Commit message: tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)

ioctl(TIOCGETD) retrieves the line discipline id directly from the
ldisc because the line discipline id (c_line) in termios is untrustworthy;
userspace may have set termios via ioctl(TCSETS*) without actually
changing the line discipline via ioctl(TIOCSETD).

However, directly accessing the current ldisc via tty->ldisc is
unsafe; the ldisc ptr dereferenced may be stale if the line discipline
is changing via ioctl(TIOCSETD) or hangup.

Wait for the line discipline reference (just like read() or write())
to retrieve the "current" line discipline id.

Cc: <stable@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CVE: CVE-2016-0723
CWE: CWE-362
Vulnerability description: Race condition in the tty_ioctl function in drivers/tty/tty_io.c in the Linux kernel through 4.4.1 allows local users to obtain sensitive information from kernel memory or cause a denial of service (use-after-free and system crash) by making a TIOCGETD ioctl call during processing of a TIOCSETD ioctl call.

Project: linux
File: tty_io.c

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;

	if (!tty)
		return;
	session = tty->session;

	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);
#endif
}

Project: linux
File: tty_io.c

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

	spin_lock_irqsave(&tty->ctrl_lock, flags);
	/*
	 * The session and fg pgrp references will be non-NULL if
	 * tiocsctty() is stealing the controlling tty
	 */
	put_pid(tty->session);
	put_pid(tty->pgrp);
	tty->pgrp = get_pid(task_pgrp(current));
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	tty->session = get_pid(task_session(current));
	if (current->signal->tty) {
		tty_debug(tty, "current tty %s not NULL!!\n",
			  current->signal->tty->name);
		tty_kref_put(current->signal->tty);
	}
	put_pid(current->signal->tty_old_pgrp);
	current->signal->tty = tty_kref_get(tty);
	current->signal->tty_old_pgrp = NULL;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

void __stop_tty(struct tty_struct *tty)
{
	if (tty->stopped)
		return;
	tty->stopped = 1;
	if (tty->ops->stop)
		tty->ops->stop(tty);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

int __tty_check_change(struct tty_struct *tty, int sig)
{
	unsigned long flags;
	struct pid *pgrp, *tty_pgrp;
	int ret = 0;

	if (current->signal->tty != tty)
		return 0;

	rcu_read_lock();
	pgrp = task_pgrp(current);

	spin_lock_irqsave(&tty->ctrl_lock, flags);
	tty_pgrp = tty->pgrp;
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	if (tty_pgrp && pgrp != tty->pgrp) {
		if (is_ignored(sig)) {
			if (sig == SIGTTIN)
				ret = -EIO;
		} else if (is_current_pgrp_orphaned())
			ret = -EIO;
		else {
			kill_pgrp(pgrp, sig, 1);
			set_thread_flag(TIF_SIGPENDING);
			ret = -ERESTARTSYS;
		}
	}
	rcu_read_unlock();

	if (!tty_pgrp)
		tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig);

	return ret;
}

Project: linux
File: tty_io.c

static int __tty_fasync(int fd, struct file *filp, int on)
{
	struct tty_struct *tty = file_tty(filp);
	struct tty_ldisc *ldisc;
	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;

	ldisc = tty_ldisc_ref(tty);
	if (ldisc) {
		if (ldisc->ops->fasync)
			ldisc->ops->fasync(tty, on);
		tty_ldisc_deref(ldisc);
	}

	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_PID;
		}
		get_pid(pid);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		__f_setown(filp, pid, type, 0);
		put_pid(pid);
		retval = 0;
	}
out:
	return retval;
}

Project: linux
File: tty_io.c

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;
	}

	/* 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);

	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. However we
	 * can't yet guarantee all that.
	 */
	set_bit(TTY_HUPPED, &tty->flags);
	tty_unlock(tty);

	if (f)
		fput(f);
}

Project: linux
File: tty_io.c

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;
	tty_ldisc_init(tty);
	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);
	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;
}

