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 ssize_t redirected_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 *);
150 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
152 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
155 #define tty_compat_ioctl NULL
157 static int __tty_fasync(int fd, struct file *filp, int on);
158 static int tty_fasync(int fd, struct file *filp, int on);
159 static void release_tty(struct tty_struct *tty, int idx);
162 * free_tty_struct - free a disused tty
163 * @tty: tty struct to free
165 * Free the write buffers, tty queue and tty memory itself.
167 * Locking: none. Must be called after tty is definitely unused
170 static void free_tty_struct(struct tty_struct *tty)
172 tty_ldisc_deinit(tty);
173 put_device(tty->dev);
174 kfree(tty->write_buf);
175 tty->magic = 0xDEADDEAD;
179 static inline struct tty_struct *file_tty(struct file *file)
181 return ((struct tty_file_private *)file->private_data)->tty;
184 int tty_alloc_file(struct file *file)
186 struct tty_file_private *priv;
188 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
192 file->private_data = priv;
197 /* Associate a new file with the tty structure */
198 void tty_add_file(struct tty_struct *tty, struct file *file)
200 struct tty_file_private *priv = file->private_data;
205 spin_lock(&tty->files_lock);
206 list_add(&priv->list, &tty->tty_files);
207 spin_unlock(&tty->files_lock);
211 * tty_free_file - free file->private_data
213 * This shall be used only for fail path handling when tty_add_file was not
216 void tty_free_file(struct file *file)
218 struct tty_file_private *priv = file->private_data;
220 file->private_data = NULL;
224 /* Delete file from its tty */
225 static void tty_del_file(struct file *file)
227 struct tty_file_private *priv = file->private_data;
228 struct tty_struct *tty = priv->tty;
230 spin_lock(&tty->files_lock);
231 list_del(&priv->list);
232 spin_unlock(&tty->files_lock);
237 * tty_name - return tty naming
238 * @tty: tty structure
240 * Convert a tty structure into a name. The name reflects the kernel
241 * naming policy and if udev is in use may not reflect user space
246 const char *tty_name(const struct tty_struct *tty)
248 if (!tty) /* Hmm. NULL pointer. That's fun. */
253 EXPORT_SYMBOL(tty_name);
255 const char *tty_driver_name(const struct tty_struct *tty)
257 if (!tty || !tty->driver)
259 return tty->driver->name;
262 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
265 #ifdef TTY_PARANOIA_CHECK
267 pr_warn("(%d:%d): %s: NULL tty\n",
268 imajor(inode), iminor(inode), routine);
271 if (tty->magic != TTY_MAGIC) {
272 pr_warn("(%d:%d): %s: bad magic number\n",
273 imajor(inode), iminor(inode), routine);
280 /* Caller must hold tty_lock */
281 static int check_tty_count(struct tty_struct *tty, const char *routine)
283 #ifdef CHECK_TTY_COUNT
285 int count = 0, kopen_count = 0;
287 spin_lock(&tty->files_lock);
288 list_for_each(p, &tty->tty_files) {
291 spin_unlock(&tty->files_lock);
292 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
293 tty->driver->subtype == PTY_TYPE_SLAVE &&
294 tty->link && tty->link->count)
296 if (tty_port_kopened(tty->port))
298 if (tty->count != (count + kopen_count)) {
299 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
300 routine, tty->count, count, kopen_count);
301 return (count + kopen_count);
308 * get_tty_driver - find device of a tty
309 * @device: device identifier
310 * @index: returns the index of the tty
312 * This routine returns a tty driver structure, given a device number
313 * and also passes back the index number.
315 * Locking: caller must hold tty_mutex
318 static struct tty_driver *get_tty_driver(dev_t device, int *index)
320 struct tty_driver *p;
322 list_for_each_entry(p, &tty_drivers, tty_drivers) {
323 dev_t base = MKDEV(p->major, p->minor_start);
324 if (device < base || device >= base + p->num)
326 *index = device - base;
327 return tty_driver_kref_get(p);
333 * tty_dev_name_to_number - return dev_t for device name
334 * @name: user space name of device under /dev
335 * @number: pointer to dev_t that this function will populate
337 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
338 * like (4, 64) or (188, 1). If no corresponding driver is registered then
339 * the function returns -ENODEV.
341 * Locking: this acquires tty_mutex to protect the tty_drivers list from
342 * being modified while we are traversing it, and makes sure to
343 * release it before exiting.
345 int tty_dev_name_to_number(const char *name, dev_t *number)
347 struct tty_driver *p;
349 int index, prefix_length = 0;
352 for (str = name; *str && !isdigit(*str); str++)
358 ret = kstrtoint(str, 10, &index);
362 prefix_length = str - name;
363 mutex_lock(&tty_mutex);
365 list_for_each_entry(p, &tty_drivers, tty_drivers)
366 if (prefix_length == strlen(p->name) && strncmp(name,
367 p->name, prefix_length) == 0) {
368 if (index < p->num) {
369 *number = MKDEV(p->major, p->minor_start + index);
374 /* if here then driver wasn't found */
377 mutex_unlock(&tty_mutex);
380 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
382 #ifdef CONFIG_CONSOLE_POLL
385 * tty_find_polling_driver - find device of a polled tty
386 * @name: name string to match
387 * @line: pointer to resulting tty line nr
389 * This routine returns a tty driver structure, given a name
390 * and the condition that the tty driver is capable of polled
393 struct tty_driver *tty_find_polling_driver(char *name, int *line)
395 struct tty_driver *p, *res = NULL;
400 for (str = name; *str; str++)
401 if ((*str >= '0' && *str <= '9') || *str == ',')
407 tty_line = simple_strtoul(str, &str, 10);
409 mutex_lock(&tty_mutex);
410 /* Search through the tty devices to look for a match */
411 list_for_each_entry(p, &tty_drivers, tty_drivers) {
412 if (!len || strncmp(name, p->name, len) != 0)
420 if (tty_line >= 0 && tty_line < p->num && p->ops &&
421 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
422 res = tty_driver_kref_get(p);
427 mutex_unlock(&tty_mutex);
431 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
434 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
439 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
444 /* No kernel lock held - none needed ;) */
445 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
447 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
450 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
453 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
456 static long hung_up_tty_compat_ioctl(struct file *file,
457 unsigned int cmd, unsigned long arg)
459 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
462 static int hung_up_tty_fasync(int fd, struct file *file, int on)
467 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
469 struct tty_struct *tty = file_tty(file);
471 if (tty && tty->ops && tty->ops->show_fdinfo)
472 tty->ops->show_fdinfo(tty, m);
475 static const struct file_operations tty_fops = {
477 .read_iter = tty_read,
478 .write_iter = tty_write,
479 .splice_read = generic_file_splice_read,
480 .splice_write = iter_file_splice_write,
482 .unlocked_ioctl = tty_ioctl,
483 .compat_ioctl = tty_compat_ioctl,
485 .release = tty_release,
486 .fasync = tty_fasync,
487 .show_fdinfo = tty_show_fdinfo,
490 static const struct file_operations console_fops = {
492 .read_iter = tty_read,
493 .write_iter = redirected_tty_write,
494 .splice_read = generic_file_splice_read,
495 .splice_write = iter_file_splice_write,
497 .unlocked_ioctl = tty_ioctl,
498 .compat_ioctl = tty_compat_ioctl,
500 .release = tty_release,
501 .fasync = tty_fasync,
504 static const struct file_operations hung_up_tty_fops = {
506 .read_iter = hung_up_tty_read,
507 .write_iter = hung_up_tty_write,
508 .poll = hung_up_tty_poll,
509 .unlocked_ioctl = hung_up_tty_ioctl,
510 .compat_ioctl = hung_up_tty_compat_ioctl,
511 .release = tty_release,
512 .fasync = hung_up_tty_fasync,
515 static DEFINE_SPINLOCK(redirect_lock);
516 static struct file *redirect;
519 * tty_wakeup - request more data
522 * Internal and external helper for wakeups of tty. This function
523 * informs the line discipline if present that the driver is ready
524 * to receive more output data.
527 void tty_wakeup(struct tty_struct *tty)
529 struct tty_ldisc *ld;
531 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
532 ld = tty_ldisc_ref(tty);
534 if (ld->ops->write_wakeup)
535 ld->ops->write_wakeup(tty);
539 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
542 EXPORT_SYMBOL_GPL(tty_wakeup);
545 * tty_release_redirect - Release a redirect on a pty if present
548 * This is available to the pty code so if the master closes, if the
549 * slave is a redirect it can release the redirect. It returns the
550 * filp for the redirect, which must be fput when the operations on
551 * the tty are completed.
553 struct file *tty_release_redirect(struct tty_struct *tty)
555 struct file *f = NULL;
557 spin_lock(&redirect_lock);
558 if (redirect && file_tty(redirect) == tty) {
562 spin_unlock(&redirect_lock);
568 * __tty_hangup - actual handler for hangup events
570 * @exit_session: if non-zero, signal all foreground group processes
572 * This can be called by a "kworker" kernel thread. That is process
573 * synchronous but doesn't hold any locks, so we need to make sure we
574 * have the appropriate locks for what we're doing.
