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 | ||
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 | ||
155 | struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) | |
156 | { | |
157 | struct path path; | |
7d71109d | 158 | int err = 0; |
311fc65c EB |
159 | |
160 | path = filp->f_path; | |
161 | path_get(&path); | |
162 | ||
a319b01d CB |
163 | /* Walk upward while the start point is a bind mount of |
164 | * a single file. | |
165 | */ | |
166 | while (path.mnt->mnt_root == path.dentry) | |
167 | if (follow_up(&path) == 0) | |
168 | break; | |
169 | ||
170 | /* devpts_ptmx_path() finds a devpts fs or returns an error. */ | |
171 | if ((path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
172 | (DEVPTS_SB(path.mnt->mnt_sb) != fsi)) | |
7d71109d | 173 | err = devpts_ptmx_path(&path); |
311fc65c | 174 | dput(path.dentry); |
a319b01d CB |
175 | if (!err) { |
176 | if (DEVPTS_SB(path.mnt->mnt_sb) == fsi) | |
177 | return path.mnt; | |
7d71109d | 178 | |
a319b01d | 179 | err = -ENODEV; |
311fc65c | 180 | } |
7d71109d | 181 | |
a319b01d CB |
182 | mntput(path.mnt); |
183 | return ERR_PTR(err); | |
311fc65c EB |
184 | } |
185 | ||
143c97cc | 186 | struct pts_fs_info *devpts_acquire(struct file *filp) |
59e55e6c | 187 | { |
eedf265a EB |
188 | struct pts_fs_info *result; |
189 | struct path path; | |
190 | struct super_block *sb; | |
eedf265a EB |
191 | |
192 | path = filp->f_path; | |
193 | path_get(&path); | |
194 | ||
7d71109d CB |
195 | /* Has the devpts filesystem already been found? */ |
196 | if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { | |
197 | int err; | |
198 | ||
199 | err = devpts_ptmx_path(&path); | |
200 | if (err) { | |
201 | result = ERR_PTR(err); | |
202 | goto out; | |
203 | } | |
eedf265a EB |
204 | } |
205 | ||
206 | /* | |
207 | * pty code needs to hold extra references in case of last /dev/tty close | |
208 | */ | |
311fc65c | 209 | sb = path.mnt->mnt_sb; |
eedf265a EB |
210 | atomic_inc(&sb->s_active); |
211 | result = DEVPTS_SB(sb); | |
212 | ||
213 | out: | |
214 | path_put(&path); | |
215 | return result; | |
216 | } | |
217 | ||
218 | void devpts_release(struct pts_fs_info *fsi) | |
219 | { | |
220 | deactivate_super(fsi->sb); | |
59e55e6c SB |
221 | } |
222 | ||
2a1b2dc0 SB |
223 | #define PARSE_MOUNT 0 |
224 | #define PARSE_REMOUNT 1 | |
225 | ||
1f71ebed SB |
226 | /* |
227 | * parse_mount_options(): | |
04541a2f | 228 | * Set @opts to mount options specified in @data. If an option is not |
eedf265a | 229 | * specified in @data, set it to its default value. |
1f71ebed SB |
230 | * |
231 | * Note: @data may be NULL (in which case all options are set to default). | |
232 | */ | |
2a1b2dc0 | 233 | static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) |
1da177e4 | 234 | { |
7a673c6b | 235 | char *p; |
f04c6ce2 EB |
236 | kuid_t uid; |
237 | kgid_t gid; | |
7a673c6b | 238 | |
31af0abb SB |
239 | opts->setuid = 0; |
240 | opts->setgid = 0; | |
f04c6ce2 EB |
241 | opts->uid = GLOBAL_ROOT_UID; |
242 | opts->gid = GLOBAL_ROOT_GID; | |
31af0abb | 243 | opts->mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 244 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e9aba515 | 245 | opts->max = NR_UNIX98_PTY_MAX; |
7a673c6b | 246 | |
eedf265a EB |
247 | /* Only allow instances mounted from the initial mount |
248 | * namespace to tap the reserve pool of ptys. | |
249 | */ | |
2a1b2dc0 | 250 | if (op == PARSE_MOUNT) |
eedf265a EB |
251 | opts->reserve = |
