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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#include <linux/compat.h>
32#include "tty.h"
33
34#undef TTY_DEBUG_HANGUP
35#ifdef TTY_DEBUG_HANGUP
36# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
37#else
38# define tty_debug_hangup(tty, f, args...) do {} while (0)
39#endif
40
41#ifdef CONFIG_UNIX98_PTYS
42static struct tty_driver *ptm_driver;
43static struct tty_driver *pts_driver;
44static DEFINE_MUTEX(devpts_mutex);
45#endif
46
47static void pty_close(struct tty_struct *tty, struct file *filp)
48{
49 if (tty->driver->subtype == PTY_TYPE_MASTER)
50 WARN_ON(tty->count > 1);
51 else {
52 if (tty_io_error(tty))
53 return;
54 if (tty->count > 2)
55 return;
56 }
57 set_bit(TTY_IO_ERROR, &tty->flags);
58 wake_up_interruptible(&tty->read_wait);
59 wake_up_interruptible(&tty->write_wait);
60 spin_lock_irq(&tty->ctrl.lock);
61 tty->ctrl.packet = false;
62 spin_unlock_irq(&tty->ctrl.lock);
63 /* Review - krefs on tty_link ?? */
64 if (!tty->link)
65 return;
66 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
67 wake_up_interruptible(&tty->link->read_wait);
68 wake_up_interruptible(&tty->link->write_wait);
69 if (tty->driver->subtype == PTY_TYPE_MASTER) {
70 set_bit(TTY_OTHER_CLOSED, &tty->flags);
71#ifdef CONFIG_UNIX98_PTYS
72 if (tty->driver == ptm_driver) {
73 mutex_lock(&devpts_mutex);
74 if (tty->link->driver_data)
75 devpts_pty_kill(tty->link->driver_data);
76 mutex_unlock(&devpts_mutex);
77 }
78#endif
79 tty_vhangup(tty->link);
80 }
81}
82
83/*
84 * The unthrottle routine is called by the line discipline to signal
85 * that it can receive more characters. For PTY's, the TTY_THROTTLED
86 * flag is always set, to force the line discipline to always call the
87 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
88 * characters in the queue. This is necessary since each time this
89 * happens, we need to wake up any sleeping processes that could be
90 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
91 * for the pty buffer to be drained.
92 */
93static void pty_unthrottle(struct tty_struct *tty)
94{
95 tty_wakeup(tty->link);
96 set_bit(TTY_THROTTLED, &tty->flags);
97}
98
99/**
100 * pty_write - write to a pty
101 * @tty: the tty we write from
102 * @buf: kernel buffer of data
103 * @c: bytes to write
104 *
105 * Our "hardware" write method. Data is coming from the ldisc which
106 * may be in a non sleeping state. We simply throw this at the other
107 * end of the link as if we were an IRQ handler receiving stuff for
108 * the other side of the pty/tty pair.
109 */
110
111static ssize_t pty_write(struct tty_struct *tty, const u8 *buf, size_t c)
112{
113 struct tty_struct *to = tty->link;
114
115 if (tty->flow.stopped || !c)
116 return 0;
117
118 return tty_insert_flip_string_and_push_buffer(to->port, buf, c);
119}
120
121/**
122 * pty_write_room - write space
123 * @tty: tty we are writing from
124 *
125 * Report how many bytes the ldisc can send into the queue for
126 * the other device.
127 */
128
129static unsigned int pty_write_room(struct tty_struct *tty)
130{
131 if (tty->flow.stopped)
132 return 0;
133 return tty_buffer_space_avail(tty->link->port);
134}
135
136/* Set the lock flag on a pty */
137static int pty_set_lock(struct tty_struct *tty, int __user *arg)
138{
139 int val;
140
141 if (get_user(val, arg))
142 return -EFAULT;
143 if (val)
144 set_bit(TTY_PTY_LOCK, &tty->flags);
145 else
146 clear_bit(TTY_PTY_LOCK, &tty->flags);
147 return 0;
148}
149
150static int pty_get_lock(struct tty_struct *tty, int __user *arg)
151{
152 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
153
154 return put_user(locked, arg);
155}
156
157/* Set the packet mode on a pty */
158static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
159{
160 int pktmode;
161
162 if (get_user(pktmode, arg))
163 return -EFAULT;
164
165 spin_lock_irq(&tty->ctrl.lock);
166 if (pktmode) {
167 if (!tty->ctrl.packet) {
168 tty->link->ctrl.pktstatus = 0;
169 smp_mb();
170 tty->ctrl.packet = true;
171 }
172 } else
173 tty->ctrl.packet = false;
174 spin_unlock_irq(&tty->ctrl.lock);
175
176 return 0;
177}
178
179/* Get the packet mode of a pty */
180static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
181{
182 int pktmode = tty->ctrl.packet;
183
184 return put_user(pktmode, arg);
185}
186
187/* Send a signal to the slave */
188static int pty_signal(struct tty_struct *tty, int sig)
189{
190 struct pid *pgrp;
191
192 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
193 return -EINVAL;
194
195 if (tty->link) {
196 pgrp = tty_get_pgrp(tty->link);
197 if (pgrp)
198 kill_pgrp(pgrp, sig, 1);
199 put_pid(pgrp);
200 }
201 return 0;
202}
203
204static void pty_flush_buffer(struct tty_struct *tty)
205{
206 struct tty_struct *to = tty->link;
207
208 if (!to)
209 return;
210
211 tty_buffer_flush(to, NULL);
212 if (to->ctrl.packet) {
213 spin_lock_irq(&tty->ctrl.lock);
214 tty->ctrl.pktstatus |= TIOCPKT_FLUSHWRITE;
215 wake_up_interruptible(&to->read_wait);
216 spin_unlock_irq(&tty->ctrl.lock);
217 }
218}
219
220static int pty_open(struct tty_struct *tty, struct file *filp)
221{
222 if (!tty || !tty->link)
223 return -ENODEV;
224
225 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
226 goto out;
227 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
228 goto out;
229 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
230 goto out;
231
232 clear_bit(TTY_IO_ERROR, &tty->flags);
233 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
234 set_bit(TTY_THROTTLED, &tty->flags);
235 return 0;
236
237out:
238 set_bit(TTY_IO_ERROR, &tty->flags);
239 return -EIO;
240}
241
242static void pty_set_termios(struct tty_struct *tty,
243 const struct ktermios *old_termios)
244{
245 /* See if packet mode change of state. */
246 if (tty->link && tty->link->ctrl.packet) {
247 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
248 int old_flow = ((old_termios->c_iflag & IXON) &&
249 (old_termios->c_cc[VSTOP] == '\023') &&
250 (old_termios->c_cc[VSTART] == '\021'));
251 int new_flow = (I_IXON(tty) &&
252 STOP_CHAR(tty) == '\023' &&
253 START_CHAR(tty) == '\021');
254 if ((old_flow != new_flow) || extproc) {
255 spin_lock_irq(&tty->ctrl.lock);
256 if (old_flow != new_flow) {
257 tty->ctrl.pktstatus &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
258 if (new_flow)
259 tty->ctrl.pktstatus |= TIOCPKT_DOSTOP;
260 else
261 tty->ctrl.pktstatus |= TIOCPKT_NOSTOP;
262 }
263 if (extproc)
264 tty->ctrl.pktstatus |= TIOCPKT_IOCTL;
265 spin_unlock_irq(&tty->ctrl.lock);
266 wake_up_interruptible(&tty->link->read_wait);
267 }
268 }
269
270 tty->termios.c_cflag &= ~(CSIZE | PARENB);
271 tty->termios.c_cflag |= (CS8 | CREAD);
272}
273
274/**
275 * pty_resize - resize event
276 * @tty: tty being resized
277 * @ws: window size being set.