576 * The hangup event clears any pending redirections onto the hung up
577 * device. It ensures future writes will error and it does the needed
578 * line discipline hangup and signal delivery. The tty object itself
583 * redirect lock for undoing redirection
584 * file list lock for manipulating list of ttys
585 * tty_ldiscs_lock from called functions
586 * termios_rwsem resetting termios data
587 * tasklist_lock to walk task list for hangup event
588 * ->siglock to protect ->signal/->sighand
590 static void __tty_hangup(struct tty_struct *tty, int exit_session)
592 struct file *cons_filp = NULL;
593 struct file *filp, *f;
594 struct tty_file_private *priv;
595 int closecount = 0, n;
601 f = tty_release_redirect(tty);
605 if (test_bit(TTY_HUPPED, &tty->flags)) {
611 * Some console devices aren't actually hung up for technical and
612 * historical reasons, which can lead to indefinite interruptible
613 * sleep in n_tty_read(). The following explicitly tells
614 * n_tty_read() to abort readers.
616 set_bit(TTY_HUPPING, &tty->flags);
618 /* inuse_filps is protected by the single tty lock,
619 this really needs to change if we want to flush the
620 workqueue with the lock held */
621 check_tty_count(tty, "tty_hangup");
623 spin_lock(&tty->files_lock);
624 /* This breaks for file handles being sent over AF_UNIX sockets ? */
625 list_for_each_entry(priv, &tty->tty_files, list) {
627 if (filp->f_op->write_iter == redirected_tty_write)
629 if (filp->f_op->write_iter != tty_write)
632 __tty_fasync(-1, filp, 0); /* can't block */
633 filp->f_op = &hung_up_tty_fops;
635 spin_unlock(&tty->files_lock);
637 refs = tty_signal_session_leader(tty, exit_session);
638 /* Account for the p->signal references we killed */
642 tty_ldisc_hangup(tty, cons_filp != NULL);
644 spin_lock_irq(&tty->ctrl_lock);
645 clear_bit(TTY_THROTTLED, &tty->flags);
646 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
647 put_pid(tty->session);
651 tty->ctrl_status = 0;
652 spin_unlock_irq(&tty->ctrl_lock);
655 * If one of the devices matches a console pointer, we
656 * cannot just call hangup() because that will cause
657 * tty->count and state->count to go out of sync.
658 * So we just call close() the right number of times.
662 for (n = 0; n < closecount; n++)
663 tty->ops->close(tty, cons_filp);
664 } else if (tty->ops->hangup)
665 tty->ops->hangup(tty);
667 * We don't want to have driver/ldisc interactions beyond the ones
668 * we did here. The driver layer expects no calls after ->hangup()
669 * from the ldisc side, which is now guaranteed.
671 set_bit(TTY_HUPPED, &tty->flags);
672 clear_bit(TTY_HUPPING, &tty->flags);
679 static void do_tty_hangup(struct work_struct *work)
681 struct tty_struct *tty =
682 container_of(work, struct tty_struct, hangup_work);
684 __tty_hangup(tty, 0);
688 * tty_hangup - trigger a hangup event
689 * @tty: tty to hangup
691 * A carrier loss (virtual or otherwise) has occurred on this like
692 * schedule a hangup sequence to run after this event.
695 void tty_hangup(struct tty_struct *tty)
697 tty_debug_hangup(tty, "hangup\n");
698 schedule_work(&tty->hangup_work);
701 EXPORT_SYMBOL(tty_hangup);
704 * tty_vhangup - process vhangup
705 * @tty: tty to hangup
707 * The user has asked via system call for the terminal to be hung up.
708 * We do this synchronously so that when the syscall returns the process
709 * is complete. That guarantee is necessary for security reasons.
712 void tty_vhangup(struct tty_struct *tty)
714 tty_debug_hangup(tty, "vhangup\n");
715 __tty_hangup(tty, 0);
718 EXPORT_SYMBOL(tty_vhangup);
722 * tty_vhangup_self - process vhangup for own ctty
724 * Perform a vhangup on the current controlling tty
727 void tty_vhangup_self(void)
729 struct tty_struct *tty;
731 tty = get_current_tty();
739 * tty_vhangup_session - hangup session leader exit
740 * @tty: tty to hangup
742 * The session leader is exiting and hanging up its controlling terminal.
743 * Every process in the foreground process group is signalled SIGHUP.
745 * We do this synchronously so that when the syscall returns the process
746 * is complete. That guarantee is necessary for security reasons.
749 void tty_vhangup_session(struct tty_struct *tty)
751 tty_debug_hangup(tty, "session hangup\n");
752 __tty_hangup(tty, 1);
756 * tty_hung_up_p - was tty hung up
757 * @filp: file pointer of tty
759 * Return true if the tty has been subject to a vhangup or a carrier
763 int tty_hung_up_p(struct file *filp)
765 return (filp && filp->f_op == &hung_up_tty_fops);
768 EXPORT_SYMBOL(tty_hung_up_p);
771 * stop_tty - propagate flow control
774 * Perform flow control to the driver. May be called
775 * on an already stopped device and will not re-call the driver
778 * This functionality is used by both the line disciplines for
779 * halting incoming flow and by the driver. It may therefore be
780 * called from any context, may be under the tty atomic_write_lock
787 void __stop_tty(struct tty_struct *tty)
796 void stop_tty(struct tty_struct *tty)
800 spin_lock_irqsave(&tty->flow_lock, flags);
802 spin_unlock_irqrestore(&tty->flow_lock, flags);
804 EXPORT_SYMBOL(stop_tty);
807 * start_tty - propagate flow control
810 * Start a tty that has been stopped if at all possible. If this
811 * tty was previous stopped and is now being started, the driver
812 * start method is invoked and the line discipline woken.
818 void __start_tty(struct tty_struct *tty)
820 if (!tty->stopped || tty->flow_stopped)
824 tty->ops->start(tty);
828 void start_tty(struct tty_struct *tty)
832 spin_lock_irqsave(&tty->flow_lock, flags);
834 spin_unlock_irqrestore(&tty->flow_lock, flags);
836 EXPORT_SYMBOL(start_tty);
838 static void tty_update_time(struct timespec64 *time)
840 time64_t sec = ktime_get_real_seconds();
843 * We only care if the two values differ in anything other than the
844 * lower three bits (i.e every 8 seconds). If so, then we can update
845 * the time of the tty device, otherwise it could be construded as a
846 * security leak to let userspace know the exact timing of the tty.
848 if ((sec ^ time->tv_sec) & ~7)
853 * Iterate on the ldisc ->read() function until we've gotten all
854 * the data the ldisc has for us.
856 * The "cookie" is something that the ldisc read function can fill
857 * in to let us know that there is more data to be had.
859 * We promise to continue to call the ldisc until it stops returning
860 * data or clears the cookie. The cookie may be something that the
861 * ldisc maintains state for and needs to free.
863 static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
864 struct file *file, struct iov_iter *to)
868 unsigned long offset = 0;
870 size_t count = iov_iter_count(to);
875 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
876 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
881 /* Did we have an earlier error (ie -EFAULT)? */
887 * -EOVERFLOW means we didn't have enough space
888 * for a whole packet, and we shouldn't return
891 if (retval == -EOVERFLOW)
896 copied = copy_to_iter(kernel_buf, size, to);
901 * If the user copy failed, we still need to do another ->read()
902 * call if we had a cookie to let the ldisc clear up.
904 * But make sure size is zeroed.
906 if (unlikely(copied != size)) {
912 /* We always clear tty buffer in case they contained passwords */
913 memzero_explicit(kernel_buf, sizeof(kernel_buf));
914 return offset ? offset : retval;
919 * tty_read - read method for tty device files
920 * @file: pointer to tty file
922 * @count: size of user buffer
925 * Perform the read system call function on this terminal device. Checks
926 * for hung up devices before calling the line discipline method.
929 * Locks the line discipline internally while needed. Multiple
930 * read calls may be outstanding in parallel.
933 static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
936 struct file *file = iocb->ki_filp;
937 struct inode *inode = file_inode(file);
938 struct tty_struct *tty = file_tty(file);
939 struct tty_ldisc *ld;
941 if (tty_paranoia_check(tty, inode, "tty_read"))
943 if (!tty || tty_io_error(tty))
946 /* We want to wait for the line discipline to sort out in this
948 ld = tty_ldisc_ref_wait(tty);
950 return hung_up_tty_read(iocb, to);
953 i = iterate_tty_read(ld, tty, file, to);
957 tty_update_time(&inode->i_atime);
962 static void tty_write_unlock(struct tty_struct *tty)
964 mutex_unlock(&tty->atomic_write_lock);
965 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
968 static int tty_write_lock(struct tty_struct *tty, int ndelay)
970 if (!mutex_trylock(&tty->atomic_write_lock)) {
973 if (mutex_lock_interruptible(&tty->atomic_write_lock))
980 * Split writes up in sane blocksizes to avoid
981 * denial-of-service type attacks
983 static inline ssize_t do_tty_write(
984 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
985 struct tty_struct *tty,
987 struct iov_iter *from)
989 size_t count = iov_iter_count(from);
990 ssize_t ret, written = 0;
993 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
998 * We chunk up writes into a temporary buffer. This
999 * simplifies low-level drivers immensely, since they
1000 * don't have locking issues and user mode accesses.
1002 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1005 * The default chunk-size is 2kB, because the NTTY
1006 * layer has problems with bigger chunks. It will
1007 * claim to be able to handle more characters than
1010 * FIXME: This can probably go away now except that 64K chunks
1011 * are too likely to fail unless switched to vmalloc...
