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>
105 #include <linux/kbd_kern.h>
106 #include <linux/vt_kern.h>
107 #include <linux/selection.h>
109 #include <linux/kmod.h>
110 #include <linux/nsproxy.h>
113 #undef TTY_DEBUG_HANGUP
114 #ifdef TTY_DEBUG_HANGUP
115 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
117 # define tty_debug_hangup(tty, f, args...) do { } while (0)
120 #define TTY_PARANOIA_CHECK 1
121 #define CHECK_TTY_COUNT 1
123 struct 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,
132 /* .c_line = N_TTY, */
134 EXPORT_SYMBOL(tty_std_termios);
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
141 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
143 /* Mutex to protect creating and releasing a tty */
144 DEFINE_MUTEX(tty_mutex);
146 static ssize_t tty_read(struct kiocb *, struct iov_iter *);
147 static ssize_t tty_write(struct kiocb *, struct iov_iter *);
148 static __poll_t tty_poll(struct file *, poll_table *);
149 static int tty_open(struct inode *, struct file *);
151 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
154 #define tty_compat_ioctl NULL
156 static int __tty_fasync(int fd, struct file *filp, int on);
157 static int tty_fasync(int fd, struct file *filp, int on);
158 static void release_tty(struct tty_struct *tty, int idx);
161 * free_tty_struct - free a disused tty
162 * @tty: tty struct to free
164 * Free the write buffers, tty queue and tty memory itself.
166 * Locking: none. Must be called after tty is definitely unused
168 static void free_tty_struct(struct tty_struct *tty)
170 tty_ldisc_deinit(tty);
171 put_device(tty->dev);
172 kvfree(tty->write_buf);
176 static inline struct tty_struct *file_tty(struct file *file)
178 return ((struct tty_file_private *)file->private_data)->tty;
181 int tty_alloc_file(struct file *file)
183 struct tty_file_private *priv;
185 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
189 file->private_data = priv;
194 /* Associate a new file with the tty structure */
195 void tty_add_file(struct tty_struct *tty, struct file *file)
197 struct tty_file_private *priv = file->private_data;
202 spin_lock(&tty->files_lock);
203 list_add(&priv->list, &tty->tty_files);
204 spin_unlock(&tty->files_lock);
208 * tty_free_file - free file->private_data
209 * @file: to free private_data of
211 * This shall be used only for fail path handling when tty_add_file was not
214 void tty_free_file(struct file *file)
216 struct tty_file_private *priv = file->private_data;
218 file->private_data = NULL;
222 /* Delete file from its tty */
223 static void tty_del_file(struct file *file)
225 struct tty_file_private *priv = file->private_data;
226 struct tty_struct *tty = priv->tty;
228 spin_lock(&tty->files_lock);
229 list_del(&priv->list);
230 spin_unlock(&tty->files_lock);
235 * tty_name - return tty naming
236 * @tty: tty structure
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
243 const char *tty_name(const struct tty_struct *tty)
245 if (!tty) /* Hmm. NULL pointer. That's fun. */
249 EXPORT_SYMBOL(tty_name);
251 const char *tty_driver_name(const struct tty_struct *tty)
253 if (!tty || !tty->driver)
255 return tty->driver->name;
258 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
261 #ifdef TTY_PARANOIA_CHECK
263 pr_warn("(%d:%d): %s: NULL tty\n",
264 imajor(inode), iminor(inode), routine);
271 /* Caller must hold tty_lock */
272 static int check_tty_count(struct tty_struct *tty, const char *routine)
274 #ifdef CHECK_TTY_COUNT
276 int count = 0, kopen_count = 0;
278 spin_lock(&tty->files_lock);
279 list_for_each(p, &tty->tty_files) {
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)
287 if (tty_port_kopened(tty->port))
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);
299 * get_tty_driver - find device of a tty
300 * @device: device identifier
301 * @index: returns the index of the tty
303 * This routine returns a tty driver structure, given a device number and also
304 * passes back the index number.
306 * Locking: caller must hold tty_mutex
308 static struct tty_driver *get_tty_driver(dev_t device, int *index)
310 struct tty_driver *p;
312 list_for_each_entry(p, &tty_drivers, tty_drivers) {
313 dev_t base = MKDEV(p->major, p->minor_start);
315 if (device < base || device >= base + p->num)
317 *index = device - base;
318 return tty_driver_kref_get(p);
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
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.
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.
336 int tty_dev_name_to_number(const char *name, dev_t *number)
338 struct tty_driver *p;
340 int index, prefix_length = 0;
343 for (str = name; *str && !isdigit(*str); str++)
349 ret = kstrtoint(str, 10, &index);
353 prefix_length = str - name;
354 mutex_lock(&tty_mutex);
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);
365 /* if here then driver wasn't found */
368 mutex_unlock(&tty_mutex);
371 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
373 #ifdef CONFIG_CONSOLE_POLL
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
380 * This routine returns a tty driver structure, given a name and the condition
381 * that the tty driver is capable of polled operation.
383 struct tty_driver *tty_find_polling_driver(char *name, int *line)
385 struct tty_driver *p, *res = NULL;
390 for (str = name; *str; str++)
391 if ((*str >= '0' && *str <= '9') || *str == ',')
397 tty_line = simple_strtoul(str, &str, 10);
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)
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);
417 mutex_unlock(&tty_mutex);
421 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
424 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
429 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
434 /* No kernel lock held - none needed ;) */
435 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
437 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
440 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
443 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
446 static long hung_up_tty_compat_ioctl(struct file *file,
447 unsigned int cmd, unsigned long arg)
449 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
452 static int hung_up_tty_fasync(int fd, struct file *file, int on)
457 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
459 struct tty_struct *tty = file_tty(file);
461 if (tty && tty->ops && tty->ops->show_fdinfo)
462 tty->ops->show_fdinfo(tty, m);
465 static const struct file_operations tty_fops = {
467 .read_iter = tty_read,
468 .write_iter = tty_write,
469 .splice_read = copy_splice_read,
470 .splice_write = iter_file_splice_write,
472 .unlocked_ioctl = tty_ioctl,
473 .compat_ioctl = tty_compat_ioctl,
475 .release = tty_release,
476 .fasync = tty_fasync,
477 .show_fdinfo = tty_show_fdinfo,
480 static const struct file_operations console_fops = {
482 .read_iter = tty_read,
483 .write_iter = redirected_tty_write,
484 .splice_read = copy_splice_read,
485 .splice_write = iter_file_splice_write,
487 .unlocked_ioctl = tty_ioctl,
488 .compat_ioctl = tty_compat_ioctl,
490 .release = tty_release,
491 .fasync = tty_fasync,
494 static const struct file_operations hung_up_tty_fops = {
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,
505 static DEFINE_SPINLOCK(redirect_lock);
506 static struct file *redirect;
509 * tty_wakeup - request more data
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
516 void tty_wakeup(struct tty_struct *tty)
518 struct tty_ldisc *ld;
520 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
521 ld = tty_ldisc_ref(tty);
523 if (ld->ops->write_wakeup)
524 ld->ops->write_wakeup(tty);
528 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
530 EXPORT_SYMBOL_GPL(tty_wakeup);
533 * tty_release_redirect - Release a redirect on a pty if present
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.
539 static struct file *tty_release_redirect(struct tty_struct *tty)
541 struct file *f = NULL;
543 spin_lock(&redirect_lock);
544 if (redirect && file_tty(redirect) == tty) {
548 spin_unlock(&redirect_lock);
554 * __tty_hangup - actual handler for hangup events
556 * @exit_session: if non-zero, signal all foreground group processes
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.
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.
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
575 * * ->siglock to protect ->signal/->sighand
578 static void __tty_hangup(struct tty_struct *tty, int exit_session)
580 struct file *cons_filp = NULL;
581 struct file *filp, *f;
582 struct tty_file_private *priv;
583 int closecount = 0, n;
589 f = tty_release_redirect(tty);
593 if (test_bit(TTY_HUPPED, &tty->flags)) {
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.
604 set_bit(TTY_HUPPING, &tty->flags);
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.
610 check_tty_count(tty, "tty_hangup");
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) {
616 if (filp->f_op->write_iter == redirected_tty_write)
618 if (filp->f_op->write_iter != tty_write)
621 __tty_fasync(-1, filp, 0); /* can't block */
622 filp->f_op = &hung_up_tty_fops;
624 spin_unlock(&tty->files_lock);
626 refs = tty_signal_session_leader(tty, exit_session);
627 /* Account for the p->signal references we killed */
631 tty_ldisc_hangup(tty, cons_filp != NULL);
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);
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.
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);
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.
