From nobody Sun Feb 8 21:56:06 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9537325F985; Tue, 10 Jun 2025 06:03:42 +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=1749535425; cv=none; b=FjcUEmxScP1TLzgLxJkLkUQLUGVfI6NLyWx4Kr1XFIGLNcw2DurJeBZpoMjxG1o80ptC1+NVrNnbd2PlCD7Q15EwHWSGrTNTWcew1sGjfoLE3a0BkIwfW4FLAY2shHX+lLQARr0380Uwn1E1J4tRIyKd/n9HelO4Z0BBakn57Bg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749535425; c=relaxed/simple; bh=XFETnRwJszuY33IPOx4LdCSnsksBJu52kllSSQvTpnE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=PuiWCrOVfdWnnTsExPjVFoNIMkZXE4xC8n70mekM+BP3lElw1x/DZqmayi+z4J0HUbRm10JA9SJpjl3i0k6uBnoWz2zrJ+259lvSixIOGbeuxoYTcad3zkeWfH3lLh0QRB2svxYSVA6TvguVHLJAiTRi0rBFuQj44A+wBrTMYgw= 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; 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 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 C7D90169E; Mon, 9 Jun 2025 23:03:22 -0700 (PDT) Received: from e129823.cambridge.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 762603F673; Mon, 9 Jun 2025 23:03:40 -0700 (PDT) From: Yeoreum Yun To: jarkko@kernel.org, sudeep.holla@arm.com, peterhuewe@gmx.de, jgg@ziepe.ca, stuart.yoder@arm.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, Yeoreum Yun Subject: [PATCH v2 1/2] firmware: arm_ffa: Change initcall level of ffa_init() to rootfs_initcall Date: Tue, 10 Jun 2025 07:03:33 +0100 Message-Id: <20250610060334.2149041-2-yeoreum.yun@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250610060334.2149041-1-yeoreum.yun@arm.com> References: <20250610060334.2149041-1-yeoreum.yun@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The Linux IMA (Integrity Measurement Architecture) subsystem used for secure boot, file integrity, or remote attestation cannot be a loadable module for few reasons listed below: o Boot-Time Integrity: IMA=E2=80=99s main role is to measure and appraise = files before they are used. This includes measuring critical system files duri= ng early boot (e.g., init, init scripts, login binaries). If IMA were a mod= ule, it would be loaded too late to cover those. o TPM Dependency: IMA integrates tightly with the TPM to record measuremen= ts into PCRs. The TPM must be initialized early (ideally before init_ima()), which aligns with IMA being built-in. o Security Model: IMA is part of a Trusted Computing Base (TCB). Making it= a module would weaken the security model, as a potentially compromised sys= tem could delay or tamper with its initialization. IMA must be built-in to ensure it starts measuring from the earliest possib= le point in boot which inturn implies TPM must be initialised and ready to use before IMA. To enable integration of tpm_event_log with the IMA subsystem, the TPM driv= ers (tpm_crb and tpm_crb_ffa) also needs to be built-in. However with FF-A driv= er also being initialised at device initcall level, it can lead to an initialization order issue where: - crb_acpi_driver_init() may run before tpm_crb_ffa_driver()_init and ffa_= init() - As a result, probing the TPM device via CRB over FFA is deferred - ima_init() (called as a late initcall) runs before deferred probe comple= tes, IMA fails to find the TPM and logs the below error: | ima: No TPM chip found, activating TPM-bypass! Eventually it fails to generate boot_aggregate with PCR values. Because of the above stated dependency, the ffa driver needs to initialised before tpm_crb_ffa module to ensure IMA finds the TPM successfully when present. Signed-off-by: Yeoreum Yun --- drivers/firmware/arm_ffa/driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/d= river.c index fe55613a8ea9..1a690b8186df 100644 --- a/drivers/firmware/arm_ffa/driver.c +++ b/drivers/firmware/arm_ffa/driver.c @@ -2058,7 +2058,7 @@ static int __init ffa_init(void) kfree(drv_info); return ret; } -module_init(ffa_init); +rootfs_initcall(ffa_init); =20 static void __exit ffa_exit(void) { --=20 LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} From nobody Sun Feb 8 21:56:06 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 