278 *
279 * Update the termios variables and send the necessary signals to
280 * peform a terminal resize correctly
281 */
282
283static int pty_resize(struct tty_struct *tty, struct winsize *ws)
284{
285 struct pid *pgrp, *rpgrp;
286 struct tty_struct *pty = tty->link;
287
288 /* For a PTY we need to lock the tty side */
289 mutex_lock(&tty->winsize_mutex);
290 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
291 goto done;
292
293 /* Signal the foreground process group of both ptys */
294 pgrp = tty_get_pgrp(tty);
295 rpgrp = tty_get_pgrp(pty);
296
297 if (pgrp)
298 kill_pgrp(pgrp, SIGWINCH, 1);
299 if (rpgrp != pgrp && rpgrp)
300 kill_pgrp(rpgrp, SIGWINCH, 1);
301
302 put_pid(pgrp);
303 put_pid(rpgrp);
304
305 tty->winsize = *ws;
306 pty->winsize = *ws; /* Never used so will go away soon */
307done:
308 mutex_unlock(&tty->winsize_mutex);
309 return 0;
310}
311
312/**
313 * pty_start - start() handler
314 * pty_stop - stop() handler
315 * @tty: tty being flow-controlled
316 *
317 * Propagates the TIOCPKT status to the master pty.
318 *
319 * NB: only the master pty can be in packet mode so only the slave
320 * needs start()/stop() handlers
321 */
322static void pty_start(struct tty_struct *tty)
323{
324 unsigned long flags;
325
326 if (tty->link && tty->link->ctrl.packet) {
327 spin_lock_irqsave(&tty->ctrl.lock, flags);
328 tty->ctrl.pktstatus &= ~TIOCPKT_STOP;
329 tty->ctrl.pktstatus |= TIOCPKT_START;
330 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
331 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
332 }
333}
334
335static void pty_stop(struct tty_struct *tty)
336{
337 unsigned long flags;
338
339 if (tty->link && tty->link->ctrl.packet) {
340 spin_lock_irqsave(&tty->ctrl.lock, flags);
341 tty->ctrl.pktstatus &= ~TIOCPKT_START;
342 tty->ctrl.pktstatus |= TIOCPKT_STOP;
343 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
344 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
345 }
346}
347
348/**
349 * pty_common_install - set up the pty pair
350 * @driver: the pty driver
351 * @tty: the tty being instantiated
352 * @legacy: true if this is BSD style
353 *
354 * Perform the initial set up for the tty/pty pair. Called from the
355 * tty layer when the port is first opened.
356 *
357 * Locking: the caller must hold the tty_mutex
358 */
359static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
360 bool legacy)
361{
362 struct tty_struct *o_tty;
363 struct tty_port *ports[2];
364 int idx = tty->index;
365 int retval = -ENOMEM;
366
367 /* Opening the slave first has always returned -EIO */
368 if (driver->subtype != PTY_TYPE_MASTER)
369 return -EIO;
370
371 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
372 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
373 if (!ports[0] || !ports[1])
374 goto err;
375 if (!try_module_get(driver->other->owner)) {
376 /* This cannot in fact currently happen */
377 goto err;
378 }
379 o_tty = alloc_tty_struct(driver->other, idx);
380 if (!o_tty)
381 goto err_put_module;
382
383 tty_set_lock_subclass(o_tty);
384 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
385
386 if (legacy) {
387 /* We always use new tty termios data so we can do this
388 the easy way .. */
389 tty_init_termios(tty);
390 tty_init_termios(o_tty);
391
392 driver->other->ttys[idx] = o_tty;
393 driver->ttys[idx] = tty;
394 } else {
395 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
396 tty->termios = driver->init_termios;
397 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
398 o_tty->termios = driver->other->init_termios;
399 }
400
401 /*
402 * Everything allocated ... set up the o_tty structure.
