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>
113 #undef TTY_DEBUG_HANGUP
114 #ifdef TTY_DEBUG_HANGUP
115 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
117 # define tty_debug_hangup(tty, f, args...) do { } while (0)
120 #define TTY_PARANOIA_CHECK 1
121 #define CHECK_TTY_COUNT 1
123 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
124 .c_iflag = ICRNL | IXON,
125 .c_oflag = OPOST | ONLCR,
126 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
127 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
128 ECHOCTL | ECHOKE | IEXTEN,
132 /* .c_line = N_TTY, */
135 EXPORT_SYMBOL(tty_std_termios);
137 /* This list gets poked at by procfs and various bits of boot up code. This
138 could do with some rationalisation such as pulling the tty proc function
141 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
143 /* Mutex to protect creating and releasing a tty */
144 DEFINE_MUTEX(tty_mutex);
146 static ssize_t tty_read(struct kiocb *, struct iov_iter *);
147 static ssize_t tty_write(struct kiocb *, struct iov_iter *);
148 static __poll_t tty_poll(struct file *, poll_table *);
149 static int tty_open(struct inode *, struct file *);
151 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
154 #define tty_compat_ioctl NULL
156 static int __tty_fasync(int fd, struct file *filp, int on);
157 static int tty_fasync(int fd, struct file *filp, int on);
158 static void release_tty(struct tty_struct *tty, int idx);
161 * free_tty_struct - free a disused tty
162 * @tty: tty struct to free
164 * Free the write buffers, tty queue and tty memory itself.
166 * Locking: none. Must be called after tty is definitely unused
169 static void free_tty_struct(struct tty_struct *tty)
171 tty_ldisc_deinit(tty);
172 put_device(tty->dev);
173 kfree(tty->write_buf);
174 tty->magic = 0xDEADDEAD;
178 static inline struct tty_struct *file_tty(struct file *file)
180 return ((struct tty_file_private *)file->private_data)->tty;
183 int tty_alloc_file(struct file *file)
185 struct tty_file_private *priv;
187 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
191 file->private_data = priv;
196 /* Associate a new file with the tty structure */
197 void tty_add_file(struct tty_struct *tty, struct file *file)
199 struct tty_file_private *priv = file->private_data;
204 spin_lock(&tty->files_lock);
205 list_add(&priv->list, &tty->tty_files);
206 spin_unlock(&tty->files_lock);
210 * tty_free_file - free file->private_data
212 * This shall be used only for fail path handling when tty_add_file was not
215 void tty_free_file(struct file *file)
217 struct tty_file_private *priv = file->private_data;
219 file->private_data = NULL;
223 /* Delete file from its tty */
224 static void tty_del_file(struct file *file)
226 struct tty_file_private *priv = file->private_data;
227 struct tty_struct *tty = priv->tty;
229 spin_lock(&tty->files_lock);
230 list_del(&priv->list);
231 spin_unlock(&tty->files_lock);
236 * tty_name - return tty naming
237 * @tty: tty structure
239 * Convert a tty structure into a name. The name reflects the kernel
240 * naming policy and if udev is in use may not reflect user space
245 const char *tty_name(const struct tty_struct *tty)
247 if (!tty) /* Hmm. NULL pointer. That's fun. */
252 EXPORT_SYMBOL(tty_name);
254 const char *tty_driver_name(const struct tty_struct *tty)
256 if (!tty || !tty->driver)
258 return tty->driver->name;
261 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
264 #ifdef TTY_PARANOIA_CHECK
266 pr_warn("(%d:%d): %s: NULL tty\n",
267 imajor(inode), iminor(inode), routine);
270 if (tty->magic != TTY_MAGIC) {
271 pr_warn("(%d:%d): %s: bad magic number\n",
272 imajor(inode), iminor(inode), routine);
279 /* Caller must hold tty_lock */
280 static int check_tty_count(struct tty_struct *tty, const char *routine)
282 #ifdef CHECK_TTY_COUNT
284 int count = 0, kopen_count = 0;
286 spin_lock(&tty->files_lock);
287 list_for_each(p, &tty->tty_files) {
290 spin_unlock(&tty->files_lock);
291 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
292 tty->driver->subtype == PTY_TYPE_SLAVE &&
293 tty->link && tty->link->count)
295 if (tty_port_kopened(tty->port))
297 if (tty->count != (count + kopen_count)) {
298 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
299 routine, tty->count, count, kopen_count);
300 return (count + kopen_count);
307 * get_tty_driver - find device of a tty
308 * @device: device identifier
309 * @index: returns the index of the tty
311 * This routine returns a tty driver structure, given a device number
312 * and also passes back the index number.
314 * Locking: caller must hold tty_mutex
317 static struct tty_driver *get_tty_driver(dev_t device, int *index)
319 struct tty_driver *p;
321 list_for_each_entry(p, &tty_drivers, tty_drivers) {
322 dev_t base = MKDEV(p->major, p->minor_start);
323 if (device < base || device >= base + p->num)
325 *index = device - base;
326 return tty_driver_kref_get(p);
332 * tty_dev_name_to_number - return dev_t for device name
333 * @name: user space name of device under /dev
334 * @number: pointer to dev_t that this function will populate
336 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
337 * like (4, 64) or (188, 1). If no corresponding driver is registered then
338 * the function returns -ENODEV.
340 * Locking: this acquires tty_mutex to protect the tty_drivers list from
341 * being modified while we are traversing it, and makes sure to
342 * release it before exiting.
344 int tty_dev_name_to_number(const char *name, dev_t *number)
346 struct tty_driver *p;
348 int index, prefix_length = 0;
351 for (str = name; *str && !isdigit(*str); str++)
357 ret = kstrtoint(str, 10, &index);
361 prefix_length = str - name;
362 mutex_lock(&tty_mutex);
364 list_for_each_entry(p, &tty_drivers, tty_drivers)
365 if (prefix_length == strlen(p->name) && strncmp(name,
366 p->name, prefix_length) == 0) {
367 if (index < p->num) {
368 *number = MKDEV(p->major, p->minor_start + index);
373 /* if here then driver wasn't found */
376 mutex_unlock(&tty_mutex);
379 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
381 #ifdef CONFIG_CONSOLE_POLL
384 * tty_find_polling_driver - find device of a polled tty
385 * @name: name string to match
386 * @line: pointer to resulting tty line nr
388 * This routine returns a tty driver structure, given a name
389 * and the condition that the tty driver is capable of polled
392 struct tty_driver *tty_find_polling_driver(char *name, int *line)
394 struct tty_driver *p, *res = NULL;
399 for (str = name; *str; str++)
400 if ((*str >= '0' && *str <= '9') || *str == ',')
406 tty_line = simple_strtoul(str, &str, 10);
408 mutex_lock(&tty_mutex);
409 /* Search through the tty devices to look for a match */
410 list_for_each_entry(p, &tty_drivers, tty_drivers) {
411 if (!len || strncmp(name, p->name, len) != 0)
419 if (tty_line >= 0 && tty_line < p->num && p->ops &&
420 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
421 res = tty_driver_kref_get(p);
426 mutex_unlock(&tty_mutex);
430 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
433 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
438 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
443 /* No kernel lock held - none needed ;) */
444 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
446 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
449 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
452 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
455 static long hung_up_tty_compat_ioctl(struct file *file,
456 unsigned int cmd, unsigned long arg)
458 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
461 static int hung_up_tty_fasync(int fd, struct file *file, int on)
466 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
468 struct tty_struct *tty = file_tty(file);
470 if (tty && tty->ops && tty->ops->show_fdinfo)
471 tty->ops->show_fdinfo(tty, m);
474 static const struct file_operations tty_fops = {
476 .read_iter = tty_read,
477 .write_iter = tty_write,
478 .splice_read = generic_file_splice_read,
479 .splice_write = iter_file_splice_write,
481 .unlocked_ioctl = tty_ioctl,
482 .compat_ioctl = tty_compat_ioctl,
484 .release = tty_release,
485 .fasync = tty_fasync,
486 .show_fdinfo = tty_show_fdinfo,
489 static const struct file_operations console_fops = {
491 .read_iter = tty_read,
492 .write_iter = redirected_tty_write,
493 .splice_read = generic_file_splice_read,
494 .splice_write = iter_file_splice_write,
496 .unlocked_ioctl = tty_ioctl,
497 .compat_ioctl = tty_compat_ioctl,
499 .release = tty_release,
500 .fasync = tty_fasync,
503 static const struct file_operations hung_up_tty_fops = {
505 .read_iter = hung_up_tty_read,
506 .write_iter = hung_up_tty_write,
507 .poll = hung_up_tty_poll,
508 .unlocked_ioctl = hung_up_tty_ioctl,
509 .compat_ioctl = hung_up_tty_compat_ioctl,
510 .release = tty_release,
511 .fasync = hung_up_tty_fasync,
514 static DEFINE_SPINLOCK(redirect_lock);
515 static struct file *redirect;
518 * tty_wakeup - request more data
521 * Internal and external helper for wakeups of tty. This function
522 * informs the line discipline if present that the driver is ready
523 * to receive more output data.
