1 /*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 *
4 * Added support for a Unix98-style ptmx device.
5 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
6 *
7 */
8
9 #include <linux/module.h>
10 #include <linux/errno.h>
11 #include <linux/interrupt.h>
12 #include <linux/tty.h>
13 #include <linux/tty_flip.h>
14 #include <linux/fcntl.h>
15 #include <linux/sched.h>
16 #include <linux/string.h>
17 #include <linux/major.h>
18 #include <linux/mm.h>
19 #include <linux/init.h>
20 #include <linux/device.h>
21 #include <linux/uaccess.h>
22 #include <linux/bitops.h>
23 #include <linux/devpts_fs.h>
24 #include <linux/slab.h>
25 #include <linux/mutex.h>
26 #include <linux/poll.h>
27
28 #undef TTY_DEBUG_HANGUP
29 #ifdef TTY_DEBUG_HANGUP
30 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
31 #else
32 # define tty_debug_hangup(tty, f, args...) do {} while (0)
33 #endif
34
35 #ifdef CONFIG_UNIX98_PTYS
36 static struct tty_driver *ptm_driver;
37 static struct tty_driver *pts_driver;
38 static DEFINE_MUTEX(devpts_mutex);
39 #endif
40
pty_close(struct tty_struct * tty,struct file * filp)41 static void pty_close(struct tty_struct *tty, struct file *filp)
42 {
43 BUG_ON(!tty);
44 if (tty->driver->subtype == PTY_TYPE_MASTER)
45 WARN_ON(tty->count > 1);
46 else {
47 if (test_bit(TTY_IO_ERROR, &tty->flags))
48 return;
49 if (tty->count > 2)
50 return;
51 }
52 set_bit(TTY_IO_ERROR, &tty->flags);
53 wake_up_interruptible(&tty->read_wait);
54 wake_up_interruptible(&tty->write_wait);
55 spin_lock_irq(&tty->ctrl_lock);
56 tty->packet = 0;
57 spin_unlock_irq(&tty->ctrl_lock);
58 /* Review - krefs on tty_link ?? */
59 if (!tty->link)
60 return;
61 set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
62 wake_up_interruptible(&tty->link->read_wait);
63 wake_up_interruptible(&tty->link->write_wait);
64 if (tty->driver->subtype == PTY_TYPE_MASTER) {
65 set_bit(TTY_OTHER_CLOSED, &tty->flags);
66 #ifdef CONFIG_UNIX98_PTYS
67 if (tty->driver == ptm_driver) {
68 mutex_lock(&devpts_mutex);
69 if (tty->link->driver_data)
70 devpts_pty_kill(tty->link->driver_data);
71 mutex_unlock(&devpts_mutex);
72 }
73 #endif
74 tty_vhangup(tty->link);
75 }
76 }
77
78 /*
79 * The unthrottle routine is called by the line discipline to signal
80 * that it can receive more characters. For PTY's, the TTY_THROTTLED
81 * flag is always set, to force the line discipline to always call the
82 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
83 * characters in the queue. This is necessary since each time this
84 * happens, we need to wake up any sleeping processes that could be
85 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
86 * for the pty buffer to be drained.
87 */
pty_unthrottle(struct tty_struct * tty)88 static void pty_unthrottle(struct tty_struct *tty)
89 {
90 tty_wakeup(tty->link);
91 set_bit(TTY_THROTTLED, &tty->flags);
92 }
93
94 /**
95 * pty_write - write to a pty
96 * @tty: the tty we write from
97 * @buf: kernel buffer of data
98 * @count: bytes to write
99 *
100 * Our "hardware" write method. Data is coming from the ldisc which
101 * may be in a non sleeping state. We simply throw this at the other
102 * end of the link as if we were an IRQ handler receiving stuff for
103 * the other side of the pty/tty pair.
