--- /dev/null
+/* 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 <utility>
+
+#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"
+
+
+namespace bssl {
+
+static int init_key_schedule(SSL_HANDSHAKE *hs, uint16_t version,
+ const SSL_CIPHER *cipher) {
+ if (!hs->transcript.InitHash(version, cipher)) {
+ return 0;
+ }
+
+ hs->hash_len = hs->transcript.DigestLen();
+
+ // 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, const uint8_t *psk,
+ size_t psk_len) {
+ if (!init_key_schedule(hs, ssl_protocol_version(hs->ssl), hs->new_cipher)) {
+ return 0;
+ }
+
+ hs->transcript.FreeBuffer();
+ return HKDF_extract(hs->secret, &hs->hash_len, hs->transcript.Digest(), psk,
+ psk_len, hs->secret, hs->hash_len);
+}
+
+int tls13_init_early_key_schedule(SSL_HANDSHAKE *hs, const uint8_t *psk,
+ size_t psk_len) {
+ SSL *const ssl = hs->ssl;
+ return init_key_schedule(hs, ssl_session_protocol_version(ssl->session),
+ ssl->session->cipher) &&
+ HKDF_extract(hs->secret, &hs->hash_len, hs->transcript.Digest(), psk,
+ psk_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 char *label, size_t label_len,
+ const uint8_t *hash, size_t hash_len, size_t len) {
+ static const char kTLS13LabelVersion[] = "tls13 ";
+
+ ScopedCBB cbb;
+ CBB child;
+ uint8_t *hkdf_label;
+ size_t hkdf_label_len;
+ if (!CBB_init(cbb.get(), 2 + 1 + strlen(kTLS13LabelVersion) + label_len + 1 +
+ hash_len) ||
+ !CBB_add_u16(cbb.get(), len) ||
+ !CBB_add_u8_length_prefixed(cbb.get(), &child) ||
+ !CBB_add_bytes(&child, (const uint8_t *)kTLS13LabelVersion,
+ strlen(kTLS13LabelVersion)) ||
+ !CBB_add_bytes(&child, (const uint8_t *)label, label_len) ||
+ !CBB_add_u8_length_prefixed(cbb.get(), &child) ||
+ !CBB_add_bytes(&child, hash, hash_len) ||
+ !CBB_finish(cbb.get(), &hkdf_label, &hkdf_label_len)) {
+ return 0;
+ }
+
+ int ret = HKDF_expand(out, len, digest, secret, secret_len, hkdf_label,
+ hkdf_label_len);
+ OPENSSL_free(hkdf_label);
+ return ret;
+}
+
+static const char kTLS13LabelDerived[] = "derived";
+
+int tls13_advance_key_schedule(SSL_HANDSHAKE *hs, const uint8_t *in,
+ size_t len) {
+ uint8_t derive_context[EVP_MAX_MD_SIZE];
+ unsigned derive_context_len;
+ if (!EVP_Digest(nullptr, 0, derive_context, &derive_context_len,
+ hs->transcript.Digest(), nullptr)) {
+ return 0;
+ }
+
+ if (!hkdf_expand_label(hs->secret, hs->transcript.Digest(), hs->secret,
+ hs->hash_len, kTLS13LabelDerived,
+ strlen(kTLS13LabelDerived), derive_context,
+ derive_context_len, hs->hash_len)) {
+ return 0;
+ }
+
+ return HKDF_extract(hs->secret, &hs->hash_len, hs->transcript.Digest(), in,
+ len, hs->secret, hs->hash_len);
+}
+
+// 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 char *label, size_t label_len) {
+ uint8_t context_hash[EVP_MAX_MD_SIZE];
+ size_t context_hash_len;
+ if (!hs->transcript.GetHash(context_hash, &context_hash_len)) {
+ return 0;
+ }
+
+ return hkdf_expand_label(out, hs->transcript.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) {
+ const SSL_SESSION *session = SSL_get_session(ssl);
+ uint16_t version = ssl_session_protocol_version(session);
+
+ 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, SSL_is_dtls(ssl))) {
+ return 0;
+ }
+
+ const EVP_MD *digest = ssl_session_get_digest(session);
+
+ // 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, "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, "iv",
+ 2, NULL, 0, iv_len)) {
+ return 0;
+ }
+
+ UniquePtr<SSLAEADContext> traffic_aead =
+ SSLAEADContext::Create(direction, session->ssl_version, SSL_is_dtls(ssl),
+ session->cipher, MakeConstSpan(key, key_len),
+ Span<const uint8_t>(), MakeConstSpan(iv, iv_len));
+ if (!traffic_aead) {
+ return 0;
+ }
+
+ if (direction == evp_aead_open) {
+ if (!ssl->method->set_read_state(ssl, std::move(traffic_aead))) {
+ return 0;
+ }
+ } else {
+ if (!ssl->method->set_write_state(ssl, std::move(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[] = "exp master";
+static const char kTLS13LabelEarlyExporter[] = "e exp master";
+
+static const char kTLS13LabelClientEarlyTraffic[] = "c e traffic";
+static const char kTLS13LabelClientHandshakeTraffic[] = "c hs traffic";
+static const char kTLS13LabelServerHandshakeTraffic[] = "s hs traffic";
+static const char kTLS13LabelClientApplicationTraffic[] = "c ap traffic";
+static const char kTLS13LabelServerApplicationTraffic[] = "s ap traffic";
+
+int tls13_derive_early_secrets(SSL_HANDSHAKE *hs) {
+ SSL *const ssl = hs->ssl;
+ if (!derive_secret(hs, hs->early_traffic_secret, hs->hash_len,
+ 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,
+ kTLS13LabelEarlyExporter,
+ strlen(kTLS13LabelEarlyExporter))) {
+ return 0;
+ }
+ ssl->s3->early_exporter_secret_len = hs->hash_len;
+ return 1;
+}
+
+int tls13_derive_handshake_secrets(SSL_HANDSHAKE *hs) {
+ SSL *const ssl = hs->ssl;
+ return derive_secret(hs, hs->client_handshake_secret, hs->hash_len,