1014 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1019 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1020 if (tty->write_cnt < chunk) {
1021 unsigned char *buf_chunk;
1026 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1031 kfree(tty->write_buf);
1032 tty->write_cnt = chunk;
1033 tty->write_buf = buf_chunk;
1036 /* Do the write .. */
1038 size_t size = count;
1043 if (copy_from_iter(tty->write_buf, size, from) != size)
1046 ret = write(tty, file, tty->write_buf, size);
1050 /* FIXME! Have Al check this! */
1052 iov_iter_revert(from, size-ret);
1059 if (signal_pending(current))
1064 tty_update_time(&file_inode(file)->i_mtime);
1068 tty_write_unlock(tty);
1073 * tty_write_message - write a message to a certain tty, not just the console.
1074 * @tty: the destination tty_struct
1075 * @msg: the message to write
1077 * This is used for messages that need to be redirected to a specific tty.
1078 * We don't put it into the syslog queue right now maybe in the future if
1081 * We must still hold the BTM and test the CLOSING flag for the moment.
1084 void tty_write_message(struct tty_struct *tty, char *msg)
1087 mutex_lock(&tty->atomic_write_lock);
1089 if (tty->ops->write && tty->count > 0)
1090 tty->ops->write(tty, msg, strlen(msg));
1092 tty_write_unlock(tty);
1099 * tty_write - write method for tty device file
1100 * @file: tty file pointer
1101 * @buf: user data to write
1102 * @count: bytes to write
1105 * Write data to a tty device via the line discipline.
1108 * Locks the line discipline as required
1109 * Writes to the tty driver are serialized by the atomic_write_lock
1110 * and are then processed in chunks to the device. The line discipline
1111 * write method will not be invoked in parallel for each device.
1114 static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1116 struct file *file = iocb->ki_filp;
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 ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1141 struct file *p = NULL;
1143 spin_lock(&redirect_lock);
1145 p = get_file(redirect);
1146 spin_unlock(&redirect_lock);
1150 res = vfs_iocb_iter_write(p, iocb, iter);
1154 return tty_write(iocb, iter);
1158 * tty_send_xchar - send priority character
1160 * Send a high priority character to the tty even if stopped
1162 * Locking: none for xchar method, write ordering for write method.
1165 int tty_send_xchar(struct tty_struct *tty, char ch)
1167 int was_stopped = tty->stopped;
1169 if (tty->ops->send_xchar) {
1170 down_read(&tty->termios_rwsem);
1171 tty->ops->send_xchar(tty, ch);
1172 up_read(&tty->termios_rwsem);
1176 if (tty_write_lock(tty, 0) < 0)
1177 return -ERESTARTSYS;
1179 down_read(&tty->termios_rwsem);
1182 tty->ops->write(tty, &ch, 1);
1185 up_read(&tty->termios_rwsem);
1186 tty_write_unlock(tty);
1190 static char ptychar[] = "pqrstuvwxyzabcde";
1193 * pty_line_name - generate name for a pty
1194 * @driver: the tty driver in use
1195 * @index: the minor number
1196 * @p: output buffer of at least 6 bytes
1198 * Generate a name from a driver reference and write it to the output
1203 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1205 int i = index + driver->name_base;
1206 /* ->name is initialized to "ttyp", but "tty" is expected */
1207 sprintf(p, "%s%c%x",
1208 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1209 ptychar[i >> 4 & 0xf], i & 0xf);
1213 * tty_line_name - generate name for a tty
1214 * @driver: the tty driver in use
1215 * @index: the minor number
1216 * @p: output buffer of at least 7 bytes
1218 * Generate a name from a driver reference and write it to the output
1223 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1225 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1226 return sprintf(p, "%s", driver->name);
1228 return sprintf(p, "%s%d", driver->name,
1229 index + driver->name_base);
1233 * tty_driver_lookup_tty() - find an existing tty, if any
1234 * @driver: the driver for the tty
1235 * @file: file object
1236 * @idx: the minor number
1238 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1239 * driver lookup() method returns an error.
1241 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1243 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1244 struct file *file, int idx)
1246 struct tty_struct *tty;
1248 if (driver->ops->lookup)
1250 tty = ERR_PTR(-EIO);
1252 tty = driver->ops->lookup(driver, file, idx);
1254 tty = driver->ttys[idx];
1262 * tty_init_termios - helper for termios setup
1263 * @tty: the tty to set up
1265 * Initialise the termios structure for this tty. This runs under
1266 * the tty_mutex currently so we can be relaxed about ordering.
1269 void tty_init_termios(struct tty_struct *tty)
1271 struct ktermios *tp;
1272 int idx = tty->index;
1274 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1275 tty->termios = tty->driver->init_termios;
1277 /* Check for lazy saved data */
1278 tp = tty->driver->termios[idx];
1281 tty->termios.c_line = tty->driver->init_termios.c_line;
1283 tty->termios = tty->driver->init_termios;
1285 /* Compatibility until drivers always set this */
1286 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1287 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1289 EXPORT_SYMBOL_GPL(tty_init_termios);
1291 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1293 tty_init_termios(tty);
1294 tty_driver_kref_get(driver);
1296 driver->ttys[tty->index] = tty;
1299 EXPORT_SYMBOL_GPL(tty_standard_install);
1302 * tty_driver_install_tty() - install a tty entry in the driver
1303 * @driver: the driver for the tty
1306 * Install a tty object into the driver tables. The tty->index field
1307 * will be set by the time this is called. This method is responsible
1308 * for ensuring any need additional structures are allocated and
1311 * Locking: tty_mutex for now
1313 static int tty_driver_install_tty(struct tty_driver *driver,
1314 struct tty_struct *tty)
1316 return driver->ops->install ? driver->ops->install(driver, tty) :
1317 tty_standard_install(driver, tty);
1321 * tty_driver_remove_tty() - remove a tty from the driver tables
1322 * @driver: the driver for the tty
1323 * @tty: tty to remove
1325 * Remvoe a tty object from the driver tables. The tty->index field
1326 * will be set by the time this is called.
1328 * Locking: tty_mutex for now
1330 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1332 if (driver->ops->remove)
1333 driver->ops->remove(driver, tty);
1335 driver->ttys[tty->index] = NULL;
1339 * tty_reopen() - fast re-open of an open tty
1340 * @tty: the tty to open
1342 * Return 0 on success, -errno on error.
1343 * Re-opens on master ptys are not allowed and return -EIO.
1345 * Locking: Caller must hold tty_lock
1347 static int tty_reopen(struct tty_struct *tty)
1349 struct tty_driver *driver = tty->driver;
1350 struct tty_ldisc *ld;
1353 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1354 driver->subtype == PTY_TYPE_MASTER)
1360 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1363 ld = tty_ldisc_ref_wait(tty);
1365 tty_ldisc_deref(ld);
1367 retval = tty_ldisc_lock(tty, 5 * HZ);
1372 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1373 tty_ldisc_unlock(tty);
1383 * tty_init_dev - initialise a tty device
1384 * @driver: tty driver we are opening a device on
1385 * @idx: device index
1387 * Prepare a tty device. This may not be a "new" clean device but
1388 * could also be an active device. The pty drivers require special
1389 * handling because of this.
1392 * The function is called under the tty_mutex, which
1393 * protects us from the tty struct or driver itself going away.
1395 * On exit the tty device has the line discipline attached and
1396 * a reference count of 1. If a pair was created for pty/tty use
1397 * and the other was a pty master then it too has a reference count of 1.
1399 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1400 * failed open. The new code protects the open with a mutex, so it's
1401 * really quite straightforward. The mutex locking can probably be
1402 * relaxed for the (most common) case of reopening a tty.
1404 * Return: returned tty structure
1407 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1409 struct tty_struct *tty;
1413 * First time open is complex, especially for PTY devices.
1414 * This code guarantees that either everything succeeds and the
1415 * TTY is ready for operation, or else the table slots are vacated
1416 * and the allocated memory released. (Except that the termios
1420 if (!try_module_get(driver->owner))
1421 return ERR_PTR(-ENODEV);
1423 tty = alloc_tty_struct(driver, idx);
1426 goto err_module_put;
1430 retval = tty_driver_install_tty(driver, tty);
1435 tty->port = driver->ports[idx];
1437 if (WARN_RATELIMIT(!tty->port,
1438 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1439 __func__, tty->driver->name)) {
1441 goto err_release_lock;
1444 retval = tty_ldisc_lock(tty, 5 * HZ);
1446 goto err_release_lock;
1447 tty->port->itty = tty;
1450 * Structures all installed ... call the ldisc open routines.
1451 * If we fail here just call release_tty to clean up. No need
1452 * to decrement the use counts, as release_tty doesn't care.
1454 retval = tty_ldisc_setup(tty, tty->link);
1456 goto err_release_tty;
1457 tty_ldisc_unlock(tty);
1458 /* Return the tty locked so that it cannot vanish under the caller */
1463 free_tty_struct(tty);
1465 module_put(driver->owner);
1466 return ERR_PTR(retval);
1468 /* call the tty release_tty routine to clean out this slot */
1470 tty_ldisc_unlock(tty);
1471 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1475 release_tty(tty, idx);
1476 return ERR_PTR(retval);
1480 * tty_save_termios() - save tty termios data in driver table
1481 * @tty: tty whose termios data to save
1483 * Locking: Caller guarantees serialisation with tty_init_termios().
