1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
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.
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
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.
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
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).
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
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.
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
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
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
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
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>
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 #include <linux/fs.h>
106 #include <linux/kbd_kern.h>
107 #include <linux/vt_kern.h>
108 #include <linux/selection.h>
110 #include <linux/kmod.h>
111 #include <linux/nsproxy.h>
114 #undef TTY_DEBUG_HANGUP
115 #ifdef TTY_DEBUG_HANGUP
116 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
118 # define tty_debug_hangup(tty, f, args...) do { } while (0)
121 #define TTY_PARANOIA_CHECK 1
122 #define CHECK_TTY_COUNT 1
124 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
125 .c_iflag = ICRNL | IXON,
126 .c_oflag = OPOST | ONLCR,
127 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
128 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
129 ECHOCTL | ECHOKE | IEXTEN,
133 /* .c_line = N_TTY, */
135 EXPORT_SYMBOL(tty_std_termios);
137 /* This list gets poked at by procfs and various bits of boot up code. This
138 * could do with some rationalisation such as pulling the tty proc function
142 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
144 /* Mutex to protect creating and releasing a tty */
145 DEFINE_MUTEX(tty_mutex);
147 static ssize_t tty_read(struct kiocb *, struct iov_iter *);
148 static ssize_t tty_write(struct kiocb *, struct iov_iter *);
149 static __poll_t tty_poll(struct file *, poll_table *);
150 static int tty_open(struct inode *, struct file *);
152 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
155 #define tty_compat_ioctl NULL
157 static int __tty_fasync(int fd, struct file *filp, int on);
158 static int tty_fasync(int fd, struct file *filp, int on);
159 static void release_tty(struct tty_struct *tty, int idx);
162 * free_tty_struct - free a disused tty
163 * @tty: tty struct to free
165 * Free the write buffers, tty queue and tty memory itself.
167 * Locking: none. Must be called after tty is definitely unused
169 static void free_tty_struct(struct tty_struct *tty)
171 tty_ldisc_deinit(tty);
172 put_device(tty->dev);
173 kvfree(tty->write_buf);
177 static inline struct tty_struct *file_tty(struct file *file)
179 return ((struct tty_file_private *)file->private_data)->tty;
182 int tty_alloc_file(struct file *file)
184 struct tty_file_private *priv;
186 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
190 file->private_data = priv;
195 /* Associate a new file with the tty structure */
196 void tty_add_file(struct tty_struct *tty, struct file *file)
198 struct tty_file_private *priv = file->private_data;
203 spin_lock(&tty->files_lock);
204 list_add(&priv->list, &tty->tty_files);
205 spin_unlock(&tty->files_lock);
209 * tty_free_file - free file->private_data
210 * @file: to free private_data of
212 * This shall be used only for fail path handling when tty_add_file was not
215 void tty_free_file(struct file *file)
217 struct tty_file_private *priv = file->private_data;
219 file->private_data = NULL;
223 /* Delete file from its tty */
224 static void tty_del_file(struct file *file)
226 struct tty_file_private *priv = file->private_data;
227 struct tty_struct *tty = priv->tty;
229 spin_lock(&tty->files_lock);
230 list_del(&priv->list);
231 spin_unlock(&tty->files_lock);
236 * tty_name - return tty naming
237 * @tty: tty structure
239 * Convert a tty structure into a name. The name reflects the kernel naming
240 * policy and if udev is in use may not reflect user space
244 const char *tty_name(const struct tty_struct *tty)
246 if (!tty) /* Hmm. NULL pointer. That's fun. */
250 EXPORT_SYMBOL(tty_name);
252 const char *tty_driver_name(const struct tty_struct *tty)
254 if (!tty || !tty->driver)
256 return tty->driver->name;
259 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
262 #ifdef TTY_PARANOIA_CHECK
264 pr_warn("(%d:%d): %s: NULL tty\n",
265 imajor(inode), iminor(inode), routine);
272 /* Caller must hold tty_lock */
273 static int check_tty_count(struct tty_struct *tty, const char *routine)
275 #ifdef CHECK_TTY_COUNT
277 int count = 0, kopen_count = 0;
279 spin_lock(&tty->files_lock);
280 list_for_each(p, &tty->tty_files) {
283 spin_unlock(&tty->files_lock);
284 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
285 tty->driver->subtype == PTY_TYPE_SLAVE &&
286 tty->link && tty->link->count)
288 if (tty_port_kopened(tty->port))
290 if (tty->count != (count + kopen_count)) {
291 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
292 routine, tty->count, count, kopen_count);
293 return (count + kopen_count);
300 * get_tty_driver - find device of a tty
301 * @device: device identifier
302 * @index: returns the index of the tty
304 * This routine returns a tty driver structure, given a device number and also
305 * passes back the index number.
307 * Locking: caller must hold tty_mutex
309 static struct tty_driver *get_tty_driver(dev_t device, int *index)
311 struct tty_driver *p;
313 list_for_each_entry(p, &tty_drivers, tty_drivers) {
314 dev_t base = MKDEV(p->major, p->minor_start);
316 if (device < base || device >= base + p->num)
318 *index = device - base;
319 return tty_driver_kref_get(p);
325 * tty_dev_name_to_number - return dev_t for device name
326 * @name: user space name of device under /dev
327 * @number: pointer to dev_t that this function will populate
329 * This function converts device names like ttyS0 or ttyUSB1 into dev_t like
330 * (4, 64) or (188, 1). If no corresponding driver is registered then the
331 * function returns -%ENODEV.
333 * Locking: this acquires tty_mutex to protect the tty_drivers list from
334 * being modified while we are traversing it, and makes sure to
335 * release it before exiting.
337 int tty_dev_name_to_number(const char *name, dev_t *number)
339 struct tty_driver *p;
341 int index, prefix_length = 0;
344 for (str = name; *str && !isdigit(*str); str++)
350 ret = kstrtoint(str, 10, &index);
354 prefix_length = str - name;
355 mutex_lock(&tty_mutex);
357 list_for_each_entry(p, &tty_drivers, tty_drivers)
358 if (prefix_length == strlen(p->name) && strncmp(name,
359 p->name, prefix_length) == 0) {
360 if (index < p->num) {
361 *number = MKDEV(p->major, p->minor_start + index);
366 /* if here then driver wasn't found */
369 mutex_unlock(&tty_mutex);
372 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
374 #ifdef CONFIG_CONSOLE_POLL
377 * tty_find_polling_driver - find device of a polled tty
378 * @name: name string to match
379 * @line: pointer to resulting tty line nr
381 * This routine returns a tty driver structure, given a name and the condition
382 * that the tty driver is capable of polled operation.
384 struct tty_driver *tty_find_polling_driver(char *name, int *line)
386 struct tty_driver *p, *res = NULL;
391 for (str = name; *str; str++)
392 if ((*str >= '0' && *str <= '9') || *str == ',')
398 tty_line = simple_strtoul(str, &str, 10);
400 mutex_lock(&tty_mutex);
401 /* Search through the tty devices to look for a match */
402 list_for_each_entry(p, &tty_drivers, tty_drivers) {
403 if (!len || strncmp(name, p->name, len) != 0)
411 if (tty_line >= 0 && tty_line < p->num && p->ops &&
412 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
413 res = tty_driver_kref_get(p);
418 mutex_unlock(&tty_mutex);
422 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
425 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
430 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
435 /* No kernel lock held - none needed ;) */
436 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
438 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
441 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
444 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
447 static long hung_up_tty_compat_ioctl(struct file *file,
448 unsigned int cmd, unsigned long arg)
450 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
453 static int hung_up_tty_fasync(int fd, struct file *file, int on)
458 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
460 struct tty_struct *tty = file_tty(file);
462 if (tty && tty->ops && tty->ops->show_fdinfo)
463 tty->ops->show_fdinfo(tty, m);
466 static const struct file_operations tty_fops = {
468 .read_iter = tty_read,
469 .write_iter = tty_write,
470 .splice_read = copy_splice_read,
471 .splice_write = iter_file_splice_write,
473 .unlocked_ioctl = tty_ioctl,
474 .compat_ioctl = tty_compat_ioctl,
476 .release = tty_release,
477 .fasync = tty_fasync,
478 .show_fdinfo = tty_show_fdinfo,
481 static const struct file_operations console_fops = {
483 .read_iter = tty_read,
484 .write_iter = redirected_tty_write,
485 .splice_read = copy_splice_read,
486 .splice_write = iter_file_splice_write,
488 .unlocked_ioctl = tty_ioctl,
489 .compat_ioctl = tty_compat_ioctl,
491 .release = tty_release,
492 .fasync = tty_fasync,
495 static const struct file_operations hung_up_tty_fops = {
497 .read_iter = hung_up_tty_read,
498 .write_iter = hung_up_tty_write,
499 .poll = hung_up_tty_poll,
500 .unlocked_ioctl = hung_up_tty_ioctl,
501 .compat_ioctl = hung_up_tty_compat_ioctl,
502 .release = tty_release,
503 .fasync = hung_up_tty_fasync,
506 static DEFINE_SPINLOCK(redirect_lock);
507 static struct file *redirect;
510 * tty_wakeup - request more data
513 * Internal and external helper for wakeups of tty. This function informs the
514 * line discipline if present that the driver is ready to receive more output
517 void tty_wakeup(struct tty_struct *tty)
519 struct tty_ldisc *ld;
521 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
522 ld = tty_ldisc_ref(tty);
524 if (ld->ops->write_wakeup)
525 ld->ops->write_wakeup(tty);
529 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
531 EXPORT_SYMBOL_GPL(tty_wakeup);
534 * tty_release_redirect - Release a redirect on a pty if present
537 * This is available to the pty code so if the master closes, if the slave is a
538 * redirect it can release the redirect.
