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zircon-guest / third_party / linux / 56536cb602eaf2f2f59c72d8f31de8112ce315ff / . / drivers / tty / tty_io.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
* or rs-channels. It also implements echoing, cooked mode etc.
*
* Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
*
* Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
* tty_struct and tty_queue structures. Previously there was an array
* of 256 tty_struct's which was statically allocated, and the
* tty_queue structures were allocated at boot time. Both are now
* dynamically allocated only when the tty is open.
*
* Also restructured routines so that there is more of a separation
* between the high-level tty routines (tty_io.c and tty_ioctl.c) and
* the low-level tty routines (serial.c, pty.c, console.c). This
* makes for cleaner and more compact code. -TYT, 9/17/92
*
* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
* which can be dynamically activated and de-activated by the line
* discipline handling modules (like SLIP).
*
* NOTE: pay no attention to the line discipline code (yet); its
* interface is still subject to change in this version...
* -- TYT, 1/31/92
*
* Added functionality to the OPOST tty handling. No delays, but all
* other bits should be there.
* -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
*
* Rewrote canonical mode and added more termios flags.
* -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
*
* Reorganized FASYNC support so mouse code can share it.
* -- ctm@ardi.com, 9Sep95
*
* New TIOCLINUX variants added.
* -- mj@k332.feld.cvut.cz, 19-Nov-95
*
* Restrict vt switching via ioctl()
* -- grif@cs.ucr.edu, 5-Dec-95
*
* Move console and virtual terminal code to more appropriate files,
* implement CONFIG_VT and generalize console device interface.
* -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
*
* Rewrote tty_init_dev and tty_release_dev to eliminate races.
* -- Bill Hawes <whawes@star.net>, June 97
*
* Added devfs support.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
*
* Reduced memory usage for older ARM systems
* -- Russell King <rmk@arm.linux.org.uk>
*
* Move do_SAK() into process context. Less stack use in devfs functions.
* alloc_tty_struct() always uses kmalloc()
* -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
*/
#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/devpts_fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/console.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/kd.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/seq_file.h>
#include <linux/serial.h>
#include <linux/ratelimit.h>
#include <linux/uaccess.h>
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/kmod.h>
#include <linux/nsproxy.h>
#undef TTY_DEBUG_HANGUP
#ifdef TTY_DEBUG_HANGUP
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
#else
# define tty_debug_hangup(tty, f, args...) do { } while (0)
#endif
#define TTY_PARANOIA_CHECK 1
#define CHECK_TTY_COUNT 1
struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
.c_iflag = ICRNL | IXON,
.c_oflag = OPOST | ONLCR,
.c_cflag = B38400 | CS8 | CREAD | HUPCL,
.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
ECHOCTL | ECHOKE | IEXTEN,
.c_cc = INIT_C_CC,
.c_ispeed = 38400,
.c_ospeed = 38400,
/* .c_line = N_TTY, */
};
EXPORT_SYMBOL(tty_std_termios);
/* This list gets poked at by procfs and various bits of boot up code. This
could do with some rationalisation such as pulling the tty proc function
into this file */
LIST_HEAD(tty_drivers); /* linked list of tty drivers */
/* Mutex to protect creating and releasing a tty */
DEFINE_MUTEX(tty_mutex);
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
ssize_t redirected_tty_write(struct file *, const char __user *,
size_t, loff_t *);
static __poll_t tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
#else
#define tty_compat_ioctl NULL
#endif
static int __tty_fasync(int fd, struct file *filp, int on);
static int tty_fasync(int fd, struct file *filp, int on);
static void release_tty(struct tty_struct *tty, int idx);
/**
* free_tty_struct - free a disused tty
* @tty: tty struct to free
*
* Free the write buffers, tty queue and tty memory itself.
*
* Locking: none. Must be called after tty is definitely unused
*/
static void free_tty_struct(struct tty_struct *tty)
{
tty_ldisc_deinit(tty);
put_device(tty->dev);
kfree(tty->write_buf);
tty->magic = 0xDEADDEAD;
kfree(tty);
}
static inline struct tty_struct *file_tty(struct file *file)
{
return ((struct tty_file_private *)file->private_data)->tty;
}
int tty_alloc_file(struct file *file)
{
struct tty_file_private *priv;
priv = kmalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
file->private_data = priv;
return 0;
}
/* Associate a new file with the tty structure */
void tty_add_file(struct tty_struct *tty, struct file *file)
{
struct tty_file_private *priv = file->private_data;
priv->tty = tty;
priv->file = file;
spin_lock(&tty->files_lock);
list_add(&priv->list, &tty->tty_files);
spin_unlock(&tty->files_lock);
}
/**
* tty_free_file - free file->private_data
*
* This shall be used only for fail path handling when tty_add_file was not
* called yet.
*/
void tty_free_file(struct file *file)
{
struct tty_file_private *priv = file->private_data;
file->private_data = NULL;
kfree(priv);
}
/* Delete file from its tty */
static void tty_del_file(struct file *file)
{
struct tty_file_private *priv = file->private_data;
struct tty_struct *tty = priv->tty;
spin_lock(&tty->files_lock);
list_del(&priv->list);
spin_unlock(&tty->files_lock);
tty_free_file(file);
}
/**
* tty_name - return tty naming
* @tty: tty structure
*
* Convert a tty structure into a name. The name reflects the kernel
* naming policy and if udev is in use may not reflect user space
*
* Locking: none
*/
const char *tty_name(const struct tty_struct *tty)
{
if (!tty) /* Hmm. NULL pointer. That's fun. */
return "NULL tty";
return tty->name;
}
EXPORT_SYMBOL(tty_name);
const char *tty_driver_name(const struct tty_struct *tty)
{
if (!tty || !tty->driver)
return "";
return tty->driver->name;
}
static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
if (!tty) {
pr_warn("(%d:%d): %s: NULL tty\n",
imajor(inode), iminor(inode), routine);
return 1;
}
if (tty->magic != TTY_MAGIC) {
pr_warn("(%d:%d): %s: bad magic number\n",
imajor(inode), iminor(inode), routine);
return 1;
}
#endif
return 0;
}
/* Caller must hold tty_lock */
static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
struct list_head *p;
int count = 0, kopen_count = 0;
spin_lock(&tty->files_lock);
list_for_each(p, &tty->tty_files) {
count++;
}
spin_unlock(&tty->files_lock);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count)
count++;
if (tty_port_kopened(tty->port))
kopen_count++;
if (tty->count != (count + kopen_count)) {
tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
routine, tty->count, count, kopen_count);
return (count + kopen_count);
}
#endif
return 0;
}
/**
* get_tty_driver - find device of a tty
* @dev_t: device identifier
* @index: returns the index of the tty
*
* This routine returns a tty driver structure, given a device number
* and also passes back the index number.
*
* Locking: caller must hold tty_mutex
*/
static struct tty_driver *get_tty_driver(dev_t device, int *index)
{
struct tty_driver *p;
list_for_each_entry(p, &tty_drivers, tty_drivers) {
dev_t base = MKDEV(p->major, p->minor_start);
if (device < base || device >= base + p->num)
continue;
*index = device - base;
return tty_driver_kref_get(p);
}
return NULL;
}
/**
* tty_dev_name_to_number - return dev_t for device name
* @name: user space name of device under /dev
* @number: pointer to dev_t that this function will populate
*
* This function converts device names like ttyS0 or ttyUSB1 into dev_t
* like (4, 64) or (188, 1). If no corresponding driver is registered then
* the function returns -ENODEV.
*
* Locking: this acquires tty_mutex to protect the tty_drivers list from
* being modified while we are traversing it, and makes sure to
* release it before exiting.
*/
int tty_dev_name_to_number(const char *name, dev_t *number)
{
struct tty_driver *p;
int ret;
int index, prefix_length = 0;
const char *str;
for (str = name; *str && !isdigit(*str); str++)
;
if (!*str)
return -EINVAL;
ret = kstrtoint(str, 10, &index);
if (ret)
return ret;
prefix_length = str - name;
mutex_lock(&tty_mutex);
list_for_each_entry(p, &tty_drivers, tty_drivers)
if (prefix_length == strlen(p->name) && strncmp(name,
p->name, prefix_length) == 0) {
if (index < p->num) {
*number = MKDEV(p->major, p->minor_start + index);
goto out;
}
}
/* if here then driver wasn't found */
ret = -ENODEV;
out:
mutex_unlock(&tty_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
#ifdef CONFIG_CONSOLE_POLL
/**
* tty_find_polling_driver - find device of a polled tty
* @name: name string to match
* @line: pointer to resulting tty line nr
*
* This routine returns a tty driver structure, given a name
* and the condition that the tty driver is capable of polled
* operation.