Project: linux
File: tty_io.c

void console_sysfs_notify(void)
{
	if (consdev)
		sysfs_notify(&consdev->kobj, NULL, "active");
}

Project: linux
File: tty_io.c

void deinitialize_tty_struct(struct tty_struct *tty)
{
	tty_ldisc_deinit(tty);
}

Project: linux
File: tty_io.c

static int dev_match_devt(struct device *dev, const void *data)
{
	const dev_t *devt = data;
	return dev->devt == *devt;
}

Project: linux
File: tty_io.c

void disassociate_ctty(int on_exit)
{
	struct tty_struct *tty;

	if (!current->signal->leader)
		return;

	tty = get_current_tty();
	if (tty) {
		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
			tty_vhangup_session(tty);
		} else {
			struct pid *tty_pgrp = tty_get_pgrp(tty);
			if (tty_pgrp) {
				kill_pgrp(tty_pgrp, SIGHUP, on_exit);
				if (!on_exit)
					kill_pgrp(tty_pgrp, SIGCONT, on_exit);
				put_pid(tty_pgrp);
			}
		}
		tty_kref_put(tty);

	} else if (on_exit) {
		struct pid *old_pgrp;
		spin_lock_irq(&current->sighand->siglock);
		old_pgrp = current->signal->tty_old_pgrp;
		current->signal->tty_old_pgrp = NULL;
		spin_unlock_irq(&current->sighand->siglock);
		if (old_pgrp) {
			kill_pgrp(old_pgrp, SIGHUP, on_exit);
			kill_pgrp(old_pgrp, SIGCONT, on_exit);
			put_pid(old_pgrp);
		}
		return;
	}

	spin_lock_irq(&current->sighand->siglock);
	put_pid(current->signal->tty_old_pgrp);
	current->signal->tty_old_pgrp = NULL;

	tty = tty_kref_get(current->signal->tty);
	if (tty) {
		unsigned long flags;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = NULL;
		tty->pgrp = NULL;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		tty_kref_put(tty);
	} else
		tty_debug_hangup(tty, "no current tty\n");

	spin_unlock_irq(&current->sighand->siglock);
	/* Now clear signal->tty under the lock */
	read_lock(&tasklist_lock);
	session_clear_tty(task_session(current));
	read_unlock(&tasklist_lock);
}

Project: linux
File: tty_io.c

void do_SAK(struct tty_struct *tty)
{
	if (!tty)
		return;
	schedule_work(&tty->SAK_work);
}

Project: linux
File: tty_io.c

static void do_SAK_work(struct work_struct *work)
{
	struct tty_struct *tty =
		container_of(work, struct tty_struct, SAK_work);
	__do_SAK(tty);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static inline struct tty_struct *file_tty(struct file *file)
{
	return ((struct tty_file_private *)file->private_data)->tty;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

void free_tty_struct(struct tty_struct *tty)
{
	if (!tty)
		return;
	put_device(tty->dev);
	kfree(tty->write_buf);
	tty->magic = 0xDEADDEAD;
	kfree(tty);
}

Project: linux
File: tty_io.c

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

	spin_lock_irqsave(&current->sighand->siglock, flags);
	tty = tty_kref_get(current->signal->tty);
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
	return tty;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static long hung_up_tty_compat_ioctl(struct file *file,
				     unsigned int cmd, unsigned long arg)
{
	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}

Project: linux
File: tty_io.c

static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
		unsigned long arg)
{
	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}

Project: linux
File: tty_io.c

static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
				size_t count, loff_t *ppos)
{
	return 0;
}

Project: linux
File: tty_io.c

static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
				 size_t count, loff_t *ppos)
{
	return -EIO;
}

Project: linux
File: tty_io.c

void no_tty(void)
{
	/* FIXME: Review locking here. The tty_lock never covered any race
	   between a new association and proc_clear_tty but possible we need
	   to protect against this anyway */
	struct task_struct *tsk = current;
	disassociate_ctty(0);
	proc_clear_tty(tsk);
}

