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
42 static struct tty_driver *ptm_driver;
43 static struct tty_driver *pts_driver;
44 static DEFINE_MUTEX(devpts_mutex);
45 #endif
46
pty_close(struct tty_struct * tty,struct file * filp)47 static 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->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 */
pty_unthrottle(struct tty_struct * tty)93 static 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
pty_write(struct tty_struct * tty,const unsigned char * buf,int c)111 static 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 spin_unlock_irqrestore(&to->port->lock, flags);
124 /* And shovel */
125 if (c)
126 tty_flip_buffer_push(to->port);
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
pty_write_room(struct tty_struct * tty)139 static 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
pty_chars_in_buffer(struct tty_struct * tty)154 static int pty_chars_in_buffer(struct tty_struct *tty)
155 {
156 return 0;
157 }
158
159 /* Set the lock flag on a pty */
pty_set_lock(struct tty_struct * tty,int __user * arg)160 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
161 {
162 int val;
163
164 if (get_user(val, arg))
165 return -EFAULT;
166 if (val)
167 set_bit(TTY_PTY_LOCK, &tty->flags);
168 else
169 clear_bit(TTY_PTY_LOCK, &tty->flags);
170 return 0;
171 }
172
pty_get_lock(struct tty_struct * tty,int __user * arg)173 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
174 {
175 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
176
177 return put_user(locked, arg);
178 }
179
180 /* Set the packet mode on a pty */
pty_set_pktmode(struct tty_struct * tty,int __user * arg)181 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
182 {
183 int pktmode;
184
185 if (get_user(pktmode, arg))
186 return -EFAULT;
187
188 spin_lock_irq(&tty->ctrl_lock);
189 if (pktmode) {
190 if (!tty->packet) {
191 tty->link->ctrl_status = 0;
192 smp_mb();
193 tty->packet = 1;
194 }
195 } else
196 tty->packet = 0;
197 spin_unlock_irq(&tty->ctrl_lock);
198
199 return 0;
200 }
201
202 /* Get the packet mode of a pty */
pty_get_pktmode(struct tty_struct * tty,int __user * arg)203 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
204 {
205 int pktmode = tty->packet;
206
207 return put_user(pktmode, arg);
208 }
209
210 /* Send a signal to the slave */
pty_signal(struct tty_struct * tty,int sig)211 static int pty_signal(struct tty_struct *tty, int sig)
212 {
213 struct pid *pgrp;
214
215 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
216 return -EINVAL;
217
218 if (tty->link) {
219 pgrp = tty_get_pgrp(tty->link);
220 if (pgrp)
221 kill_pgrp(pgrp, sig, 1);
222 put_pid(pgrp);
223 }
224 return 0;
225 }
226
pty_flush_buffer(struct tty_struct * tty)227 static void pty_flush_buffer(struct tty_struct *tty)
228 {
229 struct tty_struct *to = tty->link;
230
231 if (!to)
232 return;
233
234 tty_buffer_flush(to, NULL);
235 if (to->packet) {
236 spin_lock_irq(&tty->ctrl_lock);
237 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
238 wake_up_interruptible(&to->read_wait);
239 spin_unlock_irq(&tty->ctrl_lock);
240 }
241 }
242
pty_open(struct tty_struct * tty,struct file * filp)243 static int pty_open(struct tty_struct *tty, struct file *filp)
244 {
245 if (!tty || !tty->link)
246 return -ENODEV;
247
248 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
249 goto out;
250 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
251 goto out;
252 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
253 goto out;
254
255 clear_bit(TTY_IO_ERROR, &tty->flags);
256 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
257 set_bit(TTY_THROTTLED, &tty->flags);
258 return 0;
259
260 out:
261 set_bit(TTY_IO_ERROR, &tty->flags);
262 return -EIO;
263 }
264
pty_set_termios(struct tty_struct * tty,struct ktermios * old_termios)265 static void pty_set_termios(struct tty_struct *tty,
266 struct ktermios *old_termios)
267 {
268 /* See if packet mode change of state. */
269 if (tty->link && tty->link->packet) {
270 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
271 int old_flow = ((old_termios->c_iflag & IXON) &&
272 (old_termios->c_cc[VSTOP] == '\023') &&
273 (old_termios->c_cc[VSTART] == '\021'));
274 int new_flow = (I_IXON(tty) &&
275 STOP_CHAR(tty) == '\023' &&
276 START_CHAR(tty) == '\021');
277 if ((old_flow != new_flow) || extproc) {
278 spin_lock_irq(&tty->ctrl_lock);
279 if (old_flow != new_flow) {
280 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
281 if (new_flow)
282 tty->ctrl_status |= TIOCPKT_DOSTOP;
283 else
284 tty->ctrl_status |= TIOCPKT_NOSTOP;
285 }
286 if (extproc)
287 tty->ctrl_status |= TIOCPKT_IOCTL;
288 spin_unlock_irq(&tty->ctrl_lock);
289 wake_up_interruptible(&tty->link->read_wait);
290 }
291 }
292
293 tty->termios.c_cflag &= ~(CSIZE | PARENB);
294 tty->termios.c_cflag |= (CS8 | CREAD);
295 }
296
297 /**
298 * pty_do_resize - resize event
299 * @tty: tty being resized
300 * @ws: window size being set.
