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- /* 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 "../crypto/internal.h"
- #include "internal.h"
-
-
- static int init_key_schedule(SSL_HANDSHAKE *hs, uint16_t version,
- int algorithm_prf) {
- if (!SSL_TRANSCRIPT_init_hash(&hs->transcript, version, algorithm_prf)) {
- return 0;
- }
-
- hs->hash_len = SSL_TRANSCRIPT_digest_len(&hs->transcript);
-
- /* Initialize the secret to the zero key. */
- OPENSSL_memset(hs->secret, 0, hs->hash_len);
-
- return 1;
- }
-
- int tls13_init_key_schedule(SSL_HANDSHAKE *hs) {
- if (!init_key_schedule(hs, ssl3_protocol_version(hs->ssl),
- hs->new_cipher->algorithm_prf)) {
- return 0;
- }
-
- SSL_TRANSCRIPT_free_buffer(&hs->transcript);
- return 1;
- }
-
- int tls13_init_early_key_schedule(SSL_HANDSHAKE *hs) {
- SSL *const ssl = hs->ssl;
- uint16_t session_version;
- if (!ssl->method->version_from_wire(&session_version,
- ssl->session->ssl_version) ||
- !init_key_schedule(hs, session_version,
- ssl->session->cipher->algorithm_prf)) {
- return 0;
- }
-
- return 1;
- }
-
- int tls13_advance_key_schedule(SSL_HANDSHAKE *hs, const uint8_t *in,
- size_t len) {
- return HKDF_extract(hs->secret, &hs->hash_len,
- SSL_TRANSCRIPT_md(&hs->transcript), 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;
- }
-
- /* 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) {
- uint8_t context_hash[EVP_MAX_MD_SIZE];
- size_t context_hash_len;
- if (!SSL_TRANSCRIPT_get_hash(&hs->transcript, context_hash,
- &context_hash_len)) {
- return 0;
- }
-
- return hkdf_expand_label(out, SSL_TRANSCRIPT_md(&hs->transcript), 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) {
- const SSL_SESSION *session = SSL_get_session(ssl);
- uint16_t version;
- if (!ssl->method->version_from_wire(&version, session->ssl_version)) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
-
- if (traffic_secret_len > 0xff) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
- return 0;
- }
-
- /* Look up cipher suite properties. */
- const EVP_AEAD *aead;
- size_t discard;
- if (!ssl_cipher_get_evp_aead(&aead, &discard, &discard, session->cipher,
- version)) {
- return 0;
- }
-
- const EVP_MD *digest = ssl_get_handshake_digest(
- session->cipher->algorithm_prf, version);
-
- /* 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, version, session->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) {
- OPENSSL_memmove(ssl->s3->read_traffic_secret, traffic_secret,
- traffic_secret_len);
- ssl->s3->read_traffic_secret_len = traffic_secret_len;
- } else {
- OPENSSL_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 kTLS13LabelExporter[] = "exporter master secret";
- static const char kTLS13LabelEarlyExporter[] = "early exporter master secret";
-
- static const char kTLS13LabelClientEarlyTraffic[] =
- "client early traffic secret";
- 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_early_secrets(SSL_HANDSHAKE *hs) {
- SSL *const ssl = hs->ssl;
- return derive_secret(hs, hs->early_traffic_secret, hs->hash_len,
- (const uint8_t *)kTLS13LabelClientEarlyTraffic,
- strlen(kTLS13LabelClientEarlyTraffic)) &&
- ssl_log_secret(ssl, "CLIENT_EARLY_TRAFFIC_SECRET",
- hs->early_traffic_secret, hs->hash_len) &&
- derive_secret(hs, ssl->s3->early_exporter_secret, hs->hash_len,
- (const uint8_t *)kTLS13LabelEarlyExporter,
- strlen(kTLS13LabelEarlyExporter));
- }
-
- 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);
- }
-
- 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_session(ssl)->cipher->algorithm_prf, ssl3_protocol_version(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) {
- if (hs->hash_len > SSL_MAX_MASTER_KEY_LENGTH) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
-
- hs->new_session->master_key_length = hs->hash_len;
- return derive_secret(
- hs, hs->new_session->master_key, hs->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) {
- const uint8_t *traffic_secret;
- if (is_server) {
- traffic_secret = hs->server_handshake_secret;
- } else {
- traffic_secret = hs->client_handshake_secret;
- }
-
- uint8_t context_hash[EVP_MAX_MD_SIZE];
- size_t context_hash_len;
- if (!SSL_TRANSCRIPT_get_hash(&hs->transcript, context_hash,
- &context_hash_len) ||
- !tls13_verify_data(SSL_TRANSCRIPT_md(&hs->transcript), 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_session(ssl)->cipher->algorithm_prf, ssl3_protocol_version(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(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_HANDSHAKE *hs, uint8_t *msg, size_t len) {
- SSL *const ssl = hs->ssl;
- const EVP_MD *digest = SSL_SESSION_get_digest(ssl->session, ssl);
- if (digest == NULL) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
- 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, hs->transcript.buffer->data,
- hs->transcript.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(verify_data, digest, ssl->session->master_key,
- ssl->session->master_key_length, context, context_len,
- hash_len)) {
- return 0;
- }
-
- OPENSSL_memcpy(msg + len - hash_len, verify_data, hash_len);
- return 1;
- }
-
- int tls13_verify_psk_binder(SSL_HANDSHAKE *hs, SSL_SESSION *session,
- CBS *binders) {
- size_t hash_len = SSL_TRANSCRIPT_digest_len(&hs->transcript);
-
- /* Get the full ClientHello, including message header. It must be large enough
- * to exclude the binders. */
- CBS message;
- hs->ssl->method->get_current_message(hs->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, SSL_TRANSCRIPT_md(&hs->transcript),
- NULL)) {
- return 0;
- }
-
- uint8_t verify_data[EVP_MAX_MD_SIZE] = {0};
- CBS binder;
- if (!tls13_psk_binder(verify_data, SSL_TRANSCRIPT_md(&hs->transcript),
- 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;
- }
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