540 static struct file *tty_release_redirect(struct tty_struct *tty)
542 struct file *f = NULL;
544 spin_lock(&redirect_lock);
545 if (redirect && file_tty(redirect) == tty) {
549 spin_unlock(&redirect_lock);
555 * __tty_hangup - actual handler for hangup events
557 * @exit_session: if non-zero, signal all foreground group processes
559 * This can be called by a "kworker" kernel thread. That is process synchronous
560 * but doesn't hold any locks, so we need to make sure we have the appropriate
561 * locks for what we're doing.
563 * The hangup event clears any pending redirections onto the hung up device. It
564 * ensures future writes will error and it does the needed line discipline
565 * hangup and signal delivery. The tty object itself remains intact.
570 * * redirect lock for undoing redirection
571 * * file list lock for manipulating list of ttys
572 * * tty_ldiscs_lock from called functions
573 * * termios_rwsem resetting termios data
574 * * tasklist_lock to walk task list for hangup event
576 * * ->siglock to protect ->signal/->sighand
579 static void __tty_hangup(struct tty_struct *tty, int exit_session)
581 struct file *cons_filp = NULL;
582 struct file *filp, *f;
583 struct tty_file_private *priv;
584 int closecount = 0, n;
590 f = tty_release_redirect(tty);
594 if (test_bit(TTY_HUPPED, &tty->flags)) {
600 * Some console devices aren't actually hung up for technical and
601 * historical reasons, which can lead to indefinite interruptible
602 * sleep in n_tty_read(). The following explicitly tells
603 * n_tty_read() to abort readers.
605 set_bit(TTY_HUPPING, &tty->flags);
607 /* inuse_filps is protected by the single tty lock,
608 * this really needs to change if we want to flush the
609 * workqueue with the lock held.
611 check_tty_count(tty, "tty_hangup");
613 spin_lock(&tty->files_lock);
614 /* This breaks for file handles being sent over AF_UNIX sockets ? */
615 list_for_each_entry(priv, &tty->tty_files, list) {
617 if (filp->f_op->write_iter == redirected_tty_write)
619 if (filp->f_op->write_iter != tty_write)
622 __tty_fasync(-1, filp, 0); /* can't block */
623 filp->f_op = &hung_up_tty_fops;
625 spin_unlock(&tty->files_lock);
627 refs = tty_signal_session_leader(tty, exit_session);
628 /* Account for the p->signal references we killed */
632 tty_ldisc_hangup(tty, cons_filp != NULL);
634 spin_lock_irq(&tty->ctrl.lock);
635 clear_bit(TTY_THROTTLED, &tty->flags);
636 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
637 put_pid(tty->ctrl.session);
638 put_pid(tty->ctrl.pgrp);
639 tty->ctrl.session = NULL;
640 tty->ctrl.pgrp = NULL;
641 tty->ctrl.pktstatus = 0;
642 spin_unlock_irq(&tty->ctrl.lock);
645 * If one of the devices matches a console pointer, we
646 * cannot just call hangup() because that will cause
647 * tty->count and state->count to go out of sync.
648 * So we just call close() the right number of times.
652 for (n = 0; n < closecount; n++)
653 tty->ops->close(tty, cons_filp);
654 } else if (tty->ops->hangup)
655 tty->ops->hangup(tty);
657 * We don't want to have driver/ldisc interactions beyond the ones
658 * we did here. The driver layer expects no calls after ->hangup()
659 * from the ldisc side, which is now guaranteed.
661 set_bit(TTY_HUPPED, &tty->flags);
662 clear_bit(TTY_HUPPING, &tty->flags);
669 static void do_tty_hangup(struct work_struct *work)
671 struct tty_struct *tty =
672 container_of(work, struct tty_struct, hangup_work);
674 __tty_hangup(tty, 0);
678 * tty_hangup - trigger a hangup event
679 * @tty: tty to hangup
681 * A carrier loss (virtual or otherwise) has occurred on @tty. Schedule a
682 * hangup sequence to run after this event.
684 void tty_hangup(struct tty_struct *tty)
686 tty_debug_hangup(tty, "hangup\n");
687 schedule_work(&tty->hangup_work);
689 EXPORT_SYMBOL(tty_hangup);
692 * tty_vhangup - process vhangup
693 * @tty: tty to hangup
695 * The user has asked via system call for the terminal to be hung up. We do
696 * this synchronously so that when the syscall returns the process is complete.
697 * That guarantee is necessary for security reasons.
699 void tty_vhangup(struct tty_struct *tty)
701 tty_debug_hangup(tty, "vhangup\n");
702 __tty_hangup(tty, 0);
704 EXPORT_SYMBOL(tty_vhangup);
708 * tty_vhangup_self - process vhangup for own ctty
710 * Perform a vhangup on the current controlling tty
712 void tty_vhangup_self(void)
714 struct tty_struct *tty;
716 tty = get_current_tty();
724 * tty_vhangup_session - hangup session leader exit
725 * @tty: tty to hangup
727 * The session leader is exiting and hanging up its controlling terminal.
728 * Every process in the foreground process group is signalled %SIGHUP.
730 * We do this synchronously so that when the syscall returns the process is
731 * complete. That guarantee is necessary for security reasons.
733 void tty_vhangup_session(struct tty_struct *tty)
735 tty_debug_hangup(tty, "session hangup\n");
736 __tty_hangup(tty, 1);
740 * tty_hung_up_p - was tty hung up
741 * @filp: file pointer of tty
743 * Return: true if the tty has been subject to a vhangup or a carrier loss
745 int tty_hung_up_p(struct file *filp)
747 return (filp && filp->f_op == &hung_up_tty_fops);
749 EXPORT_SYMBOL(tty_hung_up_p);
751 void __stop_tty(struct tty_struct *tty)
753 if (tty->flow.stopped)
755 tty->flow.stopped = true;
761 * stop_tty - propagate flow control
764 * Perform flow control to the driver. May be called on an already stopped
765 * device and will not re-call the &tty_driver->stop() method.
767 * This functionality is used by both the line disciplines for halting incoming
768 * flow and by the driver. It may therefore be called from any context, may be
769 * under the tty %atomic_write_lock but not always.
774 void stop_tty(struct tty_struct *tty)
778 spin_lock_irqsave(&tty->flow.lock, flags);
780 spin_unlock_irqrestore(&tty->flow.lock, flags);
782 EXPORT_SYMBOL(stop_tty);
784 void __start_tty(struct tty_struct *tty)
786 if (!tty->flow.stopped || tty->flow.tco_stopped)
788 tty->flow.stopped = false;
790 tty->ops->start(tty);
795 * start_tty - propagate flow control
798 * Start a tty that has been stopped if at all possible. If @tty was previously
799 * stopped and is now being started, the &tty_driver->start() method is invoked
800 * and the line discipline woken.
805 void start_tty(struct tty_struct *tty)
809 spin_lock_irqsave(&tty->flow.lock, flags);
811 spin_unlock_irqrestore(&tty->flow.lock, flags);
813 EXPORT_SYMBOL(start_tty);
815 static void tty_update_time(struct tty_struct *tty, bool mtime)
817 time64_t sec = ktime_get_real_seconds();
818 struct tty_file_private *priv;
820 spin_lock(&tty->files_lock);
821 list_for_each_entry(priv, &tty->tty_files, list) {
822 struct inode *inode = file_inode(priv->file);
823 struct timespec64 *time = mtime ? &inode->i_mtime : &inode->i_atime;
826 * We only care if the two values differ in anything other than the
827 * lower three bits (i.e every 8 seconds). If so, then we can update
828 * the time of the tty device, otherwise it could be construded as a
829 * security leak to let userspace know the exact timing of the tty.
831 if ((sec ^ time->tv_sec) & ~7)
834 spin_unlock(&tty->files_lock);
838 * Iterate on the ldisc ->read() function until we've gotten all
839 * the data the ldisc has for us.
841 * The "cookie" is something that the ldisc read function can fill
842 * in to let us know that there is more data to be had.
844 * We promise to continue to call the ldisc until it stops returning
845 * data or clears the cookie. The cookie may be something that the
846 * ldisc maintains state for and needs to free.
848 static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
849 struct file *file, struct iov_iter *to)
853 unsigned long offset = 0;
855 size_t count = iov_iter_count(to);
860 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
861 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
866 /* Did we have an earlier error (ie -EFAULT)? */
872 * -EOVERFLOW means we didn't have enough space
873 * for a whole packet, and we shouldn't return
876 if (retval == -EOVERFLOW)
881 copied = copy_to_iter(kernel_buf, size, to);
886 * If the user copy failed, we still need to do another ->read()
887 * call if we had a cookie to let the ldisc clear up.
889 * But make sure size is zeroed.
891 if (unlikely(copied != size)) {
897 /* We always clear tty buffer in case they contained passwords */
898 memzero_explicit(kernel_buf, sizeof(kernel_buf));
899 return offset ? offset : retval;
904 * tty_read - read method for tty device files
905 * @iocb: kernel I/O control block
906 * @to: destination for the data read
908 * Perform the read system call function on this terminal device. Checks
909 * for hung up devices before calling the line discipline method.
912 * Locks the line discipline internally while needed. Multiple read calls
913 * may be outstanding in parallel.
915 static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
918 struct file *file = iocb->ki_filp;
919 struct inode *inode = file_inode(file);
920 struct tty_struct *tty = file_tty(file);
921 struct tty_ldisc *ld;
923 if (tty_paranoia_check(tty, inode, "tty_read"))
925 if (!tty || tty_io_error(tty))
928 /* We want to wait for the line discipline to sort out in this
931 ld = tty_ldisc_ref_wait(tty);
933 return hung_up_tty_read(iocb, to);
936 i = iterate_tty_read(ld, tty, file, to);
940 tty_update_time(tty, false);
945 void tty_write_unlock(struct tty_struct *tty)
947 mutex_unlock(&tty->atomic_write_lock);
948 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
951 int tty_write_lock(struct tty_struct *tty, int ndelay)
953 if (!mutex_trylock(&tty->atomic_write_lock)) {
956 if (mutex_lock_interruptible(&tty->atomic_write_lock))
963 * Split writes up in sane blocksizes to avoid
964 * denial-of-service type attacks
966 static inline ssize_t do_tty_write(
967 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
968 struct tty_struct *tty,
970 struct iov_iter *from)
972 size_t count = iov_iter_count(from);
973 ssize_t ret, written = 0;
976 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
981 * We chunk up writes into a temporary buffer. This
982 * simplifies low-level drivers immensely, since they
983 * don't have locking issues and user mode accesses.
