diff options
Diffstat (limited to 'drivers/auth/mbedtls')
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_common.c | 72 | ||||
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_common.mk | 111 | ||||
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_crypto.c | 394 | ||||
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_crypto.mk | 11 | ||||
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_x509.mk | 9 | ||||
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_x509_parser.c | 478 |
6 files changed, 1075 insertions, 0 deletions
diff --git a/drivers/auth/mbedtls/mbedtls_common.c b/drivers/auth/mbedtls/mbedtls_common.c new file mode 100644 index 0000000..a12e49c --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_common.c @@ -0,0 +1,72 @@ +/* + * Copyright (c) 2015-2022, Arm Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <assert.h> +#include <stddef.h> + +/* mbed TLS headers */ +#include <mbedtls/memory_buffer_alloc.h> +#include <mbedtls/platform.h> + +#include <common/debug.h> +#include <drivers/auth/mbedtls/mbedtls_common.h> +#include MBEDTLS_CONFIG_FILE +#include <plat/common/platform.h> + +static void cleanup(void) +{ + ERROR("EXIT from BL2\n"); + panic(); +} + +/* + * mbed TLS initialization function + */ +void mbedtls_init(void) +{ + static int ready; + void *heap_addr; + size_t heap_size = 0; + int err; + + if (!ready) { + if (atexit(cleanup)) + panic(); + + err = plat_get_mbedtls_heap(&heap_addr, &heap_size); + + /* Ensure heap setup is proper */ + if (err < 0) { + ERROR("Mbed TLS failed to get a heap\n"); + panic(); + } + assert(heap_size >= TF_MBEDTLS_HEAP_SIZE); + + /* Initialize the mbed TLS heap */ + mbedtls_memory_buffer_alloc_init(heap_addr, heap_size); + +#ifdef MBEDTLS_PLATFORM_SNPRINTF_ALT + mbedtls_platform_set_snprintf(snprintf); +#endif + ready = 1; + } +} + +/* + * The following helper function simply returns the default allocated heap. + * It can be used by platforms for their plat_get_mbedtls_heap() implementation. + */ +int get_mbedtls_heap_helper(void **heap_addr, size_t *heap_size) +{ + static unsigned char heap[TF_MBEDTLS_HEAP_SIZE]; + + assert(heap_addr != NULL); + assert(heap_size != NULL); + + *heap_addr = heap; + *heap_size = sizeof(heap); + return 0; +} diff --git a/drivers/auth/mbedtls/mbedtls_common.mk b/drivers/auth/mbedtls/mbedtls_common.mk new file mode 100644 index 0000000..16ce65f --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_common.mk @@ -0,0 +1,111 @@ +# +# Copyright (c) 2015-2022, Arm Limited. All rights reserved. +# +# SPDX-License-Identifier: BSD-3-Clause +# + +ifneq (${MBEDTLS_COMMON_MK},1) +MBEDTLS_COMMON_MK := 1 + +# MBEDTLS_DIR must be set to the mbed TLS main directory (it must contain +# the 'include' and 'library' subdirectories). +ifeq (${MBEDTLS_DIR},) + $(error Error: MBEDTLS_DIR not set) +endif + +MBEDTLS_INC = -I${MBEDTLS_DIR}/include + +# Specify mbed TLS configuration file +MBEDTLS_CONFIG_FILE ?= "<drivers/auth/mbedtls/mbedtls_config.h>" +$(eval $(call add_define,MBEDTLS_CONFIG_FILE)) + +MBEDTLS_SOURCES += drivers/auth/mbedtls/mbedtls_common.c + + +LIBMBEDTLS_SRCS := $(addprefix ${MBEDTLS_DIR}/library/, \ + aes.c \ + asn1parse.c \ + asn1write.c \ + cipher.c \ + cipher_wrap.c \ + memory_buffer_alloc.c \ + oid.c \ + platform.c \ + platform_util.c \ + bignum.c \ + gcm.c \ + md.c \ + pk.c \ + pk_wrap.c \ + pkparse.c \ + pkwrite.c \ + sha256.c \ + sha512.c \ + ecdsa.c \ + ecp_curves.c \ + ecp.c \ + rsa.c \ + rsa_internal.c \ + x509.c \ + x509_crt.c \ + constant_time.c \ + ) + +# The platform may define the variable 'TF_MBEDTLS_KEY_ALG' to select the key +# algorithm to use. If the variable is not defined, select it based on +# algorithm