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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CEDDECAAD5 for ; Thu, 8 Sep 2022 05:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229472AbiIHFZW (ORCPT ); Thu, 8 Sep 2022 01:25:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229477AbiIHFZT (ORCPT ); Thu, 8 Sep 2022 01:25:19 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5353C697C; Wed, 7 Sep 2022 22:25:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 77687B81F74; Thu, 8 Sep 2022 05:25:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E27E1C433C1; Thu, 8 Sep 2022 05:25:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662614715; bh=osN0nyK8KwiIgCh1KT2OvlnB6W7vIWDWuXnKS0QOONI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fdFrY63l05XtHxT0jgjBilC5RsfiXOfLR8PaJw5hnprOQn9oBQZ0I0ftP6mjYDi2Z bvWqDTib3obv+XUNvFrc5Lr9tV8eyh3Dfg035a2NMyZxdBcO94xp/HVU756mwf9/kL 2XvD92RzN259RKNwMrYSrp0tZGFABPWp9DAF5VnsEpYvpWHeNINkCOSPVOCmwvwNrl xpzciixWdDs//CQl1IiV1gkVL95QUpvw7JTauZCk+m+OCTmefuoeaXDgNjX9EsJg2U zlYLc3ZB3S7rzhMSaunVR9OgqD+xUC9iATj/x6QGtsw5NuC4rjADG+xrN5Ndd+M6Qf jny6YHh5bu8FA== Date: Thu, 8 Sep 2022 08:25:09 +0300 From: Jarkko Sakkinen To: Mimi Zohar Cc: Evan Green , Matthew Garrett , Ken Goldman , LKML , Daniil Lunev , "James E.J. Bottomley" , linux-integrity@vger.kernel.org, Jonathan Corbet , "Rafael J. Wysocki" , Gwendal Grignou , Linux PM , Len Brown , Pavel Machek , "Rafael J. Wysocki" Subject: Re: TPM: hibernate with IMA PCR 10 Message-ID: References: <20220504232102.469959-1-evgreen@chromium.org> <20220504161439.6.Ifff11e11797a1bde0297577ecb2f7ebb3f9e2b04@changeid> <96360ec16b21d8b37461a5de083ff794f3604300.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <96360ec16b21d8b37461a5de083ff794f3604300.camel@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 07, 2022 at 07:57:27PM -0400, Mimi Zohar wrote: > On Wed, 2022-09-07 at 13:47 -0700, Evan Green wrote: > > On Tue, Aug 30, 2022 at 7:48 PM Jarkko Sakkinen wrote: > > > > > > On Mon, Aug 29, 2022 at 02:51:50PM -0700, Matthew Garrett wrote: > > > > On Mon, Aug 29, 2022 at 2:45 PM Ken Goldman wrote: > > > > > > > > > > On 5/4/2022 7:20 PM, Evan Green wrote: > > > > > > Enabling the kernel to be able to do encryption and integrity checks on > > > > > > the hibernate image prevents a malicious userspace from escalating to > > > > > > kernel execution via hibernation resume. [snip] > > > > > > > > > > I have a related question. > > > > > > > > > > When a TPM powers up from hibernation, PCR 10 is reset. When a > > > > > hibernate image is restored: > > > > > > > > > > 1. Is there a design for how PCR 10 is restored? > > > > > > > > I don't see anything that does that at present. > > > > > > > > > 2. How are /sys/kernel/security/ima/[pseudofiles] saved and > > > > > restored? > > > > > > > > They're part of the running kernel state, so should re-appear without > > > > any special casing. However, in the absence of anything repopulating > > > > PCR 10, they'll no longer match the in-TPM value. > > > > > > This feature could still be supported, if IMA is disabled > > > in the kernel configuration, which I see a non-issue as > > > long as config flag checks are there. > > > > Right, from what I understand about IMA, the TPM's PCR getting out of > > sync with the in-kernel measurement list across a hibernate (because > > TPM is reset) or kexec() (because in-memory list gets reset) is > > already a problem. This series doesn't really address that, in that it > > doesn't really make that situation better or worse. > > For kexec, the PCRs are not reset, so the IMA measurment list needs to > be carried across kexec and restored. This is now being done on most > architectures. Afterwards, the IMA measurement list does match the > PCRs. > > Hibernation introduces a different situation, where the the PCRs are > reset, but the measurement list is restored, resulting in their not > matching. As I said earlier the feature still can be supported if kernel does not use IMA but obviously needs to be flagged. BR, Jarkko