From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: ext4 crypto: Do not select from EXT4_FS_ENCRYPTION Date: Sun, 3 May 2015 13:53:20 -0400 Message-ID: <20150503175320.GI10014@thunk.org> References: <20150501001855.GA31516@gondor.apana.org.au> <554615C6.1060107@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Herbert Xu , Andreas Dilger , linux-ext4@vger.kernel.org, Michael Halcrow To: Anssi Hannula Return-path: Received: from imap.thunk.org ([74.207.234.97]:42170 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750990AbbECRx0 (ORCPT ); Sun, 3 May 2015 13:53:26 -0400 Content-Disposition: inline In-Reply-To: <554615C6.1060107@iki.fi> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, May 03, 2015 at 03:34:14PM +0300, Anssi Hannula wrote: > Hi, > > 01.05.2015, 03:18, Herbert Xu kirjoitti: > > This patch adds a tristate EXT4_ENCRYPTION to do the selections > > for EXT4_FS_ENCRYPTION because selecting from a bool causes all > > the selected options to be built-in, even if EXT4 itself is a > > module. > > Hmm, are you sure? > > Since CONFIG_EXT4_FS_ENCRYPTION itself depends on CONFIG_EXT4_FS, the > selector for the selected options becomes (CONFIG_EXT4_FS_ENCRYPTION && > CONFIG_EXT4_FS && CONFIG_BLOCK). > > Per my testing on git master (without this patch), if EXT4_FS=m and > EXT4_FS_ENCRYPTION=y, both "built-in" and "module" options are allowed > for the selected options (checked CONFIG_ENCRYPTED_KEYS myself). I believe the situation which is causing concern is when someone wants to build a kernel where EXT4_FS=y, but they want the cryptographic algorithms to be modules. In that case, since EXT4_FS_ENCRYPTION is 'y', it forces the all of the crypto modules to be built into the kernel, and so it forecloses that option from someone who is building or packaging a kernel. - Ted