linux-kernel - Re: [kernel-hardening] Re: [PATCH 1/4] added SECURITY_TIOCSTI

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Message-ID: <CAGXu5j+mP784rGqx1CWOOXM=AhAN7EegRZxO_=OG0y6k0hQs+g@mail.gmail.com>
Date:   Tue, 18 Apr 2017 08:49:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Greg KH <gregkh@...uxfoundation.org>, Matt Brown <matt@...tt.com>,
        James Morris <jmorris@...ei.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [kernel-hardening] Re: [PATCH 1/4] added SECURITY_TIOCSTI_RESTRICT
 kernel config

On Tue, Apr 18, 2017 at 6:40 AM, Alan Cox <gnomes@...rguk.ukuu.org.uk> wrote:
>> Since tty sessions are usually separated by different users, how would
>> they have the same one and yet need something like this?
>>
>> Also, why not put this in the tty config section?
>
> The normal attack use case people argue about is a rogue process on the
> users machine sitting there waiting until the user has logged in to a
> remote machine and is idle and then doing stuff.

It's still a threat, though, and adding this with default n to allow
the more paranoid builders a chance to mitigate it seems reasonable to
me.

> Attackers of course don't bother doing that because it's easier to get
> the user to run a different ssh client instead.

Attackers will always take the easiest route, so we have to keep
killing the low hanging fruit.

-Kees

-- 
Kees Cook
Pixel Security