| /* Copyright (c) 2016, Google Inc. |
| * |
| * Permission to use, copy, modify, and/or distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ |
| |
| #include <openssl/ssl.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include <openssl/aead.h> |
| #include <openssl/bytestring.h> |
| #include <openssl/digest.h> |
| #include <openssl/hkdf.h> |
| #include <openssl/hmac.h> |
| #include <openssl/mem.h> |
| |
| #include "internal.h" |
| |
| |
| int tls13_init_key_schedule(SSL_HANDSHAKE *hs) { |
| SSL *const ssl = hs->ssl; |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| |
| hs->hash_len = EVP_MD_size(digest); |
| |
| /* Initialize the secret to the zero key. */ |
| memset(hs->secret, 0, hs->hash_len); |
| |
| /* Initialize the rolling hashes and release the handshake buffer. */ |
| if (!ssl3_init_handshake_hash(ssl)) { |
| return 0; |
| } |
| ssl3_free_handshake_buffer(ssl); |
| return 1; |
| } |
| |
| int tls13_advance_key_schedule(SSL_HANDSHAKE *hs, const uint8_t *in, |
| size_t len) { |
| const EVP_MD *digest = |
| ssl_get_handshake_digest(ssl_get_algorithm_prf(hs->ssl)); |
| |
| return HKDF_extract(hs->secret, &hs->hash_len, digest, in, len, hs->secret, |
| hs->hash_len); |
| } |
| |
| static int hkdf_expand_label(uint8_t *out, const EVP_MD *digest, |
| const uint8_t *secret, size_t secret_len, |
| const uint8_t *label, size_t label_len, |
| const uint8_t *hash, size_t hash_len, size_t len) { |
| static const char kTLS13LabelVersion[] = "TLS 1.3, "; |
| |
| CBB cbb, child; |
| uint8_t *hkdf_label; |
| size_t hkdf_label_len; |
| if (!CBB_init(&cbb, 2 + 1 + strlen(kTLS13LabelVersion) + label_len + 1 + |
| hash_len) || |
| !CBB_add_u16(&cbb, len) || |
| !CBB_add_u8_length_prefixed(&cbb, &child) || |
| !CBB_add_bytes(&child, (const uint8_t *)kTLS13LabelVersion, |
| strlen(kTLS13LabelVersion)) || |
| !CBB_add_bytes(&child, label, label_len) || |
| !CBB_add_u8_length_prefixed(&cbb, &child) || |
| !CBB_add_bytes(&child, hash, hash_len) || |
| !CBB_finish(&cbb, &hkdf_label, &hkdf_label_len)) { |
| CBB_cleanup(&cbb); |
| return 0; |
| } |
| |
| int ret = HKDF_expand(out, len, digest, secret, secret_len, hkdf_label, |
| hkdf_label_len); |
| OPENSSL_free(hkdf_label); |
| return ret; |
| } |
| |
| int tls13_get_context_hash(SSL *ssl, uint8_t *out, size_t *out_len) { |
| EVP_MD_CTX ctx; |
| EVP_MD_CTX_init(&ctx); |
| unsigned handshake_len = 0; |
| int ok = EVP_MD_CTX_copy_ex(&ctx, &ssl->s3->handshake_hash) && |
| EVP_DigestFinal_ex(&ctx, out, &handshake_len); |
| EVP_MD_CTX_cleanup(&ctx); |
| if (ok) { |
| *out_len = handshake_len; |
| } |
| return ok; |
| } |
| |
| /* derive_secret derives a secret of length |len| and writes the result in |out| |
| * with the given label and the current base secret and most recently-saved |
| * handshake context. It returns one on success and zero on error. */ |
| static int derive_secret(SSL_HANDSHAKE *hs, uint8_t *out, size_t len, |
| const uint8_t *label, size_t label_len) { |
| SSL *const ssl = hs->ssl; |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| |
| uint8_t context_hash[EVP_MAX_MD_SIZE]; |
| size_t context_hash_len; |
| if (!tls13_get_context_hash(ssl, context_hash, &context_hash_len)) { |
| return 0; |
| } |
| |
| return hkdf_expand_label(out, digest, hs->secret, hs->hash_len, label, |
| label_len, context_hash, context_hash_len, len); |
| } |
| |
| int tls13_set_traffic_key(SSL *ssl, enum evp_aead_direction_t direction, |
| const uint8_t *traffic_secret, |
| size_t traffic_secret_len) { |
| if (traffic_secret_len > 0xff) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); |
