cregit-Linux how code gets into the kernel

Release 4.14 drivers/tty/pty.c

Directory: drivers/tty
// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Added support for a Unix98-style ptmx device.
 *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/fcntl.h>
#include <linux/sched/signal.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/ioctl.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

#ifdef CONFIG_UNIX98_PTYS

static struct tty_driver *ptm_driver;

static struct tty_driver *pts_driver;
static DEFINE_MUTEX(devpts_mutex);
#endif




static void pty_close(struct tty_struct *tty, struct file *filp)
{
	BUG_ON(!tty);
	if (tty->driver->subtype == PTY_TYPE_MASTER)
		WARN_ON(tty->count > 1);
	else {
		if (tty_io_error(tty))
			return;
		if (tty->count > 2)
			return;
	}
	set_bit(TTY_IO_ERROR, &tty->flags);
	wake_up_interruptible(&tty->read_wait);
	wake_up_interruptible(&tty->write_wait);
	spin_lock_irq(&tty->ctrl_lock);
	tty->packet = 0;
	spin_unlock_irq(&tty->ctrl_lock);
	/* Review - krefs on tty_link ?? */
	if (!tty->link)
		return;
	set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	wake_up_interruptible(&tty->link->read_wait);
	wake_up_interruptible(&tty->link->write_wait);
	if (tty->driver->subtype == PTY_TYPE_MASTER) {
		set_bit(TTY_OTHER_CLOSED, &tty->flags);
#ifdef CONFIG_UNIX98_PTYS
		if (tty->driver == ptm_driver) {
			mutex_lock(&devpts_mutex);
			if (tty->link->driver_data)
				devpts_pty_kill(tty->link->driver_data);
			mutex_unlock(&devpts_mutex);
		}
#endif
		tty_vhangup(tty->link);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)13058.30%1346.43%


Peter Hurley4218.83%414.29%


Alan Cox219.42%310.71%


Greg Kroah-Hartman135.83%13.57%


Zou Nan hai62.69%13.57%


Brian Bloniarz31.35%13.57%


Jiri Slaby20.90%13.57%


Al Viro20.90%13.57%


Eric W. Biedermann20.90%13.57%


Arnd Bergmann10.45%13.57%


Sukadev Bhattiprolu10.45%13.57%


Total223100.00%28100.00%



/*
 * The unthrottle routine is called by the line discipline to signal
 * that it can receive more characters.  For PTY's, the TTY_THROTTLED
 * flag is always set, to force the line discipline to always call the
 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
 * characters in the queue.  This is necessary since each time this
 * happens, we need to wake up any sleeping processes that could be
 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
 * for the pty buffer to be drained.
 */



static void pty_unthrottle(struct tty_struct *tty)
{
	tty_wakeup(tty->link);
	set_bit(TTY_THROTTLED, &tty->flags);
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2692.86%150.00%


Alan Cox27.14%150.00%


Total28100.00%2100.00%



/**
 *      pty_write               -       write to a pty
 *      @tty: the tty we write from
 *      @buf: kernel buffer of data
 *      @count: bytes to write
 *
 *      Our "hardware" write method. Data is coming from the ldisc which
 *      may be in a non sleeping state. We simply throw this at the other
 *      end of the link as if we were an IRQ handler receiving stuff for
 *      the other side of the pty/tty pair.
 */




static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
{
	struct tty_struct *to = tty->link;

	if (tty->stopped)
		return 0;

	if (c > 0) {
		/* Stuff the data into the input queue of the other end */
		c = tty_insert_flip_string(to->port, buf, c);
		/* And shovel */
		if (c)
			tty_flip_buffer_push(to->port);
	}
	return c;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)5573.33%654.55%


Alan Cox1013.33%19.09%


Linus Torvalds68.00%218.18%


Jiri Slaby45.33%218.18%


Total75100.00%11100.00%



/**
 *      pty_write_room  -       write space
 *      @tty: tty we are writing from
 *
 *      Report how many bytes the ldisc can send into the queue for
 *      the other device.
 */




static int pty_write_room(struct tty_struct *tty)
{
	if (tty->stopped)
		return 0;
	return tty_buffer_space_avail(tty->link->port);
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)1550.00%125.00%


Linus Torvalds930.00%125.00%


Alan Cox310.00%125.00%


Peter Hurley310.00%125.00%


Total30100.00%4100.00%



/**
 *      pty_chars_in_buffer     -       characters currently in our tx queue
 *      @tty: our tty
 *
 *      Report how much we have in the transmit queue. As everything is
 *      instantly at the other end this is easy to implement.
 */




static int pty_chars_in_buffer(struct tty_struct *tty)
{
	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)1178.57%266.67%


