1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
4  *
5  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
6  * which can be dynamically activated and de-activated by the line
7  * discipline handling modules (like SLIP).
8  */
9 
10 #include <linux/types.h>
11 #include <linux/termios.h>
12 #include <linux/errno.h>
13 #include <linux/sched/signal.h>
14 #include <linux/kernel.h>
15 #include <linux/major.h>
16 #include <linux/tty.h>
17 #include <linux/fcntl.h>
18 #include <linux/string.h>
19 #include <linux/mm.h>
20 #include <linux/module.h>
21 #include <linux/bitops.h>
22 #include <linux/mutex.h>
23 #include <linux/compat.h>
24 #include "tty.h"
25 
26 #include <asm/io.h>
27 #include <linux/uaccess.h>
28 
29 #undef TTY_DEBUG_WAIT_UNTIL_SENT
30 
31 #ifdef TTY_DEBUG_WAIT_UNTIL_SENT
32 # define tty_debug_wait_until_sent(tty, f, args...)    tty_debug(tty, f, ##args)
33 #else
34 # define tty_debug_wait_until_sent(tty, f, args...)    do {} while (0)
35 #endif
36 
37 #undef	DEBUG
38 
39 /*
40  * Internal flag options for termios setting behavior
41  */
42 #define TERMIOS_FLUSH	1
43 #define TERMIOS_WAIT	2
44 #define TERMIOS_TERMIO	4
45 #define TERMIOS_OLD	8
46 
47 
48 /**
49  *	tty_chars_in_buffer	-	characters pending
50  *	@tty: terminal
51  *
52  *	Return the number of bytes of data in the device private
53  *	output queue. If no private method is supplied there is assumed
54  *	to be no queue on the device.
55  */
56 
tty_chars_in_buffer(struct tty_struct * tty)57 unsigned int tty_chars_in_buffer(struct tty_struct *tty)
58 {
59 	if (tty->ops->chars_in_buffer)
60 		return tty->ops->chars_in_buffer(tty);
61 	return 0;
62 }
63 EXPORT_SYMBOL(tty_chars_in_buffer);
64 
65 /**
66  *	tty_write_room		-	write queue space
67  *	@tty: terminal
68  *
69  *	Return the number of bytes that can be queued to this device
70  *	at the present time. The result should be treated as a guarantee
71  *	and the driver cannot offer a value it later shrinks by more than
72  *	the number of bytes written. If no method is provided 2K is always
73  *	returned and data may be lost as there will be no flow control.
74  */
75 
tty_write_room(struct tty_struct * tty)76 unsigned int tty_write_room(struct tty_struct *tty)
77 {
78 	if (tty->ops->write_room)
79 		return tty->ops->write_room(tty);
80 	return 2048;
81 }
82 EXPORT_SYMBOL(tty_write_room);
83 
84 /**
85  *	tty_driver_flush_buffer	-	discard internal buffer
86  *	@tty: terminal
87  *
88  *	Discard the internal output buffer for this device. If no method
89  *	is provided then either the buffer cannot be hardware flushed or
90  *	there is no buffer driver side.
91  */
tty_driver_flush_buffer(struct tty_struct * tty)92 void tty_driver_flush_buffer(struct tty_struct *tty)
93 {
94 	if (tty->ops->flush_buffer)
95 		tty->ops->flush_buffer(tty);
96 }
97 EXPORT_SYMBOL(tty_driver_flush_buffer);
98 
99 /**
100  *	tty_unthrottle		-	flow control
101  *	@tty: terminal
102  *
103  *	Indicate that a tty may continue transmitting data down the stack.
104  *	Takes the termios rwsem to protect against parallel throttle/unthrottle
105  *	and also to ensure the driver can consistently reference its own
106  *	termios data at this point when implementing software flow control.
107  *
108  *	Drivers should however remember that the stack can issue a throttle,
109  *	then change flow control method, then unthrottle.
