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=-3.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,FSL_HELO_FAKE,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 16B81C2D0C2 for ; Fri, 3 Jan 2020 16:57:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DFF91206DB for ; Fri, 3 Jan 2020 16:57:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="B42Myyie"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kxXw7SXw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DFF91206DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=slXz8L/xEMHIcepulqmB1mekEhC9CHEcb9DPDRQ6Pcw=; b=B42Myyie2YBSc2 dGIBL6U1zbcfQFv9cw2GPxFtgQdWKLAweBXZtdEZGI4ZVejTDhPszU+QF0wCpnLdWj9r36tfslnET FJbB9CMtBEbwckQqvgb2baJ9xZ5q3YdlgsWgxheCC0xEJE/0rECRj+XLgMnheDhQOmUMUTqcKlDc+ 3Ig7+U6/PRwf44R5P/d7MSh/enBRs+nsvKwWLQlMPZVQ7Jf8BFuG5QcU4iDS2TJ5fVms/z34/GwpR So8k9HtduA9H0iyrPTjLoRJ2w3iHoWYbnJEDBMGrw8BsnqLeaaZuX2cZk1cZxzm1QOd2xhnFMxB3/ QIDslZ1p5ELdB8S/8wQw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1inQGS-0002I5-LF; Fri, 03 Jan 2020 16:57:32 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1inQGP-0002GT-RF for linux-mtd@lists.infradead.org; Fri, 03 Jan 2020 16:57:31 +0000 Received: from gmail.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C5DA7206DB; Fri, 3 Jan 2020 16:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578070649; bh=RL+yaap+s7Gb++esPrb+ddyBAFUgLJGNTPp2fhE5Iv0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kxXw7SXw9knA6E1AFwsb7GlSx8TbEgrh+y/7fgxxpaTXB0F5IZCHr/2+nyXyPozfw ILl+8PJ4ckpEtM8xPBGI2xuFFCndo7KoiDhyzVqKfQU8Jg6s2/6sW1x7+8GxdVCmlv Etw2e1txnGpwPLJlYb/D0D+m8j+Y3f1VWe9VXDjA= Date: Fri, 3 Jan 2020 08:57:27 -0800 From: Eric Biggers To: linux-fscrypt@vger.kernel.org Subject: Re: [PATCH v2] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY Message-ID: <20200103165727.GB19521@gmail.com> References: <20191119222447.226853-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191119222447.226853-1-ebiggers@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200103_085729_902054_AD9730CF X-CRM114-Status: GOOD ( 19.24 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Lawrence , "Theodore Y . Ts'o" , Ondrej Mosnacek , Jarkko Sakkinen , linux-f2fs-devel@lists.sourceforge.net, David Howells , keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, Ondrej Kozina , Jaegeuk Kim , linux-ext4@vger.kernel.org, Paul Crowley Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Tue, Nov 19, 2019 at 02:24:47PM -0800, Eric Biggers wrote: > From: Eric Biggers > > Extend the FS_IOC_ADD_ENCRYPTION_KEY ioctl to allow the raw key to be > specified by a Linux keyring key, rather than specified directly. > > This is useful because fscrypt keys belong to a particular filesystem > instance, so they are destroyed when that filesystem is unmounted. > Usually this is desired. But in some cases, userspace may need to > unmount and re-mount the filesystem while keeping the keys, e.g. during > a system update. This requires keeping the keys somewhere else too. > > The keys could be kept in memory in a userspace daemon. But depending > on the security architecture and assumptions, it can be preferable to > keep them only in kernel memory, where they are unreadable by userspace. > > We also can't solve this by going back to the original fscrypt API > (where for each file, the master key was looked up in the process's > keyring hierarchy) because that caused lots of problems of its own. > > Therefore, add the ability for FS_IOC_ADD_ENCRYPTION_KEY to accept a > Linux keyring key. This solves the problem by allowing userspace to (if > needed) save the keys securely in a Linux keyring for re-provisioning, > while still using the new fscrypt key management ioctls. > > This is analogous to how dm-crypt accepts a Linux keyring key, but the > key is then stored internally in the dm-crypt data structures rather > than being looked up again each time the dm-crypt device is accessed. > > Use a custom key type "fscrypt-provisioning" rather than one of the > existing key types such as "logon". This is strongly desired because it > enforces that these keys are only usable for a particular purpose: for > fscrypt as input to a particular KDF. Otherwise, the keys could also be > passed to any kernel API that accepts a "logon" key with any service > prefix, e.g. dm-crypt, UBIFS, or (recently proposed) AF_ALG. This would > risk leaking information about the raw key despite it ostensibly being > unreadable. Of course, this mistake has already been made for multiple > kernel APIs; but since this is a new API, let's do it right. > > This patch has been tested using an xfstest which I wrote to test it. > > Signed-off-by: Eric Biggers Applied to fscrypt.git#master for 5.6. - Eric ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/