1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <linux/irqreturn.h>
7 #include <linux/kd.h>
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
10 
11 #include "chan.h"
12 #include <irq_kern.h>
13 #include <irq_user.h>
14 #include <kern_util.h>
15 #include <os.h>
16 
17 #define LINE_BUFSIZE 4096
18 
line_interrupt(int irq,void * data)19 static irqreturn_t line_interrupt(int irq, void *data)
20 {
21 	struct chan *chan = data;
22 	struct line *line = chan->line;
23 
24 	if (line)
25 		chan_interrupt(line, irq);
26 
27 	return IRQ_HANDLED;
28 }
29 
30 /*
31  * Returns the free space inside the ring buffer of this line.
32  *
33  * Should be called while holding line->lock (this does not modify data).
34  */
write_room(struct line * line)35 static unsigned int write_room(struct line *line)
36 {
37 	int n;
38 
39 	if (line->buffer == NULL)
40 		return LINE_BUFSIZE - 1;
41 
42 	/* This is for the case where the buffer is wrapped! */
43 	n = line->head - line->tail;
44 
45 	if (n <= 0)
46 		n += LINE_BUFSIZE; /* The other case */
47 	return n - 1;
48 }
49 
line_write_room(struct tty_struct * tty)50 unsigned int line_write_room(struct tty_struct *tty)
51 {
52 	struct line *line = tty->driver_data;
53 	unsigned long flags;
54 	unsigned int room;
55 
56 	spin_lock_irqsave(&line->lock, flags);
57 	room = write_room(line);
58 	spin_unlock_irqrestore(&line->lock, flags);
59 
60 	return room;
61 }
62 
line_chars_in_buffer(struct tty_struct * tty)63 unsigned int line_chars_in_buffer(struct tty_struct *tty)
64 {
65 	struct line *line = tty->driver_data;
66 	unsigned long flags;
67 	unsigned int ret;
68 
69 	spin_lock_irqsave(&line->lock, flags);
70 	/* write_room subtracts 1 for the needed NULL, so we readd it.*/
71 	ret = LINE_BUFSIZE - (write_room(line) + 1);
72 	spin_unlock_irqrestore(&line->lock, flags);
73 
74 	return ret;
75 }
76 
77 /*
78  * This copies the content of buf into the circular buffer associated with
79  * this line.
80  * The return value is the number of characters actually copied, i.e. the ones
81  * for which there was space: this function is not supposed to ever flush out
82  * the circular buffer.
83  *
84  * Must be called while holding line->lock!
85  */
buffer_data(struct line * line,const char * buf,int len)86 static int buffer_data(struct line *line, const char *buf, int len)
87 {
88 	int end, room;
89 
90 	if (line->buffer == NULL) {
91 		line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
92 		if (line->buffer == NULL) {
93 			printk(KERN_ERR "buffer_data - atomic allocation "
94 			       "failed\n");
95 			return 0;
96 		}
97 		line->head = line->buffer;
98 		line->tail = line->buffer;
99 	}
100 
101 	room = write_room(line);
102 	len = (len > room) ? room : len;
103 
104 	end = line->buffer + LINE_BUFSIZE - line->tail;
105 
106 	if (len < end) {
107 		memcpy(line->tail, buf, len);
108 		line->tail += len;
109 	}
110 	else {
111 		/* The circular buffer is wrapping */
112 		memcpy(line->tail, buf, end);
113 		buf += end;
114 		memcpy(line->buffer, buf, len - end);
115 		line->tail = line->buffer + len - end;
116 	}
117 
118 	return len;
119 }
120 
121 /*
122  * Flushes the ring buffer to the output channels. That is, write_chan is
123  * called, passing it line->head as buffer, and an appropriate count.
124  *
125  * On exit, returns 1 when the buffer is empty,
126  * 0 when the buffer is not empty on exit,
127  * and -errno when an error occurred.