104 */
105
pty_write(struct tty_struct * tty,const unsigned char * buf,int c)106 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
107 {
108 struct tty_struct *to = tty->link;
109 unsigned long flags;
110
111 if (tty->stopped)
112 return 0;
113
114 if (c > 0) {
115 spin_lock_irqsave(&to->port->lock, flags);
116 /* Stuff the data into the input queue of the other end */
117 c = tty_insert_flip_string(to->port, buf, c);
118 spin_unlock_irqrestore(&to->port->lock, flags);
119 /* And shovel */
120 if (c)
121 tty_flip_buffer_push(to->port);
122 }
123 return c;
124 }
125
126 /**
127 * pty_write_room - write space
128 * @tty: tty we are writing from
129 *
130 * Report how many bytes the ldisc can send into the queue for
131 * the other device.
132 */
133
pty_write_room(struct tty_struct * tty)134 static int pty_write_room(struct tty_struct *tty)
135 {
136 if (tty->stopped)
137 return 0;
138 return tty_buffer_space_avail(tty->link->port);
139 }
140
141 /**
142 * pty_chars_in_buffer - characters currently in our tx queue
143 * @tty: our tty
144 *
145 * Report how much we have in the transmit queue. As everything is
146 * instantly at the other end this is easy to implement.
147 */
148
pty_chars_in_buffer(struct tty_struct * tty)149 static int pty_chars_in_buffer(struct tty_struct *tty)
150 {
151 return 0;
152 }
153
154 /* Set the lock flag on a pty */
pty_set_lock(struct tty_struct * tty,int __user * arg)155 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
156 {
157 int val;
158 if (get_user(val, arg))
159 return -EFAULT;
160 if (val)
161 set_bit(TTY_PTY_LOCK, &tty->flags);
162 else
163 clear_bit(TTY_PTY_LOCK, &tty->flags);
164 return 0;
165 }
166
pty_get_lock(struct tty_struct * tty,int __user * arg)167 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
168 {
169 int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
170 return put_user(locked, arg);
171 }
172
173 /* Set the packet mode on a pty */
pty_set_pktmode(struct tty_struct * tty,int __user * arg)174 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
175 {
176 int pktmode;
177
178 if (get_user(pktmode, arg))
179 return -EFAULT;
180
181 spin_lock_irq(&tty->ctrl_lock);
182 if (pktmode) {
183 if (!tty->packet) {
184 tty->link->ctrl_status = 0;
185 smp_mb();
186 tty->packet = 1;
187 }
188 } else
189 tty->packet = 0;
190 spin_unlock_irq(&tty->ctrl_lock);
191
192 return 0;
193 }
194
195 /* Get the packet mode of a pty */
pty_get_pktmode(struct tty_struct * tty,int __user * arg)196 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
197 {
198 int pktmode = tty->packet;
199 return put_user(pktmode, arg);
200 }
201
202 /* Send a signal to the slave */
pty_signal(struct tty_struct * tty,int sig)203 static int pty_signal(struct tty_struct *tty, int sig)
204 {
205 struct pid *pgrp;
206
207 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
208 return -EINVAL;
209
210 if (tty->link) {
211 pgrp = tty_get_pgrp(tty->link);
212 if (pgrp)
213 kill_pgrp(pgrp, sig, 1);
214 put_pid(pgrp);
215 }
216 return 0;
217 }
218
pty_flush_buffer(struct tty_struct * tty)219 static void pty_flush_buffer(struct tty_struct *tty)
220 {
221 struct tty_struct *to = tty->link;
222
223 if (!to)
224 return;
225
