From patchwork Tue Oct 15 22:22:31 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeremy Linton X-Patchwork-Id: 13837333 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E21DD21E3DB; Tue, 15 Oct 2024 22:22:54 +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=1729030977; cv=none; b=BARBFdB4jjSsy32lYy+qIS89SsasddG1QDsOWuppAAqIh3I0LbU1420AlBW6FTDH41MBKwBstBCneMSKIYXfVORuKWwQNmHrk/6Ux8/6V59K2JnbzofTQBmhcFres5al2wt8TCB3YsIq3F1rYV72Bmd/6VGZuPoCH71mXbqjWow= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729030977; c=relaxed/simple; bh=a/9waGCx6zmCoPndDtrnBw09clAutUJbVmjhCyxxTzI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=vDG9QERH4P59SbzhB+5vjg5wPmK7MUGh97bFxJsVIx4iGu4n+ucoAnD0tccVJJKNNPhyhMZEP2nPq8BwHhuZvg0SxFiW7p46AHcf9oKUrpi+VgfYkHKbBDcafaFkNh95wPXSgpm0/GerA0sKCXvYwIqeoZfCmPUa2CfKeqsgLek= 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 CB6D71007; Tue, 15 Oct 2024 15:23:23 -0700 (PDT) Received: from u200865.usa.arm.com (U203867.austin.arm.com [10.118.30.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 226023F71E; Tue, 15 Oct 2024 15:22:54 -0700 (PDT) From: Jeremy Linton To: linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, hch@lst.de, gregkh@linuxfoundation.org, graf@amazon.com, lukas@wunner.de, wufan@linux.microsoft.com, brauner@kernel.org, jsperbeck@google.com, ardb@kernel.org, linux-crypto@vger.kernel.org, linux-kbuild@vger.kernel.org, keyrings@vger.kernel.org, Jeremy Linton Subject: [RFC 1/5] initramfs: Add initramfs signature checking Date: Tue, 15 Oct 2024 17:22:31 -0500 Message-ID: <20241015222235.71040-2-jeremy.linton@arm.com> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241015222235.71040-1-jeremy.linton@arm.com> References: <20241015222235.71040-1-jeremy.linton@arm.com> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Various root-level processes, configurations, and the like can exist in the initramfs provided by the boot loader. The kernel does a reasonable job of signature checking and blocking unsigned code from running in the kernel, but this is only one aspect of system security. The remaining init and early startup code running in userspace are just as critical to system security. This option provides a basic initramfs signature check, which reuses the module signature checking infrastructure to validate the boot loader provided initramfs. Later, a system policy can allow or deny images that fail the signature check. Signed-off-by: Jeremy Linton --- usr/Kconfig | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/usr/Kconfig b/usr/Kconfig index 9279a2893ab0..a9c0dc0112eb 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -32,6 +32,15 @@ config INITRAMFS_FORCE and is useful if you cannot or don't want to change the image your bootloader passes to the kernel. +config INITRAMFS_SIG + bool "Validate signed initramfs images" + depends on SYSTEM_DATA_VERIFICATION + help + This option validates that image provided by the + bootloader is signed. The decision to accept or + reject the image is then left to the kernel lockdown + logic. + config INITRAMFS_ROOT_UID int "User ID to map to 0 (user root)" depends on INITRAMFS_SOURCE!=""