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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 | ||
04541a2f FF |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | ||
1da177e4 LT |
15 | #include <linux/module.h> |
16 | #include <linux/init.h> | |
17 | #include <linux/fs.h> | |
18 | #include <linux/sched.h> | |
19 | #include <linux/namei.h> | |
5a0e3ad6 | 20 | #include <linux/slab.h> |
1da177e4 LT |
21 | #include <linux/mount.h> |
22 | #include <linux/tty.h> | |
718a9163 | 23 | #include <linux/mutex.h> |
1fd7317d | 24 | #include <linux/magic.h> |
718a9163 | 25 | #include <linux/idr.h> |
1da177e4 | 26 | #include <linux/devpts_fs.h> |
7a673c6b | 27 | #include <linux/parser.h> |
3972b7f6 | 28 | #include <linux/fsnotify.h> |
b87a267e | 29 | #include <linux/seq_file.h> |
1da177e4 | 30 | |
b87a267e | 31 | #define DEVPTS_DEFAULT_MODE 0600 |
1f8f1e29 SB |
32 | /* |
33 | * ptmx is a new node in /dev/pts and will be unused in legacy (single- | |
34 | * instance) mode. To prevent surprises in user space, set permissions of | |
35 | * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful | |
36 | * permissions. | |
37 | */ | |
38 | #define DEVPTS_DEFAULT_PTMX_MODE 0000 | |
527b3e47 | 39 | #define PTMX_MINOR 2 |
b87a267e | 40 | |
a4834c10 KK |
41 | /* |
42 | * sysctl support for setting limits on the number of Unix98 ptys allocated. | |
43 | * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. | |
44 | */ | |
45 | static int pty_limit = NR_UNIX98_PTY_DEFAULT; | |
e9aba515 | 46 | static int pty_reserve = NR_UNIX98_PTY_RESERVE; |
a4834c10 | 47 | static int pty_limit_min; |
e9aba515 | 48 | static int pty_limit_max = INT_MAX; |
a4834c10 KK |
49 | static int pty_count; |
50 | ||
51 | static struct ctl_table pty_table[] = { | |
52 | { | |
53 | .procname = "max", | |
54 | .maxlen = sizeof(int), | |
55 | .mode = 0644, | |
56 | .data = &pty_limit, | |
57 | .proc_handler = proc_dointvec_minmax, | |
58 | .extra1 = &pty_limit_min, | |
59 | .extra2 = &pty_limit_max, | |
e9aba515 KK |
60 | }, { |
61 | .procname = "reserve", | |
62 | .maxlen = sizeof(int), | |
63 | .mode = 0644, | |
64 | .data = &pty_reserve, | |
65 | .proc_handler = proc_dointvec_minmax, | |
66 | .extra1 = &pty_limit_min, | |
67 | .extra2 = &pty_limit_max, | |
a4834c10 KK |
68 | }, { |
69 | .procname = "nr", | |
70 | .maxlen = sizeof(int), | |
71 | .mode = 0444, | |
72 | .data = &pty_count, | |
73 | .proc_handler = proc_dointvec, | |
74 | }, | |
75 | {} | |
76 | }; | |
77 | ||
78 | static struct ctl_table pty_kern_table[] = { | |
79 | { | |
80 | .procname = "pty", | |
81 | .mode = 0555, | |
82 | .child = pty_table, | |
83 | }, | |
84 | {} | |
85 | }; | |
86 | ||
87 | static struct ctl_table pty_root_table[] = { | |
88 | { | |
89 | .procname = "kernel", | |
90 | .mode = 0555, | |
91 | .child = pty_kern_table, | |
92 | }, | |
93 | {} | |
94 | }; | |
95 | ||
718a9163 SB |
96 | static DEFINE_MUTEX(allocated_ptys_lock); |
97 | ||
31af0abb | 98 | struct pts_mount_opts { |
1da177e4 LT |
99 | int setuid; |
100 | int setgid; | |
f04c6ce2 EB |
101 | kuid_t uid; |
102 | kgid_t gid; | |
1da177e4 | 103 | umode_t mode; |
1f8f1e29 | 104 | umode_t ptmxmode; |
eedf265a | 105 | int reserve; |
e9aba515 | 106 | int max; |
31af0abb | 107 | }; |
1da177e4 | 108 | |
7a673c6b | 109 | enum { |
e9aba515 | 110 | Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, |
