Commit | Line | Data |
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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 |
1f8f1e29 SB |
30 | /* |
31 | * ptmx is a new node in /dev/pts and will be unused in legacy (single- | |
32 | * instance) mode. To prevent surprises in user space, set permissions of | |
33 | * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful | |
34 | * permissions. | |
35 | */ | |
36 | #define DEVPTS_DEFAULT_PTMX_MODE 0000 | |
527b3e47 | 37 | #define PTMX_MINOR 2 |
b87a267e | 38 | |
718a9163 | 39 | extern int pty_limit; /* Config limit on Unix98 ptys */ |
718a9163 SB |
40 | static DEFINE_MUTEX(allocated_ptys_lock); |
41 | ||
1da177e4 | 42 | static struct vfsmount *devpts_mnt; |
1da177e4 | 43 | |
31af0abb | 44 | struct pts_mount_opts { |
1da177e4 LT |
45 | int setuid; |
46 | int setgid; | |
47 | uid_t uid; | |
48 | gid_t gid; | |
49 | umode_t mode; | |
1f8f1e29 | 50 | umode_t ptmxmode; |
31af0abb | 51 | }; |
1da177e4 | 52 | |
7a673c6b | 53 | enum { |
1f8f1e29 | 54 | Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, |
7a673c6b DP |
55 | Opt_err |
56 | }; | |
57 | ||
a447c093 | 58 | static const match_table_t tokens = { |
7a673c6b DP |
59 | {Opt_uid, "uid=%u"}, |
60 | {Opt_gid, "gid=%u"}, | |
61 | {Opt_mode, "mode=%o"}, | |
1f8f1e29 SB |
62 | #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES |
63 | {Opt_ptmxmode, "ptmxmode=%o"}, | |
64 | #endif | |
7a673c6b DP |
65 | {Opt_err, NULL} |
66 | }; | |
67 | ||
e76b7c01 SB |
68 | struct pts_fs_info { |
69 | struct ida allocated_ptys; | |
31af0abb | 70 | struct pts_mount_opts mount_opts; |
1f8f1e29 | 71 | struct dentry *ptmx_dentry; |
e76b7c01 SB |
72 | }; |
73 | ||
74 | static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) | |
75 | { | |
76 | return sb->s_fs_info; | |
77 | } | |
78 | ||
59e55e6c SB |
79 | static inline struct super_block *pts_sb_from_inode(struct inode *inode) |
80 | { | |
81 | if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) | |
82 | return inode->i_sb; | |
83 | ||
84 | return devpts_mnt->mnt_sb; | |
85 | } | |
86 | ||
53af8ee4 | 87 | static int parse_mount_options(char *data, struct pts_mount_opts *opts) |
1da177e4 | 88 | { |
7a673c6b DP |
89 | char *p; |
90 | ||
31af0abb SB |
91 | opts->setuid = 0; |
92 | opts->setgid = 0; | |
93 | opts->uid = 0; | |
94 | opts->gid = 0; | |
95 | opts->mode = DEVPTS_DEFAULT_MODE; | |
1f8f1e29 | 96 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
7a673c6b DP |
97 | |
98 | while ((p = strsep(&data, ",")) != NULL) { | |
99 | substring_t args[MAX_OPT_ARGS]; | |
100 | int token; | |
101 | int option; | |
102 | ||
103 | if (!*p) | |
1da177e4 | 104 | continue; |
7a673c6b DP |
105 | |
106 | token = match_token(p, tokens, args); | |
107 | switch (token) { | |
108 | case Opt_uid: | |
109 | if (match_int(&args[0], &option)) | |
110 | return -EINVAL; | |
31af0abb SB |
111 | opts->uid = option; |
112 | opts->setuid = 1; | |
7a673c6b DP |
113 | break; |
114 | case Opt_gid: | |
115 | if (match_int(&args[0], &option)) | |
116 | return -EINVAL; | |
31af0abb SB |
117 | opts->gid = option; |
118 | opts->setgid = 1; | |
7a673c6b DP |
119 | break; |
120 | case Opt_mode: | |
121 | if (match_octal(&args[0], &option)) | |
122 | return -EINVAL; | |
31af0abb | 123 | opts->mode = option & S_IALLUGO; |
7a673c6b | 124 | break; |
1f8f1e29 SB |
125 | #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES |
126 | case Opt_ptmxmode: | |
127 | if (match_octal(&args[0], &option)) | |
128 | return -EINVAL; | |
129 | opts->ptmxmode = option & S_IALLUGO; | |
130 | break; | |
131 | #endif | |
7a673c6b DP |
132 | default: |
133 | printk(KERN_ERR "devpts: called with bogus options\n"); | |
1da177e4 LT |
134 | return -EINVAL; |
135 | } | |
136 | } | |
1da177e4 LT |
137 | |
138 | return 0; | |
139 | } | |
140 | ||
1f8f1e29 SB |
