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 | ||
141 | /* Has the devpts filesystem already been found? */ | |
142 | if (path->mnt->mnt_sb->s_magic == DEVPTS_SUPER_MAGIC) | |
143 | return 0; | |
144 | ||
145 | /* Is a devpts filesystem at "pts" in the same directory? */ | |
146 | err = path_pts(path); | |
147 | if (err) | |
148 | return err; | |
149 | ||
150 | /* Is the path the root of a devpts filesystem? */ | |
151 | sb = path->mnt->mnt_sb; | |
152 | if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || | |
153 | (path->mnt->mnt_root != sb->s_root)) | |
154 | return -ENODEV; | |
155 | ||
156 | return 0; | |
157 | } | |
158 | ||
159 | struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) | |
160 | { | |
161 | struct path path; | |
162 | int err; | |
163 | ||
164 | path = filp->f_path; | |
165 | path_get(&path); | |
166 | ||
167 | err = devpts_ptmx_path(&path); | |
168 | dput(path.dentry); | |
169 | if (err) { | |
170 | mntput(path.mnt); | |
171 | path.mnt = ERR_PTR(err); | |
172 | } | |
173 | if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) { | |
174 | mntput(path.mnt); | |
175 | path.mnt = ERR_PTR(-ENODEV); | |
176 | } | |
177 | return path.mnt; | |
178 | } | |
179 | ||
143c97cc | 180 | struct pts_fs_info *devpts_acquire(struct file *filp) |
59e55e6c | 181 | { |
eedf265a EB |
182 | struct pts_fs_info *result; |
183 | struct path path; | |
184 | struct super_block *sb; | |
185 | int err; | |
186 | ||
187 | path = filp->f_path; | |
188 | path_get(&path); | |
189 | ||
311fc65c EB |
190 | err = devpts_ptmx_path(&path); |
191 | if (err) { | |
192 | result = ERR_PTR(err); | |
193 | goto out; | |
eedf265a EB |
194 | } |
195 | ||
196 | /* | |
197 | * pty code needs to hold extra references in case of last /dev/tty close | |
198 | */ | |
311fc65c | 199 | sb = path.mnt->mnt_sb; |
eedf265a EB |
200 | atomic_inc(&sb->s_active); |
201 | result = DEVPTS_SB(sb); | |
202 | ||
203 | out: | |
204 | path_put(&path); | |
205 | return result; | |
206 | } | |
207 | ||
208 | void devpts_release(struct pts_fs_info *fsi) | |
209 | { | |
210 | deactivate_super(fsi->sb); | |
59e55e6c SB |
211 | } |
212 | ||
2a1b2dc0 SB |
213 | #define PARSE_MOUNT 0 |
214 | #define PARSE_REMOUNT 1 | |
215 | ||
1f71ebed SB |
216 | /* |
217 | * parse_mount_options(): | |
04541a2f | 218 | * Set @opts to mount options specified in @data. If an option is not |
eedf265a | 219 | * specified in @data, set it to its default value. |
1f71ebed SB |
220 | * |
221 | * Note: @data may be NULL (in which case all options are set to default). | |
222 | */ | |
2a1b2dc0 | 223 | static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) |
1da177e4 | 224 | { |
7a673c6b | 225 | char *p; |
f04c6ce2 EB |
226 | kuid_t uid; |
227 | kgid_t gid; | |
7a673c6b | 228 | |
31af0abb SB |
229 | opts->setuid = 0; |
230 | opts->setgid = 0; | |
f04c6ce2 EB |
231 | opts->uid = GLOBAL_ROOT_UID; |
232 | opts->gid = GLOBAL_ROOT_GID; | |
31af0abb | 233 | opts->mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 234 | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
e9aba515 | 235 | opts->max = NR_UNIX98_PTY_MAX; |
7a673c6b | 236 | |
eedf265a EB |
237 | /* Only allow instances mounted from the initial mount |
238 | * namespace to tap the reserve pool of ptys. | |
239 | */ | |
2a1b2dc0 | 240 | if (op == PARSE_MOUNT) |
eedf265a EB |
241 | opts->reserve = |
242 | (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); | |
2a1b2dc0 | 243 | |
7a673c6b DP |
244 | while ((p = strsep(&data, ",")) != NULL) { |
