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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 */
5
6/*
7 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
8 * or rs-channels. It also implements echoing, cooked mode etc.
9 *
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
11 *
12 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
13 * tty_struct and tty_queue structures. Previously there was an array
14 * of 256 tty_struct's which was statically allocated, and the
15 * tty_queue structures were allocated at boot time. Both are now
16 * dynamically allocated only when the tty is open.
17 *
18 * Also restructured routines so that there is more of a separation
19 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
20 * the low-level tty routines (serial.c, pty.c, console.c). This
21 * makes for cleaner and more compact code. -TYT, 9/17/92
22 *
23 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
24 * which can be dynamically activated and de-activated by the line
25 * discipline handling modules (like SLIP).
26 *
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
29 * -- TYT, 1/31/92
30 *
31 * Added functionality to the OPOST tty handling. No delays, but all
32 * other bits should be there.
33 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
34 *
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
37 *
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
40 *
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
43 *
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
46 *
47 * Move console and virtual terminal code to more appropriate files,
48 * implement CONFIG_VT and generalize console device interface.
49 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
50 *
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
53 *
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
56 *
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
59 *
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
62 *
63 * Move do_SAK() into process context. Less stack use in devfs functions.
64 * alloc_tty_struct() always uses kmalloc()
65 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
66 */
67
68#include <linux/types.h>
69#include <linux/major.h>
70#include <linux/errno.h>
71#include <linux/signal.h>
72#include <linux/fcntl.h>
73#include <linux/sched/signal.h>
74#include <linux/sched/task.h>
75#include <linux/interrupt.h>
76#include <linux/tty.h>
77#include <linux/tty_driver.h>
78#include <linux/tty_flip.h>
79#include <linux/devpts_fs.h>
80#include <linux/file.h>
81#include <linux/fdtable.h>
82#include <linux/console.h>
83#include <linux/timer.h>
84#include <linux/ctype.h>
85#include <linux/kd.h>
86#include <linux/mm.h>
87#include <linux/string.h>
88#include <linux/slab.h>
89#include <linux/poll.h>
90#include <linux/ppp-ioctl.h>
91#include <linux/proc_fs.h>
92#include <linux/init.h>
93#include <linux/module.h>
94#include <linux/device.h>
95#include <linux/wait.h>
96#include <linux/bitops.h>
97#include <linux/delay.h>
98#include <linux/seq_file.h>
99#include <linux/serial.h>
100#include <linux/ratelimit.h>
101#include <linux/compat.h>
102
103#include <linux/uaccess.h>
104
105#include <linux/kbd_kern.h>
106#include <linux/vt_kern.h>
107#include <linux/selection.h>
108
109#include <linux/kmod.h>
110#include <linux/nsproxy.h>
111
112#undef TTY_DEBUG_HANGUP
113#ifdef TTY_DEBUG_HANGUP
114# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
115#else
116# define tty_debug_hangup(tty, f, args...) do { } while (0)
117#endif
118
119#define TTY_PARANOIA_CHECK 1
120#define CHECK_TTY_COUNT 1
121
122struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
123 .c_iflag = ICRNL | IXON,
124 .c_oflag = OPOST | ONLCR,
125 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
126 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
127 ECHOCTL | ECHOKE | IEXTEN,
128 .c_cc = INIT_C_CC,
129 .c_ispeed = 38400,
130 .c_ospeed = 38400,
131 /* .c_line = N_TTY, */
132};
133
134EXPORT_SYMBOL(tty_std_termios);
135
136/* This list gets poked at by procfs and various bits of boot up code. This
137 could do with some rationalisation such as pulling the tty proc function
138 into this file */
139
140LIST_HEAD(tty_drivers); /* linked list of tty drivers */
141
142/* Mutex to protect creating and releasing a tty */
143DEFINE_MUTEX(tty_mutex);
144
145static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
146static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
147ssize_t redirected_tty_write(struct file *, const char __user *,
148 size_t, loff_t *);
149static __poll_t tty_poll(struct file *, poll_table *);
150static int tty_open(struct inode *, struct file *);
151long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
152#ifdef CONFIG_COMPAT
153static long tty_compat_ioctl(struct file *file, unsigned int cmd,
154 unsigned long arg);
155#else
156#define tty_compat_ioctl NULL
157#endif
158static int __tty_fasync(int fd, struct file *filp, int on);
159static int tty_fasync(int fd, struct file *filp, int on);
160static void release_tty(struct tty_struct *tty, int idx);
161
162/**
163 * free_tty_struct - free a disused tty
164 * @tty: tty struct to free
165 *
166 * Free the write buffers, tty queue and tty memory itself.
167 *
168 * Locking: none. Must be called after tty is definitely unused
169 */
170
171static void free_tty_struct(struct tty_struct *tty)
172{
173 tty_ldisc_deinit(tty);
174 put_device(tty->dev);
175 kfree(tty->write_buf);
176 tty->magic = 0xDEADDEAD;
177 kfree(tty);
178}
179
180static inline struct tty_struct *file_tty(struct file *file)
181{
182 return ((struct tty_file_private *)file->private_data)->tty;
183}
184
185int tty_alloc_file(struct file *file)
186{
187 struct tty_file_private *priv;
188
189 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
190 if (!priv)
191 return -ENOMEM;
192
193 file->private_data = priv;
194
195 return 0;
196}
197
198/* Associate a new file with the tty structure */
199void tty_add_file(struct tty_struct *tty, struct file *file)
200{
201 struct tty_file_private *priv = file->private_data;
202
203 priv->tty = tty;
204 priv->file = file;
205
206 spin_lock(&tty->files_lock);
207 list_add(&priv->list, &tty->tty_files);
208 spin_unlock(&tty->files_lock);
209}
210
211/**
212 * tty_free_file - free file->private_data
213 *
214 * This shall be used only for fail path handling when tty_add_file was not
215 * called yet.
216 */
217void tty_free_file(struct file *file)
218{
219 struct tty_file_private *priv = file->private_data;
220
221 file->private_data = NULL;
222 kfree(priv);
223}
224
225/* Delete file from its tty */
226static void tty_del_file(struct file *file)
227{
228 struct tty_file_private *priv = file->private_data;
229 struct tty_struct *tty = priv->tty;
230
231 spin_lock(&tty->files_lock);
232 list_del(&priv->list);
233 spin_unlock(&tty->files_lock);
234 tty_free_file(file);
235}
236
237/**
238 * tty_name - return tty naming
239 * @tty: tty structure
240 *
241 * Convert a tty structure into a name. The name reflects the kernel
242 * naming policy and if udev is in use may not reflect user space
243 *
244 * Locking: none
245 */
246
247const char *tty_name(const struct tty_struct *tty)
248{
249 if (!tty) /* Hmm. NULL pointer. That's fun. */
250 return "NULL tty";
251 return tty->name;
252}
253
254EXPORT_SYMBOL(tty_name);
255
256const char *tty_driver_name(const struct tty_struct *tty)
257{
258 if (!tty || !tty->driver)
259 return "";
260 return tty->driver->name;
261}
262
263static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
264 const char *routine)
265{
266#ifdef TTY_PARANOIA_CHECK
267 if (!tty) {
268 pr_warn("(%d:%d): %s: NULL tty\n",
269 imajor(inode), iminor(inode), routine);
270 return 1;
271 }
272 if (tty->magic != TTY_MAGIC) {
273 pr_warn("(%d:%d): %s: bad magic number\n",
274 imajor(inode), iminor(inode), routine);
275 return 1;
276 }
277#endif
278 return 0;
279}
280
281/* Caller must hold tty_lock */
282static int check_tty_count(struct tty_struct *tty, const char *routine)
283{
284#ifdef CHECK_TTY_COUNT
285 struct list_head *p;
286 int count = 0, kopen_count = 0;
287
288 spin_lock(&tty->files_lock);
289 list_for_each(p, &tty->tty_files) {
290 count++;
291 }
292 spin_unlock(&tty->files_lock);
293 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
294 tty->driver->subtype == PTY_TYPE_SLAVE &&
295 tty->link && tty->link->count)
296 count++;
297 if (tty_port_kopened(tty->port))
298 kopen_count++;
299 if (tty->count != (count + kopen_count)) {
300 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
301 routine, tty->count, count, kopen_count);
302 return (count + kopen_count);
303 }
304#endif
305 return 0;
306}
307
308/**
309 * get_tty_driver - find device of a tty
310 * @dev_t: device identifier
311 * @index: returns the index of the tty
312 *
313 * This routine returns a tty driver structure, given a device number
314 * and also passes back the index number.
315 *
316 * Locking: caller must hold tty_mutex
317 */
318
319static struct tty_driver *get_tty_driver(dev_t device, int *index)
320{
321 struct tty_driver *p;
322
323 list_for_each_entry(p, &tty_drivers, tty_drivers) {
324 dev_t base = MKDEV(p->major, p->minor_start);
325 if (device < base || device >= base + p->num)
326 continue;
327 *index = device - base;
328 return tty_driver_kref_get(p);
329 }
330 return NULL;
331}
332
333/**
334 * tty_dev_name_to_number - return dev_t for device name
335 * @name: user space name of device under /dev
336 * @number: pointer to dev_t that this function will populate
337 *
338 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
339 * like (4, 64) or (188, 1). If no corresponding driver is registered then
340 * the function returns -ENODEV.
341 *
342 * Locking: this acquires tty_mutex to protect the tty_drivers list from
343 * being modified while we are traversing it, and makes sure to
344 * release it before exiting.
345 */
346int tty_dev_name_to_number(const char *name, dev_t *number)
347{
348 struct tty_driver *p;
349 int ret;
350 int index, prefix_length = 0;
351 const char *str;
352
353 for (str = name; *str && !isdigit(*str); str++)
354 ;
355
356 if (!*str)
357 return -EINVAL;
358
359 ret = kstrtoint(str, 10, &index);
360 if (ret)
361 return ret;
362
363 prefix_length = str - name;
364 mutex_lock(&tty_mutex);
365
366 list_for_each_entry(p, &tty_drivers, tty_drivers)
367 if (prefix_length == strlen(p->name) && strncmp(name,
368 p->name, prefix_length) == 0) {
369 if (index < p->num) {
370 *number = MKDEV(p->major, p->minor_start + index);
371 goto out;
372 }
373 }
374
375 /* if here then driver wasn't found */
376 ret = -ENODEV;
377out:
378 mutex_unlock(&tty_mutex);
379 return ret;
380}
381EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
382
383#ifdef CONFIG_CONSOLE_POLL
384
385/**
386 * tty_find_polling_driver - find device of a polled tty
387 * @name: name string to match
388 * @line: pointer to resulting tty line nr
389 *
390 * This routine returns a tty driver structure, given a name
391 * and the condition that the tty driver is capable of polled
392 * operation.
393 */
394struct tty_driver *tty_find_polling_driver(char *name, int *line)
395{
396 struct tty_driver *p, *res = NULL;
397 int tty_line = 0;
398 int len;
399 char *str, *stp;
400
401 for (str = name; *str; str++)
402 if ((*str >= '0' && *str <= '9') || *str == ',')
403 break;
404 if (!*str)
405 return NULL;
406
407 len = str - name;
408 tty_line = simple_strtoul(str, &str, 10);
409
410 mutex_lock(&tty_mutex);
411 /* Search through the tty devices to look for a match */
412 list_for_each_entry(p, &tty_drivers, tty_drivers) {
413 if (!len || strncmp(name, p->name, len) != 0)
414 continue;
415 stp = str;
416 if (*stp == ',')
417 stp++;
418 if (*stp == '\0')
419 stp = NULL;
420
421 if (tty_line >= 0 && tty_line < p->num && p->ops &&
422 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
423 res = tty_driver_kref_get(p);
424 *line = tty_line;
425 break;
426 }
427 }
428 mutex_unlock(&tty_mutex);
429
430 return res;
431}
432EXPORT_SYMBOL_GPL(tty_find_polling_driver);
433#endif
434
435static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
436 size_t count, loff_t *ppos)
437{
438 return 0;
439}
440
441static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
442 size_t count, loff_t *ppos)
443{
444 return -EIO;
445}
446
447/* No kernel lock held - none needed ;) */
448static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
449{
450 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
451}
452
453static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
454 unsigned long arg)
455{
456 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
457}
458
459static long hung_up_tty_compat_ioctl(struct file *file,
460 unsigned int cmd, unsigned long arg)
461{
462 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
463}
464
465static int hung_up_tty_fasync(int fd, struct file *file, int on)
466{
467 return -ENOTTY;
468}
469
470static void tty_show_fdinfo(struct seq_file *m, struct file *file)
471{
472 struct tty_struct *tty = file_tty(file);
473
474 if (tty && tty->ops && tty->ops->show_fdinfo)
475 tty->ops->show_fdinfo(tty, m);
476}
477
478static const struct file_operations tty_fops = {
479 .llseek = no_llseek,
480 .read = tty_read,
481 .write = tty_write,
482 .poll = tty_poll,
483 .unlocked_ioctl = tty_ioctl,
484 .compat_ioctl = tty_compat_ioctl,
485 .open = tty_open,
486 .release = tty_release,
487 .fasync = tty_fasync,
488 .show_fdinfo = tty_show_fdinfo,
489};
490
491static const struct file_operations console_fops = {
492 .llseek = no_llseek,
493 .read = tty_read,
494 .write = redirected_tty_write,
495 .poll = tty_poll,
496 .unlocked_ioctl = tty_ioctl,
497 .compat_ioctl = tty_compat_ioctl,
498 .open = tty_open,
499 .release = tty_release,
500 .fasync = tty_fasync,
501};
502
503static const struct file_operations hung_up_tty_fops = {
504 .llseek = no_llseek,
505 .read = hung_up_tty_read,
506 .write = hung_up_tty_write,
507 .poll = hung_up_tty_poll,
508 .unlocked_ioctl = hung_up_tty_ioctl,
509 .compat_ioctl = hung_up_tty_compat_ioctl,
510 .release = tty_release,
511 .fasync = hung_up_tty_fasync,
512};
513
514static DEFINE_SPINLOCK(redirect_lock);
515static struct file *redirect;
516
517extern void tty_sysctl_init(void);
518
519/**
520 * tty_wakeup - request more data
521 * @tty: terminal
522 *
523 * Internal and external helper for wakeups of tty. This function
524 * informs the line discipline if present that the driver is ready
525 * to receive more output data.
526 */
527
528void tty_wakeup(struct tty_struct *tty)
529{
530 struct tty_ldisc *ld;
531
532 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
533 ld = tty_ldisc_ref(tty);
534 if (ld) {
535 if (ld->ops->write_wakeup)
536 ld->ops->write_wakeup(tty);
537 tty_ldisc_deref(ld);
538 }
539 }
540 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
541}
542
543EXPORT_SYMBOL_GPL(tty_wakeup);
544
545/**
546 * __tty_hangup - actual handler for hangup events
547 * @work: tty device
548 *
549 * This can be called by a "kworker" kernel thread. That is process
550 * synchronous but doesn't hold any locks, so we need to make sure we
551 * have the appropriate locks for what we're doing.
552 *
553 * The hangup event clears any pending redirections onto the hung up
554 * device. It ensures future writes will error and it does the needed
555 * line discipline hangup and signal delivery. The tty object itself
556 * remains intact.
557 *
558 * Locking:
559 * BTM
560 * redirect lock for undoing redirection
561 * file list lock for manipulating list of ttys
562 * tty_ldiscs_lock from called functions
563 * termios_rwsem resetting termios data
564 * tasklist_lock to walk task list for hangup event
565 * ->siglock to protect ->signal/->sighand
566 */
567static void __tty_hangup(struct tty_struct *tty, int exit_session)
568{
569 struct file *cons_filp = NULL;
570 struct file *filp, *f = NULL;
571 struct tty_file_private *priv;
572 int closecount = 0, n;
573 int refs;
574
575 if (!tty)
576 return;
577
578
579 spin_lock(&redirect_lock);
580 if (redirect && file_tty(redirect) == tty) {
581 f = redirect;
582 redirect = NULL;
583 }
584 spin_unlock(&redirect_lock);
585
586 tty_lock(tty);
587
588 if (test_bit(TTY_HUPPED, &tty->flags)) {
589 tty_unlock(tty);
590 return;
591 }
592
593 /*
594 * Some console devices aren't actually hung up for technical and
595 * historical reasons, which can lead to indefinite interruptible
596 * sleep in n_tty_read(). The following explicitly tells
597 * n_tty_read() to abort readers.
598 */
599 set_bit(TTY_HUPPING, &tty->flags);
600
601 /* inuse_filps is protected by the single tty lock,
602 this really needs to change if we want to flush the
603 workqueue with the lock held */
604 check_tty_count(tty, "tty_hangup");
605
606 spin_lock(&tty->files_lock);
607 /* This breaks for file handles being sent over AF_UNIX sockets ? */
608 list_for_each_entry(priv, &tty->tty_files, list) {
609 filp = priv->file;
610 if (filp->f_op->write == redirected_tty_write)
611 cons_filp = filp;
612 if (filp->f_op->write != tty_write)
613 continue;
614 closecount++;
615 __tty_fasync(-1, filp, 0); /* can't block */
616 filp->f_op = &hung_up_tty_fops;
617 }
618 spin_unlock(&tty->files_lock);
619
620 refs = tty_signal_session_leader(tty, exit_session);
621 /* Account for the p->signal references we killed */
622 while (refs--)
623 tty_kref_put(tty);
624
625 tty_ldisc_hangup(tty, cons_filp != NULL);
626
627 spin_lock_irq(&tty->ctrl_lock);
628 clear_bit(TTY_THROTTLED, &tty->flags);
629 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
630 put_pid(tty->session);
631 put_pid(tty->pgrp);
632 tty->session = NULL;
633 tty->pgrp = NULL;
634 tty->ctrl_status = 0;
635 spin_unlock_irq(&tty->ctrl_lock);
636
637 /*
638 * If one of the devices matches a console pointer, we
639 * cannot just call hangup() because that will cause
640 * tty->count and state->count to go out of sync.
641 * So we just call close() the right number of times.
642 */
643 if (cons_filp) {
644 if (tty->ops->close)
645 for (n = 0; n < closecount; n++)
646 tty->ops->close(tty, cons_filp);
647 } else if (tty->ops->hangup)
648 tty->ops->hangup(tty);
649 /*
650 * We don't want to have driver/ldisc interactions beyond the ones
651 * we did here. The driver layer expects no calls after ->hangup()
652 * from the ldisc side, which is now guaranteed.
653 */
654 set_bit(TTY_HUPPED, &tty->flags);
655 clear_bit(TTY_HUPPING, &tty->flags);
656 tty_unlock(tty);
657
658 if (f)
659 fput(f);
660}
661
662static void do_tty_hangup(struct work_struct *work)
663{
664 struct tty_struct *tty =
665 container_of(work, struct tty_struct, hangup_work);
666
667 __tty_hangup(tty, 0);
668}
669
670/**
671 * tty_hangup - trigger a hangup event
672 * @tty: tty to hangup
673 *
674 * A carrier loss (virtual or otherwise) has occurred on this like
675 * schedule a hangup sequence to run after this event.
676 */
677
678void tty_hangup(struct tty_struct *tty)
679{
680 tty_debug_hangup(tty, "hangup\n");
681 schedule_work(&tty->hangup_work);
682}
683
684EXPORT_SYMBOL(tty_hangup);
685
686/**
687 * tty_vhangup - process vhangup
688 * @tty: tty to hangup
689 *
690 * The user has asked via system call for the terminal to be hung up.
691 * We do this synchronously so that when the syscall returns the process
692 * is complete. That guarantee is necessary for security reasons.
693 */
694
695void tty_vhangup(struct tty_struct *tty)
696{
697 tty_debug_hangup(tty, "vhangup\n");
698 __tty_hangup(tty, 0);
699}
700
701EXPORT_SYMBOL(tty_vhangup);
702
703
704/**
705 * tty_vhangup_self - process vhangup for own ctty
706 *
707 * Perform a vhangup on the current controlling tty
708 */
709
710void tty_vhangup_self(void)
711{
712 struct tty_struct *tty;
713
714 tty = get_current_tty();
715 if (tty) {
716 tty_vhangup(tty);
717 tty_kref_put(tty);
718 }
719}
720
721/**
722 * tty_vhangup_session - hangup session leader exit
723 * @tty: tty to hangup
724 *
725 * The session leader is exiting and hanging up its controlling terminal.
726 * Every process in the foreground process group is signalled SIGHUP.
727 *
728 * We do this synchronously so that when the syscall returns the process
729 * is complete. That guarantee is necessary for security reasons.
730 */
731
732void tty_vhangup_session(struct tty_struct *tty)
733{
734 tty_debug_hangup(tty, "session hangup\n");
735 __tty_hangup(tty, 1);
736}
737
738/**
739 * tty_hung_up_p - was tty hung up
740 * @filp: file pointer of tty
741 *
742 * Return true if the tty has been subject to a vhangup or a carrier
743 * loss
744 */
745
746int tty_hung_up_p(struct file *filp)
747{
748 return (filp && filp->f_op == &hung_up_tty_fops);
749}
750
751EXPORT_SYMBOL(tty_hung_up_p);
752
753/**
754 * stop_tty - propagate flow control
755 * @tty: tty to stop
756 *
757 * Perform flow control to the driver. May be called
758 * on an already stopped device and will not re-call the driver
759 * method.
760 *
761 * This functionality is used by both the line disciplines for
762 * halting incoming flow and by the driver. It may therefore be
763 * called from any context, may be under the tty atomic_write_lock
764 * but not always.
765 *
766 * Locking:
767 * flow_lock
768 */
769
770void __stop_tty(struct tty_struct *tty)
771{
772 if (tty->stopped)
773 return;
774 tty->stopped = 1;
775 if (tty->ops->stop)
776 tty->ops->stop(tty);
777}
778
779void stop_tty(struct tty_struct *tty)
780{
781 unsigned long flags;
782
783 spin_lock_irqsave(&tty->flow_lock, flags);
784 __stop_tty(tty);
785 spin_unlock_irqrestore(&tty->flow_lock, flags);
786}
787EXPORT_SYMBOL(stop_tty);
788
789/**
790 * start_tty - propagate flow control
791 * @tty: tty to start
792 *
793 * Start a tty that has been stopped if at all possible. If this
794 * tty was previous stopped and is now being started, the driver
795 * start method is invoked and the line discipline woken.
796 *
797 * Locking:
798 * flow_lock
799 */
800
801void __start_tty(struct tty_struct *tty)
802{
803 if (!tty->stopped || tty->flow_stopped)
804 return;
805 tty->stopped = 0;
806 if (tty->ops->start)
807 tty->ops->start(tty);
808 tty_wakeup(tty);
809}
810
811void start_tty(struct tty_struct *tty)
812{
813 unsigned long flags;
814
815 spin_lock_irqsave(&tty->flow_lock, flags);
816 __start_tty(tty);
817 spin_unlock_irqrestore(&tty->flow_lock, flags);
818}
819EXPORT_SYMBOL(start_tty);
820
821static void tty_update_time(struct timespec64 *time)
822{
823 time64_t sec = ktime_get_real_seconds();
824
825 /*
826 * We only care if the two values differ in anything other than the
827 * lower three bits (i.e every 8 seconds). If so, then we can update
828 * the time of the tty device, otherwise it could be construded as a
829 * security leak to let userspace know the exact timing of the tty.
830 */
831 if ((sec ^ time->tv_sec) & ~7)
832 time->tv_sec = sec;
833}
834
835/**
836 * tty_read - read method for tty device files
837 * @file: pointer to tty file
838 * @buf: user buffer
839 * @count: size of user buffer
840 * @ppos: unused
841 *
842 * Perform the read system call function on this terminal device. Checks
843 * for hung up devices before calling the line discipline method.
844 *
845 * Locking:
846 * Locks the line discipline internally while needed. Multiple
847 * read calls may be outstanding in parallel.
848 */
849
850static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
851 loff_t *ppos)
852{
853 int i;
854 struct inode *inode = file_inode(file);
855 struct tty_struct *tty = file_tty(file);
856 struct tty_ldisc *ld;
857
858 if (tty_paranoia_check(tty, inode, "tty_read"))
859 return -EIO;
860 if (!tty || tty_io_error(tty))
861 return -EIO;
862
863 /* We want to wait for the line discipline to sort out in this
864 situation */
865 ld = tty_ldisc_ref_wait(tty);
866 if (!ld)
867 return hung_up_tty_read(file, buf, count, ppos);
868 if (ld->ops->read)
869 i = ld->ops->read(tty, file, buf, count);
870 else
871 i = -EIO;
872 tty_ldisc_deref(ld);
873
874 if (i > 0)
875 tty_update_time(&inode->i_atime);
876
877 return i;
878}
879
880static void tty_write_unlock(struct tty_struct *tty)
881{
882 mutex_unlock(&tty->atomic_write_lock);
883 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
884}
885
886static int tty_write_lock(struct tty_struct *tty, int ndelay)
887{
888 if (!mutex_trylock(&tty->atomic_write_lock)) {
889 if (ndelay)
890 return -EAGAIN;
891 if (mutex_lock_interruptible(&tty->atomic_write_lock))
892 return -ERESTARTSYS;
893 }
894 return 0;
895}
896
897/*
898 * Split writes up in sane blocksizes to avoid
899 * denial-of-service type attacks
900 */
901static inline ssize_t do_tty_write(
902 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
903 struct tty_struct *tty,
904 struct file *file,
905 const char __user *buf,
906 size_t count)
907{
908 ssize_t ret, written = 0;
909 unsigned int chunk;
910
911 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
912 if (ret < 0)
913 return ret;
914
915 /*
916 * We chunk up writes into a temporary buffer. This
917 * simplifies low-level drivers immensely, since they
918 * don't have locking issues and user mode accesses.
919 *
920 * But if TTY_NO_WRITE_SPLIT is set, we should use a
921 * big chunk-size..
922 *
923 * The default chunk-size is 2kB, because the NTTY
924 * layer has problems with bigger chunks. It will
925 * claim to be able to handle more characters than
926 * it actually does.
927 *
928 * FIXME: This can probably go away now except that 64K chunks
929 * are too likely to fail unless switched to vmalloc...
930 */
931 chunk = 2048;
932 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
933 chunk = 65536;
934 if (count < chunk)
935 chunk = count;
936
937 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
938 if (tty->write_cnt < chunk) {
939 unsigned char *buf_chunk;
940
941 if (chunk < 1024)
942 chunk = 1024;
943
944 buf_chunk = kmalloc(chunk, GFP_KERNEL);
945 if (!buf_chunk) {
946 ret = -ENOMEM;
947 goto out;
948 }
949 kfree(tty->write_buf);
950 tty->write_cnt = chunk;
951 tty->write_buf = buf_chunk;
952 }
953
954 /* Do the write .. */
955 for (;;) {
956 size_t size = count;
957 if (size > chunk)
958 size = chunk;
959 ret = -EFAULT;
960 if (copy_from_user(tty->write_buf, buf, size))
961 break;
962 ret = write(tty, file, tty->write_buf, size);
963 if (ret <= 0)
964 break;
965 written += ret;
966 buf += ret;
967 count -= ret;
968 if (!count)
969 break;
970 ret = -ERESTARTSYS;
971 if (signal_pending(current))
972 break;
973 cond_resched();
974 }
975 if (written) {
976 tty_update_time(&file_inode(file)->i_mtime);
977 ret = written;
978 }
979out:
980 tty_write_unlock(tty);
981 return ret;
982}
983
984/**
985 * tty_write_message - write a message to a certain tty, not just the console.
