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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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35834ca1e4
Instead of having a bunch of ifdefs in sysctl.c move all of the pty sysctl logic into drivers/char/pty.c As well as cleaning up the logic this prevents sysctl_check_table from complaining that the root table has a NULL data pointer on something with generic methods. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
441 lines
12 KiB
C
441 lines
12 KiB
C
/*
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* linux/drivers/char/pty.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* Added support for a Unix98-style ptmx device.
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* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
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* Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
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* waiting writers -- Sapan Bhatia <sapan@corewars.org>
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*
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*
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*/
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#include <linux/module.h> /* For EXPORT_SYMBOL */
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#include <linux/errno.h>
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#include <linux/interrupt.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/fcntl.h>
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#include <linux/string.h>
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#include <linux/major.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/sysctl.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <linux/bitops.h>
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#include <linux/devpts_fs.h>
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/* These are global because they are accessed in tty_io.c */
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#ifdef CONFIG_UNIX98_PTYS
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struct tty_driver *ptm_driver;
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static struct tty_driver *pts_driver;
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#endif
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static void pty_close(struct tty_struct * tty, struct file * filp)
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{
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if (!tty)
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return;
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if (tty->driver->subtype == PTY_TYPE_MASTER) {
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if (tty->count > 1)
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printk("master pty_close: count = %d!!\n", tty->count);
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} else {
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if (tty->count > 2)
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return;
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}
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wake_up_interruptible(&tty->read_wait);
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wake_up_interruptible(&tty->write_wait);
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tty->packet = 0;
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if (!tty->link)
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return;
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tty->link->packet = 0;
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set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
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wake_up_interruptible(&tty->link->read_wait);
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wake_up_interruptible(&tty->link->write_wait);
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if (tty->driver->subtype == PTY_TYPE_MASTER) {
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set_bit(TTY_OTHER_CLOSED, &tty->flags);
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#ifdef CONFIG_UNIX98_PTYS
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if (tty->driver == ptm_driver)
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devpts_pty_kill(tty->index);
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#endif
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tty_vhangup(tty->link);
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}
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}
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/*
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* The unthrottle routine is called by the line discipline to signal
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* that it can receive more characters. For PTY's, the TTY_THROTTLED
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* flag is always set, to force the line discipline to always call the
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* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
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* characters in the queue. This is necessary since each time this
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* happens, we need to wake up any sleeping processes that could be
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* (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
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* for the pty buffer to be drained.
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*/
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static void pty_unthrottle(struct tty_struct * tty)
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{
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struct tty_struct *o_tty = tty->link;
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if (!o_tty)
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return;
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tty_wakeup(o_tty);
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set_bit(TTY_THROTTLED, &tty->flags);
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}
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/*
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* WSH 05/24/97: modified to
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* (1) use space in tty->flip instead of a shared temp buffer
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* The flip buffers aren't being used for a pty, so there's lots
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* of space available. The buffer is protected by a per-pty
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* semaphore that should almost never come under contention.
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* (2) avoid redundant copying for cases where count >> receive_room
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* N.B. Calls from user space may now return an error code instead of
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* a count.
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*
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* FIXME: Our pty_write method is called with our ldisc lock held but
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* not our partners. We can't just take the other one blindly without
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* risking deadlocks.
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*/
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static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
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{
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struct tty_struct *to = tty->link;
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int c;
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if (!to || tty->stopped)
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return 0;
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c = to->receive_room;
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if (c > count)
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c = count;
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to->ldisc.receive_buf(to, buf, NULL, c);
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return c;
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}
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static int pty_write_room(struct tty_struct *tty)
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{
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struct tty_struct *to = tty->link;
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if (!to || tty->stopped)
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return 0;
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return to->receive_room;
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}
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/*
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* WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
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* The chars_in_buffer() value is used by the ldisc select() function
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* to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
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* The pty driver chars_in_buffer() Master/Slave must behave differently:
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*
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* The Master side needs to allow typed-ahead commands to accumulate
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* while being canonicalized, so we report "our buffer" as empty until
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* some threshold is reached, and then report the count. (Any count >
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* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
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* the count returned must be 0 if no canonical data is available to be
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* read. (The N_TTY ldisc.chars_in_buffer now knows this.)
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*
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* The Slave side passes all characters in raw mode to the Master side's
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* buffer where they can be read immediately, so in this case we can
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* return the true count in the buffer.