Alan Cox321.43%133.33%


Total14100.00%3100.00%



/* Set the lock flag on a pty */



static int pty_set_lock(struct tty_struct *tty, int __user *arg)
{
	int val;
	if (get_user(val, arg))
		return -EFAULT;
	if (val)
		set_bit(TTY_PTY_LOCK, &tty->flags);
	else
		clear_bit(TTY_PTY_LOCK, &tty->flags);
	return 0;
}


Contributors
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Linus Torvalds (pre-git)5998.33%150.00%


Al Viro11.67%150.00%


Total60100.00%2100.00%






static int pty_get_lock(struct tty_struct *tty, int __user *arg)
{
	int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
	return put_user(locked, arg);
}


Contributors
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Cyrill V. Gorcunov37100.00%1100.00%


Total37100.00%1100.00%



/* Set the packet mode on a pty */



static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
{
	int pktmode;

	if (get_user(pktmode, arg))
		return -EFAULT;

	spin_lock_irq(&tty->ctrl_lock);
	if (pktmode) {
		if (!tty->packet) {
			tty->link->ctrl_status = 0;
			smp_mb();
			tty->packet = 1;
		}
	} else
		tty->packet = 0;
	spin_unlock_irq(&tty->ctrl_lock);

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Cyrill V. Gorcunov7987.78%133.33%


Peter Hurley1112.22%266.67%


Total90100.00%3100.00%



/* Get the packet mode of a pty */



static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
{
	int pktmode = tty->packet;
	return put_user(pktmode, arg);
}


Contributors
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Cyrill V. Gorcunov31100.00%1100.00%


Total31100.00%1100.00%



/* Send a signal to the slave */



static int pty_signal(struct tty_struct *tty, int sig)
{
	struct pid *pgrp;

	if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
		return -EINVAL;

	if (tty->link) {
		pgrp = tty_get_pgrp(tty->link);
		if (pgrp)
			kill_pgrp(pgrp, sig, 1);
		put_pid(pgrp);
	}
	return 0;
}


Contributors
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Howard Chu5269.33%133.33%


Peter Hurley2330.67%266.67%


Total75100.00%3100.00%






static void pty_flush_buffer(struct tty_struct *tty)
{
	struct tty_struct *to = tty->link;

	if (!to)
		return;

	tty_buffer_flush(to, NULL);
	if (to->packet) {
		spin_lock_irq(&tty->ctrl_lock);
		tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
		wake_up_interruptible(&to->read_wait);
		spin_unlock_irq(&tty->ctrl_lock);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)4867.61%450.00%


Alan Cox1419.72%112.50%


Peter Hurley811.27%225.00%


Wang YanQing11.41%112.50%


Total71100.00%8100.00%






static int pty_open(struct tty_struct *tty, struct file *filp)
{
	if (!tty || !tty->link)
		return -ENODEV;

	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
		goto out;
	if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
		goto out;
	if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
		goto out;

	clear_bit(TTY_IO_ERROR, &tty->flags);
	clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
	set_bit(TTY_THROTTLED, &tty->flags);
	return 0;

out:
	set_bit(TTY_IO_ERROR, &tty->flags);
	return -EIO;
}


Contributors
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Linus Torvalds (pre-git)9973.88%975.00%


Peter Hurley3526.12%325.00%


Total134100.00%12100.00%






static void pty_set_termios(struct tty_struct *tty,
					struct ktermios *old_termios)
{
	/* See if packet mode change of state. */
	if (tty->link && tty->link->packet) {
		int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
		int old_flow = ((old_termios->c_iflag & IXON) &&
				(old_termios->c_cc[VSTOP] == '\023') &&
				(old_termios->c_cc[VSTART] == '\021'));
		int new_flow = (I_IXON(tty) &&
				STOP_CHAR(tty) == '\023' &&
				START_CHAR(tty) == '\021');
		if ((old_flow != new_flow) || extproc) {
			spin_lock_irq(&tty->ctrl_lock);
			if (old_flow != new_flow) {
				tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
				if (new_flow)
					tty->ctrl_status |= TIOCPKT_DOSTOP;
				else
					tty->ctrl_status |= TIOCPKT_NOSTOP;
			}
			if (extproc)
				tty->ctrl_status |= TIOCPKT_IOCTL;
			spin_unlock_irq(&tty->ctrl_lock);
			wake_up_interruptible(&tty->link->read_wait);
		}
	}

	tty->termios.c_cflag &= ~(CSIZE | PARENB);
	tty->termios.c_cflag |= (CS8 | CREAD);
}


