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1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 */
4
5/*
6 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
7 * or rs-channels. It also implements echoing, cooked mode etc.
8 *
9 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
10 *
11 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
12 * tty_struct and tty_queue structures. Previously there was an array
13 * of 256 tty_struct's which was statically allocated, and the
14 * tty_queue structures were allocated at boot time. Both are now
15 * dynamically allocated only when the tty is open.
16 *
17 * Also restructured routines so that there is more of a separation
18 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
19 * the low-level tty routines (serial.c, pty.c, console.c). This
20 * makes for cleaner and more compact code. -TYT, 9/17/92
21 *
22 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
23 * which can be dynamically activated and de-activated by the line
24 * discipline handling modules (like SLIP).
25 *
26 * NOTE: pay no attention to the line discipline code (yet); its
27 * interface is still subject to change in this version...
28 * -- TYT, 1/31/92
29 *
30 * Added functionality to the OPOST tty handling. No delays, but all
31 * other bits should be there.
32 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
33 *
34 * Rewrote canonical mode and added more termios flags.
35 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
36 *
37 * Reorganized FASYNC support so mouse code can share it.
38 * -- ctm@ardi.com, 9Sep95
39 *
40 * New TIOCLINUX variants added.
41 * -- mj@k332.feld.cvut.cz, 19-Nov-95
42 *
43 * Restrict vt switching via ioctl()
44 * -- grif@cs.ucr.edu, 5-Dec-95
45 *
46 * Move console and virtual terminal code to more appropriate files,
47 * implement CONFIG_VT and generalize console device interface.
48 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
49 *
50 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
51 * -- Bill Hawes <whawes@star.net>, June 97
52 *
53 * Added devfs support.
54 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
55 *
56 * Added support for a Unix98-style ptmx device.
57 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
58 *
59 * Reduced memory usage for older ARM systems
60 * -- Russell King <rmk@arm.linux.org.uk>
61 *
62 * Move do_SAK() into process context. Less stack use in devfs functions.
63 * alloc_tty_struct() always uses kmalloc()
64 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
65 */
66
67#include <linux/types.h>
68#include <linux/major.h>
69#include <linux/errno.h>
70#include <linux/signal.h>
71#include <linux/fcntl.h>
72#include <linux/sched.h>
73#include <linux/interrupt.h>
74#include <linux/tty.h>
75#include <linux/tty_driver.h>
76#include <linux/tty_flip.h>
77#include <linux/devpts_fs.h>
78#include <linux/file.h>
79#include <linux/fdtable.h>
80#include <linux/console.h>
81#include <linux/timer.h>
82#include <linux/ctype.h>
83#include <linux/kd.h>
84#include <linux/mm.h>
85#include <linux/string.h>
86#include <linux/slab.h>
87#include <linux/poll.h>
88#include <linux/proc_fs.h>
89#include <linux/init.h>
90#include <linux/module.h>
91#include <linux/device.h>
92#include <linux/wait.h>
93#include <linux/bitops.h>
94#include <linux/delay.h>
95#include <linux/seq_file.h>
96#include <linux/serial.h>
97#include <linux/ratelimit.h>
98
99#include <linux/uaccess.h>
100#include <asm/system.h>
101
102#include <linux/kbd_kern.h>
103#include <linux/vt_kern.h>
104#include <linux/selection.h>
105
106#include <linux/kmod.h>
107#include <linux/nsproxy.h>
108
109#undef TTY_DEBUG_HANGUP
110
111#define TTY_PARANOIA_CHECK 1
112#define CHECK_TTY_COUNT 1
113
114struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
115 .c_iflag = ICRNL | IXON,
116 .c_oflag = OPOST | ONLCR,
117 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
118 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
119 ECHOCTL | ECHOKE | IEXTEN,
120 .c_cc = INIT_C_CC,
121 .c_ispeed = 38400,
122 .c_ospeed = 38400
123};
124
125EXPORT_SYMBOL(tty_std_termios);
126
127/* This list gets poked at by procfs and various bits of boot up code. This
128 could do with some rationalisation such as pulling the tty proc function
129 into this file */
130
131LIST_HEAD(tty_drivers); /* linked list of tty drivers */
132
133/* Mutex to protect creating and releasing a tty. This is shared with
134 vt.c for deeply disgusting hack reasons */
135DEFINE_MUTEX(tty_mutex);
136EXPORT_SYMBOL(tty_mutex);
137
138/* Spinlock to protect the tty->tty_files list */
139DEFINE_SPINLOCK(tty_files_lock);
140
141static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
142static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
143ssize_t redirected_tty_write(struct file *, const char __user *,
144 size_t, loff_t *);
145static unsigned int tty_poll(struct file *, poll_table *);
146static int tty_open(struct inode *, struct file *);
147long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
148#ifdef CONFIG_COMPAT
149static long tty_compat_ioctl(struct file *file, unsigned int cmd,
150 unsigned long arg);
151#else
152#define tty_compat_ioctl NULL
153#endif
154static int __tty_fasync(int fd, struct file *filp, int on);
155static int tty_fasync(int fd, struct file *filp, int on);
156static void release_tty(struct tty_struct *tty, int idx);
157static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
158static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
159
160/**
161 * alloc_tty_struct - allocate a tty object
162 *
163 * Return a new empty tty structure. The data fields have not
164 * been initialized in any way but has been zeroed
165 *
166 * Locking: none
167 */
168
169struct tty_struct *alloc_tty_struct(void)
170{
171 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
172}
173
174/**
175 * free_tty_struct - free a disused tty
176 * @tty: tty struct to free
177 *
178 * Free the write buffers, tty queue and tty memory itself.
179 *
180 * Locking: none. Must be called after tty is definitely unused
181 */
182
183void free_tty_struct(struct tty_struct *tty)
184{
185 if (tty->dev)
186 put_device(tty->dev);
187 kfree(tty->write_buf);
188 tty_buffer_free_all(tty);
189 kfree(tty);
190}
191
192static inline struct tty_struct *file_tty(struct file *file)
193{
194 return ((struct tty_file_private *)file->private_data)->tty;
195}
196
197/* Associate a new file with the tty structure */
198int tty_add_file(struct tty_struct *tty, struct file *file)
199{
200 struct tty_file_private *priv;
201
202 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
203 if (!priv)
204 return -ENOMEM;
205
206 priv->tty = tty;
207 priv->file = file;
208 file->private_data = priv;
209
210 spin_lock(&tty_files_lock);
211 list_add(&priv->list, &tty->tty_files);
212 spin_unlock(&tty_files_lock);
213
214 return 0;
215}
216
217/* Delete file from its tty */
218void tty_del_file(struct file *file)
219{
220 struct tty_file_private *priv = file->private_data;
221
222 spin_lock(&tty_files_lock);
223 list_del(&priv->list);
224 spin_unlock(&tty_files_lock);
225 file->private_data = NULL;
226 kfree(priv);
227}
228
229
230#define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
231
232/**
233 * tty_name - return tty naming
234 * @tty: tty structure
235 * @buf: buffer for output
236 *
237 * Convert a tty structure into a name. The name reflects the kernel
238 * naming policy and if udev is in use may not reflect user space
239 *
240 * Locking: none
241 */
242
243char *tty_name(struct tty_struct *tty, char *buf)
244{
245 if (!tty) /* Hmm. NULL pointer. That's fun. */
246 strcpy(buf, "NULL tty");
247 else
248 strcpy(buf, tty->name);
249 return buf;
250}
251
252EXPORT_SYMBOL(tty_name);
253
254int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
255 const char *routine)
256{
257#ifdef TTY_PARANOIA_CHECK
258 if (!tty) {
259 printk(KERN_WARNING
260 "null TTY for (%d:%d) in %s\n",
261 imajor(inode), iminor(inode), routine);
262 return 1;
263 }
264 if (tty->magic != TTY_MAGIC) {
265 printk(KERN_WARNING
266 "bad magic number for tty struct (%d:%d) in %s\n",
267 imajor(inode), iminor(inode), routine);
268 return 1;
269 }
270#endif
271 return 0;
272}
273
274static int check_tty_count(struct tty_struct *tty, const char *routine)
275{
276#ifdef CHECK_TTY_COUNT
277 struct list_head *p;
278 int count = 0;
279
280 spin_lock(&tty_files_lock);
281 list_for_each(p, &tty->tty_files) {
282 count++;
283 }
284 spin_unlock(&tty_files_lock);
285 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
286 tty->driver->subtype == PTY_TYPE_SLAVE &&
287 tty->link && tty->link->count)
288 count++;
289 if (tty->count != count) {
290 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
291 "!= #fd's(%d) in %s\n",
292 tty->name, tty->count, count, routine);
293 return count;
294 }
295#endif
296 return 0;
297}
298
299/**
300 * get_tty_driver - find device of a tty
301 * @dev_t: device identifier
302 * @index: returns the index of the tty
303 *
304 * This routine returns a tty driver structure, given a device number
305 * and also passes back the index number.
306 *
307 * Locking: caller must hold tty_mutex
308 */
309
310static struct tty_driver *get_tty_driver(dev_t device, int *index)
311{
312 struct tty_driver *p;
313
314 list_for_each_entry(p, &tty_drivers, tty_drivers) {
315 dev_t base = MKDEV(p->major, p->minor_start);
316 if (device < base || device >= base + p->num)
317 continue;
318 *index = device - base;
319 return tty_driver_kref_get(p);
320 }
321 return NULL;
322}
323
324#ifdef CONFIG_CONSOLE_POLL
325
326/**
327 * tty_find_polling_driver - find device of a polled tty
328 * @name: name string to match
329 * @line: pointer to resulting tty line nr
330 *
331 * This routine returns a tty driver structure, given a name
332 * and the condition that the tty driver is capable of polled
333 * operation.
334 */
335struct tty_driver *tty_find_polling_driver(char *name, int *line)
336{
337 struct tty_driver *p, *res = NULL;
338 int tty_line = 0;
339 int len;
340 char *str, *stp;
341
342 for (str = name; *str; str++)
343 if ((*str >= '0' && *str <= '9') || *str == ',')
344 break;
345 if (!*str)
346 return NULL;
347
348 len = str - name;
349 tty_line = simple_strtoul(str, &str, 10);
350
351 mutex_lock(&tty_mutex);
352 /* Search through the tty devices to look for a match */
353 list_for_each_entry(p, &tty_drivers, tty_drivers) {
354 if (strncmp(name, p->name, len) != 0)
355 continue;
356 stp = str;
357 if (*stp == ',')
358 stp++;
359 if (*stp == '\0')
360 stp = NULL;
361
362 if (tty_line >= 0 && tty_line < p->num && p->ops &&
363 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
364 res = tty_driver_kref_get(p);
365 *line = tty_line;
366 break;
367 }
368 }
369 mutex_unlock(&tty_mutex);
370
371 return res;
372}
373EXPORT_SYMBOL_GPL(tty_find_polling_driver);
374#endif
375
376/**
377 * tty_check_change - check for POSIX terminal changes
378 * @tty: tty to check
379 *
380 * If we try to write to, or set the state of, a terminal and we're
381 * not in the foreground, send a SIGTTOU. If the signal is blocked or
382 * ignored, go ahead and perform the operation. (POSIX 7.2)
383 *
384 * Locking: ctrl_lock
385 */
386
387int tty_check_change(struct tty_struct *tty)
388{
389 unsigned long flags;
390 int ret = 0;
391
392 if (current->signal->tty != tty)
393 return 0;
394
395 spin_lock_irqsave(&tty->ctrl_lock, flags);
396
397 if (!tty->pgrp) {
398 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
399 goto out_unlock;
400 }
401 if (task_pgrp(current) == tty->pgrp)
402 goto out_unlock;
403 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
404 if (is_ignored(SIGTTOU))
405 goto out;
406 if (is_current_pgrp_orphaned()) {
407 ret = -EIO;
408 goto out;
409 }
410 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
411 set_thread_flag(TIF_SIGPENDING);
412 ret = -ERESTARTSYS;
413out:
414 return ret;
415out_unlock:
416 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
417 return ret;
418}
419
420EXPORT_SYMBOL(tty_check_change);
421
422static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
423 size_t count, loff_t *ppos)
424{
425 return 0;
426}
427
428static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
429 size_t count, loff_t *ppos)
430{
431 return -EIO;
432}
433
434/* No kernel lock held - none needed ;) */
435static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
436{
437 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
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 const struct file_operations tty_fops = {
453 .llseek = no_llseek,
454 .read = tty_read,
455 .write = tty_write,
456 .poll = tty_poll,
457 .unlocked_ioctl = tty_ioctl,
458 .compat_ioctl = tty_compat_ioctl,
459 .open = tty_open,
460 .release = tty_release,
461 .fasync = tty_fasync,
462};
463
464static const struct file_operations console_fops = {
465 .llseek = no_llseek,
466 .read = tty_read,
467 .write = redirected_tty_write,
468 .poll = tty_poll,
469 .unlocked_ioctl = tty_ioctl,
470 .compat_ioctl = tty_compat_ioctl,
471 .open = tty_open,
472 .release = tty_release,
473 .fasync = tty_fasync,
474};
475
476static const struct file_operations hung_up_tty_fops = {
477 .llseek = no_llseek,
478 .read = hung_up_tty_read,
479 .write = hung_up_tty_write,
480 .poll = hung_up_tty_poll,
481 .unlocked_ioctl = hung_up_tty_ioctl,
482 .compat_ioctl = hung_up_tty_compat_ioctl,
483 .release = tty_release,
484};
485
486static DEFINE_SPINLOCK(redirect_lock);
487static struct file *redirect;
488
489/**
490 * tty_wakeup - request more data
491 * @tty: terminal
492 *
493 * Internal and external helper for wakeups of tty. This function
494 * informs the line discipline if present that the driver is ready
495 * to receive more output data.
