v4.19.13 snapshot.
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
new file mode 100644
index 0000000..678406e
--- /dev/null
+++ b/drivers/tty/pty.c
@@ -0,0 +1,958 @@
+// 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);
+ }
+}
+
+/*
+ * 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);
+}
+
+/**
+ * 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;
+ unsigned long flags;
+
+ if (tty->stopped)
+ return 0;
+
+ if (c > 0) {
+ spin_lock_irqsave(&to->port->lock, flags);
+ /* 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);
+ spin_unlock_irqrestore(&to->port->lock, flags);
+ }
+ return c;
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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;
+}
+
+/* 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;
+}
+
+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);
+}
+
+/* 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;
+}
+
+/* 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);
+}
+
+/* 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;
+}
+
+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);
+ }
+}
+
+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;
+}
+
+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);
+}
+
+/**
+ * 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;
+}
+
+/**
+ * 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, EPOLLIN);
+ }
+}
+
+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, EPOLLIN);
+ }
+}
+
+/**
+ * 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;
+}
+
+static void pty_cleanup(struct tty_struct *tty)
+{
+ tty_port_put(tty->port);
+}
+
+/* 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);
+}
+
+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;
+}
+
+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;
+}
+
+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);
+}
+
+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");
+}
+#else
+static inline void legacy_pty_init(void) { }
+#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(flags);
+ 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;
+}
+
+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;
+}
+
+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);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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;
+}
+
+static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ return pty_common_install(driver, tty, false);
+}
+
+/* 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);
+ }
+}
+
+static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
+{
+ seq_printf(m, "tty-index:\t%d\n", tty->index);
+}
+
+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;
+}
+
+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");
+}
+
+#else
+static inline void unix98_pty_init(void) { }
+#endif
+
+static int __init pty_init(void)
+{
+ legacy_pty_init();
+ unix98_pty_init();
+ return 0;
+}
+device_initcall(pty_init);