lib/efi_loader/efi_image_loader.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  EFI image loader
 *
 *  based partly on wine code
 *
 *  Copyright (c) 2016 Alexander Graf
 */

#define LOG_CATEGORY LOGC_EFI

#include <cpu_func.h>
#include <efi_loader.h>
#include <log.h>
#include <malloc.h>
#include <mapmem.h>
#include <pe.h>
#include <sort.h>
#include <crypto/mscode.h>
#include <crypto/pkcs7_parser.h>
#include <linux/err.h>

const efi_guid_t efi_global_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
const efi_guid_t efi_guid_device_path = EFI_DEVICE_PATH_PROTOCOL_GUID;
const efi_guid_t efi_guid_loaded_image = EFI_LOADED_IMAGE_PROTOCOL_GUID;
const efi_guid_t efi_guid_loaded_image_device_path =
		EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID;
const efi_guid_t efi_simple_file_system_protocol_guid =
		EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
const efi_guid_t efi_file_info_guid = EFI_FILE_INFO_GUID;

static int machines[] = {
#if defined(__aarch64__)
	IMAGE_FILE_MACHINE_ARM64,
#elif defined(__arm__)
	IMAGE_FILE_MACHINE_ARM,
	IMAGE_FILE_MACHINE_THUMB,
	IMAGE_FILE_MACHINE_ARMNT,
#endif

#if defined(__x86_64__)
	IMAGE_FILE_MACHINE_AMD64,
#elif defined(__i386__)
	IMAGE_FILE_MACHINE_I386,
#endif

#if defined(__riscv) && (__riscv_xlen == 32)
	IMAGE_FILE_MACHINE_RISCV32,
#endif

#if defined(__riscv) && (__riscv_xlen == 64)
	IMAGE_FILE_MACHINE_RISCV64,
#endif
	0 };

/**
 * efi_print_image_info() - print information about a loaded image
 *
 * If the program counter is located within the image the offset to the base
 * address is shown.
 *
 * @obj:	EFI object
 * @image:	loaded image
 * @pc:		program counter (use NULL to suppress offset output)
 * Return:	status code
 */
static efi_status_t efi_print_image_info(struct efi_loaded_image_obj *obj,
					 struct efi_loaded_image *image,
					 void *pc)
{
	printf("UEFI image");
	printf(" [0x%p:0x%p]",
	       image->image_base, image->image_base + image->image_size - 1);
	if (pc && pc >= image->image_base &&
	    pc < image->image_base + image->image_size)
		printf(" pc=0x%zx", pc - image->image_base);
	if (image->file_path)
		printf(" '%pD'", image->file_path);
	printf("\n");
	return EFI_SUCCESS;
}

/**
 * efi_print_image_infos() - print information about all loaded images
 *
 * @pc:		program counter (use NULL to suppress offset output)
 */
void efi_print_image_infos(void *pc)
{
	struct efi_object *efiobj;
	struct efi_handler *handler;

	list_for_each_entry(efiobj, &efi_obj_list, link) {
		list_for_each_entry(handler, &efiobj->protocols, link) {
			if (!guidcmp(&handler->guid, &efi_guid_loaded_image)) {
				efi_print_image_info(
					(struct efi_loaded_image_obj *)efiobj,
					handler->protocol_interface, pc);
			}
		}
	}
}

/**
 * efi_loader_relocate() - relocate UEFI binary
 *
 * @rel:		pointer to the relocation table
 * @rel_size:		size of the relocation table in bytes
 * @efi_reloc:		actual load address of the image
 * @pref_address:	preferred load address of the image
 * Return:		status code
 */
static efi_status_t efi_loader_relocate(const IMAGE_BASE_RELOCATION *rel,
			unsigned long rel_size, void *efi_reloc,
			unsigned long pref_address)
{
	unsigned long delta = (unsigned long)efi_reloc - pref_address;
	const IMAGE_BASE_RELOCATION *end;
	int i;

	if (delta == 0)
		return EFI_SUCCESS;

