diff options
Diffstat (limited to 'drivers/tty/tty_io.c')
| -rw-r--r-- | drivers/tty/tty_io.c | 3372 |
1 files changed, 3372 insertions, 0 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c new file mode 100644 index 000000000..b6f42d0ee --- /dev/null +++ b/drivers/tty/tty_io.c @@ -0,0 +1,3372 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles + * or rs-channels. It also implements echoing, cooked mode etc. + * + * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0. + * + * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the + * tty_struct and tty_queue structures. Previously there was an array + * of 256 tty_struct's which was statically allocated, and the + * tty_queue structures were allocated at boot time. Both are now + * dynamically allocated only when the tty is open. + * + * Also restructured routines so that there is more of a separation + * between the high-level tty routines (tty_io.c and tty_ioctl.c) and + * the low-level tty routines (serial.c, pty.c, console.c). This + * makes for cleaner and more compact code. -TYT, 9/17/92 + * + * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines + * which can be dynamically activated and de-activated by the line + * discipline handling modules (like SLIP). + * + * NOTE: pay no attention to the line discipline code (yet); its + * interface is still subject to change in this version... + * -- TYT, 1/31/92 + * + * Added functionality to the OPOST tty handling. No delays, but all + * other bits should be there. + * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993. + * + * Rewrote canonical mode and added more termios flags. + * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94 + * + * Reorganized FASYNC support so mouse code can share it. + * -- ctm@ardi.com, 9Sep95 + * + * New TIOCLINUX variants added. + * -- mj@k332.feld.cvut.cz, 19-Nov-95 + * + * Restrict vt switching via ioctl() + * -- grif@cs.ucr.edu, 5-Dec-95 + * + * Move console and virtual terminal code to more appropriate files, + * implement CONFIG_VT and generalize console device interface. + * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97 + * + * Rewrote tty_init_dev and tty_release_dev to eliminate races. + * -- Bill Hawes <whawes@star.net>, June 97 + * + * Added devfs support. + * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998 + * + * Added support for a Unix98-style ptmx device. + * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 + * + * Reduced memory usage for older ARM systems + * -- Russell King <rmk@arm.linux.org.uk> + * + * Move do_SAK() into process context. Less stack use in devfs functions. + * alloc_tty_struct() always uses kmalloc() + * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01 + */ + +#include <linux/types.h> +#include <linux/major.h> +#include <linux/errno.h> +#include <linux/signal.h> +#include <linux/fcntl.h> +#include <linux/sched/signal.h> +#include <linux/sched/task.h> +#include <linux/interrupt.h> +#include <linux/tty.h> +#include <linux/tty_driver.h> +#include <linux/tty_flip.h> +#include <linux/devpts_fs.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/console.h> +#include <linux/timer.h> +#include <linux/ctype.h> +#include <linux/kd.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <linux/poll.h> +#include <linux/proc_fs.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/wait.h> +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/seq_file.h> +#include <linux/serial.h> +#include <linux/ratelimit.h> + +#include <linux/uaccess.h> + +#include <linux/kbd_kern.h> +#include <linux/vt_kern.h> +#include <linux/selection.h> + +#include <linux/kmod.h> +#include <linux/nsproxy.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 + +#define TTY_PARANOIA_CHECK 1 +#define CHECK_TTY_COUNT 1 + +struct ktermios tty_std_termios = { /* for the benefit of tty drivers */ + .c_iflag = ICRNL | IXON, + .c_oflag = OPOST | ONLCR, + .c_cflag = B38400 | CS8 | CREAD | HUPCL, + .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | + ECHOCTL | ECHOKE | IEXTEN, + .c_cc = INIT_C_CC, + .c_ispeed = 38400, + .c_ospeed = 38400, + /* .c_line = N_TTY, */ +}; + +EXPORT_SYMBOL(tty_std_termios); + +/* This list gets poked at by procfs and various bits of boot up code. This + could do with some rationalisation such as pulling the tty proc function + into this file */ + +LIST_HEAD(tty_drivers); /* linked list of tty drivers */ + +/* Mutex to protect creating and releasing a tty */ +DEFINE_MUTEX(tty_mutex); + +static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); +static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); +ssize_t redirected_tty_write(struct file *, const char __user *, + size_t, loff_t *); +static __poll_t tty_poll(struct file *, poll_table *); +static int tty_open(struct inode *, struct file *); +long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg); +#ifdef CONFIG_COMPAT +static long tty_compat_ioctl(struct file *file, unsigned int cmd, + unsigned long arg); +#else +#define tty_compat_ioctl NULL +#endif +static int __tty_fasync(int fd, struct file *filp, int on); +static int tty_fasync(int fd, struct file *filp, int on); +static void release_tty(struct tty_struct *tty, int idx); + +/** + * free_tty_struct - free a disused tty + * @tty: tty struct to free + * + * Free the write buffers, tty queue and tty memory itself. + * + * Locking: none. Must be called after tty is definitely unused + */ + +static void free_tty_struct(struct tty_struct *tty) +{ + tty_ldisc_deinit(tty); + put_device(tty->dev); + kfree(tty->write_buf); + tty->magic = 0xDEADDEAD; + kfree(tty); +} + +static inline struct tty_struct *file_tty(struct file *file) +{ + return ((struct tty_file_private *)file->private_data)->tty; +} + +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; +} + +/* Associate a new file with the tty structure */ +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); +} + +/** + * tty_free_file - free file->private_data + * + * This shall be used only for fail path handling when tty_add_file was not + * called yet. + */ +void tty_free_file(struct file *file) +{ + struct tty_file_private *priv = file->private_data; + + file->private_data = NULL; + kfree(priv); +} + +/* Delete file from its tty */ +static void tty_del_file(struct file *file) +{ + struct tty_file_private *priv = file->private_data; + struct tty_struct *tty = priv->tty; + + spin_lock(&tty->files_lock); + list_del(&priv->list); + spin_unlock(&tty->files_lock); + tty_free_file(file); +} + +/** + * tty_name - return tty naming + * @tty: tty structure + * + * Convert a tty structure into a name. The name reflects the kernel + * naming policy and if udev is in use may not reflect user space + * + * Locking: none + */ + +const char *tty_name(const struct tty_struct *tty) +{ + if (!tty) /* Hmm. NULL pointer. That's fun. */ + return "NULL tty"; + return tty->name; +} + +EXPORT_SYMBOL(tty_name); + +const char *tty_driver_name(const struct tty_struct *tty) +{ + if (!tty || !tty->driver) + return ""; + return tty->driver->name; +} + +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; +} + +/* Caller must hold tty_lock */ +static int check_tty_count(struct tty_struct *tty, const char *routine) +{ +#ifdef CHECK_TTY_COUNT + struct list_head *p; + int count = 0, kopen_count = 0; + + spin_lock(&tty->files_lock); + list_for_each(p, &tty->tty_files) { + count++; + } + spin_unlock(&tty->files_lock); + if (tty->driver->type == TTY_DRIVER_TYPE_PTY && + tty->driver->subtype == PTY_TYPE_SLAVE && + tty->link && tty->link->count) + count++; + if (tty_port_kopened(tty->port)) + kopen_count++; + if (tty->count != (count + kopen_count)) { + tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n", + routine, tty->count, count, kopen_count); + return (count + kopen_count); + } +#endif + return 0; +} + +/** + * get_tty_driver - find device of a tty + * @dev_t: device identifier + * @index: returns the index of the tty + * + * This routine returns a tty driver structure, given a device number + * and also passes back the index number. + * + * Locking: caller must hold tty_mutex + */ + +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; +} + +/** + * tty_dev_name_to_number - return dev_t for device name + * @name: user space name of device under /dev + * @number: pointer to dev_t that this function will populate + * + * This function converts device names like ttyS0 or ttyUSB1 into dev_t + * like (4, 64) or (188, 1). If no corresponding driver is registered then + * the function returns -ENODEV. + * + * Locking: this acquires tty_mutex to protect the tty_drivers list from + * being modified while we are traversing it, and makes sure to + * release it before exiting. + */ +int tty_dev_name_to_number(const char *name, dev_t *number) +{ + struct tty_driver *p; + int ret; + int index, prefix_length = 0; + const char *str; + + for (str = name; *str && !isdigit(*str); str++) + ; + + if (!*str) + return -EINVAL; + + ret = kstrtoint(str, 10, &index); + if (ret) + return ret; + + prefix_length = str - name; + mutex_lock(&tty_mutex); + + list_for_each_entry(p, &tty_drivers, tty_drivers) + if (prefix_length == strlen(p->name) && strncmp(name, + p->name, prefix_length) == 0) { + if (index < p->num) { + *number = MKDEV(p->major, p->minor_start + index); + goto out; + } + } + + /* if here then driver wasn't found */ + ret = -ENODEV; +out: + mutex_unlock(&tty_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(tty_dev_name_to_number); + +#ifdef CONFIG_CONSOLE_POLL + +/** + * tty_find_polling_driver - find device of a polled tty + * @name: name string to match + * @line: pointer to resulting tty line nr + * + * This routine returns a tty driver structure, given a name + * and the condition that the tty driver is capable of polled + * operation. + */ +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 (!len || 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; +} +EXPORT_SYMBOL_GPL(tty_find_polling_driver); +#endif + +static ssize_t hung_up_tty_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + return 0; +} + +static ssize_t hung_up_tty_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + return -EIO; +} + +/* No kernel lock held - none needed ;) */ +static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait) +{ + return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM; +} + +static long hung_up_tty_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return cmd == TIOCSPGRP ? -ENOTTY : -EIO; +} + +static long hung_up_tty_compat_ioctl(struct file *file, + unsigned int cmd, unsigned long arg) +{ + return cmd == TIOCSPGRP ? -ENOTTY : -EIO; +} + +static int hung_up_tty_fasync(int fd, struct file *file, int on) +{ + return -ENOTTY; +} + +static void tty_show_fdinfo(struct seq_file *m, struct file *file) +{ + struct tty_struct *tty = file_tty(file); + + if (tty && tty->ops && tty->ops->show_fdinfo) + tty->ops->show_fdinfo(tty, m); +} + +static const struct file_operations tty_fops = { + .llseek = no_llseek, + .read = tty_read, + .write = tty_write, + .poll = tty_poll, + .unlocked_ioctl = tty_ioctl, + .compat_ioctl = tty_compat_ioctl, + .open = tty_open, + .release = tty_release, + .fasync = tty_fasync, + .show_fdinfo = tty_show_fdinfo, +}; + +static const struct file_operations console_fops = { + .llseek = no_llseek, + .read = tty_read, + .write = redirected_tty_write, + .poll = tty_poll, + .unlocked_ioctl = tty_ioctl, + .compat_ioctl = tty_compat_ioctl, + .open = tty_open, + .release = tty_release, + .fasync = tty_fasync, +}; + +static const struct file_operations hung_up_tty_fops = { + .llseek = no_llseek, + .read = hung_up_tty_read, + .write = hung_up_tty_write, + .poll = hung_up_tty_poll, + .unlocked_ioctl = hung_up_tty_ioctl, + .compat_ioctl = hung_up_tty_compat_ioctl, + .release = tty_release, + .fasync = hung_up_tty_fasync, +}; + +static DEFINE_SPINLOCK(redirect_lock); +static struct file *redirect; + +extern void tty_sysctl_init(void); + +/** + * tty_wakeup - request more data + * @tty: terminal + * + * Internal and external helper for wakeups of tty. This function + * informs the line discipline if present that the driver is ready + * to receive more output data. + */ + +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, EPOLLOUT); +} + +EXPORT_SYMBOL_GPL(tty_wakeup); + +/** + * __tty_hangup - actual handler for hangup events + * @work: tty device + * + * This can be called by a "kworker" kernel thread. That is process + * synchronous but doesn't hold any locks, so we need to make sure we + * have the appropriate locks for what we're doing. + * + * The hangup event clears any pending redirections onto the hung up + * device. It ensures future writes will error and it does the needed + * line discipline hangup and signal delivery. The tty object itself + * remains intact. + * + * Locking: + * BTM + * redirect lock for undoing redirection + * file list lock for manipulating list of ttys + * tty_ldiscs_lock from called functions + * termios_rwsem resetting termios data + * tasklist_lock to walk task list for hangup event + * ->siglock to protect ->signal/->sighand + */ +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; + } + + /* + * Some console devices aren't actually hung up for technical and + * historical reasons, which can lead to indefinite interruptible + * sleep in n_tty_read(). The following explicitly tells + * n_tty_read() to abort readers. + */ + set_bit(TTY_HUPPING, &tty->flags); + + /* 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, cons_filp != NULL); + + 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, which is now guaranteed. + */ + set_bit(TTY_HUPPED, &tty->flags); + clear_bit(TTY_HUPPING, &tty->flags); + tty_unlock(tty); + + if (f) + fput(f); +} + +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); +} + +/** + * tty_hangup - trigger a hangup event + * @tty: tty to hangup + * + * A carrier loss (virtual or otherwise) has occurred on this like + * schedule a hangup sequence to run after this event. + */ + +void tty_hangup(struct tty_struct *tty) +{ + tty_debug_hangup(tty, "hangup\n"); + schedule_work(&tty->hangup_work); +} + +EXPORT_SYMBOL(tty_hangup); + +/** + * tty_vhangup - process vhangup + * @tty: tty to hangup + * + * The user has asked via system call for the terminal to be hung up. + * We do this synchronously so that when the syscall returns the process + * is complete. That guarantee is necessary for security reasons. + */ + +void tty_vhangup(struct tty_struct *tty) +{ + tty_debug_hangup(tty, "vhangup\n"); + __tty_hangup(tty, 0); +} + +EXPORT_SYMBOL(tty_vhangup); + + +/** + * tty_vhangup_self - process vhangup for own ctty + * + * Perform a vhangup on the current controlling tty + */ + +void tty_vhangup_self(void) +{ + struct tty_struct *tty; + + tty = get_current_tty(); + if (tty) { + tty_vhangup(tty); + tty_kref_put(tty); + } +} + +/** + * tty_vhangup_session - hangup session leader exit + * @tty: tty to hangup + * + * The session leader is exiting and hanging up its controlling terminal. + * Every process in the foreground process group is signalled SIGHUP. + * + * We do this synchronously so that when the syscall returns the process + * is complete. That guarantee is necessary for security reasons. + */ + +void tty_vhangup_session(struct tty_struct *tty) +{ + tty_debug_hangup(tty, "session hangup\n"); + __tty_hangup(tty, 1); +} + +/** + * tty_hung_up_p - was tty hung up + * @filp: file pointer of tty + * + * Return true if the tty has been subject to a vhangup or a carrier + * loss + */ + +int tty_hung_up_p(struct file *filp) +{ + return (filp && filp->f_op == &hung_up_tty_fops); +} + +EXPORT_SYMBOL(tty_hung_up_p); + +/** + * stop_tty - propagate flow control + * @tty: tty to stop + * + * Perform flow control to the driver. May be called + * on an already stopped device and will not re-call the driver + * method. + * + * This functionality is used by both the line disciplines for + * halting incoming flow and by the driver. It may therefore be + * called from any context, may be under the tty atomic_write_lock + * but not always. + * + * Locking: + * flow_lock + */ + +void __stop_tty(struct tty_struct *tty) +{ + if (tty->stopped) + return; + tty->stopped = 1; + if (tty->ops->stop) + tty->ops->stop(tty); +} + +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); +} +EXPORT_SYMBOL(stop_tty); + +/** + * start_tty - propagate flow control + * @tty: tty to start + * + * Start a tty that has been stopped if at all possible. If this + * tty was previous stopped and is now being started, the driver + * start method is invoked and the line discipline woken. + * + * Locking: + * flow_lock + */ + +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); +} + +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); +} +EXPORT_SYMBOL(start_tty); + +static void tty_update_time(struct timespec64 *time) +{ + time64_t sec = ktime_get_real_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; +} + +/** + * tty_read - read method for tty device files + * @file: pointer to tty file + * @buf: user buffer + * @count: size of user buffer + * @ppos: unused + * + * Perform the read system call function on this terminal device. Checks + * for hung up devices before calling the line discipline method. + * + * Locking: + * Locks the line discipline internally while needed. Multiple + * read calls may be outstanding in parallel. + */ + +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 || tty_io_error(tty)) + return -EIO; + + /* We want to wait for the line discipline to sort out in this + situation */ + ld = tty_ldisc_ref_wait(tty); + if (!ld) + return hung_up_tty_read(file, buf, count, ppos); + 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; +} + +static void tty_write_unlock(struct tty_struct *tty) +{ + mutex_unlock(&tty->atomic_write_lock); + wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT); +} + +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; +} + +/* + * Split writes up in sane blocksizes to avoid + * denial-of-service type attacks + */ +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; +} + +/** + * tty_write_message - write a message to a certain tty, not just the console. + * @tty: the destination tty_struct + * @msg: the message to write + * + * This is used for messages that need to be redirected to a specific tty. + * We don't put it into the syslog queue right now maybe in the future if + * really needed. + * + * We must still hold the BTM and test the CLOSING flag for the moment. + */ + +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; +} + + +/** + * tty_write - write method for tty device file + * @file: tty file pointer + * @buf: user data to write + * @count: bytes to write + * @ppos: unused + * + * Write data to a tty device via the line discipline. + * + * Locking: + * Locks the line discipline as required + * Writes to the tty driver are serialized by the atomic_write_lock + * and are then processed in chunks to the device. The line discipline + * write method will not be invoked in parallel for each device. + */ + +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 || tty_io_error(tty)) + 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) + return hung_up_tty_write(file, buf, count, ppos); + if (!ld->ops->write) + ret = -EIO; + else + ret = do_tty_write(ld->ops->write, tty, file, buf, count); + tty_ldisc_deref(ld); + return ret; +} + +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); +} + +/** + * tty_send_xchar - send priority character + * + * Send a high priority character to the tty even if stopped + * + * Locking: none for xchar method, write ordering for write method. + */ + +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; +} + +static char ptychar[] = "pqrstuvwxyzabcde"; + +/** + * pty_line_name - generate name for a pty + * @driver: the tty driver in use + * @index: the minor number + * @p: output buffer of at least 6 bytes + * + * Generate a name from a driver reference and write it to the output + * buffer. + * + * Locking: None + */ +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); +} + +/** + * tty_line_name - generate name for a tty + * @driver: the tty driver in use + * @index: the minor number + * @p: output buffer of at least 7 bytes + * + * Generate a name from a driver reference and write it to the output + * buffer. + * + * Locking: None + */ +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); +} + +/** + * tty_driver_lookup_tty() - find an existing tty, if any + * @driver: the driver for the tty + * @idx: the minor number + * + * Return the tty, if found. If not found, return NULL or ERR_PTR() if the + * driver lookup() method returns an error. + * + * Locking: tty_mutex must be held. If the tty is found, bump the tty