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/pty.c b/drivers/tty/pty.c
index d8653ab..03147fa 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -515,10 +515,8 @@
static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
struct inode *ptm_inode, int idx)
{
- struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
- if (tty)
- tty = tty->link;
- return tty;
+ /* Master must be open via /dev/ptmx */
+ return ERR_PTR(-EIO);
}
/**
@@ -677,7 +675,7 @@
mutex_lock(&tty_mutex);
tty_lock();
- tty = tty_init_dev(ptm_driver, index, 1);
+ tty = tty_init_dev(ptm_driver, index);
mutex_unlock(&tty_mutex);
if (IS_ERR(tty)) {