110  */
111 
tty_unthrottle(struct tty_struct * tty)112 void tty_unthrottle(struct tty_struct *tty)
113 {
114 	down_write(&tty->termios_rwsem);
115 	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
116 	    tty->ops->unthrottle)
117 		tty->ops->unthrottle(tty);
118 	tty->flow_change = 0;
119 	up_write(&tty->termios_rwsem);
120 }
121 EXPORT_SYMBOL(tty_unthrottle);
122 
123 /**
124  *	tty_throttle_safe	-	flow control
125  *	@tty: terminal
126  *
127  *	Indicate that a tty should stop transmitting data down the stack.
128  *	tty_throttle_safe will only attempt throttle if tty->flow_change is
129  *	TTY_THROTTLE_SAFE. Prevents an accidental throttle due to race
130  *	conditions when throttling is conditional on factors evaluated prior to
131  *	throttling.
132  *
133  *	Returns 0 if tty is throttled (or was already throttled)
134  */
135 
tty_throttle_safe(struct tty_struct * tty)136 int tty_throttle_safe(struct tty_struct *tty)
137 {
138 	int ret = 0;
139 
140 	mutex_lock(&tty->throttle_mutex);
141 	if (!tty_throttled(tty)) {
142 		if (tty->flow_change != TTY_THROTTLE_SAFE)
143 			ret = 1;
144 		else {
145 			set_bit(TTY_THROTTLED, &tty->flags);
146 			if (tty->ops->throttle)
147 				tty->ops->throttle(tty);
148 		}
149 	}
150 	mutex_unlock(&tty->throttle_mutex);
151 
152 	return ret;
153 }
154 
155 /**
156  *	tty_unthrottle_safe	-	flow control
157  *	@tty: terminal
158  *
159  *	Similar to tty_unthrottle() but will only attempt unthrottle
160  *	if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
161  *	unthrottle due to race conditions when unthrottling is conditional
162  *	on factors evaluated prior to unthrottling.
163  *
164  *	Returns 0 if tty is unthrottled (or was already unthrottled)
165  */
166 
tty_unthrottle_safe(struct tty_struct * tty)167 int tty_unthrottle_safe(struct tty_struct *tty)
168 {
169 	int ret = 0;
170 
171 	mutex_lock(&tty->throttle_mutex);
172 	if (tty_throttled(tty)) {
173 		if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
174 			ret = 1;
175 		else {
176 			clear_bit(TTY_THROTTLED, &tty->flags);
177 			if (tty->ops->unthrottle)
178 				tty->ops->unthrottle(tty);
179 		}
180 	}
181 	mutex_unlock(&tty->throttle_mutex);
182 
183 	return ret;
184 }
185 
186 /**
187  *	tty_wait_until_sent	-	wait for I/O to finish
188  *	@tty: tty we are waiting for
189  *	@timeout: how long we will wait
190  *
191  *	Wait for characters pending in a tty driver to hit the wire, or
192  *	for a timeout to occur (eg due to flow control)
193  *
194  *	Locking: none
195  */
196 
tty_wait_until_sent(struct tty_struct * tty,long timeout)197 void tty_wait_until_sent(struct tty_struct *tty, long timeout)
198 {
199 	tty_debug_wait_until_sent(tty, "wait until sent, timeout=%ld\n", timeout);
200 
201 	if (!timeout)
202 		timeout = MAX_SCHEDULE_TIMEOUT;
203 
204 	timeout = wait_event_interruptible_timeout(tty->write_wait,
205 			!tty_chars_in_buffer(tty), timeout);
206 	if (timeout <= 0)
207 		return;
208 
209 	if (timeout == MAX_SCHEDULE_TIMEOUT)
210 		timeout = 0;
211 
212 	if (tty->ops->wait_until_sent)
213 		tty->ops->wait_until_sent(tty, timeout);
214 }
215 EXPORT_SYMBOL(tty_wait_until_sent);
216 
217 
218 /*
219  *		Termios Helper Methods
220  */
221 
unset_locked_termios(struct tty_struct * tty,struct ktermios * old)222 static void unset_locked_termios(struct tty_struct *tty, struct ktermios *old)
223 {
224 	struct ktermios *termios = &tty->termios;
225 	struct ktermios *locked  = &tty->termios_locked;
226 	int	i;
227 
228 #define NOSET_MASK(x, y, z) (x = ((x) & ~(z)) | ((y) & (z)))
229 
230 	NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
231 	NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
232 	NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
233 	NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
234 	termios->c_line = locked->c_line ? old->c_line : termios->c_line;
235 	for (i = 0; i < NCCS; i++)
236 		termios->c_cc[i] = locked->c_cc[i] ?