226 tty_buffer_flush(to, NULL);
227 if (to->packet) {
228 spin_lock_irq(&tty->ctrl_lock);
229 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
230 wake_up_interruptible(&to->read_wait);
231 spin_unlock_irq(&tty->ctrl_lock);
232 }
233 }
234
pty_open(struct tty_struct * tty,struct file * filp)235 static int pty_open(struct tty_struct *tty, struct file *filp)
236 {
237 if (!tty || !tty->link)
238 return -ENODEV;
239
240 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
241 goto out;
242 if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
243 goto out;
244 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
245 goto out;
246
247 clear_bit(TTY_IO_ERROR, &tty->flags);
248 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
249 set_bit(TTY_THROTTLED, &tty->flags);
250 return 0;
251
252 out:
253 set_bit(TTY_IO_ERROR, &tty->flags);
254 return -EIO;
255 }
256
pty_set_termios(struct tty_struct * tty,struct ktermios * old_termios)257 static void pty_set_termios(struct tty_struct *tty,
258 struct ktermios *old_termios)
259 {
260 /* See if packet mode change of state. */
261 if (tty->link && tty->link->packet) {
262 int extproc = (old_termios->c_lflag & EXTPROC) |
263 (tty->termios.c_lflag & EXTPROC);
264 int old_flow = ((old_termios->c_iflag & IXON) &&
265 (old_termios->c_cc[VSTOP] == '\023') &&
266 (old_termios->c_cc[VSTART] == '\021'));
267 int new_flow = (I_IXON(tty) &&
268 STOP_CHAR(tty) == '\023' &&
269 START_CHAR(tty) == '\021');
270 if ((old_flow != new_flow) || extproc) {
271 spin_lock_irq(&tty->ctrl_lock);
272 if (old_flow != new_flow) {
273 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
274 if (new_flow)
275 tty->ctrl_status |= TIOCPKT_DOSTOP;
276 else
277 tty->ctrl_status |= TIOCPKT_NOSTOP;
278 }
279 if (extproc)
280 tty->ctrl_status |= TIOCPKT_IOCTL;
281 spin_unlock_irq(&tty->ctrl_lock);
282 wake_up_interruptible(&tty->link->read_wait);
283 }
284 }
285
286 tty->termios.c_cflag &= ~(CSIZE | PARENB);
287 tty->termios.c_cflag |= (CS8 | CREAD);
288 }
289
290 /**
291 * pty_do_resize - resize event
292 * @tty: tty being resized
293 * @ws: window size being set.
294 *
295 * Update the termios variables and send the necessary signals to
296 * peform a terminal resize correctly
297 */
298
pty_resize(struct tty_struct * tty,struct winsize * ws)299 static int pty_resize(struct tty_struct *tty, struct winsize *ws)
300 {
301 struct pid *pgrp, *rpgrp;
302 struct tty_struct *pty = tty->link;
303
304 /* For a PTY we need to lock the tty side */
305 mutex_lock(&tty->winsize_mutex);
306 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
307 goto done;
308
309 /* Signal the foreground process group of both ptys */
310 pgrp = tty_get_pgrp(tty);
311 rpgrp = tty_get_pgrp(pty);
312
313 if (pgrp)
314 kill_pgrp(pgrp, SIGWINCH, 1);
315 if (rpgrp != pgrp && rpgrp)
316 kill_pgrp(rpgrp, SIGWINCH, 1);
317
318 put_pid(pgrp);
319 put_pid(rpgrp);
320
321 tty->winsize = *ws;
322 pty->winsize = *ws; /* Never used so will go away soon */
323 done:
324 mutex_unlock(&tty->winsize_mutex);
325 return 0;
326 }
327
328 /**
329 * pty_start - start() handler
330 * pty_stop - stop() handler
331 * @tty: tty being flow-controlled
332 *
333 * Propagates the TIOCPKT status to the master pty.
