Commit | Line | Data |
---|---|---|
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 | ||
31af0abb | 75 | struct pts_mount_opts { |
1da177e4 LT |
76 | int setuid; |
77 | int setgid; | |
f04c6ce2 EB |
78 | kuid_t uid; |
79 | kgid_t gid; | |
1da177e4 | 80 | umode_t mode; |
1f8f1e29 | 81 | umode_t ptmxmode; |
eedf265a | 82 | int reserve; |
e9aba515 | 83 | int max; |
31af0abb | 84 | }; |
1da177e4 | 85 | |
7a673c6b | 86 | enum { |
e9aba515 | 87 | Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, |
7a673c6b DP |
88 | Opt_err |
89 | }; | |
90 | ||
a447c093 | 91 | static const match_table_t tokens = { |
7a673c6b DP |
92 | {Opt_uid, "uid=%u"}, |
93 | {Opt_gid, "gid=%u"}, | |
94 | {Opt_mode, "mode=%o"}, | |
1f8f1e29 | 95 | {Opt_ptmxmode, "ptmxmode=%o"}, |
2a1b2dc0 | 96 | {Opt_newinstance, "newinstance"}, |
e9aba515 | 97 | {Opt_max, "max=%d"}, |
7a673c6b DP |
98 | {Opt_err, NULL} |
99 | }; | |
100 | ||
e76b7c01 SB |
101 | struct pts_fs_info { |
102 | struct ida allocated_ptys; | |
31af0abb | 103 | struct pts_mount_opts mount_opts; |
67245ff3 | 104 | struct super_block *sb; |
1f8f1e29 | 105 | struct dentry *ptmx_dentry; |
e76b7c01 SB |
106 | }; |
107 | ||
108 | static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) | |
109 | { | |
110 | return sb->s_fs_info; | |
111 | } | |
112 | ||
311fc65c EB |
113 | static int devpts_ptmx_path(struct path *path) |
114 | { | |
115 | struct super_block *sb; | |
116 | int err; | |
117 | ||
311fc65c EB |
118 | /* Is a devpts filesystem at "pts" in the same directory? */ |
119 | err = path_pts(path); | |
120 | if (err) | |
121 | return err; | |
122 | ||
123 | /* Is the path the root of a devpts filesystem? */ | |
124 | sb = path->mnt->mnt_sb; | |
125 | if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
126 | (path->mnt->mnt_root != sb->s_root)) | |
127 | return -ENODEV; | |
128 | ||
129 | return 0; | |
130 | } | |
131 | ||
4e15f760 CB |
132 | /* |
133 | * Try to find a suitable devpts filesystem. We support the following | |
134 | * scenarios: | |
135 | * - The ptmx device node is located in the same directory as the devpts | |
136 | * mount where the pts device nodes are located. | |
137 | * This is e.g. the case when calling open on the /dev/pts/ptmx device | |
138 | * node when the devpts filesystem is mounted at /dev/pts. | |
139 | * - The ptmx device node is located outside the devpts filesystem mount | |
140 | * where the pts device nodes are located. For example, the ptmx device | |
141 | * is a symlink, separate device node, or bind-mount. | |
142 | * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and | |
143 | * then calling open on /dev/ptmx. In this case a suitable pts | |
144 | * subdirectory can be found in the common parent directory /dev of the | |
145 | * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx | |
146 | * bind-mount. | |
147 | * If no suitable pts subdirectory can be found this function will fail. | |
148 | * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. | |
149 | */ | |
311fc65c EB |
150 | struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) |
151 | { | |
152 | struct path path; | |
7d71109d | 153 | int err = 0; |
311fc65c EB |
154 | |
155 | path = filp->f_path; | |
156 | path_get(&path); | |
157 | ||
a319b01d CB |
158 | /* Walk upward while the start point is a bind mount of |
