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d6910058 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* -*- linux-c -*- --------------------------------------------------------- * |
3 | * | |
4 | * linux/fs/devpts/inode.c | |
5 | * | |
6 | * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved | |
7 | * | |
1da177e4 LT |
8 | * ------------------------------------------------------------------------- */ |
9 | ||
04541a2f FF |
10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
11 | ||
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/fs.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/namei.h> | |
5a0e3ad6 | 17 | #include <linux/slab.h> |
1da177e4 LT |
18 | #include <linux/mount.h> |
19 | #include <linux/tty.h> | |
718a9163 | 20 | #include <linux/mutex.h> |
1fd7317d | 21 | #include <linux/magic.h> |
718a9163 | 22 | #include <linux/idr.h> |
1da177e4 | 23 | #include <linux/devpts_fs.h> |
7a673c6b | 24 | #include <linux/parser.h> |
3972b7f6 | 25 | #include <linux/fsnotify.h> |
b87a267e | 26 | #include <linux/seq_file.h> |
1da177e4 | 27 | |
b87a267e | 28 | #define DEVPTS_DEFAULT_MODE 0600 |
1f8f1e29 SB |
29 | /* |
30 | * ptmx is a new node in /dev/pts and will be unused in legacy (single- | |
31 | * instance) mode. To prevent surprises in user space, set permissions of | |
32 | * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful | |
33 | * permissions. | |
34 | */ | |
35 | #define DEVPTS_DEFAULT_PTMX_MODE 0000 | |
527b3e47 | 36 | #define PTMX_MINOR 2 |
b87a267e | 37 | |
a4834c10 KK |
38 | /* |
39 | * sysctl support for setting limits on the number of Unix98 ptys allocated. | |
40 | * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. | |
41 | */ | |
42 | static int pty_limit = NR_UNIX98_PTY_DEFAULT; | |
e9aba515 | 43 | static int pty_reserve = NR_UNIX98_PTY_RESERVE; |
a4834c10 | 44 | static int pty_limit_min; |
e9aba515 | 45 | static int pty_limit_max = INT_MAX; |
0f0a0e54 | 46 | static atomic_t pty_count = ATOMIC_INIT(0); |
a4834c10 KK |
47 | |
48 | static struct ctl_table pty_table[] = { | |
49 | { | |
50 | .procname = "max", | |
51 | .maxlen = sizeof(int), | |
52 | .mode = 0644, | |
53 | .data = &pty_limit, | |
54 | .proc_handler = proc_dointvec_minmax, | |
55 | .extra1 = &pty_limit_min, | |
56 | .extra2 = &pty_limit_max, | |
e9aba515 KK |
57 | }, { |
58 | .procname = "reserve", | |
59 | .maxlen = sizeof(int), | |
60 | .mode = 0644, | |
61 | .data = &pty_reserve, | |
62 | .proc_handler = proc_dointvec_minmax, | |
63 | .extra1 = &pty_limit_min, | |
64 | .extra2 = &pty_limit_max, | |
a4834c10 KK |
65 | }, { |
66 | .procname = "nr", | |
67 | .maxlen = sizeof(int), | |
68 | .mode = 0444, | |
69 | .data = &pty_count, | |
70 | .proc_handler = proc_dointvec, | |
71 | }, | |
72 | {} | |
73 | }; | |
74 | ||
75 | static struct ctl_table pty_kern_table[] = { | |
76 | { | |
77 | .procname = "pty", | |
78 | .mode = 0555, | |
79 | .child = pty_table, | |
80 | }, | |
81 | {} | |
82 | }; | |
83 | ||
84 | static struct ctl_table pty_root_table[] = { | |
85 | { | |
86 | .procname = "kernel", | |
87 | .mode = 0555, | |
88 | .child = pty_kern_table, | |
89 | }, | |
90 | {} | |
91 | }; | |
92 | ||
31af0abb | 93 | struct pts_mount_opts { |
1da177e4 LT |
94 | int setuid; |
95 | int setgid; | |
