1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 *
5 * Added support for a Unix98-style ptmx device.
6 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
7 *
8 */
9
10#include <linux/module.h>
11#include <linux/errno.h>
12#include <linux/interrupt.h>
13#include <linux/tty.h>
14#include <linux/tty_flip.h>
15#include <linux/fcntl.h>
16#include <linux/sched/signal.h>
17#include <linux/string.h>
18#include <linux/major.h>
19#include <linux/mm.h>
20#include <linux/init.h>
21#include <linux/device.h>
22#include <linux/uaccess.h>
23#include <linux/bitops.h>
24#include <linux/devpts_fs.h>
25#include <linux/slab.h>
26#include <linux/mutex.h>
27#include <linux/poll.h>
28#include <linux/mount.h>
29#include <linux/file.h>
30#include <linux/ioctl.h>
31#include <linux/compat.h>
32
33#undef TTY_DEBUG_HANGUP
34#ifdef TTY_DEBUG_HANGUP
35# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
36#else
37# define tty_debug_hangup(tty, f, args...) do {} while (0)
38#endif
39
40#ifdef CONFIG_UNIX98_PTYS
41static struct tty_driver *ptm_driver;
42static struct tty_driver *pts_driver;
43static DEFINE_MUTEX(devpts_mutex);
44#endif
45
46static void pty_close(struct tty_struct *tty, struct file *filp)
47{
48 BUG_ON(!tty);
49 if (tty->driver->subtype == PTY_TYPE_MASTER)
50 WARN_ON(tty->count > 1);
51 else {
52 if (tty_io_error(tty))
53 return;
54 if (tty->count > 2)
55 return;
56 }
57 set_bit(TTY_IO_ERROR, &tty->flags);
58 wake_up_interruptible(&tty->read_wait);
59 wake_up_interruptible(&tty->write_wait);
60 spin_lock_irq(&tty->ctrl_lock);
61 tty->packet = 0;
62 spin_unlock_irq(&tty->ctrl_lock);
63 /* Review - krefs on tty_link ?? */
64 if (!tty->link)
65 return;
66 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
67 wake_up_interruptible(&tty->link->read_wait);
68 wake_up_interruptible(&tty->link->write_wait);
69 if (tty->driver->subtype == PTY_TYPE_MASTER) {
70 set_bit(TTY_OTHER_CLOSED, &tty->flags);
71#ifdef CONFIG_UNIX98_PTYS
72 if (tty->driver == ptm_driver) {
73 mutex_lock(&devpts_mutex);
74 if (tty->link->driver_data)
75 devpts_pty_kill(tty->link->driver_data);
76 mutex_unlock(&devpts_mutex);
77 }
78#endif
79 tty_vhangup(tty->link);
80 }
81}
82
83/*
84 * The unthrottle routine is called by the line discipline to signal
85 * that it can receive more characters. For PTY's, the TTY_THROTTLED
86 * flag is always set, to force the line discipline to always call the
87 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
88 * characters in the queue. This is necessary since each time this
89 * happens, we need to wake up any sleeping processes that could be
90 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
91 * for the pty buffer to be drained.
92 */
93static void pty_unthrottle(struct tty_struct *tty)
94{
95 tty_wakeup(tty->link);
96 set_bit(TTY_THROTTLED, &tty->flags);
97}
98
99/**
100 * pty_write - write to a pty
101 * @tty: the tty we write from
102 * @buf: kernel buffer of data
103 * @count: bytes to write
104 *
105 * Our "hardware" write method. Data is coming from the ldisc which
106 * may be in a non sleeping state. We simply throw this at the other
107 * end of the link as if we were an IRQ handler receiving stuff for
108 * the other side of the pty/tty pair.
109 */
110
111static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
112{
113 struct tty_struct *to = tty->link;
114 unsigned long flags;
115
116 if (tty->stopped)
117 return 0;
118
119 if (c > 0) {
120 spin_lock_irqsave(&to->port->lock, flags);
121 /* Stuff the data into the input queue of the other end */
122 c = tty_insert_flip_string(to->port, buf, c);
123 /* And shovel */
124 if (c)
125 tty_flip_buffer_push(to->port);
126 spin_unlock_irqrestore(&to->port->lock, flags);
127 }
128 return c;
129}
130
131/**
132 * pty_write_room - write space
133 * @tty: tty we are writing from
134 *
135 * Report how many bytes the ldisc can send into the queue for
136 * the other device.