1485 void tty_save_termios(struct tty_struct *tty)
1487 struct ktermios *tp;
1488 int idx = tty->index;
1490 /* If the port is going to reset then it has no termios to save */
1491 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1494 /* Stash the termios data */
1495 tp = tty->driver->termios[idx];
1497 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1500 tty->driver->termios[idx] = tp;
1504 EXPORT_SYMBOL_GPL(tty_save_termios);
1507 * tty_flush_works - flush all works of a tty/pty pair
1508 * @tty: tty device to flush works for (or either end of a pty pair)
1510 * Sync flush all works belonging to @tty (and the 'other' tty).
1512 static void tty_flush_works(struct tty_struct *tty)
1514 flush_work(&tty->SAK_work);
1515 flush_work(&tty->hangup_work);
1517 flush_work(&tty->link->SAK_work);
1518 flush_work(&tty->link->hangup_work);
1523 * release_one_tty - release tty structure memory
1524 * @work: work of tty we are obliterating
1526 * Releases memory associated with a tty structure, and clears out the
1527 * driver table slots. This function is called when a device is no longer
1528 * in use. It also gets called when setup of a device fails.
1531 * takes the file list lock internally when working on the list
1532 * of ttys that the driver keeps.
1534 * This method gets called from a work queue so that the driver private
1535 * cleanup ops can sleep (needed for USB at least)
1537 static void release_one_tty(struct work_struct *work)
1539 struct tty_struct *tty =
1540 container_of(work, struct tty_struct, hangup_work);
1541 struct tty_driver *driver = tty->driver;
1542 struct module *owner = driver->owner;
1544 if (tty->ops->cleanup)
1545 tty->ops->cleanup(tty);
1548 tty_driver_kref_put(driver);
1551 spin_lock(&tty->files_lock);
1552 list_del_init(&tty->tty_files);
1553 spin_unlock(&tty->files_lock);
1556 put_pid(tty->session);
1557 free_tty_struct(tty);
1560 static void queue_release_one_tty(struct kref *kref)
1562 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1564 /* The hangup queue is now free so we can reuse it rather than
1565 waste a chunk of memory for each port */
1566 INIT_WORK(&tty->hangup_work, release_one_tty);
1567 schedule_work(&tty->hangup_work);
1571 * tty_kref_put - release a tty kref
1574 * Release a reference to a tty device and if need be let the kref
1575 * layer destruct the object for us
1578 void tty_kref_put(struct tty_struct *tty)
1581 kref_put(&tty->kref, queue_release_one_tty);
1583 EXPORT_SYMBOL(tty_kref_put);
1586 * release_tty - release tty structure memory
1587 * @tty: tty device release
1588 * @idx: index of the tty device release
1590 * Release both @tty and a possible linked partner (think pty pair),
1591 * and decrement the refcount of the backing module.
1595 * takes the file list lock internally when working on the list
1596 * of ttys that the driver keeps.
1599 static void release_tty(struct tty_struct *tty, int idx)
1601 /* This should always be true but check for the moment */
1602 WARN_ON(tty->index != idx);
1603 WARN_ON(!mutex_is_locked(&tty_mutex));
1604 if (tty->ops->shutdown)
1605 tty->ops->shutdown(tty);
1606 tty_save_termios(tty);
1607 tty_driver_remove_tty(tty->driver, tty);
1609 tty->port->itty = NULL;
1611 tty->link->port->itty = NULL;
1613 tty_buffer_cancel_work(tty->port);
1615 tty_buffer_cancel_work(tty->link->port);
1617 tty_kref_put(tty->link);
1622 * tty_release_checks - check a tty before real release
1623 * @tty: tty to check
1624 * @idx: index of the tty
1626 * Performs some paranoid checking before true release of the @tty.
1627 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1629 static int tty_release_checks(struct tty_struct *tty, int idx)
1631 #ifdef TTY_PARANOIA_CHECK
1632 if (idx < 0 || idx >= tty->driver->num) {
1633 tty_debug(tty, "bad idx %d\n", idx);
1637 /* not much to check for devpts */
1638 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1641 if (tty != tty->driver->ttys[idx]) {
1642 tty_debug(tty, "bad driver table[%d] = %p\n",
1643 idx, tty->driver->ttys[idx]);
1646 if (tty->driver->other) {
1647 struct tty_struct *o_tty = tty->link;
1649 if (o_tty != tty->driver->other->ttys[idx]) {
1650 tty_debug(tty, "bad other table[%d] = %p\n",
1651 idx, tty->driver->other->ttys[idx]);
1654 if (o_tty->link != tty) {
1655 tty_debug(tty, "bad link = %p\n", o_tty->link);
1664 * tty_kclose - closes tty opened by tty_kopen
1667 * Performs the final steps to release and free a tty device. It is the
1668 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1669 * flag on tty->port.
1671 void tty_kclose(struct tty_struct *tty)
1674 * Ask the line discipline code to release its structures
1676 tty_ldisc_release(tty);
1678 /* Wait for pending work before tty destruction commmences */
1679 tty_flush_works(tty);
1681 tty_debug_hangup(tty, "freeing structure\n");
1683 * The release_tty function takes care of the details of clearing
1684 * the slots and preserving the termios structure.
1686 mutex_lock(&tty_mutex);
1687 tty_port_set_kopened(tty->port, 0);
1688 release_tty(tty, tty->index);
1689 mutex_unlock(&tty_mutex);
1691 EXPORT_SYMBOL_GPL(tty_kclose);
1694 * tty_release_struct - release a tty struct
1696 * @idx: index of the tty
1698 * Performs the final steps to release and free a tty device. It is
1699 * roughly the reverse of tty_init_dev.
1701 void tty_release_struct(struct tty_struct *tty, int idx)
1704 * Ask the line discipline code to release its structures
1706 tty_ldisc_release(tty);
1708 /* Wait for pending work before tty destruction commmences */
1709 tty_flush_works(tty);
1711 tty_debug_hangup(tty, "freeing structure\n");
1713 * The release_tty function takes care of the details of clearing
1714 * the slots and preserving the termios structure.
1716 mutex_lock(&tty_mutex);
1717 release_tty(tty, idx);
1718 mutex_unlock(&tty_mutex);
1720 EXPORT_SYMBOL_GPL(tty_release_struct);
1723 * tty_release - vfs callback for close
1724 * @inode: inode of tty
1725 * @filp: file pointer for handle to tty
1727 * Called the last time each file handle is closed that references
1728 * this tty. There may however be several such references.
1731 * Takes bkl. See tty_release_dev
1733 * Even releasing the tty structures is a tricky business.. We have
1734 * to be very careful that the structures are all released at the
1735 * same time, as interrupts might otherwise get the wrong pointers.
1737 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1738 * lead to double frees or releasing memory still in use.
1741 int tty_release(struct inode *inode, struct file *filp)
1743 struct tty_struct *tty = file_tty(filp);
1744 struct tty_struct *o_tty = NULL;
1745 int do_sleep, final;
1750 if (tty_paranoia_check(tty, inode, __func__))
1754 check_tty_count(tty, __func__);
1756 __tty_fasync(-1, filp, 0);
1759 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1760 tty->driver->subtype == PTY_TYPE_MASTER)
1763 if (tty_release_checks(tty, idx)) {
1768 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1770 if (tty->ops->close)
1771 tty->ops->close(tty, filp);
1773 /* If tty is pty master, lock the slave pty (stable lock order) */
1774 tty_lock_slave(o_tty);
1777 * Sanity check: if tty->count is going to zero, there shouldn't be
1778 * any waiters on tty->read_wait or tty->write_wait. We test the
1779 * wait queues and kick everyone out _before_ actually starting to
1780 * close. This ensures that we won't block while releasing the tty
1783 * The test for the o_tty closing is necessary, since the master and
1784 * slave sides may close in any order. If the slave side closes out
1785 * first, its count will be one, since the master side holds an open.
1786 * Thus this test wouldn't be triggered at the time the slave closed,
1792 if (tty->count <= 1) {
1793 if (waitqueue_active(&tty->read_wait)) {
1794 wake_up_poll(&tty->read_wait, EPOLLIN);
1797 if (waitqueue_active(&tty->write_wait)) {
1798 wake_up_poll(&tty->write_wait, EPOLLOUT);
1802 if (o_tty && o_tty->count <= 1) {
1803 if (waitqueue_active(&o_tty->read_wait)) {
1804 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1807 if (waitqueue_active(&o_tty->write_wait)) {
1808 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1817 tty_warn(tty, "read/write wait queue active!\n");
1819 schedule_timeout_killable(timeout);
1820 if (timeout < 120 * HZ)
1821 timeout = 2 * timeout + 1;
1823 timeout = MAX_SCHEDULE_TIMEOUT;
1827 if (--o_tty->count < 0) {
1828 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1832 if (--tty->count < 0) {
1833 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1838 * We've decremented tty->count, so we need to remove this file
1839 * descriptor off the tty->tty_files list; this serves two
1841 * - check_tty_count sees the correct number of file descriptors
1842 * associated with this tty.
1843 * - do_tty_hangup no longer sees this file descriptor as
1844 * something that needs to be handled for hangups.
1849 * Perform some housekeeping before deciding whether to return.