	end = (const IMAGE_BASE_RELOCATION *)((const char *)rel + rel_size);
	while (rel + 1 < end && rel->SizeOfBlock) {
		const uint16_t *relocs = (const uint16_t *)(rel + 1);
		i = (rel->SizeOfBlock - sizeof(*rel)) / sizeof(uint16_t);
		while (i--) {
			uint32_t offset = (uint32_t)(*relocs & 0xfff) +
					  rel->VirtualAddress;
			int type = *relocs >> EFI_PAGE_SHIFT;
			uint64_t *x64 = efi_reloc + offset;
			uint32_t *x32 = efi_reloc + offset;
			uint16_t *x16 = efi_reloc + offset;

			switch (type) {
			case IMAGE_REL_BASED_ABSOLUTE:
				break;
			case IMAGE_REL_BASED_HIGH:
				*x16 += ((uint32_t)delta) >> 16;
				break;
			case IMAGE_REL_BASED_LOW:
				*x16 += (uint16_t)delta;
				break;
			case IMAGE_REL_BASED_HIGHLOW:
				*x32 += (uint32_t)delta;
				break;
			case IMAGE_REL_BASED_DIR64:
				*x64 += (uint64_t)delta;
				break;
#ifdef __riscv
			case IMAGE_REL_BASED_RISCV_HI20:
				*x32 = ((*x32 & 0xfffff000) + (uint32_t)delta) |
					(*x32 & 0x00000fff);
				break;
			case IMAGE_REL_BASED_RISCV_LOW12I:
			case IMAGE_REL_BASED_RISCV_LOW12S:
				/* We know that we're 4k aligned */
				if (delta & 0xfff) {
					log_err("Unsupported reloc offset\n");
					return EFI_LOAD_ERROR;
				}
				break;
#endif
			default:
				log_err("Unknown Relocation off %x type %x\n",
					offset, type);
				return EFI_LOAD_ERROR;
			}
			relocs++;
		}
		rel = (const IMAGE_BASE_RELOCATION *)relocs;
	}
	return EFI_SUCCESS;
}

/**
 * efi_set_code_and_data_type() - determine the memory types to be used for code
 *				  and data.
 *
 * @loaded_image_info:	image descriptor
 * @image_type:		field Subsystem of the optional header for
 *			Windows specific field
 */
static void efi_set_code_and_data_type(
			struct efi_loaded_image *loaded_image_info,
			uint16_t image_type)
{
	switch (image_type) {
	case IMAGE_SUBSYSTEM_EFI_APPLICATION:
		loaded_image_info->image_code_type = EFI_LOADER_CODE;
		loaded_image_info->image_data_type = EFI_LOADER_DATA;
		break;
	case IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER:
		loaded_image_info->image_code_type = EFI_BOOT_SERVICES_CODE;
		loaded_image_info->image_data_type = EFI_BOOT_SERVICES_DATA;
		break;
	case IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER:
	case IMAGE_SUBSYSTEM_EFI_ROM:
		loaded_image_info->image_code_type = EFI_RUNTIME_SERVICES_CODE;
		loaded_image_info->image_data_type = EFI_RUNTIME_SERVICES_DATA;
		break;
	default:
		log_err("invalid image type: %u\n", image_type);
		/* Let's assume it is an application */
		loaded_image_info->image_code_type = EFI_LOADER_CODE;
		loaded_image_info->image_data_type = EFI_LOADER_DATA;
		break;
	}
}

/**
 * efi_image_region_add() - add an entry of region
 * @regs:	Pointer to array of regions
 * @start:	Start address of region (included)
 * @end:	End address of region (excluded)
 * @nocheck:	flag against overlapped regions
 *
 * Take one entry of region \[@start, @end\[ and insert it into the list.
 *
 * * If @nocheck is false, the list will be sorted ascending by address.
 *   Overlapping entries will not be allowed.
 *
 * * If @nocheck is true, the list will be sorted ascending by sequence
 *   of adding the entries. Overlapping is allowed.
 *
 * Return:	status code
 */
efi_status_t efi_image_region_add(struct efi_image_regions *regs,
				  const void *start, const void *end,
				  int nocheck)
{
	struct image_region *reg;
	int i, j;

	if (regs->num >= regs->max) {
		log_err("%s: no more room for regions\n", __func__);
		return EFI_OUT_OF_RESOURCES;
	}

	if (end < start)
		return EFI_INVALID_PARAMETER;

	for (i = 0; i < regs->num; i++) {
		reg = &regs->reg[i];
		if (nocheck)
			continue;

		/* new data after registered region */
		if (start >= reg->data + reg->size)
			continue;

