linux-kernel - Re: [RFC][PATCH] sysrq-j: emergency shell

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Message-ID: <871vx2jl5e.fsf@basil.nowhere.org>
Date:	Sun, 23 Nov 2008 20:29:49 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	"Vegard Nossum" <vegard.nossum@...il.com>,
	"Alexey Dobriyan" <adobriyan@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] sysrq-j: emergency shell

Alan Cox <alan@...rguk.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@...ux.intel.com
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