+
+#ifndef OPENSSL_NO_CT
+
+/*
+ * Moves SCTs from the |src| stack to the |dst| stack.
+ * The source of each SCT will be set to |origin|.
+ * If |dst| points to a NULL pointer, a new stack will be created and owned by
+ * the caller.
+ * Returns the number of SCTs moved, or a negative integer if an error occurs.
+ */
+static int ct_move_scts(STACK_OF(SCT) **dst, STACK_OF(SCT) *src,
+ sct_source_t origin)
+{
+ int scts_moved = 0;
+ SCT *sct = NULL;
+
+ if (*dst == NULL) {
+ *dst = sk_SCT_new_null();
+ if (*dst == NULL) {
+ SSLerr(SSL_F_CT_MOVE_SCTS, ERR_R_MALLOC_FAILURE);
+ goto err;
+ }
+ }
+
+ while ((sct = sk_SCT_pop(src)) != NULL) {
+ if (SCT_set_source(sct, origin) != 1)
+ goto err;
+
+ if (sk_SCT_push(*dst, sct) <= 0)
+ goto err;
+ scts_moved += 1;
+ }
+
+ return scts_moved;
+ err:
+ if (sct != NULL)
+ sk_SCT_push(src, sct); /* Put the SCT back */
+ return -1;
+}
+
+/*
+ * Look for data collected during ServerHello and parse if found.
+ * Returns the number of SCTs extracted.
+ */
+static int ct_extract_tls_extension_scts(SSL *s)
+{
+ int scts_extracted = 0;
+
+ if (s->tlsext_scts != NULL) {
+ const unsigned char *p = s->tlsext_scts;
+ STACK_OF(SCT) *scts = o2i_SCT_LIST(NULL, &p, s->tlsext_scts_len);
+
+ scts_extracted = ct_move_scts(&s->scts, scts, SCT_SOURCE_TLS_EXTENSION);
+
+ SCT_LIST_free(scts);
+ }
+
+ return scts_extracted;
+}
+
+/*
+ * Checks for an OCSP response and then attempts to extract any SCTs found if it
+ * contains an SCT X509 extension. They will be stored in |s->scts|.
+ * Returns:
+ * - The number of SCTs extracted, assuming an OCSP response exists.
+ * - 0 if no OCSP response exists or it contains no SCTs.
+ * - A negative integer if an error occurs.
+ */
+static int ct_extract_ocsp_response_scts(SSL *s)
+{
+# ifndef OPENSSL_NO_OCSP
+ int scts_extracted = 0;
+ const unsigned char *p;
+ OCSP_BASICRESP *br = NULL;
+ OCSP_RESPONSE *rsp = NULL;
+ STACK_OF(SCT) *scts = NULL;
+ int i;
+
+ if (s->tlsext_ocsp_resp == NULL || s->tlsext_ocsp_resplen == 0)
+ goto err;
+
+ p = s->tlsext_ocsp_resp;
+ rsp = d2i_OCSP_RESPONSE(NULL, &p, s->tlsext_ocsp_resplen);
+ if (rsp == NULL)
+ goto err;
+
+ br = OCSP_response_get1_basic(rsp);
+ if (br == NULL)
+ goto err;
+
+ for (i = 0; i < OCSP_resp_count(br); ++i) {
+ OCSP_SINGLERESP *single = OCSP_resp_get0(br, i);
+
+ if (single == NULL)
+ continue;
+
+ scts =
+ OCSP_SINGLERESP_get1_ext_d2i(single, NID_ct_cert_scts, NULL, NULL);
+ scts_extracted =
+ ct_move_scts(&s->scts, scts, SCT_SOURCE_OCSP_STAPLED_RESPONSE);
+ if (scts_extracted < 0)
+ goto err;
+ }
+ err:
+ SCT_LIST_free(scts);
+ OCSP_BASICRESP_free(br);
+ OCSP_RESPONSE_free(rsp);
+ return scts_extracted;
+# else
+ /* Behave as if no OCSP response exists */
+ return 0;
+# endif
+}
+
+/*
+ * Attempts to extract SCTs from the peer certificate.
+ * Return the number of SCTs extracted, or a negative integer if an error
+ * occurs.
+ */
+static int ct_extract_x509v3_extension_scts(SSL *s)
+{
+ int scts_extracted = 0;
+ X509 *cert = s->session != NULL ? s->session->peer : NULL;
+
+ if (cert != NULL) {
+ STACK_OF(SCT) *scts =
+ X509_get_ext_d2i(cert, NID_ct_precert_scts, NULL, NULL);
+
+ scts_extracted =
+ ct_move_scts(&s->scts, scts, SCT_SOURCE_X509V3_EXTENSION);
+
+ SCT_LIST_free(scts);
+ }
+
+ return scts_extracted;
+}
+
+/*
+ * Attempts to find all received SCTs by checking TLS extensions, the OCSP
+ * response (if it exists) and X509v3 extensions in the certificate.
