1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
7 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
8 * or rs-channels. It also implements echoing, cooked mode etc.
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
12 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
13 * tty_struct and tty_queue structures. Previously there was an array
14 * of 256 tty_struct's which was statically allocated, and the
15 * tty_queue structures were allocated at boot time. Both are now
16 * dynamically allocated only when the tty is open.
18 * Also restructured routines so that there is more of a separation
19 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
20 * the low-level tty routines (serial.c, pty.c, console.c). This
21 * makes for cleaner and more compact code. -TYT, 9/17/92
23 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
24 * which can be dynamically activated and de-activated by the line
25 * discipline handling modules (like SLIP).
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
31 * Added functionality to the OPOST tty handling. No delays, but all
32 * other bits should be there.
33 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
47 * Move console and virtual terminal code to more appropriate files,
48 * implement CONFIG_VT and generalize console device interface.
49 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
63 * Move do_SAK() into process context. Less stack use in devfs functions.
64 * alloc_tty_struct() always uses kmalloc()
65 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
68 #include <linux/types.h>
69 #include <linux/major.h>
70 #include <linux/errno.h>
71 #include <linux/signal.h>
72 #include <linux/fcntl.h>
73 #include <linux/sched/signal.h>
74 #include <linux/sched/task.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/ppp-ioctl.h>
91 #include <linux/proc_fs.h>
92 #include <linux/init.h>
93 #include <linux/module.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
99 #include <linux/serial.h>
100 #include <linux/ratelimit.h>
101 #include <linux/compat.h>
103 #include <linux/uaccess.h>
105 #include <linux/kbd_kern.h>
106 #include <linux/vt_kern.h>
107 #include <linux/selection.h>
109 #include <linux/kmod.h>
110 #include <linux/nsproxy.h>
112 #undef TTY_DEBUG_HANGUP
113 #ifdef TTY_DEBUG_HANGUP
114 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
116 # define tty_debug_hangup(tty, f, args...) do { } while (0)
119 #define TTY_PARANOIA_CHECK 1
120 #define CHECK_TTY_COUNT 1
122 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
123 .c_iflag = ICRNL | IXON,
124 .c_oflag = OPOST | ONLCR,
125 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
126 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
127 ECHOCTL | ECHOKE | IEXTEN,
131 /* .c_line = N_TTY, */
134 EXPORT_SYMBOL(tty_std_termios);
136 /* This list gets poked at by procfs and various bits of boot up code. This
137 could do with some rationalisation such as pulling the tty proc function
140 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
142 /* Mutex to protect creating and releasing a tty */
143 DEFINE_MUTEX(tty_mutex);
145 static ssize_t tty_read(struct kiocb *, struct iov_iter *);
146 static ssize_t tty_write(struct kiocb *, struct iov_iter *);
147 static __poll_t tty_poll(struct file *, poll_table *);
148 static int tty_open(struct inode *, struct file *);
150 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
153 #define tty_compat_ioctl NULL
155 static int __tty_fasync(int fd, struct file *filp, int on);
156 static int tty_fasync(int fd, struct file *filp, int on);
157 static void release_tty(struct tty_struct *tty, int idx);
160 * free_tty_struct - free a disused tty
161 * @tty: tty struct to free
163 * Free the write buffers, tty queue and tty memory itself.
165 * Locking: none. Must be called after tty is definitely unused
168 static void free_tty_struct(struct tty_struct *tty)
170 tty_ldisc_deinit(tty);
171 put_device(tty->dev);
172 kfree(tty->write_buf);
173 tty->magic = 0xDEADDEAD;
177 static inline struct tty_struct *file_tty(struct file *file)
179 return ((struct tty_file_private *)file->private_data)->tty;
182 int tty_alloc_file(struct file *file)
184 struct tty_file_private *priv;
186 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
190 file->private_data = priv;
195 /* Associate a new file with the tty structure */
196 void tty_add_file(struct tty_struct *tty, struct file *file)
198 struct tty_file_private *priv = file->private_data;
203 spin_lock(&tty->files_lock);
204 list_add(&priv->list, &tty->tty_files);
205 spin_unlock(&tty->files_lock);
209 * tty_free_file - free file->private_data
211 * This shall be used only for fail path handling when tty_add_file was not
214 void tty_free_file(struct file *file)
216 struct tty_file_private *priv = file->private_data;
218 file->private_data = NULL;
222 /* Delete file from its tty */
223 static void tty_del_file(struct file *file)
225 struct tty_file_private *priv = file->private_data;
226 struct tty_struct *tty = priv->tty;
228 spin_lock(&tty->files_lock);
229 list_del(&priv->list);
230 spin_unlock(&tty->files_lock);
235 * tty_name - return tty naming
236 * @tty: tty structure
238 * Convert a tty structure into a name. The name reflects the kernel
239 * naming policy and if udev is in use may not reflect user space
244 const char *tty_name(const struct tty_struct *tty)
246 if (!tty) /* Hmm. NULL pointer. That's fun. */
251 EXPORT_SYMBOL(tty_name);
253 const char *tty_driver_name(const struct tty_struct *tty)
255 if (!tty || !tty->driver)
257 return tty->driver->name;
260 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
263 #ifdef TTY_PARANOIA_CHECK
265 pr_warn("(%d:%d): %s: NULL tty\n",
266 imajor(inode), iminor(inode), routine);
269 if (tty->magic != TTY_MAGIC) {
270 pr_warn("(%d:%d): %s: bad magic number\n",
271 imajor(inode), iminor(inode), routine);
278 /* Caller must hold tty_lock */
279 static int check_tty_count(struct tty_struct *tty, const char *routine)
281 #ifdef CHECK_TTY_COUNT
283 int count = 0, kopen_count = 0;
285 spin_lock(&tty->files_lock);
286 list_for_each(p, &tty->tty_files) {
289 spin_unlock(&tty->files_lock);
290 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
291 tty->driver->subtype == PTY_TYPE_SLAVE &&
292 tty->link && tty->link->count)
294 if (tty_port_kopened(tty->port))
296 if (tty->count != (count + kopen_count)) {
297 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
298 routine, tty->count, count, kopen_count);
299 return (count + kopen_count);
306 * get_tty_driver - find device of a tty
307 * @device: device identifier
308 * @index: returns the index of the tty
310 * This routine returns a tty driver structure, given a device number
311 * and also passes back the index number.
313 * Locking: caller must hold tty_mutex
316 static struct tty_driver *get_tty_driver(dev_t device, int *index)
318 struct tty_driver *p;
320 list_for_each_entry(p, &tty_drivers, tty_drivers) {
321 dev_t base = MKDEV(p->major, p->minor_start);
322 if (device < base || device >= base + p->num)
324 *index = device - base;
325 return tty_driver_kref_get(p);
331 * tty_dev_name_to_number - return dev_t for device name
332 * @name: user space name of device under /dev
333 * @number: pointer to dev_t that this function will populate
335 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
336 * like (4, 64) or (188, 1). If no corresponding driver is registered then
337 * the function returns -ENODEV.
339 * Locking: this acquires tty_mutex to protect the tty_drivers list from
340 * being modified while we are traversing it, and makes sure to
341 * release it before exiting.
343 int tty_dev_name_to_number(const char *name, dev_t *number)
345 struct tty_driver *p;
347 int index, prefix_length = 0;
350 for (str = name; *str && !isdigit(*str); str++)
356 ret = kstrtoint(str, 10, &index);
360 prefix_length = str - name;
361 mutex_lock(&tty_mutex);
363 list_for_each_entry(p, &tty_drivers, tty_drivers)
364 if (prefix_length == strlen(p->name) && strncmp(name,
365 p->name, prefix_length) == 0) {
366 if (index < p->num) {
367 *number = MKDEV(p->major, p->minor_start + index);
372 /* if here then driver wasn't found */
375 mutex_unlock(&tty_mutex);
378 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
380 #ifdef CONFIG_CONSOLE_POLL
383 * tty_find_polling_driver - find device of a polled tty
384 * @name: name string to match
385 * @line: pointer to resulting tty line nr
387 * This routine returns a tty driver structure, given a name
388 * and the condition that the tty driver is capable of polled
391 struct tty_driver *tty_find_polling_driver(char *name, int *line)
393 struct tty_driver *p, *res = NULL;
398 for (str = name; *str; str++)
399 if ((*str >= '0' && *str <= '9') || *str == ',')
405 tty_line = simple_strtoul(str, &str, 10);
407 mutex_lock(&tty_mutex);
408 /* Search through the tty devices to look for a match */
409 list_for_each_entry(p, &tty_drivers, tty_drivers) {
410 if (!len || strncmp(name, p->name, len) != 0)
418 if (tty_line >= 0 && tty_line < p->num && p->ops &&
419 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
420 res = tty_driver_kref_get(p);
425 mutex_unlock(&tty_mutex);
429 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
432 static ssize_t hung_up_tty_read(struct kiocb *iocb, struct iov_iter *to)
437 static ssize_t hung_up_tty_write(struct kiocb *iocb, struct iov_iter *from)
442 /* No kernel lock held - none needed ;) */
443 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
445 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
448 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
451 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
454 static long hung_up_tty_compat_ioctl(struct file *file,
455 unsigned int cmd, unsigned long arg)
457 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
460 static int hung_up_tty_fasync(int fd, struct file *file, int on)
465 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
467 struct tty_struct *tty = file_tty(file);
469 if (tty && tty->ops && tty->ops->show_fdinfo)
470 tty->ops->show_fdinfo(tty, m);
473 static const struct file_operations tty_fops = {
475 .read_iter = tty_read,
476 .write_iter = tty_write,
477 .splice_read = generic_file_splice_read,
478 .splice_write = iter_file_splice_write,
480 .unlocked_ioctl = tty_ioctl,
481 .compat_ioctl = tty_compat_ioctl,
483 .release = tty_release,
484 .fasync = tty_fasync,
485 .show_fdinfo = tty_show_fdinfo,
488 static const struct file_operations console_fops = {
490 .read_iter = tty_read,
491 .write_iter = redirected_tty_write,
492 .splice_read = generic_file_splice_read,
493 .splice_write = iter_file_splice_write,
495 .unlocked_ioctl = tty_ioctl,
496 .compat_ioctl = tty_compat_ioctl,
498 .release = tty_release,
499 .fasync = tty_fasync,
502 static const struct file_operations hung_up_tty_fops = {
504 .read_iter = hung_up_tty_read,
505 .write_iter = hung_up_tty_write,
506 .poll = hung_up_tty_poll,
507 .unlocked_ioctl = hung_up_tty_ioctl,
508 .compat_ioctl = hung_up_tty_compat_ioctl,
509 .release = tty_release,
510 .fasync = hung_up_tty_fasync,
513 static DEFINE_SPINLOCK(redirect_lock);
514 static struct file *redirect;
516 extern void tty_sysctl_init(void);
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_hangup - actual handler for hangup events
548 * This can be called by a "kworker" kernel thread. That is process
549 * synchronous but doesn't hold any locks, so we need to make sure we
550 * have the appropriate locks for what we're doing.