237 			old->c_cc[i] : termios->c_cc[i];
238 	/* FIXME: What should we do for i/ospeed */
239 }
240 
241 /**
242  *	tty_termios_copy_hw	-	copy hardware settings
243  *	@new: New termios
244  *	@old: Old termios
245  *
246  *	Propagate the hardware specific terminal setting bits from
247  *	the old termios structure to the new one. This is used in cases
248  *	where the hardware does not support reconfiguration or as a helper
249  *	in some cases where only minimal reconfiguration is supported
250  */
251 
tty_termios_copy_hw(struct ktermios * new,struct ktermios * old)252 void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old)
253 {
254 	/* The bits a dumb device handles in software. Smart devices need
255 	   to always provide a set_termios method */
256 	new->c_cflag &= HUPCL | CREAD | CLOCAL;
257 	new->c_cflag |= old->c_cflag & ~(HUPCL | CREAD | CLOCAL);
258 	new->c_ispeed = old->c_ispeed;
259 	new->c_ospeed = old->c_ospeed;
260 }
261 EXPORT_SYMBOL(tty_termios_copy_hw);
262 
263 /**
264  *	tty_termios_hw_change	-	check for setting change
265  *	@a: termios
266  *	@b: termios to compare
267  *
268  *	Check if any of the bits that affect a dumb device have changed
269  *	between the two termios structures, or a speed change is needed.
270  */
271 
tty_termios_hw_change(const struct ktermios * a,const struct ktermios * b)272 int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
273 {
274 	if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
275 		return 1;
276 	if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL))
277 		return 1;
278 	return 0;
279 }
280 EXPORT_SYMBOL(tty_termios_hw_change);
281 
282 /**
283  *	tty_get_char_size	-	get size of a character
284  *	@cflag: termios cflag value
285  *
286  *	Get the size (in bits) of a character depending on @cflag's %CSIZE
287  *	setting.
288  */
tty_get_char_size(unsigned int cflag)289 unsigned char tty_get_char_size(unsigned int cflag)
290 {
291 	switch (cflag & CSIZE) {
292 	case CS5:
293 		return 5;
294 	case CS6:
295 		return 6;
296 	case CS7:
297 		return 7;
298 	case CS8:
299 	default:
300 		return 8;
301 	}
302 }
303 EXPORT_SYMBOL_GPL(tty_get_char_size);
304 
305 /**
306  *	tty_get_frame_size	-	get size of a frame
307  *	@cflag: termios cflag value
308  *
309  *	Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB,
310  *	and %PARENB setting. The result is a sum of character size, start and
311  *	stop bits -- one bit each -- second stop bit (if set), and parity bit
312  *	(if set).
313  */
tty_get_frame_size(unsigned int cflag)314 unsigned char tty_get_frame_size(unsigned int cflag)
315 {
316 	unsigned char bits = 2 + tty_get_char_size(cflag);
317 
318 	if (cflag & CSTOPB)
319 		bits++;
320 	if (cflag & PARENB)
321 		bits++;
322 
323 	return bits;
324 }
325 EXPORT_SYMBOL_GPL(tty_get_frame_size);
326 
327 /**
328  *	tty_set_termios		-	update termios values
329  *	@tty: tty to update
330  *	@new_termios: desired new value
331  *
332  *	Perform updates to the termios values set on this terminal.
333  *	A master pty's termios should never be set.
334  *
335  *	Locking: termios_rwsem
336  */
337 
tty_set_termios(struct tty_struct * tty,struct ktermios * new_termios)338 int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
339 {
340 	struct ktermios old_termios;
341 	struct tty_ldisc *ld;
342 
343 	WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
344 		tty->driver->subtype == PTY_TYPE_MASTER);
345 	/*
346 	 *	Perform the actual termios internal changes under lock.