		/* new data preceding registered region */
		if (end <= reg->data) {
			for (j = regs->num - 1; j >= i; j--)
				memcpy(&regs->reg[j + 1], &regs->reg[j],
				       sizeof(*reg));
			break;
		}

		/* new data overlapping registered region */
		log_err("%s: new region already part of another\n", __func__);
		return EFI_INVALID_PARAMETER;
	}

	reg = &regs->reg[i];
	reg->data = start;
	reg->size = end - start;
	regs->num++;

	return EFI_SUCCESS;
}

/**
 * cmp_pe_section() - compare virtual addresses of two PE image sections
 * @arg1:	pointer to pointer to first section header
 * @arg2:	pointer to pointer to second section header
 *
 * Compare the virtual addresses of two sections of an portable executable.
 * The arguments are defined as const void * to allow usage with qsort().
 *
 * Return:	-1 if the virtual address of arg1 is less than that of arg2,
 *		0 if the virtual addresses are equal, 1 if the virtual address
 *		of arg1 is greater than that of arg2.
 */
static int cmp_pe_section(const void *arg1, const void *arg2)
{
	const IMAGE_SECTION_HEADER *section1, *section2;

	section1 = *((const IMAGE_SECTION_HEADER **)arg1);
	section2 = *((const IMAGE_SECTION_HEADER **)arg2);

	if (section1->VirtualAddress < section2->VirtualAddress)
		return -1;
	else if (section1->VirtualAddress == section2->VirtualAddress)
		return 0;
	else
		return 1;
}

/**
 * efi_prepare_aligned_image() - prepare 8-byte aligned image
 * @efi:		pointer to the EFI binary
 * @efi_size:		size of @efi binary
 *
 * If @efi is not 8-byte aligned, this function newly allocates
 * the image buffer.
 *
 * Return:	valid pointer to a image, return NULL if allocation fails.
 */
void *efi_prepare_aligned_image(void *efi, u64 *efi_size)
{
	size_t new_efi_size;
	void *new_efi;

	/*
	 * Size must be 8-byte aligned and the trailing bytes must be
	 * zero'ed. Otherwise hash value may be incorrect.
	 */
	if (!IS_ALIGNED(*efi_size, 8)) {
		new_efi_size = ALIGN(*efi_size, 8);
		new_efi = calloc(new_efi_size, 1);
		if (!new_efi)
			return NULL;
		memcpy(new_efi, efi, *efi_size);
		*efi_size = new_efi_size;
		return new_efi;
	} else {
		return efi;
	}
}

/**
 * efi_image_parse() - parse a PE image
 * @efi:	Pointer to image
 * @len:	Size of @efi
 * @regp:	Pointer to a list of regions
 * @auth:	Pointer to a pointer to authentication data in PE
 * @auth_len:	Size of @auth
 *
 * Parse image binary in PE32(+) format, assuming that sanity of PE image
 * has been checked by a caller.
 * On success, an address of authentication data in @efi and its size will
 * be returned in @auth and @auth_len, respectively.
 *
 * Return:	true on success, false on error
 */
bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp,
		     WIN_CERTIFICATE **auth, size_t *auth_len)
{
	struct efi_image_regions *regs;
	IMAGE_DOS_HEADER *dos;
	IMAGE_NT_HEADERS32 *nt;
	IMAGE_SECTION_HEADER *sections, **sorted;
	int num_regions, num_sections, i;
	int ctidx = IMAGE_DIRECTORY_ENTRY_SECURITY;
	u32 align, size, authsz, authoff;
	size_t bytes_hashed;

	dos = (void *)efi;
	nt = (void *)(efi + dos->e_lfanew);
	authoff = 0;
	authsz = 0;

	/*
	 * Count maximum number of regions to be digested.
	 * We don't have to have an exact number here.
	 * See efi_image_region_add()'s in parsing below.
	 */
	num_regions = 3; /* for header */
	num_regions += nt->FileHeader.NumberOfSections;
	num_regions++; /* for extra */

	regs = calloc(sizeof(*regs) + sizeof(struct image_region) * num_regions,
		      1);
	if (!regs)
		goto err;
	regs->max = num_regions;

