From e1ac4b2406d94eddce8ac2c5ab4235f6075a9602 Mon Sep 17 00:00:00 2001 From: Chester Lin Date: Fri, 30 Oct 2020 14:08:38 +0800 Subject: [PATCH] efi: generalize efi_get_secureboot Generalize the efi_get_secureboot() function so not only efistub but also other subsystems can use it. Note that the MokSbState handling is not factored out: the variable is boot time only, and so it cannot be parameterized as easily. Also, the IMA code will switch to this version in a future patch, and it does not incorporate the MokSbState exception in the first place. Note that the new efi_get_secureboot_mode() helper treats any failures to read SetupMode as setup mode being disabled. Co-developed-by: Chester Lin Signed-off-by: Chester Lin Acked-by: Mimi Zohar Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/Makefile | 2 +- drivers/firmware/efi/libstub/efistub.h | 2 ++ drivers/firmware/efi/libstub/secureboot.c | 41 +++++++++++-------------------- include/linux/efi.h | 23 ++++++++++++++++- 4 files changed, 40 insertions(+), 28 deletions(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index ee24908..8d358a6 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -35,7 +35,7 @@ cflags-$(CONFIG_X86_32) := -march=i386 cflags-$(CONFIG_X86_64) := -mcmodel=small -mno-red-zone KBUILD_CFLAGS += $(cflags-y) KBUILD_CFLAGS += -mno-mmx -mno-sse -KBUILD_CFLAGS += -ffreestanding +KBUILD_CFLAGS += -ffreestanding -fshort-wchar KBUILD_CFLAGS += -fno-stack-protector KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) KBUILD_CFLAGS += $(call cc-disable-warning, gnu) diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index 2d7abcd..b8ec29d 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -848,4 +848,6 @@ asmlinkage void __noreturn efi_enter_kernel(unsigned long entrypoint, void efi_handle_post_ebs_state(void); +enum efi_secureboot_mode efi_get_secureboot(void); + #endif diff --git a/drivers/firmware/efi/libstub/secureboot.c b/drivers/firmware/efi/libstub/secureboot.c index 5efc524..af18d86 100644 --- a/drivers/firmware/efi/libstub/secureboot.c +++ b/drivers/firmware/efi/libstub/secureboot.c @@ -12,15 +12,16 @@ #include "efistub.h" -/* BIOS variables */ -static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID; -static const efi_char16_t efi_SecureBoot_name[] = L"SecureBoot"; -static const efi_char16_t efi_SetupMode_name[] = L"SetupMode"; - /* SHIM variables */ static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID; static const efi_char16_t shim_MokSBState_name[] = L"MokSBState"; +static efi_status_t get_var(efi_char16_t *name, efi_guid_t *vendor, u32 *attr, + unsigned long *data_size, void *data) +{ + return get_efi_var(name, vendor, attr, data_size, data); +} + /* * Determine whether we're in secure boot mode. * @@ -30,26 +31,18 @@ static const efi_char16_t shim_MokSBState_name[] = L"MokSBState"; enum efi_secureboot_mode efi_get_secureboot(void) { u32 attr; - u8 secboot, setupmode, moksbstate; unsigned long size; + enum efi_secureboot_mode mode; efi_status_t status; + u8 moksbstate; - size = sizeof(secboot); - status = get_efi_var(efi_SecureBoot_name, &efi_variable_guid, - NULL, &size, &secboot); - if (status == EFI_NOT_FOUND) - return efi_secureboot_mode_disabled; - if (status != EFI_SUCCESS) - goto out_efi_err; - - size = sizeof(setupmode); - status = get_efi_var(efi_SetupMode_name, &efi_variable_guid, - NULL, &size, &setupmode); - if (status != EFI_SUCCESS) - goto out_efi_err; - - if (secboot == 0 || setupmode == 1) - return efi_secureboot_mode_disabled; + mode = efi_get_secureboot_mode(get_var); + if (mode == efi_secureboot_mode_unknown) { + efi_err("Could not determine UEFI Secure Boot status.\n"); + return efi_secureboot_mode_unknown; + } + if (mode != efi_secureboot_mode_enabled) + return mode; /* * See if a user has put the shim into insecure mode. If so, and if the @@ -69,8 +62,4 @@ enum efi_secureboot_mode efi_get_secureboot(void) secure_boot_enabled: efi_info("UEFI Secure Boot is enabled.\n"); return efi_secureboot_mode_enabled; - -out_efi_err: - efi_err("Could not determine UEFI Secure Boot status.\n"); - return efi_secureboot_mode_unknown; } diff --git a/include/linux/efi.h b/include/linux/efi.h index d7c0e73..1cd5d91 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1089,7 +1089,28 @@ enum efi_secureboot_mode { efi_secureboot_mode_disabled, efi_secureboot_mode_enabled, }; -enum efi_secureboot_mode efi_get_secureboot(void); + +static inline +enum efi_secureboot_mode efi_get_secureboot_mode(efi_get_variable_t *get_var) +{ + u8 secboot, setupmode = 0; + efi_status_t status; + unsigned long size; + + size = sizeof(secboot); + status = get_var(L"SecureBoot", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, + &secboot); + if (status == EFI_NOT_FOUND) + return efi_secureboot_mode_disabled; + if (status != EFI_SUCCESS) + return efi_secureboot_mode_unknown; + + size = sizeof(setupmode); + get_var(L"SetupMode", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, &setupmode); + if (secboot == 0 || setupmode == 1) + return efi_secureboot_mode_disabled; + return efi_secureboot_mode_enabled; +} #ifdef CONFIG_RESET_ATTACK_MITIGATION void efi_enable_reset_attack_mitigation(void); -- 2.7.4