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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 	if (opt & (TERMIOS_FLUSH|TERMIOS_WAIT)) {
425 retry_write_wait:
426 		retval = wait_event_interruptible(tty->write_wait, !tty_chars_in_buffer(tty));
427 		if (retval < 0)
428 			return retval;
429 
430 		if (tty_write_lock(tty, false) < 0)
431 			goto retry_write_wait;
432 
433 		/* Racing writer? */
434 		if (tty_chars_in_buffer(tty)) {
435 			tty_write_unlock(tty);
436 			goto retry_write_wait;
437 		}
438 
439 		ld = tty_ldisc_ref(tty);
440 		if (ld != NULL) {
441 			if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
442 				ld->ops->flush_buffer(tty);
443 			tty_ldisc_deref(ld);
444 		}
445 
446 		if ((opt & TERMIOS_WAIT) && tty->ops->wait_until_sent) {
447 			tty->ops->wait_until_sent(tty, 0);
448 			if (signal_pending(current)) {
449 				tty_write_unlock(tty);
450 				return -ERESTARTSYS;
451 			}
452 		}
453 
454 		tty_set_termios(tty, &tmp_termios);
455 
456 		tty_write_unlock(tty);
457 	} else {
458 		tty_set_termios(tty, &tmp_termios);
459 	}
460 
461 	/* FIXME: Arguably if tmp_termios == tty->termios AND the
462 	   actual requested termios was not tmp_termios then we may
463 	   want to return an error as no user requested change has
464 	   succeeded */
465 	return 0;
466 }
467 
copy_termios(struct tty_struct * tty,struct ktermios * kterm)468 static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
469 {
470 	down_read(&tty->termios_rwsem);
471 	*kterm = tty->termios;
472 	up_read(&tty->termios_rwsem);
473 }
474 
copy_termios_locked(struct tty_struct * tty,struct ktermios * kterm)475 static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
476 {
477 	down_read(&tty->termios_rwsem);
478 	*kterm = tty->termios_locked;
479 	up_read(&tty->termios_rwsem);
480 }
481 
get_termio(struct tty_struct * tty,struct termio __user * termio)482 static int get_termio(struct tty_struct *tty, struct termio __user *termio)
483 {
484 	struct ktermios kterm;
485 	copy_termios(tty, &kterm);
486 	if (kernel_termios_to_user_termio(termio, &kterm))
487 		return -EFAULT;
488 	return 0;
489 }
490 
491 #ifdef TIOCGETP
492 /*
493  * These are deprecated, but there is limited support..
494  *
495  * The "sg_flags" translation is a joke..
496  */
get_sgflags(struct tty_struct * tty)497 static int get_sgflags(struct tty_struct *tty)
498 {
499 	int flags = 0;
500 
501 	if (!L_ICANON(tty)) {
502 		if (L_ISIG(tty))
503 			flags |= 0x02;		/* cbreak */
504 		else
505 			flags |= 0x20;		/* raw */
506 	}
507 	if (L_ECHO(tty))
508 		flags |= 0x08;			/* echo */
509 	if (O_OPOST(tty))
510 		if (O_ONLCR(tty))
511 			flags |= 0x10;		/* crmod */
512 	return flags;
513 }
514 
get_sgttyb(struct tty_struct * tty,struct sgttyb __user * sgttyb)515 static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
516 {
517 	struct sgttyb tmp;
518 
519 	down_read(&tty->termios_rwsem);
520 	tmp.sg_ispeed = tty->termios.c_ispeed;
521 	tmp.sg_ospeed = tty->termios.c_ospeed;
522 	tmp.sg_erase = tty->termios.c_cc[VERASE];
523 	tmp.sg_kill = tty->termios.c_cc[VKILL];
524 	tmp.sg_flags = get_sgflags(tty);
525 	up_read(&tty->termios_rwsem);
526 
527 	return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
528 }
529 
set_sgflags(struct ktermios * termios,int flags)530 static void set_sgflags(struct ktermios *termios, int flags)
531 {
532 	termios->c_iflag = ICRNL | IXON;
533 	termios->c_oflag = 0;
534 	termios->c_lflag = ISIG | ICANON;
535 	if (flags & 0x02) {	/* cbreak */
536 		termios->c_iflag = 0;
537 		termios->c_lflag &= ~ICANON;
538 	}
539 	if (flags & 0x08) {		/* echo */
540 		termios->c_lflag |= ECHO | ECHOE | ECHOK |
541 				    ECHOCTL | ECHOKE | IEXTEN;
542 	}
543 	if (flags & 0x10) {		/* crmod */
544 		termios->c_oflag |= OPOST | ONLCR;
545 	}
546 	if (flags & 0x20) {	/* raw */
547 		termios->c_iflag = 0;
548 		termios->c_lflag &= ~(ISIG | ICANON);
549 	}
550 	if (!(termios->c_lflag & ICANON)) {
551 		termios->c_cc[VMIN] = 1;
552 		termios->c_cc[VTIME] = 0;
553 	}
554 }
555 
556 /**
557  *	set_sgttyb		-	set legacy terminal values
558  *	@tty: tty structure
559  *	@sgttyb: pointer to old style terminal structure
560  *
561  *	Updates a terminal from the legacy BSD style terminal information
562  *	structure.
