Date: Fri, 23 Jul 2004 17:52:41 +0300 From: Maxim Sobolev <sobomax@portaone.com> To: Doug Rabson <dfr@nlsystems.com> Cc: Andrew Gallatin <gallatin@cs.duke.edu> Subject: Re: Excellent job on the firewire support! Message-ID: <41012639.3020102@portaone.com> In-Reply-To: <1090421941.7114.26.camel@builder02.qubesoft.com> References: <16634.47272.768935.436137@grasshopper.cs.duke.edu> <200407182039.10773.dfr@nlsystems.com> <16634.54674.966908.540880@grasshopper.cs.duke.edu> <200407182104.53221.dfr@nlsystems.com> <16638.32914.509773.486468@grasshopper.cs.duke.edu> <1090421941.7114.26.camel@builder02.qubesoft.com>
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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
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