301 *
302 * Update the termios variables and send the necessary signals to
303 * peform a terminal resize correctly
304 */
305
pty_resize(struct tty_struct * tty,struct winsize * ws)306 static int pty_resize(struct tty_struct *tty, struct winsize *ws)
307 {
308 struct pid *pgrp, *rpgrp;
309 struct tty_struct *pty = tty->link;
310
311 /* For a PTY we need to lock the tty side */
312 mutex_lock(&tty->winsize_mutex);
313 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
314 goto done;
315
316 /* Signal the foreground process group of both ptys */
317 pgrp = tty_get_pgrp(tty);
318 rpgrp = tty_get_pgrp(pty);
319
320 if (pgrp)
321 kill_pgrp(pgrp, SIGWINCH, 1);
322 if (rpgrp != pgrp && rpgrp)
323 kill_pgrp(rpgrp, SIGWINCH, 1);
324
325 put_pid(pgrp);
326 put_pid(rpgrp);
327
328 tty->winsize = *ws;
329 pty->winsize = *ws; /* Never used so will go away soon */
330 done:
331 mutex_unlock(&tty->winsize_mutex);
332 return 0;
333 }
334
335 /**
336 * pty_start - start() handler
337 * pty_stop - stop() handler
338 * @tty: tty being flow-controlled
339 *
340 * Propagates the TIOCPKT status to the master pty.
341 *
342 * NB: only the master pty can be in packet mode so only the slave
343 * needs start()/stop() handlers
344 */
pty_start(struct tty_struct * tty)345 static void pty_start(struct tty_struct *tty)
346 {
347 unsigned long flags;
348
349 if (tty->link && tty->link->packet) {
350 spin_lock_irqsave(&tty->ctrl_lock, flags);
351 tty->ctrl_status &= ~TIOCPKT_STOP;
352 tty->ctrl_status |= TIOCPKT_START;
353 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
354 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
355 }
356 }
357
pty_stop(struct tty_struct * tty)358 static void pty_stop(struct tty_struct *tty)
359 {
360 unsigned long flags;
361
362 if (tty->link && tty->link->packet) {
363 spin_lock_irqsave(&tty->ctrl_lock, flags);
364 tty->ctrl_status &= ~TIOCPKT_START;
365 tty->ctrl_status |= TIOCPKT_STOP;
366 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
367 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
368 }
369 }
370
371 /**
372 * pty_common_install - set up the pty pair
373 * @driver: the pty driver
374 * @tty: the tty being instantiated
375 * @legacy: true if this is BSD style
376 *
377 * Perform the initial set up for the tty/pty pair. Called from the
378 * tty layer when the port is first opened.