347 	 */
348 
349 
350 	/* FIXME: we need to decide on some locking/ordering semantics
351 	   for the set_termios notification eventually */
352 	down_write(&tty->termios_rwsem);
353 	old_termios = tty->termios;
354 	tty->termios = *new_termios;
355 	unset_locked_termios(tty, &old_termios);
356 
357 	if (tty->ops->set_termios)
358 		tty->ops->set_termios(tty, &old_termios);
359 	else
360 		tty_termios_copy_hw(&tty->termios, &old_termios);
361 
362 	ld = tty_ldisc_ref(tty);
363 	if (ld != NULL) {
364 		if (ld->ops->set_termios)
365 			ld->ops->set_termios(tty, &old_termios);
366 		tty_ldisc_deref(ld);
367 	}
368 	up_write(&tty->termios_rwsem);
369 	return 0;
370 }
371 EXPORT_SYMBOL_GPL(tty_set_termios);
372 
373 /**
374  *	set_termios		-	set termios values for a tty
375  *	@tty: terminal device
376  *	@arg: user data
377  *	@opt: option information
378  *
379  *	Helper function to prepare termios data and run necessary other
380  *	functions before using tty_set_termios to do the actual changes.
381  *
382  *	Locking:
383  *		Called functions take ldisc and termios_rwsem locks
384  */
385 
set_termios(struct tty_struct * tty,void __user * arg,int opt)386 static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
387 {
388 	struct ktermios tmp_termios;
389 	struct tty_ldisc *ld;
390 	int retval = tty_check_change(tty);
391 
392 	if (retval)
393 		return retval;
394 
395 	down_read(&tty->termios_rwsem);
396 	tmp_termios = tty->termios;
397 	up_read(&tty->termios_rwsem);
398 
399 	if (opt & TERMIOS_TERMIO) {
400 		if (user_termio_to_kernel_termios(&tmp_termios,
401 						(struct termio __user *)arg))
402 			return -EFAULT;
403 #ifdef TCGETS2
404 	} else if (opt & TERMIOS_OLD) {
405 		if (user_termios_to_kernel_termios_1(&tmp_termios,
406 						(struct termios __user *)arg))
407 			return -EFAULT;
408 	} else {
409 		if (user_termios_to_kernel_termios(&tmp_termios,
410 						(struct termios2 __user *)arg))
411 			return -EFAULT;
412 	}
413 #else
414 	} else if (user_termios_to_kernel_termios(&tmp_termios,
415 					(struct termios __user *)arg))
416 		return -EFAULT;
417 #endif
418 
419 	/* If old style Bfoo values are used then load c_ispeed/c_ospeed
420 	 * with the real speed so its unconditionally usable */
421 	tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
422 	tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);
423 
424 	ld = tty_ldisc_ref(tty);
425 
426 	if (ld != NULL) {
427 		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
428 			ld->ops->flush_buffer(tty);
429 		tty_ldisc_deref(ld);
430 	}
431 
432 	if (opt & TERMIOS_WAIT) {
433 		tty_wait_until_sent(tty, 0);
434 		if (signal_pending(current))
435 			return -ERESTARTSYS;
436 	}
437 
438 	tty_set_termios(tty, &tmp_termios);
439 
440 	/* FIXME: Arguably if tmp_termios == tty->termios AND the
441 	   actual requested termios was not tmp_termios then we may
442 	   want to return an error as no user requested change has
443 	   succeeded */
444 	return 0;
445 }
446 
copy_termios(struct tty_struct * tty,struct ktermios * kterm)447 static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
448 {
449 	down_read(&tty->termios_rwsem);
450 	*kterm = tty->termios;
451 	up_read(&tty->termios_rwsem);
452 }
453 
copy_termios_locked(struct tty_struct * tty,struct ktermios * kterm)454 static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
455 {
456 	down_read(&tty->termios_rwsem);
457 	*kterm = tty->termios_locked;
458 	up_read(&tty->termios_rwsem);
459 }
460 
get_termio(struct tty_struct * tty,struct termio __user * termio)461 static int get_termio(struct tty_struct *tty, struct termio __user *termio)
462 {
463 	struct ktermios kterm;
464 	copy_termios(tty, &kterm);
465 	if (kernel_termios_to_user_termio(termio, &kterm))
466 		return -EFAULT;
467 	return 0;
468 }
469 
470 #ifdef TIOCGETP
471 /*
472  * These are deprecated, but there is limited support..