used for key generation `KEY_ALG`. If `KEY_ALG` is not defined, +# then it is set to `rsa`. +ifeq (${TF_MBEDTLS_KEY_ALG},) + ifeq (${KEY_ALG}, ecdsa) + TF_MBEDTLS_KEY_ALG := ecdsa + else + TF_MBEDTLS_KEY_ALG := rsa + endif +endif + +ifeq (${TF_MBEDTLS_KEY_SIZE},) + ifneq ($(findstring rsa,${TF_MBEDTLS_KEY_ALG}),) + ifeq (${KEY_SIZE},) + TF_MBEDTLS_KEY_SIZE := 2048 + else + TF_MBEDTLS_KEY_SIZE := ${KEY_SIZE} + endif + endif +endif + +ifeq (${HASH_ALG}, sha384) + TF_MBEDTLS_HASH_ALG_ID := TF_MBEDTLS_SHA384 +else ifeq (${HASH_ALG}, sha512) + TF_MBEDTLS_HASH_ALG_ID := TF_MBEDTLS_SHA512 +else + TF_MBEDTLS_HASH_ALG_ID := TF_MBEDTLS_SHA256 +endif + +ifeq (${TF_MBEDTLS_KEY_ALG},ecdsa) + TF_MBEDTLS_KEY_ALG_ID := TF_MBEDTLS_ECDSA +else ifeq (${TF_MBEDTLS_KEY_ALG},rsa) + TF_MBEDTLS_KEY_ALG_ID := TF_MBEDTLS_RSA +else ifeq (${TF_MBEDTLS_KEY_ALG},rsa+ecdsa) + TF_MBEDTLS_KEY_ALG_ID := TF_MBEDTLS_RSA_AND_ECDSA +else + $(error "TF_MBEDTLS_KEY_ALG=${TF_MBEDTLS_KEY_ALG} not supported on mbed TLS") +endif + +ifeq (${DECRYPTION_SUPPORT}, aes_gcm) + TF_MBEDTLS_USE_AES_GCM := 1 +else + TF_MBEDTLS_USE_AES_GCM := 0 +endif + +# Needs to be set to drive mbed TLS configuration correctly +$(eval $(call add_defines,\ + $(sort \ + TF_MBEDTLS_KEY_ALG_ID \ + TF_MBEDTLS_KEY_SIZE \ + TF_MBEDTLS_HASH_ALG_ID \ + TF_MBEDTLS_USE_AES_GCM \ +))) + +$(eval $(call MAKE_LIB,mbedtls)) + +endif diff --git a/drivers/auth/mbedtls/mbedtls_crypto.c b/drivers/auth/mbedtls/mbedtls_crypto.c new file mode 100644 index 0000000..d231179 --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_crypto.c @@ -0,0 +1,394 @@ +/* + * Copyright (c) 2015-2022, Arm Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <assert.h> +#include <stddef.h> +#include <string.h> + +/* mbed TLS headers */ +#include <mbedtls/gcm.h> +#include <mbedtls/md.h> +#include <mbedtls/memory_buffer_alloc.h> +#include <mbedtls/oid.h> +#include <mbedtls/platform.h> +#include <mbedtls/x509.h> + +#include <common/debug.h> +#include <drivers/auth/crypto_mod.h> +#include <drivers/auth/mbedtls/mbedtls_common.h> +#include <drivers/auth/mbedtls/mbedtls_config.h> +#include <plat/common/platform.h> + +#define LIB_NAME "mbed TLS" + +#if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ +CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC +/* + * CRYPTO_MD_MAX_SIZE value is as per current stronger algorithm available + * so make sure that mbed TLS MD maximum size must be lesser than this. + */ +CASSERT(CRYPTO_MD_MAX_SIZE >= MBEDTLS_MD_MAX_SIZE, + assert_mbedtls_md_size_overflow); + +#endif /* CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ + CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ + +/* + * AlgorithmIdentifier ::= SEQUENCE { + * algorithm OBJECT IDENTIFIER, + * parameters ANY DEFINED BY algorithm OPTIONAL + * } + * + * SubjectPublicKeyInfo ::= SEQUENCE { + * algorithm AlgorithmIdentifier, + * subjectPublicKey BIT STRING + * } + * + * DigestInfo ::= SEQUENCE { + * digestAlgorithm AlgorithmIdentifier, + * digest OCTET STRING + * } + */ + +/* + * Initialize the library and export the descriptor + */ +static void init(void) +{ + /* Initialize mbed TLS */ + mbedtls_init(); +} + +#if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ +CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC +/* + * Verify a signature. + * + * Parameters are passed using the DER encoding format following the ASN.1 + * structures detailed above. + */ +static int 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) +{ + mbedtls_asn1_buf sig_oid, sig_params; + mbedtls_asn1_buf signature; + mbedtls_md_type_t md_alg; + mbedtls_pk_type_t pk_alg; + mbedtls_pk_context pk = {0}; + int rc; + void *sig_opts = NULL; + const