7a673c6b DP |
111 | Opt_err |
112 | }; | |
113 | ||
a447c093 | 114 | static const match_table_t tokens = { |
7a673c6b DP |
115 | {Opt_uid, "uid=%u"}, |
116 | {Opt_gid, "gid=%u"}, | |
117 | {Opt_mode, "mode=%o"}, | |
1f8f1e29 | 118 | {Opt_ptmxmode, "ptmxmode=%o"}, |
2a1b2dc0 | 119 | {Opt_newinstance, "newinstance"}, |
e9aba515 | 120 | {Opt_max, "max=%d"}, |
7a673c6b DP |
121 | {Opt_err, NULL} |
122 | }; | |
123 | ||
e76b7c01 SB |
124 | struct pts_fs_info { |
125 | struct ida allocated_ptys; | |
31af0abb | 126 | struct pts_mount_opts mount_opts; |
67245ff3 | 127 | struct super_block *sb; |
1f8f1e29 | 128 | struct dentry *ptmx_dentry; |
e76b7c01 SB |
129 | }; |
130 | ||
131 | static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) | |
132 | { | |
133 | return sb->s_fs_info; | |
134 | } | |
135 | ||
311fc65c EB |
136 | static int devpts_ptmx_path(struct path *path) |
137 | { | |
138 | struct super_block *sb; | |
139 | int err; | |
140 | ||
311fc65c EB |
141 | /* Is a devpts filesystem at "pts" in the same directory? */ |
142 | err = path_pts(path); | |
143 | if (err) | |
144 | return err; | |
145 | ||
146 | /* Is the path the root of a devpts filesystem? */ | |
147 | sb = path->mnt->mnt_sb; | |
148 | if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
149 | (path->mnt->mnt_root != sb->s_root)) | |
150 | return -ENODEV; | |
151 | ||
152 | return 0; | |
153 | } | |
154 | ||
06186d2f CB |
155 | /* |
156 | * Try to find a suitable devpts filesystem. We support the following | |
157 | * scenarios: | |
158 | * - The ptmx device node is located in the same directory as the devpts | |
159 | * mount where the pts device nodes are located. | |
160 | * This is e.g. the case when calling open on the /dev/pts/ptmx device | |
161 | * node when the devpts filesystem is mounted at /dev/pts. | |
162 | * - The ptmx device node is located outside the devpts filesystem mount | |
163 | * where the pts device nodes are located. For example, the ptmx device | |
164 | * is a symlink, separate device node, or bind-mount. | |
165 | * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and | |
166 | * then calling open on /dev/ptmx. In this case a suitable pts | |
167 | * subdirectory can be found in the common parent directory /dev of the | |
168 | * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx | |
169 | * bind-mount. | |
170 | * If no suitable pts subdirectory can be found this function will fail. | |
171 | * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. | |
172 | */ | |
311fc65c EB |
173 | struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) |
174 | { | |
175 | struct path path; | |
be790c05 | 176 | int err = 0; |
311fc65c EB |
177 | |
178 | path = filp->f_path; | |
179 | path_get(&path); | |
180 | ||
8dfd4f3a CB |
181 | /* Walk upward while the start point is a bind mount of |
182 | * a single file. | |
183 | */ | |
184 | while (path.mnt->mnt_root == path.dentry) | |
185 | if (follow_up(&path) == 0) | |
186 | break; | |
187 | ||
188 | /* devpts_ptmx_path() finds a devpts fs or returns an error. */ | |
189 | if ((path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
190 | (DEVPTS_SB(path.mnt->mnt_sb) != fsi)) | |
be790c05 | 191 | err = devpts_ptmx_path(&path); |
311fc65c | 192 | dput(path.dentry); |
8dfd4f3a CB |
193 | if (!err) { |
