Revert "TTY: fix atime/mtime regression"

This reverts commit 25694bc065359ff4456b4197a04a4d9f6682e244.
Revert "TTY: do not update atime/mtime on read/write"

This reverts commit c5d84294188f53d72817de6c1908f753da055953.
Revert "Add permission checking for binder IPC."

This reverts commit 37f421a13815d0543dcd46ea1435cdc9309653c9.
TTY: do not update atime/mtime on read/write

commit b0de59b5733d18b0d1974a060860a8b5c1b36a2e upstream.

On http://vladz.devzero.fr/013_ptmx-timing.php, we can see how to find
out length of a password using timestamps of /dev/ptmx. It is
documented in "Timing Analysis of Keystrokes and Timing Attacks on
SSH". To avoid that problem, do not update time when reading
from/writing to a TTY.

I am afraid of regressions as this is a behavior we have since 0.97
and apps may expect the time to be current, e.g. for monitoring
whether there was a change on the TTY. Now, there is no change. So
this would better have a lot of testing before it goes upstream.

References: CVE-2013-0160

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	drivers/tty/tty_io.c
TTY: fix atime/mtime regression

commit 37b7f3c76595e23257f61bd80b223de8658617ee upstream.

In commit b0de59b5733d ("TTY: do not update atime/mtime on read/write")
we removed timestamps from tty inodes to fix a security issue and waited
if something breaks.  Well, 'w', the utility to find out logged users
and their inactivity time broke.  It shows that users are inactive since
the time they logged in.

To revert to the old behaviour while still preventing attackers to
guess the password length, we update the timestamps in one-minute
intervals by this patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	drivers/tty/tty_io.c
version 0.3.21 exp