137 */
138
139static int pty_write_room(struct tty_struct *tty)
140{
141 if (tty->stopped)
142 return 0;
143 return tty_buffer_space_avail(tty->link->port);
144}
145
146/**
147 * pty_chars_in_buffer - characters currently in our tx queue
148 * @tty: our tty
149 *
150 * Report how much we have in the transmit queue. As everything is
151 * instantly at the other end this is easy to implement.
152 */
153
154static int pty_chars_in_buffer(struct tty_struct *tty)
155{
156 return 0;
157}
158
159/* Set the lock flag on a pty */
160static int pty_set_lock(struct tty_struct *tty, int __user *arg)
161{
162 int val;
163 if (get_user(val, arg))
164 return -EFAULT;
165 if (val)
166 set_bit(TTY_PTY_LOCK, &tty->flags);
167 else
168 clear_bit(TTY_PTY_LOCK, &tty->flags);
169 return 0;
170}
171
172static int pty_get_lock(struct tty_struct *tty, int __user *arg)
173{
174 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
175 return put_user(locked, arg);
176}
177
178/* Set the packet mode on a pty */
179static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
180{
181 int pktmode;
182
183 if (get_user(pktmode, arg))
184 return -EFAULT;
185
186 spin_lock_irq(&tty->ctrl_lock);
187 if (pktmode) {
188 if (!tty->packet) {
189 tty->link->ctrl_status = 0;
190 smp_mb();
191 tty->packet = 1;
192 }
193 } else
194 tty->packet = 0;
195 spin_unlock_irq(&tty->ctrl_lock);
196
197 return 0;
198}
199
200/* Get the packet mode of a pty */
201static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
202{
203 int pktmode = tty->packet;
204 return put_user(pktmode, arg);
205}
206
207/* Send a signal to the slave */
208static int pty_signal(struct tty_struct *tty, int sig)
209{
210 struct pid *pgrp;
211
212 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
213 return -EINVAL;
214
215 if (tty->link) {
216 pgrp = tty_get_pgrp(tty->link);
217 if (pgrp)
218 kill_pgrp(pgrp, sig, 1);
219 put_pid(pgrp);
220 }
221 return 0;
222}
223
224static void pty_flush_buffer(struct tty_struct *tty)
225{
226 struct tty_struct *to = tty->link;
227
228 if (!to)
229 return;
230
231 tty_buffer_flush(to, NULL);
232 if (to->packet) {
233 spin_lock_irq(&tty->ctrl_lock);
234 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
235 wake_up_interruptible(&to->read_wait);
236 spin_unlock_irq(&tty->ctrl_lock);
237 }
238}
239
240static int pty_open(struct tty_struct *tty, struct file *filp)
241{
242 if (!tty || !tty->link)
243 return -ENODEV;
244
245 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
246 goto out;
247 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
248 goto out;
249 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
250 goto out;
251
252 clear_bit(TTY_IO_ERROR, &tty->flags);
253 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
254 set_bit(TTY_THROTTLED, &tty->flags);
255 return 0;
256
257out:
258 set_bit(TTY_IO_ERROR, &tty->flags);
259 return -EIO;
260}
261
262static void pty_set_termios(struct tty_struct *tty,
263 struct ktermios *old_termios)
264{
265 /* See if packet mode change of state. */
266 if (tty->link && tty->link->packet) {
267 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
268 int old_flow = ((old_termios->c_iflag & IXON) &&
269 (old_termios->c_cc[VSTOP] == '\023') &&
270 (old_termios->c_cc[VSTART] == '\021'));
271 int new_flow = (I_IXON(tty) &&
272 STOP_CHAR(tty) == '\023' &&
273 START_CHAR(tty) == '\021');
274 if ((old_flow != new_flow) || extproc) {
275 spin_lock_irq(&tty->ctrl_lock);
276 if (old_flow != new_flow) {
277 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
278 if (new_flow)
279 tty->ctrl_status |= TIOCPKT_DOSTOP;
280 else
281 tty->ctrl_status |= TIOCPKT_NOSTOP;
282 }
283 if (extproc)
284 tty->ctrl_status |= TIOCPKT_IOCTL;
285 spin_unlock_irq(&tty->ctrl_lock);
286 wake_up_interruptible(&tty->link->read_wait);
287 }
288 }
289
290 tty->termios.c_cflag &= ~(CSIZE | PARENB);
291 tty->termios.c_cflag |= (CS8 | CREAD);
292}
293
294/**
295 * pty_do_resize - resize event
296 * @tty: tty being resized
297 * @ws: window size being set.
