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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 78B22C282DA for ; Wed, 17 Apr 2019 14:07:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EDDF206BA for ; Wed, 17 Apr 2019 14:07:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732365AbfDQOHV (ORCPT ); Wed, 17 Apr 2019 10:07:21 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:44458 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732288AbfDQOHV (ORCPT ); Wed, 17 Apr 2019 10:07:21 -0400 Received: from callcc.thunk.org (guestnat-104-133-0-109.corp.google.com [104.133.0.109] (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 x3HE72dN002538 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Apr 2019 10:07:02 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 9F263420497; Wed, 17 Apr 2019 10:07:01 -0400 (EDT) Date: Wed, 17 Apr 2019 10:07:01 -0400 From: "Theodore Ts'o" To: Eric Biggers Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: Re: [PATCH v2 4/5] fscrypt: only set dentry_operations on ciphertext dentries Message-ID: <20190417140701.GD4686@mit.edu> References: <20190320183913.12686-1-ebiggers@kernel.org> <20190320183913.12686-5-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190320183913.12686-5-ebiggers@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 20, 2019 at 11:39:12AM -0700, Eric Biggers wrote: > From: Eric Biggers > > Plaintext dentries are always valid, so only set fscrypt_d_ops on > ciphertext dentries. > > Besides marginally improved performance, this allows overlayfs to use an > fscrypt-encrypted upperdir, provided that all the following are true: > > (1) The fscrypt encryption key is placed in the keyring before > mounting overlayfs, and remains while the overlayfs is mounted. > > (2) The overlayfs workdir uses the same encryption policy. > > (3) No dentries for the ciphertext names of subdirectories have been > created in the upperdir or workdir yet. (Since otherwise > d_splice_alias() will reuse the old dentry with ->d_op set.) > > One potential use case is using an ephemeral encryption key to encrypt > all files created or changed by a container, so that they can be > securely erased ("crypto-shredded") after the container stops. > > Signed-off-by: Eric Biggers Looks good, applied. - Ted