From: Linn Crosetto Date: Tue, 30 Aug 2016 11:54:38 -0600 Subject: arm64: add kernel config option to lock down when in Secure Boot mode Bug-Debian: https://bugs.debian.org/831827 Forwarded: no 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 [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 4.19.3: adjust context in update_fdt()] --- arch/arm64/Kconfig | 13 +++++++++++++ drivers/firmware/efi/arm-init.c | 7 +++++++ drivers/firmware/efi/efi.c | 3 ++- drivers/firmware/efi/libstub/arm-stub.c | 2 +- drivers/firmware/efi/libstub/efistub.h | 1 + drivers/firmware/efi/libstub/fdt.c | 7 +++++++ include/linux/efi.h | 1 + 7 files changed, 32 insertions(+), 2 deletions(-) --- a/drivers/firmware/efi/arm-init.c +++ b/drivers/firmware/efi/arm-init.c @@ -21,6 +21,7 @@ #include #include #include +#include #include @@ -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; --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -657,7 +657,8 @@ static __initdata struct params fdt_para 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[] = { --- 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_syste } } + 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); --- 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 {