diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst index 654ddc54d..347cf20bc 100644 --- a/docs/getting_started/build-options.rst +++ b/docs/getting_started/build-options.rst @@ -1195,7 +1195,8 @@ Common build options The platform will use PSA compliant Crypto APIs during authentication and image measurement process by enabling this option. It uses APIs defined as per the `PSA Crypto API specification`_. This feature is only supported if - using MbedTLS 3.x version. By default it is disabled (``0``). + using MbedTLS 3.x version. By default it is disabled (``0``), and this is an + experimental feature. - ``ENABLE_CONSOLE_GETC``: Boolean option to enable `getc()` feature in console driver(s). By default it is disabled (``0``) because it constitutes an attack diff --git a/drivers/auth/mbedtls/mbedtls_psa_crypto.c b/drivers/auth/mbedtls/mbedtls_psa_crypto.c index 2fa8e63ee..5891acf37 100644 --- a/drivers/auth/mbedtls/mbedtls_psa_crypto.c +++ b/drivers/auth/mbedtls/mbedtls_psa_crypto.c @@ -28,6 +28,13 @@ #define LIB_NAME "mbed TLS PSA" +/* Maximum length of R_S pair in the ECDSA signature in bytes */ +#define MAX_ECDSA_R_S_PAIR_LEN 64U + +/* Size of ASN.1 length and tag in bytes*/ +#define SIZE_OF_ASN1_LEN 1U +#define SIZE_OF_ASN1_TAG 1U + #if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC /* @@ -108,6 +115,7 @@ CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC static void construct_psa_key_alg_and_type(mbedtls_pk_type_t pk_alg, mbedtls_md_type_t md_alg, + psa_ecc_family_t psa_ecc_family, psa_algorithm_t *psa_alg, psa_key_type_t *psa_key_type) { @@ -118,6 +126,10 @@ static void construct_psa_key_alg_and_type(mbedtls_pk_type_t pk_alg, *psa_alg = PSA_ALG_RSA_PSS(psa_md_alg); *psa_key_type = PSA_KEY_TYPE_RSA_PUBLIC_KEY; break; + case MBEDTLS_PK_ECDSA: + *psa_alg = PSA_ALG_ECDSA(psa_md_alg); + *psa_key_type = PSA_KEY_TYPE_ECC_PUBLIC_KEY(psa_ecc_family); + break; default: *psa_alg = PSA_ALG_NONE; *psa_key_type = PSA_KEY_TYPE_NONE; @@ -125,6 +137,161 @@ static void construct_psa_key_alg_and_type(mbedtls_pk_type_t pk_alg, } } + +#if TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_ECDSA || \ +TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA + +/* + * This is a helper function to detect padding byte (if the MSB bit of the + * first data byte is set to 1, for example 0x80) and on detection, ignore the + * padded byte(0x00) and increase the buffer pointer beyond padded byte and + * decrease the length of the buffer by 1. + * + * On Success returns 0, error otherwise. + **/ +static inline int ignore_asn1_int_padding_byte(unsigned char **buf_start, + size_t *buf_len) +{ + unsigned char *local_buf = *buf_start; + + /* Check for negative number */ + if ((local_buf[0] & 0x80U) != 0U) { + return -1; + } + + if ((local_buf[0] == 0U) && (local_buf[1] > 0x7FU) && + (*buf_len > 1U)) { + *buf_start = &local_buf[1]; + (*buf_len)--; + } + + return 0; +} + +/* + * This is a helper function that gets a pointer to the encoded ECDSA publicKey + * and its length (as per RFC5280) and returns corresponding decoded publicKey + * and its length. As well, it retrieves the family of ECC key in the PSA + * format. + * + * This function returns error(CRYPTO_ERR_SIGNATURE) on ASN.1 parsing failure, + * otherwise success(0). + **/ +static int get_ecdsa_pkinfo_from_asn1(unsigned char **pk_start, + unsigned int *pk_len, + psa_ecc_family_t *psa_ecc_family) +{ + mbedtls_asn1_buf alg_oid, alg_params; + mbedtls_ecp_group_id grp_id; + int rc; + unsigned char *pk_end; + size_t len; + size_t curve_bits; + unsigned char *pk_ptr = *pk_start; + + pk_end = pk_ptr + *pk_len; + rc = mbedtls_asn1_get_tag(&pk_ptr, pk_end, &len, + MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + pk_end = pk_ptr + len; + rc = mbedtls_asn1_get_alg(&pk_ptr, pk_end, &alg_oid, &alg_params); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + if (alg_params.tag == MBEDTLS_ASN1_OID) { + if (mbedtls_oid_get_ec_grp(&alg_params, &grp_id) != 0) { + return CRYPTO_ERR_SIGNATURE; + } + *psa_ecc_family = mbedtls_ecc_group_to_psa(grp_id, + &curve_bits); + } else { + return CRYPTO_ERR_SIGNATURE; + } + + pk_end = pk_ptr + len - (alg_oid.len + alg_params.len + + 2 * (SIZE_OF_ASN1_LEN + SIZE_OF_ASN1_TAG)); + rc = mbedtls_asn1_get_bitstring_null(&pk_ptr, pk_end, &len); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + *pk_start = pk_ptr; + *pk_len = len; + + return rc; +} + +/* + * Ecdsa-Sig-Value ::= SEQUENCE { + * r INTEGER, + * s INTEGER + * } + * + * This helper function that gets a pointer to the encoded ECDSA signature and + * its length (as per RFC5280) and returns corresponding decoded signature + * (R_S pair) and its size. + * + * This function returns error(CRYPTO_ERR_SIGNATURE) on ASN.1 parsing failure, + * otherwise success(0). + **/ +static int get_ecdsa_signature_from_asn1(unsigned char *sig_ptr, + size_t *sig_len, + unsigned char *r_s_pair) +{ + int rc; + unsigned char *sig_end; + size_t len, r_len, s_len; + + sig_end = sig_ptr + *sig_len; + rc = mbedtls_asn1_get_tag(&sig_ptr, sig_end, &len, + MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + sig_end = sig_ptr + len; + rc = mbedtls_asn1_get_tag(&sig_ptr, sig_end, &r_len, + MBEDTLS_ASN1_INTEGER); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + if (ignore_asn1_int_padding_byte(&sig_ptr, &r_len) != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + (void)memcpy((void *)&r_s_pair[0], (const void *)sig_ptr, r_len); + + sig_ptr = sig_ptr + r_len; + sig_end = sig_ptr + len - (r_len + (SIZE_OF_ASN1_LEN + + SIZE_OF_ASN1_TAG)); + rc = mbedtls_asn1_get_tag(&sig_ptr, sig_end, &s_len, + MBEDTLS_ASN1_INTEGER); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + if (ignore_asn1_int_padding_byte(&sig_ptr, &s_len) != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + (void)memcpy((void *)&r_s_pair[r_len], (const void *)sig_ptr, s_len); + + *sig_len = s_len + r_len; + + return 0; +} +#endif /* + * TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_ECDSA || \ + * TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA + **/ + /* * Verify a signature. * @@ -143,6 +310,10 @@ static int verify_signature(void *data_ptr, unsigned int data_len, int rc; void *sig_opts = NULL; unsigned char *p, *end; + unsigned char *local_sig_ptr; + size_t local_sig_len; + psa_ecc_family_t psa_ecc_family = 0U; + __unused unsigned char reformatted_sig[MAX_ECDSA_R_S_PAIR_LEN] = {0}; /* construct PSA key algo and type */ psa_status_t status = PSA_SUCCESS; @@ -174,10 +345,36 @@ static int verify_signature(void *data_ptr, unsigned int data_len, rc = CRYPTO_ERR_SIGNATURE; goto end2; } - signature.p = p; + + local_sig_ptr = p; + local_sig_len = signature.len; + +#if TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_ECDSA || \ +TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA + if (pk_alg == MBEDTLS_PK_ECDSA) { + rc = get_ecdsa_signature_from_asn1(local_sig_ptr, + &local_sig_len, + reformatted_sig); + if (rc != 0) { + goto end2; + } + + local_sig_ptr = reformatted_sig; + + rc = get_ecdsa_pkinfo_from_asn1((unsigned char **)&pk_ptr, + &pk_len, + &psa_ecc_family); + if (rc != 0) { + goto end2; + } + } +#endif /* + * TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_ECDSA || \ + * TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA + **/ /* Convert this pk_alg and md_alg to PSA key type and key algorithm */ - construct_psa_key_alg_and_type(pk_alg, md_alg, + construct_psa_key_alg_and_type(pk_alg, md_alg, psa_ecc_family, &psa_alg, &psa_key_type); @@ -208,7 +405,7 @@ static int verify_signature(void *data_ptr, unsigned int data_len, */ status = psa_verify_message(psa_key_id, psa_alg, data_ptr, data_len, - signature.p, signature.len); + local_sig_ptr, local_sig_len); if (status != PSA_SUCCESS) { rc = CRYPTO_ERR_SIGNATURE; diff --git a/plat/arm/board/fvp/include/platform_def.h b/plat/arm/board/fvp/include/platform_def.h index 836080a6e..aad04173b 100644 --- a/plat/arm/board/fvp/include/platform_def.h +++ b/plat/arm/board/fvp/include/platform_def.h @@ -193,8 +193,10 @@ defined(IMAGE_BL2) && MEASURED_BOOT /* * PLAT_ARM_MAX_BL1_RW_SIZE is calculated using the current BL1 RW debug size * plus a little space for growth. + * In case of PSA Crypto API, few algorithms like ECDSA needs bigger BL1 RW + * area. */ -#if TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA +#if TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA || PSA_CRYPTO #define PLAT_ARM_MAX_BL1_RW_SIZE UL(0xC000) #else #define PLAT_ARM_MAX_BL1_RW_SIZE UL(0xB000)