[U-Boot] [PATCH 05/16] efi_loader: add signature verification functions

AKASHI Takahiro
2019-11-18T07:57:14Z

Heinrich,

I will address other comments in a separate e-mail, but
it is worth mentioning that Patrick deserves credit for initial
implementation of efi secure boot, which the main logic of my current
patch set heavily relies on;

On Sat, Nov 16, 2019 at 09:00:12PM +0100, Heinrich Schuchardt wrote:
> On 11/13/19 1:52 AM, AKASHI Takahiro wrote:
>
> >diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c
> >new file mode 100644
> >index 000000000000..04f43e47d1a3
> >--- /dev/null
> >+++ b/lib/efi_loader/efi_signature.c
> >@@ -0,0 +1,600 @@
> >+// SPDX-License-Identifier: GPL-2.0+
> >+/*
> >+ * Copyright (c) 2018 Patrick Wildt <patrick@blueri.se>
>
> From which upstream did you take the code?

The original code has never been upstreamed, and I took over
his patch directly from him.

Thanks,
-Takahiro Akashi

> >+ * Copyright (c) 2019 Linaro Limited, Author: AKASHI Takahiro
> >+ */
> >+
>
> debug() checks the value of _DEBUG.
> Please, include common.h as first include.
>
> Use the sequence of includes as defined in
> https://www.denx.de/wiki/U-Boot/CodingStyle
>
> >+#include <charset.h>
> >+#include <efi_loader.h>
> >+#include <image.h>
> >+#include <hexdump.h>
> >+#include <malloc.h>
> >+#include <pe.h>
> >+#include <linux/compat.h>
> >+#include <linux/oid_registry.h>
> >+#include <u-boot/rsa.h>
>
> Shouldn't we move all cryptography stuff into a directory crypto/?
>
> >+#include <u-boot/sha256.h>
> >+/*
> >+ * avoid duplicated inclusion:
> >+ * #include "../lib/crypto/x509_parser.h"
> >+ */
> >+#include "../lib/crypto/pkcs7_parser.h"
> >+
> >+const efi_guid_t efi_guid_image_security_database =
> >+ EFI_IMAGE_SECURITY_DATABASE_GUID;
> >+const efi_guid_t efi_guid_sha256 = EFI_CERT_SHA256_GUID;
> >+const efi_guid_t efi_guid_cert_rsa2048 = EFI_CERT_RSA2048_GUID;
> >+const efi_guid_t efi_guid_cert_x509 = EFI_CERT_X509_GUID;
> >+const efi_guid_t efi_guid_cert_x509_sha256 = EFI_CERT_X509_SHA256_GUID;
> >+
> >+#ifdef CONFIG_EFI_SECURE_BOOT
> >+static const unsigned char WinIndirectSha256[] = {
>
> We don't use camel case.
>
> >+ 0x30, 0x33, 0x06, 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01, 0x82, 0x37, 0x02,
> >+ 0x01, 0x0f, 0x30, 0x25, 0x03, 0x01, 0x00, 0xa0, 0x20, 0xa2, 0x1e, 0x80,
> >+ 0x1c, 0x00, 0x3c, 0x00, 0x3c, 0x00, 0x3c, 0x00, 0x4f, 0x00, 0x62, 0x00,
> >+ 0x73, 0x00, 0x6f, 0x00, 0x6c, 0x00, 0x65, 0x00, 0x74, 0x00, 0x65, 0x00,
> >+ 0x3e, 0x00, 0x3e, 0x00, 0x3e, 0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60,
> >+ 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20
> >+};
>
> What secret sauce is this? - Please, add comments where applicable. Add
> references where needed for verification of correctness.
>
> Below you describe it as DER wrapper. So why call the variable Sha256?
>
> >+
> >+/**
> >+ * efi_hash_regions - calculate a hash value
> >+ * @regs: List of regions
> >+ * @hash: Pointer to a pointer to buffer holding a hash value
> >+ * @size: Size of buffer to be returned
> >+ *
> >+ * Calculate a sha256 value of @regs and return a value in @hash.