+ 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,
+ 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,
+ 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,
+ 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,
+ kTLS13LabelExporter, strlen(kTLS13LabelExporter)) &&
+ ssl_log_secret(ssl, "EXPORTER_SECRET", ssl->s3->exporter_secret,
+ hs->hash_len);
+}
+
+static const char kTLS13LabelApplicationTraffic[] = "traffic upd";
+
+int tls13_rotate_traffic_key(SSL *ssl, enum evp_aead_direction_t direction) {
+ 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;
+ }
+
+ const EVP_MD *digest = ssl_session_get_digest(SSL_get_session(ssl));
+ if (!hkdf_expand_label(
+ secret, digest, secret, secret_len, kTLS13LabelApplicationTraffic,
+ strlen(kTLS13LabelApplicationTraffic), NULL, 0, secret_len)) {
+ return 0;
+ }
+
+ return tls13_set_traffic_key(ssl, direction, secret, secret_len);
+}
+
+static const char kTLS13LabelResumption[] = "res master";
+
+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,
+ 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, uint16_t version,
+ 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, 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 (!hs->transcript.GetHash(context_hash, &context_hash_len) ||
+ !tls13_verify_data(hs->transcript.Digest(), hs->ssl->version, out,
+ out_len, traffic_secret, hs->hash_len, context_hash,
+ context_hash_len)) {
+ return 0;
+ }
+ return 1;
+}
+
+static const char kTLS13LabelResumptionPSK[] = "resumption";
+
+bool tls13_derive_session_psk(SSL_SESSION *session, Span<const uint8_t> nonce) {
+ const EVP_MD *digest = ssl_session_get_digest(session);
+ return hkdf_expand_label(session->master_key, digest, session->master_key,
+ session->master_key_length, kTLS13LabelResumptionPSK,
+ strlen(kTLS13LabelResumptionPSK), nonce.data(),
+ nonce.size(), session->master_key_length);
+}
+
+static const char kTLS13LabelExportKeying[] = "exporter";
+
+int tls13_export_keying_material(SSL *ssl, Span<uint8_t> out,
+ Span<const uint8_t> secret,
+ Span<const char> label,
+ Span<const uint8_t> context) {
+ if (secret.empty()) {
+ assert(0);
+ OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+
+ const EVP_MD *digest = ssl_session_get_digest(SSL_get_session(ssl));
+
+ uint8_t hash[EVP_MAX_MD_SIZE];
+ uint8_t export_context[EVP_MAX_MD_SIZE];
+ uint8_t derived_secret[EVP_MAX_MD_SIZE];
+ unsigned hash_len;
+ unsigned export_context_len;
+ unsigned derived_secret_len = EVP_MD_size(digest);
+ return EVP_Digest(context.data(), context.size(), hash, &hash_len, digest,
+ nullptr) &&
+ EVP_Digest(nullptr, 0, export_context, &export_context_len, digest,
+ nullptr) &&
+ hkdf_expand_label(derived_secret, digest, secret.data(), secret.size(),
+ label.data(), label.size(), export_context,
+ export_context_len, derived_secret_len) &&
+ hkdf_expand_label(out.data(), digest, derived_secret,
+ derived_secret_len, kTLS13LabelExportKeying,
+ strlen(kTLS13LabelExportKeying), hash, hash_len,
+ out.size());
+}
+
+static const char kTLS13LabelPSKBinder[] = "res binder";
+
+static int tls13_psk_binder(uint8_t *out, uint16_t version,
+ 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,
+ kTLS13LabelPSKBinder, strlen(kTLS13LabelPSKBinder),
+ binder_context, binder_context_len, hash_len) ||
+ !tls13_verify_data(digest, version, 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);
+ size_t hash_len = EVP_MD_size(digest);
+
+ if (len < hash_len + 3) {
+ OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+
+ ScopedEVP_MD_CTX ctx;
+ uint8_t context[EVP_MAX_MD_SIZE];
+ unsigned context_len;
+
+ if (!EVP_DigestInit_ex(ctx.get(), digest, NULL) ||
+ !EVP_DigestUpdate(ctx.get(), hs->transcript.buffer().data(),
+ hs->transcript.buffer().size()) ||
+ !EVP_DigestUpdate(ctx.get(), msg, len - hash_len - 3) ||
+ !EVP_DigestFinal_ex(ctx.get(), context, &context_len)) {
+ return 0;
+ }
+
+ uint8_t verify_data[EVP_MAX_MD_SIZE] = {0};
+ if (!tls13_psk_binder(verify_data, ssl->session->ssl_version, 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,
+ const SSLMessage &msg, CBS *binders) {
+ size_t hash_len = hs->transcript.DigestLen();
+
+ // The message must be large enough to exclude the binders.
+ if (CBS_len(&msg.raw) < CBS_len(binders) + 2) {
+ OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+
+ // Hash a ClientHello prefix up to the binders. This includes the header. 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(&msg.raw), CBS_len(&msg.raw) - CBS_len(binders) - 2,
+ context, &context_len, hs->transcript.Digest(), NULL)) {
+ return 0;
+ }
+
+ uint8_t verify_data[EVP_MAX_MD_SIZE] = {0};
+ CBS binder;
+ if (!tls13_psk_binder(verify_data, hs->ssl->version, hs->transcript.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;
+}
+
+} // namespace bssl
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