608CA2620E5; Tue, 10 Jun 2025 06:03:44 +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=1749535427; cv=none; b=ICIxLQVph4KqvJEYafCWbg5/c80+eOTwN3AMmdQxCSlobGE5di4LwfvcqJOQz3m1u6T8emVN468aJxd3Tvz1lJpkVcMO2hKedPyBWfeLqJHZu09QP+e0pdx1pAlYMj4UF0Jkrmy8co03me0Yq0LPimppW50QtppGK26OypJpDsQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749535427; c=relaxed/simple; bh=Wk4ic3cKCwA/CUwVZNrW0uVYklt7Lox9BLDg1LmmMGU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=r9iZhCdwQMYfu0z+MrU51Igu+OnFKMhpZhnv6LRxlmgPFtSUjcezq96RJy2uzh+IY6fCZ9/ANppB02nd3h1u9nBrxYVGCE+a/AHUhKG4ooIAoEGRL+Rxk+i6PRgR7vwbKRXVhx0dJ6BWKQiwMnuh7ZS2K3hRMFxwJ2wJkL27Y2A= 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; 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 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 9008B16A3; Mon, 9 Jun 2025 23:03:24 -0700 (PDT) Received: from e129823.cambridge.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 416103F673; Mon, 9 Jun 2025 23:03:42 -0700 (PDT) From: Yeoreum Yun To: jarkko@kernel.org, sudeep.holla@arm.com, peterhuewe@gmx.de, jgg@ziepe.ca, stuart.yoder@arm.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, Yeoreum Yun Subject: [PATCH v2 2/2] tpm: tpm_crb_ffa: manually register tpm_crb_ffa driver when it's built-in Date: Tue, 10 Jun 2025 07:03:34 +0100 Message-Id: <20250610060334.2149041-3-yeoreum.yun@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250610060334.2149041-1-yeoreum.yun@arm.com> References: <20250610060334.2149041-1-yeoreum.yun@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To integrate tpm_event_log with IMA subsystem, tpm_crb and tpm_crb_ffa driver should be built as built-in (CONFIG_TCG_CRB=3Dy && CONFIG_TCG_CRB_FFA=3Dy) and TPM device using CRB over FF-A should be probed before ima_init() which is called as late_initcall. However, we couldn't control the probing order between crb_acpi_driver_init() and tpm_crb_ffa_driver_init() that's why crb_acpi_driver_init() could be called before tpm_crb_ffa_driver_init() when they're deployed like: 0000000000000888 l .initcall6.init>-0000000000000000 crb_acpi_driver_= init 000000000000088c l .initcall6.init>-0000000000000000 tpm_crb_ffa_driv= er_init In this situation, the TPM device is queued deferred probing and it can be handled later ima_init() caled in init_ima(). 000000000000012c l .initcall7.init>-0000000000000000 init_ima 000000000000016c l .initcall7.init>-0000000000000000 deferred_probe_i= nitcall7 When this happen, IMA fails to generate boot_aggregate with TPM's PCR values so it prints below message: | ima: No TPM chip found, activating TPM-bypass! To resolve this issue, the tpm_crb_ffa_init() function attempts to probe the tpm_crb_ffa device. This ensures that the TPM device using CRB over FF-A can be successfully probed even if crb_acpi_driver_init() is called first. Signed-off-by: Yeoreum Yun --- drivers/char/tpm/tpm_crb_ffa.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c index 4ead61f01299..2ef29b66fa5d 100644 --- a/drivers/char/tpm/tpm_crb_ffa.c +++ b/drivers/char/tpm/tpm_crb_ffa.c @@ -115,6 +115,7 @@ struct tpm_crb_ffa { }; static struct tpm_crb_ffa *tpm_crb_ffa; +static struct ffa_driver tpm_crb_ffa_driver; static int tpm_crb_ffa_to_linux_errno(int errno) { @@ -168,13 +169,22 @@ static int tpm_crb_ffa_to_linux_errno(int errno) */ int tpm_crb_ffa_init(void) { - if (!tpm_crb_ffa) - return -ENOENT; + int ret =3D 0; - if (IS_ERR_VALUE(tpm_crb_ffa)) - return -ENODEV; + if (IS_MODULE(CONFIG_TCG_ARM_CRB_FFA)) { + if (!tpm_crb_ffa) + ret =3D -ENOENT; - return 0; + if (IS_ERR_VALUE(tpm_crb_ffa)) + ret =3D -ENODEV; + + return ret; + } + + ret =3D ffa_register(&tpm_crb_ffa_driver); + BUG_ON(!ret && !tpm_crb_ffa); + + return ret; } EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); @@ -369,7 +379,9 @@ static struct ffa_driver tpm_crb_ffa_driver =3D { .id_table =3D tpm_crb_ffa_device_id, }; +#ifdef MODULE module_ffa_driver(tpm_crb_ffa_driver); +#endif MODULE_AUTHOR("Arm"); MODULE_DESCRIPTION("TPM CRB FFA driver"); -- LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}