473  *
474  * The "sg_flags" translation is a joke..
475  */
get_sgflags(struct tty_struct * tty)476 static int get_sgflags(struct tty_struct *tty)
477 {
478 	int flags = 0;
479 
480 	if (!L_ICANON(tty)) {
481 		if (L_ISIG(tty))
482 			flags |= 0x02;		/* cbreak */
483 		else
484 			flags |= 0x20;		/* raw */
485 	}
486 	if (L_ECHO(tty))
487 		flags |= 0x08;			/* echo */
488 	if (O_OPOST(tty))
489 		if (O_ONLCR(tty))
490 			flags |= 0x10;		/* crmod */
491 	return flags;
492 }
493 
get_sgttyb(struct tty_struct * tty,struct sgttyb __user * sgttyb)494 static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
495 {
496 	struct sgttyb tmp;
497 
498 	down_read(&tty->termios_rwsem);
499 	tmp.sg_ispeed = tty->termios.c_ispeed;
500 	tmp.sg_ospeed = tty->termios.c_ospeed;
501 	tmp.sg_erase = tty->termios.c_cc[VERASE];
502 	tmp.sg_kill = tty->termios.c_cc[VKILL];
503 	tmp.sg_flags = get_sgflags(tty);
504 	up_read(&tty->termios_rwsem);
505 
506 	return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
507 }
508 
set_sgflags(struct ktermios * termios,int flags)509 static void set_sgflags(struct ktermios *termios, int flags)
510 {
511 	termios->c_iflag = ICRNL | IXON;
512 	termios->c_oflag = 0;
513 	termios->c_lflag = ISIG | ICANON;
514 	if (flags & 0x02) {	/* cbreak */
515 		termios->c_iflag = 0;
516 		termios->c_lflag &= ~ICANON;
517 	}
518 	if (flags & 0x08) {		/* echo */
519 		termios->c_lflag |= ECHO | ECHOE | ECHOK |
520 				    ECHOCTL | ECHOKE | IEXTEN;
521 	}
522 	if (flags & 0x10) {		/* crmod */
523 		termios->c_oflag |= OPOST | ONLCR;
524 	}
525 	if (flags & 0x20) {	/* raw */
526 		termios->c_iflag = 0;
527 		termios->c_lflag &= ~(ISIG | ICANON);
528 	}
529 	if (!(termios->c_lflag & ICANON)) {
530 		termios->c_cc[VMIN] = 1;
531 		termios->c_cc[VTIME] = 0;
532 	}
533 }
534 
535 /**
536  *	set_sgttyb		-	set legacy terminal values
537  *	@tty: tty structure
538  *	@sgttyb: pointer to old style terminal structure
539  *
540  *	Updates a terminal from the legacy BSD style terminal information
541  *	structure.
542  *
543  *	Locking: termios_rwsem
544  */
545 
set_sgttyb(struct tty_struct * tty,struct sgttyb __user * sgttyb)546 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
547 {
548 	int retval;
549 	struct sgttyb tmp;
550 	struct ktermios termios;
551 
552 	retval = tty_check_change(tty);
553 	if (retval)
554 		return retval;
555 
556 	if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
557 		return -EFAULT;
558 
559 	down_write(&tty->termios_rwsem);
560 	termios = tty->termios;
561 	termios.c_cc[VERASE] = tmp.sg_erase;
562 	termios.c_cc[VKILL] = tmp.sg_kill;
563 	set_sgflags(&termios, tmp.sg_flags);
564 	/* Try and encode into Bfoo format */
565 #ifdef BOTHER
566 	tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
567 						termios.c_ospeed);
568 #endif
569 	up_write(&tty->termios_rwsem);
570 	tty_set_termios(tty, &termios);
571 	return 0;
572 }
573 #endif
574 
575 #ifdef TIOCGETC
get_tchars(struct tty_struct * tty,struct tchars __user * tchars)576 static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
577 {
578 	struct tchars tmp;
579 
580 	down_read(&tty->termios_rwsem);
581 	tmp.t_intrc = tty->termios.c_cc[VINTR];
582 	tmp.t_quitc = tty->termios.c_cc[VQUIT];
583 	tmp.t_startc = tty->termios.c_cc[VSTART];
584 	tmp.t_stopc = tty->termios.c_cc[VSTOP];
585 	tmp.t_eofc = tty->termios.c_cc[VEOF];
