From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 8616D282 for ; Sat, 1 Aug 2015 19:04:01 +0000 (UTC) Received: from atrey.karlin.mff.cuni.cz (atrey.karlin.mff.cuni.cz [195.113.26.193]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 8FD5D178 for ; Sat, 1 Aug 2015 19:04:00 +0000 (UTC) Date: Sat, 1 Aug 2015 21:03:57 +0200 From: Pavel Machek To: Mark Brown Message-ID: <20150801190357.GA25683@amd> References: <20150723105726.GC30929@amd> <20150723121441.GB29747@amd> <20150723084251.54da2be0@gandalf.local.home> <20150723202901.GA30318@amd> <20150729133244.GH20130@sirena.org.uk> <20150731122227.GA31877@amd> <20150731175215.GJ20873@sirena.org.uk> <20150731220306.GA7867@amd> <20150801105522.GP20873@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150801105522.GP20873@sirena.org.uk> Cc: "ksummit-discuss@lists.linuxfoundation.org" , riverful.kim@samsung.com, kyungmin.park@samsung.com, John Stultz , Bjorn Andersson Subject: Re: [Ksummit-discuss] [CORE TOPIC] Mainline kernel on a cellphone List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat 2015-08-01 11:55:23, Mark Brown wrote: > On Sat, Aug 01, 2015 at 12:03:06AM +0200, Pavel Machek wrote: > > On Fri 2015-07-31 18:52:15, Mark Brown wrote: > > > > Given that the baseband is a key part of the data path it's not like > > > you're gaining anything there as far as I can see? I suppose you could > > > argue that the AP is actually an additional attack surface here. > > > Actually yes, I believe I'm gaining a lot. > > > If baseband is directly connected to the microphone, it can eavesdrop > > on me while the phone appears to be idle. > > Oh, right. That's not an issue since there's generally routing control > in the rest of the system (within the CODEC and sometimes elsewhere > also) so you can isolate the baseband from the local audio sources and > only connect it in call. When not in use the CODEC will be powered down > and even when in use by the AP you'd usually not route to the baseband. > > The baseband normally doesn't have sufficient physical access to > relevant control interfaces to get any input. Ok, on many systems you are right, I guess. That still leaves these reasons to route it though the CPU: * ability to record calls * ability to do signal processing on the data, like echo cancel for speakerphone (or perhaps changing your voice to female one) * ability to do advanced stuff like GSM-to-VOIP gateway. But yes, connecting baseband directly to audio is simpler... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html