298 *
299 * Update the termios variables and send the necessary signals to
300 * peform a terminal resize correctly
301 */
302
303static int pty_resize(struct tty_struct *tty, struct winsize *ws)
304{
305 struct pid *pgrp, *rpgrp;
306 struct tty_struct *pty = tty->link;
307
308 /* For a PTY we need to lock the tty side */
309 mutex_lock(&tty->winsize_mutex);
310 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
311 goto done;
312
313 /* Signal the foreground process group of both ptys */
314 pgrp = tty_get_pgrp(tty);
315 rpgrp = tty_get_pgrp(pty);
316
317 if (pgrp)
318 kill_pgrp(pgrp, SIGWINCH, 1);
319 if (rpgrp != pgrp && rpgrp)
320 kill_pgrp(rpgrp, SIGWINCH, 1);
321
322 put_pid(pgrp);
323 put_pid(rpgrp);
324
325 tty->winsize = *ws;
326 pty->winsize = *ws; /* Never used so will go away soon */
327done:
328 mutex_unlock(&tty->winsize_mutex);
329 return 0;
330}
331
332/**
333 * pty_start - start() handler
334 * pty_stop - stop() handler
335 * @tty: tty being flow-controlled
336 *
337 * Propagates the TIOCPKT status to the master pty.
338 *
339 * NB: only the master pty can be in packet mode so only the slave
340 * needs start()/stop() handlers
341 */
342static void pty_start(struct tty_struct *tty)
343{
344 unsigned long flags;
345
346 if (tty->link && tty->link->packet) {
347 spin_lock_irqsave(&tty->ctrl_lock, flags);
348 tty->ctrl_status &= ~TIOCPKT_STOP;
349 tty->ctrl_status |= TIOCPKT_START;
350 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
351 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
352 }
353}
354
355static void pty_stop(struct tty_struct *tty)
356{
357 unsigned long flags;
358
359 if (tty->link && tty->link->packet) {
360 spin_lock_irqsave(&tty->ctrl_lock, flags);
361 tty->ctrl_status &= ~TIOCPKT_START;
362 tty->ctrl_status |= TIOCPKT_STOP;
363 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
364 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
365 }
366}
367
368/**
369 * pty_common_install - set up the pty pair
370 * @driver: the pty driver
371 * @tty: the tty being instantiated
372 * @legacy: true if this is BSD style
373 *
374 * Perform the initial set up for the tty/pty pair. Called from the
375 * tty layer when the port is first opened.
376 *
377 * Locking: the caller must hold the tty_mutex
378 */
379static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
380 bool legacy)
381{
382 struct tty_struct *o_tty;
383 struct tty_port *ports[2];
384 int idx = tty->index;
385 int retval = -ENOMEM;
386
387 /* Opening the slave first has always returned -EIO */
388 if (driver->subtype != PTY_TYPE_MASTER)
389 return -EIO;
390
391 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
392 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
393 if (!ports[0] || !ports[1])
394 goto err;
395 if (!try_module_get(driver->other->owner)) {
396 /* This cannot in fact currently happen */
397 goto err;
398 }
399 o_tty = alloc_tty_struct(driver->other, idx);
400 if (!o_tty)
401 goto err_put_module;
402
403 tty_set_lock_subclass(o_tty);
404 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
405
406 if (legacy) {
407 /* We always use new tty termios data so we can do this
408 the easy way .. */
409 tty_init_termios(tty);
410 tty_init_termios(o_tty);
411
412 driver->other->ttys[idx] = o_tty;
413 driver->ttys[idx] = tty;
414 } else {
415 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
416 tty->termios = driver->init_termios;
417 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
418 o_tty->termios = driver->other->init_termios;
419 }
420
421 /*
422 * Everything allocated ... set up the o_tty structure.
