[PATCH 4/5] efi: Lock down the kernel if booted in secure boot mode
From: dhowells@redhat.com (David Howells)
Date: 2017-05-24 14:46:06
Also in:
linux-efi, lkml
Subsystem:
extensible firmware interface (efi), the rest · Maintainers:
Ard Biesheuvel, Linus Torvalds
UEFI Secure Boot provides a mechanism for ensuring that the firmware will only load signed bootloaders and kernels. Certain use cases may also require that all kernel modules also be signed. Add a configuration option that to lock down the kernel - which includes requiring validly signed modules - if the kernel is secure-booted. Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-efi at vger.kernel.org --- drivers/firmware/efi/Kconfig | 1 + drivers/firmware/efi/secureboot.c | 10 +++++++++- 2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index c40fdeaf9a45..d03af2d5f52f 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig@@ -87,6 +87,7 @@ config EFI_RUNTIME_WRAPPERS config EFI_SECURE_BOOT bool "Support UEFI Secure Boot and lock down the kernel in secure boot mode" default n + select LOCK_DOWN_KERNEL help UEFI Secure Boot provides a mechanism for ensuring that the firmware will only load signed bootloaders and kernels. Secure boot mode may
diff --git a/drivers/firmware/efi/secureboot.c b/drivers/firmware/efi/secureboot.c
index 730518061a14..7292a3b832e3 100644
--- a/drivers/firmware/efi/secureboot.c
+++ b/drivers/firmware/efi/secureboot.c@@ -12,6 +12,7 @@ #include <linux/efi.h> #include <linux/kernel.h> #include <linux/printk.h> +#include <linux/security.h> /* * Decide what to do when UEFI secure boot mode is enabled.
@@ -23,10 +24,17 @@ void __init efi_set_secure_boot(enum efi_secureboot_mode mode) 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"); + if (IS_ENABLED(CONFIG_LOCK_DOWN_KERNEL)) { + lock_kernel_down(); + pr_info("Secure boot enabled and kernel locked down\n"); + } else { + pr_info("Secure boot enabled\n"); + } break; + default: pr_info("Secure boot could not be determined\n"); break; --
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