Project: linux
File: tty_io.c

void proc_clear_tty(struct task_struct *p)
{
	unsigned long flags;
	struct tty_struct *tty;
	spin_lock_irqsave(&p->sighand->siglock, flags);
	tty = p->signal->tty;
	p->signal->tty = NULL;
	spin_unlock_irqrestore(&p->sighand->siglock, flags);
	tty_kref_put(tty);
}

Project: linux
File: tty_io.c

static void proc_set_tty(struct tty_struct *tty)
{
	spin_lock_irq(&current->sighand->siglock);
	__proc_set_tty(tty);
	spin_unlock_irq(&current->sighand->siglock);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

void put_tty_driver(struct tty_driver *d)
{
	tty_driver_kref_put(d);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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_free_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);

	tty_kref_put(tty->link);
	tty_kref_put(tty);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static void session_clear_tty(struct pid *session)
{
	struct task_struct *p;
	do_each_pid_task(session, PIDTYPE_SID, p) {
		proc_clear_tty(p);
	} while_each_pid_task(session, PIDTYPE_SID, p);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
	/*
	 * (tty == real_tty) is a cheap way of
	 * testing if the tty is NOT a master pty.
	*/
	if (tty == real_tty && current->signal->tty != real_tty)
		return -ENOTTY;
	if (!real_tty->session)
		return -ENOTTY;
	return put_user(pid_vnr(real_tty->session), p);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static int tiocsctty(struct tty_struct *tty, struct file *file, int arg)
{
	int ret = 0;

	tty_lock(tty);
	read_lock(&tasklist_lock);

	if (current->signal->leader && (task_session(current) == tty->session))
		goto unlock;

	/*
	 * The process must be a session leader and
	 * not have a controlling tty already.
	 */
	if (!current->signal->leader || current->signal->tty) {
		ret = -EPERM;
		goto unlock;
	}

	if (tty->session) {
		/*
		 * This tty is already the controlling
		 * tty for another session group!
		 */
		if (arg == 1 && capable(CAP_SYS_ADMIN)) {
			/*
			 * Steal it away
			 */
			session_clear_tty(tty->session);
		} else {
			ret = -EPERM;
			goto unlock;
		}
	}

	/* See the comment in tty_open(). */
	if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) {
		ret = -EPERM;
		goto unlock;
	}

	proc_set_tty(tty);
unlock:
	read_unlock(&tasklist_lock);
	tty_unlock(tty);
	return ret;
}

Project: linux
File: tty_io.c

static int tiocsetd(struct tty_struct *tty, int __user *p)
{
	int ldisc;
	int ret;

	if (get_user(ldisc, p))
		return -EFAULT;

	ret = tty_set_ldisc(tty, ldisc);

 	return ret;
 }

Project: linux
File: tty_io.c

static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
	struct pid *pgrp;
	pid_t pgrp_nr;
	int retval = tty_check_change(real_tty);

	if (retval == -EIO)
		return -ENOTTY;
	if (retval)
		return retval;
	if (!current->signal->tty ||
	    (current->signal->tty != real_tty) ||
	    (real_tty->session != task_session(current)))
		return -ENOTTY;
	if (get_user(pgrp_nr, p))
		return -EFAULT;
	if (pgrp_nr < 0)
		return -EINVAL;
	rcu_read_lock();
	pgrp = find_vpid(pgrp_nr);
	retval = -ESRCH;
	if (!pgrp)
		goto out_unlock;
	retval = -EPERM;
	if (session_of_pgrp(pgrp) != task_session(current))
		goto out_unlock;
	retval = 0;
	spin_lock_irq(&tty->ctrl_lock);
	put_pid(real_tty->pgrp);
	real_tty->pgrp = get_pid(pgrp);
	spin_unlock_irq(&tty->ctrl_lock);
out_unlock:
	rcu_read_unlock();
	return retval;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

int tty_check_change(struct tty_struct *tty)
{
	return __tty_check_change(tty, SIGTTOU);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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->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;
}