379 *
380 * Locking: the caller must hold the tty_mutex
381 */
pty_common_install(struct tty_driver * driver,struct tty_struct * tty,bool legacy)382 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
383 bool legacy)
384 {
385 struct tty_struct *o_tty;
386 struct tty_port *ports[2];
387 int idx = tty->index;
388 int retval = -ENOMEM;
389
390 /* Opening the slave first has always returned -EIO */
391 if (driver->subtype != PTY_TYPE_MASTER)
392 return -EIO;
393
394 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
395 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
396 if (!ports[0] || !ports[1])
397 goto err;
398 if (!try_module_get(driver->other->owner)) {
399 /* This cannot in fact currently happen */
400 goto err;
401 }
402 o_tty = alloc_tty_struct(driver->other, idx);
403 if (!o_tty)
404 goto err_put_module;
405
406 tty_set_lock_subclass(o_tty);
407 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
408
409 if (legacy) {
410 /* We always use new tty termios data so we can do this
411 the easy way .. */
412 tty_init_termios(tty);
413 tty_init_termios(o_tty);
414
415 driver->other->ttys[idx] = o_tty;
416 driver->ttys[idx] = tty;
417 } else {
418 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
419 tty->termios = driver->init_termios;
420 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
421 o_tty->termios = driver->other->init_termios;
422 }
423
424 /*
425 * Everything allocated ... set up the o_tty structure.
426 */
427 tty_driver_kref_get(driver->other);
428 /* Establish the links in both directions */
429 tty->link = o_tty;
430 o_tty->link = tty;
431 tty_port_init(ports[0]);
432 tty_port_init(ports[1]);
433 tty_buffer_set_limit(ports[0], 8192);
434 tty_buffer_set_limit(ports[1], 8192);
435 o_tty->port = ports[0];
436 tty->port = ports[1];
437 o_tty->port->itty = o_tty;
438
439 tty_buffer_set_lock_subclass(o_tty->port);
440
441 tty_driver_kref_get(driver);
442 tty->count++;
443 o_tty->count++;
444 return 0;
445
446 err_put_module:
447 module_put(driver->other->owner);
448 err:
449 kfree(ports[0]);
450 kfree(ports[1]);
451 return retval;
452 }
453
pty_cleanup(struct tty_struct * tty)454 static void pty_cleanup(struct tty_struct *tty)
455 {
456 tty_port_put(tty->port);
457 }
458
459 /* Traditional BSD devices */
460 #ifdef CONFIG_LEGACY_PTYS
461
pty_install(struct tty_driver * driver,struct tty_struct * tty)462 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
463 {
464 return pty_common_install(driver, tty, true);
465 }
466
pty_remove(struct tty_driver * driver,struct tty_struct * tty)467 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
468 {
469 struct tty_struct *pair = tty->link;
470
471 driver->ttys[tty->index] = NULL;
472 if (pair)
473 pair->driver->ttys[pair->index] = NULL;
474 }
475
pty_bsd_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)476 static int pty_bsd_ioctl(struct tty_struct *tty,
477 unsigned int cmd, unsigned long arg)
478 {
479 switch (cmd) {
480 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
481 return pty_set_lock(tty, (int __user *) arg);
482 case TIOCGPTLCK: /* Get PT Lock status */
483 return pty_get_lock(tty, (int __user *)arg);
484 case TIOCPKT: /* Set PT packet mode */
485 return pty_set_pktmode(tty, (int __user *)arg);
486 case TIOCGPKT: /* Get PT packet mode */
487 return pty_get_pktmode(tty, (int __user *)arg);
488 case TIOCSIG: /* Send signal to other side of pty */
489 return pty_signal(tty, (int) arg);
490 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
491 return -EINVAL;
492 }
493 return -ENOIOCTLCMD;
494 }
495
496 #ifdef CONFIG_COMPAT
pty_bsd_compat_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)497 static long pty_bsd_compat_ioctl(struct tty_struct *tty,
498 unsigned int cmd, unsigned long arg)
499 {
500 /*
501 * PTY ioctls don't require any special translation between 32-bit and
502 * 64-bit userspace, they are already compatible.
503 */
504 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
505 }
506 #else
507 #define pty_bsd_compat_ioctl NULL
508 #endif
509
510 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
511 /*
512 * not really modular, but the easiest way to keep compat with existing
513 * bootargs behaviour is to continue using module_param here.