423 */
424 tty_driver_kref_get(driver->other);
425 /* Establish the links in both directions */
426 tty->link = o_tty;
427 o_tty->link = tty;
428 tty_port_init(ports[0]);
429 tty_port_init(ports[1]);
430 tty_buffer_set_limit(ports[0], 8192);
431 tty_buffer_set_limit(ports[1], 8192);
432 o_tty->port = ports[0];
433 tty->port = ports[1];
434 o_tty->port->itty = o_tty;
435
436 tty_buffer_set_lock_subclass(o_tty->port);
437
438 tty_driver_kref_get(driver);
439 tty->count++;
440 o_tty->count++;
441 return 0;
442
443err_put_module:
444 module_put(driver->other->owner);
445err:
446 kfree(ports[0]);
447 kfree(ports[1]);
448 return retval;
449}
450
451static void pty_cleanup(struct tty_struct *tty)
452{
453 tty_port_put(tty->port);
454}
455
456/* Traditional BSD devices */
457#ifdef CONFIG_LEGACY_PTYS
458
459static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
460{
461 return pty_common_install(driver, tty, true);
462}
463
464static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
465{
466 struct tty_struct *pair = tty->link;
467 driver->ttys[tty->index] = NULL;
468 if (pair)
469 pair->driver->ttys[pair->index] = NULL;
470}
471
472static int pty_bsd_ioctl(struct tty_struct *tty,
473 unsigned int cmd, unsigned long arg)
474{
475 switch (cmd) {
476 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
477 return pty_set_lock(tty, (int __user *) arg);
478 case TIOCGPTLCK: /* Get PT Lock status */
479 return pty_get_lock(tty, (int __user *)arg);
480 case TIOCPKT: /* Set PT packet mode */
481 return pty_set_pktmode(tty, (int __user *)arg);
482 case TIOCGPKT: /* Get PT packet mode */
483 return pty_get_pktmode(tty, (int __user *)arg);
484 case TIOCSIG: /* Send signal to other side of pty */
485 return pty_signal(tty, (int) arg);
486 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
487 return -EINVAL;
488 }
489 return -ENOIOCTLCMD;
490}
491
492#ifdef CONFIG_COMPAT
493static long pty_bsd_compat_ioctl(struct tty_struct *tty,
494 unsigned int cmd, unsigned long arg)
495{
496 /*
497 * PTY ioctls don't require any special translation between 32-bit and
498 * 64-bit userspace, they are already compatible.
499 */
500 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
501}
502#else
503#define pty_bsd_compat_ioctl NULL
504#endif
505
506static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
507/*
508 * not really modular, but the easiest way to keep compat with existing
509 * bootargs behaviour is to continue using module_param here.
510 */
511module_param(legacy_count, int, 0);
512
513/*
514 * The master side of a pty can do TIOCSPTLCK and thus
515 * has pty_bsd_ioctl.
516 */
517static const struct tty_operations master_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 .ioctl = pty_bsd_ioctl,
527 .compat_ioctl = pty_bsd_compat_ioctl,
528 .cleanup = pty_cleanup,
529 .resize = pty_resize,
530 .remove = pty_remove
531};
532
533static const struct tty_operations slave_pty_ops_bsd = {
534 .install = pty_install,
535 .open = pty_open,
536 .close = pty_close,
537 .write = pty_write,
538 .write_room = pty_write_room,
539 .flush_buffer = pty_flush_buffer,
540 .chars_in_buffer = pty_chars_in_buffer,
541 .unthrottle = pty_unthrottle,
542 .set_termios = pty_set_termios,
543 .cleanup = pty_cleanup,
544 .resize = pty_resize,
545 .start = pty_start,
546 .stop = pty_stop,
547 .remove = pty_remove
548};
549
550static void __init legacy_pty_init(void)
551{
552 struct tty_driver *pty_driver, *pty_slave_driver;
553
554 if (legacy_count <= 0)
555 return;
556
557 pty_driver = tty_alloc_driver(legacy_count,
558 TTY_DRIVER_RESET_TERMIOS |
559 TTY_DRIVER_REAL_RAW |
560 TTY_DRIVER_DYNAMIC_ALLOC);
561 if (IS_ERR(pty_driver))
562 panic("Couldn't allocate pty driver");
563
564 pty_slave_driver = tty_alloc_driver(legacy_count,
565 TTY_DRIVER_RESET_TERMIOS |
566 TTY_DRIVER_REAL_RAW |
567 TTY_DRIVER_DYNAMIC_ALLOC);
568 if (IS_ERR(pty_slave_driver))