>
> Is this a hash of the concatenation of all regions - or is this a list
> of hashes one for each regions?
>
> >+ *
> >+ * Return: true on success, false on error
> >+ */
> >+static bool efi_hash_regions(struct efi_image_regions *regs, void **hash,
> >+ size_t *size)
>
> Why use void** for hash? There should be a structure for SHA256 hashes.
>
> >+{
> >+ *size = 0;
> >+ *hash = calloc(1, SHA256_SUM_LEN);
> >+ if (!*hash) {
> >+ debug("Out of memory\n");
> >+ return false;
> >+ }
> >+ *size = SHA256_SUM_LEN;
> >+
> >+ hash_calculate("sha256", regs->reg, regs->num, *hash);
> >+#ifdef DEBUG
> >+ debug("hash calculated:\n");
>
> debug checks the value of _DEBUG not of DEBUG. So wouldn't you use
> #ifdef _DEBUG to be consistent?
>
> >+ print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
> >+ *hash, SHA256_SUM_LEN, false);
>
> This will fail to compile if CONFIG_HEXDUMP is not defined?
>
> >+#endif
> >+
> >+ return true;
> >+}
> >+
> >+/**
> >+ * efi_hash_regions_in_der - calculate a hash value
> >+ * @regs: List of regions
> >+ * @hash: Pointer to a pointer to buffer holding a hash value
> >+ * @size: Size of buffer to be returned
> >+ *
> >+ * Calculate a sha256 value of @regs and return a value in @hash.
> >+ * This function is a variant of efi_hash_regions(), and the data will
> >+ * be wrapped with some header in DER format before hash calculation.
> >+ * Message digest in signature of PE format will be calculated this way.
> >+ *
> >+ * Return: true on success, false on error
> >+ */
> >+static bool efi_hash_regions_in_der(struct efi_image_regions *regs, void **hash,
> >+ size_t *size)
> >+{
> >+ void *msg;
> >+ size_t msg_size;
> >+ struct image_region regtmp[2];
> >+
> >+ if (!efi_hash_regions(regs, &msg, &msg_size)) {
> >+ debug("Hash calculation failed\n");
> >+ return false;
> >+ ;
> >+ }
> >+
> >+ *size = 0;
> >+ *hash = calloc(1, SHA256_SUM_LEN);
> >+ if (!*hash) {
> >+ debug("Out of memory\n");
> >+ free(msg);
> >+ return false;
> >+ }
> >+ *size = SHA256_SUM_LEN;
> >+
> >+ /* File image hash is digested with some DER wrapper. */
> >+ regtmp[0].data = WinIndirectSha256;
> >+ regtmp[0].size = sizeof(WinIndirectSha256);
> >+ regtmp[1].data = msg;
> >+ regtmp[1].size = msg_size;
> >+
> >+ hash_calculate("sha256", regtmp, 2, *hash);
> >+#ifdef DEBUG
> >+ debug("hash calculated with extra header:\n");
> >+ print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
> >+ *hash, SHA256_SUM_LEN, false);
> >+#endif
> >+
> >+ free(msg);
> >+
> >+ return true;
> >+}
> >+
> >+/**
> >+ * efi_signature_verify - verify a signature with a certificate
> >+ * @regs: List of regions to be authenticated
> >+ * @signed_info: Pointer to PKCS7's signed_info
> >+ * @cert: x509 certificate
> >+ *
> >+ * Signature pointed to by @signed_info against image pointed to by @regs
> >+ * is verified by a certificate pointed to by @cert.
> >+ * @signed_info holds a signature, including a message digest which is to be
> >+ * compared with a hash value calculated from @regs.