Contributors
PersonTokensPropCommitsCommitProp
Peter Hurley17480.93%350.00%


Linus Torvalds (pre-git)3817.67%116.67%


Alan Cox31.40%233.33%


Total215100.00%6100.00%



/**
 *      pty_do_resize           -       resize event
 *      @tty: tty being resized
 *      @ws: window size being set.
 *
 *      Update the termios variables and send the necessary signals to
 *      peform a terminal resize correctly
 */




static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
{
	struct pid *pgrp, *rpgrp;
	struct tty_struct *pty = tty->link;

	/* For a PTY we need to lock the tty side */
	mutex_lock(&tty->winsize_mutex);
	if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
		goto done;

	/* Signal the foreground process group of both ptys */
	pgrp = tty_get_pgrp(tty);
	rpgrp = tty_get_pgrp(pty);

	if (pgrp)
		kill_pgrp(pgrp, SIGWINCH, 1);
	if (rpgrp != pgrp && rpgrp)
		kill_pgrp(rpgrp, SIGWINCH, 1);

	put_pid(pgrp);
	put_pid(rpgrp);

	tty->winsize = *ws;
	pty->winsize = *ws;	/* Never used so will go away soon */
done:
	mutex_unlock(&tty->winsize_mutex);
	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Alan Cox13994.56%125.00%


Peter Hurley74.76%250.00%


Josh Triplett10.68%125.00%


Total147100.00%4100.00%



/**
 *      pty_start - start() handler
 *      pty_stop  - stop() handler
 *      @tty: tty being flow-controlled
 *
 *      Propagates the TIOCPKT status to the master pty.
 *
 *      NB: only the master pty can be in packet mode so only the slave
 *          needs start()/stop() handlers
 */



static void pty_start(struct tty_struct *tty)
{
	unsigned long flags;

	if (tty->link && tty->link->packet) {
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		tty->ctrl_status &= ~TIOCPKT_STOP;
		tty->ctrl_status |= TIOCPKT_START;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Peter Hurley74100.00%2100.00%


Total74100.00%2100.00%






static void pty_stop(struct tty_struct *tty)
{
	unsigned long flags;

	if (tty->link && tty->link->packet) {
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		tty->ctrl_status &= ~TIOCPKT_START;
		tty->ctrl_status |= TIOCPKT_STOP;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Peter Hurley74100.00%2100.00%


Total74100.00%2100.00%



/**
 *      pty_common_install              -       set up the pty pair
 *      @driver: the pty driver
 *      @tty: the tty being instantiated
 *      @legacy: true if this is BSD style
 *
 *      Perform the initial set up for the tty/pty pair. Called from the
 *      tty layer when the port is first opened.
 *
 *      Locking: the caller must hold the tty_mutex
 */



static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
		bool legacy)
{
	struct tty_struct *o_tty;
	struct tty_port *ports[2];
	int idx = tty->index;
	int retval = -ENOMEM;

	/* Opening the slave first has always returned -EIO */
	if (driver->subtype != PTY_TYPE_MASTER)
		return -EIO;

	ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
	ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
	if (!ports[0] || !ports[1])
		goto err;
	if (!try_module_get(driver->other->owner)) {
		/* This cannot in fact currently happen */
		goto err;
	}
	o_tty = alloc_tty_struct(driver->other, idx);
	if (!o_tty)
		goto err_put_module;

	tty_set_lock_subclass(o_tty);
	lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);

	if (legacy) {
		/* We always use new tty termios data so we can do this
                   the easy way .. */
		tty_init_termios(tty);
		tty_init_termios(o_tty);

		driver->other->ttys[idx] = o_tty;
		driver->ttys[idx] = tty;
	} else {
		memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
		tty->termios = driver->init_termios;
		memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
		o_tty->termios = driver->other->init_termios;
	}