563  *
564  *	Locking: termios_rwsem
565  */
566 
set_sgttyb(struct tty_struct * tty,struct sgttyb __user * sgttyb)567 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
568 {
569 	int retval;
570 	struct sgttyb tmp;
571 	struct ktermios termios;
572 
573 	retval = tty_check_change(tty);
574 	if (retval)
575 		return retval;
576 
577 	if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
578 		return -EFAULT;
579 
580 	down_write(&tty->termios_rwsem);
581 	termios = tty->termios;
582 	termios.c_cc[VERASE] = tmp.sg_erase;
583 	termios.c_cc[VKILL] = tmp.sg_kill;
584 	set_sgflags(&termios, tmp.sg_flags);
585 	/* Try and encode into Bfoo format */
586 #ifdef BOTHER
587 	tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
588 						termios.c_ospeed);
589 #endif
590 	up_write(&tty->termios_rwsem);
591 	tty_set_termios(tty, &termios);
592 	return 0;
593 }
594 #endif
595 
596 #ifdef TIOCGETC
get_tchars(struct tty_struct * tty,struct tchars __user * tchars)597 static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
598 {
599 	struct tchars tmp;
600 
601 	down_read(&tty->termios_rwsem);
602 	tmp.t_intrc = tty->termios.c_cc[VINTR];
603 	tmp.t_quitc = tty->termios.c_cc[VQUIT];
604 	tmp.t_startc = tty->termios.c_cc[VSTART];
605 	tmp.t_stopc = tty->termios.c_cc[VSTOP];
606 	tmp.t_eofc = tty->termios.c_cc[VEOF];
607 	tmp.t_brkc = tty->termios.c_cc[VEOL2];	/* what is brkc anyway? */
608 	up_read(&tty->termios_rwsem);
609 	return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
610 }
611 
set_tchars(struct tty_struct * tty,struct tchars __user * tchars)612 static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
613 {
614 	struct tchars tmp;
615 
616 	if (copy_from_user(&tmp, tchars, sizeof(tmp)))
617 		return -EFAULT;
618 	down_write(&tty->termios_rwsem);
619 	tty->termios.c_cc[VINTR] = tmp.t_intrc;
620 	tty->termios.c_cc[VQUIT] = tmp.t_quitc;
621 	tty->termios.c_cc[VSTART] = tmp.t_startc;
622 	tty->termios.c_cc[VSTOP] = tmp.t_stopc;
623 	tty->termios.c_cc[VEOF] = tmp.t_eofc;
624 	tty->termios.c_cc[VEOL2] = tmp.t_brkc;	/* what is brkc anyway? */
625 	up_write(&tty->termios_rwsem);
626 	return 0;
627 }
628 #endif
629 
630 #ifdef TIOCGLTC
get_ltchars(struct tty_struct * tty,struct ltchars __user * ltchars)631 static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
632 {
633 	struct ltchars tmp;
634 
635 	down_read(&tty->termios_rwsem);
636 	tmp.t_suspc = tty->termios.c_cc[VSUSP];
637 	/* what is dsuspc anyway? */
638 	tmp.t_dsuspc = tty->termios.c_cc[VSUSP];
639 	tmp.t_rprntc = tty->termios.c_cc[VREPRINT];
640 	/* what is flushc anyway? */
641 	tmp.t_flushc = tty->termios.c_cc[VEOL2];
642 	tmp.t_werasc = tty->termios.c_cc[VWERASE];
643 	tmp.t_lnextc = tty->termios.c_cc[VLNEXT];
644 	up_read(&tty->termios_rwsem);
645 	return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
646 }
647 
set_ltchars(struct tty_struct * tty,struct ltchars __user * ltchars)648 static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
649 {
650 	struct ltchars tmp;
651 
652 	if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
653 		return -EFAULT;
654 
655 	down_write(&tty->termios_rwsem);
656 	tty->termios.c_cc[VSUSP] = tmp.t_suspc;
657 	/* what is dsuspc anyway? */
658 	tty->termios.c_cc[VEOL2] = tmp.t_dsuspc;
659 	tty->termios.c_cc[VREPRINT] = tmp.t_rprntc;
660 	/* what is flushc anyway? */
661 	tty->termios.c_cc[VEOL2] = tmp.t_flushc;
662 	tty->termios.c_cc[VWERASE] = tmp.t_werasc;
663 	tty->termios.c_cc[VLNEXT] = tmp.t_lnextc;
664 	up_write(&tty->termios_rwsem);
665 	return 0;
666 }
667 #endif
668 
669 /**
670  *	tty_change_softcar	-	carrier change ioctl helper
671  *	@tty: tty to update
672  *	@arg: enable/disable CLOCAL
673  *
674  *	Perform a change to the CLOCAL state and call into the driver