*/
struct tty_driver *tty_find_polling_driver(char *name, int *line)
{
struct tty_driver *p, *res = NULL;
int tty_line = 0;
int len;
char *str, *stp;
for (str = name; *str; str++)
if ((*str >= '0' && *str <= '9') || *str == ',')
break;
if (!*str)
return NULL;
len = str - name;
tty_line = simple_strtoul(str, &str, 10);
mutex_lock(&tty_mutex);
/* Search through the tty devices to look for a match */
list_for_each_entry(p, &tty_drivers, tty_drivers) {
if (!len || strncmp(name, p->name, len) != 0)
continue;
stp = str;
if (*stp == ',')
stp++;
if (*stp == '\0')
stp = NULL;
if (tty_line >= 0 && tty_line < p->num && p->ops &&
p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
res = tty_driver_kref_get(p);
*line = tty_line;
break;
}
}
mutex_unlock(&tty_mutex);
return res;
}
EXPORT_SYMBOL_GPL(tty_find_polling_driver);
#endif
static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return -EIO;
}
/* No kernel lock held - none needed ;) */
static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
{
return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
}
static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
static long hung_up_tty_compat_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
static int hung_up_tty_fasync(int fd, struct file *file, int on)
{
return -ENOTTY;
}
static void tty_show_fdinfo(struct seq_file *m, struct file *file)
{
struct tty_struct *tty = file_tty(file);
if (tty && tty->ops && tty->ops->show_fdinfo)
tty->ops->show_fdinfo(tty, m);
}
static const struct file_operations tty_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
.show_fdinfo = tty_show_fdinfo,
};
static const struct file_operations console_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = redirected_tty_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
};
static const struct file_operations hung_up_tty_fops = {
.llseek = no_llseek,
.read = hung_up_tty_read,
.write = hung_up_tty_write,
.poll = hung_up_tty_poll,
.unlocked_ioctl = hung_up_tty_ioctl,
.compat_ioctl = hung_up_tty_compat_ioctl,
.release = tty_release,
.fasync = hung_up_tty_fasync,
};
static DEFINE_SPINLOCK(redirect_lock);
static struct file *redirect;
extern void tty_sysctl_init(void);
/**
* tty_wakeup - request more data
* @tty: terminal
*
* Internal and external helper for wakeups of tty. This function
* informs the line discipline if present that the driver is ready
* to receive more output data.
*/
void tty_wakeup(struct tty_struct *tty)
{
struct tty_ldisc *ld;
if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
ld = tty_ldisc_ref(tty);
if (ld) {
if (ld->ops->write_wakeup)
ld->ops->write_wakeup(tty);
tty_ldisc_deref(ld);
}
}
wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
}
EXPORT_SYMBOL_GPL(tty_wakeup);
/**
* __tty_hangup - actual handler for hangup events
* @work: tty device
*
* This can be called by a "kworker" kernel thread. That is process
* synchronous but doesn't hold any locks, so we need to make sure we
* have the appropriate locks for what we're doing.
*
* The hangup event clears any pending redirections onto the hung up
* device. It ensures future writes will error and it does the needed
* line discipline hangup and signal delivery. The tty object itself
* remains intact.
*
* Locking:
* BTM
* redirect lock for undoing redirection
* file list lock for manipulating list of ttys
* tty_ldiscs_lock from called functions
* termios_rwsem resetting termios data
* tasklist_lock to walk task list for hangup event
* ->siglock to protect ->signal/->sighand
*/
static void __tty_hangup(struct tty_struct *tty, int exit_session)
{
struct file *cons_filp = NULL;
struct file *filp, *f = NULL;
struct tty_file_private *priv;
int closecount = 0, n;
int refs;
if (!tty)
return;
spin_lock(&redirect_lock);
if (redirect && file_tty(redirect) == tty) {
f = redirect;
redirect = NULL;
}
spin_unlock(&redirect_lock);
tty_lock(tty);
if (test_bit(TTY_HUPPED, &tty->flags)) {
tty_unlock(tty);
return;
}
/*
* Some console devices aren't actually hung up for technical and
* historical reasons, which can lead to indefinite interruptible
* sleep in n_tty_read(). The following explicitly tells
* n_tty_read() to abort readers.
*/
set_bit(TTY_HUPPING, &tty->flags);
/* inuse_filps is protected by the single tty lock,
this really needs to change if we want to flush the
workqueue with the lock held */
check_tty_count(tty, "tty_hangup");
spin_lock(&tty->files_lock);
/* This breaks for file handles being sent over AF_UNIX sockets ? */
list_for_each_entry(priv, &tty->tty_files, list) {
filp = priv->file;
if (filp->f_op->write == redirected_tty_write)
cons_filp = filp;
if (filp->f_op->write != tty_write)
continue;
closecount++;
__tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops;
}
spin_unlock(&tty->files_lock);
refs = tty_signal_session_leader(tty, exit_session);
/* Account for the p->signal references we killed */
while (refs--)
tty_kref_put(tty);
tty_ldisc_hangup(tty, cons_filp != NULL);
spin_lock_irq(&tty->ctrl_lock);
clear_bit(TTY_THROTTLED, &tty->flags);
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
put_pid(tty->session);
put_pid(tty->pgrp);
tty->session = NULL;
tty->pgrp = NULL;
tty->ctrl_status = 0;
spin_unlock_irq(&tty->ctrl_lock);
/*
* If one of the devices matches a console pointer, we
* cannot just call hangup() because that will cause
* tty->count and state->count to go out of sync.
* So we just call close() the right number of times.
*/
if (cons_filp) {
if (tty->ops->close)
for (n = 0; n < closecount; n++)
tty->ops->close(tty, cons_filp);
} else if (tty->ops->hangup)
tty->ops->hangup(tty);
/*
* We don't want to have driver/ldisc interactions beyond the ones
* we did here. The driver layer expects no calls after ->hangup()
* from the ldisc side, which is now guaranteed.
*/
set_bit(TTY_HUPPED, &tty->flags);
clear_bit(TTY_HUPPING, &tty->flags);
tty_unlock(tty);
if (f)
fput(f);
}
static void do_tty_hangup(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, hangup_work);
__tty_hangup(tty, 0);
}
/**
* tty_hangup - trigger a hangup event
* @tty: tty to hangup
*
* A carrier loss (virtual or otherwise) has occurred on this like
* schedule a hangup sequence to run after this event.
*/
void tty_hangup(struct tty_struct *tty)
{
tty_debug_hangup(tty, "hangup\n");
schedule_work(&tty->hangup_work);
}
EXPORT_SYMBOL(tty_hangup);
/**
* tty_vhangup - process vhangup
* @tty: tty to hangup
*
* The user has asked via system call for the terminal to be hung up.
* We do this synchronously so that when the syscall returns the process
* is complete. That guarantee is necessary for security reasons.
*/
void tty_vhangup(struct tty_struct *tty)
{
tty_debug_hangup(tty, "vhangup\n");
__tty_hangup(tty, 0);
}
EXPORT_SYMBOL(tty_vhangup);
/**
* tty_vhangup_self - process vhangup for own ctty
*
* Perform a vhangup on the current controlling tty
*/
void tty_vhangup_self(void)
{
struct tty_struct *tty;
tty = get_current_tty();
if (tty) {
tty_vhangup(tty);
tty_kref_put(tty);
}
}
/**
* tty_vhangup_session - hangup session leader exit
* @tty: tty to hangup
*
* The session leader is exiting and hanging up its controlling terminal.
* Every process in the foreground process group is signalled SIGHUP.
*
* We do this synchronously so that when the syscall returns the process
* is complete. That guarantee is necessary for security reasons.
*/
void tty_vhangup_session(struct tty_struct *tty)
{
tty_debug_hangup(tty, "session hangup\n");
__tty_hangup(tty, 1);
}
/**
* tty_hung_up_p - was tty hung up
* @filp: file pointer of tty
*
* Return true if the tty has been subject to a vhangup or a carrier
* loss
*/
int tty_hung_up_p(struct file *filp)
{
return (filp && filp->f_op == &hung_up_tty_fops);
}
EXPORT_SYMBOL(tty_hung_up_p);
/**
* stop_tty - propagate flow control
* @tty: tty to stop
*
* Perform flow control to the driver. May be called
* on an already stopped device and will not re-call the driver
* method.
*
* This functionality is used by both the line disciplines for
* halting incoming flow and by the driver. It may therefore be
* called from any context, may be under the tty atomic_write_lock
* but not always.
*
* Locking:
* flow_lock
*/
void __stop_tty(struct tty_struct *tty)
{
if (tty->stopped)
return;
tty->stopped = 1;
if (tty->ops->stop)
tty->ops->stop(tty);
}
void stop_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__stop_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(stop_tty);
/**
* start_tty - propagate flow control
* @tty: tty to start
*
* Start a tty that has been stopped if at all possible. If this
* tty was previous stopped and is now being started, the driver
* start method is invoked and the line discipline woken.
*
* Locking:
* flow_lock
*/
void __start_tty(struct tty_struct *tty)
{
if (!tty->stopped || tty->flow_stopped)
return;
tty->stopped = 0;
if (tty->ops->start)
tty->ops->start(tty);
tty_wakeup(tty);
}
void start_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__start_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(start_tty);
static void tty_update_time(struct timespec64 *time)
{
time64_t sec = ktime_get_real_seconds();
/*
* We only care if the two values differ in anything other than the
* lower three bits (i.e every 8 seconds). If so, then we can update
* the time of the tty device, otherwise it could be construded as a
* security leak to let userspace know the exact timing of the tty.
