To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Vegard Nossum" <vegard.nossum@gmail.com>,
       "Alexey Dobriyan" <adobriyan@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] sysrq-j: emergency shell
From: Andi Kleen <andi@firstfloor.org>
References: <20081121235159.GA15861@localhost.localdomain>
	<20081122172702.GB2748@x200.localdomain>
	<20081122190719.3ef24df6@lxorguk.ukuu.org.uk>
	<19f34abd0811221448p34770633keb5ea97f8e9bf62d@mail.gmail.com>
	<20081123001035.64234982@lxorguk.ukuu.org.uk>
Date: Sun, 23 Nov 2008 20:29:49 +0100
In-Reply-To: <20081123001035.64234982@lxorguk.ukuu.org.uk> (Alan Cox's message of "Sun, 23 Nov 2008 00:10:35 +0000")
Message-ID: <871vx2jl5e.fsf@basil.nowhere.org>
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> But I realize that this does not necessarily mean that the other
>> processes cannot read from or write to the tty anymore. Do you know
>> how to do that? :-)
>
> When you have control vhangup()

It also means more people have to disable sysrq than before.

AFAIK currently it's not possible to actually change anything 
with sysrq (just reboot/kill/show information). That would
be the first one who could be actually used to change
data, enable network login etc.

I bet this unexpected change of security policy would
surprise a lot of existing users and suddenly give
a new attack vector.

So if this is added it should at least have a separate
enable switch with default off. But as Alan says, we
have vt-switch anyways so ...

-Andi

-- 
ak@linux.intel.com
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