f04c6ce2 EB |
96 | kuid_t uid; |
97 | kgid_t gid; | |
1da177e4 | 98 | umode_t mode; |
1f8f1e29 | 99 | umode_t ptmxmode; |
eedf265a | 100 | int reserve; |
e9aba515 | 101 | int max; |
31af0abb | 102 | }; |
1da177e4 | 103 | |
7a673c6b | 104 | enum { |
e9aba515 | 105 | Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, |
7a673c6b DP |
106 | Opt_err |
107 | }; | |
108 | ||
a447c093 | 109 | static const match_table_t tokens = { |
7a673c6b DP |
110 | {Opt_uid, "uid=%u"}, |
111 | {Opt_gid, "gid=%u"}, | |
112 | {Opt_mode, "mode=%o"}, | |
1f8f1e29 | 113 | {Opt_ptmxmode, "ptmxmode=%o"}, |
2a1b2dc0 | 114 | {Opt_newinstance, "newinstance"}, |
e9aba515 | 115 | {Opt_max, "max=%d"}, |
7a673c6b DP |
116 | {Opt_err, NULL} |
117 | }; | |
118 | ||
e76b7c01 SB |
119 | struct pts_fs_info { |
120 | struct ida allocated_ptys; | |
31af0abb | 121 | struct pts_mount_opts mount_opts; |
67245ff3 | 122 | struct super_block *sb; |
1f8f1e29 | 123 | struct dentry *ptmx_dentry; |
e76b7c01 SB |
124 | }; |
125 | ||
126 | static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) | |
127 | { | |
128 | return sb->s_fs_info; | |
129 | } | |
130 | ||
311fc65c EB |
131 | static int devpts_ptmx_path(struct path *path) |
132 | { | |
133 | struct super_block *sb; | |
134 | int err; | |
135 | ||
311fc65c EB |
136 | /* Is a devpts filesystem at "pts" in the same directory? */ |
137 | err = path_pts(path); | |
138 | if (err) | |
139 | return err; | |
140 | ||
141 | /* Is the path the root of a devpts filesystem? */ | |
142 | sb = path->mnt->mnt_sb; | |
143 | if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
144 | (path->mnt->mnt_root != sb->s_root)) | |
145 | return -ENODEV; | |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
4e15f760 CB |
150 | /* |
151 | * Try to find a suitable devpts filesystem. We support the following | |
152 | * scenarios: | |
153 | * - The ptmx device node is located in the same directory as the devpts | |
154 | * mount where the pts device nodes are located. | |
155 | * This is e.g. the case when calling open on the /dev/pts/ptmx device | |
156 | * node when the devpts filesystem is mounted at /dev/pts. | |
157 | * - The ptmx device node is located outside the devpts filesystem mount | |
158 | * where the pts device nodes are located. For example, the ptmx device | |
159 | * is a symlink, separate device node, or bind-mount. | |
160 | * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and | |
161 | * then calling open on /dev/ptmx. In this case a suitable pts | |
162 | * subdirectory can be found in the common parent directory /dev of the | |
163 | * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx | |
164 | * bind-mount. | |
165 | * If no suitable pts subdirectory can be found this function will fail. | |
166 | * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. | |
167 | */ | |
311fc65c EB |
168 | struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) |
169 | { | |
170 | struct path path; | |
7d71109d | 171 | int err = 0; |
311fc65c EB |
172 | |
173 | path = filp->f_path; | |
174 | path_get(&path); | |
175 | ||
a319b01d CB |
176 | /* Walk upward while the start point is a bind mount of |
177 | * a single file. | |
178 | */ | |
179 | while (path.mnt->mnt_root == path.dentry) | |
180 | if (follow_up(&path) == 0) | |