552 * The hangup event clears any pending redirections onto the hung up
553 * device. It ensures future writes will error and it does the needed
554 * line discipline hangup and signal delivery. The tty object itself
559 * redirect lock for undoing redirection
560 * file list lock for manipulating list of ttys
561 * tty_ldiscs_lock from called functions
562 * termios_rwsem resetting termios data
563 * tasklist_lock to walk task list for hangup event
564 * ->siglock to protect ->signal/->sighand
566 static void __tty_hangup(struct tty_struct *tty, int exit_session)
568 struct file *cons_filp = NULL;
569 struct file *filp, *f = NULL;
570 struct tty_file_private *priv;
571 int closecount = 0, n;
578 spin_lock(&redirect_lock);
579 if (redirect && file_tty(redirect) == tty) {
583 spin_unlock(&redirect_lock);
587 if (test_bit(TTY_HUPPED, &tty->flags)) {
593 * Some console devices aren't actually hung up for technical and
594 * historical reasons, which can lead to indefinite interruptible
595 * sleep in n_tty_read(). The following explicitly tells
596 * n_tty_read() to abort readers.
598 set_bit(TTY_HUPPING, &tty->flags);
600 /* inuse_filps is protected by the single tty lock,
601 this really needs to change if we want to flush the
602 workqueue with the lock held */
603 check_tty_count(tty, "tty_hangup");
605 spin_lock(&tty->files_lock);
606 /* This breaks for file handles being sent over AF_UNIX sockets ? */
607 list_for_each_entry(priv, &tty->tty_files, list) {
609 if (filp->f_op->write_iter == redirected_tty_write)
611 if (filp->f_op->write_iter != tty_write)
614 __tty_fasync(-1, filp, 0); /* can't block */
615 filp->f_op = &hung_up_tty_fops;
617 spin_unlock(&tty->files_lock);
619 refs = tty_signal_session_leader(tty, exit_session);
620 /* Account for the p->signal references we killed */
624 tty_ldisc_hangup(tty, cons_filp != NULL);
626 spin_lock_irq(&tty->ctrl_lock);
627 clear_bit(TTY_THROTTLED, &tty->flags);
628 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
629 put_pid(tty->session);
633 tty->ctrl_status = 0;
634 spin_unlock_irq(&tty->ctrl_lock);
637 * If one of the devices matches a console pointer, we
638 * cannot just call hangup() because that will cause
639 * tty->count and state->count to go out of sync.
640 * So we just call close() the right number of times.
644 for (n = 0; n < closecount; n++)
645 tty->ops->close(tty, cons_filp);
646 } else if (tty->ops->hangup)
647 tty->ops->hangup(tty);
649 * We don't want to have driver/ldisc interactions beyond the ones
650 * we did here. The driver layer expects no calls after ->hangup()
651 * from the ldisc side, which is now guaranteed.
653 set_bit(TTY_HUPPED, &tty->flags);
654 clear_bit(TTY_HUPPING, &tty->flags);
661 static void do_tty_hangup(struct work_struct *work)
663 struct tty_struct *tty =
664 container_of(work, struct tty_struct, hangup_work);
666 __tty_hangup(tty, 0);
670 * tty_hangup - trigger a hangup event
671 * @tty: tty to hangup
673 * A carrier loss (virtual or otherwise) has occurred on this like
674 * schedule a hangup sequence to run after this event.
677 void tty_hangup(struct tty_struct *tty)
679 tty_debug_hangup(tty, "hangup\n");
680 schedule_work(&tty->hangup_work);
683 EXPORT_SYMBOL(tty_hangup);
686 * tty_vhangup - process vhangup
687 * @tty: tty to hangup
689 * The user has asked via system call for the terminal to be hung up.
690 * We do this synchronously so that when the syscall returns the process
691 * is complete. That guarantee is necessary for security reasons.
694 void tty_vhangup(struct tty_struct *tty)
696 tty_debug_hangup(tty, "vhangup\n");
697 __tty_hangup(tty, 0);
700 EXPORT_SYMBOL(tty_vhangup);
704 * tty_vhangup_self - process vhangup for own ctty
706 * Perform a vhangup on the current controlling tty
709 void tty_vhangup_self(void)
711 struct tty_struct *tty;
713 tty = get_current_tty();
721 * tty_vhangup_session - hangup session leader exit
722 * @tty: tty to hangup
724 * The session leader is exiting and hanging up its controlling terminal.
725 * Every process in the foreground process group is signalled SIGHUP.
727 * We do this synchronously so that when the syscall returns the process
728 * is complete. That guarantee is necessary for security reasons.
731 void tty_vhangup_session(struct tty_struct *tty)
733 tty_debug_hangup(tty, "session hangup\n");
734 __tty_hangup(tty, 1);
738 * tty_hung_up_p - was tty hung up
739 * @filp: file pointer of tty
741 * Return true if the tty has been subject to a vhangup or a carrier
745 int tty_hung_up_p(struct file *filp)
747 return (filp && filp->f_op == &hung_up_tty_fops);
750 EXPORT_SYMBOL(tty_hung_up_p);
753 * stop_tty - propagate flow control
756 * Perform flow control to the driver. May be called
757 * on an already stopped device and will not re-call the driver
760 * This functionality is used by both the line disciplines for
761 * halting incoming flow and by the driver. It may therefore be
762 * called from any context, may be under the tty atomic_write_lock
769 void __stop_tty(struct tty_struct *tty)
778 void stop_tty(struct tty_struct *tty)
782 spin_lock_irqsave(&tty->flow_lock, flags);
784 spin_unlock_irqrestore(&tty->flow_lock, flags);
786 EXPORT_SYMBOL(stop_tty);
789 * start_tty - propagate flow control
792 * Start a tty that has been stopped if at all possible. If this
793 * tty was previous stopped and is now being started, the driver
794 * start method is invoked and the line discipline woken.
800 void __start_tty(struct tty_struct *tty)
802 if (!tty->stopped || tty->flow_stopped)
806 tty->ops->start(tty);
810 void start_tty(struct tty_struct *tty)
814 spin_lock_irqsave(&tty->flow_lock, flags);
816 spin_unlock_irqrestore(&tty->flow_lock, flags);
818 EXPORT_SYMBOL(start_tty);
820 static void tty_update_time(struct timespec64 *time)
822 time64_t sec = ktime_get_real_seconds();
825 * We only care if the two values differ in anything other than the
826 * lower three bits (i.e every 8 seconds). If so, then we can update
827 * the time of the tty device, otherwise it could be construded as a
828 * security leak to let userspace know the exact timing of the tty.
830 if ((sec ^ time->tv_sec) & ~7)
835 * Iterate on the ldisc ->read() function until we've gotten all
836 * the data the ldisc has for us.
838 * The "cookie" is something that the ldisc read function can fill
839 * in to let us know that there is more data to be had.
841 * We promise to continue to call the ldisc until it stops returning
842 * data or clears the cookie. The cookie may be something that the
843 * ldisc maintains state for and needs to free.
845 static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
846 struct file *file, struct iov_iter *to)
850 unsigned long offset = 0;
852 size_t count = iov_iter_count(to);
857 size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
858 size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
863 /* Did we have an earlier error (ie -EFAULT)? */
869 * -EOVERFLOW means we didn't have enough space
870 * for a whole packet, and we shouldn't return
873 if (retval == -EOVERFLOW)
878 copied = copy_to_iter(kernel_buf, size, to);
883 * If the user copy failed, we still need to do another ->read()
884 * call if we had a cookie to let the ldisc clear up.
886 * But make sure size is zeroed.
888 if (unlikely(copied != size)) {
894 /* We always clear tty buffer in case they contained passwords */
895 memzero_explicit(kernel_buf, sizeof(kernel_buf));
896 return offset ? offset : retval;
901 * tty_read - read method for tty device files
902 * @file: pointer to tty file
904 * @count: size of user buffer
907 * Perform the read system call function on this terminal device. Checks
908 * for hung up devices before calling the line discipline method.
911 * Locks the line discipline internally while needed. Multiple
912 * read calls may be outstanding in parallel.