334 *
335 * NB: only the master pty can be in packet mode so only the slave
336 * needs start()/stop() handlers
337 */
pty_start(struct tty_struct * tty)338 static void pty_start(struct tty_struct *tty)
339 {
340 unsigned long flags;
341
342 if (tty->link && tty->link->packet) {
343 spin_lock_irqsave(&tty->ctrl_lock, flags);
344 tty->ctrl_status &= ~TIOCPKT_STOP;
345 tty->ctrl_status |= TIOCPKT_START;
346 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
347 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
348 }
349 }
350
pty_stop(struct tty_struct * tty)351 static void pty_stop(struct tty_struct *tty)
352 {
353 unsigned long flags;
354
355 if (tty->link && tty->link->packet) {
356 spin_lock_irqsave(&tty->ctrl_lock, flags);
357 tty->ctrl_status &= ~TIOCPKT_START;
358 tty->ctrl_status |= TIOCPKT_STOP;
359 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
360 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
361 }
362 }
363
364 /**
365 * pty_common_install - set up the pty pair
366 * @driver: the pty driver
367 * @tty: the tty being instantiated
368 * @legacy: true if this is BSD style
369 *
370 * Perform the initial set up for the tty/pty pair. Called from the
371 * tty layer when the port is first opened.
372 *
373 * Locking: the caller must hold the tty_mutex
374 */
pty_common_install(struct tty_driver * driver,struct tty_struct * tty,bool legacy)375 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
376 bool legacy)
377 {
378 struct tty_struct *o_tty;
379 struct tty_port *ports[2];
380 int idx = tty->index;
381 int retval = -ENOMEM;
382
383 /* Opening the slave first has always returned -EIO */
384 if (driver->subtype != PTY_TYPE_MASTER)
385 return -EIO;
386
387 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
388 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
389 if (!ports[0] || !ports[1])
390 goto err;
391 if (!try_module_get(driver->other->owner)) {
392 /* This cannot in fact currently happen */
393 goto err;
394 }
395 o_tty = alloc_tty_struct(driver->other, idx);
396 if (!o_tty)
397 goto err_put_module;
398
399 tty_set_lock_subclass(o_tty);
400 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
401
402 if (legacy) {
403 /* We always use new tty termios data so we can do this
404 the easy way .. */
405 retval = tty_init_termios(tty);
406 if (retval)
407 goto err_deinit_tty;
408
409 retval = tty_init_termios(o_tty);
410 if (retval)
411 goto err_free_termios;
412
413 driver->other->ttys[idx] = o_tty;
414 driver->ttys[idx] = tty;
415 } else {
416 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
417 tty->termios = driver->init_termios;
418 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
419 o_tty->termios = driver->other->init_termios;
420 }
421
422 /*
423 * Everything allocated ... set up the o_tty structure.
424 */
425 tty_driver_kref_get(driver->other);
426 /* Establish the links in both directions */
427 tty->link = o_tty;
428 o_tty->link = tty;
429 tty_port_init(ports[0]);
430 tty_port_init(ports[1]);
431 tty_buffer_set_limit(ports[0], 8192);
432 tty_buffer_set_limit(ports[1], 8192);
433 o_tty->port = ports[0];
434 tty->port = ports[1];
435 o_tty->port->itty = o_tty;
436
437 tty_buffer_set_lock_subclass(o_tty->port);
438
439 tty_driver_kref_get(driver);
440 tty->count++;
441 o_tty->count++;
442 return 0;
443 err_free_termios:
444 if (legacy)
445 tty_free_termios(tty);
446 err_deinit_tty:
447 deinitialize_tty_struct(o_tty);
448 free_tty_struct(o_tty);
449 err_put_module:
450 module_put(driver->other->owner);
451 err:
452 kfree(ports[0]);
453 kfree(ports[1]);
454 return retval;
455 }
456
pty_cleanup(struct tty_struct * tty)457 static void pty_cleanup(struct tty_struct *tty)
458 {
459 tty_port_put(tty->port);
460 }
461
462 /* Traditional BSD devices */
463 #ifdef CONFIG_LEGACY_PTYS
464
pty_install(struct tty_driver * driver,struct tty_struct * tty)465 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
466 {
467 return pty_common_install(driver, tty, true);
468 }
469
pty_remove(struct tty_driver * driver,struct tty_struct * tty)470 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
471 {
472 struct tty_struct *pair = tty->link;
473 driver->ttys[tty->index] = NULL;
474 if (pair)
475 pair->driver->ttys[pair->index] = NULL;
476 }
477
pty_bsd_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)478 static int pty_bsd_ioctl(struct tty_struct *tty,
479 unsigned int cmd, unsigned long arg)
480 {
481 switch (cmd) {
482 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
483 return pty_set_lock(tty, (int __user *) arg);
484 case TIOCGPTLCK: /* Get PT Lock status */
485 return pty_get_lock(tty, (int __user *)arg);
486 case TIOCPKT: /* Set PT packet mode */
487 return pty_set_pktmode(tty, (int __user *)arg);
488 case TIOCGPKT: /* Get PT packet mode */
489 return pty_get_pktmode(tty, (int __user *)arg);
490 case TIOCSIG: /* Send signal to other side of pty */
491 return pty_signal(tty, (int) arg);
492 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
493 return -EINVAL;
494 }
495 return -ENOIOCTLCMD;
496 }
497
498 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
499 /*
500 * not really modular, but the easiest way to keep compat with existing
501 * bootargs behaviour is to continue using module_param here.
