From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752976AbeFEVMn (ORCPT ); Tue, 5 Jun 2018 17:12:43 -0400 Received: from imap.thunk.org ([74.207.234.97]:39342 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752708AbeFEVMl (ORCPT ); Tue, 5 Jun 2018 17:12:41 -0400 Date: Tue, 5 Jun 2018 17:12:38 -0400 From: "Theodore Y. Ts'o" To: Richard Weinberger Cc: Richard Weinberger , Linus Torvalds , LKML , linux-fscrypt@vger.kernel.org Subject: Re: [GIT PULL] fscrypt updates for 4.18 Message-ID: <20180605211238.GH7839@thunk.org> Mail-Followup-To: "Theodore Y. Ts'o" , Richard Weinberger , Richard Weinberger , Linus Torvalds , LKML , linux-fscrypt@vger.kernel.org References: <20180605150751.GA9436@thunk.org> <30587992.7Od65ROsjm@blindfold> <20180605170208.GE7839@thunk.org> <5151941.CDXohbuWeC@blindfold> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5151941.CDXohbuWeC@blindfold> User-Agent: Mutt/1.10.0 (2018-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 05, 2018 at 07:05:52PM +0200, Richard Weinberger wrote: > > An attack scenario where someone manages to downgrade the crypto of > > your phone would require replacing your kernel and your /system > > partition --- at which point, you've got other problems. :-) > > This means Speck is never enabled at kernel level on non-cheap phones? No. And even if it were, the /system partition is going to request that the kernel encrypt files using one and only encryption algorithm: namely, AES. Things aren't as configurable on an Android phone as you might be used to on a laptop. Some manufacturers use ext4; some manufacturers decide they want to use f2fs. They make that decision not you, and only the file system utilities for that one file system are compiled into the system. Similarly, you don't get to choose what crypto algorithm you use; that's decided for you by the manufacturer. Which is good; it's one less thing that hte attacker can spoof, and one less thing for users to potentially get wrong. - Ted