diff options
Diffstat (limited to 'drivers/tty/pty.c')
| -rw-r--r-- | drivers/tty/pty.c | 947 |
1 files changed, 947 insertions, 0 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c new file mode 100644 index 000000000..07394fdaf --- /dev/null +++ b/drivers/tty/pty.c @@ -0,0 +1,947 @@ +// 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> +#include <linux/compat.h> +#include "tty.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) +{ + 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->ctrl.packet = false; + 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 + * @c: 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->flow.stopped || !c) + return 0; + + return tty_insert_flip_string_and_push_buffer(to->port, buf, 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 unsigned int pty_write_room(struct tty_struct *tty) +{ + if (tty->flow.stopped) + return 0; + return tty_buffer_space_avail(tty->link->port); +} + +/* 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->ctrl.packet) { + tty->link->ctrl.pktstatus = 0; + smp_mb(); + tty->ctrl.packet = true; + } + } else + tty->ctrl.packet = false; + 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->ctrl.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->ctrl.packet) { + spin_lock_irq(&tty->ctrl.lock); + tty->ctrl.pktstatus |= 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, + const struct ktermios *old_termios) +{ + /* See if packet mode change of state. */ + if (tty->link && tty->link->ctrl.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.pktstatus &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); + if (new_flow) + tty->ctrl.pktstatus |= TIOCPKT_DOSTOP; + else + tty->ctrl.pktstatus |= TIOCPKT_NOSTOP; + } + if (extproc) + tty->ctrl.pktstatus |= 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_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->ctrl.packet) { + spin_lock_irqsave(&tty->ctrl.lock, flags); + tty->ctrl.pktstatus &= ~TIOCPKT_STOP; + tty->ctrl.pktstatus |= 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->ctrl.packet) { + spin_lock_irqsave(&tty->ctrl.lock, flags); + tty->ctrl.pktstatus &= ~TIOCPKT_START; + tty->ctrl.pktstatus |= 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; +} + +#ifdef CONFIG_COMPAT +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, (unsigned long)compat_ptr(arg)); +} +#else +#define pty_bsd_compat_ioctl NULL +#endif + +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, + .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, + .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; + 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; +} + +#ifdef CONFIG_COMPAT +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, + cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg)); +} +#else +#define pty_unix98_compat_ioctl NULL +#endif + +/** + * ptm_unix98_lookup - find a pty master + * @driver: ptm driver + * @file: unused + * @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 + * @file: file pointer to tty + * @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, + .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, + .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); |