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1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 *
4 * Added support for a Unix98-style ptmx device.
5 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
6 *
7 * When reading this code see also fs/devpts. In particular note that the
8 * driver_data field is used by the devpts side as a binding to the devpts
9 * inode.
10 */
11
12#include <linux/module.h>
13
14#include <linux/errno.h>
15#include <linux/interrupt.h>
16#include <linux/tty.h>
17#include <linux/tty_flip.h>
18#include <linux/fcntl.h>
19#include <linux/sched.h>
20#include <linux/string.h>
21#include <linux/major.h>
22#include <linux/mm.h>
23#include <linux/init.h>
24#include <linux/sysctl.h>
25#include <linux/device.h>
26#include <linux/uaccess.h>
27#include <linux/bitops.h>
28#include <linux/devpts_fs.h>
29#include <linux/slab.h>
30
31#include <asm/system.h>
32
33#ifdef CONFIG_UNIX98_PTYS
34static struct tty_driver *ptm_driver;
35static struct tty_driver *pts_driver;
36#endif
37
38static void pty_close(struct tty_struct *tty, struct file *filp)
39{
40 BUG_ON(!tty);
41 if (tty->driver->subtype == PTY_TYPE_MASTER)
42 WARN_ON(tty->count > 1);
43 else {
44 if (tty->count > 2)
45 return;
46 }
47 wake_up_interruptible(&tty->read_wait);
48 wake_up_interruptible(&tty->write_wait);
49 tty->packet = 0;
50 if (!tty->link)
51 return;
52 tty->link->packet = 0;
53 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
54 wake_up_interruptible(&tty->link->read_wait);
55 wake_up_interruptible(&tty->link->write_wait);
56 if (tty->driver->subtype == PTY_TYPE_MASTER) {
57 set_bit(TTY_OTHER_CLOSED, &tty->flags);
58#ifdef CONFIG_UNIX98_PTYS
59 if (tty->driver == ptm_driver)
60 devpts_pty_kill(tty->link);
61#endif
62 tty_unlock();
63 tty_vhangup(tty->link);
64 tty_lock();
65 }
66}
67
68/*
69 * The unthrottle routine is called by the line discipline to signal
70 * that it can receive more characters. For PTY's, the TTY_THROTTLED
71 * flag is always set, to force the line discipline to always call the
72 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
73 * characters in the queue. This is necessary since each time this
74 * happens, we need to wake up any sleeping processes that could be
75 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
76 * for the pty buffer to be drained.
77 */
78static void pty_unthrottle(struct tty_struct *tty)
79{
80 tty_wakeup(tty->link);
81 set_bit(TTY_THROTTLED, &tty->flags);
82}
83
84/**
85 * pty_space - report space left for writing
86 * @to: tty we are writing into
87 *
88 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
89 * allows a lot of overspill room for echo and other fun messes to
90 * be handled properly
91 */
92
93static int pty_space(struct tty_struct *to)
94{
95 int n = 8192 - to->buf.memory_used;
96 if (n < 0)
97 return 0;
98 return n;
99}
100
101/**
102 * pty_write - write to a pty
103 * @tty: the tty we write from
104 * @buf: kernel buffer of data
105 * @count: bytes to write
106 *
107 * Our "hardware" write method. Data is coming from the ldisc which
108 * may be in a non sleeping state. We simply throw this at the other
109 * end of the link as if we were an IRQ handler receiving stuff for
110 * the other side of the pty/tty pair.
111 */
112
113static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
114{
115 struct tty_struct *to = tty->link;
116
117 if (tty->stopped)
118 return 0;
119
120 if (c > 0) {
121 /* Stuff the data into the input queue of the other end */
122 c = tty_insert_flip_string(to, buf, c);
123 /* And shovel */
124 if (c) {
125 tty_flip_buffer_push(to);
126 tty_wakeup(tty);
127 }
128 }
129 return c;
130}
131
132/**
133 * pty_write_room - write space
134 * @tty: tty we are writing from
135 *
136 * Report how many bytes the ldisc can send into the queue for
137 * the other device.
138 */
139
140static int pty_write_room(struct tty_struct *tty)
141{
142 if (tty->stopped)
143 return 0;
144 return pty_space(tty->link);
145}
146
147/**
148 * pty_chars_in_buffer - characters currently in our tx queue
149 * @tty: our tty
150 *
151 * Report how much we have in the transmit queue. As everything is
152 * instantly at the other end this is easy to implement.
153 */
154
155static int pty_chars_in_buffer(struct tty_struct *tty)
156{
157 return 0;
158}
159
160/* Set the lock flag on a pty */
161static int pty_set_lock(struct tty_struct *tty, int __user *arg)
162{
163 int val;
164 if (get_user(val, arg))
165 return -EFAULT;
166 if (val)
167 set_bit(TTY_PTY_LOCK, &tty->flags);
168 else
169 clear_bit(TTY_PTY_LOCK, &tty->flags);
170 return 0;
171}
172
173/* Send a signal to the slave */
174static int pty_signal(struct tty_struct *tty, int sig)
175{
176 unsigned long flags;
177 struct pid *pgrp;
178
179 if (tty->link) {
180 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
181 pgrp = get_pid(tty->link->pgrp);
182 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
183
184 kill_pgrp(pgrp, sig, 1);
185 put_pid(pgrp);
186 }
187 return 0;
188}
189
190static void pty_flush_buffer(struct tty_struct *tty)
191{
192 struct tty_struct *to = tty->link;
193 unsigned long flags;
194
195 if (!to)
196 return;
197 /* tty_buffer_flush(to); FIXME */
198 if (to->packet) {
199 spin_lock_irqsave(&tty->ctrl_lock, flags);
200 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
201 wake_up_interruptible(&to->read_wait);
202 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
203 }
204}
205
206static int pty_open(struct tty_struct *tty, struct file *filp)
207{
208 int retval = -ENODEV;
209
210 if (!tty || !tty->link)
211 goto out;
212
213 retval = -EIO;
214 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
215 goto out;
216 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
217 goto out;
218 if (tty->link->count != 1)
219 goto out;
220
221 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
222 set_bit(TTY_THROTTLED, &tty->flags);
223 retval = 0;
224out:
225 return retval;
226}
227
228static void pty_set_termios(struct tty_struct *tty,
229 struct ktermios *old_termios)
230{
231 tty->termios->c_cflag &= ~(CSIZE | PARENB);
232 tty->termios->c_cflag |= (CS8 | CREAD);
233}
234
235/**
236 * pty_do_resize - resize event
237 * @tty: tty being resized
238 * @ws: window size being set.
