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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 | 29 | #define DEVPTS_DEFAULT_MODE 0600 |
527b3e47 | 30 | #define PTMX_MINOR 2 |
b87a267e | 31 | |
718a9163 | 32 | extern int pty_limit; /* Config limit on Unix98 ptys */ |
7ee7c12b | 33 | static DEFINE_IDA(allocated_ptys); |
718a9163 SB |
34 | static DEFINE_MUTEX(allocated_ptys_lock); |
35 | ||
1da177e4 LT |
36 | static struct vfsmount *devpts_mnt; |
37 | static struct dentry *devpts_root; | |
38 | ||
39 | static struct { | |
40 | int setuid; | |
41 | int setgid; | |
42 | uid_t uid; | |
43 | gid_t gid; | |
44 | umode_t mode; | |
b87a267e | 45 | } config = {.mode = DEVPTS_DEFAULT_MODE}; |
1da177e4 | 46 | |
7a673c6b DP |
47 | enum { |
48 | Opt_uid, Opt_gid, Opt_mode, | |
49 | Opt_err | |
50 | }; | |
51 | ||
a447c093 | 52 | static const match_table_t tokens = { |
7a673c6b DP |
53 | {Opt_uid, "uid=%u"}, |
54 | {Opt_gid, "gid=%u"}, | |
55 | {Opt_mode, "mode=%o"}, | |
56 | {Opt_err, NULL} | |
57 | }; | |
58 | ||
1da177e4 LT |
59 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
60 | { | |
7a673c6b DP |
61 | char *p; |
62 | ||
63 | config.setuid = 0; | |
64 | config.setgid = 0; | |
65 | config.uid = 0; | |
66 | config.gid = 0; | |
b87a267e | 67 | config.mode = DEVPTS_DEFAULT_MODE; |
7a673c6b DP |
68 | |
69 | while ((p = strsep(&data, ",")) != NULL) { | |
70 | substring_t args[MAX_OPT_ARGS]; | |
71 | int token; | |
72 | int option; | |
73 | ||
74 | if (!*p) | |
1da177e4 | 75 | continue; |
7a673c6b DP |
76 | |
77 | token = match_token(p, tokens, args); | |
78 | switch (token) { | |
79 | case Opt_uid: | |
80 | if (match_int(&args[0], &option)) | |
81 | return -EINVAL; | |
82 | config.uid = option; | |
83 | config.setuid = 1; | |
84 | break; | |
85 | case Opt_gid: | |
86 | if (match_int(&args[0], &option)) | |
87 | return -EINVAL; | |
88 | config.gid = option; | |
89 | config.setgid = 1; | |
90 | break; | |
91 | case Opt_mode: | |
92 | if (match_octal(&args[0], &option)) | |
93 | return -EINVAL; | |
b87a267e | 94 | config.mode = option & S_IALLUGO; |
7a673c6b DP |
95 | break; |
96 | default: | |
97 | printk(KERN_ERR "devpts: called with bogus options\n"); | |
1da177e4 LT |
98 | return -EINVAL; |
99 | } | |
100 | } | |
1da177e4 LT |
101 | |
102 | return 0; | |
103 | } | |
104 | ||
b87a267e MS |
105 | static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) |
106 | { | |
107 | if (config.setuid) | |
108 | seq_printf(seq, ",uid=%u", config.uid); | |
109 | if (config.setgid) | |
110 | seq_printf(seq, ",gid=%u", config.gid); | |
111 | seq_printf(seq, ",mode=%03o", config.mode); | |
112 | ||
113 | return 0; | |
114 | } | |
115 | ||
ee9b6d61 | 116 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
117 | .statfs = simple_statfs, |
118 | .remount_fs = devpts_remount, | |
b87a267e | 119 | .show_options = devpts_show_options, |
1da177e4 LT |
120 | }; |
121 | ||
122 | static int | |
123 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
124 | { | |
125 | struct inode * inode; | |
126 | ||
127 | s->s_blocksize = 1024; | |
128 | s->s_blocksize_bits = 10; | |
129 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
130 | s->s_op = &devpts_sops; | |
1da177e4 LT |
131 | s->s_time_gran = 1; |
132 | ||
133 | inode = new_inode(s); | |
134 | if (!inode) | |
135 | goto fail; | |
136 | inode->i_ino = 1; | |
137 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
138 | inode->i_blocks = 0; | |
1da177e4 LT |
139 | inode->i_uid = inode->i_gid = 0; |
140 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; | |
141 | inode->i_op = &simple_dir_inode_operations; | |
142 | inode->i_fop = &simple_dir_operations; | |
143 | inode->i_nlink = 2; | |
144 | ||
145 | devpts_root = s->s_root = d_alloc_root(inode); | |
146 | if (s->s_root) | |
147 | return 0; | |
148 | ||
149 | printk("devpts: get root dentry failed\n"); | |
150 | iput(inode); | |
151 | fail: | |
152 | return -ENOMEM; | |
153 | } | |
154 | ||
454e2398 DH |
155 | static int devpts_get_sb(struct file_system_type *fs_type, |
156 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 157 | { |
454e2398 | 158 | return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); |
1da177e4 LT |
159 | } |
160 | ||
161 | static struct file_system_type devpts_fs_type = { | |
162 | .owner = THIS_MODULE, | |
163 | .name = "devpts", | |
164 | .get_sb = devpts_get_sb, | |
165 | .kill_sb = kill_anon_super, | |
166 | }; | |
167 | ||
168 | /* | |
169 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
