From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: David Howells <dhowells@redhat.com>

Date: Tue, 27 Feb 2018 10:04:55 +0000

Subject: [PATCH] efi: Add an EFI_SECURE_BOOT flag to indicate secure boot mode

UEFI machines can be booted in Secure Boot mode.  Add an EFI_SECURE_BOOT

flag that can be passed to efi_enabled() to find out whether secure boot is

enabled.

Move the switch-statement in x86's setup_arch() that inteprets the

secure_boot boot parameter to generic code and set the bit there.

Upstream Status: RHEL only

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Signed-off-by: David Howells <dhowells@redhat.com>

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

cc: linux-efi@vger.kernel.org

[Rebased for context; efi_is_table_address was moved to arch/x86]

Signed-off-by: Jeremy Cline <jcline@redhat.com>

---

 arch/x86/kernel/setup.c           | 14 +-----------

 drivers/firmware/efi/Makefile     |  1 +

 drivers/firmware/efi/secureboot.c | 38 +++++++++++++++++++++++++++++++

 include/linux/efi.h               | 18 ++++++++++-----

 4 files changed, 52 insertions(+), 19 deletions(-)

 create mode 100644 drivers/firmware/efi/secureboot.c

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c

index 112efbef3414..c9de4b36ca51 100644

--- a/arch/x86/kernel/setup.c

+++ b/arch/x86/kernel/setup.c

@@ -1255,19 +1255,7 @@ void __init setup_arch(char **cmdline_p)

 	/* Allocate bigger log buffer */

 	setup_log_buf(1);

-	if (efi_enabled(EFI_BOOT)) {

-		switch (boot_params.secure_boot) {

-		case efi_secureboot_mode_disabled:

-			pr_info("Secure boot disabled\n");

-			break;

-		case efi_secureboot_mode_enabled:

-			pr_info("Secure boot enabled\n");

-			break;

-		default:

-			pr_info("Secure boot could not be determined\n");

-			break;

-		}

-	}

+	efi_set_secure_boot(boot_params.secure_boot);

 	reserve_initrd();

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile

index 7a216984552b..f0ef02d733af 100644

--- a/drivers/firmware/efi/Makefile

+++ b/drivers/firmware/efi/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_EFI_FAKE_MEMMAP)		+= fake_map.o

 obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o

 obj-$(CONFIG_EFI_TEST)			+= test/

 obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o

+obj-$(CONFIG_EFI)			+= secureboot.o

 obj-$(CONFIG_APPLE_PROPERTIES)		+= apple-properties.o

 obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2-table.o

 obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE)	+= embedded-firmware.o

diff --git a/drivers/firmware/efi/secureboot.c b/drivers/firmware/efi/secureboot.c

new file mode 100644

index 000000000000..de0a3714a5d4

--- /dev/null

+++ b/drivers/firmware/efi/secureboot.c

@@ -0,0 +1,38 @@

+/* Core kernel secure boot support.

+ *

+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.

+ * Written by David Howells (dhowells@redhat.com)

+ *

+ * This program is free software; you can redistribute it and/or

+ * modify it under the terms of the GNU General Public Licence

+ * as published by the Free Software Foundation; either version

+ * 2 of the Licence, or (at your option) any later version.

+ */

+

+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+

+#include <linux/efi.h>

+#include <linux/kernel.h>

+#include <linux/printk.h>

+

+/*

+ * Decide what to do when UEFI secure boot mode is enabled.

+ */

+void __init efi_set_secure_boot(enum efi_secureboot_mode mode)

+{

+	if (efi_enabled(EFI_BOOT)) {

+		switch (mode) {

+		case efi_secureboot_mode_disabled:

+			pr_info("Secure boot disabled\n");

+			break;

+		case efi_secureboot_mode_enabled:

+			set_bit(EFI_SECURE_BOOT, &efi.flags);

+			pr_info("Secure boot enabled\n");

+			break;

+		default:

+			pr_warn("Secure boot could not be determined (mode %u)\n",

+				   mode);

+			break;

+		}

+	}

+}

diff --git a/include/linux/efi.h b/include/linux/efi.h

index 92aa4697f558..1cdc5d8b6ac3 100644

--- a/include/linux/efi.h

+++ b/include/linux/efi.h

@@ -785,6 +785,14 @@ extern int __init efi_setup_pcdp_console(char *);

 #define EFI_MEM_ATTR		10	/* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */

 #define EFI_MEM_NO_SOFT_RESERVE	11	/* Is the kernel configured to ignore soft reservations? */

 #define EFI_PRESERVE_BS_REGIONS	12	/* Are EFI boot-services memory segments available? */

+#define EFI_SECURE_BOOT		13	/* Are we in Secure Boot mode? */

+

+enum efi_secureboot_mode {

+	efi_secureboot_mode_unset,

+	efi_secureboot_mode_unknown,

+	efi_secureboot_mode_disabled,

+	efi_secureboot_mode_enabled,

+};

 #ifdef CONFIG_EFI

 /*

@@ -796,6 +804,8 @@ static inline bool efi_enabled(int feature)

 }

 extern void efi_reboot(enum reboot_mode reboot_mode, const char *__unused);

+extern void __init efi_set_secure_boot(enum efi_secureboot_mode mode);

+

 bool __pure __efi_soft_reserve_enabled(void);

 static inline bool __pure efi_soft_reserve_enabled(void)

@@ -822,6 +832,8 @@ efi_capsule_pending(int *reset_type)

 	return false;

 }

+static inline void efi_set_secure_boot(enum efi_secureboot_mode mode) {}

+

 static inline bool efi_soft_reserve_enabled(void)

 {

 	return false;

@@ -1094,12 +1106,6 @@ static inline bool efi_runtime_disabled(void) { return true; }

 extern void efi_call_virt_check_flags(unsigned long flags, const char *call);

 extern unsigned long efi_call_virt_save_flags(void);

-enum efi_secureboot_mode {

-	efi_secureboot_mode_unset,

-	efi_secureboot_mode_unknown,

-	efi_secureboot_mode_disabled,

-	efi_secureboot_mode_enabled,

-};

 enum efi_secureboot_mode efi_get_secureboot(void);

 #ifdef CONFIG_RESET_ATTACK_MITIGATION

-- 

2.28.0