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linux/drivers/tty/pty.c
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license 
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

956 lines
24 KiB
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
*
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/fcntl.h>
#include <linux/sched/signal.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/ioctl.h>
#undef TTY_DEBUG_HANGUP
#ifdef TTY_DEBUG_HANGUP
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
#else
# define tty_debug_hangup(tty, f, args...) do {} while (0)
#endif
#ifdef CONFIG_UNIX98_PTYS
static struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
static DEFINE_MUTEX(devpts_mutex);
#endif
static void pty_close(struct tty_struct *tty, struct file *filp)
{
BUG_ON(!tty);
if (tty->driver->subtype == PTY_TYPE_MASTER)
WARN_ON(tty->count > 1);
else {
if (tty_io_error(tty))
return;
if (tty->count > 2)
return;
}
set_bit(TTY_IO_ERROR, &tty->flags);
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
spin_lock_irq(&tty->ctrl_lock);
tty->packet = 0;
spin_unlock_irq(&tty->ctrl_lock);
/* Review - krefs on tty_link ?? */
if (!tty->link)
return;
set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
wake_up_interruptible(&tty->link->read_wait);
wake_up_interruptible(&tty->link->write_wait);
if (tty->driver->subtype == PTY_TYPE_MASTER) {
set_bit(TTY_OTHER_CLOSED, &tty->flags);
#ifdef CONFIG_UNIX98_PTYS
if (tty->driver == ptm_driver) {
mutex_lock(&devpts_mutex);
if (tty->link->driver_data)
devpts_pty_kill(tty->link->driver_data);
mutex_unlock(&devpts_mutex);
}
#endif
tty_vhangup(tty->link);
}
}
/*
* The unthrottle routine is called by the line discipline to signal
* that it can receive more characters. For PTY's, the TTY_THROTTLED
* flag is always set, to force the line discipline to always call the
* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
* characters in the queue. This is necessary since each time this
* happens, we need to wake up any sleeping processes that could be
* (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
* for the pty buffer to be drained.
*/
static void pty_unthrottle(struct tty_struct *tty)
{
tty_wakeup(tty->link);
set_bit(TTY_THROTTLED, &tty->flags);
}
/**
* pty_write - write to a pty
* @tty: the tty we write from
* @buf: kernel buffer of data
* @count: bytes to write
*
* Our "hardware" write method. Data is coming from the ldisc which
* may be in a non sleeping state. We simply throw this at the other
* end of the link as if we were an IRQ handler receiving stuff for
* the other side of the pty/tty pair.
*/
static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
{
struct tty_struct *to = tty->link;
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->port, buf, c);
/* And shovel */
if (c)
tty_flip_buffer_push(to->port);
}
return c;
}
/**
* pty_write_room - write space
* @tty: tty we are writing from
*
* Report how many bytes the ldisc can send into the queue for
* the other device.
*/
static int pty_write_room(struct tty_struct *tty)
{
if (tty->stopped)
return 0;
return tty_buffer_space_avail(tty->link->port);
}
/**
* pty_chars_in_buffer - characters currently in our tx queue
* @tty: our tty
*
* Report how much we have in the transmit queue. As everything is
* instantly at the other end this is easy to implement.