194 | if (DEVPTS_SB(path.mnt->mnt_sb) == fsi) | |
195 | return path.mnt; | |
be790c05 | 196 | |
8dfd4f3a | 197 | err = -ENODEV; |
311fc65c | 198 | } |
be790c05 | 199 | |
8dfd4f3a CB |
200 | mntput(path.mnt); |
201 | return ERR_PTR(err); | |
311fc65c EB |
202 | } |
203 | ||
143c97cc | 204 | struct pts_fs_info *devpts_acquire(struct file *filp) |
59e55e6c | 205 | { |
eedf265a EB |
206 | struct pts_fs_info *result; |
207 | struct path path; | |
208 | struct super_block *sb; | |
eedf265a EB |
209 | |
210 | path = filp->f_path; | |
211 | path_get(&path); | |
212 | ||
be790c05 CB |
213 | /* Has the devpts filesystem already been found? */ |
214 | if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { | |
215 | int err; | |
216 | ||
217 | err = devpts_ptmx_path(&path); | |
218 | if (err) { | |
219 | result = ERR_PTR(err); | |
220 | goto out; | |
221 | } | |
eedf265a EB |
222 | } |
223 | ||
224 | /* | |
225 | * pty code needs to hold extra references in case of last /dev/tty close | |
226 | */ | |
311fc65c | 227 | sb = path.mnt->mnt_sb; |
eedf265a EB |
228 | atomic_inc(&sb->s_active); |
229 | result = DEVPTS_SB(sb); | |
230 | ||
231 | out: | |
232 | path_put(&path); | |
233 | return result; | |
234 | } | |
235 | ||
236 | void devpts_release(struct pts_fs_info *fsi) | |
237 | { | |
238 | deactivate_super(fsi->sb); | |
59e55e6c SB |
239 | } |
240 | ||
2a1b2dc0 SB |
241 | #define PARSE_MOUNT 0 |
242 | #define PARSE_REMOUNT 1 | |
243 | ||
1f71ebed SB |
244 | /* |
245 | * parse_mount_options(): | |
04541a2f | 246 | * Set @opts to mount options specified in @data. If an option is not |
eedf265a | 247 | * specified in @data, set it to its default value. |
1f71ebed SB |
248 | * |
249 | * Note: @data may be NULL (in which case all options are set to default). | |
250 | */ | |
2a1b2dc0 | 251 | static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) |
1da177e4 | 252 | { |
7a673c6b | 253 | char *p; |
f04c6ce2 EB |
254 | kuid_t uid; |
255 | kgid_t gid; | |
7a673c6b | 256 | |
31af0abb SB |
257 | opts->setuid = 0; |
258 | opts->setgid = 0; | |
f04c6ce2 EB |
259 | opts->uid = GLOBAL_ROOT_UID; |
260 | opts->gid = GLOBAL_ROOT_GID; | |
31af0abb | 261 | opts->mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 262 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e9aba515 | 263 | opts->max = NR_UNIX98_PTY_MAX; |
7a673c6b | 264 | |
eedf265a EB |
265 | /* Only allow instances mounted from the initial mount |
266 | * namespace to tap the reserve pool of ptys. | |
267 | */ | |
2a1b2dc0 | 268 | if (op == PARSE_MOUNT) |
eedf265a EB |
269 | opts->reserve = |
270 | (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); | |
2a1b2dc0 | 271 | |
7a673c6b DP |
272 | while ((p = strsep(&data, ",")) != NULL) { |
273 | substring_t args[MAX_OPT_ARGS]; | |
274 | int token; | |
275 | int option; | |
276 | ||
277 | if (!*p) | |
1da177e4 | 278 | continue; |
7a673c6b DP |
279 | |
280 | token = match_token(p, tokens, args); | |
281 | switch (token) { | |
282 | case Opt_uid: | |
283 | if (match_int(&args[0], &option)) | |
284 | return -EINVAL; | |
f04c6ce2 EB |
285 | uid = make_kuid(current_user_ns(), option); |
286 | if (!uid_valid(uid)) | |
287 | return -EINVAL; | |
288 | opts->uid = uid; | |
31af0abb | 289 | opts->setuid = 1; |
7a673c6b DP |
290 | break; |
291 | case Opt_gid: | |
292 | if (match_int(&args[0], &option)) | |