mbedtls_md_info_t *md_info; + unsigned char *p, *end; + unsigned char hash[MBEDTLS_MD_MAX_SIZE]; + + /* Get pointers to signature OID and parameters */ + p = (unsigned char *)sig_alg; + end = (unsigned char *)(p + sig_alg_len); + rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, &sig_params); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + /* Get the actual signature algorithm (MD + PK) */ + rc = mbedtls_x509_get_sig_alg(&sig_oid, &sig_params, &md_alg, &pk_alg, &sig_opts); + if (rc != 0) { + return CRYPTO_ERR_SIGNATURE; + } + + /* Parse the public key */ + mbedtls_pk_init(&pk); + p = (unsigned char *)pk_ptr; + end = (unsigned char *)(p + pk_len); + rc = mbedtls_pk_parse_subpubkey(&p, end, &pk); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end2; + } + + /* Get the signature (bitstring) */ + p = (unsigned char *)sig_ptr; + end = (unsigned char *)(p + sig_len); + signature.tag = *p; + rc = mbedtls_asn1_get_bitstring_null(&p, end, &signature.len); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + signature.p = p; + + /* Calculate the hash of the data */ + md_info = mbedtls_md_info_from_type(md_alg); + if (md_info == NULL) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + p = (unsigned char *)data_ptr; + rc = mbedtls_md(md_info, p, data_len, hash); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + + /* Verify the signature */ + rc = mbedtls_pk_verify_ext(pk_alg, sig_opts, &pk, md_alg, hash, + mbedtls_md_get_size(md_info), + signature.p, signature.len); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + + /* Signature verification success */ + rc = CRYPTO_SUCCESS; + +end1: + mbedtls_pk_free(&pk); +end2: + mbedtls_free(sig_opts); + return rc; +} + +/* + * Match a hash + * + * Digest info is passed in DER format following the ASN.1 structure detailed + * above. + */ +static int verify_hash(void *data_ptr, unsigned int data_len, + void *digest_info_ptr, unsigned int digest_info_len) +{ + mbedtls_asn1_buf hash_oid, params; + mbedtls_md_type_t md_alg; + const mbedtls_md_info_t *md_info; + unsigned char *p, *end, *hash; + unsigned char data_hash[MBEDTLS_MD_MAX_SIZE]; + size_t len; + int rc; + + /* Digest info should be an MBEDTLS_ASN1_SEQUENCE */ + p = (unsigned char *)digest_info_ptr; + end = p + digest_info_len; + rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + /* Get the hash algorithm */ + rc = mbedtls_asn1_get_alg(&p, end, &hash_oid, ¶ms); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + rc = mbedtls_oid_get_md_alg(&hash_oid, &md_alg); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + md_info = mbedtls_md_info_from_type(md_alg); + if (md_info == NULL) { + return CRYPTO_ERR_HASH; + } + + /* Hash should be octet string type */ + rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + /* Length of hash must match the algorithm's size */ + if (len != mbedtls_md_get_size(md_info)) { + return CRYPTO_ERR_HASH; + } + hash = p; + + /* Calculate the hash of the data */ + p = (unsigned char *)data_ptr; + rc = mbedtls_md(md_info, p, data_len, data_hash); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + /* Compare values */ + rc = memcmp(data_hash, hash, mbedtls_md_get_size(md_info)); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + return CRYPTO_SUCCESS; +} +#endif /* CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ + CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ + +#if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ +CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC +/* + * Map a generic crypto message digest algorithm to the corresponding macro used + * by Mbed TLS. + */ +static inline mbedtls_md_type_t md_type(enum crypto_md_algo algo) +{ + switch (algo) { + case