586 	tmp.t_brkc = tty->termios.c_cc[VEOL2];	/* what is brkc anyway? */
587 	up_read(&tty->termios_rwsem);
588 	return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
589 }
590 
set_tchars(struct tty_struct * tty,struct tchars __user * tchars)591 static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
592 {
593 	struct tchars tmp;
594 
595 	if (copy_from_user(&tmp, tchars, sizeof(tmp)))
596 		return -EFAULT;
597 	down_write(&tty->termios_rwsem);
598 	tty->termios.c_cc[VINTR] = tmp.t_intrc;
599 	tty->termios.c_cc[VQUIT] = tmp.t_quitc;
600 	tty->termios.c_cc[VSTART] = tmp.t_startc;
601 	tty->termios.c_cc[VSTOP] = tmp.t_stopc;
602 	tty->termios.c_cc[VEOF] = tmp.t_eofc;
603 	tty->termios.c_cc[VEOL2] = tmp.t_brkc;	/* what is brkc anyway? */
604 	up_write(&tty->termios_rwsem);
605 	return 0;
606 }
607 #endif
608 
609 #ifdef TIOCGLTC
get_ltchars(struct tty_struct * tty,struct ltchars __user * ltchars)610 static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
611 {
612 	struct ltchars tmp;
613 
614 	down_read(&tty->termios_rwsem);
615 	tmp.t_suspc = tty->termios.c_cc[VSUSP];
616 	/* what is dsuspc anyway? */
617 	tmp.t_dsuspc = tty->termios.c_cc[VSUSP];
618 	tmp.t_rprntc = tty->termios.c_cc[VREPRINT];
619 	/* what is flushc anyway? */
620 	tmp.t_flushc = tty->termios.c_cc[VEOL2];
621 	tmp.t_werasc = tty->termios.c_cc[VWERASE];
622 	tmp.t_lnextc = tty->termios.c_cc[VLNEXT];
623 	up_read(&tty->termios_rwsem);
624 	return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
625 }
626 
set_ltchars(struct tty_struct * tty,struct ltchars __user * ltchars)627 static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
628 {
629 	struct ltchars tmp;
630 
631 	if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
632 		return -EFAULT;
633 
634 	down_write(&tty->termios_rwsem);
635 	tty->termios.c_cc[VSUSP] = tmp.t_suspc;
636 	/* what is dsuspc anyway? */
637 	tty->termios.c_cc[VEOL2] = tmp.t_dsuspc;
638 	tty->termios.c_cc[VREPRINT] = tmp.t_rprntc;
639 	/* what is flushc anyway? */
640 	tty->termios.c_cc[VEOL2] = tmp.t_flushc;
641 	tty->termios.c_cc[VWERASE] = tmp.t_werasc;
642 	tty->termios.c_cc[VLNEXT] = tmp.t_lnextc;
643 	up_write(&tty->termios_rwsem);
644 	return 0;
645 }
646 #endif
647 
648 /**
649  *	tty_change_softcar	-	carrier change ioctl helper
650  *	@tty: tty to update
651  *	@arg: enable/disable CLOCAL
652  *
653  *	Perform a change to the CLOCAL state and call into the driver
654  *	layer to make it visible. All done with the termios rwsem
655  */
656 
tty_change_softcar(struct tty_struct * tty,int arg)657 static int tty_change_softcar(struct tty_struct *tty, int arg)
658 {
659 	int ret = 0;
660 	int bit = arg ? CLOCAL : 0;
661 	struct ktermios old;
662 
663 	down_write(&tty->termios_rwsem);
664 	old = tty->termios;
665 	tty->termios.c_cflag &= ~CLOCAL;
666 	tty->termios.c_cflag |= bit;
667 	if (tty->ops->set_termios)
668 		tty->ops->set_termios(tty, &old);
669 	if (C_CLOCAL(tty) != bit)
670 		ret = -EINVAL;
671 	up_write(&tty->termios_rwsem);
672 	return ret;
673 }
674 
675 /**
676  *	tty_mode_ioctl		-	mode related ioctls
677  *	@tty: tty for the ioctl
678  *	@cmd: command
679  *	@arg: ioctl argument
680  *
681  *	Perform non line discipline specific mode control ioctls. This
682  *	is designed to be called by line disciplines to ensure they provide
683  *	consistent mode setting.