526 void tty_wakeup(struct tty_struct *tty)
528 struct tty_ldisc *ld;
530 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
531 ld = tty_ldisc_ref(tty);
533 if (ld->ops->write_wakeup)
534 ld->ops->write_wakeup(tty);
538 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
541 EXPORT_SYMBOL_GPL(tty_wakeup);
544 * tty_release_redirect - Release a redirect on a pty if present
547 * This is available to the pty code so if the master closes, if the
548 * slave is a redirect it can release the redirect.
550 struct file *tty_release_redirect(struct tty_struct *tty)
552 struct file *f = NULL;
554 spin_lock(&redirect_lock);
555 if (redirect && file_tty(redirect) == tty) {
559 spin_unlock(&redirect_lock);
563 EXPORT_SYMBOL_GPL(tty_release_redirect);
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);
1200 * pty_line_name - generate name for a pty
1201 * @driver: the tty driver in use
1202 * @index: the minor number
1203 * @p: output buffer of at least 6 bytes
1205 * Generate a name from a driver reference and write it to the output
1210 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1212 static const char ptychar[] = "pqrstuvwxyzabcde";
1213 int i = index + driver->name_base;
1214 /* ->name is initialized to "ttyp", but "tty" is expected */
1215 sprintf(p, "%s%c%x",
1216 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1217 ptychar[i >> 4 & 0xf], i & 0xf);
1221 * tty_line_name - generate name for a tty
1222 * @driver: the tty driver in use
1223 * @index: the minor number
1224 * @p: output buffer of at least 7 bytes
1226 * Generate a name from a driver reference and write it to the output
1231 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1233 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1234 return sprintf(p, "%s", driver->name);
1236 return sprintf(p, "%s%d", driver->name,
1237 index + driver->name_base);
1241 * tty_driver_lookup_tty() - find an existing tty, if any
1242 * @driver: the driver for the tty
1243 * @file: file object
1244 * @idx: the minor number
1246 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1247 * driver lookup() method returns an error.
1249 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1251 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1252 struct file *file, int idx)
1254 struct tty_struct *tty;
1256 if (driver->ops->lookup)
1258 tty = ERR_PTR(-EIO);
1260 tty = driver->ops->lookup(driver, file, idx);
1262 tty = driver->ttys[idx];
1270 * tty_init_termios - helper for termios setup
1271 * @tty: the tty to set up
1273 * Initialise the termios structure for this tty. This runs under
1274 * the tty_mutex currently so we can be relaxed about ordering.
1277 void tty_init_termios(struct tty_struct *tty)
1279 struct ktermios *tp;
1280 int idx = tty->index;
1282 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1283 tty->termios = tty->driver->init_termios;
1285 /* Check for lazy saved data */
1286 tp = tty->driver->termios[idx];
1289 tty->termios.c_line = tty->driver->init_termios.c_line;
1291 tty->termios = tty->driver->init_termios;
1293 /* Compatibility until drivers always set this */
1294 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1295 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1297 EXPORT_SYMBOL_GPL(tty_init_termios);
1299 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1301 tty_init_termios(tty);
1302 tty_driver_kref_get(driver);
1304 driver->ttys[tty->index] = tty;
1307 EXPORT_SYMBOL_GPL(tty_standard_install);
1310 * tty_driver_install_tty() - install a tty entry in the driver
1311 * @driver: the driver for the tty
1314 * Install a tty object into the driver tables. The tty->index field
1315 * will be set by the time this is called. This method is responsible
1316 * for ensuring any need additional structures are allocated and
1319 * Locking: tty_mutex for now
1321 static int tty_driver_install_tty(struct tty_driver *driver,
1322 struct tty_struct *tty)
1324 return driver->ops->install ? driver->ops->install(driver, tty) :
1325 tty_standard_install(driver, tty);
1329 * tty_driver_remove_tty() - remove a tty from the driver tables
1330 * @driver: the driver for the tty
1331 * @tty: tty to remove
1333 * Remvoe a tty object from the driver tables. The tty->index field
1334 * will be set by the time this is called.
1336 * Locking: tty_mutex for now
1338 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1340 if (driver->ops->remove)
1341 driver->ops->remove(driver, tty);
1343 driver->ttys[tty->index] = NULL;
1347 * tty_reopen() - fast re-open of an open tty
1348 * @tty: the tty to open
1350 * Return 0 on success, -errno on error.
1351 * Re-opens on master ptys are not allowed and return -EIO.
1353 * Locking: Caller must hold tty_lock
1355 static int tty_reopen(struct tty_struct *tty)
1357 struct tty_driver *driver = tty->driver;
1358 struct tty_ldisc *ld;
1361 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1362 driver->subtype == PTY_TYPE_MASTER)
1368 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1371 ld = tty_ldisc_ref_wait(tty);
1373 tty_ldisc_deref(ld);
1375 retval = tty_ldisc_lock(tty, 5 * HZ);
1380 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1381 tty_ldisc_unlock(tty);
1391 * tty_init_dev - initialise a tty device
1392 * @driver: tty driver we are opening a device on
1393 * @idx: device index
1395 * Prepare a tty device. This may not be a "new" clean device but
1396 * could also be an active device. The pty drivers require special
1397 * handling because of this.
1400 * The function is called under the tty_mutex, which
1401 * protects us from the tty struct or driver itself going away.
1403 * On exit the tty device has the line discipline attached and
1404 * a reference count of 1. If a pair was created for pty/tty use
1405 * and the other was a pty master then it too has a reference count of 1.
1407 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1408 * failed open. The new code protects the open with a mutex, so it's
1409 * really quite straightforward. The mutex locking can probably be
1410 * relaxed for the (most common) case of reopening a tty.
1412 * Return: returned tty structure
1415 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1417 struct tty_struct *tty;
1421 * First time open is complex, especially for PTY devices.
