Add --honor-cipher-order option to mitigate BEAST attacks

src/shrpx.cc

@@ -380,6 +380,7 @@ void fill_default_config()
   // Default accept() backlog
   mod_config()->backlog = 256;
   mod_config()->ciphers = 0;
+  mod_config()->honor_cipher_order = false;
   mod_config()->spdy_proxy = false;
   mod_config()->spdy_bridge = false;
   mod_config()->client_proxy = false;
@@ -501,6 +502,9 @@ void print_help(std::ostream& out)
       << "  SSL/TLS:\n"
       << "    --ciphers=<SUITE>  Set allowed cipher list. The format of the\n"
       << "                       string is described in OpenSSL ciphers(1).\n"
+      << "    --honor-cipher-order\n"
+      << "                       Honor server cipher order, giving the\n"
+      << "                       ability to mitigate BEAST attacks.\n"
       << "    -k, --insecure     When used with -p or --client, don't verify\n"
       << "                       backend server's certificate.\n"
       << "    --cacert=<PATH>    When used with -p or --client, set path to\n"
@@ -663,6 +667,7 @@ int main(int argc, char **argv)
       {"frontend-spdy-no-tls", no_argument, &flag, 29},
       {"frontend-spdy-proto", required_argument, &flag, 30},
       {"backend-tls-sni-field", required_argument, &flag, 31},
+      {"honor-cipher-order", no_argument, &flag, 32},
       {0, 0, 0, 0 }
     };
     int option_index = 0;
@@ -847,6 +852,11 @@ int main(int argc, char **argv)
         cmdcfgs.push_back(std::make_pair(SHRPX_OPT_BACKEND_TLS_SNI_FIELD,
                                          optarg));
         break;
+      case 32:
+        // --honor-cipher-order
+        cmdcfgs.push_back(std::make_pair(SHRPX_OPT_HONOR_CIPHER_ORDER,
+                                         "yes"));
+        break;
 
       default:
         break;

src/shrpx_config.cc

@@ -86,6 +86,7 @@ const char SHRPX_OPT_SYSLOG[] = "syslog";
 const char SHRPX_OPT_SYSLOG_FACILITY[] = "syslog-facility";
 const char SHRPX_OPT_BACKLOG[] = "backlog";
 const char SHRPX_OPT_CIPHERS[] = "ciphers";
+const char SHRPX_OPT_HONOR_CIPHER_ORDER[] = "honor-cipher-order";
 const char SHRPX_OPT_CLIENT[] = "client";
 const char SHRPX_OPT_INSECURE[] = "insecure";
 const char SHRPX_OPT_CACERT[] = "cacert";
@@ -353,6 +354,8 @@ int parse_config(const char *opt, const char *optarg)
     mod_config()->backlog = strtol(optarg, 0, 10);
   } else if(util::strieq(opt, SHRPX_OPT_CIPHERS)) {
     set_config_str(&mod_config()->ciphers, optarg);
+  } else if(util::strieq(opt, SHRPX_OPT_HONOR_CIPHER_ORDER)) {
+    mod_config()->honor_cipher_order = util::strieq(optarg, "yes");
   } else if(util::strieq(opt, SHRPX_OPT_CLIENT)) {
     mod_config()->client = util::strieq(optarg, "yes");
   } else if(util::strieq(opt, SHRPX_OPT_INSECURE)) {

src/shrpx_config.h

@@ -78,6 +78,7 @@ extern const char SHRPX_OPT_SYSLOG[];
 extern const char SHRPX_OPT_SYSLOG_FACILITY[];
 extern const char SHRPX_OPT_BACKLOG[];
 extern const char SHRPX_OPT_CIPHERS[];
+extern const char SHRPX_OPT_HONOR_CIPHER_ORDER[];
 extern const char SHRPX_OPT_CLIENT[];
 extern const char SHRPX_OPT_INSECURE[];
 extern const char SHRPX_OPT_CACERT[];
@@ -146,6 +147,7 @@ struct Config {
   bool use_syslog;
   int backlog;
   char *ciphers;
+  bool honor_cipher_order;
   bool client;
   // true if --client or --client-proxy are enabled.
   bool client_mode;

src/shrpx_ssl.cc

@@ -146,6 +146,9 @@ SSL_CTX* create_ssl_context(const char *private_key_file,
                  << ERR_error_string(ERR_get_error(), NULL);
       DIE();
     }
+    if(get_config()->honor_cipher_order) {
+      SSL_CTX_set_options(ssl_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
+    }
   }
 
   SSL_CTX_set_mode(ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);