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

[Andi Kleen <andi@firstfloor.org>]

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