*/
if ((sec ^ time->tv_sec) & ~7)
time->tv_sec = sec;
}
/**
* tty_read - read method for tty device files
* @file: pointer to tty file
* @buf: user buffer
* @count: size of user buffer
* @ppos: unused
*
* Perform the read system call function on this terminal device. Checks
* for hung up devices before calling the line discipline method.
*
* Locking:
* Locks the line discipline internally while needed. Multiple
* read calls may be outstanding in parallel.
*/
static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
int i;
struct inode *inode = file_inode(file);
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
if (tty_paranoia_check(tty, inode, "tty_read"))
return -EIO;
if (!tty || tty_io_error(tty))
return -EIO;
/* We want to wait for the line discipline to sort out in this
situation */
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_read(file, buf, count, ppos);
if (ld->ops->read)
i = ld->ops->read(tty, file, buf, count);
else
i = -EIO;
tty_ldisc_deref(ld);
if (i > 0)
tty_update_time(&inode->i_atime);
return i;
}
static void tty_write_unlock(struct tty_struct *tty)
{
mutex_unlock(&tty->atomic_write_lock);
wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
}
static int tty_write_lock(struct tty_struct *tty, int ndelay)
{
if (!mutex_trylock(&tty->atomic_write_lock)) {
if (ndelay)
return -EAGAIN;
if (mutex_lock_interruptible(&tty->atomic_write_lock))
return -ERESTARTSYS;
}
return 0;
}
/*
* Split writes up in sane blocksizes to avoid
* denial-of-service type attacks
*/
static inline ssize_t do_tty_write(
ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
struct tty_struct *tty,
struct file *file,
const char __user *buf,
size_t count)
{
ssize_t ret, written = 0;
unsigned int chunk;
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
/*
* We chunk up writes into a temporary buffer. This
* simplifies low-level drivers immensely, since they
* don't have locking issues and user mode accesses.
*
* But if TTY_NO_WRITE_SPLIT is set, we should use a
* big chunk-size..
*
* The default chunk-size is 2kB, because the NTTY
* layer has problems with bigger chunks. It will
* claim to be able to handle more characters than
* it actually does.
*
* FIXME: This can probably go away now except that 64K chunks
* are too likely to fail unless switched to vmalloc...
*/
chunk = 2048;
if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
chunk = 65536;
if (count < chunk)
chunk = count;
/* write_buf/write_cnt is protected by the atomic_write_lock mutex */
if (tty->write_cnt < chunk) {
unsigned char *buf_chunk;
if (chunk < 1024)
chunk = 1024;
buf_chunk = kmalloc(chunk, GFP_KERNEL);
if (!buf_chunk) {
ret = -ENOMEM;
goto out;
}
kfree(tty->write_buf);
tty->write_cnt = chunk;
tty->write_buf = buf_chunk;
}
/* Do the write .. */
for (;;) {
size_t size = count;
if (size > chunk)
size = chunk;
ret = -EFAULT;
if (copy_from_user(tty->write_buf, buf, size))
break;
ret = write(tty, file, tty->write_buf, size);
if (ret <= 0)
break;
written += ret;
buf += ret;
count -= ret;
if (!count)
break;
ret = -ERESTARTSYS;
if (signal_pending(current))
break;
cond_resched();
}
if (written) {
tty_update_time(&file_inode(file)->i_mtime);
ret = written;
}
out:
tty_write_unlock(tty);
return ret;
}
/**
* tty_write_message - write a message to a certain tty, not just the console.
* @tty: the destination tty_struct
* @msg: the message to write
*
* This is used for messages that need to be redirected to a specific tty.
* We don't put it into the syslog queue right now maybe in the future if
* really needed.
*
* We must still hold the BTM and test the CLOSING flag for the moment.
*/
void tty_write_message(struct tty_struct *tty, char *msg)
{
if (tty) {
mutex_lock(&tty->atomic_write_lock);
tty_lock(tty);
if (tty->ops->write && tty->count > 0)
tty->ops->write(tty, msg, strlen(msg));
tty_unlock(tty);
tty_write_unlock(tty);
}
return;
}
/**
* tty_write - write method for tty device file
* @file: tty file pointer
* @buf: user data to write
* @count: bytes to write
* @ppos: unused
*
* Write data to a tty device via the line discipline.
*
* Locking:
* Locks the line discipline as required
* Writes to the tty driver are serialized by the atomic_write_lock
* and are then processed in chunks to the device. The line discipline
* write method will not be invoked in parallel for each device.
*/
static ssize_t tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
ssize_t ret;
if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
return -EIO;
if (!tty || !tty->ops->write || tty_io_error(tty))
return -EIO;
/* Short term debug to catch buggy drivers */
if (tty->ops->write_room == NULL)
tty_err(tty, "missing write_room method\n");
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_write(file, buf, count, ppos);
if (!ld->ops->write)
ret = -EIO;
else
ret = do_tty_write(ld->ops->write, tty, file, buf, count);
tty_ldisc_deref(ld);
return ret;
}
ssize_t redirected_tty_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct file *p = NULL;
spin_lock(&redirect_lock);
if (redirect)
p = get_file(redirect);
spin_unlock(&redirect_lock);
if (p) {
ssize_t res;
res = vfs_write(p, buf, count, &p->f_pos);
fput(p);
return res;
}
return tty_write(file, buf, count, ppos);
}
/**
* tty_send_xchar - send priority character
*
* Send a high priority character to the tty even if stopped
*
* Locking: none for xchar method, write ordering for write method.
*/
int tty_send_xchar(struct tty_struct *tty, char ch)
{
int was_stopped = tty->stopped;
if (tty->ops->send_xchar) {
down_read(&tty->termios_rwsem);
tty->ops->send_xchar(tty, ch);
up_read(&tty->termios_rwsem);
return 0;
}
if (tty_write_lock(tty, 0) < 0)
return -ERESTARTSYS;
down_read(&tty->termios_rwsem);
if (was_stopped)
start_tty(tty);
tty->ops->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
up_read(&tty->termios_rwsem);
tty_write_unlock(tty);
return 0;
}
static char ptychar[] = "pqrstuvwxyzabcde";
/**
* pty_line_name - generate name for a pty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 6 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
static void pty_line_name(struct tty_driver *driver, int index, char *p)
{
int i = index + driver->name_base;
/* ->name is initialized to "ttyp", but "tty" is expected */
sprintf(p, "%s%c%x",
driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
ptychar[i >> 4 & 0xf], i & 0xf);
}
/**
* tty_line_name - generate name for a tty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 7 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
{
if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
return sprintf(p, "%s", driver->name);
else
return sprintf(p, "%s%d", driver->name,
index + driver->name_base);
}
/**
* tty_driver_lookup_tty() - find an existing tty, if any
* @driver: the driver for the tty
* @idx: the minor number
*
* Return the tty, if found. If not found, return NULL or ERR_PTR() if the
* driver lookup() method returns an error.
*
* Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
*/
static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
struct file *file, int idx)
{
struct tty_struct *tty;
if (driver->ops->lookup)
if (!file)
tty = ERR_PTR(-EIO);
else
tty = driver->ops->lookup(driver, file, idx);
else
tty = driver->ttys[idx];
if (!IS_ERR(tty))
tty_kref_get(tty);
return tty;
}
/**
* tty_init_termios - helper for termios setup
* @tty: the tty to set up
*
* Initialise the termios structures for this tty. Thus runs under
* the tty_mutex currently so we can be relaxed about ordering.
*/
void tty_init_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
tty->termios = tty->driver->init_termios;
else {
/* Check for lazy saved data */
tp = tty->driver->termios[idx];
if (tp != NULL) {
tty->termios = *tp;
tty->termios.c_line = tty->driver->init_termios.c_line;
} else
tty->termios = tty->driver->init_termios;
}
/* Compatibility until drivers always set this */
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
}
EXPORT_SYMBOL_GPL(tty_init_termios);
int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
{
tty_init_termios(tty);
tty_driver_kref_get(driver);
tty->count++;
driver->ttys[tty->index] = tty;
return 0;
}
EXPORT_SYMBOL_GPL(tty_standard_install);
/**
* tty_driver_install_tty() - install a tty entry in the driver
* @driver: the driver for the tty
* @tty: the tty
*
* Install a tty object into the driver tables. The tty->index field
* will be set by the time this is called. This method is responsible
* for ensuring any need additional structures are allocated and
* configured.
*
* Locking: tty_mutex for now
*/
static int tty_driver_install_tty(struct tty_driver *driver,
struct tty_struct *tty)
{
return driver->ops->install ? driver->ops->install(driver, tty) :
tty_standard_install(driver, tty);
}
/**
* tty_driver_remove_tty() - remove a tty from the driver tables
* @driver: the driver for the tty
* @idx: the minor number
*
* Remvoe a tty object from the driver tables. The tty->index field
* will be set by the time this is called.
*
* Locking: tty_mutex for now
*/
static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
{
if (driver->ops->remove)
driver->ops->remove(driver, tty);
else
driver->ttys[tty->index] = NULL;
}
/*
* tty_reopen() - fast re-open of an open tty
* @tty - the tty to open
*
* Return 0 on success, -errno on error.
* Re-opens on master ptys are not allowed and return -EIO.
