diff options
Diffstat (limited to 'src/cbor.c')
-rw-r--r-- | src/cbor.c | 1705 |
1 files changed, 1705 insertions, 0 deletions
diff --git a/src/cbor.c b/src/cbor.c new file mode 100644 index 0000000..ab99b34 --- /dev/null +++ b/src/cbor.c @@ -0,0 +1,1705 @@ +/* + * Copyright (c) 2018-2022 Yubico AB. All rights reserved. + * Use of this source code is governed by a BSD-style + * license that can be found in the LICENSE file. + * SPDX-License-Identifier: BSD-2-Clause + */ + +#include <openssl/hmac.h> +#include <openssl/sha.h> +#include "fido.h" + +static int +check_key_type(cbor_item_t *item) +{ + if (item->type == CBOR_TYPE_UINT || item->type == CBOR_TYPE_NEGINT || + item->type == CBOR_TYPE_STRING) + return (0); + + fido_log_debug("%s: invalid type: %d", __func__, item->type); + + return (-1); +} + +/* + * Validate CTAP2 canonical CBOR encoding rules for maps. + */ +static int +ctap_check_cbor(cbor_item_t *prev, cbor_item_t *curr) +{ + size_t curr_len; + size_t prev_len; + + if (check_key_type(prev) < 0 || check_key_type(curr) < 0) + return (-1); + + if (prev->type != curr->type) { + if (prev->type < curr->type) + return (0); + fido_log_debug("%s: unsorted types", __func__); + return (-1); + } + + if (curr->type == CBOR_TYPE_UINT || curr->type == CBOR_TYPE_NEGINT) { + if (cbor_int_get_width(curr) >= cbor_int_get_width(prev) && + cbor_get_int(curr) > cbor_get_int(prev)) + return (0); + } else { + curr_len = cbor_string_length(curr); + prev_len = cbor_string_length(prev); + + if (curr_len > prev_len || (curr_len == prev_len && + memcmp(cbor_string_handle(prev), cbor_string_handle(curr), + curr_len) < 0)) + return (0); + } + + fido_log_debug("%s: invalid cbor", __func__); + + return (-1); +} + +int +cbor_map_iter(const cbor_item_t *item, void *arg, int(*f)(const cbor_item_t *, + const cbor_item_t *, void *)) +{ + struct cbor_pair *v; + size_t n; + + if ((v = cbor_map_handle(item)) == NULL) { + fido_log_debug("%s: cbor_map_handle", __func__); + return (-1); + } + + n = cbor_map_size(item); + + for (size_t i = 0; i < n; i++) { + if (v[i].key == NULL || v[i].value == NULL) { + fido_log_debug("%s: key=%p, value=%p for i=%zu", + __func__, (void *)v[i].key, (void *)v[i].value, i); + return (-1); + } + if (i && ctap_check_cbor(v[i - 1].key, v[i].key) < 0) { + fido_log_debug("%s: ctap_check_cbor", __func__); + return (-1); + } + if (f(v[i].key, v[i].value, arg) < 0) { + fido_log_debug("%s: iterator < 0 on i=%zu", __func__, + i); + return (-1); + } + } + + return (0); +} + +int +cbor_array_iter(const cbor_item_t *item, void *arg, int(*f)(const cbor_item_t *, + void *)) +{ + cbor_item_t **v; + size_t n; + + if ((v = cbor_array_handle(item)) == NULL) { + fido_log_debug("%s: cbor_array_handle", __func__); + return (-1); + } + + n = cbor_array_size(item); + + for (size_t i = 0; i < n; i++) + if (v[i] == NULL || f(v[i], arg) < 0) { + fido_log_debug("%s: iterator < 0 on i=%zu,%p", + __func__, i, (void *)v[i]); + return (-1); + } + + return (0); +} + +int +cbor_parse_reply(const unsigned char *blob, size_t blob_len, void *arg, + int(*parser)(const cbor_item_t *, const cbor_item_t *, void *)) +{ + cbor_item_t *item = NULL; + struct cbor_load_result cbor; + int r; + + if (blob_len < 1) { + fido_log_debug("%s: blob_len=%zu", __func__, blob_len); + r = FIDO_ERR_RX; + goto fail; + } + + if (blob[0] != FIDO_OK) { + fido_log_debug("%s: blob[0]=0x%02x", __func__, blob[0]); + r = blob[0]; + goto fail; + } + + if ((item = cbor_load(blob + 1, blob_len - 1, &cbor)) == NULL) { + fido_log_debug("%s: cbor_load", __func__); + r = FIDO_ERR_RX_NOT_CBOR; + goto fail; + } + + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false) { + fido_log_debug("%s: cbor type", __func__); + r = FIDO_ERR_RX_INVALID_CBOR; + goto fail; + } + + if (cbor_map_iter(item, arg, parser) < 0) { + fido_log_debug("%s: cbor_map_iter", __func__); + r = FIDO_ERR_RX_INVALID_CBOR; + goto fail; + } + + r = FIDO_OK; +fail: + if (item != NULL) + cbor_decref(&item); + + return (r); +} + +void +cbor_vector_free(cbor_item_t **item, size_t len) +{ + for (size_t i = 0; i < len; i++) + if (item[i] != NULL) + cbor_decref(&item[i]); +} + +int +cbor_bytestring_copy(const cbor_item_t *item, unsigned char **buf, size_t *len) +{ + if (*buf != NULL || *len != 0) { + fido_log_debug("%s: dup", __func__); + return (-1); + } + + if (cbor_isa_bytestring(item) == false || + cbor_bytestring_is_definite(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + *len = cbor_bytestring_length(item); + if ((*buf = malloc(*len)) == NULL) { + *len = 0; + return (-1); + } + + memcpy(*buf, cbor_bytestring_handle(item), *len); + + return (0); +} + +int +cbor_string_copy(const cbor_item_t *item, char **str) +{ + size_t len; + + if (*str != NULL) { + fido_log_debug("%s: dup", __func__); + return (-1); + } + + if (cbor_isa_string(item) == false || + cbor_string_is_definite(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + if ((len = cbor_string_length(item)) == SIZE_MAX || + (*str = malloc(len + 1)) == NULL) + return (-1); + + memcpy(*str, cbor_string_handle(item), len); + (*str)[len] = '\0'; + + return (0); +} + +int +cbor_add_bytestring(cbor_item_t *item, const char *key, + const unsigned char *value, size_t value_len) +{ + struct cbor_pair pair; + int ok = -1; + + memset(&pair, 0, sizeof(pair)); + + if ((pair.key = cbor_build_string(key)) == NULL || + (pair.value = cbor_build_bytestring(value, value_len)) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + goto fail; + } + + ok = 0; +fail: + if (pair.key) + cbor_decref(&pair.key); + if (pair.value) + cbor_decref(&pair.value); + + return (ok); +} + +int +cbor_add_string(cbor_item_t *item, const char *key, const char *value) +{ + struct cbor_pair pair; + int ok = -1; + + memset(&pair, 0, sizeof(pair)); + + if ((pair.key = cbor_build_string(key)) == NULL || + (pair.value = cbor_build_string(value)) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + goto fail; + } + + ok = 0; +fail: + if (pair.key) + cbor_decref(&pair.key); + if (pair.value) + cbor_decref(&pair.value); + + return (ok); +} + +int +cbor_add_bool(cbor_item_t *item, const char *key, fido_opt_t value) +{ + struct cbor_pair pair; + int ok = -1; + + memset(&pair, 0, sizeof(pair)); + + if ((pair.key = cbor_build_string(key)) == NULL || + (pair.value = cbor_build_bool(value == FIDO_OPT_TRUE)) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + goto fail; + } + + ok = 0; +fail: + if (pair.key) + cbor_decref(&pair.key); + if (pair.value) + cbor_decref(&pair.value); + + return (ok); +} + +static int +cbor_add_uint8(cbor_item_t *item, const char *key, uint8_t value) +{ + struct cbor_pair pair; + int ok = -1; + + memset(&pair, 0, sizeof(pair)); + + if ((pair.key = cbor_build_string(key)) == NULL || + (pair.value = cbor_build_uint8(value)) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + goto fail; + } + + ok = 0; +fail: + if (pair.key) + cbor_decref(&pair.key); + if (pair.value) + cbor_decref(&pair.value); + + return (ok); +} + +static int +cbor_add_arg(cbor_item_t *item, uint8_t n, cbor_item_t *arg) +{ + struct cbor_pair pair; + int ok = -1; + + memset(&pair, 0, sizeof(pair)); + + if (arg == NULL) + return (0); /* empty argument */ + + if ((pair.key = cbor_build_uint8(n)) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + pair.value = arg; + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + goto fail; + } + + ok = 0; +fail: + if (pair.key) + cbor_decref(&pair.key); + + return (ok); +} + +cbor_item_t * +cbor_flatten_vector(cbor_item_t *argv[], size_t argc) +{ + cbor_item_t *map; + uint8_t i; + + if (argc > UINT8_MAX - 1) + return (NULL); + + if ((map = cbor_new_definite_map(argc)) == NULL) + return (NULL); + + for (i = 0; i < argc; i++) + if (cbor_add_arg(map, (uint8_t)(i + 1), argv[i]) < 0) + break; + + if (i != argc) { + cbor_decref(&map); + map = NULL; + } + + return (map); +} + +int +cbor_build_frame(uint8_t cmd, cbor_item_t *argv[], size_t argc, fido_blob_t *f) +{ + cbor_item_t *flat = NULL; + unsigned char *cbor = NULL; + size_t cbor_len; + size_t cbor_alloc_len; + int ok = -1; + + if ((flat = cbor_flatten_vector(argv, argc)) == NULL) + goto fail; + + cbor_len = cbor_serialize_alloc(flat, &cbor, &cbor_alloc_len); + if (cbor_len == 0 || cbor_len == SIZE_MAX) { + fido_log_debug("%s: cbor_len=%zu", __func__, cbor_len); + goto fail; + } + + if ((f->ptr = malloc(cbor_len + 1)) == NULL) + goto fail; + + f->len = cbor_len + 1; + f->ptr[0] = cmd; + memcpy(f->ptr + 1, cbor, f->len - 1); + + ok = 0; +fail: + if (flat != NULL) + cbor_decref(&flat); + + free(cbor); + + return (ok); +} + +cbor_item_t * +cbor_encode_rp_entity(const fido_rp_t *rp) +{ + cbor_item_t *item = NULL; + + if ((item = cbor_new_definite_map(2)) == NULL) + return (NULL); + + if ((rp->id && cbor_add_string(item, "id", rp->id) < 0) || + (rp->name && cbor_add_string(item, "name", rp->name) < 0)) { + cbor_decref(&item); + return (NULL); + } + + return (item); +} + +cbor_item_t * +cbor_encode_user_entity(const fido_user_t *user) +{ + cbor_item_t *item = NULL; + const fido_blob_t *id = &user->id; + const char *display = user->display_name; + + if ((item = cbor_new_definite_map(4)) == NULL) + return (NULL); + + if ((id->ptr && cbor_add_bytestring(item, "id", id->ptr, id->len) < 