502 */
503 module_param(legacy_count, int, 0);
504
505 /*
506 * The master side of a pty can do TIOCSPTLCK and thus
507 * has pty_bsd_ioctl.
508 */
509 static const struct tty_operations master_pty_ops_bsd = {
510 .install = pty_install,
511 .open = pty_open,
512 .close = pty_close,
513 .write = pty_write,
514 .write_room = pty_write_room,
515 .flush_buffer = pty_flush_buffer,
516 .chars_in_buffer = pty_chars_in_buffer,
517 .unthrottle = pty_unthrottle,
518 .ioctl = pty_bsd_ioctl,
519 .cleanup = pty_cleanup,
520 .resize = pty_resize,
521 .remove = pty_remove
522 };
523
524 static const struct tty_operations slave_pty_ops_bsd = {
525 .install = pty_install,
526 .open = pty_open,
527 .close = pty_close,
528 .write = pty_write,
529 .write_room = pty_write_room,
530 .flush_buffer = pty_flush_buffer,
531 .chars_in_buffer = pty_chars_in_buffer,
532 .unthrottle = pty_unthrottle,
533 .set_termios = pty_set_termios,
534 .cleanup = pty_cleanup,
535 .resize = pty_resize,
536 .start = pty_start,
537 .stop = pty_stop,
538 .remove = pty_remove
539 };
540
legacy_pty_init(void)541 static void __init legacy_pty_init(void)
542 {
543 struct tty_driver *pty_driver, *pty_slave_driver;
544
545 if (legacy_count <= 0)
546 return;
547
548 pty_driver = tty_alloc_driver(legacy_count,
549 TTY_DRIVER_RESET_TERMIOS |
550 TTY_DRIVER_REAL_RAW |
551 TTY_DRIVER_DYNAMIC_ALLOC);
552 if (IS_ERR(pty_driver))
553 panic("Couldn't allocate pty driver");
554
555 pty_slave_driver = tty_alloc_driver(legacy_count,
556 TTY_DRIVER_RESET_TERMIOS |
557 TTY_DRIVER_REAL_RAW |
558 TTY_DRIVER_DYNAMIC_ALLOC);
559 if (IS_ERR(pty_slave_driver))
560 panic("Couldn't allocate pty slave driver");
561
562 pty_driver->driver_name = "pty_master";
563 pty_driver->name = "pty";
564 pty_driver->major = PTY_MASTER_MAJOR;
565 pty_driver->minor_start = 0;
566 pty_driver->type = TTY_DRIVER_TYPE_PTY;
567 pty_driver->subtype = PTY_TYPE_MASTER;
568 pty_driver->init_termios = tty_std_termios;
569 pty_driver->init_termios.c_iflag = 0;
570 pty_driver->init_termios.c_oflag = 0;
571 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
572 pty_driver->init_termios.c_lflag = 0;
573 pty_driver->init_termios.c_ispeed = 38400;
574 pty_driver->init_termios.c_ospeed = 38400;
575 pty_driver->other = pty_slave_driver;
576 tty_set_operations(pty_driver, &master_pty_ops_bsd);
577
578 pty_slave_driver->driver_name = "pty_slave";
579 pty_slave_driver->name = "ttyp";
