blob: e282115d72671408c085988440beadcce7929c31 [file] [log] [blame]
/*
* Copyright (c) 2022-2023, STMicroelectronics - All Rights Reserved
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <assert.h>
#include <endian.h>
#include <errno.h>
#include <common/debug.h>
#include <drivers/auth/crypto_mod.h>
#include <drivers/io/io_storage.h>
#include <drivers/st/bsec.h>
#include <drivers/st/stm32_hash.h>
#include <drivers/st/stm32_pka.h>
#include <drivers/st/stm32_rng.h>
#include <drivers/st/stm32_saes.h>
#include <lib/utils.h>
#include <lib/xlat_tables/xlat_tables_v2.h>
#include <mbedtls/asn1.h>
#include <mbedtls/md.h>
#include <mbedtls/oid.h>
#include <mbedtls/platform.h>
#include <mbedtls/x509.h>
#include <plat/common/platform.h>
#include <tools_share/firmware_encrypted.h>
#include <platform_def.h>
#define CRYPTO_HASH_MAX_SIZE 32U
#define CRYPTO_SIGN_MAX_SIZE 64U
#define CRYPTO_PUBKEY_MAX_SIZE 64U
#define CRYPTO_MAX_TAG_SIZE 16U
/* brainpoolP256t1 OID is not defined in mbedTLS */
#define OID_EC_GRP_BP256T1 MBEDTLS_OID_EC_BRAINPOOL_V1 "\x08"
#if STM32MP_CRYPTO_ROM_LIB
struct stm32mp_auth_ops {
uint32_t (*verify_signature)(uint8_t *hash_in, uint8_t *pubkey_in,
uint8_t *signature, uint32_t ecc_algo);
};
static struct stm32mp_auth_ops auth_ops;
#endif
static void crypto_lib_init(void)
{
boot_api_context_t *boot_context __maybe_unused;
int ret;
NOTICE("TRUSTED_BOARD_BOOT support enabled\n");
ret = stm32_hash_register();
if (ret != 0) {
ERROR("HASH init (%d)\n", ret);
panic();
}
if (stm32mp_is_closed_device() || stm32mp_is_auth_supported()) {
#if STM32MP_CRYPTO_ROM_LIB
boot_context = (boot_api_context_t *)stm32mp_get_boot_ctx_address();
auth_ops.verify_signature = boot_context->bootrom_ecdsa_verify_signature;
#else
/* Use hardware peripherals */
if (stm32_rng_init() != 0) {
panic();
}
if (stm32_saes_driver_init() != 0) {
panic();
}
if (stm32_pka_init() != 0) {
panic();
}
#endif
}
}
static int get_plain_pk_from_asn1(void *pk_ptr, unsigned int pk_len, void **plain_pk,
size_t *len, int *pk_alg)
{
int ret;
mbedtls_pk_context mbedtls_pk = {0};
unsigned char *p, *end;
mbedtls_asn1_buf alg_params = {0};
mbedtls_asn1_buf alg_oid = {0};
*plain_pk = NULL;
*len = 0U;
/* Parse the public key */
mbedtls_pk_init(&mbedtls_pk);
p = (unsigned char *)pk_ptr;
end = (unsigned char *)(p + pk_len);
ret = mbedtls_asn1_get_tag(&p, end, len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
if (ret != 0) {
return -EINVAL;
}
end = p + *len;
ret = mbedtls_asn1_get_alg(&p, end, &alg_oid, &alg_params);
if (ret != 0) {
VERBOSE("%s: mbedtls_asn1_get_alg (%d)\n", __func__, ret);
return -EINVAL;
}
if (pk_alg != NULL) {
if ((strlen(MBEDTLS_OID_EC_GRP_SECP256R1) == alg_params.len) &&
(memcmp(MBEDTLS_OID_EC_GRP_SECP256R1, alg_params.p, alg_params.len) == 0)) {
*pk_alg = BOOT_API_ECDSA_ALGO_TYPE_P256NIST;
} else if ((strlen(OID_EC_GRP_BP256T1) == alg_params.len) &&
(memcmp(OID_EC_GRP_BP256T1, alg_params.p, alg_params.len) == 0)) {
*pk_alg = BOOT_API_ECDSA_ALGO_TYPE_BRAINPOOL256;