*
* Locking: Caller must hold tty_lock
*/
static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;
struct tty_ldisc *ld;
int retval = 0;
if (driver->type == TTY_DRIVER_TYPE_PTY &&
driver->subtype == PTY_TYPE_MASTER)
return -EIO;
if (!tty->count)
return -EAGAIN;
if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
return -EBUSY;
ld = tty_ldisc_ref_wait(tty);
if (ld) {
tty_ldisc_deref(ld);
} else {
retval = tty_ldisc_lock(tty, 5 * HZ);
if (retval)
return retval;
if (!tty->ldisc)
retval = tty_ldisc_reinit(tty, tty->termios.c_line);
tty_ldisc_unlock(tty);
}
if (retval == 0)
tty->count++;
return retval;
}
/**
* tty_init_dev - initialise a tty device
* @driver: tty driver we are opening a device on
* @idx: device index
* @ret_tty: returned tty structure
*
* Prepare a tty device. This may not be a "new" clean device but
* could also be an active device. The pty drivers require special
* handling because of this.
*
* Locking:
* The function is called under the tty_mutex, which
* protects us from the tty struct or driver itself going away.
*
* On exit the tty device has the line discipline attached and
* a reference count of 1. If a pair was created for pty/tty use
* and the other was a pty master then it too has a reference count of 1.
*
* WSH 06/09/97: Rewritten to remove races and properly clean up after a
* failed open. The new code protects the open with a mutex, so it's
* really quite straightforward. The mutex locking can probably be
* relaxed for the (most common) case of reopening a tty.
*/
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
int retval;
/*
* First time open is complex, especially for PTY devices.
* This code guarantees that either everything succeeds and the
* TTY is ready for operation, or else the table slots are vacated
* and the allocated memory released. (Except that the termios
* may be retained.)
*/
if (!try_module_get(driver->owner))
return ERR_PTR(-ENODEV);
tty = alloc_tty_struct(driver, idx);
if (!tty) {
retval = -ENOMEM;
goto err_module_put;
}
tty_lock(tty);
retval = tty_driver_install_tty(driver, tty);
if (retval < 0)
goto err_free_tty;
if (!tty->port)
tty->port = driver->ports[idx];
WARN_RATELIMIT(!tty->port,
"%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
__func__, tty->driver->name);
retval = tty_ldisc_lock(tty, 5 * HZ);
if (retval)
goto err_release_lock;
tty->port->itty = tty;
/*
* Structures all installed ... call the ldisc open routines.
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/
retval = tty_ldisc_setup(tty, tty->link);
if (retval)
goto err_release_tty;
tty_ldisc_unlock(tty);
/* Return the tty locked so that it cannot vanish under the caller */
return tty;
err_free_tty:
tty_unlock(tty);
free_tty_struct(tty);
err_module_put:
module_put(driver->owner);
return ERR_PTR(retval);
/* call the tty release_tty routine to clean out this slot */
err_release_tty:
tty_ldisc_unlock(tty);
tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
retval, idx);
err_release_lock:
tty_unlock(tty);
release_tty(tty, idx);
return ERR_PTR(retval);
}
/**
* tty_save_termios() - save tty termios data in driver table
* @tty: tty whose termios data to save
*
* Locking: Caller guarantees serialisation with tty_init_termios().
*/
void tty_save_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
/* If the port is going to reset then it has no termios to save */
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
return;
/* Stash the termios data */
tp = tty->driver->termios[idx];
if (tp == NULL) {
tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (tp == NULL)
return;
tty->driver->termios[idx] = tp;
}
*tp = tty->termios;
}
EXPORT_SYMBOL_GPL(tty_save_termios);
/**
* tty_flush_works - flush all works of a tty/pty pair
* @tty: tty device to flush works for (or either end of a pty pair)
*
* Sync flush all works belonging to @tty (and the 'other' tty).
*/
static void tty_flush_works(struct tty_struct *tty)
{
flush_work(&tty->SAK_work);
flush_work(&tty->hangup_work);
if (tty->link) {
flush_work(&tty->link->SAK_work);
flush_work(&tty->link->hangup_work);
}
}
/**
* release_one_tty - release tty structure memory
* @kref: kref of tty we are obliterating
*
* Releases memory associated with a tty structure, and clears out the
* driver table slots. This function is called when a device is no longer
* in use. It also gets called when setup of a device fails.
*
* Locking:
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
* This method gets called from a work queue so that the driver private
* cleanup ops can sleep (needed for USB at least)
*/
static void release_one_tty(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, hangup_work);
struct tty_driver *driver = tty->driver;
struct module *owner = driver->owner;
if (tty->ops->cleanup)
tty->ops->cleanup(tty);
tty->magic = 0;
tty_driver_kref_put(driver);
module_put(owner);
spin_lock(&tty->files_lock);
list_del_init(&tty->tty_files);
spin_unlock(&tty->files_lock);
put_pid(tty->pgrp);
put_pid(tty->session);
free_tty_struct(tty);
}
static void queue_release_one_tty(struct kref *kref)
{
struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
/* The hangup queue is now free so we can reuse it rather than
waste a chunk of memory for each port */
INIT_WORK(&tty->hangup_work, release_one_tty);
schedule_work(&tty->hangup_work);
}
/**
* tty_kref_put - release a tty kref
* @tty: tty device
*
* Release a reference to a tty device and if need be let the kref
* layer destruct the object for us
*/
void tty_kref_put(struct tty_struct *tty)
{
if (tty)
kref_put(&tty->kref, queue_release_one_tty);
}
EXPORT_SYMBOL(tty_kref_put);
/**
* release_tty - release tty structure memory
*
* Release both @tty and a possible linked partner (think pty pair),
* and decrement the refcount of the backing module.
*
* Locking:
* tty_mutex
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
*/
static void release_tty(struct tty_struct *tty, int idx)
{
/* This should always be true but check for the moment */
WARN_ON(tty->index != idx);
WARN_ON(!mutex_is_locked(&tty_mutex));
if (tty->ops->shutdown)
tty->ops->shutdown(tty);
tty_save_termios(tty);
tty_driver_remove_tty(tty->driver, tty);
tty->port->itty = NULL;
if (tty->link)
tty->link->port->itty = NULL;
tty_buffer_cancel_work(tty->port);
if (tty->link)
tty_buffer_cancel_work(tty->link->port);
tty_kref_put(tty->link);
tty_kref_put(tty);
}
/**
* tty_release_checks - check a tty before real release
* @tty: tty to check
* @o_tty: link of @tty (if any)
* @idx: index of the tty
*
* Performs some paranoid checking before true release of the @tty.
* This is a no-op unless TTY_PARANOIA_CHECK is defined.
*/
static int tty_release_checks(struct tty_struct *tty, int idx)
{
#ifdef TTY_PARANOIA_CHECK
if (idx < 0 || idx >= tty->driver->num) {
tty_debug(tty, "bad idx %d\n", idx);
return -1;
}
/* not much to check for devpts */
if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
return 0;
if (tty != tty->driver->ttys[idx]) {
tty_debug(tty, "bad driver table[%d] = %p\n",
idx, tty->driver->ttys[idx]);
return -1;
}
if (tty->driver->other) {
struct tty_struct *o_tty = tty->link;
if (o_tty != tty->driver->other->ttys[idx]) {
tty_debug(tty, "bad other table[%d] = %p\n",
idx, tty->driver->other->ttys[idx]);
return -1;
}
if (o_tty->link != tty) {
tty_debug(tty, "bad link = %p\n", o_tty->link);
return -1;
}
}
#endif
return 0;
}
/**
* tty_kclose - closes tty opened by tty_kopen
* @tty: tty device
*
* Performs the final steps to release and free a tty device. It is the
* same as tty_release_struct except that it also resets TTY_PORT_KOPENED
* flag on tty->port.
*/
void tty_kclose(struct tty_struct *tty)
{
/*
* Ask the line discipline code to release its structures
*/
tty_ldisc_release(tty);
/* Wait for pending work before tty destruction commmences */
tty_flush_works(tty);
tty_debug_hangup(tty, "freeing structure\n");
/*
* The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure. The tty_unlock_pair
* should be safe as we keep a kref while the tty is locked (so the
* unlock never unlocks a freed tty).
*/
mutex_lock(&tty_mutex);
tty_port_set_kopened(tty->port, 0);
release_tty(tty, tty->index);
mutex_unlock(&tty_mutex);
}
EXPORT_SYMBOL_GPL(tty_kclose);
/**
* tty_release_struct - release a tty struct
* @tty: tty device
* @idx: index of the tty
*
* Performs the final steps to release and free a tty device. It is
* roughly the reverse of tty_init_dev.
*/
void tty_release_struct(struct tty_struct *tty, int idx)
{
/*
* Ask the line discipline code to release its structures
*/
tty_ldisc_release(tty);
/* Wait for pending work before tty destruction commmences */
tty_flush_works(tty);
tty_debug_hangup(tty, "freeing structure\n");
/*
* The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure. The tty_unlock_pair
* should be safe as we keep a kref while the tty is locked (so the
* unlock never unlocks a freed tty).