514 */
515 module_param(legacy_count, int, 0);
516
517 /*
518 * The master side of a pty can do TIOCSPTLCK and thus
519 * has pty_bsd_ioctl.
520 */
521 static const struct tty_operations master_pty_ops_bsd = {
522 .install = pty_install,
523 .open = pty_open,
524 .close = pty_close,
525 .write = pty_write,
526 .write_room = pty_write_room,
527 .flush_buffer = pty_flush_buffer,
528 .chars_in_buffer = pty_chars_in_buffer,
529 .unthrottle = pty_unthrottle,
530 .ioctl = pty_bsd_ioctl,
531 .compat_ioctl = pty_bsd_compat_ioctl,
532 .cleanup = pty_cleanup,
533 .resize = pty_resize,
534 .remove = pty_remove
535 };
536
537 static const struct tty_operations slave_pty_ops_bsd = {
538 .install = pty_install,
539 .open = pty_open,
540 .close = pty_close,
541 .write = pty_write,
542 .write_room = pty_write_room,
543 .flush_buffer = pty_flush_buffer,
544 .chars_in_buffer = pty_chars_in_buffer,
545 .unthrottle = pty_unthrottle,
546 .set_termios = pty_set_termios,
547 .cleanup = pty_cleanup,
548 .resize = pty_resize,
549 .start = pty_start,
550 .stop = pty_stop,
551 .remove = pty_remove
552 };
553
legacy_pty_init(void)554 static void __init legacy_pty_init(void)
555 {
556 struct tty_driver *pty_driver, *pty_slave_driver;
557
558 if (legacy_count <= 0)
559 return;
560
561 pty_driver = tty_alloc_driver(legacy_count,
562 TTY_DRIVER_RESET_TERMIOS |
563 TTY_DRIVER_REAL_RAW |
564 TTY_DRIVER_DYNAMIC_ALLOC);
565 if (IS_ERR(pty_driver))
566 panic("Couldn't allocate pty driver");
567
568 pty_slave_driver = tty_alloc_driver(legacy_count,
569 TTY_DRIVER_RESET_TERMIOS |
570 TTY_DRIVER_REAL_RAW |
571 TTY_DRIVER_DYNAMIC_ALLOC);
572 if (IS_ERR(pty_slave_driver))
573 panic("Couldn't allocate pty slave driver");
574
575 pty_driver->driver_name = "pty_master";
576 pty_driver->name = "pty";
577 pty_driver->major = PTY_MASTER_MAJOR;
578 pty_driver->minor_start = 0;
579 pty_driver->type = TTY_DRIVER_TYPE_PTY;
580 pty_driver->subtype = PTY_TYPE_MASTER;
581 pty_driver->init_termios = tty_std_termios;
582 pty_driver->init_termios.c_iflag = 0;
583 pty_driver->init_termios.c_oflag = 0;
584 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
585 pty_driver->init_termios.c_lflag = 0;
586 pty_driver->init_termios.c_ispeed = 38400;
587 pty_driver->init_termios.c_ospeed = 38400;
588 pty_driver->other = pty_slave_driver;
589 tty_set_operations(pty_driver, &master_pty_ops_bsd);
590
591 pty_slave_driver->driver_name = "pty_slave";
592 pty_slave_driver->name = "ttyp";
593 pty_slave_driver->major = PTY_SLAVE_MAJOR;
594 pty_slave_driver->minor_start = 0;
595 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
596 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
597 pty_slave_driver->init_termios = tty_std_termios;
598 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
599 pty_slave_driver->init_termios.c_ispeed = 38400;
600 pty_slave_driver->init_termios.c_ospeed = 38400;
601 pty_slave_driver->other = pty_driver;
602 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
603
604 if (tty_register_driver(pty_driver))
605 panic("Couldn't register pty driver");
606 if (tty_register_driver(pty_slave_driver))
607 panic("Couldn't register pty slave driver");
608 }
609 #else
legacy_pty_init(void)610 static inline void legacy_pty_init(void) { }
611 #endif
612
613 /* Unix98 devices */
614 #ifdef CONFIG_UNIX98_PTYS
615 static struct cdev ptmx_cdev;
616
617 /**
618 * ptm_open_peer - open the peer of a pty
619 * @master: the open struct file of the ptmx device node
620 * @tty: the master of the pty being opened
621 * @flags: the flags for open
622 *
623 * Provide a race free way for userspace to open the slave end of a pty
624 * (where they have the master fd and cannot access or trust the mount
625 * namespace /dev/pts was mounted inside).
