From: Chester Lin <clin@xxxxxxxx>
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 <clin@xxxxxxxx>
Signed-off-by: Chester Lin <clin@xxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
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 ee249088cbfe..8d358a6fe6ec 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 2d7abcd99de9..b8ec29d6a74a 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 5efc524b14be..af18d86c1604 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 bd9d83a94173..79b2d4de62e0 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1082,7 +1082,28 @@ 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);
--
2.17.1