252 | (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); | |
2a1b2dc0 | 253 | |
7a673c6b DP |
254 | while ((p = strsep(&data, ",")) != NULL) { |
255 | substring_t args[MAX_OPT_ARGS]; | |
256 | int token; | |
257 | int option; | |
258 | ||
259 | if (!*p) | |
1da177e4 | 260 | continue; |
7a673c6b DP |
261 | |
262 | token = match_token(p, tokens, args); | |
263 | switch (token) { | |
264 | case Opt_uid: | |
265 | if (match_int(&args[0], &option)) | |
266 | return -EINVAL; | |
f04c6ce2 EB |
267 | uid = make_kuid(current_user_ns(), option); |
268 | if (!uid_valid(uid)) | |
269 | return -EINVAL; | |
270 | opts->uid = uid; | |
31af0abb | 271 | opts->setuid = 1; |
7a673c6b DP |
272 | break; |
273 | case Opt_gid: | |
274 | if (match_int(&args[0], &option)) | |
275 | return -EINVAL; | |
f04c6ce2 EB |
276 | gid = make_kgid(current_user_ns(), option); |
277 | if (!gid_valid(gid)) | |
278 | return -EINVAL; | |
279 | opts->gid = gid; | |
31af0abb | 280 | opts->setgid = 1; |
7a673c6b DP |
281 | break; |
282 | case Opt_mode: | |
283 | if (match_octal(&args[0], &option)) | |
284 | return -EINVAL; | |
31af0abb | 285 | opts->mode = option & S_IALLUGO; |
7a673c6b | 286 | break; |
1f8f1e29 SB |
287 | case Opt_ptmxmode: |
288 | if (match_octal(&args[0], &option)) | |
289 | return -EINVAL; | |
290 | opts->ptmxmode = option & S_IALLUGO; | |
291 | break; | |
2a1b2dc0 | 292 | case Opt_newinstance: |
2a1b2dc0 | 293 | break; |
e9aba515 KK |
294 | case Opt_max: |
295 | if (match_int(&args[0], &option) || | |
296 | option < 0 || option > NR_UNIX98_PTY_MAX) | |
297 | return -EINVAL; | |
298 | opts->max = option; | |
299 | break; | |
7a673c6b | 300 | default: |
04541a2f | 301 | pr_err("called with bogus options\n"); |
1da177e4 LT |
302 | return -EINVAL; |
303 | } | |
304 | } | |
1da177e4 LT |
305 | |
306 | return 0; | |
307 | } | |
308 | ||
1f8f1e29 SB |
309 | static int mknod_ptmx(struct super_block *sb) |
310 | { | |
311 | int mode; | |
312 | int rc = -ENOMEM; | |
313 | struct dentry *dentry; | |
314 | struct inode *inode; | |
315 | struct dentry *root = sb->s_root; | |
316 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
317 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
e98d4137 EB |
318 | kuid_t ptmx_uid = current_fsuid(); |
319 | kgid_t ptmx_gid = current_fsgid(); | |
1f8f1e29 | 320 | |
5955102c | 321 | inode_lock(d_inode(root)); |
1f8f1e29 SB |
322 | |
323 | /* If we have already created ptmx node, return */ | |
324 | if (fsi->ptmx_dentry) { | |
325 | rc = 0; | |
326 | goto out; | |
327 | } | |
328 | ||
329 | dentry = d_alloc_name(root, "ptmx"); | |
330 | if (!dentry) { | |
04541a2f | 331 | pr_err("Unable to alloc dentry for ptmx node\n"); |
1f8f1e29 SB |
332 | goto out; |
333 | } | |
334 | ||
335 | /* | |
336 | * Create a new 'ptmx' node in this mount of devpts. | |
337 | */ | |
338 | inode = new_inode(sb); | |
339 | if (!inode) { | |
04541a2f | 340 | pr_err("Unable to alloc inode for ptmx node\n"); |
1f8f1e29 SB |
341 | dput(dentry); |
342 | goto out; | |
343 | } | |
344 | ||
345 | inode->i_ino = 2; | |
078cd827 | 346 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1f8f1e29 SB |
347 | |
348 | mode = S_IFCHR|opts->ptmxmode; | |
349 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
e98d4137 EB |
350 | inode->i_uid = ptmx_uid; |
351 | inode->i_gid = ptmx_gid; | |
1f8f1e29 SB |
352 | |
353 | d_add(dentry, inode); | |
354 | ||
355 | fsi->ptmx_dentry = dentry; | |
356 | rc = 0; | |
1f8f1e29 | 357 | out: |
5955102c | 358 | inode_unlock(d_inode(root)); |
1f8f1e29 SB |