986 * @tty: the destination tty_struct
987 * @msg: the message to write
988 *
989 * This is used for messages that need to be redirected to a specific tty.
990 * We don't put it into the syslog queue right now maybe in the future if
991 * really needed.
992 *
993 * We must still hold the BTM and test the CLOSING flag for the moment.
994 */
995
996void tty_write_message(struct tty_struct *tty, char *msg)
997{
998 if (tty) {
999 mutex_lock(&tty->atomic_write_lock);
1000 tty_lock(tty);
1001 if (tty->ops->write && tty->count > 0)
1002 tty->ops->write(tty, msg, strlen(msg));
1003 tty_unlock(tty);
1004 tty_write_unlock(tty);
1005 }
1006 return;
1007}
1008
1009
1010/**
1011 * tty_write - write method for tty device file
1012 * @file: tty file pointer
1013 * @buf: user data to write
1014 * @count: bytes to write
1015 * @ppos: unused
1016 *
1017 * Write data to a tty device via the line discipline.
1018 *
1019 * Locking:
1020 * Locks the line discipline as required
1021 * Writes to the tty driver are serialized by the atomic_write_lock
1022 * and are then processed in chunks to the device. The line discipline
1023 * write method will not be invoked in parallel for each device.
1024 */
1025
1026static ssize_t tty_write(struct file *file, const char __user *buf,
1027 size_t count, loff_t *ppos)
1028{
1029 struct tty_struct *tty = file_tty(file);
1030 struct tty_ldisc *ld;
1031 ssize_t ret;
1032
1033 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1034 return -EIO;
1035 if (!tty || !tty->ops->write || tty_io_error(tty))
1036 return -EIO;
1037 /* Short term debug to catch buggy drivers */
1038 if (tty->ops->write_room == NULL)
1039 tty_err(tty, "missing write_room method\n");
1040 ld = tty_ldisc_ref_wait(tty);
1041 if (!ld)
1042 return hung_up_tty_write(file, buf, count, ppos);
1043 if (!ld->ops->write)
1044 ret = -EIO;
1045 else
1046 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1047 tty_ldisc_deref(ld);
1048 return ret;
1049}
1050
1051ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1052 size_t count, loff_t *ppos)
1053{
1054 struct file *p = NULL;
1055
1056 spin_lock(&redirect_lock);
1057 if (redirect)
1058 p = get_file(redirect);
1059 spin_unlock(&redirect_lock);
1060
1061 if (p) {
1062 ssize_t res;
1063 res = vfs_write(p, buf, count, &p->f_pos);
1064 fput(p);
1065 return res;
1066 }
1067 return tty_write(file, buf, count, ppos);
1068}
1069
1070/**
1071 * tty_send_xchar - send priority character
1072 *
1073 * Send a high priority character to the tty even if stopped
1074 *
1075 * Locking: none for xchar method, write ordering for write method.
1076 */
1077
1078int tty_send_xchar(struct tty_struct *tty, char ch)
1079{
1080 int was_stopped = tty->stopped;
1081
1082 if (tty->ops->send_xchar) {
1083 down_read(&tty->termios_rwsem);
1084 tty->ops->send_xchar(tty, ch);
1085 up_read(&tty->termios_rwsem);
1086 return 0;
1087 }
1088
1089 if (tty_write_lock(tty, 0) < 0)
1090 return -ERESTARTSYS;
1091
1092 down_read(&tty->termios_rwsem);
1093 if (was_stopped)
1094 start_tty(tty);
1095 tty->ops->write(tty, &ch, 1);
1096 if (was_stopped)
1097 stop_tty(tty);
1098 up_read(&tty->termios_rwsem);
1099 tty_write_unlock(tty);
1100 return 0;
1101}
1102
1103static char ptychar[] = "pqrstuvwxyzabcde";
1104
1105/**
1106 * pty_line_name - generate name for a pty
1107 * @driver: the tty driver in use
1108 * @index: the minor number
1109 * @p: output buffer of at least 6 bytes
1110 *
1111 * Generate a name from a driver reference and write it to the output
1112 * buffer.
1113 *
1114 * Locking: None
1115 */
1116static void pty_line_name(struct tty_driver *driver, int index, char *p)
1117{
1118 int i = index + driver->name_base;
1119 /* ->name is initialized to "ttyp", but "tty" is expected */
1120 sprintf(p, "%s%c%x",
1121 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1122 ptychar[i >> 4 & 0xf], i & 0xf);
1123}
1124
1125/**
1126 * tty_line_name - generate name for a tty
1127 * @driver: the tty driver in use
1128 * @index: the minor number
1129 * @p: output buffer of at least 7 bytes
1130 *
1131 * Generate a name from a driver reference and write it to the output
1132 * buffer.
1133 *
1134 * Locking: None
1135 */
1136static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1137{
1138 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1139 return sprintf(p, "%s", driver->name);
1140 else
1141 return sprintf(p, "%s%d", driver->name,
1142 index + driver->name_base);
1143}
1144
1145/**
1146 * tty_driver_lookup_tty() - find an existing tty, if any
1147 * @driver: the driver for the tty
1148 * @idx: the minor number
1149 *
1150 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1151 * driver lookup() method returns an error.
1152 *
1153 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1154 */
1155static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1156 struct file *file, int idx)
1157{
1158 struct tty_struct *tty;
1159
1160 if (driver->ops->lookup)
1161 if (!file)
1162 tty = ERR_PTR(-EIO);
1163 else
1164 tty = driver->ops->lookup(driver, file, idx);
1165 else
1166 tty = driver->ttys[idx];
1167
1168 if (!IS_ERR(tty))
1169 tty_kref_get(tty);
1170 return tty;
1171}
1172
1173/**
1174 * tty_init_termios - helper for termios setup
1175 * @tty: the tty to set up
1176 *
1177 * Initialise the termios structure for this tty. This runs under
1178 * the tty_mutex currently so we can be relaxed about ordering.
1179 */
1180
1181void tty_init_termios(struct tty_struct *tty)
1182{
1183 struct ktermios *tp;
1184 int idx = tty->index;
1185
1186 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1187 tty->termios = tty->driver->init_termios;
1188 else {
1189 /* Check for lazy saved data */
1190 tp = tty->driver->termios[idx];
1191 if (tp != NULL) {
1192 tty->termios = *tp;
1193 tty->termios.c_line = tty->driver->init_termios.c_line;
1194 } else
1195 tty->termios = tty->driver->init_termios;
1196 }
1197 /* Compatibility until drivers always set this */
1198 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1199 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1200}
1201EXPORT_SYMBOL_GPL(tty_init_termios);
1202
1203int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1204{
1205 tty_init_termios(tty);
1206 tty_driver_kref_get(driver);
1207 tty->count++;
1208 driver->ttys[tty->index] = tty;
1209 return 0;
1210}
1211EXPORT_SYMBOL_GPL(tty_standard_install);
1212
1213/**
1214 * tty_driver_install_tty() - install a tty entry in the driver
1215 * @driver: the driver for the tty
1216 * @tty: the tty
1217 *
1218 * Install a tty object into the driver tables. The tty->index field
1219 * will be set by the time this is called. This method is responsible
1220 * for ensuring any need additional structures are allocated and
1221 * configured.
1222 *
1223 * Locking: tty_mutex for now
1224 */
1225static int tty_driver_install_tty(struct tty_driver *driver,
1226 struct tty_struct *tty)
1227{
1228 return driver->ops->install ? driver->ops->install(driver, tty) :
1229 tty_standard_install(driver, tty);
1230}
1231
1232/**
1233 * tty_driver_remove_tty() - remove a tty from the driver tables
1234 * @driver: the driver for the tty
1235 * @idx: the minor number
1236 *
1237 * Remvoe a tty object from the driver tables. The tty->index field
1238 * will be set by the time this is called.
1239 *
1240 * Locking: tty_mutex for now
1241 */
1242static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1243{
1244 if (driver->ops->remove)
1245 driver->ops->remove(driver, tty);
1246 else
1247 driver->ttys[tty->index] = NULL;
1248}
1249
1250/*
1251 * tty_reopen() - fast re-open of an open tty
1252 * @tty - the tty to open
1253 *
1254 * Return 0 on success, -errno on error.
1255 * Re-opens on master ptys are not allowed and return -EIO.
1256 *
1257 * Locking: Caller must hold tty_lock
1258 */
1259static int tty_reopen(struct tty_struct *tty)
1260{
1261 struct tty_driver *driver = tty->driver;
1262 struct tty_ldisc *ld;
1263 int retval = 0;
1264
1265 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1266 driver->subtype == PTY_TYPE_MASTER)
1267 return -EIO;
1268
1269 if (!tty->count)
1270 return -EAGAIN;
1271
1272 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1273 return -EBUSY;
1274
1275 ld = tty_ldisc_ref_wait(tty);
1276 if (ld) {
1277 tty_ldisc_deref(ld);
1278 } else {
1279 retval = tty_ldisc_lock(tty, 5 * HZ);
1280 if (retval)
1281 return retval;
1282
1283 if (!tty->ldisc)
1284 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1285 tty_ldisc_unlock(tty);
1286 }
1287
1288 if (retval == 0)
1289 tty->count++;
1290
1291 return retval;
1292}
1293
1294/**
1295 * tty_init_dev - initialise a tty device
1296 * @driver: tty driver we are opening a device on
1297 * @idx: device index
1298 * @ret_tty: returned tty structure
1299 *
1300 * Prepare a tty device. This may not be a "new" clean device but
1301 * could also be an active device. The pty drivers require special
1302 * handling because of this.
1303 *
1304 * Locking:
1305 * The function is called under the tty_mutex, which
1306 * protects us from the tty struct or driver itself going away.
1307 *
1308 * On exit the tty device has the line discipline attached and
1309 * a reference count of 1. If a pair was created for pty/tty use
1310 * and the other was a pty master then it too has a reference count of 1.
1311 *
1312 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1313 * failed open. The new code protects the open with a mutex, so it's
1314 * really quite straightforward. The mutex locking can probably be
1315 * relaxed for the (most common) case of reopening a tty.
1316 */
1317
1318struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1319{
1320 struct tty_struct *tty;
1321 int retval;
1322
1323 /*
1324 * First time open is complex, especially for PTY devices.
1325 * This code guarantees that either everything succeeds and the
1326 * TTY is ready for operation, or else the table slots are vacated
1327 * and the allocated memory released. (Except that the termios
1328 * may be retained.)
1329 */
1330
1331 if (!try_module_get(driver->owner))
1332 return ERR_PTR(-ENODEV);
1333
1334 tty = alloc_tty_struct(driver, idx);
1335 if (!tty) {
1336 retval = -ENOMEM;
1337 goto err_module_put;
1338 }
1339
1340 tty_lock(tty);
1341 retval = tty_driver_install_tty(driver, tty);
1342 if (retval < 0)
1343 goto err_free_tty;
1344
1345 if (!tty->port)
1346 tty->port = driver->ports[idx];
1347
1348 if (WARN_RATELIMIT(!tty->port,
1349 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1350 __func__, tty->driver->name)) {
1351 retval = -EINVAL;
1352 goto err_release_lock;
1353 }
1354
1355 retval = tty_ldisc_lock(tty, 5 * HZ);
1356 if (retval)
1357 goto err_release_lock;
1358 tty->port->itty = tty;
1359
1360 /*
1361 * Structures all installed ... call the ldisc open routines.
1362 * If we fail here just call release_tty to clean up. No need
1363 * to decrement the use counts, as release_tty doesn't care.
1364 */
1365 retval = tty_ldisc_setup(tty, tty->link);
1366 if (retval)
1367 goto err_release_tty;
1368 tty_ldisc_unlock(tty);
1369 /* Return the tty locked so that it cannot vanish under the caller */
1370 return tty;
1371
1372err_free_tty:
1373 tty_unlock(tty);
1374 free_tty_struct(tty);
1375err_module_put:
1376 module_put(driver->owner);
1377 return ERR_PTR(retval);
1378
1379 /* call the tty release_tty routine to clean out this slot */
1380err_release_tty:
1381 tty_ldisc_unlock(tty);
1382 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1383 retval, idx);
1384err_release_lock:
1385 tty_unlock(tty);
1386 release_tty(tty, idx);
1387 return ERR_PTR(retval);
1388}
1389
1390/**
1391 * tty_save_termios() - save tty termios data in driver table
1392 * @tty: tty whose termios data to save
1393 *
1394 * Locking: Caller guarantees serialisation with tty_init_termios().
1395 */
1396void tty_save_termios(struct tty_struct *tty)
1397{
1398 struct ktermios *tp;
1399 int idx = tty->index;
1400
1401 /* If the port is going to reset then it has no termios to save */
1402 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1403 return;
1404
1405 /* Stash the termios data */
1406 tp = tty->driver->termios[idx];
1407 if (tp == NULL) {
1408 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1409 if (tp == NULL)
1410 return;
1411 tty->driver->termios[idx] = tp;
1412 }
1413 *tp = tty->termios;
1414}
1415EXPORT_SYMBOL_GPL(tty_save_termios);
1416
1417/**
1418 * tty_flush_works - flush all works of a tty/pty pair
1419 * @tty: tty device to flush works for (or either end of a pty pair)
1420 *
1421 * Sync flush all works belonging to @tty (and the 'other' tty).
1422 */
1423static void tty_flush_works(struct tty_struct *tty)
1424{
1425 flush_work(&tty->SAK_work);
1426 flush_work(&tty->hangup_work);
1427 if (tty->link) {
1428 flush_work(&tty->link->SAK_work);
1429 flush_work(&tty->link->hangup_work);
1430 }
1431}
1432
1433/**
1434 * release_one_tty - release tty structure memory
1435 * @kref: kref of tty we are obliterating
1436 *
1437 * Releases memory associated with a tty structure, and clears out the
1438 * driver table slots. This function is called when a device is no longer
1439 * in use. It also gets called when setup of a device fails.
1440 *
1441 * Locking:
1442 * takes the file list lock internally when working on the list
1443 * of ttys that the driver keeps.
1444 *
1445 * This method gets called from a work queue so that the driver private
1446 * cleanup ops can sleep (needed for USB at least)
1447 */
1448static void release_one_tty(struct work_struct *work)
1449{
1450 struct tty_struct *tty =
1451 container_of(work, struct tty_struct, hangup_work);
1452 struct tty_driver *driver = tty->driver;
1453 struct module *owner = driver->owner;
1454
1455 if (tty->ops->cleanup)
1456 tty->ops->cleanup(tty);
1457
1458 tty->magic = 0;
1459 tty_driver_kref_put(driver);
1460 module_put(owner);
1461
1462 spin_lock(&tty->files_lock);
1463 list_del_init(&tty->tty_files);
1464 spin_unlock(&tty->files_lock);
1465
1466 put_pid(tty->pgrp);
1467 put_pid(tty->session);
1468 free_tty_struct(tty);
1469}
1470
1471static void queue_release_one_tty(struct kref *kref)
1472{
1473 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1474
1475 /* The hangup queue is now free so we can reuse it rather than
1476 waste a chunk of memory for each port */
1477 INIT_WORK(&tty->hangup_work, release_one_tty);
1478 schedule_work(&tty->hangup_work);
1479}
1480
1481/**
1482 * tty_kref_put - release a tty kref
1483 * @tty: tty device
1484 *
1485 * Release a reference to a tty device and if need be let the kref
1486 * layer destruct the object for us
1487 */
1488
1489void tty_kref_put(struct tty_struct *tty)
1490{
1491 if (tty)
1492 kref_put(&tty->kref, queue_release_one_tty);
1493}
1494EXPORT_SYMBOL(tty_kref_put);
1495
1496/**
1497 * release_tty - release tty structure memory
1498 *
1499 * Release both @tty and a possible linked partner (think pty pair),
1500 * and decrement the refcount of the backing module.
1501 *
1502 * Locking:
1503 * tty_mutex
1504 * takes the file list lock internally when working on the list
1505 * of ttys that the driver keeps.
1506 *
1507 */
1508static void release_tty(struct tty_struct *tty, int idx)
1509{
1510 /* This should always be true but check for the moment */
1511 WARN_ON(tty->index != idx);
1512 WARN_ON(!mutex_is_locked(&tty_mutex));
1513 if (tty->ops->shutdown)
1514 tty->ops->shutdown(tty);
1515 tty_save_termios(tty);
1516 tty_driver_remove_tty(tty->driver, tty);
1517 tty->port->itty = NULL;
1518 if (tty->link)
1519 tty->link->port->itty = NULL;
1520 tty_buffer_cancel_work(tty->port);
1521 if (tty->link)
1522 tty_buffer_cancel_work(tty->link->port);
1523
1524 tty_kref_put(tty->link);
1525 tty_kref_put(tty);
1526}
1527
1528/**
1529 * tty_release_checks - check a tty before real release
1530 * @tty: tty to check
1531 * @o_tty: link of @tty (if any)
1532 * @idx: index of the tty
1533 *
1534 * Performs some paranoid checking before true release of the @tty.
1535 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1536 */
1537static int tty_release_checks(struct tty_struct *tty, int idx)
1538{
1539#ifdef TTY_PARANOIA_CHECK
1540 if (idx < 0 || idx >= tty->driver->num) {
1541 tty_debug(tty, "bad idx %d\n", idx);
1542 return -1;
1543 }
1544
1545 /* not much to check for devpts */
1546 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1547 return 0;
1548
1549 if (tty != tty->driver->ttys[idx]) {
1550 tty_debug(tty, "bad driver table[%d] = %p\n",
1551 idx, tty->driver->ttys[idx]);
1552 return -1;
1553 }
1554 if (tty->driver->other) {
1555 struct tty_struct *o_tty = tty->link;
1556
1557 if (o_tty != tty->driver->other->ttys[idx]) {
1558 tty_debug(tty, "bad other table[%d] = %p\n",
1559 idx, tty->driver->other->ttys[idx]);
1560 return -1;
1561 }
1562 if (o_tty->link != tty) {
1563 tty_debug(tty, "bad link = %p\n", o_tty->link);
1564 return -1;
1565 }
1566 }
1567#endif
1568 return 0;
1569}
1570
1571/**
1572 * tty_kclose - closes tty opened by tty_kopen
1573 * @tty: tty device
1574 *
1575 * Performs the final steps to release and free a tty device. It is the
1576 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1577 * flag on tty->port.
1578 */
1579void tty_kclose(struct tty_struct *tty)
1580{
1581 /*
1582 * Ask the line discipline code to release its structures
1583 */
1584 tty_ldisc_release(tty);
1585
1586 /* Wait for pending work before tty destruction commmences */
1587 tty_flush_works(tty);
1588
1589 tty_debug_hangup(tty, "freeing structure\n");
1590 /*
1591 * The release_tty function takes care of the details of clearing
1592 * the slots and preserving the termios structure.
1593 */
1594 mutex_lock(&tty_mutex);
1595 tty_port_set_kopened(tty->port, 0);
1596 release_tty(tty, tty->index);
1597 mutex_unlock(&tty_mutex);
1598}
1599EXPORT_SYMBOL_GPL(tty_kclose);
1600
1601/**
1602 * tty_release_struct - release a tty struct
1603 * @tty: tty device
1604 * @idx: index of the tty
1605 *
1606 * Performs the final steps to release and free a tty device. It is
1607 * roughly the reverse of tty_init_dev.
1608 */
1609void tty_release_struct(struct tty_struct *tty, int idx)
1610{
1611 /*
1612 * Ask the line discipline code to release its structures
1613 */
1614 tty_ldisc_release(tty);
1615
1616 /* Wait for pending work before tty destruction commmences */
1617 tty_flush_works(tty);
1618
1619 tty_debug_hangup(tty, "freeing structure\n");
1620 /*
1621 * The release_tty function takes care of the details of clearing
1622 * the slots and preserving the termios structure.
1623 */
1624 mutex_lock(&tty_mutex);
1625 release_tty(tty, idx);
1626 mutex_unlock(&tty_mutex);
1627}
1628EXPORT_SYMBOL_GPL(tty_release_struct);
1629
1630/**
1631 * tty_release - vfs callback for close
1632 * @inode: inode of tty
1633 * @filp: file pointer for handle to tty
1634 *
1635 * Called the last time each file handle is closed that references
1636 * this tty. There may however be several such references.
1637 *
1638 * Locking:
1639 * Takes bkl. See tty_release_dev
1640 *
1641 * Even releasing the tty structures is a tricky business.. We have
1642 * to be very careful that the structures are all released at the
1643 * same time, as interrupts might otherwise get the wrong pointers.
1644 *
1645 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1646 * lead to double frees or releasing memory still in use.
1647 */
1648
1649int tty_release(struct inode *inode, struct file *filp)
1650{
1651 struct tty_struct *tty = file_tty(filp);
1652 struct tty_struct *o_tty = NULL;
1653 int do_sleep, final;
1654 int idx;
1655 long timeout = 0;
1656 int once = 1;
1657
1658 if (tty_paranoia_check(tty, inode, __func__))
1659 return 0;
1660
1661 tty_lock(tty);
1662 check_tty_count(tty, __func__);
1663
1664 __tty_fasync(-1, filp, 0);
1665
1666 idx = tty->index;
1667 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1668 tty->driver->subtype == PTY_TYPE_MASTER)
1669 o_tty = tty->link;
1670
1671 if (tty_release_checks(tty, idx)) {
1672 tty_unlock(tty);
1673 return 0;
1674 }
1675
1676 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1677
1678 if (tty->ops->close)
1679 tty->ops->close(tty, filp);
1680
1681 /* If tty is pty master, lock the slave pty (stable lock order) */
1682 tty_lock_slave(o_tty);
1683
1684 /*
1685 * Sanity check: if tty->count is going to zero, there shouldn't be
1686 * any waiters on tty->read_wait or tty->write_wait. We test the
1687 * wait queues and kick everyone out _before_ actually starting to
1688 * close. This ensures that we won't block while releasing the tty
1689 * structure.
1690 *
1691 * The test for the o_tty closing is necessary, since the master and
1692 * slave sides may close in any order. If the slave side closes out
1693 * first, its count will be one, since the master side holds an open.
1694 * Thus this test wouldn't be triggered at the time the slave closed,
1695 * so we do it now.
1696 */
1697 while (1) {
1698 do_sleep = 0;
1699
1700 if (tty->count <= 1) {
1701 if (waitqueue_active(&tty->read_wait)) {
1702 wake_up_poll(&tty->read_wait, EPOLLIN);
1703 do_sleep++;
1704 }
1705 if (waitqueue_active(&tty->write_wait)) {
1706 wake_up_poll(&tty->write_wait, EPOLLOUT);
1707 do_sleep++;
1708 }
1709 }
1710 if (o_tty && o_tty->count <= 1) {
1711 if (waitqueue_active(&o_tty->read_wait)) {
1712 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1713 do_sleep++;
1714 }
1715 if (waitqueue_active(&o_tty->write_wait)) {
1716 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1717 do_sleep++;
1718 }
1719 }
1720 if (!do_sleep)
1721 break;
1722
1723 if (once) {
1724 once = 0;
1725 tty_warn(tty, "read/write wait queue active!\n");
1726 }
1727 schedule_timeout_killable(timeout);
1728 if (timeout < 120 * HZ)
1729 timeout = 2 * timeout + 1;
1730 else
1731 timeout = MAX_SCHEDULE_TIMEOUT;
1732 }
1733
1734 if (o_tty) {
1735 if (--o_tty->count < 0) {
1736 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1737 o_tty->count = 0;
1738 }
1739 }
1740 if (--tty->count < 0) {
1741 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1742 tty->count = 0;
1743 }
1744
1745 /*
1746 * We've decremented tty->count, so we need to remove this file
1747 * descriptor off the tty->tty_files list; this serves two
1748 * purposes:
1749 * - check_tty_count sees the correct number of file descriptors
1750 * associated with this tty.
1751 * - do_tty_hangup no longer sees this file descriptor as
1752 * something that needs to be handled for hangups.
1753 */
1754 tty_del_file(filp);
1755
1756 /*
1757 * Perform some housekeeping before deciding whether to return.
1758 *
1759 * If _either_ side is closing, make sure there aren't any
1760 * processes that still think tty or o_tty is their controlling
1761 * tty.
1762 */
1763 if (!tty->count) {
1764 read_lock(&tasklist_lock);
1765 session_clear_tty(tty->session);
1766 if (o_tty)
1767 session_clear_tty(o_tty->session);
1768 read_unlock(&tasklist_lock);
1769 }
1770
1771 /* check whether both sides are closing ... */
1772 final = !tty->count && !(o_tty && o_tty->count);
1773
1774 tty_unlock_slave(o_tty);
1775 tty_unlock(tty);
1776
1777 /* At this point, the tty->count == 0 should ensure a dead tty
1778 cannot be re-opened by a racing opener */
1779
1780 if (!final)
1781 return 0;
1782
1783 tty_debug_hangup(tty, "final close\n");
1784
1785 tty_release_struct(tty, idx);
1786 return 0;
1787}
1788
1789/**
1790 * tty_open_current_tty - get locked tty of current task
1791 * @device: device number
1792 * @filp: file pointer to tty
1793 * @return: locked tty of the current task iff @device is /dev/tty
1794 *
1795 * Performs a re-open of the current task's controlling tty.
1796 *
1797 * We cannot return driver and index like for the other nodes because
1798 * devpts will not work then. It expects inodes to be from devpts FS.
1799 */
1800static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1801{
1802 struct tty_struct *tty;
1803 int retval;
1804
1805 if (device != MKDEV(TTYAUX_MAJOR, 0))
1806 return NULL;
1807
1808 tty = get_current_tty();
1809 if (!tty)
1810 return ERR_PTR(-ENXIO);
1811
1812 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1813 /* noctty = 1; */
1814 tty_lock(tty);
1815 tty_kref_put(tty); /* safe to drop the kref now */
1816
1817 retval = tty_reopen(tty);
1818 if (retval < 0) {
1819 tty_unlock(tty);
1820 tty = ERR_PTR(retval);
1821 }
1822 return tty;
1823}
1824
1825/**
1826 * tty_lookup_driver - lookup a tty driver for a given device file
1827 * @device: device number
1828 * @filp: file pointer to tty
1829 * @index: index for the device in the @return driver
1830 * @return: driver for this inode (with increased refcount)
1831 *
1832 * If @return is not erroneous, the caller is responsible to decrement the
1833 * refcount by tty_driver_kref_put.
