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-rw-r--r--drivers/firmware/efi/libstub/secureboot.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/drivers/firmware/efi/libstub/secureboot.c b/drivers/firmware/efi/libstub/secureboot.c
index b20b8b460d77..6def402bf569 100644
--- a/drivers/firmware/efi/libstub/secureboot.c
+++ b/drivers/firmware/efi/libstub/secureboot.c
@@ -21,6 +21,12 @@ static const efi_char16_t const efi_SetupMode_name[] = {
'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0
};
+/* SHIM variables */
+static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
+static efi_char16_t const shim_MokSBState_name[] = {
+ 'M', 'o', 'k', 'S', 'B', 'S', 't', 'a', 't', 'e', 0
+};
+
#define get_efi_var(name, vendor, ...) \
efi_call_runtime(get_variable, \
(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
@@ -31,7 +37,8 @@ static const efi_char16_t const efi_SetupMode_name[] = {
*/
enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg)
{
- u8 secboot, setupmode;
+ u32 attr;
+ u8 secboot, setupmode, moksbstate;
unsigned long size;
efi_status_t status;
@@ -50,6 +57,22 @@ enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg)
if (secboot == 0 || setupmode == 1)
return efi_secureboot_mode_disabled;
+ /*
+ * See if a user has put the shim into insecure mode. If so, and if the
+ * variable doesn't have the runtime attribute set, we might as well
+ * honor that.
+ */
+ size = sizeof(moksbstate);
+ status = get_efi_var(shim_MokSBState_name, &shim_guid,
+ &attr, &size, &moksbstate);
+
+ /* If it fails, we don't care why. Default to secure */
+ if (status != EFI_SUCCESS)
+ goto secure_boot_enabled;
+ if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS) && moksbstate == 1)
+ return efi_secureboot_mode_disabled;
+
+secure_boot_enabled:
pr_efi(sys_table_arg, "UEFI Secure Boot is enabled.\n");
return efi_secureboot_mode_enabled;