1b | 176 | mutex_lock(&root->d_inode->i_mutex); |
1da177e4 LT |
177 | return lookup_one_len(s, root, sprintf(s, "%d", num)); |
178 | } | |
179 | ||
718a9163 SB |
180 | int devpts_new_index(void) |
181 | { | |
182 | int index; | |
183 | int idr_ret; | |
184 | ||
185 | retry: | |
186 | if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { | |
187 | return -ENOMEM; | |
188 | } | |
189 | ||
190 | mutex_lock(&allocated_ptys_lock); | |
191 | idr_ret = idr_get_new(&allocated_ptys, NULL, &index); | |
192 | if (idr_ret < 0) { | |
193 | mutex_unlock(&allocated_ptys_lock); | |
194 | if (idr_ret == -EAGAIN) | |
195 | goto retry; | |
196 | return -EIO; | |
197 | } | |
198 | ||
199 | if (index >= pty_limit) { | |
200 | idr_remove(&allocated_ptys, index); | |
201 | mutex_unlock(&allocated_ptys_lock); | |
202 | return -EIO; | |
203 | } | |
204 | mutex_unlock(&allocated_ptys_lock); | |
205 | return index; | |
206 | } | |
207 | ||
208 | void devpts_kill_index(int idx) | |
209 | { | |
210 | mutex_lock(&allocated_ptys_lock); | |
211 | idr_remove(&allocated_ptys, idx); | |
212 | mutex_unlock(&allocated_ptys_lock); | |
213 | } | |
214 | ||
1da177e4 LT |
215 | int devpts_pty_new(struct tty_struct *tty) |
216 | { | |
718a9163 | 217 | int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ |
1da177e4 LT |
218 | struct tty_driver *driver = tty->driver; |
219 | dev_t device = MKDEV(driver->major, driver->minor_start+number); | |
220 | struct dentry *dentry; | |
221 | struct inode *inode = new_inode(devpts_mnt->mnt_sb); | |
222 | ||
223 | /* We're supposed to be given the slave end of a pty */ | |
224 | BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); | |
225 | BUG_ON(driver->subtype != PTY_TYPE_SLAVE); | |
226 | ||
227 | if (!inode) | |
228 | return -ENOMEM; | |
229 | ||
230 | inode->i_ino = number+2; | |
1da177e4 LT |
231 | inode->i_uid = config.setuid ? config.uid : current->fsuid; |
232 | inode->i_gid = config.setgid ? config.gid : current->fsgid; | |
233 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
234 | init_special_inode(inode, S_IFCHR|config.mode, device); | |
8e18e294 | 235 | inode->i_private = tty; |
1da177e4 LT |
236 | |
237 | dentry = get_node(number); | |
3972b7f6 | 238 | if (!IS_ERR(dentry) && !dentry->d_inode) { |
1da177e4 | 239 | d_instantiate(dentry, inode); |
3972b7f6 FM |
240 | fsnotify_create(devpts_root->d_inode, dentry); |
241 | } | |
1da177e4 | 242 | |
1b1dcc1b | 243 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
244 | |
245 | return 0; | |
246 | } | |
247 | ||
248 | struct tty_struct *devpts_get_tty(int number) | |
249 | { | |
250 | struct dentry *dentry = get_node(number); | |
251 | struct tty_struct *tty; | |
252 | ||
253 | tty = NULL; | |
254 | if (!IS_ERR(dentry)) { | |
255 | if (dentry->d_inode) | |
8e18e294 | 256 | tty = dentry->d_inode->i_private; |
1da177e4 LT |
257 | dput(dentry); |
258 | } | |
259 | ||
1b1dcc1b | 260 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
261 | |
262 | return tty; | |
263 | } | |
264 | ||
265 | void devpts_pty_kill(int number) | |
266 | { | |
267 | struct dentry *dentry = get_node(number); | |
268 | ||
269 | if (!IS_ERR(dentry)) { | |
270 | struct inode *inode = dentry->d_inode; | |
271 | if (inode) { | |
272 | inode->i_nlink--; | |
273 | d_delete(dentry); | |
274 | dput(dentry); | |
275 | } | |
276 | dput(dentry); | |
277 | } | |
1b1dcc1b | 278 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
279 | } |
280 | ||
281 | static int __init init_devpts_fs(void) | |
282 | { | |
283 | int err = register_filesystem(&devpts_fs_type); | |
284 | if (!err) { | |
285 | devpts_mnt = kern_mount(&devpts_fs_type); | |
286 | if (IS_ERR(devpts_mnt)) | |
287 | err = PTR_ERR(devpts_mnt); | |
288 | } | |
289 | return err; | |
290 | } | |
291 | ||
292 | static void __exit exit_devpts_fs(void) | |
293 | { | |
294 | unregister_filesystem(&devpts_fs_type); | |
295 | mntput(devpts_mnt); | |
296 | } | |
297 | ||
298 | module_init(init_devpts_fs) | |
299 | module_exit(exit_devpts_fs) | |
300 | MODULE_LICENSE("GPL"); |