> >+ *
> >+ * Return: true if signature is verified, false if not
> >+ */
> >+static bool efi_signature_verify(struct efi_image_regions *regs,
> >+ struct pkcs7_signed_info *ps_info,
> >+ struct x509_certificate *cert)
> >+{
> >+ struct image_sign_info info;
> >+ struct image_region regtmp[2];
> >+ void *hash;
> >+ size_t size;
> >+ char c;
> >+ bool verified;
> >+
> >+ debug("%s: Enter, %p, %p, %p(issuer: %s, subject: %s)\n", __func__,
> >+ regs, ps_info, cert, cert->issuer, cert->subject);
> >+
> >+ verified = false;
> >+
> >+ memset(&info, '\0', sizeof(info));
> >+ info.padding = image_get_padding_algo("pkcs-1.5");
> >+ /*
> >+ * Note: image_get_[checksum|crypto]_algo takes an string
> >+ * argument like "<checksum>,<crypto>"
> >+ * TODO: support other hash algorithms
> >+ */
> >+ if (!strcmp(ps_info->sig->hash_algo, "sha1")) {
> >+ info.checksum = image_get_checksum_algo("sha1,rsa2048");
> >+ info.name = "sha1,rsa2048";
> >+ } else if (!strcmp(ps_info->sig->hash_algo, "sha256")) {
> >+ info.checksum = image_get_checksum_algo("sha256,rsa2048");
> >+ info.name = "sha256,rsa2048";
> >+ } else {
> >+ debug("unknown msg digest algo: %s\n", ps_info->sig->hash_algo);
> >+ goto out;
> >+ }
> >+ info.crypto = image_get_crypto_algo(info.name);
> >+
> >+ info.key = cert->pub->key;
> >+ info.keylen = cert->pub->keylen;
> >+
> >+ /* verify signature */
> >+ debug("%s: crypto: %s, signature len:%x\n", __func__,
> >+ info.name, ps_info->sig->s_size);
> >+ if (ps_info->aa_set & (1UL << sinfo_has_message_digest)) {
> >+ debug("%s: RSA verify authentication attribute\n", __func__);
> >+ /*
> >+ * NOTE: This path will be executed only for
> >+ * PE image authentication
> >+ */
> >+
> >+ /* check if hash matches digest first */
> >+ debug("checking msg digest first, len:0x%x\n",
> >+ ps_info->msgdigest_len);
> >+
> >+#ifdef DEBUG
> >+ debug("hash in database:\n");
> >+ print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
> >+ ps_info->msgdigest, ps_info->msgdigest_len,
> >+ false);
> >+#endif
> >+ if (efi_hash_regions_in_der(regs, &hash, &size)) {
> >+ if (ps_info->msgdigest_len != size ||
> >+ memcmp(hash, ps_info->msgdigest, size)) {
> >+ debug("Digest doesn't match\n");
> >+ free(hash);
> >+ goto out;
> >+ }
> >+
> >+ free(hash);
> >+ } else {
> >+ debug("Digesting image failed\n");
> >+ goto out;
> >+ }
> >+
> >+ /* against digest */
> >+ c = 0x31;
> >+ regtmp[0].data = &c;
> >+ regtmp[0].size = 1;
> >+ regtmp[1].data = ps_info->authattrs;
> >+ regtmp[1].size = ps_info->authattrs_len;
> >+
> >+ if (!rsa_verify(&info, regtmp, 2,
> >+ ps_info->sig->s, ps_info->sig->s_size))
> >+ verified = true;
> >+ } else {
> >+ debug("%s: RSA verify content data\n", __func__);
> >+ /* against all data */
> >+ if (!rsa_verify(&info, regs->reg, regs->num,
> >+ ps_info->sig->s, ps_info->sig->s_size))
> >+ verified = true;
> >+ }
> >+
> >+out:
> >+ debug("%s: Exit, verified: %d\n", __func__, verified);
> >+ return verified;
> >+}
> >+
> >+/**
> >+ * efi_signature_verify_with_list - verify a signature with signature list
> >+ * @regs: List of regions to be authenticated
> >+ * @signed_info: Pointer to PKCS7's signed_info
> >+ * @siglist: Signature list for certificates
> >+ * @valid_cert: x509 certificate that verifies this signature
> >+ *
> >+ * Signature pointed to by @signed_info against image pointed to by @regs
> >+ * is verified by signature list pointed to by @siglist.
> >+ * Signature database is a simple concatenation of one or more
> >+ * signature list(s).