985 * But if TTY_NO_WRITE_SPLIT is set, we should use a
988 * The default chunk-size is 2kB, because the NTTY
989 * layer has problems with bigger chunks. It will
990 * claim to be able to handle more characters than
994 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
999 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1000 if (tty->write_cnt < chunk) {
1001 unsigned char *buf_chunk;
1006 buf_chunk = kvmalloc(chunk, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1011 kvfree(tty->write_buf);
1012 tty->write_cnt = chunk;
1013 tty->write_buf = buf_chunk;
1016 /* Do the write .. */
1018 size_t size = count;
1024 if (copy_from_iter(tty->write_buf, size, from) != size)
1027 ret = write(tty, file, tty->write_buf, size);
1035 /* FIXME! Have Al check this! */
1037 iov_iter_revert(from, size-ret);
1043 if (signal_pending(current))
1048 tty_update_time(tty, true);
1052 tty_write_unlock(tty);
1057 * tty_write_message - write a message to a certain tty, not just the console.
1058 * @tty: the destination tty_struct
1059 * @msg: the message to write
1061 * This is used for messages that need to be redirected to a specific tty. We
1062 * don't put it into the syslog queue right now maybe in the future if really
1065 * We must still hold the BTM and test the CLOSING flag for the moment.
1067 void tty_write_message(struct tty_struct *tty, char *msg)
1070 mutex_lock(&tty->atomic_write_lock);
1072 if (tty->ops->write && tty->count > 0)
1073 tty->ops->write(tty, msg, strlen(msg));
1075 tty_write_unlock(tty);
1079 static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
1081 struct tty_struct *tty = file_tty(file);
1082 struct tty_ldisc *ld;
1085 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1087 if (!tty || !tty->ops->write || tty_io_error(tty))
1089 /* Short term debug to catch buggy drivers */
1090 if (tty->ops->write_room == NULL)
1091 tty_err(tty, "missing write_room method\n");
1092 ld = tty_ldisc_ref_wait(tty);
1094 return hung_up_tty_write(iocb, from);
1095 if (!ld->ops->write)
1098 ret = do_tty_write(ld->ops->write, tty, file, from);
1099 tty_ldisc_deref(ld);
1104 * tty_write - write method for tty device file
1105 * @iocb: kernel I/O control block
1106 * @from: iov_iter with data to write
1108 * Write data to a tty device via the line discipline.
1111 * Locks the line discipline as required
1112 * Writes to the tty driver are serialized by the atomic_write_lock
1113 * and are then processed in chunks to the device. The line
1114 * discipline write method will not be invoked in parallel for
1117 static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1119 return file_tty_write(iocb->ki_filp, iocb, from);
1122 ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1124 struct file *p = NULL;
1126 spin_lock(&redirect_lock);
1128 p = get_file(redirect);
1129 spin_unlock(&redirect_lock);
1132 * We know the redirected tty is just another tty, we can
1133 * call file_tty_write() directly with that file pointer.
1138 res = file_tty_write(p, iocb, iter);
1142 return tty_write(iocb, iter);
1146 * tty_send_xchar - send priority character
1147 * @tty: the tty to send to
1148 * @ch: xchar to send
1150 * Send a high priority character to the tty even if stopped.
1152 * Locking: none for xchar method, write ordering for write method.
1154 int tty_send_xchar(struct tty_struct *tty, char ch)
1156 bool was_stopped = tty->flow.stopped;
1158 if (tty->ops->send_xchar) {
1159 down_read(&tty->termios_rwsem);
1160 tty->ops->send_xchar(tty, ch);
1161 up_read(&tty->termios_rwsem);
1165 if (tty_write_lock(tty, 0) < 0)
1166 return -ERESTARTSYS;
1168 down_read(&tty->termios_rwsem);
1171 tty->ops->write(tty, &ch, 1);
1174 up_read(&tty->termios_rwsem);
1175 tty_write_unlock(tty);
1180 * pty_line_name - generate name for a pty
1181 * @driver: the tty driver in use
1182 * @index: the minor number
1183 * @p: output buffer of at least 6 bytes
1185 * Generate a name from a @driver reference and write it to the output buffer
1190 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1192 static const char ptychar[] = "pqrstuvwxyzabcde";
1193 int i = index + driver->name_base;
1194 /* ->name is initialized to "ttyp", but "tty" is expected */
1195 sprintf(p, "%s%c%x",
1196 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1197 ptychar[i >> 4 & 0xf], i & 0xf);
1201 * tty_line_name - generate name for a tty
1202 * @driver: the tty driver in use
1203 * @index: the minor number
1204 * @p: output buffer of at least 7 bytes
1206 * Generate a name from a @driver reference and write it to the output buffer
1211 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1213 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1214 return sprintf(p, "%s", driver->name);
1216 return sprintf(p, "%s%d", driver->name,
1217 index + driver->name_base);
1221 * tty_driver_lookup_tty() - find an existing tty, if any
1222 * @driver: the driver for the tty
1223 * @file: file object
1224 * @idx: the minor number
1226 * Return: the tty, if found. If not found, return %NULL or ERR_PTR() if the
1227 * driver lookup() method returns an error.
1229 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1231 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1232 struct file *file, int idx)
1234 struct tty_struct *tty;
1236 if (driver->ops->lookup) {
1238 tty = ERR_PTR(-EIO);
1240 tty = driver->ops->lookup(driver, file, idx);
1242 if (idx >= driver->num)
1243 return ERR_PTR(-EINVAL);
1244 tty = driver->ttys[idx];
1252 * tty_init_termios - helper for termios setup
1253 * @tty: the tty to set up
1255 * Initialise the termios structure for this tty. This runs under the
1256 * %tty_mutex currently so we can be relaxed about ordering.
1258 void tty_init_termios(struct tty_struct *tty)
1260 struct ktermios *tp;
1261 int idx = tty->index;
1263 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1264 tty->termios = tty->driver->init_termios;
1266 /* Check for lazy saved data */
1267 tp = tty->driver->termios[idx];
1270 tty->termios.c_line = tty->driver->init_termios.c_line;
1272 tty->termios = tty->driver->init_termios;
1274 /* Compatibility until drivers always set this */
1275 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1276 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1278 EXPORT_SYMBOL_GPL(tty_init_termios);
1281 * tty_standard_install - usual tty->ops->install
1282 * @driver: the driver for the tty
1285 * If the @driver overrides @tty->ops->install, it still can call this function
1286 * to perform the standard install operations.
1288 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1290 tty_init_termios(tty);
1291 tty_driver_kref_get(driver);
1293 driver->ttys[tty->index] = tty;
1296 EXPORT_SYMBOL_GPL(tty_standard_install);
1299 * tty_driver_install_tty() - install a tty entry in the driver
1300 * @driver: the driver for the tty
1303 * Install a tty object into the driver tables. The @tty->index field will be
1304 * set by the time this is called. This method is responsible for ensuring any
1305 * need additional structures are allocated and configured.
1307 * Locking: tty_mutex for now
1309 static int tty_driver_install_tty(struct tty_driver *driver,
1310 struct tty_struct *tty)
1312 return driver->ops->install ? driver->ops->install(driver, tty) :
1313 tty_standard_install(driver, tty);
1317 * tty_driver_remove_tty() - remove a tty from the driver tables
1318 * @driver: the driver for the tty
1319 * @tty: tty to remove
1321 * Remove a tty object from the driver tables. The tty->index field will be set
1322 * by the time this is called.
1324 * Locking: tty_mutex for now
1326 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1328 if (driver->ops->remove)
1329 driver->ops->remove(driver, tty);
1331 driver->ttys[tty->index] = NULL;
1335 * tty_reopen() - fast re-open of an open tty
1336 * @tty: the tty to open
1338 * Re-opens on master ptys are not allowed and return -%EIO.
1340 * Locking: Caller must hold tty_lock
1341 * Return: 0 on success, -errno on error.
1343 static int tty_reopen(struct tty_struct *tty)
1345 struct tty_driver *driver = tty->driver;
1346 struct tty_ldisc *ld;
1349 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1350 driver->subtype == PTY_TYPE_MASTER)
1356 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1359 ld = tty_ldisc_ref_wait(tty);
1361 tty_ldisc_deref(ld);
1363 retval = tty_ldisc_lock(tty, 5 * HZ);
1368 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1369 tty_ldisc_unlock(tty);
1379 * tty_init_dev - initialise a tty device
1380 * @driver: tty driver we are opening a device on
1381 * @idx: device index
1383 * Prepare a tty device. This may not be a "new" clean device but could also be
1384 * an active device. The pty drivers require special handling because of this.
1387 * The function is called under the tty_mutex, which protects us from the
1388 * tty struct or driver itself going away.
1390 * On exit the tty device has the line discipline attached and a reference
1391 * count of 1. If a pair was created for pty/tty use and the other was a pty
1392 * master then it too has a reference count of 1.
1394 * WSH 06/09/97: Rewritten to remove races and properly clean up after a failed
1395 * open. The new code protects the open with a mutex, so it's really quite
1396 * straightforward. The mutex locking can probably be relaxed for the (most
1397 * common) case of reopening a tty.
1399 * Return: new tty structure
1401 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1403 struct tty_struct *tty;
1407 * First time open is complex, especially for PTY devices.