684  */
685 
tty_mode_ioctl(struct tty_struct * tty,unsigned int cmd,unsigned long arg)686 int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
687 {
688 	struct tty_struct *real_tty;
689 	void __user *p = (void __user *)arg;
690 	int ret = 0;
691 	struct ktermios kterm;
692 
693 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
694 	    tty->driver->subtype == PTY_TYPE_MASTER)
695 		real_tty = tty->link;
696 	else
697 		real_tty = tty;
698 
699 	switch (cmd) {
700 #ifdef TIOCGETP
701 	case TIOCGETP:
702 		return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
703 	case TIOCSETP:
704 	case TIOCSETN:
705 		return set_sgttyb(real_tty, (struct sgttyb __user *) arg);
706 #endif
707 #ifdef TIOCGETC
708 	case TIOCGETC:
709 		return get_tchars(real_tty, p);
710 	case TIOCSETC:
711 		return set_tchars(real_tty, p);
712 #endif
713 #ifdef TIOCGLTC
714 	case TIOCGLTC:
715 		return get_ltchars(real_tty, p);
716 	case TIOCSLTC:
717 		return set_ltchars(real_tty, p);
718 #endif
719 	case TCSETSF:
720 		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_OLD);
721 	case TCSETSW:
722 		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_OLD);
723 	case TCSETS:
724 		return set_termios(real_tty, p, TERMIOS_OLD);
725 #ifndef TCGETS2
726 	case TCGETS:
727 		copy_termios(real_tty, &kterm);
728 		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
729 			ret = -EFAULT;
730 		return ret;
731 #else
732 	case TCGETS:
733 		copy_termios(real_tty, &kterm);
734 		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
735 			ret = -EFAULT;
736 		return ret;
737 	case TCGETS2:
738 		copy_termios(real_tty, &kterm);
739 		if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))
740 			ret = -EFAULT;
741 		return ret;
742 	case TCSETSF2:
743 		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT);
744 	case TCSETSW2:
745 		return set_termios(real_tty, p, TERMIOS_WAIT);
746 	case TCSETS2:
747 		return set_termios(real_tty, p, 0);
748 #endif
749 	case TCGETA:
750 		return get_termio(real_tty, p);
751 	case TCSETAF:
752 		return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
753 	case TCSETAW:
754 		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
755 	case TCSETA:
756 		return set_termios(real_tty, p, TERMIOS_TERMIO);
757 #ifndef TCGETS2
758 	case TIOCGLCKTRMIOS:
759 		copy_termios_locked(real_tty, &kterm);
760 		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
761 			ret = -EFAULT;
762 		return ret;
763 	case TIOCSLCKTRMIOS:
764 		if (!capable(CAP_SYS_ADMIN))
765 			return -EPERM;
766 		copy_termios_locked(real_tty, &kterm);
767 		if (user_termios_to_kernel_termios(&kterm,
768 					       (struct termios __user *) arg))
769 			return -EFAULT;
770 		down_write(&real_tty->termios_rwsem);
771 		real_tty->termios_locked = kterm;
772 		up_write(&real_tty->termios_rwsem);
773 		return 0;
774 #else
775 	case TIOCGLCKTRMIOS:
776 		copy_termios_locked(real_tty, &kterm);
777 		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
778 			ret = -EFAULT;
779 		return ret;
780 	case TIOCSLCKTRMIOS:
781 		if (!capable(CAP_SYS_ADMIN))
782 			return -EPERM;
783 		copy_termios_locked(real_tty, &kterm);
784 		if (user_termios_to_kernel_termios_1(&kterm,
785 					       (struct termios __user *) arg))