159 | * a single file. | |
160 | */ | |
161 | while (path.mnt->mnt_root == path.dentry) | |
162 | if (follow_up(&path) == 0) | |
163 | break; | |
164 | ||
165 | /* devpts_ptmx_path() finds a devpts fs or returns an error. */ | |
166 | if ((path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
167 | (DEVPTS_SB(path.mnt->mnt_sb) != fsi)) | |
7d71109d | 168 | err = devpts_ptmx_path(&path); |
311fc65c | 169 | dput(path.dentry); |
a319b01d CB |
170 | if (!err) { |
171 | if (DEVPTS_SB(path.mnt->mnt_sb) == fsi) | |
172 | return path.mnt; | |
7d71109d | 173 | |
a319b01d | 174 | err = -ENODEV; |
311fc65c | 175 | } |
7d71109d | 176 | |
a319b01d CB |
177 | mntput(path.mnt); |
178 | return ERR_PTR(err); | |
311fc65c EB |
179 | } |
180 | ||
143c97cc | 181 | struct pts_fs_info *devpts_acquire(struct file *filp) |
59e55e6c | 182 | { |
eedf265a EB |
183 | struct pts_fs_info *result; |
184 | struct path path; | |
185 | struct super_block *sb; | |
eedf265a EB |
186 | |
187 | path = filp->f_path; | |
188 | path_get(&path); | |
189 | ||
7d71109d CB |
190 | /* Has the devpts filesystem already been found? */ |
191 | if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { | |
192 | int err; | |
193 | ||
194 | err = devpts_ptmx_path(&path); | |
195 | if (err) { | |
196 | result = ERR_PTR(err); | |
197 | goto out; | |
198 | } | |
eedf265a EB |
199 | } |
200 | ||
201 | /* | |
202 | * pty code needs to hold extra references in case of last /dev/tty close | |
203 | */ | |
311fc65c | 204 | sb = path.mnt->mnt_sb; |
eedf265a EB |
205 | atomic_inc(&sb->s_active); |
206 | result = DEVPTS_SB(sb); | |
207 | ||
208 | out: | |
209 | path_put(&path); | |
210 | return result; | |
211 | } | |
212 | ||
213 | void devpts_release(struct pts_fs_info *fsi) | |
214 | { | |
215 | deactivate_super(fsi->sb); | |
59e55e6c SB |
216 | } |
217 | ||
2a1b2dc0 SB |
218 | #define PARSE_MOUNT 0 |
219 | #define PARSE_REMOUNT 1 | |
220 | ||
1f71ebed SB |
221 | /* |
222 | * parse_mount_options(): | |
04541a2f | 223 | * Set @opts to mount options specified in @data. If an option is not |
eedf265a | 224 | * specified in @data, set it to its default value. |
1f71ebed SB |
225 | * |
226 | * Note: @data may be NULL (in which case all options are set to default). | |
227 | */ | |
2a1b2dc0 | 228 | static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) |
1da177e4 | 229 | { |
7a673c6b | 230 | char *p; |
f04c6ce2 EB |
231 | kuid_t uid; |
232 | kgid_t gid; | |
7a673c6b | 233 | |
31af0abb SB |
234 | opts->setuid = 0; |
235 | opts->setgid = 0; | |
f04c6ce2 EB |
236 | opts->uid = GLOBAL_ROOT_UID; |
237 | opts->gid = GLOBAL_ROOT_GID; | |
31af0abb | 238 | opts->mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 239 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e9aba515 | 240 | opts->max = NR_UNIX98_PTY_MAX; |
7a673c6b | 241 | |
eedf265a EB |
242 | /* Only allow instances mounted from the initial mount |
243 | * namespace to tap the reserve pool of ptys. | |
244 | */ | |
2a1b2dc0 | 245 | if (op == PARSE_MOUNT) |
eedf265a EB |
246 | opts->reserve = |
247 | (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); | |
2a1b2dc0 | 248 | |
7a673c6b DP |
249 | while ((p = strsep(&data, ",")) != NULL) { |
250 | substring_t args[MAX_OPT_ARGS]; | |
251 | int token; | |
252 | int option; | |
253 | ||
254 | if (!*p) | |