*/
mutex_lock(&tty_mutex);
release_tty(tty, idx);
mutex_unlock(&tty_mutex);
}
EXPORT_SYMBOL_GPL(tty_release_struct);
/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See tty_release_dev
*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
* same time, as interrupts might otherwise get the wrong pointers.
*
* WSH 09/09/97: rewritten to avoid some nasty race conditions that could
* lead to double frees or releasing memory still in use.
*/
int tty_release(struct inode *inode, struct file *filp)
{
struct tty_struct *tty = file_tty(filp);
struct tty_struct *o_tty = NULL;
int do_sleep, final;
int idx;
long timeout = 0;
int once = 1;
if (tty_paranoia_check(tty, inode, __func__))
return 0;
tty_lock(tty);
check_tty_count(tty, __func__);
__tty_fasync(-1, filp, 0);
idx = tty->index;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
o_tty = tty->link;
if (tty_release_checks(tty, idx)) {
tty_unlock(tty);
return 0;
}
tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
if (tty->ops->close)
tty->ops->close(tty, filp);
/* If tty is pty master, lock the slave pty (stable lock order) */
tty_lock_slave(o_tty);
/*
* Sanity check: if tty->count is going to zero, there shouldn't be
* any waiters on tty->read_wait or tty->write_wait. We test the
* wait queues and kick everyone out _before_ actually starting to
* close. This ensures that we won't block while releasing the tty
* structure.
*
* The test for the o_tty closing is necessary, since the master and
* slave sides may close in any order. If the slave side closes out
* first, its count will be one, since the master side holds an open.
* Thus this test wouldn't be triggered at the time the slave closed,
* so we do it now.
*/
while (1) {
do_sleep = 0;
if (tty->count <= 1) {
if (waitqueue_active(&tty->read_wait)) {
wake_up_poll(&tty->read_wait, EPOLLIN);
do_sleep++;
}
if (waitqueue_active(&tty->write_wait)) {
wake_up_poll(&tty->write_wait, EPOLLOUT);
do_sleep++;
}
}
if (o_tty && o_tty->count <= 1) {
if (waitqueue_active(&o_tty->read_wait)) {
wake_up_poll(&o_tty->read_wait, EPOLLIN);
do_sleep++;
}
if (waitqueue_active(&o_tty->write_wait)) {
wake_up_poll(&o_tty->write_wait, EPOLLOUT);
do_sleep++;
}
}
if (!do_sleep)
break;
if (once) {
once = 0;
tty_warn(tty, "read/write wait queue active!\n");
}
schedule_timeout_killable(timeout);
if (timeout < 120 * HZ)
timeout = 2 * timeout + 1;
else
timeout = MAX_SCHEDULE_TIMEOUT;
}
if (o_tty) {
if (--o_tty->count < 0) {
tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
o_tty->count = 0;
}
}
if (--tty->count < 0) {
tty_warn(tty, "bad tty->count (%d)\n", tty->count);
tty->count = 0;
}
/*
* We've decremented tty->count, so we need to remove this file
* descriptor off the tty->tty_files list; this serves two
* purposes:
* - check_tty_count sees the correct number of file descriptors
* associated with this tty.
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
tty_del_file(filp);
/*
* Perform some housekeeping before deciding whether to return.
*
* If _either_ side is closing, make sure there aren't any
* processes that still think tty or o_tty is their controlling
* tty.
*/
if (!tty->count) {
read_lock(&tasklist_lock);
session_clear_tty(tty->session);
if (o_tty)
session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
/* check whether both sides are closing ... */
final = !tty->count && !(o_tty && o_tty->count);
tty_unlock_slave(o_tty);
tty_unlock(tty);
/* At this point, the tty->count == 0 should ensure a dead tty
cannot be re-opened by a racing opener */
if (!final)
return 0;
tty_debug_hangup(tty, "final close\n");
tty_release_struct(tty, idx);
return 0;
}
/**
* tty_open_current_tty - get locked tty of current task
* @device: device number
* @filp: file pointer to tty
* @return: locked tty of the current task iff @device is /dev/tty
*
* Performs a re-open of the current task's controlling tty.
*
* We cannot return driver and index like for the other nodes because
* devpts will not work then. It expects inodes to be from devpts FS.
*/
static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
{
struct tty_struct *tty;
int retval;
if (device != MKDEV(TTYAUX_MAJOR, 0))
return NULL;
tty = get_current_tty();
if (!tty)
return ERR_PTR(-ENXIO);
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
tty_lock(tty);
tty_kref_put(tty); /* safe to drop the kref now */
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
return tty;
}
/**
* tty_lookup_driver - lookup a tty driver for a given device file
* @device: device number
* @filp: file pointer to tty
* @index: index for the device in the @return driver
* @return: driver for this inode (with increased refcount)
*
* If @return is not erroneous, the caller is responsible to decrement the
* refcount by tty_driver_kref_put.
*
* Locking: tty_mutex protects get_tty_driver
*/
static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
int *index)
{
struct tty_driver *driver;
switch (device) {
#ifdef CONFIG_VT
case MKDEV(TTY_MAJOR, 0): {
extern struct tty_driver *console_driver;
driver = tty_driver_kref_get(console_driver);
*index = fg_console;
break;
}
#endif
case MKDEV(TTYAUX_MAJOR, 1): {
struct tty_driver *console_driver = console_device(index);
if (console_driver) {
driver = tty_driver_kref_get(console_driver);
if (driver && filp) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
break;
}
}
return ERR_PTR(-ENODEV);
}
default:
driver = get_tty_driver(device, index);
if (!driver)
return ERR_PTR(-ENODEV);
break;
}
return driver;
}
/**
* tty_kopen - open a tty device for kernel
* @device: dev_t of device to open
*
* Opens tty exclusively for kernel. Performs the driver lookup,
* makes sure it's not already opened and performs the first-time
* tty initialization.
*
* Returns the locked initialized &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
struct tty_struct *tty_kopen(dev_t device)
{
struct tty_struct *tty;
struct tty_driver *driver = NULL;
int index = -1;
mutex_lock(&tty_mutex);
driver = tty_lookup_driver(device, NULL, &index);
if (IS_ERR(driver)) {
mutex_unlock(&tty_mutex);
return ERR_CAST(driver);
}
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, NULL, index);
if (IS_ERR(tty))
goto out;
if (tty) {
/* drop kref from tty_driver_lookup_tty() */
tty_kref_put(tty);
tty = ERR_PTR(-EBUSY);
} else { /* tty_init_dev returns tty with the tty_lock held */
tty = tty_init_dev(driver, index);
if (IS_ERR(tty))
goto out;
tty_port_set_kopened(tty->port, 1);
}
out:
mutex_unlock(&tty_mutex);
tty_driver_kref_put(driver);
return tty;
}
EXPORT_SYMBOL_GPL(tty_kopen);
/**
* tty_open_by_driver - open a tty device
* @device: dev_t of device to open
* @inode: inode of device file
* @filp: file pointer to tty
*
* Performs the driver lookup, checks for a reopen, or otherwise
* performs the first-time tty initialization.
*
* Returns the locked initialized or re-opened &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
struct file *filp)
{
struct tty_struct *tty;
struct tty_driver *driver = NULL;
int index = -1;
int retval;
mutex_lock(&tty_mutex);
driver = tty_lookup_driver(device, filp, &index);
if (IS_ERR(driver)) {
mutex_unlock(&tty_mutex);
return ERR_CAST(driver);
}
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, filp, index);
if (IS_ERR(tty)) {
mutex_unlock(&tty_mutex);
goto out;
}
if (tty) {
if (tty_port_kopened(tty->port)) {
tty_kref_put(tty);
mutex_unlock(&tty_mutex);
tty = ERR_PTR(-EBUSY);
goto out;
}
mutex_unlock(&tty_mutex);
retval = tty_lock_interruptible(tty);
tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
if (retval) {
if (retval == -EINTR)
retval = -ERESTARTSYS;
tty = ERR_PTR(retval);
goto out;
}
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
} else { /* Returns with the tty_lock held for now */
tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex);
}
out:
tty_driver_kref_put(driver);
return tty;
}
/**
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
* tty_open and tty_release keep up the tty count that contains the
* number of opens done on a tty. We cannot use the inode-count, as
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
*
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*
* Note: the tty_unlock/lock cases without a ref are only safe due to
* tty_mutex
*/
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
int noctty, retval;
dev_t device = inode->i_rdev;
unsigned saved_flags = filp->f_flags;
nonseekable_open(inode, filp);
retry_open:
retval = tty_alloc_file(filp);
if (retval)
return -ENOMEM;
tty = tty_open_current_tty(device, filp);
if (!tty)
tty = tty_open_by_driver(device, inode, filp);
if (IS_ERR(tty)) {
tty_free_file(filp);
retval = PTR_ERR(tty);
if (retval != -EAGAIN || signal_pending(current))
return retval;
schedule();
goto retry_open;
}
tty_add_file(tty, filp);
check_tty_count(tty, __func__);
tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
if (tty->ops->open)
retval = tty->ops->open(tty, filp);
else
retval = -ENODEV;
filp->f_flags = saved_flags;
if (retval) {
tty_debug_hangup(tty, "open error %d, releasing\n", retval);
tty_unlock(tty); /* need to call tty_release without BTM */
tty_release(inode, filp);
if (retval != -ERESTARTSYS)
return retval;
if (signal_pending(current))
return retval;
schedule();
/*
* Need to reset f_op in case a hangup happened.