CRYPTO_MD_SHA512: + return MBEDTLS_MD_SHA512; + case CRYPTO_MD_SHA384: + return MBEDTLS_MD_SHA384; + case CRYPTO_MD_SHA256: + return MBEDTLS_MD_SHA256; + default: + /* Invalid hash algorithm. */ + return MBEDTLS_MD_NONE; + } +} + +/* + * Calculate a hash + * + * output points to the computed hash + */ +static int calc_hash(enum crypto_md_algo md_algo, void *data_ptr, + unsigned int data_len, + unsigned char output[CRYPTO_MD_MAX_SIZE]) +{ + const mbedtls_md_info_t *md_info; + + md_info = mbedtls_md_info_from_type(md_type(md_algo)); + if (md_info == NULL) { + return CRYPTO_ERR_HASH; + } + + /* + * Calculate the hash of the data, it is safe to pass the + * 'output' hash buffer pointer considering its size is always + * bigger than or equal to MBEDTLS_MD_MAX_SIZE. + */ + return mbedtls_md(md_info, data_ptr, data_len, output); +} +#endif /* CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ + CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ + +#if TF_MBEDTLS_USE_AES_GCM +/* + * Stack based buffer allocation for decryption operation. It could + * be configured to balance stack usage vs execution speed. + */ +#define DEC_OP_BUF_SIZE 128 + +static int aes_gcm_decrypt(void *data_ptr, size_t len, const void *key, + unsigned int key_len, const void *iv, + unsigned int iv_len, const void *tag, + unsigned int tag_len) +{ + mbedtls_gcm_context ctx; + mbedtls_cipher_id_t cipher = MBEDTLS_CIPHER_ID_AES; + unsigned char buf[DEC_OP_BUF_SIZE]; + unsigned char tag_buf[CRYPTO_MAX_TAG_SIZE]; + unsigned char *pt = data_ptr; + size_t dec_len; + int diff, i, rc; + + mbedtls_gcm_init(&ctx); + + rc = mbedtls_gcm_setkey(&ctx, cipher, key, key_len * 8); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len, NULL, 0); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + while (len > 0) { + dec_len = MIN(sizeof(buf), len); + + rc = mbedtls_gcm_update(&ctx, dec_len, pt, buf); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + memcpy(pt, buf, dec_len); + pt += dec_len; + len -= dec_len; + } + + rc = mbedtls_gcm_finish(&ctx, tag_buf, sizeof(tag_buf)); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + /* Check tag in "constant-time" */ + for (diff = 0, i = 0; i < tag_len; i++) + diff |= ((const unsigned char *)tag)[i] ^ tag_buf[i]; + + if (diff != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + /* GCM decryption success */ + rc = CRYPTO_SUCCESS; + +exit_gcm: + mbedtls_gcm_free(&ctx); + return rc; +} + +/* + * Authenticated decryption of an image + */ +static int 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; + + assert((key_flags & ENC_KEY_IS_IDENTIFIER) == 0); + + switch (dec_algo) { + case CRYPTO_GCM_DECRYPT: + rc = aes_gcm_decrypt(data_ptr, len, key, key_len, iv, iv_len, + tag, tag_len); + if (rc != 0) + return rc; + break; + default: + return CRYPTO_ERR_DECRYPTION; + } + + return CRYPTO_SUCCESS; +} +#endif /* TF_MBEDTLS_USE_AES_GCM */ + +/* + * Register crypto library descriptor + */ +#if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC +#if TF_MBEDTLS_USE_AES_GCM +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, + auth_decrypt); +#else +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, + NULL); +#endif +#elif CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY +#if TF_MBEDTLS_USE_AES_GCM +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, + auth_decrypt); +#else +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL); +#endif +#elif CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY +REGISTER_CRYPTO_LIB(LIB_NAME, init, calc_hash); +#endif /* CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ diff --git a/drivers/auth/mbedtls/mbedtls_crypto.mk b/drivers/auth/mbedtls/mbedtls_crypto.mk new file