915 static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
918 struct file *file = iocb->ki_filp;
919 struct inode *inode = file_inode(file);
920 struct tty_struct *tty = file_tty(file);
921 struct tty_ldisc *ld;
923 if (tty_paranoia_check(tty, inode, "tty_read"))
925 if (!tty || tty_io_error(tty))
928 /* We want to wait for the line discipline to sort out in this
930 ld = tty_ldisc_ref_wait(tty);
932 return hung_up_tty_read(iocb, to);
935 i = iterate_tty_read(ld, tty, file, to);
939 tty_update_time(&inode->i_atime);
944 static void tty_write_unlock(struct tty_struct *tty)
946 mutex_unlock(&tty->atomic_write_lock);
947 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
950 static int tty_write_lock(struct tty_struct *tty, int ndelay)
952 if (!mutex_trylock(&tty->atomic_write_lock)) {
955 if (mutex_lock_interruptible(&tty->atomic_write_lock))
962 * Split writes up in sane blocksizes to avoid
963 * denial-of-service type attacks
965 static inline ssize_t do_tty_write(
966 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
967 struct tty_struct *tty,
969 struct iov_iter *from)
971 size_t count = iov_iter_count(from);
972 ssize_t ret, written = 0;
975 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
980 * We chunk up writes into a temporary buffer. This
981 * simplifies low-level drivers immensely, since they
982 * don't have locking issues and user mode accesses.
984 * But if TTY_NO_WRITE_SPLIT is set, we should use a
987 * The default chunk-size is 2kB, because the NTTY
988 * layer has problems with bigger chunks. It will
989 * claim to be able to handle more characters than
992 * FIXME: This can probably go away now except that 64K chunks
993 * are too likely to fail unless switched to vmalloc...
996 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1001 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1002 if (tty->write_cnt < chunk) {
1003 unsigned char *buf_chunk;
1008 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1013 kfree(tty->write_buf);
1014 tty->write_cnt = chunk;
1015 tty->write_buf = buf_chunk;
1018 /* Do the write .. */
1020 size_t size = count;
1025 if (copy_from_iter(tty->write_buf, size, from) != size)
1028 ret = write(tty, file, tty->write_buf, size);
1036 /* FIXME! Have Al check this! */
1038 iov_iter_revert(from, size-ret);
1044 if (signal_pending(current))
1049 tty_update_time(&file_inode(file)->i_mtime);
1053 tty_write_unlock(tty);
1058 * tty_write_message - write a message to a certain tty, not just the console.
1059 * @tty: the destination tty_struct
1060 * @msg: the message to write
1062 * This is used for messages that need to be redirected to a specific tty.
1063 * We don't put it into the syslog queue right now maybe in the future if
1066 * We must still hold the BTM and test the CLOSING flag for the moment.
1069 void tty_write_message(struct tty_struct *tty, char *msg)
1072 mutex_lock(&tty->atomic_write_lock);
1074 if (tty->ops->write && tty->count > 0)
1075 tty->ops->write(tty, msg, strlen(msg));
1077 tty_write_unlock(tty);
1084 * tty_write - write method for tty device file
1085 * @file: tty file pointer
1086 * @buf: user data to write
1087 * @count: bytes to write
1090 * Write data to a tty device via the line discipline.
1093 * Locks the line discipline as required
1094 * Writes to the tty driver are serialized by the atomic_write_lock
1095 * and are then processed in chunks to the device. The line discipline
1096 * write method will not be invoked in parallel for each device.
1099 static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
1101 struct tty_struct *tty = file_tty(file);
1102 struct tty_ldisc *ld;
1105 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1107 if (!tty || !tty->ops->write || tty_io_error(tty))
1109 /* Short term debug to catch buggy drivers */
1110 if (tty->ops->write_room == NULL)
1111 tty_err(tty, "missing write_room method\n");
1112 ld = tty_ldisc_ref_wait(tty);
1114 return hung_up_tty_write(iocb, from);
1115 if (!ld->ops->write)
1118 ret = do_tty_write(ld->ops->write, tty, file, from);
1119 tty_ldisc_deref(ld);
1123 static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
1125 return file_tty_write(iocb->ki_filp, iocb, from);
1128 ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
1130 struct file *p = NULL;
1132 spin_lock(&redirect_lock);
1134 p = get_file(redirect);
1135 spin_unlock(&redirect_lock);
1138 * We know the redirected tty is just another tty, we can can
1139 * call file_tty_write() directly with that file pointer.
1143 res = file_tty_write(p, iocb, iter);
1147 return tty_write(iocb, iter);
1151 * tty_send_xchar - send priority character
1153 * Send a high priority character to the tty even if stopped
1155 * Locking: none for xchar method, write ordering for write method.
1158 int tty_send_xchar(struct tty_struct *tty, char ch)
1160 int was_stopped = tty->stopped;
1162 if (tty->ops->send_xchar) {
1163 down_read(&tty->termios_rwsem);
1164 tty->ops->send_xchar(tty, ch);
1165 up_read(&tty->termios_rwsem);
1169 if (tty_write_lock(tty, 0) < 0)
1170 return -ERESTARTSYS;
1172 down_read(&tty->termios_rwsem);
1175 tty->ops->write(tty, &ch, 1);
1178 up_read(&tty->termios_rwsem);
1179 tty_write_unlock(tty);
1183 static char ptychar[] = "pqrstuvwxyzabcde";
1186 * pty_line_name - generate name for a pty
1187 * @driver: the tty driver in use
1188 * @index: the minor number
1189 * @p: output buffer of at least 6 bytes
1191 * Generate a name from a driver reference and write it to the output
1196 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1198 int i = index + driver->name_base;
1199 /* ->name is initialized to "ttyp", but "tty" is expected */
1200 sprintf(p, "%s%c%x",
1201 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1202 ptychar[i >> 4 & 0xf], i & 0xf);
1206 * tty_line_name - generate name for a tty
1207 * @driver: the tty driver in use
1208 * @index: the minor number
1209 * @p: output buffer of at least 7 bytes
1211 * Generate a name from a driver reference and write it to the output
1216 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1218 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1219 return sprintf(p, "%s", driver->name);
1221 return sprintf(p, "%s%d", driver->name,
1222 index + driver->name_base);
1226 * tty_driver_lookup_tty() - find an existing tty, if any
1227 * @driver: the driver for the tty
1228 * @idx: the minor number
1230 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1231 * driver lookup() method returns an error.
1233 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1235 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1236 struct file *file, int idx)
1238 struct tty_struct *tty;
1240 if (driver->ops->lookup)
1242 tty = ERR_PTR(-EIO);
1244 tty = driver->ops->lookup(driver, file, idx);
1246 tty = driver->ttys[idx];
1254 * tty_init_termios - helper for termios setup
1255 * @tty: the tty to set up
1257 * Initialise the termios structure for this tty. This runs under
1258 * the tty_mutex currently so we can be relaxed about ordering.
1261 void tty_init_termios(struct tty_struct *tty)
1263 struct ktermios *tp;
1264 int idx = tty->index;
1266 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1267 tty->termios = tty->driver->init_termios;
1269 /* Check for lazy saved data */
1270 tp = tty->driver->termios[idx];
1273 tty->termios.c_line = tty->driver->init_termios.c_line;
1275 tty->termios = tty->driver->init_termios;
1277 /* Compatibility until drivers always set this */
1278 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1279 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1281 EXPORT_SYMBOL_GPL(tty_init_termios);
1283 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1285 tty_init_termios(tty);
1286 tty_driver_kref_get(driver);
1288 driver->ttys[tty->index] = tty;
1291 EXPORT_SYMBOL_GPL(tty_standard_install);
1294 * tty_driver_install_tty() - install a tty entry in the driver
1295 * @driver: the driver for the tty
1298 * Install a tty object into the driver tables. The tty->index field
1299 * will be set by the time this is called. This method is responsible
1300 * for ensuring any need additional structures are allocated and
1303 * Locking: tty_mutex for now
1305 static int tty_driver_install_tty(struct tty_driver *driver,
1306 struct tty_struct *tty)
1308 return driver->ops->install ? driver->ops->install(driver, tty) :
1309 tty_standard_install(driver, tty);
1313 * tty_driver_remove_tty() - remove a tty from the driver tables
1314 * @driver: the driver for the tty
1315 * @tty: tty to remove
1317 * Remvoe a tty object from the driver tables. The tty->index field
1318 * will be set by the time this is called.
1320 * Locking: tty_mutex for now
1322 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1324 if (driver->ops->remove)
1325 driver->ops->remove(driver, tty);
1327 driver->ttys[tty->index] = NULL;
1331 * tty_reopen() - fast re-open of an open tty
1332 * @tty: the tty to open
1334 * Return 0 on success, -errno on error.
1335 * Re-opens on master ptys are not allowed and return -EIO.
1337 * Locking: Caller must hold tty_lock
1339 static int tty_reopen(struct tty_struct *tty)
1341 struct tty_driver *driver = tty->driver;
1342 struct tty_ldisc *ld;
1345 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1346 driver->subtype == PTY_TYPE_MASTER)
1352 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1355 ld = tty_ldisc_ref_wait(tty);
1357 tty_ldisc_deref(ld);
1359 retval = tty_ldisc_lock(tty, 5 * HZ);
1364 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1365 tty_ldisc_unlock(tty);
1375 * tty_init_dev - initialise a tty device
1376 * @driver: tty driver we are opening a device on
1377 * @idx: device index
1379 * Prepare a tty device. This may not be a "new" clean device but
1380 * could also be an active device. The pty drivers require special
1381 * handling because of this.
1384 * The function is called under the tty_mutex, which
1385 * protects us from the tty struct or driver itself going away.
1387 * On exit the tty device has the line discipline attached and
1388 * a reference count of 1. If a pair was created for pty/tty use
1389 * and the other was a pty master then it too has a reference count of 1.