403 */
404 tty_driver_kref_get(driver->other);
405 /* Establish the links in both directions */
406 tty->link = o_tty;
407 o_tty->link = tty;
408 tty_port_init(ports[0]);
409 tty_port_init(ports[1]);
410 tty_buffer_set_limit(ports[0], 8192);
411 tty_buffer_set_limit(ports[1], 8192);
412 o_tty->port = ports[0];
413 tty->port = ports[1];
414 o_tty->port->itty = o_tty;
415
416 tty_buffer_set_lock_subclass(o_tty->port);
417
418 tty_driver_kref_get(driver);
419 tty->count++;
420 o_tty->count++;
421 return 0;
422
423err_put_module:
424 module_put(driver->other->owner);
425err:
426 kfree(ports[0]);
427 kfree(ports[1]);
428 return retval;
429}
430
431static void pty_cleanup(struct tty_struct *tty)
432{
433 tty_port_put(tty->port);
434}
435
436/* Traditional BSD devices */
437#ifdef CONFIG_LEGACY_PTYS
438
439static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
440{
441 return pty_common_install(driver, tty, true);
442}
443
444static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
445{
446 struct tty_struct *pair = tty->link;
447
448 driver->ttys[tty->index] = NULL;
449 if (pair)
450 pair->driver->ttys[pair->index] = NULL;
451}
452
453static int pty_bsd_ioctl(struct tty_struct *tty,
454 unsigned int cmd, unsigned long arg)
455{
456 switch (cmd) {
457 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
458 return pty_set_lock(tty, (int __user *) arg);
459 case TIOCGPTLCK: /* Get PT Lock status */
460 return pty_get_lock(tty, (int __user *)arg);
461 case TIOCPKT: /* Set PT packet mode */
462 return pty_set_pktmode(tty, (int __user *)arg);
463 case TIOCGPKT: /* Get PT packet mode */
464 return pty_get_pktmode(tty, (int __user *)arg);
465 case TIOCSIG: /* Send signal to other side of pty */
466 return pty_signal(tty, (int) arg);
467 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
468 return -EINVAL;
469 }
470 return -ENOIOCTLCMD;
471}
472
473#ifdef CONFIG_COMPAT
474static long pty_bsd_compat_ioctl(struct tty_struct *tty,
475 unsigned int cmd, unsigned long arg)
476{
477 /*
478 * PTY ioctls don't require any special translation between 32-bit and
479 * 64-bit userspace, they are already compatible.
480 */
481 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
482}
483#else
484#define pty_bsd_compat_ioctl NULL
485#endif
486
487static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
488/*
489 * not really modular, but the easiest way to keep compat with existing
490 * bootargs behaviour is to continue using module_param here.
491 */
492module_param(legacy_count, int, 0);
493
494/*
495 * The master side of a pty can do TIOCSPTLCK and thus
496 * has pty_bsd_ioctl.
497 */
498static const struct tty_operations master_pty_ops_bsd = {
499 .install = pty_install,
500 .open = pty_open,
501 .close = pty_close,
502 .write = pty_write,
503 .write_room = pty_write_room,
504 .flush_buffer = pty_flush_buffer,
505 .unthrottle = pty_unthrottle,
506 .ioctl = pty_bsd_ioctl,
507 .compat_ioctl = pty_bsd_compat_ioctl,
508 .cleanup = pty_cleanup,
509 .resize = pty_resize,
510 .remove = pty_remove
511};
512
513static const struct tty_operations slave_pty_ops_bsd = {
514 .install = pty_install,
515 .open = pty_open,
516 .close = pty_close,
517 .write = pty_write,
518 .write_room = pty_write_room,
519 .flush_buffer = pty_flush_buffer,
520 .unthrottle = pty_unthrottle,
521 .set_termios = pty_set_termios,
522 .cleanup = pty_cleanup,
523 .resize = pty_resize,
524 .start = pty_start,
525 .stop = pty_stop,
526 .remove = pty_remove
527};
528
529static void __init legacy_pty_init(void)
530{
531 struct tty_driver *pty_driver, *pty_slave_driver;
532
533 if (legacy_count <= 0)
534 return;
535
536 pty_driver = tty_alloc_driver(legacy_count,
537 TTY_DRIVER_RESET_TERMIOS |
538 TTY_DRIVER_REAL_RAW |
539 TTY_DRIVER_DYNAMIC_ALLOC);
540 if (IS_ERR(pty_driver))
541 panic("Couldn't allocate pty driver");
542
543 pty_slave_driver = tty_alloc_driver(legacy_count,
544 TTY_DRIVER_RESET_TERMIOS |
545 TTY_DRIVER_REAL_RAW |
546 TTY_DRIVER_DYNAMIC_ALLOC);
547 if (IS_ERR(pty_slave_driver))
548 panic("Couldn't allocate pty slave driver");
549
550 pty_driver->driver_name = "pty_master";
551 pty_driver->name = "pty";
552 pty_driver->major = PTY_MASTER_MAJOR;
553 pty_driver->minor_start = 0;
554 pty_driver->type = TTY_DRIVER_TYPE_PTY;
555 pty_driver->subtype = PTY_TYPE_MASTER;
556 pty_driver->init_termios = tty_std_termios;
557 pty_driver->init_termios.c_iflag = 0;
558 pty_driver->init_termios.c_oflag = 0;
559 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
560 pty_driver->init_termios.c_lflag = 0;
561 pty_driver->init_termios.c_ispeed = 38400;
562 pty_driver->init_termios.c_ospeed = 38400;
563 pty_driver->other = pty_slave_driver;
564 tty_set_operations(pty_driver, &master_pty_ops_bsd);
565
566 pty_slave_driver->driver_name = "pty_slave";
567 pty_slave_driver->name = "ttyp";
568 pty_slave_driver->major = PTY_SLAVE_MAJOR;
569 pty_slave_driver->minor_start = 0;
570 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
571 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
572 pty_slave_driver->init_termios = tty_std_termios;
573 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
574 pty_slave_driver->init_termios.c_ispeed = 38400;
575 pty_slave_driver->init_termios.c_ospeed = 38400;
576 pty_slave_driver->other = pty_driver;
577 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
578
579 if (tty_register_driver(pty_driver))
580 panic("Couldn't register pty driver");
581 if (tty_register_driver(pty_slave_driver))
582 panic("Couldn't register pty slave driver");
583}
584#else
585static inline void legacy_pty_init(void) { }
586#endif
587
588/* Unix98 devices */
589#ifdef CONFIG_UNIX98_PTYS
590static struct cdev ptmx_cdev;
591
592/**
593 * ptm_open_peer - open the peer of a pty
594 * @master: the open struct file of the ptmx device node
595 * @tty: the master of the pty being opened
596 * @flags: the flags for open
597 *
598 * Provide a race free way for userspace to open the slave end of a pty
599 * (where they have the master fd and cannot access or trust the mount
600 * namespace /dev/pts was mounted inside).