mode 100644 index 0000000..2a9fbbf --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_crypto.mk @@ -0,0 +1,11 @@ +# +# Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved. +# +# SPDX-License-Identifier: BSD-3-Clause +# + +include drivers/auth/mbedtls/mbedtls_common.mk + +MBEDTLS_SOURCES += drivers/auth/mbedtls/mbedtls_crypto.c + + diff --git a/drivers/auth/mbedtls/mbedtls_x509.mk b/drivers/auth/mbedtls/mbedtls_x509.mk new file mode 100644 index 0000000..a0557e2 --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_x509.mk @@ -0,0 +1,9 @@ +# +# Copyright (c) 2015, ARM Limited and Contributors. All rights reserved. +# +# SPDX-License-Identifier: BSD-3-Clause +# + +include drivers/auth/mbedtls/mbedtls_common.mk + +MBEDTLS_SOURCES += drivers/auth/mbedtls/mbedtls_x509_parser.c diff --git a/drivers/auth/mbedtls/mbedtls_x509_parser.c b/drivers/auth/mbedtls/mbedtls_x509_parser.c new file mode 100644 index 0000000..993ef12 --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_x509_parser.c @@ -0,0 +1,478 @@ +/* + * Copyright (c) 2015-2022, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +/* + * X509 parser based on mbed TLS + * + * This module implements functions to check the integrity of a X509v3 + * certificate ASN.1 structure and extract authentication parameters from the + * extensions field, such as an image hash or a public key. + */ + +#include <assert.h> +#include <stddef.h> +#include <stdint.h> +#include <string.h> + +/* mbed TLS headers */ +#include <mbedtls/asn1.h> +#include <mbedtls/oid.h> +#include <mbedtls/platform.h> + +#include <arch_helpers.h> +#include <drivers/auth/img_parser_mod.h> +#include <drivers/auth/mbedtls/mbedtls_common.h> +#include <lib/utils.h> + +/* Maximum OID string length ("a.b.c.d.e.f ...") */ +#define MAX_OID_STR_LEN 64 + +#define LIB_NAME "mbed TLS X509v3" + +/* Temporary variables to speed up the authentication parameters search. These + * variables are assigned once during the integrity check and used any time an + * authentication parameter is requested, so we do not have to parse the image + * again */ +static mbedtls_asn1_buf tbs; +static mbedtls_asn1_buf v3_ext; +static mbedtls_asn1_buf pk; +static mbedtls_asn1_buf sig_alg; +static mbedtls_asn1_buf signature; + +/* + * Clear all static temporary variables. + */ +static void clear_temp_vars(void) +{ +#define ZERO_AND_CLEAN(x) \ + do { \ + zeromem(&x, sizeof(x)); \ + clean_dcache_range((uintptr_t)&x, sizeof(x)); \ + } while (0); + + ZERO_AND_CLEAN(tbs) + ZERO_AND_CLEAN(v3_ext); + ZERO_AND_CLEAN(pk); + ZERO_AND_CLEAN(sig_alg); + ZERO_AND_CLEAN(signature); + +#undef ZERO_AND_CLEAN +} + +/* + * Get X509v3 extension + * + * Global variable 'v3_ext' must point to the extensions region + * in the certificate. No need to check for errors since the image has passed + * the integrity check. + */ +static int get_ext(const char *oid, void **ext, unsigned int *ext_len) +{ + int oid_len; + size_t len; + unsigned char *end_ext_data, *end_ext_octet; + unsigned char *p; + const unsigned char *end; + char oid_str[MAX_OID_STR_LEN]; + mbedtls_asn1_buf extn_oid; + int is_critical; + + assert(oid != NULL); + + p = v3_ext.p; + end = v3_ext.p + v3_ext.len; + + mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + + while (p < end) { + zeromem(&extn_oid, sizeof(extn_oid)); + is_critical = 0; /* DEFAULT FALSE */ + + mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + end_ext_data = p + len; + + /* Get extension ID */ + extn_oid.tag = *p; + mbedtls_asn1_get_tag(&p, end, &extn_oid.len, MBEDTLS_ASN1_OID); + extn_oid.p = p; + p += extn_oid.len; + + /* Get optional critical */ + mbedtls_asn1_get_bool(&p, end_ext_data, &is_critical); + + /* Extension