From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 676F82236E0; Thu, 23 Apr 2026 13:07:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776949632; cv=none; b=FHvenZ31qmoB6V76oyQc597K1n8CBbzR6lvwG6oQUemT8m/am5s8kj2lR8TQOvZ676i8GXX6HVQ10jHJDlpM2ODeTl/3ussbRucc2f4D2qFSSPWwbopeYVX1LrlogSWvH5ZvwVhZF5S8RHr0gr8VWx00gSoYCWcUolF1TQNqz9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776949632; c=relaxed/simple; bh=RHhcDZSJjqbRFX5DvA0y5u/itfLV8Axf4SV02gWmRjk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Y5Tww5hcs5ELN8eIYe9V8MStifN146qMpbmwRJC7GBXguPhrg1wx1LL4tYjvP4RiFEf5l5DO8+ivTte8u8+hSck78P1bvOzX/cFqgiJJiVnC1c2DSmNR6KMF1RY7+j4WBeRKeobBf1oReyJIMb4CHxjjRBob+SnxcceVucZenqE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=RETRutih; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="RETRutih" 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 28BE71C25; Thu, 23 Apr 2026 06:07:04 -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 252DA3F23F; Thu, 23 Apr 2026 06:07:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776949629; bh=RHhcDZSJjqbRFX5DvA0y5u/itfLV8Axf4SV02gWmRjk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RETRutih09HHlXWKLVKHaO/cqhNbepyaLVofdEY4Le4dC4voXpZcY79oHaMaR5IzT 7c0IXm9yjEBBV4I8YBJ+yzU/LSzXbmoplWIqeZhp+uaIikQqVg29Und9n0ibXiUCt9 W7ktWMiz+W5UB4frGHtuw/sdI7E8LZLCCwvOpjOo= Date: Thu, 23 Apr 2026 14:07:03 +0100 From: Yeoreum Yun To: Jonathan McDowell Cc: Mimi Zohar , 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, 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, noodles@meta.com, sebastianene@google.com Subject: Re: [RFC PATCH v2 1/4] security: ima: call ima_init() again at late_initcall_sync for defered TPM Message-ID: References: <20260422162449.1814615-2-yeoreum.yun@arm.com> <6919248bdc85dac60277fa9d9c83d8bd258ca635.camel@linux.ibm.com> <82803bb3b471898a77084c449b73c7f7b4eb2149.camel@linux.ibm.com> <56a8aab50a3b5ce0a345fc2079fb2abc7d0f1b23.camel@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hi, > > > > On Thu, 2026-04-23 at 06:55 +0100, Yeoreum Yun wrote: > > > > > > On Wed, 2026-04-22 at 20:41 +0100, Yeoreum Yun wrote: > > > > > > > > Hi Mimi, > > > > > > > > > > > > > > > > > On Wed, 2026-04-22 at 17:24 +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, call ima_init() again at 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 > > > > > > > > > > > > > > > > > > A lot of change for just detecting whether ima_init() is being called on > > > > > > > > > late_initcall or late_initcall_sync(), without any explanation for all the other > > > > > > > > > changes (e.g. ima_init_core). > > > > > > > > > > > > > > > > > > Please just limit the change to just calling ima_init() twice. > > > > > > > > > > > > > > > > My concern is that ima_update_policy_flags() will be called > > > > > > > > when ima_init() is deferred -- not initialised anything. > > > > > > > > though functionally, it might be okay however, > > > > > > > > I think ima_update_policy_flags() and notifier should work after ima_init() > > > > > > > > works logically. > > > > > > > > > > > > > > > > This change I think not much quite a lot. just wrapper ima_init() with > > > > > > > > ima_init_core() with some error handling. > > > > > > > > > > > > > > > > Am I missing something? > > > > > > > > > > > > > > Also, if we handle in ima_init() only, but it failed with other reason, > > > > > > > we shouldn't call again ima_init() in the late_initcall_sync. > > > > > > > > > > > > > > To handle this, It wouldn't do in the ima_init() but we need to handle > > > > > > > it by caller of ima_init(). > > > > > > > > > > > > Only tpm_default_chip() is being called to set the ima_tpm_chip. On failure, > > > > > > instead of going into TPM-bypass mode, return immediately. There are no calls > > > > > > to anything else. Just call ima_init() a second time. > > > > > > > > > > I’m not fully convinced this is sufficient. > > > > > > > > > > What I meant is the case where ima_init() fails due to other > > > > > initialisation steps, not only tpm_default_chip() (e.g. ima_fs_init()). > > > > > > > > The purpose of THIS patch is to add late_initcall_sync, when the TPM is not > > > > available at late_initcall. This would be classified as a bug fix and would be > > > > backported. No other changes should be included in this patch. > > > > > > Okay. > > > > > > > > > > > > > I’d also like to ask again whether it is fine to call > > > > > ima_update_policy_flags() and keep the notifier registered in the > > > > > deferred TPM case. While this may be functionally acceptable, it seems > > > > > logically questionable to do so when ima_init() has not completed. > > > > > > > > Other than extending the TPM, IMA should behave exactly the same whether there > > > > is a TPM or goes into TPM-bypass mode. > > > > > > > > > > > > > > There is also a possibility that a deferred case ultimately fails (e.g. > > > > > deferred at late_initcall, but then failing at late_initcall_sync > > > > > for another reason, even while entering TPM bypass mode). In that case, > > > > > it seems more appropriate to handle this state in the caller of > > > > > ima_init(), rather than inside ima_init() itself. > > > > > > > > If the TPM isn't found at late_initcall_sync(), then IMA should go into TPM- > > > > bypass mode. Please don't make any other changes to the existing IMA behavior > > > > and hide it here behind the late_initcall_sync change. > > > > > > Okay. you're talking called ima_update_policy_flags() at late_initcall > > > wouldn't be not a problem even in case of late_initcall_sync's ima_init() > > > get failed with "TPM-bypass mode". > > > > > > I see then, I'll make a patch simpler then. > > > > But I think in case of below situation: > > - late_initcall's first ima_init() is deferred. > > - late_initcall_sync try again but failed and try again with > > CONFIG_IMA_DEFAULT_HASH. > > > > I would like to sustain init_ima_core to reduce the same code repeat > > in late_initcall_sync. > > I think what Mimi's proposing is: > > If we're in late_initcall, and the TPM isn't available, return immediately > with an error (the EPROBE_DEFER?), don't do any init. > > If we're in late_initcall_sync, either we're already initialised, so do > return and nothing, or run through the entire flow, even if the TPM isn't > unavailable. > > So ima_init() just needs to know a) if it's in the sync or non-sync mode and > b) for the sync mode, if we've already done the init at > non-sync. But think think about when "late_initcall_sync" happens. In case of it, whether TPM present or by-pass mode, if it failed, it try again with the DEFAULT_HASH if hash isn't use DEFAULT one (e.x. user set boot arguments hash_setup=md5). IOW, late_initcall_sync should call twice just like former code do this. I mean to wrap this duplication of code with init_core_ima(). so that int late_initcall_sync in case of deferred case to try agina ima_init() with the DEFAULT HASH. -- Sincerely, Yeoreum Yun