Project: linux
File: tty_io.c

void tty_default_fops(struct file_operations *fops)
{
	*fops = tty_fops;
}

Project: linux
File: tty_io.c

static void tty_device_create_release(struct device *dev)
{
	dev_dbg(dev, "releasing...\n");
	kfree(dev);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

dev_t tty_devnum(struct tty_struct *tty)
{
	return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
		struct inode *inode, int idx)
{
	struct tty_struct *tty;

	if (driver->ops->lookup)
		tty = driver->ops->lookup(driver, inode, idx);
	else
		tty = driver->ttys[idx];

	if (!IS_ERR(tty))
		tty_kref_get(tty);
	return tty;
}

Project: linux
File: tty_io.c

const char *tty_driver_name(const struct tty_struct *tty)
{
	if (!tty || !tty->driver)
		return "";
	return tty->driver->name;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static int tty_fasync(int fd, struct file *filp, int on)
{
	struct tty_struct *tty = file_tty(filp);
	int retval;

	tty_lock(tty);
	retval = __tty_fasync(fd, filp, on);
	tty_unlock(tty);

	return retval;
}

Project: linux
File: tty_io.c

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 (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;
}

Project: linux
File: tty_io.c

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);
	}
}

Project: linux
File: tty_io.c

void tty_free_file(struct file *file)
{
	struct tty_file_private *priv = file->private_data;

	file->private_data = NULL;
	kfree(priv);
}

Project: linux
File: tty_io.c

void tty_free_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;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

struct pid *tty_get_pgrp(struct tty_struct *tty)
{
	unsigned long flags;
	struct pid *pgrp;

	spin_lock_irqsave(&tty->ctrl_lock, flags);
	pgrp = get_pid(tty->pgrp);
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	return pgrp;
}

Project: linux
File: tty_io.c

void tty_hangup(struct tty_struct *tty)
{
	tty_debug_hangup(tty, "hangup\n");
	schedule_work(&tty->hangup_work);
}

Project: linux
File: tty_io.c

int tty_hung_up_p(struct file *filp)
{
	return (filp->f_op == &hung_up_tty_fops);
}

Project: linux
File: tty_io.c

int __init tty_init(void)
{
	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;
}

Project: linux
File: tty_io.c

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
	 * and locked 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_deinit_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);

	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;
	/* Return the tty locked so that it cannot vanish under the caller */
	return tty;

err_deinit_tty:
	tty_unlock(tty);
	deinitialize_tty_struct(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_unlock(tty);
	tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
			     retval, idx);
	release_tty(tty, idx);
	return ERR_PTR(retval);
}

Project: linux
File: tty_io.c

int 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;
		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);
	return 0;
}

Project: linux
File: tty_io.c

void tty_kref_put(struct tty_struct *tty)
{
	if (tty)
		kref_put(&tty->kref, queue_release_one_tty);
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
		int *noctty, 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;
		*noctty = 1;
		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) {
				/* Don't let /dev/console block */
				filp->f_flags |= O_NONBLOCK;
				*noctty = 1;
				break;
			}
		}
		return ERR_PTR(-ENODEV);
	}
	default:
		driver = get_tty_driver(device, index);
		if (!driver)
			return ERR_PTR(-ENODEV);
		break;
	}
	return driver;
}

Project: linux
File: tty_io.c

const char *tty_name(const struct tty_struct *tty)
{
	if (!tty) /* Hmm.  NULL pointer.  That's fun. */
		return "NULL tty";
	return tty->name;
}

Project: linux
File: tty_io.c

static int tty_open(struct inode *inode, struct file *filp)
{
	struct tty_struct *tty;
	int noctty, retval;
	struct tty_driver *driver = NULL;
	int index;
	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;

	noctty = filp->f_flags & O_NOCTTY;
	index  = -1;
	retval = 0;

	tty = tty_open_current_tty(device, filp);
	if (!tty) {
		mutex_lock(&tty_mutex);
		driver = tty_lookup_driver(device, filp, &noctty, &index);
		if (IS_ERR(driver)) {
			retval = PTR_ERR(driver);
			goto err_unlock;
		}