*/
if (tty_hung_up_p(filp))
filp->f_op = &tty_fops;
goto retry_open;
}
clear_bit(TTY_HUPPED, &tty->flags);
noctty = (filp->f_flags & O_NOCTTY) ||
(IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
device == MKDEV(TTYAUX_MAJOR, 1) ||
(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
if (!noctty)
tty_open_proc_set_tty(filp, tty);
tty_unlock(tty);
return 0;
}
/**
* tty_poll - check tty status
* @filp: file being polled
* @wait: poll wait structures to update
*
* Call the line discipline polling method to obtain the poll
* status of the device.
*
* Locking: locks called line discipline but ldisc poll method
* may be re-entered freely by other callers.
*/
static __poll_t tty_poll(struct file *filp, poll_table *wait)
{
struct tty_struct *tty = file_tty(filp);
struct tty_ldisc *ld;
__poll_t ret = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
return 0;
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_poll(filp, wait);
if (ld->ops->poll)
ret = ld->ops->poll(tty, filp, wait);
tty_ldisc_deref(ld);
return ret;
}
static int __tty_fasync(int fd, struct file *filp, int on)
{
struct tty_struct *tty = file_tty(filp);
unsigned long flags;
int retval = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
goto out;
retval = fasync_helper(fd, filp, on, &tty->fasync);
if (retval <= 0)
goto out;
if (on) {
enum pid_type type;
struct pid *pid;
spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->pgrp) {
pid = tty->pgrp;
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_TGID;
}
get_pid(pid);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
__f_setown(filp, pid, type, 0);
put_pid(pid);
retval = 0;
}
out:
return retval;
}
static int tty_fasync(int fd, struct file *filp, int on)
{
struct tty_struct *tty = file_tty(filp);
int retval = -ENOTTY;
tty_lock(tty);
if (!tty_hung_up_p(filp))
retval = __tty_fasync(fd, filp, on);
tty_unlock(tty);
return retval;
}
/**
* tiocsti - fake input character
* @tty: tty to fake input into
* @p: pointer to character
*
* Fake input to a tty device. Does the necessary locking and
* input management.
*
* FIXME: does not honour flow control ??
*
* Locking:
* Called functions take tty_ldiscs_lock
* current->signal->tty check is safe without locks
*/
static int tiocsti(struct tty_struct *tty, char __user *p)
{
char ch, mbz = 0;
struct tty_ldisc *ld;
if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(ch, p))
return -EFAULT;
tty_audit_tiocsti(tty, ch);
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return -EIO;
tty_buffer_lock_exclusive(tty->port);
if (ld->ops->receive_buf)
ld->ops->receive_buf(tty, &ch, &mbz, 1);
tty_buffer_unlock_exclusive(tty->port);
tty_ldisc_deref(ld);
return 0;
}
/**
* tiocgwinsz - implement window query ioctl
* @tty; tty
* @arg: user buffer for result
*
* Copies the kernel idea of the window size into the user buffer.
*
* Locking: tty->winsize_mutex is taken to ensure the winsize data
* is consistent.
*/
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{
int err;
mutex_lock(&tty->winsize_mutex);
err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
mutex_unlock(&tty->winsize_mutex);
return err ? -EFAULT: 0;
}
/**
* tty_do_resize - resize event
* @tty: tty being resized
* @rows: rows (character)
* @cols: cols (character)
*
* Update the termios variables and send the necessary signals to
* peform a terminal resize correctly
*/
int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
{
struct pid *pgrp;
/* Lock the tty */
mutex_lock(&tty->winsize_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Signal the foreground process group */
pgrp = tty_get_pgrp(tty);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
put_pid(pgrp);
tty->winsize = *ws;
done:
mutex_unlock(&tty->winsize_mutex);
return 0;
}
EXPORT_SYMBOL(tty_do_resize);
/**
* tiocswinsz - implement window size set ioctl
* @tty; tty side of tty
* @arg: user buffer for result
*
* Copies the user idea of the window size to the kernel. Traditionally
* this is just advisory information but for the Linux console it
* actually has driver level meaning and triggers a VC resize.
*
* Locking:
* Driver dependent. The default do_resize method takes the
* tty termios mutex and ctrl_lock. The console takes its own lock
* then calls into the default method.
*/
static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
{
struct winsize tmp_ws;
if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
return -EFAULT;
if (tty->ops->resize)
return tty->ops->resize(tty, &tmp_ws);
else
return tty_do_resize(tty, &tmp_ws);
}
/**
* tioccons - allow admin to move logical console
* @file: the file to become console
*
* Allow the administrator to move the redirected console device
*
* Locking: uses redirect_lock to guard the redirect information
*/
static int tioccons(struct file *file)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (file->f_op->write == redirected_tty_write) {
struct file *f;
spin_lock(&redirect_lock);
f = redirect;
redirect = NULL;
spin_unlock(&redirect_lock);
if (f)
fput(f);
return 0;
}
spin_lock(&redirect_lock);
if (redirect) {
spin_unlock(&redirect_lock);
return -EBUSY;
}
redirect = get_file(file);
spin_unlock(&redirect_lock);
return 0;
}
/**
* fionbio - non blocking ioctl
* @file: file to set blocking value
* @p: user parameter
*
* Historical tty interfaces had a blocking control ioctl before
* the generic functionality existed. This piece of history is preserved
* in the expected tty API of posix OS's.
*
* Locking: none, the open file handle ensures it won't go away.
*/
static int fionbio(struct file *file, int __user *p)
{
int nonblock;
if (get_user(nonblock, p))
return -EFAULT;
spin_lock(&file->f_lock);
if (nonblock)
file->f_flags |= O_NONBLOCK;
else
file->f_flags &= ~O_NONBLOCK;
spin_unlock(&file->f_lock);
return 0;
}
/**
* tiocsetd - set line discipline
* @tty: tty device
* @p: pointer to user data
*
* Set the line discipline according to user request.
*
* Locking: see tty_set_ldisc, this function is just a helper
*/
static int tiocsetd(struct tty_struct *tty, int __user *p)
{
int disc;
int ret;
if (get_user(disc, p))
return -EFAULT;
ret = tty_set_ldisc(tty, disc);
return ret;
}
/**
* tiocgetd - get line discipline
* @tty: tty device
* @p: pointer to user data
*
* Retrieves the line discipline id directly from the ldisc.
*
* Locking: waits for ldisc reference (in case the line discipline
* is changing or the tty is being hungup)
*/
static int tiocgetd(struct tty_struct *tty, int __user *p)
{
struct tty_ldisc *ld;
int ret;
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return -EIO;
ret = put_user(ld->ops->num, p);
tty_ldisc_deref(ld);
return ret;
}
/**
* send_break - performed time break
* @tty: device to break on
* @duration: timeout in mS
*
* Perform a timed break on hardware that lacks its own driver level
* timed break functionality.
*
* Locking:
* atomic_write_lock serializes
*
*/
static int send_break(struct tty_struct *tty, unsigned int duration)
{
int retval;
if (tty->ops->break_ctl == NULL)
return 0;
if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
retval = tty->ops->break_ctl(tty, duration);
else {
/* Do the work ourselves */
if (tty_write_lock(tty, 0) < 0)
return -EINTR;
retval = tty->ops->break_ctl(tty, -1);
if (retval)
goto out;
if (!signal_pending(current))
msleep_interruptible(duration);
retval = tty->ops->break_ctl(tty, 0);
out:
tty_write_unlock(tty);
if (signal_pending(current))
retval = -EINTR;
}
return retval;
}
/**
* tty_tiocmget - get modem status
* @tty: tty device
* @file: user file pointer
* @p: pointer to result
*
* Obtain the modem status bits from the tty driver if the feature
* is supported. Return -ENOTTY if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmget(struct tty_struct *tty, int __user *p)
{
int retval = -ENOTTY;
if (tty->ops->tiocmget) {
retval = tty->ops->tiocmget(tty);
if (retval >= 0)
retval = put_user(retval, p);
}
return retval;
}
/**
* tty_tiocmset - set modem status
* @tty: tty device
* @cmd: command - clear bits, set bits or set all
* @p: pointer to desired bits
*
* Set the modem status bits from the tty driver if the feature
* is supported. Return -ENOTTY if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
unsigned __user *p)
{
int retval;
unsigned int set, clear, val;
if (tty->ops->tiocmset == NULL)
return -ENOTTY;
retval = get_user(val, p);
if (retval)
return retval;
set = clear = 0;
switch (cmd) {
case TIOCMBIS:
set = val;
break;
case TIOCMBIC:
clear = val;
break;
case TIOCMSET:
set = val;
clear = ~val;
break;
}
set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
return tty->ops->tiocmset(tty, set, clear);
}
static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
{
int retval = -EINVAL;
struct serial_icounter_struct icount;
memset(&icount, 0, sizeof(icount));
if (tty->ops->get_icount)
retval = tty->ops->get_icount(tty, &icount);
if (retval != 0)
return retval;
if (copy_to_user(arg, &icount, sizeof(icount)))
return -EFAULT;
return 0;
}
static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
{
static DEFINE_RATELIMIT_STATE(depr_flags,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
char comm[TASK_COMM_LEN];
int flags;
if (get_user(flags, &ss->flags))
return;
flags &= ASYNC_DEPRECATED;
if (flags && __ratelimit(&depr_flags))
pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
__func__, get_task_comm(comm, current), flags);
}
/*
* if pty, return the slave side (real_tty)
* otherwise, return self
*/
static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
tty = tty->link;
return tty;
}
/*
* Split this up, as gcc can choke on it otherwise..