239 *
240 * Update the termios variables and send the necessary signals to
241 * peform a terminal resize correctly
242 */
243
244int pty_resize(struct tty_struct *tty, struct winsize *ws)
245{
246 struct pid *pgrp, *rpgrp;
247 unsigned long flags;
248 struct tty_struct *pty = tty->link;
249
250 /* For a PTY we need to lock the tty side */
251 mutex_lock(&tty->termios_mutex);
252 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
253 goto done;
254
255 /* Get the PID values and reference them so we can
256 avoid holding the tty ctrl lock while sending signals.
257 We need to lock these individually however. */
258
259 spin_lock_irqsave(&tty->ctrl_lock, flags);
260 pgrp = get_pid(tty->pgrp);
261 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
262
263 spin_lock_irqsave(&pty->ctrl_lock, flags);
264 rpgrp = get_pid(pty->pgrp);
265 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
266
267 if (pgrp)
268 kill_pgrp(pgrp, SIGWINCH, 1);
269 if (rpgrp != pgrp && rpgrp)
270 kill_pgrp(rpgrp, SIGWINCH, 1);
271
272 put_pid(pgrp);
273 put_pid(rpgrp);
274
275 tty->winsize = *ws;
276 pty->winsize = *ws; /* Never used so will go away soon */
277done:
278 mutex_unlock(&tty->termios_mutex);
279 return 0;
280}
281
282/* Traditional BSD devices */
283#ifdef CONFIG_LEGACY_PTYS
284
285static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
286{
287 struct tty_struct *o_tty;
288 int idx = tty->index;
289 int retval;
290
291 o_tty = alloc_tty_struct();
292 if (!o_tty)
293 return -ENOMEM;
294 if (!try_module_get(driver->other->owner)) {
295 /* This cannot in fact currently happen */
296 retval = -ENOMEM;
297 goto err_free_tty;
298 }
299 initialize_tty_struct(o_tty, driver->other, idx);
300
301 /* We always use new tty termios data so we can do this
302 the easy way .. */
303 retval = tty_init_termios(tty);
304 if (retval)
305 goto err_deinit_tty;
306
307 retval = tty_init_termios(o_tty);
308 if (retval)
309 goto err_free_termios;
310
311 /*
312 * Everything allocated ... set up the o_tty structure.
313 */
314 driver->other->ttys[idx] = o_tty;
315 tty_driver_kref_get(driver->other);
316 if (driver->subtype == PTY_TYPE_MASTER)
317 o_tty->count++;
318 /* Establish the links in both directions */
319 tty->link = o_tty;
320 o_tty->link = tty;
321
322 tty_driver_kref_get(driver);
323 tty->count++;
324 driver->ttys[idx] = tty;
325 return 0;
326err_free_termios:
327 tty_free_termios(tty);
328err_deinit_tty:
329 deinitialize_tty_struct(o_tty);
330 module_put(o_tty->driver->owner);
331err_free_tty:
332 free_tty_struct(o_tty);
333 return retval;
334}
335
336static int pty_bsd_ioctl(struct tty_struct *tty,
337 unsigned int cmd, unsigned long arg)
338{
339 switch (cmd) {
340 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
341 return pty_set_lock(tty, (int __user *) arg);
342 case TIOCSIG: /* Send signal to other side of pty */
343 return pty_signal(tty, (int) arg);
344 }
345 return -ENOIOCTLCMD;
346}
347
348static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
349module_param(legacy_count, int, 0);
350
351/*
352 * The master side of a pty can do TIOCSPTLCK and thus
353 * has pty_bsd_ioctl.
354 */
355static const struct tty_operations master_pty_ops_bsd = {
356 .install = pty_install,
357 .open = pty_open,
358 .close = pty_close,
359 .write = pty_write,
360 .write_room = pty_write_room,
361 .flush_buffer = pty_flush_buffer,
362 .chars_in_buffer = pty_chars_in_buffer,
363 .unthrottle = pty_unthrottle,
364 .set_termios = pty_set_termios,
365 .ioctl = pty_bsd_ioctl,
366 .resize = pty_resize
367};
368
369static const struct tty_operations slave_pty_ops_bsd = {
370 .install = pty_install,
371 .open = pty_open,
372 .close = pty_close,
373 .write = pty_write,
374 .write_room = pty_write_room,
375 .flush_buffer = pty_flush_buffer,
376 .chars_in_buffer = pty_chars_in_buffer,
377 .unthrottle = pty_unthrottle,
378 .set_termios = pty_set_termios,
379 .resize = pty_resize
380};
381
382static void __init legacy_pty_init(void)
383{
384 struct tty_driver *pty_driver, *pty_slave_driver;
385
386 if (legacy_count <= 0)
387 return;
388
389 pty_driver = alloc_tty_driver(legacy_count);
390 if (!pty_driver)
391 panic("Couldn't allocate pty driver");
392
393 pty_slave_driver = alloc_tty_driver(legacy_count);
394 if (!pty_slave_driver)
395 panic("Couldn't allocate pty slave driver");
396
397 pty_driver->owner = THIS_MODULE;
398 pty_driver->driver_name = "pty_master";
399 pty_driver->name = "pty";
400 pty_driver->major = PTY_MASTER_MAJOR;
401 pty_driver->minor_start = 0;
402 pty_driver->type = TTY_DRIVER_TYPE_PTY;
403 pty_driver->subtype = PTY_TYPE_MASTER;
404 pty_driver->init_termios = tty_std_termios;
405 pty_driver->init_termios.c_iflag = 0;
406 pty_driver->init_termios.c_oflag = 0;
407 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
408 pty_driver->init_termios.c_lflag = 0;
409 pty_driver->init_termios.c_ispeed = 38400;
410 pty_driver->init_termios.c_ospeed = 38400;
411 pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
412 pty_driver->other = pty_slave_driver;
413 tty_set_operations(pty_driver, &master_pty_ops_bsd);
414
415 pty_slave_driver->owner = THIS_MODULE;
416 pty_slave_driver->driver_name = "pty_slave";
417 pty_slave_driver->name = "ttyp";
418 pty_slave_driver->major = PTY_SLAVE_MAJOR;
419 pty_slave_driver->minor_start = 0;
420 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
421 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
422 pty_slave_driver->init_termios = tty_std_termios;
423 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
424 pty_slave_driver->init_termios.c_ispeed = 38400;
425 pty_slave_driver->init_termios.c_ospeed = 38400;
426 pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
427 TTY_DRIVER_REAL_RAW;
428 pty_slave_driver->other = pty_driver;
429 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
430
431 if (tty_register_driver(pty_driver))
432 panic("Couldn't register pty driver");
433 if (tty_register_driver(pty_slave_driver))
434 panic("Couldn't register pty slave driver");
435}
436#else
437static inline void legacy_pty_init(void) { }
438#endif
439
440/* Unix98 devices */
441#ifdef CONFIG_UNIX98_PTYS
442/*
443 * sysctl support for setting limits on the number of Unix98 ptys allocated.