626 */
ptm_open_peer(struct file * master,struct tty_struct * tty,int flags)627 int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
628 {
629 int fd = -1;
630 struct file *filp;
631 int retval = -EINVAL;
632 struct path path;
633
634 if (tty->driver != ptm_driver)
635 return -EIO;
636
637 fd = get_unused_fd_flags(flags);
638 if (fd < 0) {
639 retval = fd;
640 goto err;
641 }
642
643 /* Compute the slave's path */
644 path.mnt = devpts_mntget(master, tty->driver_data);
645 if (IS_ERR(path.mnt)) {
646 retval = PTR_ERR(path.mnt);
647 goto err_put;
648 }
649 path.dentry = tty->link->driver_data;
650
651 filp = dentry_open(&path, flags, current_cred());
652 mntput(path.mnt);
653 if (IS_ERR(filp)) {
654 retval = PTR_ERR(filp);
655 goto err_put;
656 }
657
658 fd_install(fd, filp);
659 return fd;
660
661 err_put:
662 put_unused_fd(fd);
663 err:
664 return retval;
665 }
666
pty_unix98_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)667 static int pty_unix98_ioctl(struct tty_struct *tty,
668 unsigned int cmd, unsigned long arg)
669 {
670 switch (cmd) {
671 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
672 return pty_set_lock(tty, (int __user *)arg);
673 case TIOCGPTLCK: /* Get PT Lock status */
674 return pty_get_lock(tty, (int __user *)arg);
675 case TIOCPKT: /* Set PT packet mode */
676 return pty_set_pktmode(tty, (int __user *)arg);
677 case TIOCGPKT: /* Get PT packet mode */
678 return pty_get_pktmode(tty, (int __user *)arg);
679 case TIOCGPTN: /* Get PT Number */
680 return put_user(tty->index, (unsigned int __user *)arg);
681 case TIOCSIG: /* Send signal to other side of pty */
682 return pty_signal(tty, (int) arg);
683 }
684
685 return -ENOIOCTLCMD;
686 }
687
688 #ifdef CONFIG_COMPAT
pty_unix98_compat_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)689 static long pty_unix98_compat_ioctl(struct tty_struct *tty,
690 unsigned int cmd, unsigned long arg)
691 {
692 /*
693 * PTY ioctls don't require any special translation between 32-bit and
694 * 64-bit userspace, they are already compatible.
695 */
696 return pty_unix98_ioctl(tty, cmd,
697 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg));
698 }
699 #else
700 #define pty_unix98_compat_ioctl NULL
701 #endif
702
703 /**
704 * ptm_unix98_lookup - find a pty master
705 * @driver: ptm driver
706 * @file: unused
707 * @idx: tty index
708 *
709 * Look up a pty master device. Called under the tty_mutex for now.
710 * This provides our locking.
711 */
712
ptm_unix98_lookup(struct tty_driver * driver,struct file * file,int idx)713 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
714 struct file *file, int idx)
715 {
716 /* Master must be open via /dev/ptmx */
717 return ERR_PTR(-EIO);
718 }
719
720 /**
721 * pts_unix98_lookup - find a pty slave
722 * @driver: pts driver
723 * @file: file pointer to tty
724 * @idx: tty index
725 *
726 * Look up a pty master device. Called under the tty_mutex for now.
727 * This provides our locking for the tty pointer.
