Re: Excellent job on the firewire support!

From: Brooks Davis <brooks_at_one-eyed-alien.net>
Date: Fri, 23 Jul 2004 09:48:09 -0700
On Fri, Jul 23, 2004 at 05:52:41PM +0300, Maxim Sobolev wrote:
> 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.

In high security environments, they use a tube of epoxy. ;-)

-- Brooks

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Received on Fri Jul 23 2004 - 14:48:11 UTC

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