0) || + (user->icon && cbor_add_string(item, "icon", user->icon) < 0) || + (user->name && cbor_add_string(item, "name", user->name) < 0) || + (display && cbor_add_string(item, "displayName", display) < 0)) { + cbor_decref(&item); + return (NULL); + } + + return (item); +} + +cbor_item_t * +cbor_encode_pubkey_param(int cose_alg) +{ + cbor_item_t *item = NULL; + cbor_item_t *body = NULL; + struct cbor_pair alg; + int ok = -1; + + memset(&alg, 0, sizeof(alg)); + + if ((item = cbor_new_definite_array(1)) == NULL || + (body = cbor_new_definite_map(2)) == NULL || + cose_alg > -1 || cose_alg < INT16_MIN) + goto fail; + + alg.key = cbor_build_string("alg"); + + if (-cose_alg - 1 > UINT8_MAX) + alg.value = cbor_build_negint16((uint16_t)(-cose_alg - 1)); + else + alg.value = cbor_build_negint8((uint8_t)(-cose_alg - 1)); + + if (alg.key == NULL || alg.value == NULL) { + fido_log_debug("%s: cbor_build", __func__); + goto fail; + } + + if (cbor_map_add(body, alg) == false || + cbor_add_string(body, "type", "public-key") < 0 || + cbor_array_push(item, body) == false) + goto fail; + + ok = 0; +fail: + if (ok < 0) { + if (item != NULL) { + cbor_decref(&item); + item = NULL; + } + } + + if (body != NULL) + cbor_decref(&body); + if (alg.key != NULL) + cbor_decref(&alg.key); + if (alg.value != NULL) + cbor_decref(&alg.value); + + return (item); +} + +cbor_item_t * +cbor_encode_pubkey(const fido_blob_t *pubkey) +{ + cbor_item_t *cbor_key = NULL; + + if ((cbor_key = cbor_new_definite_map(2)) == NULL || + cbor_add_bytestring(cbor_key, "id", pubkey->ptr, pubkey->len) < 0 || + cbor_add_string(cbor_key, "type", "public-key") < 0) { + if (cbor_key) + cbor_decref(&cbor_key); + return (NULL); + } + + return (cbor_key); +} + +cbor_item_t * +cbor_encode_pubkey_list(const fido_blob_array_t *list) +{ + cbor_item_t *array = NULL; + cbor_item_t *key = NULL; + + if ((array = cbor_new_definite_array(list->len)) == NULL) + goto fail; + + for (size_t i = 0; i < list->len; i++) { + if ((key = cbor_encode_pubkey(&list->ptr[i])) == NULL || + cbor_array_push(array, key) == false) + goto fail; + cbor_decref(&key); + } + + return (array); +fail: + if (key != NULL) + cbor_decref(&key); + if (array != NULL) + cbor_decref(&array); + + return (NULL); +} + +cbor_item_t * +cbor_encode_str_array(const fido_str_array_t *a) +{ + cbor_item_t *array = NULL; + cbor_item_t *entry = NULL; + + if ((array = cbor_new_definite_array(a->len)) == NULL) + goto fail; + + for (size_t i = 0; i < a->len; i++) { + if ((entry = cbor_build_string(a->ptr[i])) == NULL || + cbor_array_push(array, entry) == false) + goto fail; + cbor_decref(&entry); + } + + return (array); +fail: + if (entry != NULL) + cbor_decref(&entry); + if (array != NULL) + cbor_decref(&array); + + return (NULL); +} + +static int +cbor_encode_largeblob_key_ext(cbor_item_t *map) +{ + if (map == NULL || + cbor_add_bool(map, "largeBlobKey", FIDO_OPT_TRUE) < 0) + return (-1); + + return (0); +} + +cbor_item_t * +cbor_encode_cred_ext(const fido_cred_ext_t *ext, const fido_blob_t *blob) +{ + cbor_item_t *item = NULL; + size_t size = 0; + + if (ext->mask & FIDO_EXT_CRED_BLOB) + size++; + if (ext->mask & FIDO_EXT_HMAC_SECRET) + size++; + if (ext->mask & FIDO_EXT_CRED_PROTECT) + size++; + if (ext->mask & FIDO_EXT_LARGEBLOB_KEY) + size++; + if (ext->mask & FIDO_EXT_MINPINLEN) + size++; + + if (size == 0 || (item = cbor_new_definite_map(size)) == NULL) + return (NULL); + + if (ext->mask & FIDO_EXT_CRED_BLOB) { + if (cbor_add_bytestring(item, "credBlob", blob->ptr, + blob->len) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_CRED_PROTECT) { + if (ext->prot < 0 || ext->prot > UINT8_MAX || + cbor_add_uint8(item, "credProtect", + (uint8_t)ext->prot) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_HMAC_SECRET) { + if (cbor_add_bool(item, "hmac-secret", FIDO_OPT_TRUE) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_LARGEBLOB_KEY) { + if (cbor_encode_largeblob_key_ext(item) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_MINPINLEN) { + if (cbor_add_bool(item, "minPinLength", FIDO_OPT_TRUE) < 0) { + cbor_decref(&item); + return (NULL); + } + } + + return (item); +} + +cbor_item_t * +cbor_encode_cred_opt(fido_opt_t rk, fido_opt_t uv) +{ + cbor_item_t *item = NULL; + + if ((item = cbor_new_definite_map(2)) == NULL) + return (NULL); + if ((rk != FIDO_OPT_OMIT && cbor_add_bool(item, "rk", rk) < 0) || + (uv != FIDO_OPT_OMIT && cbor_add_bool(item, "uv", uv) < 0)) { + cbor_decref(&item); + return (NULL); + } + + return (item); +} + +cbor_item_t * +cbor_encode_assert_opt(fido_opt_t up, fido_opt_t uv) +{ + cbor_item_t *item = NULL; + + if ((item = cbor_new_definite_map(2)) == NULL) + return (NULL); + if ((up != FIDO_OPT_OMIT && cbor_add_bool(item, "up", up) < 0) || + (uv != FIDO_OPT_OMIT && cbor_add_bool(item, "uv", uv) < 0)) { + cbor_decref(&item); + return (NULL); + } + + return (item); +} + +cbor_item_t * +cbor_encode_pin_auth(const fido_dev_t *dev, const fido_blob_t *secret, + const fido_blob_t *data) +{ + const EVP_MD *md = NULL; + unsigned char dgst[SHA256_DIGEST_LENGTH]; + unsigned int dgst_len; + size_t outlen; + uint8_t prot; + fido_blob_t key; + + key.ptr = secret->ptr; + key.len = secret->len; + + if ((prot = fido_dev_get_pin_protocol(dev)) == 0) { + fido_log_debug("%s: fido_dev_get_pin_protocol", __func__); + return (NULL); + } + + /* select hmac portion of the shared secret */ + if (prot == CTAP_PIN_PROTOCOL2 && key.len > 32) + key.len = 32; + + if ((md = EVP_sha256()) == NULL || HMAC(md, key.ptr, + (int)key.len, data->ptr, data->len, dgst, + &dgst_len) == NULL || dgst_len != SHA256_DIGEST_LENGTH) + return (NULL); + + outlen = (prot == CTAP_PIN_PROTOCOL1) ? 16 : dgst_len; + + return (cbor_build_bytestring(dgst, outlen)); +} + +cbor_item_t * +cbor_encode_pin_opt(const fido_dev_t *dev) +{ + uint8_t prot; + + if ((prot = fido_dev_get_pin_protocol(dev)) == 0) { + fido_log_debug("%s: fido_dev_get_pin_protocol", __func__); + return (NULL); + } + + return (cbor_build_uint8(prot)); +} + +cbor_item_t * +cbor_encode_change_pin_auth(const fido_dev_t *dev, const fido_blob_t *secret, + const fido_blob_t *new_pin_enc, const fido_blob_t *pin_hash_enc) +{ + unsigned char dgst[SHA256_DIGEST_LENGTH]; + unsigned int dgst_len; + cbor_item_t *item = NULL; + const EVP_MD *md = NULL; + HMAC_CTX *ctx = NULL; + fido_blob_t key; + uint8_t prot; + size_t outlen; + + key.ptr = secret->ptr; + key.len = secret->len; + + if ((prot = fido_dev_get_pin_protocol(dev)) == 0) { + fido_log_debug("%s: fido_dev_get_pin_protocol", __func__); + goto fail; + } + + if (prot == CTAP_PIN_PROTOCOL2 && key.len > 32) + key.len = 32; + + if ((ctx = HMAC_CTX_new()) == NULL || + (md = EVP_sha256()) == NULL || + HMAC_Init_ex(ctx, key.ptr, (int)key.len, md, NULL) == 0 || + HMAC_Update(ctx, new_pin_enc->ptr, new_pin_enc->len) == 0 || + HMAC_Update(ctx, pin_hash_enc->ptr, pin_hash_enc->len) == 0 || + HMAC_Final(ctx, dgst, &dgst_len) == 0 || + dgst_len != SHA256_DIGEST_LENGTH) { + fido_log_debug("%s: HMAC", __func__); + goto fail; + } + + outlen = (prot == CTAP_PIN_PROTOCOL1) ? 16 : dgst_len; + + if ((item = cbor_build_bytestring(dgst, outlen)) == NULL) { + fido_log_debug("%s: cbor_build_bytestring", __func__); + goto fail; + } + +fail: + HMAC_CTX_free(ctx); + + return (item); +} + +static int +cbor_encode_hmac_secret_param(const fido_dev_t *dev, cbor_item_t *item, + const fido_blob_t *ecdh, const es256_pk_t *pk, const fido_blob_t *salt) +{ + cbor_item_t *param = NULL; + cbor_item_t *argv[4]; + struct cbor_pair pair; + fido_blob_t *enc = NULL; + uint8_t prot; + int r; + + memset(argv, 0, sizeof(argv)); + memset(&pair, 0, sizeof(pair)); + + if (item == NULL || ecdh == NULL || pk == NULL || salt->ptr == NULL) { + fido_log_debug("%s: ecdh=%p, pk=%p, salt->ptr=%p", __func__, + (const void *)ecdh, (const void *)pk, + (const void *)salt->ptr); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + if (salt->len != 32 && salt->len != 64) { + fido_log_debug("%s: salt->len=%zu", __func__, salt->len); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + if ((enc = fido_blob_new()) == NULL || + aes256_cbc_enc(dev, ecdh, salt, enc) < 0) { + fido_log_debug("%s: aes256_cbc_enc", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + if ((prot = fido_dev_get_pin_protocol(dev)) == 0) { + fido_log_debug("%s: fido_dev_get_pin_protocol", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + /* XXX not pin, but salt */ + if ((argv[0] = es256_pk_encode(pk, 1)) == NULL || + (argv[1] = fido_blob_encode(enc)) == NULL || + (argv[2] = cbor_encode_pin_auth(dev, ecdh, enc)) == NULL || + (prot != 1 && (argv[3] = cbor_build_uint8(prot)) == NULL)) { + fido_log_debug("%s: cbor encode", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + if ((param = cbor_flatten_vector(argv, nitems(argv))) == NULL) { + fido_log_debug("%s: cbor_flatten_vector", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + if ((pair.key = cbor_build_string("hmac-secret")) == NULL) { + fido_log_debug("%s: cbor_build", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + pair.value = param; + + if (!cbor_map_add(item, pair)) { + fido_log_debug("%s: cbor_map_add", __func__); + r = FIDO_ERR_INTERNAL; + goto fail; + } + + r = FIDO_OK; + +fail: + cbor_vector_free(argv, nitems(argv)); + + if (param != NULL) + cbor_decref(¶m); + if (pair.key != NULL) + cbor_decref(&pair.key); + + fido_blob_free(&enc); + + return (r); +} + +cbor_item_t * +cbor_encode_assert_ext(fido_dev_t *dev, const fido_assert_ext_t *ext, + const fido_blob_t *ecdh, const es256_pk_t *pk) +{ + cbor_item_t *item = NULL; + size_t size = 0; + + if (ext->mask & FIDO_EXT_CRED_BLOB) + size++; + if (ext->mask & FIDO_EXT_HMAC_SECRET) + size++; + if (ext->mask & FIDO_EXT_LARGEBLOB_KEY) + size++; + if (size == 0 || (item = cbor_new_definite_map(size)) == NULL) + return (NULL); + + if (ext->mask & FIDO_EXT_CRED_BLOB) { + if (cbor_add_bool(item, "credBlob", FIDO_OPT_TRUE) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_HMAC_SECRET) { + if (cbor_encode_hmac_secret_param(dev, item, ecdh, pk, + &ext->hmac_salt) < 0) { + cbor_decref(&item); + return (NULL); + } + } + if (ext->mask & FIDO_EXT_LARGEBLOB_KEY) { + if (cbor_encode_largeblob_key_ext(item) < 0) { + cbor_decref(&item); + return (NULL); + } + } + + return (item); +} + +int +cbor_decode_fmt(const cbor_item_t *item, char **fmt) +{ + char *type = NULL; + + if (cbor_string_copy(item, &type) < 0) { + fido_log_debug("%s: cbor_string_copy", __func__); + return (-1); + } + + if (strcmp(type, "packed") && strcmp(type, "fido-u2f") && + strcmp(type, "none") && strcmp(type, "tpm")) { + fido_log_debug("%s: type=%s", __func__, type); + free(type); + return (-1); + } + + *fmt = type; + + return (0); +} + +struct cose_key { + int kty; + int alg; + int crv; +}; + +static int +find_cose_alg(const cbor_item_t *key, const cbor_item_t *val, void *arg) +{ + struct cose_key *cose_key = arg; + + if (cbor_isa_uint(key) == true && + cbor_int_get_width(key) == CBOR_INT_8) { + switch (cbor_get_uint8(key)) { + case 1: + if (cbor_isa_uint(val) == false || + cbor_get_int(val) > INT_MAX || cose_key->kty != 0) { + fido_log_debug("%s: kty", __func__); + return (-1); + } + + cose_key->kty = (int)cbor_get_int(val); + + break; + case 3: + if (cbor_isa_negint(val) == false || + cbor_get_int(val) > INT_MAX || cose_key->alg != 0) { + fido_log_debug("%s: alg", __func__); + return (-1); + } + + cose_key->alg = -(int)cbor_get_int(val) - 1; + + break; + } + } else if (cbor_isa_negint(key) == true && + cbor_int_get_width(key) == CBOR_INT_8) { + if (cbor_get_uint8(key) == 0) { + /* get crv if not rsa, otherwise ignore */ + if (cbor_isa_uint(val) == true && + cbor_get_int(val) <= INT_MAX && + cose_key->crv == 0) + cose_key->crv = (int)cbor_get_int(val); + } + } + + return (0); +} + +static int +get_cose_alg(const cbor_item_t *item, int *cose_alg) +{ + struct cose_key cose_key; + + memset(&cose_key, 0, sizeof(cose_key)); + + *cose_alg = 0; + + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, &cose_key, find_cose_alg) < 0) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + switch (cose_key.alg) { + case COSE_ES256: + if (cose_key.kty != COSE_KTY_EC2 || + cose_key.crv != COSE_P256) { + fido_log_debug("%s: invalid kty/crv", __func__); + return (-1); + } + break; + case COSE_ES384: + if (cose_key.kty != COSE_KTY_EC2 || + cose_key.crv != COSE_P384) { + fido_log_debug("%s: invalid kty/crv", __func__); + return (-1); + } + break; + case COSE_EDDSA: + if (cose_key.kty != COSE_KTY_OKP || + cose_key.crv != COSE_ED25519) { + fido_log_debug("%s: invalid kty/crv", __func__); + return (-1); + } + break; + case COSE_RS256: + if (cose_key.kty != COSE_KTY_RSA) { + fido_log_debug("%s: invalid kty/crv", __func__); + return (-1); + } + break; + default: + fido_log_debug("%s: unknown alg %d", __func__, cose_key.alg); + + return (-1); + } + + *cose_alg = cose_key.alg; + + return (0); +} + +int +cbor_decode_pubkey(const cbor_item_t *item, int *type, void *key) +{ + if (get_cose_alg(item, type) < 0) { + fido_log_debug("%s: get_cose_alg", __func__); + return (-1); + } + + switch (*type) { + case COSE_ES256: + if (es256_pk_decode(item, key) < 0) { + fido_log_debug("%s: es256_pk_decode", __func__); + return (-1); + } + break; + case COSE_ES384: + if (es384_pk_decode(item, key) < 0) { + fido_log_debug("%s: es384_pk_decode", __func__); + return (-1); + } + break; + case COSE_RS256: + if (rs256_pk_decode(item, key) < 0) { + fido_log_debug("%s: rs256_pk_decode", __func__); + return (-1); + } + break; + case COSE_EDDSA: + if (eddsa_pk_decode(item, key) < 0) { + fido_log_debug("%s: eddsa_pk_decode", __func__); + return (-1); + } + break; + default: + fido_log_debug("%s: invalid cose_alg %d", __func__, *type); + return (-1); + } + + return (0); +} + +static int +decode_attcred(const unsigned char **buf, size_t *len, int cose_alg, + fido_attcred_t *attcred) +{ + cbor_item_t *item = NULL; + struct cbor_load_result cbor; + uint16_t id_len; + int ok = -1; + + fido_log_xxd(*buf, *len, "%s", __func__); + + if (fido_buf_read(buf, len, &attcred->aaguid, + sizeof(attcred->aaguid)) < 0) { + fido_log_debug("%s: fido_buf_read aaguid", __func__); + return (-1); + } + + if (fido_buf_read(buf, len, &id_len, sizeof(id_len)) < 0) { + fido_log_debug("%s: fido_buf_read id_len", __func__); + return (-1); + } + + attcred->id.len = (size_t)be16toh(id_len); + if ((attcred->id.ptr = malloc(attcred->id.len)) == NULL) + return (-1); + + fido_log_debug("%s: attcred->id.len=%zu", __func__, attcred->id.len); + + if (fido_buf_read(buf, len, attcred->id.ptr, attcred->id.len) < 0) { + fido_log_debug("%s: fido_buf_read id", __func__); + return (-1); + } + + if ((item = cbor_load(*buf, *len, &cbor)) == NULL) { + fido_log_debug("%s: cbor_load", __func__); + goto fail; + } + + if (cbor_decode_pubkey(item, &attcred->type, &attcred->pubkey) < 0) { + fido_log_debug("%s: cbor_decode_pubkey", __func__); + goto fail; + } + + if (attcred->type != cose_alg) { + fido_log_debug("%s: cose_alg mismatch (%d != %d)", __func__, + attcred->type, cose_alg); + goto fail; + } + + *buf += cbor.read; + *len -= cbor.read; + + ok = 0; +fail: + if (item != NULL) + cbor_decref(&item); + + return (ok); +} + +static int +decode_cred_extension(const cbor_item_t *key, const cbor_item_t *val, void *arg) +{ + fido_cred_ext_t *authdata_ext = arg; + char *type = NULL; + int ok = -1; + + if (cbor_string_copy(key, &type) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (strcmp(type, "hmac-secret") == 0) { + if (cbor_decode_bool(val, NULL) < 0) { + fido_log_debug("%s: cbor_decode_bool", __func__); + goto out; + } + if (cbor_ctrl_value(val) == CBOR_CTRL_TRUE) + authdata_ext->mask |= FIDO_EXT_HMAC_SECRET; + } else if (strcmp(type, "credProtect") == 0) { + if (cbor_isa_uint(val) == false || + cbor_int_get_width(val) != CBOR_INT_8) { + fido_log_debug("%s: cbor type", __func__); + goto out; + } + authdata_ext->mask |= FIDO_EXT_CRED_PROTECT; + authdata_ext->prot = cbor_get_uint8(val); + } else if (strcmp(type, "credBlob") == 0) { + if (cbor_decode_bool(val, NULL) < 0) { + fido_log_debug("%s: cbor_decode_bool", __func__); + goto out; + } + if (cbor_ctrl_value(val) == CBOR_CTRL_TRUE) + authdata_ext->mask |= FIDO_EXT_CRED_BLOB; + } else if (strcmp(type, "minPinLength") == 0) { + if (cbor_isa_uint(val) == false || + cbor_int_get_width(val) != CBOR_INT_8) { + fido_log_debug("%s: cbor type", __func__); + goto out; + } + authdata_ext->mask |= FIDO_EXT_MINPINLEN; + authdata_ext->minpinlen = cbor_get_uint8(val); + } + + ok = 0; +out: + free(type); + + return (ok); +} + +static int +decode_cred_extensions(const unsigned char **buf, size_t *len, + fido_cred_ext_t *authdata_ext) +{ + cbor_item_t *item = NULL; + struct cbor_load_result cbor; + int ok = -1; + + memset(authdata_ext, 0, sizeof(*authdata_ext)); + + fido_log_xxd(*buf, *len, "%s", __func__); + + if ((item = cbor_load(*buf, *len, &cbor)) == NULL) { + fido_log_debug("%s: cbor_load", __func__); + goto fail; + } + + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, authdata_ext, decode_cred_extension) < 0) { + fido_log_debug("%s: cbor type", __func__); + goto fail; + } + + *buf += cbor.read; + *len -= cbor.read; + + ok = 0; +fail: + if (item != NULL) + cbor_decref(&item); + + return (ok); +} + +static int +decode_assert_extension(const cbor_item_t *key, const cbor_item_t *val, + void *arg) +{ + fido_assert_extattr_t *authdata_ext = arg; + char *type = NULL; + int ok = -1; + + if (cbor_string_copy(key, &type) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (strcmp(type, "hmac-secret") == 0) { + if (fido_blob_decode(val, &authdata_ext->hmac_secret_enc) < 0) { + fido_log_debug("%s: fido_blob_decode", __func__); + goto out; + } + authdata_ext->mask |= FIDO_EXT_HMAC_SECRET; + } else if (strcmp(type, "credBlob") == 0) { + if (fido_blob_decode(val, &authdata_ext->blob) < 0) { + fido_log_debug("%s: fido_blob_decode", __func__); + goto out; + } + authdata_ext->mask |= FIDO_EXT_CRED_BLOB; + } + + ok = 0; +out: + free(type); + + return (ok); +} + +static int +decode_assert_extensions(const unsigned char **buf, size_t *len, + fido_assert_extattr_t *authdata_ext) +{ + cbor_item_t *item = NULL; + struct cbor_load_result cbor; + int ok = -1; + + fido_log_xxd(*buf, *len, "%s", __func__); + + if ((item = cbor_load(*buf, *len, &cbor)) == NULL) { + fido_log_debug("%s: cbor_load", __func__); + goto fail; + } + + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, authdata_ext, decode_assert_extension) < 0) { + fido_log_debug("%s: cbor type", __func__); + goto