1408 * This code guarantees that either everything succeeds and the
1409 * TTY is ready for operation, or else the table slots are vacated
1410 * and the allocated memory released. (Except that the termios
1414 if (!try_module_get(driver->owner))
1415 return ERR_PTR(-ENODEV);
1417 tty = alloc_tty_struct(driver, idx);
1420 goto err_module_put;
1424 retval = tty_driver_install_tty(driver, tty);
1429 tty->port = driver->ports[idx];
1431 if (WARN_RATELIMIT(!tty->port,
1432 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1433 __func__, tty->driver->name)) {
1435 goto err_release_lock;
1438 retval = tty_ldisc_lock(tty, 5 * HZ);
1440 goto err_release_lock;
1441 tty->port->itty = tty;
1444 * Structures all installed ... call the ldisc open routines.
1445 * If we fail here just call release_tty to clean up. No need
1446 * to decrement the use counts, as release_tty doesn't care.
1448 retval = tty_ldisc_setup(tty, tty->link);
1450 goto err_release_tty;
1451 tty_ldisc_unlock(tty);
1452 /* Return the tty locked so that it cannot vanish under the caller */
1457 free_tty_struct(tty);
1459 module_put(driver->owner);
1460 return ERR_PTR(retval);
1462 /* call the tty release_tty routine to clean out this slot */
1464 tty_ldisc_unlock(tty);
1465 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1469 release_tty(tty, idx);
1470 return ERR_PTR(retval);
1474 * tty_save_termios() - save tty termios data in driver table
1475 * @tty: tty whose termios data to save
1477 * Locking: Caller guarantees serialisation with tty_init_termios().
1479 void tty_save_termios(struct tty_struct *tty)
1481 struct ktermios *tp;
1482 int idx = tty->index;
1484 /* If the port is going to reset then it has no termios to save */
1485 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1488 /* Stash the termios data */
1489 tp = tty->driver->termios[idx];
1491 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1494 tty->driver->termios[idx] = tp;
1498 EXPORT_SYMBOL_GPL(tty_save_termios);
1501 * tty_flush_works - flush all works of a tty/pty pair
1502 * @tty: tty device to flush works for (or either end of a pty pair)
1504 * Sync flush all works belonging to @tty (and the 'other' tty).
1506 static void tty_flush_works(struct tty_struct *tty)
1508 flush_work(&tty->SAK_work);
1509 flush_work(&tty->hangup_work);
1511 flush_work(&tty->link->SAK_work);
1512 flush_work(&tty->link->hangup_work);
1517 * release_one_tty - release tty structure memory
1518 * @work: work of tty we are obliterating
1520 * Releases memory associated with a tty structure, and clears out the
1521 * driver table slots. This function is called when a device is no longer
1522 * in use. It also gets called when setup of a device fails.
1525 * takes the file list lock internally when working on the list of ttys
1526 * that the driver keeps.
1528 * This method gets called from a work queue so that the driver private
1529 * cleanup ops can sleep (needed for USB at least)
1531 static void release_one_tty(struct work_struct *work)
1533 struct tty_struct *tty =
1534 container_of(work, struct tty_struct, hangup_work);
1535 struct tty_driver *driver = tty->driver;
1536 struct module *owner = driver->owner;
1538 if (tty->ops->cleanup)
1539 tty->ops->cleanup(tty);
1541 tty_driver_kref_put(driver);
1544 spin_lock(&tty->files_lock);
1545 list_del_init(&tty->tty_files);
1546 spin_unlock(&tty->files_lock);
1548 put_pid(tty->ctrl.pgrp);
1549 put_pid(tty->ctrl.session);
1550 free_tty_struct(tty);
1553 static void queue_release_one_tty(struct kref *kref)
1555 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1557 /* The hangup queue is now free so we can reuse it rather than
1558 * waste a chunk of memory for each port.
1560 INIT_WORK(&tty->hangup_work, release_one_tty);
1561 schedule_work(&tty->hangup_work);
1565 * tty_kref_put - release a tty kref
1568 * Release a reference to the @tty device and if need be let the kref layer
1569 * destruct the object for us.
1571 void tty_kref_put(struct tty_struct *tty)
1574 kref_put(&tty->kref, queue_release_one_tty);
1576 EXPORT_SYMBOL(tty_kref_put);
1579 * release_tty - release tty structure memory
1580 * @tty: tty device release
1581 * @idx: index of the tty device release
1583 * Release both @tty and a possible linked partner (think pty pair),
1584 * and decrement the refcount of the backing module.
1588 * takes the file list lock internally when working on the list of ttys
1589 * that the driver keeps.
1591 static void release_tty(struct tty_struct *tty, int idx)
1593 /* This should always be true but check for the moment */
1594 WARN_ON(tty->index != idx);
1595 WARN_ON(!mutex_is_locked(&tty_mutex));
1596 if (tty->ops->shutdown)
1597 tty->ops->shutdown(tty);
1598 tty_save_termios(tty);
1599 tty_driver_remove_tty(tty->driver, tty);
1601 tty->port->itty = NULL;
1603 tty->link->port->itty = NULL;
1605 tty_buffer_cancel_work(tty->port);
1607 tty_buffer_cancel_work(tty->link->port);
1609 tty_kref_put(tty->link);
1614 * tty_release_checks - check a tty before real release
1615 * @tty: tty to check
1616 * @idx: index of the tty
1618 * Performs some paranoid checking before true release of the @tty. This is a
1619 * no-op unless %TTY_PARANOIA_CHECK is defined.
1621 static int tty_release_checks(struct tty_struct *tty, int idx)
1623 #ifdef TTY_PARANOIA_CHECK
1624 if (idx < 0 || idx >= tty->driver->num) {
1625 tty_debug(tty, "bad idx %d\n", idx);
1629 /* not much to check for devpts */
1630 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1633 if (tty != tty->driver->ttys[idx]) {
1634 tty_debug(tty, "bad driver table[%d] = %p\n",
1635 idx, tty->driver->ttys[idx]);
1638 if (tty->driver->other) {
1639 struct tty_struct *o_tty = tty->link;
1641 if (o_tty != tty->driver->other->ttys[idx]) {
1642 tty_debug(tty, "bad other table[%d] = %p\n",
1643 idx, tty->driver->other->ttys[idx]);
1646 if (o_tty->link != tty) {
1647 tty_debug(tty, "bad link = %p\n", o_tty->link);
1656 * tty_kclose - closes tty opened by tty_kopen
1659 * Performs the final steps to release and free a tty device. It is the same as
1660 * tty_release_struct() except that it also resets %TTY_PORT_KOPENED flag on
1663 void tty_kclose(struct tty_struct *tty)
1666 * Ask the line discipline code to release its structures
1668 tty_ldisc_release(tty);
1670 /* Wait for pending work before tty destruction commences */
1671 tty_flush_works(tty);
1673 tty_debug_hangup(tty, "freeing structure\n");
1675 * The release_tty function takes care of the details of clearing
1676 * the slots and preserving the termios structure.
1678 mutex_lock(&tty_mutex);
1679 tty_port_set_kopened(tty->port, 0);
1680 release_tty(tty, tty->index);
1681 mutex_unlock(&tty_mutex);
1683 EXPORT_SYMBOL_GPL(tty_kclose);
1686 * tty_release_struct - release a tty struct
1688 * @idx: index of the tty
1690 * Performs the final steps to release and free a tty device. It is roughly the
1691 * reverse of tty_init_dev().
1693 void tty_release_struct(struct tty_struct *tty, int idx)
1696 * Ask the line discipline code to release its structures
1698 tty_ldisc_release(tty);
1700 /* Wait for pending work before tty destruction commmences */
1701 tty_flush_works(tty);
1703 tty_debug_hangup(tty, "freeing structure\n");
1705 * The release_tty function takes care of the details of clearing
1706 * the slots and preserving the termios structure.
1708 mutex_lock(&tty_mutex);
1709 release_tty(tty, idx);
1710 mutex_unlock(&tty_mutex);
1712 EXPORT_SYMBOL_GPL(tty_release_struct);
1715 * tty_release - vfs callback for close
1716 * @inode: inode of tty
1717 * @filp: file pointer for handle to tty
1719 * Called the last time each file handle is closed that references this tty.
1720 * There may however be several such references.
1723 * Takes BKL. See tty_release_dev().
1725 * Even releasing the tty structures is a tricky business. We have to be very
1726 * careful that the structures are all released at the same time, as interrupts
1727 * might otherwise get the wrong pointers.
1729 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1730 * lead to double frees or releasing memory still in use.
1732 int tty_release(struct inode *inode, struct file *filp)
1734 struct tty_struct *tty = file_tty(filp);
1735 struct tty_struct *o_tty = NULL;
1736 int do_sleep, final;
1741 if (tty_paranoia_check(tty, inode, __func__))
1745 check_tty_count(tty, __func__);
1747 __tty_fasync(-1, filp, 0);
1750 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1751 tty->driver->subtype == PTY_TYPE_MASTER)
1754 if (tty_release_checks(tty, idx)) {
1759 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1761 if (tty->ops->close)
1762 tty->ops->close(tty, filp);
1764 /* If tty is pty master, lock the slave pty (stable lock order) */
1765 tty_lock_slave(o_tty);
1768 * Sanity check: if tty->count is going to zero, there shouldn't be
1769 * any waiters on tty->read_wait or tty->write_wait. We test the
1770 * wait queues and kick everyone out _before_ actually starting to
1771 * close. This ensures that we won't block while releasing the tty
1774 * The test for the o_tty closing is necessary, since the master and
1775 * slave sides may close in any order. If the slave side closes out
1776 * first, its count will be one, since the master side holds an open.
1777 * Thus this test wouldn't be triggered at the time the slave closed,
1783 if (tty->count <= 1) {
1784 if (waitqueue_active(&tty->read_wait)) {
1785 wake_up_poll(&tty->read_wait, EPOLLIN);
1788 if (waitqueue_active(&tty->write_wait)) {
1789 wake_up_poll(&tty->write_wait, EPOLLOUT);
1793 if (o_tty && o_tty->count <= 1) {
1794 if (waitqueue_active(&o_tty->read_wait)) {
1795 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1798 if (waitqueue_active(&o_tty->write_wait)) {
1799 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1808 tty_warn(tty, "read/write wait queue active!\n");
1810 schedule_timeout_killable(timeout);
1811 if (timeout < 120 * HZ)
1812 timeout = 2 * timeout + 1;
1814 timeout = MAX_SCHEDULE_TIMEOUT;
1818 if (--o_tty->count < 0) {
1819 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1823 if (--tty->count < 0) {
1824 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1829 * We've decremented tty->count, so we need to remove this file
1830 * descriptor off the tty->tty_files list; this serves two
1832 * - check_tty_count sees the correct number of file descriptors
1833 * associated with this tty.