141 | #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES |
142 | static int mknod_ptmx(struct super_block *sb) | |
143 | { | |
144 | int mode; | |
145 | int rc = -ENOMEM; | |
146 | struct dentry *dentry; | |
147 | struct inode *inode; | |
148 | struct dentry *root = sb->s_root; | |
149 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
150 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
151 | ||
152 | mutex_lock(&root->d_inode->i_mutex); | |
153 | ||
154 | /* If we have already created ptmx node, return */ | |
155 | if (fsi->ptmx_dentry) { | |
156 | rc = 0; | |
157 | goto out; | |
158 | } | |
159 | ||
160 | dentry = d_alloc_name(root, "ptmx"); | |
161 | if (!dentry) { | |
162 | printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); | |
163 | goto out; | |
164 | } | |
165 | ||
166 | /* | |
167 | * Create a new 'ptmx' node in this mount of devpts. | |
168 | */ | |
169 | inode = new_inode(sb); | |
170 | if (!inode) { | |
171 | printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); | |
172 | dput(dentry); | |
173 | goto out; | |
174 | } | |
175 | ||
176 | inode->i_ino = 2; | |
177 | inode->i_uid = inode->i_gid = 0; | |
178 | inode->i_blocks = 0; | |
179 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
180 | ||
181 | mode = S_IFCHR|opts->ptmxmode; | |
182 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
183 | ||
184 | d_add(dentry, inode); | |
185 | ||
186 | fsi->ptmx_dentry = dentry; | |
187 | rc = 0; | |
188 | ||
189 | printk(KERN_DEBUG "Created ptmx node in devpts ino %lu\n", | |
190 | inode->i_ino); | |
191 | out: | |
192 | mutex_unlock(&root->d_inode->i_mutex); | |
193 | return rc; | |
194 | } | |
195 | ||
196 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
197 | { | |
198 | struct inode *inode; | |
199 | if (fsi->ptmx_dentry) { | |
200 | inode = fsi->ptmx_dentry->d_inode; | |
201 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; | |
202 | } | |
203 | } | |
204 | #else | |
205 | static inline void update_ptmx_mode(struct pts_fs_info *fsi) | |
206 | { | |
207 | return; | |
208 | } | |
209 | #endif | |
210 | ||
53af8ee4 SB |
211 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
212 | { | |
1f8f1e29 | 213 | int err; |
53af8ee4 SB |
214 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
215 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
216 | ||
1f8f1e29 SB |
217 | err = parse_mount_options(data, opts); |
218 | ||
219 | /* | |
220 | * parse_mount_options() restores options to default values | |
221 | * before parsing and may have changed ptmxmode. So, update the | |
222 | * mode in the inode too. Bogus options don't fail the remount, | |
223 | * so do this even on error return. | |
224 | */ | |
225 | update_ptmx_mode(fsi); | |
226 | ||
227 | return err; | |
53af8ee4 SB |
228 | } |
229 | ||
b87a267e MS |
230 | static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) |
231 | { | |
31af0abb SB |
232 | struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb); |
233 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
234 | ||
235 | if (opts->setuid) | |
236 | seq_printf(seq, ",uid=%u", opts->uid); | |
237 | if (opts->setgid) | |
238 | seq_printf(seq, ",gid=%u", opts->gid); | |
239 | seq_printf(seq, ",mode=%03o", opts->mode); | |
1f8f1e29 SB |
240 | #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES |
241 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); | |
242 | #endif | |
b87a267e MS |
243 | |
244 | return 0; | |
245 | } | |
246 | ||
ee9b6d61 | 247 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
248 | .statfs = simple_statfs, |
249 | .remount_fs = devpts_remount, | |
b87a267e | 250 | .show_options = devpts_show_options, |
1da177e4 LT |
251 | }; |
252 | ||
e76b7c01 SB |
253 | static void *new_pts_fs_info(void) |
254 | { | |
255 | struct pts_fs_info *fsi; | |
256 | ||
257 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