		/* check whether we're reopening an existing tty */
		tty = tty_driver_lookup_tty(driver, inode, index);
		if (IS_ERR(tty)) {
			retval = PTR_ERR(tty);
			goto err_unlock;
		}

		if (tty) {
			mutex_unlock(&tty_mutex);
			retval = tty_lock_interruptible(tty);
			if (retval) {
				if (retval == -EINTR)
					retval = -ERESTARTSYS;
				goto err_unref;
			}
			/* safe to drop the kref from tty_driver_lookup_tty() */
			tty_kref_put(tty);
			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);
		}

		tty_driver_kref_put(driver);
	}

	if (IS_ERR(tty)) {
		retval = PTR_ERR(tty);
		if (retval != -EAGAIN || signal_pending(current))
			goto err_file;
		tty_free_file(filp);
		schedule();
		goto retry_open;
	}

	tty_add_file(tty, filp);

	check_tty_count(tty, __func__);
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_MASTER)
		noctty = 1;

	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);


	read_lock(&tasklist_lock);
	spin_lock_irq(&current->sighand->siglock);
	if (!noctty &&
	    current->signal->leader &&
	    !current->signal->tty &&
	    tty->session == NULL) {
		/*
		 * Don't let a process that only has write access to the tty
		 * obtain the privileges associated with having a tty as
		 * controlling terminal (being able to reopen it with full
		 * access through /dev/tty, being able to perform pushback).
		 * Many distributions set the group of all ttys to "tty" and
		 * grant write-only access to all terminals for setgid tty
		 * binaries, which should not imply full privileges on all ttys.
		 *
		 * This could theoretically break old code that performs open()
		 * on a write-only file descriptor. In that case, it might be
		 * necessary to also permit this if
		 * inode_permission(inode, MAY_READ) == 0.
		 */
		if (filp->f_mode & FMODE_READ)
			__proc_set_tty(tty);
	}
	spin_unlock_irq(&current->sighand->siglock);
	read_unlock(&tasklist_lock);
	tty_unlock(tty);
	return 0;
err_unlock:
	mutex_unlock(&tty_mutex);
err_unref:
	/* after locks to avoid deadlock */
	if (!IS_ERR_OR_NULL(driver))
		tty_driver_kref_put(driver);
err_file:
	tty_free_file(filp);
	return retval;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static unsigned int tty_poll(struct file *filp, poll_table *wait)
{
	struct tty_struct *tty = file_tty(filp);
	struct tty_ldisc *ld;
	int ret = 0;

	if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
		return 0;

	ld = tty_ldisc_ref_wait(tty);
	if (ld->ops->poll)
		ret = ld->ops->poll(tty, filp, wait);
	tty_ldisc_deref(ld);
	return ret;
}

Project: linux
File: tty_io.c

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);
}

Project: linux
File: tty_io.c

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 || (test_bit(TTY_IO_ERROR, &tty->flags)))
		return -EIO;

	/* We want to wait for the line discipline to sort out in this
	   situation */
	ld = tty_ldisc_ref_wait(tty);
	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;
}

Project: linux
File: tty_io.c

struct device *tty_register_device(struct tty_driver *driver, unsigned index,
				   struct device *device)
{
	return tty_register_device_attr(driver, index, device, NULL, NULL);
}

Project: linux
File: tty_io.c

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 device *dev = NULL;
	int retval = -ENODEV;
	bool cdev = false;

	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);

	if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
		retval = tty_cdev_add(driver, devt, index, 1);
		if (retval)
			goto error;
		cdev = true;
	}

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev) {
		retval = -ENOMEM;
		goto error;
	}