> >+ *
> >+ * Return: true if signature is verified, false if not
> >+ */
> >+static
> >+bool efi_signature_verify_with_list(struct efi_image_regions *regs,
> >+ struct pkcs7_signed_info *signed_info,
> >+ struct efi_signature_store *siglist,
> >+ struct x509_certificate **valid_cert)
> >+{
> >+ struct x509_certificate *cert;
> >+ struct efi_sig_data *sig_data;
> >+ bool verified = false;
> >+
> >+ debug("%s: Enter, %p, %p, %p, %p\n", __func__,
> >+ regs, signed_info, siglist, valid_cert);
>
> Shouldn't we use EFI_PRINT() to get proper indentation?
>
> >+
> >+ if (!signed_info) {
> >+ void *hash;
> >+ size_t size;
> >+
> >+ debug("%s: unsigned image\n", __func__);
>
> We already have indicated the function above.
>
> >+ /*
> >+ * verify based on calculated hash value
> >+ * TODO: support other hash algorithms
> >+ */
> >+ if (guidcmp(&siglist->sig_type, &efi_guid_sha256)) {
> >+ debug("Digest algorithm is not supported: %pUl\n",
> >+ &siglist->sig_type);
> >+ goto out;
> >+ }
> >+
> >+ if (!efi_hash_regions(regs, &hash, &size)) {
> >+ debug("Digesting unsigned image failed\n");
> >+ goto out;
> >+ }
> >+
> >+ /* go through the list */
> >+ for (sig_data = siglist->sig_data_list; sig_data;
> >+ sig_data = sig_data->next) {
> >+#ifdef DEBUG
> >+ debug("Msg digest in database:\n");
> >+ print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
> >+ sig_data->data, sig_data->size, false);
>
> Does this compile if CONFIG_HEXDUMP is not defined?
>
> >+#endif
> >+ if ((sig_data->size == size) &&
> >+ !memcmp(sig_data->data, hash, size)) {
> >+ verified = true;
> >+ free(hash);
> >+ goto out;
> >+ }
> >+ }
> >+ free(hash);
> >+ goto out;
> >+ }
> >+
> >+ debug("%s: signed image\n", __func__);
> >+ if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509)) {
> >+ debug("Signature type is not supported: %pUl\n",
> >+ &siglist->sig_type);
> >+ goto out;
> >+ }
> >+
> >+ /* go through the list */
> >+ for (sig_data = siglist->sig_data_list; sig_data;
> >+ sig_data = sig_data->next) {
> >+ /* TODO: support owner check based on policy */
> >+
> >+ cert = x509_cert_parse(sig_data->data, sig_data->size);
> >+ if (IS_ERR(cert)) {
> >+ debug("Parsing x509 certificate failed\n");
> >+ goto out;
> >+ }
> >+
> >+ verified = efi_signature_verify(regs, signed_info, cert);
> >+
> >+ if (verified) {
> >+ if (valid_cert)
> >+ *valid_cert = cert;
> >+ else
> >+ x509_free_certificate(cert);
> >+ break;
> >+ } else {
> >+ x509_free_certificate(cert);
> >+ }
> >+ }
> >+
> >+out:
> >+ debug("%s: Exit, verified: %d\n", __func__, verified);
> >+ return verified;
> >+}
> >+
> >+/**
> >+ * efi_signature_verify_with_sigdb - verify a signature with db
> >+ * @regs: List of regions to be authenticated
> >+ * @msg: Signature
> >+ * @db: Signature database for trusted certificates
> >+ * @cert: x509 certificate that verifies this signature
> >+ *
> >+ * Signature pointed to by @msg against image pointed to by @regs
> >+ * is verified by signature database pointed to by @db.
