Change default SSL to "enabled" if user specifies fingerprint/certificate

Currently if a user specifies a ca file or fingerprint to verify peer,
the default behavior is SSL autodetect which allows for mitm downgrade
attacks. It should be investigated whether a manual override should be
allowed - the configuration is likely always invalid.

src/rpc/core_rpc_server.cpp

@@ -149,13 +149,6 @@ namespace cryptonote
     if (rpc_config->login)
       http_login.emplace(std::move(rpc_config->login->username), std::move(rpc_config->login->password).password());
 
-    epee::net_utils::ssl_support_t ssl_support;
-    const std::string ssl = command_line::get_arg(vm, arg_rpc_ssl);
-    if (!epee::net_utils::ssl_support_from_string(ssl_support, ssl))
-    {
-      MFATAL("Invalid RPC SSL support: " << ssl);
-      return false;
-    }
     const std::string ssl_private_key = command_line::get_arg(vm, arg_rpc_ssl_private_key);
     const std::string ssl_certificate = command_line::get_arg(vm, arg_rpc_ssl_certificate);
     std::string ssl_ca_path = command_line::get_arg(vm, arg_rpc_ssl_ca_certificates);
@@ -165,6 +158,18 @@ namespace cryptonote
     std::transform(ssl_allowed_fingerprint_strings.begin(), ssl_allowed_fingerprint_strings.end(), ssl_allowed_fingerprints.begin(), epee::from_hex::vector);
     const bool ssl_allow_any_cert = command_line::get_arg(vm, arg_rpc_ssl_allow_any_cert);
 
+    // user specified CA file or fingeprints implies enabled SSL by default
+    epee::net_utils::ssl_support_t ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_enabled;
+    if ((ssl_allowed_fingerprints.empty() && ssl_ca_path.empty()) || !command_line::is_arg_defaulted(vm, arg_rpc_ssl))
+    {
+      const std::string ssl = command_line::get_arg(vm, arg_rpc_ssl);
+      if (!epee::net_utils::ssl_support_from_string(ssl_support, ssl))
+      {
+        MFATAL("Invalid RPC SSL support: " << ssl);
+        return false;
+      }
+    }
+
     auto rng = [](size_t len, uint8_t *ptr){ return crypto::rand(len, ptr); };
     return epee::http_server_impl_base<core_rpc_server, connection_context>::init(
       rng, std::move(port), std::move(rpc_config->bind_ip), std::move(rpc_config->access_control_origins), std::move(http_login),

src/wallet/wallet2.cpp

@@ -325,9 +325,14 @@ std::unique_ptr<tools::wallet2> make_basic(const boost::program_options::variabl
   auto daemon_ssl_allowed_fingerprints = command_line::get_arg(vm, opts.daemon_ssl_allowed_fingerprints);
   auto daemon_ssl_allow_any_cert = command_line::get_arg(vm, opts.daemon_ssl_allow_any_cert);
   auto daemon_ssl = command_line::get_arg(vm, opts.daemon_ssl);
-  epee::net_utils::ssl_support_t ssl_support;
+
-  THROW_WALLET_EXCEPTION_IF(!epee::net_utils::ssl_support_from_string(ssl_support, daemon_ssl), tools::error::wallet_internal_error,
+  // user specified CA file or fingeprints implies enabled SSL by default
-      tools::wallet2::tr("Invalid argument for ") + std::string(opts.daemon_ssl.name));
+  epee::net_utils::ssl_support_t ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_enabled;
+  if ((daemon_ssl_ca_file.empty() && daemon_ssl_allowed_fingerprints.empty()) || !command_line::is_arg_defaulted(vm, opts.daemon_ssl))
+  {
+    THROW_WALLET_EXCEPTION_IF(!epee::net_utils::ssl_support_from_string(ssl_support, daemon_ssl), tools::error::wallet_internal_error,
+       tools::wallet2::tr("Invalid argument for ") + std::string(opts.daemon_ssl.name));
+  }
 
   THROW_WALLET_EXCEPTION_IF(!daemon_address.empty() && !daemon_host.empty() && 0 != daemon_port,
       tools::error::wallet_internal_error, tools::wallet2::tr("can't specify daemon host or port more than once"));

src/wallet/wallet_rpc_server.cpp

@@ -250,11 +250,16 @@ namespace tools
     auto rpc_ssl_ca_file = command_line::get_arg(vm, arg_rpc_ssl_ca_certificates);
     auto rpc_ssl_allowed_fingerprints = command_line::get_arg(vm, arg_rpc_ssl_allowed_fingerprints);
     auto rpc_ssl = command_line::get_arg(vm, arg_rpc_ssl);
-    epee::net_utils::ssl_support_t rpc_ssl_support;
+    epee::net_utils::ssl_support_t rpc_ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_enabled;
-    if (!epee::net_utils::ssl_support_from_string(rpc_ssl_support, rpc_ssl))
+
+    // user specified CA file or fingeprints implies enabled SSL by default
+    if ((rpc_ssl_ca_file.empty() && rpc_ssl_allowed_fingerprints.empty()) || !command_line::is_arg_defaulted(vm, arg_rpc_ssl))
     {
-      MERROR("Invalid argument for " << std::string(arg_rpc_ssl.name));
+      if (!epee::net_utils::ssl_support_from_string(rpc_ssl_support, rpc_ssl))
-      return false;
+      {
+        MERROR("Invalid argument for " << std::string(arg_rpc_ssl.name));
+        return false;
+      }
     }
 
     std::vector<std::vector<uint8_t>> allowed_fingerprints{ rpc_ssl_allowed_fingerprints.size() };