1851 * If _either_ side is closing, make sure there aren't any
1852 * processes that still think tty or o_tty is their controlling
1856 read_lock(&tasklist_lock);
1857 session_clear_tty(tty->session);
1859 session_clear_tty(o_tty->session);
1860 read_unlock(&tasklist_lock);
1863 /* check whether both sides are closing ... */
1864 final = !tty->count && !(o_tty && o_tty->count);
1866 tty_unlock_slave(o_tty);
1869 /* At this point, the tty->count == 0 should ensure a dead tty
1870 cannot be re-opened by a racing opener */
1875 tty_debug_hangup(tty, "final close\n");
1877 tty_release_struct(tty, idx);
1882 * tty_open_current_tty - get locked tty of current task
1883 * @device: device number
1884 * @filp: file pointer to tty
1885 * @return: locked tty of the current task iff @device is /dev/tty
1887 * Performs a re-open of the current task's controlling tty.
1889 * We cannot return driver and index like for the other nodes because
1890 * devpts will not work then. It expects inodes to be from devpts FS.
1892 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1894 struct tty_struct *tty;
1897 if (device != MKDEV(TTYAUX_MAJOR, 0))
1900 tty = get_current_tty();
1902 return ERR_PTR(-ENXIO);
1904 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1907 tty_kref_put(tty); /* safe to drop the kref now */
1909 retval = tty_reopen(tty);
1912 tty = ERR_PTR(retval);
1918 * tty_lookup_driver - lookup a tty driver for a given device file
1919 * @device: device number
1920 * @filp: file pointer to tty
1921 * @index: index for the device in the @return driver
1922 * @return: driver for this inode (with increased refcount)
1924 * If @return is not erroneous, the caller is responsible to decrement the
1925 * refcount by tty_driver_kref_put.
1927 * Locking: tty_mutex protects get_tty_driver
1929 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1932 struct tty_driver *driver = NULL;
1936 case MKDEV(TTY_MAJOR, 0): {
1937 extern struct tty_driver *console_driver;
1938 driver = tty_driver_kref_get(console_driver);
1939 *index = fg_console;
1943 case MKDEV(TTYAUX_MAJOR, 1): {
1944 struct tty_driver *console_driver = console_device(index);
1945 if (console_driver) {
1946 driver = tty_driver_kref_get(console_driver);
1947 if (driver && filp) {
1948 /* Don't let /dev/console block */
1949 filp->f_flags |= O_NONBLOCK;
1954 tty_driver_kref_put(driver);
1955 return ERR_PTR(-ENODEV);
1958 driver = get_tty_driver(device, index);
1960 return ERR_PTR(-ENODEV);
1966 static struct tty_struct *tty_kopen(dev_t device, int shared)
1968 struct tty_struct *tty;
1969 struct tty_driver *driver;
1972 mutex_lock(&tty_mutex);
1973 driver = tty_lookup_driver(device, NULL, &index);
1974 if (IS_ERR(driver)) {
1975 mutex_unlock(&tty_mutex);
1976 return ERR_CAST(driver);
1979 /* check whether we're reopening an existing tty */
1980 tty = tty_driver_lookup_tty(driver, NULL, index);
1981 if (IS_ERR(tty) || shared)
1985 /* drop kref from tty_driver_lookup_tty() */
1987 tty = ERR_PTR(-EBUSY);
1988 } else { /* tty_init_dev returns tty with the tty_lock held */
1989 tty = tty_init_dev(driver, index);
1992 tty_port_set_kopened(tty->port, 1);
1995 mutex_unlock(&tty_mutex);
1996 tty_driver_kref_put(driver);
2001 * tty_kopen_exclusive - open a tty device for kernel
2002 * @device: dev_t of device to open
2004 * Opens tty exclusively for kernel. Performs the driver lookup,
2005 * makes sure it's not already opened and performs the first-time
2006 * tty initialization.
2008 * Returns the locked initialized &tty_struct
2010 * Claims the global tty_mutex to serialize:
2011 * - concurrent first-time tty initialization
2012 * - concurrent tty driver removal w/ lookup
2013 * - concurrent tty removal from driver table
2015 struct tty_struct *tty_kopen_exclusive(dev_t device)
2017 return tty_kopen(device, 0);
2019 EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2022 * tty_kopen_shared - open a tty device for shared in-kernel use
2023 * @device: dev_t of device to open
2025 * Opens an already existing tty for in-kernel use. Compared to
2026 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2028 * Locking is identical to tty_kopen() above.
2030 struct tty_struct *tty_kopen_shared(dev_t device)
2032 return tty_kopen(device, 1);
2034 EXPORT_SYMBOL_GPL(tty_kopen_shared);
2037 * tty_open_by_driver - open a tty device
2038 * @device: dev_t of device to open
2039 * @filp: file pointer to tty
2041 * Performs the driver lookup, checks for a reopen, or otherwise
2042 * performs the first-time tty initialization.
2044 * Returns the locked initialized or re-opened &tty_struct
2046 * Claims the global tty_mutex to serialize:
2047 * - concurrent first-time tty initialization
2048 * - concurrent tty driver removal w/ lookup
2049 * - concurrent tty removal from driver table
2051 static struct tty_struct *tty_open_by_driver(dev_t device,
2054 struct tty_struct *tty;
2055 struct tty_driver *driver = NULL;
2059 mutex_lock(&tty_mutex);
2060 driver = tty_lookup_driver(device, filp, &index);
2061 if (IS_ERR(driver)) {
2062 mutex_unlock(&tty_mutex);
2063 return ERR_CAST(driver);
2066 /* check whether we're reopening an existing tty */
2067 tty = tty_driver_lookup_tty(driver, filp, index);
2069 mutex_unlock(&tty_mutex);
2074 if (tty_port_kopened(tty->port)) {
2076 mutex_unlock(&tty_mutex);
2077 tty = ERR_PTR(-EBUSY);
2080 mutex_unlock(&tty_mutex);
2081 retval = tty_lock_interruptible(tty);
2082 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2084 if (retval == -EINTR)
2085 retval = -ERESTARTSYS;
2086 tty = ERR_PTR(retval);
2089 retval = tty_reopen(tty);
2092 tty = ERR_PTR(retval);
2094 } else { /* Returns with the tty_lock held for now */
2095 tty = tty_init_dev(driver, index);
2096 mutex_unlock(&tty_mutex);
2099 tty_driver_kref_put(driver);
2104 * tty_open - open a tty device
2105 * @inode: inode of device file
2106 * @filp: file pointer to tty
2108 * tty_open and tty_release keep up the tty count that contains the
2109 * number of opens done on a tty. We cannot use the inode-count, as
2110 * different inodes might point to the same tty.
2112 * Open-counting is needed for pty masters, as well as for keeping
2113 * track of serial lines: DTR is dropped when the last close happens.
2114 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2116 * The termios state of a pty is reset on first open so that
2117 * settings don't persist across reuse.
2119 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2120 * tty->count should protect the rest.
2121 * ->siglock protects ->signal/->sighand
2123 * Note: the tty_unlock/lock cases without a ref are only safe due to
2127 static int tty_open(struct inode *inode, struct file *filp)
2129 struct tty_struct *tty;
2131 dev_t device = inode->i_rdev;
2132 unsigned saved_flags = filp->f_flags;
2134 nonseekable_open(inode, filp);
2137 retval = tty_alloc_file(filp);
2141 tty = tty_open_current_tty(device, filp);
2143 tty = tty_open_by_driver(device, filp);
2146 tty_free_file(filp);
2147 retval = PTR_ERR(tty);
2148 if (retval != -EAGAIN || signal_pending(current))
2154 tty_add_file(tty, filp);
2156 check_tty_count(tty, __func__);
2157 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2160 retval = tty->ops->open(tty, filp);
2163 filp->f_flags = saved_flags;
2166 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2168 tty_unlock(tty); /* need to call tty_release without BTM */
2169 tty_release(inode, filp);
2170 if (retval != -ERESTARTSYS)
2173 if (signal_pending(current))
2178 * Need to reset f_op in case a hangup happened.
2180 if (tty_hung_up_p(filp))
2181 filp->f_op = &tty_fops;
2184 clear_bit(TTY_HUPPED, &tty->flags);
2186 noctty = (filp->f_flags & O_NOCTTY) ||
2187 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2188 device == MKDEV(TTYAUX_MAJOR, 1) ||
2189 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2190 tty->driver->subtype == PTY_TYPE_MASTER);
2192 tty_open_proc_set_tty(filp, tty);
2200 * tty_poll - check tty status
2201 * @filp: file being polled
2202 * @wait: poll wait structures to update
2204 * Call the line discipline polling method to obtain the poll
2205 * status of the device.
2207 * Locking: locks called line discipline but ldisc poll method
2208 * may be re-entered freely by other callers.
2211 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2213 struct tty_struct *tty = file_tty(filp);
2214 struct tty_ldisc *ld;
2217 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2220 ld = tty_ldisc_ref_wait(tty);
2222 return hung_up_tty_poll(filp, wait);
2224 ret = ld->ops->poll(tty, filp, wait);
2225 tty_ldisc_deref(ld);
2229 static int __tty_fasync(int fd, struct file *filp, int on)
2231 struct tty_struct *tty = file_tty(filp);
2232 unsigned long flags;
2235 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2238 retval = fasync_helper(fd, filp, on, &tty->fasync);
2246 spin_lock_irqsave(&tty->ctrl_lock, flags);
2249 type = PIDTYPE_PGID;
2251 pid = task_pid(current);
2252 type = PIDTYPE_TGID;
2255 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2256 __f_setown(filp, pid, type, 0);
2264 static int tty_fasync(int fd, struct file *filp, int on)
2266 struct tty_struct *tty = file_tty(filp);
2267 int retval = -ENOTTY;
2270 if (!tty_hung_up_p(filp))
2271 retval = __tty_fasync(fd, filp, on);
2278 * tiocsti - fake input character
2279 * @tty: tty to fake input into
2280 * @p: pointer to character
2282 * Fake input to a tty device. Does the necessary locking and
2285 * FIXME: does not honour flow control ??