*/
static int pty_chars_in_buffer(struct tty_struct *tty)
{
return 0;
}
/* Set the lock flag on a pty */
static int pty_set_lock(struct tty_struct *tty, int __user *arg)
{
int val;
if (get_user(val, arg))
return -EFAULT;
if (val)
set_bit(TTY_PTY_LOCK, &tty->flags);
else
clear_bit(TTY_PTY_LOCK, &tty->flags);
return 0;
}
static int pty_get_lock(struct tty_struct *tty, int __user *arg)
{
int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
return put_user(locked, arg);
}
/* Set the packet mode on a pty */
static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
{
int pktmode;
if (get_user(pktmode, arg))
return -EFAULT;
spin_lock_irq(&tty->ctrl_lock);
if (pktmode) {
if (!tty->packet) {
tty->link->ctrl_status = 0;
smp_mb();
tty->packet = 1;
}
} else
tty->packet = 0;
spin_unlock_irq(&tty->ctrl_lock);
return 0;
}
/* Get the packet mode of a pty */
static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
{
int pktmode = tty->packet;
return put_user(pktmode, arg);
}
/* Send a signal to the slave */
static int pty_signal(struct tty_struct *tty, int sig)
{
struct pid *pgrp;
if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
return -EINVAL;
if (tty->link) {
pgrp = tty_get_pgrp(tty->link);
if (pgrp)
kill_pgrp(pgrp, sig, 1);
put_pid(pgrp);
}
return 0;
}
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
if (!to)
return;
tty_buffer_flush(to, NULL);
if (to->packet) {
spin_lock_irq(&tty->ctrl_lock);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
wake_up_interruptible(&to->read_wait);
spin_unlock_irq(&tty->ctrl_lock);
}
}
static int pty_open(struct tty_struct *tty, struct file *filp)
{
if (!tty || !tty->link)
return -ENODEV;
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
goto out;
if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
goto out;
if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
goto out;
clear_bit(TTY_IO_ERROR, &tty->flags);
clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
set_bit(TTY_THROTTLED, &tty->flags);
return 0;
out:
set_bit(TTY_IO_ERROR, &tty->flags);
return -EIO;
}
static void pty_set_termios(struct tty_struct *tty,
struct ktermios *old_termios)
{
/* See if packet mode change of state. */
if (tty->link && tty->link->packet) {
int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
int old_flow = ((old_termios->c_iflag & IXON) &&
(old_termios->c_cc[VSTOP] == '\023') &&
(old_termios->c_cc[VSTART] == '\021'));
int new_flow = (I_IXON(tty) &&
STOP_CHAR(tty) == '\023' &&
START_CHAR(tty) == '\021');
if ((old_flow != new_flow) || extproc) {
spin_lock_irq(&tty->ctrl_lock);
if (old_flow != new_flow) {
tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
if (new_flow)
tty->ctrl_status |= TIOCPKT_DOSTOP;
else
tty->ctrl_status |= TIOCPKT_NOSTOP;
}
if (extproc)
tty->ctrl_status |= TIOCPKT_IOCTL;
spin_unlock_irq(&tty->ctrl_lock);
wake_up_interruptible(&tty->link->read_wait);
}
}
tty->termios.c_cflag &= ~(CSIZE | PARENB);
tty->termios.c_cflag |= (CS8 | CREAD);
}
/**
* pty_do_resize - resize event
* @tty: tty being resized
* @ws: window size being set.
*
* Update the termios variables and send the necessary signals to
* peform a terminal resize correctly
*/
static int pty_resize(struct tty_struct *tty, struct winsize *ws)
{
struct pid *pgrp, *rpgrp;
struct tty_struct *pty = tty->link;
/* For a PTY we need to lock the tty side */
mutex_lock(&tty->winsize_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Signal the foreground process group of both ptys */
pgrp = tty_get_pgrp(tty);
rpgrp = tty_get_pgrp(pty);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
if (rpgrp != pgrp && rpgrp)
kill_pgrp(rpgrp, SIGWINCH, 1);
put_pid(pgrp);
put_pid(rpgrp);
tty->winsize = *ws;
pty->winsize = *ws; /* Never used so will go away soon */
done:
mutex_unlock(&tty->winsize_mutex);
return 0;
}
/**
* pty_start - start() handler
* pty_stop - stop() handler
* @tty: tty being flow-controlled
*
* Propagates the TIOCPKT status to the master pty.
*
* NB: only the master pty can be in packet mode so only the slave
* needs start()/stop() handlers
*/
static void pty_start(struct tty_struct *tty)
{
unsigned long flags;
if (tty->link && tty->link->packet) {
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status &= ~TIOCPKT_STOP;
tty->ctrl_status |= TIOCPKT_START;
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
}
}
static void pty_stop(struct tty_struct *tty)
{
unsigned long flags;
if (tty->link && tty->link->packet) {
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status &= ~TIOCPKT_START;
tty->ctrl_status |= TIOCPKT_STOP;
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
}
}
/**
* pty_common_install - set up the pty pair
* @driver: the pty driver
* @tty: the tty being instantiated
* @legacy: true if this is BSD style
*
* Perform the initial set up for the tty/pty pair. Called from the
* tty layer when the port is first opened.
*
* Locking: the caller must hold the tty_mutex
*/
static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
bool legacy)
{
struct tty_struct *o_tty;
struct tty_port *ports[2];
int idx = tty->index;
int retval = -ENOMEM;
/* Opening the slave first has always returned -EIO */
if (driver->subtype != PTY_TYPE_MASTER)
return -EIO;
ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
if (!ports[0] || !ports[1])
goto err;
if (!try_module_get(driver->other->owner)) {
/* This cannot in fact currently happen */
goto err;
}
o_tty = alloc_tty_struct(driver->other, idx);
if (!o_tty)
goto err_put_module;
tty_set_lock_subclass(o_tty);
lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
if (legacy) {
/* We always use new tty termios data so we can do this
the easy way .. */
tty_init_termios(tty);
tty_init_termios(o_tty);
driver->other->ttys[idx] = o_tty;
driver->ttys[idx] = tty;
} else {
memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
tty->termios = driver->init_termios;
memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
o_tty->termios = driver->other->init_termios;
}
/*
* Everything allocated ... set up the o_tty structure.