	/*
         * Everything allocated ... set up the o_tty structure.
         */
	tty_driver_kref_get(driver->other);
	/* Establish the links in both directions */
	tty->link   = o_tty;
	o_tty->link = tty;
	tty_port_init(ports[0]);
	tty_port_init(ports[1]);
	tty_buffer_set_limit(ports[0], 8192);
	tty_buffer_set_limit(ports[1], 8192);
	o_tty->port = ports[0];
	tty->port = ports[1];
	o_tty->port->itty = o_tty;

	tty_buffer_set_lock_subclass(o_tty->port);

	tty_driver_kref_get(driver);
	tty->count++;
	o_tty->count++;
	return 0;

err_put_module:
	module_put(driver->other->owner);
err:
	kfree(ports[0]);
	kfree(ports[1]);
	return retval;
}


Contributors
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Jiri Slaby17143.96%430.77%


Alan Cox14035.99%215.38%


Peter Hurley6015.42%538.46%


Rasmus Villemoes184.63%215.38%


Total389100.00%13100.00%






static void pty_cleanup(struct tty_struct *tty)
{
	tty_port_put(tty->port);
}


Contributors
PersonTokensPropCommitsCommitProp
Jiri Slaby18100.00%2100.00%


Total18100.00%2100.00%



/* Traditional BSD devices */
#ifdef CONFIG_LEGACY_PTYS




static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
{
	return pty_common_install(driver, tty, true);
}


Contributors
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Jiri Slaby26100.00%1100.00%


Total26100.00%1100.00%






static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
{
	struct tty_struct *pair = tty->link;
	driver->ttys[tty->index] = NULL;
	if (pair)
		pair->driver->ttys[pair->index] = NULL;
}


Contributors
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Alan Cox53100.00%1100.00%


Total53100.00%1100.00%






static int pty_bsd_ioctl(struct tty_struct *tty,
			 unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
		return pty_set_lock(tty, (int __user *) arg);
	case TIOCGPTLCK: /* Get PT Lock status */
		return pty_get_lock(tty, (int __user *)arg);
	case TIOCPKT: /* Set PT packet mode */
		return pty_set_pktmode(tty, (int __user *)arg);
	case TIOCGPKT: /* Get PT packet mode */
		return pty_get_pktmode(tty, (int __user *)arg);
	case TIOCSIG:    /* Send signal to other side of pty */
		return pty_signal(tty, (int) arg);
	case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
		return -EINVAL;
	}
	return -ENOIOCTLCMD;
}


Contributors
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Cyrill V. Gorcunov5142.50%233.33%


Christoph Hellwig3730.83%116.67%


Howard Chu1512.50%116.67%


Andrew Morton97.50%116.67%


Jiri Slaby86.67%116.67%


Total120100.00%6100.00%






static long pty_bsd_compat_ioctl(struct tty_struct *tty,
				 unsigned int cmd, unsigned long arg)
{
	/*
         * PTY ioctls don't require any special translation between 32-bit and
         * 64-bit userspace, they are already compatible.
         */
	return pty_bsd_ioctl(tty, cmd, arg);
}


Contributors
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Aleksa Sarai30100.00%1100.00%


Total30100.00%1100.00%




static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
/*
 * not really modular, but the easiest way to keep compat with existing
 * bootargs behaviour is to continue using module_param here.
 */
module_param(legacy_count, int, 0);

/*
 * The master side of a pty can do TIOCSPTLCK and thus
 * has pty_bsd_ioctl.
 */

static const struct tty_operations master_pty_ops_bsd = {
	.install = pty_install,
	.open = pty_open,
	.close = pty_close,
	.write = pty_write,
	.write_room = pty_write_room,
	.flush_buffer = pty_flush_buffer,
	.chars_in_buffer = pty_chars_in_buffer,
	.unthrottle = pty_unthrottle,
	.ioctl = pty_bsd_ioctl,
	.compat_ioctl = pty_bsd_compat_ioctl,
	.cleanup = pty_cleanup,
	.resize = pty_resize,
	.remove = pty_remove
};


static const struct tty_operations slave_pty_ops_bsd = {
	.install = pty_install,
	.open = pty_open,
	.close = pty_close,
	.write = pty_write,
	.write_room = pty_write_room,
	.flush_buffer = pty_flush_buffer,
	.chars_in_buffer = pty_chars_in_buffer,
	.unthrottle = pty_unthrottle,
	.set_termios = pty_set_termios,
	.cleanup = pty_cleanup,
	.resize = pty_resize,
	.start = pty_start,
	.stop = pty_stop,
	.remove = pty_remove
};




static void __init legacy_pty_init(void)
{
	struct tty_driver *pty_driver, *pty_slave_driver;

	if (legacy_count <= 0)
		return;