660 set_bit(TTY_HUPPED, &tty->flags);
661 clear_bit(TTY_HUPPING, &tty->flags);
668 static void do_tty_hangup(struct work_struct *work)
670 struct tty_struct *tty =
671 container_of(work, struct tty_struct, hangup_work);
673 __tty_hangup(tty, 0);
677 * tty_hangup - trigger a hangup event
678 * @tty: tty to hangup
680 * A carrier loss (virtual or otherwise) has occurred on @tty. Schedule a
681 * hangup sequence to run after this event.
683 void tty_hangup(struct tty_struct *tty)
685 tty_debug_hangup(tty, "hangup\n");
686 schedule_work(&tty->hangup_work);
688 EXPORT_SYMBOL(tty_hangup);
691 * tty_vhangup - process vhangup
692 * @tty: tty to hangup
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.
698 void tty_vhangup(struct tty_struct *tty)
700 tty_debug_hangup(tty, "vhangup\n");
701 __tty_hangup(tty, 0);
703 EXPORT_SYMBOL(tty_vhangup);
707 * tty_vhangup_self - process vhangup for own ctty
709 * Perform a vhangup on the current controlling tty
711 void tty_vhangup_self(void)
713 struct tty_struct *tty;
715 tty = get_current_tty();
723 * tty_vhangup_session - hangup session leader exit
724 * @tty: tty to hangup
726 * The session leader is exiting and hanging up its controlling terminal.
727 * Every process in the foreground process group is signalled %SIGHUP.
729 * We do this synchronously so that when the syscall returns the process is
730 * complete. That guarantee is necessary for security reasons.
732 void tty_vhangup_session(struct tty_struct *tty)
734 tty_debug_hangup(tty, "session hangup\n");
735 __tty_hangup(tty, 1);
739 * tty_hung_up_p - was tty hung up
740 * @filp: file pointer of tty
742 * Return: true if the tty has been subject to a vhangup or a carrier loss
744 int tty_hung_up_p(struct file *filp)
746 return (filp && filp->f_op == &hung_up_tty_fops);
748 EXPORT_SYMBOL(tty_hung_up_p);
750 void __stop_tty(struct tty_struct *tty)
752 if (tty->flow.stopped)
754 tty->flow.stopped = true;
760 * stop_tty - propagate flow control
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.
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.
773 void stop_tty(struct tty_struct *tty)
777 spin_lock_irqsave(&tty->flow.lock, flags);
779 spin_unlock_irqrestore(&tty->flow.lock, flags);
781 EXPORT_SYMBOL(stop_tty);
783 void __start_tty(struct tty_struct *tty)
785 if (!tty->flow.stopped || tty->flow.tco_stopped)
787 tty->flow.stopped = false;
789 tty->ops->start(tty);
794 * start_tty - propagate flow control
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.
804 void start_tty(struct tty_struct *tty)
808 spin_lock_irqsave(&tty->flow.lock, flags);
810 spin_unlock_irqrestore(&tty->flow.lock, flags);
812 EXPORT_SYMBOL(start_tty);
814 static void tty_update_time(struct timespec64 *time)
816 time64_t sec = ktime_get_real_seconds();
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.
824 if ((sec ^ time->tv_sec) & ~7)
829 * Iterate on the ldisc ->read() function until we've gotten all
830 * the data the ldisc has for us.
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.
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.
839 static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
840 struct file *file, struct iov_iter *to)
844 unsigned long offset = 0;
846 size_t count = iov_iter_count(to);
851 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
852 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
857 /* Did we have an earlier error (ie -EFAULT)? */
863 * -EOVERFLOW means we didn't have enough space
864 * for a whole packet, and we shouldn't return
867 if (retval == -EOVERFLOW)
872 copied = copy_to_iter(kernel_buf, size, to);
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.
880 * But make sure size is zeroed.
882 if (unlikely(copied != size)) {
888 /* We always clear tty buffer in case they contained passwords */
889 memzero_explicit(kernel_buf, sizeof(kernel_buf));
890 return offset ? offset : retval;
895 * tty_read - read method for tty device files
896 * @iocb: kernel I/O control block
897 * @to: destination for the data read
899 * Perform the read system call function on this terminal device. Checks
900 * for hung up devices before calling the line discipline method.
903 * Locks the line discipline internally while needed. Multiple read calls
904 * may be outstanding in parallel.
906 static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
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;
914 if (tty_paranoia_check(tty, inode, "tty_read"))
916 if (!tty || tty_io_error(tty))
919 /* We want to wait for the line discipline to sort out in this
922 ld = tty_ldisc_ref_wait(tty);
924 return hung_up_tty_read(iocb, to);
927 i = iterate_tty_read(ld, tty, file, to);
931 tty_update_time(&inode->i_atime);
936 void tty_write_unlock(struct tty_struct *tty)
938 mutex_unlock(&tty->atomic_write_lock);
939 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
942 int tty_write_lock(struct tty_struct *tty, int ndelay)
944 if (!mutex_trylock(&tty->atomic_write_lock)) {
947 if (mutex_lock_interruptible(&tty->atomic_write_lock))
954 * Split writes up in sane blocksizes to avoid
955 * denial-of-service type attacks
957 static 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,
961 struct iov_iter *from)
963 size_t count = iov_iter_count(from);
964 ssize_t ret, written = 0;
967 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
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.
976 * But if TTY_NO_WRITE_SPLIT is set, we should use a
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
985 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
990 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
991 if (tty->write_cnt < chunk) {
992 unsigned char *buf_chunk;
997 buf_chunk = kvmalloc(chunk, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1002 kvfree(tty->write_buf);
1003 tty->write_cnt = chunk;
1004 tty->write_buf = buf_chunk;
1007 /* Do the write .. */
1009 size_t size = count;
1015 if (copy_from_iter(tty->write_buf, size, from) != size)
1018 ret = write(tty, file, tty->write_buf, size);
1026 /* FIXME! Have Al check this! */
1028 iov_iter_revert(from, size-ret);
1034 if (signal_pending(current))
1039 tty_update_time(&file_inode(file)->i_mtime);
1043 tty_write_unlock(tty);
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
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
1056 * We must still hold the BTM and test the CLOSING flag for the moment.
1058 void tty_write_message(struct tty_struct *tty, char *msg)
1061 mutex_lock(&tty->atomic_write_lock);
1063 if (tty->ops->write && tty->count > 0)
1064 tty->ops->write(tty, msg, strlen(msg));
1066 tty_write_unlock(tty);
1070 static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
1072 struct tty_struct *tty = file_tty(file);
1073 struct tty_ldisc *ld;
1076 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1078 if (!tty || !tty->ops->write || tty_io_error(tty))
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);
1085 return hung_up_tty_write(iocb, from);
1086 if (!ld->ops->write)
1089 ret = do_tty_write(ld->ops->write, tty, file, from);
1090 tty_ldisc_deref(ld);
1095 * tty_write - write method for tty device file
1096 * @iocb: kernel I/O control block
1097 * @from: iov_iter with data to write
1099 * Write data to a tty device via the line discipline.
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
1108 static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1110 return file_tty_write(iocb->ki_filp, iocb, from);
1113 ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1115 struct file *p = NULL;
1117 spin_lock(&redirect_lock);
1119 p = get_file(redirect);
1120 spin_unlock(&redirect_lock);
1123 * We know the redirected tty is just another tty, we can
1124 * call file_tty_write() directly with that file pointer.
1129 res = file_tty_write(p, iocb, iter);
1133 return tty_write(iocb, iter);
1137 * tty_send_xchar - send priority character
1138 * @tty: the tty to send to
1139 * @ch: xchar to send
1141 * Send a high priority character to the tty even if stopped.
1143 * Locking: none for xchar method, write ordering for write method.
1145 int tty_send_xchar(struct tty_struct *tty, char ch)
1147 bool was_stopped = tty->flow.stopped;
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);
1156 if (tty_write_lock(tty, 0) < 0)
1157 return -ERESTARTSYS;
1159 down_read(&tty->termios_rwsem);
1162 tty->ops->write(tty, &ch, 1);
1165 up_read(&tty->termios_rwsem);
1166 tty_write_unlock(tty);
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
1176 * Generate a name from a @driver reference and write it to the output buffer
1181 static void pty_line_name(struct tty_driver *driver, int index, char *p)
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);
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
1197 * Generate a name from a @driver reference and write it to the output buffer
1202 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1204 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1205 return sprintf(p, "%s", driver->name);
1207 return sprintf(p, "%s%d", driver->name,
1208 index + driver->name_base);
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
1217 * Return: the tty, if found. If not found, return %NULL or ERR_PTR() if the
1218 * driver lookup() method returns an error.
