Add some plumbing to the zboot EFI header generation to set the newly
introduced DllCharacteristicsEx flag associated with forward edge CFI
enforcement instructions (BTI on arm64, IBT on x86)
x86 does not currently uses the zboot infrastructure, so let's wire it
up only for arm64.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/arm64/boot/Makefile | 1 +
drivers/firmware/efi/libstub/Makefile.zboot | 9 +++-
drivers/firmware/efi/libstub/zboot-header.S | 49 +++++++++++++-------
3 files changed, 40 insertions(+), 19 deletions(-)
diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
index c65aee0884103c6f..ae645fda90bca574 100644
--- a/arch/arm64/boot/Makefile
+++ b/arch/arm64/boot/Makefile
@@ -42,5 +42,6 @@ $(obj)/Image.zst: $(obj)/Image FORCE
EFI_ZBOOT_PAYLOAD := Image
EFI_ZBOOT_BFD_TARGET := elf64-littleaarch64
EFI_ZBOOT_MACH_TYPE := ARM64
+EFI_ZBOOT_FORWARD_CFI := $(CONFIG_ARM64_BTI_KERNEL)
include $(srctree)/drivers/firmware/efi/libstub/Makefile.zboot
diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot
index 2d78770236049b21..0a9dcc2b13736519 100644
--- a/drivers/firmware/efi/libstub/Makefile.zboot
+++ b/drivers/firmware/efi/libstub/Makefile.zboot
@@ -1,7 +1,8 @@
# SPDX-License-Identifier: GPL-2.0
# to be include'd by arch/$(ARCH)/boot/Makefile after setting
-# EFI_ZBOOT_PAYLOAD, EFI_ZBOOT_BFD_TARGET and EFI_ZBOOT_MACH_TYPE
+# EFI_ZBOOT_PAYLOAD, EFI_ZBOOT_BFD_TARGET, EFI_ZBOOT_MACH_TYPE and
+# EFI_ZBOOT_FORWARD_CFI
quiet_cmd_copy_and_pad = PAD $@
cmd_copy_and_pad = cp $< $@ && \
@@ -44,10 +45,14 @@ OBJCOPYFLAGS_vmlinuz.o := -I binary -O $(EFI_ZBOOT_BFD_TARGET) \
$(obj)/vmlinuz.o: $(obj)/vmlinuz FORCE
$(call if_changed,objcopy)
+aflags-zboot-header-$(EFI_ZBOOT_FORWARD_CFI) := \
+ -DPE_DLL_CHAR_EX=IMAGE_DLLCHARACTERISTICS_EX_FORWARD_CFI_COMPAT
+
AFLAGS_zboot-header.o += -DMACHINE_TYPE=IMAGE_FILE_MACHINE_$(EFI_ZBOOT_MACH_TYPE) \
-DZBOOT_EFI_PATH="\"$(realpath $(obj)/vmlinuz.efi.elf)\"" \
-DZBOOT_SIZE_LEN=$(zboot-size-len-y) \
- -DCOMP_TYPE="\"$(comp-type-y)\""
+ -DCOMP_TYPE="\"$(comp-type-y)\"" \
+ $(aflags-zboot-header-y)
$(obj)/zboot-header.o: $(srctree)/drivers/firmware/efi/libstub/zboot-header.S FORCE
$(call if_changed_rule,as_o_S)
diff --git a/drivers/firmware/efi/libstub/zboot-header.S b/drivers/firmware/efi/libstub/zboot-header.S
index 053aba073594936b..fb676ded47fa4341 100644
--- a/drivers/firmware/efi/libstub/zboot-header.S
+++ b/drivers/firmware/efi/libstub/zboot-header.S
@@ -78,9 +78,36 @@ __efistub_efi_zboot_header:
.quad 0 // ExceptionTable
.quad 0 // CertificationTable
.quad 0 // BaseRelocationTable
-#ifdef CONFIG_DEBUG_EFI
+#if defined(PE_DLL_CHAR_EX) || defined(CONFIG_DEBUG_EFI)
.long .Lefi_debug_table - .Ldoshdr // DebugTable
.long .Lefi_debug_table_size
+
+ .section ".rodata", "a"
+ .p2align 2
+.Lefi_debug_table:
+ // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY[]
+#ifdef PE_DLL_CHAR_EX
+ .long 0 // Characteristics
+ .long 0 // TimeDateStamp
+ .short 0 // MajorVersion
+ .short 0 // MinorVersion
+ .long IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS // Type
+ .long 4 // SizeOfData
+ .long 0 // RVA
+ .long .Lefi_dll_characteristics_ex - .Ldoshdr // FileOffset
+#endif
+#ifdef CONFIG_DEBUG_EFI
+ .long 0 // Characteristics
+ .long 0 // TimeDateStamp
+ .short 0 // MajorVersion
+ .short 0 // MinorVersion
+ .long IMAGE_DEBUG_TYPE_CODEVIEW // Type
+ .long .Lefi_debug_entry_size // SizeOfData
+ .long 0 // RVA
+ .long .Lefi_debug_entry - .Ldoshdr // FileOffset
+#endif
+ .set .Lefi_debug_table_size, . - .Lefi_debug_table
+ .previous
#endif
.Lsection_table:
@@ -110,23 +137,11 @@ __efistub_efi_zboot_header:
.set .Lsection_count, (. - .Lsection_table) / 40
+#ifdef PE_DLL_CHAR_EX
+.Lefi_dll_characteristics_ex:
+ .long PE_DLL_CHAR_EX
+#endif
#ifdef CONFIG_DEBUG_EFI
- .section ".rodata", "a"
- .align 2
-.Lefi_debug_table:
- // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY
- .long 0 // Characteristics
- .long 0 // TimeDateStamp
- .short 0 // MajorVersion
- .short 0 // MinorVersion
- .long IMAGE_DEBUG_TYPE_CODEVIEW // Type
- .long .Lefi_debug_entry_size // SizeOfData
- .long 0 // RVA
- .long .Lefi_debug_entry - .Ldoshdr // FileOffset
-
- .set .Lefi_debug_table_size, . - .Lefi_debug_table
- .previous
-
.Lefi_debug_entry:
// EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY
.ascii "NB10" // Signature
--
2.39.2