496 */
497
498void tty_wakeup(struct tty_struct *tty)
499{
500 struct tty_ldisc *ld;
501
502 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
503 ld = tty_ldisc_ref(tty);
504 if (ld) {
505 if (ld->ops->write_wakeup)
506 ld->ops->write_wakeup(tty);
507 tty_ldisc_deref(ld);
508 }
509 }
510 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
511}
512
513EXPORT_SYMBOL_GPL(tty_wakeup);
514
515/**
516 * __tty_hangup - actual handler for hangup events
517 * @work: tty device
518 *
519 * This can be called by the "eventd" kernel thread. That is process
520 * synchronous but doesn't hold any locks, so we need to make sure we
521 * have the appropriate locks for what we're doing.
522 *
523 * The hangup event clears any pending redirections onto the hung up
524 * device. It ensures future writes will error and it does the needed
525 * line discipline hangup and signal delivery. The tty object itself
526 * remains intact.
527 *
528 * Locking:
529 * BTM
530 * redirect lock for undoing redirection
531 * file list lock for manipulating list of ttys
532 * tty_ldisc_lock from called functions
533 * termios_mutex resetting termios data
534 * tasklist_lock to walk task list for hangup event
535 * ->siglock to protect ->signal/->sighand
536 */
537void __tty_hangup(struct tty_struct *tty)
538{
539 struct file *cons_filp = NULL;
540 struct file *filp, *f = NULL;
541 struct task_struct *p;
542 struct tty_file_private *priv;
543 int closecount = 0, n;
544 unsigned long flags;
545 int refs = 0;
546
547 if (!tty)
548 return;
549
550
551 spin_lock(&redirect_lock);
552 if (redirect && file_tty(redirect) == tty) {
553 f = redirect;
554 redirect = NULL;
555 }
556 spin_unlock(&redirect_lock);
557
558 tty_lock();
559
560 /* some functions below drop BTM, so we need this bit */
561 set_bit(TTY_HUPPING, &tty->flags);
562
563 /* inuse_filps is protected by the single tty lock,
564 this really needs to change if we want to flush the
565 workqueue with the lock held */
566 check_tty_count(tty, "tty_hangup");
567
568 spin_lock(&tty_files_lock);
569 /* This breaks for file handles being sent over AF_UNIX sockets ? */
570 list_for_each_entry(priv, &tty->tty_files, list) {
571 filp = priv->file;
572 if (filp->f_op->write == redirected_tty_write)
573 cons_filp = filp;
574 if (filp->f_op->write != tty_write)
575 continue;
576 closecount++;
577 __tty_fasync(-1, filp, 0); /* can't block */
578 filp->f_op = &hung_up_tty_fops;
579 }
580 spin_unlock(&tty_files_lock);
581
582 /*
583 * it drops BTM and thus races with reopen
584 * we protect the race by TTY_HUPPING
585 */
586 tty_ldisc_hangup(tty);
587
588 read_lock(&tasklist_lock);
589 if (tty->session) {
590 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
591 spin_lock_irq(&p->sighand->siglock);
592 if (p->signal->tty == tty) {
593 p->signal->tty = NULL;
594 /* We defer the dereferences outside fo
595 the tasklist lock */
596 refs++;
597 }
598 if (!p->signal->leader) {
599 spin_unlock_irq(&p->sighand->siglock);
600 continue;
601 }
602 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
603 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
604 put_pid(p->signal->tty_old_pgrp); /* A noop */
605 spin_lock_irqsave(&tty->ctrl_lock, flags);
606 if (tty->pgrp)
607 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
608 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
609 spin_unlock_irq(&p->sighand->siglock);
610 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
611 }
612 read_unlock(&tasklist_lock);
613
614 spin_lock_irqsave(&tty->ctrl_lock, flags);
615 clear_bit(TTY_THROTTLED, &tty->flags);
616 clear_bit(TTY_PUSH, &tty->flags);
617 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
618 put_pid(tty->session);
619 put_pid(tty->pgrp);
620 tty->session = NULL;
621 tty->pgrp = NULL;
622 tty->ctrl_status = 0;
623 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
624
625 /* Account for the p->signal references we killed */
626 while (refs--)
627 tty_kref_put(tty);
628
629 /*
630 * If one of the devices matches a console pointer, we
631 * cannot just call hangup() because that will cause
632 * tty->count and state->count to go out of sync.
633 * So we just call close() the right number of times.
634 */
635 if (cons_filp) {
636 if (tty->ops->close)
637 for (n = 0; n < closecount; n++)
638 tty->ops->close(tty, cons_filp);
639 } else if (tty->ops->hangup)
640 (tty->ops->hangup)(tty);
641 /*
642 * We don't want to have driver/ldisc interactions beyond
643 * the ones we did here. The driver layer expects no
644 * calls after ->hangup() from the ldisc side. However we
645 * can't yet guarantee all that.
646 */
647 set_bit(TTY_HUPPED, &tty->flags);
648 clear_bit(TTY_HUPPING, &tty->flags);
649 tty_ldisc_enable(tty);
650
651 tty_unlock();
652
653 if (f)
654 fput(f);
655}
656
657static void do_tty_hangup(struct work_struct *work)
658{
659 struct tty_struct *tty =
660 container_of(work, struct tty_struct, hangup_work);
661
662 __tty_hangup(tty);
663}
664
665/**
666 * tty_hangup - trigger a hangup event
667 * @tty: tty to hangup
668 *
669 * A carrier loss (virtual or otherwise) has occurred on this like
670 * schedule a hangup sequence to run after this event.
671 */
672
673void tty_hangup(struct tty_struct *tty)
674{
675#ifdef TTY_DEBUG_HANGUP
676 char buf[64];
677 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
678#endif
679 schedule_work(&tty->hangup_work);
680}
681
682EXPORT_SYMBOL(tty_hangup);
683
684/**
685 * tty_vhangup - process vhangup
686 * @tty: tty to hangup
687 *
688 * The user has asked via system call for the terminal to be hung up.
689 * We do this synchronously so that when the syscall returns the process
690 * is complete. That guarantee is necessary for security reasons.
691 */
692
693void tty_vhangup(struct tty_struct *tty)
694{
695#ifdef TTY_DEBUG_HANGUP
696 char buf[64];
697
698 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
699#endif
700 __tty_hangup(tty);
701}
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 */
711
712void tty_vhangup_self(void)
713{
714 struct tty_struct *tty;
715
716 tty = get_current_tty();
717 if (tty) {
718 tty_vhangup(tty);
719 tty_kref_put(tty);
720 }
721}
722
723/**
724 * tty_hung_up_p - was tty hung up
725 * @filp: file pointer of tty
726 *
727 * Return true if the tty has been subject to a vhangup or a carrier
728 * loss
729 */
730
731int tty_hung_up_p(struct file *filp)
732{
733 return (filp->f_op == &hung_up_tty_fops);
734}
735
736EXPORT_SYMBOL(tty_hung_up_p);
737
738static void session_clear_tty(struct pid *session)
739{
740 struct task_struct *p;
741 do_each_pid_task(session, PIDTYPE_SID, p) {
742 proc_clear_tty(p);
743 } while_each_pid_task(session, PIDTYPE_SID, p);
744}
745
746/**
747 * disassociate_ctty - disconnect controlling tty
748 * @on_exit: true if exiting so need to "hang up" the session
749 *
750 * This function is typically called only by the session leader, when
751 * it wants to disassociate itself from its controlling tty.
752 *
753 * It performs the following functions:
754 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
755 * (2) Clears the tty from being controlling the session
756 * (3) Clears the controlling tty for all processes in the
757 * session group.
758 *
759 * The argument on_exit is set to 1 if called when a process is
760 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
761 *
762 * Locking:
763 * BTM is taken for hysterical raisins, and held when
764 * called from no_tty().
765 * tty_mutex is taken to protect tty
766 * ->siglock is taken to protect ->signal/->sighand
767 * tasklist_lock is taken to walk process list for sessions
768 * ->siglock is taken to protect ->signal/->sighand
769 */
770
771void disassociate_ctty(int on_exit)
772{
773 struct tty_struct *tty;
774 struct pid *tty_pgrp = NULL;
775
776 if (!current->signal->leader)
777 return;
778
779 tty = get_current_tty();
780 if (tty) {
781 tty_pgrp = get_pid(tty->pgrp);
782 if (on_exit) {
783 if (tty->driver->type != TTY_DRIVER_TYPE_PTY)
784 tty_vhangup(tty);
785 }
786 tty_kref_put(tty);
787 } else if (on_exit) {
788 struct pid *old_pgrp;
789 spin_lock_irq(¤t->sighand->siglock);
790 old_pgrp = current->signal->tty_old_pgrp;
791 current->signal->tty_old_pgrp = NULL;
792 spin_unlock_irq(¤t->sighand->siglock);
793 if (old_pgrp) {
794 kill_pgrp(old_pgrp, SIGHUP, on_exit);
795 kill_pgrp(old_pgrp, SIGCONT, on_exit);
796 put_pid(old_pgrp);
797 }
798 return;
799 }
800 if (tty_pgrp) {
801 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
802 if (!on_exit)
803 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
804 put_pid(tty_pgrp);
805 }
806
807 spin_lock_irq(¤t->sighand->siglock);
808 put_pid(current->signal->tty_old_pgrp);
809 current->signal->tty_old_pgrp = NULL;
810 spin_unlock_irq(¤t->sighand->siglock);
811
812 tty = get_current_tty();
813 if (tty) {
814 unsigned long flags;
815 spin_lock_irqsave(&tty->ctrl_lock, flags);
816 put_pid(tty->session);
817 put_pid(tty->pgrp);
818 tty->session = NULL;
819 tty->pgrp = NULL;
820 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
821 tty_kref_put(tty);
822 } else {
823#ifdef TTY_DEBUG_HANGUP
824 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
825 " = NULL", tty);
826#endif
827 }
828
829 /* Now clear signal->tty under the lock */
830 read_lock(&tasklist_lock);
831 session_clear_tty(task_session(current));
832 read_unlock(&tasklist_lock);
833}
834
835/**
836 *
837 * no_tty - Ensure the current process does not have a controlling tty
838 */
839void no_tty(void)
840{
841 struct task_struct *tsk = current;
842 tty_lock();
843 disassociate_ctty(0);
844 tty_unlock();
845 proc_clear_tty(tsk);
846}
847
848
849/**
850 * stop_tty - propagate flow control
851 * @tty: tty to stop
852 *
853 * Perform flow control to the driver. For PTY/TTY pairs we
854 * must also propagate the TIOCKPKT status. May be called
855 * on an already stopped device and will not re-call the driver
856 * method.
857 *
858 * This functionality is used by both the line disciplines for
859 * halting incoming flow and by the driver. It may therefore be
860 * called from any context, may be under the tty atomic_write_lock
861 * but not always.
862 *
863 * Locking:
864 * Uses the tty control lock internally
865 */
866
867void stop_tty(struct tty_struct *tty)
868{
869 unsigned long flags;
870 spin_lock_irqsave(&tty->ctrl_lock, flags);
871 if (tty->stopped) {
872 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
873 return;
874 }
875 tty->stopped = 1;
876 if (tty->link && tty->link->packet) {
877 tty->ctrl_status &= ~TIOCPKT_START;
878 tty->ctrl_status |= TIOCPKT_STOP;
879 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
880 }
881 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
882 if (tty->ops->stop)
883 (tty->ops->stop)(tty);
884}
885
886EXPORT_SYMBOL(stop_tty);
887
888/**
889 * start_tty - propagate flow control
890 * @tty: tty to start
891 *
892 * Start a tty that has been stopped if at all possible. Perform
893 * any necessary wakeups and propagate the TIOCPKT status. If this
894 * is the tty was previous stopped and is being started then the
895 * driver start method is invoked and the line discipline woken.