444 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
445 */
446int pty_limit = NR_UNIX98_PTY_DEFAULT;
447static int pty_limit_min;
448static int pty_limit_max = NR_UNIX98_PTY_MAX;
449static int tty_count;
450static int pty_count;
451
452static inline void pty_inc_count(void)
453{
454 pty_count = (++tty_count) / 2;
455}
456
457static inline void pty_dec_count(void)
458{
459 pty_count = (--tty_count) / 2;
460}
461
462static struct cdev ptmx_cdev;
463
464static struct ctl_table pty_table[] = {
465 {
466 .procname = "max",
467 .maxlen = sizeof(int),
468 .mode = 0644,
469 .data = &pty_limit,
470 .proc_handler = proc_dointvec_minmax,
471 .extra1 = &pty_limit_min,
472 .extra2 = &pty_limit_max,
473 }, {
474 .procname = "nr",
475 .maxlen = sizeof(int),
476 .mode = 0444,
477 .data = &pty_count,
478 .proc_handler = proc_dointvec,
479 },
480 {}
481};
482
483static struct ctl_table pty_kern_table[] = {
484 {
485 .procname = "pty",
486 .mode = 0555,
487 .child = pty_table,
488 },
489 {}
490};
491
492static struct ctl_table pty_root_table[] = {
493 {
494 .procname = "kernel",
495 .mode = 0555,
496 .child = pty_kern_table,
497 },
498 {}
499};
500
501
502static int pty_unix98_ioctl(struct tty_struct *tty,
503 unsigned int cmd, unsigned long arg)
504{
505 switch (cmd) {
506 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
507 return pty_set_lock(tty, (int __user *)arg);
508 case TIOCGPTN: /* Get PT Number */
509 return put_user(tty->index, (unsigned int __user *)arg);
510 case TIOCSIG: /* Send signal to other side of pty */
511 return pty_signal(tty, (int) arg);
512 }
513
514 return -ENOIOCTLCMD;
515}
516
517/**
518 * ptm_unix98_lookup - find a pty master
519 * @driver: ptm driver
520 * @idx: tty index
521 *
522 * Look up a pty master device. Called under the tty_mutex for now.
523 * This provides our locking.
524 */
525
526static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
527 struct inode *ptm_inode, int idx)
528{
529 struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
530 if (tty)
531 tty = tty->link;
532 return tty;
533}
534
535/**
536 * pts_unix98_lookup - find a pty slave
537 * @driver: pts driver
538 * @idx: tty index
539 *
540 * Look up a pty master device. Called under the tty_mutex for now.
541 * This provides our locking.
542 */
543
544static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
545 struct inode *pts_inode, int idx)
546{
547 struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
548 /* Master must be open before slave */
549 if (!tty)
550 return ERR_PTR(-EIO);
551 return tty;
552}
553
554static void pty_unix98_shutdown(struct tty_struct *tty)
555{
556 tty_driver_remove_tty(tty->driver, tty);
557 /* We have our own method as we don't use the tty index */
558 kfree(tty->termios);
559}
560
561/* We have no need to install and remove our tty objects as devpts does all
562 the work for us */
563
564static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
565{
566 struct tty_struct *o_tty;
567 int idx = tty->index;
568
569 o_tty = alloc_tty_struct();
570 if (!o_tty)
571 return -ENOMEM;
572 if (!try_module_get(driver->other->owner)) {
573 /* This cannot in fact currently happen */
574 goto err_free_tty;
575 }
576 initialize_tty_struct(o_tty, driver->other, idx);
577
578 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
579 if (tty->termios == NULL)
580 goto err_free_mem;
581 *tty->termios = driver->init_termios;
582 tty->termios_locked = tty->termios + 1;
583
584 o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
585 if (o_tty->termios == NULL)
586 goto err_free_mem;
587 *o_tty->termios = driver->other->init_termios;
588 o_tty->termios_locked = o_tty->termios + 1;
589
590 tty_driver_kref_get(driver->other);
591 if (driver->subtype == PTY_TYPE_MASTER)
592 o_tty->count++;
593 /* Establish the links in both directions */
594 tty->link = o_tty;
595 o_tty->link = tty;
596 /*
597 * All structures have been allocated, so now we install them.
598 * Failures after this point use release_tty to clean up, so
599 * there's no need to null out the local pointers.
600 */
601 tty_driver_kref_get(driver);
602 tty->count++;
603 pty_inc_count(); /* tty */
604 pty_inc_count(); /* tty->link */
605 return 0;
606err_free_mem:
607 deinitialize_tty_struct(o_tty);
608 kfree(o_tty->termios);
609 kfree(tty->termios);
610 module_put(o_tty->driver->owner);
611err_free_tty:
612 free_tty_struct(o_tty);
613 return -ENOMEM;
614}
615
616static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
617{
618 pty_dec_count();
619}
620
621static const struct tty_operations ptm_unix98_ops = {
622 .lookup = ptm_unix98_lookup,
623 .install = pty_unix98_install,
624 .remove = pty_unix98_remove,
625 .open = pty_open,
626 .close = pty_close,
627 .write = pty_write,
628 .write_room = pty_write_room,
629 .flush_buffer = pty_flush_buffer,
630 .chars_in_buffer = pty_chars_in_buffer,
631 .unthrottle = pty_unthrottle,
632 .set_termios = pty_set_termios,
633 .ioctl = pty_unix98_ioctl,
634 .shutdown = pty_unix98_shutdown,
635 .resize = pty_resize
636};
637
638static const struct tty_operations pty_unix98_ops = {
639 .lookup = pts_unix98_lookup,
640 .install = pty_unix98_install,
641 .remove = pty_unix98_remove,
642 .open = pty_open,
643 .close = pty_close,
644 .write = pty_write,
645 .write_room = pty_write_room,
646 .flush_buffer = pty_flush_buffer,
647 .chars_in_buffer = pty_chars_in_buffer,
648 .unthrottle = pty_unthrottle,
649 .set_termios = pty_set_termios,
650 .shutdown = pty_unix98_shutdown
651};
652
653/**
654 * ptmx_open - open a unix 98 pty master
655 * @inode: inode of device file
656 * @filp: file pointer to tty
657 *
658 * Allocate a unix98 pty master device from the ptmx driver.
659 *
660 * Locking: tty_mutex protects the init_dev work. tty->count should
661 * protect the rest.