245 | substring_t args[MAX_OPT_ARGS]; | |
246 | int token; | |
247 | int option; | |
248 | ||
249 | if (!*p) | |
1da177e4 | 250 | continue; |
7a673c6b DP |
251 | |
252 | token = match_token(p, tokens, args); | |
253 | switch (token) { | |
254 | case Opt_uid: | |
255 | if (match_int(&args[0], &option)) | |
256 | return -EINVAL; | |
f04c6ce2 EB |
257 | uid = make_kuid(current_user_ns(), option); |
258 | if (!uid_valid(uid)) | |
259 | return -EINVAL; | |
260 | opts->uid = uid; | |
31af0abb | 261 | opts->setuid = 1; |
7a673c6b DP |
262 | break; |
263 | case Opt_gid: | |
264 | if (match_int(&args[0], &option)) | |
265 | return -EINVAL; | |
f04c6ce2 EB |
266 | gid = make_kgid(current_user_ns(), option); |
267 | if (!gid_valid(gid)) | |
268 | return -EINVAL; | |
269 | opts->gid = gid; | |
31af0abb | 270 | opts->setgid = 1; |
7a673c6b DP |
271 | break; |
272 | case Opt_mode: | |
273 | if (match_octal(&args[0], &option)) | |
274 | return -EINVAL; | |
31af0abb | 275 | opts->mode = option & S_IALLUGO; |
7a673c6b | 276 | break; |
1f8f1e29 SB |
277 | case Opt_ptmxmode: |
278 | if (match_octal(&args[0], &option)) | |
279 | return -EINVAL; | |
280 | opts->ptmxmode = option & S_IALLUGO; | |
281 | break; | |
2a1b2dc0 | 282 | case Opt_newinstance: |
2a1b2dc0 | 283 | break; |
e9aba515 KK |
284 | case Opt_max: |
285 | if (match_int(&args[0], &option) || | |
286 | option < 0 || option > NR_UNIX98_PTY_MAX) | |
287 | return -EINVAL; | |
288 | opts->max = option; | |
289 | break; | |
7a673c6b | 290 | default: |
04541a2f | 291 | pr_err("called with bogus options\n"); |
1da177e4 LT |
292 | return -EINVAL; |
293 | } | |
294 | } | |
1da177e4 LT |
295 | |
296 | return 0; | |
297 | } | |
298 | ||
1f8f1e29 SB |
299 | static int mknod_ptmx(struct super_block *sb) |
300 | { | |
301 | int mode; | |
302 | int rc = -ENOMEM; | |
303 | struct dentry *dentry; | |
304 | struct inode *inode; | |
305 | struct dentry *root = sb->s_root; | |
306 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
307 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
e98d4137 EB |
308 | kuid_t ptmx_uid = current_fsuid(); |
309 | kgid_t ptmx_gid = current_fsgid(); | |
1f8f1e29 | 310 | |
5955102c | 311 | inode_lock(d_inode(root)); |
1f8f1e29 SB |
312 | |
313 | /* If we have already created ptmx node, return */ | |
314 | if (fsi->ptmx_dentry) { | |
315 | rc = 0; | |
316 | goto out; | |
317 | } | |
318 | ||
319 | dentry = d_alloc_name(root, "ptmx"); | |
320 | if (!dentry) { | |
04541a2f | 321 | pr_err("Unable to alloc dentry for ptmx node\n"); |
1f8f1e29 SB |
322 | goto out; |
323 | } | |
324 | ||
325 | /* | |
326 | * Create a new 'ptmx' node in this mount of devpts. | |
327 | */ | |
328 | inode = new_inode(sb); | |
329 | if (!inode) { | |
04541a2f | 330 | pr_err("Unable to alloc inode for ptmx node\n"); |
1f8f1e29 SB |
331 | dput(dentry); |
332 | goto out; | |
333 | } | |
334 | ||
335 | inode->i_ino = 2; | |
078cd827 | 336 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1f8f1e29 SB |
337 | |
338 | mode = S_IFCHR|opts->ptmxmode; | |
339 | init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); | |
e98d4137 EB |
340 | inode->i_uid = ptmx_uid; |
341 | inode->i_gid = ptmx_gid; | |
1f8f1e29 SB |
342 | |
343 | d_add(dentry, inode); | |
344 | ||
345 | fsi->ptmx_dentry = dentry; | |
346 | rc = 0; | |
1f8f1e29 | 347 | out: |
5955102c | 348 | inode_unlock(d_inode(root)); |
1f8f1e29 SB |
349 | return rc; |
350 | } | |
351 | ||
352 | static void update_ptmx_mode(struct pts_fs_info *fsi) | |