181 | break; | |
182 | ||
183 | /* devpts_ptmx_path() finds a devpts fs or returns an error. */ | |
184 | if ((path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
185 | (DEVPTS_SB(path.mnt->mnt_sb) != fsi)) | |
7d71109d | 186 | err = devpts_ptmx_path(&path); |
311fc65c | 187 | dput(path.dentry); |
a319b01d CB |
188 | if (!err) { |
189 | if (DEVPTS_SB(path.mnt->mnt_sb) == fsi) | |
190 | return path.mnt; | |
7d71109d | 191 | |
a319b01d | 192 | err = -ENODEV; |
311fc65c | 193 | } |
7d71109d | 194 | |
a319b01d CB |
195 | mntput(path.mnt); |
196 | return ERR_PTR(err); | |
311fc65c EB |
197 | } |
198 | ||
143c97cc | 199 | struct pts_fs_info *devpts_acquire(struct file *filp) |
59e55e6c | 200 | { |
eedf265a EB |
201 | struct pts_fs_info *result; |
202 | struct path path; | |
203 | struct super_block *sb; | |
eedf265a EB |
204 | |
205 | path = filp->f_path; | |
206 | path_get(&path); | |
207 | ||
7d71109d CB |
208 | /* Has the devpts filesystem already been found? */ |
209 | if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { | |
210 | int err; | |
211 | ||
212 | err = devpts_ptmx_path(&path); | |
213 | if (err) { | |
214 | result = ERR_PTR(err); | |
215 | goto out; | |
216 | } | |
eedf265a EB |
217 | } |
218 | ||
219 | /* | |
220 | * pty code needs to hold extra references in case of last /dev/tty close | |
221 | */ | |
311fc65c | 222 | sb = path.mnt->mnt_sb; |
eedf265a EB |
223 | atomic_inc(&sb->s_active); |
224 | result = DEVPTS_SB(sb); | |
225 | ||
226 | out: | |
227 | path_put(&path); | |
228 | return result; | |
229 | } | |
230 | ||
231 | void devpts_release(struct pts_fs_info *fsi) | |
232 | { | |
233 | deactivate_super(fsi->sb); | |
59e55e6c SB |
234 | } |
235 | ||
2a1b2dc0 SB |
236 | #define PARSE_MOUNT 0 |
237 | #define PARSE_REMOUNT 1 | |
238 | ||
1f71ebed SB |
239 | /* |
240 | * parse_mount_options(): | |
04541a2f | 241 | * Set @opts to mount options specified in @data. If an option is not |
eedf265a | 242 | * specified in @data, set it to its default value. |
1f71ebed SB |
243 | * |
244 | * Note: @data may be NULL (in which case all options are set to default). | |
245 | */ | |
2a1b2dc0 | 246 | static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) |
1da177e4 | 247 | { |
7a673c6b | 248 | char *p; |
f04c6ce2 EB |
249 | kuid_t uid; |
250 | kgid_t gid; | |
7a673c6b | 251 | |
31af0abb SB |
252 | opts->setuid = 0; |
253 | opts->setgid = 0; | |
f04c6ce2 EB |
254 | opts->uid = GLOBAL_ROOT_UID; |
255 | opts->gid = GLOBAL_ROOT_GID; | |
31af0abb | 256 | opts->mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 257 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e9aba515 | 258 | opts->max = NR_UNIX98_PTY_MAX; |
7a673c6b | 259 | |
eedf265a EB |
260 | /* Only allow instances mounted from the initial mount |
261 | * namespace to tap the reserve pool of ptys. | |
262 | */ | |
2a1b2dc0 | 263 | if (op == PARSE_MOUNT) |
eedf265a EB |
264 | opts->reserve = |
265 | (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); | |
2a1b2dc0 | 266 | |
7a673c6b DP |
267 | while ((p = strsep(&data, ",")) != NULL) { |
268 | substring_t args[MAX_OPT_ARGS]; | |
269 | int token; | |
270 | int option; | |
271 | ||
272 | if (!*p) | |
1da177e4 | 273 | continue; |
7a673c6b DP |
274 | |
275 | token = match_token(p, tokens, args); | |