662 * allocated_ptys_lock handles the list of free pty numbers
663 */
664
665static int ptmx_open(struct inode *inode, struct file *filp)
666{
667 struct tty_struct *tty;
668 int retval;
669 int index;
670
671 nonseekable_open(inode, filp);
672
673 /* find a device that is not in use. */
674 tty_lock();
675 index = devpts_new_index(inode);
676 tty_unlock();
677 if (index < 0)
678 return index;
679
680 mutex_lock(&tty_mutex);
681 tty_lock();
682 tty = tty_init_dev(ptm_driver, index, 1);
683 mutex_unlock(&tty_mutex);
684
685 if (IS_ERR(tty)) {
686 retval = PTR_ERR(tty);
687 goto out;
688 }
689
690 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
691
692 retval = tty_add_file(tty, filp);
693 if (retval)
694 goto out;
695
696 retval = devpts_pty_new(inode, tty->link);
697 if (retval)
698 goto out1;
699
700 retval = ptm_driver->ops->open(tty, filp);
701 if (retval)
702 goto out2;
703out1:
704 tty_unlock();
705 return retval;
706out2:
707 tty_unlock();
708 tty_release(inode, filp);
709 return retval;
710out:
711 devpts_kill_index(inode, index);
712 tty_unlock();
713 return retval;
714}
715
716static struct file_operations ptmx_fops;
717
718static void __init unix98_pty_init(void)
719{
720 ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
721 if (!ptm_driver)
722 panic("Couldn't allocate Unix98 ptm driver");
723 pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
724 if (!pts_driver)
725 panic("Couldn't allocate Unix98 pts driver");
726
727 ptm_driver->owner = THIS_MODULE;
728 ptm_driver->driver_name = "pty_master";
729 ptm_driver->name = "ptm";
730 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
731 ptm_driver->minor_start = 0;
732 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
733 ptm_driver->subtype = PTY_TYPE_MASTER;
734 ptm_driver->init_termios = tty_std_termios;
735 ptm_driver->init_termios.c_iflag = 0;
736 ptm_driver->init_termios.c_oflag = 0;
737 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
738 ptm_driver->init_termios.c_lflag = 0;
739 ptm_driver->init_termios.c_ispeed = 38400;
740 ptm_driver->init_termios.c_ospeed = 38400;
741 ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
742 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
743 ptm_driver->other = pts_driver;
744 tty_set_operations(ptm_driver, &ptm_unix98_ops);
745
746 pts_driver->owner = THIS_MODULE;
747 pts_driver->driver_name = "pty_slave";
748 pts_driver->name = "pts";
749 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
750 pts_driver->minor_start = 0;
751 pts_driver->type = TTY_DRIVER_TYPE_PTY;
752 pts_driver->subtype = PTY_TYPE_SLAVE;
753 pts_driver->init_termios = tty_std_termios;
754 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
755 pts_driver->init_termios.c_ispeed = 38400;
756 pts_driver->init_termios.c_ospeed = 38400;
757 pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
758 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
759 pts_driver->other = ptm_driver;
760 tty_set_operations(pts_driver, &pty_unix98_ops);
761
762 if (tty_register_driver(ptm_driver))
763 panic("Couldn't register Unix98 ptm driver");
764 if (tty_register_driver(pts_driver))
765 panic("Couldn't register Unix98 pts driver");
766
767 register_sysctl_table(pty_root_table);
768
769 /* Now create the /dev/ptmx special device */
770 tty_default_fops(&ptmx_fops);
771 ptmx_fops.open = ptmx_open;
772
773 cdev_init(&ptmx_cdev, &ptmx_fops);
774 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
775 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
776 panic("Couldn't register /dev/ptmx driver\n");
777 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
778}
779
780#else
781static inline void unix98_pty_init(void) { }
782#endif
783
784static int __init pty_init(void)
785{
786 legacy_pty_init();
787 unix98_pty_init();
788 return 0;
789}
790module_init(pty_init);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 *
5 * Added support for a Unix98-style ptmx device.
6 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
7 *
8 */
9
10#include <linux/module.h>
11#include <linux/errno.h>
12#include <linux/interrupt.h>
13#include <linux/tty.h>
14#include <linux/tty_flip.h>
15#include <linux/fcntl.h>
16#include <linux/sched/signal.h>
17#include <linux/string.h>
18#include <linux/major.h>
19#include <linux/mm.h>
20#include <linux/init.h>
21#include <linux/device.h>
22#include <linux/uaccess.h>
23#include <linux/bitops.h>
24#include <linux/devpts_fs.h>
25#include <linux/slab.h>
26#include <linux/mutex.h>
27#include <linux/poll.h>
28#include <linux/mount.h>
29#include <linux/file.h>
30#include <linux/ioctl.h>
31#include <linux/compat.h>
32#include "tty.h"
33
34#undef TTY_DEBUG_HANGUP
35#ifdef TTY_DEBUG_HANGUP
36# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
37#else
38# define tty_debug_hangup(tty, f, args...) do {} while (0)
39#endif
40
41#ifdef CONFIG_UNIX98_PTYS
42static struct tty_driver *ptm_driver;
43static struct tty_driver *pts_driver;
44static DEFINE_MUTEX(devpts_mutex);
45#endif
46
47static void pty_close(struct tty_struct *tty, struct file *filp)
48{
49 if (tty->driver->subtype == PTY_TYPE_MASTER)
50 WARN_ON(tty->count > 1);
51 else {
52 if (tty_io_error(tty))
53 return;
54 if (tty->count > 2)
55 return;
56 }
57 set_bit(TTY_IO_ERROR, &tty->flags);
58 wake_up_interruptible(&tty->read_wait);
59 wake_up_interruptible(&tty->write_wait);
60 spin_lock_irq(&tty->ctrl.lock);
61 tty->ctrl.packet = false;
62 spin_unlock_irq(&tty->ctrl.lock);
63 /* Review - krefs on tty_link ?? */
64 if (!tty->link)
65 return;
66 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
67 wake_up_interruptible(&tty->link->read_wait);
68 wake_up_interruptible(&tty->link->write_wait);
69 if (tty->driver->subtype == PTY_TYPE_MASTER) {
70 set_bit(TTY_OTHER_CLOSED, &tty->flags);
71#ifdef CONFIG_UNIX98_PTYS
72 if (tty->driver == ptm_driver) {
73 mutex_lock(&devpts_mutex);
74 if (tty->link->driver_data)
75 devpts_pty_kill(tty->link->driver_data);
76 mutex_unlock(&devpts_mutex);
77 }
78#endif
79 tty_vhangup(tty->link);
80 }
81}
82
83/*
84 * The unthrottle routine is called by the line discipline to signal
85 * that it can receive more characters. For PTY's, the TTY_THROTTLED
86 * flag is always set, to force the line discipline to always call the
87 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
88 * characters in the queue. This is necessary since each time this
89 * happens, we need to wake up any sleeping processes that could be
90 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
91 * for the pty buffer to be drained.