353 | { | |
354 | struct inode *inode; | |
355 | if (fsi->ptmx_dentry) { | |
2b0143b5 | 356 | inode = d_inode(fsi->ptmx_dentry); |
1f8f1e29 SB |
357 | inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; |
358 | } | |
359 | } | |
1f8f1e29 | 360 | |
53af8ee4 SB |
361 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
362 | { | |
1f8f1e29 | 363 | int err; |
53af8ee4 SB |
364 | struct pts_fs_info *fsi = DEVPTS_SB(sb); |
365 | struct pts_mount_opts *opts = &fsi->mount_opts; | |
366 | ||
2a1b2dc0 | 367 | err = parse_mount_options(data, PARSE_REMOUNT, opts); |
1f8f1e29 SB |
368 | |
369 | /* | |
370 | * parse_mount_options() restores options to default values | |
371 | * before parsing and may have changed ptmxmode. So, update the | |
372 | * mode in the inode too. Bogus options don't fail the remount, | |
373 | * so do this even on error return. | |
374 | */ | |
375 | update_ptmx_mode(fsi); | |
376 | ||
377 | return err; | |
53af8ee4 SB |
378 | } |
379 | ||
34c80b1d | 380 | static int devpts_show_options(struct seq_file *seq, struct dentry *root) |
b87a267e | 381 | { |
34c80b1d | 382 | struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); |
31af0abb SB |
383 | struct pts_mount_opts *opts = &fsi->mount_opts; |
384 | ||
385 | if (opts->setuid) | |
04541a2f FF |
386 | seq_printf(seq, ",uid=%u", |
387 | from_kuid_munged(&init_user_ns, opts->uid)); | |
31af0abb | 388 | if (opts->setgid) |
04541a2f FF |
389 | seq_printf(seq, ",gid=%u", |
390 | from_kgid_munged(&init_user_ns, opts->gid)); | |
31af0abb | 391 | seq_printf(seq, ",mode=%03o", opts->mode); |
1f8f1e29 | 392 | seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); |
e9aba515 KK |
393 | if (opts->max < NR_UNIX98_PTY_MAX) |
394 | seq_printf(seq, ",max=%d", opts->max); | |
b87a267e MS |
395 | |
396 | return 0; | |
397 | } | |
398 | ||
ee9b6d61 | 399 | static const struct super_operations devpts_sops = { |
1da177e4 LT |
400 | .statfs = simple_statfs, |
401 | .remount_fs = devpts_remount, | |
b87a267e | 402 | .show_options = devpts_show_options, |
1da177e4 LT |
403 | }; |
404 | ||
67245ff3 | 405 | static void *new_pts_fs_info(struct super_block *sb) |
e76b7c01 SB |
406 | { |
407 | struct pts_fs_info *fsi; | |
408 | ||
409 | fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); | |
410 | if (!fsi) | |
411 | return NULL; | |
412 | ||
413 | ida_init(&fsi->allocated_ptys); | |
31af0abb | 414 | fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; |
1f8f1e29 | 415 | fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; |
67245ff3 | 416 | fsi->sb = sb; |
e76b7c01 SB |
417 | |
418 | return fsi; | |
419 | } | |
420 | ||
1da177e4 LT |
421 | static int |
422 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
423 | { | |
1f8f1e29 | 424 | struct inode *inode; |
dee87d47 | 425 | int error; |
1da177e4 | 426 | |
cc50a07a | 427 | s->s_iflags &= ~SB_I_NODEV; |
1da177e4 LT |
428 | s->s_blocksize = 1024; |
429 | s->s_blocksize_bits = 10; | |
430 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
431 | s->s_op = &devpts_sops; | |
1da177e4 LT |
432 | s->s_time_gran = 1; |
433 | ||
dee87d47 | 434 | error = -ENOMEM; |
67245ff3 | 435 | s->s_fs_info = new_pts_fs_info(s); |
e76b7c01 SB |
436 | if (!s->s_fs_info) |
437 | goto fail; | |
438 | ||
dee87d47 EB |
439 | error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); |
440 | if (error) | |
441 | goto fail; | |
442 | ||
443 | error = -ENOMEM; | |
1da177e4 LT |
444 | inode = new_inode(s); |
445 | if (!inode) | |
