Store RPC SSL key/cert for consistent authentication between runs

contrib/epee/include/net/abstract_tcp_server2.h

@@ -265,6 +265,12 @@ namespace net_utils
     template<class t_callback>
     bool connect_async(const std::string& adr, const std::string& port, uint32_t conn_timeot, const t_callback &cb, const std::string& bind_ip = "0.0.0.0", epee::net_utils::ssl_support_t ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_autodetect);
 
+    boost::asio::ssl::context& get_ssl_context() noexcept
+    {
+      assert(m_state != nullptr);
+      return m_state->ssl_context;
+    }
+
     typename t_protocol_handler::config_type& get_config_object()
     {
       assert(m_state != nullptr); // always set in constructor

contrib/epee/include/net/net_ssl.h

@@ -36,6 +36,7 @@
 #include <boost/utility/string_ref.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/ssl.hpp>
+#include <boost/filesystem/path.hpp>
 #include <boost/system/error_code.hpp>
 
 #define SSL_FINGERPRINT_SIZE 32
@@ -144,6 +145,9 @@ namespace net_utils
 
 	bool create_ec_ssl_certificate(EVP_PKEY *&pkey, X509 *&cert);
 	bool create_rsa_ssl_certificate(EVP_PKEY *&pkey, X509 *&cert);
+
+  //! Store private key for `ssl` at `base + ".key"` unencrypted and certificate for `ssl` at `base + ".crt"`.
+  boost::system::error_code store_ssl_keys(boost::asio::ssl::context& ssl, const boost::filesystem::path& base);
 }
 }
 

contrib/epee/src/net_ssl.cpp

@@ -29,6 +29,8 @@
 #include <string.h>
 #include <thread>
 #include <boost/asio/ssl.hpp>
+#include <boost/cerrno.hpp>
+#include <boost/filesystem/operations.hpp>
 #include <boost/lambda/lambda.hpp>
 #include <openssl/ssl.h>
 #include <openssl/pem.h>
@@ -567,6 +569,51 @@ bool ssl_support_from_string(ssl_support_t &ssl, boost::string_ref s)
   return true;
 }
 
+boost::system::error_code store_ssl_keys(boost::asio::ssl::context& ssl, const boost::filesystem::path& base)
+{
+  EVP_PKEY* ssl_key = nullptr;
+  X509* ssl_cert = nullptr;
+  const auto ctx = ssl.native_handle();
+  CHECK_AND_ASSERT_MES(ctx, boost::system::error_code(EINVAL, boost::system::system_category()), "Context is null");
+  CHECK_AND_ASSERT_MES(base.has_filename(), boost::system::error_code(EINVAL, boost::system::system_category()), "Need filename");
+  if (!(ssl_key = SSL_CTX_get0_privatekey(ctx)) || !(ssl_cert = SSL_CTX_get0_certificate(ctx)))
+    return {EINVAL, boost::system::system_category()};
+
+  using file_closer = int(std::FILE*);
+  boost::system::error_code error{};
+  std::unique_ptr<std::FILE, file_closer*> file{nullptr, std::fclose};
+
+  // write key file unencrypted
+  {
+    const boost::filesystem::path key_file{base.string() + ".key"};
+    file.reset(std::fopen(key_file.string().c_str(), "wb"));
+    if (!file)
+      return {errno, boost::system::system_category()};
+    boost::filesystem::permissions(key_file, boost::filesystem::owner_read, error);
+    if (error)
+      return error;
+    if (!PEM_write_PrivateKey(file.get(), ssl_key, nullptr, nullptr, 0, nullptr, nullptr))
+      return boost::asio::error::ssl_errors(ERR_get_error());
+    if (std::fclose(file.release()) != 0)
+      return {errno, boost::system::system_category()};
+  }
+
+  // write certificate file in standard SSL X.509 unencrypted
+  const boost::filesystem::path cert_file{base.string() + ".crt"};
+  file.reset(std::fopen(cert_file.string().c_str(), "wb"));
+  if (!file)
+    return {errno, boost::system::system_category()};
+  const auto cert_perms = (boost::filesystem::owner_read | boost::filesystem::group_read | boost::filesystem::others_read);
+  boost::filesystem::permissions(cert_file, cert_perms, error);
+  if (error)
+    return error;
+  if (!PEM_write_X509(file.get(), ssl_cert))
+    return boost::asio::error::ssl_errors(ERR_get_error());
+  if (std::fclose(file.release()) != 0)
+    return {errno, boost::system::system_category()};
+  return error;
+}
+
 } // namespace
 } // namespace
 

src/rpc/core_rpc_server.cpp

@@ -278,6 +278,7 @@ namespace cryptonote
       }
     }
     disable_rpc_ban = rpc_config->disable_rpc_ban;
+    const std::string data_dir{command_line::get_arg(vm, cryptonote::arg_data_dir)};
     std::string address = command_line::get_arg(vm, arg_rpc_payment_address);
     if (!address.empty() && allow_rpc_payment)
     {
@@ -306,7 +307,7 @@ namespace cryptonote
       }
       m_rpc_payment_allow_free_loopback = command_line::get_arg(vm, arg_rpc_payment_allow_free_loopback);
       m_rpc_payment.reset(new rpc_payment(info.address, diff, credits));
-      m_rpc_payment->load(command_line::get_arg(vm, cryptonote::arg_data_dir));
+      m_rpc_payment->load(data_dir);
       m_p2p.set_rpc_credits_per_hash(RPC_CREDITS_PER_HASH_SCALE * (credits / (float)diff));
     }
 
@@ -333,12 +334,32 @@ namespace cryptonote
     if (m_rpc_payment)
       m_net_server.add_idle_handler([this](){ return m_rpc_payment->on_idle(); }, 60 * 1000);
 
+    bool store_ssl_key = !restricted && rpc_config->ssl_options.auth.certificate_path.empty();
+    const auto ssl_base_path = (boost::filesystem::path{data_dir} / "rpc_ssl").string();
+    if (store_ssl_key && boost::filesystem::exists(ssl_base_path + ".crt"))
+    {
+      // load key from previous run, password prompted by OpenSSL
+      store_ssl_key = false;
+      rpc_config->ssl_options.auth =
+        epee::net_utils::ssl_authentication_t{ssl_base_path + ".key", ssl_base_path + ".crt"};
+    }
+
     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(
+    const bool inited = epee::http_server_impl_base<core_rpc_server, connection_context>::init(
       rng, std::move(port), std::move(bind_ip_str),
       std::move(bind_ipv6_str), std::move(rpc_config->use_ipv6), std::move(rpc_config->require_ipv4),
       std::move(rpc_config->access_control_origins), std::move(http_login), std::move(rpc_config->ssl_options)
     );
+
+    if (store_ssl_key && inited)
+    {
+      // new keys were generated, store for next run
+      const auto error = epee::net_utils::store_ssl_keys(m_net_server.get_ssl_context(), ssl_base_path);
+      if (error)
+        MFATAL("Failed to store HTTP SSL cert/key for " << (restricted ? "restricted " : "") << "RPC server: " << error.message());
+      return !bool(error);
+    }
+    return inited;
   }
   //------------------------------------------------------------------------------------------------------------------------------
   bool core_rpc_server::check_payment(const std::string &client_message, uint64_t payment, const std::string &rpc, bool same_ts, std::string &message, uint64_t &credits, std::string &top_hash)