1422 * This code guarantees that either everything succeeds and the
1423 * TTY is ready for operation, or else the table slots are vacated
1424 * and the allocated memory released. (Except that the termios
1428 if (!try_module_get(driver->owner))
1429 return ERR_PTR(-ENODEV);
1431 tty = alloc_tty_struct(driver, idx);
1434 goto err_module_put;
1438 retval = tty_driver_install_tty(driver, tty);
1443 tty->port = driver->ports[idx];
1445 if (WARN_RATELIMIT(!tty->port,
1446 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1447 __func__, tty->driver->name)) {
1449 goto err_release_lock;
1452 retval = tty_ldisc_lock(tty, 5 * HZ);
1454 goto err_release_lock;
1455 tty->port->itty = tty;
1458 * Structures all installed ... call the ldisc open routines.
1459 * If we fail here just call release_tty to clean up. No need
1460 * to decrement the use counts, as release_tty doesn't care.
1462 retval = tty_ldisc_setup(tty, tty->link);
1464 goto err_release_tty;
1465 tty_ldisc_unlock(tty);
1466 /* Return the tty locked so that it cannot vanish under the caller */
1471 free_tty_struct(tty);
1473 module_put(driver->owner);
1474 return ERR_PTR(retval);
1476 /* call the tty release_tty routine to clean out this slot */
1478 tty_ldisc_unlock(tty);
1479 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1483 release_tty(tty, idx);
1484 return ERR_PTR(retval);
1488 * tty_save_termios() - save tty termios data in driver table
1489 * @tty: tty whose termios data to save
1491 * Locking: Caller guarantees serialisation with tty_init_termios().
1493 void tty_save_termios(struct tty_struct *tty)
1495 struct ktermios *tp;
1496 int idx = tty->index;
1498 /* If the port is going to reset then it has no termios to save */
1499 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1502 /* Stash the termios data */
1503 tp = tty->driver->termios[idx];
1505 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1508 tty->driver->termios[idx] = tp;
1512 EXPORT_SYMBOL_GPL(tty_save_termios);
1515 * tty_flush_works - flush all works of a tty/pty pair
1516 * @tty: tty device to flush works for (or either end of a pty pair)
1518 * Sync flush all works belonging to @tty (and the 'other' tty).
1520 static void tty_flush_works(struct tty_struct *tty)
1522 flush_work(&tty->SAK_work);
1523 flush_work(&tty->hangup_work);
1525 flush_work(&tty->link->SAK_work);
1526 flush_work(&tty->link->hangup_work);
1531 * release_one_tty - release tty structure memory
1532 * @work: work of tty we are obliterating
1534 * Releases memory associated with a tty structure, and clears out the
1535 * driver table slots. This function is called when a device is no longer
1536 * in use. It also gets called when setup of a device fails.
1539 * takes the file list lock internally when working on the list
1540 * of ttys that the driver keeps.
1542 * This method gets called from a work queue so that the driver private
1543 * cleanup ops can sleep (needed for USB at least)
1545 static void release_one_tty(struct work_struct *work)
1547 struct tty_struct *tty =
1548 container_of(work, struct tty_struct, hangup_work);
1549 struct tty_driver *driver = tty->driver;
1550 struct module *owner = driver->owner;
1552 if (tty->ops->cleanup)
1553 tty->ops->cleanup(tty);
1556 tty_driver_kref_put(driver);
1559 spin_lock(&tty->files_lock);
1560 list_del_init(&tty->tty_files);
1561 spin_unlock(&tty->files_lock);
1564 put_pid(tty->session);
1565 free_tty_struct(tty);
1568 static void queue_release_one_tty(struct kref *kref)
1570 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1572 /* The hangup queue is now free so we can reuse it rather than
1573 waste a chunk of memory for each port */
1574 INIT_WORK(&tty->hangup_work, release_one_tty);
1575 schedule_work(&tty->hangup_work);
1579 * tty_kref_put - release a tty kref
1582 * Release a reference to a tty device and if need be let the kref
1583 * layer destruct the object for us
1586 void tty_kref_put(struct tty_struct *tty)
1589 kref_put(&tty->kref, queue_release_one_tty);
1591 EXPORT_SYMBOL(tty_kref_put);
1594 * release_tty - release tty structure memory
1595 * @tty: tty device release
1596 * @idx: index of the tty device release
1598 * Release both @tty and a possible linked partner (think pty pair),
1599 * and decrement the refcount of the backing module.
1603 * takes the file list lock internally when working on the list
1604 * of ttys that the driver keeps.
1607 static void release_tty(struct tty_struct *tty, int idx)
1609 /* This should always be true but check for the moment */
1610 WARN_ON(tty->index != idx);
1611 WARN_ON(!mutex_is_locked(&tty_mutex));
1612 if (tty->ops->shutdown)
1613 tty->ops->shutdown(tty);
1614 tty_save_termios(tty);
1615 tty_driver_remove_tty(tty->driver, tty);
1617 tty->port->itty = NULL;
1619 tty->link->port->itty = NULL;
1621 tty_buffer_cancel_work(tty->port);
1623 tty_buffer_cancel_work(tty->link->port);
1625 tty_kref_put(tty->link);
1630 * tty_release_checks - check a tty before real release
1631 * @tty: tty to check
1632 * @idx: index of the tty
1634 * Performs some paranoid checking before true release of the @tty.
1635 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1637 static int tty_release_checks(struct tty_struct *tty, int idx)
1639 #ifdef TTY_PARANOIA_CHECK
1640 if (idx < 0 || idx >= tty->driver->num) {
1641 tty_debug(tty, "bad idx %d\n", idx);
1645 /* not much to check for devpts */
1646 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1649 if (tty != tty->driver->ttys[idx]) {
1650 tty_debug(tty, "bad driver table[%d] = %p\n",
1651 idx, tty->driver->ttys[idx]);
1654 if (tty->driver->other) {
1655 struct tty_struct *o_tty = tty->link;
1657 if (o_tty != tty->driver->other->ttys[idx]) {
1658 tty_debug(tty, "bad other table[%d] = %p\n",
1659 idx, tty->driver->other->ttys[idx]);
1662 if (o_tty->link != tty) {
1663 tty_debug(tty, "bad link = %p\n", o_tty->link);
1672 * tty_kclose - closes tty opened by tty_kopen
1675 * Performs the final steps to release and free a tty device. It is the
1676 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1677 * flag on tty->port.
1679 void tty_kclose(struct tty_struct *tty)
1682 * Ask the line discipline code to release its structures
1684 tty_ldisc_release(tty);
1686 /* Wait for pending work before tty destruction commmences */
1687 tty_flush_works(tty);
1689 tty_debug_hangup(tty, "freeing structure\n");
1691 * The release_tty function takes care of the details of clearing
1692 * the slots and preserving the termios structure.
1694 mutex_lock(&tty_mutex);
1695 tty_port_set_kopened(tty->port, 0);
1696 release_tty(tty, tty->index);
1697 mutex_unlock(&tty_mutex);
1699 EXPORT_SYMBOL_GPL(tty_kclose);
1702 * tty_release_struct - release a tty struct
1704 * @idx: index of the tty
1706 * Performs the final steps to release and free a tty device. It is
1707 * roughly the reverse of tty_init_dev.
1709 void tty_release_struct(struct tty_struct *tty, int idx)
1712 * Ask the line discipline code to release its structures
1714 tty_ldisc_release(tty);
1716 /* Wait for pending work before tty destruction commmences */
1717 tty_flush_works(tty);
1719 tty_debug_hangup(tty, "freeing structure\n");
1721 * The release_tty function takes care of the details of clearing
1722 * the slots and preserving the termios structure.
1724 mutex_lock(&tty_mutex);
1725 release_tty(tty, idx);
1726 mutex_unlock(&tty_mutex);
1728 EXPORT_SYMBOL_GPL(tty_release_struct);
1731 * tty_release - vfs callback for close
1732 * @inode: inode of tty
1733 * @filp: file pointer for handle to tty
1735 * Called the last time each file handle is closed that references
1736 * this tty. There may however be several such references.