*/
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct tty_struct *tty = file_tty(file);
struct tty_struct *real_tty;
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
real_tty = tty_pair_get_tty(tty);
/*
* Factor out some common prep work
*/
switch (cmd) {
case TIOCSETD:
case TIOCSBRK:
case TIOCCBRK:
case TCSBRK:
case TCSBRKP:
retval = tty_check_change(tty);
if (retval)
return retval;
if (cmd != TIOCCBRK) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
return -EINTR;
}
break;
}
/*
* Now do the stuff.
*/
switch (cmd) {
case TIOCSTI:
return tiocsti(tty, p);
case TIOCGWINSZ:
return tiocgwinsz(real_tty, p);
case TIOCSWINSZ:
return tiocswinsz(real_tty, p);
case TIOCCONS:
return real_tty != tty ? -EINVAL : tioccons(file);
case FIONBIO:
return fionbio(file, p);
case TIOCEXCL:
set_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCNXCL:
clear_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCGEXCL:
{
int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
return put_user(excl, (int __user *)p);
}
case TIOCGETD:
return tiocgetd(tty, p);
case TIOCSETD:
return tiocsetd(tty, p);
case TIOCVHANGUP:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
tty_vhangup(tty);
return 0;
case TIOCGDEV:
{
unsigned int ret = new_encode_dev(tty_devnum(real_tty));
return put_user(ret, (unsigned int __user *)p);
}
/*
* Break handling
*/
case TIOCSBRK: /* Turn break on, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, -1);
return 0;
case TIOCCBRK: /* Turn break off, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, 0);
return 0;
case TCSBRK: /* SVID version: non-zero arg --> no break */
/* non-zero arg means wait for all output data
* to be sent (performed above) but don't send break.
* This is used by the tcdrain() termios function.
*/
if (!arg)
return send_break(tty, 250);
return 0;
case TCSBRKP: /* support for POSIX tcsendbreak() */
return send_break(tty, arg ? arg*100 : 250);
case TIOCMGET:
return tty_tiocmget(tty, p);
case TIOCMSET:
case TIOCMBIC:
case TIOCMBIS:
return tty_tiocmset(tty, cmd, p);
case TIOCGICOUNT:
retval = tty_tiocgicount(tty, p);
/* For the moment allow fall through to the old method */
if (retval != -EINVAL)
return retval;
break;
case TCFLSH:
switch (arg) {
case TCIFLUSH:
case TCIOFLUSH:
/* flush tty buffer and allow ldisc to process ioctl */
tty_buffer_flush(tty, NULL);
break;
}
break;
case TIOCSSERIAL:
tty_warn_deprecated_flags(p);
break;
case TIOCGPTPEER:
/* Special because the struct file is needed */
return ptm_open_peer(file, tty, (int)arg);
default:
retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
if (tty->ops->ioctl) {
retval = tty->ops->ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_ioctl(file, cmd, arg);
retval = -EINVAL;
if (ld->ops->ioctl) {
retval = ld->ops->ioctl(tty, file, cmd, arg);
if (retval == -ENOIOCTLCMD)
retval = -ENOTTY;
}
tty_ldisc_deref(ld);
return retval;
}
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
int retval = -ENOIOCTLCMD;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
if (tty->ops->compat_ioctl) {
retval = tty->ops->compat_ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
if (!ld)
return hung_up_tty_compat_ioctl(file, cmd, arg);
if (ld->ops->compat_ioctl)
retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
else
retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
tty_ldisc_deref(ld);
return retval;
}
#endif
static int this_tty(const void *t, struct file *file, unsigned fd)
{
if (likely(file->f_op->read != tty_read))
return 0;
return file_tty(file) != t ? 0 : fd + 1;
}
/*
* This implements the "Secure Attention Key" --- the idea is to
* prevent trojan horses by killing all processes associated with this
* tty when the user hits the "Secure Attention Key". Required for
* super-paranoid applications --- see the Orange Book for more details.
*
* This code could be nicer; ideally it should send a HUP, wait a few
* seconds, then send a INT, and then a KILL signal. But you then
* have to coordinate with the init process, since all processes associated
* with the current tty must be dead before the new getty is allowed
* to spawn.
*
* Now, if it would be correct ;-/ The current code has a nasty hole -
* it doesn't catch files in flight. We may send the descriptor to ourselves
* via AF_UNIX socket, close it and later fetch from socket. FIXME.
*
* Nasty bug: do_SAK is being called in interrupt context. This can
* deadlock. We punt it up to process context. AKPM - 16Mar2001
*/
void __do_SAK(struct tty_struct *tty)
{
#ifdef TTY_SOFT_SAK
tty_hangup(tty);
#else
struct task_struct *g, *p;
struct pid *session;
int i;
unsigned long flags;
if (!tty)
return;
spin_lock_irqsave(&tty->ctrl_lock, flags);
session = get_pid(tty->session);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
tty_ldisc_flush(tty);
tty_driver_flush_buffer(tty);
read_lock(&tasklist_lock);
/* Kill the entire session */
do_each_pid_task(session, PIDTYPE_SID, p) {
tty_notice(tty, "SAK: killed process %d (%s): by session\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
} while_each_pid_task(session, PIDTYPE_SID, p);
/* Now kill any processes that happen to have the tty open */
do_each_thread(g, p) {
if (p->signal->tty == tty) {
tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
continue;
}
task_lock(p);
i = iterate_fd(p->files, 0, this_tty, tty);
if (i != 0) {
tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
task_pid_nr(p), p->comm, i - 1);
force_sig(SIGKILL, p);
}
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
put_pid(session);
#endif
}
static void do_SAK_work(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, SAK_work);
__do_SAK(tty);
}
/*
* The tq handling here is a little racy - tty->SAK_work may already be queued.
* Fortunately we don't need to worry, because if ->SAK_work is already queued,
* the values which we write to it will be identical to the values which it
* already has. --akpm
*/
void do_SAK(struct tty_struct *tty)
{
if (!tty)
return;
schedule_work(&tty->SAK_work);
}
EXPORT_SYMBOL(do_SAK);
static int dev_match_devt(struct device *dev, const void *data)
{
const dev_t *devt = data;
return dev->devt == *devt;
}
/* Must put_device() after it's unused! */
static struct device *tty_get_device(struct tty_struct *tty)
{
dev_t devt = tty_devnum(tty);
return class_find_device(tty_class, NULL, &devt, dev_match_devt);
}
/**
* alloc_tty_struct
*
* This subroutine allocates and initializes a tty structure.
*
* Locking: none - tty in question is not exposed at this point
*/
struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
tty = kzalloc(sizeof(*tty), GFP_KERNEL);
if (!tty)
return NULL;
kref_init(&tty->kref);
tty->magic = TTY_MAGIC;
if (tty_ldisc_init(tty)) {
kfree(tty);
return NULL;
}
tty->session = NULL;
tty->pgrp = NULL;
mutex_init(&tty->legacy_mutex);
mutex_init(&tty->throttle_mutex);
init_rwsem(&tty->termios_rwsem);
mutex_init(&tty->winsize_mutex);
init_ldsem(&tty->ldisc_sem);
init_waitqueue_head(&tty->write_wait);
init_waitqueue_head(&tty->read_wait);
INIT_WORK(&tty->hangup_work, do_tty_hangup);
mutex_init(&tty->atomic_write_lock);
spin_lock_init(&tty->ctrl_lock);
spin_lock_init(&tty->flow_lock);
spin_lock_init(&tty->files_lock);
INIT_LIST_HEAD(&tty->tty_files);
INIT_WORK(&tty->SAK_work, do_SAK_work);
tty->driver = driver;
tty->ops = driver->ops;
tty->index = idx;
tty_line_name(driver, idx, tty->name);
tty->dev = tty_get_device(tty);
return tty;
}
/**
* tty_put_char - write one character to a tty
* @tty: tty
* @ch: character
*
* Write one byte to the tty using the provided put_char method
* if present. Returns the number of characters successfully output.