258 | if (!fsi) | |
259 | return NULL; | |
260 | ||
261 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 262 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 263 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e76b7c01 SB |
264 | |
265 | return fsi; | |
266 | } | |
267 | ||
1da177e4 LT |
268 | static int |
269 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
270 | { | |
1f8f1e29 | 271 | struct inode *inode; |
1da177e4 LT |
272 | |
273 | s->s_blocksize = 1024; | |
274 | s->s_blocksize_bits = 10; | |
275 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
276 | s->s_op = &devpts_sops; | |
1da177e4 LT |
277 | s->s_time_gran = 1; |
278 | ||
e76b7c01 SB |
279 | s->s_fs_info = new_pts_fs_info(); |
280 | if (!s->s_fs_info) | |
281 | goto fail; | |
282 | ||
1da177e4 LT |
283 | inode = new_inode(s); |
284 | if (!inode) | |
e76b7c01 | 285 | goto free_fsi; |
1da177e4 LT |
286 | inode->i_ino = 1; |
287 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
288 | inode->i_blocks = 0; | |
1da177e4 LT |
289 | inode->i_uid = inode->i_gid = 0; |
290 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; | |
291 | inode->i_op = &simple_dir_inode_operations; | |
292 | inode->i_fop = &simple_dir_operations; | |
293 | inode->i_nlink = 2; | |
294 | ||
59e55e6c | 295 | s->s_root = d_alloc_root(inode); |
1da177e4 LT |
296 | if (s->s_root) |
297 | return 0; | |
1f8f1e29 | 298 | |
1da177e4 LT |
299 | printk("devpts: get root dentry failed\n"); |
300 | iput(inode); | |
e76b7c01 SB |
301 | |
302 | free_fsi: | |
303 | kfree(s->s_fs_info); | |
1da177e4 LT |
304 | fail: |
305 | return -ENOMEM; | |
306 | } | |
307 | ||
454e2398 DH |
308 | static int devpts_get_sb(struct file_system_type *fs_type, |
309 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 310 | { |
454e2398 | 311 | return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); |
1da177e4 LT |
312 | } |
313 | ||
e76b7c01 SB |
314 | static void devpts_kill_sb(struct super_block *sb) |
315 | { | |
316 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
317 | ||
318 | kfree(fsi); | |
1f8f1e29 | 319 | kill_litter_super(sb); |
e76b7c01 SB |
320 | } |
321 | ||
1da177e4 LT |
322 | static struct file_system_type devpts_fs_type = { |
323 | .owner = THIS_MODULE, | |
324 | .name = "devpts", | |
325 | .get_sb = devpts_get_sb, | |
e76b7c01 | 326 | .kill_sb = devpts_kill_sb, |
1da177e4 LT |
327 | }; |
328 | ||
329 | /* | |
330 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
331 | * to the System V naming convention | |
332 | */ | |
333 | ||
15f1a633 | 334 | int devpts_new_index(struct inode *ptmx_inode) |
718a9163 | 335 | { |
e76b7c01 SB |
336 | struct super_block *sb = pts_sb_from_inode(ptmx_inode); |
337 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
718a9163 | 338 | int index; |
7ee7c12b | 339 | int ida_ret; |
718a9163 SB |
340 | |
341 | retry: | |
e76b7c01 | 342 | if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) { |
718a9163 SB |
343 | return -ENOMEM; |
344 | } | |
345 | ||
346 | mutex_lock(&allocated_ptys_lock); | |
e76b7c01 | 347 | ida_ret = ida_get_new(&fsi->allocated_ptys, &index); |
7ee7c12b | 348 | if (ida_ret < 0) { |
718a9163 | 349 | mutex_unlock(&allocated_ptys_lock); |
7ee7c12b | 350 | if (ida_ret == -EAGAIN) |
718a9163 SB |
351 | goto retry; |
352 | return -EIO; | |
353 | } | |
354 | ||
355 | if (index >= pty_limit) { | |
e76b7c01 | 356 | ida_remove(&fsi->allocated_ptys, index); |
718a9163 SB |
357 | mutex_unlock(&allocated_ptys_lock); |
358 | return -EIO; | |
359 | } | |
360 | mutex_unlock(&allocated_ptys_lock); | |
361 | return index; | |
362 | } | |
363 | ||
15f1a633 | 364 | void devpts_kill_index(struct inode *ptmx_inode, int idx) |
718a9163 | 365 | { |
e76b7c01 SB |
366 | struct super_block *sb = pts_sb_from_inode(ptmx_inode); |
367 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