*/
tty_driver_kref_get(driver->other);
/* Establish the links in both directions */
tty->link = o_tty;
o_tty->link = tty;
tty_port_init(ports[0]);
tty_port_init(ports[1]);
tty_buffer_set_limit(ports[0], 8192);
tty_buffer_set_limit(ports[1], 8192);
o_tty->port = ports[0];
tty->port = ports[1];
o_tty->port->itty = o_tty;
tty_buffer_set_lock_subclass(o_tty->port);
tty_driver_kref_get(driver);
tty->count++;
o_tty->count++;
return 0;
err_put_module:
module_put(driver->other->owner);
err:
kfree(ports[0]);
kfree(ports[1]);
return retval;
}
static void pty_cleanup(struct tty_struct *tty)
{
tty_port_put(tty->port);
}
/* Traditional BSD devices */
#ifdef CONFIG_LEGACY_PTYS
static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
{
return pty_common_install(driver, tty, true);
}
static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
{
struct tty_struct *pair = tty->link;
driver->ttys[tty->index] = NULL;
if (pair)
pair->driver->ttys[pair->index] = NULL;
}
static int pty_bsd_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int __user *) arg);
case TIOCGPTLCK: /* Get PT Lock status */
return pty_get_lock(tty, (int __user *)arg);
case TIOCPKT: /* Set PT packet mode */
return pty_set_pktmode(tty, (int __user *)arg);
case TIOCGPKT: /* Get PT packet mode */
return pty_get_pktmode(tty, (int __user *)arg);
case TIOCSIG: /* Send signal to other side of pty */
return pty_signal(tty, (int) arg);
case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
return -EINVAL;
}
return -ENOIOCTLCMD;
}
static long pty_bsd_compat_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
/*
* PTY ioctls don't require any special translation between 32-bit and
* 64-bit userspace, they are already compatible.
*/
return pty_bsd_ioctl(tty, cmd, arg);
}
static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
/*
* not really modular, but the easiest way to keep compat with existing
* bootargs behaviour is to continue using module_param here.
*/
module_param(legacy_count, int, 0);
/*
* The master side of a pty can do TIOCSPTLCK and thus
* has pty_bsd_ioctl.
*/
static const struct tty_operations master_pty_ops_bsd = {
.install = pty_install,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.ioctl = pty_bsd_ioctl,
.compat_ioctl = pty_bsd_compat_ioctl,
.cleanup = pty_cleanup,
.resize = pty_resize,
.remove = pty_remove
};
static const struct tty_operations slave_pty_ops_bsd = {
.install = pty_install,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.cleanup = pty_cleanup,
.resize = pty_resize,
.start = pty_start,
.stop = pty_stop,
.remove = pty_remove
};
static void __init legacy_pty_init(void)
{
struct tty_driver *pty_driver, *pty_slave_driver;
if (legacy_count <= 0)
return;
pty_driver = tty_alloc_driver(legacy_count,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pty_driver))
panic("Couldn't allocate pty driver");
pty_slave_driver = tty_alloc_driver(legacy_count,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pty_slave_driver))
panic("Couldn't allocate pty slave driver");
pty_driver->driver_name = "pty_master";
pty_driver->name = "pty";
pty_driver->major = PTY_MASTER_MAJOR;
pty_driver->minor_start = 0;
pty_driver->type = TTY_DRIVER_TYPE_PTY;
pty_driver->subtype = PTY_TYPE_MASTER;
pty_driver->init_termios = tty_std_termios;
pty_driver->init_termios.c_iflag = 0;
pty_driver->init_termios.c_oflag = 0;
pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pty_driver->init_termios.c_lflag = 0;
pty_driver->init_termios.c_ispeed = 38400;
pty_driver->init_termios.c_ospeed = 38400;
pty_driver->other = pty_slave_driver;
tty_set_operations(pty_driver, &master_pty_ops_bsd);
pty_slave_driver->driver_name = "pty_slave";
pty_slave_driver->name = "ttyp";
pty_slave_driver->major = PTY_SLAVE_MAJOR;
pty_slave_driver->minor_start = 0;
pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
pty_slave_driver->subtype = PTY_TYPE_SLAVE;
pty_slave_driver->init_termios = tty_std_termios;
pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pty_slave_driver->init_termios.c_ispeed = 38400;
pty_slave_driver->init_termios.c_ospeed = 38400;
pty_slave_driver->other = pty_driver;
tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
if (tty_register_driver(pty_driver))
panic("Couldn't register pty driver");
if (tty_register_driver(pty_slave_driver))
panic("Couldn't register pty slave driver");
}
#else
static inline void legacy_pty_init(void) { }
#endif
/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
static struct cdev ptmx_cdev;
/**
* ptm_open_peer - open the peer of a pty
* @master: the open struct file of the ptmx device node
* @tty: the master of the pty being opened
* @flags: the flags for open
*
* Provide a race free way for userspace to open the slave end of a pty
* (where they have the master fd and cannot access or trust the mount
* namespace /dev/pts was mounted inside).