1834 *
1835 * Locking: tty_mutex protects get_tty_driver
1836 */
1837static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1838 int *index)
1839{
1840 struct tty_driver *driver = NULL;
1841
1842 switch (device) {
1843#ifdef CONFIG_VT
1844 case MKDEV(TTY_MAJOR, 0): {
1845 extern struct tty_driver *console_driver;
1846 driver = tty_driver_kref_get(console_driver);
1847 *index = fg_console;
1848 break;
1849 }
1850#endif
1851 case MKDEV(TTYAUX_MAJOR, 1): {
1852 struct tty_driver *console_driver = console_device(index);
1853 if (console_driver) {
1854 driver = tty_driver_kref_get(console_driver);
1855 if (driver && filp) {
1856 /* Don't let /dev/console block */
1857 filp->f_flags |= O_NONBLOCK;
1858 break;
1859 }
1860 }
1861 if (driver)
1862 tty_driver_kref_put(driver);
1863 return ERR_PTR(-ENODEV);
1864 }
1865 default:
1866 driver = get_tty_driver(device, index);
1867 if (!driver)
1868 return ERR_PTR(-ENODEV);
1869 break;
1870 }
1871 return driver;
1872}
1873
1874/**
1875 * tty_kopen - open a tty device for kernel
1876 * @device: dev_t of device to open
1877 *
1878 * Opens tty exclusively for kernel. Performs the driver lookup,
1879 * makes sure it's not already opened and performs the first-time
1880 * tty initialization.
1881 *
1882 * Returns the locked initialized &tty_struct
1883 *
1884 * Claims the global tty_mutex to serialize:
1885 * - concurrent first-time tty initialization
1886 * - concurrent tty driver removal w/ lookup
1887 * - concurrent tty removal from driver table
1888 */
1889struct tty_struct *tty_kopen(dev_t device)
1890{
1891 struct tty_struct *tty;
1892 struct tty_driver *driver;
1893 int index = -1;
1894
1895 mutex_lock(&tty_mutex);
1896 driver = tty_lookup_driver(device, NULL, &index);
1897 if (IS_ERR(driver)) {
1898 mutex_unlock(&tty_mutex);
1899 return ERR_CAST(driver);
1900 }
1901
1902 /* check whether we're reopening an existing tty */
1903 tty = tty_driver_lookup_tty(driver, NULL, index);
1904 if (IS_ERR(tty))
1905 goto out;
1906
1907 if (tty) {
1908 /* drop kref from tty_driver_lookup_tty() */
1909 tty_kref_put(tty);
1910 tty = ERR_PTR(-EBUSY);
1911 } else { /* tty_init_dev returns tty with the tty_lock held */
1912 tty = tty_init_dev(driver, index);
1913 if (IS_ERR(tty))
1914 goto out;
1915 tty_port_set_kopened(tty->port, 1);
1916 }
1917out:
1918 mutex_unlock(&tty_mutex);
1919 tty_driver_kref_put(driver);
1920 return tty;
1921}
1922EXPORT_SYMBOL_GPL(tty_kopen);
1923
1924/**
1925 * tty_open_by_driver - open a tty device
1926 * @device: dev_t of device to open
1927 * @filp: file pointer to tty
1928 *
1929 * Performs the driver lookup, checks for a reopen, or otherwise
1930 * performs the first-time tty initialization.
1931 *
1932 * Returns the locked initialized or re-opened &tty_struct
1933 *
1934 * Claims the global tty_mutex to serialize:
1935 * - concurrent first-time tty initialization
1936 * - concurrent tty driver removal w/ lookup
1937 * - concurrent tty removal from driver table
1938 */
1939static struct tty_struct *tty_open_by_driver(dev_t device,
1940 struct file *filp)
1941{
1942 struct tty_struct *tty;
1943 struct tty_driver *driver = NULL;
1944 int index = -1;
1945 int retval;
1946
1947 mutex_lock(&tty_mutex);
1948 driver = tty_lookup_driver(device, filp, &index);
1949 if (IS_ERR(driver)) {
1950 mutex_unlock(&tty_mutex);
1951 return ERR_CAST(driver);
1952 }
1953
1954 /* check whether we're reopening an existing tty */
1955 tty = tty_driver_lookup_tty(driver, filp, index);
1956 if (IS_ERR(tty)) {
1957 mutex_unlock(&tty_mutex);
1958 goto out;
1959 }
1960
1961 if (tty) {
1962 if (tty_port_kopened(tty->port)) {
1963 tty_kref_put(tty);
1964 mutex_unlock(&tty_mutex);
1965 tty = ERR_PTR(-EBUSY);
1966 goto out;
1967 }
1968 mutex_unlock(&tty_mutex);
1969 retval = tty_lock_interruptible(tty);
1970 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1971 if (retval) {
1972 if (retval == -EINTR)
1973 retval = -ERESTARTSYS;
1974 tty = ERR_PTR(retval);
1975 goto out;
1976 }
1977 retval = tty_reopen(tty);
1978 if (retval < 0) {
1979 tty_unlock(tty);
1980 tty = ERR_PTR(retval);
1981 }
1982 } else { /* Returns with the tty_lock held for now */
1983 tty = tty_init_dev(driver, index);
1984 mutex_unlock(&tty_mutex);
1985 }
1986out:
1987 tty_driver_kref_put(driver);
1988 return tty;
1989}
1990
1991/**
1992 * tty_open - open a tty device
1993 * @inode: inode of device file
1994 * @filp: file pointer to tty
1995 *
1996 * tty_open and tty_release keep up the tty count that contains the
1997 * number of opens done on a tty. We cannot use the inode-count, as
1998 * different inodes might point to the same tty.
1999 *
2000 * Open-counting is needed for pty masters, as well as for keeping
2001 * track of serial lines: DTR is dropped when the last close happens.
2002 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2003 *
2004 * The termios state of a pty is reset on first open so that
2005 * settings don't persist across reuse.
2006 *
2007 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2008 * tty->count should protect the rest.
2009 * ->siglock protects ->signal/->sighand
2010 *
2011 * Note: the tty_unlock/lock cases without a ref are only safe due to
2012 * tty_mutex
2013 */
2014
2015static int tty_open(struct inode *inode, struct file *filp)
2016{
2017 struct tty_struct *tty;
2018 int noctty, retval;
2019 dev_t device = inode->i_rdev;
2020 unsigned saved_flags = filp->f_flags;
2021
2022 nonseekable_open(inode, filp);
2023
2024retry_open:
2025 retval = tty_alloc_file(filp);
2026 if (retval)
2027 return -ENOMEM;
2028
2029 tty = tty_open_current_tty(device, filp);
2030 if (!tty)
2031 tty = tty_open_by_driver(device, filp);
2032
2033 if (IS_ERR(tty)) {
2034 tty_free_file(filp);
2035 retval = PTR_ERR(tty);
2036 if (retval != -EAGAIN || signal_pending(current))
2037 return retval;
2038 schedule();
2039 goto retry_open;
2040 }
2041
2042 tty_add_file(tty, filp);
2043
2044 check_tty_count(tty, __func__);
2045 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2046
2047 if (tty->ops->open)
2048 retval = tty->ops->open(tty, filp);
2049 else
2050 retval = -ENODEV;
2051 filp->f_flags = saved_flags;
2052
2053 if (retval) {
2054 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2055
2056 tty_unlock(tty); /* need to call tty_release without BTM */
2057 tty_release(inode, filp);
2058 if (retval != -ERESTARTSYS)
2059 return retval;
2060
2061 if (signal_pending(current))
2062 return retval;
2063
2064 schedule();
2065 /*
2066 * Need to reset f_op in case a hangup happened.
2067 */
2068 if (tty_hung_up_p(filp))
2069 filp->f_op = &tty_fops;
2070 goto retry_open;
2071 }
2072 clear_bit(TTY_HUPPED, &tty->flags);
2073
2074 noctty = (filp->f_flags & O_NOCTTY) ||
2075 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2076 device == MKDEV(TTYAUX_MAJOR, 1) ||
2077 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2078 tty->driver->subtype == PTY_TYPE_MASTER);
2079 if (!noctty)
2080 tty_open_proc_set_tty(filp, tty);
2081 tty_unlock(tty);
2082 return 0;
2083}
2084
2085
2086
2087/**
2088 * tty_poll - check tty status
2089 * @filp: file being polled
2090 * @wait: poll wait structures to update
2091 *
2092 * Call the line discipline polling method to obtain the poll
2093 * status of the device.
2094 *
2095 * Locking: locks called line discipline but ldisc poll method
2096 * may be re-entered freely by other callers.
2097 */
2098
2099static __poll_t tty_poll(struct file *filp, poll_table *wait)
2100{
2101 struct tty_struct *tty = file_tty(filp);
2102 struct tty_ldisc *ld;
2103 __poll_t ret = 0;
2104
2105 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2106 return 0;
2107
2108 ld = tty_ldisc_ref_wait(tty);
2109 if (!ld)
2110 return hung_up_tty_poll(filp, wait);
2111 if (ld->ops->poll)
2112 ret = ld->ops->poll(tty, filp, wait);
2113 tty_ldisc_deref(ld);
2114 return ret;
2115}
2116
2117static int __tty_fasync(int fd, struct file *filp, int on)
2118{
2119 struct tty_struct *tty = file_tty(filp);
2120 unsigned long flags;
2121 int retval = 0;
2122
2123 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2124 goto out;
2125
2126 retval = fasync_helper(fd, filp, on, &tty->fasync);
2127 if (retval <= 0)
2128 goto out;
2129
2130 if (on) {
2131 enum pid_type type;
2132 struct pid *pid;
2133
2134 spin_lock_irqsave(&tty->ctrl_lock, flags);
2135 if (tty->pgrp) {
2136 pid = tty->pgrp;
2137 type = PIDTYPE_PGID;
2138 } else {
2139 pid = task_pid(current);
2140 type = PIDTYPE_TGID;
2141 }
2142 get_pid(pid);
2143 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2144 __f_setown(filp, pid, type, 0);
2145 put_pid(pid);
2146 retval = 0;
2147 }
2148out:
2149 return retval;
2150}
2151
2152static int tty_fasync(int fd, struct file *filp, int on)
2153{
2154 struct tty_struct *tty = file_tty(filp);
2155 int retval = -ENOTTY;
2156
2157 tty_lock(tty);
2158 if (!tty_hung_up_p(filp))
2159 retval = __tty_fasync(fd, filp, on);
2160 tty_unlock(tty);
2161
2162 return retval;
2163}
2164
2165/**
2166 * tiocsti - fake input character
2167 * @tty: tty to fake input into
2168 * @p: pointer to character
2169 *
2170 * Fake input to a tty device. Does the necessary locking and
2171 * input management.
2172 *
2173 * FIXME: does not honour flow control ??
2174 *
2175 * Locking:
2176 * Called functions take tty_ldiscs_lock
2177 * current->signal->tty check is safe without locks
2178 *
2179 * FIXME: may race normal receive processing
2180 */
2181
2182static int tiocsti(struct tty_struct *tty, char __user *p)
2183{
2184 char ch, mbz = 0;
2185 struct tty_ldisc *ld;
2186
2187 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2188 return -EPERM;
2189 if (get_user(ch, p))
2190 return -EFAULT;
2191 tty_audit_tiocsti(tty, ch);
2192 ld = tty_ldisc_ref_wait(tty);
2193 if (!ld)
2194 return -EIO;
2195 if (ld->ops->receive_buf)
2196 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2197 tty_ldisc_deref(ld);
2198 return 0;
2199}
2200
2201/**
2202 * tiocgwinsz - implement window query ioctl
2203 * @tty; tty
2204 * @arg: user buffer for result
2205 *
2206 * Copies the kernel idea of the window size into the user buffer.
2207 *
2208 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2209 * is consistent.
2210 */
2211
2212static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2213{
2214 int err;
2215
2216 mutex_lock(&tty->winsize_mutex);
2217 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2218 mutex_unlock(&tty->winsize_mutex);
2219
2220 return err ? -EFAULT: 0;
2221}
2222
2223/**
2224 * tty_do_resize - resize event
2225 * @tty: tty being resized
2226 * @rows: rows (character)
2227 * @cols: cols (character)
2228 *
2229 * Update the termios variables and send the necessary signals to
2230 * peform a terminal resize correctly
2231 */
2232
2233int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2234{
2235 struct pid *pgrp;
2236
2237 /* Lock the tty */
2238 mutex_lock(&tty->winsize_mutex);
2239 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2240 goto done;
2241
2242 /* Signal the foreground process group */
2243 pgrp = tty_get_pgrp(tty);
2244 if (pgrp)
2245 kill_pgrp(pgrp, SIGWINCH, 1);
2246 put_pid(pgrp);
2247
2248 tty->winsize = *ws;
2249done:
2250 mutex_unlock(&tty->winsize_mutex);
2251 return 0;
2252}
2253EXPORT_SYMBOL(tty_do_resize);
2254
2255/**
2256 * tiocswinsz - implement window size set ioctl
2257 * @tty; tty side of tty
2258 * @arg: user buffer for result
2259 *
2260 * Copies the user idea of the window size to the kernel. Traditionally
2261 * this is just advisory information but for the Linux console it
2262 * actually has driver level meaning and triggers a VC resize.
2263 *
2264 * Locking:
2265 * Driver dependent. The default do_resize method takes the
2266 * tty termios mutex and ctrl_lock. The console takes its own lock
2267 * then calls into the default method.
2268 */
2269
2270static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2271{
2272 struct winsize tmp_ws;
2273 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2274 return -EFAULT;
2275
2276 if (tty->ops->resize)
2277 return tty->ops->resize(tty, &tmp_ws);
2278 else
2279 return tty_do_resize(tty, &tmp_ws);
2280}
2281
2282/**
2283 * tioccons - allow admin to move logical console
2284 * @file: the file to become console
2285 *
2286 * Allow the administrator to move the redirected console device
2287 *
2288 * Locking: uses redirect_lock to guard the redirect information
2289 */
2290
2291static int tioccons(struct file *file)
2292{
2293 if (!capable(CAP_SYS_ADMIN))
2294 return -EPERM;
2295 if (file->f_op->write == redirected_tty_write) {
2296 struct file *f;
2297 spin_lock(&redirect_lock);
2298 f = redirect;
2299 redirect = NULL;
2300 spin_unlock(&redirect_lock);
2301 if (f)
2302 fput(f);
2303 return 0;
2304 }
2305 spin_lock(&redirect_lock);
2306 if (redirect) {
2307 spin_unlock(&redirect_lock);
2308 return -EBUSY;
2309 }
2310 redirect = get_file(file);
2311 spin_unlock(&redirect_lock);
2312 return 0;
2313}
2314
2315/**
2316 * tiocsetd - set line discipline
2317 * @tty: tty device
2318 * @p: pointer to user data
2319 *
2320 * Set the line discipline according to user request.
2321 *
2322 * Locking: see tty_set_ldisc, this function is just a helper
2323 */
2324
2325static int tiocsetd(struct tty_struct *tty, int __user *p)
2326{
2327 int disc;
2328 int ret;
2329
2330 if (get_user(disc, p))
2331 return -EFAULT;
2332
2333 ret = tty_set_ldisc(tty, disc);
2334
2335 return ret;
2336}
2337
2338/**
2339 * tiocgetd - get line discipline
2340 * @tty: tty device
2341 * @p: pointer to user data
2342 *
2343 * Retrieves the line discipline id directly from the ldisc.
2344 *
2345 * Locking: waits for ldisc reference (in case the line discipline
2346 * is changing or the tty is being hungup)
2347 */
2348
2349static int tiocgetd(struct tty_struct *tty, int __user *p)
2350{
2351 struct tty_ldisc *ld;
2352 int ret;
2353
2354 ld = tty_ldisc_ref_wait(tty);
2355 if (!ld)
2356 return -EIO;
2357 ret = put_user(ld->ops->num, p);
2358 tty_ldisc_deref(ld);
2359 return ret;
2360}
2361
2362/**
2363 * send_break - performed time break
2364 * @tty: device to break on
2365 * @duration: timeout in mS
2366 *
2367 * Perform a timed break on hardware that lacks its own driver level
2368 * timed break functionality.
2369 *
2370 * Locking:
2371 * atomic_write_lock serializes
2372 *
2373 */
2374
2375static int send_break(struct tty_struct *tty, unsigned int duration)
2376{
2377 int retval;
2378
2379 if (tty->ops->break_ctl == NULL)
2380 return 0;
2381
2382 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2383 retval = tty->ops->break_ctl(tty, duration);
2384 else {
2385 /* Do the work ourselves */
2386 if (tty_write_lock(tty, 0) < 0)
2387 return -EINTR;
2388 retval = tty->ops->break_ctl(tty, -1);
2389 if (retval)
2390 goto out;
2391 if (!signal_pending(current))
2392 msleep_interruptible(duration);
2393 retval = tty->ops->break_ctl(tty, 0);
2394out:
2395 tty_write_unlock(tty);
2396 if (signal_pending(current))
2397 retval = -EINTR;
2398 }
2399 return retval;
2400}
2401
2402/**
2403 * tty_tiocmget - get modem status
2404 * @tty: tty device
2405 * @file: user file pointer
2406 * @p: pointer to result
2407 *
2408 * Obtain the modem status bits from the tty driver if the feature
2409 * is supported. Return -EINVAL if it is not available.
2410 *
2411 * Locking: none (up to the driver)
2412 */
2413
2414static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2415{
2416 int retval = -EINVAL;
2417
2418 if (tty->ops->tiocmget) {
2419 retval = tty->ops->tiocmget(tty);
2420
2421 if (retval >= 0)
2422 retval = put_user(retval, p);
2423 }
2424 return retval;
2425}
2426
2427/**
2428 * tty_tiocmset - set modem status
2429 * @tty: tty device
2430 * @cmd: command - clear bits, set bits or set all
2431 * @p: pointer to desired bits
2432 *
2433 * Set the modem status bits from the tty driver if the feature
2434 * is supported. Return -EINVAL if it is not available.
2435 *
2436 * Locking: none (up to the driver)
2437 */
2438
2439static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2440 unsigned __user *p)
2441{
2442 int retval;
2443 unsigned int set, clear, val;
2444
2445 if (tty->ops->tiocmset == NULL)
2446 return -EINVAL;
2447
2448 retval = get_user(val, p);
2449 if (retval)
2450 return retval;
2451 set = clear = 0;
2452 switch (cmd) {
2453 case TIOCMBIS:
2454 set = val;
2455 break;
2456 case TIOCMBIC:
2457 clear = val;
2458 break;
2459 case TIOCMSET:
2460 set = val;
2461 clear = ~val;
2462 break;
2463 }
2464 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2465 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2466 return tty->ops->tiocmset(tty, set, clear);
2467}
2468
2469static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2470{
2471 int retval = -EINVAL;
2472 struct serial_icounter_struct icount;
2473 memset(&icount, 0, sizeof(icount));
2474 if (tty->ops->get_icount)
2475 retval = tty->ops->get_icount(tty, &icount);
2476 if (retval != 0)
2477 return retval;
2478 if (copy_to_user(arg, &icount, sizeof(icount)))
2479 return -EFAULT;
2480 return 0;
2481}
2482
2483static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2484{
2485 static DEFINE_RATELIMIT_STATE(depr_flags,
2486 DEFAULT_RATELIMIT_INTERVAL,
2487 DEFAULT_RATELIMIT_BURST);
2488 char comm[TASK_COMM_LEN];
2489 struct serial_struct v;
2490 int flags;
2491
2492 if (copy_from_user(&v, ss, sizeof(*ss)))
2493 return -EFAULT;
2494
2495 flags = v.flags & ASYNC_DEPRECATED;
2496
2497 if (flags && __ratelimit(&depr_flags))
2498 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2499 __func__, get_task_comm(comm, current), flags);
2500 if (!tty->ops->set_serial)
2501 return -ENOTTY;
2502 return tty->ops->set_serial(tty, &v);
2503}
2504
2505static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2506{
2507 struct serial_struct v;
2508 int err;
2509
2510 memset(&v, 0, sizeof(v));
2511 if (!tty->ops->get_serial)
2512 return -ENOTTY;
2513 err = tty->ops->get_serial(tty, &v);
2514 if (!err && copy_to_user(ss, &v, sizeof(v)))
2515 err = -EFAULT;
2516 return err;
2517}
2518
2519/*
2520 * if pty, return the slave side (real_tty)
2521 * otherwise, return self
2522 */
2523static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2524{
2525 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2526 tty->driver->subtype == PTY_TYPE_MASTER)
2527 tty = tty->link;
2528 return tty;
2529}
2530
2531/*
2532 * Split this up, as gcc can choke on it otherwise..
2533 */
2534long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2535{
2536 struct tty_struct *tty = file_tty(file);
2537 struct tty_struct *real_tty;
2538 void __user *p = (void __user *)arg;
2539 int retval;
2540 struct tty_ldisc *ld;
2541
2542 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2543 return -EINVAL;
2544
2545 real_tty = tty_pair_get_tty(tty);
2546
2547 /*
2548 * Factor out some common prep work
2549 */
2550 switch (cmd) {
2551 case TIOCSETD:
2552 case TIOCSBRK:
2553 case TIOCCBRK:
2554 case TCSBRK:
2555 case TCSBRKP:
2556 retval = tty_check_change(tty);
2557 if (retval)
2558 return retval;
2559 if (cmd != TIOCCBRK) {
2560 tty_wait_until_sent(tty, 0);
2561 if (signal_pending(current))
2562 return -EINTR;
2563 }
2564 break;
2565 }
2566
2567 /*
2568 * Now do the stuff.
2569 */
2570 switch (cmd) {
2571 case TIOCSTI:
2572 return tiocsti(tty, p);
2573 case TIOCGWINSZ:
2574 return tiocgwinsz(real_tty, p);
2575 case TIOCSWINSZ:
2576 return tiocswinsz(real_tty, p);
2577 case TIOCCONS:
2578 return real_tty != tty ? -EINVAL : tioccons(file);
2579 case TIOCEXCL:
2580 set_bit(TTY_EXCLUSIVE, &tty->flags);
2581 return 0;
2582 case TIOCNXCL:
2583 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2584 return 0;
2585 case TIOCGEXCL:
2586 {
2587 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2588 return put_user(excl, (int __user *)p);
2589 }
2590 case TIOCGETD:
2591 return tiocgetd(tty, p);
2592 case TIOCSETD:
2593 return tiocsetd(tty, p);
2594 case TIOCVHANGUP:
2595 if (!capable(CAP_SYS_ADMIN))
2596 return -EPERM;
2597 tty_vhangup(tty);
2598 return 0;
2599 case TIOCGDEV:
2600 {
2601 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2602 return put_user(ret, (unsigned int __user *)p);
2603 }
2604 /*
2605 * Break handling
2606 */
2607 case TIOCSBRK: /* Turn break on, unconditionally */
2608 if (tty->ops->break_ctl)
2609 return tty->ops->break_ctl(tty, -1);
2610 return 0;
2611 case TIOCCBRK: /* Turn break off, unconditionally */
2612 if (tty->ops->break_ctl)
2613 return tty->ops->break_ctl(tty, 0);
2614 return 0;
2615 case TCSBRK: /* SVID version: non-zero arg --> no break */
2616 /* non-zero arg means wait for all output data
2617 * to be sent (performed above) but don't send break.
2618 * This is used by the tcdrain() termios function.
