Merge branch 'efi-sbat' into efi/next

Author: ardbiesheuvel

drivers/firmware/efi/Kconfig

@@ -281,6 +281,30 @@ config EFI_EMBEDDED_FIRMWARE
 	bool
 	select CRYPTO_LIB_SHA256
 
+config EFI_SBAT
+       def_bool y if EFI_SBAT_FILE!=""
+
+config EFI_SBAT_FILE
+	string "Embedded SBAT section file path"
+	depends on EFI_ZBOOT
+	help
+	  SBAT section provides a way to improve SecureBoot revocations of UEFI
+	  binaries by introducing a generation-based mechanism. With SBAT, older
+	  UEFI binaries can be prevented from booting by bumping the minimal
+	  required generation for the specific component in the bootloader.
+
+	  Note: SBAT information is distribution specific, i.e. the owner of the
+	  signing SecureBoot certificate must define the SBAT policy. Linux
+	  kernel upstream does not define SBAT components and their generations.
+
+	  See https://github.com/rhboot/shim/blob/main/SBAT.md for the additional
+	  details.
+
+	  Specify a file with SBAT data which is going to be embedded as '.sbat'
+	  section into the kernel.
+
+	  If unsure, leave blank.
+
 endmenu
 
 config UEFI_CPER

drivers/firmware/efi/libstub/Makefile.zboot

@@ -44,6 +44,10 @@ AFLAGS_zboot-header.o += -DMACHINE_TYPE=IMAGE_FILE_MACHINE_$(EFI_ZBOOT_MACH_TYPE
 $(obj)/zboot-header.o: $(srctree)/drivers/firmware/efi/libstub/zboot-header.S FORCE
 	$(call if_changed_rule,as_o_S)
 
+ifneq ($(CONFIG_EFI_SBAT_FILE),)
+$(obj)/zboot-header.o: $(CONFIG_EFI_SBAT_FILE)
+endif
+
 ZBOOT_DEPS := $(obj)/zboot-header.o $(objtree)/drivers/firmware/efi/libstub/lib.a
 
 LDFLAGS_vmlinuz.efi.elf := -T $(srctree)/drivers/firmware/efi/libstub/zboot.lds

drivers/firmware/efi/libstub/zboot-header.S

@@ -123,11 +123,29 @@ __efistub_efi_zboot_header:
 			IMAGE_SCN_MEM_READ | \
 			IMAGE_SCN_MEM_EXECUTE
 
+#ifdef CONFIG_EFI_SBAT
+	.ascii		".sbat\0\0\0"
+	.long		__sbat_size
+	.long		_sbat - .Ldoshdr
+	.long		__sbat_size
+	.long		_sbat - .Ldoshdr
+
+	.long		0, 0
+	.short		0, 0
+	.long		IMAGE_SCN_CNT_INITIALIZED_DATA | \
+			IMAGE_SCN_MEM_READ | \
+			IMAGE_SCN_MEM_DISCARDABLE
+
+	.pushsection ".sbat", "a", @progbits
+	.incbin CONFIG_EFI_SBAT_FILE
+	.popsection
+#endif
+
 	.ascii		".data\0\0\0"
 	.long		__data_size
-	.long		_etext - .Ldoshdr
+	.long		_data - .Ldoshdr
 	.long		__data_rawsize
-	.long		_etext - .Ldoshdr
+	.long		_data - .Ldoshdr
 
 	.long		0, 0
 	.short		0, 0

drivers/firmware/efi/libstub/zboot.lds

@@ -29,7 +29,17 @@ SECTIONS
 		. = _etext;
 	}
 
+#ifdef CONFIG_EFI_SBAT
+        .sbat : ALIGN(4096) {
+		_sbat = .;
+		*(.sbat)
+		_esbat = ALIGN(4096);
+		. = _esbat;
+	}
+#endif
+
 	.data : ALIGN(4096) {
+		_data = .;
 		*(.data* .init.data*)
 		_edata = ALIGN(512);
 		. = _edata;
@@ -52,3 +62,4 @@ PROVIDE(__efistub__gzdata_size =
 
 PROVIDE(__data_rawsize = ABSOLUTE(_edata - _etext));
 PROVIDE(__data_size = ABSOLUTE(_end - _etext));
+PROVIDE(__sbat_size = ABSOLUTE(_esbat - _sbat));