293 | return -EINVAL; | |
f04c6ce2 EB |
294 | gid = make_kgid(current_user_ns(), option); |
295 | if (!gid_valid(gid)) | |
296 | return -EINVAL; | |
297 | opts->gid = gid; | |
31af0abb | 298 | opts->setgid = 1; |
7a673c6b DP |
299 | break; |
300 | case Opt_mode: | |
301 | if (match_octal(&args[0], &option)) | |
302 | return -EINVAL; | |
31af0abb | 303 | opts->mode = option & S_IALLUGO; |
7a673c6b | 304 | break; |
1f8f1e29 SB |
305 | case Opt_ptmxmode: |
306 | if (match_octal(&args[0], &option)) | |
307 | return -EINVAL; | |
308 | opts->ptmxmode = option & S_IALLUGO; | |
309 | break; | |
2a1b2dc0 | 310 | case Opt_newinstance: |
2a1b2dc0 | 311 | break; |
e9aba515 KK |
312 | case Opt_max: |
313 | if (match_int(&args[0], &option) || | |
314 | option < 0 || option > NR_UNIX98_PTY_MAX) | |
315 | return -EINVAL; | |
316 | opts->max = option; | |
317 | break; | |
7a673c6b | 318 | default: |
04541a2f | 319 | pr_err("called with bogus options\n"); |
1da177e4 LT |
320 | return -EINVAL; |
321 | } | |
322 | } | |
1da177e4 LT |
323 | |
324 | return 0; | |
325 | } | |
326 | ||
1f8f1e29 SB |
327 | static int mknod_ptmx(struct super_block *sb) |
328 | { | |
329 | int mode; | |
330 | int rc = -ENOMEM; | |
331 | struct dentry *dentry; | |
332 | struct inode *inode; | |
333 | struct dentry *root = sb->s_root; | |
334 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
335 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
e98d4137 EB |
336 | kuid_t ptmx_uid = current_fsuid(); |
337 | kgid_t ptmx_gid = current_fsgid(); | |
1f8f1e29 | 338 | |
5955102c | 339 | inode_lock(d_inode(root)); |
1f8f1e29 SB |
340 | |
341 | /* If we have already created ptmx node, return */ | |
342 | if (fsi->ptmx_dentry) { | |
343 | rc = 0; | |
344 | goto out; | |
345 | } | |
346 | ||
347 | dentry = d_alloc_name(root, "ptmx"); | |
348 | if (!dentry) { | |
04541a2f | 349 | pr_err("Unable to alloc dentry for ptmx node\n"); |
1f8f1e29 SB |
350 | goto out; |
351 | } | |
352 | ||
353 | /* | |
354 | * Create a new 'ptmx' node in this mount of devpts. | |
355 | */ | |
356 | inode = new_inode(sb); | |
357 | if (!inode) { | |
04541a2f | 358 | pr_err("Unable to alloc inode for ptmx node\n"); |
1f8f1e29 SB |
359 | dput(dentry); |
360 | goto out; | |
361 | } | |
362 | ||
363 | inode->i_ino = 2; | |
078cd827 | 364 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1f8f1e29 SB |
365 | |
366 | mode = S_IFCHR|opts->ptmxmode; | |
367 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
e98d4137 EB |
368 | inode->i_uid = ptmx_uid; |
369 | inode->i_gid = ptmx_gid; | |
1f8f1e29 SB |
370 | |
371 | d_add(dentry, inode); | |
372 | ||
373 | fsi->ptmx_dentry = dentry; | |
374 | rc = 0; | |
1f8f1e29 | 375 | out: |
5955102c | 376 | inode_unlock(d_inode(root)); |
1f8f1e29 SB |
377 | return rc; |
378 | } | |
379 | ||
380 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
381 | { | |
382 | struct inode *inode; | |
383 | if (fsi->ptmx_dentry) { | |
2b0143b5 | 384 | inode = d_inode(fsi->ptmx_dentry); |
1f8f1e29 SB |
385 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; |
386 | } | |
387 | } | |
1f8f1e29 | 388 | |
53af8ee4 SB |
389 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
390 | { | |
1f8f1e29 | 391 | int err; |
53af8ee4 SB |
392 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
393 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