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*/
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static int pty_chars_in_buffer(struct tty_struct *tty)
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{
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struct tty_struct *to = tty->link;
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int count;
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/* We should get the line discipline lock for "tty->link" */
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if (!to || !to->ldisc.chars_in_buffer)
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return 0;
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/* The ldisc must report 0 if no characters available to be read */
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count = to->ldisc.chars_in_buffer(to);
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if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
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/* Master side driver ... if the other side's read buffer is less than
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* half full, return 0 to allow writers to proceed; otherwise return
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* the count. This leaves a comfortable margin to avoid overflow,
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* and still allows half a buffer's worth of typed-ahead commands.
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*/
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return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
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}
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/* Set the lock flag on a pty */
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static int pty_set_lock(struct tty_struct *tty, int __user * arg)
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{
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int val;
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if (get_user(val,arg))
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return -EFAULT;
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if (val)
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set_bit(TTY_PTY_LOCK, &tty->flags);
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else
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clear_bit(TTY_PTY_LOCK, &tty->flags);
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return 0;
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}
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static void pty_flush_buffer(struct tty_struct *tty)
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{
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struct tty_struct *to = tty->link;
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if (!to)
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return;
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if (to->ldisc.flush_buffer)
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to->ldisc.flush_buffer(to);
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if (to->packet) {
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tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
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wake_up_interruptible(&to->read_wait);
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}
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}
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static int pty_open(struct tty_struct *tty, struct file * filp)
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{
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int retval = -ENODEV;
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if (!tty || !tty->link)
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goto out;
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retval = -EIO;
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if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
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goto out;
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if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
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goto out;
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if (tty->link->count != 1)
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goto out;
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clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
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set_bit(TTY_THROTTLED, &tty->flags);
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set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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retval = 0;
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out:
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return retval;
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}
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static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
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{
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tty->termios->c_cflag &= ~(CSIZE | PARENB);
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tty->termios->c_cflag |= (CS8 | CREAD);
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}
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static const struct tty_operations pty_ops = {
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.open = pty_open,
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.close = pty_close,
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.write = pty_write,
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.write_room = pty_write_room,
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.flush_buffer = pty_flush_buffer,
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.chars_in_buffer = pty_chars_in_buffer,
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.unthrottle = pty_unthrottle,
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.set_termios = pty_set_termios,
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};
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/* Traditional BSD devices */
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#ifdef CONFIG_LEGACY_PTYS
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static struct tty_driver *pty_driver, *pty_slave_driver;
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static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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switch (cmd) {
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case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
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return pty_set_lock(tty, (int __user *) arg);
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}
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return -ENOIOCTLCMD;
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}
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static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
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module_param(legacy_count, int, 0);
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static void __init legacy_pty_init(void)
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{
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if (legacy_count <= 0)
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return;
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pty_driver = alloc_tty_driver(legacy_count);
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if (!pty_driver)
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panic("Couldn't allocate pty driver");
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pty_slave_driver = alloc_tty_driver(legacy_count);
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if (!pty_slave_driver)
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panic("Couldn't allocate pty slave driver");
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pty_driver->owner = THIS_MODULE;
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pty_driver->driver_name = "pty_master";
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pty_driver->name = "pty";
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pty_driver->major = PTY_MASTER_MAJOR;
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pty_driver->minor_start = 0;
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pty_driver->type = TTY_DRIVER_TYPE_PTY;
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pty_driver->subtype = PTY_TYPE_MASTER;
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pty_driver->init_termios = tty_std_termios;
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pty_driver->init_termios.c_iflag = 0;
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pty_driver->init_termios.c_oflag = 0;
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pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
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pty_driver->init_termios.c_lflag = 0;
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pty_driver->init_termios.c_ispeed = 38400;
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pty_driver->init_termios.c_ospeed = 38400;
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pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
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pty_driver->other = pty_slave_driver;
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tty_set_operations(pty_driver, &pty_ops);
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pty_driver->ioctl = pty_bsd_ioctl;
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pty_slave_driver->owner = THIS_MODULE;
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pty_slave_driver->driver_name = "pty_slave";
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pty_slave_driver->name = "ttyp";
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pty_slave_driver->major = PTY_SLAVE_MAJOR;
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pty_slave_driver->minor_start = 0;
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pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
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pty_slave_driver->subtype = PTY_TYPE_SLAVE;
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pty_slave_driver->init_termios = tty_std_termios;
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pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
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pty_slave_driver->init_termios.c_ispeed = 38400;
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pty_slave_driver->init_termios.c_ospeed = 38400;
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pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
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TTY_DRIVER_REAL_RAW;
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pty_slave_driver->other = pty_driver;
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tty_set_operations(pty_slave_driver, &pty_ops);
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if (tty_register_driver(pty_driver))
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panic("Couldn't register pty driver");
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if (tty_register_driver(pty_slave_driver))
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panic("Couldn't register pty slave driver");
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}
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#else
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static inline void legacy_pty_init(void) { }
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#endif
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/* Unix98 devices */
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#ifdef CONFIG_UNIX98_PTYS
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/*
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* sysctl support for setting limits on the number of Unix98 ptys allocated.