2619 */
2620 if (!arg)
2621 return send_break(tty, 250);
2622 return 0;
2623 case TCSBRKP: /* support for POSIX tcsendbreak() */
2624 return send_break(tty, arg ? arg*100 : 250);
2625
2626 case TIOCMGET:
2627 return tty_tiocmget(tty, p);
2628 case TIOCMSET:
2629 case TIOCMBIC:
2630 case TIOCMBIS:
2631 return tty_tiocmset(tty, cmd, p);
2632 case TIOCGICOUNT:
2633 return tty_tiocgicount(tty, p);
2634 case TCFLSH:
2635 switch (arg) {
2636 case TCIFLUSH:
2637 case TCIOFLUSH:
2638 /* flush tty buffer and allow ldisc to process ioctl */
2639 tty_buffer_flush(tty, NULL);
2640 break;
2641 }
2642 break;
2643 case TIOCSSERIAL:
2644 return tty_tiocsserial(tty, p);
2645 case TIOCGSERIAL:
2646 return tty_tiocgserial(tty, p);
2647 case TIOCGPTPEER:
2648 /* Special because the struct file is needed */
2649 return ptm_open_peer(file, tty, (int)arg);
2650 default:
2651 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2652 if (retval != -ENOIOCTLCMD)
2653 return retval;
2654 }
2655 if (tty->ops->ioctl) {
2656 retval = tty->ops->ioctl(tty, cmd, arg);
2657 if (retval != -ENOIOCTLCMD)
2658 return retval;
2659 }
2660 ld = tty_ldisc_ref_wait(tty);
2661 if (!ld)
2662 return hung_up_tty_ioctl(file, cmd, arg);
2663 retval = -EINVAL;
2664 if (ld->ops->ioctl) {
2665 retval = ld->ops->ioctl(tty, file, cmd, arg);
2666 if (retval == -ENOIOCTLCMD)
2667 retval = -ENOTTY;
2668 }
2669 tty_ldisc_deref(ld);
2670 return retval;
2671}
2672
2673#ifdef CONFIG_COMPAT
2674
2675struct serial_struct32 {
2676 compat_int_t type;
2677 compat_int_t line;
2678 compat_uint_t port;
2679 compat_int_t irq;
2680 compat_int_t flags;
2681 compat_int_t xmit_fifo_size;
2682 compat_int_t custom_divisor;
2683 compat_int_t baud_base;
2684 unsigned short close_delay;
2685 char io_type;
2686 char reserved_char;
2687 compat_int_t hub6;
2688 unsigned short closing_wait; /* time to wait before closing */
2689 unsigned short closing_wait2; /* no longer used... */
2690 compat_uint_t iomem_base;
2691 unsigned short iomem_reg_shift;
2692 unsigned int port_high;
2693 /* compat_ulong_t iomap_base FIXME */
2694 compat_int_t reserved;
2695};
2696
2697static int compat_tty_tiocsserial(struct tty_struct *tty,
2698 struct serial_struct32 __user *ss)
2699{
2700 static DEFINE_RATELIMIT_STATE(depr_flags,
2701 DEFAULT_RATELIMIT_INTERVAL,
2702 DEFAULT_RATELIMIT_BURST);
2703 char comm[TASK_COMM_LEN];
2704 struct serial_struct32 v32;
2705 struct serial_struct v;
2706 int flags;
2707
2708 if (copy_from_user(&v32, ss, sizeof(*ss)))
2709 return -EFAULT;
2710
2711 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2712 v.iomem_base = compat_ptr(v32.iomem_base);
2713 v.iomem_reg_shift = v32.iomem_reg_shift;
2714 v.port_high = v32.port_high;
2715 v.iomap_base = 0;
2716
2717 flags = v.flags & ASYNC_DEPRECATED;
2718
2719 if (flags && __ratelimit(&depr_flags))
2720 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2721 __func__, get_task_comm(comm, current), flags);
2722 if (!tty->ops->set_serial)
2723 return -ENOTTY;
2724 return tty->ops->set_serial(tty, &v);
2725}
2726
2727static int compat_tty_tiocgserial(struct tty_struct *tty,
2728 struct serial_struct32 __user *ss)
2729{
2730 struct serial_struct32 v32;
2731 struct serial_struct v;
2732 int err;
2733
2734 memset(&v, 0, sizeof(v));
2735 memset(&v32, 0, sizeof(v32));
2736
2737 if (!tty->ops->get_serial)
2738 return -ENOTTY;
2739 err = tty->ops->get_serial(tty, &v);
2740 if (!err) {
2741 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2742 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2743 0xfffffff : ptr_to_compat(v.iomem_base);
2744 v32.iomem_reg_shift = v.iomem_reg_shift;
2745 v32.port_high = v.port_high;
2746 if (copy_to_user(ss, &v32, sizeof(v32)))
2747 err = -EFAULT;
2748 }
2749 return err;
2750}
2751static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2752 unsigned long arg)
2753{
2754 struct tty_struct *tty = file_tty(file);
2755 struct tty_ldisc *ld;
2756 int retval = -ENOIOCTLCMD;
2757
2758 switch (cmd) {
2759 case TIOCOUTQ:
2760 case TIOCSTI:
2761 case TIOCGWINSZ:
2762 case TIOCSWINSZ:
2763 case TIOCGEXCL:
2764 case TIOCGETD:
2765 case TIOCSETD:
2766 case TIOCGDEV:
2767 case TIOCMGET:
2768 case TIOCMSET:
2769 case TIOCMBIC:
2770 case TIOCMBIS:
2771 case TIOCGICOUNT:
2772 case TIOCGPGRP:
2773 case TIOCSPGRP:
2774 case TIOCGSID:
2775 case TIOCSERGETLSR:
2776 case TIOCGRS485:
2777 case TIOCSRS485:
2778#ifdef TIOCGETP
2779 case TIOCGETP:
2780 case TIOCSETP:
2781 case TIOCSETN:
2782#endif
2783#ifdef TIOCGETC
2784 case TIOCGETC:
2785 case TIOCSETC:
2786#endif
2787#ifdef TIOCGLTC
2788 case TIOCGLTC:
2789 case TIOCSLTC:
2790#endif
2791 case TCSETSF:
2792 case TCSETSW:
2793 case TCSETS:
2794 case TCGETS:
2795#ifdef TCGETS2
2796 case TCGETS2:
2797 case TCSETSF2:
2798 case TCSETSW2:
2799 case TCSETS2:
2800#endif
2801 case TCGETA:
2802 case TCSETAF:
2803 case TCSETAW:
2804 case TCSETA:
2805 case TIOCGLCKTRMIOS:
2806 case TIOCSLCKTRMIOS:
2807#ifdef TCGETX
2808 case TCGETX:
2809 case TCSETX:
2810 case TCSETXW:
2811 case TCSETXF:
2812#endif
2813 case TIOCGSOFTCAR:
2814 case TIOCSSOFTCAR:
2815
2816 case PPPIOCGCHAN:
2817 case PPPIOCGUNIT:
2818 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2819 case TIOCCONS:
2820 case TIOCEXCL:
2821 case TIOCNXCL:
2822 case TIOCVHANGUP:
2823 case TIOCSBRK:
2824 case TIOCCBRK:
2825 case TCSBRK:
2826 case TCSBRKP:
2827 case TCFLSH:
2828 case TIOCGPTPEER:
2829 case TIOCNOTTY:
2830 case TIOCSCTTY:
2831 case TCXONC:
2832 case TIOCMIWAIT:
2833 case TIOCSERCONFIG:
2834 return tty_ioctl(file, cmd, arg);
2835 }
2836
2837 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2838 return -EINVAL;
2839
2840 switch (cmd) {
2841 case TIOCSSERIAL:
2842 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2843 case TIOCGSERIAL:
2844 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2845 }
2846 if (tty->ops->compat_ioctl) {
2847 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2848 if (retval != -ENOIOCTLCMD)
2849 return retval;
2850 }
2851
2852 ld = tty_ldisc_ref_wait(tty);
2853 if (!ld)
2854 return hung_up_tty_compat_ioctl(file, cmd, arg);
2855 if (ld->ops->compat_ioctl)
2856 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2857 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2858 retval = ld->ops->ioctl(tty, file,
2859 (unsigned long)compat_ptr(cmd), arg);
2860 tty_ldisc_deref(ld);
2861
2862 return retval;
2863}
2864#endif
2865
2866static int this_tty(const void *t, struct file *file, unsigned fd)
2867{
2868 if (likely(file->f_op->read != tty_read))
2869 return 0;
2870 return file_tty(file) != t ? 0 : fd + 1;
2871}
2872
2873/*
2874 * This implements the "Secure Attention Key" --- the idea is to
2875 * prevent trojan horses by killing all processes associated with this
2876 * tty when the user hits the "Secure Attention Key". Required for
2877 * super-paranoid applications --- see the Orange Book for more details.
2878 *
2879 * This code could be nicer; ideally it should send a HUP, wait a few
2880 * seconds, then send a INT, and then a KILL signal. But you then
2881 * have to coordinate with the init process, since all processes associated
2882 * with the current tty must be dead before the new getty is allowed
2883 * to spawn.
2884 *
2885 * Now, if it would be correct ;-/ The current code has a nasty hole -
2886 * it doesn't catch files in flight. We may send the descriptor to ourselves
2887 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2888 *
2889 * Nasty bug: do_SAK is being called in interrupt context. This can
2890 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2891 */
2892void __do_SAK(struct tty_struct *tty)
2893{
2894#ifdef TTY_SOFT_SAK
2895 tty_hangup(tty);
2896#else
2897 struct task_struct *g, *p;
2898 struct pid *session;
2899 int i;
2900
2901 if (!tty)
2902 return;
2903 session = tty->session;
2904
2905 tty_ldisc_flush(tty);
2906
2907 tty_driver_flush_buffer(tty);
2908
2909 read_lock(&tasklist_lock);
2910 /* Kill the entire session */
2911 do_each_pid_task(session, PIDTYPE_SID, p) {
2912 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2913 task_pid_nr(p), p->comm);
2914 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2915 } while_each_pid_task(session, PIDTYPE_SID, p);
2916
2917 /* Now kill any processes that happen to have the tty open */
2918 do_each_thread(g, p) {
2919 if (p->signal->tty == tty) {
2920 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2921 task_pid_nr(p), p->comm);
2922 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2923 continue;
2924 }
2925 task_lock(p);
2926 i = iterate_fd(p->files, 0, this_tty, tty);
2927 if (i != 0) {
2928 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2929 task_pid_nr(p), p->comm, i - 1);
2930 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2931 }
2932 task_unlock(p);
2933 } while_each_thread(g, p);
2934 read_unlock(&tasklist_lock);
2935#endif
2936}
2937
2938static void do_SAK_work(struct work_struct *work)
2939{
2940 struct tty_struct *tty =
2941 container_of(work, struct tty_struct, SAK_work);
2942 __do_SAK(tty);
2943}
2944
2945/*
2946 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2947 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2948 * the values which we write to it will be identical to the values which it
2949 * already has. --akpm
2950 */
2951void do_SAK(struct tty_struct *tty)
2952{
2953 if (!tty)
2954 return;
2955 schedule_work(&tty->SAK_work);
2956}
2957
2958EXPORT_SYMBOL(do_SAK);
2959
2960/* Must put_device() after it's unused! */
2961static struct device *tty_get_device(struct tty_struct *tty)
2962{
2963 dev_t devt = tty_devnum(tty);
2964 return class_find_device_by_devt(tty_class, devt);
2965}
2966
2967
2968/**
2969 * alloc_tty_struct
2970 *
2971 * This subroutine allocates and initializes a tty structure.
2972 *
2973 * Locking: none - tty in question is not exposed at this point
2974 */
2975
2976struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2977{
2978 struct tty_struct *tty;
2979
2980 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2981 if (!tty)
2982 return NULL;
2983
2984 kref_init(&tty->kref);
2985 tty->magic = TTY_MAGIC;
2986 if (tty_ldisc_init(tty)) {
2987 kfree(tty);
2988 return NULL;
2989 }
2990 tty->session = NULL;
2991 tty->pgrp = NULL;
2992 mutex_init(&tty->legacy_mutex);
2993 mutex_init(&tty->throttle_mutex);
2994 init_rwsem(&tty->termios_rwsem);
2995 mutex_init(&tty->winsize_mutex);
2996 init_ldsem(&tty->ldisc_sem);
2997 init_waitqueue_head(&tty->write_wait);
2998 init_waitqueue_head(&tty->read_wait);
2999 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3000 mutex_init(&tty->atomic_write_lock);
3001 spin_lock_init(&tty->ctrl_lock);
3002 spin_lock_init(&tty->flow_lock);
3003 spin_lock_init(&tty->files_lock);
3004 INIT_LIST_HEAD(&tty->tty_files);
3005 INIT_WORK(&tty->SAK_work, do_SAK_work);
3006
3007 tty->driver = driver;
3008 tty->ops = driver->ops;
3009 tty->index = idx;
3010 tty_line_name(driver, idx, tty->name);
3011 tty->dev = tty_get_device(tty);
3012
3013 return tty;
3014}
3015
3016/**
3017 * tty_put_char - write one character to a tty
3018 * @tty: tty
3019 * @ch: character
3020 *
3021 * Write one byte to the tty using the provided put_char method
3022 * if present. Returns the number of characters successfully output.
3023 *
3024 * Note: the specific put_char operation in the driver layer may go
3025 * away soon. Don't call it directly, use this method
3026 */
3027
3028int tty_put_char(struct tty_struct *tty, unsigned char ch)
3029{
3030 if (tty->ops->put_char)
3031 return tty->ops->put_char(tty, ch);
3032 return tty->ops->write(tty, &ch, 1);
3033}
3034EXPORT_SYMBOL_GPL(tty_put_char);
3035
3036struct class *tty_class;
3037
3038static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3039 unsigned int index, unsigned int count)
3040{
3041 int err;
3042
3043 /* init here, since reused cdevs cause crashes */
3044 driver->cdevs[index] = cdev_alloc();
3045 if (!driver->cdevs[index])
3046 return -ENOMEM;
3047 driver->cdevs[index]->ops = &tty_fops;
3048 driver->cdevs[index]->owner = driver->owner;
3049 err = cdev_add(driver->cdevs[index], dev, count);
3050 if (err)
3051 kobject_put(&driver->cdevs[index]->kobj);
3052 return err;
3053}
3054
3055/**
3056 * tty_register_device - register a tty device
3057 * @driver: the tty driver that describes the tty device
3058 * @index: the index in the tty driver for this tty device
3059 * @device: a struct device that is associated with this tty device.
3060 * This field is optional, if there is no known struct device
3061 * for this tty device it can be set to NULL safely.
3062 *
3063 * Returns a pointer to the struct device for this tty device
3064 * (or ERR_PTR(-EFOO) on error).
3065 *
3066 * This call is required to be made to register an individual tty device
3067 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3068 * that bit is not set, this function should not be called by a tty
3069 * driver.
3070 *
3071 * Locking: ??
3072 */
3073
3074struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3075 struct device *device)
3076{
3077 return tty_register_device_attr(driver, index, device, NULL, NULL);
3078}
3079EXPORT_SYMBOL(tty_register_device);
3080
3081static void tty_device_create_release(struct device *dev)
3082{
3083 dev_dbg(dev, "releasing...\n");
3084 kfree(dev);
3085}
3086
3087/**
3088 * tty_register_device_attr - register a tty device
3089 * @driver: the tty driver that describes the tty device
3090 * @index: the index in the tty driver for this tty device
3091 * @device: a struct device that is associated with this tty device.
3092 * This field is optional, if there is no known struct device
3093 * for this tty device it can be set to NULL safely.
3094 * @drvdata: Driver data to be set to device.
3095 * @attr_grp: Attribute group to be set on device.
3096 *
3097 * Returns a pointer to the struct device for this tty device
3098 * (or ERR_PTR(-EFOO) on error).
3099 *
3100 * This call is required to be made to register an individual tty device
3101 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3102 * that bit is not set, this function should not be called by a tty
3103 * driver.
3104 *
3105 * Locking: ??
3106 */
3107struct device *tty_register_device_attr(struct tty_driver *driver,
3108 unsigned index, struct device *device,
3109 void *drvdata,
3110 const struct attribute_group **attr_grp)
3111{
3112 char name[64];
3113 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3114 struct ktermios *tp;
3115 struct device *dev;
3116 int retval;
3117
3118 if (index >= driver->num) {
3119 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3120 driver->name, index);
3121 return ERR_PTR(-EINVAL);
3122 }
3123
3124 if (driver->type == TTY_DRIVER_TYPE_PTY)
3125 pty_line_name(driver, index, name);
3126 else
3127 tty_line_name(driver, index, name);
3128
3129 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3130 if (!dev)
3131 return ERR_PTR(-ENOMEM);
3132
3133 dev->devt = devt;
3134 dev->class = tty_class;
3135 dev->parent = device;
3136 dev->release = tty_device_create_release;
3137 dev_set_name(dev, "%s", name);
3138 dev->groups = attr_grp;
3139 dev_set_drvdata(dev, drvdata);
3140
3141 dev_set_uevent_suppress(dev, 1);
3142
3143 retval = device_register(dev);
3144 if (retval)
3145 goto err_put;
3146
3147 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3148 /*
3149 * Free any saved termios data so that the termios state is
3150 * reset when reusing a minor number.
3151 */
3152 tp = driver->termios[index];
3153 if (tp) {
3154 driver->termios[index] = NULL;
3155 kfree(tp);
3156 }
3157
3158 retval = tty_cdev_add(driver, devt, index, 1);
3159 if (retval)
3160 goto err_del;
3161 }
3162
3163 dev_set_uevent_suppress(dev, 0);
3164 kobject_uevent(&dev->kobj, KOBJ_ADD);
3165
3166 return dev;
3167
3168err_del:
3169 device_del(dev);
3170err_put:
3171 put_device(dev);
3172
3173 return ERR_PTR(retval);
3174}
3175EXPORT_SYMBOL_GPL(tty_register_device_attr);
3176
3177/**
3178 * tty_unregister_device - unregister a tty device
3179 * @driver: the tty driver that describes the tty device
3180 * @index: the index in the tty driver for this tty device
3181 *
3182 * If a tty device is registered with a call to tty_register_device() then
3183 * this function must be called when the tty device is gone.
3184 *
3185 * Locking: ??
3186 */
3187
3188void tty_unregister_device(struct tty_driver *driver, unsigned index)
3189{
3190 device_destroy(tty_class,
3191 MKDEV(driver->major, driver->minor_start) + index);
3192 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3193 cdev_del(driver->cdevs[index]);
3194 driver->cdevs[index] = NULL;
3195 }
3196}
3197EXPORT_SYMBOL(tty_unregister_device);
3198
3199/**
3200 * __tty_alloc_driver -- allocate tty driver
3201 * @lines: count of lines this driver can handle at most
3202 * @owner: module which is responsible for this driver
3203 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3204 *
3205 * This should not be called directly, some of the provided macros should be
3206 * used instead. Use IS_ERR and friends on @retval.
3207 */
3208struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3209 unsigned long flags)
3210{
3211 struct tty_driver *driver;
3212 unsigned int cdevs = 1;
3213 int err;
3214
3215 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3216 return ERR_PTR(-EINVAL);
3217
3218 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3219 if (!driver)
3220 return ERR_PTR(-ENOMEM);
3221
3222 kref_init(&driver->kref);
3223 driver->magic = TTY_DRIVER_MAGIC;
3224 driver->num = lines;
3225 driver->owner = owner;
3226 driver->flags = flags;
3227
3228 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3229 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3230 GFP_KERNEL);
3231 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3232 GFP_KERNEL);
3233 if (!driver->ttys || !driver->termios) {
3234 err = -ENOMEM;
3235 goto err_free_all;
3236 }
3237 }
3238
3239 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3240 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3241 GFP_KERNEL);
3242 if (!driver->ports) {
3243 err = -ENOMEM;
3244 goto err_free_all;
3245 }
3246 cdevs = lines;
3247 }
3248
3249 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3250 if (!driver->cdevs) {
3251 err = -ENOMEM;
3252 goto err_free_all;
3253 }
3254
3255 return driver;
3256err_free_all:
3257 kfree(driver->ports);
3258 kfree(driver->ttys);
3259 kfree(driver->termios);
3260 kfree(driver->cdevs);
3261 kfree(driver);
3262 return ERR_PTR(err);
3263}
3264EXPORT_SYMBOL(__tty_alloc_driver);
3265
3266static void destruct_tty_driver(struct kref *kref)
3267{
3268 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3269 int i;
3270 struct ktermios *tp;
3271
3272 if (driver->flags & TTY_DRIVER_INSTALLED) {
3273 for (i = 0; i < driver->num; i++) {
3274 tp = driver->termios[i];
3275 if (tp) {
3276 driver->termios[i] = NULL;
3277 kfree(tp);
3278 }
3279 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3280 tty_unregister_device(driver, i);
3281 }
3282 proc_tty_unregister_driver(driver);
3283 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3284 cdev_del(driver->cdevs[0]);
3285 }
3286 kfree(driver->cdevs);
3287 kfree(driver->ports);
3288 kfree(driver->termios);
3289 kfree(driver->ttys);
3290 kfree(driver);
3291}
3292
3293void tty_driver_kref_put(struct tty_driver *driver)
3294{
3295 kref_put(&driver->kref, destruct_tty_driver);
3296}
3297EXPORT_SYMBOL(tty_driver_kref_put);
3298
3299void tty_set_operations(struct tty_driver *driver,
3300 const struct tty_operations *op)
3301{
3302 driver->ops = op;
3303};
3304EXPORT_SYMBOL(tty_set_operations);
3305
3306void put_tty_driver(struct tty_driver *d)
3307{
3308 tty_driver_kref_put(d);
3309}
3310EXPORT_SYMBOL(put_tty_driver);
3311
3312/*
3313 * Called by a tty driver to register itself.
3314 */
3315int tty_register_driver(struct tty_driver *driver)
3316{
3317 int error;
3318 int i;
3319 dev_t dev;
3320 struct device *d;
3321
3322 if (!driver->major) {
3323 error = alloc_chrdev_region(&dev, driver->minor_start,
3324 driver->num, driver->name);
3325 if (!error) {
3326 driver->major = MAJOR(dev);
3327 driver->minor_start = MINOR(dev);
3328 }
3329 } else {
3330 dev = MKDEV(driver->major, driver->minor_start);
3331 error = register_chrdev_region(dev, driver->num, driver->name);
3332 }
3333 if (error < 0)
3334 goto err;
3335
3336 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3337 error = tty_cdev_add(driver, dev, 0, driver->num);
3338 if (error)
3339 goto err_unreg_char;
3340 }
3341
3342 mutex_lock(&tty_mutex);
3343 list_add(&driver->tty_drivers, &tty_drivers);
3344 mutex_unlock(&tty_mutex);
3345
3346 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3347 for (i = 0; i < driver->num; i++) {
3348 d = tty_register_device(driver, i, NULL);
3349 if (IS_ERR(d)) {
3350 error = PTR_ERR(d);
3351 goto err_unreg_devs;
3352 }
3353 }
3354 }
3355 proc_tty_register_driver(driver);
3356 driver->flags |= TTY_DRIVER_INSTALLED;
3357 return 0;
3358
3359err_unreg_devs:
3360 for (i--; i >= 0; i--)
3361 tty_unregister_device(driver, i);
3362
3363 mutex_lock(&tty_mutex);
3364 list_del(&driver->tty_drivers);
3365 mutex_unlock(&tty_mutex);
3366
3367err_unreg_char:
3368 unregister_chrdev_region(dev, driver->num);
3369err:
3370 return error;
3371}
3372EXPORT_SYMBOL(tty_register_driver);
3373
3374/*
3375 * Called by a tty driver to unregister itself.
3376 */
3377int tty_unregister_driver(struct tty_driver *driver)
3378{
3379#if 0
3380 /* FIXME */
3381 if (driver->refcount)
3382 return -EBUSY;
3383#endif
3384 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3385 driver->num);
3386 mutex_lock(&tty_mutex);
3387 list_del(&driver->tty_drivers);
3388 mutex_unlock(&tty_mutex);
3389 return 0;
3390}
3391
3392EXPORT_SYMBOL(tty_unregister_driver);
3393
3394dev_t tty_devnum(struct tty_struct *tty)
3395{
3396 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3397}
3398EXPORT_SYMBOL(tty_devnum);
3399
3400void tty_default_fops(struct file_operations *fops)
3401{
3402 *fops = tty_fops;
3403}
3404
3405static char *tty_devnode(struct device *dev, umode_t *mode)
3406{
3407 if (!mode)
3408 return NULL;
3409 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3410 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3411 *mode = 0666;
3412 return NULL;
3413}
3414
3415static int __init tty_class_init(void)
3416{
3417 tty_class = class_create(THIS_MODULE, "tty");
3418 if (IS_ERR(tty_class))
3419 return PTR_ERR(tty_class);
3420 tty_class->devnode = tty_devnode;
3421 return 0;
3422}
3423
3424postcore_initcall(tty_class_init);
3425
3426/* 3/2004 jmc: why do these devices exist? */
3427static struct cdev tty_cdev, console_cdev;
3428
3429static ssize_t show_cons_active(struct device *dev,
3430 struct device_attribute *attr, char *buf)
3431{
3432 struct console *cs[16];
3433 int i = 0;
3434 struct console *c;
3435 ssize_t count = 0;
3436
3437 console_lock();
3438 for_each_console(c) {
3439 if (!c->device)
3440 continue;
3441 if (!c->write)
3442 continue;
3443 if ((c->flags & CON_ENABLED) == 0)
3444 continue;
3445 cs[i++] = c;
3446 if (i >= ARRAY_SIZE(cs))
3447 break;
3448 }
3449 while (i--) {
3450 int index = cs[i]->index;
3451 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3452
3453 /* don't resolve tty0 as some programs depend on it */
3454 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3455 count += tty_line_name(drv, index, buf + count);
3456 else
3457 count += sprintf(buf + count, "%s%d",
3458 cs[i]->name, cs[i]->index);
3459
3460 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3461 }
3462 console_unlock();
3463
3464 return count;
3465}
3466static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3467
3468static struct attribute *cons_dev_attrs[] = {
3469 &dev_attr_active.attr,
3470 NULL
3471};
3472
3473ATTRIBUTE_GROUPS(cons_dev);
3474
3475static struct device *consdev;
3476
3477void console_sysfs_notify(void)
3478{
3479 if (consdev)
3480 sysfs_notify(&consdev->kobj, NULL, "active");
3481}
3482
3483/*
3484 * Ok, now we can initialize the rest of the tty devices and can count
3485 * on memory allocations, interrupts etc..
3486 */
3487int __init tty_init(void)
3488{
3489 tty_sysctl_init();
3490 cdev_init(&tty_cdev, &tty_fops);
3491 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3492 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3493 panic("Couldn't register /dev/tty driver\n");
3494 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3495
3496 cdev_init(&console_cdev, &console_fops);
3497 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3498 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3499 panic("Couldn't register /dev/console driver\n");
3500 consdev = device_create_with_groups(tty_class, NULL,
3501 MKDEV(TTYAUX_MAJOR, 1), NULL,
3502 cons_dev_groups, "console");
3503 if (IS_ERR(consdev))
3504 consdev = NULL;
3505
3506#ifdef CONFIG_VT
3507 vty_init(&console_fops);
3508#endif
3509 return 0;
3510}
3511
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 */
5
6/*
7 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
8 * or rs-channels. It also implements echoing, cooked mode etc.
9 *
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
11 *
12 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
13 * tty_struct and tty_queue structures. Previously there was an array
14 * of 256 tty_struct's which was statically allocated, and the
15 * tty_queue structures were allocated at boot time. Both are now
16 * dynamically allocated only when the tty is open.
17 *
18 * Also restructured routines so that there is more of a separation
19 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
20 * the low-level tty routines (serial.c, pty.c, console.c). This
21 * makes for cleaner and more compact code. -TYT, 9/17/92
22 *
23 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
24 * which can be dynamically activated and de-activated by the line
25 * discipline handling modules (like SLIP).
26 *
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
29 * -- TYT, 1/31/92
30 *
31 * Added functionality to the OPOST tty handling. No delays, but all
32 * other bits should be there.
33 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
34 *
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
37 *
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
40 *
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
43 *
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
46 *
47 * Move console and virtual terminal code to more appropriate files,
48 * implement CONFIG_VT and generalize console device interface.
49 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
50 *
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
53 *
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
56 *
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
59 *
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
62 *
63 * Move do_SAK() into process context. Less stack use in devfs functions.
64 * alloc_tty_struct() always uses kmalloc()
65 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
66 */
67
68#include <linux/types.h>
69#include <linux/major.h>
70#include <linux/errno.h>
71#include <linux/signal.h>
72#include <linux/fcntl.h>
73#include <linux/sched/signal.h>
74#include <linux/sched/task.h>
75#include <linux/interrupt.h>
76#include <linux/tty.h>
77#include <linux/tty_driver.h>
78#include <linux/tty_flip.h>
79#include <linux/devpts_fs.h>
80#include <linux/file.h>
81#include <linux/fdtable.h>
82#include <linux/console.h>
83#include <linux/timer.h>
84#include <linux/ctype.h>
85#include <linux/kd.h>
86#include <linux/mm.h>
87#include <linux/string.h>
88#include <linux/slab.h>
89#include <linux/poll.h>
90#include <linux/ppp-ioctl.h>
91#include <linux/proc_fs.h>
92#include <linux/init.h>
93#include <linux/module.h>
94#include <linux/device.h>
95#include <linux/wait.h>
96#include <linux/bitops.h>
97#include <linux/delay.h>
98#include <linux/seq_file.h>
99#include <linux/serial.h>
100#include <linux/ratelimit.h>
101#include <linux/compat.h>
102#include <linux/uaccess.h>
103#include <linux/termios_internal.h>
104
105#include <linux/kbd_kern.h>
106#include <linux/vt_kern.h>
107#include <linux/selection.h>
108
109#include <linux/kmod.h>
110#include <linux/nsproxy.h>
111#include "tty.h"
112
113#undef TTY_DEBUG_HANGUP
114#ifdef TTY_DEBUG_HANGUP
115# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
116#else
117# define tty_debug_hangup(tty, f, args...) do { } while (0)
118#endif
119
120#define TTY_PARANOIA_CHECK 1
121#define CHECK_TTY_COUNT 1
122
123struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
124 .c_iflag = ICRNL | IXON,
125 .c_oflag = OPOST | ONLCR,
126 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
127 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
128 ECHOCTL | ECHOKE | IEXTEN,
129 .c_cc = INIT_C_CC,
130 .c_ispeed = 38400,
131 .c_ospeed = 38400,
132 /* .c_line = N_TTY, */
133};
134EXPORT_SYMBOL(tty_std_termios);
135
136/* This list gets poked at by procfs and various bits of boot up code. This
137 * could do with some rationalisation such as pulling the tty proc function
138 * into this file.