1220 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1222 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1223 struct file *file, int idx)
1225 struct tty_struct *tty;
1227 if (driver->ops->lookup) {
1229 tty = ERR_PTR(-EIO);
1231 tty = driver->ops->lookup(driver, file, idx);
1233 if (idx >= driver->num)
1234 return ERR_PTR(-EINVAL);
1235 tty = driver->ttys[idx];
1243 * tty_init_termios - helper for termios setup
1244 * @tty: the tty to set up
1246 * Initialise the termios structure for this tty. This runs under the
1247 * %tty_mutex currently so we can be relaxed about ordering.
1249 void tty_init_termios(struct tty_struct *tty)
1251 struct ktermios *tp;
1252 int idx = tty->index;
1254 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1255 tty->termios = tty->driver->init_termios;
1257 /* Check for lazy saved data */
1258 tp = tty->driver->termios[idx];
1261 tty->termios.c_line = tty->driver->init_termios.c_line;
1263 tty->termios = tty->driver->init_termios;
1265 /* Compatibility until drivers always set this */
1266 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1267 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1269 EXPORT_SYMBOL_GPL(tty_init_termios);
1272 * tty_standard_install - usual tty->ops->install
1273 * @driver: the driver for the tty
1276 * If the @driver overrides @tty->ops->install, it still can call this function
1277 * to perform the standard install operations.
1279 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1281 tty_init_termios(tty);
1282 tty_driver_kref_get(driver);
1284 driver->ttys[tty->index] = tty;
1287 EXPORT_SYMBOL_GPL(tty_standard_install);
1290 * tty_driver_install_tty() - install a tty entry in the driver
1291 * @driver: the driver for the tty
1294 * Install a tty object into the driver tables. The @tty->index field will be
1295 * set by the time this is called. This method is responsible for ensuring any
1296 * need additional structures are allocated and configured.
1298 * Locking: tty_mutex for now
1300 static int tty_driver_install_tty(struct tty_driver *driver,
1301 struct tty_struct *tty)
1303 return driver->ops->install ? driver->ops->install(driver, tty) :
1304 tty_standard_install(driver, tty);
1308 * tty_driver_remove_tty() - remove a tty from the driver tables
1309 * @driver: the driver for the tty
1310 * @tty: tty to remove
1312 * Remove a tty object from the driver tables. The tty->index field will be set
1313 * by the time this is called.
1315 * Locking: tty_mutex for now
1317 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1319 if (driver->ops->remove)
1320 driver->ops->remove(driver, tty);
1322 driver->ttys[tty->index] = NULL;
1326 * tty_reopen() - fast re-open of an open tty
1327 * @tty: the tty to open
1329 * Re-opens on master ptys are not allowed and return -%EIO.
1331 * Locking: Caller must hold tty_lock
1332 * Return: 0 on success, -errno on error.
1334 static int tty_reopen(struct tty_struct *tty)
1336 struct tty_driver *driver = tty->driver;
1337 struct tty_ldisc *ld;
1340 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1341 driver->subtype == PTY_TYPE_MASTER)
1347 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1350 ld = tty_ldisc_ref_wait(tty);
1352 tty_ldisc_deref(ld);
1354 retval = tty_ldisc_lock(tty, 5 * HZ);
1359 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1360 tty_ldisc_unlock(tty);
1370 * tty_init_dev - initialise a tty device
1371 * @driver: tty driver we are opening a device on
1372 * @idx: device index
1374 * Prepare a tty device. This may not be a "new" clean device but could also be
1375 * an active device. The pty drivers require special handling because of this.
1378 * The function is called under the tty_mutex, which protects us from the
1379 * tty struct or driver itself going away.
1381 * On exit the tty device has the line discipline attached and a reference
1382 * count of 1. If a pair was created for pty/tty use and the other was a pty
1383 * master then it too has a reference count of 1.
1385 * WSH 06/09/97: Rewritten to remove races and properly clean up after a failed
1386 * open. The new code protects the open with a mutex, so it's really quite
1387 * straightforward. The mutex locking can probably be relaxed for the (most
1388 * common) case of reopening a tty.
1390 * Return: new tty structure
1392 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1394 struct tty_struct *tty;
1398 * First time open is complex, especially for PTY devices.
1399 * This code guarantees that either everything succeeds and the
1400 * TTY is ready for operation, or else the table slots are vacated
1401 * and the allocated memory released. (Except that the termios
1405 if (!try_module_get(driver->owner))
1406 return ERR_PTR(-ENODEV);
1408 tty = alloc_tty_struct(driver, idx);
1411 goto err_module_put;
1415 retval = tty_driver_install_tty(driver, tty);
1420 tty->port = driver->ports[idx];
1422 if (WARN_RATELIMIT(!tty->port,
1423 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1424 __func__, tty->driver->name)) {
1426 goto err_release_lock;
1429 retval = tty_ldisc_lock(tty, 5 * HZ);
1431 goto err_release_lock;
1432 tty->port->itty = tty;
1435 * Structures all installed ... call the ldisc open routines.
1436 * If we fail here just call release_tty to clean up. No need
1437 * to decrement the use counts, as release_tty doesn't care.
1439 retval = tty_ldisc_setup(tty, tty->link);
1441 goto err_release_tty;
1442 tty_ldisc_unlock(tty);
1443 /* Return the tty locked so that it cannot vanish under the caller */
1448 free_tty_struct(tty);
1450 module_put(driver->owner);
1451 return ERR_PTR(retval);
1453 /* call the tty release_tty routine to clean out this slot */
1455 tty_ldisc_unlock(tty);
1456 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1460 release_tty(tty, idx);
1461 return ERR_PTR(retval);
1465 * tty_save_termios() - save tty termios data in driver table
1466 * @tty: tty whose termios data to save
1468 * Locking: Caller guarantees serialisation with tty_init_termios().
1470 void tty_save_termios(struct tty_struct *tty)
1472 struct ktermios *tp;
1473 int idx = tty->index;
1475 /* If the port is going to reset then it has no termios to save */
1476 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1479 /* Stash the termios data */
1480 tp = tty->driver->termios[idx];
1482 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1485 tty->driver->termios[idx] = tp;
1489 EXPORT_SYMBOL_GPL(tty_save_termios);
1492 * tty_flush_works - flush all works of a tty/pty pair
1493 * @tty: tty device to flush works for (or either end of a pty pair)
1495 * Sync flush all works belonging to @tty (and the 'other' tty).
1497 static void tty_flush_works(struct tty_struct *tty)
1499 flush_work(&tty->SAK_work);
1500 flush_work(&tty->hangup_work);
1502 flush_work(&tty->link->SAK_work);
1503 flush_work(&tty->link->hangup_work);
1508 * release_one_tty - release tty structure memory
1509 * @work: work of tty we are obliterating
1511 * Releases memory associated with a tty structure, and clears out the
1512 * driver table slots. This function is called when a device is no longer
1513 * in use. It also gets called when setup of a device fails.
1516 * takes the file list lock internally when working on the list of ttys
1517 * that the driver keeps.
1519 * This method gets called from a work queue so that the driver private
1520 * cleanup ops can sleep (needed for USB at least)
1522 static void release_one_tty(struct work_struct *work)
1524 struct tty_struct *tty =
1525 container_of(work, struct tty_struct, hangup_work);
1526 struct tty_driver *driver = tty->driver;
1527 struct module *owner = driver->owner;
1529 if (tty->ops->cleanup)
1530 tty->ops->cleanup(tty);
1532 tty_driver_kref_put(driver);
1535 spin_lock(&tty->files_lock);
1536 list_del_init(&tty->tty_files);
1537 spin_unlock(&tty->files_lock);
1539 put_pid(tty->ctrl.pgrp);
1540 put_pid(tty->ctrl.session);
1541 free_tty_struct(tty);
1544 static void queue_release_one_tty(struct kref *kref)
1546 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1548 /* The hangup queue is now free so we can reuse it rather than
1549 * waste a chunk of memory for each port.
1551 INIT_WORK(&tty->hangup_work, release_one_tty);
1552 schedule_work(&tty->hangup_work);
1556 * tty_kref_put - release a tty kref
1559 * Release a reference to the @tty device and if need be let the kref layer
1560 * destruct the object for us.
1562 void tty_kref_put(struct tty_struct *tty)
1565 kref_put(&tty->kref, queue_release_one_tty);
1567 EXPORT_SYMBOL(tty_kref_put);
1570 * release_tty - release tty structure memory
1571 * @tty: tty device release
1572 * @idx: index of the tty device release
1574 * Release both @tty and a possible linked partner (think pty pair),
1575 * and decrement the refcount of the backing module.
1579 * takes the file list lock internally when working on the list of ttys
1580 * that the driver keeps.