1391 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1392 * failed open. The new code protects the open with a mutex, so it's
1393 * really quite straightforward. The mutex locking can probably be
1394 * relaxed for the (most common) case of reopening a tty.
1396 * Return: returned tty structure
1399 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1401 struct tty_struct *tty;
1405 * First time open is complex, especially for PTY devices.
1406 * This code guarantees that either everything succeeds and the
1407 * TTY is ready for operation, or else the table slots are vacated
1408 * and the allocated memory released. (Except that the termios
1412 if (!try_module_get(driver->owner))
1413 return ERR_PTR(-ENODEV);
1415 tty = alloc_tty_struct(driver, idx);
1418 goto err_module_put;
1422 retval = tty_driver_install_tty(driver, tty);
1427 tty->port = driver->ports[idx];
1429 if (WARN_RATELIMIT(!tty->port,
1430 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1431 __func__, tty->driver->name)) {
1433 goto err_release_lock;
1436 retval = tty_ldisc_lock(tty, 5 * HZ);
1438 goto err_release_lock;
1439 tty->port->itty = tty;
1442 * Structures all installed ... call the ldisc open routines.
1443 * If we fail here just call release_tty to clean up. No need
1444 * to decrement the use counts, as release_tty doesn't care.
1446 retval = tty_ldisc_setup(tty, tty->link);
1448 goto err_release_tty;
1449 tty_ldisc_unlock(tty);
1450 /* Return the tty locked so that it cannot vanish under the caller */
1455 free_tty_struct(tty);
1457 module_put(driver->owner);
1458 return ERR_PTR(retval);
1460 /* call the tty release_tty routine to clean out this slot */
1462 tty_ldisc_unlock(tty);
1463 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1467 release_tty(tty, idx);
1468 return ERR_PTR(retval);
1472 * tty_save_termios() - save tty termios data in driver table
1473 * @tty: tty whose termios data to save
1475 * Locking: Caller guarantees serialisation with tty_init_termios().
1477 void tty_save_termios(struct tty_struct *tty)
1479 struct ktermios *tp;
1480 int idx = tty->index;
1482 /* If the port is going to reset then it has no termios to save */
1483 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1486 /* Stash the termios data */
1487 tp = tty->driver->termios[idx];
1489 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1492 tty->driver->termios[idx] = tp;
1496 EXPORT_SYMBOL_GPL(tty_save_termios);
1499 * tty_flush_works - flush all works of a tty/pty pair
1500 * @tty: tty device to flush works for (or either end of a pty pair)
1502 * Sync flush all works belonging to @tty (and the 'other' tty).
1504 static void tty_flush_works(struct tty_struct *tty)
1506 flush_work(&tty->SAK_work);
1507 flush_work(&tty->hangup_work);
1509 flush_work(&tty->link->SAK_work);
1510 flush_work(&tty->link->hangup_work);
1515 * release_one_tty - release tty structure memory
1516 * @work: work of tty we are obliterating
1518 * Releases memory associated with a tty structure, and clears out the
1519 * driver table slots. This function is called when a device is no longer
1520 * in use. It also gets called when setup of a device fails.
1523 * takes the file list lock internally when working on the list
1524 * of ttys that the driver keeps.
1526 * This method gets called from a work queue so that the driver private
1527 * cleanup ops can sleep (needed for USB at least)
1529 static void release_one_tty(struct work_struct *work)
1531 struct tty_struct *tty =
1532 container_of(work, struct tty_struct, hangup_work);
1533 struct tty_driver *driver = tty->driver;
1534 struct module *owner = driver->owner;
1536 if (tty->ops->cleanup)
1537 tty->ops->cleanup(tty);
1540 tty_driver_kref_put(driver);
1543 spin_lock(&tty->files_lock);
1544 list_del_init(&tty->tty_files);
1545 spin_unlock(&tty->files_lock);
1548 put_pid(tty->session);
1549 free_tty_struct(tty);
1552 static void queue_release_one_tty(struct kref *kref)
1554 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1556 /* The hangup queue is now free so we can reuse it rather than
1557 waste a chunk of memory for each port */
1558 INIT_WORK(&tty->hangup_work, release_one_tty);
1559 schedule_work(&tty->hangup_work);
1563 * tty_kref_put - release a tty kref
1566 * Release a reference to a tty device and if need be let the kref
1567 * layer destruct the object for us
1570 void tty_kref_put(struct tty_struct *tty)
1573 kref_put(&tty->kref, queue_release_one_tty);
1575 EXPORT_SYMBOL(tty_kref_put);
1578 * release_tty - release tty structure memory
1580 * Release both @tty and a possible linked partner (think pty pair),
1581 * and decrement the refcount of the backing module.
1585 * takes the file list lock internally when working on the list
1586 * of ttys that the driver keeps.
1589 static void release_tty(struct tty_struct *tty, int idx)
1591 /* This should always be true but check for the moment */
1592 WARN_ON(tty->index != idx);
1593 WARN_ON(!mutex_is_locked(&tty_mutex));
1594 if (tty->ops->shutdown)
1595 tty->ops->shutdown(tty);
1596 tty_save_termios(tty);
1597 tty_driver_remove_tty(tty->driver, tty);
1599 tty->port->itty = NULL;
1601 tty->link->port->itty = NULL;
1603 tty_buffer_cancel_work(tty->port);
1605 tty_buffer_cancel_work(tty->link->port);
1607 tty_kref_put(tty->link);
1612 * tty_release_checks - check a tty before real release
1613 * @tty: tty to check
1614 * @idx: index of the tty
1616 * Performs some paranoid checking before true release of the @tty.
1617 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1619 static int tty_release_checks(struct tty_struct *tty, int idx)
1621 #ifdef TTY_PARANOIA_CHECK
1622 if (idx < 0 || idx >= tty->driver->num) {
1623 tty_debug(tty, "bad idx %d\n", idx);
1627 /* not much to check for devpts */
1628 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1631 if (tty != tty->driver->ttys[idx]) {
1632 tty_debug(tty, "bad driver table[%d] = %p\n",
1633 idx, tty->driver->ttys[idx]);
1636 if (tty->driver->other) {
1637 struct tty_struct *o_tty = tty->link;
1639 if (o_tty != tty->driver->other->ttys[idx]) {
1640 tty_debug(tty, "bad other table[%d] = %p\n",
1641 idx, tty->driver->other->ttys[idx]);
1644 if (o_tty->link != tty) {
1645 tty_debug(tty, "bad link = %p\n", o_tty->link);
1654 * tty_kclose - closes tty opened by tty_kopen
1657 * Performs the final steps to release and free a tty device. It is the
1658 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1659 * flag on tty->port.
1661 void tty_kclose(struct tty_struct *tty)
1664 * Ask the line discipline code to release its structures
1666 tty_ldisc_release(tty);
1668 /* Wait for pending work before tty destruction commmences */
1669 tty_flush_works(tty);
1671 tty_debug_hangup(tty, "freeing structure\n");
1673 * The release_tty function takes care of the details of clearing
1674 * the slots and preserving the termios structure.
1676 mutex_lock(&tty_mutex);
1677 tty_port_set_kopened(tty->port, 0);
1678 release_tty(tty, tty->index);
1679 mutex_unlock(&tty_mutex);
1681 EXPORT_SYMBOL_GPL(tty_kclose);
1684 * tty_release_struct - release a tty struct
1686 * @idx: index of the tty
1688 * Performs the final steps to release and free a tty device. It is
1689 * roughly the reverse of tty_init_dev.
1691 void tty_release_struct(struct tty_struct *tty, int idx)
1694 * Ask the line discipline code to release its structures
1696 tty_ldisc_release(tty);
1698 /* Wait for pending work before tty destruction commmences */
1699 tty_flush_works(tty);
1701 tty_debug_hangup(tty, "freeing structure\n");
1703 * The release_tty function takes care of the details of clearing
1704 * the slots and preserving the termios structure.
1706 mutex_lock(&tty_mutex);
1707 release_tty(tty, idx);
1708 mutex_unlock(&tty_mutex);
1710 EXPORT_SYMBOL_GPL(tty_release_struct);
1713 * tty_release - vfs callback for close
1714 * @inode: inode of tty
1715 * @filp: file pointer for handle to tty
1717 * Called the last time each file handle is closed that references
1718 * this tty. There may however be several such references.
1721 * Takes bkl. See tty_release_dev
1723 * Even releasing the tty structures is a tricky business.. We have
1724 * to be very careful that the structures are all released at the
1725 * same time, as interrupts might otherwise get the wrong pointers.
1727 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1728 * lead to double frees or releasing memory still in use.
1731 int tty_release(struct inode *inode, struct file *filp)
1733 struct tty_struct *tty = file_tty(filp);
1734 struct tty_struct *o_tty = NULL;
1735 int do_sleep, final;
1740 if (tty_paranoia_check(tty, inode, __func__))
1744 check_tty_count(tty, __func__);
1746 __tty_fasync(-1, filp, 0);
1749 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1750 tty->driver->subtype == PTY_TYPE_MASTER)
1753 if (tty_release_checks(tty, idx)) {
1758 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1760 if (tty->ops->close)
1761 tty->ops->close(tty, filp);
1763 /* If tty is pty master, lock the slave pty (stable lock order) */
1764 tty_lock_slave(o_tty);
1767 * Sanity check: if tty->count is going to zero, there shouldn't be
1768 * any waiters on tty->read_wait or tty->write_wait. We test the
1769 * wait queues and kick everyone out _before_ actually starting to
1770 * close. This ensures that we won't block while releasing the tty
1773 * The test for the o_tty closing is necessary, since the master and
1774 * slave sides may close in any order. If the slave side closes out
1775 * first, its count will be one, since the master side holds an open.