2288 * Called functions take tty_ldiscs_lock
2289 * current->signal->tty check is safe without locks
2291 * FIXME: may race normal receive processing
2294 static int tiocsti(struct tty_struct *tty, char __user *p)
2297 struct tty_ldisc *ld;
2299 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2301 if (get_user(ch, p))
2303 tty_audit_tiocsti(tty, ch);
2304 ld = tty_ldisc_ref_wait(tty);
2307 if (ld->ops->receive_buf)
2308 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2309 tty_ldisc_deref(ld);
2314 * tiocgwinsz - implement window query ioctl
2316 * @arg: user buffer for result
2318 * Copies the kernel idea of the window size into the user buffer.
2320 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2324 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2328 mutex_lock(&tty->winsize_mutex);
2329 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2330 mutex_unlock(&tty->winsize_mutex);
2332 return err ? -EFAULT: 0;
2336 * tty_do_resize - resize event
2337 * @tty: tty being resized
2338 * @ws: new dimensions
2340 * Update the termios variables and send the necessary signals to
2341 * peform a terminal resize correctly
2344 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2349 mutex_lock(&tty->winsize_mutex);
2350 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2353 /* Signal the foreground process group */
2354 pgrp = tty_get_pgrp(tty);
2356 kill_pgrp(pgrp, SIGWINCH, 1);
2361 mutex_unlock(&tty->winsize_mutex);
2364 EXPORT_SYMBOL(tty_do_resize);
2367 * tiocswinsz - implement window size set ioctl
2368 * @tty: tty side of tty
2369 * @arg: user buffer for result
2371 * Copies the user idea of the window size to the kernel. Traditionally
2372 * this is just advisory information but for the Linux console it
2373 * actually has driver level meaning and triggers a VC resize.
2376 * Driver dependent. The default do_resize method takes the
2377 * tty termios mutex and ctrl_lock. The console takes its own lock
2378 * then calls into the default method.
2381 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2383 struct winsize tmp_ws;
2384 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2387 if (tty->ops->resize)
2388 return tty->ops->resize(tty, &tmp_ws);
2390 return tty_do_resize(tty, &tmp_ws);
2394 * tioccons - allow admin to move logical console
2395 * @file: the file to become console
2397 * Allow the administrator to move the redirected console device
2399 * Locking: uses redirect_lock to guard the redirect information
2402 static int tioccons(struct file *file)
2404 if (!capable(CAP_SYS_ADMIN))
2406 if (file->f_op->write_iter == redirected_tty_write) {
2408 spin_lock(&redirect_lock);
2411 spin_unlock(&redirect_lock);
2416 spin_lock(&redirect_lock);
2418 spin_unlock(&redirect_lock);
2421 redirect = get_file(file);
2422 spin_unlock(&redirect_lock);
2427 * tiocsetd - set line discipline
2429 * @p: pointer to user data
2431 * Set the line discipline according to user request.
2433 * Locking: see tty_set_ldisc, this function is just a helper
2436 static int tiocsetd(struct tty_struct *tty, int __user *p)
2441 if (get_user(disc, p))
2444 ret = tty_set_ldisc(tty, disc);
2450 * tiocgetd - get line discipline
2452 * @p: pointer to user data
2454 * Retrieves the line discipline id directly from the ldisc.
2456 * Locking: waits for ldisc reference (in case the line discipline
2457 * is changing or the tty is being hungup)
2460 static int tiocgetd(struct tty_struct *tty, int __user *p)
2462 struct tty_ldisc *ld;
2465 ld = tty_ldisc_ref_wait(tty);
2468 ret = put_user(ld->ops->num, p);
2469 tty_ldisc_deref(ld);
2474 * send_break - performed time break
2475 * @tty: device to break on
2476 * @duration: timeout in mS
2478 * Perform a timed break on hardware that lacks its own driver level
2479 * timed break functionality.
2482 * atomic_write_lock serializes
2486 static int send_break(struct tty_struct *tty, unsigned int duration)
2490 if (tty->ops->break_ctl == NULL)
2493 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2494 retval = tty->ops->break_ctl(tty, duration);
2496 /* Do the work ourselves */
2497 if (tty_write_lock(tty, 0) < 0)
2499 retval = tty->ops->break_ctl(tty, -1);
2502 if (!signal_pending(current))
2503 msleep_interruptible(duration);
2504 retval = tty->ops->break_ctl(tty, 0);
2506 tty_write_unlock(tty);
2507 if (signal_pending(current))
2514 * tty_tiocmget - get modem status
2516 * @p: pointer to result
2518 * Obtain the modem status bits from the tty driver if the feature
2519 * is supported. Return -EINVAL if it is not available.
2521 * Locking: none (up to the driver)
2524 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2526 int retval = -EINVAL;
2528 if (tty->ops->tiocmget) {
2529 retval = tty->ops->tiocmget(tty);
2532 retval = put_user(retval, p);
2538 * tty_tiocmset - set modem status
2540 * @cmd: command - clear bits, set bits or set all
2541 * @p: pointer to desired bits
2543 * Set the modem status bits from the tty driver if the feature
2544 * is supported. Return -EINVAL if it is not available.
2546 * Locking: none (up to the driver)
2549 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2553 unsigned int set, clear, val;
2555 if (tty->ops->tiocmset == NULL)
2558 retval = get_user(val, p);
2574 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2575 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2576 return tty->ops->tiocmset(tty, set, clear);
2580 * tty_get_icount - get tty statistics
2582 * @icount: output parameter
2584 * Gets a copy of the tty's icount statistics.
2586 * Locking: none (up to the driver)
2588 int tty_get_icount(struct tty_struct *tty,
2589 struct serial_icounter_struct *icount)
2591 memset(icount, 0, sizeof(*icount));
2593 if (tty->ops->get_icount)
2594 return tty->ops->get_icount(tty, icount);
2598 EXPORT_SYMBOL_GPL(tty_get_icount);
2600 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2602 struct serial_icounter_struct icount;
2605 retval = tty_get_icount(tty, &icount);
2609 if (copy_to_user(arg, &icount, sizeof(icount)))
2614 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2616 static DEFINE_RATELIMIT_STATE(depr_flags,
2617 DEFAULT_RATELIMIT_INTERVAL,
2618 DEFAULT_RATELIMIT_BURST);
2619 char comm[TASK_COMM_LEN];
2620 struct serial_struct v;
2623 if (copy_from_user(&v, ss, sizeof(*ss)))
2626 flags = v.flags & ASYNC_DEPRECATED;
2628 if (flags && __ratelimit(&depr_flags))
2629 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2630 __func__, get_task_comm(comm, current), flags);
2631 if (!tty->ops->set_serial)
2633 return tty->ops->set_serial(tty, &v);
2636 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2638 struct serial_struct v;
2641 memset(&v, 0, sizeof(v));
2642 if (!tty->ops->get_serial)
2644 err = tty->ops->get_serial(tty, &v);
2645 if (!err && copy_to_user(ss, &v, sizeof(v)))
2651 * if pty, return the slave side (real_tty)
2652 * otherwise, return self
2654 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2656 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2657 tty->driver->subtype == PTY_TYPE_MASTER)
2663 * Split this up, as gcc can choke on it otherwise..
2665 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2667 struct tty_struct *tty = file_tty(file);
2668 struct tty_struct *real_tty;
2669 void __user *p = (void __user *)arg;
2671 struct tty_ldisc *ld;
2673 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2676 real_tty = tty_pair_get_tty(tty);
2679 * Factor out some common prep work
2687 retval = tty_check_change(tty);
2690 if (cmd != TIOCCBRK) {
2691 tty_wait_until_sent(tty, 0);
2692 if (signal_pending(current))
2703 return tiocsti(tty, p);
2705 return tiocgwinsz(real_tty, p);
2707 return tiocswinsz(real_tty, p);
2709 return real_tty != tty ? -EINVAL : tioccons(file);
2711 set_bit(TTY_EXCLUSIVE, &tty->flags);
2714 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2718 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2719 return put_user(excl, (int __user *)p);
2722 return tiocgetd(tty, p);
2724 return tiocsetd(tty, p);
2726 if (!capable(CAP_SYS_ADMIN))
2732 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2733 return put_user(ret, (unsigned int __user *)p);
2738 case TIOCSBRK: /* Turn break on, unconditionally */
2739 if (tty->ops->break_ctl)
2740 return tty->ops->break_ctl(tty, -1);
2742 case TIOCCBRK: /* Turn break off, unconditionally */
2743 if (tty->ops->break_ctl)
2744 return tty->ops->break_ctl(tty, 0);
2746 case TCSBRK: /* SVID version: non-zero arg --> no break */
2747 /* non-zero arg means wait for all output data
2748 * to be sent (performed above) but don't send break.
2749 * This is used by the tcdrain() termios function.
