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>
103 #include <linux/uaccess.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>
112 #undef TTY_DEBUG_HANGUP
113 #ifdef TTY_DEBUG_HANGUP
114 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
116 # define tty_debug_hangup(tty, f, args...) do { } while (0)
119 #define TTY_PARANOIA_CHECK 1
120 #define CHECK_TTY_COUNT 1
122 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
123 .c_iflag = ICRNL | IXON,
124 .c_oflag = OPOST | ONLCR,
125 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
126 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
127 ECHOCTL | ECHOKE | IEXTEN,
131 /* .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
140 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
142 /* Mutex to protect creating and releasing a tty */
143 DEFINE_MUTEX(tty_mutex);
145 static ssize_t tty_read(struct kiocb *, struct iov_iter *);
146 static ssize_t tty_write(struct kiocb *, struct iov_iter *);
147 static __poll_t tty_poll(struct file *, poll_table *);
148 static int tty_open(struct inode *, struct file *);
150 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
153 #define tty_compat_ioctl NULL
155 static int __tty_fasync(int fd, struct file *filp, int on);
156 static int tty_fasync(int fd, struct file *filp, int on);
157 static void release_tty(struct tty_struct *tty, int idx);
160 * free_tty_struct - free a disused tty
161 * @tty: tty struct to free
163 * Free the write buffers, tty queue and tty memory itself.
165 * 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 kfree(tty->write_buf);
173 tty->magic = 0xDEADDEAD;
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
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
239 * naming 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. */
251 EXPORT_SYMBOL(tty_name);
253 const char *tty_driver_name(const struct tty_struct *tty)
255 if (!tty || !tty->driver)
257 return tty->driver->name;
260 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
263 #ifdef TTY_PARANOIA_CHECK
265 pr_warn("(%d:%d): %s: NULL tty\n",
266 imajor(inode), iminor(inode), routine);
269 if (tty->magic != TTY_MAGIC) {
270 pr_warn("(%d:%d): %s: bad magic number\n",
271 imajor(inode), iminor(inode), routine);
278 /* Caller must hold tty_lock */
279 static int check_tty_count(struct tty_struct *tty, const char *routine)
281 #ifdef CHECK_TTY_COUNT
283 int count = 0, kopen_count = 0;
285 spin_lock(&tty->files_lock);
286 list_for_each(p, &tty->tty_files) {
289 spin_unlock(&tty->files_lock);
290 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
291 tty->driver->subtype == PTY_TYPE_SLAVE &&
292 tty->link && tty->link->count)
294 if (tty_port_kopened(tty->port))
296 if (tty->count != (count + kopen_count)) {
297 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
298 routine, tty->count, count, kopen_count);
299 return (count + kopen_count);
306 * get_tty_driver - find device of a tty
307 * @device: device identifier
308 * @index: returns the index of the tty
310 * This routine returns a tty driver structure, given a device number
311 * and also passes back the index number.
313 * Locking: caller must hold tty_mutex
316 static struct tty_driver *get_tty_driver(dev_t device, int *index)
318 struct tty_driver *p;
320 list_for_each_entry(p, &tty_drivers, tty_drivers) {
321 dev_t base = MKDEV(p->major, p->minor_start);
322 if (device < base || device >= base + p->num)
324 *index = device - base;
325 return tty_driver_kref_get(p);
331 * tty_dev_name_to_number - return dev_t for device name
332 * @name: user space name of device under /dev
333 * @number: pointer to dev_t that this function will populate
335 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
336 * like (4, 64) or (188, 1). If no corresponding driver is registered then
337 * the function returns -ENODEV.
339 * Locking: this acquires tty_mutex to protect the tty_drivers list from
340 * being modified while we are traversing it, and makes sure to
341 * release it before exiting.
343 int tty_dev_name_to_number(const char *name, dev_t *number)
345 struct tty_driver *p;
347 int index, prefix_length = 0;
350 for (str = name; *str && !isdigit(*str); str++)
356 ret = kstrtoint(str, 10, &index);
360 prefix_length = str - name;
361 mutex_lock(&tty_mutex);
363 list_for_each_entry(p, &tty_drivers, tty_drivers)
364 if (prefix_length == strlen(p->name) && strncmp(name,
365 p->name, prefix_length) == 0) {
366 if (index < p->num) {
367 *number = MKDEV(p->major, p->minor_start + index);
372 /* if here then driver wasn't found */
375 mutex_unlock(&tty_mutex);
378 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
380 #ifdef CONFIG_CONSOLE_POLL
383 * tty_find_polling_driver - find device of a polled tty
384 * @name: name string to match
385 * @line: pointer to resulting tty line nr
387 * This routine returns a tty driver structure, given a name
388 * and the condition that the tty driver is capable of polled
391 struct tty_driver *tty_find_polling_driver(char *name, int *line)
393 struct tty_driver *p, *res = NULL;
398 for (str = name; *str; str++)
399 if ((*str >= '0' && *str <= '9') || *str == ',')
405 tty_line = simple_strtoul(str, &str, 10);
407 mutex_lock(&tty_mutex);
408 /* Search through the tty devices to look for a match */
409 list_for_each_entry(p, &tty_drivers, tty_drivers) {
410 if (!len || strncmp(name, p->name, len) != 0)
418 if (tty_line >= 0 && tty_line < p->num && p->ops &&
419 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
420 res = tty_driver_kref_get(p);
425 mutex_unlock(&tty_mutex);
429 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
432 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
437 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
442 /* No kernel lock held - none needed ;) */
443 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
445 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
448 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
451 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
454 static long hung_up_tty_compat_ioctl(struct file *file,
455 unsigned int cmd, unsigned long arg)
457 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
460 static int hung_up_tty_fasync(int fd, struct file *file, int on)
465 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
467 struct tty_struct *tty = file_tty(file);
469 if (tty && tty->ops && tty->ops->show_fdinfo)
470 tty->ops->show_fdinfo(tty, m);
473 static const struct file_operations tty_fops = {
475 .read_iter = tty_read,
476 .write_iter = tty_write,
477 .splice_read = generic_file_splice_read,
478 .splice_write = iter_file_splice_write,
480 .unlocked_ioctl = tty_ioctl,
481 .compat_ioctl = tty_compat_ioctl,
483 .release = tty_release,
484 .fasync = tty_fasync,
485 .show_fdinfo = tty_show_fdinfo,
488 static const struct file_operations console_fops = {
490 .read_iter = tty_read,
491 .write_iter = redirected_tty_write,
492 .splice_read = generic_file_splice_read,
493 .splice_write = iter_file_splice_write,
495 .unlocked_ioctl = tty_ioctl,
496 .compat_ioctl = tty_compat_ioctl,
498 .release = tty_release,
499 .fasync = tty_fasync,
502 static const struct file_operations hung_up_tty_fops = {
504 .read_iter = hung_up_tty_read,
505 .write_iter = hung_up_tty_write,
506 .poll = hung_up_tty_poll,
507 .unlocked_ioctl = hung_up_tty_ioctl,
508 .compat_ioctl = hung_up_tty_compat_ioctl,
509 .release = tty_release,
510 .fasync = hung_up_tty_fasync,
513 static DEFINE_SPINLOCK(redirect_lock);
514 static struct file *redirect;
517 * tty_wakeup - request more data
520 * Internal and external helper for wakeups of tty. This function
521 * informs the line discipline if present that the driver is ready
522 * to receive more output data.
525 void tty_wakeup(struct tty_struct *tty)
527 struct tty_ldisc *ld;
529 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
530 ld = tty_ldisc_ref(tty);
532 if (ld->ops->write_wakeup)
533 ld->ops->write_wakeup(tty);
537 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
540 EXPORT_SYMBOL_GPL(tty_wakeup);
543 * tty_release_redirect - Release a redirect on a pty if present
546 * This is available to the pty code so if the master closes, if the
547 * slave is a redirect it can release the redirect. It returns the
548 * filp for the redirect, which must be fput when the operations on
549 * the tty are completed.
551 struct file *tty_release_redirect(struct tty_struct *tty)
553 struct file *f = NULL;
555 spin_lock(&redirect_lock);
556 if (redirect && file_tty(redirect) == tty) {
560 spin_unlock(&redirect_lock);
566 * __tty_hangup - actual handler for hangup events
568 * @exit_session: if non-zero, signal all foreground group processes
570 * This can be called by a "kworker" kernel thread. That is process
571 * synchronous but doesn't hold any locks, so we need to make sure we
572 * have the appropriate locks for what we're doing.
574 * The hangup event clears any pending redirections onto the hung up
575 * device. It ensures future writes will error and it does the needed
576 * line discipline hangup and signal delivery. The tty object itself
581 * redirect lock for undoing redirection
582 * file list lock for manipulating list of ttys
583 * tty_ldiscs_lock from called functions
584 * termios_rwsem resetting termios data
585 * tasklist_lock to walk task list for hangup event
586 * ->siglock to protect ->signal/->sighand
588 static void __tty_hangup(struct tty_struct *tty, int exit_session)
590 struct file *cons_filp = NULL;
591 struct file *filp, *f;
592 struct tty_file_private *priv;
593 int closecount = 0, n;
599 f = tty_release_redirect(tty);
603 if (test_bit(TTY_HUPPED, &tty->flags)) {
609 * Some console devices aren't actually hung up for technical and
610 * historical reasons, which can lead to indefinite interruptible
611 * sleep in n_tty_read(). The following explicitly tells
612 * n_tty_read() to abort readers.