1776 * Thus this test wouldn't be triggered at the time the slave closed,
1782 if (tty->count <= 1) {
1783 if (waitqueue_active(&tty->read_wait)) {
1784 wake_up_poll(&tty->read_wait, EPOLLIN);
1787 if (waitqueue_active(&tty->write_wait)) {
1788 wake_up_poll(&tty->write_wait, EPOLLOUT);
1792 if (o_tty && o_tty->count <= 1) {
1793 if (waitqueue_active(&o_tty->read_wait)) {
1794 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1797 if (waitqueue_active(&o_tty->write_wait)) {
1798 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1807 tty_warn(tty, "read/write wait queue active!\n");
1809 schedule_timeout_killable(timeout);
1810 if (timeout < 120 * HZ)
1811 timeout = 2 * timeout + 1;
1813 timeout = MAX_SCHEDULE_TIMEOUT;
1817 if (--o_tty->count < 0) {
1818 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1822 if (--tty->count < 0) {
1823 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1828 * We've decremented tty->count, so we need to remove this file
1829 * descriptor off the tty->tty_files list; this serves two
1831 * - check_tty_count sees the correct number of file descriptors
1832 * associated with this tty.
1833 * - do_tty_hangup no longer sees this file descriptor as
1834 * something that needs to be handled for hangups.
1839 * Perform some housekeeping before deciding whether to return.
1841 * If _either_ side is closing, make sure there aren't any
1842 * processes that still think tty or o_tty is their controlling
1846 read_lock(&tasklist_lock);
1847 session_clear_tty(tty->session);
1849 session_clear_tty(o_tty->session);
1850 read_unlock(&tasklist_lock);
1853 /* check whether both sides are closing ... */
1854 final = !tty->count && !(o_tty && o_tty->count);
1856 tty_unlock_slave(o_tty);
1859 /* At this point, the tty->count == 0 should ensure a dead tty
1860 cannot be re-opened by a racing opener */
1865 tty_debug_hangup(tty, "final close\n");
1867 tty_release_struct(tty, idx);
1872 * tty_open_current_tty - get locked tty of current task
1873 * @device: device number
1874 * @filp: file pointer to tty
1875 * @return: locked tty of the current task iff @device is /dev/tty
1877 * Performs a re-open of the current task's controlling tty.
1879 * We cannot return driver and index like for the other nodes because
1880 * devpts will not work then. It expects inodes to be from devpts FS.
1882 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1884 struct tty_struct *tty;
1887 if (device != MKDEV(TTYAUX_MAJOR, 0))
1890 tty = get_current_tty();
1892 return ERR_PTR(-ENXIO);
1894 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1897 tty_kref_put(tty); /* safe to drop the kref now */
1899 retval = tty_reopen(tty);
1902 tty = ERR_PTR(retval);
1908 * tty_lookup_driver - lookup a tty driver for a given device file
1909 * @device: device number
1910 * @filp: file pointer to tty
1911 * @index: index for the device in the @return driver
1912 * @return: driver for this inode (with increased refcount)
1914 * If @return is not erroneous, the caller is responsible to decrement the
1915 * refcount by tty_driver_kref_put.
1917 * Locking: tty_mutex protects get_tty_driver
1919 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1922 struct tty_driver *driver = NULL;
1926 case MKDEV(TTY_MAJOR, 0): {
1927 extern struct tty_driver *console_driver;
1928 driver = tty_driver_kref_get(console_driver);
1929 *index = fg_console;
1933 case MKDEV(TTYAUX_MAJOR, 1): {
1934 struct tty_driver *console_driver = console_device(index);
1935 if (console_driver) {
1936 driver = tty_driver_kref_get(console_driver);
1937 if (driver && filp) {
1938 /* Don't let /dev/console block */
1939 filp->f_flags |= O_NONBLOCK;
1944 tty_driver_kref_put(driver);
1945 return ERR_PTR(-ENODEV);
1948 driver = get_tty_driver(device, index);
1950 return ERR_PTR(-ENODEV);
1957 * tty_kopen - open a tty device for kernel
1958 * @device: dev_t of device to open
1960 * Opens tty exclusively for kernel. Performs the driver lookup,
1961 * makes sure it's not already opened and performs the first-time
1962 * tty initialization.
1964 * Returns the locked initialized &tty_struct
1966 * Claims the global tty_mutex to serialize:
1967 * - concurrent first-time tty initialization
1968 * - concurrent tty driver removal w/ lookup
1969 * - concurrent tty removal from driver table
1971 struct tty_struct *tty_kopen(dev_t device)
1973 struct tty_struct *tty;
1974 struct tty_driver *driver;
1977 mutex_lock(&tty_mutex);
1978 driver = tty_lookup_driver(device, NULL, &index);
1979 if (IS_ERR(driver)) {
1980 mutex_unlock(&tty_mutex);
1981 return ERR_CAST(driver);
1984 /* check whether we're reopening an existing tty */
1985 tty = tty_driver_lookup_tty(driver, NULL, index);
1990 /* drop kref from tty_driver_lookup_tty() */
1992 tty = ERR_PTR(-EBUSY);
1993 } else { /* tty_init_dev returns tty with the tty_lock held */
1994 tty = tty_init_dev(driver, index);
1997 tty_port_set_kopened(tty->port, 1);
2000 mutex_unlock(&tty_mutex);
2001 tty_driver_kref_put(driver);
2004 EXPORT_SYMBOL_GPL(tty_kopen);
2007 * tty_open_by_driver - open a tty device
2008 * @device: dev_t of device to open
2009 * @filp: file pointer to tty
2011 * Performs the driver lookup, checks for a reopen, or otherwise
2012 * performs the first-time tty initialization.
2014 * Returns the locked initialized or re-opened &tty_struct
2016 * Claims the global tty_mutex to serialize:
2017 * - concurrent first-time tty initialization
2018 * - concurrent tty driver removal w/ lookup
2019 * - concurrent tty removal from driver table
2021 static struct tty_struct *tty_open_by_driver(dev_t device,
2024 struct tty_struct *tty;
2025 struct tty_driver *driver = NULL;
2029 mutex_lock(&tty_mutex);
2030 driver = tty_lookup_driver(device, filp, &index);
2031 if (IS_ERR(driver)) {
2032 mutex_unlock(&tty_mutex);
2033 return ERR_CAST(driver);
2036 /* check whether we're reopening an existing tty */
2037 tty = tty_driver_lookup_tty(driver, filp, index);
2039 mutex_unlock(&tty_mutex);
2044 if (tty_port_kopened(tty->port)) {
2046 mutex_unlock(&tty_mutex);
2047 tty = ERR_PTR(-EBUSY);
2050 mutex_unlock(&tty_mutex);
2051 retval = tty_lock_interruptible(tty);
2052 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
2054 if (retval == -EINTR)
2055 retval = -ERESTARTSYS;
2056 tty = ERR_PTR(retval);
2059 retval = tty_reopen(tty);
2062 tty = ERR_PTR(retval);
2064 } else { /* Returns with the tty_lock held for now */
2065 tty = tty_init_dev(driver, index);
2066 mutex_unlock(&tty_mutex);
2069 tty_driver_kref_put(driver);
2074 * tty_open - open a tty device
2075 * @inode: inode of device file
2076 * @filp: file pointer to tty
2078 * tty_open and tty_release keep up the tty count that contains the
2079 * number of opens done on a tty. We cannot use the inode-count, as
2080 * different inodes might point to the same tty.
2082 * Open-counting is needed for pty masters, as well as for keeping
2083 * track of serial lines: DTR is dropped when the last close happens.
2084 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2086 * The termios state of a pty is reset on first open so that
2087 * settings don't persist across reuse.
2089 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2090 * tty->count should protect the rest.
2091 * ->siglock protects ->signal/->sighand
2093 * Note: the tty_unlock/lock cases without a ref are only safe due to
2097 static int tty_open(struct inode *inode, struct file *filp)
2099 struct tty_struct *tty;
2101 dev_t device = inode->i_rdev;
2102 unsigned saved_flags = filp->f_flags;
2104 nonseekable_open(inode, filp);
2107 retval = tty_alloc_file(filp);
2111 tty = tty_open_current_tty(device, filp);
2113 tty = tty_open_by_driver(device, filp);
2116 tty_free_file(filp);
2117 retval = PTR_ERR(tty);
2118 if (retval != -EAGAIN || signal_pending(current))
2124 tty_add_file(tty, filp);
2126 check_tty_count(tty, __func__);
2127 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2130 retval = tty->ops->open(tty, filp);
2133 filp->f_flags = saved_flags;
2136 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2138 tty_unlock(tty); /* need to call tty_release without BTM */
2139 tty_release(inode, filp);
2140 if (retval != -ERESTARTSYS)
2143 if (signal_pending(current))
2148 * Need to reset f_op in case a hangup happened.
2150 if (tty_hung_up_p(filp))
2151 filp->f_op = &tty_fops;
2154 clear_bit(TTY_HUPPED, &tty->flags);
2156 noctty = (filp->f_flags & O_NOCTTY) ||
2157 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2158 device == MKDEV(TTYAUX_MAJOR, 1) ||
2159 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2160 tty->driver->subtype == PTY_TYPE_MASTER);
2162 tty_open_proc_set_tty(filp, tty);
2170 * tty_poll - check tty status
2171 * @filp: file being polled
2172 * @wait: poll wait structures to update
2174 * Call the line discipline polling method to obtain the poll
2175 * status of the device.
2177 * Locking: locks called line discipline but ldisc poll method
2178 * may be re-entered freely by other callers.