359 | return rc; |
360 | } | |
361 | ||
362 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
363 | { | |
364 | struct inode *inode; | |
365 | if (fsi->ptmx_dentry) { | |
2b0143b5 | 366 | inode = d_inode(fsi->ptmx_dentry); |
1f8f1e29 SB |
367 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; |
368 | } | |
369 | } | |
1f8f1e29 | 370 | |
53af8ee4 SB |
371 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
372 | { | |
1f8f1e29 | 373 | int err; |
53af8ee4 SB |
374 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
375 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
376 | ||
2a1b2dc0 | 377 | err = parse_mount_options(data, PARSE_REMOUNT, opts); |
1f8f1e29 SB |
378 | |
379 | /* | |
380 | * parse_mount_options() restores options to default values | |
381 | * before parsing and may have changed ptmxmode. So, update the | |
382 | * mode in the inode too. Bogus options don't fail the remount, | |
383 | * so do this even on error return. | |
384 | */ | |
385 | update_ptmx_mode(fsi); | |
386 | ||
387 | return err; | |
53af8ee4 SB |
388 | } |
389 | ||
34c80b1d | 390 | static int devpts_show_options(struct seq_file *seq, struct dentry *root) |
b87a267e | 391 | { |
34c80b1d | 392 | struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); |
31af0abb SB |
393 | struct pts_mount_opts *opts = &fsi->mount_opts; |
394 | ||
395 | if (opts->setuid) | |
04541a2f FF |
396 | seq_printf(seq, ",uid=%u", |
397 | from_kuid_munged(&init_user_ns, opts->uid)); | |
31af0abb | 398 | if (opts->setgid) |
04541a2f FF |
399 | seq_printf(seq, ",gid=%u", |
400 | from_kgid_munged(&init_user_ns, opts->gid)); | |
31af0abb | 401 | seq_printf(seq, ",mode=%03o", opts->mode); |
1f8f1e29 | 402 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); |
e9aba515 KK |
403 | if (opts->max < NR_UNIX98_PTY_MAX) |
404 | seq_printf(seq, ",max=%d", opts->max); | |
b87a267e MS |
405 | |
406 | return 0; | |
407 | } | |
408 | ||
ee9b6d61 | 409 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
410 | .statfs = simple_statfs, |
411 | .remount_fs = devpts_remount, | |
b87a267e | 412 | .show_options = devpts_show_options, |
1da177e4 LT |
413 | }; |
414 | ||
67245ff3 | 415 | static void *new_pts_fs_info(struct super_block *sb) |
e76b7c01 SB |
416 | { |
417 | struct pts_fs_info *fsi; | |
418 | ||
419 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
420 | if (!fsi) | |
421 | return NULL; | |
422 | ||
423 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 424 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 425 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
67245ff3 | 426 | fsi->sb = sb; |
e76b7c01 SB |
427 | |
428 | return fsi; | |
429 | } | |
430 | ||
1da177e4 LT |
431 | static int |
432 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
433 | { | |
1f8f1e29 | 434 | struct inode *inode; |
dee87d47 | 435 | int error; |
1da177e4 | 436 | |
cc50a07a | 437 | s->s_iflags &= ~SB_I_NODEV; |
1da177e4 LT |
438 | s->s_blocksize = 1024; |
439 | s->s_blocksize_bits = 10; | |
440 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
441 | s->s_op = &devpts_sops; | |
1da177e4 LT |
442 | s->s_time_gran = 1; |
443 | ||
dee87d47 | 444 | error = -ENOMEM; |
67245ff3 | 445 | s->s_fs_info = new_pts_fs_info(s); |
e76b7c01 SB |
446 | if (!s->s_fs_info) |
447 | goto fail; | |
448 | ||
dee87d47 EB |
449 | error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); |
450 | if (error) | |
451 | goto fail; | |
452 | ||
453 | error = -ENOMEM; | |
1da177e4 LT |
454 | inode = new_inode(s); |
