linux-kernel - [PATCH v10a 1/9] powerpc: detect the secure boot mode of the system

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Message-Id: <46b003b9-3225-6bf7-9101-ed6580bb748c@linux.ibm.com>
Date:   Tue, 5 Nov 2019 17:00:22 -0600
From:   Eric Richter <erichte@...ux.ibm.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, linuxppc-dev@...abs.org,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     Nayna Jain <nayna@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Kerr <jk@...abs.org>,
        "Oliver O'Halloran" <oohall@...il.com>
Subject: [PATCH v10a 1/9] powerpc: detect the secure boot mode of the system

From: Nayna Jain <nayna@...ux.ibm.com>

This patch defines a function to detect the secure boot state of a
PowerNV system.

The PPC_SECURE_BOOT config represents the base enablement of secure boot
for powerpc.

Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
Signed-off-by: Eric Richter <erichte@...ux.ibm.com>
---
v10a:
- moved get_ppc_fw_sb_node to this patch
- updated based on skiboot device tree changes
  - os-secure-enforcing was renamed os-secureboot-enforcing
  - os-secureboot-enforcing was moved to ibm,secureboot
- removed now unnecessary node availibility check

 arch/powerpc/Kconfig                   | 10 ++++++++
 arch/powerpc/include/asm/secure_boot.h | 23 +++++++++++++++++
 arch/powerpc/kernel/Makefile           |  2 ++
 arch/powerpc/kernel/secure_boot.c      | 34 ++++++++++++++++++++++++++
 4 files changed, 69 insertions(+)
 create mode 100644 arch/powerpc/include/asm/secure_boot.h
 create mode 100644 arch/powerpc/kernel/secure_boot.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3e56c9c2f16e..56ea0019b616 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -934,6 +934,16 @@ config PPC_MEM_KEYS
 
 	  If unsure, say y.
 
+config PPC_SECURE_BOOT
+	prompt "Enable secure boot support"
+	bool
+	depends on PPC_POWERNV
+	help
+	  Systems with firmware secure boot enabled need to define security
+	  policies to extend secure boot to the OS. This config allows a user
+	  to enable OS secure boot on systems that have firmware support for
+	  it. If in doubt say N.
+
 endmenu
 
 config ISA_DMA_API
diff --git a/arch/powerpc/include/asm/secure_boot.h b/arch/powerpc/include/asm/secure_boot.h
new file mode 100644
index 000000000000..07d0fe0ca81f
--- /dev/null
+++ b/arch/powerpc/include/asm/secure_boot.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Secure boot definitions
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain
+ */
+#ifndef _ASM_POWER_SECURE_BOOT_H
+#define _ASM_POWER_SECURE_BOOT_H
+
+#ifdef CONFIG_PPC_SECURE_BOOT
+
+bool is_ppc_secureboot_enabled(void);
+
+#else
+
+static inline bool is_ppc_secureboot_enabled(void)
+{
+	return false;
+}
+
+#endif
+#endif
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index a7ca8fe62368..e2a54fa240ac 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -161,6 +161,8 @@ ifneq ($(CONFIG_PPC_POWERNV)$(CONFIG_PPC_SVM),)
 obj-y				+= ucall.o
 endif
 
+obj-$(CONFIG_PPC_SECURE_BOOT)	+= secure_boot.o
+
 # Disable GCOV, KCOV & sanitizers in odd or sensitive code
 GCOV_PROFILE_prom_init.o := n
 KCOV_INSTRUMENT_prom_init.o := n
diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
new file mode 100644
index 000000000000..3f55be33f5c8
--- /dev/null
+++ b/arch/powerpc/kernel/secure_boot.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain
+ */
+#include <linux/types.h>
+#include <linux/of.h>
+#include <asm/secure_boot.h>
+
+static struct device_node *get_ppc_fw_sb_node(void)
+{
+	static const struct of_device_id ids[] = {
+		{ .compatible = "ibm,secureboot-v1", },
+		{ .compatible = "ibm,secureboot-v2", },
+		{},
+	};
+
+	return of_find_matching_node(NULL, ids);
+}
+
+bool is_ppc_secureboot_enabled(void)
+{
+	struct device_node *node;
+	bool enabled = false;
+
+	node = get_ppc_fw_sb_node();
+	enabled = of_property_read_bool(node, "os-secureboot-enforcing");
+
+	of_node_put(node);
+
+	pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
+
+	return enabled;
+}
-- 
2.20.1