	/*
	 * Collect data regions for hash calculation
	 * 1. File headers
	 */
	if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
		IMAGE_NT_HEADERS64 *nt64 = (void *)nt;
		IMAGE_OPTIONAL_HEADER64 *opt = &nt64->OptionalHeader;

		/* Skip CheckSum */
		efi_image_region_add(regs, efi, &opt->CheckSum, 0);
		if (nt64->OptionalHeader.NumberOfRvaAndSizes <= ctidx) {
			efi_image_region_add(regs,
					     &opt->Subsystem,
					     efi + opt->SizeOfHeaders, 0);
		} else {
			/* Skip Certificates Table */
			efi_image_region_add(regs,
					     &opt->Subsystem,
					     &opt->DataDirectory[ctidx], 0);
			efi_image_region_add(regs,
					     &opt->DataDirectory[ctidx] + 1,
					     efi + opt->SizeOfHeaders, 0);

			authoff = opt->DataDirectory[ctidx].VirtualAddress;
			authsz = opt->DataDirectory[ctidx].Size;
		}

		bytes_hashed = opt->SizeOfHeaders;
		align = opt->FileAlignment;
	} else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
		IMAGE_OPTIONAL_HEADER32 *opt = &nt->OptionalHeader;

		/* Skip CheckSum */
		efi_image_region_add(regs, efi, &opt->CheckSum, 0);
		if (nt->OptionalHeader.NumberOfRvaAndSizes <= ctidx) {
			efi_image_region_add(regs,
					     &opt->Subsystem,
					     efi + opt->SizeOfHeaders, 0);
		} else {
			/* Skip Certificates Table */
			efi_image_region_add(regs, &opt->Subsystem,
					     &opt->DataDirectory[ctidx], 0);
			efi_image_region_add(regs,
					     &opt->DataDirectory[ctidx] + 1,
					     efi + opt->SizeOfHeaders, 0);

			authoff = opt->DataDirectory[ctidx].VirtualAddress;
			authsz = opt->DataDirectory[ctidx].Size;
		}

		bytes_hashed = opt->SizeOfHeaders;
		align = opt->FileAlignment;
	} else {
		log_err("%s: Invalid optional header magic %x\n", __func__,
			nt->OptionalHeader.Magic);
		goto err;
	}

	/* 2. Sections */
	num_sections = nt->FileHeader.NumberOfSections;
	sections = (void *)((uint8_t *)&nt->OptionalHeader +
			    nt->FileHeader.SizeOfOptionalHeader);
	sorted = calloc(sizeof(IMAGE_SECTION_HEADER *), num_sections);
	if (!sorted) {
		log_err("%s: Out of memory\n", __func__);
		goto err;
	}

	/*
	 * Make sure the section list is in ascending order.
	 */
	for (i = 0; i < num_sections; i++)
		sorted[i] = &sections[i];
	qsort(sorted, num_sections, sizeof(sorted[0]), cmp_pe_section);

	for (i = 0; i < num_sections; i++) {
		if (!sorted[i]->SizeOfRawData)
			continue;

		size = (sorted[i]->SizeOfRawData + align - 1) & ~(align - 1);
		efi_image_region_add(regs, efi + sorted[i]->PointerToRawData,
				     efi + sorted[i]->PointerToRawData + size,
				     0);
		log_debug("section[%d](%s): raw: 0x%x-0x%x, virt: %x-%x\n",
			  i, sorted[i]->Name,
			  sorted[i]->PointerToRawData,
			  sorted[i]->PointerToRawData + size,
			  sorted[i]->VirtualAddress,
			  sorted[i]->VirtualAddress
			    + sorted[i]->Misc.VirtualSize);

		bytes_hashed += size;
	}
	free(sorted);

	/* 3. Extra data excluding Certificates Table */
	if (bytes_hashed + authsz < len) {
		log_debug("extra data for hash: %zu\n",
			  len - (bytes_hashed + authsz));
		efi_image_region_add(regs, efi + bytes_hashed,
				     efi + len - authsz, 0);
	}

	/* Return Certificates Table */
	if (authsz) {
		if (len < authoff + authsz) {
			log_err("%s: Size for auth too large: %u >= %zu\n",
				__func__, authsz, len - authoff);
			goto err;
		}
		if (authsz < sizeof(*auth)) {
			log_err("%s: Size for auth too small: %u < %zu\n",
				__func__, authsz, sizeof(*auth));
			goto err;
		}
		*auth = efi + authoff;
		*auth_len = authsz;
		log_debug("WIN_CERTIFICATE: 0x%x, size: 0x%x\n", authoff,
			  authsz);
	} else {
		*auth = NULL;
		*auth_len = 0;
	}