1834 * - do_tty_hangup no longer sees this file descriptor as
1835 * something that needs to be handled for hangups.
1840 * Perform some housekeeping before deciding whether to return.
1842 * If _either_ side is closing, make sure there aren't any
1843 * processes that still think tty or o_tty is their controlling
1847 read_lock(&tasklist_lock);
1848 session_clear_tty(tty->ctrl.session);
1850 session_clear_tty(o_tty->ctrl.session);
1851 read_unlock(&tasklist_lock);
1854 /* check whether both sides are closing ... */
1855 final = !tty->count && !(o_tty && o_tty->count);
1857 tty_unlock_slave(o_tty);
1860 /* At this point, the tty->count == 0 should ensure a dead tty
1861 * cannot be re-opened by a racing opener.
1867 tty_debug_hangup(tty, "final close\n");
1869 tty_release_struct(tty, idx);
1874 * tty_open_current_tty - get locked tty of current task
1875 * @device: device number
1876 * @filp: file pointer to tty
1877 * @return: locked tty of the current task iff @device is /dev/tty
1879 * Performs a re-open of the current task's controlling tty.
1881 * We cannot return driver and index like for the other nodes because devpts
1882 * will not work then. It expects inodes to be from devpts FS.
1884 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1886 struct tty_struct *tty;
1889 if (device != MKDEV(TTYAUX_MAJOR, 0))
1892 tty = get_current_tty();
1894 return ERR_PTR(-ENXIO);
1896 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1899 tty_kref_put(tty); /* safe to drop the kref now */
1901 retval = tty_reopen(tty);
1904 tty = ERR_PTR(retval);
1910 * tty_lookup_driver - lookup a tty driver for a given device file
1911 * @device: device number
1912 * @filp: file pointer to tty
1913 * @index: index for the device in the @return driver
1915 * If returned value is not erroneous, the caller is responsible to decrement
1916 * the refcount by tty_driver_kref_put().
1918 * Locking: %tty_mutex protects get_tty_driver()
1920 * Return: driver for this inode (with increased refcount)
1922 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1925 struct tty_driver *driver = NULL;
1929 case MKDEV(TTY_MAJOR, 0): {
1930 extern struct tty_driver *console_driver;
1932 driver = tty_driver_kref_get(console_driver);
1933 *index = fg_console;
1937 case MKDEV(TTYAUX_MAJOR, 1): {
1938 struct tty_driver *console_driver = console_device(index);
1940 if (console_driver) {
1941 driver = tty_driver_kref_get(console_driver);
1942 if (driver && filp) {
1943 /* Don't let /dev/console block */
1944 filp->f_flags |= O_NONBLOCK;
1949 tty_driver_kref_put(driver);
1950 return ERR_PTR(-ENODEV);
1953 driver = get_tty_driver(device, index);
1955 return ERR_PTR(-ENODEV);
1961 static struct tty_struct *tty_kopen(dev_t device, int shared)
1963 struct tty_struct *tty;
1964 struct tty_driver *driver;
1967 mutex_lock(&tty_mutex);
1968 driver = tty_lookup_driver(device, NULL, &index);
1969 if (IS_ERR(driver)) {
1970 mutex_unlock(&tty_mutex);
1971 return ERR_CAST(driver);
1974 /* check whether we're reopening an existing tty */
1975 tty = tty_driver_lookup_tty(driver, NULL, index);
1976 if (IS_ERR(tty) || shared)
1980 /* drop kref from tty_driver_lookup_tty() */
1982 tty = ERR_PTR(-EBUSY);
1983 } else { /* tty_init_dev returns tty with the tty_lock held */
1984 tty = tty_init_dev(driver, index);
1987 tty_port_set_kopened(tty->port, 1);
1990 mutex_unlock(&tty_mutex);
1991 tty_driver_kref_put(driver);
1996 * tty_kopen_exclusive - open a tty device for kernel
1997 * @device: dev_t of device to open
1999 * Opens tty exclusively for kernel. Performs the driver lookup, makes sure
2000 * it's not already opened and performs the first-time tty initialization.
2002 * Claims the global %tty_mutex to serialize:
2003 * * concurrent first-time tty initialization
2004 * * concurrent tty driver removal w/ lookup
2005 * * concurrent tty removal from driver table
2007 * Return: the locked initialized &tty_struct
2009 struct tty_struct *tty_kopen_exclusive(dev_t device)
2011 return tty_kopen(device, 0);
2013 EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2016 * tty_kopen_shared - open a tty device for shared in-kernel use
2017 * @device: dev_t of device to open
2019 * Opens an already existing tty for in-kernel use. Compared to
2020 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2022 * Locking: identical to tty_kopen() above.
2024 struct tty_struct *tty_kopen_shared(dev_t device)
2026 return tty_kopen(device, 1);
2028 EXPORT_SYMBOL_GPL(tty_kopen_shared);
2031 * tty_open_by_driver - open a tty device
2032 * @device: dev_t of device to open
2033 * @filp: file pointer to tty
2035 * Performs the driver lookup, checks for a reopen, or otherwise performs the
2036 * first-time tty initialization.
2039 * Claims the global tty_mutex to serialize:
2040 * * concurrent first-time tty initialization
2041 * * concurrent tty driver removal w/ lookup
2042 * * concurrent tty removal from driver table
2044 * Return: the locked initialized or re-opened &tty_struct
2046 static struct tty_struct *tty_open_by_driver(dev_t device,
2049 struct tty_struct *tty;
2050 struct tty_driver *driver = NULL;
2054 mutex_lock(&tty_mutex);
2055 driver = tty_lookup_driver(device, filp, &index);
2056 if (IS_ERR(driver)) {
2057 mutex_unlock(&tty_mutex);
2058 return ERR_CAST(driver);
2061 /* check whether we're reopening an existing tty */
2062 tty = tty_driver_lookup_tty(driver, filp, index);
2064 mutex_unlock(&tty_mutex);
2069 if (tty_port_kopened(tty->port)) {
2071 mutex_unlock(&tty_mutex);
2072 tty = ERR_PTR(-EBUSY);
2075 mutex_unlock(&tty_mutex);
2076 retval = tty_lock_interruptible(tty);
2077 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2079 if (retval == -EINTR)
2080 retval = -ERESTARTSYS;
2081 tty = ERR_PTR(retval);
2084 retval = tty_reopen(tty);
2087 tty = ERR_PTR(retval);
2089 } else { /* Returns with the tty_lock held for now */
2090 tty = tty_init_dev(driver, index);
2091 mutex_unlock(&tty_mutex);
2094 tty_driver_kref_put(driver);
2099 * tty_open - open a tty device
2100 * @inode: inode of device file
2101 * @filp: file pointer to tty
2103 * tty_open() and tty_release() keep up the tty count that contains the number
2104 * of opens done on a tty. We cannot use the inode-count, as different inodes
2105 * might point to the same tty.
2107 * Open-counting is needed for pty masters, as well as for keeping track of
2108 * serial lines: DTR is dropped when the last close happens.
2109 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2111 * The termios state of a pty is reset on the first open so that settings don't
2112 * persist across reuse.
2115 * * %tty_mutex protects tty, tty_lookup_driver() and tty_init_dev().
2116 * * @tty->count should protect the rest.
2117 * * ->siglock protects ->signal/->sighand
2119 * Note: the tty_unlock/lock cases without a ref are only safe due to %tty_mutex
2121 static int tty_open(struct inode *inode, struct file *filp)
2123 struct tty_struct *tty;
2125 dev_t device = inode->i_rdev;
2126 unsigned saved_flags = filp->f_flags;
2128 nonseekable_open(inode, filp);
2131 retval = tty_alloc_file(filp);
2135 tty = tty_open_current_tty(device, filp);
2137 tty = tty_open_by_driver(device, filp);
2140 tty_free_file(filp);
2141 retval = PTR_ERR(tty);
2142 if (retval != -EAGAIN || signal_pending(current))
2148 tty_add_file(tty, filp);
2150 check_tty_count(tty, __func__);
2151 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2154 retval = tty->ops->open(tty, filp);
2157 filp->f_flags = saved_flags;
2160 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2162 tty_unlock(tty); /* need to call tty_release without BTM */
2163 tty_release(inode, filp);
2164 if (retval != -ERESTARTSYS)
2167 if (signal_pending(current))
2172 * Need to reset f_op in case a hangup happened.
2174 if (tty_hung_up_p(filp))
2175 filp->f_op = &tty_fops;
2178 clear_bit(TTY_HUPPED, &tty->flags);
2180 noctty = (filp->f_flags & O_NOCTTY) ||
2181 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2182 device == MKDEV(TTYAUX_MAJOR, 1) ||
2183 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2184 tty->driver->subtype == PTY_TYPE_MASTER);
2186 tty_open_proc_set_tty(filp, tty);
2193 * tty_poll - check tty status
2194 * @filp: file being polled
2195 * @wait: poll wait structures to update
2197 * Call the line discipline polling method to obtain the poll status of the
2200 * Locking: locks called line discipline but ldisc poll method may be
2201 * re-entered freely by other callers.