394 | ||
2a1b2dc0 | 395 | err = parse_mount_options(data, PARSE_REMOUNT, opts); |
1f8f1e29 SB |
396 | |
397 | /* | |
398 | * parse_mount_options() restores options to default values | |
399 | * before parsing and may have changed ptmxmode. So, update the | |
400 | * mode in the inode too. Bogus options don't fail the remount, | |
401 | * so do this even on error return. | |
402 | */ | |
403 | update_ptmx_mode(fsi); | |
404 | ||
405 | return err; | |
53af8ee4 SB |
406 | } |
407 | ||
34c80b1d | 408 | static int devpts_show_options(struct seq_file *seq, struct dentry *root) |
b87a267e | 409 | { |
34c80b1d | 410 | struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); |
31af0abb SB |
411 | struct pts_mount_opts *opts = &fsi->mount_opts; |
412 | ||
413 | if (opts->setuid) | |
04541a2f FF |
414 | seq_printf(seq, ",uid=%u", |
415 | from_kuid_munged(&init_user_ns, opts->uid)); | |
31af0abb | 416 | if (opts->setgid) |
04541a2f FF |
417 | seq_printf(seq, ",gid=%u", |
418 | from_kgid_munged(&init_user_ns, opts->gid)); | |
31af0abb | 419 | seq_printf(seq, ",mode=%03o", opts->mode); |
1f8f1e29 | 420 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); |
e9aba515 KK |
421 | if (opts->max < NR_UNIX98_PTY_MAX) |
422 | seq_printf(seq, ",max=%d", opts->max); | |
b87a267e MS |
423 | |
424 | return 0; | |
425 | } | |
426 | ||
ee9b6d61 | 427 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
428 | .statfs = simple_statfs, |
429 | .remount_fs = devpts_remount, | |
b87a267e | 430 | .show_options = devpts_show_options, |
1da177e4 LT |
431 | }; |
432 | ||
67245ff3 | 433 | static void *new_pts_fs_info(struct super_block *sb) |
e76b7c01 SB |
434 | { |
435 | struct pts_fs_info *fsi; | |
436 | ||
437 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
438 | if (!fsi) | |
439 | return NULL; | |
440 | ||
441 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 442 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 443 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
67245ff3 | 444 | fsi->sb = sb; |
e76b7c01 SB |
445 | |
446 | return fsi; | |
447 | } | |
448 | ||
1da177e4 LT |
449 | static int |
450 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
451 | { | |
1f8f1e29 | 452 | struct inode *inode; |
dee87d47 | 453 | int error; |
1da177e4 | 454 | |
cc50a07a | 455 | s->s_iflags &= ~SB_I_NODEV; |
1da177e4 LT |
456 | s->s_blocksize = 1024; |
457 | s->s_blocksize_bits = 10; | |
458 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
459 | s->s_op = &devpts_sops; | |
b5fd8973 | 460 | s->s_d_op = &simple_dentry_operations; |
1da177e4 LT |
461 | s->s_time_gran = 1; |
462 | ||
dee87d47 | 463 | error = -ENOMEM; |
67245ff3 | 464 | s->s_fs_info = new_pts_fs_info(s); |
e76b7c01 SB |
465 | if (!s->s_fs_info) |
466 | goto fail; | |
467 | ||
dee87d47 EB |
468 | error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); |
469 | if (error) | |
470 | goto fail; | |
471 | ||
472 | error = -ENOMEM; | |
1da177e4 LT |
473 | inode = new_inode(s); |
474 | if (!inode) | |
3850aba7 | 475 | goto fail; |
1da177e4 | 476 | inode->i_ino = 1; |
078cd827 | 477 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1da177e4 LT |
478 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; |
479 | inode->i_op = &simple_dir_inode_operations; | |
480 | inode->i_fop = &simple_dir_operations; | |
