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=-7.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 F2622C4338F for ; Mon, 23 Aug 2021 13:29:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2A806137B for ; Mon, 23 Aug 2021 13:29:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233628AbhHWNaA (ORCPT ); Mon, 23 Aug 2021 09:30:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230009AbhHWN36 (ORCPT ); Mon, 23 Aug 2021 09:29:58 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0E06C061575 for ; Mon, 23 Aug 2021 06:29:15 -0700 (PDT) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=[127.0.0.1]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1mIA0k-00069J-F0; Mon, 23 Aug 2021 15:29:10 +0200 Subject: Re: [PATCH 0/4] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys To: Tim Harvey Cc: David Gstir , Aymen Sghaier , Mimi Zohar , Jan Luebbe , keyrings@vger.kernel.org, Steffen Trumtrar , linux-security-module@vger.kernel.org, Udit Agarwal , Herbert Xu , =?UTF-8?Q?Horia_Geant=c4=83?= , Richard Weinberger , James Morris , Eric Biggers , "Serge E. Hallyn" , Sumit Garg , James Bottomley , Franck LENORMAND , David Howells , open list , Jarkko Sakkinen , linux-crypto@vger.kernel.org, Sascha Hauer , linux-integrity@vger.kernel.org, "David S. Miller" References: <2b48a848-d70b-9c43-5ca0-9ab72622ed12@pengutronix.de> <9200d46d-94a2-befd-e9b0-93036e56eb8a@pengutronix.de> From: Ahmad Fatoum Message-ID: Date: Mon, 23 Aug 2021 15:29:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: a.fatoum@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Tim, On 20.08.21 23:19, Tim Harvey wrote: > On Fri, Aug 20, 2021 at 1:36 PM Ahmad Fatoum wrote: >> >> On 20.08.21 22:20, Tim Harvey wrote: >>> On Fri, Aug 20, 2021 at 9:20 AM Ahmad Fatoum wrote: >>>> On 20.08.21 17:39, Tim Harvey wrote: >>>>> Thanks for your work! >>>>> >>>>> I've been asked to integrate the capability of using CAAM to >>>>> blob/deblob data to an older 5.4 kernel such as NXP's downstream >>>>> vendor kernel does [1] and I'm trying to understand how your series >>>>> works. I'm not at all familiar with the Linux Key Management API's or >>>>> trusted keys. Can you provide an example of how this can be used for >>>>> such a thing? >>>> >>>> Here's an example with dm-crypt: >>>> >>>> https://lore.kernel.org/linux-integrity/5d44e50e-4309-830b-79f6-f5d888b1ef69@pengutronix.de/ >>>> >>>> dm-crypt is a bit special at the moment, because it has direct support for >>>> trusted keys. For interfacing with other parts of the kernel like ecryptfs >>>> or EVM, you have to create encrypted keys rooted to the trusted keys and use >>>> those. The kernel documentation has an example: >>>> >>>> https://www.kernel.org/doc/html/v5.13/security/keys/trusted-encrypted.html >>>> >>>> If you backport this series, you can include the typo fix spotted by David. >>>> >>>> I'll send out a revised series, but given that a regression fix I want to >>>> rebase on hasn't been picked up for 3 weeks now, I am not in a hurry. >>>> >>> Thanks for the reference. >>> >>> I'm still trying to understand the keyctl integration with caam. For >>> the 'data' param to keyctl you are using tings like 'new ' and >>> 'load '. Where are these 'commands' identified? >> >> Search for match_table_t in security/keys/trusted-keys/trusted_core.c >> >>> I may still be missing something. I'm using 4.14-rc6 with your series >>> and seeing the following: >> >> That's an odd version to backport stuff to.. >> >>> # cat /proc/cmdline >>> trusted.source=caam >>> # keyctl add trusted mykey 'new 32' @s)# create new trusted key named >>> 'mykey' of 32 bytes in the session keyring >>> 480104283 >>> # keyctl print 480104283 # dump the key >>> keyctl_read_alloc: Unknown error 126 >>> ^^^ not clear what this is >> >> Not sure what returns -ENOKEY for you. I haven't been using trusted >> keys on v4.14, but you can try tracing the keyctl syscall. > > yikes... that would be painful. I typo'd and meant 5.14-rc6 :) ^^ > I'm working with mainline first to make sure I understand everything. If I > backport this it would be to 5.4 but that looks to be extremely > painful. It looks like there was a lot of activity around trusted keys > in 5.13. Ye. It used to be limited to TPM before that. > It works for a user keyring but not a session keyring... does that > explain anything? > # keyctl add trusted mykey 'new 32' @u > 941210782 > # keyctl print 941210782 > 83b7845cb45216496aead9ee2c6a406f587d64aad47bddc539d8947a247e618798d9306b36398b5dc2722a4c3f220a3a763ee175f6bd64758fdd49ca4db597e8ce328121b60edbba9b8d8d55056be896 > # keyctl add trusted mykey 'new 32' @s > 310571960 > # keyctl print 310571960 > keyctl_read_alloc: Unknown error 126 Both sequences work for me. My getty is started by systemd. I think systemd allocates a new session keyring for the getty that's inherited by the shell and the commands I run it in. If you don't do that, each command will get its own session key. > Sorry, I'm still trying to wrap my head around the differences in > keyrings and trusted vs user keys. No problem. HTH. Cheers, Ahmad > > Tim > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |