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