569 panic("Couldn't allocate pty slave driver");
570
571 pty_driver->driver_name = "pty_master";
572 pty_driver->name = "pty";
573 pty_driver->major = PTY_MASTER_MAJOR;
574 pty_driver->minor_start = 0;
575 pty_driver->type = TTY_DRIVER_TYPE_PTY;
576 pty_driver->subtype = PTY_TYPE_MASTER;
577 pty_driver->init_termios = tty_std_termios;
578 pty_driver->init_termios.c_iflag = 0;
579 pty_driver->init_termios.c_oflag = 0;
580 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
581 pty_driver->init_termios.c_lflag = 0;
582 pty_driver->init_termios.c_ispeed = 38400;
583 pty_driver->init_termios.c_ospeed = 38400;
584 pty_driver->other = pty_slave_driver;
585 tty_set_operations(pty_driver, &master_pty_ops_bsd);
586
587 pty_slave_driver->driver_name = "pty_slave";
588 pty_slave_driver->name = "ttyp";
589 pty_slave_driver->major = PTY_SLAVE_MAJOR;
590 pty_slave_driver->minor_start = 0;
591 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
592 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
593 pty_slave_driver->init_termios = tty_std_termios;
594 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
595 pty_slave_driver->init_termios.c_ispeed = 38400;
596 pty_slave_driver->init_termios.c_ospeed = 38400;
597 pty_slave_driver->other = pty_driver;
598 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
599
600 if (tty_register_driver(pty_driver))
601 panic("Couldn't register pty driver");
602 if (tty_register_driver(pty_slave_driver))
603 panic("Couldn't register pty slave driver");
604}
605#else
606static inline void legacy_pty_init(void) { }
607#endif
608
609/* Unix98 devices */
610#ifdef CONFIG_UNIX98_PTYS
611static struct cdev ptmx_cdev;
612
613/**
614 * ptm_open_peer - open the peer of a pty
615 * @master: the open struct file of the ptmx device node
616 * @tty: the master of the pty being opened
617 * @flags: the flags for open
618 *
619 * Provide a race free way for userspace to open the slave end of a pty
620 * (where they have the master fd and cannot access or trust the mount
621 * namespace /dev/pts was mounted inside).
622 */
623int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
624{
625 int fd = -1;
626 struct file *filp;
627 int retval = -EINVAL;
628 struct path path;
629
630 if (tty->driver != ptm_driver)
631 return -EIO;
632
633 fd = get_unused_fd_flags(flags);
634 if (fd < 0) {
635 retval = fd;
636 goto err;
637 }
638
639 /* Compute the slave's path */
640 path.mnt = devpts_mntget(master, tty->driver_data);
641 if (IS_ERR(path.mnt)) {
642 retval = PTR_ERR(path.mnt);
643 goto err_put;
644 }
645 path.dentry = tty->link->driver_data;
646
647 filp = dentry_open(&path, flags, current_cred());
648 mntput(path.mnt);
649 if (IS_ERR(filp)) {
650 retval = PTR_ERR(filp);
651 goto err_put;
652 }
653
654 fd_install(fd, filp);
655 return fd;
656
657err_put:
658 put_unused_fd(fd);
659err:
660 return retval;
661}
662
663static int pty_unix98_ioctl(struct tty_struct *tty,
664 unsigned int cmd, unsigned long arg)
665{
666 switch (cmd) {
667 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
668 return pty_set_lock(tty, (int __user *)arg);
669 case TIOCGPTLCK: /* Get PT Lock status */
670 return pty_get_lock(tty, (int __user *)arg);
671 case TIOCPKT: /* Set PT packet mode */
672 return pty_set_pktmode(tty, (int __user *)arg);
673 case TIOCGPKT: /* Get PT packet mode */
674 return pty_get_pktmode(tty, (int __user *)arg);
675 case TIOCGPTN: /* Get PT Number */
676 return put_user(tty->index, (unsigned int __user *)arg);
677 case TIOCSIG: /* Send signal to other side of pty */
678 return pty_signal(tty, (int) arg);
679 }
680
681 return -ENOIOCTLCMD;
682}
683
684#ifdef CONFIG_COMPAT
685static long pty_unix98_compat_ioctl(struct tty_struct *tty,
686 unsigned int cmd, unsigned long arg)
687{
688 /*
689 * PTY ioctls don't require any special translation between 32-bit and
690 * 64-bit userspace, they are already compatible.