} else {
ERROR("%s: Algorithm is not supported\n", __func__);
return -EINVAL;
}
}
ret = mbedtls_asn1_get_bitstring_null(&p, end, len);
if (ret != 0) {
VERBOSE("%s: mbedtls_asn1_get_bitstring_null (%d)\n", __func__, ret);
return -EINVAL;
}
/* We remove the ident (0x04) first byte. */
if ((*len < 1U) || (p[0] != MBEDTLS_ASN1_OCTET_STRING)) {
VERBOSE("%s: not expected len or tag\n", __func__);
return -EINVAL;
}
*len = *len - 1U;
*plain_pk = p + 1U;
return 0;
}
#if STM32MP_CRYPTO_ROM_LIB
uint32_t verify_signature(uint8_t *hash_in, uint8_t *pubkey_in,
uint8_t *signature, uint32_t ecc_algo)
{
int ret;
ret = mmap_add_dynamic_region(STM32MP_ROM_BASE, STM32MP_ROM_BASE,
STM32MP_ROM_SIZE_2MB_ALIGNED, MT_CODE | MT_SECURE);
if (ret != 0) {
VERBOSE("%s: mmap_add_dynamic_region (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
ret = auth_ops.verify_signature(hash_in, pubkey_in, signature, ecc_algo);
if (ret != BOOT_API_RETURN_OK) {
VERBOSE("%s: auth_ops.verify_sign (%d)\n", __func__, ret);
ret = CRYPTO_ERR_SIGNATURE;
} else {
ret = 0;
}
mmap_remove_dynamic_region(STM32MP_ROM_BASE, STM32MP_ROM_SIZE_2MB_ALIGNED);
return ret;
}
static int crypto_convert_pk(void *full_pk_ptr, unsigned int full_pk_len,
void **hashed_pk_ptr, unsigned int *hashed_pk_len)
{
size_t len;
int ret;
ret = get_plain_pk_from_asn1(full_pk_ptr, full_pk_len, hashed_pk_ptr, &len, NULL);
if (ret == 0) {
*hashed_pk_len = (unsigned int)len;
}
return ret;
}
#else /* STM32MP_CRYPTO_ROM_LIB*/
static uint32_t verify_signature(uint8_t *hash_in, uint8_t *pubkey_in,
uint8_t *signature, uint32_t ecc_algo)
{
int ret = -1;
enum stm32_pka_ecdsa_curve_id cid;
switch (ecc_algo) {
case BOOT_API_ECDSA_ALGO_TYPE_P256NIST:
#if PKA_USE_NIST_P256
cid = PKA_NIST_P256;
ret = 0;
#else
WARN("%s nist_p256 requested but not included\n", __func__);
#endif
break;
case BOOT_API_ECDSA_ALGO_TYPE_BRAINPOOL256:
#if PKA_USE_BRAINPOOL_P256T1
cid = PKA_BRAINPOOL_P256T1;
ret = 0;
#else
WARN("%s brainpool_p256t1 requested but not included\n", __func__);
#endif
break;
default:
WARN("%s unexpected ecc_algo(%u)\n", __func__, ecc_algo);
break;
}
if (ret < 0) {
return CRYPTO_ERR_SIGNATURE;
}
ret = stm32_pka_ecdsa_verif(hash_in,
BOOT_API_SHA256_DIGEST_SIZE_IN_BYTES,
signature, BOOT_API_ECDSA_SIGNATURE_LEN_IN_BYTES / 2U,
signature + BOOT_API_ECDSA_SIGNATURE_LEN_IN_BYTES / 2U,
BOOT_API_ECDSA_SIGNATURE_LEN_IN_BYTES / 2U,
pubkey_in, BOOT_API_ECDSA_PUB_KEY_LEN_IN_BYTES / 2U,
pubkey_in + BOOT_API_ECDSA_PUB_KEY_LEN_IN_BYTES / 2U,
BOOT_API_ECDSA_PUB_KEY_LEN_IN_BYTES / 2U, cid);
if (ret < 0) {
return CRYPTO_ERR_SIGNATURE;
}
return 0;
}
static int crypto_convert_pk(void *full_pk_ptr, unsigned int full_pk_len,
void **hashed_pk_ptr, unsigned int *hashed_pk_len)
{
static uint8_t st_pk[CRYPTO_PUBKEY_MAX_SIZE + sizeof(uint32_t)];
int ret;
void *plain_pk;
size_t len;
int curve_id;
uint32_t cid;
ret = get_plain_pk_from_asn1(full_pk_ptr, full_pk_len, &plain_pk, &len, &curve_id);