92 */
93static void pty_unthrottle(struct tty_struct *tty)
94{
95 tty_wakeup(tty->link);
96 set_bit(TTY_THROTTLED, &tty->flags);
97}
98
99/**
100 * pty_write - write to a pty
101 * @tty: the tty we write from
102 * @buf: kernel buffer of data
103 * @c: bytes to write
104 *
105 * Our "hardware" write method. Data is coming from the ldisc which
106 * may be in a non sleeping state. We simply throw this at the other
107 * end of the link as if we were an IRQ handler receiving stuff for
108 * the other side of the pty/tty pair.
109 */
110
111static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
112{
113 struct tty_struct *to = tty->link;
114 unsigned long flags;
115
116 if (tty->flow.stopped)
117 return 0;
118
119 if (c > 0) {
120 spin_lock_irqsave(&to->port->lock, flags);
121 /* Stuff the data into the input queue of the other end */
122 c = tty_insert_flip_string(to->port, buf, c);
123 spin_unlock_irqrestore(&to->port->lock, flags);
124 /* And shovel */
125 if (c)
126 tty_flip_buffer_push(to->port);
127 }
128 return c;
129}
130
131/**
132 * pty_write_room - write space
133 * @tty: tty we are writing from
134 *
135 * Report how many bytes the ldisc can send into the queue for
136 * the other device.
137 */
138
139static unsigned int pty_write_room(struct tty_struct *tty)
140{
141 if (tty->flow.stopped)
142 return 0;
143 return tty_buffer_space_avail(tty->link->port);
144}
145
146/* Set the lock flag on a pty */
147static int pty_set_lock(struct tty_struct *tty, int __user *arg)
148{
149 int val;
150
151 if (get_user(val, arg))
152 return -EFAULT;
153 if (val)
154 set_bit(TTY_PTY_LOCK, &tty->flags);
155 else
156 clear_bit(TTY_PTY_LOCK, &tty->flags);
157 return 0;
158}
159
160static int pty_get_lock(struct tty_struct *tty, int __user *arg)
161{
162 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
163
164 return put_user(locked, arg);
165}
166
167/* Set the packet mode on a pty */
168static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
169{
170 int pktmode;
171
172 if (get_user(pktmode, arg))
173 return -EFAULT;
174
175 spin_lock_irq(&tty->ctrl.lock);
176 if (pktmode) {
177 if (!tty->ctrl.packet) {
178 tty->link->ctrl.pktstatus = 0;
179 smp_mb();
180 tty->ctrl.packet = true;
181 }
182 } else
183 tty->ctrl.packet = false;
184 spin_unlock_irq(&tty->ctrl.lock);
185
186 return 0;
187}
188
189/* Get the packet mode of a pty */
190static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
191{
192 int pktmode = tty->ctrl.packet;
193
194 return put_user(pktmode, arg);
195}
196
197/* Send a signal to the slave */
198static int pty_signal(struct tty_struct *tty, int sig)
199{
200 struct pid *pgrp;
201
202 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
203 return -EINVAL;
204
205 if (tty->link) {
206 pgrp = tty_get_pgrp(tty->link);
207 if (pgrp)
208 kill_pgrp(pgrp, sig, 1);
209 put_pid(pgrp);
210 }
211 return 0;
212}
213
214static void pty_flush_buffer(struct tty_struct *tty)
215{
216 struct tty_struct *to = tty->link;
217
218 if (!to)
219 return;
220
221 tty_buffer_flush(to, NULL);
222 if (to->ctrl.packet) {
223 spin_lock_irq(&tty->ctrl.lock);
224 tty->ctrl.pktstatus |= TIOCPKT_FLUSHWRITE;
225 wake_up_interruptible(&to->read_wait);
226 spin_unlock_irq(&tty->ctrl.lock);
227 }
228}
229
230static int pty_open(struct tty_struct *tty, struct file *filp)
231{
232 if (!tty || !tty->link)
233 return -ENODEV;
234
235 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
236 goto out;
237 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
238 goto out;
239 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
240 goto out;
241
242 clear_bit(TTY_IO_ERROR, &tty->flags);
243 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
244 set_bit(TTY_THROTTLED, &tty->flags);
245 return 0;
246
247out:
248 set_bit(TTY_IO_ERROR, &tty->flags);
249 return -EIO;
250}
251
252static void pty_set_termios(struct tty_struct *tty,
253 struct ktermios *old_termios)
254{
255 /* See if packet mode change of state. */
256 if (tty->link && tty->link->ctrl.packet) {
257 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
258 int old_flow = ((old_termios->c_iflag & IXON) &&
259 (old_termios->c_cc[VSTOP] == '\023') &&
260 (old_termios->c_cc[VSTART] == '\021'));
261 int new_flow = (I_IXON(tty) &&
262 STOP_CHAR(tty) == '\023' &&
263 START_CHAR(tty) == '\021');
264 if ((old_flow != new_flow) || extproc) {
265 spin_lock_irq(&tty->ctrl.lock);
266 if (old_flow != new_flow) {
267 tty->ctrl.pktstatus &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
268 if (new_flow)
269 tty->ctrl.pktstatus |= TIOCPKT_DOSTOP;
270 else
271 tty->ctrl.pktstatus |= TIOCPKT_NOSTOP;
272 }
273 if (extproc)
274 tty->ctrl.pktstatus |= TIOCPKT_IOCTL;
275 spin_unlock_irq(&tty->ctrl.lock);
276 wake_up_interruptible(&tty->link->read_wait);
277 }
278 }
279
280 tty->termios.c_cflag &= ~(CSIZE | PARENB);
281 tty->termios.c_cflag |= (CS8 | CREAD);
282}
283
284/**
285 * pty_resize - resize event
286 * @tty: tty being resized
287 * @ws: window size being set.
288 *
289 * Update the termios variables and send the necessary signals to
290 * peform a terminal resize correctly
291 */
292
293static int pty_resize(struct tty_struct *tty, struct winsize *ws)
294{
295 struct pid *pgrp, *rpgrp;
296 struct tty_struct *pty = tty->link;
297
298 /* For a PTY we need to lock the tty side */
299 mutex_lock(&tty->winsize_mutex);
300 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
301 goto done;
302
303 /* Signal the foreground process group of both ptys */
304 pgrp = tty_get_pgrp(tty);
305 rpgrp = tty_get_pgrp(pty);
306
307 if (pgrp)
308 kill_pgrp(pgrp, SIGWINCH, 1);
309 if (rpgrp != pgrp && rpgrp)
310 kill_pgrp(rpgrp, SIGWINCH, 1);
311
312 put_pid(pgrp);
313 put_pid(rpgrp);
314
315 tty->winsize = *ws;
316 pty->winsize = *ws; /* Never used so will go away soon */
317done:
318 mutex_unlock(&tty->winsize_mutex);
319 return 0;
320}
321
322/**
323 * pty_start - start() handler
324 * pty_stop - stop() handler
325 * @tty: tty being flow-controlled
326 *
327 * Propagates the TIOCPKT status to the master pty.