	pty_driver = tty_alloc_driver(legacy_count,
			TTY_DRIVER_RESET_TERMIOS |
			TTY_DRIVER_REAL_RAW |
			TTY_DRIVER_DYNAMIC_ALLOC);
	if (IS_ERR(pty_driver))
		panic("Couldn't allocate pty driver");

	pty_slave_driver = tty_alloc_driver(legacy_count,
			TTY_DRIVER_RESET_TERMIOS |
			TTY_DRIVER_REAL_RAW |
			TTY_DRIVER_DYNAMIC_ALLOC);
	if (IS_ERR(pty_slave_driver))
		panic("Couldn't allocate pty slave driver");

	pty_driver->driver_name = "pty_master";
	pty_driver->name = "pty";
	pty_driver->major = PTY_MASTER_MAJOR;
	pty_driver->minor_start = 0;
	pty_driver->type = TTY_DRIVER_TYPE_PTY;
	pty_driver->subtype = PTY_TYPE_MASTER;
	pty_driver->init_termios = tty_std_termios;
	pty_driver->init_termios.c_iflag = 0;
	pty_driver->init_termios.c_oflag = 0;
	pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pty_driver->init_termios.c_lflag = 0;
	pty_driver->init_termios.c_ispeed = 38400;
	pty_driver->init_termios.c_ospeed = 38400;
	pty_driver->other = pty_slave_driver;
	tty_set_operations(pty_driver, &master_pty_ops_bsd);

	pty_slave_driver->driver_name = "pty_slave";
	pty_slave_driver->name = "ttyp";
	pty_slave_driver->major = PTY_SLAVE_MAJOR;
	pty_slave_driver->minor_start = 0;
	pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
	pty_slave_driver->subtype = PTY_TYPE_SLAVE;
	pty_slave_driver->init_termios = tty_std_termios;
	pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pty_slave_driver->init_termios.c_ispeed = 38400;
	pty_slave_driver->init_termios.c_ospeed = 38400;
	pty_slave_driver->other = pty_driver;
	tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);

	if (tty_register_driver(pty_driver))
		panic("Couldn't register pty driver");
	if (tty_register_driver(pty_slave_driver))
		panic("Couldn't register pty slave driver");
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)15051.72%1052.63%


Al Viro6422.07%15.26%


Alan Cox3211.03%15.26%


Jiri Slaby144.83%15.26%


Linus Torvalds103.45%15.26%


Kay Sievers93.10%15.26%


Dan Carpenter62.07%15.26%


Christoph Hellwig31.03%15.26%


Andrew Morton20.69%210.53%


Total290100.00%19100.00%



#else



static inline void legacy_pty_init(void) { }

Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig8100.00%1100.00%


Total8100.00%1100.00%



#endif

/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS

static struct cdev ptmx_cdev;

/**
 *      ptm_open_peer - open the peer of a pty
 *      @master: the open struct file of the ptmx device node
 *      @tty: the master of the pty being opened
 *      @flags: the flags for open
 *
 *      Provide a race free way for userspace to open the slave end of a pty
 *      (where they have the master fd and cannot access or trust the mount
 *      namespace /dev/pts was mounted inside).
 */



int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
{
	int fd = -1;
	struct file *filp;
	int retval = -EINVAL;
	struct path path;

	if (tty->driver != ptm_driver)
		return -EIO;

	fd = get_unused_fd_flags(0);
	if (fd < 0) {
		retval = fd;
		goto err;
	}

	/* Compute the slave's path */
	path.mnt = devpts_mntget(master, tty->driver_data);
	if (IS_ERR(path.mnt)) {
		retval = PTR_ERR(path.mnt);
		goto err_put;
	}
	path.dentry = tty->link->driver_data;

	filp = dentry_open(&path, flags, current_cred());
	mntput(path.mnt);
	if (IS_ERR(filp)) {
		retval = PTR_ERR(filp);
		goto err_put;
	}

	fd_install(fd, filp);
	return fd;

err_put:
	put_unused_fd(fd);
err:
	return retval;
}


Contributors
PersonTokensPropCommitsCommitProp
Arnd Bergmann10155.80%150.00%


Eric W. Biedermann8044.20%150.00%


Total181100.00%2100.00%






static int pty_unix98_ioctl(struct tty_struct *tty,
			    unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
		return pty_set_lock(tty, (int __user *)arg);
	case TIOCGPTLCK: /* Get PT Lock status */
		return pty_get_lock(tty, (int __user *)arg);
	case TIOCPKT: /* Set PT packet mode */
		return pty_set_pktmode(tty, (int __user *)arg);
	case TIOCGPKT: /* Get PT packet mode */
		return pty_get_pktmode(tty, (int __user *)arg);
	case TIOCGPTN: /* Get PT Number */
		return put_user(tty->index, (unsigned int __user *)arg);
	case TIOCSIG:    /* Send signal to other side of pty */
		return pty_signal(tty, (int) arg);
	}

