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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C98C9F8FA80 for ; Tue, 21 Apr 2026 14:09:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=y3oJcLyo7vkpYXoTMc3/PzZ4YiSdMZCysgNXPHUpAiM=; b=oUEXcXbWnMIvhcMNhPYLS6c21C N4BXfBsWIi+g7z/x2an8dK8KrsaoXGsEQfa5FIHM2UFNIWh0X3tJSm4eN4VJn2TcB/geeicnG5ffQ QcOr8sz/BQSU7R10loZ6i2/Pzt4ndLtuKyri3e2QSLyuPe8T//ZYlQRaAYsJTmLJwPIG8PeSGaKwC GOVTQAfS7Q0PAn2tKOjiDA457ItQh+n3a2PKM9WT+jVd/qqcgcS++hLnnA97n/QNtueVpqeatj1ck fYmeD/5hDHArxXZo+JaHgwfJve0FlSalCGy3USYUrczCU2LeSqI3DGeKpDwUJ8+1w9prMpqwdxzLz 6fkMPhLg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wFBnB-00000008iRp-35YE; Tue, 21 Apr 2026 14:09:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wFBn9-00000008iRL-24kQ for linux-arm-kernel@lists.infradead.org; Tue, 21 Apr 2026 14:09:32 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9411D25DC; Tue, 21 Apr 2026 07:09:23 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BE3763F915; Tue, 21 Apr 2026 07:09:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776780568; bh=PM0r4vU3njSbwOSpmk+txAaJg1BVbJV8LhO5dpZzTXA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Aqpn6Rs6HdmexG8FiKGSHBbrKhhKVxm72mZiGAWnCbVyf1d+em6YjunDAfB22s/bS QQkYCu8FBISjfN4/0nJ/dGmsJsEA5WNXPJ/KK2n0K4lAWF96MweAYDOhli6QHxz8Lc MmQMD2rltRpMnrYoMqAktVh7FekpLbELIu7MJ2w0= Date: Tue, 21 Apr 2026 15:09:23 +0100 From: Yeoreum Yun To: Mimi Zohar Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, roberto.sassu@huawei.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, sudeep.holla@kernel.org, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org Subject: Re: [RFC PATCH 1/4] security: ima: move ima_init into late_initcall_sync Message-ID: References: <20260417175759.3191279-1-yeoreum.yun@arm.com> <20260417175759.3191279-2-yeoreum.yun@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260421_070931_696048_AA27D02B X-CRM114-Status: GOOD ( 43.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mimi, > On Tue, 2026-04-21 at 13:50 +0100, Yeoreum Yun wrote: > > Hi Mimi, > > > > > On Fri, 2026-04-17 at 18:57 +0100, Yeoreum Yun wrote: > > > > To generate the boot_aggregate log in the IMA subsystem with TPM PCR values, > > > > the TPM driver must be built as built-in and > > > > must be probed before the IMA subsystem is initialized. > > > > > > > > However, when the TPM device operates over the FF-A protocol using > > > > the CRB interface, probing fails and returns -EPROBE_DEFER if > > > > the tpm_crb_ffa device — an FF-A device that provides the communication > > > > interface to the tpm_crb driver — has not yet been probed. > > > > > > > > To ensure the TPM device operating over the FF-A protocol with > > > > the CRB interface is probed before IMA initialization, > > > > the following conditions must be met: > > > > > > > > 1. The corresponding ffa_device must be registered, > > > > which is done via ffa_init(). > > > > > > > > 2. The tpm_crb_driver must successfully probe this device via > > > > tpm_crb_ffa_init(). > > > > > > > > 3. The tpm_crb driver using CRB over FF-A can then > > > > be probed successfully. (See crb_acpi_add() and > > > > tpm_crb_ffa_init() for reference.) > > > > > > > > Unfortunately, ffa_init(), tpm_crb_ffa_init(), and crb_acpi_driver_init() are > > > > all registered with device_initcall, which means crb_acpi_driver_init() may > > > > be invoked before ffa_init() and tpm_crb_ffa_init() are completed. > > > > > > > > When this occurs, probing the TPM device is deferred. > > > > However, the deferred probe can happen after the IMA subsystem > > > > has already been initialized, since IMA initialization is performed > > > > during late_initcall, and deferred_probe_initcall() is performed > > > > at the same level. > > > > > > > > To resolve this, move ima_init() into late_inicall_sync level > > > > so that let IMA not miss TPM PCR value when generating boot_aggregate > > > > log though TPM device presents in the system. > > > > > > > > Signed-off-by: Yeoreum Yun > > > > > > IMA should be initialized as early as possible. I'm really hesitant to defer > > > ima_init() to late_initcall_sync() for systems that the TPM is currently > > > initialized in time. For these systems, continue initializing IMA at > > > late_initcall(). As a compromise for those systems that the TPM isn't properly > > > initialized in time, define and instantiate the late_initcall_sync(). > > > > > > ima_init() would need to differentiate between the late_initcall and > > > late_initcall_sync. On late_initcall(), instead of saying "No TPM chip found, > > > activating TPM-bypass!", it should say "No TPM chip found, deferring to > > > late_initcall_sync" or something similar. > > > > But can we really move those initialisations to be called again? > > > > I am referring to functions such as ima_init_crypto(), > > ima_add_boot_aggregate(), and ima_measure_critical_data() in ima_init()— > > first without TPM, and then a second time once TPM becomes available. > > I don’t think that approach would work. > > > > In other words, unless tpm_default_chip() can differentiate between a TPM > > device that is deferred and one that does not exist, we cannot distinguish > > between the “defer” case and “-EEXIST”. > > > > It might be possible if the TPM core tracked the state when a driver returns > > -EPROBE_DEFER, but I am not sure that is the right approach. > > For deferred probe cases, the “device initialised in time” check should > > likely be done at late_initcall_sync, rather than late_initcall. > > > > This implies that any such check performed before late_initcall_sync > > does not reflect a valid state, as it cannot distinguish between “not > > present” and “deferred”. > > > > Therefore, I think the TPM check in IMA should be performed at > > late_initcall_sync. > > > > > > Am I missing something? > > In ima_init() you short circuit out, when called by late_initcall(), if the TPM > hasn't been initialized. So the rest of the ima_init() isn't called. Roughly > something like this (needs some cleanup): > > int __init ima_init(void) > { > static int first = 1; > int rc; > > if (ima_tpm_chip) > return 0; > > ima_tpm_chip = tpm_default_chip(); > if (!ima_tpm_chip && first) { > pr_info("No TPM chip found, deferring te late_initcall_sync()\n"); > first = 0; > return 0; > } I see. then I'll respin in v2. Thanks! -- Sincerely, Yeoreum Yun