[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
cc: linux-...@vger.kernel.org
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");

[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
cc: linux-...@vger.kernel.org
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");

[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");

[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");

[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");

[PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode

[David Howells]

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 
---

 arch/x86/Kconfig|   12 
 arch/x86/kernel/setup.c |8 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..21f39855661d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1817,6 +1817,18 @@ config EFI_MIXED
 
   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+   def_bool n
+   depends on EFI
+   prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+   ---help---
+ 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 and that
+ userspace is prevented from directly changing the running kernel
+ image.  Say Y here to automatically lock down the kernel when a
+ system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 396285bddb93..85dfa745c442 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 
@@ -1185,7 +1186,12 @@ void __init setup_arch(char **cmdline_p)
break;
case efi_secureboot_mode_enabled:
set_bit(EFI_SECURE_BOOT, );
-   pr_info("Secure boot enabled\n");
+   if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+   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");