1582 static void release_tty(struct tty_struct *tty, int idx)
1584 /* This should always be true but check for the moment */
1585 WARN_ON(tty->index != idx);
1586 WARN_ON(!mutex_is_locked(&tty_mutex));
1587 if (tty->ops->shutdown)
1588 tty->ops->shutdown(tty);
1589 tty_save_termios(tty);
1590 tty_driver_remove_tty(tty->driver, tty);
1592 tty->port->itty = NULL;
1594 tty->link->port->itty = NULL;
1596 tty_buffer_cancel_work(tty->port);
1598 tty_buffer_cancel_work(tty->link->port);
1600 tty_kref_put(tty->link);
1605 * tty_release_checks - check a tty before real release
1606 * @tty: tty to check
1607 * @idx: index of the tty
1609 * Performs some paranoid checking before true release of the @tty. This is a
1610 * no-op unless %TTY_PARANOIA_CHECK is defined.
1612 static int tty_release_checks(struct tty_struct *tty, int idx)
1614 #ifdef TTY_PARANOIA_CHECK
1615 if (idx < 0 || idx >= tty->driver->num) {
1616 tty_debug(tty, "bad idx %d\n", idx);
1620 /* not much to check for devpts */
1621 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1624 if (tty != tty->driver->ttys[idx]) {
1625 tty_debug(tty, "bad driver table[%d] = %p\n",
1626 idx, tty->driver->ttys[idx]);
1629 if (tty->driver->other) {
1630 struct tty_struct *o_tty = tty->link;
1632 if (o_tty != tty->driver->other->ttys[idx]) {
1633 tty_debug(tty, "bad other table[%d] = %p\n",
1634 idx, tty->driver->other->ttys[idx]);
1637 if (o_tty->link != tty) {
1638 tty_debug(tty, "bad link = %p\n", o_tty->link);
1647 * tty_kclose - closes tty opened by tty_kopen
1650 * Performs the final steps to release and free a tty device. It is the same as
1651 * tty_release_struct() except that it also resets %TTY_PORT_KOPENED flag on
1654 void tty_kclose(struct tty_struct *tty)
1657 * Ask the line discipline code to release its structures
1659 tty_ldisc_release(tty);
1661 /* Wait for pending work before tty destruction commences */
1662 tty_flush_works(tty);
1664 tty_debug_hangup(tty, "freeing structure\n");
1666 * The release_tty function takes care of the details of clearing
1667 * the slots and preserving the termios structure.
1669 mutex_lock(&tty_mutex);
1670 tty_port_set_kopened(tty->port, 0);
1671 release_tty(tty, tty->index);
1672 mutex_unlock(&tty_mutex);
1674 EXPORT_SYMBOL_GPL(tty_kclose);
1677 * tty_release_struct - release a tty struct
1679 * @idx: index of the tty
1681 * Performs the final steps to release and free a tty device. It is roughly the
1682 * reverse of tty_init_dev().
1684 void tty_release_struct(struct tty_struct *tty, int idx)
1687 * Ask the line discipline code to release its structures
1689 tty_ldisc_release(tty);
1691 /* Wait for pending work before tty destruction commmences */
1692 tty_flush_works(tty);
1694 tty_debug_hangup(tty, "freeing structure\n");
1696 * The release_tty function takes care of the details of clearing
1697 * the slots and preserving the termios structure.
1699 mutex_lock(&tty_mutex);
1700 release_tty(tty, idx);
1701 mutex_unlock(&tty_mutex);
1703 EXPORT_SYMBOL_GPL(tty_release_struct);
1706 * tty_release - vfs callback for close
1707 * @inode: inode of tty
1708 * @filp: file pointer for handle to tty
1710 * Called the last time each file handle is closed that references this tty.
1711 * There may however be several such references.
1714 * Takes BKL. See tty_release_dev().
1716 * Even releasing the tty structures is a tricky business. We have to be very
1717 * careful that the structures are all released at the same time, as interrupts
1718 * might otherwise get the wrong pointers.
1720 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1721 * lead to double frees or releasing memory still in use.
1723 int tty_release(struct inode *inode, struct file *filp)
1725 struct tty_struct *tty = file_tty(filp);
1726 struct tty_struct *o_tty = NULL;
1727 int do_sleep, final;
1732 if (tty_paranoia_check(tty, inode, __func__))
1736 check_tty_count(tty, __func__);
1738 __tty_fasync(-1, filp, 0);
1741 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1742 tty->driver->subtype == PTY_TYPE_MASTER)
1745 if (tty_release_checks(tty, idx)) {
1750 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1752 if (tty->ops->close)
1753 tty->ops->close(tty, filp);
1755 /* If tty is pty master, lock the slave pty (stable lock order) */
1756 tty_lock_slave(o_tty);
1759 * Sanity check: if tty->count is going to zero, there shouldn't be
1760 * any waiters on tty->read_wait or tty->write_wait. We test the
1761 * wait queues and kick everyone out _before_ actually starting to
1762 * close. This ensures that we won't block while releasing the tty
1765 * The test for the o_tty closing is necessary, since the master and
1766 * slave sides may close in any order. If the slave side closes out
1767 * first, its count will be one, since the master side holds an open.
1768 * Thus this test wouldn't be triggered at the time the slave closed,
1774 if (tty->count <= 1) {
1775 if (waitqueue_active(&tty->read_wait)) {
1776 wake_up_poll(&tty->read_wait, EPOLLIN);
1779 if (waitqueue_active(&tty->write_wait)) {
1780 wake_up_poll(&tty->write_wait, EPOLLOUT);
1784 if (o_tty && o_tty->count <= 1) {
1785 if (waitqueue_active(&o_tty->read_wait)) {
1786 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1789 if (waitqueue_active(&o_tty->write_wait)) {
1790 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1799 tty_warn(tty, "read/write wait queue active!\n");
1801 schedule_timeout_killable(timeout);
1802 if (timeout < 120 * HZ)
1803 timeout = 2 * timeout + 1;
1805 timeout = MAX_SCHEDULE_TIMEOUT;
1809 if (--o_tty->count < 0) {
1810 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1814 if (--tty->count < 0) {
1815 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1820 * We've decremented tty->count, so we need to remove this file
1821 * descriptor off the tty->tty_files list; this serves two
1823 * - check_tty_count sees the correct number of file descriptors
1824 * associated with this tty.
1825 * - do_tty_hangup no longer sees this file descriptor as
1826 * something that needs to be handled for hangups.
1831 * Perform some housekeeping before deciding whether to return.
1833 * If _either_ side is closing, make sure there aren't any
1834 * processes that still think tty or o_tty is their controlling
1838 read_lock(&tasklist_lock);
1839 session_clear_tty(tty->ctrl.session);
1841 session_clear_tty(o_tty->ctrl.session);
1842 read_unlock(&tasklist_lock);
1845 /* check whether both sides are closing ... */
1846 final = !tty->count && !(o_tty && o_tty->count);
1848 tty_unlock_slave(o_tty);
1851 /* At this point, the tty->count == 0 should ensure a dead tty
1852 * cannot be re-opened by a racing opener.
1858 tty_debug_hangup(tty, "final close\n");
1860 tty_release_struct(tty, idx);
1865 * tty_open_current_tty - get locked tty of current task
1866 * @device: device number
1867 * @filp: file pointer to tty
1868 * @return: locked tty of the current task iff @device is /dev/tty
1870 * Performs a re-open of the current task's controlling tty.
1872 * We cannot return driver and index like for the other nodes because devpts
1873 * will not work then. It expects inodes to be from devpts FS.
1875 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1877 struct tty_struct *tty;
1880 if (device != MKDEV(TTYAUX_MAJOR, 0))
1883 tty = get_current_tty();
1885 return ERR_PTR(-ENXIO);
1887 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1890 tty_kref_put(tty); /* safe to drop the kref now */
1892 retval = tty_reopen(tty);
1895 tty = ERR_PTR(retval);
1901 * tty_lookup_driver - lookup a tty driver for a given device file
1902 * @device: device number
1903 * @filp: file pointer to tty
1904 * @index: index for the device in the @return driver
1906 * If returned value is not erroneous, the caller is responsible to decrement
1907 * the refcount by tty_driver_kref_put().