328 *
329 * NB: only the master pty can be in packet mode so only the slave
330 * needs start()/stop() handlers
331 */
332static void pty_start(struct tty_struct *tty)
333{
334 unsigned long flags;
335
336 if (tty->link && tty->link->ctrl.packet) {
337 spin_lock_irqsave(&tty->ctrl.lock, flags);
338 tty->ctrl.pktstatus &= ~TIOCPKT_STOP;
339 tty->ctrl.pktstatus |= TIOCPKT_START;
340 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
341 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
342 }
343}
344
345static void pty_stop(struct tty_struct *tty)
346{
347 unsigned long flags;
348
349 if (tty->link && tty->link->ctrl.packet) {
350 spin_lock_irqsave(&tty->ctrl.lock, flags);
351 tty->ctrl.pktstatus &= ~TIOCPKT_START;
352 tty->ctrl.pktstatus |= TIOCPKT_STOP;
353 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
354 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
355 }
356}
357
358/**
359 * pty_common_install - set up the pty pair
360 * @driver: the pty driver
361 * @tty: the tty being instantiated
362 * @legacy: true if this is BSD style
363 *
364 * Perform the initial set up for the tty/pty pair. Called from the
365 * tty layer when the port is first opened.
366 *
367 * Locking: the caller must hold the tty_mutex
368 */
369static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
370 bool legacy)
371{
372 struct tty_struct *o_tty;
373 struct tty_port *ports[2];
374 int idx = tty->index;
375 int retval = -ENOMEM;
376
377 /* Opening the slave first has always returned -EIO */
378 if (driver->subtype != PTY_TYPE_MASTER)
379 return -EIO;
380
381 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
382 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
383 if (!ports[0] || !ports[1])
384 goto err;
385 if (!try_module_get(driver->other->owner)) {
386 /* This cannot in fact currently happen */
387 goto err;
388 }
389 o_tty = alloc_tty_struct(driver->other, idx);
390 if (!o_tty)
391 goto err_put_module;
392
393 tty_set_lock_subclass(o_tty);
394 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
395
396 if (legacy) {
397 /* We always use new tty termios data so we can do this
398 the easy way .. */
399 tty_init_termios(tty);
400 tty_init_termios(o_tty);
401
402 driver->other->ttys[idx] = o_tty;
403 driver->ttys[idx] = tty;
404 } else {
405 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
406 tty->termios = driver->init_termios;
407 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
408 o_tty->termios = driver->other->init_termios;
409 }
410
411 /*
412 * Everything allocated ... set up the o_tty structure.
413 */
414 tty_driver_kref_get(driver->other);
415 /* Establish the links in both directions */
416 tty->link = o_tty;
417 o_tty->link = tty;
418 tty_port_init(ports[0]);
419 tty_port_init(ports[1]);
420 tty_buffer_set_limit(ports[0], 8192);
421 tty_buffer_set_limit(ports[1], 8192);
422 o_tty->port = ports[0];
423 tty->port = ports[1];
424 o_tty->port->itty = o_tty;
425
426 tty_buffer_set_lock_subclass(o_tty->port);
427
428 tty_driver_kref_get(driver);
429 tty->count++;
430 o_tty->count++;
431 return 0;
432
433err_put_module:
434 module_put(driver->other->owner);
435err:
436 kfree(ports[0]);
437 kfree(ports[1]);
438 return retval;
439}
440
441static void pty_cleanup(struct tty_struct *tty)
442{
443 tty_port_put(tty->port);
444}
445
446/* Traditional BSD devices */
447#ifdef CONFIG_LEGACY_PTYS
448
449static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
450{
451 return pty_common_install(driver, tty, true);
452}
453
454static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
455{
456 struct tty_struct *pair = tty->link;
457
458 driver->ttys[tty->index] = NULL;
459 if (pair)
460 pair->driver->ttys[pair->index] = NULL;
461}
462
463static int pty_bsd_ioctl(struct tty_struct *tty,
464 unsigned int cmd, unsigned long arg)
465{
466 switch (cmd) {
467 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
468 return pty_set_lock(tty, (int __user *) arg);
469 case TIOCGPTLCK: /* Get PT Lock status */
470 return pty_get_lock(tty, (int __user *)arg);
471 case TIOCPKT: /* Set PT packet mode */
472 return pty_set_pktmode(tty, (int __user *)arg);
473 case TIOCGPKT: /* Get PT packet mode */
474 return pty_get_pktmode(tty, (int __user *)arg);
475 case TIOCSIG: /* Send signal to other side of pty */
476 return pty_signal(tty, (int) arg);
477 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
478 return -EINVAL;
479 }
480 return -ENOIOCTLCMD;
481}
482
483#ifdef CONFIG_COMPAT
484static long pty_bsd_compat_ioctl(struct tty_struct *tty,
485 unsigned int cmd, unsigned long arg)
486{
487 /*
488 * PTY ioctls don't require any special translation between 32-bit and
489 * 64-bit userspace, they are already compatible.
490 */
491 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
492}
493#else
494#define pty_bsd_compat_ioctl NULL
495#endif
496
497static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
498/*
499 * not really modular, but the easiest way to keep compat with existing
500 * bootargs behaviour is to continue using module_param here.
501 */
502module_param(legacy_count, int, 0);
503
504/*
505 * The master side of a pty can do TIOCSPTLCK and thus
506 * has pty_bsd_ioctl.
