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|
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2018 Patrick Wildt <patrick@blueri.se>
* Copyright (c) 2019 Linaro Limited, Author: AKASHI Takahiro
*/
#include <common.h>
#include <charset.h>
#include <efi_loader.h>
#include <image.h>
#include <hexdump.h>
#include <malloc.h>
#include <crypto/pkcs7_parser.h>
#include <linux/compat.h>
#include <linux/oid_registry.h>
#include <u-boot/rsa.h>
#include <u-boot/sha256.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
/**
* 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.
*
* Return: true on success, false on error
*/
static bool efi_hash_regions(struct efi_image_regions *regs, void **hash,
size_t *size)
{
*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");
print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
*hash, SHA256_SUM_LEN, false);
#endif
return true;
}
/**
* efi_hash_msg_content - calculate a hash value of contentInfo
* @msg: Signature
* @hash: Pointer to a pointer to buffer holding a hash value
* @size: Size of buffer to be returned
*
* Calculate a sha256 value of contentInfo in @msg and return a value in @hash.
*
* Return: true on success, false on error
*/
static bool efi_hash_msg_content(struct pkcs7_message *msg, void **hash,
size_t *size)
{
struct image_region regtmp;
*size = 0;
*hash = calloc(1, SHA256_SUM_LEN);
if (!*hash) {
debug("Out of memory\n");
free(msg);
return false;
}
*size = SHA256_SUM_LEN;
regtmp.data = msg->data;
regtmp.size = msg->data_len;
hash_calculate("sha256", ®tmp, 1, *hash);
#ifdef DEBUG
debug("hash calculated based on contentInfo:\n");
print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
*hash, SHA256_SUM_LEN, false);
#endif
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_message *msg,
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
/* against contentInfo first */
if ((msg->data && efi_hash_msg_content(msg, &hash, &size)) ||
/* for signed image */
efi_hash_regions(regs, &hash, &size)) {
/* for authenticated variable */
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
* @msg: Signature
* @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_message *msg,
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);
if (!signed_info) {
void *hash;
size_t size;
debug("%s: unsigned image\n", __func__);
/*
* 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);
#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, msg, signed_info, cert);
if (verified) {
if (valid_cert)
*valid_cert = cert;
else
x509_free_certificate(cert);
break;
}
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, 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, msg, 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);
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 */
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 >= 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 = ®s->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(®s->reg[j], ®s->reg[j + 1],
sizeof(*reg));
break;
}
}
reg = ®s->reg[i];
reg->data = start;
reg->size = end - start;
regs->num++;
return EFI_SUCCESS;
}
/**
* efi_sigstore_free - free signature store
* @sigstore: Pointer to signature store structure
*
* Feee all the memories held in signature store and itself,
* which were allocated by efi_sigstore_parse_sigdb().
*/
void efi_sigstore_free(struct efi_signature_store *sigstore)
{
struct efi_signature_store *sigstore_next;
struct efi_sig_data *sig_data, *sig_data_next;
while (sigstore) {
sigstore_next = sigstore->next;
sig_data = sigstore->sig_data_list;
while (sig_data) {
sig_data_next = sig_data->next;
free(sig_data->data);
free(sig_data);
sig_data = sig_data_next;
}
free(sigstore);
sigstore = sigstore_next;
}
}
/**
* efi_sigstore_parse_siglist - parse a signature list
* @name: Pointer to signature list
*
* Parse signature list and instantiate a signature store structure.
* Signature database is a simple concatenation of one or more
* signature list(s).
*
* Return: Pointer to signature store on success, NULL on error
*/
static struct efi_signature_store *
efi_sigstore_parse_siglist(struct efi_signature_list *esl)
{
struct efi_signature_store *siglist = NULL;
struct efi_sig_data *sig_data, *sig_data_next;
struct efi_signature_data *esd;
size_t left;
/*
* UEFI specification defines certificate types:
* for non-signed images,
* EFI_CERT_SHA256_GUID
* EFI_CERT_RSA2048_GUID
* EFI_CERT_RSA2048_SHA256_GUID
* EFI_CERT_SHA1_GUID
* EFI_CERT_RSA2048_SHA_GUID
* EFI_CERT_SHA224_GUID
* EFI_CERT_SHA384_GUID
* EFI_CERT_SHA512_GUID
*
* for signed images,
* EFI_CERT_X509_GUID
* NOTE: Each certificate will normally be in a separate
* EFI_SIGNATURE_LIST as the size may vary depending on
* its algo's.