786 			return -EFAULT;
787 		down_write(&real_tty->termios_rwsem);
788 		real_tty->termios_locked = kterm;
789 		up_write(&real_tty->termios_rwsem);
790 		return ret;
791 #endif
792 #ifdef TCGETX
793 	case TCGETX:
794 	case TCSETX:
795 	case TCSETXW:
796 	case TCSETXF:
797 		return -ENOTTY;
798 #endif
799 	case TIOCGSOFTCAR:
800 		copy_termios(real_tty, &kterm);
801 		ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,
802 						(int __user *)arg);
803 		return ret;
804 	case TIOCSSOFTCAR:
805 		if (get_user(arg, (unsigned int __user *) arg))
806 			return -EFAULT;
807 		return tty_change_softcar(real_tty, arg);
808 	default:
809 		return -ENOIOCTLCMD;
810 	}
811 }
812 EXPORT_SYMBOL_GPL(tty_mode_ioctl);
813 
814 
815 /* Caller guarantees ldisc reference is held */
__tty_perform_flush(struct tty_struct * tty,unsigned long arg)816 static int __tty_perform_flush(struct tty_struct *tty, unsigned long arg)
817 {
818 	struct tty_ldisc *ld = tty->ldisc;
819 
820 	switch (arg) {
821 	case TCIFLUSH:
822 		if (ld && ld->ops->flush_buffer) {
823 			ld->ops->flush_buffer(tty);
824 			tty_unthrottle(tty);
825 		}
826 		break;
827 	case TCIOFLUSH:
828 		if (ld && ld->ops->flush_buffer) {
829 			ld->ops->flush_buffer(tty);
830 			tty_unthrottle(tty);
831 		}
832 		fallthrough;
833 	case TCOFLUSH:
834 		tty_driver_flush_buffer(tty);
835 		break;
836 	default:
837 		return -EINVAL;
838 	}
839 	return 0;
840 }
841 
tty_perform_flush(struct tty_struct * tty,unsigned long arg)842 int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
843 {
844 	struct tty_ldisc *ld;
845 	int retval = tty_check_change(tty);
846 	if (retval)
847 		return retval;
848 
849 	ld = tty_ldisc_ref_wait(tty);
850 	retval = __tty_perform_flush(tty, arg);
851 	if (ld)
852 		tty_ldisc_deref(ld);
853 	return retval;
854 }
855 EXPORT_SYMBOL_GPL(tty_perform_flush);
856 
n_tty_ioctl_helper(struct tty_struct * tty,unsigned int cmd,unsigned long arg)857 int n_tty_ioctl_helper(struct tty_struct *tty, unsigned int cmd,
858 		unsigned long arg)
859 {
860 	int retval;
861 
862 	switch (cmd) {
863 	case TCXONC:
864 		retval = tty_check_change(tty);
865 		if (retval)
866 			return retval;
867 		switch (arg) {
868 		case TCOOFF:
869 			spin_lock_irq(&tty->flow.lock);
870 			if (!tty->flow.tco_stopped) {
871 				tty->flow.tco_stopped = true;
872 				__stop_tty(tty);
873 			}
874 			spin_unlock_irq(&tty->flow.lock);
875 			break;
876 		case TCOON:
877 			spin_lock_irq(&tty->flow.lock);
878 			if (tty->flow.tco_stopped) {
879 				tty->flow.tco_stopped = false;
880 				__start_tty(tty);
881 			}
882 			spin_unlock_irq(&tty->flow.lock);
883 			break;
884 		case TCIOFF:
885 			if (STOP_CHAR(tty) != __DISABLED_CHAR)
886 				retval = tty_send_xchar(tty, STOP_CHAR(tty));
887 			break;
888 		case TCION:
889 			if (START_CHAR(tty) != __DISABLED_CHAR)
890 				retval = tty_send_xchar(tty, START_CHAR(tty));
891 			break;
892 		default:
893 			return -EINVAL;
894 		}
895 		return retval;
896 	case TCFLSH:
897 		retval = tty_check_change(tty);
898 		if (retval)
899 			return retval;
900 		return __tty_perform_flush(tty, arg);
901 	default:
902 		/* Try the mode commands */
903 		return tty_mode_ioctl(tty, cmd, arg);
904 	}
905 }
906 EXPORT_SYMBOL(n_tty_ioctl_helper);
907