691 */
692 return pty_unix98_ioctl(tty, cmd,
693 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg));
694}
695#else
696#define pty_unix98_compat_ioctl NULL
697#endif
698
699/**
700 * ptm_unix98_lookup - find a pty master
701 * @driver: ptm driver
702 * @idx: tty index
703 *
704 * Look up a pty master device. Called under the tty_mutex for now.
705 * This provides our locking.
706 */
707
708static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
709 struct file *file, int idx)
710{
711 /* Master must be open via /dev/ptmx */
712 return ERR_PTR(-EIO);
713}
714
715/**
716 * pts_unix98_lookup - find a pty slave
717 * @driver: pts driver
718 * @idx: tty index
719 *
720 * Look up a pty master device. Called under the tty_mutex for now.
721 * This provides our locking for the tty pointer.
722 */
723
724static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
725 struct file *file, int idx)
726{
727 struct tty_struct *tty;
728
729 mutex_lock(&devpts_mutex);
730 tty = devpts_get_priv(file->f_path.dentry);
731 mutex_unlock(&devpts_mutex);
732 /* Master must be open before slave */
733 if (!tty)
734 return ERR_PTR(-EIO);
735 return tty;
736}
737
738static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
739{
740 return pty_common_install(driver, tty, false);
741}
742
743/* this is called once with whichever end is closed last */
744static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
745{
746 struct pts_fs_info *fsi;
747
748 if (tty->driver->subtype == PTY_TYPE_MASTER)
749 fsi = tty->driver_data;
750 else
751 fsi = tty->link->driver_data;
752
753 if (fsi) {
754 devpts_kill_index(fsi, tty->index);
755 devpts_release(fsi);
756 }
757}
758
759static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
760{
761 seq_printf(m, "tty-index:\t%d\n", tty->index);
762}
763
764static const struct tty_operations ptm_unix98_ops = {
765 .lookup = ptm_unix98_lookup,
766 .install = pty_unix98_install,
767 .remove = pty_unix98_remove,
768 .open = pty_open,
769 .close = pty_close,
770 .write = pty_write,
771 .write_room = pty_write_room,
772 .flush_buffer = pty_flush_buffer,
773 .chars_in_buffer = pty_chars_in_buffer,
774 .unthrottle = pty_unthrottle,
775 .ioctl = pty_unix98_ioctl,
776 .compat_ioctl = pty_unix98_compat_ioctl,
777 .resize = pty_resize,
778 .cleanup = pty_cleanup,
779 .show_fdinfo = pty_show_fdinfo,
780};
781
782static const struct tty_operations pty_unix98_ops = {
783 .lookup = pts_unix98_lookup,
784 .install = pty_unix98_install,
785 .remove = pty_unix98_remove,
786 .open = pty_open,
787 .close = pty_close,
788 .write = pty_write,
789 .write_room = pty_write_room,
790 .flush_buffer = pty_flush_buffer,
791 .chars_in_buffer = pty_chars_in_buffer,
792 .unthrottle = pty_unthrottle,
793 .set_termios = pty_set_termios,
794 .start = pty_start,
795 .stop = pty_stop,
796 .cleanup = pty_cleanup,
797};
798
799/**
800 * ptmx_open - open a unix 98 pty master
801 * @inode: inode of device file
802 * @filp: file pointer to tty
803 *
804 * Allocate a unix98 pty master device from the ptmx driver.
805 *
806 * Locking: tty_mutex protects the init_dev work. tty->count should
807 * protect the rest.