	return -ENOIOCTLCMD;
}


Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig6650.00%125.00%


Cyrill V. Gorcunov5138.64%250.00%


Howard Chu1511.36%125.00%


Total132100.00%4100.00%






static long pty_unix98_compat_ioctl(struct tty_struct *tty,
				 unsigned int cmd, unsigned long arg)
{
	/*
         * PTY ioctls don't require any special translation between 32-bit and
         * 64-bit userspace, they are already compatible.
         */
	return pty_unix98_ioctl(tty, cmd, arg);
}


Contributors
PersonTokensPropCommitsCommitProp
Aleksa Sarai30100.00%1100.00%


Total30100.00%1100.00%



/**
 *      ptm_unix98_lookup       -       find a pty master
 *      @driver: ptm driver
 *      @idx: tty index
 *
 *      Look up a pty master device. Called under the tty_mutex for now.
 *      This provides our locking.
 */




static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
		struct file *file, int idx)
{
	/* Master must be open via /dev/ptmx */
	return ERR_PTR(-EIO);
}


Contributors
PersonTokensPropCommitsCommitProp
Alan Cox1965.52%125.00%


Konstantin Khlebnikov517.24%125.00%


Sukadev Bhattiprolu310.34%125.00%


Linus Torvalds26.90%125.00%


Total29100.00%4100.00%



/**
 *      pts_unix98_lookup       -       find a pty slave
 *      @driver: pts driver
 *      @idx: tty index
 *
 *      Look up a pty master device. Called under the tty_mutex for now.
 *      This provides our locking for the tty pointer.
 */




static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
		struct file *file, int idx)
{
	struct tty_struct *tty;

	mutex_lock(&devpts_mutex);
	tty = devpts_get_priv(file->f_path.dentry);
	mutex_unlock(&devpts_mutex);
	/* Master must be open before slave */
	if (!tty)
		return ERR_PTR(-EIO);
	return tty;
}


Contributors
PersonTokensPropCommitsCommitProp
Alan Cox5483.08%240.00%


Linus Torvalds710.77%120.00%


Sukadev Bhattiprolu34.62%120.00%


Jiri Slaby11.54%120.00%


Total65100.00%5100.00%






static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
{
	return pty_common_install(driver, tty, false);
}


Contributors
PersonTokensPropCommitsCommitProp
Alan Cox2492.31%266.67%


Jiri Slaby27.69%133.33%


Total26100.00%3100.00%



/* this is called once with whichever end is closed last */



static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
{
	struct pts_fs_info *fsi;

	if (tty->driver->subtype == PTY_TYPE_MASTER)
		fsi = tty->driver_data;
	else
		fsi = tty->link->driver_data;

	if (fsi) {
		devpts_kill_index(fsi, tty->index);
		devpts_release(fsi);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Herton Ronaldo Krzesinski2842.42%112.50%


Jiri Slaby2334.85%337.50%


Colin Ian King69.09%112.50%


Linus Torvalds69.09%112.50%


Alan Cox23.03%112.50%


Eric W. Biedermann11.52%112.50%


Total66100.00%8100.00%






static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
{
	seq_printf(m, "tty-index:\t%d\n", tty->index);
}


Contributors
PersonTokensPropCommitsCommitProp
Masatake YAMATO27100.00%1100.00%


Total27100.00%1100.00%




static const struct tty_operations ptm_unix98_ops = {
	.lookup = ptm_unix98_lookup,
	.install = pty_unix98_install,
	.remove = pty_unix98_remove,
	.open = pty_open,
	.close = pty_close,
	.write = pty_write,
	.write_room = pty_write_room,
	.flush_buffer = pty_flush_buffer,
	.chars_in_buffer = pty_chars_in_buffer,
	.unthrottle = pty_unthrottle,
	.ioctl = pty_unix98_ioctl,
	.compat_ioctl = pty_unix98_compat_ioctl,
	.resize = pty_resize,
	.cleanup = pty_cleanup,
	.show_fdinfo = pty_show_fdinfo,
};


static const struct tty_operations pty_unix98_ops = {
	.lookup = pts_unix98_lookup,
	.install = pty_unix98_install,
	.remove = pty_unix98_remove,
	.open = pty_open,
	.close = pty_close,
	.write = pty_write,
	.write_room = pty_write_room,
	.flush_buffer = pty_flush_buffer,
	.chars_in_buffer = pty_chars_in_buffer,
	.unthrottle = pty_unthrottle,
	.set_termios = pty_set_termios,
	.start = pty_start,
	.stop = pty_stop,
	.cleanup = pty_cleanup,
};