614 set_bit(TTY_HUPPING, &tty->flags);
616 /* inuse_filps is protected by the single tty lock,
617 this really needs to change if we want to flush the
618 workqueue with the lock held */
619 check_tty_count(tty, "tty_hangup");
621 spin_lock(&tty->files_lock);
622 /* This breaks for file handles being sent over AF_UNIX sockets ? */
623 list_for_each_entry(priv, &tty->tty_files, list) {
625 if (filp->f_op->write_iter == redirected_tty_write)
627 if (filp->f_op->write_iter != tty_write)
630 __tty_fasync(-1, filp, 0); /* can't block */
631 filp->f_op = &hung_up_tty_fops;
633 spin_unlock(&tty->files_lock);
635 refs = tty_signal_session_leader(tty, exit_session);
636 /* Account for the p->signal references we killed */
640 tty_ldisc_hangup(tty, cons_filp != NULL);
642 spin_lock_irq(&tty->ctrl_lock);
643 clear_bit(TTY_THROTTLED, &tty->flags);
644 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
645 put_pid(tty->session);
649 tty->ctrl_status = 0;
650 spin_unlock_irq(&tty->ctrl_lock);
653 * If one of the devices matches a console pointer, we
654 * cannot just call hangup() because that will cause
655 * tty->count and state->count to go out of sync.
656 * So we just call close() the right number of times.
660 for (n = 0; n < closecount; n++)
661 tty->ops->close(tty, cons_filp);
662 } else if (tty->ops->hangup)
663 tty->ops->hangup(tty);
665 * We don't want to have driver/ldisc interactions beyond the ones
666 * we did here. The driver layer expects no calls after ->hangup()
667 * from the ldisc side, which is now guaranteed.
669 set_bit(TTY_HUPPED, &tty->flags);
670 clear_bit(TTY_HUPPING, &tty->flags);
677 static void do_tty_hangup(struct work_struct *work)
679 struct tty_struct *tty =
680 container_of(work, struct tty_struct, hangup_work);
682 __tty_hangup(tty, 0);
686 * tty_hangup - trigger a hangup event
687 * @tty: tty to hangup
689 * A carrier loss (virtual or otherwise) has occurred on this like
690 * schedule a hangup sequence to run after this event.
693 void tty_hangup(struct tty_struct *tty)
695 tty_debug_hangup(tty, "hangup\n");
696 schedule_work(&tty->hangup_work);
699 EXPORT_SYMBOL(tty_hangup);
702 * tty_vhangup - process vhangup
703 * @tty: tty to hangup
705 * The user has asked via system call for the terminal to be hung up.
706 * We do this synchronously so that when the syscall returns the process
707 * is complete. That guarantee is necessary for security reasons.
710 void tty_vhangup(struct tty_struct *tty)
712 tty_debug_hangup(tty, "vhangup\n");
713 __tty_hangup(tty, 0);
716 EXPORT_SYMBOL(tty_vhangup);
720 * tty_vhangup_self - process vhangup for own ctty
722 * Perform a vhangup on the current controlling tty
725 void tty_vhangup_self(void)
727 struct tty_struct *tty;
729 tty = get_current_tty();
737 * tty_vhangup_session - hangup session leader exit
738 * @tty: tty to hangup
740 * The session leader is exiting and hanging up its controlling terminal.
741 * Every process in the foreground process group is signalled SIGHUP.
743 * We do this synchronously so that when the syscall returns the process
744 * is complete. That guarantee is necessary for security reasons.
747 void tty_vhangup_session(struct tty_struct *tty)
749 tty_debug_hangup(tty, "session hangup\n");
750 __tty_hangup(tty, 1);
754 * tty_hung_up_p - was tty hung up
755 * @filp: file pointer of tty
757 * Return true if the tty has been subject to a vhangup or a carrier
761 int tty_hung_up_p(struct file *filp)
763 return (filp && filp->f_op == &hung_up_tty_fops);
766 EXPORT_SYMBOL(tty_hung_up_p);
769 * stop_tty - propagate flow control
772 * Perform flow control to the driver. May be called
773 * on an already stopped device and will not re-call the driver
776 * This functionality is used by both the line disciplines for
777 * halting incoming flow and by the driver. It may therefore be
778 * called from any context, may be under the tty atomic_write_lock
785 void __stop_tty(struct tty_struct *tty)
794 void stop_tty(struct tty_struct *tty)
798 spin_lock_irqsave(&tty->flow_lock, flags);
800 spin_unlock_irqrestore(&tty->flow_lock, flags);
802 EXPORT_SYMBOL(stop_tty);
805 * start_tty - propagate flow control
808 * Start a tty that has been stopped if at all possible. If this
809 * tty was previous stopped and is now being started, the driver
810 * start method is invoked and the line discipline woken.
816 void __start_tty(struct tty_struct *tty)
818 if (!tty->stopped || tty->flow_stopped)
822 tty->ops->start(tty);
826 void start_tty(struct tty_struct *tty)
830 spin_lock_irqsave(&tty->flow_lock, flags);
832 spin_unlock_irqrestore(&tty->flow_lock, flags);
834 EXPORT_SYMBOL(start_tty);
836 static void tty_update_time(struct timespec64 *time)
838 time64_t sec = ktime_get_real_seconds();
841 * We only care if the two values differ in anything other than the
842 * lower three bits (i.e every 8 seconds). If so, then we can update
843 * the time of the tty device, otherwise it could be construded as a
844 * security leak to let userspace know the exact timing of the tty.
846 if ((sec ^ time->tv_sec) & ~7)
851 * Iterate on the ldisc ->read() function until we've gotten all
852 * the data the ldisc has for us.
854 * The "cookie" is something that the ldisc read function can fill
855 * in to let us know that there is more data to be had.
857 * We promise to continue to call the ldisc until it stops returning
858 * data or clears the cookie. The cookie may be something that the
859 * ldisc maintains state for and needs to free.
861 static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
862 struct file *file, struct iov_iter *to)
866 unsigned long offset = 0;
868 size_t count = iov_iter_count(to);
873 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
874 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
879 /* Did we have an earlier error (ie -EFAULT)? */
885 * -EOVERFLOW means we didn't have enough space
886 * for a whole packet, and we shouldn't return
889 if (retval == -EOVERFLOW)
894 copied = copy_to_iter(kernel_buf, size, to);
899 * If the user copy failed, we still need to do another ->read()
900 * call if we had a cookie to let the ldisc clear up.
902 * But make sure size is zeroed.
904 if (unlikely(copied != size)) {
910 /* We always clear tty buffer in case they contained passwords */
911 memzero_explicit(kernel_buf, sizeof(kernel_buf));
912 return offset ? offset : retval;
917 * tty_read - read method for tty device files
918 * @file: pointer to tty file
920 * @count: size of user buffer
923 * Perform the read system call function on this terminal device. Checks
924 * for hung up devices before calling the line discipline method.
927 * Locks the line discipline internally while needed. Multiple
928 * read calls may be outstanding in parallel.
931 static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
934 struct file *file = iocb->ki_filp;
935 struct inode *inode = file_inode(file);
936 struct tty_struct *tty = file_tty(file);
937 struct tty_ldisc *ld;
939 if (tty_paranoia_check(tty, inode, "tty_read"))
941 if (!tty || tty_io_error(tty))
944 /* We want to wait for the line discipline to sort out in this
946 ld = tty_ldisc_ref_wait(tty);
948 return hung_up_tty_read(iocb, to);
951 i = iterate_tty_read(ld, tty, file, to);
955 tty_update_time(&inode->i_atime);
960 static void tty_write_unlock(struct tty_struct *tty)
962 mutex_unlock(&tty->atomic_write_lock);
963 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
966 static int tty_write_lock(struct tty_struct *tty, int ndelay)
968 if (!mutex_trylock(&tty->atomic_write_lock)) {
971 if (mutex_lock_interruptible(&tty->atomic_write_lock))
978 * Split writes up in sane blocksizes to avoid
979 * denial-of-service type attacks
981 static inline ssize_t do_tty_write(
982 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
983 struct tty_struct *tty,
985 struct iov_iter *from)
987 size_t count = iov_iter_count(from);
988 ssize_t ret, written = 0;
991 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
996 * We chunk up writes into a temporary buffer. This
997 * simplifies low-level drivers immensely, since they
998 * don't have locking issues and user mode accesses.
1000 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1003 * The default chunk-size is 2kB, because the NTTY
1004 * layer has problems with bigger chunks. It will
1005 * claim to be able to handle more characters than
1008 * FIXME: This can probably go away now except that 64K chunks
1009 * are too likely to fail unless switched to vmalloc...
1012 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1017 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1018 if (tty->write_cnt < chunk) {
1019 unsigned char *buf_chunk;
1024 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1029 kfree(tty->write_buf);
1030 tty->write_cnt = chunk;
1031 tty->write_buf = buf_chunk;
1034 /* Do the write .. */
1036 size_t size = count;
1041 if (copy_from_iter(tty->write_buf, size, from) != size)
1044 ret = write(tty, file, tty->write_buf, size);
1052 /* FIXME! Have Al check this! */
1054 iov_iter_revert(from, size-ret);
1060 if (signal_pending(current))
1065 tty_update_time(&file_inode(file)->i_mtime);
1069 tty_write_unlock(tty);
1074 * tty_write_message - write a message to a certain tty, not just the console.
