Adds CT validation to SSL connections
Disabled by default, but can be enabled by setting the
ct_validation_callback on a SSL or SSL_CTX.
Reviewed-by: Ben Laurie <ben@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/ssl/t1_ext.c b/ssl/t1_ext.c
index 09f1044..eb7d8a7 100644
--- a/ssl/t1_ext.c
+++ b/ssl/t1_ext.c
@@ -54,11 +54,14 @@
/* Custom extension utility functions */
+#ifndef OPENSSL_NO_CT
+# include <openssl/ct.h>
+#endif
#include "ssl_locl.h"
/* Find a custom extension from the list. */
-static custom_ext_method *custom_ext_find(custom_ext_methods *exts,
+static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
unsigned int ext_type)
{
size_t i;
@@ -211,8 +214,12 @@
*/
if (!add_cb && free_cb)
return 0;
- /* Don't add if extension supported internally. */
- if (SSL_extension_supported(ext_type))
+ /*
+ * Don't add if extension supported internally, but make exception
+ * for extension types that previously were not supported, but now are.
+ */
+ if (SSL_extension_supported(ext_type) &&
+ ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
return 0;
/* Extension type must fit in 16 bits */
if (ext_type > 0xffff)
@@ -241,6 +248,12 @@
return 1;
}
+/* Return true if a client custom extension exists, false otherwise */
+int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
+{
+ return custom_ext_find(&ctx->cert->cli_ext, ext_type) != NULL;
+}
+
/* Application level functions to add custom extension callbacks */
int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
custom_ext_add_cb add_cb,
@@ -249,8 +262,25 @@
custom_ext_parse_cb parse_cb,
void *parse_arg)
{
- return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type,
- add_cb, free_cb, add_arg, parse_cb, parse_arg);
+ int ret = custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
+ free_cb, add_arg, parse_cb, parse_arg);
+
+ if (ret != 1)
+ goto end;
+
+#ifndef OPENSSL_NO_CT
+ /*
+ * We don't want applications registering callbacks for SCT extensions
+ * whilst simultaneously using the built-in SCT validation features, as
+ * these two things may not play well together.
+ */
+ if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
+ SSL_CTX_get_ct_validation_callback(ctx) != NULL) {
+ ret = 0;
+ }
+#endif
+end:
+ return ret;
}
int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
@@ -280,6 +310,7 @@
case TLSEXT_TYPE_signature_algorithms:
case TLSEXT_TYPE_srp:
case TLSEXT_TYPE_status_request:
+ case TLSEXT_TYPE_signed_certificate_timestamp:
case TLSEXT_TYPE_use_srtp:
#ifdef TLSEXT_TYPE_encrypt_then_mac
case TLSEXT_TYPE_encrypt_then_mac:
