From: David Howells Date: Wed, 8 Nov 2017 15:11:37 +0000 Subject: [28/29] efi: Add an EFI_SECURE_BOOT flag to indicate secure boot mode Origin: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit?id=eb4a8603eb727afaeb9c6123eda2eda4b2757bf3 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. Suggested-by: Ard Biesheuvel Signed-off-by: David Howells Reviewed-by: Ard Biesheuvel cc: linux-efi@vger.kernel.org --- arch/x86/kernel/setup.c | 14 +------------- drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/secureboot.c | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/efi.h | 16 ++++++++++------ 4 files changed, 50 insertions(+), 19 deletions(-) create mode 100644 drivers/firmware/efi/secureboot.c Index: linux/arch/x86/kernel/setup.c =================================================================== --- linux.orig/arch/x86/kernel/setup.c +++ linux/arch/x86/kernel/setup.c @@ -1159,19 +1159,7 @@ 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(); Index: linux/drivers/firmware/efi/Makefile =================================================================== --- linux.orig/drivers/firmware/efi/Makefile +++ linux/drivers/firmware/efi/Makefile @@ -24,6 +24,7 @@ obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_m obj-$(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 arm-obj-$(CONFIG_EFI) := arm-init.o arm-runtime.o Index: linux/drivers/firmware/efi/secureboot.c =================================================================== --- /dev/null +++ linux/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 +#include +#include + +/* + * 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_warning("Secure boot could not be determined (mode %u)\n", + mode); + break; + } + } +} Index: linux/include/linux/efi.h =================================================================== --- linux.orig/include/linux/efi.h +++ linux/include/linux/efi.h @@ -1152,6 +1152,14 @@ extern int __init efi_setup_pcdp_console #define EFI_DBG 8 /* Print additional debug info at runtime */ #define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */ #define EFI_MEM_ATTR 10 /* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */ +#define EFI_SECURE_BOOT 11 /* 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 /* @@ -1164,6 +1172,7 @@ static inline bool efi_enabled(int featu extern void efi_reboot(enum reboot_mode reboot_mode, const char *__unused); extern bool efi_is_table_address(unsigned long phys_addr); +extern void __init efi_set_secure_boot(enum efi_secureboot_mode mode); #else static inline bool efi_enabled(int feature) { @@ -1182,6 +1191,7 @@ static inline bool efi_is_table_address( { return false; } +static inline void efi_set_secure_boot(enum efi_secureboot_mode mode) {} #endif extern int efi_status_to_err(efi_status_t status); @@ -1572,12 +1582,6 @@ static inline bool efi_runtime_disabled( extern void efi_call_virt_check_flags(unsigned long flags, const char *call); -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(efi_system_table_t *sys_table); #ifdef CONFIG_RESET_ATTACK_MITIGATION