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=-4.9 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,URIBL_BLOCKED,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 687C6C432C3 for ; Wed, 13 Nov 2019 20:36:12 +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 100B4206F3 for ; Wed, 13 Nov 2019 20:36:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="HHWcgSzB"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="cN+5BXj9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 100B4206F3 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=1vEGG2XZootCHB0ZPnhqiwjICe8WFzkNJufQds3EKTY=; b=HHWcgSzBUaQmvp VYpFDM+oXui+gAWgl4cvoLOhicxyUdducAIy4SfAQxwetgKkr4ImqJgFR3yZDp9O5w28gm8/2mysP pG3i7WAwWkn0y4AMnyaWYgB0dCVlK8DCglSg84EjKSyLTbBSyobB6ZMJRaKDkrDfIO86/tX0GLkAz m/PQ2ODSkhVxvG9ZjR02M6cSJi2KjmrGf06zl/PjH/rDN16ethPTSXnIJNBg2DZkgGXP/mjgSdwdZ qfBlmXdKTQfgXUJH0sHENvfkRhL8hZD75xDAu07Kf5fE+f8eYBBTpKzb9D5WzXNlOsqdcJ6LxqtAS zsBEwRIz6L1nJzA75dhg==; 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 1iUzMr-00005N-1t; Wed, 13 Nov 2019 20:35:57 +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 1iUzMn-0008WF-NA for linux-mtd@lists.infradead.org; Wed, 13 Nov 2019 20:35:55 +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 D1D53206F0; Wed, 13 Nov 2019 20:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573677354; bh=F7ZEXH3Tifjy9sGUrwh8Fhs+H6mYs1GYZonZpiJuwEo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cN+5BXj91Btq6Ry/bO1VhiaNdo4x1+Lt3QDXuQLQyXlsCVgrWNJGKLW3Zy0M3qYgf kZYrGKdT5NAbCuJckqXAScixPVqWmbN98LNs2qdXXxKYYq+xhab0ygSaprMlJrUDjc 2Rl8cQmt+I9y4p/mks0qpzDMku7DMTI2kzVonDxM= Date: Wed, 13 Nov 2019 12:35:51 -0800 From: Eric Biggers To: David Howells , Jarkko Sakkinen , keyrings@vger.kernel.org Subject: Re: [PATCH] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY Message-ID: <20191113203550.GI221701@gmail.com> Mail-Followup-To: David Howells , Jarkko Sakkinen , keyrings@vger.kernel.org, linux-fscrypt@vger.kernel.org, "Theodore Y . Ts'o" , Ondrej Mosnacek , linux-f2fs-devel@lists.sourceforge.net, Paul Lawrence , linux-mtd@lists.infradead.org, Ondrej Kozina , Jaegeuk Kim , linux-ext4@vger.kernel.org, Paul Crowley References: <20191107001259.115018-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191107001259.115018-1-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-20191113_123553_810253_E8FEEDA6 X-CRM114-Status: GOOD ( 18.98 ) 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: "Theodore Y . Ts'o" , Ondrej Mosnacek , linux-f2fs-devel@lists.sourceforge.net, Paul Lawrence , linux-fscrypt@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 Wed, Nov 06, 2019 at 04:12:59PM -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. > > Signed-off-by: Eric Biggers David and Jarkko, are you okay with this patch from a keyrings subsystem perspective? - Eric ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/