Re: Excellent job on the firewire support!

From: Maxim Sobolev <sobomax_at_portaone.com>
Date: Fri, 23 Jul 2004 17:52:41 +0300
Doug Rabson wrote:

> On Wed, 2004-07-21 at 15:41, Andrew Gallatin wrote:
> 
>>Doug Rabson writes:
>> > Actually thats the only downside of dcons. It doesn't cut in until the 
>> > firewire controller attaches. It relies on the fact that the fwohci 
>> > driver allows access to physical memory from any node on the bus 
>> > (implemeted in hardware so you can examine the memory of a hung 
>> > machine). The dconschat program uses this feature to access the dcons 
>> > ring buffers in the target machine.
>>
>>Does remote access to physical memory require dcons to be loaded
>>on the target?
> 
> 
> No. The remote access to physical memory is a hardware-implemented
> feature of the firewire ohci hardware. Its enabled in fwohci_attach().
> In the long term, I would like to restrict this a bit but right now all
> you have to have is fwohci loaded on the target machine.

It would be nice to have some sysctl which to disable such access, since 
it is BAD THING[tm] from the security POV.

-Maxim
Received on Fri Jul 23 2004 - 12:53:05 UTC

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