1909 * Locking: %tty_mutex protects get_tty_driver()
1911 * Return: driver for this inode (with increased refcount)
1913 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1916 struct tty_driver *driver = NULL;
1920 case MKDEV(TTY_MAJOR, 0): {
1921 extern struct tty_driver *console_driver;
1923 driver = tty_driver_kref_get(console_driver);
1924 *index = fg_console;
1928 case MKDEV(TTYAUX_MAJOR, 1): {
1929 struct tty_driver *console_driver = console_device(index);
1931 if (console_driver) {
1932 driver = tty_driver_kref_get(console_driver);
1933 if (driver && filp) {
1934 /* Don't let /dev/console block */
1935 filp->f_flags |= O_NONBLOCK;
1940 tty_driver_kref_put(driver);
1941 return ERR_PTR(-ENODEV);
1944 driver = get_tty_driver(device, index);
1946 return ERR_PTR(-ENODEV);
1952 static struct tty_struct *tty_kopen(dev_t device, int shared)
1954 struct tty_struct *tty;
1955 struct tty_driver *driver;
1958 mutex_lock(&tty_mutex);
1959 driver = tty_lookup_driver(device, NULL, &index);
1960 if (IS_ERR(driver)) {
1961 mutex_unlock(&tty_mutex);
1962 return ERR_CAST(driver);
1965 /* check whether we're reopening an existing tty */
1966 tty = tty_driver_lookup_tty(driver, NULL, index);
1967 if (IS_ERR(tty) || shared)
1971 /* drop kref from tty_driver_lookup_tty() */
1973 tty = ERR_PTR(-EBUSY);
1974 } else { /* tty_init_dev returns tty with the tty_lock held */
1975 tty = tty_init_dev(driver, index);
1978 tty_port_set_kopened(tty->port, 1);
1981 mutex_unlock(&tty_mutex);
1982 tty_driver_kref_put(driver);
1987 * tty_kopen_exclusive - open a tty device for kernel
1988 * @device: dev_t of device to open
1990 * Opens tty exclusively for kernel. Performs the driver lookup, makes sure
1991 * it's not already opened and performs the first-time tty initialization.
1993 * Claims the global %tty_mutex to serialize:
1994 * * concurrent first-time tty initialization
1995 * * concurrent tty driver removal w/ lookup
1996 * * concurrent tty removal from driver table
1998 * Return: the locked initialized &tty_struct
2000 struct tty_struct *tty_kopen_exclusive(dev_t device)
2002 return tty_kopen(device, 0);
2004 EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2007 * tty_kopen_shared - open a tty device for shared in-kernel use
2008 * @device: dev_t of device to open
2010 * Opens an already existing tty for in-kernel use. Compared to
2011 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2013 * Locking: identical to tty_kopen() above.
2015 struct tty_struct *tty_kopen_shared(dev_t device)
2017 return tty_kopen(device, 1);
2019 EXPORT_SYMBOL_GPL(tty_kopen_shared);
2022 * tty_open_by_driver - open a tty device
2023 * @device: dev_t of device to open
2024 * @filp: file pointer to tty
2026 * Performs the driver lookup, checks for a reopen, or otherwise performs the
2027 * first-time tty initialization.
2030 * Claims the global tty_mutex to serialize:
2031 * * concurrent first-time tty initialization
2032 * * concurrent tty driver removal w/ lookup
2033 * * concurrent tty removal from driver table
2035 * Return: the locked initialized or re-opened &tty_struct
2037 static struct tty_struct *tty_open_by_driver(dev_t device,
2040 struct tty_struct *tty;
2041 struct tty_driver *driver = NULL;
2045 mutex_lock(&tty_mutex);
2046 driver = tty_lookup_driver(device, filp, &index);
2047 if (IS_ERR(driver)) {
2048 mutex_unlock(&tty_mutex);
2049 return ERR_CAST(driver);
2052 /* check whether we're reopening an existing tty */
2053 tty = tty_driver_lookup_tty(driver, filp, index);
2055 mutex_unlock(&tty_mutex);
2060 if (tty_port_kopened(tty->port)) {
2062 mutex_unlock(&tty_mutex);
2063 tty = ERR_PTR(-EBUSY);
2066 mutex_unlock(&tty_mutex);
2067 retval = tty_lock_interruptible(tty);
2068 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2070 if (retval == -EINTR)
2071 retval = -ERESTARTSYS;
2072 tty = ERR_PTR(retval);
2075 retval = tty_reopen(tty);
2078 tty = ERR_PTR(retval);
2080 } else { /* Returns with the tty_lock held for now */
2081 tty = tty_init_dev(driver, index);
2082 mutex_unlock(&tty_mutex);
2085 tty_driver_kref_put(driver);
2090 * tty_open - open a tty device
2091 * @inode: inode of device file
2092 * @filp: file pointer to tty
2094 * tty_open() and tty_release() keep up the tty count that contains the number
2095 * of opens done on a tty. We cannot use the inode-count, as different inodes
2096 * might point to the same tty.
2098 * Open-counting is needed for pty masters, as well as for keeping track of
2099 * serial lines: DTR is dropped when the last close happens.
2100 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2102 * The termios state of a pty is reset on the first open so that settings don't
2103 * persist across reuse.
2106 * * %tty_mutex protects tty, tty_lookup_driver() and tty_init_dev().
2107 * * @tty->count should protect the rest.
2108 * * ->siglock protects ->signal/->sighand
2110 * Note: the tty_unlock/lock cases without a ref are only safe due to %tty_mutex
2112 static int tty_open(struct inode *inode, struct file *filp)
2114 struct tty_struct *tty;
2116 dev_t device = inode->i_rdev;
2117 unsigned saved_flags = filp->f_flags;
2119 nonseekable_open(inode, filp);
2122 retval = tty_alloc_file(filp);
2126 tty = tty_open_current_tty(device, filp);
2128 tty = tty_open_by_driver(device, filp);
2131 tty_free_file(filp);
2132 retval = PTR_ERR(tty);
2133 if (retval != -EAGAIN || signal_pending(current))
2139 tty_add_file(tty, filp);
2141 check_tty_count(tty, __func__);
2142 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2145 retval = tty->ops->open(tty, filp);
2148 filp->f_flags = saved_flags;
2151 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2153 tty_unlock(tty); /* need to call tty_release without BTM */
2154 tty_release(inode, filp);
2155 if (retval != -ERESTARTSYS)
2158 if (signal_pending(current))
2163 * Need to reset f_op in case a hangup happened.
2165 if (tty_hung_up_p(filp))
2166 filp->f_op = &tty_fops;
2169 clear_bit(TTY_HUPPED, &tty->flags);
2171 noctty = (filp->f_flags & O_NOCTTY) ||
2172 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2173 device == MKDEV(TTYAUX_MAJOR, 1) ||
2174 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2175 tty->driver->subtype == PTY_TYPE_MASTER);
2177 tty_open_proc_set_tty(filp, tty);
2184 * tty_poll - check tty status
2185 * @filp: file being polled
2186 * @wait: poll wait structures to update
2188 * Call the line discipline polling method to obtain the poll status of the
2191 * Locking: locks called line discipline but ldisc poll method may be
2192 * re-entered freely by other callers.
2194 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2196 struct tty_struct *tty = file_tty(filp);
2197 struct tty_ldisc *ld;
2200 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2203 ld = tty_ldisc_ref_wait(tty);
2205 return hung_up_tty_poll(filp, wait);
2207 ret = ld->ops->poll(tty, filp, wait);
2208 tty_ldisc_deref(ld);
2212 static int __tty_fasync(int fd, struct file *filp, int on)
2214 struct tty_struct *tty = file_tty(filp);
2215 unsigned long flags;
2218 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2221 retval = fasync_helper(fd, filp, on, &tty->fasync);
2229 spin_lock_irqsave(&tty->ctrl.lock, flags);
2230 if (tty->ctrl.pgrp) {
2231 pid = tty->ctrl.pgrp;
2232 type = PIDTYPE_PGID;
2234 pid = task_pid(current);
2235 type = PIDTYPE_TGID;
2238 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
2239 __f_setown(filp, pid, type, 0);
2247 static int tty_fasync(int fd, struct file *filp, int on)
2249 struct tty_struct *tty = file_tty(filp);
2250 int retval = -ENOTTY;
2253 if (!tty_hung_up_p(filp))
2254 retval = __tty_fasync(fd, filp, on);
2260 static bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI);
2262 * tiocsti - fake input character
2263 * @tty: tty to fake input into
2264 * @p: pointer to character
2266 * Fake input to a tty device. Does the necessary locking and input management.
2268 * FIXME: does not honour flow control ??
2271 * * Called functions take tty_ldiscs_lock
2272 * * current->signal->tty check is safe without locks
2274 static int tiocsti(struct tty_struct *tty, char __user *p)
2277 struct tty_ldisc *ld;
2279 if (!tty_legacy_tiocsti)
2282 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2284 if (get_user(ch, p))
2286 tty_audit_tiocsti(tty, ch);
2287 ld = tty_ldisc_ref_wait(tty);
2290 tty_buffer_lock_exclusive(tty->port);
2291 if (ld->ops->receive_buf)
2292 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2293 tty_buffer_unlock_exclusive(tty->port);
2294 tty_ldisc_deref(ld);
2299 * tiocgwinsz - implement window query ioctl
2301 * @arg: user buffer for result
2303 * Copies the kernel idea of the window size into the user buffer.