896 *
897 * Locking:
898 * ctrl_lock
899 */
900
901void start_tty(struct tty_struct *tty)
902{
903 unsigned long flags;
904 spin_lock_irqsave(&tty->ctrl_lock, flags);
905 if (!tty->stopped || tty->flow_stopped) {
906 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
907 return;
908 }
909 tty->stopped = 0;
910 if (tty->link && tty->link->packet) {
911 tty->ctrl_status &= ~TIOCPKT_STOP;
912 tty->ctrl_status |= TIOCPKT_START;
913 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
914 }
915 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
916 if (tty->ops->start)
917 (tty->ops->start)(tty);
918 /* If we have a running line discipline it may need kicking */
919 tty_wakeup(tty);
920}
921
922EXPORT_SYMBOL(start_tty);
923
924/**
925 * tty_read - read method for tty device files
926 * @file: pointer to tty file
927 * @buf: user buffer
928 * @count: size of user buffer
929 * @ppos: unused
930 *
931 * Perform the read system call function on this terminal device. Checks
932 * for hung up devices before calling the line discipline method.
933 *
934 * Locking:
935 * Locks the line discipline internally while needed. Multiple
936 * read calls may be outstanding in parallel.
937 */
938
939static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
940 loff_t *ppos)
941{
942 int i;
943 struct inode *inode = file->f_path.dentry->d_inode;
944 struct tty_struct *tty = file_tty(file);
945 struct tty_ldisc *ld;
946
947 if (tty_paranoia_check(tty, inode, "tty_read"))
948 return -EIO;
949 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
950 return -EIO;
951
952 /* We want to wait for the line discipline to sort out in this
953 situation */
954 ld = tty_ldisc_ref_wait(tty);
955 if (ld->ops->read)
956 i = (ld->ops->read)(tty, file, buf, count);
957 else
958 i = -EIO;
959 tty_ldisc_deref(ld);
960 if (i > 0)
961 inode->i_atime = current_fs_time(inode->i_sb);
962 return i;
963}
964
965void tty_write_unlock(struct tty_struct *tty)
966 __releases(&tty->atomic_write_lock)
967{
968 mutex_unlock(&tty->atomic_write_lock);
969 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
970}
971
972int tty_write_lock(struct tty_struct *tty, int ndelay)
973 __acquires(&tty->atomic_write_lock)
974{
975 if (!mutex_trylock(&tty->atomic_write_lock)) {
976 if (ndelay)
977 return -EAGAIN;
978 if (mutex_lock_interruptible(&tty->atomic_write_lock))
979 return -ERESTARTSYS;
980 }
981 return 0;
982}
983
984/*
985 * Split writes up in sane blocksizes to avoid
986 * denial-of-service type attacks
987 */
988static inline ssize_t do_tty_write(
989 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
990 struct tty_struct *tty,
991 struct file *file,
992 const char __user *buf,
993 size_t count)
994{
995 ssize_t ret, written = 0;
996 unsigned int chunk;
997
998 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
999 if (ret < 0)
1000 return ret;
1001
1002 /*
1003 * We chunk up writes into a temporary buffer. This
1004 * simplifies low-level drivers immensely, since they
1005 * don't have locking issues and user mode accesses.
1006 *
1007 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1008 * big chunk-size..
1009 *
1010 * The default chunk-size is 2kB, because the NTTY
1011 * layer has problems with bigger chunks. It will
1012 * claim to be able to handle more characters than
1013 * it actually does.
1014 *
1015 * FIXME: This can probably go away now except that 64K chunks
1016 * are too likely to fail unless switched to vmalloc...
1017 */
1018 chunk = 2048;
1019 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1020 chunk = 65536;
1021 if (count < chunk)
1022 chunk = count;
1023
1024 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1025 if (tty->write_cnt < chunk) {
1026 unsigned char *buf_chunk;
1027
1028 if (chunk < 1024)
1029 chunk = 1024;
1030
1031 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1032 if (!buf_chunk) {
1033 ret = -ENOMEM;
1034 goto out;
1035 }
1036 kfree(tty->write_buf);
1037 tty->write_cnt = chunk;
1038 tty->write_buf = buf_chunk;
1039 }
1040
1041 /* Do the write .. */
1042 for (;;) {
1043 size_t size = count;
1044 if (size > chunk)
1045 size = chunk;
1046 ret = -EFAULT;
1047 if (copy_from_user(tty->write_buf, buf, size))
1048 break;
1049 ret = write(tty, file, tty->write_buf, size);
1050 if (ret <= 0)
1051 break;
1052 written += ret;
1053 buf += ret;
1054 count -= ret;
1055 if (!count)
1056 break;
1057 ret = -ERESTARTSYS;
1058 if (signal_pending(current))
1059 break;
1060 cond_resched();
1061 }
1062 if (written) {
1063 struct inode *inode = file->f_path.dentry->d_inode;
1064 inode->i_mtime = current_fs_time(inode->i_sb);
1065 ret = written;
1066 }
1067out:
1068 tty_write_unlock(tty);
1069 return ret;
1070}
1071
1072/**
1073 * tty_write_message - write a message to a certain tty, not just the console.
1074 * @tty: the destination tty_struct
1075 * @msg: the message to write
1076 *
1077 * This is used for messages that need to be redirected to a specific tty.
1078 * We don't put it into the syslog queue right now maybe in the future if
1079 * really needed.
1080 *
1081 * We must still hold the BTM and test the CLOSING flag for the moment.
1082 */
1083
1084void tty_write_message(struct tty_struct *tty, char *msg)
1085{
1086 if (tty) {
1087 mutex_lock(&tty->atomic_write_lock);
1088 tty_lock();
1089 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
1090 tty_unlock();
1091 tty->ops->write(tty, msg, strlen(msg));
1092 } else
1093 tty_unlock();
1094 tty_write_unlock(tty);
1095 }
1096 return;
1097}
1098
1099
1100/**
1101 * tty_write - write method for tty device file
1102 * @file: tty file pointer
1103 * @buf: user data to write
1104 * @count: bytes to write
1105 * @ppos: unused
1106 *
1107 * Write data to a tty device via the line discipline.
1108 *
1109 * Locking:
1110 * Locks the line discipline as required
1111 * Writes to the tty driver are serialized by the atomic_write_lock
1112 * and are then processed in chunks to the device. The line discipline
1113 * write method will not be invoked in parallel for each device.
1114 */
1115
1116static ssize_t tty_write(struct file *file, const char __user *buf,
1117 size_t count, loff_t *ppos)
1118{
1119 struct inode *inode = file->f_path.dentry->d_inode;
1120 struct tty_struct *tty = file_tty(file);
1121 struct tty_ldisc *ld;
1122 ssize_t ret;
1123
1124 if (tty_paranoia_check(tty, inode, "tty_write"))
1125 return -EIO;
1126 if (!tty || !tty->ops->write ||
1127 (test_bit(TTY_IO_ERROR, &tty->flags)))
1128 return -EIO;
1129 /* Short term debug to catch buggy drivers */
1130 if (tty->ops->write_room == NULL)
1131 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1132 tty->driver->name);
1133 ld = tty_ldisc_ref_wait(tty);
1134 if (!ld->ops->write)
1135 ret = -EIO;
1136 else
1137 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1138 tty_ldisc_deref(ld);
1139 return ret;
1140}
1141
1142ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1143 size_t count, loff_t *ppos)
1144{
1145 struct file *p = NULL;
1146
1147 spin_lock(&redirect_lock);
1148 if (redirect) {
1149 get_file(redirect);
1150 p = redirect;
1151 }
1152 spin_unlock(&redirect_lock);
1153
1154 if (p) {
1155 ssize_t res;
1156 res = vfs_write(p, buf, count, &p->f_pos);
1157 fput(p);
1158 return res;
1159 }
1160 return tty_write(file, buf, count, ppos);
1161}
1162
1163static char ptychar[] = "pqrstuvwxyzabcde";
1164
1165/**
1166 * pty_line_name - generate name for a pty
1167 * @driver: the tty driver in use
1168 * @index: the minor number
1169 * @p: output buffer of at least 6 bytes
1170 *
1171 * Generate a name from a driver reference and write it to the output
1172 * buffer.
1173 *
1174 * Locking: None
1175 */
1176static void pty_line_name(struct tty_driver *driver, int index, char *p)
1177{
1178 int i = index + driver->name_base;
1179 /* ->name is initialized to "ttyp", but "tty" is expected */
1180 sprintf(p, "%s%c%x",
1181 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1182 ptychar[i >> 4 & 0xf], i & 0xf);
1183}
1184
1185/**
1186 * tty_line_name - generate name for a tty
1187 * @driver: the tty driver in use
1188 * @index: the minor number
1189 * @p: output buffer of at least 7 bytes
1190 *
1191 * Generate a name from a driver reference and write it to the output
1192 * buffer.
1193 *
1194 * Locking: None
1195 */
1196static void tty_line_name(struct tty_driver *driver, int index, char *p)
1197{
1198 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1199}
1200
1201/**
1202 * tty_driver_lookup_tty() - find an existing tty, if any
1203 * @driver: the driver for the tty
1204 * @idx: the minor number
1205 *
1206 * Return the tty, if found or ERR_PTR() otherwise.
1207 *
1208 * Locking: tty_mutex must be held. If tty is found, the mutex must
1209 * be held until the 'fast-open' is also done. Will change once we
1210 * have refcounting in the driver and per driver locking
1211 */
1212static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1213 struct inode *inode, int idx)
1214{
1215 struct tty_struct *tty;
1216
1217 if (driver->ops->lookup)
1218 return driver->ops->lookup(driver, inode, idx);
1219
1220 tty = driver->ttys[idx];
1221 return tty;
1222}
1223
1224/**
1225 * tty_init_termios - helper for termios setup
1226 * @tty: the tty to set up
1227 *
1228 * Initialise the termios structures for this tty. Thus runs under
1229 * the tty_mutex currently so we can be relaxed about ordering.
1230 */
1231
1232int tty_init_termios(struct tty_struct *tty)
1233{
1234 struct ktermios *tp;
1235 int idx = tty->index;
1236
1237 tp = tty->driver->termios[idx];
1238 if (tp == NULL) {
1239 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1240 if (tp == NULL)
1241 return -ENOMEM;
1242 memcpy(tp, &tty->driver->init_termios,
1243 sizeof(struct ktermios));
1244 tty->driver->termios[idx] = tp;
1245 }
1246 tty->termios = tp;
1247 tty->termios_locked = tp + 1;
1248
1249 /* Compatibility until drivers always set this */
1250 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1251 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1252 return 0;
1253}
1254EXPORT_SYMBOL_GPL(tty_init_termios);
1255
1256/**
1257 * tty_driver_install_tty() - install a tty entry in the driver
1258 * @driver: the driver for the tty
1259 * @tty: the tty
1260 *
1261 * Install a tty object into the driver tables. The tty->index field
1262 * will be set by the time this is called. This method is responsible
1263 * for ensuring any need additional structures are allocated and
1264 * configured.
1265 *
1266 * Locking: tty_mutex for now
1267 */
1268static int tty_driver_install_tty(struct tty_driver *driver,
1269 struct tty_struct *tty)
1270{
1271 int idx = tty->index;
1272 int ret;
1273
1274 if (driver->ops->install) {
1275 ret = driver->ops->install(driver, tty);
1276 return ret;
1277 }
1278
1279 if (tty_init_termios(tty) == 0) {
1280 tty_driver_kref_get(driver);
1281 tty->count++;
1282 driver->ttys[idx] = tty;
1283 return 0;
1284 }
1285 return -ENOMEM;
1286}
1287
1288/**
1289 * tty_driver_remove_tty() - remove a tty from the driver tables
1290 * @driver: the driver for the tty
1291 * @idx: the minor number
1292 *
1293 * Remvoe a tty object from the driver tables. The tty->index field
1294 * will be set by the time this is called.
1295 *
1296 * Locking: tty_mutex for now
1297 */
1298void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1299{
1300 if (driver->ops->remove)
1301 driver->ops->remove(driver, tty);
1302 else
1303 driver->ttys[tty->index] = NULL;
1304}
1305
1306/*
1307 * tty_reopen() - fast re-open of an open tty
1308 * @tty - the tty to open
1309 *
1310 * Return 0 on success, -errno on error.
