diff options
Diffstat (limited to 'drivers/tty/pty.c')
| -rw-r--r-- | drivers/tty/pty.c | 777 |
1 files changed, 777 insertions, 0 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c new file mode 100644 index 000000000000..923a48585501 --- /dev/null +++ b/drivers/tty/pty.c @@ -0,0 +1,777 @@ +/* + * linux/drivers/char/pty.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * Added support for a Unix98-style ptmx device. + * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 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 <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.h> +#include <linux/string.h> +#include <linux/major.h> +#include <linux/mm.h> +#include <linux/init.h> +#include <linux/smp_lock.h> +#include <linux/sysctl.h> +#include <linux/device.h> +#include <linux/uaccess.h> +#include <linux/bitops.h> +#include <linux/devpts_fs.h> +#include <linux/slab.h> + +#include <asm/system.h> + +#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_unlock(); + tty_vhangup(tty->link); + tty_lock(); + } +} + +/* + * 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. */ + tty_lock(); + index = devpts_new_index(inode); + tty_unlock(); + if (index < 0) + return index; + + mutex_lock(&tty_mutex); + tty_lock(); + 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 */ + + retval = tty_add_file(tty, filp); + if (retval) + goto out; + + retval = devpts_pty_new(inode, tty->link); + if (retval) + goto out1; + + retval = ptm_driver->ops->open(tty, filp); + if (retval) + goto out2; +out1: + tty_unlock(); + return retval; +out2: + tty_unlock(); + tty_release(inode, filp); + return retval; +out: + devpts_kill_index(inode, index); + tty_unlock(); + return retval; +} + +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); |