1739 * Takes bkl. See tty_release_dev
1741 * Even releasing the tty structures is a tricky business.. We have
1742 * to be very careful that the structures are all released at the
1743 * same time, as interrupts might otherwise get the wrong pointers.
1745 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1746 * lead to double frees or releasing memory still in use.
1749 int tty_release(struct inode *inode, struct file *filp)
1751 struct tty_struct *tty = file_tty(filp);
1752 struct tty_struct *o_tty = NULL;
1753 int do_sleep, final;
1758 if (tty_paranoia_check(tty, inode, __func__))
1762 check_tty_count(tty, __func__);
1764 __tty_fasync(-1, filp, 0);
1767 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1768 tty->driver->subtype == PTY_TYPE_MASTER)
1771 if (tty_release_checks(tty, idx)) {
1776 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1778 if (tty->ops->close)
1779 tty->ops->close(tty, filp);
1781 /* If tty is pty master, lock the slave pty (stable lock order) */
1782 tty_lock_slave(o_tty);
1785 * Sanity check: if tty->count is going to zero, there shouldn't be
1786 * any waiters on tty->read_wait or tty->write_wait. We test the
1787 * wait queues and kick everyone out _before_ actually starting to
1788 * close. This ensures that we won't block while releasing the tty
1791 * The test for the o_tty closing is necessary, since the master and
1792 * slave sides may close in any order. If the slave side closes out
1793 * first, its count will be one, since the master side holds an open.
1794 * Thus this test wouldn't be triggered at the time the slave closed,
1800 if (tty->count <= 1) {
1801 if (waitqueue_active(&tty->read_wait)) {
1802 wake_up_poll(&tty->read_wait, EPOLLIN);
1805 if (waitqueue_active(&tty->write_wait)) {
1806 wake_up_poll(&tty->write_wait, EPOLLOUT);
1810 if (o_tty && o_tty->count <= 1) {
1811 if (waitqueue_active(&o_tty->read_wait)) {
1812 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1815 if (waitqueue_active(&o_tty->write_wait)) {
1816 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1825 tty_warn(tty, "read/write wait queue active!\n");
1827 schedule_timeout_killable(timeout);
1828 if (timeout < 120 * HZ)
1829 timeout = 2 * timeout + 1;
1831 timeout = MAX_SCHEDULE_TIMEOUT;
1835 if (--o_tty->count < 0) {
1836 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1840 if (--tty->count < 0) {
1841 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1846 * We've decremented tty->count, so we need to remove this file
1847 * descriptor off the tty->tty_files list; this serves two
1849 * - check_tty_count sees the correct number of file descriptors
1850 * associated with this tty.
1851 * - do_tty_hangup no longer sees this file descriptor as
1852 * something that needs to be handled for hangups.
1857 * Perform some housekeeping before deciding whether to return.
1859 * If _either_ side is closing, make sure there aren't any
1860 * processes that still think tty or o_tty is their controlling
1864 read_lock(&tasklist_lock);
1865 session_clear_tty(tty->session);
1867 session_clear_tty(o_tty->session);
1868 read_unlock(&tasklist_lock);
1871 /* check whether both sides are closing ... */
1872 final = !tty->count && !(o_tty && o_tty->count);
1874 tty_unlock_slave(o_tty);
1877 /* At this point, the tty->count == 0 should ensure a dead tty
1878 cannot be re-opened by a racing opener */
1883 tty_debug_hangup(tty, "final close\n");
1885 tty_release_struct(tty, idx);
1890 * tty_open_current_tty - get locked tty of current task
1891 * @device: device number
1892 * @filp: file pointer to tty
1893 * @return: locked tty of the current task iff @device is /dev/tty
1895 * Performs a re-open of the current task's controlling tty.
1897 * We cannot return driver and index like for the other nodes because
1898 * devpts will not work then. It expects inodes to be from devpts FS.
1900 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1902 struct tty_struct *tty;
1905 if (device != MKDEV(TTYAUX_MAJOR, 0))
1908 tty = get_current_tty();
1910 return ERR_PTR(-ENXIO);
1912 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1915 tty_kref_put(tty); /* safe to drop the kref now */
1917 retval = tty_reopen(tty);
1920 tty = ERR_PTR(retval);
1926 * tty_lookup_driver - lookup a tty driver for a given device file
1927 * @device: device number
1928 * @filp: file pointer to tty
1929 * @index: index for the device in the @return driver
1930 * @return: driver for this inode (with increased refcount)
1932 * If @return is not erroneous, the caller is responsible to decrement the
1933 * refcount by tty_driver_kref_put.
1935 * Locking: tty_mutex protects get_tty_driver
1937 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1940 struct tty_driver *driver = NULL;
1944 case MKDEV(TTY_MAJOR, 0): {
1945 extern struct tty_driver *console_driver;
1946 driver = tty_driver_kref_get(console_driver);
1947 *index = fg_console;
1951 case MKDEV(TTYAUX_MAJOR, 1): {
1952 struct tty_driver *console_driver = console_device(index);
1953 if (console_driver) {
1954 driver = tty_driver_kref_get(console_driver);
1955 if (driver && filp) {
1956 /* Don't let /dev/console block */
1957 filp->f_flags |= O_NONBLOCK;
1962 tty_driver_kref_put(driver);
1963 return ERR_PTR(-ENODEV);
1966 driver = get_tty_driver(device, index);
1968 return ERR_PTR(-ENODEV);
1974 static struct tty_struct *tty_kopen(dev_t device, int shared)
1976 struct tty_struct *tty;
1977 struct tty_driver *driver;
1980 mutex_lock(&tty_mutex);
1981 driver = tty_lookup_driver(device, NULL, &index);
1982 if (IS_ERR(driver)) {
1983 mutex_unlock(&tty_mutex);
1984 return ERR_CAST(driver);
1987 /* check whether we're reopening an existing tty */
1988 tty = tty_driver_lookup_tty(driver, NULL, index);
1989 if (IS_ERR(tty) || shared)
1993 /* drop kref from tty_driver_lookup_tty() */
1995 tty = ERR_PTR(-EBUSY);
1996 } else { /* tty_init_dev returns tty with the tty_lock held */
1997 tty = tty_init_dev(driver, index);
2000 tty_port_set_kopened(tty->port, 1);
2003 mutex_unlock(&tty_mutex);
2004 tty_driver_kref_put(driver);
2009 * tty_kopen_exclusive - open a tty device for kernel
2010 * @device: dev_t of device to open
2012 * Opens tty exclusively for kernel. Performs the driver lookup,
2013 * makes sure it's not already opened and performs the first-time
2014 * tty initialization.
2016 * Returns the locked initialized &tty_struct
2018 * Claims the global tty_mutex to serialize:
2019 * - concurrent first-time tty initialization
2020 * - concurrent tty driver removal w/ lookup
2021 * - concurrent tty removal from driver table
2023 struct tty_struct *tty_kopen_exclusive(dev_t device)
2025 return tty_kopen(device, 0);
2027 EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
2030 * tty_kopen_shared - open a tty device for shared in-kernel use
2031 * @device: dev_t of device to open
2033 * Opens an already existing tty for in-kernel use. Compared to
2034 * tty_kopen_exclusive() above it doesn't ensure to be the only user.
2036 * Locking is identical to tty_kopen() above.