128  *
129  * Must be called while holding line->lock!*/
flush_buffer(struct line * line)130 static int flush_buffer(struct line *line)
131 {
132 	int n, count;
133 
134 	if ((line->buffer == NULL) || (line->head == line->tail))
135 		return 1;
136 
137 	if (line->tail < line->head) {
138 		/* line->buffer + LINE_BUFSIZE is the end of the buffer! */
139 		count = line->buffer + LINE_BUFSIZE - line->head;
140 
141 		n = write_chan(line->chan_out, line->head, count,
142 			       line->write_irq);
143 		if (n < 0)
144 			return n;
145 		if (n == count) {
146 			/*
147 			 * We have flushed from ->head to buffer end, now we
148 			 * must flush only from the beginning to ->tail.
149 			 */
150 			line->head = line->buffer;
151 		} else {
152 			line->head += n;
153 			return 0;
154 		}
155 	}
156 
157 	count = line->tail - line->head;
158 	n = write_chan(line->chan_out, line->head, count,
159 		       line->write_irq);
160 
161 	if (n < 0)
162 		return n;
163 
164 	line->head += n;
165 	return line->head == line->tail;
166 }
167 
line_flush_buffer(struct tty_struct * tty)168 void line_flush_buffer(struct tty_struct *tty)
169 {
170 	struct line *line = tty->driver_data;
171 	unsigned long flags;
172 
173 	spin_lock_irqsave(&line->lock, flags);
174 	flush_buffer(line);
175 	spin_unlock_irqrestore(&line->lock, flags);
176 }
177 
178 /*
179  * We map both ->flush_chars and ->put_char (which go in pair) onto
180  * ->flush_buffer and ->write. Hope it's not that bad.
181  */
line_flush_chars(struct tty_struct * tty)182 void line_flush_chars(struct tty_struct *tty)
183 {
184 	line_flush_buffer(tty);
185 }
186 
line_write(struct tty_struct * tty,const unsigned char * buf,int len)187 int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
188 {
189 	struct line *line = tty->driver_data;
190 	unsigned long flags;
191 	int n, ret = 0;
192 
193 	spin_lock_irqsave(&line->lock, flags);
194 	if (line->head != line->tail)
195 		ret = buffer_data(line, buf, len);
196 	else {
197 		n = write_chan(line->chan_out, buf, len,
198 			       line->write_irq);
199 		if (n < 0) {
200 			ret = n;
201 			goto out_up;
202 		}
203 
204 		len -= n;
205 		ret += n;
206 		if (len > 0)
207 			ret += buffer_data(line, buf + n, len);
208 	}
209 out_up:
210 	spin_unlock_irqrestore(&line->lock, flags);
211 	return ret;
212 }
213 
line_throttle(struct tty_struct * tty)214 void line_throttle(struct tty_struct *tty)
215 {
216 	struct line *line = tty->driver_data;
217 
218 	deactivate_chan(line->chan_in, line->read_irq);
219 	line->throttled = 1;
220 }
221 
line_unthrottle(struct tty_struct * tty)222 void line_unthrottle(struct tty_struct *tty)
223 {
224 	struct line *line = tty->driver_data;
225 
226 	line->throttled = 0;
227 	chan_interrupt(line, line->read_irq);
228 }
229 
line_write_interrupt(int irq,void * data)230 static irqreturn_t line_write_interrupt(int irq, void *data)
231 {
232 	struct chan *chan = data;
233 	struct line *line = chan->line;
234 	int err;
235 
236 	/*
237 	 * Interrupts are disabled here because genirq keep irqs disabled when
238 	 * calling the action handler.