2752 return send_break(tty, 250);
2754 case TCSBRKP: /* support for POSIX tcsendbreak() */
2755 return send_break(tty, arg ? arg*100 : 250);
2758 return tty_tiocmget(tty, p);
2762 return tty_tiocmset(tty, cmd, p);
2764 return tty_tiocgicount(tty, p);
2769 /* flush tty buffer and allow ldisc to process ioctl */
2770 tty_buffer_flush(tty, NULL);
2775 return tty_tiocsserial(tty, p);
2777 return tty_tiocgserial(tty, p);
2779 /* Special because the struct file is needed */
2780 return ptm_open_peer(file, tty, (int)arg);
2782 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2783 if (retval != -ENOIOCTLCMD)
2786 if (tty->ops->ioctl) {
2787 retval = tty->ops->ioctl(tty, cmd, arg);
2788 if (retval != -ENOIOCTLCMD)
2791 ld = tty_ldisc_ref_wait(tty);
2793 return hung_up_tty_ioctl(file, cmd, arg);
2795 if (ld->ops->ioctl) {
2796 retval = ld->ops->ioctl(tty, file, cmd, arg);
2797 if (retval == -ENOIOCTLCMD)
2800 tty_ldisc_deref(ld);
2804 #ifdef CONFIG_COMPAT
2806 struct serial_struct32 {
2812 compat_int_t xmit_fifo_size;
2813 compat_int_t custom_divisor;
2814 compat_int_t baud_base;
2815 unsigned short close_delay;
2819 unsigned short closing_wait; /* time to wait before closing */
2820 unsigned short closing_wait2; /* no longer used... */
2821 compat_uint_t iomem_base;
2822 unsigned short iomem_reg_shift;
2823 unsigned int port_high;
2824 /* compat_ulong_t iomap_base FIXME */
2825 compat_int_t reserved;
2828 static int compat_tty_tiocsserial(struct tty_struct *tty,
2829 struct serial_struct32 __user *ss)
2831 static DEFINE_RATELIMIT_STATE(depr_flags,
2832 DEFAULT_RATELIMIT_INTERVAL,
2833 DEFAULT_RATELIMIT_BURST);
2834 char comm[TASK_COMM_LEN];
2835 struct serial_struct32 v32;
2836 struct serial_struct v;
2839 if (copy_from_user(&v32, ss, sizeof(*ss)))
2842 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2843 v.iomem_base = compat_ptr(v32.iomem_base);
2844 v.iomem_reg_shift = v32.iomem_reg_shift;
2845 v.port_high = v32.port_high;
2848 flags = v.flags & ASYNC_DEPRECATED;
2850 if (flags && __ratelimit(&depr_flags))
2851 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2852 __func__, get_task_comm(comm, current), flags);
2853 if (!tty->ops->set_serial)
2855 return tty->ops->set_serial(tty, &v);
2858 static int compat_tty_tiocgserial(struct tty_struct *tty,
2859 struct serial_struct32 __user *ss)
2861 struct serial_struct32 v32;
2862 struct serial_struct v;
2865 memset(&v, 0, sizeof(v));
2866 memset(&v32, 0, sizeof(v32));
2868 if (!tty->ops->get_serial)
2870 err = tty->ops->get_serial(tty, &v);
2872 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2873 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2874 0xfffffff : ptr_to_compat(v.iomem_base);
2875 v32.iomem_reg_shift = v.iomem_reg_shift;
2876 v32.port_high = v.port_high;
2877 if (copy_to_user(ss, &v32, sizeof(v32)))
2882 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2885 struct tty_struct *tty = file_tty(file);
2886 struct tty_ldisc *ld;
2887 int retval = -ENOIOCTLCMD;
2936 case TIOCGLCKTRMIOS:
2937 case TIOCSLCKTRMIOS:
2949 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2965 return tty_ioctl(file, cmd, arg);
2968 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2973 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2975 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2977 if (tty->ops->compat_ioctl) {
2978 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2979 if (retval != -ENOIOCTLCMD)
2983 ld = tty_ldisc_ref_wait(tty);
2985 return hung_up_tty_compat_ioctl(file, cmd, arg);
2986 if (ld->ops->compat_ioctl)
2987 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2988 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2989 retval = ld->ops->ioctl(tty, file,
2990 (unsigned long)compat_ptr(cmd), arg);
2991 tty_ldisc_deref(ld);
2997 static int this_tty(const void *t, struct file *file, unsigned fd)
2999 if (likely(file->f_op->read_iter != tty_read))
3001 return file_tty(file) != t ? 0 : fd + 1;
3005 * This implements the "Secure Attention Key" --- the idea is to
3006 * prevent trojan horses by killing all processes associated with this
3007 * tty when the user hits the "Secure Attention Key". Required for
3008 * super-paranoid applications --- see the Orange Book for more details.
3010 * This code could be nicer; ideally it should send a HUP, wait a few
3011 * seconds, then send a INT, and then a KILL signal. But you then
3012 * have to coordinate with the init process, since all processes associated
3013 * with the current tty must be dead before the new getty is allowed
3016 * Now, if it would be correct ;-/ The current code has a nasty hole -
3017 * it doesn't catch files in flight. We may send the descriptor to ourselves
3018 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3020 * Nasty bug: do_SAK is being called in interrupt context. This can
3021 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3023 void __do_SAK(struct tty_struct *tty)
3028 struct task_struct *g, *p;
3029 struct pid *session;
3031 unsigned long flags;
3036 spin_lock_irqsave(&tty->ctrl_lock, flags);
3037 session = get_pid(tty->session);
3038 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3040 tty_ldisc_flush(tty);
3042 tty_driver_flush_buffer(tty);
3044 read_lock(&tasklist_lock);
3045 /* Kill the entire session */
3046 do_each_pid_task(session, PIDTYPE_SID, p) {
3047 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3048 task_pid_nr(p), p->comm);
3049 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3050 } while_each_pid_task(session, PIDTYPE_SID, p);
3052 /* Now kill any processes that happen to have the tty open */
3053 do_each_thread(g, p) {
3054 if (p->signal->tty == tty) {
3055 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3056 task_pid_nr(p), p->comm);
3057 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3061 i = iterate_fd(p->files, 0, this_tty, tty);
3063 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3064 task_pid_nr(p), p->comm, i - 1);
3065 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3068 } while_each_thread(g, p);
3069 read_unlock(&tasklist_lock);
3074 static void do_SAK_work(struct work_struct *work)
3076 struct tty_struct *tty =
3077 container_of(work, struct tty_struct, SAK_work);
3082 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3083 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3084 * the values which we write to it will be identical to the values which it
3085 * already has. --akpm
3087 void do_SAK(struct tty_struct *tty)
3091 schedule_work(&tty->SAK_work);
3094 EXPORT_SYMBOL(do_SAK);
3096 /* Must put_device() after it's unused! */
3097 static struct device *tty_get_device(struct tty_struct *tty)
3099 dev_t devt = tty_devnum(tty);
3100 return class_find_device_by_devt(tty_class, devt);
3107 * This subroutine allocates and initializes a tty structure.
3109 * Locking: none - tty in question is not exposed at this point
3112 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3114 struct tty_struct *tty;
3116 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3120 kref_init(&tty->kref);
3121 tty->magic = TTY_MAGIC;
3122 if (tty_ldisc_init(tty)) {
3126 tty->session = NULL;
3128 mutex_init(&tty->legacy_mutex);
3129 mutex_init(&tty->throttle_mutex);
3130 init_rwsem(&tty->termios_rwsem);
3131 mutex_init(&tty->winsize_mutex);
3132 init_ldsem(&tty->ldisc_sem);
3133 init_waitqueue_head(&tty->write_wait);
3134 init_waitqueue_head(&tty->read_wait);
3135 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3136 mutex_init(&tty->atomic_write_lock);
3137 spin_lock_init(&tty->ctrl_lock);
3138 spin_lock_init(&tty->flow_lock);
3139 spin_lock_init(&tty->files_lock);
3140 INIT_LIST_HEAD(&tty->tty_files);
3141 INIT_WORK(&tty->SAK_work, do_SAK_work);
3143 tty->driver = driver;
3144 tty->ops = driver->ops;
3146 tty_line_name(driver, idx, tty->name);
3147 tty->dev = tty_get_device(tty);
3153 * tty_put_char - write one character to a tty
3157 * Write one byte to the tty using the provided put_char method
3158 * if present. Returns the number of characters successfully output.
3160 * Note: the specific put_char operation in the driver layer may go
3161 * away soon. Don't call it directly, use this method
3164 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3166 if (tty->ops->put_char)
3167 return tty->ops->put_char(tty, ch);
3168 return tty->ops->write(tty, &ch, 1);
3170 EXPORT_SYMBOL_GPL(tty_put_char);
3172 struct class *tty_class;
3174 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3175 unsigned int index, unsigned int count)
3179 /* init here, since reused cdevs cause crashes */
3180 driver->cdevs[index] = cdev_alloc();
3181 if (!driver->cdevs[index])
3183 driver->cdevs[index]->ops = &tty_fops;
3184 driver->cdevs[index]->owner = driver->owner;
3185 err = cdev_add(driver->cdevs[index], dev, count);
3187 kobject_put(&driver->cdevs[index]->kobj);
3192 * tty_register_device - register a tty device
3193 * @driver: the tty driver that describes the tty device
3194 * @index: the index in the tty driver for this tty device
3195 * @device: a struct device that is associated with this tty device.
3196 * This field is optional, if there is no known struct device
3197 * for this tty device it can be set to NULL safely.