data */ + mbedtls_asn1_get_tag(&p, end_ext_data, &len, + MBEDTLS_ASN1_OCTET_STRING); + end_ext_octet = p + len; + + /* Detect requested extension */ + oid_len = mbedtls_oid_get_numeric_string(oid_str, + MAX_OID_STR_LEN, + &extn_oid); + if ((oid_len == MBEDTLS_ERR_OID_BUF_TOO_SMALL) || (oid_len < 0)) { + return IMG_PARSER_ERR; + } + if (((size_t)oid_len == strlen(oid_str)) && !strcmp(oid, oid_str)) { + *ext = (void *)p; + *ext_len = (unsigned int)len; + return IMG_PARSER_OK; + } + + /* Next */ + p = end_ext_octet; + } + + return IMG_PARSER_ERR_NOT_FOUND; +} + + +/* + * Check the integrity of the certificate ASN.1 structure. + * + * Extract the relevant data that will be used later during authentication. + * + * This function doesn't clear the static variables located on the top of this + * file in case of an error. It is only called from check_integrity(), which + * performs the cleanup if necessary. + */ +static int cert_parse(void *img, unsigned int img_len) +{ + int ret, is_critical; + size_t len; + unsigned char *p, *end, *crt_end; + mbedtls_asn1_buf sig_alg1, sig_alg2; + + p = (unsigned char *)img; + len = img_len; + end = p + len; + + /* + * Certificate ::= SEQUENCE { + * tbsCertificate TBSCertificate, + * signatureAlgorithm AlgorithmIdentifier, + * signatureValue BIT STRING } + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + + if (len > (size_t)(end - p)) { + return IMG_PARSER_ERR_FORMAT; + } + crt_end = p + len; + + /* + * TBSCertificate ::= SEQUENCE { + */ + tbs.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + end = p + len; + tbs.len = end - tbs.p; + + /* + * Version ::= INTEGER { v1(0), v2(1), v3(2) } + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_CONTEXT_SPECIFIC | + MBEDTLS_ASN1_CONSTRUCTED | 0); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* + * CertificateSerialNumber ::= INTEGER + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* + * signature AlgorithmIdentifier + */ + sig_alg1.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + if ((end - p) < 1) { + return IMG_PARSER_ERR_FORMAT; + } + sig_alg1.len = (p + len) - sig_alg1.p; + p += len; + + /* + * issuer Name + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* + * Validity ::= SEQUENCE { + * notBefore Time, + * notAfter Time } + * + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* + * subject Name + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* + * SubjectPublicKeyInfo + */ + pk.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + pk.len = (p + len) - pk.p; + p += len; + + /* + * issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL, + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_CONTEXT_SPECIFIC | + MBEDTLS_ASN1_CONSTRUCTED | 1); + if (ret != 0) { + if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { + return IMG_PARSER_ERR_FORMAT; + } + } else { + p += len; + } + + /* + * subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL, + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_CONTEXT_SPECIFIC | + MBEDTLS_ASN1_CONSTRUCTED | 2); + if (ret != 0) { + if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { + return IMG_PARSER_ERR_FORMAT; + } + } else { + p += len; + } + + /* + * extensions [3] EXPLICIT Extensions OPTIONAL + */ + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_CONTEXT_SPECIFIC | + MBEDTLS_ASN1_CONSTRUCTED | 3); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + + /* + * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension + */ + v3_ext.