1075 * @tty: the destination tty_struct
1076 * @msg: the message to write
1078 * This is used for messages that need to be redirected to a specific tty.
1079 * We don't put it into the syslog queue right now maybe in the future if
1082 * We must still hold the BTM and test the CLOSING flag for the moment.
1085 void tty_write_message(struct tty_struct *tty, char *msg)
1088 mutex_lock(&tty->atomic_write_lock);
1090 if (tty->ops->write && tty->count > 0)
1091 tty->ops->write(tty, msg, strlen(msg));
1093 tty_write_unlock(tty);
1100 * tty_write - write method for tty device file
1101 * @file: tty file pointer
1102 * @buf: user data to write
1103 * @count: bytes to write
1106 * Write data to a tty device via the line discipline.
1109 * Locks the line discipline as required
1110 * Writes to the tty driver are serialized by the atomic_write_lock
1111 * and are then processed in chunks to the device. The line discipline
1112 * write method will not be invoked in parallel for each device.
1115 static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
1117 struct tty_struct *tty = file_tty(file);
1118 struct tty_ldisc *ld;
1121 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1123 if (!tty || !tty->ops->write || tty_io_error(tty))
1125 /* Short term debug to catch buggy drivers */
1126 if (tty->ops->write_room == NULL)
1127 tty_err(tty, "missing write_room method\n");
1128 ld = tty_ldisc_ref_wait(tty);
1130 return hung_up_tty_write(iocb, from);
1131 if (!ld->ops->write)
1134 ret = do_tty_write(ld->ops->write, tty, file, from);
1135 tty_ldisc_deref(ld);
1139 static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1141 return file_tty_write(iocb->ki_filp, iocb, from);
1144 ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1146 struct file *p = NULL;
1148 spin_lock(&redirect_lock);
1150 p = get_file(redirect);
1151 spin_unlock(&redirect_lock);
1154 * We know the redirected tty is just another tty, we can can
1155 * call file_tty_write() directly with that file pointer.
1159 res = file_tty_write(p, iocb, iter);
1163 return tty_write(iocb, iter);
1167 * tty_send_xchar - send priority character
1169 * Send a high priority character to the tty even if stopped
1171 * Locking: none for xchar method, write ordering for write method.
1174 int tty_send_xchar(struct tty_struct *tty, char ch)
1176 int was_stopped = tty->stopped;
1178 if (tty->ops->send_xchar) {
1179 down_read(&tty->termios_rwsem);
1180 tty->ops->send_xchar(tty, ch);
1181 up_read(&tty->termios_rwsem);
1185 if (tty_write_lock(tty, 0) < 0)
1186 return -ERESTARTSYS;
1188 down_read(&tty->termios_rwsem);
1191 tty->ops->write(tty, &ch, 1);
1194 up_read(&tty->termios_rwsem);
1195 tty_write_unlock(tty);
1199 static char ptychar[] = "pqrstuvwxyzabcde";
1202 * pty_line_name - generate name for a pty
1203 * @driver: the tty driver in use
1204 * @index: the minor number
1205 * @p: output buffer of at least 6 bytes
1207 * Generate a name from a driver reference and write it to the output
1212 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1214 int i = index + driver->name_base;
1215 /* ->name is initialized to "ttyp", but "tty" is expected */
1216 sprintf(p, "%s%c%x",
1217 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1218 ptychar[i >> 4 & 0xf], i & 0xf);
1222 * tty_line_name - generate name for a tty
1223 * @driver: the tty driver in use
1224 * @index: the minor number
1225 * @p: output buffer of at least 7 bytes
1227 * Generate a name from a driver reference and write it to the output
1232 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1234 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1235 return sprintf(p, "%s", driver->name);
1237 return sprintf(p, "%s%d", driver->name,
1238 index + driver->name_base);
1242 * tty_driver_lookup_tty() - find an existing tty, if any
1243 * @driver: the driver for the tty
1244 * @file: file object
1245 * @idx: the minor number
1247 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1248 * driver lookup() method returns an error.
1250 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1252 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1253 struct file *file, int idx)
1255 struct tty_struct *tty;
1257 if (driver->ops->lookup)
1259 tty = ERR_PTR(-EIO);
1261 tty = driver->ops->lookup(driver, file, idx);
1263 tty = driver->ttys[idx];
1271 * tty_init_termios - helper for termios setup
1272 * @tty: the tty to set up
1274 * Initialise the termios structure for this tty. This runs under
1275 * the tty_mutex currently so we can be relaxed about ordering.
1278 void tty_init_termios(struct tty_struct *tty)
1280 struct ktermios *tp;
1281 int idx = tty->index;
1283 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1284 tty->termios = tty->driver->init_termios;
1286 /* Check for lazy saved data */
1287 tp = tty->driver->termios[idx];
1290 tty->termios.c_line = tty->driver->init_termios.c_line;
1292 tty->termios = tty->driver->init_termios;
1294 /* Compatibility until drivers always set this */
1295 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1296 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1298 EXPORT_SYMBOL_GPL(tty_init_termios);
1300 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1302 tty_init_termios(tty);
1303 tty_driver_kref_get(driver);
1305 driver->ttys[tty->index] = tty;
1308 EXPORT_SYMBOL_GPL(tty_standard_install);
1311 * tty_driver_install_tty() - install a tty entry in the driver
1312 * @driver: the driver for the tty
1315 * Install a tty object into the driver tables. The tty->index field
1316 * will be set by the time this is called. This method is responsible
1317 * for ensuring any need additional structures are allocated and
1320 * Locking: tty_mutex for now
1322 static int tty_driver_install_tty(struct tty_driver *driver,
1323 struct tty_struct *tty)
1325 return driver->ops->install ? driver->ops->install(driver, tty) :
1326 tty_standard_install(driver, tty);
1330 * tty_driver_remove_tty() - remove a tty from the driver tables
1331 * @driver: the driver for the tty
1332 * @tty: tty to remove
1334 * Remvoe a tty object from the driver tables. The tty->index field
1335 * will be set by the time this is called.
1337 * Locking: tty_mutex for now
1339 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1341 if (driver->ops->remove)
1342 driver->ops->remove(driver, tty);
1344 driver->ttys[tty->index] = NULL;
1348 * tty_reopen() - fast re-open of an open tty
1349 * @tty: the tty to open
1351 * Return 0 on success, -errno on error.
1352 * Re-opens on master ptys are not allowed and return -EIO.
1354 * Locking: Caller must hold tty_lock
1356 static int tty_reopen(struct tty_struct *tty)
1358 struct tty_driver *driver = tty->driver;
1359 struct tty_ldisc *ld;
1362 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1363 driver->subtype == PTY_TYPE_MASTER)
1369 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1372 ld = tty_ldisc_ref_wait(tty);
1374 tty_ldisc_deref(ld);
1376 retval = tty_ldisc_lock(tty, 5 * HZ);
1381 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1382 tty_ldisc_unlock(tty);
1392 * tty_init_dev - initialise a tty device
1393 * @driver: tty driver we are opening a device on
1394 * @idx: device index
1396 * Prepare a tty device. This may not be a "new" clean device but
1397 * could also be an active device. The pty drivers require special
1398 * handling because of this.
1401 * The function is called under the tty_mutex, which
1402 * protects us from the tty struct or driver itself going away.
1404 * On exit the tty device has the line discipline attached and
1405 * a reference count of 1. If a pair was created for pty/tty use
1406 * and the other was a pty master then it too has a reference count of 1.
1408 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1409 * failed open. The new code protects the open with a mutex, so it's
1410 * really quite straightforward. The mutex locking can probably be
1411 * relaxed for the (most common) case of reopening a tty.
1413 * Return: returned tty structure
1416 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1418 struct tty_struct *tty;
1422 * First time open is complex, especially for PTY devices.
1423 * This code guarantees that either everything succeeds and the
1424 * TTY is ready for operation, or else the table slots are vacated
1425 * and the allocated memory released. (Except that the termios
1429 if (!try_module_get(driver->owner))
1430 return ERR_PTR(-ENODEV);
1432 tty = alloc_tty_struct(driver, idx);
1435 goto err_module_put;
1439 retval = tty_driver_install_tty(driver, tty);
1444 tty->port = driver->ports[idx];
1446 if (WARN_RATELIMIT(!tty->port,
1447 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1448 __func__, tty->driver->name)) {
1450 goto err_release_lock;
1453 retval = tty_ldisc_lock(tty, 5 * HZ);
1455 goto err_release_lock;
1456 tty->port->itty = tty;
1459 * Structures all installed ... call the ldisc open routines.
1460 * If we fail here just call release_tty to clean up. No need
1461 * to decrement the use counts, as release_tty doesn't care.
1463 retval = tty_ldisc_setup(tty, tty->link);
1465 goto err_release_tty;
1466 tty_ldisc_unlock(tty);
1467 /* Return the tty locked so that it cannot vanish under the caller */
1472 free_tty_struct(tty);
1474 module_put(driver->owner);
1475 return ERR_PTR(retval);
1477 /* call the tty release_tty routine to clean out this slot */
1479 tty_ldisc_unlock(tty);
1480 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1484 release_tty(tty, idx);
1485 return ERR_PTR(retval);
1489 * tty_save_termios() - save tty termios data in driver table
1490 * @tty: tty whose termios data to save
1492 * Locking: Caller guarantees serialisation with tty_init_termios().