bfe86848 | 481 | set_nlink(inode, 2); |
1da177e4 | 482 | |
48fde701 | 483 | s->s_root = d_make_root(inode); |
180d9044 EB |
484 | if (!s->s_root) { |
485 | pr_err("get root dentry failed\n"); | |
486 | goto fail; | |
487 | } | |
1f8f1e29 | 488 | |
180d9044 EB |
489 | error = mknod_ptmx(s); |
490 | if (error) | |
491 | goto fail_dput; | |
e76b7c01 | 492 | |
180d9044 EB |
493 | return 0; |
494 | fail_dput: | |
495 | dput(s->s_root); | |
496 | s->s_root = NULL; | |
1da177e4 | 497 | fail: |
dee87d47 | 498 | return error; |
1da177e4 LT |
499 | } |
500 | ||
2a1b2dc0 | 501 | /* |
fc14f2fe | 502 | * devpts_mount() |
1bd79035 | 503 | * |
eedf265a EB |
504 | * Mount a new (private) instance of devpts. PTYs created in this |
505 | * instance are independent of the PTYs in other devpts instances. | |
d4076ac5 | 506 | */ |
fc14f2fe AV |
507 | static struct dentry *devpts_mount(struct file_system_type *fs_type, |
508 | int flags, const char *dev_name, void *data) | |
1da177e4 | 509 | { |
c1b241f0 | 510 | return mount_nodev(fs_type, flags, data, devpts_fill_super); |
1da177e4 | 511 | } |
482984f0 | 512 | |
e76b7c01 SB |
513 | static void devpts_kill_sb(struct super_block *sb) |
514 | { | |
515 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
516 | ||
40b320e1 EB |
517 | if (fsi) |
518 | ida_destroy(&fsi->allocated_ptys); | |
e76b7c01 | 519 | kfree(fsi); |
1f8f1e29 | 520 | kill_litter_super(sb); |
e76b7c01 SB |
521 | } |
522 | ||
1da177e4 | 523 | static struct file_system_type devpts_fs_type = { |
1da177e4 | 524 | .name = "devpts", |
fc14f2fe | 525 | .mount = devpts_mount, |
e76b7c01 | 526 | .kill_sb = devpts_kill_sb, |
cc50a07a | 527 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
528 | }; |
529 | ||
530 | /* | |
531 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
532 | * to the System V naming convention | |
533 | */ | |
534 | ||
67245ff3 | 535 | int devpts_new_index(struct pts_fs_info *fsi) |
718a9163 SB |
536 | { |
537 | int index; | |
7ee7c12b | 538 | int ida_ret; |
718a9163 SB |
539 | |
540 | retry: | |
835aa440 | 541 | if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) |
718a9163 | 542 | return -ENOMEM; |
718a9163 SB |
543 | |
544 | mutex_lock(&allocated_ptys_lock); | |
eedf265a EB |
545 | if (pty_count >= (pty_limit - |
546 | (fsi->mount_opts.reserve ? 0 : pty_reserve))) { | |
e9aba515 KK |
547 | mutex_unlock(&allocated_ptys_lock); |
548 | return -ENOSPC; | |
549 | } | |
550 | ||
e76b7c01 | 551 | ida_ret = ida_get_new(&fsi->allocated_ptys, &index); |
7ee7c12b | 552 | if (ida_ret < 0) { |
718a9163 | 553 | mutex_unlock(&allocated_ptys_lock); |
7ee7c12b | 554 | if (ida_ret == -EAGAIN) |
718a9163 SB |
555 | goto retry; |
556 | return -EIO; | |
557 | } | |
558 | ||
e9aba515 | 559 | if (index >= fsi->mount_opts.max) { |
e76b7c01 | 560 | ida_remove(&fsi->allocated_ptys, index); |
718a9163 | 561 | mutex_unlock(&allocated_ptys_lock); |
e9aba515 | 562 | return -ENOSPC; |
718a9163 | 563 | } |
a4834c10 | 564 | pty_count++; |
718a9163 SB |
565 | mutex_unlock(&allocated_ptys_lock); |
566 | return index; | |
567 | } | |
568 | ||
67245ff3 | 569 | void devpts_kill_index(struct pts_fs_info *fsi, int idx) |
718a9163 SB |
570 | { |
571 | mutex_lock(&allocated_ptys_lock); | |
e76b7c01 | 572 | ida_remove(&fsi->allocated_ptys, idx); |
a4834c10 | 573 | pty_count--; |
718a9163 SB |