139 */
140
141LIST_HEAD(tty_drivers); /* linked list of tty drivers */
142
143/* Mutex to protect creating and releasing a tty */
144DEFINE_MUTEX(tty_mutex);
145
146static ssize_t tty_read(struct kiocb *, struct iov_iter *);
147static ssize_t tty_write(struct kiocb *, struct iov_iter *);
148static __poll_t tty_poll(struct file *, poll_table *);
149static int tty_open(struct inode *, struct file *);
150#ifdef CONFIG_COMPAT
151static long tty_compat_ioctl(struct file *file, unsigned int cmd,
152 unsigned long arg);
153#else
154#define tty_compat_ioctl NULL
155#endif
156static int __tty_fasync(int fd, struct file *filp, int on);
157static int tty_fasync(int fd, struct file *filp, int on);
158static void release_tty(struct tty_struct *tty, int idx);
159
160/**
161 * free_tty_struct - free a disused tty
162 * @tty: tty struct to free
163 *
164 * Free the write buffers, tty queue and tty memory itself.
165 *
166 * Locking: none. Must be called after tty is definitely unused
167 */
168static void free_tty_struct(struct tty_struct *tty)
169{
170 tty_ldisc_deinit(tty);
171 put_device(tty->dev);
172 kvfree(tty->write_buf);
173 kfree(tty);
174}
175
176static inline struct tty_struct *file_tty(struct file *file)
177{
178 return ((struct tty_file_private *)file->private_data)->tty;
179}
180
181int tty_alloc_file(struct file *file)
182{
183 struct tty_file_private *priv;
184
185 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
186 if (!priv)
187 return -ENOMEM;
188
189 file->private_data = priv;
190
191 return 0;
192}
193
194/* Associate a new file with the tty structure */
195void tty_add_file(struct tty_struct *tty, struct file *file)
196{
197 struct tty_file_private *priv = file->private_data;
198
199 priv->tty = tty;
200 priv->file = file;
201
202 spin_lock(&tty->files_lock);
203 list_add(&priv->list, &tty->tty_files);
204 spin_unlock(&tty->files_lock);
205}
206
207/**
208 * tty_free_file - free file->private_data
209 * @file: to free private_data of
210 *
211 * This shall be used only for fail path handling when tty_add_file was not
212 * called yet.
213 */
214void tty_free_file(struct file *file)
215{
216 struct tty_file_private *priv = file->private_data;
217
218 file->private_data = NULL;
219 kfree(priv);
220}
221
222/* Delete file from its tty */
223static void tty_del_file(struct file *file)
224{
225 struct tty_file_private *priv = file->private_data;
226 struct tty_struct *tty = priv->tty;
227
228 spin_lock(&tty->files_lock);
229 list_del(&priv->list);
230 spin_unlock(&tty->files_lock);
231 tty_free_file(file);
232}
233
234/**
235 * tty_name - return tty naming
236 * @tty: tty structure
237 *
238 * Convert a tty structure into a name. The name reflects the kernel naming
239 * policy and if udev is in use may not reflect user space
240 *
241 * Locking: none
242 */
243const char *tty_name(const struct tty_struct *tty)
244{
245 if (!tty) /* Hmm. NULL pointer. That's fun. */
246 return "NULL tty";
247 return tty->name;
248}
249EXPORT_SYMBOL(tty_name);
250
251const char *tty_driver_name(const struct tty_struct *tty)
252{
253 if (!tty || !tty->driver)
254 return "";
255 return tty->driver->name;
256}
257
258static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
259 const char *routine)
260{
261#ifdef TTY_PARANOIA_CHECK
262 if (!tty) {
263 pr_warn("(%d:%d): %s: NULL tty\n",
264 imajor(inode), iminor(inode), routine);
265 return 1;
266 }
267#endif
268 return 0;
269}
270
271/* Caller must hold tty_lock */
272static int check_tty_count(struct tty_struct *tty, const char *routine)
273{
274#ifdef CHECK_TTY_COUNT
275 struct list_head *p;
276 int count = 0, kopen_count = 0;
277
278 spin_lock(&tty->files_lock);
279 list_for_each(p, &tty->tty_files) {
280 count++;
281 }
282 spin_unlock(&tty->files_lock);
283 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
284 tty->driver->subtype == PTY_TYPE_SLAVE &&
285 tty->link && tty->link->count)
286 count++;
287 if (tty_port_kopened(tty->port))
288 kopen_count++;
289 if (tty->count != (count + kopen_count)) {
290 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
291 routine, tty->count, count, kopen_count);
292 return (count + kopen_count);
293 }
294#endif
295 return 0;
296}
297
298/**
299 * get_tty_driver - find device of a tty
300 * @device: device identifier
301 * @index: returns the index of the tty
302 *
303 * This routine returns a tty driver structure, given a device number and also
304 * passes back the index number.
305 *
306 * Locking: caller must hold tty_mutex
307 */
308static struct tty_driver *get_tty_driver(dev_t device, int *index)
309{
310 struct tty_driver *p;
311
312 list_for_each_entry(p, &tty_drivers, tty_drivers) {
313 dev_t base = MKDEV(p->major, p->minor_start);
314
315 if (device < base || device >= base + p->num)
316 continue;
317 *index = device - base;
318 return tty_driver_kref_get(p);
319 }
320 return NULL;
321}
322
323/**
324 * tty_dev_name_to_number - return dev_t for device name
325 * @name: user space name of device under /dev
326 * @number: pointer to dev_t that this function will populate
327 *
328 * This function converts device names like ttyS0 or ttyUSB1 into dev_t like
329 * (4, 64) or (188, 1). If no corresponding driver is registered then the
330 * function returns -%ENODEV.
331 *
332 * Locking: this acquires tty_mutex to protect the tty_drivers list from
333 * being modified while we are traversing it, and makes sure to
334 * release it before exiting.
335 */
336int tty_dev_name_to_number(const char *name, dev_t *number)
337{
338 struct tty_driver *p;
339 int ret;
340 int index, prefix_length = 0;
341 const char *str;
342
343 for (str = name; *str && !isdigit(*str); str++)
344 ;
345
346 if (!*str)
347 return -EINVAL;
348
349 ret = kstrtoint(str, 10, &index);
350 if (ret)
351 return ret;
352
353 prefix_length = str - name;
354 mutex_lock(&tty_mutex);
355
356 list_for_each_entry(p, &tty_drivers, tty_drivers)
357 if (prefix_length == strlen(p->name) && strncmp(name,
358 p->name, prefix_length) == 0) {
359 if (index < p->num) {
360 *number = MKDEV(p->major, p->minor_start + index);
361 goto out;
362 }
363 }
364
365 /* if here then driver wasn't found */
366 ret = -ENODEV;
367out:
368 mutex_unlock(&tty_mutex);
369 return ret;
370}
371EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
372
373#ifdef CONFIG_CONSOLE_POLL
374
375/**
376 * tty_find_polling_driver - find device of a polled tty
377 * @name: name string to match
378 * @line: pointer to resulting tty line nr
379 *
380 * This routine returns a tty driver structure, given a name and the condition
381 * that the tty driver is capable of polled operation.
382 */
383struct tty_driver *tty_find_polling_driver(char *name, int *line)
384{
385 struct tty_driver *p, *res = NULL;
386 int tty_line = 0;
387 int len;
388 char *str, *stp;
389
390 for (str = name; *str; str++)
391 if ((*str >= '0' && *str <= '9') || *str == ',')
392 break;
393 if (!*str)
394 return NULL;
395
396 len = str - name;
397 tty_line = simple_strtoul(str, &str, 10);
398
399 mutex_lock(&tty_mutex);
400 /* Search through the tty devices to look for a match */
401 list_for_each_entry(p, &tty_drivers, tty_drivers) {
402 if (!len || strncmp(name, p->name, len) != 0)
403 continue;
404 stp = str;
405 if (*stp == ',')
406 stp++;
407 if (*stp == '\0')
408 stp = NULL;
409
410 if (tty_line >= 0 && tty_line < p->num && p->ops &&
411 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
412 res = tty_driver_kref_get(p);
413 *line = tty_line;
414 break;
415 }
416 }
417 mutex_unlock(&tty_mutex);
418
419 return res;
420}
421EXPORT_SYMBOL_GPL(tty_find_polling_driver);
422#endif
423
424static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
425{
426 return 0;
427}
428
429static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
430{
431 return -EIO;
432}
433
434/* No kernel lock held - none needed ;) */
435static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
436{
437 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
438}
439
440static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
441 unsigned long arg)
442{
443 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
444}
445
446static long hung_up_tty_compat_ioctl(struct file *file,
447 unsigned int cmd, unsigned long arg)
448{
449 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
450}
451
452static int hung_up_tty_fasync(int fd, struct file *file, int on)
453{
454 return -ENOTTY;
455}
456
457static void tty_show_fdinfo(struct seq_file *m, struct file *file)
458{
459 struct tty_struct *tty = file_tty(file);
460
461 if (tty && tty->ops && tty->ops->show_fdinfo)
462 tty->ops->show_fdinfo(tty, m);
463}
464
465static const struct file_operations tty_fops = {
466 .llseek = no_llseek,
467 .read_iter = tty_read,
468 .write_iter = tty_write,
469 .splice_read = generic_file_splice_read,
470 .splice_write = iter_file_splice_write,
471 .poll = tty_poll,
472 .unlocked_ioctl = tty_ioctl,
473 .compat_ioctl = tty_compat_ioctl,
474 .open = tty_open,
475 .release = tty_release,
476 .fasync = tty_fasync,
477 .show_fdinfo = tty_show_fdinfo,
478};
479
480static const struct file_operations console_fops = {
481 .llseek = no_llseek,
482 .read_iter = tty_read,
483 .write_iter = redirected_tty_write,
484 .splice_read = generic_file_splice_read,
485 .splice_write = iter_file_splice_write,
486 .poll = tty_poll,
487 .unlocked_ioctl = tty_ioctl,
488 .compat_ioctl = tty_compat_ioctl,
489 .open = tty_open,
490 .release = tty_release,
491 .fasync = tty_fasync,
492};
493
494static const struct file_operations hung_up_tty_fops = {
495 .llseek = no_llseek,
496 .read_iter = hung_up_tty_read,
497 .write_iter = hung_up_tty_write,
498 .poll = hung_up_tty_poll,
499 .unlocked_ioctl = hung_up_tty_ioctl,
500 .compat_ioctl = hung_up_tty_compat_ioctl,
501 .release = tty_release,
502 .fasync = hung_up_tty_fasync,
503};
504
505static DEFINE_SPINLOCK(redirect_lock);
506static struct file *redirect;
507
508/**
509 * tty_wakeup - request more data
510 * @tty: terminal
511 *
512 * Internal and external helper for wakeups of tty. This function informs the
513 * line discipline if present that the driver is ready to receive more output
514 * data.
515 */
516void tty_wakeup(struct tty_struct *tty)
517{
518 struct tty_ldisc *ld;
519
520 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
521 ld = tty_ldisc_ref(tty);
522 if (ld) {
523 if (ld->ops->write_wakeup)
524 ld->ops->write_wakeup(tty);
525 tty_ldisc_deref(ld);
526 }
527 }
528 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
529}
530EXPORT_SYMBOL_GPL(tty_wakeup);
531
532/**
533 * tty_release_redirect - Release a redirect on a pty if present
534 * @tty: tty device
535 *
536 * This is available to the pty code so if the master closes, if the slave is a
537 * redirect it can release the redirect.
538 */
539static struct file *tty_release_redirect(struct tty_struct *tty)
540{
541 struct file *f = NULL;
542
543 spin_lock(&redirect_lock);
544 if (redirect && file_tty(redirect) == tty) {
545 f = redirect;
546 redirect = NULL;
547 }
548 spin_unlock(&redirect_lock);
549
550 return f;
551}
552
553/**
554 * __tty_hangup - actual handler for hangup events
555 * @tty: tty device
556 * @exit_session: if non-zero, signal all foreground group processes
557 *
558 * This can be called by a "kworker" kernel thread. That is process synchronous
559 * but doesn't hold any locks, so we need to make sure we have the appropriate
560 * locks for what we're doing.
561 *
562 * The hangup event clears any pending redirections onto the hung up device. It
563 * ensures future writes will error and it does the needed line discipline
564 * hangup and signal delivery. The tty object itself remains intact.
565 *
566 * Locking:
567 * * BTM
568 *
569 * * redirect lock for undoing redirection
570 * * file list lock for manipulating list of ttys
571 * * tty_ldiscs_lock from called functions
572 * * termios_rwsem resetting termios data
573 * * tasklist_lock to walk task list for hangup event
574 *
575 * * ->siglock to protect ->signal/->sighand
576 *
577 */
578static void __tty_hangup(struct tty_struct *tty, int exit_session)
579{
580 struct file *cons_filp = NULL;
581 struct file *filp, *f;
582 struct tty_file_private *priv;
583 int closecount = 0, n;
584 int refs;
585
586 if (!tty)
587 return;
588
589 f = tty_release_redirect(tty);
590
591 tty_lock(tty);
592
593 if (test_bit(TTY_HUPPED, &tty->flags)) {
594 tty_unlock(tty);
595 return;
596 }
597
598 /*
599 * Some console devices aren't actually hung up for technical and
600 * historical reasons, which can lead to indefinite interruptible
601 * sleep in n_tty_read(). The following explicitly tells
602 * n_tty_read() to abort readers.
603 */
604 set_bit(TTY_HUPPING, &tty->flags);
605
606 /* inuse_filps is protected by the single tty lock,
607 * this really needs to change if we want to flush the
608 * workqueue with the lock held.
609 */
610 check_tty_count(tty, "tty_hangup");
611
612 spin_lock(&tty->files_lock);
613 /* This breaks for file handles being sent over AF_UNIX sockets ? */
614 list_for_each_entry(priv, &tty->tty_files, list) {
615 filp = priv->file;
616 if (filp->f_op->write_iter == redirected_tty_write)
617 cons_filp = filp;
618 if (filp->f_op->write_iter != tty_write)
619 continue;
620 closecount++;
621 __tty_fasync(-1, filp, 0); /* can't block */
622 filp->f_op = &hung_up_tty_fops;
623 }
624 spin_unlock(&tty->files_lock);
625
626 refs = tty_signal_session_leader(tty, exit_session);
627 /* Account for the p->signal references we killed */
628 while (refs--)
629 tty_kref_put(tty);
630
631 tty_ldisc_hangup(tty, cons_filp != NULL);
632
633 spin_lock_irq(&tty->ctrl.lock);
634 clear_bit(TTY_THROTTLED, &tty->flags);
635 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
636 put_pid(tty->ctrl.session);
637 put_pid(tty->ctrl.pgrp);
638 tty->ctrl.session = NULL;
639 tty->ctrl.pgrp = NULL;
640 tty->ctrl.pktstatus = 0;
641 spin_unlock_irq(&tty->ctrl.lock);
642
643 /*
644 * If one of the devices matches a console pointer, we
645 * cannot just call hangup() because that will cause
646 * tty->count and state->count to go out of sync.
647 * So we just call close() the right number of times.
648 */
649 if (cons_filp) {
650 if (tty->ops->close)
651 for (n = 0; n < closecount; n++)
652 tty->ops->close(tty, cons_filp);
653 } else if (tty->ops->hangup)
654 tty->ops->hangup(tty);
655 /*
656 * We don't want to have driver/ldisc interactions beyond the ones
657 * we did here. The driver layer expects no calls after ->hangup()
658 * from the ldisc side, which is now guaranteed.
659 */
660 set_bit(TTY_HUPPED, &tty->flags);
661 clear_bit(TTY_HUPPING, &tty->flags);
662 tty_unlock(tty);
663
664 if (f)
665 fput(f);
666}
667
668static void do_tty_hangup(struct work_struct *work)
669{
670 struct tty_struct *tty =
671 container_of(work, struct tty_struct, hangup_work);
672
673 __tty_hangup(tty, 0);
674}
675
676/**
677 * tty_hangup - trigger a hangup event
678 * @tty: tty to hangup
679 *
680 * A carrier loss (virtual or otherwise) has occurred on @tty. Schedule a
681 * hangup sequence to run after this event.
682 */
683void tty_hangup(struct tty_struct *tty)
684{
685 tty_debug_hangup(tty, "hangup\n");
686 schedule_work(&tty->hangup_work);
687}
688EXPORT_SYMBOL(tty_hangup);
689
690/**
691 * tty_vhangup - process vhangup
692 * @tty: tty to hangup
693 *
694 * The user has asked via system call for the terminal to be hung up. We do
695 * this synchronously so that when the syscall returns the process is complete.
696 * That guarantee is necessary for security reasons.
697 */
698void tty_vhangup(struct tty_struct *tty)
699{
700 tty_debug_hangup(tty, "vhangup\n");
701 __tty_hangup(tty, 0);
702}
703EXPORT_SYMBOL(tty_vhangup);
704
705
706/**
707 * tty_vhangup_self - process vhangup for own ctty
708 *
709 * Perform a vhangup on the current controlling tty
710 */
711void tty_vhangup_self(void)
712{
713 struct tty_struct *tty;
714
715 tty = get_current_tty();
716 if (tty) {
717 tty_vhangup(tty);
718 tty_kref_put(tty);
719 }
720}
721
722/**
723 * tty_vhangup_session - hangup session leader exit
724 * @tty: tty to hangup
725 *
726 * The session leader is exiting and hanging up its controlling terminal.
727 * Every process in the foreground process group is signalled %SIGHUP.
728 *
729 * We do this synchronously so that when the syscall returns the process is
730 * complete. That guarantee is necessary for security reasons.
731 */
732void tty_vhangup_session(struct tty_struct *tty)
733{
734 tty_debug_hangup(tty, "session hangup\n");
735 __tty_hangup(tty, 1);
736}
737
738/**
739 * tty_hung_up_p - was tty hung up
740 * @filp: file pointer of tty
741 *
742 * Return: true if the tty has been subject to a vhangup or a carrier loss
743 */
744int tty_hung_up_p(struct file *filp)
745{
746 return (filp && filp->f_op == &hung_up_tty_fops);
747}
748EXPORT_SYMBOL(tty_hung_up_p);
749
750void __stop_tty(struct tty_struct *tty)
751{
752 if (tty->flow.stopped)
753 return;
754 tty->flow.stopped = true;
755 if (tty->ops->stop)
756 tty->ops->stop(tty);
757}
758
759/**
760 * stop_tty - propagate flow control
761 * @tty: tty to stop
762 *
763 * Perform flow control to the driver. May be called on an already stopped
764 * device and will not re-call the &tty_driver->stop() method.
765 *
766 * This functionality is used by both the line disciplines for halting incoming
767 * flow and by the driver. It may therefore be called from any context, may be
768 * under the tty %atomic_write_lock but not always.
769 *
770 * Locking:
771 * flow.lock
772 */
773void stop_tty(struct tty_struct *tty)
774{
775 unsigned long flags;
776
777 spin_lock_irqsave(&tty->flow.lock, flags);
778 __stop_tty(tty);
779 spin_unlock_irqrestore(&tty->flow.lock, flags);
780}
781EXPORT_SYMBOL(stop_tty);
782
783void __start_tty(struct tty_struct *tty)
784{
785 if (!tty->flow.stopped || tty->flow.tco_stopped)
786 return;
787 tty->flow.stopped = false;
788 if (tty->ops->start)
789 tty->ops->start(tty);
790 tty_wakeup(tty);
791}
792
793/**
794 * start_tty - propagate flow control
795 * @tty: tty to start
796 *
797 * Start a tty that has been stopped if at all possible. If @tty was previously
798 * stopped and is now being started, the &tty_driver->start() method is invoked
799 * and the line discipline woken.
800 *
801 * Locking:
802 * flow.lock
803 */
804void start_tty(struct tty_struct *tty)
805{
806 unsigned long flags;
807
808 spin_lock_irqsave(&tty->flow.lock, flags);
809 __start_tty(tty);
810 spin_unlock_irqrestore(&tty->flow.lock, flags);
811}
812EXPORT_SYMBOL(start_tty);
813
814static void tty_update_time(struct timespec64 *time)
815{
816 time64_t sec = ktime_get_real_seconds();
817
818 /*
819 * We only care if the two values differ in anything other than the
820 * lower three bits (i.e every 8 seconds). If so, then we can update
821 * the time of the tty device, otherwise it could be construded as a
822 * security leak to let userspace know the exact timing of the tty.
823 */
824 if ((sec ^ time->tv_sec) & ~7)
825 time->tv_sec = sec;
826}
827
828/*
829 * Iterate on the ldisc ->read() function until we've gotten all
830 * the data the ldisc has for us.
831 *
832 * The "cookie" is something that the ldisc read function can fill
833 * in to let us know that there is more data to be had.
834 *
835 * We promise to continue to call the ldisc until it stops returning
836 * data or clears the cookie. The cookie may be something that the
837 * ldisc maintains state for and needs to free.
838 */
839static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
840 struct file *file, struct iov_iter *to)
841{
842 int retval = 0;
843 void *cookie = NULL;
844 unsigned long offset = 0;
845 char kernel_buf[64];
846 size_t count = iov_iter_count(to);
847
848 do {
849 int size, copied;
850
851 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
852 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
853 if (!size)
854 break;
855
856 if (size < 0) {
857 /* Did we have an earlier error (ie -EFAULT)? */
858 if (retval)
859 break;
860 retval = size;
861
862 /*
863 * -EOVERFLOW means we didn't have enough space
864 * for a whole packet, and we shouldn't return
865 * a partial result.
866 */
867 if (retval == -EOVERFLOW)
868 offset = 0;
869 break;
870 }
871
872 copied = copy_to_iter(kernel_buf, size, to);
873 offset += copied;
874 count -= copied;
875
876 /*
877 * If the user copy failed, we still need to do another ->read()
878 * call if we had a cookie to let the ldisc clear up.
879 *
880 * But make sure size is zeroed.
881 */
882 if (unlikely(copied != size)) {
883 count = 0;
884 retval = -EFAULT;
885 }
886 } while (cookie);
887
888 /* We always clear tty buffer in case they contained passwords */
889 memzero_explicit(kernel_buf, sizeof(kernel_buf));
890 return offset ? offset : retval;
891}
892
893
894/**
895 * tty_read - read method for tty device files
896 * @iocb: kernel I/O control block
897 * @to: destination for the data read
898 *
899 * Perform the read system call function on this terminal device. Checks
900 * for hung up devices before calling the line discipline method.
901 *
902 * Locking:
903 * Locks the line discipline internally while needed. Multiple read calls
904 * may be outstanding in parallel.
905 */
906static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
907{
908 int i;
909 struct file *file = iocb->ki_filp;
910 struct inode *inode = file_inode(file);
911 struct tty_struct *tty = file_tty(file);
912 struct tty_ldisc *ld;
913
914 if (tty_paranoia_check(tty, inode, "tty_read"))
915 return -EIO;
916 if (!tty || tty_io_error(tty))
917 return -EIO;
918
919 /* We want to wait for the line discipline to sort out in this
920 * situation.
921 */
922 ld = tty_ldisc_ref_wait(tty);
923 if (!ld)
924 return hung_up_tty_read(iocb, to);
925 i = -EIO;
926 if (ld->ops->read)
927 i = iterate_tty_read(ld, tty, file, to);
928 tty_ldisc_deref(ld);
929
930 if (i > 0)
931 tty_update_time(&inode->i_atime);
932
933 return i;
934}
935
936static void tty_write_unlock(struct tty_struct *tty)
937{
938 mutex_unlock(&tty->atomic_write_lock);
939 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
940}
941
942static int tty_write_lock(struct tty_struct *tty, int ndelay)
943{
944 if (!mutex_trylock(&tty->atomic_write_lock)) {
945 if (ndelay)
946 return -EAGAIN;
947 if (mutex_lock_interruptible(&tty->atomic_write_lock))
948 return -ERESTARTSYS;
949 }
950 return 0;
951}
952
953/*
954 * Split writes up in sane blocksizes to avoid
955 * denial-of-service type attacks
956 */
957static inline ssize_t do_tty_write(
958 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
959 struct tty_struct *tty,
960 struct file *file,
961 struct iov_iter *from)
962{
963 size_t count = iov_iter_count(from);
964 ssize_t ret, written = 0;
965 unsigned int chunk;
966
967 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
968 if (ret < 0)
969 return ret;
970
971 /*
972 * We chunk up writes into a temporary buffer. This
973 * simplifies low-level drivers immensely, since they
974 * don't have locking issues and user mode accesses.
975 *
976 * But if TTY_NO_WRITE_SPLIT is set, we should use a
977 * big chunk-size..
978 *
979 * The default chunk-size is 2kB, because the NTTY
980 * layer has problems with bigger chunks. It will
981 * claim to be able to handle more characters than
982 * it actually does.
983 */
984 chunk = 2048;
985 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
986 chunk = 65536;
987 if (count < chunk)
988 chunk = count;
989
990 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
991 if (tty->write_cnt < chunk) {
992 unsigned char *buf_chunk;
993
994 if (chunk < 1024)
995 chunk = 1024;
996
997 buf_chunk = kvmalloc(chunk, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
998 if (!buf_chunk) {
999 ret = -ENOMEM;
1000 goto out;
1001 }
1002 kvfree(tty->write_buf);
1003 tty->write_cnt = chunk;
1004 tty->write_buf = buf_chunk;
1005 }
1006
1007 /* Do the write .. */
1008 for (;;) {
1009 size_t size = count;
1010
1011 if (size > chunk)
1012 size = chunk;
1013
1014 ret = -EFAULT;
1015 if (copy_from_iter(tty->write_buf, size, from) != size)
1016 break;
1017
1018 ret = write(tty, file, tty->write_buf, size);
1019 if (ret <= 0)
1020 break;
1021
1022 written += ret;
1023 if (ret > size)
1024 break;
1025
1026 /* FIXME! Have Al check this! */
1027 if (ret != size)
1028 iov_iter_revert(from, size-ret);
1029
1030 count -= ret;
1031 if (!count)
1032 break;
1033 ret = -ERESTARTSYS;
1034 if (signal_pending(current))
1035 break;
1036 cond_resched();
1037 }
1038 if (written) {
1039 tty_update_time(&file_inode(file)->i_mtime);
1040 ret = written;
1041 }
1042out:
1043 tty_write_unlock(tty);
1044 return ret;
1045}
1046
1047/**
1048 * tty_write_message - write a message to a certain tty, not just the console.
1049 * @tty: the destination tty_struct
1050 * @msg: the message to write
1051 *
1052 * This is used for messages that need to be redirected to a specific tty. We
1053 * don't put it into the syslog queue right now maybe in the future if really
1054 * needed.