601 */
602int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
603{
604 int fd;
605 struct file *filp;
606 int retval = -EINVAL;
607 struct path path;
608
609 if (tty->driver != ptm_driver)
610 return -EIO;
611
612 fd = get_unused_fd_flags(flags);
613 if (fd < 0) {
614 retval = fd;
615 goto err;
616 }
617
618 /* Compute the slave's path */
619 path.mnt = devpts_mntget(master, tty->driver_data);
620 if (IS_ERR(path.mnt)) {
621 retval = PTR_ERR(path.mnt);
622 goto err_put;
623 }
624 path.dentry = tty->link->driver_data;
625
626 filp = dentry_open(&path, flags, current_cred());
627 mntput(path.mnt);
628 if (IS_ERR(filp)) {
629 retval = PTR_ERR(filp);
630 goto err_put;
631 }
632
633 fd_install(fd, filp);
634 return fd;
635
636err_put:
637 put_unused_fd(fd);
638err:
639 return retval;
640}
641
642static int pty_unix98_ioctl(struct tty_struct *tty,
643 unsigned int cmd, unsigned long arg)
644{
645 switch (cmd) {
646 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
647 return pty_set_lock(tty, (int __user *)arg);
648 case TIOCGPTLCK: /* Get PT Lock status */
649 return pty_get_lock(tty, (int __user *)arg);
650 case TIOCPKT: /* Set PT packet mode */
651 return pty_set_pktmode(tty, (int __user *)arg);
652 case TIOCGPKT: /* Get PT packet mode */
653 return pty_get_pktmode(tty, (int __user *)arg);
654 case TIOCGPTN: /* Get PT Number */
655 return put_user(tty->index, (unsigned int __user *)arg);
656 case TIOCSIG: /* Send signal to other side of pty */
657 return pty_signal(tty, (int) arg);
658 }
659
660 return -ENOIOCTLCMD;
661}
662
663#ifdef CONFIG_COMPAT
664static long pty_unix98_compat_ioctl(struct tty_struct *tty,
665 unsigned int cmd, unsigned long arg)
666{
667 /*
668 * PTY ioctls don't require any special translation between 32-bit and
669 * 64-bit userspace, they are already compatible.
670 */
671 return pty_unix98_ioctl(tty, cmd,
672 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg));
673}
674#else
675#define pty_unix98_compat_ioctl NULL
676#endif
677
678/**
679 * ptm_unix98_lookup - find a pty master
680 * @driver: ptm driver
681 * @file: unused
682 * @idx: tty index
683 *
684 * Look up a pty master device. Called under the tty_mutex for now.
685 * This provides our locking.
686 */
687
688static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
689 struct file *file, int idx)
690{
691 /* Master must be open via /dev/ptmx */
692 return ERR_PTR(-EIO);
693}
694
695/**
696 * pts_unix98_lookup - find a pty slave
697 * @driver: pts driver
698 * @file: file pointer to tty
699 * @idx: tty index
700 *
701 * Look up a pty master device. Called under the tty_mutex for now.
702 * This provides our locking for the tty pointer.
703 */
704
705static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
706 struct file *file, int idx)
707{
708 struct tty_struct *tty;
709
710 mutex_lock(&devpts_mutex);
711 tty = devpts_get_priv(file->f_path.dentry);
712 mutex_unlock(&devpts_mutex);
713 /* Master must be open before slave */
714 if (!tty)
715 return ERR_PTR(-EIO);
716 return tty;
717}
718
719static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
720{
721 return pty_common_install(driver, tty, false);
722}
723
724/* this is called once with whichever end is closed last */
725static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
726{
727 struct pts_fs_info *fsi;
728
729 if (tty->driver->subtype == PTY_TYPE_MASTER)
730 fsi = tty->driver_data;
731 else
732 fsi = tty->link->driver_data;
733
734 if (fsi) {
735 devpts_kill_index(fsi, tty->index);
736 devpts_release(fsi);
737 }
738}
739
740static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
741{
742 seq_printf(m, "tty-index:\t%d\n", tty->index);
743}
744
745static const struct tty_operations ptm_unix98_ops = {
746 .lookup = ptm_unix98_lookup,
747 .install = pty_unix98_install,
748 .remove = pty_unix98_remove,
749 .open = pty_open,
750 .close = pty_close,
751 .write = pty_write,
752 .write_room = pty_write_room,
753 .flush_buffer = pty_flush_buffer,
754 .unthrottle = pty_unthrottle,
755 .ioctl = pty_unix98_ioctl,
756 .compat_ioctl = pty_unix98_compat_ioctl,
757 .resize = pty_resize,
758 .cleanup = pty_cleanup,
759 .show_fdinfo = pty_show_fdinfo,
760};
761
762static const struct tty_operations pty_unix98_ops = {
763 .lookup = pts_unix98_lookup,
764 .install = pty_unix98_install,
765 .remove = pty_unix98_remove,
766 .open = pty_open,
767 .close = pty_close,
768 .write = pty_write,
769 .write_room = pty_write_room,
770 .flush_buffer = pty_flush_buffer,
771 .unthrottle = pty_unthrottle,
772 .set_termios = pty_set_termios,
773 .start = pty_start,
774 .stop = pty_stop,
775 .cleanup = pty_cleanup,
776};
777
778/**
779 * ptmx_open - open a unix 98 pty master
780 * @inode: inode of device file
781 * @filp: file pointer to tty
782 *
783 * Allocate a unix98 pty master device from the ptmx driver.
784 *
785 * Locking: tty_mutex protects the init_dev work. tty->count should
786 * protect the rest.