574 | mutex_unlock(&allocated_ptys_lock); |
575 | } | |
576 | ||
1dcb8e6d JS |
577 | /** |
578 | * devpts_pty_new -- create a new inode in /dev/pts/ | |
579 | * @ptmx_inode: inode of the master | |
580 | * @device: major+minor of the node to be created | |
581 | * @index: used as a name of the node | |
582 | * @priv: what's given back by devpts_get_priv | |
583 | * | |
584 | * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. | |
585 | */ | |
8ead9dd5 | 586 | struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) |
1da177e4 | 587 | { |
1da177e4 | 588 | struct dentry *dentry; |
eedf265a | 589 | struct super_block *sb = fsi->sb; |
162b97cf | 590 | struct inode *inode; |
9ce71148 | 591 | struct dentry *root; |
9ce71148 | 592 | struct pts_mount_opts *opts; |
89a52e10 | 593 | char s[12]; |
1da177e4 | 594 | |
9ce71148 | 595 | root = sb->s_root; |
9ce71148 JT |
596 | opts = &fsi->mount_opts; |
597 | ||
162b97cf | 598 | inode = new_inode(sb); |
1da177e4 | 599 | if (!inode) |
162b97cf | 600 | return ERR_PTR(-ENOMEM); |
1da177e4 | 601 | |
f11afb61 | 602 | inode->i_ino = index + 3; |
d0eafc7d DH |
603 | inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); |
604 | inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); | |
078cd827 | 605 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
8ead9dd5 | 606 | init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); |
1da177e4 | 607 | |
f11afb61 | 608 | sprintf(s, "%d", index); |
89a52e10 | 609 | |
59e55e6c | 610 | dentry = d_alloc_name(root, s); |
b12d1259 | 611 | if (dentry) { |
8ead9dd5 | 612 | dentry->d_fsdata = priv; |
89a52e10 | 613 | d_add(dentry, inode); |
2b0143b5 | 614 | fsnotify_create(d_inode(root), dentry); |
aa597bc1 AV |
615 | } else { |
616 | iput(inode); | |
8ead9dd5 | 617 | dentry = ERR_PTR(-ENOMEM); |
3972b7f6 | 618 | } |
1da177e4 | 619 | |
8ead9dd5 | 620 | return dentry; |
1da177e4 LT |
621 | } |
622 | ||
1dcb8e6d JS |
623 | /** |
624 | * devpts_get_priv -- get private data for a slave | |
625 | * @pts_inode: inode of the slave | |
626 | * | |
627 | * Returns whatever was passed as priv in devpts_pty_new for a given inode. | |
628 | */ | |
8ead9dd5 | 629 | void *devpts_get_priv(struct dentry *dentry) |
1da177e4 | 630 | { |
3e423945 LT |
631 | if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) |
632 | return NULL; | |
8ead9dd5 | 633 | return dentry->d_fsdata; |
1da177e4 LT |
634 | } |
635 | ||
1dcb8e6d JS |
636 | /** |
637 | * devpts_pty_kill -- remove inode form /dev/pts/ | |
638 | * @inode: inode of the slave to be removed | |
639 | * | |
640 | * This is an inverse operation of devpts_pty_new. | |
641 | */ | |
8ead9dd5 | 642 | void devpts_pty_kill(struct dentry *dentry) |
1da177e4 | 643 | { |
8ead9dd5 | 644 | WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); |
1da177e4 | 645 | |
8ead9dd5 LT |
646 | dentry->d_fsdata = NULL; |
647 | drop_nlink(dentry->d_inode); | |
aa597bc1 AV |
648 | d_delete(dentry); |
649 | dput(dentry); /* d_alloc_name() in devpts_pty_new() */ | |
1da177e4 LT |
650 | } |
651 | ||
652 | static int __init init_devpts_fs(void) | |
653 | { | |
654 | int err = register_filesystem(&devpts_fs_type); | |
655 | if (!err) { | |
eedf265a | 656 | register_sysctl_table(pty_root_table); |
1da177e4 LT |
657 | } |
658 | return err; | |
659 | } | |
1da177e4 | 660 | module_init(init_devpts_fs) |