276 | switch (token) { | |
277 | case Opt_uid: | |
278 | if (match_int(&args[0], &option)) | |
279 | return -EINVAL; | |
f04c6ce2 EB |
280 | uid = make_kuid(current_user_ns(), option); |
281 | if (!uid_valid(uid)) | |
282 | return -EINVAL; | |
283 | opts->uid = uid; | |
31af0abb | 284 | opts->setuid = 1; |
7a673c6b DP |
285 | break; |
286 | case Opt_gid: | |
287 | if (match_int(&args[0], &option)) | |
288 | return -EINVAL; | |
f04c6ce2 EB |
289 | gid = make_kgid(current_user_ns(), option); |
290 | if (!gid_valid(gid)) | |
291 | return -EINVAL; | |
292 | opts->gid = gid; | |
31af0abb | 293 | opts->setgid = 1; |
7a673c6b DP |
294 | break; |
295 | case Opt_mode: | |
296 | if (match_octal(&args[0], &option)) | |
297 | return -EINVAL; | |
31af0abb | 298 | opts->mode = option & S_IALLUGO; |
7a673c6b | 299 | break; |
1f8f1e29 SB |
300 | case Opt_ptmxmode: |
301 | if (match_octal(&args[0], &option)) | |
302 | return -EINVAL; | |
303 | opts->ptmxmode = option & S_IALLUGO; | |
304 | break; | |
2a1b2dc0 | 305 | case Opt_newinstance: |
2a1b2dc0 | 306 | break; |
e9aba515 KK |
307 | case Opt_max: |
308 | if (match_int(&args[0], &option) || | |
309 | option < 0 || option > NR_UNIX98_PTY_MAX) | |
310 | return -EINVAL; | |
311 | opts->max = option; | |
312 | break; | |
7a673c6b | 313 | default: |
04541a2f | 314 | pr_err("called with bogus options\n"); |
1da177e4 LT |
315 | return -EINVAL; |
316 | } | |
317 | } | |
1da177e4 LT |
318 | |
319 | return 0; | |
320 | } | |
321 | ||
1f8f1e29 SB |
322 | static int mknod_ptmx(struct super_block *sb) |
323 | { | |
324 | int mode; | |
325 | int rc = -ENOMEM; | |
326 | struct dentry *dentry; | |
327 | struct inode *inode; | |
328 | struct dentry *root = sb->s_root; | |
329 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
330 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
e98d4137 EB |
331 | kuid_t ptmx_uid = current_fsuid(); |
332 | kgid_t ptmx_gid = current_fsgid(); | |
1f8f1e29 | 333 | |
5955102c | 334 | inode_lock(d_inode(root)); |
1f8f1e29 SB |
335 | |
336 | /* If we have already created ptmx node, return */ | |
337 | if (fsi->ptmx_dentry) { | |
338 | rc = 0; | |
339 | goto out; | |
340 | } | |
341 | ||
342 | dentry = d_alloc_name(root, "ptmx"); | |
343 | if (!dentry) { | |
04541a2f | 344 | pr_err("Unable to alloc dentry for ptmx node\n"); |
1f8f1e29 SB |
345 | goto out; |
346 | } | |
347 | ||
348 | /* | |
349 | * Create a new 'ptmx' node in this mount of devpts. | |
350 | */ | |
351 | inode = new_inode(sb); | |
352 | if (!inode) { | |
04541a2f | 353 | pr_err("Unable to alloc inode for ptmx node\n"); |
1f8f1e29 SB |
354 | dput(dentry); |
355 | goto out; | |
356 | } | |
357 | ||
358 | inode->i_ino = 2; | |
078cd827 | 359 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1f8f1e29 SB |
360 | |
361 | mode = S_IFCHR|opts->ptmxmode; | |
362 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
e98d4137 EB |
363 | inode->i_uid = ptmx_uid; |
364 | inode->i_gid = ptmx_gid; | |
1f8f1e29 SB |
365 | |
366 | d_add(dentry, inode); | |
367 | ||
368 | fsi->ptmx_dentry = dentry; | |
369 | rc = 0; | |
1f8f1e29 | 370 | out: |
5955102c | 371 | inode_unlock(d_inode(root)); |
1f8f1e29 SB |
372 | return rc; |
373 | } | |
374 | ||
375 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