1311 *
1312 * Locking: tty_mutex must be held from the time the tty was found
1313 * till this open completes.
1314 */
1315static int tty_reopen(struct tty_struct *tty)
1316{
1317 struct tty_driver *driver = tty->driver;
1318
1319 if (test_bit(TTY_CLOSING, &tty->flags) ||
1320 test_bit(TTY_HUPPING, &tty->flags) ||
1321 test_bit(TTY_LDISC_CHANGING, &tty->flags))
1322 return -EIO;
1323
1324 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1325 driver->subtype == PTY_TYPE_MASTER) {
1326 /*
1327 * special case for PTY masters: only one open permitted,
1328 * and the slave side open count is incremented as well.
1329 */
1330 if (tty->count)
1331 return -EIO;
1332
1333 tty->link->count++;
1334 }
1335 tty->count++;
1336 tty->driver = driver; /* N.B. why do this every time?? */
1337
1338 mutex_lock(&tty->ldisc_mutex);
1339 WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1340 mutex_unlock(&tty->ldisc_mutex);
1341
1342 return 0;
1343}
1344
1345/**
1346 * tty_init_dev - initialise a tty device
1347 * @driver: tty driver we are opening a device on
1348 * @idx: device index
1349 * @ret_tty: returned tty structure
1350 * @first_ok: ok to open a new device (used by ptmx)
1351 *
1352 * Prepare a tty device. This may not be a "new" clean device but
1353 * could also be an active device. The pty drivers require special
1354 * handling because of this.
1355 *
1356 * Locking:
1357 * The function is called under the tty_mutex, which
1358 * protects us from the tty struct or driver itself going away.
1359 *
1360 * On exit the tty device has the line discipline attached and
1361 * a reference count of 1. If a pair was created for pty/tty use
1362 * and the other was a pty master then it too has a reference count of 1.
1363 *
1364 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1365 * failed open. The new code protects the open with a mutex, so it's
1366 * really quite straightforward. The mutex locking can probably be
1367 * relaxed for the (most common) case of reopening a tty.
1368 */
1369
1370struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
1371 int first_ok)
1372{
1373 struct tty_struct *tty;
1374 int retval;
1375
1376 /* Check if pty master is being opened multiple times */
1377 if (driver->subtype == PTY_TYPE_MASTER &&
1378 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
1379 return ERR_PTR(-EIO);
1380 }
1381
1382 /*
1383 * First time open is complex, especially for PTY devices.
1384 * This code guarantees that either everything succeeds and the
1385 * TTY is ready for operation, or else the table slots are vacated
1386 * and the allocated memory released. (Except that the termios
1387 * and locked termios may be retained.)
1388 */
1389
1390 if (!try_module_get(driver->owner))
1391 return ERR_PTR(-ENODEV);
1392
1393 tty = alloc_tty_struct();
1394 if (!tty) {
1395 retval = -ENOMEM;
1396 goto err_module_put;
1397 }
1398 initialize_tty_struct(tty, driver, idx);
1399
1400 retval = tty_driver_install_tty(driver, tty);
1401 if (retval < 0)
1402 goto err_deinit_tty;
1403
1404 /*
1405 * Structures all installed ... call the ldisc open routines.
1406 * If we fail here just call release_tty to clean up. No need
1407 * to decrement the use counts, as release_tty doesn't care.
1408 */
1409 retval = tty_ldisc_setup(tty, tty->link);
1410 if (retval)
1411 goto err_release_tty;
1412 return tty;
1413
1414err_deinit_tty:
1415 deinitialize_tty_struct(tty);
1416 free_tty_struct(tty);
1417err_module_put:
1418 module_put(driver->owner);
1419 return ERR_PTR(retval);
1420
1421 /* call the tty release_tty routine to clean out this slot */
1422err_release_tty:
1423 printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
1424 "clearing slot %d\n", idx);
1425 release_tty(tty, idx);
1426 return ERR_PTR(retval);
1427}
1428
1429void tty_free_termios(struct tty_struct *tty)
1430{
1431 struct ktermios *tp;
1432 int idx = tty->index;
1433 /* Kill this flag and push into drivers for locking etc */
1434 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1435 /* FIXME: Locking on ->termios array */
1436 tp = tty->termios;
1437 tty->driver->termios[idx] = NULL;
1438 kfree(tp);
1439 }
1440}
1441EXPORT_SYMBOL(tty_free_termios);
1442
1443void tty_shutdown(struct tty_struct *tty)
1444{
1445 tty_driver_remove_tty(tty->driver, tty);
1446 tty_free_termios(tty);
1447}
1448EXPORT_SYMBOL(tty_shutdown);
1449
1450/**
1451 * release_one_tty - release tty structure memory
1452 * @kref: kref of tty we are obliterating
1453 *
1454 * Releases memory associated with a tty structure, and clears out the
1455 * driver table slots. This function is called when a device is no longer
1456 * in use. It also gets called when setup of a device fails.
1457 *
1458 * Locking:
1459 * tty_mutex - sometimes only
1460 * takes the file list lock internally when working on the list
1461 * of ttys that the driver keeps.
1462 *
1463 * This method gets called from a work queue so that the driver private
1464 * cleanup ops can sleep (needed for USB at least)
1465 */
1466static void release_one_tty(struct work_struct *work)
1467{
1468 struct tty_struct *tty =
1469 container_of(work, struct tty_struct, hangup_work);
1470 struct tty_driver *driver = tty->driver;
1471
1472 if (tty->ops->cleanup)
1473 tty->ops->cleanup(tty);
1474
1475 tty->magic = 0;
1476 tty_driver_kref_put(driver);
1477 module_put(driver->owner);
1478
1479 spin_lock(&tty_files_lock);
1480 list_del_init(&tty->tty_files);
1481 spin_unlock(&tty_files_lock);
1482
1483 put_pid(tty->pgrp);
1484 put_pid(tty->session);
1485 free_tty_struct(tty);
1486}
1487
1488static void queue_release_one_tty(struct kref *kref)
1489{
1490 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1491
1492 if (tty->ops->shutdown)
1493 tty->ops->shutdown(tty);
1494 else
1495 tty_shutdown(tty);
1496
1497 /* The hangup queue is now free so we can reuse it rather than
1498 waste a chunk of memory for each port */
1499 INIT_WORK(&tty->hangup_work, release_one_tty);
1500 schedule_work(&tty->hangup_work);
1501}
1502
1503/**
1504 * tty_kref_put - release a tty kref
1505 * @tty: tty device
1506 *
1507 * Release a reference to a tty device and if need be let the kref
1508 * layer destruct the object for us
1509 */
1510
1511void tty_kref_put(struct tty_struct *tty)
1512{
1513 if (tty)
1514 kref_put(&tty->kref, queue_release_one_tty);
1515}
1516EXPORT_SYMBOL(tty_kref_put);
1517
1518/**
1519 * release_tty - release tty structure memory
1520 *
1521 * Release both @tty and a possible linked partner (think pty pair),
1522 * and decrement the refcount of the backing module.
1523 *
1524 * Locking:
1525 * tty_mutex - sometimes only
1526 * takes the file list lock internally when working on the list
1527 * of ttys that the driver keeps.
1528 * FIXME: should we require tty_mutex is held here ??
1529 *
1530 */
1531static void release_tty(struct tty_struct *tty, int idx)
1532{
1533 /* This should always be true but check for the moment */
1534 WARN_ON(tty->index != idx);
1535
1536 if (tty->link)
1537 tty_kref_put(tty->link);
1538 tty_kref_put(tty);
1539}
1540
1541/**
1542 * tty_release - vfs callback for close
1543 * @inode: inode of tty
1544 * @filp: file pointer for handle to tty
1545 *
1546 * Called the last time each file handle is closed that references
1547 * this tty. There may however be several such references.
1548 *
1549 * Locking:
1550 * Takes bkl. See tty_release_dev
1551 *
1552 * Even releasing the tty structures is a tricky business.. We have
1553 * to be very careful that the structures are all released at the
1554 * same time, as interrupts might otherwise get the wrong pointers.
1555 *
1556 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1557 * lead to double frees or releasing memory still in use.
1558 */
1559
1560int tty_release(struct inode *inode, struct file *filp)
1561{
1562 struct tty_struct *tty = file_tty(filp);
1563 struct tty_struct *o_tty;
1564 int pty_master, tty_closing, o_tty_closing, do_sleep;
1565 int devpts;
1566 int idx;
1567 char buf[64];
1568
1569 if (tty_paranoia_check(tty, inode, "tty_release_dev"))
1570 return 0;
1571
1572 tty_lock();
1573 check_tty_count(tty, "tty_release_dev");
1574
1575 __tty_fasync(-1, filp, 0);
1576
1577 idx = tty->index;
1578 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1579 tty->driver->subtype == PTY_TYPE_MASTER);
1580 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1581 o_tty = tty->link;
1582
1583#ifdef TTY_PARANOIA_CHECK
1584 if (idx < 0 || idx >= tty->driver->num) {
1585 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1586 "free (%s)\n", tty->name);
1587 tty_unlock();
1588 return 0;
1589 }
1590 if (!devpts) {
1591 if (tty != tty->driver->ttys[idx]) {
1592 tty_unlock();
1593 printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1594 "for (%s)\n", idx, tty->name);
1595 return 0;
1596 }
1597 if (tty->termios != tty->driver->termios[idx]) {
1598 tty_unlock();
1599 printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1600 "for (%s)\n",
1601 idx, tty->name);
1602 return 0;
1603 }
1604 }
1605#endif
1606
1607#ifdef TTY_DEBUG_HANGUP
1608 printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1609 tty_name(tty, buf), tty->count);
1610#endif
1611
1612#ifdef TTY_PARANOIA_CHECK
1613 if (tty->driver->other &&
1614 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1615 if (o_tty != tty->driver->other->ttys[idx]) {
1616 tty_unlock();
1617 printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1618 "not o_tty for (%s)\n",
1619 idx, tty->name);
1620 return 0 ;
1621 }
1622 if (o_tty->termios != tty->driver->other->termios[idx]) {
1623 tty_unlock();
1624 printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1625 "not o_termios for (%s)\n",
1626 idx, tty->name);
1627 return 0;
1628 }
1629 if (o_tty->link != tty) {
1630 tty_unlock();
1631 printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1632 return 0;
1633 }
1634 }
1635#endif
1636 if (tty->ops->close)
1637 tty->ops->close(tty, filp);
1638
1639 tty_unlock();
1640 /*
1641 * Sanity check: if tty->count is going to zero, there shouldn't be
1642 * any waiters on tty->read_wait or tty->write_wait. We test the
1643 * wait queues and kick everyone out _before_ actually starting to
1644 * close. This ensures that we won't block while releasing the tty
1645 * structure.
1646 *
1647 * The test for the o_tty closing is necessary, since the master and
1648 * slave sides may close in any order. If the slave side closes out
1649 * first, its count will be one, since the master side holds an open.
1650 * Thus this test wouldn't be triggered at the time the slave closes,
1651 * so we do it now.
1652 *
1653 * Note that it's possible for the tty to be opened again while we're
1654 * flushing out waiters. By recalculating the closing flags before
1655 * each iteration we avoid any problems.
1656 */
1657 while (1) {
1658 /* Guard against races with tty->count changes elsewhere and
1659 opens on /dev/tty */
1660
1661 mutex_lock(&tty_mutex);
1662 tty_lock();
1663 tty_closing = tty->count <= 1;
1664 o_tty_closing = o_tty &&
1665 (o_tty->count <= (pty_master ? 1 : 0));
1666 do_sleep = 0;
1667
1668 if (tty_closing) {
1669 if (waitqueue_active(&tty->read_wait)) {
1670 wake_up_poll(&tty->read_wait, POLLIN);
1671 do_sleep++;
1672 }
1673 if (waitqueue_active(&tty->write_wait)) {
1674 wake_up_poll(&tty->write_wait, POLLOUT);
1675 do_sleep++;
1676 }
1677 }
1678 if (o_tty_closing) {
1679 if (waitqueue_active(&o_tty->read_wait)) {
1680 wake_up_poll(&o_tty->read_wait, POLLIN);
1681 do_sleep++;
1682 }
1683 if (waitqueue_active(&o_tty->write_wait)) {
1684 wake_up_poll(&o_tty->write_wait, POLLOUT);
1685 do_sleep++;
1686 }
1687 }
1688 if (!do_sleep)
1689 break;
1690
1691 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1692 "active!\n", tty_name(tty, buf));
1693 tty_unlock();
1694 mutex_unlock(&tty_mutex);
1695 schedule();
1696 }
1697
1698 /*
1699 * The closing flags are now consistent with the open counts on
1700 * both sides, and we've completed the last operation that could
1701 * block, so it's safe to proceed with closing.