1494 void tty_save_termios(struct tty_struct *tty)
1496 struct ktermios *tp;
1497 int idx = tty->index;
1499 /* If the port is going to reset then it has no termios to save */
1500 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1503 /* Stash the termios data */
1504 tp = tty->driver->termios[idx];
1506 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1509 tty->driver->termios[idx] = tp;
1513 EXPORT_SYMBOL_GPL(tty_save_termios);
1516 * tty_flush_works - flush all works of a tty/pty pair
1517 * @tty: tty device to flush works for (or either end of a pty pair)
1519 * Sync flush all works belonging to @tty (and the 'other' tty).
1521 static void tty_flush_works(struct tty_struct *tty)
1523 flush_work(&tty->SAK_work);
1524 flush_work(&tty->hangup_work);
1526 flush_work(&tty->link->SAK_work);
1527 flush_work(&tty->link->hangup_work);
1532 * release_one_tty - release tty structure memory
1533 * @work: work of tty we are obliterating
1535 * Releases memory associated with a tty structure, and clears out the
1536 * driver table slots. This function is called when a device is no longer
1537 * in use. It also gets called when setup of a device fails.
1540 * takes the file list lock internally when working on the list
1541 * of ttys that the driver keeps.
1543 * This method gets called from a work queue so that the driver private
1544 * cleanup ops can sleep (needed for USB at least)
1546 static void release_one_tty(struct work_struct *work)
1548 struct tty_struct *tty =
1549 container_of(work, struct tty_struct, hangup_work);
1550 struct tty_driver *driver = tty->driver;
1551 struct module *owner = driver->owner;
1553 if (tty->ops->cleanup)
1554 tty->ops->cleanup(tty);
1557 tty_driver_kref_put(driver);
1560 spin_lock(&tty->files_lock);
1561 list_del_init(&tty->tty_files);
1562 spin_unlock(&tty->files_lock);
1565 put_pid(tty->session);
1566 free_tty_struct(tty);
1569 static void queue_release_one_tty(struct kref *kref)
1571 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1573 /* The hangup queue is now free so we can reuse it rather than
1574 waste a chunk of memory for each port */
1575 INIT_WORK(&tty->hangup_work, release_one_tty);
1576 schedule_work(&tty->hangup_work);
1580 * tty_kref_put - release a tty kref
1583 * Release a reference to a tty device and if need be let the kref
1584 * layer destruct the object for us
1587 void tty_kref_put(struct tty_struct *tty)
1590 kref_put(&tty->kref, queue_release_one_tty);
1592 EXPORT_SYMBOL(tty_kref_put);
1595 * release_tty - release tty structure memory
1596 * @tty: tty device release
1597 * @idx: index of the tty device release
1599 * Release both @tty and a possible linked partner (think pty pair),
1600 * and decrement the refcount of the backing module.
1604 * takes the file list lock internally when working on the list
1605 * of ttys that the driver keeps.
1608 static void release_tty(struct tty_struct *tty, int idx)
1610 /* This should always be true but check for the moment */
1611 WARN_ON(tty->index != idx);
1612 WARN_ON(!mutex_is_locked(&tty_mutex));
1613 if (tty->ops->shutdown)
1614 tty->ops->shutdown(tty);
1615 tty_save_termios(tty);
1616 tty_driver_remove_tty(tty->driver, tty);
1618 tty->port->itty = NULL;
1620 tty->link->port->itty = NULL;
1622 tty_buffer_cancel_work(tty->port);
1624 tty_buffer_cancel_work(tty->link->port);
1626 tty_kref_put(tty->link);
1631 * tty_release_checks - check a tty before real release
1632 * @tty: tty to check
1633 * @idx: index of the tty
1635 * Performs some paranoid checking before true release of the @tty.
1636 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1638 static int tty_release_checks(struct tty_struct *tty, int idx)
1640 #ifdef TTY_PARANOIA_CHECK
1641 if (idx < 0 || idx >= tty->driver->num) {
1642 tty_debug(tty, "bad idx %d\n", idx);
1646 /* not much to check for devpts */
1647 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1650 if (tty != tty->driver->ttys[idx]) {
1651 tty_debug(tty, "bad driver table[%d] = %p\n",
1652 idx, tty->driver->ttys[idx]);
1655 if (tty->driver->other) {
1656 struct tty_struct *o_tty = tty->link;
1658 if (o_tty != tty->driver->other->ttys[idx]) {
1659 tty_debug(tty, "bad other table[%d] = %p\n",
1660 idx, tty->driver->other->ttys[idx]);
1663 if (o_tty->link != tty) {
1664 tty_debug(tty, "bad link = %p\n", o_tty->link);
1673 * tty_kclose - closes tty opened by tty_kopen
1676 * Performs the final steps to release and free a tty device. It is the
1677 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1678 * flag on tty->port.
1680 void tty_kclose(struct tty_struct *tty)
1683 * Ask the line discipline code to release its structures
1685 tty_ldisc_release(tty);
1687 /* Wait for pending work before tty destruction commmences */
1688 tty_flush_works(tty);
1690 tty_debug_hangup(tty, "freeing structure\n");
1692 * The release_tty function takes care of the details of clearing
1693 * the slots and preserving the termios structure.
1695 mutex_lock(&tty_mutex);
1696 tty_port_set_kopened(tty->port, 0);
1697 release_tty(tty, tty->index);
1698 mutex_unlock(&tty_mutex);
1700 EXPORT_SYMBOL_GPL(tty_kclose);
1703 * tty_release_struct - release a tty struct
1705 * @idx: index of the tty
1707 * Performs the final steps to release and free a tty device. It is
1708 * roughly the reverse of tty_init_dev.
1710 void tty_release_struct(struct tty_struct *tty, int idx)
1713 * Ask the line discipline code to release its structures
1715 tty_ldisc_release(tty);
1717 /* Wait for pending work before tty destruction commmences */
1718 tty_flush_works(tty);
1720 tty_debug_hangup(tty, "freeing structure\n");
1722 * The release_tty function takes care of the details of clearing
1723 * the slots and preserving the termios structure.
1725 mutex_lock(&tty_mutex);
1726 release_tty(tty, idx);
1727 mutex_unlock(&tty_mutex);
1729 EXPORT_SYMBOL_GPL(tty_release_struct);
1732 * tty_release - vfs callback for close
1733 * @inode: inode of tty
1734 * @filp: file pointer for handle to tty
1736 * Called the last time each file handle is closed that references
1737 * this tty. There may however be several such references.
1740 * Takes bkl. See tty_release_dev
1742 * Even releasing the tty structures is a tricky business.. We have
1743 * to be very careful that the structures are all released at the
1744 * same time, as interrupts might otherwise get the wrong pointers.
1746 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1747 * lead to double frees or releasing memory still in use.
1750 int tty_release(struct inode *inode, struct file *filp)
1752 struct tty_struct *tty = file_tty(filp);
1753 struct tty_struct *o_tty = NULL;
1754 int do_sleep, final;
1759 if (tty_paranoia_check(tty, inode, __func__))
1763 check_tty_count(tty, __func__);
1765 __tty_fasync(-1, filp, 0);
1768 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1769 tty->driver->subtype == PTY_TYPE_MASTER)
1772 if (tty_release_checks(tty, idx)) {
1777 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1779 if (tty->ops->close)
1780 tty->ops->close(tty, filp);
1782 /* If tty is pty master, lock the slave pty (stable lock order) */
1783 tty_lock_slave(o_tty);
1786 * Sanity check: if tty->count is going to zero, there shouldn't be
1787 * any waiters on tty->read_wait or tty->write_wait. We test the
1788 * wait queues and kick everyone out _before_ actually starting to
1789 * close. This ensures that we won't block while releasing the tty
1792 * The test for the o_tty closing is necessary, since the master and
1793 * slave sides may close in any order. If the slave side closes out
1794 * first, its count will be one, since the master side holds an open.
1795 * Thus this test wouldn't be triggered at the time the slave closed,
1801 if (tty->count <= 1) {
1802 if (waitqueue_active(&tty->read_wait)) {
1803 wake_up_poll(&tty->read_wait, EPOLLIN);
1806 if (waitqueue_active(&tty->write_wait)) {
1807 wake_up_poll(&tty->write_wait, EPOLLOUT);
1811 if (o_tty && o_tty->count <= 1) {
1812 if (waitqueue_active(&o_tty->read_wait)) {
1813 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1816 if (waitqueue_active(&o_tty->write_wait)) {
1817 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1826 tty_warn(tty, "read/write wait queue active!\n");
1828 schedule_timeout_killable(timeout);
1829 if (timeout < 120 * HZ)
1830 timeout = 2 * timeout + 1;
1832 timeout = MAX_SCHEDULE_TIMEOUT;
1836 if (--o_tty->count < 0) {
1837 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1841 if (--tty->count < 0) {
1842 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1847 * We've decremented tty->count, so we need to remove this file
1848 * descriptor off the tty->tty_files list; this serves two
1850 * - check_tty_count sees the correct number of file descriptors
1851 * associated with this tty.
1852 * - do_tty_hangup no longer sees this file descriptor as
1853 * something that needs to be handled for hangups.
1858 * Perform some housekeeping before deciding whether to return.