368 | ||
718a9163 | 369 | mutex_lock(&allocated_ptys_lock); |
e76b7c01 | 370 | ida_remove(&fsi->allocated_ptys, idx); |
718a9163 SB |
371 | mutex_unlock(&allocated_ptys_lock); |
372 | } | |
373 | ||
15f1a633 | 374 | int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) |
1da177e4 | 375 | { |
718a9163 | 376 | int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ |
1da177e4 LT |
377 | struct tty_driver *driver = tty->driver; |
378 | dev_t device = MKDEV(driver->major, driver->minor_start+number); | |
379 | struct dentry *dentry; | |
59e55e6c SB |
380 | struct super_block *sb = pts_sb_from_inode(ptmx_inode); |
381 | struct inode *inode = new_inode(sb); | |
382 | struct dentry *root = sb->s_root; | |
31af0abb SB |
383 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
384 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
89a52e10 | 385 | char s[12]; |
1da177e4 LT |
386 | |
387 | /* We're supposed to be given the slave end of a pty */ | |
388 | BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); | |
389 | BUG_ON(driver->subtype != PTY_TYPE_SLAVE); | |
390 | ||
391 | if (!inode) | |
392 | return -ENOMEM; | |
393 | ||
394 | inode->i_ino = number+2; | |
ec4c2aac DH |
395 | inode->i_uid = config.setuid ? config.uid : current_fsuid(); |
396 | inode->i_gid = config.setgid ? config.gid : current_fsgid(); | |
1da177e4 | 397 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
31af0abb | 398 | init_special_inode(inode, S_IFCHR|opts->mode, device); |
8e18e294 | 399 | inode->i_private = tty; |
a6f37daa | 400 | tty->driver_data = inode; |
1da177e4 | 401 | |
89a52e10 SB |
402 | sprintf(s, "%d", number); |
403 | ||
59e55e6c | 404 | mutex_lock(&root->d_inode->i_mutex); |
89a52e10 | 405 | |
59e55e6c | 406 | dentry = d_alloc_name(root, s); |
89a52e10 SB |
407 | if (!IS_ERR(dentry)) { |
408 | d_add(dentry, inode); | |
59e55e6c | 409 | fsnotify_create(root->d_inode, dentry); |
3972b7f6 | 410 | } |
1da177e4 | 411 | |
59e55e6c | 412 | mutex_unlock(&root->d_inode->i_mutex); |
1da177e4 LT |
413 | |
414 | return 0; | |
415 | } | |
416 | ||
15f1a633 | 417 | struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) |
1da177e4 | 418 | { |
527b3e47 | 419 | BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); |
1da177e4 | 420 | |
527b3e47 SB |
421 | if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) |
422 | return (struct tty_struct *)pts_inode->i_private; | |
423 | return NULL; | |
1da177e4 LT |
424 | } |
425 | ||
15f1a633 | 426 | void devpts_pty_kill(struct tty_struct *tty) |
1da177e4 | 427 | { |
a6f37daa | 428 | struct inode *inode = tty->driver_data; |
59e55e6c SB |
429 | struct super_block *sb = pts_sb_from_inode(inode); |
430 | struct dentry *root = sb->s_root; | |
a6f37daa | 431 | struct dentry *dentry; |
1da177e4 | 432 | |
a6f37daa SB |
433 | BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); |
434 | ||
59e55e6c | 435 | mutex_lock(&root->d_inode->i_mutex); |
a6f37daa SB |
436 | |
437 | dentry = d_find_alias(inode); | |
438 | if (dentry && !IS_ERR(dentry)) { | |
439 | inode->i_nlink--; | |
440 | d_delete(dentry); | |
1da177e4 LT |
441 | dput(dentry); |
442 | } | |
a6f37daa | 443 | |
59e55e6c | 444 | mutex_unlock(&root->d_inode->i_mutex); |
1da177e4 LT |
445 | } |
446 | ||
447 | static int __init init_devpts_fs(void) | |
448 | { | |
449 | int err = register_filesystem(&devpts_fs_type); | |
450 | if (!err) { | |
451 | devpts_mnt = kern_mount(&devpts_fs_type); | |
452 | if (IS_ERR(devpts_mnt)) | |
453 | err = PTR_ERR(devpts_mnt); | |
454 | } | |
455 | return err; | |
456 | } | |
457 | ||
458 | static void __exit exit_devpts_fs(void) | |
459 | { | |
460 | unregister_filesystem(&devpts_fs_type); | |
461 | mntput(devpts_mnt); | |
462 | } | |
463 | ||
464 | module_init(init_devpts_fs) | |
465 | module_exit(exit_devpts_fs) | |
466 | MODULE_LICENSE("GPL"); |