> >+ *
> >+ * Return: true if signature is verified, false if not
> >+ */
> >+bool efi_signature_verify_with_sigdb(struct efi_image_regions *regs,
> >+ struct pkcs7_message *msg,
> >+ struct efi_signature_store *db,
> >+ struct x509_certificate **cert)
> >+{
> >+ struct pkcs7_signed_info *info;
> >+ struct efi_signature_store *siglist;
> >+ bool verified = false;
> >+
> >+ debug("%s: Enter, %p, %p, %p, %p\n", __func__, regs, msg, db, cert);
> >+
> >+ if (!db)
> >+ goto out;
> >+
> >+ if (!db->sig_data_list)
> >+ goto out;
> >+
> >+ /* for unsigned image */
> >+ if (!msg) {
> >+ debug("%s: Verify unsigned image with db\n", __func__);
> >+ for (siglist = db; siglist; siglist = siglist->next)
> >+ if (efi_signature_verify_with_list(regs, NULL,
> >+ siglist, cert)) {
> >+ verified = true;
> >+ goto out;
> >+ }
> >+
> >+ goto out;
> >+ }
> >+
> >+ /* for signed image or variable */
> >+ debug("%s: Verify signed image with db\n", __func__);
> >+ for (info = msg->signed_infos; info; info = info->next) {
> >+ debug("Signed Info: digest algo: %s, pkey algo: %s\n",
> >+ info->sig->hash_algo, info->sig->pkey_algo);
> >+
> >+ for (siglist = db; siglist; siglist = siglist->next) {
> >+ if (efi_signature_verify_with_list(regs, info,
> >+ siglist, cert)) {
> >+ verified = true;
> >+ goto out;
> >+ }
> >+ }
> >+ }
> >+
> >+out:
> >+ debug("%s: Exit, verified: %d\n", __func__, verified);
> >+ return verified;
> >+}
> >+
> >+/**
> >+ * efi_search_siglist - search signature list for a certificate
> >+ * @cert: x509 certificate
> >+ * @siglist: Signature list
> >+ * @revoc_time: Pointer to buffer for revocation time
> >+ *
> >+ * Search signature list pointed to by @siglist and find a certificate
> >+ * pointed to by @cert.
> >+ * If found, revocation time that is specified in signature database is
> >+ * returned in @revoc_time.
> >+ *
> >+ * Return: true if certificate is found, false if not
> >+ */
> >+static bool efi_search_siglist(struct x509_certificate *cert,
> >+ struct efi_signature_store *siglist,
> >+ time64_t *revoc_time)
> >+{
> >+ struct image_region reg[1];
> >+ void *hash = NULL, *msg = NULL;
> >+ struct efi_sig_data *sig_data;
> >+ bool found = false;
> >+
> >+ /* can be null */
> >+ if (!siglist->sig_data_list)
> >+ return false;
> >+
> >+ if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509_sha256)) {
> >+ /* TODO: other hash algos */
> >+ debug("Certificate's digest type is not supported: %pUl\n",
> >+ &siglist->sig_type);
> >+ goto out;
> >+ }
> >+
> >+ /* calculate hash of TBSCertificate */
> >+ msg = calloc(1, SHA256_SUM_LEN);
> >+ if (!msg) {
> >+ debug("Out of memory\n");
> >+ goto out;
> >+ }
> >+
> >+ hash = calloc(1, SHA256_SUM_LEN);
> >+ if (!hash) {
> >+ debug("Out of memory\n");
> >+ goto out;
> >+ }
> >+
> >+ reg[0].data = cert->tbs;
> >+ reg[0].size = cert->tbs_size;
> >+ hash_calculate("sha256", reg, 1, msg);
> >+
> >+ /* go through signature list */
> >+ for (sig_data = siglist->sig_data_list; sig_data;
> >+ sig_data = sig_data->next) {
> >+ /*
> >+ * struct efi_cert_x509_sha256 {
> >+ * u8 tbs_hash[256/8];
> >+ * time64_t revocation_time;
> >+ * };
> >+ */
> >+ if ((sig_data->size == SHA256_SUM_LEN) &&
> >+ !memcmp(sig_data->data, hash, SHA256_SUM_LEN)) {
> >+ memcpy(revoc_time, sig_data->data + SHA256_SUM_LEN,
> >+ sizeof(*revoc_time));
> >+ found = true;
> >+ goto out;
> >+ }
> >+ }
> >+
> >+out:
> >+ free(hash);
> >+ free(msg);
> >+
> >+ return found;
> >+}
> >+
> >+/**
> >+ * efi_signature_verify_cert - verify a certificate with dbx
> >+ * @cert: x509 certificate
> >+ * @dbx: Signature database
> >+ *
> >+ * Search signature database pointed to by @dbx and find a certificate
> >+ * pointed to by @cert.
