Commit e1ac4b24 authored by Chester Lin's avatar Chester Lin Committed by Ard Biesheuvel
Browse files

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: default avatarChester Lin <clin@suse.com>
Signed-off-by: default avatarChester Lin <clin@suse.com>
Acked-by: default avatarMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 6edcf9dc

arch/x86/boot/compressed/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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)

drivers/firmware/efi/libstub/efistub.h

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/firmware/efi/libstub/secureboot.c

+15 −26
Original line number Diff line number Diff line
@@ -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;

}

include/linux/efi.h

+22 −1
Original line number Diff line number Diff line
@@ -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);

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