808 * allocated_ptys_lock handles the list of free pty numbers
809 */
810
811static int ptmx_open(struct inode *inode, struct file *filp)
812{
813 struct pts_fs_info *fsi;
814 struct tty_struct *tty;
815 struct dentry *dentry;
816 int retval;
817 int index;
818
819 nonseekable_open(inode, filp);
820
821 /* We refuse fsnotify events on ptmx, since it's a shared resource */
822 filp->f_mode |= FMODE_NONOTIFY;
823
824 retval = tty_alloc_file(filp);
825 if (retval)
826 return retval;
827
828 fsi = devpts_acquire(filp);
829 if (IS_ERR(fsi)) {
830 retval = PTR_ERR(fsi);
831 goto out_free_file;
832 }
833
834 /* find a device that is not in use. */
835 mutex_lock(&devpts_mutex);
836 index = devpts_new_index(fsi);
837 mutex_unlock(&devpts_mutex);
838
839 retval = index;
840 if (index < 0)
841 goto out_put_fsi;
842
843
844 mutex_lock(&tty_mutex);
845 tty = tty_init_dev(ptm_driver, index);
846 /* The tty returned here is locked so we can safely
847 drop the mutex */
848 mutex_unlock(&tty_mutex);
849
850 retval = PTR_ERR(tty);
851 if (IS_ERR(tty))
852 goto out;
853
854 /*
855 * From here on out, the tty is "live", and the index and
856 * fsi will be killed/put by the tty_release()
857 */
858 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
859 tty->driver_data = fsi;
860
861 tty_add_file(tty, filp);
862
863 dentry = devpts_pty_new(fsi, index, tty->link);
864 if (IS_ERR(dentry)) {
865 retval = PTR_ERR(dentry);
866 goto err_release;
867 }
868 tty->link->driver_data = dentry;
869
870 retval = ptm_driver->ops->open(tty, filp);
871 if (retval)
872 goto err_release;
873
874 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
875
876 tty_unlock(tty);
877 return 0;
878err_release:
879 tty_unlock(tty);
880 // This will also put-ref the fsi
881 tty_release(inode, filp);
882 return retval;
883out:
884 devpts_kill_index(fsi, index);
885out_put_fsi:
886 devpts_release(fsi);
887out_free_file:
888 tty_free_file(filp);
889 return retval;
890}
891
892static struct file_operations ptmx_fops __ro_after_init;
893
894static void __init unix98_pty_init(void)
895{
896 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
897 TTY_DRIVER_RESET_TERMIOS |
898 TTY_DRIVER_REAL_RAW |
899 TTY_DRIVER_DYNAMIC_DEV |
900 TTY_DRIVER_DEVPTS_MEM |
901 TTY_DRIVER_DYNAMIC_ALLOC);
902 if (IS_ERR(ptm_driver))
903 panic("Couldn't allocate Unix98 ptm driver");
904 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
905 TTY_DRIVER_RESET_TERMIOS |
906 TTY_DRIVER_REAL_RAW |
907 TTY_DRIVER_DYNAMIC_DEV |
908 TTY_DRIVER_DEVPTS_MEM |
909 TTY_DRIVER_DYNAMIC_ALLOC);
910 if (IS_ERR(pts_driver))
911 panic("Couldn't allocate Unix98 pts driver");
912
913 ptm_driver->driver_name = "pty_master";
914 ptm_driver->name = "ptm";
915 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
916 ptm_driver->minor_start = 0;
917 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
918 ptm_driver->subtype = PTY_TYPE_MASTER;
919 ptm_driver->init_termios = tty_std_termios;
920 ptm_driver->init_termios.c_iflag = 0;
921 ptm_driver->init_termios.c_oflag = 0;
922 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
923 ptm_driver->init_termios.c_lflag = 0;
924 ptm_driver->init_termios.c_ispeed = 38400;
925 ptm_driver->init_termios.c_ospeed = 38400;
926 ptm_driver->other = pts_driver;
927 tty_set_operations(ptm_driver, &ptm_unix98_ops);
928
929 pts_driver->driver_name = "pty_slave";
930 pts_driver->name = "pts";
931 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
932 pts_driver->minor_start = 0;
933 pts_driver->type = TTY_DRIVER_TYPE_PTY;
934 pts_driver->subtype = PTY_TYPE_SLAVE;
935 pts_driver->init_termios = tty_std_termios;
936 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
937 pts_driver->init_termios.c_ispeed = 38400;
938 pts_driver->init_termios.c_ospeed = 38400;
939 pts_driver->other = ptm_driver;
940 tty_set_operations(pts_driver, &pty_unix98_ops);
941
942 if (tty_register_driver(ptm_driver))
943 panic("Couldn't register Unix98 ptm driver");
944 if (tty_register_driver(pts_driver))
945 panic("Couldn't register Unix98 pts driver");
946
947 /* Now create the /dev/ptmx special device */
948 tty_default_fops(&ptmx_fops);
949 ptmx_fops.open = ptmx_open;
950
951 cdev_init(&ptmx_cdev, &ptmx_fops);
952 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
953 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
954 panic("Couldn't register /dev/ptmx driver");
955 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
956}
957
958#else
959static inline void unix98_pty_init(void) { }
960#endif
961
962static int __init pty_init(void)
963{
964 legacy_pty_init();
965 unix98_pty_init();
966 return 0;
967}
968device_initcall(pty_init);
969