2038 struct tty_struct *tty_kopen_shared(dev_t device)
2040 return tty_kopen(device, 1);
2042 EXPORT_SYMBOL_GPL(tty_kopen_shared);
2045 * tty_open_by_driver - open a tty device
2046 * @device: dev_t of device to open
2047 * @filp: file pointer to tty
2049 * Performs the driver lookup, checks for a reopen, or otherwise
2050 * performs the first-time tty initialization.
2052 * Returns the locked initialized or re-opened &tty_struct
2054 * Claims the global tty_mutex to serialize:
2055 * - concurrent first-time tty initialization
2056 * - concurrent tty driver removal w/ lookup
2057 * - concurrent tty removal from driver table
2059 static struct tty_struct *tty_open_by_driver(dev_t device,
2062 struct tty_struct *tty;
2063 struct tty_driver *driver = NULL;
2067 mutex_lock(&tty_mutex);
2068 driver = tty_lookup_driver(device, filp, &index);
2069 if (IS_ERR(driver)) {
2070 mutex_unlock(&tty_mutex);
2071 return ERR_CAST(driver);
2074 /* check whether we're reopening an existing tty */
2075 tty = tty_driver_lookup_tty(driver, filp, index);
2077 mutex_unlock(&tty_mutex);
2082 if (tty_port_kopened(tty->port)) {
2084 mutex_unlock(&tty_mutex);
2085 tty = ERR_PTR(-EBUSY);
2088 mutex_unlock(&tty_mutex);
2089 retval = tty_lock_interruptible(tty);
2090 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2092 if (retval == -EINTR)
2093 retval = -ERESTARTSYS;
2094 tty = ERR_PTR(retval);
2097 retval = tty_reopen(tty);
2100 tty = ERR_PTR(retval);
2102 } else { /* Returns with the tty_lock held for now */
2103 tty = tty_init_dev(driver, index);
2104 mutex_unlock(&tty_mutex);
2107 tty_driver_kref_put(driver);
2112 * tty_open - open a tty device
2113 * @inode: inode of device file
2114 * @filp: file pointer to tty
2116 * tty_open and tty_release keep up the tty count that contains the
2117 * number of opens done on a tty. We cannot use the inode-count, as
2118 * different inodes might point to the same tty.
2120 * Open-counting is needed for pty masters, as well as for keeping
2121 * track of serial lines: DTR is dropped when the last close happens.
2122 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2124 * The termios state of a pty is reset on first open so that
2125 * settings don't persist across reuse.
2127 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2128 * tty->count should protect the rest.
2129 * ->siglock protects ->signal/->sighand
2131 * Note: the tty_unlock/lock cases without a ref are only safe due to
2135 static int tty_open(struct inode *inode, struct file *filp)
2137 struct tty_struct *tty;
2139 dev_t device = inode->i_rdev;
2140 unsigned saved_flags = filp->f_flags;
2142 nonseekable_open(inode, filp);
2145 retval = tty_alloc_file(filp);
2149 tty = tty_open_current_tty(device, filp);
2151 tty = tty_open_by_driver(device, filp);
2154 tty_free_file(filp);
2155 retval = PTR_ERR(tty);
2156 if (retval != -EAGAIN || signal_pending(current))
2162 tty_add_file(tty, filp);
2164 check_tty_count(tty, __func__);
2165 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2168 retval = tty->ops->open(tty, filp);
2171 filp->f_flags = saved_flags;
2174 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2176 tty_unlock(tty); /* need to call tty_release without BTM */
2177 tty_release(inode, filp);
2178 if (retval != -ERESTARTSYS)
2181 if (signal_pending(current))
2186 * Need to reset f_op in case a hangup happened.
2188 if (tty_hung_up_p(filp))
2189 filp->f_op = &tty_fops;
2192 clear_bit(TTY_HUPPED, &tty->flags);
2194 noctty = (filp->f_flags & O_NOCTTY) ||
2195 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2196 device == MKDEV(TTYAUX_MAJOR, 1) ||
2197 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2198 tty->driver->subtype == PTY_TYPE_MASTER);
2200 tty_open_proc_set_tty(filp, tty);
2208 * tty_poll - check tty status
2209 * @filp: file being polled
2210 * @wait: poll wait structures to update
2212 * Call the line discipline polling method to obtain the poll
2213 * status of the device.
2215 * Locking: locks called line discipline but ldisc poll method
2216 * may be re-entered freely by other callers.
2219 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2221 struct tty_struct *tty = file_tty(filp);
2222 struct tty_ldisc *ld;
2225 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2228 ld = tty_ldisc_ref_wait(tty);
2230 return hung_up_tty_poll(filp, wait);
2232 ret = ld->ops->poll(tty, filp, wait);
2233 tty_ldisc_deref(ld);
2237 static int __tty_fasync(int fd, struct file *filp, int on)
2239 struct tty_struct *tty = file_tty(filp);
2240 unsigned long flags;
2243 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2246 retval = fasync_helper(fd, filp, on, &tty->fasync);
2254 spin_lock_irqsave(&tty->ctrl_lock, flags);
2257 type = PIDTYPE_PGID;
2259 pid = task_pid(current);
2260 type = PIDTYPE_TGID;
2263 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2264 __f_setown(filp, pid, type, 0);
2272 static int tty_fasync(int fd, struct file *filp, int on)
2274 struct tty_struct *tty = file_tty(filp);
2275 int retval = -ENOTTY;
2278 if (!tty_hung_up_p(filp))
2279 retval = __tty_fasync(fd, filp, on);
2286 * tiocsti - fake input character
2287 * @tty: tty to fake input into
2288 * @p: pointer to character
2290 * Fake input to a tty device. Does the necessary locking and
2293 * FIXME: does not honour flow control ??
2296 * Called functions take tty_ldiscs_lock
2297 * current->signal->tty check is safe without locks
2299 * FIXME: may race normal receive processing
2302 static int tiocsti(struct tty_struct *tty, char __user *p)
2305 struct tty_ldisc *ld;
2307 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2309 if (get_user(ch, p))
2311 tty_audit_tiocsti(tty, ch);
2312 ld = tty_ldisc_ref_wait(tty);
2315 if (ld->ops->receive_buf)
2316 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2317 tty_ldisc_deref(ld);
2322 * tiocgwinsz - implement window query ioctl
2324 * @arg: user buffer for result
2326 * Copies the kernel idea of the window size into the user buffer.
2328 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2332 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2336 mutex_lock(&tty->winsize_mutex);
2337 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2338 mutex_unlock(&tty->winsize_mutex);
2340 return err ? -EFAULT: 0;
2344 * tty_do_resize - resize event
2345 * @tty: tty being resized
2346 * @ws: new dimensions
2348 * Update the termios variables and send the necessary signals to
2349 * peform a terminal resize correctly
2352 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2357 mutex_lock(&tty->winsize_mutex);
2358 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2361 /* Signal the foreground process group */
2362 pgrp = tty_get_pgrp(tty);
2364 kill_pgrp(pgrp, SIGWINCH, 1);
2369 mutex_unlock(&tty->winsize_mutex);
2372 EXPORT_SYMBOL(tty_do_resize);
2375 * tiocswinsz - implement window size set ioctl
2376 * @tty: tty side of tty
2377 * @arg: user buffer for result
2379 * Copies the user idea of the window size to the kernel. Traditionally
2380 * this is just advisory information but for the Linux console it
2381 * actually has driver level meaning and triggers a VC resize.
2384 * Driver dependent. The default do_resize method takes the
2385 * tty termios mutex and ctrl_lock. The console takes its own lock
2386 * then calls into the default method.