*
* Note: the specific put_char operation in the driver layer may go
* away soon. Don't call it directly, use this method
*/
int tty_put_char(struct tty_struct *tty, unsigned char ch)
{
if (tty->ops->put_char)
return tty->ops->put_char(tty, ch);
return tty->ops->write(tty, &ch, 1);
}
EXPORT_SYMBOL_GPL(tty_put_char);
struct class *tty_class;
static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count)
{
int err;
/* init here, since reused cdevs cause crashes */
driver->cdevs[index] = cdev_alloc();
if (!driver->cdevs[index])
return -ENOMEM;
driver->cdevs[index]->ops = &tty_fops;
driver->cdevs[index]->owner = driver->owner;
err = cdev_add(driver->cdevs[index], dev, count);
if (err)
kobject_put(&driver->cdevs[index]->kobj);
return err;
}
/**
* tty_register_device - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
return tty_register_device_attr(driver, index, device, NULL, NULL);
}
EXPORT_SYMBOL(tty_register_device);
static void tty_device_create_release(struct device *dev)
{
dev_dbg(dev, "releasing...\n");
kfree(dev);
}
/**
* tty_register_device_attr - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
* @drvdata: Driver data to be set to device.
* @attr_grp: Attribute group to be set on device.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device_attr(struct tty_driver *driver,
unsigned index, struct device *device,
void *drvdata,
const struct attribute_group **attr_grp)
{
char name[64];
dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
struct ktermios *tp;
struct device *dev;
int retval;
if (index >= driver->num) {
pr_err("%s: Attempt to register invalid tty line number (%d)\n",
driver->name, index);
return ERR_PTR(-EINVAL);
}
if (driver->type == TTY_DRIVER_TYPE_PTY)
pty_line_name(driver, index, name);
else
tty_line_name(driver, index, name);
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return ERR_PTR(-ENOMEM);
dev->devt = devt;
dev->class = tty_class;
dev->parent = device;
dev->release = tty_device_create_release;
dev_set_name(dev, "%s", name);
dev->groups = attr_grp;
dev_set_drvdata(dev, drvdata);
dev_set_uevent_suppress(dev, 1);
retval = device_register(dev);
if (retval)
goto err_put;
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
/*
* Free any saved termios data so that the termios state is
* reset when reusing a minor number.
*/
tp = driver->termios[index];
if (tp) {
driver->termios[index] = NULL;
kfree(tp);
}
retval = tty_cdev_add(driver, devt, index, 1);
if (retval)
goto err_del;
}
dev_set_uevent_suppress(dev, 0);
kobject_uevent(&dev->kobj, KOBJ_ADD);
return dev;
err_del:
device_del(dev);
err_put:
put_device(dev);
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(tty_register_device_attr);
/**
* tty_unregister_device - unregister a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
*
* If a tty device is registered with a call to tty_register_device() then
* this function must be called when the tty device is gone.
*
* Locking: ??
*/
void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
}
EXPORT_SYMBOL(tty_unregister_device);
/**
* __tty_alloc_driver -- allocate tty driver
* @lines: count of lines this driver can handle at most
* @owner: module which is responsible for this driver
* @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
*
* This should not be called directly, some of the provided macros should be
* used instead. Use IS_ERR and friends on @retval.
*/
struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
unsigned long flags)
{
struct tty_driver *driver;
unsigned int cdevs = 1;
int err;
if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
return ERR_PTR(-EINVAL);
driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
if (!driver)
return ERR_PTR(-ENOMEM);
kref_init(&driver->kref);
driver->magic = TTY_DRIVER_MAGIC;
driver->num = lines;
driver->owner = owner;
driver->flags = flags;
if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
GFP_KERNEL);
driver->termios = kcalloc(lines, sizeof(*driver->termios),
GFP_KERNEL);
if (!driver->ttys || !driver->termios) {
err = -ENOMEM;
goto err_free_all;
}
}
if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
driver->ports = kcalloc(lines, sizeof(*driver->ports),
GFP_KERNEL);
if (!driver->ports) {
err = -ENOMEM;
goto err_free_all;
}
cdevs = lines;
}
driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
if (!driver->cdevs) {
err = -ENOMEM;
goto err_free_all;
}
return driver;
err_free_all:
kfree(driver->ports);
kfree(driver->ttys);
kfree(driver->termios);
kfree(driver->cdevs);
kfree(driver);
return ERR_PTR(err);
}
EXPORT_SYMBOL(__tty_alloc_driver);
static void destruct_tty_driver(struct kref *kref)
{
struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
int i;
struct ktermios *tp;
if (driver->flags & TTY_DRIVER_INSTALLED) {
for (i = 0; i < driver->num; i++) {
tp = driver->termios[i];
if (tp) {
driver->termios[i] = NULL;
kfree(tp);
}
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
tty_unregister_device(driver, i);
}
proc_tty_unregister_driver(driver);
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
cdev_del(driver->cdevs[0]);
}
kfree(driver->cdevs);
kfree(driver->ports);
kfree(driver->termios);
kfree(driver->ttys);
kfree(driver);
}
void tty_driver_kref_put(struct tty_driver *driver)
{
kref_put(&driver->kref, destruct_tty_driver);
}
EXPORT_SYMBOL(tty_driver_kref_put);
void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op)
{
driver->ops = op;
};
EXPORT_SYMBOL(tty_set_operations);
void put_tty_driver(struct tty_driver *d)
{
tty_driver_kref_put(d);
}
EXPORT_SYMBOL(put_tty_driver);
/*
* Called by a tty driver to register itself.
*/
int tty_register_driver(struct tty_driver *driver)
{
int error;
int i;
dev_t dev;
struct device *d;
if (!driver->major) {
error = alloc_chrdev_region(&dev, driver->minor_start,
driver->num, driver->name);
if (!error) {
driver->major = MAJOR(dev);
driver->minor_start = MINOR(dev);
}
} else {
dev = MKDEV(driver->major, driver->minor_start);
error = register_chrdev_region(dev, driver->num, driver->name);
}
if (error < 0)
goto err;
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
error = tty_cdev_add(driver, dev, 0, driver->num);
if (error)
goto err_unreg_char;
}
mutex_lock(&tty_mutex);
list_add(&driver->tty_drivers, &tty_drivers);
mutex_unlock(&tty_mutex);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
for (i = 0; i < driver->num; i++) {
d = tty_register_device(driver, i, NULL);
if (IS_ERR(d)) {
error = PTR_ERR(d);
goto err_unreg_devs;
}
}
}
proc_tty_register_driver(driver);
driver->flags |= TTY_DRIVER_INSTALLED;
return 0;
err_unreg_devs:
for (i--; i >= 0; i--)
tty_unregister_device(driver, i);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
err_unreg_char:
unregister_chrdev_region(dev, driver->num);
err:
return error;
}
EXPORT_SYMBOL(tty_register_driver);
/*
* Called by a tty driver to unregister itself.
*/
int tty_unregister_driver(struct tty_driver *driver)
{
#if 0
/* FIXME */
if (driver->refcount)
return -EBUSY;
#endif
unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
driver->num);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
return 0;
}
EXPORT_SYMBOL(tty_unregister_driver);
dev_t tty_devnum(struct tty_struct *tty)
{
return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}
EXPORT_SYMBOL(tty_devnum);
void tty_default_fops(struct file_operations *fops)
{
*fops = tty_fops;
}
static char *tty_devnode(struct device *dev, umode_t *mode)
{
if (!mode)
return NULL;
if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
dev->devt == MKDEV(TTYAUX_MAJOR, 2))
*mode = 0666;
return NULL;
}
static int __init tty_class_init(void)
{
tty_class = class_create(THIS_MODULE, "tty");
if (IS_ERR(tty_class))
return PTR_ERR(tty_class);
tty_class->devnode = tty_devnode;
return 0;
}
postcore_initcall(tty_class_init);
/* 3/2004 jmc: why do these devices exist? */
static struct cdev tty_cdev, console_cdev;
static ssize_t show_cons_active(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct console *cs[16];
int i = 0;
struct console *c;
ssize_t count = 0;
console_lock();
for_each_console(c) {
if (!c->device)
continue;
if (!c->write)
continue;
if ((c->flags & CON_ENABLED) == 0)
continue;
cs[i++] = c;
if (i >= ARRAY_SIZE(cs))
break;
}
while (i--) {
int index = cs[i]->index;
struct tty_driver *drv = cs[i]->device(cs[i], &index);
/* don't resolve tty0 as some programs depend on it */
if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
count += tty_line_name(drv, index, buf + count);
else
count += sprintf(buf + count, "%s%d",
cs[i]->name, cs[i]->index);
count += sprintf(buf + count, "%c", i ? ' ':'\n');
}
console_unlock();
return count;
}
static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
static struct attribute *cons_dev_attrs[] = {
&dev_attr_active.attr,
NULL
};
ATTRIBUTE_GROUPS(cons_dev);
static struct device *consdev;
void console_sysfs_notify(void)
{
if (consdev)
sysfs_notify(&consdev->kobj, NULL, "active");
}
/*
* Ok, now we can initialize the rest of the tty devices and can count
* on memory allocations, interrupts etc..
*/
int __init tty_init(void)
{
tty_sysctl_init();
cdev_init(&tty_cdev, &tty_fops);
if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
panic("Couldn't register /dev/tty driver\n");
device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
cdev_init(&console_cdev, &console_fops);
if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
panic("Couldn't register /dev/console driver\n");
consdev = device_create_with_groups(tty_class, NULL,
MKDEV(TTYAUX_MAJOR, 1), NULL,
cons_dev_groups, "console");
if (IS_ERR(consdev))
consdev = NULL;
#ifdef CONFIG_VT
vty_init(&console_fops);
#endif
return 0;
}