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + v3_ext.len = (p + len) - v3_ext.p; + + /* + * Check extensions integrity + */ + while (p < end) { + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + + /* Get extension ID */ + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OID); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + + /* Get optional critical */ + ret = mbedtls_asn1_get_bool(&p, end, &is_critical); + if ((ret != 0) && (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG)) { + return IMG_PARSER_ERR_FORMAT; + } + + /* Data should be octet string type */ + ret = mbedtls_asn1_get_tag(&p, end, &len, + MBEDTLS_ASN1_OCTET_STRING); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + p += len; + } + + if (p != end) { + return IMG_PARSER_ERR_FORMAT; + } + + end = crt_end; + + /* + * } + * -- end of TBSCertificate + * + * signatureAlgorithm AlgorithmIdentifier + */ + sig_alg2.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + if ((end - p) < 1) { + return IMG_PARSER_ERR_FORMAT; + } + sig_alg2.len = (p + len) - sig_alg2.p; + p += len; + + /* Compare both signature algorithms */ + if (sig_alg1.len != sig_alg2.len) { + return IMG_PARSER_ERR_FORMAT; + } + if (0 != memcmp(sig_alg1.p, sig_alg2.p, sig_alg1.len)) { + return IMG_PARSER_ERR_FORMAT; + } + memcpy(&sig_alg, &sig_alg1, sizeof(sig_alg)); + + /* + * signatureValue BIT STRING + */ + signature.p = p; + ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_BIT_STRING); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } + signature.len = (p + len) - signature.p; + p += len; + + /* Check certificate length */ + if (p != end) { + return IMG_PARSER_ERR_FORMAT; + } + + return IMG_PARSER_OK; +} + + +/* Exported functions */ + +static void init(void) +{ + mbedtls_init(); +} + +/* + * Wrapper for cert_parse() that clears the static variables used by it in case + * of an error. + */ +static int check_integrity(void *img, unsigned int img_len) +{ + int rc = cert_parse(img, img_len); + + if (rc != IMG_PARSER_OK) + clear_temp_vars(); + + return rc; +} + +/* + * Extract an authentication parameter from an X509v3 certificate + * + * This function returns a pointer to the extracted data and its length. + * Depending on the type of parameter, a pointer to the data stored in the + * certificate may be returned (i.e. an octet string containing a hash). Other + * data may need to be copied and formatted (i.e. integers). In the later case, + * a buffer of the correct type needs to be statically allocated, filled and + * returned. + */ +static int get_auth_param(const auth_param_type_desc_t *type_desc, + void *img, unsigned int img_len, + void **param, unsigned int *param_len) +{ + int rc = IMG_PARSER_OK; + + /* We do not use img because the check_integrity function has already + * extracted the relevant data (v3_ext, pk, sig_alg, etc) */ + + switch (type_desc->type) { + case AUTH_PARAM_RAW_DATA: + /* Data to be signed */ + *param = (void *)tbs.p; + *param_len = (unsigned int)tbs.len; + break; + case AUTH_PARAM_HASH: + case AUTH_PARAM_NV_CTR: + /* All these parameters are included as X509v3 extensions */ + rc = get_ext(type_desc->cookie, param, param_len); + break; + case AUTH_PARAM_PUB_KEY: + if (type_desc->cookie != 0) { + /* Get public key from extension */ + rc = get_ext(type_desc->cookie, param, param_len); + } else { + /* Get the subject public key */ + *param = (void *)pk.p; + *param_len = (unsigned int)pk.len; + } + break; + case AUTH_PARAM_SIG_ALG: + /* Get the certificate signature algorithm */ + *param = (void *)sig_alg.p; + *param_len = (unsigned int)sig_alg.len; + break; + case AUTH_PARAM_SIG: + /* Get the certificate signature */ + *param = (void *)signature.p; + *param_len = (unsigned int)signature.len; + break; + default: + rc = IMG_PARSER_ERR_NOT_FOUND; + break; + } + + return rc; +} + +REGISTER_IMG_PARSER_LIB(IMG_CERT, LIB_NAME, init, \ + check_integrity, get_auth_param); |