[PATCH 8/8] efi: Add EFI_SECURE_BOOT bit [ver #6]

From: David Howells
Date: Thu Dec 08 2016 - 07:31:16 EST


From: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>

UEFI machines can be booted in Secure Boot mode. Add a EFI_SECURE_BOOT bit
that can be passed to efi_enabled() to find out whether secure boot is
enabled.

This will be used by the SysRq+x handler, registered by the x86 arch, to find
out whether secure boot mode is enabled so that it can be disabled.

Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

arch/x86/kernel/setup.c | 15 +++++++++++++++
include/linux/efi.h | 1 +
2 files changed, 16 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 9c337b0e8ba7..d8972ec6257d 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1152,6 +1152,21 @@ void __init setup_arch(char **cmdline_p)
/* Allocate bigger log buffer */
setup_log_buf(1);

+ if (IS_ENABLED(CONFIG_EFI)) {
+ switch (boot_params.secure_boot) {
+ 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_info("Secure boot could not be determined\n");
+ break;
+ }
+ }
+
reserve_initrd();

acpi_table_upgrade();
diff --git a/include/linux/efi.h b/include/linux/efi.h
index c894ed5bfa1c..e1893f5002c3 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1070,6 +1070,7 @@ extern int __init efi_setup_pcdp_console(char *);
#define EFI_ARCH_1 7 /* First arch-specific bit */
#define EFI_DBG 8 /* Print additional debug info at runtime */
#define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */
+#define EFI_SECURE_BOOT 10 /* Are we in Secure Boot mode? */

#ifdef CONFIG_EFI
/*