1055 *
1056 * We must still hold the BTM and test the CLOSING flag for the moment.
1057 */
1058void tty_write_message(struct tty_struct *tty, char *msg)
1059{
1060 if (tty) {
1061 mutex_lock(&tty->atomic_write_lock);
1062 tty_lock(tty);
1063 if (tty->ops->write && tty->count > 0)
1064 tty->ops->write(tty, msg, strlen(msg));
1065 tty_unlock(tty);
1066 tty_write_unlock(tty);
1067 }
1068}
1069
1070static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
1071{
1072 struct tty_struct *tty = file_tty(file);
1073 struct tty_ldisc *ld;
1074 ssize_t ret;
1075
1076 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1077 return -EIO;
1078 if (!tty || !tty->ops->write || tty_io_error(tty))
1079 return -EIO;
1080 /* Short term debug to catch buggy drivers */
1081 if (tty->ops->write_room == NULL)
1082 tty_err(tty, "missing write_room method\n");
1083 ld = tty_ldisc_ref_wait(tty);
1084 if (!ld)
1085 return hung_up_tty_write(iocb, from);
1086 if (!ld->ops->write)
1087 ret = -EIO;
1088 else
1089 ret = do_tty_write(ld->ops->write, tty, file, from);
1090 tty_ldisc_deref(ld);
1091 return ret;
1092}
1093
1094/**
1095 * tty_write - write method for tty device file
1096 * @iocb: kernel I/O control block
1097 * @from: iov_iter with data to write
1098 *
1099 * Write data to a tty device via the line discipline.
1100 *
1101 * Locking:
1102 * Locks the line discipline as required
1103 * Writes to the tty driver are serialized by the atomic_write_lock
1104 * and are then processed in chunks to the device. The line
1105 * discipline write method will not be invoked in parallel for
1106 * each device.
1107 */
1108static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1109{
1110 return file_tty_write(iocb->ki_filp, iocb, from);
1111}
1112
1113ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1114{
1115 struct file *p = NULL;
1116
1117 spin_lock(&redirect_lock);
1118 if (redirect)
1119 p = get_file(redirect);
1120 spin_unlock(&redirect_lock);
1121
1122 /*
1123 * We know the redirected tty is just another tty, we can
1124 * call file_tty_write() directly with that file pointer.
1125 */
1126 if (p) {
1127 ssize_t res;
1128
1129 res = file_tty_write(p, iocb, iter);
1130 fput(p);
1131 return res;
1132 }
1133 return tty_write(iocb, iter);
1134}
1135
1136/**
1137 * tty_send_xchar - send priority character
1138 * @tty: the tty to send to
1139 * @ch: xchar to send
1140 *
1141 * Send a high priority character to the tty even if stopped.
1142 *
1143 * Locking: none for xchar method, write ordering for write method.
1144 */
1145int tty_send_xchar(struct tty_struct *tty, char ch)
1146{
1147 bool was_stopped = tty->flow.stopped;
1148
1149 if (tty->ops->send_xchar) {
1150 down_read(&tty->termios_rwsem);
1151 tty->ops->send_xchar(tty, ch);
1152 up_read(&tty->termios_rwsem);
1153 return 0;
1154 }
1155
1156 if (tty_write_lock(tty, 0) < 0)
1157 return -ERESTARTSYS;
1158
1159 down_read(&tty->termios_rwsem);
1160 if (was_stopped)
1161 start_tty(tty);
1162 tty->ops->write(tty, &ch, 1);
1163 if (was_stopped)
1164 stop_tty(tty);
1165 up_read(&tty->termios_rwsem);
1166 tty_write_unlock(tty);
1167 return 0;
1168}
1169
1170/**
1171 * pty_line_name - generate name for a pty
1172 * @driver: the tty driver in use
1173 * @index: the minor number
1174 * @p: output buffer of at least 6 bytes
1175 *
1176 * Generate a name from a @driver reference and write it to the output buffer
1177 * @p.
1178 *
1179 * Locking: None
1180 */
1181static void pty_line_name(struct tty_driver *driver, int index, char *p)
1182{
1183 static const char ptychar[] = "pqrstuvwxyzabcde";
1184 int i = index + driver->name_base;
1185 /* ->name is initialized to "ttyp", but "tty" is expected */
1186 sprintf(p, "%s%c%x",
1187 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1188 ptychar[i >> 4 & 0xf], i & 0xf);
1189}
1190
1191/**
1192 * tty_line_name - generate name for a tty
1193 * @driver: the tty driver in use
1194 * @index: the minor number
1195 * @p: output buffer of at least 7 bytes
1196 *
1197 * Generate a name from a @driver reference and write it to the output buffer
1198 * @p.
1199 *
1200 * Locking: None
1201 */
1202static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1203{
1204 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1205 return sprintf(p, "%s", driver->name);
1206 else
1207 return sprintf(p, "%s%d", driver->name,
1208 index + driver->name_base);
1209}
1210
1211/**
1212 * tty_driver_lookup_tty() - find an existing tty, if any
1213 * @driver: the driver for the tty
1214 * @file: file object
1215 * @idx: the minor number
1216 *
1217 * Return: the tty, if found. If not found, return %NULL or ERR_PTR() if the
1218 * driver lookup() method returns an error.
1219 *
1220 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1221 */
1222static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1223 struct file *file, int idx)
1224{
1225 struct tty_struct *tty;
1226
1227 if (driver->ops->lookup)
1228 if (!file)
1229 tty = ERR_PTR(-EIO);
1230 else
1231 tty = driver->ops->lookup(driver, file, idx);
1232 else
1233 tty = driver->ttys[idx];
1234
1235 if (!IS_ERR(tty))
1236 tty_kref_get(tty);
1237 return tty;
1238}
1239
1240/**
1241 * tty_init_termios - helper for termios setup
1242 * @tty: the tty to set up
1243 *
1244 * Initialise the termios structure for this tty. This runs under the
1245 * %tty_mutex currently so we can be relaxed about ordering.
1246 */
1247void tty_init_termios(struct tty_struct *tty)
1248{
1249 struct ktermios *tp;
1250 int idx = tty->index;
1251
1252 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1253 tty->termios = tty->driver->init_termios;
1254 else {
1255 /* Check for lazy saved data */
1256 tp = tty->driver->termios[idx];
1257 if (tp != NULL) {
1258 tty->termios = *tp;
1259 tty->termios.c_line = tty->driver->init_termios.c_line;
1260 } else
1261 tty->termios = tty->driver->init_termios;
1262 }
1263 /* Compatibility until drivers always set this */
1264 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1265 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1266}
1267EXPORT_SYMBOL_GPL(tty_init_termios);
1268
1269/**
1270 * tty_standard_install - usual tty->ops->install
1271 * @driver: the driver for the tty
1272 * @tty: the tty
1273 *
1274 * If the @driver overrides @tty->ops->install, it still can call this function
1275 * to perform the standard install operations.
1276 */
1277int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1278{
1279 tty_init_termios(tty);
1280 tty_driver_kref_get(driver);
1281 tty->count++;
1282 driver->ttys[tty->index] = tty;
1283 return 0;
1284}
1285EXPORT_SYMBOL_GPL(tty_standard_install);
1286
1287/**
1288 * tty_driver_install_tty() - install a tty entry in the driver
1289 * @driver: the driver for the tty
1290 * @tty: the tty
1291 *
1292 * Install a tty object into the driver tables. The @tty->index field will be
1293 * set by the time this is called. This method is responsible for ensuring any
1294 * need additional structures are allocated and configured.
1295 *
1296 * Locking: tty_mutex for now
1297 */
1298static int tty_driver_install_tty(struct tty_driver *driver,
1299 struct tty_struct *tty)
1300{
1301 return driver->ops->install ? driver->ops->install(driver, tty) :
1302 tty_standard_install(driver, tty);
1303}
1304
1305/**
1306 * tty_driver_remove_tty() - remove a tty from the driver tables
1307 * @driver: the driver for the tty
1308 * @tty: tty to remove
1309 *
1310 * Remove a tty object from the driver tables. The tty->index field will be set
1311 * by the time this is called.
1312 *
1313 * Locking: tty_mutex for now
1314 */
1315static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1316{
1317 if (driver->ops->remove)
1318 driver->ops->remove(driver, tty);
1319 else
1320 driver->ttys[tty->index] = NULL;
1321}
1322
1323/**
1324 * tty_reopen() - fast re-open of an open tty
1325 * @tty: the tty to open
1326 *
1327 * Re-opens on master ptys are not allowed and return -%EIO.
1328 *
1329 * Locking: Caller must hold tty_lock
1330 * Return: 0 on success, -errno on error.
1331 */
1332static int tty_reopen(struct tty_struct *tty)
1333{
1334 struct tty_driver *driver = tty->driver;
1335 struct tty_ldisc *ld;
1336 int retval = 0;
1337
1338 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1339 driver->subtype == PTY_TYPE_MASTER)
1340 return -EIO;
1341
1342 if (!tty->count)
1343 return -EAGAIN;
1344
1345 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1346 return -EBUSY;
1347
1348 ld = tty_ldisc_ref_wait(tty);
1349 if (ld) {
1350 tty_ldisc_deref(ld);
1351 } else {
1352 retval = tty_ldisc_lock(tty, 5 * HZ);
1353 if (retval)
1354 return retval;
1355
1356 if (!tty->ldisc)
1357 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1358 tty_ldisc_unlock(tty);
1359 }
1360
1361 if (retval == 0)
1362 tty->count++;
1363
1364 return retval;
1365}
1366
1367/**
1368 * tty_init_dev - initialise a tty device
1369 * @driver: tty driver we are opening a device on
1370 * @idx: device index
1371 *
1372 * Prepare a tty device. This may not be a "new" clean device but could also be
1373 * an active device. The pty drivers require special handling because of this.
1374 *
1375 * Locking:
1376 * The function is called under the tty_mutex, which protects us from the
1377 * tty struct or driver itself going away.
1378 *
1379 * On exit the tty device has the line discipline attached and a reference
1380 * count of 1. If a pair was created for pty/tty use and the other was a pty
1381 * master then it too has a reference count of 1.
1382 *
1383 * WSH 06/09/97: Rewritten to remove races and properly clean up after a failed
1384 * open. The new code protects the open with a mutex, so it's really quite
1385 * straightforward. The mutex locking can probably be relaxed for the (most
1386 * common) case of reopening a tty.
1387 *
1388 * Return: new tty structure
1389 */
1390struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1391{
1392 struct tty_struct *tty;
1393 int retval;
1394
1395 /*
1396 * First time open is complex, especially for PTY devices.
1397 * This code guarantees that either everything succeeds and the
1398 * TTY is ready for operation, or else the table slots are vacated
1399 * and the allocated memory released. (Except that the termios
1400 * may be retained.)
1401 */
1402
1403 if (!try_module_get(driver->owner))
1404 return ERR_PTR(-ENODEV);
1405
1406 tty = alloc_tty_struct(driver, idx);
1407 if (!tty) {
1408 retval = -ENOMEM;
1409 goto err_module_put;
1410 }
1411
1412 tty_lock(tty);
1413 retval = tty_driver_install_tty(driver, tty);
1414 if (retval < 0)
1415 goto err_free_tty;
1416
1417 if (!tty->port)
1418 tty->port = driver->ports[idx];
1419
1420 if (WARN_RATELIMIT(!tty->port,
1421 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1422 __func__, tty->driver->name)) {
1423 retval = -EINVAL;
1424 goto err_release_lock;
1425 }
1426
1427 retval = tty_ldisc_lock(tty, 5 * HZ);
1428 if (retval)
1429 goto err_release_lock;
1430 tty->port->itty = tty;
1431
1432 /*
1433 * Structures all installed ... call the ldisc open routines.
1434 * If we fail here just call release_tty to clean up. No need
1435 * to decrement the use counts, as release_tty doesn't care.
1436 */
1437 retval = tty_ldisc_setup(tty, tty->link);
1438 if (retval)
1439 goto err_release_tty;
1440 tty_ldisc_unlock(tty);
1441 /* Return the tty locked so that it cannot vanish under the caller */
1442 return tty;
1443
1444err_free_tty:
1445 tty_unlock(tty);
1446 free_tty_struct(tty);
1447err_module_put:
1448 module_put(driver->owner);
1449 return ERR_PTR(retval);
1450
1451 /* call the tty release_tty routine to clean out this slot */
1452err_release_tty:
1453 tty_ldisc_unlock(tty);
1454 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1455 retval, idx);
1456err_release_lock:
1457 tty_unlock(tty);
1458 release_tty(tty, idx);
1459 return ERR_PTR(retval);
1460}
1461
1462/**
1463 * tty_save_termios() - save tty termios data in driver table
1464 * @tty: tty whose termios data to save
1465 *
1466 * Locking: Caller guarantees serialisation with tty_init_termios().
1467 */
1468void tty_save_termios(struct tty_struct *tty)
1469{
1470 struct ktermios *tp;
1471 int idx = tty->index;
1472
1473 /* If the port is going to reset then it has no termios to save */
1474 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1475 return;
1476
1477 /* Stash the termios data */
1478 tp = tty->driver->termios[idx];
1479 if (tp == NULL) {
1480 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1481 if (tp == NULL)
1482 return;
1483 tty->driver->termios[idx] = tp;
1484 }
1485 *tp = tty->termios;
1486}
1487EXPORT_SYMBOL_GPL(tty_save_termios);
1488
1489/**
1490 * tty_flush_works - flush all works of a tty/pty pair
1491 * @tty: tty device to flush works for (or either end of a pty pair)
1492 *
1493 * Sync flush all works belonging to @tty (and the 'other' tty).
1494 */
1495static void tty_flush_works(struct tty_struct *tty)
1496{
1497 flush_work(&tty->SAK_work);
1498 flush_work(&tty->hangup_work);
1499 if (tty->link) {
1500 flush_work(&tty->link->SAK_work);
1501 flush_work(&tty->link->hangup_work);
1502 }
1503}
1504
1505/**
1506 * release_one_tty - release tty structure memory
1507 * @work: work of tty we are obliterating
1508 *
1509 * Releases memory associated with a tty structure, and clears out the
1510 * driver table slots. This function is called when a device is no longer
1511 * in use. It also gets called when setup of a device fails.
1512 *
1513 * Locking:
1514 * takes the file list lock internally when working on the list of ttys
1515 * that the driver keeps.
1516 *
1517 * This method gets called from a work queue so that the driver private
1518 * cleanup ops can sleep (needed for USB at least)
1519 */
1520static void release_one_tty(struct work_struct *work)
1521{
1522 struct tty_struct *tty =
1523 container_of(work, struct tty_struct, hangup_work);
1524 struct tty_driver *driver = tty->driver;
1525 struct module *owner = driver->owner;
1526
1527 if (tty->ops->cleanup)
1528 tty->ops->cleanup(tty);
1529
1530 tty_driver_kref_put(driver);
1531 module_put(owner);
1532
1533 spin_lock(&tty->files_lock);
1534 list_del_init(&tty->tty_files);
1535 spin_unlock(&tty->files_lock);
1536
1537 put_pid(tty->ctrl.pgrp);
1538 put_pid(tty->ctrl.session);
1539 free_tty_struct(tty);
1540}
1541
1542static void queue_release_one_tty(struct kref *kref)
1543{
1544 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1545
1546 /* The hangup queue is now free so we can reuse it rather than
1547 * waste a chunk of memory for each port.
1548 */
1549 INIT_WORK(&tty->hangup_work, release_one_tty);
1550 schedule_work(&tty->hangup_work);
1551}
1552
1553/**
1554 * tty_kref_put - release a tty kref
1555 * @tty: tty device
1556 *
1557 * Release a reference to the @tty device and if need be let the kref layer
1558 * destruct the object for us.
1559 */
1560void tty_kref_put(struct tty_struct *tty)
1561{
1562 if (tty)
1563 kref_put(&tty->kref, queue_release_one_tty);
1564}
1565EXPORT_SYMBOL(tty_kref_put);
1566
1567/**
1568 * release_tty - release tty structure memory
1569 * @tty: tty device release
1570 * @idx: index of the tty device release
1571 *
1572 * Release both @tty and a possible linked partner (think pty pair),
1573 * and decrement the refcount of the backing module.
1574 *
1575 * Locking:
1576 * tty_mutex
1577 * takes the file list lock internally when working on the list of ttys
1578 * that the driver keeps.
1579 */
1580static void release_tty(struct tty_struct *tty, int idx)
1581{
1582 /* This should always be true but check for the moment */
1583 WARN_ON(tty->index != idx);
1584 WARN_ON(!mutex_is_locked(&tty_mutex));
1585 if (tty->ops->shutdown)
1586 tty->ops->shutdown(tty);
1587 tty_save_termios(tty);
1588 tty_driver_remove_tty(tty->driver, tty);
1589 if (tty->port)
1590 tty->port->itty = NULL;
1591 if (tty->link)
1592 tty->link->port->itty = NULL;
1593 if (tty->port)
1594 tty_buffer_cancel_work(tty->port);
1595 if (tty->link)
1596 tty_buffer_cancel_work(tty->link->port);
1597
1598 tty_kref_put(tty->link);
1599 tty_kref_put(tty);
1600}
1601
1602/**
1603 * tty_release_checks - check a tty before real release
1604 * @tty: tty to check
1605 * @idx: index of the tty
1606 *
1607 * Performs some paranoid checking before true release of the @tty. This is a
1608 * no-op unless %TTY_PARANOIA_CHECK is defined.
1609 */
1610static int tty_release_checks(struct tty_struct *tty, int idx)
1611{
1612#ifdef TTY_PARANOIA_CHECK
1613 if (idx < 0 || idx >= tty->driver->num) {
1614 tty_debug(tty, "bad idx %d\n", idx);
1615 return -1;
1616 }
1617
1618 /* not much to check for devpts */
1619 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1620 return 0;
1621
1622 if (tty != tty->driver->ttys[idx]) {
1623 tty_debug(tty, "bad driver table[%d] = %p\n",
1624 idx, tty->driver->ttys[idx]);
1625 return -1;
1626 }
1627 if (tty->driver->other) {
1628 struct tty_struct *o_tty = tty->link;
1629
1630 if (o_tty != tty->driver->other->ttys[idx]) {
1631 tty_debug(tty, "bad other table[%d] = %p\n",
1632 idx, tty->driver->other->ttys[idx]);
1633 return -1;
1634 }
1635 if (o_tty->link != tty) {
1636 tty_debug(tty, "bad link = %p\n", o_tty->link);
1637 return -1;
1638 }
1639 }
1640#endif
1641 return 0;
1642}
1643
1644/**
1645 * tty_kclose - closes tty opened by tty_kopen
1646 * @tty: tty device
1647 *
1648 * Performs the final steps to release and free a tty device. It is the same as
1649 * tty_release_struct() except that it also resets %TTY_PORT_KOPENED flag on
1650 * @tty->port.
1651 */
1652void tty_kclose(struct tty_struct *tty)
1653{
1654 /*
1655 * Ask the line discipline code to release its structures
1656 */
1657 tty_ldisc_release(tty);
1658
1659 /* Wait for pending work before tty destruction commences */
1660 tty_flush_works(tty);
1661
1662 tty_debug_hangup(tty, "freeing structure\n");
1663 /*
1664 * The release_tty function takes care of the details of clearing
1665 * the slots and preserving the termios structure.
1666 */
1667 mutex_lock(&tty_mutex);
1668 tty_port_set_kopened(tty->port, 0);
1669 release_tty(tty, tty->index);
1670 mutex_unlock(&tty_mutex);
1671}
1672EXPORT_SYMBOL_GPL(tty_kclose);
1673
1674/**
1675 * tty_release_struct - release a tty struct
1676 * @tty: tty device
1677 * @idx: index of the tty
1678 *
1679 * Performs the final steps to release and free a tty device. It is roughly the
1680 * reverse of tty_init_dev().
1681 */
1682void tty_release_struct(struct tty_struct *tty, int idx)
1683{
1684 /*
1685 * Ask the line discipline code to release its structures
1686 */
1687 tty_ldisc_release(tty);
1688
1689 /* Wait for pending work before tty destruction commmences */
1690 tty_flush_works(tty);
1691
1692 tty_debug_hangup(tty, "freeing structure\n");
1693 /*
1694 * The release_tty function takes care of the details of clearing
1695 * the slots and preserving the termios structure.
1696 */
1697 mutex_lock(&tty_mutex);
1698 release_tty(tty, idx);
1699 mutex_unlock(&tty_mutex);
1700}
1701EXPORT_SYMBOL_GPL(tty_release_struct);
1702
1703/**
1704 * tty_release - vfs callback for close
1705 * @inode: inode of tty
1706 * @filp: file pointer for handle to tty
1707 *
1708 * Called the last time each file handle is closed that references this tty.
1709 * There may however be several such references.
1710 *
1711 * Locking:
1712 * Takes BKL. See tty_release_dev().
1713 *
1714 * Even releasing the tty structures is a tricky business. We have to be very
1715 * careful that the structures are all released at the same time, as interrupts
1716 * might otherwise get the wrong pointers.
1717 *
1718 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1719 * lead to double frees or releasing memory still in use.
1720 */
1721int tty_release(struct inode *inode, struct file *filp)
1722{
1723 struct tty_struct *tty = file_tty(filp);
1724 struct tty_struct *o_tty = NULL;
1725 int do_sleep, final;
1726 int idx;
1727 long timeout = 0;
1728 int once = 1;
1729
1730 if (tty_paranoia_check(tty, inode, __func__))
1731 return 0;
1732
1733 tty_lock(tty);
1734 check_tty_count(tty, __func__);
1735
1736 __tty_fasync(-1, filp, 0);
1737
1738 idx = tty->index;
1739 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1740 tty->driver->subtype == PTY_TYPE_MASTER)
1741 o_tty = tty->link;
1742
1743 if (tty_release_checks(tty, idx)) {
1744 tty_unlock(tty);
1745 return 0;
1746 }
1747
1748 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1749
1750 if (tty->ops->close)
1751 tty->ops->close(tty, filp);
1752
1753 /* If tty is pty master, lock the slave pty (stable lock order) */
1754 tty_lock_slave(o_tty);
1755
1756 /*
1757 * Sanity check: if tty->count is going to zero, there shouldn't be
1758 * any waiters on tty->read_wait or tty->write_wait. We test the
1759 * wait queues and kick everyone out _before_ actually starting to
1760 * close. This ensures that we won't block while releasing the tty
1761 * structure.
1762 *
1763 * The test for the o_tty closing is necessary, since the master and
1764 * slave sides may close in any order. If the slave side closes out
1765 * first, its count will be one, since the master side holds an open.
1766 * Thus this test wouldn't be triggered at the time the slave closed,
1767 * so we do it now.
1768 */
1769 while (1) {
1770 do_sleep = 0;
1771
1772 if (tty->count <= 1) {
1773 if (waitqueue_active(&tty->read_wait)) {
1774 wake_up_poll(&tty->read_wait, EPOLLIN);
1775 do_sleep++;
1776 }
1777 if (waitqueue_active(&tty->write_wait)) {
1778 wake_up_poll(&tty->write_wait, EPOLLOUT);
1779 do_sleep++;
1780 }
1781 }
1782 if (o_tty && o_tty->count <= 1) {
1783 if (waitqueue_active(&o_tty->read_wait)) {
1784 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1785 do_sleep++;
1786 }
1787 if (waitqueue_active(&o_tty->write_wait)) {
1788 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1789 do_sleep++;
1790 }
1791 }
1792 if (!do_sleep)
1793 break;
1794
1795 if (once) {
1796 once = 0;
1797 tty_warn(tty, "read/write wait queue active!\n");
1798 }
1799 schedule_timeout_killable(timeout);
1800 if (timeout < 120 * HZ)
1801 timeout = 2 * timeout + 1;
1802 else
1803 timeout = MAX_SCHEDULE_TIMEOUT;
1804 }
1805
1806 if (o_tty) {
1807 if (--o_tty->count < 0) {
1808 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1809 o_tty->count = 0;
1810 }
1811 }
1812 if (--tty->count < 0) {
1813 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1814 tty->count = 0;
1815 }
1816
1817 /*
1818 * We've decremented tty->count, so we need to remove this file
1819 * descriptor off the tty->tty_files list; this serves two
1820 * purposes:
1821 * - check_tty_count sees the correct number of file descriptors
1822 * associated with this tty.
1823 * - do_tty_hangup no longer sees this file descriptor as
1824 * something that needs to be handled for hangups.
1825 */
1826 tty_del_file(filp);
1827
1828 /*
1829 * Perform some housekeeping before deciding whether to return.
1830 *
1831 * If _either_ side is closing, make sure there aren't any
1832 * processes that still think tty or o_tty is their controlling
1833 * tty.
1834 */
1835 if (!tty->count) {
1836 read_lock(&tasklist_lock);
1837 session_clear_tty(tty->ctrl.session);
1838 if (o_tty)
1839 session_clear_tty(o_tty->ctrl.session);
1840 read_unlock(&tasklist_lock);
1841 }
1842
1843 /* check whether both sides are closing ... */
1844 final = !tty->count && !(o_tty && o_tty->count);
1845
1846 tty_unlock_slave(o_tty);
1847 tty_unlock(tty);
1848
1849 /* At this point, the tty->count == 0 should ensure a dead tty
1850 * cannot be re-opened by a racing opener.
1851 */
1852
1853 if (!final)
1854 return 0;
1855
1856 tty_debug_hangup(tty, "final close\n");
1857
1858 tty_release_struct(tty, idx);
1859 return 0;
1860}
1861
1862/**
1863 * tty_open_current_tty - get locked tty of current task
1864 * @device: device number
1865 * @filp: file pointer to tty
1866 * @return: locked tty of the current task iff @device is /dev/tty
1867 *
1868 * Performs a re-open of the current task's controlling tty.
1869 *
1870 * We cannot return driver and index like for the other nodes because devpts
1871 * will not work then. It expects inodes to be from devpts FS.
1872 */
1873static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1874{
1875 struct tty_struct *tty;
1876 int retval;
1877
1878 if (device != MKDEV(TTYAUX_MAJOR, 0))
1879 return NULL;
1880
1881 tty = get_current_tty();
1882 if (!tty)
1883 return ERR_PTR(-ENXIO);
1884
1885 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1886 /* noctty = 1; */
1887 tty_lock(tty);
1888 tty_kref_put(tty); /* safe to drop the kref now */
1889
1890 retval = tty_reopen(tty);
1891 if (retval < 0) {
1892 tty_unlock(tty);
1893 tty = ERR_PTR(retval);
1894 }
1895 return tty;
1896}
1897
1898/**
1899 * tty_lookup_driver - lookup a tty driver for a given device file
1900 * @device: device number
1901 * @filp: file pointer to tty
1902 * @index: index for the device in the @return driver
1903 *
1904 * If returned value is not erroneous, the caller is responsible to decrement
1905 * the refcount by tty_driver_kref_put().