2203 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2205 struct tty_struct *tty = file_tty(filp);
2206 struct tty_ldisc *ld;
2209 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2212 ld = tty_ldisc_ref_wait(tty);
2214 return hung_up_tty_poll(filp, wait);
2216 ret = ld->ops->poll(tty, filp, wait);
2217 tty_ldisc_deref(ld);
2221 static int __tty_fasync(int fd, struct file *filp, int on)
2223 struct tty_struct *tty = file_tty(filp);
2224 unsigned long flags;
2227 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2230 retval = fasync_helper(fd, filp, on, &tty->fasync);
2238 spin_lock_irqsave(&tty->ctrl.lock, flags);
2239 if (tty->ctrl.pgrp) {
2240 pid = tty->ctrl.pgrp;
2241 type = PIDTYPE_PGID;
2243 pid = task_pid(current);
2244 type = PIDTYPE_TGID;
2247 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
2248 __f_setown(filp, pid, type, 0);
2256 static int tty_fasync(int fd, struct file *filp, int on)
2258 struct tty_struct *tty = file_tty(filp);
2259 int retval = -ENOTTY;
2262 if (!tty_hung_up_p(filp))
2263 retval = __tty_fasync(fd, filp, on);
2269 static bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI);
2271 * tiocsti - fake input character
2272 * @tty: tty to fake input into
2273 * @p: pointer to character
2275 * Fake input to a tty device. Does the necessary locking and input management.
2277 * FIXME: does not honour flow control ??
2280 * * Called functions take tty_ldiscs_lock
2281 * * current->signal->tty check is safe without locks
2283 static int tiocsti(struct tty_struct *tty, char __user *p)
2286 struct tty_ldisc *ld;
2288 if (!tty_legacy_tiocsti)
2291 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2293 if (get_user(ch, p))
2295 tty_audit_tiocsti(tty, ch);
2296 ld = tty_ldisc_ref_wait(tty);
2299 tty_buffer_lock_exclusive(tty->port);
2300 if (ld->ops->receive_buf)
2301 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2302 tty_buffer_unlock_exclusive(tty->port);
2303 tty_ldisc_deref(ld);
2308 * tiocgwinsz - implement window query ioctl
2310 * @arg: user buffer for result
2312 * Copies the kernel idea of the window size into the user buffer.
2314 * Locking: @tty->winsize_mutex is taken to ensure the winsize data is
2317 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2321 mutex_lock(&tty->winsize_mutex);
2322 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2323 mutex_unlock(&tty->winsize_mutex);
2325 return err ? -EFAULT : 0;
2329 * tty_do_resize - resize event
2330 * @tty: tty being resized
2331 * @ws: new dimensions
2333 * Update the termios variables and send the necessary signals to peform a
2334 * terminal resize correctly.
2336 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2341 mutex_lock(&tty->winsize_mutex);
2342 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2345 /* Signal the foreground process group */
2346 pgrp = tty_get_pgrp(tty);
2348 kill_pgrp(pgrp, SIGWINCH, 1);
2353 mutex_unlock(&tty->winsize_mutex);
2356 EXPORT_SYMBOL(tty_do_resize);
2359 * tiocswinsz - implement window size set ioctl
2360 * @tty: tty side of tty
2361 * @arg: user buffer for result
2363 * Copies the user idea of the window size to the kernel. Traditionally this is
2364 * just advisory information but for the Linux console it actually has driver
2365 * level meaning and triggers a VC resize.
2368 * Driver dependent. The default do_resize method takes the tty termios
2369 * mutex and ctrl.lock. The console takes its own lock then calls into the
2372 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2374 struct winsize tmp_ws;
2376 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2379 if (tty->ops->resize)
2380 return tty->ops->resize(tty, &tmp_ws);
2382 return tty_do_resize(tty, &tmp_ws);
2386 * tioccons - allow admin to move logical console
2387 * @file: the file to become console
2389 * Allow the administrator to move the redirected console device.
2391 * Locking: uses redirect_lock to guard the redirect information
2393 static int tioccons(struct file *file)
2395 if (!capable(CAP_SYS_ADMIN))
2397 if (file->f_op->write_iter == redirected_tty_write) {
2400 spin_lock(&redirect_lock);
2403 spin_unlock(&redirect_lock);
2408 if (file->f_op->write_iter != tty_write)
2410 if (!(file->f_mode & FMODE_WRITE))
2412 if (!(file->f_mode & FMODE_CAN_WRITE))
2414 spin_lock(&redirect_lock);
2416 spin_unlock(&redirect_lock);
2419 redirect = get_file(file);
2420 spin_unlock(&redirect_lock);
2425 * tiocsetd - set line discipline
2427 * @p: pointer to user data
2429 * Set the line discipline according to user request.
2431 * Locking: see tty_set_ldisc(), this function is just a helper
2433 static int tiocsetd(struct tty_struct *tty, int __user *p)
2438 if (get_user(disc, p))
2441 ret = tty_set_ldisc(tty, disc);
2447 * tiocgetd - get line discipline
2449 * @p: pointer to user data
2451 * Retrieves the line discipline id directly from the ldisc.
2453 * Locking: waits for ldisc reference (in case the line discipline is changing
2454 * or the @tty is being hungup)
2456 static int tiocgetd(struct tty_struct *tty, int __user *p)
2458 struct tty_ldisc *ld;
2461 ld = tty_ldisc_ref_wait(tty);
2464 ret = put_user(ld->ops->num, p);
2465 tty_ldisc_deref(ld);
2470 * send_break - performed time break
2471 * @tty: device to break on
2472 * @duration: timeout in mS
2474 * Perform a timed break on hardware that lacks its own driver level timed
2475 * break functionality.
2478 * @tty->atomic_write_lock serializes
2480 static int send_break(struct tty_struct *tty, unsigned int duration)
2484 if (tty->ops->break_ctl == NULL)
2487 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2488 retval = tty->ops->break_ctl(tty, duration);
2490 /* Do the work ourselves */
2491 if (tty_write_lock(tty, 0) < 0)
2493 retval = tty->ops->break_ctl(tty, -1);
2496 if (!signal_pending(current))
2497 msleep_interruptible(duration);
2498 retval = tty->ops->break_ctl(tty, 0);
2500 tty_write_unlock(tty);
2501 if (signal_pending(current))
2508 * tty_tiocmget - get modem status
2510 * @p: pointer to result
2512 * Obtain the modem status bits from the tty driver if the feature is
2513 * supported. Return -%ENOTTY if it is not available.
2515 * Locking: none (up to the driver)
2517 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2519 int retval = -ENOTTY;
2521 if (tty->ops->tiocmget) {
2522 retval = tty->ops->tiocmget(tty);
2525 retval = put_user(retval, p);
2531 * tty_tiocmset - set modem status
2533 * @cmd: command - clear bits, set bits or set all
2534 * @p: pointer to desired bits
2536 * Set the modem status bits from the tty driver if the feature
2537 * is supported. Return -%ENOTTY if it is not available.
2539 * Locking: none (up to the driver)
2541 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2545 unsigned int set, clear, val;
2547 if (tty->ops->tiocmset == NULL)
2550 retval = get_user(val, p);
2566 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2567 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2568 return tty->ops->tiocmset(tty, set, clear);
2572 * tty_get_icount - get tty statistics
2574 * @icount: output parameter
2576 * Gets a copy of the @tty's icount statistics.
2578 * Locking: none (up to the driver)
2580 int tty_get_icount(struct tty_struct *tty,
2581 struct serial_icounter_struct *icount)
2583 memset(icount, 0, sizeof(*icount));
2585 if (tty->ops->get_icount)
2586 return tty->ops->get_icount(tty, icount);
2590 EXPORT_SYMBOL_GPL(tty_get_icount);
2592 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2594 struct serial_icounter_struct icount;
2597 retval = tty_get_icount(tty, &icount);
2601 if (copy_to_user(arg, &icount, sizeof(icount)))
2606 static int tty_set_serial(struct tty_struct *tty, struct serial_struct *ss)
2608 char comm[TASK_COMM_LEN];
2611 flags = ss->flags & ASYNC_DEPRECATED;
2614 pr_warn_ratelimited("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2615 __func__, get_task_comm(comm, current), flags);
2617 if (!tty->ops->set_serial)
2620 return tty->ops->set_serial(tty, ss);
2623 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2625 struct serial_struct v;
2627 if (copy_from_user(&v, ss, sizeof(*ss)))
2630 return tty_set_serial(tty, &v);
2633 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2635 struct serial_struct v;
2638 memset(&v, 0, sizeof(v));
2639 if (!tty->ops->get_serial)
2641 err = tty->ops->get_serial(tty, &v);
2642 if (!err && copy_to_user(ss, &v, sizeof(v)))
2648 * if pty, return the slave side (real_tty)
2649 * otherwise, return self
2651 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2653 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2654 tty->driver->subtype == PTY_TYPE_MASTER)
2660 * Split this up, as gcc can choke on it otherwise..
2662 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2664 struct tty_struct *tty = file_tty(file);
2665 struct tty_struct *real_tty;
2666 void __user *p = (void __user *)arg;
2668 struct tty_ldisc *ld;
2670 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2673 real_tty = tty_pair_get_tty(tty);
2676 * Factor out some common prep work
2684 retval = tty_check_change(tty);
2687 if (cmd != TIOCCBRK) {
2688 tty_wait_until_sent(tty, 0);
2689 if (signal_pending(current))
2700 return tiocsti(tty, p);
2702 return tiocgwinsz(real_tty, p);
2704 return tiocswinsz(real_tty, p);
2706 return real_tty != tty ? -EINVAL : tioccons(file);
2708 set_bit(TTY_EXCLUSIVE, &tty->flags);
2711 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2715 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2717 return put_user(excl, (int __user *)p);
2720 return tiocgetd(tty, p);
2722 return tiocsetd(tty, p);
2724 if (!capable(CAP_SYS_ADMIN))
2730 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2732 return put_user(ret, (unsigned int __user *)p);
2737 case TIOCSBRK: /* Turn break on, unconditionally */
2738 if (tty->ops->break_ctl)
2739 return tty->ops->break_ctl(tty, -1);
2741 case TIOCCBRK: /* Turn break off, unconditionally */
2742 if (tty->ops->break_ctl)
2743 return tty->ops->break_ctl(tty, 0);
2745 case TCSBRK: /* SVID version: non-zero arg --> no break */
2746 /* non-zero arg means wait for all output data
2747 * to be sent (performed above) but don't send break.