239 	 */
240 
241 	spin_lock(&line->lock);
242 	err = flush_buffer(line);
243 	if (err == 0) {
244 		spin_unlock(&line->lock);
245 		return IRQ_NONE;
246 	} else if ((err < 0) && (err != -EAGAIN)) {
247 		line->head = line->buffer;
248 		line->tail = line->buffer;
249 	}
250 	spin_unlock(&line->lock);
251 
252 	tty_port_tty_wakeup(&line->port);
253 
254 	return IRQ_HANDLED;
255 }
256 
line_setup_irq(int fd,int input,int output,struct line * line,void * data)257 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
258 {
259 	const struct line_driver *driver = line->driver;
260 	int err;
261 
262 	if (input) {
263 		err = um_request_irq(UM_IRQ_ALLOC, fd, IRQ_READ,
264 				     line_interrupt, 0,
265 				     driver->read_irq_name, data);
266 		if (err < 0)
267 			return err;
268 
269 		line->read_irq = err;
270 	}
271 
272 	if (output) {
273 		err = um_request_irq(UM_IRQ_ALLOC, fd, IRQ_WRITE,
274 				     line_write_interrupt, 0,
275 				     driver->write_irq_name, data);
276 		if (err < 0)
277 			return err;
278 
279 		line->write_irq = err;
280 	}
281 
282 	return 0;
283 }
284 
line_activate(struct tty_port * port,struct tty_struct * tty)285 static int line_activate(struct tty_port *port, struct tty_struct *tty)
286 {
287 	int ret;
288 	struct line *line = tty->driver_data;
289 
290 	ret = enable_chan(line);
291 	if (ret)
292 		return ret;
293 
294 	if (!line->sigio) {
295 		chan_enable_winch(line->chan_out, port);
296 		line->sigio = 1;
297 	}
298 
299 	chan_window_size(line, &tty->winsize.ws_row,
300 		&tty->winsize.ws_col);
301 
302 	return 0;
303 }
304 
305 static void unregister_winch(struct tty_struct *tty);
306 
line_destruct(struct tty_port * port)307 static void line_destruct(struct tty_port *port)
308 {
309 	struct tty_struct *tty = tty_port_tty_get(port);
310 	struct line *line = tty->driver_data;
311 
312 	if (line->sigio) {
313 		unregister_winch(tty);
314 		line->sigio = 0;
315 	}
316 }
317 
318 static const struct tty_port_operations line_port_ops = {
319 	.activate = line_activate,
320 	.destruct = line_destruct,
321 };
322 
line_open(struct tty_struct * tty,struct file * filp)323 int line_open(struct tty_struct *tty, struct file *filp)
324 {
325 	struct line *line = tty->driver_data;
326 
327 	return tty_port_open(&line->port, tty, filp);
328 }
329 
line_install(struct tty_driver * driver,struct tty_struct * tty,struct line * line)330 int line_install(struct tty_driver *driver, struct tty_struct *tty,
331 		 struct line *line)
332 {
333 	int ret;
334 
335 	ret = tty_standard_install(driver, tty);
336 	if (ret)
337 		return ret;
338 
339 	tty->driver_data = line;
340 
341 	return 0;
342 }
343 
line_close(struct tty_struct * tty,struct file * filp)344 void line_close(struct tty_struct *tty, struct file * filp)
345 {
346 	struct line *line = tty->driver_data;
347 
348 	tty_port_close(&line->port, tty, filp);
349 }
350 
line_hangup(struct tty_struct * tty)351 void line_hangup(struct tty_struct *tty)
352 {
353 	struct line *line = tty->driver_data;
354 
355 	tty_port_hangup(&line->port);
356 }
357 
close_lines(struct line * lines,int nlines)358 void close_lines(struct line *lines, int nlines)
359 {
360 	int i;
361 
362 	for(i = 0; i < nlines; i++)
363 		close_chan(&lines[i]);
364 }
365 
setup_one_line(struct line * lines,int n,char * init,const struct chan_opts * opts,char ** error_out)366 int setup_one_line(struct line *lines, int n, char *init,
367 		   const struct chan_opts *opts, char **error_out)
368 {
369 	struct line *line = &lines[n];
370 	struct tty_driver *driver = line->driver->driver;
371 	int err = -EINVAL;
372 
373 	if (line->port.count) {
374 		*error_out = "Device is already open";
375 		goto out;
376 	}
377 
378 	if (!strcmp(init, "none")) {
379 		if (line->valid) {
380 			line->valid = 0;
381 			kfree(line->init_str);
382 			tty_unregister_device(driver, n);
383 			parse_chan_pair(NULL, line, n, opts, error_out);
384 			err = 0;
385 		}
386 	} else {
387 		char *new = kstrdup(init, GFP_KERNEL);
388 		if (!new) {
389 			*error_out = "Failed to allocate memory";
390 			return -ENOMEM;
391 		}
392 		if (line->valid) {
393 			tty_unregister_device(driver, n);
394 			kfree(line->init_str);
395 		}
396 		line->init_str = new;
397 		line->valid = 1;
398 		err = parse_chan_pair(new, line, n, opts, error_out);
399 		if (!err) {
400 			struct device *d = tty_port_register_device(&line->port,
401 					driver, n, NULL);
402 			if (IS_ERR(d)) {
403 				*error_out = "Failed to register device";
404 				err = PTR_ERR(d);
405 				parse_chan_pair(NULL, line, n, opts, error_out);
406 			}
407 		}
408 		if (err) {
409 			line->init_str = NULL;
410 			line->valid = 0;
411 			kfree(new);
412 		}
413 	}
414 out:
415 	return err;
416 }
417 
418 /*
419  * Common setup code for both startup command line and mconsole initialization.