728 */
729
pts_unix98_lookup(struct tty_driver * driver,struct file * file,int idx)730 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
731 struct file *file, int idx)
732 {
733 struct tty_struct *tty;
734
735 mutex_lock(&devpts_mutex);
736 tty = devpts_get_priv(file->f_path.dentry);
737 mutex_unlock(&devpts_mutex);
738 /* Master must be open before slave */
739 if (!tty)
740 return ERR_PTR(-EIO);
741 return tty;
742 }
743
pty_unix98_install(struct tty_driver * driver,struct tty_struct * tty)744 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
745 {
746 return pty_common_install(driver, tty, false);
747 }
748
749 /* this is called once with whichever end is closed last */
pty_unix98_remove(struct tty_driver * driver,struct tty_struct * tty)750 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
751 {
752 struct pts_fs_info *fsi;
753
754 if (tty->driver->subtype == PTY_TYPE_MASTER)
755 fsi = tty->driver_data;
756 else
757 fsi = tty->link->driver_data;
758
759 if (fsi) {
760 devpts_kill_index(fsi, tty->index);
761 devpts_release(fsi);
762 }
763 }
764
pty_show_fdinfo(struct tty_struct * tty,struct seq_file * m)765 static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
766 {
767 seq_printf(m, "tty-index:\t%d\n", tty->index);
768 }
769
770 static const struct tty_operations ptm_unix98_ops = {
771 .lookup = ptm_unix98_lookup,
772 .install = pty_unix98_install,
773 .remove = pty_unix98_remove,
774 .open = pty_open,
775 .close = pty_close,
776 .write = pty_write,
777 .write_room = pty_write_room,
778 .flush_buffer = pty_flush_buffer,
779 .chars_in_buffer = pty_chars_in_buffer,
780 .unthrottle = pty_unthrottle,
781 .ioctl = pty_unix98_ioctl,
782 .compat_ioctl = pty_unix98_compat_ioctl,
783 .resize = pty_resize,
784 .cleanup = pty_cleanup,
785 .show_fdinfo = pty_show_fdinfo,
786 };
787
788 static const struct tty_operations pty_unix98_ops = {
789 .lookup = pts_unix98_lookup,
790 .install = pty_unix98_install,
791 .remove = pty_unix98_remove,
792 .open = pty_open,
793 .close = pty_close,
794 .write = pty_write,
795 .write_room = pty_write_room,
796 .flush_buffer = pty_flush_buffer,
797 .chars_in_buffer = pty_chars_in_buffer,
798 .unthrottle = pty_unthrottle,
799 .set_termios = pty_set_termios,
800 .start = pty_start,
801 .stop = pty_stop,
802 .cleanup = pty_cleanup,
803 };
804
805 /**
806 * ptmx_open - open a unix 98 pty master
807 * @inode: inode of device file
808 * @filp: file pointer to tty
809 *
810 * Allocate a unix98 pty master device from the ptmx driver.
811 *
812 * Locking: tty_mutex protects the init_dev work. tty->count should
813 * protect the rest.
814 * allocated_ptys_lock handles the list of free pty numbers
815 */
816
ptmx_open(struct inode * inode,struct file * filp)817 static int ptmx_open(struct inode *inode, struct file *filp)
818 {
819 struct pts_fs_info *fsi;
820 struct tty_struct *tty;
821 struct dentry *dentry;
822 int retval;
823 int index;
824
825 nonseekable_open(inode, filp);
826
827 /* We refuse fsnotify events on ptmx, since it's a shared resource */
828 filp->f_mode |= FMODE_NONOTIFY;
829
830 retval = tty_alloc_file(filp);
831 if (retval)
832 return retval;
833
834 fsi = devpts_acquire(filp);
835 if (IS_ERR(fsi)) {
836 retval = PTR_ERR(fsi);
837 goto out_free_file;
838 }
839
840 /* find a device that is not in use. */
841 mutex_lock(&devpts_mutex);
842 index = devpts_new_index(fsi);
843 mutex_unlock(&devpts_mutex);
844
845 retval = index;
846 if (index < 0)
847 goto out_put_fsi;
848
849
850 mutex_lock(&tty_mutex);
851 tty = tty_init_dev(ptm_driver, index);
852 /* The tty returned here is locked so we can safely
853 drop the mutex */
854 mutex_unlock(&tty_mutex);
855
856 retval = PTR_ERR(tty);