*/
int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
{
int fd = -1;
struct file *filp;
int retval = -EINVAL;
struct path path;
if (tty->driver != ptm_driver)
return -EIO;
fd = get_unused_fd_flags(0);
if (fd < 0) {
retval = fd;
goto err;
}
/* Compute the slave's path */
path.mnt = devpts_mntget(master, tty->driver_data);
if (IS_ERR(path.mnt)) {
retval = PTR_ERR(path.mnt);
goto err_put;
}
path.dentry = tty->link->driver_data;
filp = dentry_open(&path, flags, current_cred());
mntput(path.mnt);
if (IS_ERR(filp)) {
retval = PTR_ERR(filp);
goto err_put;
}
fd_install(fd, filp);
return fd;
err_put:
put_unused_fd(fd);
err:
return retval;
}
static int pty_unix98_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int __user *)arg);
case TIOCGPTLCK: /* Get PT Lock status */
return pty_get_lock(tty, (int __user *)arg);
case TIOCPKT: /* Set PT packet mode */
return pty_set_pktmode(tty, (int __user *)arg);
case TIOCGPKT: /* Get PT packet mode */
return pty_get_pktmode(tty, (int __user *)arg);
case TIOCGPTN: /* Get PT Number */
return put_user(tty->index, (unsigned int __user *)arg);
case TIOCSIG: /* Send signal to other side of pty */
return pty_signal(tty, (int) arg);
}
return -ENOIOCTLCMD;
}
static long pty_unix98_compat_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
/*
* PTY ioctls don't require any special translation between 32-bit and
* 64-bit userspace, they are already compatible.
*/
return pty_unix98_ioctl(tty, cmd, arg);
}
/**
* ptm_unix98_lookup - find a pty master
* @driver: ptm driver
* @idx: tty index
*
* Look up a pty master device. Called under the tty_mutex for now.
* This provides our locking.
*/
static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
struct file *file, int idx)
{
/* Master must be open via /dev/ptmx */
return ERR_PTR(-EIO);
}
/**
* pts_unix98_lookup - find a pty slave
* @driver: pts driver
* @idx: tty index
*
* Look up a pty master device. Called under the tty_mutex for now.
* This provides our locking for the tty pointer.
*/
static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
struct file *file, int idx)
{
struct tty_struct *tty;
mutex_lock(&devpts_mutex);
tty = devpts_get_priv(file->f_path.dentry);
mutex_unlock(&devpts_mutex);
/* Master must be open before slave */
if (!tty)
return ERR_PTR(-EIO);
return tty;
}
static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
{
return pty_common_install(driver, tty, false);
}
/* this is called once with whichever end is closed last */
static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
{
struct pts_fs_info *fsi;
if (tty->driver->subtype == PTY_TYPE_MASTER)
fsi = tty->driver_data;
else
fsi = tty->link->driver_data;
if (fsi) {
devpts_kill_index(fsi, tty->index);
devpts_release(fsi);
}
}
static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
{
seq_printf(m, "tty-index:\t%d\n", tty->index);
}
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
.install = pty_unix98_install,
.remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.ioctl = pty_unix98_ioctl,
.compat_ioctl = pty_unix98_compat_ioctl,
.resize = pty_resize,
.cleanup = pty_cleanup,
.show_fdinfo = pty_show_fdinfo,
};
static const struct tty_operations pty_unix98_ops = {
.lookup = pts_unix98_lookup,
.install = pty_unix98_install,
.remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.start = pty_start,
.stop = pty_stop,
.cleanup = pty_cleanup,
};
/**
* ptmx_open - open a unix 98 pty master
* @inode: inode of device file
* @filp: file pointer to tty
*
* Allocate a unix98 pty master device from the ptmx driver.