455 | if (!inode) | |
3850aba7 | 456 | goto fail; |
1da177e4 | 457 | inode->i_ino = 1; |
078cd827 | 458 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1da177e4 LT |
459 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; |
460 | inode->i_op = &simple_dir_inode_operations; | |
461 | inode->i_fop = &simple_dir_operations; | |
bfe86848 | 462 | set_nlink(inode, 2); |
1da177e4 | 463 | |
48fde701 | 464 | s->s_root = d_make_root(inode); |
180d9044 EB |
465 | if (!s->s_root) { |
466 | pr_err("get root dentry failed\n"); | |
467 | goto fail; | |
468 | } | |
1f8f1e29 | 469 | |
180d9044 EB |
470 | error = mknod_ptmx(s); |
471 | if (error) | |
472 | goto fail_dput; | |
e76b7c01 | 473 | |
180d9044 EB |
474 | return 0; |
475 | fail_dput: | |
476 | dput(s->s_root); | |
477 | s->s_root = NULL; | |
1da177e4 | 478 | fail: |
dee87d47 | 479 | return error; |
1da177e4 LT |
480 | } |
481 | ||
2a1b2dc0 | 482 | /* |
fc14f2fe | 483 | * devpts_mount() |
1bd79035 | 484 | * |
eedf265a EB |
485 | * Mount a new (private) instance of devpts. PTYs created in this |
486 | * instance are independent of the PTYs in other devpts instances. | |
d4076ac5 | 487 | */ |
fc14f2fe AV |
488 | static struct dentry *devpts_mount(struct file_system_type *fs_type, |
489 | int flags, const char *dev_name, void *data) | |
1da177e4 | 490 | { |
c1b241f0 | 491 | return mount_nodev(fs_type, flags, data, devpts_fill_super); |
1da177e4 | 492 | } |
482984f0 | 493 | |
e76b7c01 SB |
494 | static void devpts_kill_sb(struct super_block *sb) |
495 | { | |
496 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
497 | ||
40b320e1 EB |
498 | if (fsi) |
499 | ida_destroy(&fsi->allocated_ptys); | |
e76b7c01 | 500 | kfree(fsi); |
1f8f1e29 | 501 | kill_litter_super(sb); |
e76b7c01 SB |
502 | } |
503 | ||
1da177e4 | 504 | static struct file_system_type devpts_fs_type = { |
1da177e4 | 505 | .name = "devpts", |
fc14f2fe | 506 | .mount = devpts_mount, |
e76b7c01 | 507 | .kill_sb = devpts_kill_sb, |
cc50a07a | 508 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
509 | }; |
510 | ||
511 | /* | |
512 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
513 | * to the System V naming convention | |
514 | */ | |
515 | ||
67245ff3 | 516 | int devpts_new_index(struct pts_fs_info *fsi) |
718a9163 SB |
517 | { |
518 | int index; | |
7ee7c12b | 519 | int ida_ret; |
718a9163 SB |
520 | |
521 | retry: | |
835aa440 | 522 | if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) |
718a9163 | 523 | return -ENOMEM; |
718a9163 SB |
524 | |
525 | mutex_lock(&allocated_ptys_lock); | |
eedf265a EB |
526 | if (pty_count >= (pty_limit - |
527 | (fsi->mount_opts.reserve ? 0 : pty_reserve))) { | |
e9aba515 KK |
528 | mutex_unlock(&allocated_ptys_lock); |
529 | return -ENOSPC; | |
530 | } | |
531 | ||
e76b7c01 | 532 | ida_ret = ida_get_new(&fsi->allocated_ptys, &index); |
7ee7c12b | 533 | if (ida_ret < 0) { |
718a9163 | 534 | mutex_unlock(&allocated_ptys_lock); |
7ee7c12b | 535 | if (ida_ret == -EAGAIN) |
718a9163 SB |
536 | goto retry; |
537 | return -EIO; | |
538 | } | |
539 | ||
e9aba515 | 540 | if (index >= fsi->mount_opts.max) { |
e76b7c01 | 541 | ida_remove(&fsi->allocated_ptys, index); |
718a9163 | 542 | mutex_unlock(&allocated_ptys_lock); |
e9aba515 | 543 | return -ENOSPC; |
718a9163 | 544 | } |
a4834c10 | 545 | pty_count++; |
718a9163 SB |
546 | mutex_unlock(&allocated_ptys_lock); |
547 | return index; | |
548 | } | |
549 | ||
67245ff3 | 550 | void devpts_kill_index(struct pts_fs_info *fsi, int idx) |
718a9163 SB |