3850aba7 | 446 | goto fail; |
1da177e4 | 447 | inode->i_ino = 1; |
078cd827 | 448 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
1da177e4 LT |
449 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; |
450 | inode->i_op = &simple_dir_inode_operations; | |
451 | inode->i_fop = &simple_dir_operations; | |
bfe86848 | 452 | set_nlink(inode, 2); |
1da177e4 | 453 | |
48fde701 | 454 | s->s_root = d_make_root(inode); |
180d9044 EB |
455 | if (!s->s_root) { |
456 | pr_err("get root dentry failed\n"); | |
457 | goto fail; | |
458 | } | |
1f8f1e29 | 459 | |
180d9044 EB |
460 | error = mknod_ptmx(s); |
461 | if (error) | |
462 | goto fail_dput; | |
e76b7c01 | 463 | |
180d9044 EB |
464 | return 0; |
465 | fail_dput: | |
466 | dput(s->s_root); | |
467 | s->s_root = NULL; | |
1da177e4 | 468 | fail: |
dee87d47 | 469 | return error; |
1da177e4 LT |
470 | } |
471 | ||
2a1b2dc0 | 472 | /* |
fc14f2fe | 473 | * devpts_mount() |
1bd79035 | 474 | * |
eedf265a EB |
475 | * Mount a new (private) instance of devpts. PTYs created in this |
476 | * instance are independent of the PTYs in other devpts instances. | |
d4076ac5 | 477 | */ |
fc14f2fe AV |
478 | static struct dentry *devpts_mount(struct file_system_type *fs_type, |
479 | int flags, const char *dev_name, void *data) | |
1da177e4 | 480 | { |
c1b241f0 | 481 | return mount_nodev(fs_type, flags, data, devpts_fill_super); |
1da177e4 | 482 | } |
482984f0 | 483 | |
e76b7c01 SB |
484 | static void devpts_kill_sb(struct super_block *sb) |
485 | { | |
486 | struct pts_fs_info *fsi = DEVPTS_SB(sb); | |
487 | ||
40b320e1 EB |
488 | if (fsi) |
489 | ida_destroy(&fsi->allocated_ptys); | |
e76b7c01 | 490 | kfree(fsi); |
1f8f1e29 | 491 | kill_litter_super(sb); |
e76b7c01 SB |
492 | } |
493 | ||
1da177e4 | 494 | static struct file_system_type devpts_fs_type = { |
1da177e4 | 495 | .name = "devpts", |
fc14f2fe | 496 | .mount = devpts_mount, |
e76b7c01 | 497 | .kill_sb = devpts_kill_sb, |
cc50a07a | 498 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
499 | }; |
500 | ||
501 | /* | |
502 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
503 | * to the System V naming convention | |
504 | */ | |
505 | ||
67245ff3 | 506 | int devpts_new_index(struct pts_fs_info *fsi) |
718a9163 SB |
507 | { |
508 | int index; | |
7ee7c12b | 509 | int ida_ret; |
718a9163 SB |
510 | |
511 | retry: | |
835aa440 | 512 | if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) |
718a9163 | 513 | return -ENOMEM; |
718a9163 SB |
514 | |
515 | mutex_lock(&allocated_ptys_lock); | |
eedf265a EB |
516 | if (pty_count >= (pty_limit - |
517 | (fsi->mount_opts.reserve ? 0 : pty_reserve))) { | |
e9aba515 KK |
518 | mutex_unlock(&allocated_ptys_lock); |
519 | return -ENOSPC; | |
520 | } | |
521 | ||
e76b7c01 | 522 | ida_ret = ida_get_new(&fsi->allocated_ptys, &index); |
7ee7c12b | 523 | if (ida_ret < 0) { |
718a9163 | 524 | mutex_unlock(&allocated_ptys_lock); |
7ee7c12b | 525 | if (ida_ret == -EAGAIN) |
718a9163 SB |
526 | goto retry; |
527 | return -EIO; | |
528 | } | |
529 | ||
e9aba515 | 530 | if (index >= fsi->mount_opts.max) { |
e76b7c01 | 531 | ida_remove(&fsi->allocated_ptys, index); |
718a9163 | 532 | mutex_unlock(&allocated_ptys_lock); |
e9aba515 | 533 | return -ENOSPC; |
718a9163 | 534 | } |
a4834c10 | 535 | pty_count++; |
718a9163 SB |
536 | mutex_unlock(&allocated_ptys_lock); |
537 | return index; | |
538 | } | |
539 | ||
67245ff3 | 540 | void devpts_kill_index(struct pts_fs_info *fsi, int idx) |
718a9163 SB |
541 | { |
