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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1FC3DC7618F for ; Sun, 28 Jul 2019 21:24:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E94B521655 for ; Sun, 28 Jul 2019 21:24:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726171AbfG1VYV (ORCPT ); Sun, 28 Jul 2019 17:24:21 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:36595 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726103AbfG1VYV (ORCPT ); Sun, 28 Jul 2019 17:24:21 -0400 Received: from callcc.thunk.org (96-72-102-169-static.hfc.comcastbusiness.net [96.72.102.169] (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 x6SLO3BG013518 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 28 Jul 2019 17:24:04 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 87A1D4202F5; Sun, 28 Jul 2019 17:24:02 -0400 (EDT) Date: Sun, 28 Jul 2019 17:24:02 -0400 From: "Theodore Y. 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-api@vger.kernel.org, linux-crypto@vger.kernel.org, keyrings@vger.kernel.org, Paul Crowley , Satya Tangirala Subject: Re: [PATCH v7 12/16] fscrypt: require that key be added when setting a v2 encryption policy Message-ID: <20190728212402.GM6088@mit.edu> References: <20190726224141.14044-1-ebiggers@kernel.org> <20190726224141.14044-13-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190726224141.14044-13-ebiggers@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Fri, Jul 26, 2019 at 03:41:37PM -0700, Eric Biggers wrote: > From: Eric Biggers > > By looking up the master keys in a filesystem-level keyring rather than > in the calling processes' key hierarchy, it becomes possible for a user > to set an encryption policy which refers to some key they don't actually > know, then encrypt their files using that key. Cryptographically this > isn't much of a problem, but the semantics of this would be a bit weird. > Thus, enforce that a v2 encryption policy can only be set if the user > has previously added the key, or has capable(CAP_FOWNER). > > We tolerate that this problem will continue to exist for v1 encryption > policies, however; there is no way around that. > > Signed-off-by: Eric Biggers Looks good, feel free to add: Reviewed-by: Theodore Ts'o - Ted