1da177e4 | 255 | continue; |
7a673c6b DP |
256 | |
257 | token = match_token(p, tokens, args); | |
258 | switch (token) { | |
259 | case Opt_uid: | |
260 | if (match_int(&args[0], &option)) | |
261 | return -EINVAL; | |
f04c6ce2 EB |
262 | uid = make_kuid(current_user_ns(), option); |
263 | if (!uid_valid(uid)) | |
264 | return -EINVAL; | |
265 | opts->uid = uid; | |
31af0abb | 266 | opts->setuid = 1; |
7a673c6b DP |
267 | break; |
268 | case Opt_gid: | |
269 | if (match_int(&args[0], &option)) | |
270 | return -EINVAL; | |
f04c6ce2 EB |
271 | gid = make_kgid(current_user_ns(), option); |
272 | if (!gid_valid(gid)) | |
273 | return -EINVAL; | |
274 | opts->gid = gid; | |
31af0abb | 275 | opts->setgid = 1; |
7a673c6b DP |
276 | break; |
277 | case Opt_mode: | |
278 | if (match_octal(&args[0], &option)) | |
279 | return -EINVAL; | |
31af0abb | 280 | opts->mode = option & S_IALLUGO; |
7a673c6b | 281 | break; |
1f8f1e29 SB |
282 | case Opt_ptmxmode: |
283 | if (match_octal(&args[0], &option)) | |
284 | return -EINVAL; | |
285 | opts->ptmxmode = option & S_IALLUGO; | |
286 | break; | |
2a1b2dc0 | 287 | case Opt_newinstance: |
2a1b2dc0 | 288 | break; |
e9aba515 KK |
289 | case Opt_max: |
290 | if (match_int(&args[0], &option) || | |
291 | option < 0 || option > NR_UNIX98_PTY_MAX) | |
292 | return -EINVAL; | |
293 | opts->max = option; | |
294 | break; | |
7a673c6b | 295 | default: |
04541a2f | 296 | pr_err("called with bogus options\n"); |
1da177e4 LT |
297 | return -EINVAL; |
298 | } | |
299 | } | |
1da177e4 LT |
300 | |
301 | return 0; | |
302 | } | |
303 | ||
1f8f1e29 SB |
304 | static int mknod_ptmx(struct super_block *sb) |
305 | { | |
306 | int mode; | |
307 | int rc = -ENOMEM; | |
308 | struct dentry *dentry; | |
309 | struct inode *inode; | |
310 | struct dentry *root = sb->s_root; | |
311 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
312 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
e98d4137 EB |
313 | kuid_t ptmx_uid = current_fsuid(); |
314 | kgid_t ptmx_gid = current_fsgid(); | |
1f8f1e29 | 315 | |
5955102c | 316 | inode_lock(d_inode(root)); |
1f8f1e29 SB |
317 | |
318 | /* If we have already created ptmx node, return */ | |
319 | if (fsi->ptmx_dentry) { | |
320 | rc = 0; | |
321 | goto out; | |
322 | } | |
323 | ||
324 | dentry = d_alloc_name(root, "ptmx"); | |
325 | if (!dentry) { | |
04541a2f | 326 | pr_err("Unable to alloc dentry for ptmx node\n"); |
1f8f1e29 SB |
327 | goto out; |
328 | } | |
329 | ||
330 | /* | |
331 | * Create a new 'ptmx' node in this mount of devpts. | |
332 | */ | |
333 | inode = new_inode(sb); | |
334 | if (!inode) { | |
04541a2f | 335 | pr_err("Unable to alloc inode for ptmx node\n"); |
1f8f1e29 SB |
336 | dput(dentry); |
337 | goto out; | |
338 | } | |
339 | ||
340 | inode->i_ino = 2; | |
2ca7b9cd | 341 | inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode); |
1f8f1e29 SB |
342 | |
343 | mode = S_IFCHR|opts->ptmxmode; | |
344 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
e98d4137 EB |
345 | inode->i_uid = ptmx_uid; |
346 | inode->i_gid = ptmx_gid; | |
1f8f1e29 SB |
347 | |
348 | d_add(dentry, inode); | |
349 | ||
350 | fsi->ptmx_dentry = dentry; | |
351 | rc = 0; | |
1f8f1e29 | 352 | out: |
5955102c | 353 | inode_unlock(d_inode(root)); |
1f8f1e29 SB |
354 | return rc; |
355 | } | |
356 | ||