| return 0; |
| } |
| |
| /* Look up cipher suite properties. */ |
| const EVP_AEAD *aead; |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| size_t discard; |
| if (!ssl_cipher_get_evp_aead(&aead, &discard, &discard, |
| SSL_get_session(ssl)->cipher, |
| ssl3_protocol_version(ssl))) { |
| return 0; |
| } |
| |
| /* Derive the key. */ |
| size_t key_len = EVP_AEAD_key_length(aead); |
| uint8_t key[EVP_AEAD_MAX_KEY_LENGTH]; |
| if (!hkdf_expand_label(key, digest, traffic_secret, traffic_secret_len, |
| (const uint8_t *)"key", 3, NULL, 0, key_len)) { |
| return 0; |
| } |
| |
| /* Derive the IV. */ |
| size_t iv_len = EVP_AEAD_nonce_length(aead); |
| uint8_t iv[EVP_AEAD_MAX_NONCE_LENGTH]; |
| if (!hkdf_expand_label(iv, digest, traffic_secret, traffic_secret_len, |
| (const uint8_t *)"iv", 2, NULL, 0, iv_len)) { |
| return 0; |
| } |
| |
| SSL_AEAD_CTX *traffic_aead = SSL_AEAD_CTX_new( |
| direction, ssl3_protocol_version(ssl), SSL_get_session(ssl)->cipher, key, |
| key_len, NULL, 0, iv, iv_len); |
| if (traffic_aead == NULL) { |
| return 0; |
| } |
| |
| if (direction == evp_aead_open) { |
| if (!ssl->method->set_read_state(ssl, traffic_aead)) { |
| return 0; |
| } |
| } else { |
| if (!ssl->method->set_write_state(ssl, traffic_aead)) { |
| return 0; |
| } |
| } |
| |
| /* Save the traffic secret. */ |
| if (direction == evp_aead_open) { |
| memmove(ssl->s3->read_traffic_secret, traffic_secret, traffic_secret_len); |
| ssl->s3->read_traffic_secret_len = traffic_secret_len; |
| } else { |
| memmove(ssl->s3->write_traffic_secret, traffic_secret, traffic_secret_len); |
| ssl->s3->write_traffic_secret_len = traffic_secret_len; |
| } |
| |
| return 1; |
| } |
| |
| static const char kTLS13LabelClientHandshakeTraffic[] = |
| "client handshake traffic secret"; |
| static const char kTLS13LabelServerHandshakeTraffic[] = |
| "server handshake traffic secret"; |
| static const char kTLS13LabelClientApplicationTraffic[] = |
| "client application traffic secret"; |
| static const char kTLS13LabelServerApplicationTraffic[] = |
| "server application traffic secret"; |
| |
| int tls13_derive_handshake_secrets(SSL_HANDSHAKE *hs) { |
| SSL *const ssl = hs->ssl; |
| return derive_secret(hs, hs->client_handshake_secret, hs->hash_len, |
| (const uint8_t *)kTLS13LabelClientHandshakeTraffic, |
| strlen(kTLS13LabelClientHandshakeTraffic)) && |
| ssl_log_secret(ssl, "CLIENT_HANDSHAKE_TRAFFIC_SECRET", |
| hs->client_handshake_secret, hs->hash_len) && |
| derive_secret(hs, hs->server_handshake_secret, hs->hash_len, |
| (const uint8_t *)kTLS13LabelServerHandshakeTraffic, |
| strlen(kTLS13LabelServerHandshakeTraffic)) && |
| ssl_log_secret(ssl, "SERVER_HANDSHAKE_TRAFFIC_SECRET", |
| hs->server_handshake_secret, hs->hash_len); |
| } |
| |
| static const char kTLS13LabelExporter[] = "exporter master secret"; |
| |
| int tls13_derive_application_secrets(SSL_HANDSHAKE *hs) { |
| SSL *const ssl = hs->ssl; |
| ssl->s3->exporter_secret_len = hs->hash_len; |
| return derive_secret(hs, hs->client_traffic_secret_0, hs->hash_len, |
| (const uint8_t *)kTLS13LabelClientApplicationTraffic, |
| strlen(kTLS13LabelClientApplicationTraffic)) && |
| ssl_log_secret(ssl, "CLIENT_TRAFFIC_SECRET_0", |
| hs->client_traffic_secret_0, hs->hash_len) && |
| derive_secret(hs, hs->server_traffic_secret_0, hs->hash_len, |
| (const uint8_t *)kTLS13LabelServerApplicationTraffic, |
| strlen(kTLS13LabelServerApplicationTraffic)) && |
| ssl_log_secret(ssl, "SERVER_TRAFFIC_SECRET_0", |
| hs->server_traffic_secret_0, hs->hash_len) && |
