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 C2E3FC433FF for ; Sun, 28 Jul 2019 19:30:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A0C3C2075B for ; Sun, 28 Jul 2019 19:30:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726180AbfG1Taf (ORCPT ); Sun, 28 Jul 2019 15:30:35 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:44444 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726108AbfG1Tae (ORCPT ); Sun, 28 Jul 2019 15:30:34 -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 x6SJUDhE009303 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 28 Jul 2019 15:30:14 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 7DDB54202F5; Sun, 28 Jul 2019 15:30:12 -0400 (EDT) Date: Sun, 28 Jul 2019 15:30:12 -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 08/16] fscrypt: add FS_IOC_GET_ENCRYPTION_KEY_STATUS ioctl Message-ID: <20190728193012.GH6088@mit.edu> References: <20190726224141.14044-1-ebiggers@kernel.org> <20190726224141.14044-9-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190726224141.14044-9-ebiggers@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Fri, Jul 26, 2019 at 03:41:33PM -0700, Eric Biggers wrote: > From: Eric Biggers > > Add a new fscrypt ioctl, FS_IOC_GET_ENCRYPTION_KEY_STATUS. Given a key > specified by 'struct fscrypt_key_specifier' (the same way a key is > specified for the other fscrypt key management ioctls), it returns > status information in a 'struct fscrypt_get_key_status_arg'. > > The main motivation for this is that applications need to be able to > check whether an encrypted directory is "unlocked" or not, so that they > can add the key if it is not, and avoid adding the key (which may > involve prompting the user for a passphrase) if it already is. > > It's possible to use some workarounds such as checking whether opening a > regular file fails with ENOKEY, or checking whether the filenames "look > like gibberish" or not. However, no workaround is usable in all cases. > > Like the other key management ioctls, the keyrings syscalls may seem at > first to be a good fit for this. Unfortunately, they are not. Even if > we exposed the keyring ID of the ->s_master_keys keyring and gave > everyone Search permission on it (note: currently the keyrings > permission system would also allow everyone to "invalidate" the keyring > too), the fscrypt keys have an additional state that doesn't map cleanly > to the keyrings API: the secret can be removed, but we can be still > tracking the files that were using the key, and the removal can be > re-attempted or the secret added again. > > After later patches, some applications will also need a way to determine > whether a key was added by the current user vs. by some other user. > Reserved fields are included in fscrypt_get_key_status_arg for this and > other future extensions. > > Signed-off-by: Eric Biggers Looks good, feel free to add: Reviewed-by: Theodore Ts'o