357 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
358 | { | |
359 | struct inode *inode; | |
360 | if (fsi->ptmx_dentry) { | |
2b0143b5 | 361 | inode = d_inode(fsi->ptmx_dentry); |
1f8f1e29 SB |
362 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; |
363 | } | |
364 | } | |
1f8f1e29 | 365 | |
53af8ee4 SB |
366 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
367 | { | |
1f8f1e29 | 368 | int err; |
53af8ee4 SB |
369 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
370 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
371 | ||
2a1b2dc0 | 372 | err = parse_mount_options(data, PARSE_REMOUNT, opts); |
1f8f1e29 SB |
373 | |
374 | /* | |
375 | * parse_mount_options() restores options to default values | |
376 | * before parsing and may have changed ptmxmode. So, update the | |
377 | * mode in the inode too. Bogus options don't fail the remount, | |
378 | * so do this even on error return. | |
379 | */ | |
380 | update_ptmx_mode(fsi); | |
381 | ||
382 | return err; | |
53af8ee4 SB |
383 | } |
384 | ||
34c80b1d | 385 | static int devpts_show_options(struct seq_file *seq, struct dentry *root) |
b87a267e | 386 | { |
34c80b1d | 387 | struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); |
31af0abb SB |
388 | struct pts_mount_opts *opts = &fsi->mount_opts; |
389 | ||
390 | if (opts->setuid) | |
04541a2f FF |
391 | seq_printf(seq, ",uid=%u", |
392 | from_kuid_munged(&init_user_ns, opts->uid)); | |
31af0abb | 393 | if (opts->setgid) |
04541a2f FF |
394 | seq_printf(seq, ",gid=%u", |
395 | from_kgid_munged(&init_user_ns, opts->gid)); | |
31af0abb | 396 | seq_printf(seq, ",mode=%03o", opts->mode); |
1f8f1e29 | 397 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); |
e9aba515 KK |
398 | if (opts->max < NR_UNIX98_PTY_MAX) |
399 | seq_printf(seq, ",max=%d", opts->max); | |
b87a267e MS |
400 | |
401 | return 0; | |
402 | } | |
403 | ||
ee9b6d61 | 404 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
405 | .statfs = simple_statfs, |
406 | .remount_fs = devpts_remount, | |
b87a267e | 407 | .show_options = devpts_show_options, |
1da177e4 LT |
408 | }; |
409 | ||
67245ff3 | 410 | static void *new_pts_fs_info(struct super_block *sb) |
e76b7c01 SB |
411 | { |
412 | struct pts_fs_info *fsi; | |
413 | ||
414 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
415 | if (!fsi) | |
416 | return NULL; | |
417 | ||
418 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 419 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 420 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
67245ff3 | 421 | fsi->sb = sb; |
e76b7c01 SB |
422 | |
423 | return fsi; | |
424 | } | |
425 | ||
1da177e4 LT |
426 | static int |
427 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
428 | { | |
1f8f1e29 | 429 | struct inode *inode; |
dee87d47 | 430 | int error; |
1da177e4 | 431 | |
cc50a07a | 432 | s->s_iflags &= ~SB_I_NODEV; |
1da177e4 LT |
433 | s->s_blocksize = 1024; |
434 | s->s_blocksize_bits = 10; | |
435 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
436 | s->s_op = &devpts_sops; | |
73052b0d | 437 | s->s_d_op = &simple_dentry_operations; |
1da177e4 LT |
438 | s->s_time_gran = 1; |
439 | ||
dee87d47 | 440 | error = -ENOMEM; |
67245ff3 | 441 | s->s_fs_info = new_pts_fs_info(s); |
e76b7c01 SB |
442 | if (!s->s_fs_info) |
443 | goto fail; | |
444 | ||
dee87d47 EB |
445 | error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); |
446 | if (error) | |
447 | goto fail; | |
448 | ||
449 | error = -ENOMEM; | |
1da177e4 LT |
450 | inode = new_inode(s); |
451 | if (!inode) | |
3850aba7 | 452 | goto fail; |
1da177e4 | 453 | inode->i_ino = 1; |
2ca7b9cd | 454 | inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode); |
1da177e4 LT |
455 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; |
456 | inode->i_op = &simple_dir_inode_operations; | |
457 | inode->i_fop = &simple_dir_operations; | |
bfe86848 | 458 | set_nlink(inode, 2); |
1da177e4 | 459 | |
48fde701 | 460 | s->s_root = d_make_root(inode); |
180d9044 EB |
461 | if (!s->s_root) { |
462 | pr_err("get root dentry failed\n"); | |
463 | goto fail; | |
464 | } | |
1f8f1e29 | 465 | |
180d9044 EB |
466 | error = mknod_ptmx(s); |
467 | if (error) | |
468 | goto fail_dput; | |
e76b7c01 | 469 | |
180d9044 EB |
470 | return 0; |
471 | fail_dput: | |
472 | dput(s->s_root); | |
473 | s->s_root = NULL; | |
1da177e4 | 474 | fail: |
dee87d47 | 475 | return error; |
1da177e4 LT |
476 | } |
477 | ||
2a1b2dc0 | 478 | /* |
fc14f2fe | 479 | * devpts_mount() |
1bd79035 | 480 | * |
eedf265a EB |
481 | * Mount a new (private) instance of devpts. PTYs created in this |
482 | * instance are independent of the PTYs in other devpts instances. | |
d4076ac5 | 483 | */ |
fc14f2fe AV |
484 | static struct dentry *devpts_mount(struct file_system_type *fs_type, |
485 | int flags, const char *dev_name, void *data) | |
1da177e4 | 486 | { |
c1b241f0 | 487 | return mount_nodev(fs_type, flags, data, devpts_fill_super); |
1da177e4 | 488 | } |
482984f0 | 489 | |
e76b7c01 SB |
490 | static void devpts_kill_sb(struct super_block *sb) |
491 | { | |
492 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
493 | ||
40b320e1 EB |
494 | if (fsi) |
495 | ida_destroy(&fsi->allocated_ptys); | |
e76b7c01 | 496 | kfree(fsi); |
1f8f1e29 | 497 | kill_litter_super(sb); |
e76b7c01 SB |
498 | } |
499 | ||
1da177e4 | 500 | static struct file_system_type devpts_fs_type = { |
1da177e4 | 501 | .name = "devpts", |
fc14f2fe | 502 | .mount = devpts_mount, |
e76b7c01 | 503 | .kill_sb = devpts_kill_sb, |
cc50a07a | 504 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
505 | }; |
506 | ||
507 | /* | |
508 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
509 | * to the System V naming convention | |
510 | */ | |
511 | ||
67245ff3 | 512 | int devpts_new_index(struct pts_fs_info *fsi) |
718a9163 | 513 | { |
0f0a0e54 | 514 | int index = -ENOSPC; |
e9aba515 | 515 | |
0f0a0e54 MW |
516 | if (atomic_inc_return(&pty_count) >= (pty_limit - |
517 | (fsi->mount_opts.reserve ? 0 : pty_reserve))) | |
518 | goto out; | |
718a9163 | 519 | |
0f0a0e54 MW |
520 | index = ida_alloc_max(&fsi->allocated_ptys, fsi->mount_opts.max - 1, |
521 | GFP_KERNEL); | |
522 | ||
523 | out: | |
524 | if (index < 0) | |
525 | atomic_dec(&pty_count); | |
718a9163 SB |
526 | return index; |
527 | } | |
528 | ||
67245ff3 | 529 | void devpts_kill_index(struct pts_fs_info *fsi, int idx) |
718a9163 | 530 | { |
0f0a0e54 MW |
531 | ida_free(&fsi->allocated_ptys, idx); |
532 | atomic_dec(&pty_count); | |
718a9163 SB |
533 | } |
534 | ||
1dcb8e6d JS |
535 | /** |
536 | * devpts_pty_new -- create a new inode in /dev/pts/ | |
ec05b126 | 537 | * @fsi: Filesystem info for this instance. |