170 | * to the System V naming convention | |
171 | */ | |
172 | ||
15f1a633 | 173 | int devpts_new_index(struct inode *ptmx_inode) |
718a9163 SB |
174 | { |
175 | int index; | |
7ee7c12b | 176 | int ida_ret; |
718a9163 SB |
177 | |
178 | retry: | |
7ee7c12b | 179 | if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) { |
718a9163 SB |
180 | return -ENOMEM; |
181 | } | |
182 | ||
183 | mutex_lock(&allocated_ptys_lock); | |
7ee7c12b AD |
184 | ida_ret = ida_get_new(&allocated_ptys, &index); |
185 | if (ida_ret < 0) { | |
718a9163 | 186 | mutex_unlock(&allocated_ptys_lock); |
7ee7c12b | 187 | if (ida_ret == -EAGAIN) |
718a9163 SB |
188 | goto retry; |
189 | return -EIO; | |
190 | } | |
191 | ||
192 | if (index >= pty_limit) { | |
7ee7c12b | 193 | ida_remove(&allocated_ptys, index); |
718a9163 SB |
194 | mutex_unlock(&allocated_ptys_lock); |
195 | return -EIO; | |
196 | } | |
197 | mutex_unlock(&allocated_ptys_lock); | |
198 | return index; | |
199 | } | |
200 | ||
15f1a633 | 201 | void devpts_kill_index(struct inode *ptmx_inode, int idx) |
718a9163 SB |
202 | { |
203 | mutex_lock(&allocated_ptys_lock); | |
7ee7c12b | 204 | ida_remove(&allocated_ptys, idx); |
718a9163 SB |
205 | mutex_unlock(&allocated_ptys_lock); |
206 | } | |
207 | ||
15f1a633 | 208 | int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) |
1da177e4 | 209 | { |
718a9163 | 210 | int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ |
1da177e4 LT |
211 | struct tty_driver *driver = tty->driver; |
212 | dev_t device = MKDEV(driver->major, driver->minor_start+number); | |
213 | struct dentry *dentry; | |
214 | struct inode *inode = new_inode(devpts_mnt->mnt_sb); | |
89a52e10 | 215 | char s[12]; |
1da177e4 LT |
216 | |
217 | /* We're supposed to be given the slave end of a pty */ | |
218 | BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); | |
219 | BUG_ON(driver->subtype != PTY_TYPE_SLAVE); | |
220 | ||
221 | if (!inode) | |
222 | return -ENOMEM; | |
223 | ||
224 | inode->i_ino = number+2; | |
ec4c2aac DH |
225 | inode->i_uid = config.setuid ? config.uid : current_fsuid(); |
226 | inode->i_gid = config.setgid ? config.gid : current_fsgid(); | |
1da177e4 LT |
227 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
228 | init_special_inode(inode, S_IFCHR|config.mode, device); | |
8e18e294 | 229 | inode->i_private = tty; |
a6f37daa | 230 | tty->driver_data = inode; |
1da177e4 | 231 | |
89a52e10 SB |
232 | sprintf(s, "%d", number); |
233 | ||
234 | mutex_lock(&devpts_root->d_inode->i_mutex); | |
235 | ||
236 | dentry = d_alloc_name(devpts_root, s); | |
237 | if (!IS_ERR(dentry)) { | |
238 | d_add(dentry, inode); | |
3972b7f6 FM |
239 | fsnotify_create(devpts_root->d_inode, dentry); |
240 | } | |
1da177e4 | 241 | |
1b1dcc1b | 242 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
243 | |
244 | return 0; | |
245 | } | |
246 | ||
15f1a633 | 247 | struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) |
1da177e4 | 248 | { |
527b3e47 | 249 | BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); |
1da177e4 | 250 | |
527b3e47 SB |
251 | if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) |
252 | return (struct tty_struct *)pts_inode->i_private; | |
253 | return NULL; | |
1da177e4 LT |
254 | } |
255 | ||
15f1a633 | 256 | void devpts_pty_kill(struct tty_struct *tty) |
1da177e4 | 257 | { |
a6f37daa SB |
258 | struct inode *inode = tty->driver_data; |
259 | struct dentry *dentry; | |
1da177e4 | 260 | |
a6f37daa SB |
261 | BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); |
262 | ||
263 | mutex_lock(&devpts_root->d_inode->i_mutex); | |
264 | ||
265 | dentry = d_find_alias(inode); | |
266 | if (dentry && !IS_ERR(dentry)) { | |
267 | inode->i_nlink--; | |
268 | d_delete(dentry); | |
1da177e4 LT |
269 | dput(dentry); |
270 | } | |
a6f37daa | 271 | |
1b1dcc1b | 272 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
273 | } |
274 | ||
275 | static int __init init_devpts_fs(void) | |
276 | { | |
277 | int err = register_filesystem(&devpts_fs_type); | |
278 | if (!err) { | |
279 | devpts_mnt = kern_mount(&devpts_fs_type); | |
280 | if (IS_ERR(devpts_mnt)) | |
281 | err = PTR_ERR(devpts_mnt); | |
282 | } | |
283 | return err; | |
284 | } | |
285 | ||
286 | static void __exit exit_devpts_fs(void) | |
287 | { | |
288 | unregister_filesystem(&devpts_fs_type); | |
289 | mntput(devpts_mnt); | |
290 | } | |
291 | ||
292 | module_init(init_devpts_fs) | |
293 | module_exit(exit_devpts_fs) | |
294 | MODULE_LICENSE("GPL"); |