2305 * Locking: @tty->winsize_mutex is taken to ensure the winsize data is
2308 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2312 mutex_lock(&tty->winsize_mutex);
2313 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2314 mutex_unlock(&tty->winsize_mutex);
2316 return err ? -EFAULT : 0;
2320 * tty_do_resize - resize event
2321 * @tty: tty being resized
2322 * @ws: new dimensions
2324 * Update the termios variables and send the necessary signals to peform a
2325 * terminal resize correctly.
2327 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2332 mutex_lock(&tty->winsize_mutex);
2333 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2336 /* Signal the foreground process group */
2337 pgrp = tty_get_pgrp(tty);
2339 kill_pgrp(pgrp, SIGWINCH, 1);
2344 mutex_unlock(&tty->winsize_mutex);
2347 EXPORT_SYMBOL(tty_do_resize);
2350 * tiocswinsz - implement window size set ioctl
2351 * @tty: tty side of tty
2352 * @arg: user buffer for result
2354 * Copies the user idea of the window size to the kernel. Traditionally this is
2355 * just advisory information but for the Linux console it actually has driver
2356 * level meaning and triggers a VC resize.
2359 * Driver dependent. The default do_resize method takes the tty termios
2360 * mutex and ctrl.lock. The console takes its own lock then calls into the
2363 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2365 struct winsize tmp_ws;
2367 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2370 if (tty->ops->resize)
2371 return tty->ops->resize(tty, &tmp_ws);
2373 return tty_do_resize(tty, &tmp_ws);
2377 * tioccons - allow admin to move logical console
2378 * @file: the file to become console
2380 * Allow the administrator to move the redirected console device.
2382 * Locking: uses redirect_lock to guard the redirect information
2384 static int tioccons(struct file *file)
2386 if (!capable(CAP_SYS_ADMIN))
2388 if (file->f_op->write_iter == redirected_tty_write) {
2391 spin_lock(&redirect_lock);
2394 spin_unlock(&redirect_lock);
2399 if (file->f_op->write_iter != tty_write)
2401 if (!(file->f_mode & FMODE_WRITE))
2403 if (!(file->f_mode & FMODE_CAN_WRITE))
2405 spin_lock(&redirect_lock);
2407 spin_unlock(&redirect_lock);
2410 redirect = get_file(file);
2411 spin_unlock(&redirect_lock);
2416 * tiocsetd - set line discipline
2418 * @p: pointer to user data
2420 * Set the line discipline according to user request.
2422 * Locking: see tty_set_ldisc(), this function is just a helper
2424 static int tiocsetd(struct tty_struct *tty, int __user *p)
2429 if (get_user(disc, p))
2432 ret = tty_set_ldisc(tty, disc);
2438 * tiocgetd - get line discipline
2440 * @p: pointer to user data
2442 * Retrieves the line discipline id directly from the ldisc.
2444 * Locking: waits for ldisc reference (in case the line discipline is changing
2445 * or the @tty is being hungup)
2447 static int tiocgetd(struct tty_struct *tty, int __user *p)
2449 struct tty_ldisc *ld;
2452 ld = tty_ldisc_ref_wait(tty);
2455 ret = put_user(ld->ops->num, p);
2456 tty_ldisc_deref(ld);
2461 * send_break - performed time break
2462 * @tty: device to break on
2463 * @duration: timeout in mS
2465 * Perform a timed break on hardware that lacks its own driver level timed
2466 * break functionality.
2469 * @tty->atomic_write_lock serializes
2471 static int send_break(struct tty_struct *tty, unsigned int duration)
2475 if (tty->ops->break_ctl == NULL)
2478 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2479 retval = tty->ops->break_ctl(tty, duration);
2481 /* Do the work ourselves */
2482 if (tty_write_lock(tty, 0) < 0)
2484 retval = tty->ops->break_ctl(tty, -1);
2487 if (!signal_pending(current))
2488 msleep_interruptible(duration);
2489 retval = tty->ops->break_ctl(tty, 0);
2491 tty_write_unlock(tty);
2492 if (signal_pending(current))
2499 * tty_tiocmget - get modem status
2501 * @p: pointer to result
2503 * Obtain the modem status bits from the tty driver if the feature is
2504 * supported. Return -%ENOTTY if it is not available.
2506 * Locking: none (up to the driver)
2508 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2510 int retval = -ENOTTY;
2512 if (tty->ops->tiocmget) {
2513 retval = tty->ops->tiocmget(tty);
2516 retval = put_user(retval, p);
2522 * tty_tiocmset - set modem status
2524 * @cmd: command - clear bits, set bits or set all
2525 * @p: pointer to desired bits
2527 * Set the modem status bits from the tty driver if the feature
2528 * is supported. Return -%ENOTTY if it is not available.
2530 * Locking: none (up to the driver)
2532 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2536 unsigned int set, clear, val;
2538 if (tty->ops->tiocmset == NULL)
2541 retval = get_user(val, p);
2557 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2558 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2559 return tty->ops->tiocmset(tty, set, clear);
2563 * tty_get_icount - get tty statistics
2565 * @icount: output parameter
2567 * Gets a copy of the @tty's icount statistics.
2569 * Locking: none (up to the driver)
2571 int tty_get_icount(struct tty_struct *tty,
2572 struct serial_icounter_struct *icount)
2574 memset(icount, 0, sizeof(*icount));
2576 if (tty->ops->get_icount)
2577 return tty->ops->get_icount(tty, icount);
2581 EXPORT_SYMBOL_GPL(tty_get_icount);
2583 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2585 struct serial_icounter_struct icount;
2588 retval = tty_get_icount(tty, &icount);
2592 if (copy_to_user(arg, &icount, sizeof(icount)))
2597 static int tty_set_serial(struct tty_struct *tty, struct serial_struct *ss)
2599 char comm[TASK_COMM_LEN];
2602 flags = ss->flags & ASYNC_DEPRECATED;
2605 pr_warn_ratelimited("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2606 __func__, get_task_comm(comm, current), flags);
2608 if (!tty->ops->set_serial)
2611 return tty->ops->set_serial(tty, ss);
2614 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2616 struct serial_struct v;
2618 if (copy_from_user(&v, ss, sizeof(*ss)))
2621 return tty_set_serial(tty, &v);
2624 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2626 struct serial_struct v;
2629 memset(&v, 0, sizeof(v));
2630 if (!tty->ops->get_serial)
2632 err = tty->ops->get_serial(tty, &v);
2633 if (!err && copy_to_user(ss, &v, sizeof(v)))
2639 * if pty, return the slave side (real_tty)
2640 * otherwise, return self
2642 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2644 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2645 tty->driver->subtype == PTY_TYPE_MASTER)
2651 * Split this up, as gcc can choke on it otherwise..
2653 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2655 struct tty_struct *tty = file_tty(file);
2656 struct tty_struct *real_tty;
2657 void __user *p = (void __user *)arg;
2659 struct tty_ldisc *ld;
2661 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2664 real_tty = tty_pair_get_tty(tty);
2667 * Factor out some common prep work
2675 retval = tty_check_change(tty);
2678 if (cmd != TIOCCBRK) {
2679 tty_wait_until_sent(tty, 0);
2680 if (signal_pending(current))
2691 return tiocsti(tty, p);
2693 return tiocgwinsz(real_tty, p);
2695 return tiocswinsz(real_tty, p);
2697 return real_tty != tty ? -EINVAL : tioccons(file);
2699 set_bit(TTY_EXCLUSIVE, &tty->flags);
2702 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2706 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2708 return put_user(excl, (int __user *)p);
2711 return tiocgetd(tty, p);
2713 return tiocsetd(tty, p);
2715 if (!capable(CAP_SYS_ADMIN))
2721 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2723 return put_user(ret, (unsigned int __user *)p);
2728 case TIOCSBRK: /* Turn break on, unconditionally */
2729 if (tty->ops->break_ctl)
2730 return tty->ops->break_ctl(tty, -1);
2732 case TIOCCBRK: /* Turn break off, unconditionally */
2733 if (tty->ops->break_ctl)
2734 return tty->ops->break_ctl(tty, 0);
2736 case TCSBRK: /* SVID version: non-zero arg --> no break */
2737 /* non-zero arg means wait for all output data
2738 * to be sent (performed above) but don't send break.
2739 * This is used by the tcdrain() termios function.