1906 *
1907 * Locking: %tty_mutex protects get_tty_driver()
1908 *
1909 * Return: driver for this inode (with increased refcount)
1910 */
1911static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1912 int *index)
1913{
1914 struct tty_driver *driver = NULL;
1915
1916 switch (device) {
1917#ifdef CONFIG_VT
1918 case MKDEV(TTY_MAJOR, 0): {
1919 extern struct tty_driver *console_driver;
1920
1921 driver = tty_driver_kref_get(console_driver);
1922 *index = fg_console;
1923 break;
1924 }
1925#endif
1926 case MKDEV(TTYAUX_MAJOR, 1): {
1927 struct tty_driver *console_driver = console_device(index);
1928
1929 if (console_driver) {
1930 driver = tty_driver_kref_get(console_driver);
1931 if (driver && filp) {
1932 /* Don't let /dev/console block */
1933 filp->f_flags |= O_NONBLOCK;
1934 break;
1935 }
1936 }
1937 if (driver)
1938 tty_driver_kref_put(driver);
1939 return ERR_PTR(-ENODEV);
1940 }
1941 default:
1942 driver = get_tty_driver(device, index);
1943 if (!driver)
1944 return ERR_PTR(-ENODEV);
1945 break;
1946 }
1947 return driver;
1948}
1949
1950static struct tty_struct *tty_kopen(dev_t device, int shared)
1951{
1952 struct tty_struct *tty;
1953 struct tty_driver *driver;
1954 int index = -1;
1955
1956 mutex_lock(&tty_mutex);
1957 driver = tty_lookup_driver(device, NULL, &index);
1958 if (IS_ERR(driver)) {
1959 mutex_unlock(&tty_mutex);
1960 return ERR_CAST(driver);
1961 }
1962
1963 /* check whether we're reopening an existing tty */
1964 tty = tty_driver_lookup_tty(driver, NULL, index);
1965 if (IS_ERR(tty) || shared)
1966 goto out;
1967
1968 if (tty) {
1969 /* drop kref from tty_driver_lookup_tty() */
1970 tty_kref_put(tty);
1971 tty = ERR_PTR(-EBUSY);
1972 } else { /* tty_init_dev returns tty with the tty_lock held */
1973 tty = tty_init_dev(driver, index);
1974 if (IS_ERR(tty))
1975 goto out;
1976 tty_port_set_kopened(tty->port, 1);
1977 }
1978out:
1979 mutex_unlock(&tty_mutex);
1980 tty_driver_kref_put(driver);
1981 return tty;
1982}
1983
1984/**
1985 * tty_kopen_exclusive - open a tty device for kernel
1986 * @device: dev_t of device to open
1987 *
1988 * Opens tty exclusively for kernel. Performs the driver lookup, makes sure
1989 * it's not already opened and performs the first-time tty initialization.
1990 *
1991 * Claims the global %tty_mutex to serialize:
1992 * * concurrent first-time tty initialization
1993 * * concurrent tty driver removal w/ lookup
1994 * * concurrent tty removal from driver table
1995 *
1996 * Return: the locked initialized &tty_struct
1997 */
1998struct tty_struct *tty_kopen_exclusive(dev_t device)
1999{
2000 return tty_kopen(device, 0);
2001}
2002EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2003
2004/**
2005 * tty_kopen_shared - open a tty device for shared in-kernel use
2006 * @device: dev_t of device to open
2007 *
2008 * Opens an already existing tty for in-kernel use. Compared to
2009 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2010 *
2011 * Locking: identical to tty_kopen() above.
2012 */
2013struct tty_struct *tty_kopen_shared(dev_t device)
2014{
2015 return tty_kopen(device, 1);
2016}
2017EXPORT_SYMBOL_GPL(tty_kopen_shared);
2018
2019/**
2020 * tty_open_by_driver - open a tty device
2021 * @device: dev_t of device to open
2022 * @filp: file pointer to tty
2023 *
2024 * Performs the driver lookup, checks for a reopen, or otherwise performs the
2025 * first-time tty initialization.
2026 *
2027 *
2028 * Claims the global tty_mutex to serialize:
2029 * * concurrent first-time tty initialization
2030 * * concurrent tty driver removal w/ lookup
2031 * * concurrent tty removal from driver table
2032 *
2033 * Return: the locked initialized or re-opened &tty_struct
2034 */
2035static struct tty_struct *tty_open_by_driver(dev_t device,
2036 struct file *filp)
2037{
2038 struct tty_struct *tty;
2039 struct tty_driver *driver = NULL;
2040 int index = -1;
2041 int retval;
2042
2043 mutex_lock(&tty_mutex);
2044 driver = tty_lookup_driver(device, filp, &index);
2045 if (IS_ERR(driver)) {
2046 mutex_unlock(&tty_mutex);
2047 return ERR_CAST(driver);
2048 }
2049
2050 /* check whether we're reopening an existing tty */
2051 tty = tty_driver_lookup_tty(driver, filp, index);
2052 if (IS_ERR(tty)) {
2053 mutex_unlock(&tty_mutex);
2054 goto out;
2055 }
2056
2057 if (tty) {
2058 if (tty_port_kopened(tty->port)) {
2059 tty_kref_put(tty);
2060 mutex_unlock(&tty_mutex);
2061 tty = ERR_PTR(-EBUSY);
2062 goto out;
2063 }
2064 mutex_unlock(&tty_mutex);
2065 retval = tty_lock_interruptible(tty);
2066 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2067 if (retval) {
2068 if (retval == -EINTR)
2069 retval = -ERESTARTSYS;
2070 tty = ERR_PTR(retval);
2071 goto out;
2072 }
2073 retval = tty_reopen(tty);
2074 if (retval < 0) {
2075 tty_unlock(tty);
2076 tty = ERR_PTR(retval);
2077 }
2078 } else { /* Returns with the tty_lock held for now */
2079 tty = tty_init_dev(driver, index);
2080 mutex_unlock(&tty_mutex);
2081 }
2082out:
2083 tty_driver_kref_put(driver);
2084 return tty;
2085}
2086
2087/**
2088 * tty_open - open a tty device
2089 * @inode: inode of device file
2090 * @filp: file pointer to tty
2091 *
2092 * tty_open() and tty_release() keep up the tty count that contains the number
2093 * of opens done on a tty. We cannot use the inode-count, as different inodes
2094 * might point to the same tty.
2095 *
2096 * Open-counting is needed for pty masters, as well as for keeping track of
2097 * serial lines: DTR is dropped when the last close happens.
2098 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2099 *
2100 * The termios state of a pty is reset on the first open so that settings don't
2101 * persist across reuse.
2102 *
2103 * Locking:
2104 * * %tty_mutex protects tty, tty_lookup_driver() and tty_init_dev().
2105 * * @tty->count should protect the rest.
2106 * * ->siglock protects ->signal/->sighand
2107 *
2108 * Note: the tty_unlock/lock cases without a ref are only safe due to %tty_mutex
2109 */
2110static int tty_open(struct inode *inode, struct file *filp)
2111{
2112 struct tty_struct *tty;
2113 int noctty, retval;
2114 dev_t device = inode->i_rdev;
2115 unsigned saved_flags = filp->f_flags;
2116
2117 nonseekable_open(inode, filp);
2118
2119retry_open:
2120 retval = tty_alloc_file(filp);
2121 if (retval)
2122 return -ENOMEM;
2123
2124 tty = tty_open_current_tty(device, filp);
2125 if (!tty)
2126 tty = tty_open_by_driver(device, filp);
2127
2128 if (IS_ERR(tty)) {
2129 tty_free_file(filp);
2130 retval = PTR_ERR(tty);
2131 if (retval != -EAGAIN || signal_pending(current))
2132 return retval;
2133 schedule();
2134 goto retry_open;
2135 }
2136
2137 tty_add_file(tty, filp);
2138
2139 check_tty_count(tty, __func__);
2140 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2141
2142 if (tty->ops->open)
2143 retval = tty->ops->open(tty, filp);
2144 else
2145 retval = -ENODEV;
2146 filp->f_flags = saved_flags;
2147
2148 if (retval) {
2149 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2150
2151 tty_unlock(tty); /* need to call tty_release without BTM */
2152 tty_release(inode, filp);
2153 if (retval != -ERESTARTSYS)
2154 return retval;
2155
2156 if (signal_pending(current))
2157 return retval;
2158
2159 schedule();
2160 /*
2161 * Need to reset f_op in case a hangup happened.
2162 */
2163 if (tty_hung_up_p(filp))
2164 filp->f_op = &tty_fops;
2165 goto retry_open;
2166 }
2167 clear_bit(TTY_HUPPED, &tty->flags);
2168
2169 noctty = (filp->f_flags & O_NOCTTY) ||
2170 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2171 device == MKDEV(TTYAUX_MAJOR, 1) ||
2172 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2173 tty->driver->subtype == PTY_TYPE_MASTER);
2174 if (!noctty)
2175 tty_open_proc_set_tty(filp, tty);
2176 tty_unlock(tty);
2177 return 0;
2178}
2179
2180
2181/**
2182 * tty_poll - check tty status
2183 * @filp: file being polled
2184 * @wait: poll wait structures to update
2185 *
2186 * Call the line discipline polling method to obtain the poll status of the
2187 * device.
2188 *
2189 * Locking: locks called line discipline but ldisc poll method may be
2190 * re-entered freely by other callers.
2191 */
2192static __poll_t tty_poll(struct file *filp, poll_table *wait)
2193{
2194 struct tty_struct *tty = file_tty(filp);
2195 struct tty_ldisc *ld;
2196 __poll_t ret = 0;
2197
2198 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2199 return 0;
2200
2201 ld = tty_ldisc_ref_wait(tty);
2202 if (!ld)
2203 return hung_up_tty_poll(filp, wait);
2204 if (ld->ops->poll)
2205 ret = ld->ops->poll(tty, filp, wait);
2206 tty_ldisc_deref(ld);
2207 return ret;
2208}
2209
2210static int __tty_fasync(int fd, struct file *filp, int on)
2211{
2212 struct tty_struct *tty = file_tty(filp);
2213 unsigned long flags;
2214 int retval = 0;
2215
2216 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2217 goto out;
2218
2219 retval = fasync_helper(fd, filp, on, &tty->fasync);
2220 if (retval <= 0)
2221 goto out;
2222
2223 if (on) {
2224 enum pid_type type;
2225 struct pid *pid;
2226
2227 spin_lock_irqsave(&tty->ctrl.lock, flags);
2228 if (tty->ctrl.pgrp) {
2229 pid = tty->ctrl.pgrp;
2230 type = PIDTYPE_PGID;
2231 } else {
2232 pid = task_pid(current);
2233 type = PIDTYPE_TGID;
2234 }
2235 get_pid(pid);
2236 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
2237 __f_setown(filp, pid, type, 0);
2238 put_pid(pid);
2239 retval = 0;
2240 }
2241out:
2242 return retval;
2243}
2244
2245static int tty_fasync(int fd, struct file *filp, int on)
2246{
2247 struct tty_struct *tty = file_tty(filp);
2248 int retval = -ENOTTY;
2249
2250 tty_lock(tty);
2251 if (!tty_hung_up_p(filp))
2252 retval = __tty_fasync(fd, filp, on);
2253 tty_unlock(tty);
2254
2255 return retval;
2256}
2257
2258static bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI);
2259/**
2260 * tiocsti - fake input character
2261 * @tty: tty to fake input into
2262 * @p: pointer to character
2263 *
2264 * Fake input to a tty device. Does the necessary locking and input management.
2265 *
2266 * FIXME: does not honour flow control ??
2267 *
2268 * Locking:
2269 * * Called functions take tty_ldiscs_lock
2270 * * current->signal->tty check is safe without locks
2271 */
2272static int tiocsti(struct tty_struct *tty, char __user *p)
2273{
2274 char ch, mbz = 0;
2275 struct tty_ldisc *ld;
2276
2277 if (!tty_legacy_tiocsti)
2278 return -EIO;
2279
2280 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2281 return -EPERM;
2282 if (get_user(ch, p))
2283 return -EFAULT;
2284 tty_audit_tiocsti(tty, ch);
2285 ld = tty_ldisc_ref_wait(tty);
2286 if (!ld)
2287 return -EIO;
2288 tty_buffer_lock_exclusive(tty->port);
2289 if (ld->ops->receive_buf)
2290 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2291 tty_buffer_unlock_exclusive(tty->port);
2292 tty_ldisc_deref(ld);
2293 return 0;
2294}
2295
2296/**
2297 * tiocgwinsz - implement window query ioctl
2298 * @tty: tty
2299 * @arg: user buffer for result
2300 *
2301 * Copies the kernel idea of the window size into the user buffer.
2302 *
2303 * Locking: @tty->winsize_mutex is taken to ensure the winsize data is
2304 * consistent.
2305 */
2306static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2307{
2308 int err;
2309
2310 mutex_lock(&tty->winsize_mutex);
2311 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2312 mutex_unlock(&tty->winsize_mutex);
2313
2314 return err ? -EFAULT : 0;
2315}
2316
2317/**
2318 * tty_do_resize - resize event
2319 * @tty: tty being resized
2320 * @ws: new dimensions
2321 *
2322 * Update the termios variables and send the necessary signals to peform a
2323 * terminal resize correctly.
2324 */
2325int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2326{
2327 struct pid *pgrp;
2328
2329 /* Lock the tty */
2330 mutex_lock(&tty->winsize_mutex);
2331 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2332 goto done;
2333
2334 /* Signal the foreground process group */
2335 pgrp = tty_get_pgrp(tty);
2336 if (pgrp)
2337 kill_pgrp(pgrp, SIGWINCH, 1);
2338 put_pid(pgrp);
2339
2340 tty->winsize = *ws;
2341done:
2342 mutex_unlock(&tty->winsize_mutex);
2343 return 0;
2344}
2345EXPORT_SYMBOL(tty_do_resize);
2346
2347/**
2348 * tiocswinsz - implement window size set ioctl
2349 * @tty: tty side of tty
2350 * @arg: user buffer for result
2351 *
2352 * Copies the user idea of the window size to the kernel. Traditionally this is
2353 * just advisory information but for the Linux console it actually has driver
2354 * level meaning and triggers a VC resize.
2355 *
2356 * Locking:
2357 * Driver dependent. The default do_resize method takes the tty termios
2358 * mutex and ctrl.lock. The console takes its own lock then calls into the
2359 * default method.
2360 */
2361static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2362{
2363 struct winsize tmp_ws;
2364
2365 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2366 return -EFAULT;
2367
2368 if (tty->ops->resize)
2369 return tty->ops->resize(tty, &tmp_ws);
2370 else
2371 return tty_do_resize(tty, &tmp_ws);
2372}
2373
2374/**
2375 * tioccons - allow admin to move logical console
2376 * @file: the file to become console
2377 *
2378 * Allow the administrator to move the redirected console device.
2379 *
2380 * Locking: uses redirect_lock to guard the redirect information
2381 */
2382static int tioccons(struct file *file)
2383{
2384 if (!capable(CAP_SYS_ADMIN))
2385 return -EPERM;
2386 if (file->f_op->write_iter == redirected_tty_write) {
2387 struct file *f;
2388
2389 spin_lock(&redirect_lock);
2390 f = redirect;
2391 redirect = NULL;
2392 spin_unlock(&redirect_lock);
2393 if (f)
2394 fput(f);
2395 return 0;
2396 }
2397 if (file->f_op->write_iter != tty_write)
2398 return -ENOTTY;
2399 if (!(file->f_mode & FMODE_WRITE))
2400 return -EBADF;
2401 if (!(file->f_mode & FMODE_CAN_WRITE))
2402 return -EINVAL;
2403 spin_lock(&redirect_lock);
2404 if (redirect) {
2405 spin_unlock(&redirect_lock);
2406 return -EBUSY;
2407 }
2408 redirect = get_file(file);
2409 spin_unlock(&redirect_lock);
2410 return 0;
2411}
2412
2413/**
2414 * tiocsetd - set line discipline
2415 * @tty: tty device
2416 * @p: pointer to user data
2417 *
2418 * Set the line discipline according to user request.
2419 *
2420 * Locking: see tty_set_ldisc(), this function is just a helper
2421 */
2422static int tiocsetd(struct tty_struct *tty, int __user *p)
2423{
2424 int disc;
2425 int ret;
2426
2427 if (get_user(disc, p))
2428 return -EFAULT;
2429
2430 ret = tty_set_ldisc(tty, disc);
2431
2432 return ret;
2433}
2434
2435/**
2436 * tiocgetd - get line discipline
2437 * @tty: tty device
2438 * @p: pointer to user data
2439 *
2440 * Retrieves the line discipline id directly from the ldisc.
2441 *
2442 * Locking: waits for ldisc reference (in case the line discipline is changing
2443 * or the @tty is being hungup)
2444 */
2445static int tiocgetd(struct tty_struct *tty, int __user *p)
2446{
2447 struct tty_ldisc *ld;
2448 int ret;
2449
2450 ld = tty_ldisc_ref_wait(tty);
2451 if (!ld)
2452 return -EIO;
2453 ret = put_user(ld->ops->num, p);
2454 tty_ldisc_deref(ld);
2455 return ret;
2456}
2457
2458/**
2459 * send_break - performed time break
2460 * @tty: device to break on
2461 * @duration: timeout in mS
2462 *
2463 * Perform a timed break on hardware that lacks its own driver level timed
2464 * break functionality.
2465 *
2466 * Locking:
2467 * @tty->atomic_write_lock serializes
2468 */
2469static int send_break(struct tty_struct *tty, unsigned int duration)
2470{
2471 int retval;
2472
2473 if (tty->ops->break_ctl == NULL)
2474 return 0;
2475
2476 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2477 retval = tty->ops->break_ctl(tty, duration);
2478 else {
2479 /* Do the work ourselves */
2480 if (tty_write_lock(tty, 0) < 0)
2481 return -EINTR;
2482 retval = tty->ops->break_ctl(tty, -1);
2483 if (retval)
2484 goto out;
2485 if (!signal_pending(current))
2486 msleep_interruptible(duration);
2487 retval = tty->ops->break_ctl(tty, 0);
2488out:
2489 tty_write_unlock(tty);
2490 if (signal_pending(current))
2491 retval = -EINTR;
2492 }
2493 return retval;
2494}
2495
2496/**
2497 * tty_tiocmget - get modem status
2498 * @tty: tty device
2499 * @p: pointer to result
2500 *
2501 * Obtain the modem status bits from the tty driver if the feature is
2502 * supported. Return -%ENOTTY if it is not available.
2503 *
2504 * Locking: none (up to the driver)
2505 */
2506static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2507{
2508 int retval = -ENOTTY;
2509
2510 if (tty->ops->tiocmget) {
2511 retval = tty->ops->tiocmget(tty);
2512
2513 if (retval >= 0)
2514 retval = put_user(retval, p);
2515 }
2516 return retval;
2517}
2518
2519/**
2520 * tty_tiocmset - set modem status
2521 * @tty: tty device
2522 * @cmd: command - clear bits, set bits or set all
2523 * @p: pointer to desired bits
2524 *
2525 * Set the modem status bits from the tty driver if the feature
2526 * is supported. Return -%ENOTTY if it is not available.
2527 *
2528 * Locking: none (up to the driver)
2529 */
2530static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2531 unsigned __user *p)
2532{
2533 int retval;
2534 unsigned int set, clear, val;
2535
2536 if (tty->ops->tiocmset == NULL)
2537 return -ENOTTY;
2538
2539 retval = get_user(val, p);
2540 if (retval)
2541 return retval;
2542 set = clear = 0;
2543 switch (cmd) {
2544 case TIOCMBIS:
2545 set = val;
2546 break;
2547 case TIOCMBIC:
2548 clear = val;
2549 break;
2550 case TIOCMSET:
2551 set = val;
2552 clear = ~val;
2553 break;
2554 }
2555 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2556 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2557 return tty->ops->tiocmset(tty, set, clear);
2558}
2559
2560/**
2561 * tty_get_icount - get tty statistics
2562 * @tty: tty device
2563 * @icount: output parameter
2564 *
2565 * Gets a copy of the @tty's icount statistics.
2566 *
2567 * Locking: none (up to the driver)
2568 */
2569int tty_get_icount(struct tty_struct *tty,
2570 struct serial_icounter_struct *icount)
2571{
2572 memset(icount, 0, sizeof(*icount));
2573
2574 if (tty->ops->get_icount)
2575 return tty->ops->get_icount(tty, icount);
2576 else
2577 return -ENOTTY;
2578}
2579EXPORT_SYMBOL_GPL(tty_get_icount);
2580
2581static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2582{
2583 struct serial_icounter_struct icount;
2584 int retval;
2585
2586 retval = tty_get_icount(tty, &icount);
2587 if (retval != 0)
2588 return retval;
2589
2590 if (copy_to_user(arg, &icount, sizeof(icount)))
2591 return -EFAULT;
2592 return 0;
2593}
2594
2595static int tty_set_serial(struct tty_struct *tty, struct serial_struct *ss)
2596{
2597 char comm[TASK_COMM_LEN];
2598 int flags;
2599
2600 flags = ss->flags & ASYNC_DEPRECATED;
2601
2602 if (flags)
2603 pr_warn_ratelimited("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2604 __func__, get_task_comm(comm, current), flags);
2605
2606 if (!tty->ops->set_serial)
2607 return -ENOTTY;
2608
2609 return tty->ops->set_serial(tty, ss);
2610}
2611
2612static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2613{
2614 struct serial_struct v;
2615
2616 if (copy_from_user(&v, ss, sizeof(*ss)))
2617 return -EFAULT;
2618
2619 return tty_set_serial(tty, &v);
2620}
2621
2622static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2623{
2624 struct serial_struct v;
2625 int err;
2626
2627 memset(&v, 0, sizeof(v));
2628 if (!tty->ops->get_serial)
2629 return -ENOTTY;
2630 err = tty->ops->get_serial(tty, &v);
2631 if (!err && copy_to_user(ss, &v, sizeof(v)))
2632 err = -EFAULT;
2633 return err;
2634}
2635
2636/*
2637 * if pty, return the slave side (real_tty)
2638 * otherwise, return self
2639 */
2640static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2641{
2642 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2643 tty->driver->subtype == PTY_TYPE_MASTER)
2644 tty = tty->link;
2645 return tty;
2646}
2647
2648/*
2649 * Split this up, as gcc can choke on it otherwise..
2650 */
2651long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2652{
2653 struct tty_struct *tty = file_tty(file);
2654 struct tty_struct *real_tty;
2655 void __user *p = (void __user *)arg;
2656 int retval;
2657 struct tty_ldisc *ld;
2658
2659 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2660 return -EINVAL;
2661
2662 real_tty = tty_pair_get_tty(tty);
2663
2664 /*
2665 * Factor out some common prep work
2666 */
2667 switch (cmd) {
2668 case TIOCSETD:
2669 case TIOCSBRK:
2670 case TIOCCBRK:
2671 case TCSBRK:
2672 case TCSBRKP:
2673 retval = tty_check_change(tty);
2674 if (retval)
2675 return retval;
2676 if (cmd != TIOCCBRK) {
2677 tty_wait_until_sent(tty, 0);
2678 if (signal_pending(current))
2679 return -EINTR;
2680 }
2681 break;
2682 }
2683
2684 /*
2685 * Now do the stuff.
2686 */
2687 switch (cmd) {
2688 case TIOCSTI:
2689 return tiocsti(tty, p);
2690 case TIOCGWINSZ:
2691 return tiocgwinsz(real_tty, p);
2692 case TIOCSWINSZ:
2693 return tiocswinsz(real_tty, p);
2694 case TIOCCONS:
2695 return real_tty != tty ? -EINVAL : tioccons(file);
2696 case TIOCEXCL:
2697 set_bit(TTY_EXCLUSIVE, &tty->flags);
2698 return 0;
2699 case TIOCNXCL:
2700 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2701 return 0;
2702 case TIOCGEXCL:
2703 {
2704 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2705
2706 return put_user(excl, (int __user *)p);
2707 }
2708 case TIOCGETD:
2709 return tiocgetd(tty, p);
2710 case TIOCSETD:
2711 return tiocsetd(tty, p);
2712 case TIOCVHANGUP:
2713 if (!capable(CAP_SYS_ADMIN))
2714 return -EPERM;
2715 tty_vhangup(tty);
2716 return 0;
2717 case TIOCGDEV:
2718 {
2719 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2720
2721 return put_user(ret, (unsigned int __user *)p);
2722 }
2723 /*
2724 * Break handling
2725 */
2726 case TIOCSBRK: /* Turn break on, unconditionally */
2727 if (tty->ops->break_ctl)
2728 return tty->ops->break_ctl(tty, -1);
2729 return 0;
2730 case TIOCCBRK: /* Turn break off, unconditionally */
2731 if (tty->ops->break_ctl)
2732 return tty->ops->break_ctl(tty, 0);
2733 return 0;
2734 case TCSBRK: /* SVID version: non-zero arg --> no break */
2735 /* non-zero arg means wait for all output data
2736 * to be sent (performed above) but don't send break.
2737 * This is used by the tcdrain() termios function.