kref. + */ +static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, + struct file *file, int idx) +{ + struct tty_struct *tty; + + if (driver->ops->lookup) + if (!file) + tty = ERR_PTR(-EIO); + else + tty = driver->ops->lookup(driver, file, idx); + else + tty = driver->ttys[idx]; + + if (!IS_ERR(tty)) + tty_kref_get(tty); + return tty; +} + +/** + * tty_init_termios - helper for termios setup + * @tty: the tty to set up + * + * Initialise the termios structures for this tty. Thus runs under + * the tty_mutex currently so we can be relaxed about ordering. + */ + +void 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; + tty->termios.c_line = tty->driver->init_termios.c_line; + } 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); +} +EXPORT_SYMBOL_GPL(tty_init_termios); + +int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty) +{ + tty_init_termios(tty); + tty_driver_kref_get(driver); + tty->count++; + driver->ttys[tty->index] = tty; + return 0; +} +EXPORT_SYMBOL_GPL(tty_standard_install); + +/** + * tty_driver_install_tty() - install a tty entry in the driver + * @driver: the driver for the tty + * @tty: the tty + * + * Install a tty object into the driver tables. The tty->index field + * will be set by the time this is called. This method is responsible + * for ensuring any need additional structures are allocated and + * configured. + * + * Locking: tty_mutex for now + */ +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); +} + +/** + * tty_driver_remove_tty() - remove a tty from the driver tables + * @driver: the driver for the tty + * @idx: the minor number + * + * Remvoe a tty object from the driver tables. The tty->index field + * will be set by the time this is called. + * + * Locking: tty_mutex for now + */ +static 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; +} + +/* + * tty_reopen() - fast re-open of an open tty + * @tty - the tty to open + * + * Return 0 on success, -errno on error. + * Re-opens on master ptys are not allowed and return -EIO. + * + * Locking: Caller must hold tty_lock + */ +static int tty_reopen(struct tty_struct *tty) +{ + struct tty_driver *driver = tty->driver; + struct tty_ldisc *ld; + int retval = 0; + + 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; + + ld = tty_ldisc_ref_wait(tty); + if (ld) { + tty_ldisc_deref(ld); + } else { + retval = tty_ldisc_lock(tty, 5 * HZ); + if (retval) + return retval; + + if (!tty->ldisc) + retval = tty_ldisc_reinit(tty, tty->termios.c_line); + tty_ldisc_unlock(tty); + } + + if (retval == 0) + tty->count++; + + return retval; +} + +/** + * tty_init_dev - initialise a tty device + * @driver: tty driver we are opening a device on + * @idx: device index + * @ret_tty: returned tty structure + * + * Prepare a tty device. This may not be a "new" clean device but + * could also be an active device. The pty drivers require special + * handling because of this. + * + * Locking: + * The function is called under the tty_mutex, which + * protects us from the tty struct or driver itself going away. + * + * On exit the tty device has the line discipline attached and + * a reference count of 1. If a pair was created for pty/tty use + * and the other was a pty master then it too has a reference count of 1. + * + * WSH 06/09/97: Rewritten to remove races and properly clean up after a + * failed open. The new code protects the open with a mutex, so it's + * really quite straightforward. The mutex locking can probably be + * relaxed for the (most common) case of reopening a tty. + */ + +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 + * 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_free_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); + + retval = tty_ldisc_lock(tty, 5 * HZ); + if (retval) + goto err_release_lock; + 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; + tty_ldisc_unlock(tty); + /* Return the tty locked so that it cannot vanish under the caller */ + return tty; + +err_free_tty: + tty_unlock(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_ldisc_unlock(tty); + tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n", + retval, idx); +err_release_lock: + tty_unlock(tty); + release_tty(tty, idx); + return ERR_PTR(retval); +} + +/** + * tty_save_termios() - save tty termios data in driver table + * @tty: tty whose termios data to save + * + * Locking: Caller guarantees serialisation with tty_init_termios(). + */ +void tty_save_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; +} +EXPORT_SYMBOL_GPL(tty_save_termios); + +/** + * tty_flush_works - flush all works of a tty/pty pair + * @tty: tty device to flush works for (or either end of a pty pair) + * + * Sync flush all works belonging to @tty (and the 'other' tty). + */ +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); + } +} + +/** + * release_one_tty - release tty structure memory + * @kref: kref of tty we are obliterating + * + * Releases memory associated with a tty structure, and clears out the + * driver table slots. This function is called when a device is no longer + * in use. It also gets called when setup of a device fails. + * + * Locking: + * takes the file list lock internally when working on the list + * of ttys that the driver keeps. + * + * This method gets called from a work queue so that the driver private + * cleanup ops can sleep (needed for USB at least) + */ +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); +} + +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); +} + +/** + * tty_kref_put - release a tty kref + * @tty: tty device + * + * Release a reference to a tty device and if need be let the kref + * layer destruct the object for us + */ + +void tty_kref_put(struct tty_struct *tty) +{ + if (tty) + kref_put(&tty->kref, queue_release_one_tty); +} +EXPORT_SYMBOL(tty_kref_put); + +/** + * release_tty - release tty structure memory + * + * Release both @tty and a possible linked partner (think pty pair), + * and decrement the refcount of the backing module. + * + * Locking: + * tty_mutex + * takes the file list lock internally when working on the list + * of ttys that the driver keeps. + * + */ +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_save_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); + if (tty->link) + tty_buffer_cancel_work(tty->link->port); + + tty_kref_put(tty->link); + tty_kref_put(tty); +} + +/** + * tty_release_checks - check a tty before real release + * @tty: tty to check + * @o_tty: link of @tty (if any) + * @idx: index of the tty + * + * Performs some paranoid checking before true release of the @tty. + * This is a no-op unless TTY_PARANOIA_CHECK is defined. + */ +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; +} + +/** + * tty_kclose - closes tty opened by tty_kopen + * @tty: tty device + * + * Performs the final steps to release and free a tty device. It is the + * same as tty_release_struct except that it also resets