+ * Returns NULL if an error occurs.
+ */
+const STACK_OF(SCT) *SSL_get0_peer_scts(SSL *s)
+{
+ if (!s->scts_parsed) {
+ if (ct_extract_tls_extension_scts(s) < 0 ||
+ ct_extract_ocsp_response_scts(s) < 0 ||
+ ct_extract_x509v3_extension_scts(s) < 0)
+ goto err;
+
+ s->scts_parsed = 1;
+ }
+ return s->scts;
+ err:
+ return NULL;
+}
+
+static int ct_permissive(const CT_POLICY_EVAL_CTX * ctx,
+ const STACK_OF(SCT) *scts, void *unused_arg)
+{
+ return 1;
+}
+
+static int ct_strict(const CT_POLICY_EVAL_CTX * ctx,
+ const STACK_OF(SCT) *scts, void *unused_arg)
+{
+ int count = scts != NULL ? sk_SCT_num(scts) : 0;
+ int i;
+
+ for (i = 0; i < count; ++i) {
+ SCT *sct = sk_SCT_value(scts, i);
+ int status = SCT_get_validation_status(sct);
+
+ if (status == SCT_VALIDATION_STATUS_VALID)
+ return 1;
+ }
+ SSLerr(SSL_F_CT_STRICT, SSL_R_NO_VALID_SCTS);
+ return 0;
+}
+
+int SSL_set_ct_validation_callback(SSL *s, ssl_ct_validation_cb callback,
+ void *arg)
+{
+ /*
+ * Since code exists that uses the custom extension handler for CT, look
+ * for this and throw an error if they have already registered to use CT.
+ */
+ if (callback != NULL && SSL_CTX_has_client_custom_ext(s->ctx,
+ TLSEXT_TYPE_signed_certificate_timestamp))
+ {
+ SSLerr(SSL_F_SSL_SET_CT_VALIDATION_CALLBACK,
+ SSL_R_CUSTOM_EXT_HANDLER_ALREADY_INSTALLED);
+ return 0;
+ }
+
+ if (callback != NULL) {
+ /*
+ * If we are validating CT, then we MUST accept SCTs served via OCSP
+ */
+ if (!SSL_set_tlsext_status_type(s, TLSEXT_STATUSTYPE_ocsp))
+ return 0;
+ }
+
+ s->ct_validation_callback = callback;
+ s->ct_validation_callback_arg = arg;
+
+ return 1;
+}
+
+int SSL_CTX_set_ct_validation_callback(SSL_CTX *ctx,
+ ssl_ct_validation_cb callback, void *arg)
+{
+ /*
+ * Since code exists that uses the custom extension handler for CT, look for
+ * this and throw an error if they have already registered to use CT.
+ */
+ if (callback != NULL && SSL_CTX_has_client_custom_ext(ctx,
+ TLSEXT_TYPE_signed_certificate_timestamp))
+ {
+ SSLerr(SSL_F_SSL_CTX_SET_CT_VALIDATION_CALLBACK,
+ SSL_R_CUSTOM_EXT_HANDLER_ALREADY_INSTALLED);
+ return 0;
+ }
+
+ ctx->ct_validation_callback = callback;
+ ctx->ct_validation_callback_arg = arg;
+ return 1;
+}
+
+int SSL_ct_is_enabled(const SSL *s)
+{
+ return s->ct_validation_callback != NULL;
+}
+
+int SSL_CTX_ct_is_enabled(const SSL_CTX *ctx)
+{
+ return ctx->ct_validation_callback != NULL;
+}
+
+int ssl_validate_ct(SSL *s)
+{
+ int ret = 0;
+ X509 *cert = s->session != NULL ? s->session->peer : NULL;
+ X509 *issuer;
+ SSL_DANE *dane = &s->dane;
+ CT_POLICY_EVAL_CTX *ctx = NULL;
+ const STACK_OF(SCT) *scts;
+
+ /*
+ * If no callback is set, the peer is anonymous, or its chain is invalid,
+ * skip SCT validation - just return success. Applications that continue
+ * handshakes without certificates, with unverified chains, or pinned leaf
+ * certificates are outside the scope of the WebPKI and CT.
+ *
+ * The above exclusions notwithstanding the vast majority of peers will
+ * have rather ordinary certificate chains validated by typical
+ * applications that perform certificate verification and therefore will
+ * process SCTs when enabled.