580 pty_slave_driver->major = PTY_SLAVE_MAJOR;
581 pty_slave_driver->minor_start = 0;
582 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
583 pty_slave_driver->subtype = PTY_TYPE_SLAVE;
584 pty_slave_driver->init_termios = tty_std_termios;
585 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
586 pty_slave_driver->init_termios.c_ispeed = 38400;
587 pty_slave_driver->init_termios.c_ospeed = 38400;
588 pty_slave_driver->other = pty_driver;
589 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
590
591 if (tty_register_driver(pty_driver))
592 panic("Couldn't register pty driver");
593 if (tty_register_driver(pty_slave_driver))
594 panic("Couldn't register pty slave driver");
595 }
596 #else
legacy_pty_init(void)597 static inline void legacy_pty_init(void) { }
598 #endif
599
600 /* Unix98 devices */
601 #ifdef CONFIG_UNIX98_PTYS
602
603 static struct cdev ptmx_cdev;
604
pty_unix98_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)605 static int pty_unix98_ioctl(struct tty_struct *tty,
606 unsigned int cmd, unsigned long arg)
607 {
608 switch (cmd) {
609 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
610 return pty_set_lock(tty, (int __user *)arg);
611 case TIOCGPTLCK: /* Get PT Lock status */
612 return pty_get_lock(tty, (int __user *)arg);
613 case TIOCPKT: /* Set PT packet mode */
614 return pty_set_pktmode(tty, (int __user *)arg);
615 case TIOCGPKT: /* Get PT packet mode */
616 return pty_get_pktmode(tty, (int __user *)arg);
617 case TIOCGPTN: /* Get PT Number */
618 return put_user(tty->index, (unsigned int __user *)arg);
619 case TIOCSIG: /* Send signal to other side of pty */
620 return pty_signal(tty, (int) arg);
621 }
622
623 return -ENOIOCTLCMD;
624 }
625
626 /**
627 * ptm_unix98_lookup - find a pty master
628 * @driver: ptm driver
629 * @idx: tty index
630 *
631 * Look up a pty master device. Called under the tty_mutex for now.
632 * This provides our locking.
633 */
634
ptm_unix98_lookup(struct tty_driver * driver,struct inode * ptm_inode,int idx)635 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
636 struct inode *ptm_inode, int idx)
637 {
638 /* Master must be open via /dev/ptmx */
639 return ERR_PTR(-EIO);
640 }
641
642 /**
643 * pts_unix98_lookup - find a pty slave
644 * @driver: pts driver
645 * @idx: tty index
646 *
647 * Look up a pty master device. Called under the tty_mutex for now.
648 * This provides our locking for the tty pointer.