> >+ * This function is expected to be used against "dbx".
> >+ *
> >+ * Return: true if a certificate is not rejected, false otherwise.
> >+ */
> >+bool efi_signature_verify_cert(struct x509_certificate *cert,
> >+ struct efi_signature_store *dbx)
> >+{
> >+ struct efi_signature_store *siglist;
> >+ time64_t revoc_time;
> >+ bool found = false;
> >+
> >+ debug("%s: Enter, %p, %p\n", __func__, dbx, cert);
>
> EFI_PRINT() ?
>
> >+
> >+ if (!cert)
> >+ return false;
> >+
> >+ for (siglist = dbx; siglist; siglist = siglist->next) {
> >+ if (efi_search_siglist(cert, siglist, &revoc_time)) {
> >+ /* TODO */
> >+ /* compare signing time with revocation time */
>
> Is this a difficult thing to do? If not, please, fill the gap.
>
> Best regards
>
> Heinrich
>
> >+
> >+ found = true;
> >+ break;
> >+ }
> >+ }
> >+
> >+ debug("%s: Exit, verified: %d\n", __func__, !found);
> >+ return !found;
> >+}
> >+
> >+/**
> >+ * efi_signature_verify_signers - verify signers' certificates with dbx
> >+ * @msg: Signature
> >+ * @dbx: Signature database
> >+ *
> >+ * Determine if any of signers' certificates in @msg may be verified
> >+ * by any of certificates in signature database pointed to by @dbx.
> >+ * This function is expected to be used against "dbx".
> >+ *
> >+ * Return: true if none of certificates is rejected, false otherwise.
> >+ */
> >+bool efi_signature_verify_signers(struct pkcs7_message *msg,
> >+ struct efi_signature_store *dbx)
> >+{
> >+ struct pkcs7_signed_info *info;
> >+ bool found = false;
> >+
> >+ debug("%s: Enter, %p, %p\n", __func__, msg, dbx);
> >+
> >+ if (!msg)
> >+ goto out;
> >+
> >+ for (info = msg->signed_infos; info; info = info->next) {
> >+ if (info->signer &&
> >+ !efi_signature_verify_cert(info->signer, dbx)) {
> >+ found = true;
> >+ goto out;
> >+ }
> >+ }
> >+out:
> >+ debug("%s: Exit, verified: %d\n", __func__, !found);
> >+ return !found;
> >+}
> >+
> >+/**
> >+ * efi_image_region_add - add an entry of region
> >+ * @regs: Pointer to array of regions
> >+ * @start: Start address of region
> >+ * @end: End address of region
> >+ * @nocheck: flag against overlapped regions
> >+ *
> >+ * Take one entry of region [@start, @end] and append it to the list
> >+ * pointed to by @regs. If @nocheck is false, overlapping among entries
> >+ * will be checked first.
> >+ *
> >+ * Return: 0 on success, status code (negative) on error
> >+ */
> >+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 >= EFI_REGS_MAX) {
> >+ debug("%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;
> >+
> >+ if (start > reg->data + reg->size)
> >+ continue;
> >+
> >+ if ((start >= reg->data && start < reg->data + reg->size) ||
> >+ (end > reg->data && end < reg->data + reg->size)) {
> >+ debug("%s: new region already part of another\n",
> >+ __func__);
> >+ return EFI_INVALID_PARAMETER;
> >+ }
> >+
> >+ if (start < reg->data && end < reg->data + reg->size) {
> >+ for (j = regs->num - 1; j >= i; j--)
> >+ memcpy(&regs->reg[j], &regs->reg[j + 1],
> >+ sizeof(*reg));
> >+ break;
> >+ }
> >+ }
> >+
> >+ reg = &regs->reg[i];
> >+ reg->data = start;
> >+ reg->size = end - start;
> >+ regs->num++;
> >+
> >+ return EFI_SUCCESS;
> >+}
> >+#endif /* CONFIG_EFI_SECURE_BOOT */
> >
>