/**
 *      ptmx_open               -       open a unix 98 pty master
 *      @inode: inode of device file
 *      @filp: file pointer to tty
 *
 *      Allocate a unix98 pty master device from the ptmx driver.
 *
 *      Locking: tty_mutex protects the init_dev work. tty->count should
 *              protect the rest.
 *              allocated_ptys_lock handles the list of free pty numbers
 */




static int ptmx_open(struct inode *inode, struct file *filp)
{
	struct pts_fs_info *fsi;
	struct tty_struct *tty;
	struct dentry *dentry;
	int retval;
	int index;

	nonseekable_open(inode, filp);

	/* We refuse fsnotify events on ptmx, since it's a shared resource */
	filp->f_mode |= FMODE_NONOTIFY;

	retval = tty_alloc_file(filp);
	if (retval)
		return retval;

	fsi = devpts_acquire(filp);
	if (IS_ERR(fsi)) {
		retval = PTR_ERR(fsi);
		goto out_free_file;
	}

	/* find a device that is not in use. */
	mutex_lock(&devpts_mutex);
	index = devpts_new_index(fsi);
	mutex_unlock(&devpts_mutex);

	retval = index;
	if (index < 0)
		goto out_put_fsi;


	mutex_lock(&tty_mutex);
	tty = tty_init_dev(ptm_driver, index);
	/* The tty returned here is locked so we can safely
           drop the mutex */
	mutex_unlock(&tty_mutex);

	retval = PTR_ERR(tty);
	if (IS_ERR(tty))
		goto out;

	/*
         * From here on out, the tty is "live", and the index and
         * fsi will be killed/put by the tty_release()
         */
	set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
	tty->driver_data = fsi;

	tty_add_file(tty, filp);

	dentry = devpts_pty_new(fsi, index, tty->link);
	if (IS_ERR(dentry)) {
		retval = PTR_ERR(dentry);
		goto err_release;
	}
	tty->link->driver_data = dentry;

	retval = ptm_driver->ops->open(tty, filp);
	if (retval)
		goto err_release;

	tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);

	tty_unlock(tty);
	return 0;
err_release:
	tty_unlock(tty);
	// This will also put-ref the fsi
	tty_release(inode, filp);
	return retval;
out:
	devpts_kill_index(fsi, index);
out_put_fsi:
	devpts_release(fsi);
out_free_file:
	tty_free_file(filp);
	return retval;
}


Contributors
PersonTokensPropCommitsCommitProp
Alan Cox14646.95%625.00%


Linus Torvalds6420.58%312.50%


Jiri Slaby4113.18%416.67%


Peter Hurley227.07%312.50%


Eric W. Biedermann185.79%28.33%


Arnd Bergmann82.57%14.17%


Nicholas Piggin61.93%28.33%


Sukadev Bhattiprolu41.29%14.17%


Greg Kroah-Hartman10.32%14.17%


Herton Ronaldo Krzesinski10.32%14.17%


Total311100.00%24100.00%




static struct file_operations ptmx_fops __ro_after_init;




static void __init unix98_pty_init(void)
{
	ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
			TTY_DRIVER_RESET_TERMIOS |
			TTY_DRIVER_REAL_RAW |
			TTY_DRIVER_DYNAMIC_DEV |
			TTY_DRIVER_DEVPTS_MEM |
			TTY_DRIVER_DYNAMIC_ALLOC);
	if (IS_ERR(ptm_driver))
		panic("Couldn't allocate Unix98 ptm driver");
	pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
			TTY_DRIVER_RESET_TERMIOS |
			TTY_DRIVER_REAL_RAW |
			TTY_DRIVER_DYNAMIC_DEV |
			TTY_DRIVER_DEVPTS_MEM |
			TTY_DRIVER_DYNAMIC_ALLOC);
	if (IS_ERR(pts_driver))
		panic("Couldn't allocate Unix98 pts driver");