2742 return send_break(tty, 250);
2744 case TCSBRKP: /* support for POSIX tcsendbreak() */
2745 return send_break(tty, arg ? arg*100 : 250);
2748 return tty_tiocmget(tty, p);
2752 return tty_tiocmset(tty, cmd, p);
2754 return tty_tiocgicount(tty, p);
2759 /* flush tty buffer and allow ldisc to process ioctl */
2760 tty_buffer_flush(tty, NULL);
2765 return tty_tiocsserial(tty, p);
2767 return tty_tiocgserial(tty, p);
2769 /* Special because the struct file is needed */
2770 return ptm_open_peer(file, tty, (int)arg);
2772 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2773 if (retval != -ENOIOCTLCMD)
2776 if (tty->ops->ioctl) {
2777 retval = tty->ops->ioctl(tty, cmd, arg);
2778 if (retval != -ENOIOCTLCMD)
2781 ld = tty_ldisc_ref_wait(tty);
2783 return hung_up_tty_ioctl(file, cmd, arg);
2785 if (ld->ops->ioctl) {
2786 retval = ld->ops->ioctl(tty, cmd, arg);
2787 if (retval == -ENOIOCTLCMD)
2790 tty_ldisc_deref(ld);
2794 #ifdef CONFIG_COMPAT
2796 struct serial_struct32 {
2802 compat_int_t xmit_fifo_size;
2803 compat_int_t custom_divisor;
2804 compat_int_t baud_base;
2805 unsigned short close_delay;
2809 unsigned short closing_wait; /* time to wait before closing */
2810 unsigned short closing_wait2; /* no longer used... */
2811 compat_uint_t iomem_base;
2812 unsigned short iomem_reg_shift;
2813 unsigned int port_high;
2814 /* compat_ulong_t iomap_base FIXME */
2815 compat_int_t reserved;
2818 static int compat_tty_tiocsserial(struct tty_struct *tty,
2819 struct serial_struct32 __user *ss)
2821 struct serial_struct32 v32;
2822 struct serial_struct v;
2824 if (copy_from_user(&v32, ss, sizeof(*ss)))
2827 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2828 v.iomem_base = compat_ptr(v32.iomem_base);
2829 v.iomem_reg_shift = v32.iomem_reg_shift;
2830 v.port_high = v32.port_high;
2833 return tty_set_serial(tty, &v);
2836 static int compat_tty_tiocgserial(struct tty_struct *tty,
2837 struct serial_struct32 __user *ss)
2839 struct serial_struct32 v32;
2840 struct serial_struct v;
2843 memset(&v, 0, sizeof(v));
2844 memset(&v32, 0, sizeof(v32));
2846 if (!tty->ops->get_serial)
2848 err = tty->ops->get_serial(tty, &v);
2850 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2851 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2852 0xfffffff : ptr_to_compat(v.iomem_base);
2853 v32.iomem_reg_shift = v.iomem_reg_shift;
2854 v32.port_high = v.port_high;
2855 if (copy_to_user(ss, &v32, sizeof(v32)))
2860 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2863 struct tty_struct *tty = file_tty(file);
2864 struct tty_ldisc *ld;
2865 int retval = -ENOIOCTLCMD;
2914 case TIOCGLCKTRMIOS:
2915 case TIOCSLCKTRMIOS:
2927 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2943 return tty_ioctl(file, cmd, arg);
2946 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2951 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2953 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2955 if (tty->ops->compat_ioctl) {
2956 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2957 if (retval != -ENOIOCTLCMD)
2961 ld = tty_ldisc_ref_wait(tty);
2963 return hung_up_tty_compat_ioctl(file, cmd, arg);
2964 if (ld->ops->compat_ioctl)
2965 retval = ld->ops->compat_ioctl(tty, cmd, arg);
2966 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2967 retval = ld->ops->ioctl(tty, (unsigned long)compat_ptr(cmd),
2969 tty_ldisc_deref(ld);
2975 static int this_tty(const void *t, struct file *file, unsigned fd)
2977 if (likely(file->f_op->read_iter != tty_read))
2979 return file_tty(file) != t ? 0 : fd + 1;
2983 * This implements the "Secure Attention Key" --- the idea is to
2984 * prevent trojan horses by killing all processes associated with this
2985 * tty when the user hits the "Secure Attention Key". Required for
2986 * super-paranoid applications --- see the Orange Book for more details.
2988 * This code could be nicer; ideally it should send a HUP, wait a few
2989 * seconds, then send a INT, and then a KILL signal. But you then
2990 * have to coordinate with the init process, since all processes associated
2991 * with the current tty must be dead before the new getty is allowed
2994 * Now, if it would be correct ;-/ The current code has a nasty hole -
2995 * it doesn't catch files in flight. We may send the descriptor to ourselves
2996 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2998 * Nasty bug: do_SAK is being called in interrupt context. This can
2999 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3001 void __do_SAK(struct tty_struct *tty)
3003 struct task_struct *g, *p;
3004 struct pid *session;
3006 unsigned long flags;
3008 spin_lock_irqsave(&tty->ctrl.lock, flags);
3009 session = get_pid(tty->ctrl.session);
3010 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
3012 tty_ldisc_flush(tty);
3014 tty_driver_flush_buffer(tty);
3016 read_lock(&tasklist_lock);
3017 /* Kill the entire session */
3018 do_each_pid_task(session, PIDTYPE_SID, p) {
3019 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3020 task_pid_nr(p), p->comm);
3021 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3022 } while_each_pid_task(session, PIDTYPE_SID, p);
3024 /* Now kill any processes that happen to have the tty open */
3025 do_each_thread(g, p) {
3026 if (p->signal->tty == tty) {
3027 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3028 task_pid_nr(p), p->comm);
3029 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3034 i = iterate_fd(p->files, 0, this_tty, tty);
3036 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3037 task_pid_nr(p), p->comm, i - 1);
3038 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
3042 } while_each_thread(g, p);
3043 read_unlock(&tasklist_lock);
3047 static void do_SAK_work(struct work_struct *work)
3049 struct tty_struct *tty =
3050 container_of(work, struct tty_struct, SAK_work);
3055 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3056 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3057 * the values which we write to it will be identical to the values which it
3058 * already has. --akpm
3060 void do_SAK(struct tty_struct *tty)
3064 schedule_work(&tty->SAK_work);
3066 EXPORT_SYMBOL(do_SAK);
3068 /* Must put_device() after it's unused! */
3069 static struct device *tty_get_device(struct tty_struct *tty)
3071 dev_t devt = tty_devnum(tty);
3073 return class_find_device_by_devt(&tty_class, devt);
3078 * alloc_tty_struct - allocate a new tty
3079 * @driver: driver which will handle the returned tty
3080 * @idx: minor of the tty
3082 * This subroutine allocates and initializes a tty structure.
3084 * Locking: none - @tty in question is not exposed at this point
3086 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3088 struct tty_struct *tty;
3090 tty = kzalloc(sizeof(*tty), GFP_KERNEL_ACCOUNT);
3094 kref_init(&tty->kref);
3095 if (tty_ldisc_init(tty)) {
3099 tty->ctrl.session = NULL;
3100 tty->ctrl.pgrp = NULL;
3101 mutex_init(&tty->legacy_mutex);
3102 mutex_init(&tty->throttle_mutex);
3103 init_rwsem(&tty->termios_rwsem);
3104 mutex_init(&tty->winsize_mutex);
3105 init_ldsem(&tty->ldisc_sem);
3106 init_waitqueue_head(&tty->write_wait);
3107 init_waitqueue_head(&tty->read_wait);
3108 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3109 mutex_init(&tty->atomic_write_lock);
3110 spin_lock_init(&tty->ctrl.lock);
3111 spin_lock_init(&tty->flow.lock);
3112 spin_lock_init(&tty->files_lock);
3113 INIT_LIST_HEAD(&tty->tty_files);
3114 INIT_WORK(&tty->SAK_work, do_SAK_work);
3116 tty->driver = driver;
3117 tty->ops = driver->ops;
3119 tty_line_name(driver, idx, tty->name);
3120 tty->dev = tty_get_device(tty);
3126 * tty_put_char - write one character to a tty
3128 * @ch: character to write
3130 * Write one byte to the @tty using the provided @tty->ops->put_char() method
3133 * Note: the specific put_char operation in the driver layer may go
3134 * away soon. Don't call it directly, use this method
3136 * Return: the number of characters successfully output.
3138 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3140 if (tty->ops->put_char)
3141 return tty->ops->put_char(tty, ch);
3142 return tty->ops->write(tty, &ch, 1);
3144 EXPORT_SYMBOL_GPL(tty_put_char);
3146 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3147 unsigned int index, unsigned int count)
3151 /* init here, since reused cdevs cause crashes */
3152 driver->cdevs[index] = cdev_alloc();
3153 if (!driver->cdevs[index])
3155 driver->cdevs[index]->ops = &tty_fops;
3156 driver->cdevs[index]->owner = driver->owner;
3157 err = cdev_add(driver->cdevs[index], dev, count);
3159 kobject_put(&driver->cdevs[index]->kobj);
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.