1702 */
1703 if (pty_master) {
1704 if (--o_tty->count < 0) {
1705 printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1706 "(%d) for %s\n",
1707 o_tty->count, tty_name(o_tty, buf));
1708 o_tty->count = 0;
1709 }
1710 }
1711 if (--tty->count < 0) {
1712 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1713 tty->count, tty_name(tty, buf));
1714 tty->count = 0;
1715 }
1716
1717 /*
1718 * We've decremented tty->count, so we need to remove this file
1719 * descriptor off the tty->tty_files list; this serves two
1720 * purposes:
1721 * - check_tty_count sees the correct number of file descriptors
1722 * associated with this tty.
1723 * - do_tty_hangup no longer sees this file descriptor as
1724 * something that needs to be handled for hangups.
1725 */
1726 tty_del_file(filp);
1727
1728 /*
1729 * Perform some housekeeping before deciding whether to return.
1730 *
1731 * Set the TTY_CLOSING flag if this was the last open. In the
1732 * case of a pty we may have to wait around for the other side
1733 * to close, and TTY_CLOSING makes sure we can't be reopened.
1734 */
1735 if (tty_closing)
1736 set_bit(TTY_CLOSING, &tty->flags);
1737 if (o_tty_closing)
1738 set_bit(TTY_CLOSING, &o_tty->flags);
1739
1740 /*
1741 * If _either_ side is closing, make sure there aren't any
1742 * processes that still think tty or o_tty is their controlling
1743 * tty.
1744 */
1745 if (tty_closing || o_tty_closing) {
1746 read_lock(&tasklist_lock);
1747 session_clear_tty(tty->session);
1748 if (o_tty)
1749 session_clear_tty(o_tty->session);
1750 read_unlock(&tasklist_lock);
1751 }
1752
1753 mutex_unlock(&tty_mutex);
1754
1755 /* check whether both sides are closing ... */
1756 if (!tty_closing || (o_tty && !o_tty_closing)) {
1757 tty_unlock();
1758 return 0;
1759 }
1760
1761#ifdef TTY_DEBUG_HANGUP
1762 printk(KERN_DEBUG "freeing tty structure...");
1763#endif
1764 /*
1765 * Ask the line discipline code to release its structures
1766 */
1767 tty_ldisc_release(tty, o_tty);
1768 /*
1769 * The release_tty function takes care of the details of clearing
1770 * the slots and preserving the termios structure.
1771 */
1772 release_tty(tty, idx);
1773
1774 /* Make this pty number available for reallocation */
1775 if (devpts)
1776 devpts_kill_index(inode, idx);
1777 tty_unlock();
1778 return 0;
1779}
1780
1781/**
1782 * tty_open - open a tty device
1783 * @inode: inode of device file
1784 * @filp: file pointer to tty
1785 *
1786 * tty_open and tty_release keep up the tty count that contains the
1787 * number of opens done on a tty. We cannot use the inode-count, as
1788 * different inodes might point to the same tty.
1789 *
1790 * Open-counting is needed for pty masters, as well as for keeping
1791 * track of serial lines: DTR is dropped when the last close happens.
1792 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1793 *
1794 * The termios state of a pty is reset on first open so that
1795 * settings don't persist across reuse.
1796 *
1797 * Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1798 * tty->count should protect the rest.
1799 * ->siglock protects ->signal/->sighand
1800 */
1801
1802static int tty_open(struct inode *inode, struct file *filp)
1803{
1804 struct tty_struct *tty = NULL;
1805 int noctty, retval;
1806 struct tty_driver *driver;
1807 int index;
1808 dev_t device = inode->i_rdev;
1809 unsigned saved_flags = filp->f_flags;
1810
1811 nonseekable_open(inode, filp);
1812
1813retry_open:
1814 noctty = filp->f_flags & O_NOCTTY;
1815 index = -1;
1816 retval = 0;
1817
1818 mutex_lock(&tty_mutex);
1819 tty_lock();
1820
1821 if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1822 tty = get_current_tty();
1823 if (!tty) {
1824 tty_unlock();
1825 mutex_unlock(&tty_mutex);
1826 return -ENXIO;
1827 }
1828 driver = tty_driver_kref_get(tty->driver);
1829 index = tty->index;
1830 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1831 /* noctty = 1; */
1832 /* FIXME: Should we take a driver reference ? */
1833 tty_kref_put(tty);
1834 goto got_driver;
1835 }
1836#ifdef CONFIG_VT
1837 if (device == MKDEV(TTY_MAJOR, 0)) {
1838 extern struct tty_driver *console_driver;
1839 driver = tty_driver_kref_get(console_driver);
1840 index = fg_console;
1841 noctty = 1;
1842 goto got_driver;
1843 }
1844#endif
1845 if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1846 struct tty_driver *console_driver = console_device(&index);
1847 if (console_driver) {
1848 driver = tty_driver_kref_get(console_driver);
1849 if (driver) {
1850 /* Don't let /dev/console block */
1851 filp->f_flags |= O_NONBLOCK;
1852 noctty = 1;
1853 goto got_driver;
1854 }
1855 }
1856 tty_unlock();
1857 mutex_unlock(&tty_mutex);
1858 return -ENODEV;
1859 }
1860
1861 driver = get_tty_driver(device, &index);
1862 if (!driver) {
1863 tty_unlock();
1864 mutex_unlock(&tty_mutex);
1865 return -ENODEV;
1866 }
1867got_driver:
1868 if (!tty) {
1869 /* check whether we're reopening an existing tty */
1870 tty = tty_driver_lookup_tty(driver, inode, index);
1871
1872 if (IS_ERR(tty)) {
1873 tty_unlock();
1874 mutex_unlock(&tty_mutex);
1875 return PTR_ERR(tty);
1876 }
1877 }
1878
1879 if (tty) {
1880 retval = tty_reopen(tty);
1881 if (retval)
1882 tty = ERR_PTR(retval);
1883 } else
1884 tty = tty_init_dev(driver, index, 0);
1885
1886 mutex_unlock(&tty_mutex);
1887 tty_driver_kref_put(driver);
1888 if (IS_ERR(tty)) {
1889 tty_unlock();
1890 return PTR_ERR(tty);
1891 }
1892
1893 retval = tty_add_file(tty, filp);
1894 if (retval) {
1895 tty_unlock();
1896 tty_release(inode, filp);
1897 return retval;
1898 }
1899
1900 check_tty_count(tty, "tty_open");
1901 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1902 tty->driver->subtype == PTY_TYPE_MASTER)
1903 noctty = 1;
1904#ifdef TTY_DEBUG_HANGUP
1905 printk(KERN_DEBUG "opening %s...", tty->name);
1906#endif
1907 if (tty->ops->open)
1908 retval = tty->ops->open(tty, filp);
1909 else
1910 retval = -ENODEV;
1911 filp->f_flags = saved_flags;
1912
1913 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1914 !capable(CAP_SYS_ADMIN))
1915 retval = -EBUSY;
1916
1917 if (retval) {
1918#ifdef TTY_DEBUG_HANGUP
1919 printk(KERN_DEBUG "error %d in opening %s...", retval,
1920 tty->name);
1921#endif
1922 tty_unlock(); /* need to call tty_release without BTM */
1923 tty_release(inode, filp);
1924 if (retval != -ERESTARTSYS)
1925 return retval;
1926
1927 if (signal_pending(current))
1928 return retval;
1929
1930 schedule();
1931 /*
1932 * Need to reset f_op in case a hangup happened.
1933 */
1934 tty_lock();
1935 if (filp->f_op == &hung_up_tty_fops)
1936 filp->f_op = &tty_fops;
1937 tty_unlock();
1938 goto retry_open;
1939 }
1940 tty_unlock();
1941
1942
1943 mutex_lock(&tty_mutex);
1944 tty_lock();
1945 spin_lock_irq(¤t->sighand->siglock);
1946 if (!noctty &&
1947 current->signal->leader &&
1948 !current->signal->tty &&
1949 tty->session == NULL)
1950 __proc_set_tty(current, tty);
1951 spin_unlock_irq(¤t->sighand->siglock);
1952 tty_unlock();
1953 mutex_unlock(&tty_mutex);
1954 return 0;
1955}
1956
1957
1958
1959/**
1960 * tty_poll - check tty status
1961 * @filp: file being polled
1962 * @wait: poll wait structures to update
1963 *
1964 * Call the line discipline polling method to obtain the poll
1965 * status of the device.
1966 *
1967 * Locking: locks called line discipline but ldisc poll method
1968 * may be re-entered freely by other callers.
1969 */
1970
1971static unsigned int tty_poll(struct file *filp, poll_table *wait)
1972{
1973 struct tty_struct *tty = file_tty(filp);
1974 struct tty_ldisc *ld;
1975 int ret = 0;
1976
1977 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
1978 return 0;
1979
1980 ld = tty_ldisc_ref_wait(tty);
1981 if (ld->ops->poll)
1982 ret = (ld->ops->poll)(tty, filp, wait);
1983 tty_ldisc_deref(ld);
1984 return ret;
1985}
1986
1987static int __tty_fasync(int fd, struct file *filp, int on)
1988{
1989 struct tty_struct *tty = file_tty(filp);
1990 unsigned long flags;
1991 int retval = 0;
1992
1993 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
1994 goto out;
1995
1996 retval = fasync_helper(fd, filp, on, &tty->fasync);
1997 if (retval <= 0)
1998 goto out;
1999
2000 if (on) {
2001 enum pid_type type;
2002 struct pid *pid;
2003 if (!waitqueue_active(&tty->read_wait))
2004 tty->minimum_to_wake = 1;
2005 spin_lock_irqsave(&tty->ctrl_lock, flags);
2006 if (tty->pgrp) {
2007 pid = tty->pgrp;
2008 type = PIDTYPE_PGID;
2009 } else {
2010 pid = task_pid(current);
2011 type = PIDTYPE_PID;
2012 }
2013 get_pid(pid);
2014 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2015 retval = __f_setown(filp, pid, type, 0);
2016 put_pid(pid);
2017 if (retval)
2018 goto out;
2019 } else {
2020 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2021 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2022 }
2023 retval = 0;
2024out:
2025 return retval;
2026}
2027
2028static int tty_fasync(int fd, struct file *filp, int on)
2029{
2030 int retval;
2031 tty_lock();
2032 retval = __tty_fasync(fd, filp, on);
2033 tty_unlock();
2034 return retval;
2035}
2036
2037/**
2038 * tiocsti - fake input character
2039 * @tty: tty to fake input into
2040 * @p: pointer to character
2041 *
2042 * Fake input to a tty device. Does the necessary locking and
2043 * input management.
2044 *
2045 * FIXME: does not honour flow control ??
2046 *
2047 * Locking:
2048 * Called functions take tty_ldisc_lock
2049 * current->signal->tty check is safe without locks
2050 *
2051 * FIXME: may race normal receive processing
2052 */
2053
2054static int tiocsti(struct tty_struct *tty, char __user *p)
2055{
2056 char ch, mbz = 0;
2057 struct tty_ldisc *ld;
2058
2059 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2060 return -EPERM;
2061 if (get_user(ch, p))
2062 return -EFAULT;
2063 tty_audit_tiocsti(tty, ch);
2064 ld = tty_ldisc_ref_wait(tty);
2065 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2066 tty_ldisc_deref(ld);
2067 return 0;
2068}
2069
2070/**
2071 * tiocgwinsz - implement window query ioctl
2072 * @tty; tty
2073 * @arg: user buffer for result
2074 *
2075 * Copies the kernel idea of the window size into the user buffer.
2076 *
2077 * Locking: tty->termios_mutex is taken to ensure the winsize data
2078 * is consistent.