376 | { | |
377 | struct inode *inode; | |
378 | if (fsi->ptmx_dentry) { | |
2b0143b5 | 379 | inode = d_inode(fsi->ptmx_dentry); |
1f8f1e29 SB |
380 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; |
381 | } | |
382 | } | |
1f8f1e29 | 383 | |
53af8ee4 SB |
384 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
385 | { | |
1f8f1e29 | 386 | int err; |
53af8ee4 SB |
387 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
388 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
389 | ||
2a1b2dc0 | 390 | err = parse_mount_options(data, PARSE_REMOUNT, opts); |
1f8f1e29 SB |
391 | |
392 | /* | |
393 | * parse_mount_options() restores options to default values | |
394 | * before parsing and may have changed ptmxmode. So, update the | |
395 | * mode in the inode too. Bogus options don't fail the remount, | |
396 | * so do this even on error return. | |
397 | */ | |
398 | update_ptmx_mode(fsi); | |
399 | ||
400 | return err; | |
53af8ee4 SB |
401 | } |
402 | ||
34c80b1d | 403 | static int devpts_show_options(struct seq_file *seq, struct dentry *root) |
b87a267e | 404 | { |
34c80b1d | 405 | struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); |
31af0abb SB |
406 | struct pts_mount_opts *opts = &fsi->mount_opts; |
407 | ||
408 | if (opts->setuid) | |
04541a2f FF |
409 | seq_printf(seq, ",uid=%u", |
410 | from_kuid_munged(&init_user_ns, opts->uid)); | |
31af0abb | 411 | if (opts->setgid) |
04541a2f FF |
412 | seq_printf(seq, ",gid=%u", |
413 | from_kgid_munged(&init_user_ns, opts->gid)); | |
31af0abb | 414 | seq_printf(seq, ",mode=%03o", opts->mode); |
1f8f1e29 | 415 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); |
e9aba515 KK |
416 | if (opts->max < NR_UNIX98_PTY_MAX) |
417 | seq_printf(seq, ",max=%d", opts->max); | |
b87a267e MS |
418 | |
419 | return 0; | |
420 | } | |
421 | ||
ee9b6d61 | 422 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
423 | .statfs = simple_statfs, |
424 | .remount_fs = devpts_remount, | |
b87a267e | 425 | .show_options = devpts_show_options, |
1da177e4 LT |
426 | }; |
427 | ||
67245ff3 | 428 | static void *new_pts_fs_info(struct super_block *sb) |
e76b7c01 SB |
429 | { |
430 | struct pts_fs_info *fsi; | |
431 | ||
432 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
433 | if (!fsi) | |
434 | return NULL; | |
435 | ||
436 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 437 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 438 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
67245ff3 | 439 | fsi->sb = sb; |
e76b7c01 SB |
440 | |
441 | return fsi; | |
442 | } | |
443 | ||
1da177e4 LT |
444 | static int |
445 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
446 | { | |
1f8f1e29 | 447 | struct inode *inode; |
dee87d47 | 448 | int error; |
1da177e4 | 449 | |
cc50a07a | 450 | s->s_iflags &= ~SB_I_NODEV; |
1da177e4 LT |
451 | s->s_blocksize = 1024; |
452 | s->s_blocksize_bits = 10; | |
453 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
454 | s->s_op = &devpts_sops; | |
73052b0d | 455 | s->s_d_op = &simple_dentry_operations; |
1da177e4 LT |
456 | s->s_time_gran = 1; |
457 | ||
dee87d47 | 458 | error = -ENOMEM; |
67245ff3 | 459 | s->s_fs_info = new_pts_fs_info(s); |
e76b7c01 SB |
460 | if (!s->s_fs_info) |
461 | goto fail; | |
462 | ||
