cbfs: Add CBFS_TYPE_INTEL_FIT and exclude it from CBFS verification

The Intel Firmware Interface Table (FIT) is a bit of an annoying outlier
among CBFS files because it gets manipulated by a separate utility
(ifittool) after cbfstool has already added it to the image. This will
break file hashes created for CBFS verification.

This is not actually a problem when booting, since coreboot never
actually loads the FIT from CBFS -- instead, it's only in the image for
use by platform-specific mechanisms that run before coreboot's
bootblock. But having an invalid file hash in the CBFS image is
confusing when you want to verify that the image is correctly built for
verification.

This patch adds a new CBFS file type "intel_fit" which is only used for
the intel_fit (and intel_fit_ts, if applicable) file containing the FIT.
cbfstool will avoid generating and verifying file hashes for this type,
like it already does for the "bootblock" and "cbfs header" types. (Note
that this means that any attempt to use the CBFS API to actually access
this file from coreboot will result in a verification error when CBFS
verification is enabled.)

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I1c1bb6dab0c9ccc6e78529758a42ad3194cd130c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64736
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/commonlib/bsd/include/commonlib/bsd/cbfs_serialized.h

@@ -30,6 +30,7 @@ enum cbfs_type {
 	CBFS_TYPE_VSA		= 0x51,
 	CBFS_TYPE_MBI		= 0x52,
 	CBFS_TYPE_MICROCODE	= 0x53,
+	CBFS_TYPE_INTEL_FIT	= 0x54,
 	CBFS_TYPE_FSP		= 0x60,
 	CBFS_TYPE_MRC		= 0x61,
 	CBFS_TYPE_MMA		= 0x62,

src/cpu/intel/fit/Makefile.inc

@@ -8,7 +8,7 @@ bootblock-y += fit.c
 
 cbfs-files-y += intel_fit
 intel_fit-file := fit_table.c:struct
-intel_fit-type := raw
+intel_fit-type := intel_fit
 intel_fit-align := 16
 
 $(call add_intermediate, set_fit_ptr, $(IFITTOOL))
@@ -41,7 +41,7 @@ endif # FIT_ENTRY
 
 cbfs-files-y += intel_fit_ts
 intel_fit_ts-file := fit_table.c:struct
-intel_fit_ts-type := raw
+intel_fit_ts-type := intel_fit
 intel_fit_ts-align := 16
 
 endif # CONFIG_INTEL_ADD_TOP_SWAP_BOOTBLOCK

util/cbfstool/cbfs.h

@@ -40,6 +40,7 @@ static struct typedesc_t filetypes[] unused = {
 	{CBFS_TYPE_VSA, "vsa"},
 	{CBFS_TYPE_MBI, "mbi"},
 	{CBFS_TYPE_MICROCODE, "microcode"},
+	{CBFS_TYPE_INTEL_FIT, "intel_fit"},
 	{CBFS_TYPE_FSP, "fsp"},
 	{CBFS_TYPE_MRC, "mrc"},
 	{CBFS_TYPE_CMOS_DEFAULT, "cmos_default"},

util/cbfstool/cbfstool.c

@@ -279,6 +279,18 @@ static int maybe_update_fmap_hash(void)
 	return update_anchor(mhc, fmap_hash);
 }
 
+static bool verification_exclude(enum cbfs_type type)
+{
+	switch (type) {
+	case CBFS_TYPE_BOOTBLOCK:
+	case CBFS_TYPE_CBFSHEADER:
+	case CBFS_TYPE_INTEL_FIT:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static bool region_is_flashmap(const char *region)
 {
 	return partitioned_file_region_check_magic(param.image_file, region,
@@ -872,7 +884,7 @@ static int cbfs_add_component(const char *filename,
 	/* Bootblock and CBFS header should never have file hashes. When adding
 	   the bootblock it is important that we *don't* look up the metadata
 	   hash yet (before it is added) or we'll cache an outdated result. */
-	if (param.type != CBFS_TYPE_BOOTBLOCK && param.type != CBFS_TYPE_CBFSHEADER) {
+	if (!verification_exclude(param.type)) {
 		enum vb2_hash_algorithm mh_algo = get_mh_cache()->cbfs_hash.algo;
 		if (mh_algo != VB2_HASH_INVALID && param.hash != mh_algo) {
 			if (param.hash == VB2_HASH_INVALID) {