| derive_secret(hs, ssl->s3->exporter_secret, hs->hash_len, |
| (const uint8_t *)kTLS13LabelExporter, |
| strlen(kTLS13LabelExporter)); |
| } |
| |
| static const char kTLS13LabelApplicationTraffic[] = |
| "application traffic secret"; |
| |
| int tls13_rotate_traffic_key(SSL *ssl, enum evp_aead_direction_t direction) { |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| |
| uint8_t *secret; |
| size_t secret_len; |
| if (direction == evp_aead_open) { |
| secret = ssl->s3->read_traffic_secret; |
| secret_len = ssl->s3->read_traffic_secret_len; |
| } else { |
| secret = ssl->s3->write_traffic_secret; |
| secret_len = ssl->s3->write_traffic_secret_len; |
| } |
| |
| if (!hkdf_expand_label(secret, digest, secret, secret_len, |
| (const uint8_t *)kTLS13LabelApplicationTraffic, |
| strlen(kTLS13LabelApplicationTraffic), NULL, 0, |
| secret_len)) { |
| return 0; |
| } |
| |
| return tls13_set_traffic_key(ssl, direction, secret, secret_len); |
| } |
| |
| static const char kTLS13LabelResumption[] = "resumption master secret"; |
| |
| int tls13_derive_resumption_secret(SSL_HANDSHAKE *hs) { |
| SSL *const ssl = hs->ssl; |
| if (ssl->s3->hs->hash_len > SSL_MAX_MASTER_KEY_LENGTH) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| ssl->s3->new_session->master_key_length = hs->hash_len; |
| return derive_secret(hs, ssl->s3->new_session->master_key, |
| ssl->s3->new_session->master_key_length, |
| (const uint8_t *)kTLS13LabelResumption, |
| strlen(kTLS13LabelResumption)); |
| } |
| |
| static const char kTLS13LabelFinished[] = "finished"; |
| |
| /* tls13_verify_data sets |out| to be the HMAC of |context| using a derived |
| * Finished key for both Finished messages and the PSK binder. */ |
| static int tls13_verify_data(const EVP_MD *digest, uint8_t *out, |
| size_t *out_len, const uint8_t *secret, |
| size_t hash_len, uint8_t *context, |
| size_t context_len) { |
| uint8_t key[EVP_MAX_MD_SIZE]; |
| unsigned len; |
| if (!hkdf_expand_label(key, digest, secret, hash_len, |
| (const uint8_t *)kTLS13LabelFinished, |
| strlen(kTLS13LabelFinished), NULL, 0, hash_len) || |
| HMAC(digest, key, hash_len, context, context_len, out, &len) == NULL) { |
| return 0; |
| } |
| *out_len = len; |
| return 1; |
| } |
| |
| int tls13_finished_mac(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len, |
| int is_server) { |
| SSL *const ssl = hs->ssl; |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| |
| const uint8_t *traffic_secret; |
| if (is_server == ssl->server) { |
| traffic_secret = ssl->s3->write_traffic_secret; |
| } else { |
| traffic_secret = ssl->s3->read_traffic_secret; |
| } |
| |
| uint8_t context_hash[EVP_MAX_MD_SIZE]; |
| size_t context_hash_len; |
| if (!tls13_get_context_hash(ssl, context_hash, &context_hash_len) || |
| !tls13_verify_data(digest, out, out_len, traffic_secret, hs->hash_len, |
| context_hash, context_hash_len)) { |
| return 0; |
| } |
| return 1; |
| } |
| |
| int tls13_export_keying_material(SSL *ssl, uint8_t *out, size_t out_len, |
| const char *label, size_t label_len, |
| const uint8_t *context, size_t context_len, |
| int use_context) { |
| const EVP_MD *digest = ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)); |
| |
| const uint8_t *hash = NULL; |
| size_t hash_len = 0; |
| if (use_context) { |
| hash = context; |
| hash_len = context_len; |
| } |
| return hkdf_expand_label(out, digest, ssl->s3->exporter_secret, |
| ssl->s3->exporter_secret_len, (const uint8_t *)label, |
| label_len, hash, hash_len, out_len); |
| } |
| |
| static const char kTLS13LabelPSKBinder[] = "resumption psk binder key"; |
| |