2389 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2391 struct winsize tmp_ws;
2392 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2395 if (tty->ops->resize)
2396 return tty->ops->resize(tty, &tmp_ws);
2398 return tty_do_resize(tty, &tmp_ws);
2402 * tioccons - allow admin to move logical console
2403 * @file: the file to become console
2405 * Allow the administrator to move the redirected console device
2407 * Locking: uses redirect_lock to guard the redirect information
2410 static int tioccons(struct file *file)
2412 if (!capable(CAP_SYS_ADMIN))
2414 if (file->f_op->write_iter == redirected_tty_write) {
2416 spin_lock(&redirect_lock);
2419 spin_unlock(&redirect_lock);
2424 if (file->f_op->write_iter != tty_write)
2426 if (!(file->f_mode & FMODE_WRITE))
2428 if (!(file->f_mode & FMODE_CAN_WRITE))
2430 spin_lock(&redirect_lock);
2432 spin_unlock(&redirect_lock);
2435 redirect = get_file(file);
2436 spin_unlock(&redirect_lock);
2441 * tiocsetd - set line discipline
2443 * @p: pointer to user data
2445 * Set the line discipline according to user request.
2447 * Locking: see tty_set_ldisc, this function is just a helper
2450 static int tiocsetd(struct tty_struct *tty, int __user *p)
2455 if (get_user(disc, p))
2458 ret = tty_set_ldisc(tty, disc);
2464 * tiocgetd - get line discipline
2466 * @p: pointer to user data
2468 * Retrieves the line discipline id directly from the ldisc.
2470 * Locking: waits for ldisc reference (in case the line discipline
2471 * is changing or the tty is being hungup)
2474 static int tiocgetd(struct tty_struct *tty, int __user *p)
2476 struct tty_ldisc *ld;
2479 ld = tty_ldisc_ref_wait(tty);
2482 ret = put_user(ld->ops->num, p);
2483 tty_ldisc_deref(ld);
2488 * send_break - performed time break
2489 * @tty: device to break on
2490 * @duration: timeout in mS
2492 * Perform a timed break on hardware that lacks its own driver level
2493 * timed break functionality.
2496 * atomic_write_lock serializes
2500 static int send_break(struct tty_struct *tty, unsigned int duration)
2504 if (tty->ops->break_ctl == NULL)
2507 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2508 retval = tty->ops->break_ctl(tty, duration);
2510 /* Do the work ourselves */
2511 if (tty_write_lock(tty, 0) < 0)
2513 retval = tty->ops->break_ctl(tty, -1);
2516 if (!signal_pending(current))
2517 msleep_interruptible(duration);
2518 retval = tty->ops->break_ctl(tty, 0);
2520 tty_write_unlock(tty);
2521 if (signal_pending(current))
2528 * tty_tiocmget - get modem status
2530 * @p: pointer to result
2532 * Obtain the modem status bits from the tty driver if the feature
2533 * is supported. Return -ENOTTY if it is not available.
2535 * Locking: none (up to the driver)
2538 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2540 int retval = -ENOTTY;
2542 if (tty->ops->tiocmget) {
2543 retval = tty->ops->tiocmget(tty);
2546 retval = put_user(retval, p);
2552 * tty_tiocmset - set modem status
2554 * @cmd: command - clear bits, set bits or set all
2555 * @p: pointer to desired bits
2557 * Set the modem status bits from the tty driver if the feature
2558 * is supported. Return -ENOTTY if it is not available.
2560 * Locking: none (up to the driver)
2563 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2567 unsigned int set, clear, val;
2569 if (tty->ops->tiocmset == NULL)
2572 retval = get_user(val, p);
2588 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2589 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2590 return tty->ops->tiocmset(tty, set, clear);
2594 * tty_get_icount - get tty statistics
2596 * @icount: output parameter
2598 * Gets a copy of the tty's icount statistics.
2600 * Locking: none (up to the driver)
2602 int tty_get_icount(struct tty_struct *tty,
2603 struct serial_icounter_struct *icount)
2605 memset(icount, 0, sizeof(*icount));
2607 if (tty->ops->get_icount)
2608 return tty->ops->get_icount(tty, icount);
2612 EXPORT_SYMBOL_GPL(tty_get_icount);
2614 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2616 struct serial_icounter_struct icount;
2619 retval = tty_get_icount(tty, &icount);
2623 if (copy_to_user(arg, &icount, sizeof(icount)))
2628 static int tty_set_serial(struct tty_struct *tty, struct serial_struct *ss)
2630 char comm[TASK_COMM_LEN];
2633 flags = ss->flags & ASYNC_DEPRECATED;
2636 pr_warn_ratelimited("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2637 __func__, get_task_comm(comm, current), flags);
2639 if (!tty->ops->set_serial)
2642 return tty->ops->set_serial(tty, ss);
2645 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2647 struct serial_struct v;
2649 if (copy_from_user(&v, ss, sizeof(*ss)))
2652 return tty_set_serial(tty, &v);
2655 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2657 struct serial_struct v;
2660 memset(&v, 0, sizeof(v));
2661 if (!tty->ops->get_serial)
2663 err = tty->ops->get_serial(tty, &v);
2664 if (!err && copy_to_user(ss, &v, sizeof(v)))
2670 * if pty, return the slave side (real_tty)
2671 * otherwise, return self
2673 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2675 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2676 tty->driver->subtype == PTY_TYPE_MASTER)
2682 * Split this up, as gcc can choke on it otherwise..
2684 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2686 struct tty_struct *tty = file_tty(file);
2687 struct tty_struct *real_tty;
2688 void __user *p = (void __user *)arg;
2690 struct tty_ldisc *ld;
2692 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2695 real_tty = tty_pair_get_tty(tty);
2698 * Factor out some common prep work
2706 retval = tty_check_change(tty);
2709 if (cmd != TIOCCBRK) {
2710 tty_wait_until_sent(tty, 0);
2711 if (signal_pending(current))
2722 return tiocsti(tty, p);
2724 return tiocgwinsz(real_tty, p);
2726 return tiocswinsz(real_tty, p);
2728 return real_tty != tty ? -EINVAL : tioccons(file);
2730 set_bit(TTY_EXCLUSIVE, &tty->flags);
2733 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2737 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2738 return put_user(excl, (int __user *)p);
2741 return tiocgetd(tty, p);
2743 return tiocsetd(tty, p);
2745 if (!capable(CAP_SYS_ADMIN))
2751 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2752 return put_user(ret, (unsigned int __user *)p);
2757 case TIOCSBRK: /* Turn break on, unconditionally */
2758 if (tty->ops->break_ctl)
2759 return tty->ops->break_ctl(tty, -1);
2761 case TIOCCBRK: /* Turn break off, unconditionally */
2762 if (tty->ops->break_ctl)
2763 return tty->ops->break_ctl(tty, 0);
2765 case TCSBRK: /* SVID version: non-zero arg --> no break */
2766 /* non-zero arg means wait for all output data
2767 * to be sent (performed above) but don't send break.
2768 * This is used by the tcdrain() termios function.
