From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34502C43381 for ; Thu, 14 Mar 2019 23:07:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09AFC21874 for ; Thu, 14 Mar 2019 23:07:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728054AbfCNXH2 (ORCPT ); Thu, 14 Mar 2019 19:07:28 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:44811 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727489AbfCNXH1 (ORCPT ); Thu, 14 Mar 2019 19:07:27 -0400 Received: from callcc.thunk.org (guestnat-104-133-0-99.corp.google.com [104.133.0.99] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x2EN72P5022266 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 14 Mar 2019 19:07:03 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 27E6A420AA8; Thu, 14 Mar 2019 19:07:02 -0400 (EDT) Date: Thu, 14 Mar 2019 19:07:02 -0400 From: "Theodore Ts'o" To: Richard Weinberger Cc: Eric Biggers , linux-mtd@lists.infradead.org, linux-fscrypt@vger.kernel.org, jaegeuk@kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, paullawrence@google.com Subject: Re: [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Message-ID: <20190314230702.GE6482@mit.edu> Mail-Followup-To: Theodore Ts'o , Richard Weinberger , Eric Biggers , linux-mtd@lists.infradead.org, linux-fscrypt@vger.kernel.org, jaegeuk@kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, paullawrence@google.com References: <20190314171559.27584-5-richard@nod.at> <20190314174913.GA30026@gmail.com> <1957441.Hty6t2mpXG@blindfold> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1957441.Hty6t2mpXG@blindfold> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Richard --- stepping back for a moment, in your use case, are you assuming that the encryption key is always going to be present while the system is running? Ubifs can't use dm-crypt, since it doesn't have a block device, but if you could, is much more like dm-crypt, in that you have the key *before* the file system is mounted, and you don't really expect the key to ever be expunged from the system while it is mounted? If that's true, maybe the real mismatch is in using fscrypt in the first place --- and in fact, something where you encrypt everything, including the file system metadata (ala dm-crypt), would actually give you much better security properties. - Ted