675  *	layer to make it visible. All done with the termios rwsem
676  */
677 
tty_change_softcar(struct tty_struct * tty,int arg)678 static int tty_change_softcar(struct tty_struct *tty, int arg)
679 {
680 	int ret = 0;
681 	int bit = arg ? CLOCAL : 0;
682 	struct ktermios old;
683 
684 	down_write(&tty->termios_rwsem);
685 	old = tty->termios;
686 	tty->termios.c_cflag &= ~CLOCAL;
687 	tty->termios.c_cflag |= bit;
688 	if (tty->ops->set_termios)
689 		tty->ops->set_termios(tty, &old);
690 	if (C_CLOCAL(tty) != bit)
691 		ret = -EINVAL;
692 	up_write(&tty->termios_rwsem);
693 	return ret;
694 }
695 
696 /**
697  *	tty_mode_ioctl		-	mode related ioctls
698  *	@tty: tty for the ioctl
699  *	@file: file pointer for the tty
700  *	@cmd: command
701  *	@arg: ioctl argument
702  *
703  *	Perform non line discipline specific mode control ioctls. This
704  *	is designed to be called by line disciplines to ensure they provide
705  *	consistent mode setting.
706  */
707 
tty_mode_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)708 int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
709 			unsigned int cmd, unsigned long arg)
710 {
711 	struct tty_struct *real_tty;
712 	void __user *p = (void __user *)arg;
713 	int ret = 0;
714 	struct ktermios kterm;
715 
716 	BUG_ON(file == NULL);
717 
718 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
719 	    tty->driver->subtype == PTY_TYPE_MASTER)
720 		real_tty = tty->link;
721 	else
722 		real_tty = tty;
723 
724 	switch (cmd) {
725 #ifdef TIOCGETP
726 	case TIOCGETP:
727 		return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
728 	case TIOCSETP:
729 	case TIOCSETN:
730 		return set_sgttyb(real_tty, (struct sgttyb __user *) arg);
731 #endif
732 #ifdef TIOCGETC
733 	case TIOCGETC:
734 		return get_tchars(real_tty, p);
735 	case TIOCSETC:
736 		return set_tchars(real_tty, p);
737 #endif
738 #ifdef TIOCGLTC
739 	case TIOCGLTC:
740 		return get_ltchars(real_tty, p);
741 	case TIOCSLTC:
742 		return set_ltchars(real_tty, p);
743 #endif
744 	case TCSETSF:
745 		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_OLD);
746 	case TCSETSW:
747 		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_OLD);
748 	case TCSETS:
749 		return set_termios(real_tty, p, TERMIOS_OLD);
750 #ifndef TCGETS2
751 	case TCGETS:
752 		copy_termios(real_tty, &kterm);
753 		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
754 			ret = -EFAULT;
755 		return ret;
756 #else
757 	case TCGETS:
758 		copy_termios(real_tty, &kterm);
759 		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
760 			ret = -EFAULT;
761 		return ret;
762 	case TCGETS2:
763 		copy_termios(real_tty, &kterm);
764 		if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))
765 			ret = -EFAULT;
766 		return ret;
767 	case TCSETSF2:
768 		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT);
769 	case TCSETSW2:
770 		return set_termios(real_tty, p, TERMIOS_WAIT);
771 	case TCSETS2:
772 		return set_termios(real_tty, p, 0);
773 #endif
774 	case TCGETA:
775 		return get_termio(real_tty, p);
776 	case TCSETAF:
777 		return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
778 	case TCSETAW:
779 		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
780 	case TCSETA:
781 		return set_termios(real_tty, p, TERMIOS_TERMIO);
782 #ifndef TCGETS2
783 	case TIOCGLCKTRMIOS:
784 		copy_termios_locked(real_tty, &kterm);
785 		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
786 			ret = -EFAULT;
787 		return ret;
788 	case TIOCSLCKTRMIOS:
789 		if (!checkpoint_restore_ns_capable(&init_user_ns))
790 			return -EPERM;
791 		copy_termios_locked(real_tty, &kterm);
792 		if (user_termios_to_kernel_termios(&kterm,
793 					       (struct termios __user *) arg))
794 			return -EFAULT;
795 		down_write(&real_tty->termios_rwsem);