	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);

	retval = device_register(dev);
	if (retval)
		goto error;

	return dev;

error:
	put_device(dev);
	if (cdev) {
		cdev_del(driver->cdevs[index]);
		driver->cdevs[index] = NULL;
	}
	return ERR_PTR(retval);
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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, POLLIN);
				do_sleep++;
			}
			if (waitqueue_active(&tty->write_wait)) {
				wake_up_poll(&tty->write_wait, POLLOUT);
				do_sleep++;
			}
		}
		if (o_tty && o_tty->count <= 1) {
			if (waitqueue_active(&o_tty->read_wait)) {
				wake_up_poll(&o_tty->read_wait, POLLIN);
				do_sleep++;
			}
			if (waitqueue_active(&o_tty->write_wait)) {
				wake_up_poll(&o_tty->write_wait, POLLOUT);
				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");
	/*
	 * 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);

	return 0;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static int tty_reopen(struct tty_struct *tty)
{
	struct tty_driver *driver = tty->driver;

	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;

	tty->count++;

	WARN_ON(!tty->ldisc);

	return 0;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

void tty_set_operations(struct tty_driver *driver,
			const struct tty_operations *op)
{
	driver->ops = op;
};

Project: linux
File: tty_io.c

static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
{
	struct task_struct *p;
	int refs = 0;
	struct pid *tty_pgrp = NULL;

	read_lock(&tasklist_lock);
	if (tty->session) {
		do_each_pid_task(tty->session, PIDTYPE_SID, p) {
			spin_lock_irq(&p->sighand->siglock);
			if (p->signal->tty == tty) {
				p->signal->tty = NULL;
				/* We defer the dereferences outside fo
				   the tasklist lock */
				refs++;
			}
			if (!p->signal->leader) {
				spin_unlock_irq(&p->sighand->siglock);
				continue;
			}
			__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
			__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
			put_pid(p->signal->tty_old_pgrp);  /* A noop */
			spin_lock(&tty->ctrl_lock);
			tty_pgrp = get_pid(tty->pgrp);
			if (tty->pgrp)
				p->signal->tty_old_pgrp = get_pid(tty->pgrp);
			spin_unlock(&tty->ctrl_lock);
			spin_unlock_irq(&p->sighand->siglock);
		} while_each_pid_task(tty->session, PIDTYPE_SID, p);
	}
	read_unlock(&tasklist_lock);

	if (tty_pgrp) {
		if (exit_session)
			kill_pgrp(tty_pgrp, SIGHUP, exit_session);
		put_pid(tty_pgrp);
	}

	return refs;
}

Project: linux
File: tty_io.c

int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
{
	int ret = tty_init_termios(tty);
	if (ret)
		return ret;

	tty_driver_kref_get(driver);
	tty->count++;
	driver->ttys[tty->index] = tty;
	return 0;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static int tty_tiocmget(struct tty_struct *tty, int __user *p)
{
	int retval = -EINVAL;

	if (tty->ops->tiocmget) {
		retval = tty->ops->tiocmget(tty);

		if (retval >= 0)
			retval = put_user(retval, p);
	}
	return retval;
}

Project: linux
File: tty_io.c

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 -EINVAL;

	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);
}

Project: linux
File: tty_io.c

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;
	}
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static void tty_update_time(struct timespec *time)
{
	unsigned long sec = get_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;
}

Project: linux
File: tty_io.c

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, POLLOUT);
}

Project: linux
File: tty_io.c

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_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
				__func__, get_task_comm(comm, current), flags);
}

Project: linux
File: tty_io.c

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 ||
		(test_bit(TTY_IO_ERROR, &tty->flags)))
			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->ops->write)
		ret = -EIO;
	else
		ret = do_tty_write(ld->ops->write, tty, file, buf, count);
	tty_ldisc_deref(ld);
	return ret;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

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;
}

Project: linux
File: tty_io.c

static void tty_write_unlock(struct tty_struct *tty)
{
	mutex_unlock(&tty->atomic_write_lock);
	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
}