	*regp = regs;

	return true;

err:
	free(regs);

	return false;
}

#ifdef CONFIG_EFI_SECURE_BOOT
/**
 * efi_image_verify_digest - verify image's message digest
 * @regs:	Array of memory regions to digest
 * @msg:	Signature in pkcs7 structure
 *
 * @regs contains all the data in a PE image to digest. Calculate
 * a hash value based on @regs and compare it with a messaged digest
 * in the content (SpcPeImageData) of @msg's contentInfo.
 *
 * Return:	true if verified, false if not
 */
static bool efi_image_verify_digest(struct efi_image_regions *regs,
				    struct pkcs7_message *msg)
{
	struct pefile_context ctx;
	void *hash;
	int hash_len, ret;

	const void *data;
	size_t data_len;
	size_t asn1hdrlen;

	/* get pkcs7's contentInfo */
	ret = pkcs7_get_content_data(msg, &data, &data_len, &asn1hdrlen);
	if (ret < 0 || !data)
		return false;

	/* parse data and retrieve a message digest into ctx */
	ret = mscode_parse(&ctx, data, data_len, asn1hdrlen);
	if (ret < 0)
		return false;

	/* calculate a hash value of PE image */
	hash = NULL;
	if (!efi_hash_regions(regs->reg, regs->num, &hash, ctx.digest_algo,
			      &hash_len))
		return false;

	/* match the digest */
	if (ctx.digest_len != hash_len || memcmp(ctx.digest, hash, hash_len))
		return false;

	return true;
}

/**
 * efi_image_authenticate() - verify a signature of signed image
 * @efi:	Pointer to image
 * @efi_size:	Size of @efi
 *
 * A signed image should have its signature stored in a table of its PE header.
 * So if an image is signed and only if if its signature is verified using
 * signature databases, an image is authenticated.
 * If an image is not signed, its validity is checked by using
 * efi_image_unsigned_authenticated().
 * TODO:
 * When AuditMode==0, if the image's signature is not found in
 * the authorized database, or is found in the forbidden database,
 * the image will not be started and instead, information about it
 * will be placed in this table.
 * When AuditMode==1, an EFI_IMAGE_EXECUTION_INFO element is created
 * in the EFI_IMAGE_EXECUTION_INFO_TABLE for every certificate found
 * in the certificate table of every image that is validated.
 *
 * Return:	true if authenticated, false if not
 */
static bool efi_image_authenticate(void *efi, size_t efi_size)
{
	struct efi_image_regions *regs = NULL;
	WIN_CERTIFICATE *wincerts = NULL, *wincert;
	size_t wincerts_len;
	struct pkcs7_message *msg = NULL;
	struct efi_signature_store *db = NULL, *dbx = NULL;
	void *new_efi = NULL;
	u8 *auth, *wincerts_end;
	u64 new_efi_size = efi_size;
	size_t auth_size;
	bool ret = false;

	log_debug("%s: Enter, %d\n", __func__, ret);

	if (!efi_secure_boot_enabled())
		return true;

	new_efi = efi_prepare_aligned_image(efi, &new_efi_size);
	if (!new_efi)
		return false;

	if (!efi_image_parse(new_efi, new_efi_size, &regs, &wincerts,
			     &wincerts_len)) {
		log_err("Parsing PE executable image failed\n");
		goto out;
	}

	/*
	 * verify signature using db and dbx
	 */
	db = efi_sigstore_parse_sigdb(u"db");
	if (!db) {
		log_err("Getting signature database(db) failed\n");
		goto out;
	}

	dbx = efi_sigstore_parse_sigdb(u"dbx");
	if (!dbx) {
		log_err("Getting signature database(dbx) failed\n");
		goto out;
	}

	if (efi_signature_lookup_digest(regs, dbx, true)) {
		log_debug("Image's digest was found in \"dbx\"\n");
		goto out;
	}