857 if (IS_ERR(tty))
858 goto out;
859
860 /*
861 * From here on out, the tty is "live", and the index and
862 * fsi will be killed/put by the tty_release()
863 */
864 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
865 tty->driver_data = fsi;
866
867 tty_add_file(tty, filp);
868
869 dentry = devpts_pty_new(fsi, index, tty->link);
870 if (IS_ERR(dentry)) {
871 retval = PTR_ERR(dentry);
872 goto err_release;
873 }
874 tty->link->driver_data = dentry;
875
876 retval = ptm_driver->ops->open(tty, filp);
877 if (retval)
878 goto err_release;
879
880 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
881
882 tty_unlock(tty);
883 return 0;
884 err_release:
885 tty_unlock(tty);
886 // This will also put-ref the fsi
887 tty_release(inode, filp);
888 return retval;
889 out:
890 devpts_kill_index(fsi, index);
891 out_put_fsi:
892 devpts_release(fsi);
893 out_free_file:
894 tty_free_file(filp);
895 return retval;
896 }
897
898 static struct file_operations ptmx_fops __ro_after_init;
899
unix98_pty_init(void)900 static void __init unix98_pty_init(void)
901 {
902 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
903 TTY_DRIVER_RESET_TERMIOS |
904 TTY_DRIVER_REAL_RAW |
905 TTY_DRIVER_DYNAMIC_DEV |
906 TTY_DRIVER_DEVPTS_MEM |
907 TTY_DRIVER_DYNAMIC_ALLOC);
908 if (IS_ERR(ptm_driver))
909 panic("Couldn't allocate Unix98 ptm driver");
910 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
911 TTY_DRIVER_RESET_TERMIOS |
912 TTY_DRIVER_REAL_RAW |
913 TTY_DRIVER_DYNAMIC_DEV |
914 TTY_DRIVER_DEVPTS_MEM |
915 TTY_DRIVER_DYNAMIC_ALLOC);
916 if (IS_ERR(pts_driver))
917 panic("Couldn't allocate Unix98 pts driver");
918
919 ptm_driver->driver_name = "pty_master";
920 ptm_driver->name = "ptm";
921 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
922 ptm_driver->minor_start = 0;
923 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
924 ptm_driver->subtype = PTY_TYPE_MASTER;
925 ptm_driver->init_termios = tty_std_termios;
926 ptm_driver->init_termios.c_iflag = 0;
927 ptm_driver->init_termios.c_oflag = 0;
928 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
929 ptm_driver->init_termios.c_lflag = 0;
930 ptm_driver->init_termios.c_ispeed = 38400;
931 ptm_driver->init_termios.c_ospeed = 38400;
932 ptm_driver->other = pts_driver;
933 tty_set_operations(ptm_driver, &ptm_unix98_ops);
934
935 pts_driver->driver_name = "pty_slave";
936 pts_driver->name = "pts";
937 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
938 pts_driver->minor_start = 0;
939 pts_driver->type = TTY_DRIVER_TYPE_PTY;
940 pts_driver->subtype = PTY_TYPE_SLAVE;
941 pts_driver->init_termios = tty_std_termios;
942 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
943 pts_driver->init_termios.c_ispeed = 38400;
944 pts_driver->init_termios.c_ospeed = 38400;
945 pts_driver->other = ptm_driver;
946 tty_set_operations(pts_driver, &pty_unix98_ops);
947
948 if (tty_register_driver(ptm_driver))
949 panic("Couldn't register Unix98 ptm driver");
950 if (tty_register_driver(pts_driver))
951 panic("Couldn't register Unix98 pts driver");
952
953 /* Now create the /dev/ptmx special device */
954 tty_default_fops(&ptmx_fops);
955 ptmx_fops.open = ptmx_open;
956
957 cdev_init(&ptmx_cdev, &ptmx_fops);
958 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
959 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
960 panic("Couldn't register /dev/ptmx driver");
961 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
962 }
963
964 #else
unix98_pty_init(void)965 static inline void unix98_pty_init(void) { }
966 #endif
967
pty_init(void)968 static int __init pty_init(void)
969 {
970 legacy_pty_init();
971 unix98_pty_init();
972 return 0;
973 }
974 device_initcall(pty_init);
975