dee87d47 EB |
463 | error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); |
464 | if (error) | |
465 | goto fail; | |
466 | ||
467 | error = -ENOMEM; | |
1da177e4 LT |
468 | inode = new_inode(s); |
469 | if (!inode) | |
3850aba7 | 470 | goto fail; |
1da177e4 | 471 | inode->i_ino = 1; |
078cd827 | 472 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1da177e4 LT |
473 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; |
474 | inode->i_op = &simple_dir_inode_operations; | |
475 | inode->i_fop = &simple_dir_operations; | |
bfe86848 | 476 | set_nlink(inode, 2); |
1da177e4 | 477 | |
48fde701 | 478 | s->s_root = d_make_root(inode); |
180d9044 EB |
479 | if (!s->s_root) { |
480 | pr_err("get root dentry failed\n"); | |
481 | goto fail; | |
482 | } | |
1f8f1e29 | 483 | |
180d9044 EB |
484 | error = mknod_ptmx(s); |
485 | if (error) | |
486 | goto fail_dput; | |
e76b7c01 | 487 | |
180d9044 EB |
488 | return 0; |
489 | fail_dput: | |
490 | dput(s->s_root); | |
491 | s->s_root = NULL; | |
1da177e4 | 492 | fail: |
dee87d47 | 493 | return error; |
1da177e4 LT |
494 | } |
495 | ||
2a1b2dc0 | 496 | /* |
fc14f2fe | 497 | * devpts_mount() |
1bd79035 | 498 | * |
eedf265a EB |
499 | * Mount a new (private) instance of devpts. PTYs created in this |
500 | * instance are independent of the PTYs in other devpts instances. | |
d4076ac5 | 501 | */ |
fc14f2fe AV |
502 | static struct dentry *devpts_mount(struct file_system_type *fs_type, |
503 | int flags, const char *dev_name, void *data) | |
1da177e4 | 504 | { |
c1b241f0 | 505 | return mount_nodev(fs_type, flags, data, devpts_fill_super); |
1da177e4 | 506 | } |
482984f0 | 507 | |
e76b7c01 SB |
508 | static void devpts_kill_sb(struct super_block *sb) |
509 | { | |
510 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
511 | ||
40b320e1 EB |
512 | if (fsi) |
513 | ida_destroy(&fsi->allocated_ptys); | |
e76b7c01 | 514 | kfree(fsi); |
1f8f1e29 | 515 | kill_litter_super(sb); |
e76b7c01 SB |
516 | } |
517 | ||
1da177e4 | 518 | static struct file_system_type devpts_fs_type = { |
1da177e4 | 519 | .name = "devpts", |
fc14f2fe | 520 | .mount = devpts_mount, |
e76b7c01 | 521 | .kill_sb = devpts_kill_sb, |
cc50a07a | 522 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
523 | }; |
524 | ||
525 | /* | |
526 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
527 | * to the System V naming convention | |
528 | */ | |
529 | ||
67245ff3 | 530 | int devpts_new_index(struct pts_fs_info *fsi) |
718a9163 | 531 | { |
0f0a0e54 | 532 | int index = -ENOSPC; |
e9aba515 | 533 | |
0f0a0e54 MW |
534 | if (atomic_inc_return(&pty_count) >= (pty_limit - |
535 | (fsi->mount_opts.reserve ? 0 : pty_reserve))) | |
536 | goto out; | |
718a9163 | 537 | |
0f0a0e54 MW |
538 | index = ida_alloc_max(&fsi->allocated_ptys, fsi->mount_opts.max - 1, |
539 | GFP_KERNEL); | |
540 | ||
541 | out: | |
542 | if (index < 0) | |
543 | atomic_dec(&pty_count); | |
718a9163 SB |
544 | return index; |
545 | } | |
546 | ||
67245ff3 | 547 | void devpts_kill_index(struct pts_fs_info *fsi, int idx) |
718a9163 | 548 | { |
0f0a0e54 MW |
549 | ida_free(&fsi->allocated_ptys, idx); |
550 | atomic_dec(&pty_count); | |
718a9163 SB |
551 | } |
552 | ||
1dcb8e6d JS |
553 | /** |
554 | * devpts_pty_new -- create a new inode in /dev/pts/ | |