	/*
	 * go through WIN_CERTIFICATE list
	 * NOTE:
	 * We may have multiple signatures either as WIN_CERTIFICATE's
	 * in PE header, or as pkcs7 SignerInfo's in SignedData.
	 * So the verification policy here is:
	 *   - Success if, at least, one of signatures is verified
	 *   - unless signature is rejected explicitly with its digest.
	 */

	for (wincert = wincerts, wincerts_end = (u8 *)wincerts + wincerts_len;
	     (u8 *)wincert < wincerts_end;
	     wincert = (WIN_CERTIFICATE *)
			((u8 *)wincert + ALIGN(wincert->dwLength, 8))) {
		if ((u8 *)wincert + sizeof(*wincert) >= wincerts_end)
			break;

		if (wincert->dwLength <= sizeof(*wincert)) {
			log_debug("dwLength too small: %u < %zu\n",
				  wincert->dwLength, sizeof(*wincert));
			continue;
		}

		log_debug("WIN_CERTIFICATE_TYPE: 0x%x\n",
			  wincert->wCertificateType);

		auth = (u8 *)wincert + sizeof(*wincert);
		auth_size = wincert->dwLength - sizeof(*wincert);
		if (wincert->wCertificateType == WIN_CERT_TYPE_EFI_GUID) {
			if (auth + sizeof(efi_guid_t) >= wincerts_end)
				break;

			if (auth_size <= sizeof(efi_guid_t)) {
				log_debug("dwLength too small: %u < %zu\n",
					  wincert->dwLength, sizeof(*wincert));
				continue;
			}
			if (guidcmp(auth, &efi_guid_cert_type_pkcs7)) {
				log_debug("Certificate type not supported: %pUs\n",
					  auth);
				ret = false;
				goto out;
			}

			auth += sizeof(efi_guid_t);
			auth_size -= sizeof(efi_guid_t);
		} else if (wincert->wCertificateType
				!= WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
			log_debug("Certificate type not supported\n");
			ret = false;
			goto out;
		}

		msg = pkcs7_parse_message(auth, auth_size);
		if (IS_ERR(msg)) {
			log_err("Parsing image's signature failed\n");
			msg = NULL;
			continue;
		}

		/*
		 * verify signatures in pkcs7's signedInfos which are
		 * to authenticate the integrity of pkcs7's contentInfo.
		 *
		 * NOTE:
		 * UEFI specification defines two signature types possible
		 * in signature database:
		 * a. x509 certificate, where a signature in image is
		 *    a message digest encrypted by RSA public key
		 *    (EFI_CERT_X509_GUID)
		 * b. bare hash value of message digest
		 *    (EFI_CERT_SHAxxx_GUID)
		 *
		 * efi_signature_verify() handles case (a), while
		 * efi_signature_lookup_digest() handles case (b).
		 *
		 * There is a third type:
		 * c. message digest of a certificate
		 *    (EFI_CERT_X509_SHAAxxx_GUID)
		 * This type of signature is used only in revocation list
		 * (dbx) and handled as part of efi_signatgure_verify().
		 */
		/* try black-list first */
		if (efi_signature_verify_one(regs, msg, dbx)) {
			ret = false;
			log_debug("Signature was rejected by \"dbx\"\n");
			goto out;
		}

		if (!efi_signature_check_signers(msg, dbx)) {
			ret = false;
			log_debug("Signer(s) in \"dbx\"\n");
			goto out;
		}

		/* try white-list */
		if (!efi_signature_verify(regs, msg, db, dbx)) {
			log_debug("Signature was not verified by \"db\"\n");
			continue;
		}

		/*
		 * now calculate an image's hash value and compare it with
		 * a messaged digest embedded in pkcs7's contentInfo
		 */
		if (efi_image_verify_digest(regs, msg)) {
			ret = true;
			continue;
		}

		log_debug("Message digest doesn't match\n");
	}

	/* last resort try the image sha256 hash in db */
	if (!ret && efi_signature_lookup_digest(regs, db, false))
		ret = true;

out:
	efi_sigstore_free(db);
	efi_sigstore_free(dbx);
	pkcs7_free_message(msg);
	free(regs);
	if (new_efi != efi)
		free(new_efi);

	log_debug("%s: Exit, %d\n", __func__, ret);
	return ret;
}
#else
static bool efi_image_authenticate(void *efi, size_t efi_size)
{
	return true;
}
#endif /* CONFIG_EFI_SECURE_BOOT */

