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