787 * allocated_ptys_lock handles the list of free pty numbers
788 */
789
790static int ptmx_open(struct inode *inode, struct file *filp)
791{
792 struct pts_fs_info *fsi;
793 struct tty_struct *tty;
794 struct dentry *dentry;
795 int retval;
796 int index;
797
798 nonseekable_open(inode, filp);
799
800 /* We refuse fsnotify events on ptmx, since it's a shared resource */
801 filp->f_mode |= FMODE_NONOTIFY;
802
803 retval = tty_alloc_file(filp);
804 if (retval)
805 return retval;
806
807 fsi = devpts_acquire(filp);
808 if (IS_ERR(fsi)) {
809 retval = PTR_ERR(fsi);
810 goto out_free_file;
811 }
812
813 /* find a device that is not in use. */
814 mutex_lock(&devpts_mutex);
815 index = devpts_new_index(fsi);
816 mutex_unlock(&devpts_mutex);
817
818 retval = index;
819 if (index < 0)
820 goto out_put_fsi;
821
822
823 mutex_lock(&tty_mutex);
824 tty = tty_init_dev(ptm_driver, index);
825 /* The tty returned here is locked so we can safely
826 drop the mutex */
827 mutex_unlock(&tty_mutex);
828
829 retval = PTR_ERR(tty);
830 if (IS_ERR(tty))
831 goto out;
832
833 /*
834 * From here on out, the tty is "live", and the index and
835 * fsi will be killed/put by the tty_release()
836 */
837 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
838 tty->driver_data = fsi;
839
840 tty_add_file(tty, filp);
841
842 dentry = devpts_pty_new(fsi, index, tty->link);
843 if (IS_ERR(dentry)) {
844 retval = PTR_ERR(dentry);
845 goto err_release;
846 }
847 tty->link->driver_data = dentry;
848
849 retval = ptm_driver->ops->open(tty, filp);
850 if (retval)
851 goto err_release;
852
853 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
854
855 tty_unlock(tty);
856 return 0;
857err_release:
858 tty_unlock(tty);
859 // This will also put-ref the fsi
860 tty_release(inode, filp);
861 return retval;
862out:
863 devpts_kill_index(fsi, index);
864out_put_fsi:
865 devpts_release(fsi);
866out_free_file:
867 tty_free_file(filp);
868 return retval;
869}
870
871static struct file_operations ptmx_fops __ro_after_init;
872
873static void __init unix98_pty_init(void)
874{
875 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
876 TTY_DRIVER_RESET_TERMIOS |
877 TTY_DRIVER_REAL_RAW |
878 TTY_DRIVER_DYNAMIC_DEV |
879 TTY_DRIVER_DEVPTS_MEM |
880 TTY_DRIVER_DYNAMIC_ALLOC);
881 if (IS_ERR(ptm_driver))
882 panic("Couldn't allocate Unix98 ptm driver");
883 pts_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(pts_driver))
890 panic("Couldn't allocate Unix98 pts driver");
891
892 ptm_driver->driver_name = "pty_master";
893 ptm_driver->name = "ptm";
894 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
895 ptm_driver->minor_start = 0;
896 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
897 ptm_driver->subtype = PTY_TYPE_MASTER;
898 ptm_driver->init_termios = tty_std_termios;
899 ptm_driver->init_termios.c_iflag = 0;
900 ptm_driver->init_termios.c_oflag = 0;
901 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
902 ptm_driver->init_termios.c_lflag = 0;
903 ptm_driver->init_termios.c_ispeed = 38400;
904 ptm_driver->init_termios.c_ospeed = 38400;
905 ptm_driver->other = pts_driver;
906 tty_set_operations(ptm_driver, &ptm_unix98_ops);
907
908 pts_driver->driver_name = "pty_slave";
909 pts_driver->name = "pts";
910 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
911 pts_driver->minor_start = 0;
912 pts_driver->type = TTY_DRIVER_TYPE_PTY;
913 pts_driver->subtype = PTY_TYPE_SLAVE;
914 pts_driver->init_termios = tty_std_termios;
915 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
916 pts_driver->init_termios.c_ispeed = 38400;
917 pts_driver->init_termios.c_ospeed = 38400;
918 pts_driver->other = ptm_driver;
919 tty_set_operations(pts_driver, &pty_unix98_ops);
920
921 if (tty_register_driver(ptm_driver))
922 panic("Couldn't register Unix98 ptm driver");
923 if (tty_register_driver(pts_driver))
924 panic("Couldn't register Unix98 pts driver");
925
926 /* Now create the /dev/ptmx special device */
927 tty_default_fops(&ptmx_fops);
928 ptmx_fops.open = ptmx_open;
929
930 cdev_init(&ptmx_cdev, &ptmx_fops);
931 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
932 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
933 panic("Couldn't register /dev/ptmx driver");
934 device_create(&tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
935}
936
937#else
938static inline void unix98_pty_init(void) { }
939#endif
940
941static int __init pty_init(void)
942{
943 legacy_pty_init();
944 unix98_pty_init();
945 return 0;
946}
947device_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 * 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/device.h>
25#include <linux/uaccess.h>
26#include <linux/bitops.h>
27#include <linux/devpts_fs.h>
28#include <linux/slab.h>
29#include <linux/mutex.h>
30
31
32#ifdef CONFIG_UNIX98_PTYS
33static struct tty_driver *ptm_driver;
34static struct tty_driver *pts_driver;
35static DEFINE_MUTEX(devpts_mutex);
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 mutex_lock(&devpts_mutex);
61 devpts_pty_kill(tty->link);
62 mutex_unlock(&devpts_mutex);
63 }
64#endif
65 tty_unlock();
66 tty_vhangup(tty->link);
67 tty_lock();
68 }
69}
70
71/*
72 * The unthrottle routine is called by the line discipline to signal
73 * that it can receive more characters. For PTY's, the TTY_THROTTLED
74 * flag is always set, to force the line discipline to always call the
75 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
76 * characters in the queue. This is necessary since each time this
77 * happens, we need to wake up any sleeping processes that could be
78 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
79 * for the pty buffer to be drained.
80 */
81static void pty_unthrottle(struct tty_struct *tty)
82{
83 tty_wakeup(tty->link);
84 set_bit(TTY_THROTTLED, &tty->flags);
85}
86
87/**
88 * pty_space - report space left for writing
89 * @to: tty we are writing into
90 *
91 * The tty buffers allow 64K but we sneak a peak and clip at 8K this
92 * allows a lot of overspill room for echo and other fun messes to
93 * be handled properly
94 */
95
96static int pty_space(struct tty_struct *to)
97{
98 int n = 8192 - to->buf.memory_used;
99 if (n < 0)
100 return 0;
101 return n;
102}
103
104/**
105 * pty_write - write to a pty
106 * @tty: the tty we write from
107 * @buf: kernel buffer of data
108 * @count: bytes to write
109 *
110 * Our "hardware" write method. Data is coming from the ldisc which
111 * may be in a non sleeping state. We simply throw this at the other
112 * end of the link as if we were an IRQ handler receiving stuff for
113 * the other side of the pty/tty pair.