1860 * If _either_ side is closing, make sure there aren't any
1861 * processes that still think tty or o_tty is their controlling
1865 read_lock(&tasklist_lock);
1866 session_clear_tty(tty->session);
1868 session_clear_tty(o_tty->session);
1869 read_unlock(&tasklist_lock);
1872 /* check whether both sides are closing ... */
1873 final = !tty->count && !(o_tty && o_tty->count);
1875 tty_unlock_slave(o_tty);
1878 /* At this point, the tty->count == 0 should ensure a dead tty
1879 cannot be re-opened by a racing opener */
1884 tty_debug_hangup(tty, "final close\n");
1886 tty_release_struct(tty, idx);
1891 * tty_open_current_tty - get locked tty of current task
1892 * @device: device number
1893 * @filp: file pointer to tty
1894 * @return: locked tty of the current task iff @device is /dev/tty
1896 * Performs a re-open of the current task's controlling tty.
1898 * We cannot return driver and index like for the other nodes because
1899 * devpts will not work then. It expects inodes to be from devpts FS.
1901 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1903 struct tty_struct *tty;
1906 if (device != MKDEV(TTYAUX_MAJOR, 0))
1909 tty = get_current_tty();
1911 return ERR_PTR(-ENXIO);
1913 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1916 tty_kref_put(tty); /* safe to drop the kref now */
1918 retval = tty_reopen(tty);
1921 tty = ERR_PTR(retval);
1927 * tty_lookup_driver - lookup a tty driver for a given device file
1928 * @device: device number
1929 * @filp: file pointer to tty
1930 * @index: index for the device in the @return driver
1931 * @return: driver for this inode (with increased refcount)
1933 * If @return is not erroneous, the caller is responsible to decrement the
1934 * refcount by tty_driver_kref_put.
1936 * Locking: tty_mutex protects get_tty_driver
1938 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1941 struct tty_driver *driver = NULL;
1945 case MKDEV(TTY_MAJOR, 0): {
1946 extern struct tty_driver *console_driver;
1947 driver = tty_driver_kref_get(console_driver);
1948 *index = fg_console;
1952 case MKDEV(TTYAUX_MAJOR, 1): {
1953 struct tty_driver *console_driver = console_device(index);
1954 if (console_driver) {
1955 driver = tty_driver_kref_get(console_driver);
1956 if (driver && filp) {
1957 /* Don't let /dev/console block */
1958 filp->f_flags |= O_NONBLOCK;
1963 tty_driver_kref_put(driver);
1964 return ERR_PTR(-ENODEV);
1967 driver = get_tty_driver(device, index);
1969 return ERR_PTR(-ENODEV);
1975 static struct tty_struct *tty_kopen(dev_t device, int shared)
1977 struct tty_struct *tty;
1978 struct tty_driver *driver;
1981 mutex_lock(&tty_mutex);
1982 driver = tty_lookup_driver(device, NULL, &index);
1983 if (IS_ERR(driver)) {
1984 mutex_unlock(&tty_mutex);
1985 return ERR_CAST(driver);
1988 /* check whether we're reopening an existing tty */
1989 tty = tty_driver_lookup_tty(driver, NULL, index);
1990 if (IS_ERR(tty) || shared)
1994 /* drop kref from tty_driver_lookup_tty() */
1996 tty = ERR_PTR(-EBUSY);
1997 } else { /* tty_init_dev returns tty with the tty_lock held */
1998 tty = tty_init_dev(driver, index);
2001 tty_port_set_kopened(tty->port, 1);
2004 mutex_unlock(&tty_mutex);
2005 tty_driver_kref_put(driver);
2010 * tty_kopen_exclusive - open a tty device for kernel
2011 * @device: dev_t of device to open
2013 * Opens tty exclusively for kernel. Performs the driver lookup,
2014 * makes sure it's not already opened and performs the first-time
2015 * tty initialization.
2017 * Returns the locked initialized &tty_struct
2019 * Claims the global tty_mutex to serialize:
2020 * - concurrent first-time tty initialization
2021 * - concurrent tty driver removal w/ lookup
2022 * - concurrent tty removal from driver table
2024 struct tty_struct *tty_kopen_exclusive(dev_t device)
2026 return tty_kopen(device, 0);
2028 EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2031 * tty_kopen_shared - open a tty device for shared in-kernel use
2032 * @device: dev_t of device to open
2034 * Opens an already existing tty for in-kernel use. Compared to
2035 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2037 * Locking is identical to tty_kopen() above.
2039 struct tty_struct *tty_kopen_shared(dev_t device)
2041 return tty_kopen(device, 1);
2043 EXPORT_SYMBOL_GPL(tty_kopen_shared);
2046 * tty_open_by_driver - open a tty device
2047 * @device: dev_t of device to open
2048 * @filp: file pointer to tty
2050 * Performs the driver lookup, checks for a reopen, or otherwise
2051 * performs the first-time tty initialization.
2053 * Returns the locked initialized or re-opened &tty_struct
2055 * Claims the global tty_mutex to serialize:
2056 * - concurrent first-time tty initialization
2057 * - concurrent tty driver removal w/ lookup
2058 * - concurrent tty removal from driver table
2060 static struct tty_struct *tty_open_by_driver(dev_t device,
2063 struct tty_struct *tty;
2064 struct tty_driver *driver = NULL;
2068 mutex_lock(&tty_mutex);
2069 driver = tty_lookup_driver(device, filp, &index);
2070 if (IS_ERR(driver)) {
2071 mutex_unlock(&tty_mutex);
2072 return ERR_CAST(driver);
2075 /* check whether we're reopening an existing tty */
2076 tty = tty_driver_lookup_tty(driver, filp, index);
2078 mutex_unlock(&tty_mutex);
2083 if (tty_port_kopened(tty->port)) {
2085 mutex_unlock(&tty_mutex);
2086 tty = ERR_PTR(-EBUSY);
2089 mutex_unlock(&tty_mutex);
2090 retval = tty_lock_interruptible(tty);
2091 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2093 if (retval == -EINTR)
2094 retval = -ERESTARTSYS;
2095 tty = ERR_PTR(retval);
2098 retval = tty_reopen(tty);
2101 tty = ERR_PTR(retval);
2103 } else { /* Returns with the tty_lock held for now */
2104 tty = tty_init_dev(driver, index);
2105 mutex_unlock(&tty_mutex);
2108 tty_driver_kref_put(driver);
2113 * tty_open - open a tty device
2114 * @inode: inode of device file
2115 * @filp: file pointer to tty
2117 * tty_open and tty_release keep up the tty count that contains the
2118 * number of opens done on a tty. We cannot use the inode-count, as
2119 * different inodes might point to the same tty.
2121 * Open-counting is needed for pty masters, as well as for keeping
2122 * track of serial lines: DTR is dropped when the last close happens.
2123 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2125 * The termios state of a pty is reset on first open so that
2126 * settings don't persist across reuse.
2128 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2129 * tty->count should protect the rest.
2130 * ->siglock protects ->signal/->sighand
2132 * Note: the tty_unlock/lock cases without a ref are only safe due to
2136 static int tty_open(struct inode *inode, struct file *filp)
2138 struct tty_struct *tty;
2140 dev_t device = inode->i_rdev;
2141 unsigned saved_flags = filp->f_flags;
2143 nonseekable_open(inode, filp);
2146 retval = tty_alloc_file(filp);
2150 tty = tty_open_current_tty(device, filp);
2152 tty = tty_open_by_driver(device, filp);
2155 tty_free_file(filp);
2156 retval = PTR_ERR(tty);
2157 if (retval != -EAGAIN || signal_pending(current))
2163 tty_add_file(tty, filp);
2165 check_tty_count(tty, __func__);
2166 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2169 retval = tty->ops->open(tty, filp);
2172 filp->f_flags = saved_flags;
2175 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2177 tty_unlock(tty); /* need to call tty_release without BTM */
2178 tty_release(inode, filp);
2179 if (retval != -ERESTARTSYS)
2182 if (signal_pending(current))
2187 * Need to reset f_op in case a hangup happened.
2189 if (tty_hung_up_p(filp))
2190 filp->f_op = &tty_fops;
2193 clear_bit(TTY_HUPPED, &tty->flags);
2195 noctty = (filp->f_flags & O_NOCTTY) ||
2196 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2197 device == MKDEV(TTYAUX_MAJOR, 1) ||
2198 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2199 tty->driver->subtype == PTY_TYPE_MASTER);
2201 tty_open_proc_set_tty(filp, tty);
2209 * tty_poll - check tty status
2210 * @filp: file being polled
2211 * @wait: poll wait structures to update
2213 * Call the line discipline polling method to obtain the poll
2214 * status of the device.
2216 * Locking: locks called line discipline but ldisc poll method
2217 * may be re-entered freely by other callers.
2220 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2222 struct tty_struct *tty = file_tty(filp);
2223 struct tty_ldisc *ld;
2226 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2229 ld = tty_ldisc_ref_wait(tty);
2231 return hung_up_tty_poll(filp, wait);
2233 ret = ld->ops->poll(tty, filp, wait);
2234 tty_ldisc_deref(ld);
2238 static int __tty_fasync(int fd, struct file *filp, int on)
2240 struct tty_struct *tty = file_tty(filp);
2241 unsigned long flags;
2244 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2247 retval = fasync_helper(fd, filp, on, &tty->fasync);
2255 spin_lock_irqsave(&tty->ctrl_lock, flags);
2258 type = PIDTYPE_PGID;
2260 pid = task_pid(current);
2261 type = PIDTYPE_TGID;
2264 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2265 __f_setown(filp, pid, type, 0);
2273 static int tty_fasync(int fd, struct file *filp, int on)
2275 struct tty_struct *tty = file_tty(filp);
2276 int retval = -ENOTTY;
2279 if (!tty_hung_up_p(filp))
2280 retval = __tty_fasync(fd, filp, on);
2287 * tiocsti - fake input character
2288 * @tty: tty to fake input into
2289 * @p: pointer to character
2291 * Fake input to a tty device. Does the necessary locking and
2294 * FIXME: does not honour flow control ??