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* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
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*/
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int pty_limit = NR_UNIX98_PTY_DEFAULT;
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static int pty_limit_min = 0;
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static int pty_limit_max = NR_UNIX98_PTY_MAX;
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static struct ctl_table pty_table[] = {
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{
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.ctl_name = PTY_MAX,
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.procname = "max",
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.maxlen = sizeof(int),
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.mode = 0644,
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.data = &pty_limit,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &pty_limit_min,
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.extra2 = &pty_limit_max,
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}, {
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.ctl_name = PTY_NR,
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.procname = "nr",
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.maxlen = sizeof(int),
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.mode = 0444,
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.proc_handler = &proc_dointvec,
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}, {
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.ctl_name = 0
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}
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};
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static struct ctl_table pty_kern_table[] = {
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{
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.ctl_name = KERN_PTY,
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.procname = "pty",
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.mode = 0555,
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.child = pty_table,
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},
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{}
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};
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static struct ctl_table pty_root_table[] = {
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{
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.ctl_name = CTL_KERN,
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.procname = "kernel",
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.mode = 0555,
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.child = pty_kern_table,
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},
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{}
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};
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static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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switch (cmd) {
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case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
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return pty_set_lock(tty, (int __user *)arg);
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case TIOCGPTN: /* Get PT Number */
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return put_user(tty->index, (unsigned int __user *)arg);
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}
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return -ENOIOCTLCMD;
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}
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static void __init unix98_pty_init(void)
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{
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ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
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if (!ptm_driver)
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panic("Couldn't allocate Unix98 ptm driver");
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pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
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if (!pts_driver)
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panic("Couldn't allocate Unix98 pts driver");
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ptm_driver->owner = THIS_MODULE;
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ptm_driver->driver_name = "pty_master";
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ptm_driver->name = "ptm";
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ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
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ptm_driver->minor_start = 0;
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ptm_driver->type = TTY_DRIVER_TYPE_PTY;
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ptm_driver->subtype = PTY_TYPE_MASTER;
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ptm_driver->init_termios = tty_std_termios;
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ptm_driver->init_termios.c_iflag = 0;
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ptm_driver->init_termios.c_oflag = 0;
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ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
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ptm_driver->init_termios.c_lflag = 0;
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ptm_driver->init_termios.c_ispeed = 38400;
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ptm_driver->init_termios.c_ospeed = 38400;
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ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
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TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
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ptm_driver->other = pts_driver;
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tty_set_operations(ptm_driver, &pty_ops);
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ptm_driver->ioctl = pty_unix98_ioctl;
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pts_driver->owner = THIS_MODULE;
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pts_driver->driver_name = "pty_slave";
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pts_driver->name = "pts";
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pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
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pts_driver->minor_start = 0;
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pts_driver->type = TTY_DRIVER_TYPE_PTY;
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pts_driver->subtype = PTY_TYPE_SLAVE;
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pts_driver->init_termios = tty_std_termios;
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pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
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pts_driver->init_termios.c_ispeed = 38400;
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pts_driver->init_termios.c_ospeed = 38400;
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pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
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TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
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pts_driver->other = ptm_driver;
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tty_set_operations(pts_driver, &pty_ops);
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if (tty_register_driver(ptm_driver))
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panic("Couldn't register Unix98 ptm driver");
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if (tty_register_driver(pts_driver))
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panic("Couldn't register Unix98 pts driver");
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pty_table[1].data = &ptm_driver->refcount;
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register_sysctl_table(pty_root_table);
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}
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#else
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static inline void unix98_pty_init(void) { }
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#endif
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static int __init pty_init(void)
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{
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legacy_pty_init();
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unix98_pty_init();
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return 0;
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}
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module_init(pty_init);
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