2079 */
2080
2081static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2082{
2083 int err;
2084
2085 mutex_lock(&tty->termios_mutex);
2086 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2087 mutex_unlock(&tty->termios_mutex);
2088
2089 return err ? -EFAULT: 0;
2090}
2091
2092/**
2093 * tty_do_resize - resize event
2094 * @tty: tty being resized
2095 * @rows: rows (character)
2096 * @cols: cols (character)
2097 *
2098 * Update the termios variables and send the necessary signals to
2099 * peform a terminal resize correctly
2100 */
2101
2102int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2103{
2104 struct pid *pgrp;
2105 unsigned long flags;
2106
2107 /* Lock the tty */
2108 mutex_lock(&tty->termios_mutex);
2109 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2110 goto done;
2111 /* Get the PID values and reference them so we can
2112 avoid holding the tty ctrl lock while sending signals */
2113 spin_lock_irqsave(&tty->ctrl_lock, flags);
2114 pgrp = get_pid(tty->pgrp);
2115 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2116
2117 if (pgrp)
2118 kill_pgrp(pgrp, SIGWINCH, 1);
2119 put_pid(pgrp);
2120
2121 tty->winsize = *ws;
2122done:
2123 mutex_unlock(&tty->termios_mutex);
2124 return 0;
2125}
2126
2127/**
2128 * tiocswinsz - implement window size set ioctl
2129 * @tty; tty side of tty
2130 * @arg: user buffer for result
2131 *
2132 * Copies the user idea of the window size to the kernel. Traditionally
2133 * this is just advisory information but for the Linux console it
2134 * actually has driver level meaning and triggers a VC resize.
2135 *
2136 * Locking:
2137 * Driver dependent. The default do_resize method takes the
2138 * tty termios mutex and ctrl_lock. The console takes its own lock
2139 * then calls into the default method.
2140 */
2141
2142static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2143{
2144 struct winsize tmp_ws;
2145 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2146 return -EFAULT;
2147
2148 if (tty->ops->resize)
2149 return tty->ops->resize(tty, &tmp_ws);
2150 else
2151 return tty_do_resize(tty, &tmp_ws);
2152}
2153
2154/**
2155 * tioccons - allow admin to move logical console
2156 * @file: the file to become console
2157 *
2158 * Allow the administrator to move the redirected console device
2159 *
2160 * Locking: uses redirect_lock to guard the redirect information
2161 */
2162
2163static int tioccons(struct file *file)
2164{
2165 if (!capable(CAP_SYS_ADMIN))
2166 return -EPERM;
2167 if (file->f_op->write == redirected_tty_write) {
2168 struct file *f;
2169 spin_lock(&redirect_lock);
2170 f = redirect;
2171 redirect = NULL;
2172 spin_unlock(&redirect_lock);
2173 if (f)
2174 fput(f);
2175 return 0;
2176 }
2177 spin_lock(&redirect_lock);
2178 if (redirect) {
2179 spin_unlock(&redirect_lock);
2180 return -EBUSY;
2181 }
2182 get_file(file);
2183 redirect = file;
2184 spin_unlock(&redirect_lock);
2185 return 0;
2186}
2187
2188/**
2189 * fionbio - non blocking ioctl
2190 * @file: file to set blocking value
2191 * @p: user parameter
2192 *
2193 * Historical tty interfaces had a blocking control ioctl before
2194 * the generic functionality existed. This piece of history is preserved
2195 * in the expected tty API of posix OS's.
2196 *
2197 * Locking: none, the open file handle ensures it won't go away.
2198 */
2199
2200static int fionbio(struct file *file, int __user *p)
2201{
2202 int nonblock;
2203
2204 if (get_user(nonblock, p))
2205 return -EFAULT;
2206
2207 spin_lock(&file->f_lock);
2208 if (nonblock)
2209 file->f_flags |= O_NONBLOCK;
2210 else
2211 file->f_flags &= ~O_NONBLOCK;
2212 spin_unlock(&file->f_lock);
2213 return 0;
2214}
2215
2216/**
2217 * tiocsctty - set controlling tty
2218 * @tty: tty structure
2219 * @arg: user argument
2220 *
2221 * This ioctl is used to manage job control. It permits a session
2222 * leader to set this tty as the controlling tty for the session.
2223 *
2224 * Locking:
2225 * Takes tty_mutex() to protect tty instance
2226 * Takes tasklist_lock internally to walk sessions
2227 * Takes ->siglock() when updating signal->tty
2228 */
2229
2230static int tiocsctty(struct tty_struct *tty, int arg)
2231{
2232 int ret = 0;
2233 if (current->signal->leader && (task_session(current) == tty->session))
2234 return ret;
2235
2236 mutex_lock(&tty_mutex);
2237 /*
2238 * The process must be a session leader and
2239 * not have a controlling tty already.
2240 */
2241 if (!current->signal->leader || current->signal->tty) {
2242 ret = -EPERM;
2243 goto unlock;
2244 }
2245
2246 if (tty->session) {
2247 /*
2248 * This tty is already the controlling
2249 * tty for another session group!
2250 */
2251 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2252 /*
2253 * Steal it away
2254 */
2255 read_lock(&tasklist_lock);
2256 session_clear_tty(tty->session);
2257 read_unlock(&tasklist_lock);
2258 } else {
2259 ret = -EPERM;
2260 goto unlock;
2261 }
2262 }
2263 proc_set_tty(current, tty);
2264unlock:
2265 mutex_unlock(&tty_mutex);
2266 return ret;
2267}
2268
2269/**
2270 * tty_get_pgrp - return a ref counted pgrp pid
2271 * @tty: tty to read
2272 *
2273 * Returns a refcounted instance of the pid struct for the process
2274 * group controlling the tty.
2275 */
2276
2277struct pid *tty_get_pgrp(struct tty_struct *tty)
2278{
2279 unsigned long flags;
2280 struct pid *pgrp;
2281
2282 spin_lock_irqsave(&tty->ctrl_lock, flags);
2283 pgrp = get_pid(tty->pgrp);
2284 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2285
2286 return pgrp;
2287}
2288EXPORT_SYMBOL_GPL(tty_get_pgrp);
2289
2290/**
2291 * tiocgpgrp - get process group
2292 * @tty: tty passed by user
2293 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2294 * @p: returned pid
2295 *
2296 * Obtain the process group of the tty. If there is no process group
2297 * return an error.
2298 *
2299 * Locking: none. Reference to current->signal->tty is safe.
2300 */
2301
2302static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2303{
2304 struct pid *pid;
2305 int ret;
2306 /*
2307 * (tty == real_tty) is a cheap way of
2308 * testing if the tty is NOT a master pty.
2309 */
2310 if (tty == real_tty && current->signal->tty != real_tty)
2311 return -ENOTTY;
2312 pid = tty_get_pgrp(real_tty);
2313 ret = put_user(pid_vnr(pid), p);
2314 put_pid(pid);
2315 return ret;
2316}
2317
2318/**
2319 * tiocspgrp - attempt to set process group
2320 * @tty: tty passed by user
2321 * @real_tty: tty side device matching tty passed by user
2322 * @p: pid pointer
2323 *
2324 * Set the process group of the tty to the session passed. Only
2325 * permitted where the tty session is our session.
2326 *
2327 * Locking: RCU, ctrl lock
2328 */
2329
2330static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2331{
2332 struct pid *pgrp;
2333 pid_t pgrp_nr;
2334 int retval = tty_check_change(real_tty);
2335 unsigned long flags;
2336
2337 if (retval == -EIO)
2338 return -ENOTTY;
2339 if (retval)
2340 return retval;
2341 if (!current->signal->tty ||
2342 (current->signal->tty != real_tty) ||
2343 (real_tty->session != task_session(current)))
2344 return -ENOTTY;
2345 if (get_user(pgrp_nr, p))
2346 return -EFAULT;
2347 if (pgrp_nr < 0)
2348 return -EINVAL;
2349 rcu_read_lock();
2350 pgrp = find_vpid(pgrp_nr);
2351 retval = -ESRCH;
2352 if (!pgrp)
2353 goto out_unlock;
2354 retval = -EPERM;
2355 if (session_of_pgrp(pgrp) != task_session(current))
2356 goto out_unlock;
2357 retval = 0;
2358 spin_lock_irqsave(&tty->ctrl_lock, flags);
2359 put_pid(real_tty->pgrp);
2360 real_tty->pgrp = get_pid(pgrp);
2361 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2362out_unlock:
2363 rcu_read_unlock();
2364 return retval;
2365}
2366
2367/**
2368 * tiocgsid - get session id
2369 * @tty: tty passed by user
2370 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2371 * @p: pointer to returned session id
2372 *
2373 * Obtain the session id of the tty. If there is no session
2374 * return an error.
2375 *
2376 * Locking: none. Reference to current->signal->tty is safe.
2377 */
2378
2379static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2380{
2381 /*
2382 * (tty == real_tty) is a cheap way of
2383 * testing if the tty is NOT a master pty.
2384 */
2385 if (tty == real_tty && current->signal->tty != real_tty)
2386 return -ENOTTY;
2387 if (!real_tty->session)
2388 return -ENOTTY;
2389 return put_user(pid_vnr(real_tty->session), p);
2390}
2391
2392/**
2393 * tiocsetd - set line discipline
2394 * @tty: tty device
2395 * @p: pointer to user data
2396 *
2397 * Set the line discipline according to user request.
2398 *
2399 * Locking: see tty_set_ldisc, this function is just a helper
2400 */
2401
2402static int tiocsetd(struct tty_struct *tty, int __user *p)
2403{
2404 int ldisc;
2405 int ret;
2406
2407 if (get_user(ldisc, p))
2408 return -EFAULT;
2409
2410 ret = tty_set_ldisc(tty, ldisc);
2411
2412 return ret;
2413}
2414
2415/**
2416 * send_break - performed time break
2417 * @tty: device to break on
2418 * @duration: timeout in mS
2419 *
2420 * Perform a timed break on hardware that lacks its own driver level
2421 * timed break functionality.
2422 *
2423 * Locking:
2424 * atomic_write_lock serializes
2425 *
2426 */
2427
2428static int send_break(struct tty_struct *tty, unsigned int duration)
2429{
2430 int retval;
2431
2432 if (tty->ops->break_ctl == NULL)
2433 return 0;
2434
2435 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2436 retval = tty->ops->break_ctl(tty, duration);
2437 else {
2438 /* Do the work ourselves */
2439 if (tty_write_lock(tty, 0) < 0)
2440 return -EINTR;
2441 retval = tty->ops->break_ctl(tty, -1);
2442 if (retval)
2443 goto out;
2444 if (!signal_pending(current))
2445 msleep_interruptible(duration);
2446 retval = tty->ops->break_ctl(tty, 0);
2447out:
2448 tty_write_unlock(tty);
2449 if (signal_pending(current))
2450 retval = -EINTR;
2451 }
2452 return retval;
2453}
2454
2455/**
2456 * tty_tiocmget - get modem status
2457 * @tty: tty device
2458 * @file: user file pointer
2459 * @p: pointer to result
2460 *
2461 * Obtain the modem status bits from the tty driver if the feature
2462 * is supported. Return -EINVAL if it is not available.
2463 *
2464 * Locking: none (up to the driver)
2465 */
2466
2467static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2468{
2469 int retval = -EINVAL;
2470
2471 if (tty->ops->tiocmget) {
2472 retval = tty->ops->tiocmget(tty);
2473
2474 if (retval >= 0)
2475 retval = put_user(retval, p);
2476 }
2477 return retval;
2478}
2479
2480/**
2481 * tty_tiocmset - set modem status
2482 * @tty: tty device
2483 * @cmd: command - clear bits, set bits or set all
2484 * @p: pointer to desired bits
2485 *
2486 * Set the modem status bits from the tty driver if the feature
2487 * is supported. Return -EINVAL if it is not available.
2488 *
2489 * Locking: none (up to the driver)
2490 */
2491
2492static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2493 unsigned __user *p)
2494{
2495 int retval;
2496 unsigned int set, clear, val;
2497
2498 if (tty->ops->tiocmset == NULL)
2499 return -EINVAL;
2500
2501 retval = get_user(val, p);
2502 if (retval)
2503 return retval;
2504 set = clear = 0;
2505 switch (cmd) {
2506 case TIOCMBIS:
2507 set = val;
2508 break;
2509 case TIOCMBIC:
2510 clear = val;
2511 break;
2512 case TIOCMSET:
2513 set = val;
2514 clear = ~val;
2515 break;
2516 }
2517 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2518 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2519 return tty->ops->tiocmset(tty, set, clear);
2520}
2521
2522static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2523{
2524 int retval = -EINVAL;
2525 struct serial_icounter_struct icount;
2526 memset(&icount, 0, sizeof(icount));
2527 if (tty->ops->get_icount)
2528 retval = tty->ops->get_icount(tty, &icount);
2529 if (retval != 0)
2530 return retval;
2531 if (copy_to_user(arg, &icount, sizeof(icount)))
2532 return -EFAULT;
2533 return 0;
2534}
2535
2536struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2537{
2538 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2539 tty->driver->subtype == PTY_TYPE_MASTER)
2540 tty = tty->link;
2541 return tty;
2542}
2543EXPORT_SYMBOL(tty_pair_get_tty);
2544
2545struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
2546{
2547 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2548 tty->driver->subtype == PTY_TYPE_MASTER)
2549 return tty;
2550 return tty->link;
2551}
2552EXPORT_SYMBOL(tty_pair_get_pty);
2553
2554/*
2555 * Split this up, as gcc can choke on it otherwise..