2297 * Called functions take tty_ldiscs_lock
2298 * current->signal->tty check is safe without locks
2300 * FIXME: may race normal receive processing
2303 static int tiocsti(struct tty_struct *tty, char __user *p)
2306 struct tty_ldisc *ld;
2308 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2310 if (get_user(ch, p))
2312 tty_audit_tiocsti(tty, ch);
2313 ld = tty_ldisc_ref_wait(tty);
2316 if (ld->ops->receive_buf)
2317 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2318 tty_ldisc_deref(ld);
2323 * tiocgwinsz - implement window query ioctl
2325 * @arg: user buffer for result
2327 * Copies the kernel idea of the window size into the user buffer.
2329 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2333 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2337 mutex_lock(&tty->winsize_mutex);
2338 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2339 mutex_unlock(&tty->winsize_mutex);
2341 return err ? -EFAULT: 0;
2345 * tty_do_resize - resize event
2346 * @tty: tty being resized
2347 * @ws: new dimensions
2349 * Update the termios variables and send the necessary signals to
2350 * peform a terminal resize correctly
2353 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2358 mutex_lock(&tty->winsize_mutex);
2359 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2362 /* Signal the foreground process group */
2363 pgrp = tty_get_pgrp(tty);
2365 kill_pgrp(pgrp, SIGWINCH, 1);
2370 mutex_unlock(&tty->winsize_mutex);
2373 EXPORT_SYMBOL(tty_do_resize);
2376 * tiocswinsz - implement window size set ioctl
2377 * @tty: tty side of tty
2378 * @arg: user buffer for result
2380 * Copies the user idea of the window size to the kernel. Traditionally
2381 * this is just advisory information but for the Linux console it
2382 * actually has driver level meaning and triggers a VC resize.
2385 * Driver dependent. The default do_resize method takes the
2386 * tty termios mutex and ctrl_lock. The console takes its own lock
2387 * then calls into the default method.
2390 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2392 struct winsize tmp_ws;
2393 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2396 if (tty->ops->resize)
2397 return tty->ops->resize(tty, &tmp_ws);
2399 return tty_do_resize(tty, &tmp_ws);
2403 * tioccons - allow admin to move logical console
2404 * @file: the file to become console
2406 * Allow the administrator to move the redirected console device
2408 * Locking: uses redirect_lock to guard the redirect information
2411 static int tioccons(struct file *file)
2413 if (!capable(CAP_SYS_ADMIN))
2415 if (file->f_op->write_iter == redirected_tty_write) {
2417 spin_lock(&redirect_lock);
2420 spin_unlock(&redirect_lock);
2425 if (file->f_op->write_iter != tty_write)
2427 if (!(file->f_mode & FMODE_WRITE))
2429 if (!(file->f_mode & FMODE_CAN_WRITE))
2431 spin_lock(&redirect_lock);
2433 spin_unlock(&redirect_lock);
2436 redirect = get_file(file);
2437 spin_unlock(&redirect_lock);
2442 * tiocsetd - set line discipline
2444 * @p: pointer to user data
2446 * Set the line discipline according to user request.
2448 * Locking: see tty_set_ldisc, this function is just a helper
2451 static int tiocsetd(struct tty_struct *tty, int __user *p)
2456 if (get_user(disc, p))
2459 ret = tty_set_ldisc(tty, disc);
2465 * tiocgetd - get line discipline
2467 * @p: pointer to user data
2469 * Retrieves the line discipline id directly from the ldisc.
2471 * Locking: waits for ldisc reference (in case the line discipline
2472 * is changing or the tty is being hungup)
2475 static int tiocgetd(struct tty_struct *tty, int __user *p)
2477 struct tty_ldisc *ld;
2480 ld = tty_ldisc_ref_wait(tty);
2483 ret = put_user(ld->ops->num, p);
2484 tty_ldisc_deref(ld);
2489 * send_break - performed time break
2490 * @tty: device to break on
2491 * @duration: timeout in mS
2493 * Perform a timed break on hardware that lacks its own driver level
2494 * timed break functionality.
2497 * atomic_write_lock serializes
2501 static int send_break(struct tty_struct *tty, unsigned int duration)
2505 if (tty->ops->break_ctl == NULL)
2508 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2509 retval = tty->ops->break_ctl(tty, duration);
2511 /* Do the work ourselves */
2512 if (tty_write_lock(tty, 0) < 0)
2514 retval = tty->ops->break_ctl(tty, -1);
2517 if (!signal_pending(current))
2518 msleep_interruptible(duration);
2519 retval = tty->ops->break_ctl(tty, 0);
2521 tty_write_unlock(tty);
2522 if (signal_pending(current))
2529 * tty_tiocmget - get modem status
2531 * @p: pointer to result
2533 * Obtain the modem status bits from the tty driver if the feature
2534 * is supported. Return -EINVAL if it is not available.
2536 * Locking: none (up to the driver)
2539 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2541 int retval = -EINVAL;
2543 if (tty->ops->tiocmget) {
2544 retval = tty->ops->tiocmget(tty);
2547 retval = put_user(retval, p);
2553 * tty_tiocmset - set modem status
2555 * @cmd: command - clear bits, set bits or set all
2556 * @p: pointer to desired bits
2558 * Set the modem status bits from the tty driver if the feature
2559 * is supported. Return -EINVAL if it is not available.
2561 * Locking: none (up to the driver)
2564 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2568 unsigned int set, clear, val;
2570 if (tty->ops->tiocmset == NULL)
2573 retval = get_user(val, p);
2589 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2590 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2591 return tty->ops->tiocmset(tty, set, clear);
2595 * tty_get_icount - get tty statistics
2597 * @icount: output parameter
2599 * Gets a copy of the tty's icount statistics.
2601 * Locking: none (up to the driver)
2603 int tty_get_icount(struct tty_struct *tty,
2604 struct serial_icounter_struct *icount)
2606 memset(icount, 0, sizeof(*icount));
2608 if (tty->ops->get_icount)
2609 return tty->ops->get_icount(tty, icount);
2613 EXPORT_SYMBOL_GPL(tty_get_icount);
2615 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2617 struct serial_icounter_struct icount;
2620 retval = tty_get_icount(tty, &icount);
2624 if (copy_to_user(arg, &icount, sizeof(icount)))
2629 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2631 static DEFINE_RATELIMIT_STATE(depr_flags,
2632 DEFAULT_RATELIMIT_INTERVAL,
2633 DEFAULT_RATELIMIT_BURST);
2634 char comm[TASK_COMM_LEN];
2635 struct serial_struct v;
2638 if (copy_from_user(&v, ss, sizeof(*ss)))
2641 flags = v.flags & ASYNC_DEPRECATED;
2643 if (flags && __ratelimit(&depr_flags))
2644 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2645 __func__, get_task_comm(comm, current), flags);
2646 if (!tty->ops->set_serial)
2648 return tty->ops->set_serial(tty, &v);
2651 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2653 struct serial_struct v;
2656 memset(&v, 0, sizeof(v));
2657 if (!tty->ops->get_serial)
2659 err = tty->ops->get_serial(tty, &v);
2660 if (!err && copy_to_user(ss, &v, sizeof(v)))
2666 * if pty, return the slave side (real_tty)
2667 * otherwise, return self
2669 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2671 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2672 tty->driver->subtype == PTY_TYPE_MASTER)
2678 * Split this up, as gcc can choke on it otherwise..
2680 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2682 struct tty_struct *tty = file_tty(file);
2683 struct tty_struct *real_tty;
2684 void __user *p = (void __user *)arg;
2686 struct tty_ldisc *ld;
2688 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2691 real_tty = tty_pair_get_tty(tty);
2694 * Factor out some common prep work
2702 retval = tty_check_change(tty);
2705 if (cmd != TIOCCBRK) {
2706 tty_wait_until_sent(tty, 0);
2707 if (signal_pending(current))
2718 return tiocsti(tty, p);
2720 return tiocgwinsz(real_tty, p);
2722 return tiocswinsz(real_tty, p);
2724 return real_tty != tty ? -EINVAL : tioccons(file);
2726 set_bit(TTY_EXCLUSIVE, &tty->flags);
2729 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2733 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2734 return put_user(excl, (int __user *)p);
2737 return tiocgetd(tty, p);
2739 return tiocsetd(tty, p);
2741 if (!capable(CAP_SYS_ADMIN))
2747 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2748 return put_user(ret, (unsigned int __user *)p);
2753 case TIOCSBRK: /* Turn break on, unconditionally */
2754 if (tty->ops->break_ctl)
2755 return tty->ops->break_ctl(tty, -1);
2757 case TIOCCBRK: /* Turn break off, unconditionally */
2758 if (tty->ops->break_ctl)
2759 return tty->ops->break_ctl(tty, 0);
2761 case TCSBRK: /* SVID version: non-zero arg --> no break */
2762 /* non-zero arg means wait for all output data
2763 * to be sent (performed above) but don't send break.
2764 * This is used by the tcdrain() termios function.
