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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);
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);