796 		real_tty->termios_locked = kterm;
797 		up_write(&real_tty->termios_rwsem);
798 		return 0;
799 #else
800 	case TIOCGLCKTRMIOS:
801 		copy_termios_locked(real_tty, &kterm);
802 		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
803 			ret = -EFAULT;
804 		return ret;
805 	case TIOCSLCKTRMIOS:
806 		if (!checkpoint_restore_ns_capable(&init_user_ns))
807 			return -EPERM;
808 		copy_termios_locked(real_tty, &kterm);
809 		if (user_termios_to_kernel_termios_1(&kterm,
810 					       (struct termios __user *) arg))
811 			return -EFAULT;
812 		down_write(&real_tty->termios_rwsem);
813 		real_tty->termios_locked = kterm;
814 		up_write(&real_tty->termios_rwsem);
815 		return ret;
816 #endif
817 #ifdef TCGETX
818 	case TCGETX:
819 	case TCSETX:
820 	case TCSETXW:
821 	case TCSETXF:
822 		return -ENOTTY;
823 #endif
824 	case TIOCGSOFTCAR:
825 		copy_termios(real_tty, &kterm);
826 		ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,
827 						(int __user *)arg);
828 		return ret;
829 	case TIOCSSOFTCAR:
830 		if (get_user(arg, (unsigned int __user *) arg))
831 			return -EFAULT;
832 		return tty_change_softcar(real_tty, arg);
833 	default:
834 		return -ENOIOCTLCMD;
835 	}
836 }
837 EXPORT_SYMBOL_GPL(tty_mode_ioctl);
838 
839 
840 /* Caller guarantees ldisc reference is held */
__tty_perform_flush(struct tty_struct * tty,unsigned long arg)841 static int __tty_perform_flush(struct tty_struct *tty, unsigned long arg)
842 {
843 	struct tty_ldisc *ld = tty->ldisc;
844 
845 	switch (arg) {
846 	case TCIFLUSH:
847 		if (ld && ld->ops->flush_buffer) {
848 			ld->ops->flush_buffer(tty);
849 			tty_unthrottle(tty);
850 		}
851 		break;
852 	case TCIOFLUSH:
853 		if (ld && ld->ops->flush_buffer) {
854 			ld->ops->flush_buffer(tty);
855 			tty_unthrottle(tty);
856 		}
857 		fallthrough;
858 	case TCOFLUSH:
859 		tty_driver_flush_buffer(tty);
860 		break;
861 	default:
862 		return -EINVAL;
863 	}
864 	return 0;
865 }
866 
tty_perform_flush(struct tty_struct * tty,unsigned long arg)867 int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
868 {
869 	struct tty_ldisc *ld;
870 	int retval = tty_check_change(tty);
871 	if (retval)
872 		return retval;
873 
874 	ld = tty_ldisc_ref_wait(tty);
875 	retval = __tty_perform_flush(tty, arg);
876 	if (ld)
877 		tty_ldisc_deref(ld);
878 	return retval;
879 }
880 EXPORT_SYMBOL_GPL(tty_perform_flush);
881 
n_tty_ioctl_helper(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)882 int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
883 		       unsigned int cmd, unsigned long arg)
884 {
885 	int retval;
886 
887 	switch (cmd) {
888 	case TCXONC:
889 		retval = tty_check_change(tty);
890 		if (retval)
891 			return retval;
892 		switch (arg) {
893 		case TCOOFF:
894 			spin_lock_irq(&tty->flow.lock);
895 			if (!tty->flow.tco_stopped) {
896 				tty->flow.tco_stopped = true;
897 				__stop_tty(tty);
898 			}
899 			spin_unlock_irq(&tty->flow.lock);
900 			break;
901 		case TCOON:
902 			spin_lock_irq(&tty->flow.lock);
903 			if (tty->flow.tco_stopped) {
904 				tty->flow.tco_stopped = false;
905 				__start_tty(tty);
906 			}
907 			spin_unlock_irq(&tty->flow.lock);
908 			break;
909 		case TCIOFF:
910 			if (STOP_CHAR(tty) != __DISABLED_CHAR)
911 				retval = tty_send_xchar(tty, STOP_CHAR(tty));
912 			break;
913 		case TCION:
914 			if (START_CHAR(tty) != __DISABLED_CHAR)
915 				retval = tty_send_xchar(tty, START_CHAR(tty));
916 			break;
917 		default:
918 			return -EINVAL;
919 		}
920 		return retval;
921 	case TCFLSH:
922 		retval = tty_check_change(tty);
923 		if (retval)
924 			return retval;
925 		return __tty_perform_flush(tty, arg);
926 	default:
927 		/* Try the mode commands */
928 		return tty_mode_ioctl(tty, file, cmd, arg);
929 	}
930 }
931 EXPORT_SYMBOL(n_tty_ioctl_helper);
932