TTY_PORT_KOPENED + * flag on tty->port. + */ +void tty_kclose(struct tty_struct *tty) +{ + /* + * 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); + tty_port_set_kopened(tty->port, 0); + release_tty(tty, tty->index); + mutex_unlock(&tty_mutex); +} +EXPORT_SYMBOL_GPL(tty_kclose); + +/** + * tty_release_struct - release a tty struct + * @tty: tty device + * @idx: index of the tty + * + * Performs the final steps to release and free a tty device. It is + * roughly the reverse of tty_init_dev. + */ +void tty_release_struct(struct tty_struct *tty, int idx) +{ + /* + * 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); +} +EXPORT_SYMBOL_GPL(tty_release_struct); + +/** + * tty_release - vfs callback for close + * @inode: inode of tty + * @filp: file pointer for handle to tty + * + * Called the last time each file handle is closed that references + * this tty. There may however be several such references. + * + * Locking: + * Takes bkl. See tty_release_dev + * + * Even releasing the tty structures is a tricky business.. We have + * to be very careful that the structures are all released at the + * same time, as interrupts might otherwise get the wrong pointers. + * + * WSH 09/09/97: rewritten to avoid some nasty race conditions that could + * lead to double frees or releasing memory still in use. + */ + +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, EPOLLIN); + do_sleep++; + } + if (waitqueue_active(&tty->write_wait)) { + wake_up_poll(&tty->write_wait, EPOLLOUT); + do_sleep++; + } + } + if (o_tty && o_tty->count <= 1) { + if (waitqueue_active(&o_tty->read_wait)) { + wake_up_poll(&o_tty->read_wait, EPOLLIN); + do_sleep++; + } + if (waitqueue_active(&o_tty->write_wait)) { + wake_up_poll(&o_tty->write_wait, EPOLLOUT); + 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"); + + tty_release_struct(tty, idx); + return 0; +} + +/** + * tty_open_current_tty - get locked tty of current task + * @device: device number + * @filp: file pointer to tty + * @return: locked tty of the current task iff @device is /dev/tty + * + * Performs a re-open of the current task's controlling tty. + * + * We cannot return driver and index like for the other nodes because + * devpts will not work then. It expects inodes to be from devpts FS. + */ +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; +} + +/** + * tty_lookup_driver - lookup a tty driver for a given device file + * @device: device number + * @filp: file pointer to tty + * @index: index for the device in the @return driver + * @return: driver for this inode (with increased refcount) + * + * If @return is not erroneous, the caller is responsible to decrement the + * refcount by tty_driver_kref_put. + * + * Locking: tty_mutex protects get_tty_driver + */ +static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp, + 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; + 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 && filp) { + /* Don't let /dev/console block */ + filp->f_flags |= O_NONBLOCK; + break; + } + } + return ERR_PTR(-ENODEV); + } + default: + driver = get_tty_driver(device, index); + if (!driver) + return ERR_PTR(-ENODEV); + break; + } + return driver; +} + +/** + * tty_kopen - open a tty device for kernel + * @device: dev_t of device to open + * + * Opens tty exclusively for kernel. Performs the driver lookup, + * makes sure it's not already opened and performs the first-time + * tty initialization. + * + * Returns the locked initialized &tty_struct + * + * Claims the global tty_mutex to serialize: + * - concurrent first-time tty initialization + * - concurrent tty driver removal w/ lookup + * - concurrent tty removal from driver table + */ +struct tty_struct *tty_kopen(dev_t device) +{ + struct tty_struct *tty; + struct tty_driver *driver = NULL; + int index = -1; + + mutex_lock(&tty_mutex); + driver = tty_lookup_driver(device, NULL, &index); + if (IS_ERR(driver)) { + mutex_unlock(&tty_mutex); + return ERR_CAST(driver); + } + + /* check whether we're reopening an existing tty */ + tty = tty_driver_lookup_tty(driver, NULL, index); + if (IS_ERR(tty)) + goto out; + + if (tty) { + /* drop kref from tty_driver_lookup_tty() */ + tty_kref_put(tty); + tty = ERR_PTR(-EBUSY); + } else { /* tty_init_dev returns tty with the tty_lock held */ + tty = tty_init_dev(driver, index); + if (IS_ERR(tty)) + goto out; + tty_port_set_kopened(tty->port, 1); + } +out: + mutex_unlock(&tty_mutex); + tty_driver_kref_put(driver); + return tty; +} +EXPORT_SYMBOL_GPL(tty_kopen); + +/** + * tty_open_by_driver - open a tty device + * @device: dev_t of device to open + * @inode: inode of device file + * @filp: file pointer to tty + * + * Performs the driver lookup, checks for a reopen, or otherwise + * performs the first-time tty initialization. + * + * Returns the locked initialized or re-opened &tty_struct + * + * Claims the global tty_mutex to serialize: + * - concurrent first-time tty initialization + * - concurrent tty driver removal w/ lookup + * - concurrent tty removal from driver table + */ +static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, + struct file *filp) +{ + struct tty_struct *tty; + struct tty_driver *driver = NULL; + int index = -1; + int retval; + + mutex_lock(&tty_mutex); + driver = tty_lookup_driver(device, filp, &index); + if (IS_ERR(driver)) { + mutex_unlock(&tty_mutex); + return ERR_CAST(driver); + } + + /* check whether we're reopening an existing tty */ + tty = tty_driver_lookup_tty(driver, filp, index); + if (IS_ERR(tty)) { + mutex_unlock(&tty_mutex); + goto out; + } + + if (tty) { + if (tty_port_kopened(tty->port)) { + tty_kref_put(tty); + mutex_unlock(&tty_mutex); + tty = ERR_PTR(-EBUSY); + goto out; + } + mutex_unlock(&tty_mutex); + retval = tty_lock_interruptible(tty); + tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */ + if (retval) { + if (retval == -EINTR) + retval = -ERESTARTSYS; + tty = ERR_PTR(retval); + goto out; + } + 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); + } +out: + tty_driver_kref_put(driver); + return tty; +} + +/** + * tty_open - open a tty device + * @inode: inode of device file + * @filp: file pointer to tty + * + * tty_open and tty_release keep up the tty count that contains the + * number of opens done on a tty. We cannot use the inode-count, as + * different inodes might point to the same tty. + * + * Open-counting is needed for pty masters, as well as for keeping + * track of serial lines: DTR is dropped when the last close happens. + * (This is not done solely through tty->count, now. - Ted 1/27/92) + * + * The termios state of a pty is reset on first open so that + * settings don't persist across reuse. + * + * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev. + * tty->count should protect the rest. + * ->siglock protects ->signal/->sighand + * + * Note: the tty_unlock/lock cases without a ref are only safe due to + * tty_mutex + */ + +static