2556 */
2557long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2558{
2559 struct tty_struct *tty = file_tty(file);
2560 struct tty_struct *real_tty;
2561 void __user *p = (void __user *)arg;
2562 int retval;
2563 struct tty_ldisc *ld;
2564 struct inode *inode = file->f_dentry->d_inode;
2565
2566 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2567 return -EINVAL;
2568
2569 real_tty = tty_pair_get_tty(tty);
2570
2571 /*
2572 * Factor out some common prep work
2573 */
2574 switch (cmd) {
2575 case TIOCSETD:
2576 case TIOCSBRK:
2577 case TIOCCBRK:
2578 case TCSBRK:
2579 case TCSBRKP:
2580 retval = tty_check_change(tty);
2581 if (retval)
2582 return retval;
2583 if (cmd != TIOCCBRK) {
2584 tty_wait_until_sent(tty, 0);
2585 if (signal_pending(current))
2586 return -EINTR;
2587 }
2588 break;
2589 }
2590
2591 /*
2592 * Now do the stuff.
2593 */
2594 switch (cmd) {
2595 case TIOCSTI:
2596 return tiocsti(tty, p);
2597 case TIOCGWINSZ:
2598 return tiocgwinsz(real_tty, p);
2599 case TIOCSWINSZ:
2600 return tiocswinsz(real_tty, p);
2601 case TIOCCONS:
2602 return real_tty != tty ? -EINVAL : tioccons(file);
2603 case FIONBIO:
2604 return fionbio(file, p);
2605 case TIOCEXCL:
2606 set_bit(TTY_EXCLUSIVE, &tty->flags);
2607 return 0;
2608 case TIOCNXCL:
2609 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2610 return 0;
2611 case TIOCNOTTY:
2612 if (current->signal->tty != tty)
2613 return -ENOTTY;
2614 no_tty();
2615 return 0;
2616 case TIOCSCTTY:
2617 return tiocsctty(tty, arg);
2618 case TIOCGPGRP:
2619 return tiocgpgrp(tty, real_tty, p);
2620 case TIOCSPGRP:
2621 return tiocspgrp(tty, real_tty, p);
2622 case TIOCGSID:
2623 return tiocgsid(tty, real_tty, p);
2624 case TIOCGETD:
2625 return put_user(tty->ldisc->ops->num, (int __user *)p);
2626 case TIOCSETD:
2627 return tiocsetd(tty, p);
2628 case TIOCVHANGUP:
2629 if (!capable(CAP_SYS_ADMIN))
2630 return -EPERM;
2631 tty_vhangup(tty);
2632 return 0;
2633 case TIOCGDEV:
2634 {
2635 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2636 return put_user(ret, (unsigned int __user *)p);
2637 }
2638 /*
2639 * Break handling
2640 */
2641 case TIOCSBRK: /* Turn break on, unconditionally */
2642 if (tty->ops->break_ctl)
2643 return tty->ops->break_ctl(tty, -1);
2644 return 0;
2645 case TIOCCBRK: /* Turn break off, unconditionally */
2646 if (tty->ops->break_ctl)
2647 return tty->ops->break_ctl(tty, 0);
2648 return 0;
2649 case TCSBRK: /* SVID version: non-zero arg --> no break */
2650 /* non-zero arg means wait for all output data
2651 * to be sent (performed above) but don't send break.
2652 * This is used by the tcdrain() termios function.
2653 */
2654 if (!arg)
2655 return send_break(tty, 250);
2656 return 0;
2657 case TCSBRKP: /* support for POSIX tcsendbreak() */
2658 return send_break(tty, arg ? arg*100 : 250);
2659
2660 case TIOCMGET:
2661 return tty_tiocmget(tty, p);
2662 case TIOCMSET:
2663 case TIOCMBIC:
2664 case TIOCMBIS:
2665 return tty_tiocmset(tty, cmd, p);
2666 case TIOCGICOUNT:
2667 retval = tty_tiocgicount(tty, p);
2668 /* For the moment allow fall through to the old method */
2669 if (retval != -EINVAL)
2670 return retval;
2671 break;
2672 case TCFLSH:
2673 switch (arg) {
2674 case TCIFLUSH:
2675 case TCIOFLUSH:
2676 /* flush tty buffer and allow ldisc to process ioctl */
2677 tty_buffer_flush(tty);
2678 break;
2679 }
2680 break;
2681 }
2682 if (tty->ops->ioctl) {
2683 retval = (tty->ops->ioctl)(tty, cmd, arg);
2684 if (retval != -ENOIOCTLCMD)
2685 return retval;
2686 }
2687 ld = tty_ldisc_ref_wait(tty);
2688 retval = -EINVAL;
2689 if (ld->ops->ioctl) {
2690 retval = ld->ops->ioctl(tty, file, cmd, arg);
2691 if (retval == -ENOIOCTLCMD)
2692 retval = -EINVAL;
2693 }
2694 tty_ldisc_deref(ld);
2695 return retval;
2696}
2697
2698#ifdef CONFIG_COMPAT
2699static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2700 unsigned long arg)
2701{
2702 struct inode *inode = file->f_dentry->d_inode;
2703 struct tty_struct *tty = file_tty(file);
2704 struct tty_ldisc *ld;
2705 int retval = -ENOIOCTLCMD;
2706
2707 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2708 return -EINVAL;
2709
2710 if (tty->ops->compat_ioctl) {
2711 retval = (tty->ops->compat_ioctl)(tty, cmd, arg);
2712 if (retval != -ENOIOCTLCMD)
2713 return retval;
2714 }
2715
2716 ld = tty_ldisc_ref_wait(tty);
2717 if (ld->ops->compat_ioctl)
2718 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2719 tty_ldisc_deref(ld);
2720
2721 return retval;
2722}
2723#endif
2724
2725/*
2726 * This implements the "Secure Attention Key" --- the idea is to
2727 * prevent trojan horses by killing all processes associated with this
2728 * tty when the user hits the "Secure Attention Key". Required for
2729 * super-paranoid applications --- see the Orange Book for more details.
2730 *
2731 * This code could be nicer; ideally it should send a HUP, wait a few
2732 * seconds, then send a INT, and then a KILL signal. But you then
2733 * have to coordinate with the init process, since all processes associated
2734 * with the current tty must be dead before the new getty is allowed
2735 * to spawn.
2736 *
2737 * Now, if it would be correct ;-/ The current code has a nasty hole -
2738 * it doesn't catch files in flight. We may send the descriptor to ourselves
2739 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2740 *
2741 * Nasty bug: do_SAK is being called in interrupt context. This can
2742 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2743 */
2744void __do_SAK(struct tty_struct *tty)
2745{
2746#ifdef TTY_SOFT_SAK
2747 tty_hangup(tty);
2748#else
2749 struct task_struct *g, *p;
2750 struct pid *session;
2751 int i;
2752 struct file *filp;
2753 struct fdtable *fdt;
2754
2755 if (!tty)
2756 return;
2757 session = tty->session;
2758
2759 tty_ldisc_flush(tty);
2760
2761 tty_driver_flush_buffer(tty);
2762
2763 read_lock(&tasklist_lock);
2764 /* Kill the entire session */
2765 do_each_pid_task(session, PIDTYPE_SID, p) {
2766 printk(KERN_NOTICE "SAK: killed process %d"
2767 " (%s): task_session(p)==tty->session\n",
2768 task_pid_nr(p), p->comm);
2769 send_sig(SIGKILL, p, 1);
2770 } while_each_pid_task(session, PIDTYPE_SID, p);
2771 /* Now kill any processes that happen to have the
2772 * tty open.
2773 */
2774 do_each_thread(g, p) {
2775 if (p->signal->tty == tty) {
2776 printk(KERN_NOTICE "SAK: killed process %d"
2777 " (%s): task_session(p)==tty->session\n",
2778 task_pid_nr(p), p->comm);
2779 send_sig(SIGKILL, p, 1);
2780 continue;
2781 }
2782 task_lock(p);
2783 if (p->files) {
2784 /*
2785 * We don't take a ref to the file, so we must
2786 * hold ->file_lock instead.
2787 */
2788 spin_lock(&p->files->file_lock);
2789 fdt = files_fdtable(p->files);
2790 for (i = 0; i < fdt->max_fds; i++) {
2791 filp = fcheck_files(p->files, i);
2792 if (!filp)
2793 continue;
2794 if (filp->f_op->read == tty_read &&
2795 file_tty(filp) == tty) {
2796 printk(KERN_NOTICE "SAK: killed process %d"
2797 " (%s): fd#%d opened to the tty\n",
2798 task_pid_nr(p), p->comm, i);
2799 force_sig(SIGKILL, p);
2800 break;
2801 }
2802 }
2803 spin_unlock(&p->files->file_lock);
2804 }
2805 task_unlock(p);
2806 } while_each_thread(g, p);
2807 read_unlock(&tasklist_lock);
2808#endif
2809}
2810
2811static void do_SAK_work(struct work_struct *work)
2812{
2813 struct tty_struct *tty =
2814 container_of(work, struct tty_struct, SAK_work);
2815 __do_SAK(tty);
2816}
2817
2818/*
2819 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2820 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2821 * the values which we write to it will be identical to the values which it
2822 * already has. --akpm
2823 */
2824void do_SAK(struct tty_struct *tty)
2825{
2826 if (!tty)
2827 return;
2828 schedule_work(&tty->SAK_work);
2829}
2830
2831EXPORT_SYMBOL(do_SAK);
2832
2833static int dev_match_devt(struct device *dev, void *data)
2834{
2835 dev_t *devt = data;
2836 return dev->devt == *devt;
2837}
2838
2839/* Must put_device() after it's unused! */
2840static struct device *tty_get_device(struct tty_struct *tty)
2841{
2842 dev_t devt = tty_devnum(tty);
2843 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2844}
2845
2846
2847/**
2848 * initialize_tty_struct
2849 * @tty: tty to initialize
2850 *
2851 * This subroutine initializes a tty structure that has been newly
2852 * allocated.
2853 *
2854 * Locking: none - tty in question must not be exposed at this point
2855 */
2856
2857void initialize_tty_struct(struct tty_struct *tty,
2858 struct tty_driver *driver, int idx)
2859{
2860 memset(tty, 0, sizeof(struct tty_struct));
2861 kref_init(&tty->kref);
2862 tty->magic = TTY_MAGIC;
2863 tty_ldisc_init(tty);
2864 tty->session = NULL;
2865 tty->pgrp = NULL;
2866 tty->overrun_time = jiffies;
2867 tty->buf.head = tty->buf.tail = NULL;
2868 tty_buffer_init(tty);
2869 mutex_init(&tty->termios_mutex);
2870 mutex_init(&tty->ldisc_mutex);
2871 init_waitqueue_head(&tty->write_wait);
2872 init_waitqueue_head(&tty->read_wait);
2873 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2874 mutex_init(&tty->atomic_read_lock);
2875 mutex_init(&tty->atomic_write_lock);
2876 mutex_init(&tty->output_lock);
2877 mutex_init(&tty->echo_lock);
2878 spin_lock_init(&tty->read_lock);
2879 spin_lock_init(&tty->ctrl_lock);
2880 INIT_LIST_HEAD(&tty->tty_files);
2881 INIT_WORK(&tty->SAK_work, do_SAK_work);
2882
2883 tty->driver = driver;
2884 tty->ops = driver->ops;
2885 tty->index = idx;
2886 tty_line_name(driver, idx, tty->name);
2887 tty->dev = tty_get_device(tty);
2888}
2889
2890/**
2891 * deinitialize_tty_struct
2892 * @tty: tty to deinitialize
2893 *
2894 * This subroutine deinitializes a tty structure that has been newly
2895 * allocated but tty_release cannot be called on that yet.
2896 *
2897 * Locking: none - tty in question must not be exposed at this point
2898 */
2899void deinitialize_tty_struct(struct tty_struct *tty)
2900{
2901 tty_ldisc_deinit(tty);
2902}
2903
2904/**
2905 * tty_put_char - write one character to a tty
2906 * @tty: tty
2907 * @ch: character
2908 *
2909 * Write one byte to the tty using the provided put_char method
2910 * if present. Returns the number of characters successfully output.
