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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 8FB75C433DF for ; Mon, 1 Jun 2020 04:07:29 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 D8CEA20659 for ; Mon, 1 Jun 2020 04:07:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="RtclL/1m" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D8CEA20659 Authentication-Results: mail.kernel.org; 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Mon, 1 Jun 2020 14:05:45 +1000 (AEST) Received: from [10.0.0.249] (c-24-19-135-168.hsd1.wa.comcast.net [24.19.135.168]) by linux.microsoft.com (Postfix) with ESMTPSA id 2990E20B717B; Sun, 31 May 2020 21:05:43 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 2990E20B717B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1590984344; bh=cRf16aYvsFXacsv2R2HsGnQ+AFezDz46tzhgNYqzsKQ=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=RtclL/1mN0GD5uQjpU2HqQMKwfeCxJF7ii6ZMHj1q8msZDrQl3a61nZvqqop/mGeG +bxU39v107EGEpBikMuO+iu4qzmqb+8SjDrtEiRMmCNrLLpEmRo0efZ8pYE0dEAJfw Iq/vtpTkpHILxsgjyodTpvugBzpBvpLdSBmcmuWk= Subject: Re: [RFC][PATCH 0/2] Add support for using reserved memory for ima buffer pass To: Thiago Jung Bauermann References: <20200504203829.6330-1-prsriva@linux.microsoft.com> <20200505095620.GA82424@C02TD0UTHF1T.local> <20200512230509.GA2654@bogus> <7701df90-a68b-b710-4279-9d64e45ee792@linux.microsoft.com> <87v9knpa36.fsf@morokweng.localdomain> From: Prakhar Srivastava Message-ID: <9c016a54-1c05-2f5c-6755-3814309e17af@linux.microsoft.com> Date: Sun, 31 May 2020 21:05:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87v9knpa36.fsf@morokweng.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, bhsharma@redhat.com, tao.li@vivo.com, zohar@linux.ibm.com, paulus@samba.org, vincenzo.frascino@arm.com, will@kernel.org, Rob Herring , nramas@linux.microsoft.com, frowand.list@gmail.com, masahiroy@kernel.org, jmorris@namei.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, serge@hallyn.com, devicetree@vger.kernel.org, pasha.tatashin@soleen.com, hsinyi@chromium.org, tusharsu@linux.microsoft.com, tglx@linutronix.de, allison@lohutok.net, christophe.leroy@c-s.fr, mbrugger@suse.com, balajib@linux.microsoft.com, dmitry.kasatkin@gmail.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, james.morse@arm.com, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 5/22/20 9:08 PM, Thiago Jung Bauermann wrote: > > Hello Prakhar, > > Prakhar Srivastava writes: > >> On 5/12/20 4:05 PM, Rob Herring wrote: >>> On Wed, May 06, 2020 at 10:50:04PM -0700, Prakhar Srivastava wrote: >>>> Hi Mark, >>> >>> Please don't top post. >>> >>>> This patch set currently only address the Pure DT implementation. >>>> EFI and ACPI implementations will be posted in subsequent patchsets. >>>> >>>> The logs are intended to be carried over the kexec and once read the >>>> logs are no longer needed and in prior conversation with James( >>>> https://lore.kernel.org/linux-arm-kernel/0053eb68-0905-4679-c97a-00c5cb6f1abb@arm.com/) >>>> the apporach of using a chosen node doesn't >>>> support the case. >>>> >>>> The DT entries make the reservation permanent and thus doesnt need kernel >>>> segments to be used for this, however using a chosen-node with >>>> reserved memory only changes the node information but memory still is >>>> reserved via reserved-memory section. >>> >>> I think Mark's point was whether it needs to be permanent. We don't >>> hardcode the initrd address for example. >>> >> Thankyou for clarifying my misunderstanding, i am modelling this keeping to the >> TPM log implementation that uses a reserved memory. I will rev up the version >> with chosen-node support. >> That will make the memory reservation free after use. > > Nice. Do you intend to use the same property that powerpc uses > (linux,ima-kexec-buffer)? > I was naming it ima-buffer, but naming is not a huge concern. I will use linux,ima-kexec-buffer. >>>> On 5/5/20 2:59 AM, Mark Rutland wrote: >>>>> Hi Prakhar, >>>>> >>>>> On Mon, May 04, 2020 at 01:38:27PM -0700, Prakhar Srivastava wrote: >>>>>> IMA during kexec(kexec file load) verifies the kernel signature and measures >>> >>> What's IMAIMA is a LSM attempting to detect if files have been accidentally or >> maliciously altered, both remotely and locally, it can also be used >> to appraise a file's measurement against a "good" value stored as an extended >> attribute, and enforce local file integrity. >> >> IMA also validates and measures the signers of the kernel and initrd >> during kexec. The measurements are extended to PCR 10(configurable) and the logs >> stored in memory, however once kexec'd the logs are lost. Kexec is used as >> secondary boot loader in may use cases and loosing the signer >> creates a security hole. >> >> This patch is an implementation to carry over the logs and making it >> possible to remotely validate the signers of the kernel and initrd. Such a >> support exits only in powerpc. >> This patch makes the carry over of logs architecture independent and puts the >> complexity in a driver. > > If I'm not mistaken, the code at arch/powerpc/kexec/ima.c isn't actually > powerpc-specific. It could be moved to an arch-independent directory and > used by any other architecture which supports device trees. > > I think that's the simplest way forward. And to be honest I'm still > trying to understand why you didn't take that approach. Did you try it > and hit some obstacle or noticed a disadvantage for your use case? > The approach i have in this patch set is to provide an abstraction layer that can be called from any architecture. However taking a deeper look only the setup dtb is probably architecture specific, only because the architecture specific kexec sets up the device tree. I can also move the code up in security/ima. However i do have some concerns with layering. I am hoping you can provide me with some guidance in this aspect, i will send you the patch i am working on to get some early feedback. Thanks, Prakhar Srivastava > -- > Thiago Jung Bauermann > IBM Linux Technology Center >