From: David Howells Date: Mon, 18 Feb 2019 12:45:03 +0000 Subject: [28/30] 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=a5d70c55c603233c192b375f72116a395909da28 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 [rperier: Forward-ported to 5.5: - Use pr_warn() - Adjust context] [bwh: Forward-ported to 5.6: adjust context] [bwh: Forward-ported to 5.7: - Use the next available bit in efi.flags - Adjust context] --- arch/x86/kernel/setup.c | 14 +---------- drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/secureboot.c | 39 +++++++++++++++++++++++++++++++ include/linux/efi.h | 16 ++++++++----- 4 files changed, 51 insertions(+), 19 deletions(-) create mode 100644 drivers/firmware/efi/secureboot.c --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1070,19 +1070,7 @@ 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(); --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -25,6 +25,7 @@ subdir-$(CONFIG_EFI_STUB) += libstub obj-$(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 --- /dev/null +++ b/drivers/firmware/efi/secureboot.c @@ -0,0 +1,39 @@ + +/* 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_warn("Secure boot could not be determined (mode %u)\n", + mode); + break; + } + } +} --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -875,6 +875,14 @@ static inline int efi_range_is_wc(unsign #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 /* @@ -899,6 +907,7 @@ static inline bool efi_rt_services_suppo return (efi.runtime_supported_mask & mask) == mask; } extern void efi_find_mirror(void); +extern void __init efi_set_secure_boot(enum efi_secureboot_mode mode); #else static inline bool efi_enabled(int feature) { @@ -918,6 +927,7 @@ static inline bool efi_rt_services_suppo } static inline void efi_find_mirror(void) {} +static inline void efi_set_secure_boot(enum efi_secureboot_mode mode) {} #endif extern int efi_status_to_err(efi_status_t status); @@ -1136,13 +1146,6 @@ static inline bool efi_runtime_disabled( extern void efi_call_virt_check_flags(unsigned long flags, const void *caller); 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, -}; - static inline enum efi_secureboot_mode efi_get_secureboot_mode(efi_get_variable_t *get_var) {