2181 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2183 struct tty_struct *tty = file_tty(filp);
2184 struct tty_ldisc *ld;
2187 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2190 ld = tty_ldisc_ref_wait(tty);
2192 return hung_up_tty_poll(filp, wait);
2194 ret = ld->ops->poll(tty, filp, wait);
2195 tty_ldisc_deref(ld);
2199 static int __tty_fasync(int fd, struct file *filp, int on)
2201 struct tty_struct *tty = file_tty(filp);
2202 unsigned long flags;
2205 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2208 retval = fasync_helper(fd, filp, on, &tty->fasync);
2216 spin_lock_irqsave(&tty->ctrl_lock, flags);
2219 type = PIDTYPE_PGID;
2221 pid = task_pid(current);
2222 type = PIDTYPE_TGID;
2225 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2226 __f_setown(filp, pid, type, 0);
2234 static int tty_fasync(int fd, struct file *filp, int on)
2236 struct tty_struct *tty = file_tty(filp);
2237 int retval = -ENOTTY;
2240 if (!tty_hung_up_p(filp))
2241 retval = __tty_fasync(fd, filp, on);
2248 * tiocsti - fake input character
2249 * @tty: tty to fake input into
2250 * @p: pointer to character
2252 * Fake input to a tty device. Does the necessary locking and
2255 * FIXME: does not honour flow control ??
2258 * Called functions take tty_ldiscs_lock
2259 * current->signal->tty check is safe without locks
2262 static int tiocsti(struct tty_struct *tty, char __user *p)
2265 struct tty_ldisc *ld;
2267 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2269 if (get_user(ch, p))
2271 tty_audit_tiocsti(tty, ch);
2272 ld = tty_ldisc_ref_wait(tty);
2275 tty_buffer_lock_exclusive(tty->port);
2276 if (ld->ops->receive_buf)
2277 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2278 tty_buffer_unlock_exclusive(tty->port);
2279 tty_ldisc_deref(ld);
2284 * tiocgwinsz - implement window query ioctl
2286 * @arg: user buffer for result
2288 * Copies the kernel idea of the window size into the user buffer.
2290 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2294 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2298 mutex_lock(&tty->winsize_mutex);
2299 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2300 mutex_unlock(&tty->winsize_mutex);
2302 return err ? -EFAULT: 0;
2306 * tty_do_resize - resize event
2307 * @tty: tty being resized
2308 * @ws: new dimensions
2310 * Update the termios variables and send the necessary signals to
2311 * peform a terminal resize correctly
2314 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2319 mutex_lock(&tty->winsize_mutex);
2320 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2323 /* Signal the foreground process group */
2324 pgrp = tty_get_pgrp(tty);
2326 kill_pgrp(pgrp, SIGWINCH, 1);
2331 mutex_unlock(&tty->winsize_mutex);
2334 EXPORT_SYMBOL(tty_do_resize);
2337 * tiocswinsz - implement window size set ioctl
2338 * @tty: tty side of tty
2339 * @arg: user buffer for result
2341 * Copies the user idea of the window size to the kernel. Traditionally
2342 * this is just advisory information but for the Linux console it
2343 * actually has driver level meaning and triggers a VC resize.
2346 * Driver dependent. The default do_resize method takes the
2347 * tty termios mutex and ctrl_lock. The console takes its own lock
2348 * then calls into the default method.
2351 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2353 struct winsize tmp_ws;
2354 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2357 if (tty->ops->resize)
2358 return tty->ops->resize(tty, &tmp_ws);
2360 return tty_do_resize(tty, &tmp_ws);
2364 * tioccons - allow admin to move logical console
2365 * @file: the file to become console
2367 * Allow the administrator to move the redirected console device
2369 * Locking: uses redirect_lock to guard the redirect information
2372 static int tioccons(struct file *file)
2374 if (!capable(CAP_SYS_ADMIN))
2376 if (file->f_op->write_iter == redirected_tty_write) {
2378 spin_lock(&redirect_lock);
2381 spin_unlock(&redirect_lock);
2386 if (file->f_op->write_iter != tty_write)
2388 if (!(file->f_mode & FMODE_WRITE))
2390 if (!(file->f_mode & FMODE_CAN_WRITE))
2392 spin_lock(&redirect_lock);
2394 spin_unlock(&redirect_lock);
2397 redirect = get_file(file);
2398 spin_unlock(&redirect_lock);
2403 * tiocsetd - set line discipline
2405 * @p: pointer to user data
2407 * Set the line discipline according to user request.
2409 * Locking: see tty_set_ldisc, this function is just a helper
2412 static int tiocsetd(struct tty_struct *tty, int __user *p)
2417 if (get_user(disc, p))
2420 ret = tty_set_ldisc(tty, disc);
2426 * tiocgetd - get line discipline
2428 * @p: pointer to user data
2430 * Retrieves the line discipline id directly from the ldisc.
2432 * Locking: waits for ldisc reference (in case the line discipline
2433 * is changing or the tty is being hungup)
2436 static int tiocgetd(struct tty_struct *tty, int __user *p)
2438 struct tty_ldisc *ld;
2441 ld = tty_ldisc_ref_wait(tty);
2444 ret = put_user(ld->ops->num, p);
2445 tty_ldisc_deref(ld);
2450 * send_break - performed time break
2451 * @tty: device to break on
2452 * @duration: timeout in mS
2454 * Perform a timed break on hardware that lacks its own driver level
2455 * timed break functionality.
2458 * atomic_write_lock serializes
2462 static int send_break(struct tty_struct *tty, unsigned int duration)
2466 if (tty->ops->break_ctl == NULL)
2469 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2470 retval = tty->ops->break_ctl(tty, duration);
2472 /* Do the work ourselves */
2473 if (tty_write_lock(tty, 0) < 0)
2475 retval = tty->ops->break_ctl(tty, -1);
2478 if (!signal_pending(current))
2479 msleep_interruptible(duration);
2480 retval = tty->ops->break_ctl(tty, 0);
2482 tty_write_unlock(tty);
2483 if (signal_pending(current))
2490 * tty_tiocmget - get modem status
2492 * @p: pointer to result
2494 * Obtain the modem status bits from the tty driver if the feature
2495 * is supported. Return -ENOTTY if it is not available.
2497 * Locking: none (up to the driver)
2500 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2502 int retval = -ENOTTY;
2504 if (tty->ops->tiocmget) {
2505 retval = tty->ops->tiocmget(tty);
2508 retval = put_user(retval, p);
2514 * tty_tiocmset - set modem status
2516 * @cmd: command - clear bits, set bits or set all
2517 * @p: pointer to desired bits
2519 * Set the modem status bits from the tty driver if the feature
2520 * is supported. Return -ENOTTY if it is not available.
2522 * Locking: none (up to the driver)
2525 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2529 unsigned int set, clear, val;
2531 if (tty->ops->tiocmset == NULL)
2534 retval = get_user(val, p);
2550 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2551 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2552 return tty->ops->tiocmset(tty, set, clear);
2555 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2557 int retval = -EINVAL;
2558 struct serial_icounter_struct icount;
2559 memset(&icount, 0, sizeof(icount));
2560 if (tty->ops->get_icount)
2561 retval = tty->ops->get_icount(tty, &icount);
2564 if (copy_to_user(arg, &icount, sizeof(icount)))
2569 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2571 static DEFINE_RATELIMIT_STATE(depr_flags,
2572 DEFAULT_RATELIMIT_INTERVAL,
2573 DEFAULT_RATELIMIT_BURST);
2574 char comm[TASK_COMM_LEN];
2575 struct serial_struct v;
2578 if (copy_from_user(&v, ss, sizeof(*ss)))
2581 flags = v.flags & ASYNC_DEPRECATED;
2583 if (flags && __ratelimit(&depr_flags))
2584 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2585 __func__, get_task_comm(comm, current), flags);
2586 if (!tty->ops->set_serial)
2588 return tty->ops->set_serial(tty, &v);
2591 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2593 struct serial_struct v;
2596 memset(&v, 0, sizeof(v));
2597 if (!tty->ops->get_serial)
2599 err = tty->ops->get_serial(tty, &v);
2600 if (!err && copy_to_user(ss, &v, sizeof(v)))
2606 * if pty, return the slave side (real_tty)
2607 * otherwise, return self
2609 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2611 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2612 tty->driver->subtype == PTY_TYPE_MASTER)
2618 * Split this up, as gcc can choke on it otherwise..
2620 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2622 struct tty_struct *tty = file_tty(file);
2623 struct tty_struct *real_tty;
2624 void __user *p = (void __user *)arg;
2626 struct tty_ldisc *ld;
2628 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2631 real_tty = tty_pair_get_tty(tty);
2634 * Factor out some common prep work
2642 retval = tty_check_change(tty);
2645 if (cmd != TIOCCBRK) {
2646 tty_wait_until_sent(tty, 0);
2647 if (signal_pending(current))
2658 return tiocsti(tty, p);
2660 return tiocgwinsz(real_tty, p);
2662 return tiocswinsz(real_tty, p);
2664 return real_tty != tty ? -EINVAL : tioccons(file);
2666 set_bit(TTY_EXCLUSIVE, &tty->flags);
2669 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2673 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2674 return put_user(excl, (int __user *)p);
2677 return tiocgetd(tty, p);
2679 return tiocsetd(tty, p);
2681 if (!capable(CAP_SYS_ADMIN))
2687 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2688 return put_user(ret, (unsigned int __user *)p);
2693 case TIOCSBRK: /* Turn break on, unconditionally */
2694 if (tty->ops->break_ctl)
2695 return tty->ops->break_ctl(tty, -1);
2697 case TIOCCBRK: /* Turn break off, unconditionally */
2698 if (tty->ops->break_ctl)
2699 return tty->ops->break_ctl(tty, 0);
2701 case TCSBRK: /* SVID version: non-zero arg --> no break */
2702 /* non-zero arg means wait for all output data
2703 * to be sent (performed above) but don't send break.