420  * @lines contains the array (of size @num) to modify;
421  * @init is the setup string;
422  * @error_out is an error string in the case of failure;
423  */
424 
line_setup(char ** conf,unsigned int num,char ** def,char * init,char * name)425 int line_setup(char **conf, unsigned int num, char **def,
426 	       char *init, char *name)
427 {
428 	char *error;
429 
430 	if (*init == '=') {
431 		/*
432 		 * We said con=/ssl= instead of con#=, so we are configuring all
433 		 * consoles at once.
434 		 */
435 		*def = init + 1;
436 	} else {
437 		char *end;
438 		unsigned n = simple_strtoul(init, &end, 0);
439 
440 		if (*end != '=') {
441 			error = "Couldn't parse device number";
442 			goto out;
443 		}
444 		if (n >= num) {
445 			error = "Device number out of range";
446 			goto out;
447 		}
448 		conf[n] = end + 1;
449 	}
450 	return 0;
451 
452 out:
453 	printk(KERN_ERR "Failed to set up %s with "
454 	       "configuration string \"%s\" : %s\n", name, init, error);
455 	return -EINVAL;
456 }
457 
line_config(struct line * lines,unsigned int num,char * str,const struct chan_opts * opts,char ** error_out)458 int line_config(struct line *lines, unsigned int num, char *str,
459 		const struct chan_opts *opts, char **error_out)
460 {
461 	char *end;
462 	int n;
463 
464 	if (*str == '=') {
465 		*error_out = "Can't configure all devices from mconsole";
466 		return -EINVAL;
467 	}
468 
469 	n = simple_strtoul(str, &end, 0);
470 	if (*end++ != '=') {
471 		*error_out = "Couldn't parse device number";
472 		return -EINVAL;
473 	}
474 	if (n >= num) {
475 		*error_out = "Device number out of range";
476 		return -EINVAL;
477 	}
478 
479 	return setup_one_line(lines, n, end, opts, error_out);
480 }
481 
line_get_config(char * name,struct line * lines,unsigned int num,char * str,int size,char ** error_out)482 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
483 		    int size, char **error_out)
484 {
485 	struct line *line;
486 	char *end;
487 	int dev, n = 0;
488 
489 	dev = simple_strtoul(name, &end, 0);
490 	if ((*end != '\0') || (end == name)) {
491 		*error_out = "line_get_config failed to parse device number";
492 		return 0;
493 	}
494 
495 	if ((dev < 0) || (dev >= num)) {
496 		*error_out = "device number out of range";
497 		return 0;
498 	}
499 
500 	line = &lines[dev];
501 
502 	if (!line->valid)
503 		CONFIG_CHUNK(str, size, n, "none", 1);
504 	else {
505 		struct tty_struct *tty = tty_port_tty_get(&line->port);
506 		if (tty == NULL) {
507 			CONFIG_CHUNK(str, size, n, line->init_str, 1);
508 		} else {
509 			n = chan_config_string(line, str, size, error_out);
510 			tty_kref_put(tty);
511 		}
512 	}
513 
514 	return n;
515 }
516 
line_id(char ** str,int * start_out,int * end_out)517 int line_id(char **str, int *start_out, int *end_out)
518 {
519 	char *end;
520 	int n;
521 
522 	n = simple_strtoul(*str, &end, 0);
523 	if ((*end != '\0') || (end == *str))
524 		return -1;
525 
526 	*str = end;
527 	*start_out = n;
528 	*end_out = n;
529 	return n;
530 }
531 
line_remove(struct line * lines,unsigned int num,int n,char ** error_out)532 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
533 {
534 	if (n >= num) {