/**
 * efi_check_pe() - check if a memory buffer contains a PE-COFF image
 *
 * @buffer:	buffer to check
 * @size:	size of buffer
 * @nt_header:	on return pointer to NT header of PE-COFF image
 * Return:	EFI_SUCCESS if the buffer contains a PE-COFF image
 */
efi_status_t efi_check_pe(void *buffer, size_t size, void **nt_header)
{
	IMAGE_DOS_HEADER *dos = buffer;
	IMAGE_NT_HEADERS32 *nt;

	if (size < sizeof(*dos))
		return EFI_INVALID_PARAMETER;

	/* Check for DOS magix */
	if (dos->e_magic != IMAGE_DOS_SIGNATURE)
		return EFI_INVALID_PARAMETER;

	/*
	 * Check if the image section header fits into the file. Knowing that at
	 * least one section header follows we only need to check for the length
	 * of the 64bit header which is longer than the 32bit header.
	 */
	if (size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS32))
		return EFI_INVALID_PARAMETER;
	nt = (IMAGE_NT_HEADERS32 *)((u8 *)buffer + dos->e_lfanew);

	/* Check for PE-COFF magic */
	if (nt->Signature != IMAGE_NT_SIGNATURE)
		return EFI_INVALID_PARAMETER;

	if (nt_header)
		*nt_header = nt;

	return EFI_SUCCESS;
}

/**
 * section_size() - determine size of section
 *
 * The size of a section in memory if normally given by VirtualSize.
 * If VirtualSize is not provided, use SizeOfRawData.
 *
 * @sec:	section header
 * Return:	size of section in memory
 */
static u32 section_size(IMAGE_SECTION_HEADER *sec)
{
	if (sec->Misc.VirtualSize)
		return sec->Misc.VirtualSize;
	else
		return sec->SizeOfRawData;
}

/**
 * efi_load_pe() - relocate EFI binary
 *
 * This function loads all sections from a PE binary into a newly reserved
 * piece of memory. On success the entry point is returned as handle->entry.
 *
 * @handle:		loaded image handle
 * @efi:		pointer to the EFI binary
 * @efi_size:		size of @efi binary
 * @loaded_image_info:	loaded image protocol
 * Return:		status code
 */
efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
			 void *efi, size_t efi_size,
			 struct efi_loaded_image *loaded_image_info)
{
	IMAGE_NT_HEADERS32 *nt;
	IMAGE_DOS_HEADER *dos;
	IMAGE_SECTION_HEADER *sections;
	int num_sections;
	void *efi_reloc;
	int i;
	const IMAGE_BASE_RELOCATION *rel;
	unsigned long rel_size;
	int rel_idx = IMAGE_DIRECTORY_ENTRY_BASERELOC;
	uint64_t image_base;
	unsigned long virt_size = 0;
	int supported = 0;
	efi_status_t ret;

	ret = efi_check_pe(efi, efi_size, (void **)&nt);
	if (ret != EFI_SUCCESS) {
		log_err("Not a PE-COFF file\n");
		return EFI_LOAD_ERROR;
	}

	for (i = 0; machines[i]; i++)
		if (machines[i] == nt->FileHeader.Machine) {
			supported = 1;
			break;
		}

	if (!supported) {
		log_err("Machine type 0x%04x is not supported\n",
			nt->FileHeader.Machine);
		return EFI_LOAD_ERROR;
	}

	num_sections = nt->FileHeader.NumberOfSections;
	sections = (void *)&nt->OptionalHeader +
			    nt->FileHeader.SizeOfOptionalHeader;

	if (efi_size < ((void *)sections + sizeof(sections[0]) * num_sections
			- efi)) {
		log_err("Invalid number of sections: %d\n", num_sections);
		return EFI_LOAD_ERROR;
	}

	/* Authenticate an image */
	if (efi_image_authenticate(efi, efi_size)) {
		handle->auth_status = EFI_IMAGE_AUTH_PASSED;
	} else {
		handle->auth_status = EFI_IMAGE_AUTH_FAILED;
		log_err("Image not authenticated\n");
	}

	/* Calculate upper virtual address boundary */
	for (i = num_sections - 1; i >= 0; i--) {
		IMAGE_SECTION_HEADER *sec = &sections[i];

		virt_size = max_t(unsigned long, virt_size,
				  sec->VirtualAddress + section_size(sec));
	}