int tty_open(struct inode *inode, struct file *filp) +{ + struct tty_struct *tty; + int noctty, retval; + 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; + + tty = tty_open_current_tty(device, filp); + if (!tty) + tty = tty_open_by_driver(device, inode, filp); + + if (IS_ERR(tty)) { + tty_free_file(filp); + retval = PTR_ERR(tty); + if (retval != -EAGAIN || signal_pending(current)) + return retval; + schedule(); + goto retry_open; + } + + tty_add_file(tty, filp); + + check_tty_count(tty, __func__); + 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); + + noctty = (filp->f_flags & O_NOCTTY) || + (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) || + device == MKDEV(TTYAUX_MAJOR, 1) || + (tty->driver->type == TTY_DRIVER_TYPE_PTY && + tty->driver->subtype == PTY_TYPE_MASTER); + if (!noctty) + tty_open_proc_set_tty(filp, tty); + tty_unlock(tty); + return 0; +} + + + +/** + * tty_poll - check tty status + * @filp: file being polled + * @wait: poll wait structures to update + * + * Call the line discipline polling method to obtain the poll + * status of the device. + * + * Locking: locks called line discipline but ldisc poll method + * may be re-entered freely by other callers. + */ + +static __poll_t tty_poll(struct file *filp, poll_table *wait) +{ + struct tty_struct *tty = file_tty(filp); + struct tty_ldisc *ld; + __poll_t ret = 0; + + if (tty_paranoia_check(tty, file_inode(filp), "tty_poll")) + return 0; + + ld = tty_ldisc_ref_wait(tty); + if (!ld) + return hung_up_tty_poll(filp, wait); + if (ld->ops->poll) + ret = ld->ops->poll(tty, filp, wait); + tty_ldisc_deref(ld); + return ret; +} + +static int __tty_fasync(int fd, struct file *filp, int on) +{ + struct tty_struct *tty = file_tty(filp); + 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; + + 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_TGID; + } + get_pid(pid); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + __f_setown(filp, pid, type, 0); + put_pid(pid); + retval = 0; + } +out: + return retval; +} + +static int tty_fasync(int fd, struct file *filp, int on) +{ + struct tty_struct *tty = file_tty(filp); + int retval = -ENOTTY; + + tty_lock(tty); + if (!tty_hung_up_p(filp)) + retval = __tty_fasync(fd, filp, on); + tty_unlock(tty); + + return retval; +} + +/** + * tiocsti - fake input character + * @tty: tty to fake input into + * @p: pointer to character + * + * Fake input to a tty device. Does the necessary locking and + * input management. + * + * FIXME: does not honour flow control ?? + * + * Locking: + * Called functions take tty_ldiscs_lock + * current->signal->tty check is safe without locks + */ + +static int tiocsti(struct tty_struct *tty, char __user *p) +{ + char ch, mbz = 0; + struct tty_ldisc *ld; + + if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + if (get_user(ch, p)) + return -EFAULT; + tty_audit_tiocsti(tty, ch); + ld = tty_ldisc_ref_wait(tty); + if (!ld) + return -EIO; + tty_buffer_lock_exclusive(tty->port); + if (ld->ops->receive_buf) + ld->ops->receive_buf(tty, &ch, &mbz, 1); + tty_buffer_unlock_exclusive(tty->port); + tty_ldisc_deref(ld); + return 0; +} + +/** + * tiocgwinsz - implement window query ioctl + * @tty; tty + * @arg: user buffer for result + * + * Copies the kernel idea of the window size into the user buffer. + * + * Locking: tty->winsize_mutex is taken to ensure the winsize data + * is consistent. + */ + +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; +} + +/** + * tty_do_resize - resize event + * @tty: tty being resized + * @rows: rows (character) + * @cols: cols (character) + * + * Update the termios variables and send the necessary signals to + * peform a terminal resize correctly + */ + +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; +} +EXPORT_SYMBOL(tty_do_resize); + +/** + * tiocswinsz - implement window size set ioctl + * @tty; tty side of tty + * @arg: user buffer for result + * + * Copies the user idea of the window size to the kernel. Traditionally + * this is just advisory information but for the Linux console it + * actually has driver level meaning and triggers a VC resize. + * + * Locking: + * Driver dependent. The default do_resize method takes the + * tty termios mutex and ctrl_lock. The console takes its own lock + * then calls into the default method. + */ + +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); +} + +/** + * tioccons - allow admin to move logical console + * @file: the file to become console + * + * Allow the administrator to move the redirected console device + * + * Locking: uses redirect_lock to guard the redirect information + */ + +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; +} + +/** + * fionbio - non blocking ioctl + * @file: file to set blocking value + * @p: user parameter + * + * Historical tty interfaces had a blocking control ioctl before + * the generic functionality existed. This piece of history is preserved + * in the expected tty API of posix OS's. + * + * Locking: none, the open file handle ensures it won't go away. + */ + +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; +} + +/** + * tiocsetd - set line discipline + * @tty: tty device + * @p: pointer to user data + * + * Set the line discipline according to user request. + * + * Locking: see tty_set_ldisc, this function is just a helper + */ + +static int tiocsetd(struct tty_struct *tty, int __user *p) +{ + int disc; + int ret; + + if (get_user(disc, p)) + return -EFAULT; + + ret = tty_set_ldisc(tty, disc); + + return ret; +} + +/** + * tiocgetd - get line discipline + * @tty: tty device + * @p: pointer to user data + * + * Retrieves the line discipline id directly from the ldisc. + * + * Locking: waits for ldisc reference (in case the line discipline + * is changing or the tty is being hungup) + */ + +static int tiocgetd(struct tty_struct *tty, int __user *p) +{ + struct tty_ldisc *ld; + int ret; + + ld = tty_ldisc_ref_wait(tty); + if (!ld) + return -EIO; + ret = put_user(ld->ops->num, p); + tty_ldisc_deref(ld); + return ret; +} + +/** + * send_break - performed time break + * @tty: device to break on + * @duration: timeout in mS + * + * Perform a timed break on hardware that lacks its own driver level + * timed break functionality. + * + * Locking: + * atomic_write_lock serializes + * + */ + +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; +} + +/** + * tty_tiocmget - get modem status + * @tty: tty device + * @file: user file pointer + * @p: pointer to result + * + * Obtain the modem status bits from the tty driver if the feature + * is supported. Return -ENOTTY if it is not available. + * + * Locking: none (up to the driver) + */ + +static int tty_tiocmget(struct tty_struct *tty, int __user *p) +{ + int retval = -ENOTTY; + + if (tty->ops->tiocmget) { + retval = tty->ops->tiocmget(tty); + + if (retval >= 0) + retval = put_user(retval, p); + } + return retval; +} + +/** + * tty_tiocmset - set modem