114 */
115
116static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
117{
118 struct tty_struct *to = tty->link;
119
120 if (tty->stopped)
121 return 0;
122
123 if (c > 0) {
124 /* Stuff the data into the input queue of the other end */
125 c = tty_insert_flip_string(to, buf, c);
126 /* And shovel */
127 if (c) {
128 tty_flip_buffer_push(to);
129 tty_wakeup(tty);
130 }
131 }
132 return c;
133}
134
135/**
136 * pty_write_room - write space
137 * @tty: tty we are writing from
138 *
139 * Report how many bytes the ldisc can send into the queue for
140 * the other device.
141 */
142
143static int pty_write_room(struct tty_struct *tty)
144{
145 if (tty->stopped)
146 return 0;
147 return pty_space(tty->link);
148}
149
150/**
151 * pty_chars_in_buffer - characters currently in our tx queue
152 * @tty: our tty
153 *
154 * Report how much we have in the transmit queue. As everything is
155 * instantly at the other end this is easy to implement.
156 */
157
158static int pty_chars_in_buffer(struct tty_struct *tty)
159{
160 return 0;
161}
162
163/* Set the lock flag on a pty */
164static int pty_set_lock(struct tty_struct *tty, int __user *arg)
165{
166 int val;
167 if (get_user(val, arg))
168 return -EFAULT;
169 if (val)
170 set_bit(TTY_PTY_LOCK, &tty->flags);
171 else
172 clear_bit(TTY_PTY_LOCK, &tty->flags);
173 return 0;
174}
175
176/* Send a signal to the slave */
177static int pty_signal(struct tty_struct *tty, int sig)
178{
179 unsigned long flags;
180 struct pid *pgrp;
181
182 if (tty->link) {
183 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
184 pgrp = get_pid(tty->link->pgrp);
185 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
186
187 kill_pgrp(pgrp, sig, 1);
188 put_pid(pgrp);
189 }
190 return 0;
191}
192
193static void pty_flush_buffer(struct tty_struct *tty)
194{
195 struct tty_struct *to = tty->link;
196 unsigned long flags;
197
198 if (!to)
199 return;
200 /* tty_buffer_flush(to); FIXME */
201 if (to->packet) {
202 spin_lock_irqsave(&tty->ctrl_lock, flags);
203 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
204 wake_up_interruptible(&to->read_wait);
205 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
206 }
207}
208
209static int pty_open(struct tty_struct *tty, struct file *filp)
210{
211 int retval = -ENODEV;
212
213 if (!tty || !tty->link)
214 goto out;
215
216 retval = -EIO;
217 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
218 goto out;
219 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
220 goto out;
221 if (tty->link->count != 1)
222 goto out;
223
224 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
225 set_bit(TTY_THROTTLED, &tty->flags);
226 retval = 0;
227out:
228 return retval;
229}
230
231static void pty_set_termios(struct tty_struct *tty,
232 struct ktermios *old_termios)
233{
234 tty->termios->c_cflag &= ~(CSIZE | PARENB);
235 tty->termios->c_cflag |= (CS8 | CREAD);
236}
237
238/**
239 * pty_do_resize - resize event
240 * @tty: tty being resized
241 * @ws: window size being set.
242 *
243 * Update the termios variables and send the necessary signals to
244 * peform a terminal resize correctly
245 */
246
247int pty_resize(struct tty_struct *tty, struct winsize *ws)
248{
249 struct pid *pgrp, *rpgrp;
250 unsigned long flags;
251 struct tty_struct *pty = tty->link;
252
253 /* For a PTY we need to lock the tty side */
254 mutex_lock(&tty->termios_mutex);
255 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
256 goto done;
257
258 /* Get the PID values and reference them so we can
259 avoid holding the tty ctrl lock while sending signals.
260 We need to lock these individually however. */
261
262 spin_lock_irqsave(&tty->ctrl_lock, flags);
263 pgrp = get_pid(tty->pgrp);
264 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
265
266 spin_lock_irqsave(&pty->ctrl_lock, flags);
267 rpgrp = get_pid(pty->pgrp);
268 spin_unlock_irqrestore(&pty->ctrl_lock, flags);
269
270 if (pgrp)
271 kill_pgrp(pgrp, SIGWINCH, 1);
272 if (rpgrp != pgrp && rpgrp)
273 kill_pgrp(rpgrp, SIGWINCH, 1);
274
275 put_pid(pgrp);
276 put_pid(rpgrp);
277
278 tty->winsize = *ws;
279 pty->winsize = *ws; /* Never used so will go away soon */
280done:
281 mutex_unlock(&tty->termios_mutex);
282 return 0;
283}
284
285/* Traditional BSD devices */
286#ifdef CONFIG_LEGACY_PTYS
287
288static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
289{
290 struct tty_struct *o_tty;
291 int idx = tty->index;
292 int retval;
293
294 o_tty = alloc_tty_struct();
295 if (!o_tty)
296 return -ENOMEM;
297 if (!try_module_get(driver->other->owner)) {
298 /* This cannot in fact currently happen */
299 retval = -ENOMEM;
300 goto err_free_tty;
301 }
302 initialize_tty_struct(o_tty, driver->other, idx);
303
304 /* We always use new tty termios data so we can do this
305 the easy way .. */
306 retval = tty_init_termios(tty);
307 if (retval)
308 goto err_deinit_tty;
309
310 retval = tty_init_termios(o_tty);
311 if (retval)
312 goto err_free_termios;
313
314 /*
315 * Everything allocated ... set up the o_tty structure.
316 */
317 driver->other->ttys[idx] = o_tty;
318 tty_driver_kref_get(driver->other);
319 if (driver->subtype == PTY_TYPE_MASTER)
320 o_tty->count++;
321 /* Establish the links in both directions */
322 tty->link = o_tty;
323 o_tty->link = tty;
324
325 tty_driver_kref_get(driver);
326 tty->count++;
327 driver->ttys[idx] = tty;
328 return 0;
329err_free_termios:
330 tty_free_termios(tty);
331err_deinit_tty:
332 deinitialize_tty_struct(o_tty);
333 module_put(o_tty->driver->owner);
334err_free_tty:
335 free_tty_struct(o_tty);
336 return retval;
337}
338
339static int pty_bsd_ioctl(struct tty_struct *tty,
340 unsigned int cmd, unsigned long arg)
341{
342 switch (cmd) {
343 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
344 return pty_set_lock(tty, (int __user *) arg);
345 case TIOCSIG: /* Send signal to other side of pty */
346 return pty_signal(tty, (int) arg);
347 }
348 return -ENOIOCTLCMD;
349}
350
351static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
352module_param(legacy_count, int, 0);
353
354/*
355 * The master side of a pty can do TIOCSPTLCK and thus
356 * has pty_bsd_ioctl.