2704 * This is used by the tcdrain() termios function.
2707 return send_break(tty, 250);
2709 case TCSBRKP: /* support for POSIX tcsendbreak() */
2710 return send_break(tty, arg ? arg*100 : 250);
2713 return tty_tiocmget(tty, p);
2717 return tty_tiocmset(tty, cmd, p);
2719 return tty_tiocgicount(tty, p);
2724 /* flush tty buffer and allow ldisc to process ioctl */
2725 tty_buffer_flush(tty, NULL);
2730 return tty_tiocsserial(tty, p);
2732 return tty_tiocgserial(tty, p);
2734 /* Special because the struct file is needed */
2735 return ptm_open_peer(file, tty, (int)arg);
2737 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2738 if (retval != -ENOIOCTLCMD)
2741 if (tty->ops->ioctl) {
2742 retval = tty->ops->ioctl(tty, cmd, arg);
2743 if (retval != -ENOIOCTLCMD)
2746 ld = tty_ldisc_ref_wait(tty);
2748 return hung_up_tty_ioctl(file, cmd, arg);
2750 if (ld->ops->ioctl) {
2751 retval = ld->ops->ioctl(tty, file, cmd, arg);
2752 if (retval == -ENOIOCTLCMD)
2755 tty_ldisc_deref(ld);
2759 #ifdef CONFIG_COMPAT
2761 struct serial_struct32 {
2767 compat_int_t xmit_fifo_size;
2768 compat_int_t custom_divisor;
2769 compat_int_t baud_base;
2770 unsigned short close_delay;
2774 unsigned short closing_wait; /* time to wait before closing */
2775 unsigned short closing_wait2; /* no longer used... */
2776 compat_uint_t iomem_base;
2777 unsigned short iomem_reg_shift;
2778 unsigned int port_high;
2779 /* compat_ulong_t iomap_base FIXME */
2780 compat_int_t reserved;
2783 static int compat_tty_tiocsserial(struct tty_struct *tty,
2784 struct serial_struct32 __user *ss)
2786 static DEFINE_RATELIMIT_STATE(depr_flags,
2787 DEFAULT_RATELIMIT_INTERVAL,
2788 DEFAULT_RATELIMIT_BURST);
2789 char comm[TASK_COMM_LEN];
2790 struct serial_struct32 v32;
2791 struct serial_struct v;
2794 if (copy_from_user(&v32, ss, sizeof(*ss)))
2797 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2798 v.iomem_base = compat_ptr(v32.iomem_base);
2799 v.iomem_reg_shift = v32.iomem_reg_shift;
2800 v.port_high = v32.port_high;
2803 flags = v.flags & ASYNC_DEPRECATED;
2805 if (flags && __ratelimit(&depr_flags))
2806 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2807 __func__, get_task_comm(comm, current), flags);
2808 if (!tty->ops->set_serial)
2810 return tty->ops->set_serial(tty, &v);
2813 static int compat_tty_tiocgserial(struct tty_struct *tty,
2814 struct serial_struct32 __user *ss)
2816 struct serial_struct32 v32;
2817 struct serial_struct v;
2820 memset(&v, 0, sizeof(v));
2821 memset(&v32, 0, sizeof(v32));
2823 if (!tty->ops->get_serial)
2825 err = tty->ops->get_serial(tty, &v);
2827 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2828 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2829 0xfffffff : ptr_to_compat(v.iomem_base);
2830 v32.iomem_reg_shift = v.iomem_reg_shift;
2831 v32.port_high = v.port_high;
2832 if (copy_to_user(ss, &v32, sizeof(v32)))
2837 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2840 struct tty_struct *tty = file_tty(file);
2841 struct tty_ldisc *ld;
2842 int retval = -ENOIOCTLCMD;
2891 case TIOCGLCKTRMIOS:
2892 case TIOCSLCKTRMIOS:
2904 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2920 return tty_ioctl(file, cmd, arg);
2923 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2928 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2930 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2932 if (tty->ops->compat_ioctl) {
2933 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2934 if (retval != -ENOIOCTLCMD)
2938 ld = tty_ldisc_ref_wait(tty);
2940 return hung_up_tty_compat_ioctl(file, cmd, arg);
2941 if (ld->ops->compat_ioctl)
2942 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2943 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2944 retval = ld->ops->ioctl(tty, file,
2945 (unsigned long)compat_ptr(cmd), arg);
2946 tty_ldisc_deref(ld);
2952 static int this_tty(const void *t, struct file *file, unsigned fd)
2954 if (likely(file->f_op->read_iter != tty_read))
2956 return file_tty(file) != t ? 0 : fd + 1;
2960 * This implements the "Secure Attention Key" --- the idea is to
2961 * prevent trojan horses by killing all processes associated with this
2962 * tty when the user hits the "Secure Attention Key". Required for
2963 * super-paranoid applications --- see the Orange Book for more details.
2965 * This code could be nicer; ideally it should send a HUP, wait a few
2966 * seconds, then send a INT, and then a KILL signal. But you then
2967 * have to coordinate with the init process, since all processes associated
2968 * with the current tty must be dead before the new getty is allowed
2971 * Now, if it would be correct ;-/ The current code has a nasty hole -
2972 * it doesn't catch files in flight. We may send the descriptor to ourselves
2973 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2975 * Nasty bug: do_SAK is being called in interrupt context. This can
2976 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2978 void __do_SAK(struct tty_struct *tty)
2983 struct task_struct *g, *p;
2984 struct pid *session;
2986 unsigned long flags;
2991 spin_lock_irqsave(&tty->ctrl_lock, flags);
2992 session = get_pid(tty->session);
2993 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2995 tty_ldisc_flush(tty);
2997 tty_driver_flush_buffer(tty);
2999 read_lock(&tasklist_lock);
3000 /* Kill the entire session */
3001 do_each_pid_task(session, PIDTYPE_SID, p) {
3002 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3003 task_pid_nr(p), p->comm);
3004 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3005 } while_each_pid_task(session, PIDTYPE_SID, p);
3007 /* Now kill any processes that happen to have the tty open */
3008 do_each_thread(g, p) {
3009 if (p->signal->tty == tty) {
3010 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3011 task_pid_nr(p), p->comm);
3012 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3016 i = iterate_fd(p->files, 0, this_tty, tty);
3018 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3019 task_pid_nr(p), p->comm, i - 1);
3020 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
3023 } while_each_thread(g, p);
3024 read_unlock(&tasklist_lock);
3029 static void do_SAK_work(struct work_struct *work)
3031 struct tty_struct *tty =
3032 container_of(work, struct tty_struct, SAK_work);
3037 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3038 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3039 * the values which we write to it will be identical to the values which it
3040 * already has. --akpm
3042 void do_SAK(struct tty_struct *tty)
3046 schedule_work(&tty->SAK_work);
3049 EXPORT_SYMBOL(do_SAK);
3051 /* Must put_device() after it's unused! */
3052 static struct device *tty_get_device(struct tty_struct *tty)
3054 dev_t devt = tty_devnum(tty);
3055 return class_find_device_by_devt(tty_class, devt);
3062 * This subroutine allocates and initializes a tty structure.
3064 * Locking: none - tty in question is not exposed at this point
3067 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3069 struct tty_struct *tty;
3071 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3075 kref_init(&tty->kref);
3076 tty->magic = TTY_MAGIC;
3077 if (tty_ldisc_init(tty)) {
3081 tty->session = NULL;
3083 mutex_init(&tty->legacy_mutex);
3084 mutex_init(&tty->throttle_mutex);
3085 init_rwsem(&tty->termios_rwsem);
3086 mutex_init(&tty->winsize_mutex);
3087 init_ldsem(&tty->ldisc_sem);
3088 init_waitqueue_head(&tty->write_wait);
3089 init_waitqueue_head(&tty->read_wait);
3090 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3091 mutex_init(&tty->atomic_write_lock);
3092 spin_lock_init(&tty->ctrl_lock);
3093 spin_lock_init(&tty->flow_lock);
3094 spin_lock_init(&tty->files_lock);
3095 INIT_LIST_HEAD(&tty->tty_files);
3096 INIT_WORK(&tty->SAK_work, do_SAK_work);
3098 tty->driver = driver;
3099 tty->ops = driver->ops;
3101 tty_line_name(driver, idx, tty->name);
3102 tty->dev = tty_get_device(tty);
3108 * tty_put_char - write one character to a tty
3112 * Write one byte to the tty using the provided put_char method
3113 * if present. Returns the number of characters successfully output.
3115 * Note: the specific put_char operation in the driver layer may go
3116 * away soon. Don't call it directly, use this method
3119 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3121 if (tty->ops->put_char)
3122 return tty->ops->put_char(tty, ch);
3123 return tty->ops->write(tty, &ch, 1);
3125 EXPORT_SYMBOL_GPL(tty_put_char);
3127 struct class *tty_class;
3129 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3130 unsigned int index, unsigned int count)
3134 /* init here, since reused cdevs cause crashes */
3135 driver->cdevs[index] = cdev_alloc();
3136 if (!driver->cdevs[index])
3138 driver->cdevs[index]->ops = &tty_fops;
3139 driver->cdevs[index]->owner = driver->owner;
3140 err = cdev_add(driver->cdevs[index], dev, count);
3142 kobject_put(&driver->cdevs[index]->kobj);
3147 * tty_register_device - register a tty device
3148 * @driver: the tty driver that describes the tty device
3149 * @index: the index in the tty driver for this tty device
3150 * @device: a struct device that is associated with this tty device.