if ((ret != 0) || (len > CRYPTO_PUBKEY_MAX_SIZE)) {
return -EINVAL;
}
cid = curve_id; /* we want value of curve_id (1 or 2) in a uint32_t */
memcpy(st_pk, &cid, sizeof(cid));
memcpy(st_pk + sizeof(cid), plain_pk, len);
*hashed_pk_ptr = st_pk;
*hashed_pk_len = (unsigned int)(len + sizeof(cid));
return 0;
}
#endif /* STM32MP_CRYPTO_ROM_LIB */
static int get_plain_digest_from_asn1(void *digest_ptr, unsigned int digest_len,
uint8_t **out, size_t *out_len, mbedtls_md_type_t *md_alg)
{
int ret;
mbedtls_asn1_buf hash_oid, params;
size_t len;
unsigned char *p, *end;
*out = NULL;
*out_len = 0U;
/* Digest info should be an MBEDTLS_ASN1_SEQUENCE */
p = (unsigned char *)digest_ptr;
end = p + digest_len;
ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE);
if (ret != 0) {
return ret;
}
/* Get the hash algorithm */
ret = mbedtls_asn1_get_alg(&p, end, &hash_oid, &params);
if (ret != 0) {
return ret;
}
ret = mbedtls_oid_get_md_alg(&hash_oid, md_alg);
if (ret != 0) {
return ret;
}
ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING);
if (ret != 0) {
return ret;
}
/* Length of hash must match the algorithm's size */
if (len != BOOT_API_SHA256_DIGEST_SIZE_IN_BYTES) {
return -1;
}
*out = p;
*out_len = len;
return 0;
}
static int crypto_verify_signature(void *data_ptr, unsigned int data_len,
void *sig_ptr, unsigned int sig_len,
void *sig_alg, unsigned int sig_alg_len,
void *pk_ptr, unsigned int pk_len)
{
uint8_t image_hash[CRYPTO_HASH_MAX_SIZE] = {0};
uint8_t sig[CRYPTO_SIGN_MAX_SIZE];
uint8_t my_pk[CRYPTO_PUBKEY_MAX_SIZE];
int ret;
size_t len;
mbedtls_asn1_sequence seq;
mbedtls_asn1_sequence *cur;
unsigned char *p, *end;
int curve_id;
mbedtls_asn1_buf sig_oid, sig_params;
mbedtls_md_type_t md_alg;
mbedtls_pk_type_t pk_alg;
size_t bignum_len = sizeof(sig) / 2U;
unsigned int seq_num = 0U;
if (!stm32mp_is_closed_device() && !stm32mp_is_auth_supported()) {
return CRYPTO_SUCCESS;
}
/* Get pointers to signature OID and parameters */
p = (unsigned char *)sig_alg;
end = (unsigned char *)(p + sig_alg_len);
ret = mbedtls_asn1_get_alg(&p, end, &sig_oid, &sig_params);
if (ret != 0) {
VERBOSE("%s: mbedtls_asn1_get_alg (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
/* Get the actual signature algorithm (MD + PK) */
ret = mbedtls_oid_get_sig_alg(&sig_oid, &md_alg, &pk_alg);
if (ret != 0) {
VERBOSE("%s: mbedtls_oid_get_sig_alg (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
if ((md_alg != MBEDTLS_MD_SHA256) || (pk_alg != MBEDTLS_PK_ECDSA)) {
VERBOSE("%s: md_alg=%u pk_alg=%u\n", __func__, md_alg, pk_alg);
return CRYPTO_ERR_SIGNATURE;
}
ret = get_plain_pk_from_asn1(pk_ptr, pk_len, &pk_ptr, &len, &curve_id);
if (ret != 0) {
VERBOSE("%s: get_plain_pk_from_asn1 (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
/* We expect a known pk_len */
if (len != sizeof(my_pk)) {
VERBOSE("%s: pk_len=%zu sizeof(my_pk)=%zu)\n", __func__, len, sizeof(my_pk));
return CRYPTO_ERR_SIGNATURE;
}
/* Need to copy as auth_ops.verify_signature
* expects aligned public key.