357 */
358static const struct tty_operations master_pty_ops_bsd = {
359 .install = pty_install,
360 .open = pty_open,
361 .close = pty_close,
362 .write = pty_write,
363 .write_room = pty_write_room,
364 .flush_buffer = pty_flush_buffer,
365 .chars_in_buffer = pty_chars_in_buffer,
366 .unthrottle = pty_unthrottle,
367 .set_termios = pty_set_termios,
368 .ioctl = pty_bsd_ioctl,
369 .resize = pty_resize
370};
371
372static const struct tty_operations slave_pty_ops_bsd = {
373 .install = pty_install,
374 .open = pty_open,
375 .close = pty_close,
376 .write = pty_write,
377 .write_room = pty_write_room,
378 .flush_buffer = pty_flush_buffer,
379 .chars_in_buffer = pty_chars_in_buffer,
380 .unthrottle = pty_unthrottle,
381 .set_termios = pty_set_termios,
382 .resize = pty_resize
383};
384
385static void __init legacy_pty_init(void)
386{
387 struct tty_driver *pty_driver, *pty_slave_driver;
388
389 if (legacy_count <= 0)
390 return;
391
392 pty_driver = alloc_tty_driver(legacy_count);
393 if (!pty_driver)
394 panic("Couldn't allocate pty driver");
395
396 pty_slave_driver = alloc_tty_driver(legacy_count);
397 if (!pty_slave_driver)
398 panic("Couldn't allocate pty slave driver");
399
400 pty_driver->driver_name = "pty_master";
401 pty_driver->name = "pty";
402 pty_driver->major = PTY_MASTER_MAJOR;
403 pty_driver->minor_start = 0;
404 pty_driver->type = TTY_DRIVER_TYPE_PTY;
405 pty_driver->subtype = PTY_TYPE_MASTER;
406 pty_driver->init_termios = tty_std_termios;
407 pty_driver->init_termios.c_iflag = 0;
408 pty_driver->init_termios.c_oflag = 0;
409 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
410 pty_driver->init_termios.c_lflag = 0;
411 pty_driver->init_termios.c_ispeed = 38400;
412 pty_driver->init_termios.c_ospeed = 38400;
413 pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
414 pty_driver->other = pty_slave_driver;
415 tty_set_operations(pty_driver, &master_pty_ops_bsd);
416
417 pty_slave_driver->driver_name = "pty_slave";
418 pty_slave_driver->name = "ttyp";
419 pty_slave_driver->major = PTY_SLAVE_MAJOR;
420 pty_slave_driver->minor_start = 0;
421 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
422 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
423 pty_slave_driver->init_termios = tty_std_termios;
424 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
425 pty_slave_driver->init_termios.c_ispeed = 38400;
426 pty_slave_driver->init_termios.c_ospeed = 38400;
427 pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
428 TTY_DRIVER_REAL_RAW;
429 pty_slave_driver->other = pty_driver;
430 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
431
432 if (tty_register_driver(pty_driver))
433 panic("Couldn't register pty driver");
434 if (tty_register_driver(pty_slave_driver))
435 panic("Couldn't register pty slave driver");
436}
437#else
438static inline void legacy_pty_init(void) { }
439#endif
440
441/* Unix98 devices */
442#ifdef CONFIG_UNIX98_PTYS
443
444static struct cdev ptmx_cdev;
445
446static int pty_unix98_ioctl(struct tty_struct *tty,
447 unsigned int cmd, unsigned long arg)
448{
449 switch (cmd) {
450 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
451 return pty_set_lock(tty, (int __user *)arg);
452 case TIOCGPTN: /* Get PT Number */
453 return put_user(tty->index, (unsigned int __user *)arg);
454 case TIOCSIG: /* Send signal to other side of pty */
455 return pty_signal(tty, (int) arg);
456 }
457
458 return -ENOIOCTLCMD;
459}
460
461/**
462 * ptm_unix98_lookup - find a pty master
463 * @driver: ptm driver
464 * @idx: tty index
465 *
466 * Look up a pty master device. Called under the tty_mutex for now.
467 * This provides our locking.
468 */
469
470static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
471 struct inode *ptm_inode, int idx)
472{
473 /* Master must be open via /dev/ptmx */
474 return ERR_PTR(-EIO);
475}
476
477/**
478 * pts_unix98_lookup - find a pty slave
479 * @driver: pts driver
480 * @idx: tty index
481 *
482 * Look up a pty master device. Called under the tty_mutex for now.
483 * This provides our locking for the tty pointer.
484 */
485
486static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
487 struct inode *pts_inode, int idx)
488{
489 struct tty_struct *tty;
490
491 mutex_lock(&devpts_mutex);
492 tty = devpts_get_tty(pts_inode, idx);
493 mutex_unlock(&devpts_mutex);
494 /* Master must be open before slave */
495 if (!tty)
496 return ERR_PTR(-EIO);
497 return tty;
498}
499
500static void pty_unix98_shutdown(struct tty_struct *tty)
501{
502 tty_driver_remove_tty(tty->driver, tty);
503 /* We have our own method as we don't use the tty index */
504 kfree(tty->termios);
505}
506
507/* We have no need to install and remove our tty objects as devpts does all
508 the work for us */
509
510static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
511{
512 struct tty_struct *o_tty;
513 int idx = tty->index;
514
515 o_tty = alloc_tty_struct();
516 if (!o_tty)
517 return -ENOMEM;
518 if (!try_module_get(driver->other->owner)) {
519 /* This cannot in fact currently happen */
520 goto err_free_tty;
521 }
522 initialize_tty_struct(o_tty, driver->other, idx);
523
524 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
525 if (tty->termios == NULL)
526 goto err_free_mem;
527 *tty->termios = driver->init_termios;
528 tty->termios_locked = tty->termios + 1;
529
530 o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
531 if (o_tty->termios == NULL)
532 goto err_free_mem;
533 *o_tty->termios = driver->other->init_termios;
534 o_tty->termios_locked = o_tty->termios + 1;
535
536 tty_driver_kref_get(driver->other);
537 if (driver->subtype == PTY_TYPE_MASTER)
538 o_tty->count++;
539 /* Establish the links in both directions */
540 tty->link = o_tty;
541 o_tty->link = tty;
542 /*
543 * All structures have been allocated, so now we install them.