555 | * @ptmx_inode: inode of the master | |
556 | * @device: major+minor of the node to be created | |
557 | * @index: used as a name of the node | |
558 | * @priv: what's given back by devpts_get_priv | |
559 | * | |
560 | * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. | |
561 | */ | |
8ead9dd5 | 562 | struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) |
1da177e4 | 563 | { |
1da177e4 | 564 | struct dentry *dentry; |
eedf265a | 565 | struct super_block *sb = fsi->sb; |
162b97cf | 566 | struct inode *inode; |
9ce71148 | 567 | struct dentry *root; |
9ce71148 | 568 | struct pts_mount_opts *opts; |
89a52e10 | 569 | char s[12]; |
1da177e4 | 570 | |
9ce71148 | 571 | root = sb->s_root; |
9ce71148 JT |
572 | opts = &fsi->mount_opts; |
573 | ||
162b97cf | 574 | inode = new_inode(sb); |
1da177e4 | 575 | if (!inode) |
162b97cf | 576 | return ERR_PTR(-ENOMEM); |
1da177e4 | 577 | |
f11afb61 | 578 | inode->i_ino = index + 3; |
d0eafc7d DH |
579 | inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); |
580 | inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); | |
078cd827 | 581 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
8ead9dd5 | 582 | init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); |
1da177e4 | 583 | |
f11afb61 | 584 | sprintf(s, "%d", index); |
89a52e10 | 585 | |
59e55e6c | 586 | dentry = d_alloc_name(root, s); |
b12d1259 | 587 | if (dentry) { |
8ead9dd5 | 588 | dentry->d_fsdata = priv; |
89a52e10 | 589 | d_add(dentry, inode); |
2b0143b5 | 590 | fsnotify_create(d_inode(root), dentry); |
aa597bc1 AV |
591 | } else { |
592 | iput(inode); | |
8ead9dd5 | 593 | dentry = ERR_PTR(-ENOMEM); |
3972b7f6 | 594 | } |
1da177e4 | 595 | |
8ead9dd5 | 596 | return dentry; |
1da177e4 LT |
597 | } |
598 | ||
1dcb8e6d JS |
599 | /** |
600 | * devpts_get_priv -- get private data for a slave | |
601 | * @pts_inode: inode of the slave | |
602 | * | |
603 | * Returns whatever was passed as priv in devpts_pty_new for a given inode. | |
604 | */ | |
8ead9dd5 | 605 | void *devpts_get_priv(struct dentry *dentry) |
1da177e4 | 606 | { |
3e423945 LT |
607 | if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) |
608 | return NULL; | |
8ead9dd5 | 609 | return dentry->d_fsdata; |
1da177e4 LT |
610 | } |
611 | ||
1dcb8e6d JS |
612 | /** |
613 | * devpts_pty_kill -- remove inode form /dev/pts/ | |
614 | * @inode: inode of the slave to be removed | |
615 | * | |
616 | * This is an inverse operation of devpts_pty_new. | |
617 | */ | |
8ead9dd5 | 618 | void devpts_pty_kill(struct dentry *dentry) |
1da177e4 | 619 | { |
8ead9dd5 | 620 | WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); |
1da177e4 | 621 | |
8ead9dd5 LT |
622 | dentry->d_fsdata = NULL; |
623 | drop_nlink(dentry->d_inode); | |
fd0d506f | 624 | fsnotify_unlink(d_inode(dentry->d_parent), dentry); |
aa597bc1 AV |
625 | d_delete(dentry); |
626 | dput(dentry); /* d_alloc_name() in devpts_pty_new() */ | |
1da177e4 LT |
627 | } |
628 | ||
629 | static int __init init_devpts_fs(void) | |
630 | { | |
631 | int err = register_filesystem(&devpts_fs_type); | |
632 | if (!err) { | |
eedf265a | 633 | register_sysctl_table(pty_root_table); |
1da177e4 LT |
634 | } |
635 | return err; | |
636 | } | |
1da177e4 | 637 | module_init(init_devpts_fs) |