2767 return send_break(tty, 250);
2769 case TCSBRKP: /* support for POSIX tcsendbreak() */
2770 return send_break(tty, arg ? arg*100 : 250);
2773 return tty_tiocmget(tty, p);
2777 return tty_tiocmset(tty, cmd, p);
2779 return tty_tiocgicount(tty, p);
2784 /* flush tty buffer and allow ldisc to process ioctl */
2785 tty_buffer_flush(tty, NULL);
2790 return tty_tiocsserial(tty, p);
2792 return tty_tiocgserial(tty, p);
2794 /* Special because the struct file is needed */
2795 return ptm_open_peer(file, tty, (int)arg);
2797 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2798 if (retval != -ENOIOCTLCMD)
2801 if (tty->ops->ioctl) {
2802 retval = tty->ops->ioctl(tty, cmd, arg);
2803 if (retval != -ENOIOCTLCMD)
2806 ld = tty_ldisc_ref_wait(tty);
2808 return hung_up_tty_ioctl(file, cmd, arg);
2810 if (ld->ops->ioctl) {
2811 retval = ld->ops->ioctl(tty, file, cmd, arg);
2812 if (retval == -ENOIOCTLCMD)
2815 tty_ldisc_deref(ld);
2819 #ifdef CONFIG_COMPAT
2821 struct serial_struct32 {
2827 compat_int_t xmit_fifo_size;
2828 compat_int_t custom_divisor;
2829 compat_int_t baud_base;
2830 unsigned short close_delay;
2834 unsigned short closing_wait; /* time to wait before closing */
2835 unsigned short closing_wait2; /* no longer used... */
2836 compat_uint_t iomem_base;
2837 unsigned short iomem_reg_shift;
2838 unsigned int port_high;
2839 /* compat_ulong_t iomap_base FIXME */
2840 compat_int_t reserved;
2843 static int compat_tty_tiocsserial(struct tty_struct *tty,
2844 struct serial_struct32 __user *ss)
2846 static DEFINE_RATELIMIT_STATE(depr_flags,
2847 DEFAULT_RATELIMIT_INTERVAL,
2848 DEFAULT_RATELIMIT_BURST);
2849 char comm[TASK_COMM_LEN];
2850 struct serial_struct32 v32;
2851 struct serial_struct v;
2854 if (copy_from_user(&v32, ss, sizeof(*ss)))
2857 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2858 v.iomem_base = compat_ptr(v32.iomem_base);
2859 v.iomem_reg_shift = v32.iomem_reg_shift;
2860 v.port_high = v32.port_high;
2863 flags = v.flags & ASYNC_DEPRECATED;
2865 if (flags && __ratelimit(&depr_flags))
2866 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2867 __func__, get_task_comm(comm, current), flags);
2868 if (!tty->ops->set_serial)
2870 return tty->ops->set_serial(tty, &v);
2873 static int compat_tty_tiocgserial(struct tty_struct *tty,
2874 struct serial_struct32 __user *ss)
2876 struct serial_struct32 v32;
2877 struct serial_struct v;
2880 memset(&v, 0, sizeof(v));
2881 memset(&v32, 0, sizeof(v32));
2883 if (!tty->ops->get_serial)
2885 err = tty->ops->get_serial(tty, &v);
2887 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2888 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2889 0xfffffff : ptr_to_compat(v.iomem_base);
2890 v32.iomem_reg_shift = v.iomem_reg_shift;
2891 v32.port_high = v.port_high;
2892 if (copy_to_user(ss, &v32, sizeof(v32)))
2897 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2900 struct tty_struct *tty = file_tty(file);
2901 struct tty_ldisc *ld;
2902 int retval = -ENOIOCTLCMD;
2951 case TIOCGLCKTRMIOS:
2952 case TIOCSLCKTRMIOS:
2964 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2980 return tty_ioctl(file, cmd, arg);
2983 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2988 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2990 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2992 if (tty->ops->compat_ioctl) {
2993 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2994 if (retval != -ENOIOCTLCMD)
2998 ld = tty_ldisc_ref_wait(tty);
3000 return hung_up_tty_compat_ioctl(file, cmd, arg);
3001 if (ld->ops->compat_ioctl)
3002 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
3003 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
3004 retval = ld->ops->ioctl(tty, file,
3005 (unsigned long)compat_ptr(cmd), arg);
3006 tty_ldisc_deref(ld);
3012 static int this_tty(const void *t, struct file *file, unsigned fd)
3014 if (likely(file->f_op->read_iter != tty_read))
3016 return file_tty(file) != t ? 0 : fd + 1;
3020 * This implements the "Secure Attention Key" --- the idea is to
3021 * prevent trojan horses by killing all processes associated with this
3022 * tty when the user hits the "Secure Attention Key". Required for
3023 * super-paranoid applications --- see the Orange Book for more details.
3025 * This code could be nicer; ideally it should send a HUP, wait a few
3026 * seconds, then send a INT, and then a KILL signal. But you then
3027 * have to coordinate with the init process, since all processes associated
3028 * with the current tty must be dead before the new getty is allowed
3031 * Now, if it would be correct ;-/ The current code has a nasty hole -
3032 * it doesn't catch files in flight. We may send the descriptor to ourselves
3033 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3035 * Nasty bug: do_SAK is being called in interrupt context. This can
3036 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3038 void __do_SAK(struct tty_struct *tty)
3043 struct task_struct *g, *p;
3044 struct pid *session;
3046 unsigned long flags;
3051 spin_lock_irqsave(&tty->ctrl_lock, flags);
3052 session = get_pid(tty->session);
3053 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3055 tty_ldisc_flush(tty);
3057 tty_driver_flush_buffer(tty);
3059 read_lock(&tasklist_lock);
3060 /* Kill the entire session */
3061 do_each_pid_task(session, PIDTYPE_SID, p) {
3062 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3063 task_pid_nr(p), p->comm);
3064 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3065 } while_each_pid_task(session, PIDTYPE_SID, p);
3067 /* Now kill any processes that happen to have the tty open */
3068 do_each_thread(g, p) {
3069 if (p->signal->tty == tty) {
3070 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3071 task_pid_nr(p), p->comm);
3072 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3076 i = iterate_fd(p->files, 0, this_tty, tty);
3078 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3079 task_pid_nr(p), p->comm, i - 1);
3080 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3083 } while_each_thread(g, p);
3084 read_unlock(&tasklist_lock);
3089 static void do_SAK_work(struct work_struct *work)
3091 struct tty_struct *tty =
3092 container_of(work, struct tty_struct, SAK_work);
3097 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3098 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3099 * the values which we write to it will be identical to the values which it
3100 * already has. --akpm
3102 void do_SAK(struct tty_struct *tty)
3106 schedule_work(&tty->SAK_work);
3109 EXPORT_SYMBOL(do_SAK);
3111 /* Must put_device() after it's unused! */
3112 static struct device *tty_get_device(struct tty_struct *tty)
3114 dev_t devt = tty_devnum(tty);
3115 return class_find_device_by_devt(tty_class, devt);
3122 * This subroutine allocates and initializes a tty structure.
3124 * Locking: none - tty in question is not exposed at this point
3127 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3129 struct tty_struct *tty;
3131 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3135 kref_init(&tty->kref);
3136 tty->magic = TTY_MAGIC;
3137 if (tty_ldisc_init(tty)) {
3141 tty->session = NULL;
3143 mutex_init(&tty->legacy_mutex);
3144 mutex_init(&tty->throttle_mutex);
3145 init_rwsem(&tty->termios_rwsem);
3146 mutex_init(&tty->winsize_mutex);
3147 init_ldsem(&tty->ldisc_sem);
3148 init_waitqueue_head(&tty->write_wait);
3149 init_waitqueue_head(&tty->read_wait);
3150 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3151 mutex_init(&tty->atomic_write_lock);
3152 spin_lock_init(&tty->ctrl_lock);
3153 spin_lock_init(&tty->flow_lock);
3154 spin_lock_init(&tty->files_lock);
3155 INIT_LIST_HEAD(&tty->tty_files);
3156 INIT_WORK(&tty->SAK_work, do_SAK_work);
3158 tty->driver = driver;
3159 tty->ops = driver->ops;
3161 tty_line_name(driver, idx, tty->name);
3162 tty->dev = tty_get_device(tty);
3168 * tty_put_char - write one character to a tty
3172 * Write one byte to the tty using the provided put_char method
3173 * if present. Returns the number of characters successfully output.
3175 * Note: the specific put_char operation in the driver layer may go
3176 * away soon. Don't call it directly, use this method
3179 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3181 if (tty->ops->put_char)
3182 return tty->ops->put_char(tty, ch);
3183 return tty->ops->write(tty, &ch, 1);
3185 EXPORT_SYMBOL_GPL(tty_put_char);
3187 struct class *tty_class;
3189 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3190 unsigned int index, unsigned int count)
3194 /* init here, since reused cdevs cause crashes */
3195 driver->cdevs[index] = cdev_alloc();
3196 if (!driver->cdevs[index])
3198 driver->cdevs[index]->ops = &tty_fops;
3199 driver->cdevs[index]->owner = driver->owner;
3200 err = cdev_add(driver->cdevs[index], dev, count);
3202 kobject_put(&driver->cdevs[index]->kobj);
3207 * tty_register_device - register a tty device
3208 * @driver: the tty driver that describes the tty device
3209 * @index: the index in the tty driver for this tty device
3210 * @device: a struct device that is associated with this tty device.