649 */
650
pts_unix98_lookup(struct tty_driver * driver,struct inode * pts_inode,int idx)651 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
652 struct inode *pts_inode, int idx)
653 {
654 struct tty_struct *tty;
655
656 mutex_lock(&devpts_mutex);
657 tty = devpts_get_priv(pts_inode);
658 mutex_unlock(&devpts_mutex);
659 /* Master must be open before slave */
660 if (!tty)
661 return ERR_PTR(-EIO);
662 return tty;
663 }
664
665 /* We have no need to install and remove our tty objects as devpts does all
666 the work for us */
667
pty_unix98_install(struct tty_driver * driver,struct tty_struct * tty)668 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
669 {
670 return pty_common_install(driver, tty, false);
671 }
672
pty_unix98_remove(struct tty_driver * driver,struct tty_struct * tty)673 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
674 {
675 }
676
677 /* this is called once with whichever end is closed last */
pty_unix98_shutdown(struct tty_struct * tty)678 static void pty_unix98_shutdown(struct tty_struct *tty)
679 {
680 struct pts_fs_info *fsi;
681
682 if (tty->driver->subtype == PTY_TYPE_MASTER)
683 fsi = tty->driver_data;
684 else
685 fsi = tty->link->driver_data;
686 devpts_kill_index(fsi, tty->index);
687 devpts_put_ref(fsi);
688 }
689
690 static const struct tty_operations ptm_unix98_ops = {
691 .lookup = ptm_unix98_lookup,
692 .install = pty_unix98_install,
693 .remove = pty_unix98_remove,
694 .open = pty_open,
695 .close = pty_close,
696 .write = pty_write,
697 .write_room = pty_write_room,
698 .flush_buffer = pty_flush_buffer,
699 .chars_in_buffer = pty_chars_in_buffer,
700 .unthrottle = pty_unthrottle,
701 .ioctl = pty_unix98_ioctl,
702 .resize = pty_resize,
703 .shutdown = pty_unix98_shutdown,
704 .cleanup = pty_cleanup
705 };
706
707 static const struct tty_operations pty_unix98_ops = {
708 .lookup = pts_unix98_lookup,
709 .install = pty_unix98_install,
710 .remove = pty_unix98_remove,
711 .open = pty_open,
712 .close = pty_close,
713 .write = pty_write,
714 .write_room = pty_write_room,
715 .flush_buffer = pty_flush_buffer,
716 .chars_in_buffer = pty_chars_in_buffer,
717 .unthrottle = pty_unthrottle,
718 .set_termios = pty_set_termios,
719 .start = pty_start,
720 .stop = pty_stop,
721 .shutdown = pty_unix98_shutdown,
722 .cleanup = pty_cleanup,
723 };
724
725 /**
726 * ptmx_open - open a unix 98 pty master
727 * @inode: inode of device file
728 * @filp: file pointer to tty
729 *
730 * Allocate a unix98 pty master device from the ptmx driver.
731 *
732 * Locking: tty_mutex protects the init_dev work. tty->count should
733 * protect the rest.
734 * allocated_ptys_lock handles the list of free pty numbers
735 */
736
ptmx_open(struct inode * inode,struct file * filp)737 static int ptmx_open(struct inode *inode, struct file *filp)
738 {
739 struct pts_fs_info *fsi;
740 struct tty_struct *tty;
741 struct inode *slave_inode;
742 int retval;
743 int index;
744
745 nonseekable_open(inode, filp);
746
747 /* We refuse fsnotify events on ptmx, since it's a shared resource */
748 filp->f_mode |= FMODE_NONOTIFY;
749
750 retval = tty_alloc_file(filp);
751 if (retval)
752 return retval;
753
754 fsi = devpts_get_ref(inode, filp);
755 retval = -ENODEV;
756 if (!fsi)
757 goto out_free_file;
758
759 /* find a device that is not in use. */
760 mutex_lock(&devpts_mutex);
761 index = devpts_new_index(fsi);
762 mutex_unlock(&devpts_mutex);
763
764 retval = index;
765 if (index < 0)
766 goto out_put_ref;
767
768
769 mutex_lock(&tty_mutex);
770 tty = tty_init_dev(ptm_driver, index);
771 /* The tty returned here is locked so we can safely
772 drop the mutex */
773 mutex_unlock(&tty_mutex);
774
775 retval = PTR_ERR(tty);
776 if (IS_ERR(tty))