551 | { |
552 | mutex_lock(&allocated_ptys_lock); | |
e76b7c01 | 553 | ida_remove(&fsi->allocated_ptys, idx); |
a4834c10 | 554 | pty_count--; |
718a9163 SB |
555 | mutex_unlock(&allocated_ptys_lock); |
556 | } | |
557 | ||
1dcb8e6d JS |
558 | /** |
559 | * devpts_pty_new -- create a new inode in /dev/pts/ | |
560 | * @ptmx_inode: inode of the master | |
561 | * @device: major+minor of the node to be created | |
562 | * @index: used as a name of the node | |
563 | * @priv: what's given back by devpts_get_priv | |
564 | * | |
565 | * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. | |
566 | */ | |
8ead9dd5 | 567 | struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) |
1da177e4 | 568 | { |
1da177e4 | 569 | struct dentry *dentry; |
eedf265a | 570 | struct super_block *sb = fsi->sb; |
162b97cf | 571 | struct inode *inode; |
9ce71148 | 572 | struct dentry *root; |
9ce71148 | 573 | struct pts_mount_opts *opts; |
89a52e10 | 574 | char s[12]; |
1da177e4 | 575 | |
9ce71148 | 576 | root = sb->s_root; |
9ce71148 JT |
577 | opts = &fsi->mount_opts; |
578 | ||
162b97cf | 579 | inode = new_inode(sb); |
1da177e4 | 580 | if (!inode) |
162b97cf | 581 | return ERR_PTR(-ENOMEM); |
1da177e4 | 582 | |
f11afb61 | 583 | inode->i_ino = index + 3; |
d0eafc7d DH |
584 | inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); |
585 | inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); | |
078cd827 | 586 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
8ead9dd5 | 587 | init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); |
1da177e4 | 588 | |
f11afb61 | 589 | sprintf(s, "%d", index); |
89a52e10 | 590 | |
59e55e6c | 591 | dentry = d_alloc_name(root, s); |
b12d1259 | 592 | if (dentry) { |
8ead9dd5 | 593 | dentry->d_fsdata = priv; |
89a52e10 | 594 | d_add(dentry, inode); |
2b0143b5 | 595 | fsnotify_create(d_inode(root), dentry); |
aa597bc1 AV |
596 | } else { |
597 | iput(inode); | |
8ead9dd5 | 598 | dentry = ERR_PTR(-ENOMEM); |
3972b7f6 | 599 | } |
1da177e4 | 600 | |
8ead9dd5 | 601 | return dentry; |
1da177e4 LT |
602 | } |
603 | ||
1dcb8e6d JS |
604 | /** |
605 | * devpts_get_priv -- get private data for a slave | |
606 | * @pts_inode: inode of the slave | |
607 | * | |
608 | * Returns whatever was passed as priv in devpts_pty_new for a given inode. | |
609 | */ | |
8ead9dd5 | 610 | void *devpts_get_priv(struct dentry *dentry) |
1da177e4 | 611 | { |
3e423945 LT |
612 | if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) |
613 | return NULL; | |
8ead9dd5 | 614 | return dentry->d_fsdata; |
1da177e4 LT |
615 | } |
616 | ||
1dcb8e6d JS |
617 | /** |
618 | * devpts_pty_kill -- remove inode form /dev/pts/ | |
619 | * @inode: inode of the slave to be removed | |
620 | * | |
621 | * This is an inverse operation of devpts_pty_new. | |
622 | */ | |
8ead9dd5 | 623 | void devpts_pty_kill(struct dentry *dentry) |
1da177e4 | 624 | { |
8ead9dd5 | 625 | WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); |
1da177e4 | 626 | |
8ead9dd5 LT |
627 | dentry->d_fsdata = NULL; |
628 | drop_nlink(dentry->d_inode); | |
aa597bc1 AV |
629 | d_delete(dentry); |
630 | dput(dentry); /* d_alloc_name() in devpts_pty_new() */ | |
1da177e4 LT |
631 | } |
632 | ||
633 | static int __init init_devpts_fs(void) | |
634 | { | |
635 | int err = register_filesystem(&devpts_fs_type); | |
636 | if (!err) { | |
eedf265a | 637 | register_sysctl_table(pty_root_table); |
1da177e4 LT |
638 | } |
639 | return err; | |
640 | } | |
1da177e4 | 641 | module_init(init_devpts_fs) |