*/
memcpy(my_pk, pk_ptr, sizeof(my_pk));
/* Get the signature (bitstring) */
p = (unsigned char *)sig_ptr;
end = (unsigned char *)(p + sig_len);
ret = mbedtls_asn1_get_bitstring_null(&p, end, &len);
if (ret != 0) {
VERBOSE("%s: mbedtls_asn1_get_bitstring_null (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
/* Get r and s from sequence */
ret = mbedtls_asn1_get_sequence_of(&p, end, &seq, MBEDTLS_ASN1_INTEGER);
if (ret != 0) {
VERBOSE("%s: mbedtls_asn1_get_sequence_of (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
/* We expect only 2 integers (r and s) from the sequence */
if (seq.next->next != NULL) {
cur = seq.next;
mbedtls_asn1_sequence *next;
VERBOSE("%s: nb seq != 2\n", __func__);
/* Free all the sequences */
while (cur != NULL) {
next = cur->next;
mbedtls_free(cur);
cur = next;
}
return CRYPTO_ERR_SIGNATURE;
}
/*
* ECDSA signatures are composed of a tuple (R,S) where R and S are between 0 and n.
* This means that the R and S can have a maximum of 32 each, but can also be smaller.
* Also seen the integer sequence may (sometime) start with 0x00 as MSB, but we can only
* manage exactly 2*32 bytes, we remove this higher byte if there are not 00,
* we will fail either.
*/
cur = &seq;
memset(sig, 0U, sizeof(sig));
while (cur != NULL) {
size_t skip = 0U;
size_t seek = seq_num * bignum_len;
if (cur->buf.len > bignum_len) {
/* Remove extra 0x00 bytes */
skip = cur->buf.len - bignum_len;
} else if (cur->buf.len < bignum_len) {
/* Add padding to match HW required size */
seek += (bignum_len % cur->buf.len);
}
if (seek + cur->buf.len > sizeof(sig) + skip) {
panic();
}
memcpy(sig + seek, cur->buf.p + skip, cur->buf.len - skip);
cur = cur->next;
seq_num++;
}
/* Need to free allocated 'next' in mbedtls_asn1_get_sequence_of */
mbedtls_free(seq.next);
/* Compute hash for the data covered by the signature */
stm32_hash_init(HASH_SHA256);
ret = stm32_hash_final_update((uint8_t *)data_ptr, data_len, image_hash);
if (ret != 0) {
VERBOSE("%s: stm32_hash_final_update (%d)\n", __func__, ret);
return CRYPTO_ERR_SIGNATURE;
}
return verify_signature(image_hash, my_pk, sig, curve_id);
}
static int crypto_verify_hash(void *data_ptr, unsigned int data_len,
void *digest_info_ptr,
unsigned int digest_info_len)
{
int ret;
uint8_t calc_hash[BOOT_API_SHA256_DIGEST_SIZE_IN_BYTES];
unsigned char *p;
mbedtls_md_type_t md_alg;
size_t len;
/* we receive an asn1 encapsulated digest, we flatten it */
ret = get_plain_digest_from_asn1(digest_info_ptr,
digest_info_len, &p, &len,
&md_alg);
if ((ret != 0) || (md_alg != MBEDTLS_MD_SHA256) || (len != sizeof(calc_hash))) {
return CRYPTO_ERR_HASH;
}
digest_info_ptr = p;
digest_info_len = len;
stm32_hash_init(HASH_SHA256);
ret = stm32_hash_final_update(data_ptr, data_len, calc_hash);
if (ret != 0) {
VERBOSE("%s: hash failed\n", __func__);
return CRYPTO_ERR_HASH;
}
ret = memcmp(calc_hash, digest_info_ptr, digest_info_len);
if (ret != 0) {
VERBOSE("%s: not expected digest\n", __func__);
ret = CRYPTO_ERR_HASH;
}
return ret;
}
#if !defined(DECRYPTION_SUPPORT_none)
static int derive_key(uint8_t *key, size_t *key_len, size_t len,
unsigned int *flags, const uint8_t *img_id, size_t img_id_len)
{
size_t i, j;
assert(*key_len >= 32U);
/*
* Not a real derivation yet
*
* We expect a 32 bytes key, if OTP is only 16 bytes
* => duplicate.
