tty: cleanup prohibition of direct opening for unix98 pty master
cleanup hack added in v2.6.27-3203-g15582d3
comment from that patch:
: pty: If the administrator creates a device for a ptmx slave we should not error
:
: The open path for ptmx slaves is via the ptmx device. Opening them any
: other way is not allowed. Vegard Nossum found that previously this was not
: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
:
: Signed-off-by: Alan Cox <alan@redhat.com>
: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
devpts_get_tty() returns non-null only for inodes on devpts, but there is no
inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
Thus we can completely forbid lookup for master-devices and eliminate that hack in
tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e41b9bb..fbcc140 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1365,7 +1365,6 @@
* @driver: tty driver we are opening a device on
* @idx: device index
* @ret_tty: returned tty structure
- * @first_ok: ok to open a new device (used by ptmx)
*
* Prepare a tty device. This may not be a "new" clean device but
* could also be an active device. The pty drivers require special
@@ -1385,18 +1384,11 @@
* relaxed for the (most common) case of reopening a tty.
*/
-struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
- int first_ok)
+struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
int retval;
- /* Check if pty master is being opened multiple times */
- if (driver->subtype == PTY_TYPE_MASTER &&
- (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
- return ERR_PTR(-EIO);
- }
-
/*
* First time open is complex, especially for PTY devices.
* This code guarantees that either everything succeeds and the
@@ -1950,7 +1942,7 @@
if (retval)
tty = ERR_PTR(retval);
} else
- tty = tty_init_dev(driver, index, 0);
+ tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex);
if (driver)