	ptm_driver->driver_name = "pty_master";
	ptm_driver->name = "ptm";
	ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
	ptm_driver->minor_start = 0;
	ptm_driver->type = TTY_DRIVER_TYPE_PTY;
	ptm_driver->subtype = PTY_TYPE_MASTER;
	ptm_driver->init_termios = tty_std_termios;
	ptm_driver->init_termios.c_iflag = 0;
	ptm_driver->init_termios.c_oflag = 0;
	ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	ptm_driver->init_termios.c_lflag = 0;
	ptm_driver->init_termios.c_ispeed = 38400;
	ptm_driver->init_termios.c_ospeed = 38400;
	ptm_driver->other = pts_driver;
	tty_set_operations(ptm_driver, &ptm_unix98_ops);

	pts_driver->driver_name = "pty_slave";
	pts_driver->name = "pts";
	pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
	pts_driver->minor_start = 0;
	pts_driver->type = TTY_DRIVER_TYPE_PTY;
	pts_driver->subtype = PTY_TYPE_SLAVE;
	pts_driver->init_termios = tty_std_termios;
	pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
	pts_driver->init_termios.c_ispeed = 38400;
	pts_driver->init_termios.c_ospeed = 38400;
	pts_driver->other = ptm_driver;
	tty_set_operations(pts_driver, &pty_unix98_ops);

	if (tty_register_driver(ptm_driver))
		panic("Couldn't register Unix98 ptm driver");
	if (tty_register_driver(pts_driver))
		panic("Couldn't register Unix98 pts driver");

	/* Now create the /dev/ptmx special device */
	tty_default_fops(&ptmx_fops);
	ptmx_fops.open = ptmx_open;

	cdev_init(&ptmx_cdev, &ptmx_fops);
	if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
		panic("Couldn't register /dev/ptmx driver");
	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
}


Contributors
PersonTokensPropCommitsCommitProp
Al Viro12534.63%211.11%


Alan Cox11130.75%422.22%


Linus Torvalds (pre-git)8523.55%738.89%


Jiri Slaby226.09%15.56%


Christoph Hellwig92.49%15.56%


Dan Carpenter61.66%15.56%


Andrew Morton20.55%15.56%


Cong Ding10.28%15.56%


Total361100.00%18100.00%



#else



static inline void unix98_pty_init(void) { }

Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig8100.00%1100.00%


Total8100.00%1100.00%



#endif




static int __init pty_init(void)
{
	legacy_pty_init();
	unix98_pty_init();
	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig1477.78%133.33%


Linus Torvalds (pre-git)422.22%266.67%


Total18100.00%3100.00%




device_initcall(pty_init);

Overall Contributors
PersonTokensPropCommitsCommitProp
Alan Cox100024.60%2114.19%


Linus Torvalds (pre-git)77719.11%3322.30%


Peter Hurley59214.56%2416.22%


Jiri Slaby3568.76%1711.49%


Cyrill V. Gorcunov2516.17%21.35%


Al Viro1944.77%42.70%


Linus Torvalds1694.16%74.73%


Christoph Hellwig1503.69%10.68%


Arnd Bergmann1102.71%32.03%


Eric W. Biedermann1022.51%21.35%


Howard Chu832.04%10.68%


Aleksa Sarai791.94%21.35%


Masatake YAMATO330.81%10.68%


Herton Ronaldo Krzesinski290.71%10.68%


Kay Sievers240.59%10.68%


Andrew Morton190.47%32.03%


Rasmus Villemoes190.47%21.35%


Greg Kroah-Hartman150.37%32.03%


Dan Carpenter120.30%10.68%


Sukadev Bhattiprolu110.27%10.68%


Nicholas Piggin60.15%21.35%


Zou Nan hai60.15%10.68%


Colin Ian King60.15%10.68%


Konstantin Khlebnikov50.12%10.68%


Brian Bloniarz30.07%10.68%


Paul Gortmaker20.05%10.68%


Cong Ding20.05%21.35%


Alexey Dobriyan20.05%10.68%


Adrian Bunk10.02%10.68%


Roel Kluin10.02%10.68%


Daniel Mack10.02%10.68%


Ingo Molnar10.02%10.68%


Josh Triplett10.02%10.68%


Wang YanQing10.02%10.68%


Kees Cook10.02%10.68%


Tejun Heo10.02%10.68%


Total4065100.00%148100.00%


Directory: drivers/tty



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