Re: [ 03/42] TTY: fix atime/mtime regression

From: Wolfram Gloger
Date: Tue Apr 30 2013 - 08:02:23 EST


>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.

Sorry if I miss something, but isn't this an issue that should be very
obviously fixed in user space? Only user space knows whether the
atime/mtime updates on a device are security-sensitive or not.

The sshd process and/or the login process could easily perform randomly
timed, dummy utime() calls on the tty around and within the password
typing, making this attack unfeasible. I faintly remember sshd _already
does this_ for the network packets anyway by exchanging dummy packets.

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