From: Linn Crosetto <linn@hpe.com>
Date: Tue, 30 Aug 2016 17:54:38 +0000 (-0600)
Subject: arm64: add kernel config option to lock down when in Secure Boot mode
X-Git-Tag: archive/raspbian/4.18.20-2+rpi1^2~19
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=e5748b7792ddfcfb224e13157a36d5de65854cc1;p=linux.git

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]
[bwh: Forward-ported to 4.18.20: adjust context in update_fdt()]

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 388a929baf9..930997ddcf1 100644
--- 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 232f4915223..89f26b721c8 100644
--- 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 0c0d2312f4a..3dae6e668c2 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -159,6 +159,12 @@ static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 		}
 	}
 
+	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;
+
 	/* shrink the FDT back to its minimum size */
 	fdt_pack(fdt);
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 64215117684..d969c10a093 100644
--- 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 {