*
* Locking: tty_mutex protects the init_dev work. tty->count should
* protect the rest.
* allocated_ptys_lock handles the list of free pty numbers
*/
static int ptmx_open(struct inode *inode, struct file *filp)
{
struct pts_fs_info *fsi;
struct tty_struct *tty;
struct dentry *dentry;
int retval;
int index;
nonseekable_open(inode, filp);
/* We refuse fsnotify events on ptmx, since it's a shared resource */
filp->f_mode |= FMODE_NONOTIFY;
retval = tty_alloc_file(filp);
if (retval)
return retval;
fsi = devpts_acquire(filp);
if (IS_ERR(fsi)) {
retval = PTR_ERR(fsi);
goto out_free_file;
}
/* find a device that is not in use. */
mutex_lock(&devpts_mutex);
index = devpts_new_index(fsi);
mutex_unlock(&devpts_mutex);
retval = index;
if (index < 0)
goto out_put_fsi;
mutex_lock(&tty_mutex);
tty = tty_init_dev(ptm_driver, index);
/* The tty returned here is locked so we can safely
drop the mutex */
mutex_unlock(&tty_mutex);
retval = PTR_ERR(tty);
if (IS_ERR(tty))
goto out;
/*
* From here on out, the tty is "live", and the index and
* fsi will be killed/put by the tty_release()
*/
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
tty->driver_data = fsi;
tty_add_file(tty, filp);
dentry = devpts_pty_new(fsi, index, tty->link);
if (IS_ERR(dentry)) {
retval = PTR_ERR(dentry);
goto err_release;
}
tty->link->driver_data = dentry;
retval = ptm_driver->ops->open(tty, filp);
if (retval)
goto err_release;
tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
tty_unlock(tty);
return 0;
err_release:
tty_unlock(tty);
// This will also put-ref the fsi
tty_release(inode, filp);
return retval;
out:
devpts_kill_index(fsi, index);
out_put_fsi:
devpts_release(fsi);
out_free_file:
tty_free_file(filp);
return retval;
}
static struct file_operations ptmx_fops __ro_after_init;
static void __init unix98_pty_init(void)
{
ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV |
TTY_DRIVER_DEVPTS_MEM |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(ptm_driver))
panic("Couldn't allocate Unix98 ptm driver");
pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV |
TTY_DRIVER_DEVPTS_MEM |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pts_driver))
panic("Couldn't allocate Unix98 pts driver");
ptm_driver->driver_name = "pty_master";
ptm_driver->name = "ptm";
ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
ptm_driver->minor_start = 0;
ptm_driver->type = TTY_DRIVER_TYPE_PTY;
ptm_driver->subtype = PTY_TYPE_MASTER;
ptm_driver->init_termios = tty_std_termios;
ptm_driver->init_termios.c_iflag = 0;
ptm_driver->init_termios.c_oflag = 0;
ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
ptm_driver->init_termios.c_lflag = 0;
ptm_driver->init_termios.c_ispeed = 38400;
ptm_driver->init_termios.c_ospeed = 38400;
ptm_driver->other = pts_driver;
tty_set_operations(ptm_driver, &ptm_unix98_ops);
pts_driver->driver_name = "pty_slave";
pts_driver->name = "pts";
pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
pts_driver->minor_start = 0;
pts_driver->type = TTY_DRIVER_TYPE_PTY;
pts_driver->subtype = PTY_TYPE_SLAVE;
pts_driver->init_termios = tty_std_termios;
pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pts_driver->init_termios.c_ispeed = 38400;
pts_driver->init_termios.c_ospeed = 38400;
pts_driver->other = ptm_driver;
tty_set_operations(pts_driver, &pty_unix98_ops);
if (tty_register_driver(ptm_driver))
panic("Couldn't register Unix98 ptm driver");
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");
/* Now create the /dev/ptmx special device */
tty_default_fops(&ptmx_fops);
ptmx_fops.open = ptmx_open;
cdev_init(&ptmx_cdev, &ptmx_fops);
if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
panic("Couldn't register /dev/ptmx driver");
device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
}
#else
static inline void unix98_pty_init(void) { }
#endif
static int __init pty_init(void)
{
legacy_pty_init();
unix98_pty_init();
return 0;
}
device_initcall(pty_init);
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