544 * Failures after this point use release_tty to clean up, so
545 * there's no need to null out the local pointers.
546 */
547 tty_driver_kref_get(driver);
548 tty->count++;
549 return 0;
550err_free_mem:
551 deinitialize_tty_struct(o_tty);
552 kfree(o_tty->termios);
553 kfree(tty->termios);
554 module_put(o_tty->driver->owner);
555err_free_tty:
556 free_tty_struct(o_tty);
557 return -ENOMEM;
558}
559
560static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
561{
562}
563
564static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
565{
566}
567
568static const struct tty_operations ptm_unix98_ops = {
569 .lookup = ptm_unix98_lookup,
570 .install = pty_unix98_install,
571 .remove = ptm_unix98_remove,
572 .open = pty_open,
573 .close = pty_close,
574 .write = pty_write,
575 .write_room = pty_write_room,
576 .flush_buffer = pty_flush_buffer,
577 .chars_in_buffer = pty_chars_in_buffer,
578 .unthrottle = pty_unthrottle,
579 .set_termios = pty_set_termios,
580 .ioctl = pty_unix98_ioctl,
581 .shutdown = pty_unix98_shutdown,
582 .resize = pty_resize
583};
584
585static const struct tty_operations pty_unix98_ops = {
586 .lookup = pts_unix98_lookup,
587 .install = pty_unix98_install,
588 .remove = pts_unix98_remove,
589 .open = pty_open,
590 .close = pty_close,
591 .write = pty_write,
592 .write_room = pty_write_room,
593 .flush_buffer = pty_flush_buffer,
594 .chars_in_buffer = pty_chars_in_buffer,
595 .unthrottle = pty_unthrottle,
596 .set_termios = pty_set_termios,
597 .shutdown = pty_unix98_shutdown
598};
599
600/**
601 * ptmx_open - open a unix 98 pty master
602 * @inode: inode of device file
603 * @filp: file pointer to tty
604 *
605 * Allocate a unix98 pty master device from the ptmx driver.
606 *
607 * Locking: tty_mutex protects the init_dev work. tty->count should
608 * protect the rest.
609 * allocated_ptys_lock handles the list of free pty numbers
610 */
611
612static int ptmx_open(struct inode *inode, struct file *filp)
613{
614 struct tty_struct *tty;
615 int retval;
616 int index;
617
618 nonseekable_open(inode, filp);
619
620 retval = tty_alloc_file(filp);
621 if (retval)
622 return retval;
623
624 /* find a device that is not in use. */
625 tty_lock();
626 index = devpts_new_index(inode);
627 tty_unlock();
628 if (index < 0) {
629 retval = index;
630 goto err_file;
631 }
632
633 mutex_lock(&tty_mutex);
634 mutex_lock(&devpts_mutex);
635 tty = tty_init_dev(ptm_driver, index);
636 mutex_unlock(&devpts_mutex);
637 tty_lock();
638 mutex_unlock(&tty_mutex);
639
640 if (IS_ERR(tty)) {
641 retval = PTR_ERR(tty);
642 goto out;
643 }
644
645 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
646
647 tty_add_file(tty, filp);
648
649 retval = devpts_pty_new(inode, tty->link);
650 if (retval)
651 goto err_release;
652
653 retval = ptm_driver->ops->open(tty, filp);
654 if (retval)
655 goto err_release;
656
657 tty_unlock();
658 return 0;
659err_release:
660 tty_unlock();
661 tty_release(inode, filp);
662 return retval;
663out:
664 devpts_kill_index(inode, index);
665 tty_unlock();
666err_file:
667 tty_free_file(filp);
668 return retval;
669}
670
671static struct file_operations ptmx_fops;
672
673static void __init unix98_pty_init(void)
674{
675 ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
676 if (!ptm_driver)
677 panic("Couldn't allocate Unix98 ptm driver");
678 pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
679 if (!pts_driver)
680 panic("Couldn't allocate Unix98 pts driver");
681
682 ptm_driver->driver_name = "pty_master";
683 ptm_driver->name = "ptm";
684 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
685 ptm_driver->minor_start = 0;
686 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
687 ptm_driver->subtype = PTY_TYPE_MASTER;
688 ptm_driver->init_termios = tty_std_termios;
689 ptm_driver->init_termios.c_iflag = 0;
690 ptm_driver->init_termios.c_oflag = 0;
691 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
692 ptm_driver->init_termios.c_lflag = 0;
693 ptm_driver->init_termios.c_ispeed = 38400;
694 ptm_driver->init_termios.c_ospeed = 38400;
695 ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
696 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
697 ptm_driver->other = pts_driver;
698 tty_set_operations(ptm_driver, &ptm_unix98_ops);
699
700 pts_driver->driver_name = "pty_slave";
701 pts_driver->name = "pts";
702 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
703 pts_driver->minor_start = 0;
704 pts_driver->type = TTY_DRIVER_TYPE_PTY;
705 pts_driver->subtype = PTY_TYPE_SLAVE;
706 pts_driver->init_termios = tty_std_termios;
707 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
708 pts_driver->init_termios.c_ispeed = 38400;
709 pts_driver->init_termios.c_ospeed = 38400;
710 pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
711 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
712 pts_driver->other = ptm_driver;
713 tty_set_operations(pts_driver, &pty_unix98_ops);
714
715 if (tty_register_driver(ptm_driver))
716 panic("Couldn't register Unix98 ptm driver");
717 if (tty_register_driver(pts_driver))
718 panic("Couldn't register Unix98 pts driver");
719
720 /* Now create the /dev/ptmx special device */
721 tty_default_fops(&ptmx_fops);
722 ptmx_fops.open = ptmx_open;
723
724 cdev_init(&ptmx_cdev, &ptmx_fops);
725 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
726 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
727 panic("Couldn't register /dev/ptmx driver\n");
728 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
729}
730
731#else
732static inline void unix98_pty_init(void) { }
733#endif
734
735static int __init pty_init(void)
736{
737 legacy_pty_init();
738 unix98_pty_init();
739 return 0;
740}
741module_init(pty_init);