507 */
508static const struct tty_operations master_pty_ops_bsd = {
509 .install = pty_install,
510 .open = pty_open,
511 .close = pty_close,
512 .write = pty_write,
513 .write_room = pty_write_room,
514 .flush_buffer = pty_flush_buffer,
515 .unthrottle = pty_unthrottle,
516 .ioctl = pty_bsd_ioctl,
517 .compat_ioctl = pty_bsd_compat_ioctl,
518 .cleanup = pty_cleanup,
519 .resize = pty_resize,
520 .remove = pty_remove
521};
522
523static const struct tty_operations slave_pty_ops_bsd = {
524 .install = pty_install,
525 .open = pty_open,
526 .close = pty_close,
527 .write = pty_write,
528 .write_room = pty_write_room,
529 .flush_buffer = pty_flush_buffer,
530 .unthrottle = pty_unthrottle,
531 .set_termios = pty_set_termios,
532 .cleanup = pty_cleanup,
533 .resize = pty_resize,
534 .start = pty_start,
535 .stop = pty_stop,
536 .remove = pty_remove
537};
538
539static void __init legacy_pty_init(void)
540{
541 struct tty_driver *pty_driver, *pty_slave_driver;
542
543 if (legacy_count <= 0)
544 return;
545
546 pty_driver = tty_alloc_driver(legacy_count,
547 TTY_DRIVER_RESET_TERMIOS |
548 TTY_DRIVER_REAL_RAW |
549 TTY_DRIVER_DYNAMIC_ALLOC);
550 if (IS_ERR(pty_driver))
551 panic("Couldn't allocate pty driver");
552
553 pty_slave_driver = tty_alloc_driver(legacy_count,
554 TTY_DRIVER_RESET_TERMIOS |
555 TTY_DRIVER_REAL_RAW |
556 TTY_DRIVER_DYNAMIC_ALLOC);
557 if (IS_ERR(pty_slave_driver))
558 panic("Couldn't allocate pty slave driver");
559
560 pty_driver->driver_name = "pty_master";
561 pty_driver->name = "pty";
562 pty_driver->major = PTY_MASTER_MAJOR;
563 pty_driver->minor_start = 0;
564 pty_driver->type = TTY_DRIVER_TYPE_PTY;
565 pty_driver->subtype = PTY_TYPE_MASTER;
566 pty_driver->init_termios = tty_std_termios;
567 pty_driver->init_termios.c_iflag = 0;
568 pty_driver->init_termios.c_oflag = 0;
569 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
570 pty_driver->init_termios.c_lflag = 0;
571 pty_driver->init_termios.c_ispeed = 38400;
572 pty_driver->init_termios.c_ospeed = 38400;
573 pty_driver->other = pty_slave_driver;
574 tty_set_operations(pty_driver, &master_pty_ops_bsd);
575
576 pty_slave_driver->driver_name = "pty_slave";
577 pty_slave_driver->name = "ttyp";
578 pty_slave_driver->major = PTY_SLAVE_MAJOR;
579 pty_slave_driver->minor_start = 0;
580 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
581 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
582 pty_slave_driver->init_termios = tty_std_termios;
583 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
584 pty_slave_driver->init_termios.c_ispeed = 38400;
585 pty_slave_driver->init_termios.c_ospeed = 38400;
586 pty_slave_driver->other = pty_driver;
587 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
588
589 if (tty_register_driver(pty_driver))
590 panic("Couldn't register pty driver");
591 if (tty_register_driver(pty_slave_driver))
592 panic("Couldn't register pty slave driver");
593}
594#else
595static inline void legacy_pty_init(void) { }
596#endif
597
598/* Unix98 devices */
599#ifdef CONFIG_UNIX98_PTYS
600static struct cdev ptmx_cdev;
601
602/**
603 * ptm_open_peer - open the peer of a pty
604 * @master: the open struct file of the ptmx device node
605 * @tty: the master of the pty being opened
606 * @flags: the flags for open
607 *
608 * Provide a race free way for userspace to open the slave end of a pty
609 * (where they have the master fd and cannot access or trust the mount
610 * namespace /dev/pts was mounted inside).
611 */
612int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
613{
614 int fd;
615 struct file *filp;
616 int retval = -EINVAL;
617 struct path path;
618
619 if (tty->driver != ptm_driver)
620 return -EIO;
621
622 fd = get_unused_fd_flags(flags);
623 if (fd < 0) {
624 retval = fd;
625 goto err;
626 }
627
628 /* Compute the slave's path */
629 path.mnt = devpts_mntget(master, tty->driver_data);
630 if (IS_ERR(path.mnt)) {
631 retval = PTR_ERR(path.mnt);
632 goto err_put;
633 }
634 path.dentry = tty->link->driver_data;
635
636 filp = dentry_open(&path, flags, current_cred());
637 mntput(path.mnt);
638 if (IS_ERR(filp)) {
639 retval = PTR_ERR(filp);
640 goto err_put;
641 }
642
643 fd_install(fd, filp);
644 return fd;
645
646err_put:
647 put_unused_fd(fd);
648err:
649 return retval;
650}
651
652static int pty_unix98_ioctl(struct tty_struct *tty,
653 unsigned int cmd, unsigned long arg)
654{
655 switch (cmd) {
656 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
657 return pty_set_lock(tty, (int __user *)arg);
658 case TIOCGPTLCK: /* Get PT Lock status */
659 return pty_get_lock(tty, (int __user *)arg);
660 case TIOCPKT: /* Set PT packet mode */
661 return pty_set_pktmode(tty, (int __user *)arg);
662 case TIOCGPKT: /* Get PT packet mode */
663 return pty_get_pktmode(tty, (int __user *)arg);
664 case TIOCGPTN: /* Get PT Number */
665 return put_user(tty->index, (unsigned int __user *)arg);
666 case TIOCSIG: /* Send signal to other side of pty */
667 return pty_signal(tty, (int) arg);
668 }
669
670 return -ENOIOCTLCMD;
671}
672
673#ifdef CONFIG_COMPAT
674static long pty_unix98_compat_ioctl(struct tty_struct *tty,
675 unsigned int cmd, unsigned long arg)
676{
677 /*
678 * PTY ioctls don't require any special translation between 32-bit and
679 * 64-bit userspace, they are already compatible.
680 */
681 return pty_unix98_ioctl(tty, cmd,
682 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg));
683}
684#else
685#define pty_unix98_compat_ioctl NULL
686#endif
687
688/**
689 * ptm_unix98_lookup - find a pty master
690 * @driver: ptm driver
691 * @file: unused
692 * @idx: tty index
693 *
694 * Look up a pty master device. Called under the tty_mutex for now.
695 * This provides our locking.
696 */
697
698static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
699 struct file *file, int idx)
700{
701 /* Master must be open via /dev/ptmx */
702 return ERR_PTR(-EIO);
703}
704
705/**
706 * pts_unix98_lookup - find a pty slave
707 * @driver: pts driver
708 * @file: file pointer to tty
709 * @idx: tty index
710 *
711 * Look up a pty master device. Called under the tty_mutex for now.
712 * This provides our locking for the tty pointer.