fail; + } + + *buf += cbor.read; + *len -= cbor.read; + + ok = 0; +fail: + if (item != NULL) + cbor_decref(&item); + + return (ok); +} + +int +cbor_decode_cred_authdata(const cbor_item_t *item, int cose_alg, + fido_blob_t *authdata_cbor, fido_authdata_t *authdata, + fido_attcred_t *attcred, fido_cred_ext_t *authdata_ext) +{ + const unsigned char *buf = NULL; + size_t len; + size_t alloc_len; + + if (cbor_isa_bytestring(item) == false || + cbor_bytestring_is_definite(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + if (authdata_cbor->ptr != NULL || + (authdata_cbor->len = cbor_serialize_alloc(item, + &authdata_cbor->ptr, &alloc_len)) == 0) { + fido_log_debug("%s: cbor_serialize_alloc", __func__); + return (-1); + } + + buf = cbor_bytestring_handle(item); + len = cbor_bytestring_length(item); + fido_log_xxd(buf, len, "%s", __func__); + + if (fido_buf_read(&buf, &len, authdata, sizeof(*authdata)) < 0) { + fido_log_debug("%s: fido_buf_read", __func__); + return (-1); + } + + authdata->sigcount = be32toh(authdata->sigcount); + + if (attcred != NULL) { + if ((authdata->flags & CTAP_AUTHDATA_ATT_CRED) == 0 || + decode_attcred(&buf, &len, cose_alg, attcred) < 0) + return (-1); + } + + if (authdata_ext != NULL) { + if ((authdata->flags & CTAP_AUTHDATA_EXT_DATA) != 0 && + decode_cred_extensions(&buf, &len, authdata_ext) < 0) + return (-1); + } + + /* XXX we should probably ensure that len == 0 at this point */ + + return (FIDO_OK); +} + +int +cbor_decode_assert_authdata(const cbor_item_t *item, fido_blob_t *authdata_cbor, + fido_authdata_t *authdata, fido_assert_extattr_t *authdata_ext) +{ + const unsigned char *buf = NULL; + size_t len; + size_t alloc_len; + + if (cbor_isa_bytestring(item) == false || + cbor_bytestring_is_definite(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + if (authdata_cbor->ptr != NULL || + (authdata_cbor->len = cbor_serialize_alloc(item, + &authdata_cbor->ptr, &alloc_len)) == 0) { + fido_log_debug("%s: cbor_serialize_alloc", __func__); + return (-1); + } + + buf = cbor_bytestring_handle(item); + len = cbor_bytestring_length(item); + + fido_log_debug("%s: buf=%p, len=%zu", __func__, (const void *)buf, len); + + if (fido_buf_read(&buf, &len, authdata, sizeof(*authdata)) < 0) { + fido_log_debug("%s: fido_buf_read", __func__); + return (-1); + } + + authdata->sigcount = be32toh(authdata->sigcount); + + if ((authdata->flags & CTAP_AUTHDATA_EXT_DATA) != 0) { + if (decode_assert_extensions(&buf, &len, authdata_ext) < 0) { + fido_log_debug("%s: decode_assert_extensions", + __func__); + return (-1); + } + } + + /* XXX we should probably ensure that len == 0 at this point */ + + return (FIDO_OK); +} + +static int +decode_x5c(const cbor_item_t *item, void *arg) +{ + fido_blob_t *x5c = arg; + + if (x5c->len) + return (0); /* ignore */ + + return (fido_blob_decode(item, x5c)); +} + +static int +decode_attstmt_entry(const cbor_item_t *key, const cbor_item_t *val, void *arg) +{ + fido_attstmt_t *attstmt = arg; + char *name = NULL; + int ok = -1; + + if (cbor_string_copy(key, &name) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (!strcmp(name, "alg")) { + if (cbor_isa_negint(val) == false || + cbor_get_int(val) > UINT16_MAX) { + fido_log_debug("%s: alg", __func__); + goto out; + } + attstmt->alg = -(int)cbor_get_int(val) - 1; + if (attstmt->alg != COSE_ES256 && attstmt->alg != COSE_ES384 && + attstmt->alg != COSE_RS256 && attstmt->alg != COSE_EDDSA && + attstmt->alg != COSE_RS1) { + fido_log_debug("%s: unsupported attstmt->alg=%d", + __func__, attstmt->alg); + goto out; + } + } else if (!strcmp(name, "sig")) { + if (fido_blob_decode(val, &attstmt->sig) < 0) { + fido_log_debug("%s: sig", __func__); + goto out; + } + } else if (!strcmp(name, "x5c")) { + if (cbor_isa_array(val) == false || + cbor_array_is_definite(val) == false || + cbor_array_iter(val, &attstmt->x5c, decode_x5c) < 0) { + fido_log_debug("%s: x5c", __func__); + goto out; + } + } else if (!strcmp(name, "certInfo")) { + if (fido_blob_decode(val, &attstmt->certinfo) < 0) { + fido_log_debug("%s: certinfo", __func__); + goto out; + } + } else if (!strcmp(name, "pubArea")) { + if (fido_blob_decode(val, &attstmt->pubarea) < 0) { + fido_log_debug("%s: pubarea", __func__); + goto out; + } + } + + ok = 0; +out: + free(name); + + return (ok); +} + +int +cbor_decode_attstmt(const cbor_item_t *item, fido_attstmt_t *attstmt) +{ + size_t alloc_len; + + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, attstmt, decode_attstmt_entry) < 0) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + if (attstmt->cbor.ptr != NULL || + (attstmt->cbor.len = cbor_serialize_alloc(item, + &attstmt->cbor.ptr, &alloc_len)) == 0) { + fido_log_debug("%s: cbor_serialize_alloc", __func__); + return (-1); + } + + return (0); +} + +int +cbor_decode_uint64(const cbor_item_t *item, uint64_t *n) +{ + if (cbor_isa_uint(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + *n = cbor_get_int(item); + + return (0); +} + +static int +decode_cred_id_entry(const cbor_item_t *key, const cbor_item_t *val, void *arg) +{ + fido_blob_t *id = arg; + char *name = NULL; + int ok = -1; + + if (cbor_string_copy(key, &name) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (!strcmp(name, "id")) + if (fido_blob_decode(val, id) < 0) { + fido_log_debug("%s: cbor_bytestring_copy", __func__); + goto out; + } + + ok = 0; +out: + free(name); + + return (ok); +} + +int +cbor_decode_cred_id(const cbor_item_t *item, fido_blob_t *id) +{ + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, id, decode_cred_id_entry) < 0) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + return (0); +} + +static int +decode_user_entry(const cbor_item_t *key, const cbor_item_t *val, void *arg) +{ + fido_user_t *user = arg; + char *name = NULL; + int ok = -1; + + if (cbor_string_copy(key, &name) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (!strcmp(name, "icon")) { + if (cbor_string_copy(val, &user->icon) < 0) { + fido_log_debug("%s: icon", __func__); + goto out; + } + } else if (!strcmp(name, "name")) { + if (cbor_string_copy(val, &user->name) < 0) { + fido_log_debug("%s: name", __func__); + goto out; + } + } else if (!strcmp(name, "displayName")) { + if (cbor_string_copy(val, &user->display_name) < 0) { + fido_log_debug("%s: display_name", __func__); + goto out; + } + } else if (!strcmp(name, "id")) { + if (fido_blob_decode(val, &user->id) < 0) { + fido_log_debug("%s: id", __func__); + goto out; + } + } + + ok = 0; +out: + free(name); + + return (ok); +} + +int +cbor_decode_user(const cbor_item_t *item, fido_user_t *user) +{ + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, user, decode_user_entry) < 0) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + return (0); +} + +static int +decode_rp_entity_entry(const cbor_item_t *key, const cbor_item_t *val, + void *arg) +{ + fido_rp_t *rp = arg; + char *name = NULL; + int ok = -1; + + if (cbor_string_copy(key, &name) < 0) { + fido_log_debug("%s: cbor type", __func__); + ok = 0; /* ignore */ + goto out; + } + + if (!strcmp(name, "id")) { + if (cbor_string_copy(val, &rp->id) < 0) { + fido_log_debug("%s: id", __func__); + goto out; + } + } else if (!strcmp(name, "name")) { + if (cbor_string_copy(val, &rp->name) < 0) { + fido_log_debug("%s: name", __func__); + goto out; + } + } + + ok = 0; +out: + free(name); + + return (ok); +} + +int +cbor_decode_rp_entity(const cbor_item_t *item, fido_rp_t *rp) +{ + if (cbor_isa_map(item) == false || + cbor_map_is_definite(item) == false || + cbor_map_iter(item, rp, decode_rp_entity_entry) < 0) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + return (0); +} + +int +cbor_decode_bool(const cbor_item_t *item, bool *v) +{ + if (cbor_isa_float_ctrl(item) == false || + cbor_float_get_width(item) != CBOR_FLOAT_0 || + cbor_is_bool(item) == false) { + fido_log_debug("%s: cbor type", __func__); + return (-1); + } + + if (v != NULL) + *v = cbor_ctrl_value(item) == CBOR_CTRL_TRUE; + + return (0); +} + +cbor_item_t * +cbor_build_uint(const uint64_t value) +{ + if (value <= UINT8_MAX) + return cbor_build_uint8((uint8_t)value); + else if (value <= UINT16_MAX) + return cbor_build_uint16((uint16_t)value); + else if (value <= UINT32_MAX) + return cbor_build_uint32((uint32_t)value); + + return cbor_build_uint64(value); +} + +int +cbor_array_append(cbor_item_t **array, cbor_item_t *item) +{ + cbor_item_t **v, *ret; + size_t n; + + if ((v = cbor_array_handle(*array)) == NULL || + (n = cbor_array_size(*array)) == SIZE_MAX || + (ret = cbor_new_definite_array(n + 1)) == NULL) + return -1; + for (size_t i = 0; i < n; i++) { + if (cbor_array_push(ret, v[i]) == 0) { + cbor_decref(&ret); + return -1; + } + } + if (cbor_array_push(ret, item) == 0) { + cbor_decref(&ret); + return -1; + } + cbor_decref(array); + *array = ret; + + return 0; +} + +int +cbor_array_drop(cbor_item_t **array, size_t idx) +{ + cbor_item_t **v, *ret; + size_t n; + + if ((v = cbor_array_handle(*array)) == NULL || + (n = cbor_array_size(*array)) == 0 || idx >= n || + (ret = cbor_new_definite_array(n - 1)) == NULL) + return -1; + for (size_t i = 0; i < n; i++) { + if (i != idx && cbor_array_push(ret, v[i]) == 0) { + cbor_decref(&ret); + return -1; + } + } + cbor_decref(array); + *array = ret; + + return 0; +} |