+ */
+ if (s->ct_validation_callback == NULL || cert == NULL ||
+ s->verify_result != X509_V_OK ||
+ s->verified_chain == NULL || sk_X509_num(s->verified_chain) <= 1)
+ return 1;
+
+ /*
+ * CT not applicable for chains validated via DANE-TA(2) or DANE-EE(3)
+ * trust-anchors. See https://tools.ietf.org/html/rfc7671#section-4.2
+ */
+ if (DANETLS_ENABLED(dane) && dane->mtlsa != NULL) {
+ switch (dane->mtlsa->usage) {
+ case DANETLS_USAGE_DANE_TA:
+ case DANETLS_USAGE_DANE_EE:
+ return 1;
+ }
+ }
+
+ ctx = CT_POLICY_EVAL_CTX_new();
+ if (ctx == NULL) {
+ SSLerr(SSL_F_SSL_VALIDATE_CT, ERR_R_MALLOC_FAILURE);
+ goto end;
+ }
+
+ issuer = sk_X509_value(s->verified_chain, 1);
+ CT_POLICY_EVAL_CTX_set1_cert(ctx, cert);
+ CT_POLICY_EVAL_CTX_set1_issuer(ctx, issuer);
+ CT_POLICY_EVAL_CTX_set_shared_CTLOG_STORE(ctx, s->ctx->ctlog_store);
+
+ scts = SSL_get0_peer_scts(s);
+
+ /*
+ * This function returns success (> 0) only when all the SCTs are valid, 0
+ * when some are invalid, and < 0 on various internal errors (out of
+ * memory, etc.). Having some, or even all, invalid SCTs is not sufficient
+ * reason to abort the handshake, that decision is up to the callback.
+ * Therefore, we error out only in the unexpected case that the return
+ * value is negative.
+ *
+ * XXX: One might well argue that the return value of this function is an
+ * unfortunate design choice. Its job is only to determine the validation
+ * status of each of the provided SCTs. So long as it correctly separates
+ * the wheat from the chaff it should return success. Failure in this case
+ * ought to correspond to an inability to carry out its duties.
+ */
+ if (SCT_LIST_validate(scts, ctx) < 0) {
+ SSLerr(SSL_F_SSL_VALIDATE_CT, SSL_R_SCT_VERIFICATION_FAILED);
+ goto end;
+ }
+
+ ret = s->ct_validation_callback(ctx, scts, s->ct_validation_callback_arg);
+ if (ret < 0)
+ ret = 0; /* This function returns 0 on failure */
+
+ end:
+ CT_POLICY_EVAL_CTX_free(ctx);
+ /*
+ * With SSL_VERIFY_NONE the session may be cached and re-used despite a
+ * failure return code here. Also the application may wish the complete
+ * the handshake, and then disconnect cleanly at a higher layer, after
+ * checking the verification status of the completed connection.
+ *
+ * We therefore force a certificate verification failure which will be
+ * visible via SSL_get_verify_result() and cached as part of any resumed
+ * session.
+ *
+ * Note: the permissive callback is for information gathering only, always
+ * returns success, and does not affect verification status. Only the
+ * strict callback or a custom application-specified callback can trigger
+ * connection failure or record a verification error.
+ */
+ if (ret <= 0)
+ s->verify_result = X509_V_ERR_NO_VALID_SCTS;
+ return ret;
+}
+
+int SSL_CTX_enable_ct(SSL_CTX *ctx, int validation_mode)
+{
+ switch (validation_mode) {
+ default:
+ SSLerr(SSL_F_SSL_CTX_ENABLE_CT, SSL_R_INVALID_CT_VALIDATION_TYPE);
+ return 0;
+ case SSL_CT_VALIDATION_PERMISSIVE:
+ return SSL_CTX_set_ct_validation_callback(ctx, ct_permissive, NULL);
+ case SSL_CT_VALIDATION_STRICT:
+ return SSL_CTX_set_ct_validation_callback(ctx, ct_strict, NULL);
+ }
+}
+
+int SSL_enable_ct(SSL *s, int validation_mode)
+{
+ switch (validation_mode) {
+ default:
+ SSLerr(SSL_F_SSL_ENABLE_CT, SSL_R_INVALID_CT_VALIDATION_TYPE);
+ return 0;
+ case SSL_CT_VALIDATION_PERMISSIVE:
+ return SSL_set_ct_validation_callback(s, ct_permissive, NULL);
+ case SSL_CT_VALIDATION_STRICT:
+ return SSL_set_ct_validation_callback(s, ct_strict, NULL);
+ }
+}
+
+int SSL_CTX_set_default_ctlog_list_file(SSL_CTX *ctx)
+{
+ return CTLOG_STORE_load_default_file(ctx->ctlog_store);
+}
+
+int SSL_CTX_set_ctlog_list_file(SSL_CTX *ctx, const char *path)
+{
+ return CTLOG_STORE_load_file(ctx->ctlog_store, path);
+}
+
+void SSL_CTX_set0_ctlog_store(SSL_CTX *ctx, CTLOG_STORE * logs)
+{
+ CTLOG_STORE_free(ctx->ctlog_store);
+ ctx->ctlog_store = logs;
+}
+
+const CTLOG_STORE *SSL_CTX_get0_ctlog_store(const SSL_CTX *ctx)
+{
+ return ctx->ctlog_store;
+}
+
+#endif