| static int tls13_psk_binder(SSL *ssl, uint8_t *out, const EVP_MD *digest, |
| uint8_t *psk, size_t psk_len, uint8_t *context, |
| size_t context_len, size_t hash_len) { |
| uint8_t binder_context[EVP_MAX_MD_SIZE]; |
| unsigned binder_context_len; |
| if (!EVP_Digest(NULL, 0, binder_context, &binder_context_len, digest, NULL)) { |
| return 0; |
| } |
| |
| uint8_t early_secret[EVP_MAX_MD_SIZE] = {0}; |
| size_t early_secret_len; |
| if (!HKDF_extract(early_secret, &early_secret_len, digest, psk, hash_len, |
| NULL, 0)) { |
| return 0; |
| } |
| |
| uint8_t binder_key[EVP_MAX_MD_SIZE] = {0}; |
| size_t len; |
| if (!hkdf_expand_label(binder_key, digest, early_secret, hash_len, |
| (const uint8_t *)kTLS13LabelPSKBinder, |
| strlen(kTLS13LabelPSKBinder), binder_context, |
| binder_context_len, hash_len) || |
| !tls13_verify_data(digest, out, &len, binder_key, hash_len, context, |
| context_len)) { |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| int tls13_write_psk_binder(SSL *ssl, uint8_t *msg, size_t len) { |
| const EVP_MD *digest = |
| ssl_get_handshake_digest(ssl->session->cipher->algorithm_prf); |
| size_t hash_len = EVP_MD_size(digest); |
| |
| if (len < hash_len + 3) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| EVP_MD_CTX ctx; |
| EVP_MD_CTX_init(&ctx); |
| uint8_t context[EVP_MAX_MD_SIZE]; |
| unsigned context_len; |
| if (!EVP_DigestInit_ex(&ctx, digest, NULL) || |
| !EVP_DigestUpdate(&ctx, ssl->s3->handshake_buffer->data, |
| ssl->s3->handshake_buffer->length) || |
| !EVP_DigestUpdate(&ctx, msg, len - hash_len - 3) || |
| !EVP_DigestFinal_ex(&ctx, context, &context_len)) { |
| EVP_MD_CTX_cleanup(&ctx); |
| return 0; |
| } |
| |
| EVP_MD_CTX_cleanup(&ctx); |
| |
| uint8_t verify_data[EVP_MAX_MD_SIZE] = {0}; |
| if (!tls13_psk_binder(ssl, verify_data, digest, ssl->session->master_key, |
| ssl->session->master_key_length, context, |
| context_len, hash_len)) { |
| return 0; |
| } |
| |
| memcpy(msg + len - hash_len, verify_data, hash_len); |
| return 1; |
| } |
| |
| int tls13_verify_psk_binder(SSL *ssl, SSL_SESSION *session, |
| CBS *binders) { |
| const EVP_MD *digest = |
| ssl_get_handshake_digest(session->cipher->algorithm_prf); |
| size_t hash_len = EVP_MD_size(digest); |
| |
| /* Get the full ClientHello, including message header. It must be large enough |
| * to exclude the binders. */ |
| CBS message; |
| ssl->method->get_current_message(ssl, &message); |
| if (CBS_len(&message) < CBS_len(binders) + 2) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| /* Hash a ClientHello prefix up to the binders. For now, this assumes we only |
| * ever verify PSK binders on initial ClientHellos. */ |
| uint8_t context[EVP_MAX_MD_SIZE]; |
| unsigned context_len; |
| if (!EVP_Digest(CBS_data(&message), CBS_len(&message) - CBS_len(binders) - 2, |
| context, &context_len, digest, NULL)) { |
| return 0; |
| } |
| |
| uint8_t verify_data[EVP_MAX_MD_SIZE] = {0}; |
| CBS binder; |
| if (!tls13_psk_binder(ssl, verify_data, digest, session->master_key, |
| session->master_key_length, context, context_len, |
| hash_len) || |
| /* We only consider the first PSK, so compare against the first binder. */ |
| !CBS_get_u8_length_prefixed(binders, &binder)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| int binder_ok = CBS_len(&binder) == hash_len && |
| CRYPTO_memcmp(CBS_data(&binder), verify_data, hash_len) == 0; |
| #if defined(BORINGSSL_UNSAFE_FUZZER_MODE) |
| binder_ok = 1; |
| #endif |
| if (!binder_ok) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED); |
| return 0; |
| } |
| |
| return 1; |
| } |