*/
for (i = 0U, j = len; j < 32U;
i += sizeof(uint32_t), j += sizeof(uint32_t)) {
memcpy(key + j, key + i, sizeof(uint32_t));
}
*key_len = 32U;
/* Variable 'key' store a real key */
*flags = 0U;
return 0;
}
int plat_get_enc_key_info(enum fw_enc_status_t fw_enc_status, uint8_t *key,
size_t *key_len, unsigned int *flags,
const uint8_t *img_id, size_t img_id_len)
{
uint32_t otp_idx;
uint32_t otp_len;
size_t read_len;
size_t i;
if (fw_enc_status == FW_ENC_WITH_BSSK) {
return -EINVAL;
}
if (stm32_get_otp_index(ENCKEY_OTP, &otp_idx, &otp_len) != 0) {
VERBOSE("%s: get %s index error\n", __func__, ENCKEY_OTP);
return -EINVAL;
}
if (otp_len > (*key_len * CHAR_BIT)) {
VERBOSE("%s: length Error otp_len=%u key_len=%zu\n", __func__,
otp_len, *key_len * CHAR_BIT);
return -EINVAL;
}
read_len = otp_len / CHAR_BIT;
assert(read_len % sizeof(uint32_t) == 0);
for (i = 0U; i < read_len / sizeof(uint32_t); i++) {
uint32_t tmp;
uint32_t otp_val;
if (stm32_get_otp_value_from_idx(otp_idx + i, &otp_val) != 0) {
zeromem(key, *key_len);
VERBOSE("%s: unable to read from otp\n", __func__);
return -EINVAL;
}
tmp = bswap32(otp_val);
memcpy(key + i * sizeof(uint32_t), &tmp, sizeof(tmp));
}
/* Now we have the OTP values in key till read_len */
if (derive_key(key, key_len, read_len, flags, img_id,
img_id_len) != 0) {
zeromem(key, *key_len);
return -EINVAL;
}
return 0;
}
static enum stm32_saes_key_selection select_key(unsigned int key_flags)
{
if ((key_flags & ENC_KEY_IS_IDENTIFIER) != 0U) {
panic();
}
/* Use the provided key buffer */
return STM32_SAES_KEY_SOFT;
}
static int stm32_decrypt_aes_gcm(void *data, size_t data_len,
const void *key, unsigned int key_len,
unsigned int key_flags,
const void *iv, unsigned int iv_len,
const void *tag, unsigned int tag_len)
{
int ret;
struct stm32_saes_context ctx;
unsigned char tag_buf[CRYPTO_MAX_TAG_SIZE];
enum stm32_saes_key_selection key_mode;
unsigned int diff = 0U;
unsigned int i;
key_mode = select_key(key_flags);
ret = stm32_saes_init(&ctx, true, STM32_SAES_MODE_GCM, key_mode, key,
key_len, iv, iv_len);
if (ret != 0) {
return CRYPTO_ERR_INIT;
}
ret = stm32_saes_update_assodata(&ctx, true, NULL, 0U);
if (ret != 0) {
return CRYPTO_ERR_DECRYPTION;
}
ret = stm32_saes_update_load(&ctx, true, data, data, data_len);
if (ret != 0) {
return CRYPTO_ERR_DECRYPTION;
}
ret = stm32_saes_final(&ctx, tag_buf, sizeof(tag_buf));
if (ret != 0) {
return CRYPTO_ERR_DECRYPTION;
}
/* Check tag in "constant-time" */
for (i = 0U; i < tag_len; i++) {
diff |= ((const unsigned char *)tag)[i] ^ tag_buf[i];
}
if (diff != 0U) {
return CRYPTO_ERR_DECRYPTION;
}
return CRYPTO_SUCCESS;
}
/*
* Authenticated decryption of an image
*
*/
static int crypto_auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr, size_t len,
const void *key, unsigned int key_len, unsigned int key_flags,
const void *iv, unsigned int iv_len, const void *tag,
unsigned int tag_len)
{
int rc = -1;
uint32_t real_iv[4];
switch (dec_algo) {
case CRYPTO_GCM_DECRYPT:
/*
* GCM expect a Nonce
* The AES IV is the nonce (a uint32_t[3])
* then a counter (a uint32_t big endian)
* The counter starts at 2.
*/
memcpy(real_iv, iv, iv_len);
real_iv[3] = htobe32(0x2U);
rc = stm32_decrypt_aes_gcm(data_ptr, len, key, key_len, key_flags,
real_iv, sizeof(real_iv), tag, tag_len);
break;
default:
rc = CRYPTO_ERR_DECRYPTION;
break;
}
if (rc != 0) {
return rc;
}
return CRYPTO_SUCCESS;
}
REGISTER_CRYPTO_LIB("stm32_crypto_lib",
crypto_lib_init,
crypto_verify_signature,
crypto_verify_hash,
NULL,
crypto_auth_decrypt,
crypto_convert_pk);
#else /* No decryption support */
REGISTER_CRYPTO_LIB("stm32_crypto_lib",
crypto_lib_init,
crypto_verify_signature,
crypto_verify_hash,
NULL,
NULL,
crypto_convert_pk);
#endif