3199 * Returns a pointer to the struct device for this tty device
3200 * (or ERR_PTR(-EFOO) on error).
3202 * This call is required to be made to register an individual tty device
3203 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3204 * that bit is not set, this function should not be called by a tty
3210 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3211 struct device *device)
3213 return tty_register_device_attr(driver, index, device, NULL, NULL);
3215 EXPORT_SYMBOL(tty_register_device);
3217 static void tty_device_create_release(struct device *dev)
3219 dev_dbg(dev, "releasing...\n");
3224 * tty_register_device_attr - register a tty device
3225 * @driver: the tty driver that describes the tty device
3226 * @index: the index in the tty driver for this tty device
3227 * @device: a struct device that is associated with this tty device.
3228 * This field is optional, if there is no known struct device
3229 * for this tty device it can be set to NULL safely.
3230 * @drvdata: Driver data to be set to device.
3231 * @attr_grp: Attribute group to be set on device.
3233 * Returns a pointer to the struct device for this tty device
3234 * (or ERR_PTR(-EFOO) on error).
3236 * This call is required to be made to register an individual tty device
3237 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3238 * that bit is not set, this function should not be called by a tty
3243 struct device *tty_register_device_attr(struct tty_driver *driver,
3244 unsigned index, struct device *device,
3246 const struct attribute_group **attr_grp)
3249 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3250 struct ktermios *tp;
3254 if (index >= driver->num) {
3255 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3256 driver->name, index);
3257 return ERR_PTR(-EINVAL);
3260 if (driver->type == TTY_DRIVER_TYPE_PTY)
3261 pty_line_name(driver, index, name);
3263 tty_line_name(driver, index, name);
3265 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3267 return ERR_PTR(-ENOMEM);
3270 dev->class = tty_class;
3271 dev->parent = device;
3272 dev->release = tty_device_create_release;
3273 dev_set_name(dev, "%s", name);
3274 dev->groups = attr_grp;
3275 dev_set_drvdata(dev, drvdata);
3277 dev_set_uevent_suppress(dev, 1);
3279 retval = device_register(dev);
3283 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3285 * Free any saved termios data so that the termios state is
3286 * reset when reusing a minor number.
3288 tp = driver->termios[index];
3290 driver->termios[index] = NULL;
3294 retval = tty_cdev_add(driver, devt, index, 1);
3299 dev_set_uevent_suppress(dev, 0);
3300 kobject_uevent(&dev->kobj, KOBJ_ADD);
3309 return ERR_PTR(retval);
3311 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3314 * tty_unregister_device - unregister a tty device
3315 * @driver: the tty driver that describes the tty device
3316 * @index: the index in the tty driver for this tty device
3318 * If a tty device is registered with a call to tty_register_device() then
3319 * this function must be called when the tty device is gone.
3324 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3326 device_destroy(tty_class,
3327 MKDEV(driver->major, driver->minor_start) + index);
3328 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3329 cdev_del(driver->cdevs[index]);
3330 driver->cdevs[index] = NULL;
3333 EXPORT_SYMBOL(tty_unregister_device);
3336 * __tty_alloc_driver -- allocate tty driver
3337 * @lines: count of lines this driver can handle at most
3338 * @owner: module which is responsible for this driver
3339 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3341 * This should not be called directly, some of the provided macros should be
3342 * used instead. Use IS_ERR and friends on @retval.
3344 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3345 unsigned long flags)
3347 struct tty_driver *driver;
3348 unsigned int cdevs = 1;
3351 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3352 return ERR_PTR(-EINVAL);
3354 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3356 return ERR_PTR(-ENOMEM);
3358 kref_init(&driver->kref);
3359 driver->magic = TTY_DRIVER_MAGIC;
3360 driver->num = lines;
3361 driver->owner = owner;
3362 driver->flags = flags;
3364 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3365 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3367 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3369 if (!driver->ttys || !driver->termios) {
3375 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3376 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3378 if (!driver->ports) {
3385 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3386 if (!driver->cdevs) {
3393 kfree(driver->ports);
3394 kfree(driver->ttys);
3395 kfree(driver->termios);
3396 kfree(driver->cdevs);
3398 return ERR_PTR(err);
3400 EXPORT_SYMBOL(__tty_alloc_driver);
3402 static void destruct_tty_driver(struct kref *kref)
3404 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3406 struct ktermios *tp;
3408 if (driver->flags & TTY_DRIVER_INSTALLED) {
3409 for (i = 0; i < driver->num; i++) {
3410 tp = driver->termios[i];
3412 driver->termios[i] = NULL;
3415 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3416 tty_unregister_device(driver, i);
3418 proc_tty_unregister_driver(driver);
3419 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3420 cdev_del(driver->cdevs[0]);
3422 kfree(driver->cdevs);
3423 kfree(driver->ports);
3424 kfree(driver->termios);
3425 kfree(driver->ttys);
3429 void tty_driver_kref_put(struct tty_driver *driver)
3431 kref_put(&driver->kref, destruct_tty_driver);
3433 EXPORT_SYMBOL(tty_driver_kref_put);
3435 void tty_set_operations(struct tty_driver *driver,
3436 const struct tty_operations *op)
3440 EXPORT_SYMBOL(tty_set_operations);
3442 void put_tty_driver(struct tty_driver *d)
3444 tty_driver_kref_put(d);
3446 EXPORT_SYMBOL(put_tty_driver);
3449 * Called by a tty driver to register itself.
3451 int tty_register_driver(struct tty_driver *driver)
3458 if (!driver->major) {
3459 error = alloc_chrdev_region(&dev, driver->minor_start,
3460 driver->num, driver->name);
3462 driver->major = MAJOR(dev);
3463 driver->minor_start = MINOR(dev);
3466 dev = MKDEV(driver->major, driver->minor_start);
3467 error = register_chrdev_region(dev, driver->num, driver->name);
3472 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3473 error = tty_cdev_add(driver, dev, 0, driver->num);
3475 goto err_unreg_char;
3478 mutex_lock(&tty_mutex);
3479 list_add(&driver->tty_drivers, &tty_drivers);
3480 mutex_unlock(&tty_mutex);
3482 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3483 for (i = 0; i < driver->num; i++) {
3484 d = tty_register_device(driver, i, NULL);
3487 goto err_unreg_devs;
3491 proc_tty_register_driver(driver);
3492 driver->flags |= TTY_DRIVER_INSTALLED;
3496 for (i--; i >= 0; i--)
3497 tty_unregister_device(driver, i);
3499 mutex_lock(&tty_mutex);
3500 list_del(&driver->tty_drivers);
3501 mutex_unlock(&tty_mutex);
3504 unregister_chrdev_region(dev, driver->num);
3508 EXPORT_SYMBOL(tty_register_driver);
3511 * Called by a tty driver to unregister itself.
3513 int tty_unregister_driver(struct tty_driver *driver)
3517 if (driver->refcount)
3520 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3522 mutex_lock(&tty_mutex);
3523 list_del(&driver->tty_drivers);
3524 mutex_unlock(&tty_mutex);
3528 EXPORT_SYMBOL(tty_unregister_driver);
3530 dev_t tty_devnum(struct tty_struct *tty)
3532 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3534 EXPORT_SYMBOL(tty_devnum);
3536 void tty_default_fops(struct file_operations *fops)
3541 static char *tty_devnode(struct device *dev, umode_t *mode)
3545 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3546 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3551 static int __init tty_class_init(void)
3553 tty_class = class_create(THIS_MODULE, "tty");
3554 if (IS_ERR(tty_class))
3555 return PTR_ERR(tty_class);
3556 tty_class->devnode = tty_devnode;
3560 postcore_initcall(tty_class_init);
3562 /* 3/2004 jmc: why do these devices exist? */
3563 static struct cdev tty_cdev, console_cdev;
3565 static ssize_t show_cons_active(struct device *dev,
3566 struct device_attribute *attr, char *buf)
3568 struct console *cs[16];
3574 for_each_console(c) {
3579 if ((c->flags & CON_ENABLED) == 0)
3582 if (i >= ARRAY_SIZE(cs))
3586 int index = cs[i]->index;
3587 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3589 /* don't resolve tty0 as some programs depend on it */
3590 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3591 count += tty_line_name(drv, index, buf + count);
3593 count += sprintf(buf + count, "%s%d",
3594 cs[i]->name, cs[i]->index);
3596 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3602 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3604 static struct attribute *cons_dev_attrs[] = {
3605 &dev_attr_active.attr,
3609 ATTRIBUTE_GROUPS(cons_dev);
3611 static struct device *consdev;
3613 void console_sysfs_notify(void)
3616 sysfs_notify(&consdev->kobj, NULL, "active");
3620 * Ok, now we can initialize the rest of the tty devices and can count
3621 * on memory allocations, interrupts etc..
3623 int __init tty_init(void)
3626 cdev_init(&tty_cdev, &tty_fops);
3627 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3628 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3629 panic("Couldn't register /dev/tty driver\n");
3630 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3632 cdev_init(&console_cdev, &console_fops);
3633 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3634 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3635 panic("Couldn't register /dev/console driver\n");
3636 consdev = device_create_with_groups(tty_class, NULL,
3637 MKDEV(TTYAUX_MAJOR, 1), NULL,
3638 cons_dev_groups, "console");
3639 if (IS_ERR(consdev))
3643 vty_init(&console_fops);