*
* for timestamp revocation of certificate,
* EFI_CERT_X509_SHA512_GUID
* EFI_CERT_X509_SHA256_GUID
* EFI_CERT_X509_SHA384_GUID
*/
if (esl->signature_list_size
<= (sizeof(*esl) + esl->signature_header_size)) {
debug("Siglist in wrong format\n");
return NULL;
}
/* Create a head */
siglist = calloc(sizeof(*siglist), 1);
if (!siglist) {
debug("Out of memory\n");
goto err;
}
memcpy(&siglist->sig_type, &esl->signature_type, sizeof(efi_guid_t));
/* Go through the list */
sig_data_next = NULL;
left = esl->signature_list_size
- (sizeof(*esl) + esl->signature_header_size);
esd = (struct efi_signature_data *)
((u8 *)esl + sizeof(*esl) + esl->signature_header_size);
while ((left > 0) && left >= esl->signature_size) {
/* Signature must exist if there is remaining data. */
if (left < esl->signature_size) {
debug("Certificate is too small\n");
goto err;
}
sig_data = calloc(esl->signature_size
- sizeof(esd->signature_owner), 1);
if (!sig_data) {
debug("Out of memory\n");
goto err;
}
/* Append signature data */
memcpy(&sig_data->owner, &esd->signature_owner,
sizeof(efi_guid_t));
sig_data->size = esl->signature_size
- sizeof(esd->signature_owner);
sig_data->data = malloc(sig_data->size);
if (!sig_data->data) {
debug("Out of memory\n");
goto err;
}
memcpy(sig_data->data, esd->signature_data, sig_data->size);
sig_data->next = sig_data_next;
sig_data_next = sig_data;
/* Next */
esd = (struct efi_signature_data *)
((u8 *)esd + esl->signature_size);
left -= esl->signature_size;
}
siglist->sig_data_list = sig_data_next;
return siglist;
err:
efi_sigstore_free(siglist);
return NULL;
}
/**
* efi_sigstore_parse_sigdb - parse a signature database variable
* @name: Variable's name
*
* Read in a value of signature database variable pointed to by
* @name, parse it and instantiate a signature store structure.
*
* Return: Pointer to signature store on success, NULL on error
*/
struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name)
{
struct efi_signature_store *sigstore = NULL, *siglist;
struct efi_signature_list *esl;
const efi_guid_t *vendor;
void *db;
efi_uintn_t db_size;
efi_status_t ret;
if (!u16_strcmp(name, L"PK") || !u16_strcmp(name, L"KEK")) {
vendor = &efi_global_variable_guid;
} else if (!u16_strcmp(name, L"db") || !u16_strcmp(name, L"dbx")) {
vendor = &efi_guid_image_security_database;
} else {
debug("unknown signature database, %ls\n", name);
return NULL;
}
/* retrieve variable data */
db_size = 0;
ret = EFI_CALL(efi_get_variable(name, vendor, NULL, &db_size, NULL));
if (ret == EFI_NOT_FOUND) {
debug("variable, %ls, not found\n", name);
sigstore = calloc(sizeof(*sigstore), 1);
return sigstore;
} else if (ret != EFI_BUFFER_TOO_SMALL) {
debug("Getting variable, %ls, failed\n", name);
return NULL;
}
db = malloc(db_size);
if (!db) {
debug("Out of memory\n");
return NULL;
}
ret = EFI_CALL(efi_get_variable(name, vendor, NULL, &db_size, db));
if (ret != EFI_SUCCESS) {
debug("Getting variable, %ls, failed\n", name);
goto err;
}
/* Parse siglist list */
esl = db;
while (db_size > 0) {
/* List must exist if there is remaining data. */
if (db_size < sizeof(*esl)) {
debug("variable, %ls, in wrong format\n", name);
goto err;
}
if (db_size < esl->signature_list_size) {
debug("variable, %ls, in wrong format\n", name);
goto err;
}
/* Parse a single siglist. */
siglist = efi_sigstore_parse_siglist(esl);
if (!siglist) {
debug("Parsing signature list of %ls failed\n", name);
goto err;
}
/* Append siglist */
siglist->next = sigstore;
sigstore = siglist;
/* Next */
db_size -= esl->signature_list_size;
esl = (void *)esl + esl->signature_list_size;
}
free(db);
return sigstore;
err:
efi_sigstore_free(sigstore);
free(db);
return NULL;
}
#endif /* CONFIG_EFI_SECURE_BOOT */
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