535 		*error_out = "Device number out of range";
536 		return -EINVAL;
537 	}
538 	return setup_one_line(lines, n, "none", NULL, error_out);
539 }
540 
register_lines(struct line_driver * line_driver,const struct tty_operations * ops,struct line * lines,int nlines)541 int register_lines(struct line_driver *line_driver,
542 		   const struct tty_operations *ops,
543 		   struct line *lines, int nlines)
544 {
545 	struct tty_driver *driver;
546 	int err;
547 	int i;
548 
549 	driver = tty_alloc_driver(nlines, TTY_DRIVER_REAL_RAW |
550 			TTY_DRIVER_DYNAMIC_DEV);
551 	if (IS_ERR(driver))
552 		return PTR_ERR(driver);
553 
554 	driver->driver_name = line_driver->name;
555 	driver->name = line_driver->device_name;
556 	driver->major = line_driver->major;
557 	driver->minor_start = line_driver->minor_start;
558 	driver->type = line_driver->type;
559 	driver->subtype = line_driver->subtype;
560 	driver->init_termios = tty_std_termios;
561 
562 	for (i = 0; i < nlines; i++) {
563 		tty_port_init(&lines[i].port);
564 		lines[i].port.ops = &line_port_ops;
565 		spin_lock_init(&lines[i].lock);
566 		lines[i].driver = line_driver;
567 		INIT_LIST_HEAD(&lines[i].chan_list);
568 	}
569 	tty_set_operations(driver, ops);
570 
571 	err = tty_register_driver(driver);
572 	if (err) {
573 		printk(KERN_ERR "register_lines : can't register %s driver\n",
574 		       line_driver->name);
575 		tty_driver_kref_put(driver);
576 		for (i = 0; i < nlines; i++)
577 			tty_port_destroy(&lines[i].port);
578 		return err;
579 	}
580 
581 	line_driver->driver = driver;
582 	mconsole_register_dev(&line_driver->mc);
583 	return 0;
584 }
585 
586 static DEFINE_SPINLOCK(winch_handler_lock);
587 static LIST_HEAD(winch_handlers);
588 
589 struct winch {
590 	struct list_head list;
591 	int fd;
592 	int tty_fd;
593 	int pid;
594 	struct tty_port *port;
595 	unsigned long stack;
596 	struct work_struct work;
597 };
598 
__free_winch(struct work_struct * work)599 static void __free_winch(struct work_struct *work)
600 {
601 	struct winch *winch = container_of(work, struct winch, work);
602 	um_free_irq(WINCH_IRQ, winch);
603 
604 	if (winch->pid != -1)
605 		os_kill_process(winch->pid, 1);
606 	if (winch->stack != 0)
607 		free_stack(winch->stack, 0);
608 	kfree(winch);
609 }
610 
free_winch(struct winch * winch)611 static void free_winch(struct winch *winch)
612 {
613 	int fd = winch->fd;
614 	winch->fd = -1;
615 	if (fd != -1)
616 		os_close_file(fd);
617 	__free_winch(&winch->work);
618 }
619 
winch_interrupt(int irq,void * data)620 static irqreturn_t winch_interrupt(int irq, void *data)
621 {
622 	struct winch *winch = data;
623 	struct tty_struct *tty;
624 	struct line *line;
625 	int fd = winch->fd;
626 	int err;
627 	char c;
628 	struct pid *pgrp;
629 
630 	if (fd != -1) {
631 		err = generic_read(fd, &c, NULL);
632 		if (err < 0) {
633 			if (err != -EAGAIN) {
634 				winch->fd = -1;
635 				list_del(&winch->list);
636 				os_close_file(fd);
637 				printk(KERN_ERR "winch_interrupt : "
638 				       "read failed, errno = %d\n", -err);
639 				printk(KERN_ERR "fd %d is losing SIGWINCH "
640 				       "support\n", winch->tty_fd);
641 				INIT_WORK(&winch->work, __free_winch);