2911 *
2912 * Note: the specific put_char operation in the driver layer may go
2913 * away soon. Don't call it directly, use this method
2914 */
2915
2916int tty_put_char(struct tty_struct *tty, unsigned char ch)
2917{
2918 if (tty->ops->put_char)
2919 return tty->ops->put_char(tty, ch);
2920 return tty->ops->write(tty, &ch, 1);
2921}
2922EXPORT_SYMBOL_GPL(tty_put_char);
2923
2924struct class *tty_class;
2925
2926/**
2927 * tty_register_device - register a tty device
2928 * @driver: the tty driver that describes the tty device
2929 * @index: the index in the tty driver for this tty device
2930 * @device: a struct device that is associated with this tty device.
2931 * This field is optional, if there is no known struct device
2932 * for this tty device it can be set to NULL safely.
2933 *
2934 * Returns a pointer to the struct device for this tty device
2935 * (or ERR_PTR(-EFOO) on error).
2936 *
2937 * This call is required to be made to register an individual tty device
2938 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2939 * that bit is not set, this function should not be called by a tty
2940 * driver.
2941 *
2942 * Locking: ??
2943 */
2944
2945struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2946 struct device *device)
2947{
2948 char name[64];
2949 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2950
2951 if (index >= driver->num) {
2952 printk(KERN_ERR "Attempt to register invalid tty line number "
2953 " (%d).\n", index);
2954 return ERR_PTR(-EINVAL);
2955 }
2956
2957 if (driver->type == TTY_DRIVER_TYPE_PTY)
2958 pty_line_name(driver, index, name);
2959 else
2960 tty_line_name(driver, index, name);
2961
2962 return device_create(tty_class, device, dev, NULL, name);
2963}
2964EXPORT_SYMBOL(tty_register_device);
2965
2966/**
2967 * tty_unregister_device - unregister a tty device
2968 * @driver: the tty driver that describes the tty device
2969 * @index: the index in the tty driver for this tty device
2970 *
2971 * If a tty device is registered with a call to tty_register_device() then
2972 * this function must be called when the tty device is gone.
2973 *
2974 * Locking: ??
2975 */
2976
2977void tty_unregister_device(struct tty_driver *driver, unsigned index)
2978{
2979 device_destroy(tty_class,
2980 MKDEV(driver->major, driver->minor_start) + index);
2981}
2982EXPORT_SYMBOL(tty_unregister_device);
2983
2984struct tty_driver *alloc_tty_driver(int lines)
2985{
2986 struct tty_driver *driver;
2987
2988 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2989 if (driver) {
2990 kref_init(&driver->kref);
2991 driver->magic = TTY_DRIVER_MAGIC;
2992 driver->num = lines;
2993 /* later we'll move allocation of tables here */
2994 }
2995 return driver;
2996}
2997EXPORT_SYMBOL(alloc_tty_driver);
2998
2999static void destruct_tty_driver(struct kref *kref)
3000{
3001 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3002 int i;
3003 struct ktermios *tp;
3004 void *p;
3005
3006 if (driver->flags & TTY_DRIVER_INSTALLED) {
3007 /*
3008 * Free the termios and termios_locked structures because
3009 * we don't want to get memory leaks when modular tty
3010 * drivers are removed from the kernel.
3011 */
3012 for (i = 0; i < driver->num; i++) {
3013 tp = driver->termios[i];
3014 if (tp) {
3015 driver->termios[i] = NULL;
3016 kfree(tp);
3017 }
3018 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3019 tty_unregister_device(driver, i);
3020 }
3021 p = driver->ttys;
3022 proc_tty_unregister_driver(driver);
3023 driver->ttys = NULL;
3024 driver->termios = NULL;
3025 kfree(p);
3026 cdev_del(&driver->cdev);
3027 }
3028 kfree(driver);
3029}
3030
3031void tty_driver_kref_put(struct tty_driver *driver)
3032{
3033 kref_put(&driver->kref, destruct_tty_driver);
3034}
3035EXPORT_SYMBOL(tty_driver_kref_put);
3036
3037void tty_set_operations(struct tty_driver *driver,
3038 const struct tty_operations *op)
3039{
3040 driver->ops = op;
3041};
3042EXPORT_SYMBOL(tty_set_operations);
3043
3044void put_tty_driver(struct tty_driver *d)
3045{
3046 tty_driver_kref_put(d);
3047}
3048EXPORT_SYMBOL(put_tty_driver);
3049
3050/*
3051 * Called by a tty driver to register itself.
3052 */
3053int tty_register_driver(struct tty_driver *driver)
3054{
3055 int error;
3056 int i;
3057 dev_t dev;
3058 void **p = NULL;
3059 struct device *d;
3060
3061 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3062 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
3063 if (!p)
3064 return -ENOMEM;
3065 }
3066
3067 if (!driver->major) {
3068 error = alloc_chrdev_region(&dev, driver->minor_start,
3069 driver->num, driver->name);
3070 if (!error) {
3071 driver->major = MAJOR(dev);
3072 driver->minor_start = MINOR(dev);
3073 }
3074 } else {
3075 dev = MKDEV(driver->major, driver->minor_start);
3076 error = register_chrdev_region(dev, driver->num, driver->name);
3077 }
3078 if (error < 0) {
3079 kfree(p);
3080 return error;
3081 }
3082
3083 if (p) {
3084 driver->ttys = (struct tty_struct **)p;
3085 driver->termios = (struct ktermios **)(p + driver->num);
3086 } else {
3087 driver->ttys = NULL;
3088 driver->termios = NULL;
3089 }
3090
3091 cdev_init(&driver->cdev, &tty_fops);
3092 driver->cdev.owner = driver->owner;
3093 error = cdev_add(&driver->cdev, dev, driver->num);
3094 if (error) {
3095 unregister_chrdev_region(dev, driver->num);
3096 driver->ttys = NULL;
3097 driver->termios = NULL;
3098 kfree(p);
3099 return error;
3100 }
3101
3102 mutex_lock(&tty_mutex);
3103 list_add(&driver->tty_drivers, &tty_drivers);
3104 mutex_unlock(&tty_mutex);
3105
3106 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3107 for (i = 0; i < driver->num; i++) {
3108 d = tty_register_device(driver, i, NULL);
3109 if (IS_ERR(d)) {
3110 error = PTR_ERR(d);
3111 goto err;
3112 }
3113 }
3114 }
3115 proc_tty_register_driver(driver);
3116 driver->flags |= TTY_DRIVER_INSTALLED;
3117 return 0;
3118
3119err:
3120 for (i--; i >= 0; i--)
3121 tty_unregister_device(driver, i);
3122
3123 mutex_lock(&tty_mutex);
3124 list_del(&driver->tty_drivers);
3125 mutex_unlock(&tty_mutex);
3126
3127 unregister_chrdev_region(dev, driver->num);
3128 driver->ttys = NULL;
3129 driver->termios = NULL;
3130 kfree(p);
3131 return error;
3132}
3133
3134EXPORT_SYMBOL(tty_register_driver);
3135
3136/*
3137 * Called by a tty driver to unregister itself.
3138 */
3139int tty_unregister_driver(struct tty_driver *driver)
3140{
3141#if 0
3142 /* FIXME */
3143 if (driver->refcount)
3144 return -EBUSY;
3145#endif
3146 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3147 driver->num);
3148 mutex_lock(&tty_mutex);
3149 list_del(&driver->tty_drivers);
3150 mutex_unlock(&tty_mutex);
3151 return 0;
3152}
3153
3154EXPORT_SYMBOL(tty_unregister_driver);
3155
3156dev_t tty_devnum(struct tty_struct *tty)
3157{
3158 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3159}
3160EXPORT_SYMBOL(tty_devnum);
3161
3162void proc_clear_tty(struct task_struct *p)
3163{
3164 unsigned long flags;
3165 struct tty_struct *tty;
3166 spin_lock_irqsave(&p->sighand->siglock, flags);
3167 tty = p->signal->tty;
3168 p->signal->tty = NULL;
3169 spin_unlock_irqrestore(&p->sighand->siglock, flags);
3170 tty_kref_put(tty);
3171}
3172
3173/* Called under the sighand lock */
3174
3175static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3176{
3177 if (tty) {
3178 unsigned long flags;
3179 /* We should not have a session or pgrp to put here but.... */
3180 spin_lock_irqsave(&tty->ctrl_lock, flags);
3181 put_pid(tty->session);
3182 put_pid(tty->pgrp);
3183 tty->pgrp = get_pid(task_pgrp(tsk));
3184 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3185 tty->session = get_pid(task_session(tsk));
3186 if (tsk->signal->tty) {
3187 printk(KERN_DEBUG "tty not NULL!!\n");
3188 tty_kref_put(tsk->signal->tty);
3189 }
3190 }
3191 put_pid(tsk->signal->tty_old_pgrp);
3192 tsk->signal->tty = tty_kref_get(tty);
3193 tsk->signal->tty_old_pgrp = NULL;
3194}
3195
3196static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3197{
3198 spin_lock_irq(&tsk->sighand->siglock);
3199 __proc_set_tty(tsk, tty);
3200 spin_unlock_irq(&tsk->sighand->siglock);
3201}
3202
3203struct tty_struct *get_current_tty(void)
3204{
3205 struct tty_struct *tty;
3206 unsigned long flags;
3207
3208 spin_lock_irqsave(¤t->sighand->siglock, flags);
3209 tty = tty_kref_get(current->signal->tty);
3210 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
3211 return tty;
3212}
3213EXPORT_SYMBOL_GPL(get_current_tty);
3214
3215void tty_default_fops(struct file_operations *fops)
3216{
3217 *fops = tty_fops;
3218}
3219
3220/*
3221 * Initialize the console device. This is called *early*, so
3222 * we can't necessarily depend on lots of kernel help here.
3223 * Just do some early initializations, and do the complex setup
3224 * later.
3225 */
3226void __init console_init(void)
3227{
3228 initcall_t *call;
3229
3230 /* Setup the default TTY line discipline. */
3231 tty_ldisc_begin();
3232
3233 /*
3234 * set up the console device so that later boot sequences can
3235 * inform about problems etc..
3236 */
3237 call = __con_initcall_start;
3238 while (call < __con_initcall_end) {
3239 (*call)();
3240 call++;
3241 }
3242}
3243
3244static char *tty_devnode(struct device *dev, mode_t *mode)
3245{
3246 if (!mode)
3247 return NULL;
3248 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3249 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3250 *mode = 0666;
3251 return NULL;
3252}
3253
3254static int __init tty_class_init(void)
3255{
3256 tty_class = class_create(THIS_MODULE, "tty");
3257 if (IS_ERR(tty_class))
3258 return PTR_ERR(tty_class);
3259 tty_class->devnode = tty_devnode;
3260 return 0;
3261}
3262
3263postcore_initcall(tty_class_init);
3264
3265/* 3/2004 jmc: why do these devices exist? */
3266static struct cdev tty_cdev, console_cdev;
3267
3268static ssize_t show_cons_active(struct device *dev,
3269 struct device_attribute *attr, char *buf)
3270{
3271 struct console *cs[16];
3272 int i = 0;
3273 struct console *c;
3274 ssize_t count = 0;
3275
3276 console_lock();
3277 for_each_console(c) {
3278 if (!c->device)
3279 continue;
3280 if (!c->write)
3281 continue;
3282 if ((c->flags & CON_ENABLED) == 0)
3283 continue;
3284 cs[i++] = c;
3285 if (i >= ARRAY_SIZE(cs))
3286 break;
3287 }
3288 while (i--)
3289 count += sprintf(buf + count, "%s%d%c",
3290 cs[i]->name, cs[i]->index, i ? ' ':'\n');
3291 console_unlock();
3292
3293 return count;
3294}
3295static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3296
3297static struct device *consdev;
3298
3299void console_sysfs_notify(void)
3300{
3301 if (consdev)
3302 sysfs_notify(&consdev->kobj, NULL, "active");
3303}
3304
3305/*
3306 * Ok, now we can initialize the rest of the tty devices and can count
3307 * on memory allocations, interrupts etc..
3308 */
3309int __init tty_init(void)
3310{
3311 cdev_init(&tty_cdev, &tty_fops);
3312 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3313 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3314 panic("Couldn't register /dev/tty driver\n");
3315 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3316
3317 cdev_init(&console_cdev, &console_fops);
3318 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3319 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3320 panic("Couldn't register /dev/console driver\n");
3321 consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3322 "console");
3323 if (IS_ERR(consdev))
3324 consdev = NULL;
3325 else
3326 WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
3327
3328#ifdef CONFIG_VT
3329 vty_init(&console_fops);
3330#endif
3331 return 0;
3332}
3333
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}