1dcb8e6d JS |
538 | * @index: used as a name of the node |
539 | * @priv: what's given back by devpts_get_priv | |
540 | * | |
ec05b126 MWO |
541 | * The dentry for the created inode is returned. |
542 | * Remove it from /dev/pts/ with devpts_pty_kill(). | |
1dcb8e6d | 543 | */ |
8ead9dd5 | 544 | struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) |
1da177e4 | 545 | { |
1da177e4 | 546 | struct dentry *dentry; |
eedf265a | 547 | struct super_block *sb = fsi->sb; |
162b97cf | 548 | struct inode *inode; |
9ce71148 | 549 | struct dentry *root; |
9ce71148 | 550 | struct pts_mount_opts *opts; |
89a52e10 | 551 | char s[12]; |
1da177e4 | 552 | |
9ce71148 | 553 | root = sb->s_root; |
9ce71148 JT |
554 | opts = &fsi->mount_opts; |
555 | ||
162b97cf | 556 | inode = new_inode(sb); |
1da177e4 | 557 | if (!inode) |
162b97cf | 558 | return ERR_PTR(-ENOMEM); |
1da177e4 | 559 | |
f11afb61 | 560 | inode->i_ino = index + 3; |
d0eafc7d DH |
561 | inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); |
562 | inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); | |
2ca7b9cd | 563 | inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode); |
8ead9dd5 | 564 | init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); |
1da177e4 | 565 | |
f11afb61 | 566 | sprintf(s, "%d", index); |
89a52e10 | 567 | |
59e55e6c | 568 | dentry = d_alloc_name(root, s); |
b12d1259 | 569 | if (dentry) { |
8ead9dd5 | 570 | dentry->d_fsdata = priv; |
89a52e10 | 571 | d_add(dentry, inode); |
2b0143b5 | 572 | fsnotify_create(d_inode(root), dentry); |
aa597bc1 AV |
573 | } else { |
574 | iput(inode); | |
8ead9dd5 | 575 | dentry = ERR_PTR(-ENOMEM); |
3972b7f6 | 576 | } |
1da177e4 | 577 | |
8ead9dd5 | 578 | return dentry; |
1da177e4 LT |
579 | } |
580 | ||
1dcb8e6d JS |
581 | /** |
582 | * devpts_get_priv -- get private data for a slave | |
ec05b126 | 583 | * @dentry: dentry of the slave |
1dcb8e6d JS |
584 | * |
585 | * Returns whatever was passed as priv in devpts_pty_new for a given inode. | |
586 | */ | |
8ead9dd5 | 587 | void *devpts_get_priv(struct dentry *dentry) |
1da177e4 | 588 | { |
3e423945 LT |
589 | if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) |
590 | return NULL; | |
8ead9dd5 | 591 | return dentry->d_fsdata; |
1da177e4 LT |
592 | } |
593 | ||
1dcb8e6d JS |
594 | /** |
595 | * devpts_pty_kill -- remove inode form /dev/pts/ | |
ec05b126 | 596 | * @dentry: dentry of the slave to be removed |
1dcb8e6d JS |
597 | * |
598 | * This is an inverse operation of devpts_pty_new. | |
599 | */ | |
8ead9dd5 | 600 | void devpts_pty_kill(struct dentry *dentry) |
1da177e4 | 601 | { |
8ead9dd5 | 602 | WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); |
1da177e4 | 603 | |
8ead9dd5 LT |
604 | dentry->d_fsdata = NULL; |
605 | drop_nlink(dentry->d_inode); | |
46c46f8d | 606 | d_drop(dentry); |
29044dae | 607 | fsnotify_unlink(d_inode(dentry->d_parent), dentry); |
aa597bc1 | 608 | dput(dentry); /* d_alloc_name() in devpts_pty_new() */ |
1da177e4 LT |
609 | } |
610 | ||
611 | static int __init init_devpts_fs(void) | |
612 | { | |
613 | int err = register_filesystem(&devpts_fs_type); | |
614 | if (!err) { | |
3e27877a | 615 | register_sysctl("kernel/pty", pty_table); |
1da177e4 LT |
616 | } |
617 | return err; | |
618 | } | |
1da177e4 | 619 | module_init(init_devpts_fs) |