From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Fri, 23 Jul 2021 16:30:10 +0200 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1m6wBm-00077e-Nw for lore@lore.pengutronix.de; Fri, 23 Jul 2021 16:30:10 +0200 Received: from localhost ([127.0.0.1] helo=metis.ext.pengutronix.de) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1m6wBm-00029N-Bw; Fri, 23 Jul 2021 16:30:10 +0200 Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1m6wBa-000234-LM; Fri, 23 Jul 2021 16:29:58 +0200 Received: from rhi by dude.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1m6wBa-0008KP-Cg; Fri, 23 Jul 2021 16:29:58 +0200 From: Roland Hieber To: ptxdist@pengutronix.de Date: Fri, 23 Jul 2021 16:29:55 +0200 Message-Id: <20210723142956.31879-2-rhi@pengutronix.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210723142956.31879-1-rhi@pengutronix.de> References: <20210723142956.31879-1-rhi@pengutronix.de> MIME-Version: 1.0 Mail-Followup-To: Roland Hieber , ptxdist@pengutronix.de Subject: [ptxdist] [PATCH v2 2/3] kernel: add support for module signing X-BeenThere: ptxdist@pengutronix.de X-Mailman-Version: 2.1.29 Precedence: list List-Id: PTXdist Development Mailing List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: ptxdist@pengutronix.de Cc: Roland Hieber Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "ptxdist" X-SA-Exim-Connect-IP: 127.0.0.1 X-SA-Exim-Mail-From: ptxdist-bounces@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false Use the code signing role 'kernel-modules' to supply the kernel with the key for kernel module singing. This only works if kernel module signing is enabled in the kernel config file, so write a short paragraph for the "daily use" chapter in the docs what has to be considered when using module signing in PTXdist. Signed-off-by: Roland Hieber --- PATCH v2: - rebase to current master - split trusted key handling into its own patch (see previous patch) - add CONFIG_MODULE_SIG_KEY to KENREL_BASE_OPT instead of KERNEL_SIGN_OPT, and only if module signing is enabled in the platformconfig - fix some typos and adapt documentation PATCH v1: https://lore.ptxdist.org/ptxdist/20210719183053.3799-1-rhi@pengutronix.de doc/daily_work.inc | 38 ++++++++++++++++++++++++++++++++++++++ platforms/kernel.in | 15 +++++++++++++++ rules/kernel.make | 4 ++++ 3 files changed, 57 insertions(+) diff --git a/doc/daily_work.inc b/doc/daily_work.inc index 4562b5ca70b9..37bb9bc48180 100644 --- a/doc/daily_work.inc +++ b/doc/daily_work.inc @@ -157,6 +157,44 @@ add those certificates to the kernel trust root. :ref:`cs_append_ca_from_pem`, or :ref:`cs_append_ca_from_uri` with the ``kernel-trusted`` role to supply those certificates.) +Note that the kernel also always adds the module signing key to the trust root +(see :ref:`kernel_module_signing` below). +If the EVM key is signed by the module signing key (or if the two keys are the +same *and* it is self-signed), no additional trust CA is necessary. + +.. _kernel_module_signing: + +Kernel Module Signing +~~~~~~~~~~~~~~~~~~~~~ + +The kernel's build system can generate cryptographic signatures for all +kernel modules during the build process. +This can ensure that all modules loaded on the target at runtime have been +built by a trustworthy source. + +If ``PTXCONF_KERNEL_MODULES_SIGN`` ("sign modules") is enabled in the +platformconfig, PTXdist augments the kernel config with the following config +options during the `kernel.compile` and `kernel.install` stages: + +* ``CONFIG_MODULE_SIG_KEY`` ("File name or PKCS#11 URI of module signing key"): + PTXdist supplies the URI from the ``kernel-modules`` role of the configured + code signing provider. + (The code signing provider should use :ref:`cs_set_uri` to set the URI.) + +However, additional settings must also be enabled in the kernel config: + +* ``CONFIG_MODULE_SIG=y`` ("Module signature verification"): + Enable this option for module signing, and to get access to its sub-options. +* ``CONFIG_MODULE_SIG_ALL=y`` ("Automatically sign all modules"): + Enable this option so that the kernel's build system signs the modules during + PTXdist's `kernel.install` stage. +* Additionally, ``CONFIG_MODULE_SIG_FORCE`` ("Require modules to be validly + signed") can be useful so that the kernel refuses loading modules with + invalid, untrusted, or no signature. + +For the full overview, refer to the `kernel's module signing documentation +`_. + Discovering Runtime Dependencies -------------------------------- diff --git a/platforms/kernel.in b/platforms/kernel.in index 8fe47b741fa7..ff3cc8df4f47 100644 --- a/platforms/kernel.in +++ b/platforms/kernel.in @@ -39,6 +39,21 @@ config KERNEL_MODULES_INSTALL prompt "Install modules into /lib/modules" depends on KERNEL_MODULES +config KERNEL_MODULES_SIGN + bool + depends on KERNEL_MODULES + select KERNEL_CODE_SIGNING + select KERNEL_MODULES_INSTALL + prompt "sign modules" + help + If enabled, kernel modules are signed during the install stage with + the key specified by the code signing provider in the "kernel-modules" + role. + + See the section "Kernel module signing" in the "Daily Work" chapter in + the PTXdist manual for use cases and more infos about what needs to be + enabled in the kernel config file. + config KERNEL_VERSION prompt "kernel version" string diff --git a/rules/kernel.make b/rules/kernel.make index ac27450832df..9caff677918e 100644 --- a/rules/kernel.make +++ b/rules/kernel.make @@ -76,6 +76,10 @@ KERNEL_BASE_OPT += \ $(if $(shell cs_get_ca kernel-trusted), \ CONFIG_SYSTEM_TRUSTED_KEYS=$(shell cs_get_ca kernel-trusted)) endif +ifdef PTXCONF_KERNEL_MODULES_SIGN +KERNEL_BASE_OPT += \ + CONFIG_MODULE_SIG_KEY='"$(shell cs_get_uri kernel-modules)"' +endif # Intermediate option. This will be used by kernel module packages. KERNEL_MODULE_OPT = \ -- 2.30.2 _______________________________________________ ptxdist mailing list ptxdist@pengutronix.de To unsubscribe, send a mail with subject "unsubscribe" to ptxdist-request@pengutronix.de