2748 * This is used by the tcdrain() termios function.
2751 return send_break(tty, 250);
2753 case TCSBRKP: /* support for POSIX tcsendbreak() */
2754 return send_break(tty, arg ? arg*100 : 250);
2757 return tty_tiocmget(tty, p);
2761 return tty_tiocmset(tty, cmd, p);
2763 return tty_tiocgicount(tty, p);
2768 /* flush tty buffer and allow ldisc to process ioctl */
2769 tty_buffer_flush(tty, NULL);
2774 return tty_tiocsserial(tty, p);
2776 return tty_tiocgserial(tty, p);
2778 /* Special because the struct file is needed */
2779 return ptm_open_peer(file, tty, (int)arg);
2781 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2782 if (retval != -ENOIOCTLCMD)
2785 if (tty->ops->ioctl) {
2786 retval = tty->ops->ioctl(tty, cmd, arg);
2787 if (retval != -ENOIOCTLCMD)
2790 ld = tty_ldisc_ref_wait(tty);
2792 return hung_up_tty_ioctl(file, cmd, arg);
2794 if (ld->ops->ioctl) {
2795 retval = ld->ops->ioctl(tty, cmd, arg);
2796 if (retval == -ENOIOCTLCMD)
2799 tty_ldisc_deref(ld);
2803 #ifdef CONFIG_COMPAT
2805 struct serial_struct32 {
2811 compat_int_t xmit_fifo_size;
2812 compat_int_t custom_divisor;
2813 compat_int_t baud_base;
2814 unsigned short close_delay;
2818 unsigned short closing_wait; /* time to wait before closing */
2819 unsigned short closing_wait2; /* no longer used... */
2820 compat_uint_t iomem_base;
2821 unsigned short iomem_reg_shift;
2822 unsigned int port_high;
2823 /* compat_ulong_t iomap_base FIXME */
2824 compat_int_t reserved;
2827 static int compat_tty_tiocsserial(struct tty_struct *tty,
2828 struct serial_struct32 __user *ss)
2830 struct serial_struct32 v32;
2831 struct serial_struct v;
2833 if (copy_from_user(&v32, ss, sizeof(*ss)))
2836 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2837 v.iomem_base = compat_ptr(v32.iomem_base);
2838 v.iomem_reg_shift = v32.iomem_reg_shift;
2839 v.port_high = v32.port_high;
2842 return tty_set_serial(tty, &v);
2845 static int compat_tty_tiocgserial(struct tty_struct *tty,
2846 struct serial_struct32 __user *ss)
2848 struct serial_struct32 v32;
2849 struct serial_struct v;
2852 memset(&v, 0, sizeof(v));
2853 memset(&v32, 0, sizeof(v32));
2855 if (!tty->ops->get_serial)
2857 err = tty->ops->get_serial(tty, &v);
2859 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2860 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2861 0xfffffff : ptr_to_compat(v.iomem_base);
2862 v32.iomem_reg_shift = v.iomem_reg_shift;
2863 v32.port_high = v.port_high;
2864 if (copy_to_user(ss, &v32, sizeof(v32)))
2869 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2872 struct tty_struct *tty = file_tty(file);
2873 struct tty_ldisc *ld;
2874 int retval = -ENOIOCTLCMD;
2923 case TIOCGLCKTRMIOS:
2924 case TIOCSLCKTRMIOS:
2936 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2952 return tty_ioctl(file, cmd, arg);
2955 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2960 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2962 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2964 if (tty->ops->compat_ioctl) {
2965 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2966 if (retval != -ENOIOCTLCMD)
2970 ld = tty_ldisc_ref_wait(tty);
2972 return hung_up_tty_compat_ioctl(file, cmd, arg);
2973 if (ld->ops->compat_ioctl)
2974 retval = ld->ops->compat_ioctl(tty, cmd, arg);
2975 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2976 retval = ld->ops->ioctl(tty, (unsigned long)compat_ptr(cmd),
2978 tty_ldisc_deref(ld);
2984 static int this_tty(const void *t, struct file *file, unsigned fd)
2986 if (likely(file->f_op->read_iter != tty_read))
2988 return file_tty(file) != t ? 0 : fd + 1;
2992 * This implements the "Secure Attention Key" --- the idea is to
2993 * prevent trojan horses by killing all processes associated with this
2994 * tty when the user hits the "Secure Attention Key". Required for
2995 * super-paranoid applications --- see the Orange Book for more details.
2997 * This code could be nicer; ideally it should send a HUP, wait a few
2998 * seconds, then send a INT, and then a KILL signal. But you then
2999 * have to coordinate with the init process, since all processes associated
3000 * with the current tty must be dead before the new getty is allowed
3003 * Now, if it would be correct ;-/ The current code has a nasty hole -
3004 * it doesn't catch files in flight. We may send the descriptor to ourselves
3005 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3007 * Nasty bug: do_SAK is being called in interrupt context. This can
3008 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3010 void __do_SAK(struct tty_struct *tty)
3012 struct task_struct *g, *p;
3013 struct pid *session;
3015 unsigned long flags;
3017 spin_lock_irqsave(&tty->ctrl.lock, flags);
3018 session = get_pid(tty->ctrl.session);
3019 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
3021 tty_ldisc_flush(tty);
3023 tty_driver_flush_buffer(tty);
3025 read_lock(&tasklist_lock);
3026 /* Kill the entire session */
3027 do_each_pid_task(session, PIDTYPE_SID, p) {
3028 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3029 task_pid_nr(p), p->comm);
3030 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3031 } while_each_pid_task(session, PIDTYPE_SID, p);
3033 /* Now kill any processes that happen to have the tty open */
3034 do_each_thread(g, p) {
3035 if (p->signal->tty == tty) {
3036 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3037 task_pid_nr(p), p->comm);
3038 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3043 i = iterate_fd(p->files, 0, this_tty, tty);
3045 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3046 task_pid_nr(p), p->comm, i - 1);
3047 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3051 } while_each_thread(g, p);
3052 read_unlock(&tasklist_lock);
3056 static void do_SAK_work(struct work_struct *work)
3058 struct tty_struct *tty =
3059 container_of(work, struct tty_struct, SAK_work);
3064 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3065 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3066 * the values which we write to it will be identical to the values which it
3067 * already has. --akpm
3069 void do_SAK(struct tty_struct *tty)
3073 schedule_work(&tty->SAK_work);
3075 EXPORT_SYMBOL(do_SAK);
3077 /* Must put_device() after it's unused! */
3078 static struct device *tty_get_device(struct tty_struct *tty)
3080 dev_t devt = tty_devnum(tty);
3082 return class_find_device_by_devt(&tty_class, devt);
3087 * alloc_tty_struct - allocate a new tty
3088 * @driver: driver which will handle the returned tty
3089 * @idx: minor of the tty
3091 * This subroutine allocates and initializes a tty structure.
3093 * Locking: none - @tty in question is not exposed at this point
3095 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3097 struct tty_struct *tty;
3099 tty = kzalloc(sizeof(*tty), GFP_KERNEL_ACCOUNT);
3103 kref_init(&tty->kref);
3104 if (tty_ldisc_init(tty)) {
3108 tty->ctrl.session = NULL;
3109 tty->ctrl.pgrp = NULL;
3110 mutex_init(&tty->legacy_mutex);
3111 mutex_init(&tty->throttle_mutex);
3112 init_rwsem(&tty->termios_rwsem);
3113 mutex_init(&tty->winsize_mutex);
3114 init_ldsem(&tty->ldisc_sem);
3115 init_waitqueue_head(&tty->write_wait);
3116 init_waitqueue_head(&tty->read_wait);
3117 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3118 mutex_init(&tty->atomic_write_lock);
3119 spin_lock_init(&tty->ctrl.lock);
3120 spin_lock_init(&tty->flow.lock);
3121 spin_lock_init(&tty->files_lock);
3122 INIT_LIST_HEAD(&tty->tty_files);
3123 INIT_WORK(&tty->SAK_work, do_SAK_work);
3125 tty->driver = driver;
3126 tty->ops = driver->ops;
3128 tty_line_name(driver, idx, tty->name);
3129 tty->dev = tty_get_device(tty);
3135 * tty_put_char - write one character to a tty
3137 * @ch: character to write
3139 * Write one byte to the @tty using the provided @tty->ops->put_char() method
3142 * Note: the specific put_char operation in the driver layer may go
3143 * away soon. Don't call it directly, use this method
3145 * Return: the number of characters successfully output.
3147 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3149 if (tty->ops->put_char)
3150 return tty->ops->put_char(tty, ch);
3151 return tty->ops->write(tty, &ch, 1);
3153 EXPORT_SYMBOL_GPL(tty_put_char);
3155 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3156 unsigned int index, unsigned int count)
3160 /* init here, since reused cdevs cause crashes */
3161 driver->cdevs[index] = cdev_alloc();
3162 if (!driver->cdevs[index])
3164 driver->cdevs[index]->ops = &tty_fops;
3165 driver->cdevs[index]->owner = driver->owner;
3166 err = cdev_add(driver->cdevs[index], dev, count);
3168 kobject_put(&driver->cdevs[index]->kobj);
3173 * tty_register_device - register a tty device
3174 * @driver: the tty driver that describes the tty device
3175 * @index: the index in the tty driver for this tty device
3176 * @device: a struct device that is associated with this tty device.
3177 * This field is optional, if there is no known struct device
3178 * for this tty device it can be set to NULL safely.
3180 * This call is required to be made to register an individual tty device
3181 * if the tty driver's flags have the %TTY_DRIVER_DYNAMIC_DEV bit set. If
3182 * that bit is not set, this function should not be called by a tty
3187 * Return: A pointer to the struct device for this tty device (or
3188 * ERR_PTR(-EFOO) on error).