542 | mutex_lock(&allocated_ptys_lock); | |
e76b7c01 | 543 | ida_remove(&fsi->allocated_ptys, idx); |
a4834c10 | 544 | pty_count--; |
718a9163 SB |
545 | mutex_unlock(&allocated_ptys_lock); |
546 | } | |
547 | ||
1dcb8e6d JS |
548 | /** |
549 | * devpts_pty_new -- create a new inode in /dev/pts/ | |
550 | * @ptmx_inode: inode of the master | |
551 | * @device: major+minor of the node to be created | |
552 | * @index: used as a name of the node | |
553 | * @priv: what's given back by devpts_get_priv | |
554 | * | |
555 | * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. | |
556 | */ | |
8ead9dd5 | 557 | struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) |
1da177e4 | 558 | { |
1da177e4 | 559 | struct dentry *dentry; |
eedf265a | 560 | struct super_block *sb = fsi->sb; |
162b97cf | 561 | struct inode *inode; |
9ce71148 | 562 | struct dentry *root; |
9ce71148 | 563 | struct pts_mount_opts *opts; |
89a52e10 | 564 | char s[12]; |
1da177e4 | 565 | |
9ce71148 | 566 | root = sb->s_root; |
9ce71148 JT |
567 | opts = &fsi->mount_opts; |
568 | ||
162b97cf | 569 | inode = new_inode(sb); |
1da177e4 | 570 | if (!inode) |
162b97cf | 571 | return ERR_PTR(-ENOMEM); |
1da177e4 | 572 | |
f11afb61 | 573 | inode->i_ino = index + 3; |
d0eafc7d DH |
574 | inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); |
575 | inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); | |
078cd827 | 576 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
8ead9dd5 | 577 | init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); |
1da177e4 | 578 | |
f11afb61 | 579 | sprintf(s, "%d", index); |
89a52e10 | 580 | |
59e55e6c | 581 | dentry = d_alloc_name(root, s); |
b12d1259 | 582 | if (dentry) { |
8ead9dd5 | 583 | dentry->d_fsdata = priv; |
89a52e10 | 584 | d_add(dentry, inode); |
2b0143b5 | 585 | fsnotify_create(d_inode(root), dentry); |
aa597bc1 AV |
586 | } else { |
587 | iput(inode); | |
8ead9dd5 | 588 | dentry = ERR_PTR(-ENOMEM); |
3972b7f6 | 589 | } |
1da177e4 | 590 | |
8ead9dd5 | 591 | return dentry; |
1da177e4 LT |
592 | } |
593 | ||
1dcb8e6d JS |
594 | /** |
595 | * devpts_get_priv -- get private data for a slave | |
596 | * @pts_inode: inode of the slave | |
597 | * | |
598 | * Returns whatever was passed as priv in devpts_pty_new for a given inode. | |
599 | */ | |
8ead9dd5 | 600 | void *devpts_get_priv(struct dentry *dentry) |
1da177e4 | 601 | { |
3e423945 LT |
602 | if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) |
603 | return NULL; | |
8ead9dd5 | 604 | return dentry->d_fsdata; |
1da177e4 LT |
605 | } |
606 | ||
1dcb8e6d JS |
607 | /** |
608 | * devpts_pty_kill -- remove inode form /dev/pts/ | |
609 | * @inode: inode of the slave to be removed | |
610 | * | |
611 | * This is an inverse operation of devpts_pty_new. | |
612 | */ | |
8ead9dd5 | 613 | void devpts_pty_kill(struct dentry *dentry) |
1da177e4 | 614 | { |
8ead9dd5 | 615 | WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); |
1da177e4 | 616 | |
8ead9dd5 LT |
617 | dentry->d_fsdata = NULL; |
618 | drop_nlink(dentry->d_inode); | |
aa597bc1 AV |
619 | d_delete(dentry); |
620 | dput(dentry); /* d_alloc_name() in devpts_pty_new() */ | |
1da177e4 LT |
621 | } |
622 | ||
623 | static int __init init_devpts_fs(void) | |
624 | { | |
625 | int err = register_filesystem(&devpts_fs_type); | |
626 | if (!err) { | |
eedf265a | 627 | register_sysctl_table(pty_root_table); |
1da177e4 LT |
628 | } |
629 | return err; | |
630 | } | |
1da177e4 | 631 | module_init(init_devpts_fs) |