2771 return send_break(tty, 250);
2773 case TCSBRKP: /* support for POSIX tcsendbreak() */
2774 return send_break(tty, arg ? arg*100 : 250);
2777 return tty_tiocmget(tty, p);
2781 return tty_tiocmset(tty, cmd, p);
2783 return tty_tiocgicount(tty, p);
2788 /* flush tty buffer and allow ldisc to process ioctl */
2789 tty_buffer_flush(tty, NULL);
2794 return tty_tiocsserial(tty, p);
2796 return tty_tiocgserial(tty, p);
2798 /* Special because the struct file is needed */
2799 return ptm_open_peer(file, tty, (int)arg);
2801 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2802 if (retval != -ENOIOCTLCMD)
2805 if (tty->ops->ioctl) {
2806 retval = tty->ops->ioctl(tty, cmd, arg);
2807 if (retval != -ENOIOCTLCMD)
2810 ld = tty_ldisc_ref_wait(tty);
2812 return hung_up_tty_ioctl(file, cmd, arg);
2814 if (ld->ops->ioctl) {
2815 retval = ld->ops->ioctl(tty, file, cmd, arg);
2816 if (retval == -ENOIOCTLCMD)
2819 tty_ldisc_deref(ld);
2823 #ifdef CONFIG_COMPAT
2825 struct serial_struct32 {
2831 compat_int_t xmit_fifo_size;
2832 compat_int_t custom_divisor;
2833 compat_int_t baud_base;
2834 unsigned short close_delay;
2838 unsigned short closing_wait; /* time to wait before closing */
2839 unsigned short closing_wait2; /* no longer used... */
2840 compat_uint_t iomem_base;
2841 unsigned short iomem_reg_shift;
2842 unsigned int port_high;
2843 /* compat_ulong_t iomap_base FIXME */
2844 compat_int_t reserved;
2847 static int compat_tty_tiocsserial(struct tty_struct *tty,
2848 struct serial_struct32 __user *ss)
2850 struct serial_struct32 v32;
2851 struct serial_struct v;
2853 if (copy_from_user(&v32, ss, sizeof(*ss)))
2856 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2857 v.iomem_base = compat_ptr(v32.iomem_base);
2858 v.iomem_reg_shift = v32.iomem_reg_shift;
2859 v.port_high = v32.port_high;
2862 return tty_set_serial(tty, &v);
2865 static int compat_tty_tiocgserial(struct tty_struct *tty,
2866 struct serial_struct32 __user *ss)
2868 struct serial_struct32 v32;
2869 struct serial_struct v;
2872 memset(&v, 0, sizeof(v));
2873 memset(&v32, 0, sizeof(v32));
2875 if (!tty->ops->get_serial)
2877 err = tty->ops->get_serial(tty, &v);
2879 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2880 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2881 0xfffffff : ptr_to_compat(v.iomem_base);
2882 v32.iomem_reg_shift = v.iomem_reg_shift;
2883 v32.port_high = v.port_high;
2884 if (copy_to_user(ss, &v32, sizeof(v32)))
2889 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2892 struct tty_struct *tty = file_tty(file);
2893 struct tty_ldisc *ld;
2894 int retval = -ENOIOCTLCMD;
2943 case TIOCGLCKTRMIOS:
2944 case TIOCSLCKTRMIOS:
2956 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2972 return tty_ioctl(file, cmd, arg);
2975 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2980 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2982 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2984 if (tty->ops->compat_ioctl) {
2985 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2986 if (retval != -ENOIOCTLCMD)
2990 ld = tty_ldisc_ref_wait(tty);
2992 return hung_up_tty_compat_ioctl(file, cmd, arg);
2993 if (ld->ops->compat_ioctl)
2994 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2995 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2996 retval = ld->ops->ioctl(tty, file,
2997 (unsigned long)compat_ptr(cmd), arg);
2998 tty_ldisc_deref(ld);
3004 static int this_tty(const void *t, struct file *file, unsigned fd)
3006 if (likely(file->f_op->read_iter != tty_read))
3008 return file_tty(file) != t ? 0 : fd + 1;
3012 * This implements the "Secure Attention Key" --- the idea is to
3013 * prevent trojan horses by killing all processes associated with this
3014 * tty when the user hits the "Secure Attention Key". Required for
3015 * super-paranoid applications --- see the Orange Book for more details.
3017 * This code could be nicer; ideally it should send a HUP, wait a few
3018 * seconds, then send a INT, and then a KILL signal. But you then
3019 * have to coordinate with the init process, since all processes associated
3020 * with the current tty must be dead before the new getty is allowed
3023 * Now, if it would be correct ;-/ The current code has a nasty hole -
3024 * it doesn't catch files in flight. We may send the descriptor to ourselves
3025 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3027 * Nasty bug: do_SAK is being called in interrupt context. This can
3028 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3030 void __do_SAK(struct tty_struct *tty)
3035 struct task_struct *g, *p;
3036 struct pid *session;
3038 unsigned long flags;
3043 spin_lock_irqsave(&tty->ctrl_lock, flags);
3044 session = get_pid(tty->session);
3045 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3047 tty_ldisc_flush(tty);
3049 tty_driver_flush_buffer(tty);
3051 read_lock(&tasklist_lock);
3052 /* Kill the entire session */
3053 do_each_pid_task(session, PIDTYPE_SID, p) {
3054 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3055 task_pid_nr(p), p->comm);
3056 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3057 } while_each_pid_task(session, PIDTYPE_SID, p);
3059 /* Now kill any processes that happen to have the tty open */
3060 do_each_thread(g, p) {
3061 if (p->signal->tty == tty) {
3062 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3063 task_pid_nr(p), p->comm);
3064 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3068 i = iterate_fd(p->files, 0, this_tty, tty);
3070 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3071 task_pid_nr(p), p->comm, i - 1);
3072 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3075 } while_each_thread(g, p);
3076 read_unlock(&tasklist_lock);
3081 static void do_SAK_work(struct work_struct *work)
3083 struct tty_struct *tty =
3084 container_of(work, struct tty_struct, SAK_work);
3089 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3090 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3091 * the values which we write to it will be identical to the values which it
3092 * already has. --akpm
3094 void do_SAK(struct tty_struct *tty)
3098 schedule_work(&tty->SAK_work);
3101 EXPORT_SYMBOL(do_SAK);
3103 /* Must put_device() after it's unused! */
3104 static struct device *tty_get_device(struct tty_struct *tty)
3106 dev_t devt = tty_devnum(tty);
3107 return class_find_device_by_devt(tty_class, devt);
3114 * This subroutine allocates and initializes a tty structure.
3116 * Locking: none - tty in question is not exposed at this point
3119 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3121 struct tty_struct *tty;
3123 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3127 kref_init(&tty->kref);
3128 tty->magic = TTY_MAGIC;
3129 if (tty_ldisc_init(tty)) {
3133 tty->session = NULL;
3135 mutex_init(&tty->legacy_mutex);
3136 mutex_init(&tty->throttle_mutex);
3137 init_rwsem(&tty->termios_rwsem);
3138 mutex_init(&tty->winsize_mutex);
3139 init_ldsem(&tty->ldisc_sem);
3140 init_waitqueue_head(&tty->write_wait);
3141 init_waitqueue_head(&tty->read_wait);
3142 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3143 mutex_init(&tty->atomic_write_lock);
3144 spin_lock_init(&tty->ctrl_lock);
3145 spin_lock_init(&tty->flow_lock);
3146 spin_lock_init(&tty->files_lock);
3147 INIT_LIST_HEAD(&tty->tty_files);
3148 INIT_WORK(&tty->SAK_work, do_SAK_work);
3150 tty->driver = driver;
3151 tty->ops = driver->ops;
3153 tty_line_name(driver, idx, tty->name);
3154 tty->dev = tty_get_device(tty);
3160 * tty_put_char - write one character to a tty
3164 * Write one byte to the tty using the provided put_char method
3165 * if present. Returns the number of characters successfully output.