713 */
714
715static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
716 struct file *file, int idx)
717{
718 struct tty_struct *tty;
719
720 mutex_lock(&devpts_mutex);
721 tty = devpts_get_priv(file->f_path.dentry);
722 mutex_unlock(&devpts_mutex);
723 /* Master must be open before slave */
724 if (!tty)
725 return ERR_PTR(-EIO);
726 return tty;
727}
728
729static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
730{
731 return pty_common_install(driver, tty, false);
732}
733
734/* this is called once with whichever end is closed last */
735static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
736{
737 struct pts_fs_info *fsi;
738
739 if (tty->driver->subtype == PTY_TYPE_MASTER)
740 fsi = tty->driver_data;
741 else
742 fsi = tty->link->driver_data;
743
744 if (fsi) {
745 devpts_kill_index(fsi, tty->index);
746 devpts_release(fsi);
747 }
748}
749
750static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
751{
752 seq_printf(m, "tty-index:\t%d\n", tty->index);
753}
754
755static const struct tty_operations ptm_unix98_ops = {
756 .lookup = ptm_unix98_lookup,
757 .install = pty_unix98_install,
758 .remove = pty_unix98_remove,
759 .open = pty_open,
760 .close = pty_close,
761 .write = pty_write,
762 .write_room = pty_write_room,
763 .flush_buffer = pty_flush_buffer,
764 .unthrottle = pty_unthrottle,
765 .ioctl = pty_unix98_ioctl,
766 .compat_ioctl = pty_unix98_compat_ioctl,
767 .resize = pty_resize,
768 .cleanup = pty_cleanup,
769 .show_fdinfo = pty_show_fdinfo,
770};
771
772static const struct tty_operations pty_unix98_ops = {
773 .lookup = pts_unix98_lookup,
774 .install = pty_unix98_install,
775 .remove = pty_unix98_remove,
776 .open = pty_open,
777 .close = pty_close,
778 .write = pty_write,
779 .write_room = pty_write_room,
780 .flush_buffer = pty_flush_buffer,
781 .unthrottle = pty_unthrottle,
782 .set_termios = pty_set_termios,
783 .start = pty_start,
784 .stop = pty_stop,
785 .cleanup = pty_cleanup,
786};
787
788/**
789 * ptmx_open - open a unix 98 pty master
790 * @inode: inode of device file
791 * @filp: file pointer to tty
792 *
793 * Allocate a unix98 pty master device from the ptmx driver.
794 *
795 * Locking: tty_mutex protects the init_dev work. tty->count should
796 * protect the rest.
797 * allocated_ptys_lock handles the list of free pty numbers
798 */
799
800static int ptmx_open(struct inode *inode, struct file *filp)
801{
802 struct pts_fs_info *fsi;
803 struct tty_struct *tty;
804 struct dentry *dentry;
805 int retval;
806 int index;
807
808 nonseekable_open(inode, filp);
809
810 /* We refuse fsnotify events on ptmx, since it's a shared resource */
811 filp->f_mode |= FMODE_NONOTIFY;
812
813 retval = tty_alloc_file(filp);
814 if (retval)
815 return retval;
816
817 fsi = devpts_acquire(filp);
818 if (IS_ERR(fsi)) {
819 retval = PTR_ERR(fsi);
820 goto out_free_file;
821 }
822
823 /* find a device that is not in use. */
824 mutex_lock(&devpts_mutex);
825 index = devpts_new_index(fsi);
826 mutex_unlock(&devpts_mutex);
827
828 retval = index;
829 if (index < 0)
830 goto out_put_fsi;
831
832
833 mutex_lock(&tty_mutex);
834 tty = tty_init_dev(ptm_driver, index);
835 /* The tty returned here is locked so we can safely
836 drop the mutex */
837 mutex_unlock(&tty_mutex);
838
839 retval = PTR_ERR(tty);
840 if (IS_ERR(tty))
841 goto out;
842
843 /*
844 * From here on out, the tty is "live", and the index and
845 * fsi will be killed/put by the tty_release()
846 */
847 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
848 tty->driver_data = fsi;
849
850 tty_add_file(tty, filp);
851
852 dentry = devpts_pty_new(fsi, index, tty->link);
853 if (IS_ERR(dentry)) {
854 retval = PTR_ERR(dentry);
855 goto err_release;
856 }
857 tty->link->driver_data = dentry;
858
859 retval = ptm_driver->ops->open(tty, filp);
860 if (retval)
861 goto err_release;
862
863 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
864
865 tty_unlock(tty);
866 return 0;
867err_release:
868 tty_unlock(tty);
869 // This will also put-ref the fsi
870 tty_release(inode, filp);
871 return retval;
872out:
873 devpts_kill_index(fsi, index);
874out_put_fsi:
875 devpts_release(fsi);
876out_free_file:
877 tty_free_file(filp);
878 return retval;
879}
880
881static struct file_operations ptmx_fops __ro_after_init;
882
883static void __init unix98_pty_init(void)
884{
885 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
886 TTY_DRIVER_RESET_TERMIOS |
887 TTY_DRIVER_REAL_RAW |
888 TTY_DRIVER_DYNAMIC_DEV |
889 TTY_DRIVER_DEVPTS_MEM |
890 TTY_DRIVER_DYNAMIC_ALLOC);
891 if (IS_ERR(ptm_driver))
892 panic("Couldn't allocate Unix98 ptm driver");
893 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
894 TTY_DRIVER_RESET_TERMIOS |
895 TTY_DRIVER_REAL_RAW |
896 TTY_DRIVER_DYNAMIC_DEV |
897 TTY_DRIVER_DEVPTS_MEM |
898 TTY_DRIVER_DYNAMIC_ALLOC);
899 if (IS_ERR(pts_driver))
900 panic("Couldn't allocate Unix98 pts driver");
901
902 ptm_driver->driver_name = "pty_master";
903 ptm_driver->name = "ptm";
904 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
905 ptm_driver->minor_start = 0;
906 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
907 ptm_driver->subtype = PTY_TYPE_MASTER;
908 ptm_driver->init_termios = tty_std_termios;
909 ptm_driver->init_termios.c_iflag = 0;
910 ptm_driver->init_termios.c_oflag = 0;
911 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
912 ptm_driver->init_termios.c_lflag = 0;
913 ptm_driver->init_termios.c_ispeed = 38400;
914 ptm_driver->init_termios.c_ospeed = 38400;
915 ptm_driver->other = pts_driver;
916 tty_set_operations(ptm_driver, &ptm_unix98_ops);
917
918 pts_driver->driver_name = "pty_slave";
919 pts_driver->name = "pts";
920 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
921 pts_driver->minor_start = 0;
922 pts_driver->type = TTY_DRIVER_TYPE_PTY;
923 pts_driver->subtype = PTY_TYPE_SLAVE;
924 pts_driver->init_termios = tty_std_termios;
925 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
926 pts_driver->init_termios.c_ispeed = 38400;
927 pts_driver->init_termios.c_ospeed = 38400;
928 pts_driver->other = ptm_driver;
929 tty_set_operations(pts_driver, &pty_unix98_ops);
930
931 if (tty_register_driver(ptm_driver))
932 panic("Couldn't register Unix98 ptm driver");
933 if (tty_register_driver(pts_driver))
934 panic("Couldn't register Unix98 pts driver");
935
936 /* Now create the /dev/ptmx special device */
937 tty_default_fops(&ptmx_fops);
938 ptmx_fops.open = ptmx_open;
939
940 cdev_init(&ptmx_cdev, &ptmx_fops);
941 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
942 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
943 panic("Couldn't register /dev/ptmx driver");
944 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
945}
946
947#else
948static inline void unix98_pty_init(void) { }
949#endif
950
951static int __init pty_init(void)
952{
953 legacy_pty_init();
954 unix98_pty_init();
955 return 0;
956}
957device_initcall(pty_init);