2738 */
2739 if (!arg)
2740 return send_break(tty, 250);
2741 return 0;
2742 case TCSBRKP: /* support for POSIX tcsendbreak() */
2743 return send_break(tty, arg ? arg*100 : 250);
2744
2745 case TIOCMGET:
2746 return tty_tiocmget(tty, p);
2747 case TIOCMSET:
2748 case TIOCMBIC:
2749 case TIOCMBIS:
2750 return tty_tiocmset(tty, cmd, p);
2751 case TIOCGICOUNT:
2752 return tty_tiocgicount(tty, p);
2753 case TCFLSH:
2754 switch (arg) {
2755 case TCIFLUSH:
2756 case TCIOFLUSH:
2757 /* flush tty buffer and allow ldisc to process ioctl */
2758 tty_buffer_flush(tty, NULL);
2759 break;
2760 }
2761 break;
2762 case TIOCSSERIAL:
2763 return tty_tiocsserial(tty, p);
2764 case TIOCGSERIAL:
2765 return tty_tiocgserial(tty, p);
2766 case TIOCGPTPEER:
2767 /* Special because the struct file is needed */
2768 return ptm_open_peer(file, tty, (int)arg);
2769 default:
2770 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2771 if (retval != -ENOIOCTLCMD)
2772 return retval;
2773 }
2774 if (tty->ops->ioctl) {
2775 retval = tty->ops->ioctl(tty, cmd, arg);
2776 if (retval != -ENOIOCTLCMD)
2777 return retval;
2778 }
2779 ld = tty_ldisc_ref_wait(tty);
2780 if (!ld)
2781 return hung_up_tty_ioctl(file, cmd, arg);
2782 retval = -EINVAL;
2783 if (ld->ops->ioctl) {
2784 retval = ld->ops->ioctl(tty, cmd, arg);
2785 if (retval == -ENOIOCTLCMD)
2786 retval = -ENOTTY;
2787 }
2788 tty_ldisc_deref(ld);
2789 return retval;
2790}
2791
2792#ifdef CONFIG_COMPAT
2793
2794struct serial_struct32 {
2795 compat_int_t type;
2796 compat_int_t line;
2797 compat_uint_t port;
2798 compat_int_t irq;
2799 compat_int_t flags;
2800 compat_int_t xmit_fifo_size;
2801 compat_int_t custom_divisor;
2802 compat_int_t baud_base;
2803 unsigned short close_delay;
2804 char io_type;
2805 char reserved_char;
2806 compat_int_t hub6;
2807 unsigned short closing_wait; /* time to wait before closing */
2808 unsigned short closing_wait2; /* no longer used... */
2809 compat_uint_t iomem_base;
2810 unsigned short iomem_reg_shift;
2811 unsigned int port_high;
2812 /* compat_ulong_t iomap_base FIXME */
2813 compat_int_t reserved;
2814};
2815
2816static int compat_tty_tiocsserial(struct tty_struct *tty,
2817 struct serial_struct32 __user *ss)
2818{
2819 struct serial_struct32 v32;
2820 struct serial_struct v;
2821
2822 if (copy_from_user(&v32, ss, sizeof(*ss)))
2823 return -EFAULT;
2824
2825 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2826 v.iomem_base = compat_ptr(v32.iomem_base);
2827 v.iomem_reg_shift = v32.iomem_reg_shift;
2828 v.port_high = v32.port_high;
2829 v.iomap_base = 0;
2830
2831 return tty_set_serial(tty, &v);
2832}
2833
2834static int compat_tty_tiocgserial(struct tty_struct *tty,
2835 struct serial_struct32 __user *ss)
2836{
2837 struct serial_struct32 v32;
2838 struct serial_struct v;
2839 int err;
2840
2841 memset(&v, 0, sizeof(v));
2842 memset(&v32, 0, sizeof(v32));
2843
2844 if (!tty->ops->get_serial)
2845 return -ENOTTY;
2846 err = tty->ops->get_serial(tty, &v);
2847 if (!err) {
2848 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2849 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2850 0xfffffff : ptr_to_compat(v.iomem_base);
2851 v32.iomem_reg_shift = v.iomem_reg_shift;
2852 v32.port_high = v.port_high;
2853 if (copy_to_user(ss, &v32, sizeof(v32)))
2854 err = -EFAULT;
2855 }
2856 return err;
2857}
2858static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2859 unsigned long arg)
2860{
2861 struct tty_struct *tty = file_tty(file);
2862 struct tty_ldisc *ld;
2863 int retval = -ENOIOCTLCMD;
2864
2865 switch (cmd) {
2866 case TIOCOUTQ:
2867 case TIOCSTI:
2868 case TIOCGWINSZ:
2869 case TIOCSWINSZ:
2870 case TIOCGEXCL:
2871 case TIOCGETD:
2872 case TIOCSETD:
2873 case TIOCGDEV:
2874 case TIOCMGET:
2875 case TIOCMSET:
2876 case TIOCMBIC:
2877 case TIOCMBIS:
2878 case TIOCGICOUNT:
2879 case TIOCGPGRP:
2880 case TIOCSPGRP:
2881 case TIOCGSID:
2882 case TIOCSERGETLSR:
2883 case TIOCGRS485:
2884 case TIOCSRS485:
2885#ifdef TIOCGETP
2886 case TIOCGETP:
2887 case TIOCSETP:
2888 case TIOCSETN:
2889#endif
2890#ifdef TIOCGETC
2891 case TIOCGETC:
2892 case TIOCSETC:
2893#endif
2894#ifdef TIOCGLTC
2895 case TIOCGLTC:
2896 case TIOCSLTC:
2897#endif
2898 case TCSETSF:
2899 case TCSETSW:
2900 case TCSETS:
2901 case TCGETS:
2902#ifdef TCGETS2
2903 case TCGETS2:
2904 case TCSETSF2:
2905 case TCSETSW2:
2906 case TCSETS2:
2907#endif
2908 case TCGETA:
2909 case TCSETAF:
2910 case TCSETAW:
2911 case TCSETA:
2912 case TIOCGLCKTRMIOS:
2913 case TIOCSLCKTRMIOS:
2914#ifdef TCGETX
2915 case TCGETX:
2916 case TCSETX:
2917 case TCSETXW:
2918 case TCSETXF:
2919#endif
2920 case TIOCGSOFTCAR:
2921 case TIOCSSOFTCAR:
2922
2923 case PPPIOCGCHAN:
2924 case PPPIOCGUNIT:
2925 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2926 case TIOCCONS:
2927 case TIOCEXCL:
2928 case TIOCNXCL:
2929 case TIOCVHANGUP:
2930 case TIOCSBRK:
2931 case TIOCCBRK:
2932 case TCSBRK:
2933 case TCSBRKP:
2934 case TCFLSH:
2935 case TIOCGPTPEER:
2936 case TIOCNOTTY:
2937 case TIOCSCTTY:
2938 case TCXONC:
2939 case TIOCMIWAIT:
2940 case TIOCSERCONFIG:
2941 return tty_ioctl(file, cmd, arg);
2942 }
2943
2944 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2945 return -EINVAL;
2946
2947 switch (cmd) {
2948 case TIOCSSERIAL:
2949 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2950 case TIOCGSERIAL:
2951 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2952 }
2953 if (tty->ops->compat_ioctl) {
2954 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2955 if (retval != -ENOIOCTLCMD)
2956 return retval;
2957 }
2958
2959 ld = tty_ldisc_ref_wait(tty);
2960 if (!ld)
2961 return hung_up_tty_compat_ioctl(file, cmd, arg);
2962 if (ld->ops->compat_ioctl)
2963 retval = ld->ops->compat_ioctl(tty, cmd, arg);
2964 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2965 retval = ld->ops->ioctl(tty, (unsigned long)compat_ptr(cmd),
2966 arg);
2967 tty_ldisc_deref(ld);
2968
2969 return retval;
2970}
2971#endif
2972
2973static int this_tty(const void *t, struct file *file, unsigned fd)
2974{
2975 if (likely(file->f_op->read_iter != tty_read))
2976 return 0;
2977 return file_tty(file) != t ? 0 : fd + 1;
2978}
2979
2980/*
2981 * This implements the "Secure Attention Key" --- the idea is to
2982 * prevent trojan horses by killing all processes associated with this
2983 * tty when the user hits the "Secure Attention Key". Required for
2984 * super-paranoid applications --- see the Orange Book for more details.
2985 *
2986 * This code could be nicer; ideally it should send a HUP, wait a few
2987 * seconds, then send a INT, and then a KILL signal. But you then
2988 * have to coordinate with the init process, since all processes associated
2989 * with the current tty must be dead before the new getty is allowed
2990 * to spawn.
2991 *
2992 * Now, if it would be correct ;-/ The current code has a nasty hole -
2993 * it doesn't catch files in flight. We may send the descriptor to ourselves
2994 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2995 *
2996 * Nasty bug: do_SAK is being called in interrupt context. This can
2997 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2998 */
2999void __do_SAK(struct tty_struct *tty)
3000{
3001 struct task_struct *g, *p;
3002 struct pid *session;
3003 int i;
3004 unsigned long flags;
3005
3006 spin_lock_irqsave(&tty->ctrl.lock, flags);
3007 session = get_pid(tty->ctrl.session);
3008 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
3009
3010 tty_ldisc_flush(tty);
3011
3012 tty_driver_flush_buffer(tty);
3013
3014 read_lock(&tasklist_lock);
3015 /* Kill the entire session */
3016 do_each_pid_task(session, PIDTYPE_SID, p) {
3017 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3018 task_pid_nr(p), p->comm);
3019 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3020 } while_each_pid_task(session, PIDTYPE_SID, p);
3021
3022 /* Now kill any processes that happen to have the tty open */
3023 do_each_thread(g, p) {
3024 if (p->signal->tty == tty) {
3025 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3026 task_pid_nr(p), p->comm);
3027 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3028 PIDTYPE_SID);
3029 continue;
3030 }
3031 task_lock(p);
3032 i = iterate_fd(p->files, 0, this_tty, tty);
3033 if (i != 0) {
3034 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3035 task_pid_nr(p), p->comm, i - 1);
3036 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3037 PIDTYPE_SID);
3038 }
3039 task_unlock(p);
3040 } while_each_thread(g, p);
3041 read_unlock(&tasklist_lock);
3042 put_pid(session);
3043}
3044
3045static void do_SAK_work(struct work_struct *work)
3046{
3047 struct tty_struct *tty =
3048 container_of(work, struct tty_struct, SAK_work);
3049 __do_SAK(tty);
3050}
3051
3052/*
3053 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3054 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3055 * the values which we write to it will be identical to the values which it
3056 * already has. --akpm
3057 */
3058void do_SAK(struct tty_struct *tty)
3059{
3060 if (!tty)
3061 return;
3062 schedule_work(&tty->SAK_work);
3063}
3064EXPORT_SYMBOL(do_SAK);
3065
3066/* Must put_device() after it's unused! */
3067static struct device *tty_get_device(struct tty_struct *tty)
3068{
3069 dev_t devt = tty_devnum(tty);
3070
3071 return class_find_device_by_devt(tty_class, devt);
3072}
3073
3074
3075/**
3076 * alloc_tty_struct - allocate a new tty
3077 * @driver: driver which will handle the returned tty
3078 * @idx: minor of the tty
3079 *
3080 * This subroutine allocates and initializes a tty structure.
3081 *
3082 * Locking: none - @tty in question is not exposed at this point
3083 */
3084struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3085{
3086 struct tty_struct *tty;
3087
3088 tty = kzalloc(sizeof(*tty), GFP_KERNEL_ACCOUNT);
3089 if (!tty)
3090 return NULL;
3091
3092 kref_init(&tty->kref);
3093 if (tty_ldisc_init(tty)) {
3094 kfree(tty);
3095 return NULL;
3096 }
3097 tty->ctrl.session = NULL;
3098 tty->ctrl.pgrp = NULL;
3099 mutex_init(&tty->legacy_mutex);
3100 mutex_init(&tty->throttle_mutex);
3101 init_rwsem(&tty->termios_rwsem);
3102 mutex_init(&tty->winsize_mutex);
3103 init_ldsem(&tty->ldisc_sem);
3104 init_waitqueue_head(&tty->write_wait);
3105 init_waitqueue_head(&tty->read_wait);
3106 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3107 mutex_init(&tty->atomic_write_lock);
3108 spin_lock_init(&tty->ctrl.lock);
3109 spin_lock_init(&tty->flow.lock);
3110 spin_lock_init(&tty->files_lock);
3111 INIT_LIST_HEAD(&tty->tty_files);
3112 INIT_WORK(&tty->SAK_work, do_SAK_work);
3113
3114 tty->driver = driver;
3115 tty->ops = driver->ops;
3116 tty->index = idx;
3117 tty_line_name(driver, idx, tty->name);
3118 tty->dev = tty_get_device(tty);
3119
3120 return tty;
3121}
3122
3123/**
3124 * tty_put_char - write one character to a tty
3125 * @tty: tty
3126 * @ch: character to write
3127 *
3128 * Write one byte to the @tty using the provided @tty->ops->put_char() method
3129 * if present.
3130 *
3131 * Note: the specific put_char operation in the driver layer may go
3132 * away soon. Don't call it directly, use this method
3133 *
3134 * Return: the number of characters successfully output.
3135 */
3136int tty_put_char(struct tty_struct *tty, unsigned char ch)
3137{
3138 if (tty->ops->put_char)
3139 return tty->ops->put_char(tty, ch);
3140 return tty->ops->write(tty, &ch, 1);
3141}
3142EXPORT_SYMBOL_GPL(tty_put_char);
3143
3144struct class *tty_class;
3145
3146static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3147 unsigned int index, unsigned int count)
3148{
3149 int err;
3150
3151 /* init here, since reused cdevs cause crashes */
3152 driver->cdevs[index] = cdev_alloc();
3153 if (!driver->cdevs[index])
3154 return -ENOMEM;
3155 driver->cdevs[index]->ops = &tty_fops;
3156 driver->cdevs[index]->owner = driver->owner;
3157 err = cdev_add(driver->cdevs[index], dev, count);
3158 if (err)
3159 kobject_put(&driver->cdevs[index]->kobj);
3160 return err;
3161}
3162
3163/**
3164 * tty_register_device - register a tty device
3165 * @driver: the tty driver that describes the tty device
3166 * @index: the index in the tty driver for this tty device
3167 * @device: a struct device that is associated with this tty device.
3168 * This field is optional, if there is no known struct device
3169 * for this tty device it can be set to NULL safely.
3170 *
3171 * This call is required to be made to register an individual tty device
3172 * if the tty driver's flags have the %TTY_DRIVER_DYNAMIC_DEV bit set. If
3173 * that bit is not set, this function should not be called by a tty
3174 * driver.
3175 *
3176 * Locking: ??
3177 *
3178 * Return: A pointer to the struct device for this tty device (or
3179 * ERR_PTR(-EFOO) on error).
3180 */
3181struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3182 struct device *device)
3183{
3184 return tty_register_device_attr(driver, index, device, NULL, NULL);
3185}
3186EXPORT_SYMBOL(tty_register_device);
3187
3188static void tty_device_create_release(struct device *dev)
3189{
3190 dev_dbg(dev, "releasing...\n");
3191 kfree(dev);
3192}
3193
3194/**
3195 * tty_register_device_attr - register a tty device
3196 * @driver: the tty driver that describes the tty device
3197 * @index: the index in the tty driver for this tty device
3198 * @device: a struct device that is associated with this tty device.
3199 * This field is optional, if there is no known struct device
3200 * for this tty device it can be set to %NULL safely.
3201 * @drvdata: Driver data to be set to device.
3202 * @attr_grp: Attribute group to be set on device.
3203 *
3204 * This call is required to be made to register an individual tty device if the
3205 * tty driver's flags have the %TTY_DRIVER_DYNAMIC_DEV bit set. If that bit is
3206 * not set, this function should not be called by a tty driver.
3207 *
3208 * Locking: ??
3209 *
3210 * Return: A pointer to the struct device for this tty device (or
3211 * ERR_PTR(-EFOO) on error).
3212 */
3213struct device *tty_register_device_attr(struct tty_driver *driver,
3214 unsigned index, struct device *device,
3215 void *drvdata,
3216 const struct attribute_group **attr_grp)
3217{
3218 char name[64];
3219 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3220 struct ktermios *tp;
3221 struct device *dev;
3222 int retval;
3223
3224 if (index >= driver->num) {
3225 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3226 driver->name, index);
3227 return ERR_PTR(-EINVAL);
3228 }
3229
3230 if (driver->type == TTY_DRIVER_TYPE_PTY)
3231 pty_line_name(driver, index, name);
3232 else
3233 tty_line_name(driver, index, name);
3234
3235 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3236 if (!dev)
3237 return ERR_PTR(-ENOMEM);
3238
3239 dev->devt = devt;
3240 dev->class = tty_class;
3241 dev->parent = device;
3242 dev->release = tty_device_create_release;
3243 dev_set_name(dev, "%s", name);
3244 dev->groups = attr_grp;
3245 dev_set_drvdata(dev, drvdata);
3246
3247 dev_set_uevent_suppress(dev, 1);
3248
3249 retval = device_register(dev);
3250 if (retval)
3251 goto err_put;
3252
3253 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3254 /*
3255 * Free any saved termios data so that the termios state is
3256 * reset when reusing a minor number.
3257 */
3258 tp = driver->termios[index];
3259 if (tp) {
3260 driver->termios[index] = NULL;
3261 kfree(tp);
3262 }
3263
3264 retval = tty_cdev_add(driver, devt, index, 1);
3265 if (retval)
3266 goto err_del;
3267 }
3268
3269 dev_set_uevent_suppress(dev, 0);
3270 kobject_uevent(&dev->kobj, KOBJ_ADD);
3271
3272 return dev;
3273
3274err_del:
3275 device_del(dev);
3276err_put:
3277 put_device(dev);
3278
3279 return ERR_PTR(retval);
3280}
3281EXPORT_SYMBOL_GPL(tty_register_device_attr);
3282
3283/**
3284 * tty_unregister_device - unregister a tty device
3285 * @driver: the tty driver that describes the tty device
3286 * @index: the index in the tty driver for this tty device
3287 *
3288 * If a tty device is registered with a call to tty_register_device() then
3289 * this function must be called when the tty device is gone.
3290 *
3291 * Locking: ??
3292 */
3293void tty_unregister_device(struct tty_driver *driver, unsigned index)
3294{
3295 device_destroy(tty_class,
3296 MKDEV(driver->major, driver->minor_start) + index);
3297 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3298 cdev_del(driver->cdevs[index]);
3299 driver->cdevs[index] = NULL;
3300 }
3301}
3302EXPORT_SYMBOL(tty_unregister_device);
3303
3304/**
3305 * __tty_alloc_driver -- allocate tty driver
3306 * @lines: count of lines this driver can handle at most
3307 * @owner: module which is responsible for this driver
3308 * @flags: some of %TTY_DRIVER_ flags, will be set in driver->flags
3309 *
3310 * This should not be called directly, some of the provided macros should be
3311 * used instead. Use IS_ERR() and friends on @retval.
3312 */
3313struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3314 unsigned long flags)
3315{
3316 struct tty_driver *driver;
3317 unsigned int cdevs = 1;
3318 int err;
3319
3320 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3321 return ERR_PTR(-EINVAL);
3322
3323 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3324 if (!driver)
3325 return ERR_PTR(-ENOMEM);
3326
3327 kref_init(&driver->kref);
3328 driver->num = lines;
3329 driver->owner = owner;
3330 driver->flags = flags;
3331
3332 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3333 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3334 GFP_KERNEL);
3335 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3336 GFP_KERNEL);
3337 if (!driver->ttys || !driver->termios) {
3338 err = -ENOMEM;
3339 goto err_free_all;
3340 }
3341 }
3342
3343 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3344 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3345 GFP_KERNEL);
3346 if (!driver->ports) {
3347 err = -ENOMEM;
3348 goto err_free_all;
3349 }
3350 cdevs = lines;
3351 }
3352
3353 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3354 if (!driver->cdevs) {
3355 err = -ENOMEM;
3356 goto err_free_all;
3357 }
3358
3359 return driver;
3360err_free_all:
3361 kfree(driver->ports);
3362 kfree(driver->ttys);
3363 kfree(driver->termios);
3364 kfree(driver->cdevs);
3365 kfree(driver);
3366 return ERR_PTR(err);
3367}
3368EXPORT_SYMBOL(__tty_alloc_driver);
3369
3370static void destruct_tty_driver(struct kref *kref)
3371{
3372 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3373 int i;
3374 struct ktermios *tp;
3375
3376 if (driver->flags & TTY_DRIVER_INSTALLED) {
3377 for (i = 0; i < driver->num; i++) {
3378 tp = driver->termios[i];
3379 if (tp) {
3380 driver->termios[i] = NULL;
3381 kfree(tp);
3382 }
3383 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3384 tty_unregister_device(driver, i);
3385 }
3386 proc_tty_unregister_driver(driver);
3387 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3388 cdev_del(driver->cdevs[0]);
3389 }
3390 kfree(driver->cdevs);
3391 kfree(driver->ports);
3392 kfree(driver->termios);
3393 kfree(driver->ttys);
3394 kfree(driver);
3395}
3396
3397/**
3398 * tty_driver_kref_put -- drop a reference to a tty driver
3399 * @driver: driver of which to drop the reference
3400 *
3401 * The final put will destroy and free up the driver.
3402 */
3403void tty_driver_kref_put(struct tty_driver *driver)
3404{
3405 kref_put(&driver->kref, destruct_tty_driver);
3406}
3407EXPORT_SYMBOL(tty_driver_kref_put);
3408
3409/**
3410 * tty_register_driver -- register a tty driver
3411 * @driver: driver to register
3412 *
3413 * Called by a tty driver to register itself.
3414 */
3415int tty_register_driver(struct tty_driver *driver)
3416{
3417 int error;
3418 int i;
3419 dev_t dev;
3420 struct device *d;
3421
3422 if (!driver->major) {
3423 error = alloc_chrdev_region(&dev, driver->minor_start,
3424 driver->num, driver->name);
3425 if (!error) {
3426 driver->major = MAJOR(dev);
3427 driver->minor_start = MINOR(dev);
3428 }
3429 } else {
3430 dev = MKDEV(driver->major, driver->minor_start);
3431 error = register_chrdev_region(dev, driver->num, driver->name);
3432 }
3433 if (error < 0)
3434 goto err;
3435
3436 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3437 error = tty_cdev_add(driver, dev, 0, driver->num);
3438 if (error)
3439 goto err_unreg_char;
3440 }
3441
3442 mutex_lock(&tty_mutex);
3443 list_add(&driver->tty_drivers, &tty_drivers);
3444 mutex_unlock(&tty_mutex);
3445
3446 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3447 for (i = 0; i < driver->num; i++) {
3448 d = tty_register_device(driver, i, NULL);
3449 if (IS_ERR(d)) {
3450 error = PTR_ERR(d);
3451 goto err_unreg_devs;
3452 }
3453 }
3454 }
3455 proc_tty_register_driver(driver);
3456 driver->flags |= TTY_DRIVER_INSTALLED;
3457 return 0;
3458
3459err_unreg_devs:
3460 for (i--; i >= 0; i--)
3461 tty_unregister_device(driver, i);
3462
3463 mutex_lock(&tty_mutex);
3464 list_del(&driver->tty_drivers);
3465 mutex_unlock(&tty_mutex);
3466
3467err_unreg_char:
3468 unregister_chrdev_region(dev, driver->num);
3469err:
3470 return error;
3471}
3472EXPORT_SYMBOL(tty_register_driver);
3473
3474/**
3475 * tty_unregister_driver -- unregister a tty driver
3476 * @driver: driver to unregister
3477 *
3478 * Called by a tty driver to unregister itself.
3479 */
3480void tty_unregister_driver(struct tty_driver *driver)
3481{
3482 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3483 driver->num);
3484 mutex_lock(&tty_mutex);
3485 list_del(&driver->tty_drivers);
3486 mutex_unlock(&tty_mutex);
3487}
3488EXPORT_SYMBOL(tty_unregister_driver);
3489
3490dev_t tty_devnum(struct tty_struct *tty)
3491{
3492 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3493}
3494EXPORT_SYMBOL(tty_devnum);
3495
3496void tty_default_fops(struct file_operations *fops)
3497{
3498 *fops = tty_fops;
3499}
3500
3501static char *tty_devnode(const struct device *dev, umode_t *mode)
3502{
3503 if (!mode)
3504 return NULL;
3505 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3506 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3507 *mode = 0666;
3508 return NULL;
3509}
3510
3511static int __init tty_class_init(void)
3512{
3513 tty_class = class_create(THIS_MODULE, "tty");
3514 if (IS_ERR(tty_class))
3515 return PTR_ERR(tty_class);
3516 tty_class->devnode = tty_devnode;
3517 return 0;
3518}
3519
3520postcore_initcall(tty_class_init);
3521
3522/* 3/2004 jmc: why do these devices exist? */
3523static struct cdev tty_cdev, console_cdev;
3524
3525static ssize_t show_cons_active(struct device *dev,
3526 struct device_attribute *attr, char *buf)
3527{
3528 struct console *cs[16];
3529 int i = 0;
3530 struct console *c;
3531 ssize_t count = 0;
3532
3533 /*
3534 * Hold the console_list_lock to guarantee that no consoles are
3535 * unregistered until all console processing is complete.
3536 * This also allows safe traversal of the console list and
3537 * race-free reading of @flags.
3538 */
3539 console_list_lock();
3540
3541 for_each_console(c) {
3542 if (!c->device)
3543 continue;
3544 if (!c->write)
3545 continue;
3546 if ((c->flags & CON_ENABLED) == 0)
3547 continue;
3548 cs[i++] = c;
3549 if (i >= ARRAY_SIZE(cs))
3550 break;
3551 }
3552
3553 /*
3554 * Take console_lock to serialize device() callback with
3555 * other console operations. For example, fg_console is
3556 * modified under console_lock when switching vt.
3557 */
3558 console_lock();
3559 while (i--) {
3560 int index = cs[i]->index;
3561 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3562
3563 /* don't resolve tty0 as some programs depend on it */
3564 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3565 count += tty_line_name(drv, index, buf + count);
3566 else
3567 count += sprintf(buf + count, "%s%d",
3568 cs[i]->name, cs[i]->index);
3569
3570 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3571 }
3572 console_unlock();
3573
3574 console_list_unlock();
3575
3576 return count;
3577}
3578static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3579
3580static struct attribute *cons_dev_attrs[] = {
3581 &dev_attr_active.attr,
3582 NULL
3583};
3584
3585ATTRIBUTE_GROUPS(cons_dev);
3586
3587static struct device *consdev;
3588
3589void console_sysfs_notify(void)
3590{
3591 if (consdev)
3592 sysfs_notify(&consdev->kobj, NULL, "active");
3593}
3594
3595static struct ctl_table tty_table[] = {
3596 {
3597 .procname = "legacy_tiocsti",
3598 .data = &tty_legacy_tiocsti,
3599 .maxlen = sizeof(tty_legacy_tiocsti),
3600 .mode = 0644,
3601 .proc_handler = proc_dobool,
3602 },
3603 {
3604 .procname = "ldisc_autoload",
3605 .data = &tty_ldisc_autoload,
3606 .maxlen = sizeof(tty_ldisc_autoload),
3607 .mode = 0644,
3608 .proc_handler = proc_dointvec,
3609 .extra1 = SYSCTL_ZERO,
3610 .extra2 = SYSCTL_ONE,
3611 },
3612 { }
3613};
3614
3615static struct ctl_table tty_dir_table[] = {
3616 {
3617 .procname = "tty",
3618 .mode = 0555,
3619 .child = tty_table,
3620 },
3621 { }
3622};
3623
3624static struct ctl_table tty_root_table[] = {
3625 {
3626 .procname = "dev",
3627 .mode = 0555,
3628 .child = tty_dir_table,
3629 },
3630 { }
3631};
3632
3633/*
3634 * Ok, now we can initialize the rest of the tty devices and can count
3635 * on memory allocations, interrupts etc..
3636 */
3637int __init tty_init(void)
3638{
3639 register_sysctl_table(tty_root_table);
3640 cdev_init(&tty_cdev, &tty_fops);
3641 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3642 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3643 panic("Couldn't register /dev/tty driver\n");
3644 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3645
3646 cdev_init(&console_cdev, &console_fops);
3647 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3648 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3649 panic("Couldn't register /dev/console driver\n");
3650 consdev = device_create_with_groups(tty_class, NULL,
3651 MKDEV(TTYAUX_MAJOR, 1), NULL,
3652 cons_dev_groups, "console");
3653 if (IS_ERR(consdev))
3654 consdev = NULL;
3655
3656#ifdef CONFIG_VT
3657 vty_init(&console_fops);
3658#endif
3659 return 0;
3660}