/* * linux/drivers/char/pty.c * * Copyright (C) 1991, 1992 Linus Torvalds * * Added support for a Unix98-style ptmx device. * -- C. Scott Ananian , 14-Jan-1998 * * When reading this code see also fs/devpts. In particular note that the * driver_data field is used by the devpts side as a binding to the devpts * inode. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_UNIX98_PTYS static struct tty_driver *ptm_driver; static struct tty_driver *pts_driver; #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->count > 2) return; } wake_up_interruptible(&tty->read_wait); wake_up_interruptible(&tty->write_wait); tty->packet = 0; if (!tty->link) return; tty->link->packet = 0; 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) devpts_pty_kill(tty->link); #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_space - report space left for writing * @to: tty we are writing into * * The tty buffers allow 64K but we sneak a peak and clip at 8K this * allows a lot of overspill room for echo and other fun messes to * be handled properly */ static int pty_space(struct tty_struct *to) { int n = 8192 - to->buf.memory_used; if (n < 0) return 0; return n; } /** * pty_write - write to a pty * @tty: the tty we write from * @buf: kernel buffer of data * @count: bytes to write * * Our "hardware" write method. Data is coming from the ldisc which * may be in a non sleeping state. We simply throw this at the other * end of the link as if we were an IRQ handler receiving stuff for * the other side of the pty/tty pair. */ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) { struct tty_struct *to = tty->link; if (tty->stopped) return 0; if (c > 0) { /* Stuff the data into the input queue of the other end */ c = tty_insert_flip_string(to, buf, c); /* And shovel */ if (c) { tty_flip_buffer_push(to); tty_wakeup(tty); } } 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 pty_space(tty->link); } /** * 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; } /* Send a signal to the slave */ static int pty_signal(struct tty_struct *tty, int sig) { unsigned long flags; struct pid *pgrp; if (tty->link) { spin_lock_irqsave(&tty->link->ctrl_lock, flags); pgrp = get_pid(tty->link->pgrp); spin_unlock_irqrestore(&tty->link->ctrl_lock, flags); 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; unsigned long flags; if (!to) return; /* tty_buffer_flush(to); FIXME */ if (to->packet) { spin_lock_irqsave(&tty->ctrl_lock, flags); tty->ctrl_status |= TIOCPKT_FLUSHWRITE; wake_up_interruptible(&to->read_wait); spin_unlock_irqrestore(&tty->ctrl_lock, flags); } } static int pty_open(struct tty_struct *tty, struct file *filp) { int retval = -ENODEV; if (!tty || !tty->link) goto out; retval = -EIO; if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) goto out; if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) goto out; if (tty->link->count != 1) goto out; clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); set_bit(TTY_THROTTLED, &tty->flags); retval = 0; out: return retval; } static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios) { 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 */ int pty_resize(struct tty_struct *tty, struct winsize *ws) { struct pid *pgrp, *rpgrp; unsigned long flags; struct tty_struct *pty = tty->link; /* For a PTY we need to lock the tty side */ mutex_lock(&tty->termios_mutex); if (!memcmp(ws, &tty->winsize, sizeof(*ws))) goto done; /* Get the PID values and reference them so we can avoid holding the tty ctrl lock while sending signals. We need to lock these individually however. */ spin_lock_irqsave(&tty->ctrl_lock, flags); pgrp = get_pid(tty->pgrp); spin_unlock_irqrestore(&tty->ctrl_lock, flags); spin_lock_irqsave(&pty->ctrl_lock, flags); rpgrp = get_pid(pty->pgrp); spin_unlock_irqrestore(&pty->ctrl_lock, flags); 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->termios_mutex); return 0; } /* Traditional BSD devices */ #ifdef CONFIG_LEGACY_PTYS static int pty_install(struct tty_driver *driver, struct tty_struct *tty) { struct tty_struct *o_tty; int idx = tty->index; int retval; o_tty = alloc_tty_struct(); if (!o_tty) return -ENOMEM; if (!try_module_get(driver->other->owner)) { /* This cannot in fact currently happen */ free_tty_struct(o_tty); return -ENOMEM; } initialize_tty_struct(o_tty, driver->other, idx); /* We always use new tty termios data so we can do this the easy way .. */ retval = tty_init_termios(tty); if (retval) goto free_mem_out; retval = tty_init_termios(o_tty); if (retval) { tty_free_termios(tty); goto free_mem_out; } /* * Everything allocated ... set up the o_tty structure. */ driver->other->ttys[idx] = o_tty; tty_driver_kref_get(driver->other); if (driver->subtype == PTY_TYPE_MASTER) o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; tty_driver_kref_get(driver); tty->count++; driver->ttys[idx] = tty; return 0; free_mem_out: module_put(o_tty->driver->owner); free_tty_struct(o_tty); return -ENOMEM; } static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file, 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 TIOCSIG: /* Send signal to other side of pty */ return pty_signal(tty, (int) arg); } return -ENOIOCTLCMD; } static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 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, .set_termios = pty_set_termios, .ioctl = pty_bsd_ioctl, .resize = pty_resize }; 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, .resize = pty_resize }; static void __init legacy_pty_init(void) { struct tty_driver *pty_driver, *pty_slave_driver; if (legacy_count <= 0) return; pty_driver = alloc_tty_driver(legacy_count); if (!pty_driver) panic("Couldn't allocate pty driver"); pty_slave_driver = alloc_tty_driver(legacy_count); if (!pty_slave_driver) panic("Couldn't allocate pty slave driver"); pty_driver->owner = THIS_MODULE; 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; pty_driver->other = pty_slave_driver; tty_set_operations(pty_driver, &master_pty_ops_bsd); pty_slave_driver->owner = THIS_MODULE; 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; 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 /* * sysctl support for setting limits on the number of Unix98 ptys allocated. * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. */ int pty_limit = NR_UNIX98_PTY_DEFAULT; static int pty_limit_min; static int pty_limit_max = NR_UNIX98_PTY_MAX; static int pty_count; static struct cdev ptmx_cdev; static struct ctl_table pty_table[] = { { .procname = "max", .maxlen = sizeof(int), .mode = 0644, .data = &pty_limit, .proc_handler = proc_dointvec_minmax, .extra1 = &pty_limit_min, .extra2 = &pty_limit_max, }, { .procname = "nr", .maxlen = sizeof(int), .mode = 0444, .data = &pty_count, .proc_handler = proc_dointvec, }, {} }; static struct ctl_table pty_kern_table[] = { { .procname = "pty", .mode = 0555, .child = pty_table, }, {} }; static struct ctl_table pty_root_table[] = { { .procname = "kernel", .mode = 0555, .child = pty_kern_table, }, {} }; static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file, 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 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; } /** * 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 inode *ptm_inode, int idx) { struct tty_struct *tty = devpts_get_tty(ptm_inode, idx); if (tty) tty = tty->link; return tty; } /** * 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. */ static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, struct inode *pts_inode, int idx) { struct tty_struct *tty = devpts_get_tty(pts_inode, idx); /* Master must be open before slave */ if (!tty) return ERR_PTR(-EIO); return tty; } static void pty_unix98_shutdown(struct tty_struct *tty) { /* We have our own method as we don't use the tty index */ kfree(tty->termios); } /* We have no need to install and remove our tty objects as devpts does all the work for us */ static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) { struct tty_struct *o_tty; int idx = tty->index; o_tty = alloc_tty_struct(); if (!o_tty) return -ENOMEM; if (!try_module_get(driver->other->owner)) { /* This cannot in fact currently happen */ free_tty_struct(o_tty); return -ENOMEM; } initialize_tty_struct(o_tty, driver->other, idx); tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL); if (tty->termios == NULL) goto free_mem_out; *tty->termios = driver->init_termios; tty->termios_locked = tty->termios + 1; o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL); if (o_tty->termios == NULL) goto free_mem_out; *o_tty->termios = driver->other->init_termios; o_tty->termios_locked = o_tty->termios + 1; tty_driver_kref_get(driver->other); if (driver->subtype == PTY_TYPE_MASTER) o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; /* * All structures have been allocated, so now we install them. * Failures after this point use release_tty to clean up, so * there's no need to null out the local pointers. */ tty_driver_kref_get(driver); tty->count++; pty_count++; return 0; free_mem_out: kfree(o_tty->termios); module_put(o_tty->driver->owner); free_tty_struct(o_tty); kfree(tty->termios); return -ENOMEM; } static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) { pty_count--; } 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, .set_termios = pty_set_termios, .ioctl = pty_unix98_ioctl, .shutdown = pty_unix98_shutdown, .resize = pty_resize }; 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, .shutdown = pty_unix98_shutdown }; /** * 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 tty_struct *tty; int retval; int index; nonseekable_open(inode, filp); /* find a device that is not in use. */ index = devpts_new_index(inode); if (index < 0) return index; mutex_lock(&tty_mutex); tty = tty_init_dev(ptm_driver, index, 1); mutex_unlock(&tty_mutex); if (IS_ERR(tty)) { retval = PTR_ERR(tty); goto out; } set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ filp->private_data = tty; file_move(filp, &tty->tty_files); retval = devpts_pty_new(inode, tty->link); if (retval) goto out1; retval = ptm_driver->ops->open(tty, filp); if (!retval) return 0; out1: tty_release(inode, filp); return retval; out: devpts_kill_index(inode, index); return retval; } static int ptmx_open(struct inode *inode, struct file *filp) { int ret; tty_lock(); ret = __ptmx_open(inode, filp); tty_unlock(); return ret; } static struct file_operations ptmx_fops; static void __init unix98_pty_init(void) { ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); if (!ptm_driver) panic("Couldn't allocate Unix98 ptm driver"); pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); if (!pts_driver) panic("Couldn't allocate Unix98 pts driver"); ptm_driver->owner = THIS_MODULE; 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; ptm_driver->other = pts_driver; tty_set_operations(ptm_driver, &ptm_unix98_ops); pts_driver->owner = THIS_MODULE; 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; 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"); register_sysctl_table(pty_root_table); /* 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\n"); 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; } module_init(pty_init);