3190 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3191 struct device *device)
3193 return tty_register_device_attr(driver, index, device, NULL, NULL);
3195 EXPORT_SYMBOL(tty_register_device);
3197 static void tty_device_create_release(struct device *dev)
3199 dev_dbg(dev, "releasing...\n");
3204 * tty_register_device_attr - register a tty device
3205 * @driver: the tty driver that describes the tty device
3206 * @index: the index in the tty driver for this tty device
3207 * @device: a struct device that is associated with this tty device.
3208 * This field is optional, if there is no known struct device
3209 * for this tty device it can be set to %NULL safely.
3210 * @drvdata: Driver data to be set to device.
3211 * @attr_grp: Attribute group to be set on device.
3213 * This call is required to be made to register an individual tty device if the
3214 * tty driver's flags have the %TTY_DRIVER_DYNAMIC_DEV bit set. If that bit is
3215 * not set, this function should not be called by a tty driver.
3219 * Return: A pointer to the struct device for this tty device (or
3220 * ERR_PTR(-EFOO) on error).
3222 struct device *tty_register_device_attr(struct tty_driver *driver,
3223 unsigned index, struct device *device,
3225 const struct attribute_group **attr_grp)
3228 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3229 struct ktermios *tp;
3233 if (index >= driver->num) {
3234 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3235 driver->name, index);
3236 return ERR_PTR(-EINVAL);
3239 if (driver->type == TTY_DRIVER_TYPE_PTY)
3240 pty_line_name(driver, index, name);
3242 tty_line_name(driver, index, name);
3244 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3246 return ERR_PTR(-ENOMEM);
3249 dev->class = &tty_class;
3250 dev->parent = device;
3251 dev->release = tty_device_create_release;
3252 dev_set_name(dev, "%s", name);
3253 dev->groups = attr_grp;
3254 dev_set_drvdata(dev, drvdata);
3256 dev_set_uevent_suppress(dev, 1);
3258 retval = device_register(dev);
3262 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3264 * Free any saved termios data so that the termios state is
3265 * reset when reusing a minor number.
3267 tp = driver->termios[index];
3269 driver->termios[index] = NULL;
3273 retval = tty_cdev_add(driver, devt, index, 1);
3278 dev_set_uevent_suppress(dev, 0);
3279 kobject_uevent(&dev->kobj, KOBJ_ADD);
3288 return ERR_PTR(retval);
3290 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3293 * tty_unregister_device - unregister a tty device
3294 * @driver: the tty driver that describes the tty device
3295 * @index: the index in the tty driver for this tty device
3297 * If a tty device is registered with a call to tty_register_device() then
3298 * this function must be called when the tty device is gone.
3302 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3304 device_destroy(&tty_class, MKDEV(driver->major, driver->minor_start) + index);
3305 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3306 cdev_del(driver->cdevs[index]);
3307 driver->cdevs[index] = NULL;
3310 EXPORT_SYMBOL(tty_unregister_device);
3313 * __tty_alloc_driver -- allocate tty driver
3314 * @lines: count of lines this driver can handle at most
3315 * @owner: module which is responsible for this driver
3316 * @flags: some of %TTY_DRIVER_ flags, will be set in driver->flags
3318 * This should not be called directly, some of the provided macros should be
3319 * used instead. Use IS_ERR() and friends on @retval.
3321 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3322 unsigned long flags)
3324 struct tty_driver *driver;
3325 unsigned int cdevs = 1;
3328 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3329 return ERR_PTR(-EINVAL);
3331 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3333 return ERR_PTR(-ENOMEM);
3335 kref_init(&driver->kref);
3336 driver->num = lines;
3337 driver->owner = owner;
3338 driver->flags = flags;
3340 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3341 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3343 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3345 if (!driver->ttys || !driver->termios) {
3351 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3352 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3354 if (!driver->ports) {
3361 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3362 if (!driver->cdevs) {
3369 kfree(driver->ports);
3370 kfree(driver->ttys);
3371 kfree(driver->termios);
3372 kfree(driver->cdevs);
3374 return ERR_PTR(err);
3376 EXPORT_SYMBOL(__tty_alloc_driver);
3378 static void destruct_tty_driver(struct kref *kref)
3380 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3382 struct ktermios *tp;
3384 if (driver->flags & TTY_DRIVER_INSTALLED) {
3385 for (i = 0; i < driver->num; i++) {
3386 tp = driver->termios[i];
3388 driver->termios[i] = NULL;
3391 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3392 tty_unregister_device(driver, i);
3394 proc_tty_unregister_driver(driver);
3395 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3396 cdev_del(driver->cdevs[0]);
3398 kfree(driver->cdevs);
3399 kfree(driver->ports);
3400 kfree(driver->termios);
3401 kfree(driver->ttys);
3406 * tty_driver_kref_put -- drop a reference to a tty driver
3407 * @driver: driver of which to drop the reference
3409 * The final put will destroy and free up the driver.
3411 void tty_driver_kref_put(struct tty_driver *driver)
3413 kref_put(&driver->kref, destruct_tty_driver);
3415 EXPORT_SYMBOL(tty_driver_kref_put);
3418 * tty_register_driver -- register a tty driver
3419 * @driver: driver to register
3421 * Called by a tty driver to register itself.
3423 int tty_register_driver(struct tty_driver *driver)
3430 if (!driver->major) {
3431 error = alloc_chrdev_region(&dev, driver->minor_start,
3432 driver->num, driver->name);
3434 driver->major = MAJOR(dev);
3435 driver->minor_start = MINOR(dev);
3438 dev = MKDEV(driver->major, driver->minor_start);
3439 error = register_chrdev_region(dev, driver->num, driver->name);
3444 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3445 error = tty_cdev_add(driver, dev, 0, driver->num);
3447 goto err_unreg_char;
3450 mutex_lock(&tty_mutex);
3451 list_add(&driver->tty_drivers, &tty_drivers);
3452 mutex_unlock(&tty_mutex);
3454 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3455 for (i = 0; i < driver->num; i++) {
3456 d = tty_register_device(driver, i, NULL);
3459 goto err_unreg_devs;
3463 proc_tty_register_driver(driver);
3464 driver->flags |= TTY_DRIVER_INSTALLED;
3468 for (i--; i >= 0; i--)
3469 tty_unregister_device(driver, i);
3471 mutex_lock(&tty_mutex);
3472 list_del(&driver->tty_drivers);
3473 mutex_unlock(&tty_mutex);
3476 unregister_chrdev_region(dev, driver->num);
3480 EXPORT_SYMBOL(tty_register_driver);
3483 * tty_unregister_driver -- unregister a tty driver
3484 * @driver: driver to unregister
3486 * Called by a tty driver to unregister itself.
3488 void tty_unregister_driver(struct tty_driver *driver)
3490 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3492 mutex_lock(&tty_mutex);
3493 list_del(&driver->tty_drivers);
3494 mutex_unlock(&tty_mutex);
3496 EXPORT_SYMBOL(tty_unregister_driver);
3498 dev_t tty_devnum(struct tty_struct *tty)
3500 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3502 EXPORT_SYMBOL(tty_devnum);
3504 void tty_default_fops(struct file_operations *fops)
3509 static char *tty_devnode(const struct device *dev, umode_t *mode)
3513 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3514 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3519 const struct class tty_class = {
3521 .devnode = tty_devnode,
3524 static int __init tty_class_init(void)
3526 return class_register(&tty_class);
3529 postcore_initcall(tty_class_init);
3531 /* 3/2004 jmc: why do these devices exist? */
3532 static struct cdev tty_cdev, console_cdev;
3534 static ssize_t show_cons_active(struct device *dev,
3535 struct device_attribute *attr, char *buf)
3537 struct console *cs[16];
3543 * Hold the console_list_lock to guarantee that no consoles are
3544 * unregistered until all console processing is complete.
3545 * This also allows safe traversal of the console list and
3546 * race-free reading of @flags.
3548 console_list_lock();
3550 for_each_console(c) {
3555 if ((c->flags & CON_ENABLED) == 0)
3558 if (i >= ARRAY_SIZE(cs))
3563 * Take console_lock to serialize device() callback with
3564 * other console operations. For example, fg_console is
3565 * modified under console_lock when switching vt.
3569 int index = cs[i]->index;
3570 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3572 /* don't resolve tty0 as some programs depend on it */
3573 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3574 count += tty_line_name(drv, index, buf + count);
3576 count += sprintf(buf + count, "%s%d",
3577 cs[i]->name, cs[i]->index);
3579 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3583 console_list_unlock();
3587 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3589 static struct attribute *cons_dev_attrs[] = {
3590 &dev_attr_active.attr,
3594 ATTRIBUTE_GROUPS(cons_dev);
3596 static struct device *consdev;
3598 void console_sysfs_notify(void)
3601 sysfs_notify(&consdev->kobj, NULL, "active");
3604 static struct ctl_table tty_table[] = {
3606 .procname = "legacy_tiocsti",
3607 .data = &tty_legacy_tiocsti,
3608 .maxlen = sizeof(tty_legacy_tiocsti),
3610 .proc_handler = proc_dobool,
3613 .procname = "ldisc_autoload",
3614 .data = &tty_ldisc_autoload,
3615 .maxlen = sizeof(tty_ldisc_autoload),
3617 .proc_handler = proc_dointvec,
3618 .extra1 = SYSCTL_ZERO,
3619 .extra2 = SYSCTL_ONE,
3625 * Ok, now we can initialize the rest of the tty devices and can count
3626 * on memory allocations, interrupts etc..
3628 int __init tty_init(void)
3630 register_sysctl_init("dev/tty", tty_table);
3631 cdev_init(&tty_cdev, &tty_fops);
3632 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3633 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3634 panic("Couldn't register /dev/tty driver\n");
3635 device_create(&tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3637 cdev_init(&console_cdev, &console_fops);
3638 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3639 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3640 panic("Couldn't register /dev/console driver\n");
3641 consdev = device_create_with_groups(&tty_class, NULL,
3642 MKDEV(TTYAUX_MAJOR, 1), NULL,
3643 cons_dev_groups, "console");
3644 if (IS_ERR(consdev))
3648 vty_init(&console_fops);