3167 * Note: the specific put_char operation in the driver layer may go
3168 * away soon. Don't call it directly, use this method
3171 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3173 if (tty->ops->put_char)
3174 return tty->ops->put_char(tty, ch);
3175 return tty->ops->write(tty, &ch, 1);
3177 EXPORT_SYMBOL_GPL(tty_put_char);
3179 struct class *tty_class;
3181 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3182 unsigned int index, unsigned int count)
3186 /* init here, since reused cdevs cause crashes */
3187 driver->cdevs[index] = cdev_alloc();
3188 if (!driver->cdevs[index])
3190 driver->cdevs[index]->ops = &tty_fops;
3191 driver->cdevs[index]->owner = driver->owner;
3192 err = cdev_add(driver->cdevs[index], dev, count);
3194 kobject_put(&driver->cdevs[index]->kobj);
3199 * tty_register_device - register a tty device
3200 * @driver: the tty driver that describes the tty device
3201 * @index: the index in the tty driver for this tty device
3202 * @device: a struct device that is associated with this tty device.
3203 * This field is optional, if there is no known struct device
3204 * for this tty device it can be set to NULL safely.
3206 * Returns a pointer to the struct device for this tty device
3207 * (or ERR_PTR(-EFOO) on error).
3209 * This call is required to be made to register an individual tty device
3210 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3211 * that bit is not set, this function should not be called by a tty
3217 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3218 struct device *device)
3220 return tty_register_device_attr(driver, index, device, NULL, NULL);
3222 EXPORT_SYMBOL(tty_register_device);
3224 static void tty_device_create_release(struct device *dev)
3226 dev_dbg(dev, "releasing...\n");
3231 * tty_register_device_attr - register a tty device
3232 * @driver: the tty driver that describes the tty device
3233 * @index: the index in the tty driver for this tty device
3234 * @device: a struct device that is associated with this tty device.
3235 * This field is optional, if there is no known struct device
3236 * for this tty device it can be set to NULL safely.
3237 * @drvdata: Driver data to be set to device.
3238 * @attr_grp: Attribute group to be set on device.
3240 * Returns a pointer to the struct device for this tty device
3241 * (or ERR_PTR(-EFOO) on error).
3243 * This call is required to be made to register an individual tty device
3244 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3245 * that bit is not set, this function should not be called by a tty
3250 struct device *tty_register_device_attr(struct tty_driver *driver,
3251 unsigned index, struct device *device,
3253 const struct attribute_group **attr_grp)
3256 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3257 struct ktermios *tp;
3261 if (index >= driver->num) {
3262 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3263 driver->name, index);
3264 return ERR_PTR(-EINVAL);
3267 if (driver->type == TTY_DRIVER_TYPE_PTY)
3268 pty_line_name(driver, index, name);
3270 tty_line_name(driver, index, name);
3272 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3274 return ERR_PTR(-ENOMEM);
3277 dev->class = tty_class;
3278 dev->parent = device;
3279 dev->release = tty_device_create_release;
3280 dev_set_name(dev, "%s", name);
3281 dev->groups = attr_grp;
3282 dev_set_drvdata(dev, drvdata);
3284 dev_set_uevent_suppress(dev, 1);
3286 retval = device_register(dev);
3290 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3292 * Free any saved termios data so that the termios state is
3293 * reset when reusing a minor number.
3295 tp = driver->termios[index];
3297 driver->termios[index] = NULL;
3301 retval = tty_cdev_add(driver, devt, index, 1);
3306 dev_set_uevent_suppress(dev, 0);
3307 kobject_uevent(&dev->kobj, KOBJ_ADD);
3316 return ERR_PTR(retval);
3318 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3321 * tty_unregister_device - unregister a tty device
3322 * @driver: the tty driver that describes the tty device
3323 * @index: the index in the tty driver for this tty device
3325 * If a tty device is registered with a call to tty_register_device() then
3326 * this function must be called when the tty device is gone.
3331 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3333 device_destroy(tty_class,
3334 MKDEV(driver->major, driver->minor_start) + index);
3335 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3336 cdev_del(driver->cdevs[index]);
3337 driver->cdevs[index] = NULL;
3340 EXPORT_SYMBOL(tty_unregister_device);
3343 * __tty_alloc_driver -- allocate tty driver
3344 * @lines: count of lines this driver can handle at most
3345 * @owner: module which is responsible for this driver
3346 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3348 * This should not be called directly, some of the provided macros should be
3349 * used instead. Use IS_ERR and friends on @retval.
3351 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3352 unsigned long flags)
3354 struct tty_driver *driver;
3355 unsigned int cdevs = 1;
3358 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3359 return ERR_PTR(-EINVAL);
3361 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3363 return ERR_PTR(-ENOMEM);
3365 kref_init(&driver->kref);
3366 driver->magic = TTY_DRIVER_MAGIC;
3367 driver->num = lines;
3368 driver->owner = owner;
3369 driver->flags = flags;
3371 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3372 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3374 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3376 if (!driver->ttys || !driver->termios) {
3382 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3383 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3385 if (!driver->ports) {
3392 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3393 if (!driver->cdevs) {
3400 kfree(driver->ports);
3401 kfree(driver->ttys);
3402 kfree(driver->termios);
3403 kfree(driver->cdevs);
3405 return ERR_PTR(err);
3407 EXPORT_SYMBOL(__tty_alloc_driver);
3409 static void destruct_tty_driver(struct kref *kref)
3411 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3413 struct ktermios *tp;
3415 if (driver->flags & TTY_DRIVER_INSTALLED) {
3416 for (i = 0; i < driver->num; i++) {
3417 tp = driver->termios[i];
3419 driver->termios[i] = NULL;
3422 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3423 tty_unregister_device(driver, i);
3425 proc_tty_unregister_driver(driver);
3426 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3427 cdev_del(driver->cdevs[0]);
3429 kfree(driver->cdevs);
3430 kfree(driver->ports);
3431 kfree(driver->termios);
3432 kfree(driver->ttys);
3436 void tty_driver_kref_put(struct tty_driver *driver)
3438 kref_put(&driver->kref, destruct_tty_driver);
3440 EXPORT_SYMBOL(tty_driver_kref_put);
3442 void tty_set_operations(struct tty_driver *driver,
3443 const struct tty_operations *op)
3447 EXPORT_SYMBOL(tty_set_operations);
3449 void put_tty_driver(struct tty_driver *d)
3451 tty_driver_kref_put(d);
3453 EXPORT_SYMBOL(put_tty_driver);
3456 * Called by a tty driver to register itself.
3458 int tty_register_driver(struct tty_driver *driver)
3465 if (!driver->major) {
3466 error = alloc_chrdev_region(&dev, driver->minor_start,
3467 driver->num, driver->name);
3469 driver->major = MAJOR(dev);
3470 driver->minor_start = MINOR(dev);
3473 dev = MKDEV(driver->major, driver->minor_start);
3474 error = register_chrdev_region(dev, driver->num, driver->name);
3479 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3480 error = tty_cdev_add(driver, dev, 0, driver->num);
3482 goto err_unreg_char;
3485 mutex_lock(&tty_mutex);
3486 list_add(&driver->tty_drivers, &tty_drivers);
3487 mutex_unlock(&tty_mutex);
3489 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3490 for (i = 0; i < driver->num; i++) {
3491 d = tty_register_device(driver, i, NULL);
3494 goto err_unreg_devs;
3498 proc_tty_register_driver(driver);
3499 driver->flags |= TTY_DRIVER_INSTALLED;
3503 for (i--; i >= 0; i--)
3504 tty_unregister_device(driver, i);
3506 mutex_lock(&tty_mutex);
3507 list_del(&driver->tty_drivers);
3508 mutex_unlock(&tty_mutex);
3511 unregister_chrdev_region(dev, driver->num);
3515 EXPORT_SYMBOL(tty_register_driver);
3518 * Called by a tty driver to unregister itself.
3520 void tty_unregister_driver(struct tty_driver *driver)
3522 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3524 mutex_lock(&tty_mutex);
3525 list_del(&driver->tty_drivers);
3526 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);