From owner-freebsd-hackers Sat Apr 13 15:33:21 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from ns.koganei.wide.ad.jp (koganei.wide.ad.jp [202.249.37.254]) by hub.freebsd.org (Postfix) with ESMTP id C896B37B405 for ; Sat, 13 Apr 2002 15:33:14 -0700 (PDT) Received: from koganei.wide.ad.jp (214.pool2.ftthtokyo.att.ne.jp [165.76.218.214]) (authenticated (0 bits)) by ns.koganei.wide.ad.jp (8.11.6/8.11.6) with ESMTP id g3DMYTD80984; Sun, 14 Apr 2002 07:34:29 +0900 (JST) (envelope-from ikob@koganei.wide.ad.jp) Message-ID: <3CB8B228.70006@koganei.wide.ad.jp> Date: Sun, 14 Apr 2002 07:33:12 +0900 From: Katsushi Kobayashi User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.8) Gecko/20020204 X-Accept-Language: en-us MIME-Version: 1.0 To: Mikko Tyolajarvi Cc: simokawa@sat.t.u-tokyo.ac.jp, hackers@FreeBSD.ORG Subject: Re: FireWire for kernel hackers References: <200204131941.g3DJfAb18611@mikko.rsa.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Mikko Tyolajarvi wrote: > >Umm... excuse a stupid question, but does this mean that a firewire >port always gives unconditional access to the host's memory? Great >for kernel debugging. Maybe not so great for a running system, from a >security point a view (ok, physical access eventually equals full >access, but plugging in a firewire cable is a heck of a lot faster >than using a screwdriver...) > Basically, firewire provides a function all host memory mapped into the unified memory space. Using this unified memory enables a connected host access to other host without CPU process. I believe access control function relys a chip implementatin. The IEEE1394 OHCI specifies two ways for the access control: 1. Host can specify the nodes capable to access its physical memory. 2. Host can specify the memory area capable to be accessed from other host. I believe the two access control ways are not enough in today. However, the currecnt firewire standard only provides limited phisical connection environment. Limited cable length and limited number of node. I think the unconditional access issues will occure at the limited situation only. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message