3211 * This field is optional, if there is no known struct device
3212 * for this tty device it can be set to NULL safely.
3214 * Returns a pointer to the struct device for this tty device
3215 * (or ERR_PTR(-EFOO) on error).
3217 * This call is required to be made to register an individual tty device
3218 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3219 * that bit is not set, this function should not be called by a tty
3225 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3226 struct device *device)
3228 return tty_register_device_attr(driver, index, device, NULL, NULL);
3230 EXPORT_SYMBOL(tty_register_device);
3232 static void tty_device_create_release(struct device *dev)
3234 dev_dbg(dev, "releasing...\n");
3239 * tty_register_device_attr - register a tty device
3240 * @driver: the tty driver that describes the tty device
3241 * @index: the index in the tty driver for this tty device
3242 * @device: a struct device that is associated with this tty device.
3243 * This field is optional, if there is no known struct device
3244 * for this tty device it can be set to NULL safely.
3245 * @drvdata: Driver data to be set to device.
3246 * @attr_grp: Attribute group to be set on device.
3248 * Returns a pointer to the struct device for this tty device
3249 * (or ERR_PTR(-EFOO) on error).
3251 * This call is required to be made to register an individual tty device
3252 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3253 * that bit is not set, this function should not be called by a tty
3258 struct device *tty_register_device_attr(struct tty_driver *driver,
3259 unsigned index, struct device *device,
3261 const struct attribute_group **attr_grp)
3264 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3265 struct ktermios *tp;
3269 if (index >= driver->num) {
3270 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3271 driver->name, index);
3272 return ERR_PTR(-EINVAL);
3275 if (driver->type == TTY_DRIVER_TYPE_PTY)
3276 pty_line_name(driver, index, name);
3278 tty_line_name(driver, index, name);
3280 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3282 return ERR_PTR(-ENOMEM);
3285 dev->class = tty_class;
3286 dev->parent = device;
3287 dev->release = tty_device_create_release;
3288 dev_set_name(dev, "%s", name);
3289 dev->groups = attr_grp;
3290 dev_set_drvdata(dev, drvdata);
3292 dev_set_uevent_suppress(dev, 1);
3294 retval = device_register(dev);
3298 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3300 * Free any saved termios data so that the termios state is
3301 * reset when reusing a minor number.
3303 tp = driver->termios[index];
3305 driver->termios[index] = NULL;
3309 retval = tty_cdev_add(driver, devt, index, 1);
3314 dev_set_uevent_suppress(dev, 0);
3315 kobject_uevent(&dev->kobj, KOBJ_ADD);
3324 return ERR_PTR(retval);
3326 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3329 * tty_unregister_device - unregister a tty device
3330 * @driver: the tty driver that describes the tty device
3331 * @index: the index in the tty driver for this tty device
3333 * If a tty device is registered with a call to tty_register_device() then
3334 * this function must be called when the tty device is gone.
3339 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3341 device_destroy(tty_class,
3342 MKDEV(driver->major, driver->minor_start) + index);
3343 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3344 cdev_del(driver->cdevs[index]);
3345 driver->cdevs[index] = NULL;
3348 EXPORT_SYMBOL(tty_unregister_device);
3351 * __tty_alloc_driver -- allocate tty driver
3352 * @lines: count of lines this driver can handle at most
3353 * @owner: module which is responsible for this driver
3354 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3356 * This should not be called directly, some of the provided macros should be
3357 * used instead. Use IS_ERR and friends on @retval.
3359 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3360 unsigned long flags)
3362 struct tty_driver *driver;
3363 unsigned int cdevs = 1;
3366 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3367 return ERR_PTR(-EINVAL);
3369 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3371 return ERR_PTR(-ENOMEM);
3373 kref_init(&driver->kref);
3374 driver->magic = TTY_DRIVER_MAGIC;
3375 driver->num = lines;
3376 driver->owner = owner;
3377 driver->flags = flags;
3379 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3380 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3382 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3384 if (!driver->ttys || !driver->termios) {
3390 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3391 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3393 if (!driver->ports) {
3400 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3401 if (!driver->cdevs) {
3408 kfree(driver->ports);
3409 kfree(driver->ttys);
3410 kfree(driver->termios);
3411 kfree(driver->cdevs);
3413 return ERR_PTR(err);
3415 EXPORT_SYMBOL(__tty_alloc_driver);
3417 static void destruct_tty_driver(struct kref *kref)
3419 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3421 struct ktermios *tp;
3423 if (driver->flags & TTY_DRIVER_INSTALLED) {
3424 for (i = 0; i < driver->num; i++) {
3425 tp = driver->termios[i];
3427 driver->termios[i] = NULL;
3430 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3431 tty_unregister_device(driver, i);
3433 proc_tty_unregister_driver(driver);
3434 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3435 cdev_del(driver->cdevs[0]);
3437 kfree(driver->cdevs);
3438 kfree(driver->ports);
3439 kfree(driver->termios);
3440 kfree(driver->ttys);
3444 void tty_driver_kref_put(struct tty_driver *driver)
3446 kref_put(&driver->kref, destruct_tty_driver);
3448 EXPORT_SYMBOL(tty_driver_kref_put);
3450 void tty_set_operations(struct tty_driver *driver,
3451 const struct tty_operations *op)
3455 EXPORT_SYMBOL(tty_set_operations);
3457 void put_tty_driver(struct tty_driver *d)
3459 tty_driver_kref_put(d);
3461 EXPORT_SYMBOL(put_tty_driver);
3464 * Called by a tty driver to register itself.
3466 int tty_register_driver(struct tty_driver *driver)
3473 if (!driver->major) {
3474 error = alloc_chrdev_region(&dev, driver->minor_start,
3475 driver->num, driver->name);
3477 driver->major = MAJOR(dev);
3478 driver->minor_start = MINOR(dev);
3481 dev = MKDEV(driver->major, driver->minor_start);
3482 error = register_chrdev_region(dev, driver->num, driver->name);
3487 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3488 error = tty_cdev_add(driver, dev, 0, driver->num);
3490 goto err_unreg_char;
3493 mutex_lock(&tty_mutex);
3494 list_add(&driver->tty_drivers, &tty_drivers);
3495 mutex_unlock(&tty_mutex);
3497 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3498 for (i = 0; i < driver->num; i++) {
3499 d = tty_register_device(driver, i, NULL);
3502 goto err_unreg_devs;
3506 proc_tty_register_driver(driver);
3507 driver->flags |= TTY_DRIVER_INSTALLED;
3511 for (i--; i >= 0; i--)
3512 tty_unregister_device(driver, i);
3514 mutex_lock(&tty_mutex);
3515 list_del(&driver->tty_drivers);
3516 mutex_unlock(&tty_mutex);
3519 unregister_chrdev_region(dev, driver->num);
3523 EXPORT_SYMBOL(tty_register_driver);
3526 * Called by a tty driver to unregister itself.
3528 int tty_unregister_driver(struct tty_driver *driver)
3532 if (driver->refcount)
3535 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3537 mutex_lock(&tty_mutex);
3538 list_del(&driver->tty_drivers);
3539 mutex_unlock(&tty_mutex);
3543 EXPORT_SYMBOL(tty_unregister_driver);
3545 dev_t tty_devnum(struct tty_struct *tty)
3547 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3549 EXPORT_SYMBOL(tty_devnum);
3551 void tty_default_fops(struct file_operations *fops)
3556 static char *tty_devnode(struct device *dev, umode_t *mode)
3560 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3561 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3566 static int __init tty_class_init(void)
3568 tty_class = class_create(THIS_MODULE, "tty");
3569 if (IS_ERR(tty_class))
3570 return PTR_ERR(tty_class);
3571 tty_class->devnode = tty_devnode;
3575 postcore_initcall(tty_class_init);
3577 /* 3/2004 jmc: why do these devices exist? */
3578 static struct cdev tty_cdev, console_cdev;
3580 static ssize_t show_cons_active(struct device *dev,
3581 struct device_attribute *attr, char *buf)
3583 struct console *cs[16];
3589 for_each_console(c) {
3594 if ((c->flags & CON_ENABLED) == 0)
3597 if (i >= ARRAY_SIZE(cs))
3601 int index = cs[i]->index;
3602 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3604 /* don't resolve tty0 as some programs depend on it */
3605 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3606 count += tty_line_name(drv, index, buf + count);
3608 count += sprintf(buf + count, "%s%d",
3609 cs[i]->name, cs[i]->index);
3611 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3617 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3619 static struct attribute *cons_dev_attrs[] = {
3620 &dev_attr_active.attr,
3624 ATTRIBUTE_GROUPS(cons_dev);
3626 static struct device *consdev;
3628 void console_sysfs_notify(void)
3631 sysfs_notify(&consdev->kobj, NULL, "active");
3635 * Ok, now we can initialize the rest of the tty devices and can count
3636 * on memory allocations, interrupts etc..
3638 int __init tty_init(void)
3641 cdev_init(&tty_cdev, &tty_fops);
3642 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3643 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3644 panic("Couldn't register /dev/tty driver\n");
3645 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3647 cdev_init(&console_cdev, &console_fops);
3648 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3649 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3650 panic("Couldn't register /dev/console driver\n");
3651 consdev = device_create_with_groups(tty_class, NULL,
3652 MKDEV(TTYAUX_MAJOR, 1), NULL,
3653 cons_dev_groups, "console");
3654 if (IS_ERR(consdev))
3658 vty_init(&console_fops);