777 goto out;
778
779 /*
780 * From here on out, the tty is "live", and the index and
781 * fsi will be killed/put by the tty_release()
782 */
783 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
784 tty->driver_data = fsi;
785
786 tty_add_file(tty, filp);
787
788 slave_inode = devpts_pty_new(fsi,
789 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
790 tty->link);
791 if (IS_ERR(slave_inode)) {
792 retval = PTR_ERR(slave_inode);
793 goto err_release;
794 }
795 tty->link->driver_data = slave_inode;
796
797 retval = ptm_driver->ops->open(tty, filp);
798 if (retval)
799 goto err_release;
800
801 tty_debug_hangup(tty, "(tty count=%d)\n", tty->count);
802
803 tty_unlock(tty);
804 return 0;
805 err_release:
806 tty_unlock(tty);
807 // This will also put-ref the fsi
808 tty_release(inode, filp);
809 return retval;
810 out:
811 devpts_kill_index(fsi, index);
812 out_put_ref:
813 devpts_put_ref(fsi);
814 out_free_file:
815 tty_free_file(filp);
816 return retval;
817 }
818
819 static struct file_operations ptmx_fops;
820
unix98_pty_init(void)821 static void __init unix98_pty_init(void)
822 {
823 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
824 TTY_DRIVER_RESET_TERMIOS |
825 TTY_DRIVER_REAL_RAW |
826 TTY_DRIVER_DYNAMIC_DEV |
827 TTY_DRIVER_DEVPTS_MEM |
828 TTY_DRIVER_DYNAMIC_ALLOC);
829 if (IS_ERR(ptm_driver))
830 panic("Couldn't allocate Unix98 ptm driver");
831 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
832 TTY_DRIVER_RESET_TERMIOS |
833 TTY_DRIVER_REAL_RAW |
834 TTY_DRIVER_DYNAMIC_DEV |
835 TTY_DRIVER_DEVPTS_MEM |
836 TTY_DRIVER_DYNAMIC_ALLOC);
837 if (IS_ERR(pts_driver))
838 panic("Couldn't allocate Unix98 pts driver");
839
840 ptm_driver->driver_name = "pty_master";
841 ptm_driver->name = "ptm";
842 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
843 ptm_driver->minor_start = 0;
844 ptm_driver->type = TTY_DRIVER_TYPE_PTY;
845 ptm_driver->subtype = PTY_TYPE_MASTER;
846 ptm_driver->init_termios = tty_std_termios;
847 ptm_driver->init_termios.c_iflag = 0;
848 ptm_driver->init_termios.c_oflag = 0;
849 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
850 ptm_driver->init_termios.c_lflag = 0;
851 ptm_driver->init_termios.c_ispeed = 38400;
852 ptm_driver->init_termios.c_ospeed = 38400;
853 ptm_driver->other = pts_driver;
854 tty_set_operations(ptm_driver, &ptm_unix98_ops);
855
856 pts_driver->driver_name = "pty_slave";
857 pts_driver->name = "pts";
858 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
859 pts_driver->minor_start = 0;
860 pts_driver->type = TTY_DRIVER_TYPE_PTY;
861 pts_driver->subtype = PTY_TYPE_SLAVE;
862 pts_driver->init_termios = tty_std_termios;
863 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
864 pts_driver->init_termios.c_ispeed = 38400;
865 pts_driver->init_termios.c_ospeed = 38400;
866 pts_driver->other = ptm_driver;
867 tty_set_operations(pts_driver, &pty_unix98_ops);
868
869 if (tty_register_driver(ptm_driver))
870 panic("Couldn't register Unix98 ptm driver");
871 if (tty_register_driver(pts_driver))
872 panic("Couldn't register Unix98 pts driver");
873
874 /* Now create the /dev/ptmx special device */
875 tty_default_fops(&ptmx_fops);
876 ptmx_fops.open = ptmx_open;
877
878 cdev_init(&ptmx_cdev, &ptmx_fops);
879 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
880 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
881 panic("Couldn't register /dev/ptmx driver");
882 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
883 }
884
885 #else
unix98_pty_init(void)886 static inline void unix98_pty_init(void) { }
887 #endif
888
pty_init(void)889 static int __init pty_init(void)
890 {
891 legacy_pty_init();
892 unix98_pty_init();
893 return 0;
894 }
895 device_initcall(pty_init);
896