status + * @tty: tty device + * @cmd: command - clear bits, set bits or set all + * @p: pointer to desired bits + * + * Set the modem status bits from the tty driver if the feature + * is supported. Return -ENOTTY if it is not available. + * + * Locking: none (up to the driver) + */ + +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 -ENOTTY; + + 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); +} + +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; +} + +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_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n", + __func__, get_task_comm(comm, current), flags); +} + +/* + * if pty, return the slave side (real_tty) + * otherwise, return self + */ +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; +} + +/* + * Split this up, as gcc can choke on it otherwise.. + */ +long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct tty_struct *tty = file_tty(file); + struct tty_struct *real_tty; + void __user *p = (void __user *)arg; + int retval; + struct tty_ldisc *ld; + + if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl")) + return -EINVAL; + + real_tty = tty_pair_get_tty(tty); + + /* + * Factor out some common prep work + */ + switch (cmd) { + case TIOCSETD: + case TIOCSBRK: + case TIOCCBRK: + case TCSBRK: + case TCSBRKP: + retval = tty_check_change(tty); + if (retval) + return retval; + if (cmd != TIOCCBRK) { + tty_wait_until_sent(tty, 0); + if (signal_pending(current)) + return -EINTR; + } + break; + } + + /* + * Now do the stuff. + */ + switch (cmd) { + case TIOCSTI: + return tiocsti(tty, p); + case TIOCGWINSZ: + return tiocgwinsz(real_tty, p); + case TIOCSWINSZ: + return tiocswinsz(real_tty, p); + case TIOCCONS: + return real_tty != tty ? -EINVAL : tioccons(file); + case FIONBIO: + return fionbio(file, p); + case TIOCEXCL: + set_bit(TTY_EXCLUSIVE, &tty->flags); + return 0; + case TIOCNXCL: + clear_bit(TTY_EXCLUSIVE, &tty->flags); + return 0; + case TIOCGEXCL: + { + int excl = test_bit(TTY_EXCLUSIVE, &tty->flags); + return put_user(excl, (int __user *)p); + } + case TIOCGETD: + return tiocgetd(tty, p); + case TIOCSETD: + return tiocsetd(tty, p); + case TIOCVHANGUP: + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + tty_vhangup(tty); + return 0; + case TIOCGDEV: + { + unsigned int ret = new_encode_dev(tty_devnum(real_tty)); + return put_user(ret, (unsigned int __user *)p); + } + /* + * Break handling + */ + case TIOCSBRK: /* Turn break on, unconditionally */ + if (tty->ops->break_ctl) + return tty->ops->break_ctl(tty, -1); + return 0; + case TIOCCBRK: /* Turn break off, unconditionally */ + if (tty->ops->break_ctl) + return tty->ops->break_ctl(tty, 0); + return 0; + case TCSBRK: /* SVID version: non-zero arg --> no break */ + /* non-zero arg means wait for all output data + * to be sent (performed above) but don't send break. + * This is used by the tcdrain() termios function. + */ + if (!arg) + return send_break(tty, 250); + return 0; + case TCSBRKP: /* support for POSIX tcsendbreak() */ + return send_break(tty, arg ? arg*100 : 250); + + case TIOCMGET: + return tty_tiocmget(tty, p); + case TIOCMSET: + case TIOCMBIC: + case TIOCMBIS: + return tty_tiocmset(tty, cmd, p); + case TIOCGICOUNT: + retval = tty_tiocgicount(tty, p); + /* For the moment allow fall through to the old method */ + if (retval != -EINVAL) + return retval; + break; + case TCFLSH: + switch (arg) { + case TCIFLUSH: + case TCIOFLUSH: + /* flush tty buffer and allow ldisc to process ioctl */ + tty_buffer_flush(tty, NULL); + break; + } + break; + case TIOCSSERIAL: + tty_warn_deprecated_flags(p); + break; + case TIOCGPTPEER: + /* Special because the struct file is needed */ + return ptm_open_peer(file, tty, (int)arg); + default: + retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg); + if (retval != -ENOIOCTLCMD) + return retval; + } + if (tty->ops->ioctl) { + retval = tty->ops->ioctl(tty, cmd, arg); + if (retval != -ENOIOCTLCMD) + return retval; + } + ld = tty_ldisc_ref_wait(tty); + if (!ld) + return hung_up_tty_ioctl(file, cmd, arg); + retval = -EINVAL; + if (ld->ops->ioctl) { + retval = ld->ops->ioctl(tty, file, cmd, arg); + if (retval == -ENOIOCTLCMD) + retval = -ENOTTY; + } + tty_ldisc_deref(ld); + return retval; +} + +#ifdef CONFIG_COMPAT +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) + return hung_up_tty_compat_ioctl(file, cmd, arg); + 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; +} +#endif + +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; +} + +/* + * This implements the "Secure Attention Key" --- the idea is to + * prevent trojan horses by killing all processes associated with this + * tty when the user hits the "Secure Attention Key". Required for + * super-paranoid applications --- see the Orange Book for more details. + * + * This code could be nicer; ideally it should send a HUP, wait a few + * seconds, then send a INT, and then a KILL signal. But you then + * have to coordinate with the init process, since all processes associated + * with the current tty must be dead before the new getty is allowed + * to spawn. + * + * Now, if it would be correct ;-/ The current code has a nasty hole - + * it doesn't catch files in flight. We may send the descriptor to ourselves + * via AF_UNIX socket, close it and later fetch from socket. FIXME. + * + * Nasty bug: do_SAK is being called in interrupt context. This can + * deadlock. We punt it up to process context. AKPM - 16Mar2001 + */ +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; + unsigned long flags; + + if (!tty) + return; + + spin_lock_irqsave(&tty->ctrl_lock, flags); + session = get_pid(tty->session); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + + 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); + put_pid(session); +#endif +} + +static void do_SAK_work(struct work_struct *work) +{ + struct tty_struct *tty = + container_of(work, struct tty_struct, SAK_work); + __do_SAK(tty); +} + +/* + * The tq handling here is a little racy - tty->SAK_work may already be queued. + * Fortunately we don't need to worry, because if ->SAK_work is already queued, + * the values which we write to it will be identical to the values which it + * already has. --akpm + */ +void do_SAK(struct tty_struct *tty) +{ + if (!tty) + return; + schedule_work(&tty->SAK_work); +} + +EXPORT_SYMBOL(do_SAK); + +static int dev_match_devt(struct device *dev, const void *data) +{ + const dev_t *devt = data; + return dev->devt == *devt; +} + +/* Must put_device() after it's unused! */ +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); +} + + +/** + * alloc_tty_struct + * + * This subroutine allocates and initializes a tty structure. + * + * Locking: none - tty in question is not exposed at this point + */ + +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; + if (tty_ldisc_init(tty)) { + kfree(tty); + return NULL; + } + 