3151 * This field is optional, if there is no known struct device
3152 * for this tty device it can be set to NULL safely.
3154 * Returns a pointer to the struct device for this tty device
3155 * (or ERR_PTR(-EFOO) on error).
3157 * This call is required to be made to register an individual tty device
3158 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3159 * that bit is not set, this function should not be called by a tty
3165 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3166 struct device *device)
3168 return tty_register_device_attr(driver, index, device, NULL, NULL);
3170 EXPORT_SYMBOL(tty_register_device);
3172 static void tty_device_create_release(struct device *dev)
3174 dev_dbg(dev, "releasing...\n");
3179 * tty_register_device_attr - register a tty device
3180 * @driver: the tty driver that describes the tty device
3181 * @index: the index in the tty driver for this tty device
3182 * @device: a struct device that is associated with this tty device.
3183 * This field is optional, if there is no known struct device
3184 * for this tty device it can be set to NULL safely.
3185 * @drvdata: Driver data to be set to device.
3186 * @attr_grp: Attribute group to be set on device.
3188 * Returns a pointer to the struct device for this tty device
3189 * (or ERR_PTR(-EFOO) on error).
3191 * This call is required to be made to register an individual tty device
3192 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3193 * that bit is not set, this function should not be called by a tty
3198 struct device *tty_register_device_attr(struct tty_driver *driver,
3199 unsigned index, struct device *device,
3201 const struct attribute_group **attr_grp)
3204 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3205 struct ktermios *tp;
3209 if (index >= driver->num) {
3210 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3211 driver->name, index);
3212 return ERR_PTR(-EINVAL);
3215 if (driver->type == TTY_DRIVER_TYPE_PTY)
3216 pty_line_name(driver, index, name);
3218 tty_line_name(driver, index, name);
3220 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3222 return ERR_PTR(-ENOMEM);
3225 dev->class = tty_class;
3226 dev->parent = device;
3227 dev->release = tty_device_create_release;
3228 dev_set_name(dev, "%s", name);
3229 dev->groups = attr_grp;
3230 dev_set_drvdata(dev, drvdata);
3232 dev_set_uevent_suppress(dev, 1);
3234 retval = device_register(dev);
3238 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3240 * Free any saved termios data so that the termios state is
3241 * reset when reusing a minor number.
3243 tp = driver->termios[index];
3245 driver->termios[index] = NULL;
3249 retval = tty_cdev_add(driver, devt, index, 1);
3254 dev_set_uevent_suppress(dev, 0);
3255 kobject_uevent(&dev->kobj, KOBJ_ADD);
3264 return ERR_PTR(retval);
3266 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3269 * tty_unregister_device - unregister a tty device
3270 * @driver: the tty driver that describes the tty device
3271 * @index: the index in the tty driver for this tty device
3273 * If a tty device is registered with a call to tty_register_device() then
3274 * this function must be called when the tty device is gone.
3279 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3281 device_destroy(tty_class,
3282 MKDEV(driver->major, driver->minor_start) + index);
3283 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3284 cdev_del(driver->cdevs[index]);
3285 driver->cdevs[index] = NULL;
3288 EXPORT_SYMBOL(tty_unregister_device);
3291 * __tty_alloc_driver -- allocate tty driver
3292 * @lines: count of lines this driver can handle at most
3293 * @owner: module which is responsible for this driver
3294 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3296 * This should not be called directly, some of the provided macros should be
3297 * used instead. Use IS_ERR and friends on @retval.
3299 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3300 unsigned long flags)
3302 struct tty_driver *driver;
3303 unsigned int cdevs = 1;
3306 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3307 return ERR_PTR(-EINVAL);
3309 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3311 return ERR_PTR(-ENOMEM);
3313 kref_init(&driver->kref);
3314 driver->magic = TTY_DRIVER_MAGIC;
3315 driver->num = lines;
3316 driver->owner = owner;
3317 driver->flags = flags;
3319 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3320 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3322 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3324 if (!driver->ttys || !driver->termios) {
3330 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3331 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3333 if (!driver->ports) {
3340 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3341 if (!driver->cdevs) {
3348 kfree(driver->ports);
3349 kfree(driver->ttys);
3350 kfree(driver->termios);
3351 kfree(driver->cdevs);
3353 return ERR_PTR(err);
3355 EXPORT_SYMBOL(__tty_alloc_driver);
3357 static void destruct_tty_driver(struct kref *kref)
3359 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3361 struct ktermios *tp;
3363 if (driver->flags & TTY_DRIVER_INSTALLED) {
3364 for (i = 0; i < driver->num; i++) {
3365 tp = driver->termios[i];
3367 driver->termios[i] = NULL;
3370 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3371 tty_unregister_device(driver, i);
3373 proc_tty_unregister_driver(driver);
3374 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3375 cdev_del(driver->cdevs[0]);
3377 kfree(driver->cdevs);
3378 kfree(driver->ports);
3379 kfree(driver->termios);
3380 kfree(driver->ttys);
3384 void tty_driver_kref_put(struct tty_driver *driver)
3386 kref_put(&driver->kref, destruct_tty_driver);
3388 EXPORT_SYMBOL(tty_driver_kref_put);
3390 void tty_set_operations(struct tty_driver *driver,
3391 const struct tty_operations *op)
3395 EXPORT_SYMBOL(tty_set_operations);
3397 void put_tty_driver(struct tty_driver *d)
3399 tty_driver_kref_put(d);
3401 EXPORT_SYMBOL(put_tty_driver);
3404 * Called by a tty driver to register itself.
3406 int tty_register_driver(struct tty_driver *driver)
3413 if (!driver->major) {
3414 error = alloc_chrdev_region(&dev, driver->minor_start,
3415 driver->num, driver->name);
3417 driver->major = MAJOR(dev);
3418 driver->minor_start = MINOR(dev);
3421 dev = MKDEV(driver->major, driver->minor_start);
3422 error = register_chrdev_region(dev, driver->num, driver->name);
3427 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3428 error = tty_cdev_add(driver, dev, 0, driver->num);
3430 goto err_unreg_char;
3433 mutex_lock(&tty_mutex);
3434 list_add(&driver->tty_drivers, &tty_drivers);
3435 mutex_unlock(&tty_mutex);
3437 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3438 for (i = 0; i < driver->num; i++) {
3439 d = tty_register_device(driver, i, NULL);
3442 goto err_unreg_devs;
3446 proc_tty_register_driver(driver);
3447 driver->flags |= TTY_DRIVER_INSTALLED;
3451 for (i--; i >= 0; i--)
3452 tty_unregister_device(driver, i);
3454 mutex_lock(&tty_mutex);
3455 list_del(&driver->tty_drivers);
3456 mutex_unlock(&tty_mutex);
3459 unregister_chrdev_region(dev, driver->num);
3463 EXPORT_SYMBOL(tty_register_driver);
3466 * Called by a tty driver to unregister itself.
3468 int tty_unregister_driver(struct tty_driver *driver)
3472 if (driver->refcount)
3475 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3477 mutex_lock(&tty_mutex);
3478 list_del(&driver->tty_drivers);
3479 mutex_unlock(&tty_mutex);
3483 EXPORT_SYMBOL(tty_unregister_driver);
3485 dev_t tty_devnum(struct tty_struct *tty)
3487 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3489 EXPORT_SYMBOL(tty_devnum);
3491 void tty_default_fops(struct file_operations *fops)
3496 static char *tty_devnode(struct device *dev, umode_t *mode)
3500 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3501 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3506 static int __init tty_class_init(void)
3508 tty_class = class_create(THIS_MODULE, "tty");
3509 if (IS_ERR(tty_class))
3510 return PTR_ERR(tty_class);
3511 tty_class->devnode = tty_devnode;
3515 postcore_initcall(tty_class_init);
3517 /* 3/2004 jmc: why do these devices exist? */
3518 static struct cdev tty_cdev, console_cdev;
3520 static ssize_t show_cons_active(struct device *dev,
3521 struct device_attribute *attr, char *buf)
3523 struct console *cs[16];
3529 for_each_console(c) {
3534 if ((c->flags & CON_ENABLED) == 0)
3537 if (i >= ARRAY_SIZE(cs))
3541 int index = cs[i]->index;
3542 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3544 /* don't resolve tty0 as some programs depend on it */
3545 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3546 count += tty_line_name(drv, index, buf + count);
3548 count += sprintf(buf + count, "%s%d",
3549 cs[i]->name, cs[i]->index);
3551 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3557 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3559 static struct attribute *cons_dev_attrs[] = {
3560 &dev_attr_active.attr,
3564 ATTRIBUTE_GROUPS(cons_dev);
3566 static struct device *consdev;
3568 void console_sysfs_notify(void)
3571 sysfs_notify(&consdev->kobj, NULL, "active");
3575 * Ok, now we can initialize the rest of the tty devices and can count
3576 * on memory allocations, interrupts etc..
3578 int __init tty_init(void)
3581 cdev_init(&tty_cdev, &tty_fops);
3582 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3583 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3584 panic("Couldn't register /dev/tty driver\n");
3585 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3587 cdev_init(&console_cdev, &console_fops);
3588 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3589 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3590 panic("Couldn't register /dev/console driver\n");
3591 consdev = device_create_with_groups(tty_class, NULL,
3592 MKDEV(TTYAUX_MAJOR, 1), NULL,
3593 cons_dev_groups, "console");
3594 if (IS_ERR(consdev))
3598 vty_init(&console_fops);