642 				schedule_work(&winch->work);
643 				return IRQ_HANDLED;
644 			}
645 			goto out;
646 		}
647 	}
648 	tty = tty_port_tty_get(winch->port);
649 	if (tty != NULL) {
650 		line = tty->driver_data;
651 		if (line != NULL) {
652 			chan_window_size(line, &tty->winsize.ws_row,
653 					 &tty->winsize.ws_col);
654 			pgrp = tty_get_pgrp(tty);
655 			if (pgrp)
656 				kill_pgrp(pgrp, SIGWINCH, 1);
657 			put_pid(pgrp);
658 		}
659 		tty_kref_put(tty);
660 	}
661  out:
662 	return IRQ_HANDLED;
663 }
664 
register_winch_irq(int fd,int tty_fd,int pid,struct tty_port * port,unsigned long stack)665 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
666 			unsigned long stack)
667 {
668 	struct winch *winch;
669 
670 	winch = kmalloc(sizeof(*winch), GFP_KERNEL);
671 	if (winch == NULL) {
672 		printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
673 		goto cleanup;
674 	}
675 
676 	*winch = ((struct winch) { .list  	= LIST_HEAD_INIT(winch->list),
677 				   .fd  	= fd,
678 				   .tty_fd 	= tty_fd,
679 				   .pid  	= pid,
680 				   .port 	= port,
681 				   .stack	= stack });
682 
683 	if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
684 			   IRQF_SHARED, "winch", winch) < 0) {
685 		printk(KERN_ERR "register_winch_irq - failed to register "
686 		       "IRQ\n");
687 		goto out_free;
688 	}
689 
690 	spin_lock(&winch_handler_lock);
691 	list_add(&winch->list, &winch_handlers);
692 	spin_unlock(&winch_handler_lock);
693 
694 	return;
695 
696  out_free:
697 	kfree(winch);
698  cleanup:
699 	os_kill_process(pid, 1);
700 	os_close_file(fd);
701 	if (stack != 0)
702 		free_stack(stack, 0);
703 }
704 
unregister_winch(struct tty_struct * tty)705 static void unregister_winch(struct tty_struct *tty)
706 {
707 	struct list_head *ele, *next;
708 	struct winch *winch;
709 	struct tty_struct *wtty;
710 
711 	spin_lock(&winch_handler_lock);
712 
713 	list_for_each_safe(ele, next, &winch_handlers) {
714 		winch = list_entry(ele, struct winch, list);
715 		wtty = tty_port_tty_get(winch->port);
716 		if (wtty == tty) {
717 			list_del(&winch->list);
718 			spin_unlock(&winch_handler_lock);
719 			free_winch(winch);
720 			break;
721 		}
722 		tty_kref_put(wtty);
723 	}
724 	spin_unlock(&winch_handler_lock);
725 }
726 
winch_cleanup(void)727 static void winch_cleanup(void)
728 {
729 	struct winch *winch;
730 
731 	spin_lock(&winch_handler_lock);
732 	while ((winch = list_first_entry_or_null(&winch_handlers,
733 						 struct winch, list))) {
734 		list_del(&winch->list);
735 		spin_unlock(&winch_handler_lock);
736 
737 		free_winch(winch);
738 
739 		spin_lock(&winch_handler_lock);
740 	}
741 
742 	spin_unlock(&winch_handler_lock);
743 }
744 __uml_exitcall(winch_cleanup);
745 
add_xterm_umid(char * base)746 char *add_xterm_umid(char *base)
747 {
748 	char *umid, *title;
749 	int len;
750 
751 	umid = get_umid();
752 	if (*umid == '\0')
753 		return base;
754 
755 	len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
756 	title = kmalloc(len, GFP_KERNEL);
757 	if (title == NULL) {
758 		printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
759 		return base;
760 	}
761 
762 	snprintf(title, len, "%s (%s)", base, umid);
763 	return title;
764 }
765