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
3178 * Return: A pointer to the struct device for this tty device (or
3179 * ERR_PTR(-EFOO) on error).
3181 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3182 struct device *device)
3184 return tty_register_device_attr(driver, index, device, NULL, NULL);
3186 EXPORT_SYMBOL(tty_register_device);
3188 static void tty_device_create_release(struct device *dev)
3190 dev_dbg(dev, "releasing...\n");
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.
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.
3210 * Return: A pointer to the struct device for this tty device (or
3211 * ERR_PTR(-EFOO) on error).
3213 struct device *tty_register_device_attr(struct tty_driver *driver,
3214 unsigned index, struct device *device,
3216 const struct attribute_group **attr_grp)
3219 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3220 struct ktermios *tp;
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);
3230 if (driver->type == TTY_DRIVER_TYPE_PTY)
3231 pty_line_name(driver, index, name);
3233 tty_line_name(driver, index, name);
3235 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3237 return ERR_PTR(-ENOMEM);
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);
3247 dev_set_uevent_suppress(dev, 1);
3249 retval = device_register(dev);
3253 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3255 * Free any saved termios data so that the termios state is
3256 * reset when reusing a minor number.
3258 tp = driver->termios[index];
3260 driver->termios[index] = NULL;
3264 retval = tty_cdev_add(driver, devt, index, 1);
3269 dev_set_uevent_suppress(dev, 0);
3270 kobject_uevent(&dev->kobj, KOBJ_ADD);
3279 return ERR_PTR(retval);
3281 EXPORT_SYMBOL_GPL(tty_register_device_attr);
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
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.
3293 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3295 device_destroy(&tty_class, MKDEV(driver->major, driver->minor_start) + index);
3296 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3297 cdev_del(driver->cdevs[index]);
3298 driver->cdevs[index] = NULL;
3301 EXPORT_SYMBOL(tty_unregister_device);
3304 * __tty_alloc_driver -- allocate tty driver
3305 * @lines: count of lines this driver can handle at most
3306 * @owner: module which is responsible for this driver
3307 * @flags: some of %TTY_DRIVER_ flags, will be set in driver->flags
3309 * This should not be called directly, some of the provided macros should be
3310 * used instead. Use IS_ERR() and friends on @retval.
3312 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3313 unsigned long flags)
3315 struct tty_driver *driver;
3316 unsigned int cdevs = 1;
3319 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3320 return ERR_PTR(-EINVAL);
3322 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3324 return ERR_PTR(-ENOMEM);
3326 kref_init(&driver->kref);
3327 driver->num = lines;
3328 driver->owner = owner;
3329 driver->flags = flags;
3331 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3332 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3334 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3336 if (!driver->ttys || !driver->termios) {
3342 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3343 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3345 if (!driver->ports) {
3352 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3353 if (!driver->cdevs) {
3360 kfree(driver->ports);
3361 kfree(driver->ttys);
3362 kfree(driver->termios);
3363 kfree(driver->cdevs);
3365 return ERR_PTR(err);
3367 EXPORT_SYMBOL(__tty_alloc_driver);
3369 static void destruct_tty_driver(struct kref *kref)
3371 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3373 struct ktermios *tp;
3375 if (driver->flags & TTY_DRIVER_INSTALLED) {
3376 for (i = 0; i < driver->num; i++) {
3377 tp = driver->termios[i];
3379 driver->termios[i] = NULL;
3382 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3383 tty_unregister_device(driver, i);
3385 proc_tty_unregister_driver(driver);
3386 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3387 cdev_del(driver->cdevs[0]);
3389 kfree(driver->cdevs);
3390 kfree(driver->ports);
3391 kfree(driver->termios);
3392 kfree(driver->ttys);
3397 * tty_driver_kref_put -- drop a reference to a tty driver
3398 * @driver: driver of which to drop the reference
3400 * The final put will destroy and free up the driver.
3402 void tty_driver_kref_put(struct tty_driver *driver)
3404 kref_put(&driver->kref, destruct_tty_driver);
3406 EXPORT_SYMBOL(tty_driver_kref_put);
3409 * tty_register_driver -- register a tty driver
3410 * @driver: driver to register
3412 * Called by a tty driver to register itself.
3414 int tty_register_driver(struct tty_driver *driver)
3421 if (!driver->major) {
3422 error = alloc_chrdev_region(&dev, driver->minor_start,
3423 driver->num, driver->name);
3425 driver->major = MAJOR(dev);
3426 driver->minor_start = MINOR(dev);
3429 dev = MKDEV(driver->major, driver->minor_start);
3430 error = register_chrdev_region(dev, driver->num, driver->name);
3435 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3436 error = tty_cdev_add(driver, dev, 0, driver->num);
3438 goto err_unreg_char;
3441 mutex_lock(&tty_mutex);
3442 list_add(&driver->tty_drivers, &tty_drivers);
3443 mutex_unlock(&tty_mutex);
3445 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3446 for (i = 0; i < driver->num; i++) {
3447 d = tty_register_device(driver, i, NULL);
3450 goto err_unreg_devs;
3454 proc_tty_register_driver(driver);
3455 driver->flags |= TTY_DRIVER_INSTALLED;
3459 for (i--; i >= 0; i--)
3460 tty_unregister_device(driver, i);
3462 mutex_lock(&tty_mutex);
3463 list_del(&driver->tty_drivers);
3464 mutex_unlock(&tty_mutex);
3467 unregister_chrdev_region(dev, driver->num);
3471 EXPORT_SYMBOL(tty_register_driver);
3474 * tty_unregister_driver -- unregister a tty driver
3475 * @driver: driver to unregister
3477 * Called by a tty driver to unregister itself.
3479 void tty_unregister_driver(struct tty_driver *driver)
3481 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3483 mutex_lock(&tty_mutex);
3484 list_del(&driver->tty_drivers);
3485 mutex_unlock(&tty_mutex);
3487 EXPORT_SYMBOL(tty_unregister_driver);
3489 dev_t tty_devnum(struct tty_struct *tty)
3491 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3493 EXPORT_SYMBOL(tty_devnum);
3495 void tty_default_fops(struct file_operations *fops)
3500 static char *tty_devnode(const struct device *dev, umode_t *mode)
3504 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3505 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3510 const struct class tty_class = {
3512 .devnode = tty_devnode,
3515 static int __init tty_class_init(void)
3517 return class_register(&tty_class);
3520 postcore_initcall(tty_class_init);
3522 /* 3/2004 jmc: why do these devices exist? */
3523 static struct cdev tty_cdev, console_cdev;
3525 static ssize_t show_cons_active(struct device *dev,
3526 struct device_attribute *attr, char *buf)
3528 struct console *cs[16];
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.
3539 console_list_lock();
3541 for_each_console(c) {
3546 if ((c->flags & CON_ENABLED) == 0)
3549 if (i >= ARRAY_SIZE(cs))
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.
3560 int index = cs[i]->index;
3561 struct tty_driver *drv = cs[i]->device(cs[i], &index);
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);
3567 count += sprintf(buf + count, "%s%d",
3568 cs[i]->name, cs[i]->index);
3570 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3574 console_list_unlock();
3578 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3580 static struct attribute *cons_dev_attrs[] = {
3581 &dev_attr_active.attr,
3585 ATTRIBUTE_GROUPS(cons_dev);
3587 static struct device *consdev;
3589 void console_sysfs_notify(void)
3592 sysfs_notify(&consdev->kobj, NULL, "active");
3595 static struct ctl_table tty_table[] = {
3597 .procname = "legacy_tiocsti",
3598 .data = &tty_legacy_tiocsti,
3599 .maxlen = sizeof(tty_legacy_tiocsti),
3601 .proc_handler = proc_dobool,
3604 .procname = "ldisc_autoload",
3605 .data = &tty_ldisc_autoload,
3606 .maxlen = sizeof(tty_ldisc_autoload),
3608 .proc_handler = proc_dointvec,
3609 .extra1 = SYSCTL_ZERO,
3610 .extra2 = SYSCTL_ONE,
3616 * Ok, now we can initialize the rest of the tty devices and can count
3617 * on memory allocations, interrupts etc..
3619 int __init tty_init(void)
3621 register_sysctl_init("dev/tty", tty_table);
3622 cdev_init(&tty_cdev, &tty_fops);
3623 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3624 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3625 panic("Couldn't register /dev/tty driver\n");
3626 device_create(&tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3628 cdev_init(&console_cdev, &console_fops);
3629 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3630 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3631 panic("Couldn't register /dev/console driver\n");
3632 consdev = device_create_with_groups(&tty_class, NULL,
3633 MKDEV(TTYAUX_MAJOR, 1), NULL,
3634 cons_dev_groups, "console");
3635 if (IS_ERR(consdev))
3639 vty_init(&console_fops);