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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A7B0CC2D0FB for ; Wed, 13 May 2020 00:56:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A3BF20675 for ; Wed, 13 May 2020 00:56:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732155AbgEMA4B (ORCPT ); Tue, 12 May 2020 20:56:01 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:55970 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732082AbgEMAz7 (ORCPT ); Tue, 12 May 2020 20:55:59 -0400 Received: from callcc.thunk.org (pool-100-0-195-244.bstnma.fios.verizon.net [100.0.195.244]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 04D0tcEU000849 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 May 2020 20:55:39 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id C4B6E4202E4; Tue, 12 May 2020 20:55:38 -0400 (EDT) Date: Tue, 12 May 2020 20:55:38 -0400 From: "Theodore Y. Ts'o" To: Eric Biggers Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Jaegeuk Kim , Daniel Rosenberg Subject: Re: [PATCH 2/4] fscrypt: add fscrypt_add_test_dummy_key() Message-ID: <20200513005538.GF1596452@mit.edu> References: <20200512233251.118314-1-ebiggers@kernel.org> <20200512233251.118314-3-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200512233251.118314-3-ebiggers@kernel.org> Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org On Tue, May 12, 2020 at 04:32:49PM -0700, Eric Biggers wrote: > From: Eric Biggers > > Currently, the test_dummy_encryption mount option (which is used for > encryption I/O testing with xfstests) uses v1 encryption policies, and > it relies on userspace inserting a test key into the session keyring. > > We need test_dummy_encryption to support v2 encryption policies too. > Requiring userspace to add the test key doesn't work well with v2 > policies, since v2 policies only support the filesystem keyring (not the > session keyring), and keys in the filesystem keyring are lost when the > filesystem is unmounted. Hooking all test code that unmounts and > re-mounts the filesystem would be difficult. > > Instead, let's make the filesystem automatically add the test key to its > keyring when test_dummy_encryption is enabled. > > That puts the responsibility for choosing the test key on the kernel. > We could just hard-code a key. But out of paranoia, let's first try > using a per-boot random key, to prevent this code from being misused. > A per-boot key will work as long as no one expects dummy-encrypted files > to remain accessible after a reboot. (gce-xfstests doesn't.) > > Therefore, this patch adds a function fscrypt_add_test_dummy_key() which > implements the above. The next patch will use it. > > Signed-off-by: Eric Biggers Reviewed-by: Theodore Ts'o