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); + spin_lock_init(&tty->files_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; +} + +/** + * tty_put_char - write one character to a tty + * @tty: tty + * @ch: character + * + * Write one byte to the tty using the provided put_char method + * if present. Returns the number of characters successfully output. + * + * Note: the specific put_char operation in the driver layer may go + * away soon. Don't call it directly, use this method + */ + +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); +} +EXPORT_SYMBOL_GPL(tty_put_char); + +struct class *tty_class; + +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; +} + +/** + * tty_register_device - register a tty device + * @driver: the tty driver that describes the tty device + * @index: the index in the tty driver for this tty device + * @device: a struct device that is associated with this tty device. + * This field is optional, if there is no known struct device + * for this tty device it can be set to NULL safely. + * + * Returns a pointer to the struct device for this tty device + * (or ERR_PTR(-EFOO) on error). + * + * This call is required to be made to register an individual tty device + * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If + * that bit is not set, this function should not be called by a tty + * driver. + * + * Locking: ?? + */ + +struct device *tty_register_device(struct tty_driver *driver, unsigned index, + struct device *device) +{ + return tty_register_device_attr(driver, index, device, NULL, NULL); +} +EXPORT_SYMBOL(tty_register_device); + +static void tty_device_create_release(struct device *dev) +{ + dev_dbg(dev, "releasing...\n"); + kfree(dev); +} + +/** + * tty_register_device_attr - register a tty device + * @driver: the tty driver that describes the tty device + * @index: the index in the tty driver for this tty device + * @device: a struct device that is associated with this tty device. + * This field is optional, if there is no known struct device + * for this tty device it can be set to NULL safely. + * @drvdata: Driver data to be set to device. + * @attr_grp: Attribute group to be set on device. + * + * Returns a pointer to the struct device for this tty device + * (or ERR_PTR(-EFOO) on error). + * + * This call is required to be made to register an individual tty device + * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If + * that bit is not set, this function should not be called by a tty + * driver. + * + * Locking: ?? + */ +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 ktermios *tp; + struct device *dev; + int retval; + + 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); + + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) + return ERR_PTR(-ENOMEM); + + 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); + + dev_set_uevent_suppress(dev, 1); + + retval = device_register(dev); + if (retval) + goto err_put; + + if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) { + /* + * Free any saved termios data so that the termios state is + * reset when reusing a minor number. + */ + tp = driver->termios[index]; + if (tp) { + driver->termios[index] = NULL; + kfree(tp); + } + + retval = tty_cdev_add(driver, devt, index, 1); + if (retval) + goto err_del; + } + + dev_set_uevent_suppress(dev, 0); + kobject_uevent(&dev->kobj, KOBJ_ADD); + + return dev; + +err_del: + device_del(dev); +err_put: + put_device(dev); + + return ERR_PTR(retval); +} +EXPORT_SYMBOL_GPL(tty_register_device_attr); + +/** + * tty_unregister_device - unregister a tty device + * @driver: the tty driver that describes the tty device + * @index: the index in the tty driver for this tty device + * + * If a tty device is registered with a call to tty_register_device() then + * this function must be called when the tty device is gone. + * + * Locking: ?? + */ + +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; + } +} +EXPORT_SYMBOL(tty_unregister_device); + +/** + * __tty_alloc_driver -- allocate tty driver + * @lines: count of lines this driver can handle at most + * @owner: module which is responsible for this driver + * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags + * + * This should not be called directly, some of the provided macros should be + * used instead. Use IS_ERR and friends on @retval. + */ +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); +} +EXPORT_SYMBOL(__tty_alloc_driver); + +static void destruct_tty_driver(struct kref *kref) +{ + struct tty_driver *driver = container_of(kref, struct tty_driver, kref); + int i; + struct ktermios *tp; + + if (driver->flags & TTY_DRIVER_INSTALLED) { + for (i = 0; i < driver->num; i++) { + tp = driver->termios[i]; + if (tp) { + driver->termios[i] = NULL; + kfree(tp); + } + if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) + tty_unregister_device(driver, i); + } + proc_tty_unregister_driver(driver); + if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) + cdev_del(driver->cdevs[0]); + } + kfree(driver->cdevs); + kfree(driver->ports); + kfree(driver->termios); + kfree(driver->ttys); + kfree(driver); +} + +void tty_driver_kref_put(struct tty_driver *driver) +{ + kref_put(&driver->kref, destruct_tty_driver); +} +EXPORT_SYMBOL(tty_driver_kref_put); + +void tty_set_operations(struct tty_driver *driver, + const struct tty_operations *op) +{ + driver->ops = op; +}; +EXPORT_SYMBOL(tty_set_operations); + +void put_tty_driver(struct tty_driver *d) +{ + tty_driver_kref_put(d); +} +EXPORT_SYMBOL(put_tty_driver); + +/* + * Called by a tty driver to register itself. + */ +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; +} +EXPORT_SYMBOL(tty_register_driver); + +/* + * Called by a tty driver to unregister itself. + */ +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; +} + +EXPORT_SYMBOL(tty_unregister_driver); + +dev_t tty_devnum(struct tty_struct *tty) +{ + return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; +} +EXPORT_SYMBOL(tty_devnum); + +void tty_default_fops(struct file_operations *fops) +{ + *fops = tty_fops; +} + +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; +} + +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; +} + +postcore_initcall(tty_class_init); + +/* 3/2004 jmc: why do these devices exist? */ +static struct cdev tty_cdev, console_cdev; + +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; +} +static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL); + +static struct attribute *cons_dev_attrs[] = { + &dev_attr_active.attr, + NULL +}; + +ATTRIBUTE_GROUPS(cons_dev); + +static struct device *consdev; + +void console_sysfs_notify(void) +{ + if (consdev) + sysfs_notify(&consdev->kobj, NULL, "active"); +} + +/* + * Ok, now we can initialize the rest of the tty devices and can count + * on memory allocations, interrupts etc.. + */ +int __init tty_init(void) +{ + tty_sysctl_init(); + 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; +} + |