From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f179.google.com ([209.85.223.179]:35280 "EHLO mail-io0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753319AbcCZNrv (ORCPT ); Sat, 26 Mar 2016 09:47:51 -0400 Date: Sat, 26 Mar 2016 08:47:48 -0500 From: Eric Biggers To: Jaegeuk Kim Cc: Linus Torvalds , Linux Kernel Mailing List , Linux FS Dev Mailing List , Linux F2FS Dev Mailing List Subject: Re: [GIT PULL] f2fs updates for v4.6 Message-ID: <20160326134748.GA971@zzz> References: <20160320225859.GA5047@jaegeuk.hsd1.ca.comcast.net> <20160321184520.GA8199@jaegeuk.gateway> <20160326061007.GA24620@zzz> <20160326085606.GA41603@jaegeuk.hsd1.ca.comcast.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160326085606.GA41603@jaegeuk.hsd1.ca.comcast.net> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: It seems strange to me --- a "renaming" commit made IVs start getting reused, weakening the encryption. Do you have an explanation for how this change got introduced? Another question about the choice of IV. If the page index in CPU order is (supposed to be) used as the IV, doesn't make the on-disk format of the filesystem endianness-dependent? I thought that's a big no-no. On Sat, Mar 26, 2016 at 01:56:06AM -0700, Jaegeuk Kim wrote: > On Sat, Mar 26, 2016 at 01:10:07AM -0500, Eric Biggers wrote: > > Why was the XTS tweak initialization changed in commit 0b81d0779072 ("fs crypto: > > move per-file encryption from f2fs tree to fs/crypto")? > > > > Old code: > > > > memcpy(xts_tweak, &index, sizeof(index)); > > memset(&xts_tweak[sizeof(index)], 0, > > F2FS_XTS_TWEAK_SIZE - sizeof(index)); > > > > New code: > > memcpy(xts_tweak, &inode->i_ino, sizeof(index)); > > memset(&xts_tweak[sizeof(index)], 0, > > FS_XTS_TWEAK_SIZE - sizeof(index)); > > > > Now the XTS tweak is the same for all pages of each inode. > > Thank you for catching this. > I've checked several times, but turns out I missed something tho. :( > Let me write a patch to fix this. > > Thanks, > >