diff options
Diffstat (limited to 'drivers/char/tty_io.c')
| -rw-r--r-- | drivers/char/tty_io.c | 104 |
1 files changed, 53 insertions, 51 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index bb0d9199e99..333741770f1 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -129,6 +129,7 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ /* Semaphore to protect creating and releasing a tty. This is shared with vt.c for deeply disgusting hack reasons */ DEFINE_MUTEX(tty_mutex); +EXPORT_SYMBOL(tty_mutex); #ifdef CONFIG_UNIX98_PTYS extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */ @@ -160,17 +161,11 @@ static void release_mem(struct tty_struct *tty, int idx); * been initialized in any way but has been zeroed * * Locking: none - * FIXME: use kzalloc */ static struct tty_struct *alloc_tty_struct(void) { - struct tty_struct *tty; - - tty = kmalloc(sizeof(struct tty_struct), GFP_KERNEL); - if (tty) - memset(tty, 0, sizeof(struct tty_struct)); - return tty; + return kzalloc(sizeof(struct tty_struct), GFP_KERNEL); } static void tty_buffer_free_all(struct tty_struct *); @@ -483,10 +478,9 @@ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars, tb->used += space; copied += space; chars += space; - } - /* There is a small chance that we need to split the data over - several buffers. If this is the case we must loop */ - while (unlikely(size > copied)); + /* There is a small chance that we need to split the data over + several buffers. If this is the case we must loop */ + } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string); @@ -521,10 +515,9 @@ int tty_insert_flip_string_flags(struct tty_struct *tty, copied += space; chars += space; flags += space; - } - /* There is a small chance that we need to split the data over - several buffers. If this is the case we must loop */ - while (unlikely(size > copied)); + /* There is a small chance that we need to split the data over + several buffers. If this is the case we must loop */ + } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string_flags); @@ -626,9 +619,9 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); static void tty_set_termios_ldisc(struct tty_struct *tty, int num) { - down(&tty->termios_sem); + mutex_lock(&tty->termios_mutex); tty->termios->c_line = num; - up(&tty->termios_sem); + mutex_unlock(&tty->termios_mutex); } /* @@ -1346,9 +1339,9 @@ static void do_tty_hangup(void *data) */ if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) { - down(&tty->termios_sem); + mutex_lock(&tty->termios_mutex); *tty->termios = tty->driver->init_termios; - up(&tty->termios_sem); + mutex_unlock(&tty->termios_mutex); } /* Defer ldisc switch */ @@ -2072,8 +2065,9 @@ fail_no_mem: /* call the tty release_mem routine to clean out this slot */ release_mem_out: - printk(KERN_INFO "init_dev: ldisc open failed, " - "clearing slot %d\n", idx); + if (printk_ratelimit()) + printk(KERN_INFO "init_dev: ldisc open failed, " + "clearing slot %d\n", idx); release_mem(tty, idx); goto end_init; } @@ -2726,6 +2720,8 @@ static int tty_fasync(int fd, struct file * filp, int on) * Locking: * Called functions take tty_ldisc_lock * current->signal->tty check is safe without locks + * + * FIXME: may race normal receive processing */ static int tiocsti(struct tty_struct *tty, char __user *p) @@ -2748,18 +2744,21 @@ static int tiocsti(struct tty_struct *tty, char __user *p) * @tty; tty * @arg: user buffer for result * - * Copies the kernel idea of the window size into the user buffer. No - * locking is done. + * Copies the kernel idea of the window size into the user buffer. * - * FIXME: Returning random values racing a window size set is wrong - * should lock here against that + * Locking: tty->termios_sem is taken to ensure the winsize data + * is consistent. */ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) { - if (copy_to_user(arg, &tty->winsize, sizeof(*arg))) - return -EFAULT; - return 0; + int err; + + mutex_lock(&tty->termios_mutex); + err = copy_to_user(arg, &tty->winsize, sizeof(*arg)); + mutex_unlock(&tty->termios_mutex); + + return err ? -EFAULT: 0; } /** @@ -2772,12 +2771,11 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) * actually has driver level meaning and triggers a VC resize. * * Locking: - * The console_sem is used to ensure we do not try and resize - * the console twice at once. - * FIXME: Two racing size sets may leave the console and kernel - * parameters disagreeing. Is this exploitable ? - * FIXME: Random values racing a window size get is wrong - * should lock here against that + * Called function use the console_sem is used to ensure we do + * not try and resize the console twice at once. + * The tty->termios_sem is used to ensure we don't double + * resize and get confused. Lock order - tty->termios.sem before + * console sem */ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, @@ -2787,17 +2785,18 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, if (copy_from_user(&tmp_ws, arg, sizeof(*arg))) return -EFAULT; + + mutex_lock(&tty->termios_mutex); if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg))) - return 0; + goto done; + #ifdef CONFIG_VT if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) { - int rc; - - acquire_console_sem(); - rc = vc_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row); - release_console_sem(); - if (rc) - return -ENXIO; + if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col, + tmp_ws.ws_row)) { + mutex_unlock(&tty->termios_mutex); + return -ENXIO; + } } #endif if (tty->pgrp > 0) @@ -2806,6 +2805,8 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, kill_pg(real_tty->pgrp, SIGWINCH, 1); tty->winsize = tmp_ws; real_tty->winsize = tmp_ws; +done: + mutex_unlock(&tty->termios_mutex); return 0; } @@ -2880,9 +2881,7 @@ static int fionbio(struct file *file, int __user *p) * Locking: * Takes tasklist lock internally to walk sessions * Takes task_lock() when updating signal->tty - * - * FIXME: tty_mutex is needed to protect signal->tty references. - * FIXME: why task_lock on the signal->tty reference ?? + * Takes tty_mutex() to protect tty instance * */ @@ -2917,9 +2916,11 @@ static int tiocsctty(struct tty_struct *tty, int arg) } else return -EPERM; } + mutex_lock(&tty_mutex); task_lock(current); current->signal->tty = tty; task_unlock(current); + mutex_unlock(&tty_mutex); current->signal->tty_old_pgrp = 0; tty->session = current->signal->session; tty->pgrp = process_group(current); @@ -2959,8 +2960,6 @@ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t * permitted where the tty session is our session. * * Locking: None - * - * FIXME: current->signal->tty referencing is unsafe. */ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) @@ -3039,19 +3038,20 @@ static int tiocsetd(struct tty_struct *tty, int __user *p) * timed break functionality. * * Locking: - * None + * atomic_write_lock serializes * - * FIXME: - * What if two overlap */ static int send_break(struct tty_struct *tty, unsigned int duration) { + if (mutex_lock_interruptible(&tty->atomic_write_lock)) + return -EINTR; tty->driver->break_ctl(tty, -1); if (!signal_pending(current)) { msleep_interruptible(duration); } tty->driver->break_ctl(tty, 0); + mutex_unlock(&tty->atomic_write_lock); if (signal_pending(current)) return -EINTR; return 0; @@ -3144,6 +3144,8 @@ int tty_ioctl(struct inode * inode, struct file * file, if (tty_paranoia_check(tty, inode, "tty_ioctl")) return -EINVAL; + /* CHECKME: is this safe as one end closes ? */ + real_tty = tty; if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) @@ -3580,7 +3582,7 @@ static void initialize_tty_struct(struct tty_struct *tty) tty_buffer_init(tty); INIT_WORK(&tty->buf.work, flush_to_ldisc, tty); init_MUTEX(&tty->buf.pty_sem); - init_MUTEX(&tty->termios_sem); + mutex_init(&tty->termios_mutex); init_waitqueue_head(&tty->write_wait); init_waitqueue_head(&tty->read_wait); INIT_WORK(&tty->hangup_work, do_tty_hangup, tty); |