nghttpx: Add --curves option to specify supported elliptic curves

gennghttpxfun.py

@@ -107,7 +107,8 @@ OPTIONS = [
     "add-forwarded",
     "strip-incoming-forwarded",
     "forwarded-by",
-    "forwarded-for"
+    "forwarded-for",
+    "curves"
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -933,6 +933,7 @@ void fill_default_config() {
     dyn_recconf.idle_timeout = 1_s;
 
     tlsconf.session_timeout = std::chrono::hours(12);
+    tlsconf.curves = "P-256";
   }
 
   auto &httpconf = mod_config()->http;
@@ -1437,6 +1438,12 @@ SSL/TLS:
               TLS HTTP/2 backends.
               Default: )"
       << util::duration_str(get_config()->tls.dyn_rec.idle_timeout) << R"(
+  --curves=<CURVES>
+              Specify  supported  elliptic   curves  in  frontend  TLS
+              connection.  The <CURVES> must be a colon separated list
+              of curves.   The curve name  is either NIST  name (e.g.,
+              "P-256") or OpenSSL OID name (e.g., "prime256v1").
+              Default: )" << get_config()->tls.curves << R"(
 
 HTTP/2 and SPDY:
   -c, --http2-max-concurrent-streams=<N>
@@ -2212,6 +2219,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_STRIP_INCOMING_FORWARDED, no_argument, &flag, 98},
         {SHRPX_OPT_FORWARDED_BY, required_argument, &flag, 99},
         {SHRPX_OPT_FORWARDED_FOR, required_argument, &flag, 100},
+        {SHRPX_OPT_CURVES, required_argument, &flag, 101},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -2641,6 +2649,10 @@ int main(int argc, char **argv) {
         // --forwarded-for
         cmdcfgs.emplace_back(SHRPX_OPT_FORWARDED_FOR, optarg);
         break;
+      case 101:
+        // --curves
+        cmdcfgs.emplace_back(SHRPX_OPT_CURVES, optarg);
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -694,6 +694,7 @@ enum {
   SHRPX_OPTID_CLIENT_PRIVATE_KEY_FILE,
   SHRPX_OPTID_CLIENT_PROXY,
   SHRPX_OPTID_CONF,
+  SHRPX_OPTID_CURVES,
   SHRPX_OPTID_DAEMON,
   SHRPX_OPTID_DH_PARAM_FILE,
   SHRPX_OPTID_ERRORLOG_FILE,
@@ -803,6 +804,11 @@ int option_lookup_token(const char *name, size_t namelen) {
         return SHRPX_OPTID_DAEMON;
       }
       break;
+    case 's':
+      if (util::strieq_l("curve", name, 5)) {
+        return SHRPX_OPTID_CURVES;
+      }
+      break;
     case 't':
       if (util::strieq_l("cacer", name, 5)) {
         return SHRPX_OPTID_CACERT;
@@ -2152,6 +2158,13 @@ int parse_config(const char *opt, const char *optarg,
 
     return 0;
   }
+  case SHRPX_OPTID_CURVES:
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+    mod_config()->tls.curves = optarg;
+#else  // OPENSSL_VERSION_NUMBER < 0x10002000L
+    LOG(WARN) << opt << ": this option requires OpenSSL >= 1.0.2.";
+#endif // OPENSSL_VERSION_NUMBER < 0x10002000L
+    return 0;
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";
 

src/shrpx_config.h

@@ -196,6 +196,7 @@ constexpr char SHRPX_OPT_STRIP_INCOMING_FORWARDED[] =
     "strip-incoming-forwarded";
 constexpr static char SHRPX_OPT_FORWARDED_BY[] = "forwarded-by";
 constexpr char SHRPX_OPT_FORWARDED_FOR[] = "forwarded-for";
+constexpr char SHRPX_OPT_CURVES[] = "curves";
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -366,6 +367,9 @@ struct TLSConfig {
   // passed to SSL_CTX_set_options().
   long int tls_proto_mask;
   std::string backend_sni_name;
+  // Supported elliptic curves, separated by colon (':').  This is
+  // directly passed to OpenSSL configuration function.
+  std::string curves;
   std::chrono::seconds session_timeout;
   std::unique_ptr<char[]> private_key_file;
   std::unique_ptr<char[]> private_key_passwd;

src/shrpx_ssl.cc

@@ -506,13 +506,28 @@ SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file
   }
 
 #ifndef OPENSSL_NO_EC
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  auto conf_ctx = SSL_CONF_CTX_new();
 
-  // Disabled SSL_CTX_set_ecdh_auto, because computational cost of
-  // chosen curve is much higher than P-256.
+  SSL_CONF_CTX_set_flags(conf_ctx, SSL_CONF_FLAG_SERVER | SSL_CONF_FLAG_FILE);
+  SSL_CONF_CTX_set_ssl_ctx(conf_ctx, ssl_ctx);
 
-  // #if OPENSSL_VERSION_NUMBER >= 0x10002000L
-  //   SSL_CTX_set_ecdh_auto(ssl_ctx, 1);
-  // #else // OPENSSL_VERSION_NUBMER < 0x10002000L
+  if (!tlsconf.curves.empty()) {
+    if (SSL_CONF_cmd(conf_ctx, "Curves", tlsconf.curves.c_str()) != 2) {
+      LOG(FATAL) << "Setting named curves failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+  }
+
+  if (SSL_CONF_CTX_finish(conf_ctx) == 0) {
+    LOG(FATAL) << "Configuring SSL_CTX failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+  SSL_CONF_CTX_free(conf_ctx);
+#else  // OPENSSL_VERSION_NUBMER < 0x10002000L
   // Use P-256, which is sufficiently secure at the time of this
   // writing.
   auto ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
@@ -523,7 +538,7 @@ SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file
   }
   SSL_CTX_set_tmp_ecdh(ssl_ctx, ecdh);
   EC_KEY_free(ecdh);
-// #endif // OPENSSL_VERSION_NUBMER < 0x10002000L
+#endif // OPENSSL_VERSION_NUBMER < 0x10002000L
 
 #endif // OPENSSL_NO_EC