From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Date: Fri, 15 Nov 2019 17:29:44 +0000 Subject: Re: [PATCH] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY Message-Id: <20191115172944.GB21300@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20191107001259.115018-1-ebiggers@kernel.org> <20191113203550.GI221701@gmail.com> In-Reply-To: <20191113203550.GI221701@gmail.com> To: David Howells , 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 , g@linux.intel.com On Wed, Nov 13, 2019 at 12:35:51PM -0800, Eric Biggers wrote: > 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? Thanks for reminding. Still catching up with keyring. I gave some feedback to the patch. /Jarkko 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=unavailable 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 0D246C43141 for ; Fri, 15 Nov 2019 17:29:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E63E320740 for ; Fri, 15 Nov 2019 17:29:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727627AbfKOR3x (ORCPT ); Fri, 15 Nov 2019 12:29:53 -0500 Received: from mga04.intel.com ([192.55.52.120]:14118 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727543AbfKOR3x (ORCPT ); Fri, 15 Nov 2019 12:29:53 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2019 09:29:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,308,1569308400"; d="scan'208";a="288613668" Received: from sgaffney-mobl3.amr.corp.intel.com (HELO localhost) ([10.252.4.81]) by orsmga001.jf.intel.com with ESMTP; 15 Nov 2019 09:29:45 -0800 Date: Fri, 15 Nov 2019 19:29:44 +0200 From: Jarkko Sakkinen To: David Howells , 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 , g@linux.intel.com Subject: Re: [PATCH] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY Message-ID: <20191115172944.GB21300@linux.intel.com> References: <20191107001259.115018-1-ebiggers@kernel.org> <20191113203550.GI221701@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191113203550.GI221701@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo 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 Wed, Nov 13, 2019 at 12:35:51PM -0800, Eric Biggers wrote: > 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? Thanks for reminding. Still catching up with keyring. I gave some feedback to the patch. /Jarkko 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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 147BFC43215 for ; Fri, 15 Nov 2019 17:30:02 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (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 DC16B2073B; Fri, 15 Nov 2019 17:30:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="Jon/3HQI"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sf.net header.i=@sf.net header.b="I4r1M6fQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC16B2073B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1iVfQ1-0002HW-HD; Fri, 15 Nov 2019 17:30:01 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1iVfPz-0002HD-JH for linux-f2fs-devel@lists.sourceforge.net; Fri, 15 Nov 2019 17:29:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:To:From:Date:Sender:Reply-To:Cc:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=oWcX7oylNZmX12Lrm67bE44Swo+hnDKmSPFc1Af2TcA=; b=Jon/3HQIT/D5tYq0Ofy6xMRyfu cb027YjBbtq+giALaM+Kx4CrJ6C9pGz/hRcRIJIuFM9I0nMTQXoWe1fk+9+HPrDCWBS8LlrfHHXVW sEcTmR40iEWGf1bdf5Iy+4PCzUl5c0f657+vd/XgwDAa0bd24ffZWRDKcAeSgZP/HEMs=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:To: From:Date:Sender:Reply-To:Cc:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=oWcX7oylNZmX12Lrm67bE44Swo+hnDKmSPFc1Af2TcA=; b=I4r1M6fQo2+iBec8POwSCqbk5R 5iwMrDB4TrFWjB4HmREV71VLkArfl2LdxJxCfkPqfeiKpFBg8XixXrtqwoEi8mmAMB3CzF/REp6lc 5mjzmt+ugo6/EcLWYo/Wus8jkd3+PZa20t3fg3rwVKAZ28IjBFidAdsUECUh4O7Zlgt0=; Received: from mga04.intel.com ([192.55.52.120]) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.2) id 1iVfPy-0018RN-8d for linux-f2fs-devel@lists.sourceforge.net; Fri, 15 Nov 2019 17:29:59 +0000 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2019 09:29:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,308,1569308400"; d="scan'208";a="288613668" Received: from sgaffney-mobl3.amr.corp.intel.com (HELO localhost) ([10.252.4.81]) by orsmga001.jf.intel.com with ESMTP; 15 Nov 2019 09:29:45 -0800 Date: Fri, 15 Nov 2019 19:29:44 +0200 From: Jarkko Sakkinen To: David Howells , 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 , g@linux.intel.com Message-ID: <20191115172944.GB21300@linux.intel.com> References: <20191107001259.115018-1-ebiggers@kernel.org> <20191113203550.GI221701@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191113203550.GI221701@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) X-Headers-End: 1iVfPy-0018RN-8d Subject: Re: [f2fs-dev] [PATCH] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Wed, Nov 13, 2019 at 12:35:51PM -0800, Eric Biggers wrote: > 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? Thanks for reminding. Still catching up with keyring. I gave some feedback to the patch. /Jarkko _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel 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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 C49EDC432C3 for ; Fri, 15 Nov 2019 17:30:25 +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 96B4E2073B for ; Fri, 15 Nov 2019 17:30:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Lyq/Qq0+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96B4E2073B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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: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:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3FI0G7KtP9PGwdgg2t+7vH2ptGYYsMPlut2dcAiWHOU=; b=Lyq/Qq0+kDTSU4 jZLU5pqjh4ykVLOfv/M8W7vfjd2nYrgs6DXH9d7Q53KvztAVyDjLJ8YSFshR669iMFXmz9F8U7tmm YJq2PkGZho+S8gic+ZZePGEE2VKks+bLXZLHBXude6xQiguLkhQlmakKb8TMpUWCL1fkPUdn2Dunq a09bKag3ZPolE5QWjfL6iP6i9k06RXLOyvCNbGD5Avv4jt9LptXfwSFdzc3jQ6htKLP2NytnqsQgX zYKo2nNXjZ5fnYL2xiw68AcNd5l/QsP9Hs6QIEfnTiQvUl+gQdLFRAmuRBsaE8yaUl3Y5cWu6oVq3 pQhU8QZUzy7w6HKYibug==; 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 1iVfQ1-0001gS-Gy; Fri, 15 Nov 2019 17:30:01 +0000 Received: from mga14.intel.com ([192.55.52.115]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iVfPz-0001fV-6p for linux-mtd@lists.infradead.org; Fri, 15 Nov 2019 17:30:00 +0000 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2019 09:29:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,308,1569308400"; d="scan'208";a="288613668" Received: from sgaffney-mobl3.amr.corp.intel.com (HELO localhost) ([10.252.4.81]) by orsmga001.jf.intel.com with ESMTP; 15 Nov 2019 09:29:45 -0800 Date: Fri, 15 Nov 2019 19:29:44 +0200 From: Jarkko Sakkinen To: David Howells , 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 , g@linux.intel.com Subject: Re: [PATCH] fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY Message-ID: <20191115172944.GB21300@linux.intel.com> References: <20191107001259.115018-1-ebiggers@kernel.org> <20191113203550.GI221701@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191113203550.GI221701@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo 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-20191115_092959_260144_1A7C3C38 X-CRM114-Status: GOOD ( 22.04 ) 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: , 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 13, 2019 at 12:35:51PM -0800, Eric Biggers wrote: > 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? Thanks for reminding. Still catching up with keyring. I gave some feedback to the patch. /Jarkko ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/