	/* Read 32/64bit specific header bits */
	if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
		IMAGE_NT_HEADERS64 *nt64 = (void *)nt;
		IMAGE_OPTIONAL_HEADER64 *opt = &nt64->OptionalHeader;
		image_base = opt->ImageBase;
		efi_set_code_and_data_type(loaded_image_info, opt->Subsystem);
		handle->image_type = opt->Subsystem;
		efi_reloc = efi_alloc_aligned_pages(virt_size,
						    loaded_image_info->image_code_type,
						    opt->SectionAlignment);
		if (!efi_reloc) {
			log_err("Out of memory\n");
			ret = EFI_OUT_OF_RESOURCES;
			goto err;
		}
		handle->entry = efi_reloc + opt->AddressOfEntryPoint;
		rel_size = opt->DataDirectory[rel_idx].Size;
		rel = efi_reloc + opt->DataDirectory[rel_idx].VirtualAddress;
	} else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
		IMAGE_OPTIONAL_HEADER32 *opt = &nt->OptionalHeader;
		image_base = opt->ImageBase;
		efi_set_code_and_data_type(loaded_image_info, opt->Subsystem);
		handle->image_type = opt->Subsystem;
		efi_reloc = efi_alloc_aligned_pages(virt_size,
						    loaded_image_info->image_code_type,
						    opt->SectionAlignment);
		if (!efi_reloc) {
			log_err("Out of memory\n");
			ret = EFI_OUT_OF_RESOURCES;
			goto err;
		}
		handle->entry = efi_reloc + opt->AddressOfEntryPoint;
		rel_size = opt->DataDirectory[rel_idx].Size;
		rel = efi_reloc + opt->DataDirectory[rel_idx].VirtualAddress;
	} else {
		log_err("Invalid optional header magic %x\n",
			nt->OptionalHeader.Magic);
		ret = EFI_LOAD_ERROR;
		goto err;
	}

#if IS_ENABLED(CONFIG_EFI_TCG2_PROTOCOL)
	/* Measure an PE/COFF image */
	ret = tcg2_measure_pe_image(efi, efi_size, handle, loaded_image_info);
	if (ret == EFI_SECURITY_VIOLATION) {
		/*
		 * TCG2 Protocol is installed but no TPM device found,
		 * this is not expected.
		 */
		log_err("PE image measurement failed, no tpm device found\n");
		goto err;
	}

#endif

	/* Copy PE headers */
	memcpy(efi_reloc, efi,
	       sizeof(*dos)
		 + sizeof(*nt)
		 + nt->FileHeader.SizeOfOptionalHeader
		 + num_sections * sizeof(IMAGE_SECTION_HEADER));

	/* Load sections into RAM */
	for (i = num_sections - 1; i >= 0; i--) {
		IMAGE_SECTION_HEADER *sec = &sections[i];
		u32 copy_size = section_size(sec);

		if (copy_size > sec->SizeOfRawData) {
			copy_size = sec->SizeOfRawData;
			memset(efi_reloc + sec->VirtualAddress, 0,
			       sec->Misc.VirtualSize);
		}
		memcpy(efi_reloc + sec->VirtualAddress,
		       efi + sec->PointerToRawData,
		       copy_size);
	}

	/* Run through relocations */
	if (efi_loader_relocate(rel, rel_size, efi_reloc,
				(unsigned long)image_base) != EFI_SUCCESS) {
		efi_free_pages((uintptr_t) efi_reloc,
			       (virt_size + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT);
		ret = EFI_LOAD_ERROR;
		goto err;
	}

	/* Flush cache */
	flush_cache(map_to_sysmem(efi_reloc),
		    ALIGN(virt_size, EFI_CACHELINE_SIZE));

	/*
	 * If on x86 a write affects a prefetched instruction,
	 * the prefetch queue is invalidated.
	 */
	if (!CONFIG_IS_ENABLED(X86))
		invalidate_icache_all();

	/* Populate the loaded image interface bits */
	loaded_image_info->image_base = efi_reloc;
	loaded_image_info->image_size = virt_size;

	if (handle->auth_status == EFI_IMAGE_AUTH_PASSED)
		return EFI_SUCCESS;
	else
		return EFI_SECURITY_VIOLATION;

err:
	return ret;
}