arm64: add kernel config option to lock down when in Secure Boot mode

Add a kernel configuration option to lock down the kernel, to restrict
userspace's ability to modify the running kernel when UEFI Secure Boot is
enabled. Based on the x86 patch by Matthew Garrett.

Determine the state of Secure Boot in the EFI stub and pass this to the
kernel using the FDT.

Signed-off-by: Linn Crosetto <linn@hpe.com>
[bwh: Forward-ported to 4.10: adjust context]
[Lukas Wunner: Forward-ported to 4.11: drop parts applied upstream]
[bwh: Forward-ported to 4.15 and lockdown patch set:
 - Pass result of efi_get_secureboot() in stub through to
   efi_set_secure_boot() in main kernel
 - Use lockdown API and naming]

Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name arm64-add-kernel-config-option-to-lock-down-when.patch

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 80d1a885def5c2dd8bd15591bcc7c62d9b2e3b8c..56ee44ebac30a57cb87946860e046155590ce79f 100644 (file)
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -21,6 +21,7 @@
 #include <linux/of_fdt.h>
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
+#include <linux/security.h>
 
 #include <asm/efi.h>
 
@@ -252,6 +253,9 @@ void __init efi_init(void)
             "Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
              efi.memmap.desc_version);
 
+       efi_set_secure_boot(params.secure_boot);
+       init_lockdown();
+
        if (uefi_init() < 0) {
                efi_memmap_unmap();
                return;

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 232f4915223b519b3ee6580cb08354ac9b0a7016..89f26b721c8f85bd91ab1057d7b54f2f99dbf8e6 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -648,7 +648,8 @@ static __initdata struct params fdt_params[] = {
        UEFI_PARAM("MemMap Address", "linux,uefi-mmap-start", mmap),
        UEFI_PARAM("MemMap Size", "linux,uefi-mmap-size", mmap_size),
        UEFI_PARAM("MemMap Desc. Size", "linux,uefi-mmap-desc-size", desc_size),
-       UEFI_PARAM("MemMap Desc. Version", "linux,uefi-mmap-desc-ver", desc_ver)
+       UEFI_PARAM("MemMap Desc. Version", "linux,uefi-mmap-desc-ver", desc_ver),
+       UEFI_PARAM("Secure Boot Enabled", "linux,uefi-secure-boot", secure_boot)
 };
 
 static __initdata struct params xen_fdt_params[] = {

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 8830fa601e45d9a1b1094419cd1ec66f41a25e49..532b02fbc5d6cbbf5fb7ef826b2dd7903e77b064 100644 (file)
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -158,6 +158,13 @@ static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
                        return efi_status;
                }
        }
+
+       fdt_val32 = cpu_to_fdt32(efi_get_secureboot(sys_table));
+       status = fdt_setprop(fdt, node, "linux,uefi-secure-boot",
+                            &fdt_val32, sizeof(fdt_val32));
+       if (status)
+               goto fdt_set_fail;
+
        return EFI_SUCCESS;
 
 fdt_set_fail:

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 9004e66358889f028479308656fcf5ec6c7b6611..d55d970cfc360c1dd61adcc1db90fdf4ceb34bb1 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -786,6 +786,7 @@ struct efi_fdt_params {
        u32 mmap_size;
        u32 desc_size;
        u32 desc_ver;
+       u32 secure_boot;
 };
 
 typedef struct {