diff options
Diffstat (limited to 'drivers/tty/pty.c')
| -rw-r--r-- | drivers/tty/pty.c | 72 |
1 files changed, 34 insertions, 38 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 284749fb0f6b..26dcb3b60fb9 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -69,13 +69,8 @@ static void pty_close(struct tty_struct *tty, struct file *filp) #ifdef CONFIG_UNIX98_PTYS if (tty->driver == ptm_driver) { mutex_lock(&devpts_mutex); - if (tty->link->driver_data) { - struct path *path = tty->link->driver_data; - - devpts_pty_kill(path->dentry); - path_put(path); - kfree(path); - } + if (tty->link->driver_data) + devpts_pty_kill(tty->link->driver_data); mutex_unlock(&devpts_mutex); } #endif @@ -607,25 +602,24 @@ static inline void legacy_pty_init(void) { } static struct cdev ptmx_cdev; /** - * pty_open_peer - open the peer of a pty - * @tty: the peer of the pty being opened + * 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 * - * Open the cached dentry in tty->link, providing a safe way for userspace - * to get 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). + * 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). */ -static struct file *pty_open_peer(struct tty_struct *tty, int flags) -{ - if (tty->driver->subtype != PTY_TYPE_MASTER) - return ERR_PTR(-EIO); - return dentry_open(tty->link->driver_data, flags, current_cred()); -} - -static int pty_get_peer(struct tty_struct *tty, int flags) +int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags) { int fd = -1; - struct file *filp = NULL; + 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) { @@ -633,7 +627,16 @@ static int pty_get_peer(struct tty_struct *tty, int flags) goto err; } - filp = pty_open_peer(tty, flags); + /* 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; @@ -662,8 +665,6 @@ static int pty_unix98_ioctl(struct tty_struct *tty, return pty_get_pktmode(tty, (int __user *)arg); case TIOCGPTN: /* Get PT Number */ return put_user(tty->index, (unsigned int __user *)arg); - case TIOCGPTPEER: /* Open the other end */ - return pty_get_peer(tty, (int) arg); case TIOCSIG: /* Send signal to other side of pty */ return pty_signal(tty, (int) arg); } @@ -741,6 +742,11 @@ static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) } } +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, @@ -755,7 +761,8 @@ static const struct tty_operations ptm_unix98_ops = { .ioctl = pty_unix98_ioctl, .compat_ioctl = pty_unix98_compat_ioctl, .resize = pty_resize, - .cleanup = pty_cleanup + .cleanup = pty_cleanup, + .show_fdinfo = pty_show_fdinfo, }; static const struct tty_operations pty_unix98_ops = { @@ -791,7 +798,6 @@ static int ptmx_open(struct inode *inode, struct file *filp) { struct pts_fs_info *fsi; struct tty_struct *tty; - struct path *pts_path; struct dentry *dentry; int retval; int index; @@ -845,26 +851,16 @@ static int ptmx_open(struct inode *inode, struct file *filp) retval = PTR_ERR(dentry); goto err_release; } - /* We need to cache a fake path for TIOCGPTPEER. */ - pts_path = kmalloc(sizeof(struct path), GFP_KERNEL); - if (!pts_path) - goto err_release; - pts_path->mnt = filp->f_path.mnt; - pts_path->dentry = dentry; - path_get(pts_path); - tty->link->driver_data = pts_path; + tty->link->driver_data = dentry; retval = ptm_driver->ops->open(tty, filp); if (retval) - goto err_path_put; + goto err_release; tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); tty_unlock(tty); return 0; -err_path_put: - path_put(pts_path); - kfree(pts_path); err_release: tty_unlock(tty); // This will also put-ref the fsi |