Change SSL certificate file list to OpenSSL builtin load_verify_location

Specifying SSL certificates for peer verification does an exact match,
making it a not-so-obvious alias for the fingerprints option. This
changes the checks to OpenSSL which loads concatenated certificate(s)
from a single file and does a certificate-authority (chain of trust)
check instead. There is no drop in security - a compromised exact match
fingerprint has the same worse case failure. There is increased security
in allowing separate long-term CA key and short-term SSL server keys.

This also removes loading of the system-default CA files if a custom
CA file or certificate fingerprint is specified.

4 files changed, 19 insertions, 40 deletions

diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 54fbd9ca8..c4f466699 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -243,7 +243,7 @@ struct options {
   const command_line::arg_descriptor<std::string> daemon_ssl = {"daemon-ssl", tools::wallet2::tr("Enable SSL on daemon RPC connections: enabled|disabled|autodetect"), "autodetect"};
   const command_line::arg_descriptor<std::string> daemon_ssl_private_key = {"daemon-ssl-private-key", tools::wallet2::tr("Path to a PEM format private key"), ""};
   const command_line::arg_descriptor<std::string> daemon_ssl_certificate = {"daemon-ssl-certificate", tools::wallet2::tr("Path to a PEM format certificate"), ""};
-  const command_line::arg_descriptor<std::vector<std::string>> daemon_ssl_allowed_certificates = {"daemon-ssl-allowed-certificates", tools::wallet2::tr("List of paths to PEM format certificates of allowed RPC servers")};
+  const command_line::arg_descriptor<std::string> daemon_ssl_ca_certificates = {"daemon-ssl-ca-certificates", tools::wallet2::tr("Path to file containing concatenated PEM format certificate(s) to replace system CA(s).")};
   const command_line::arg_descriptor<std::vector<std::string>> daemon_ssl_allowed_fingerprints = {"daemon-ssl-allowed-fingerprints", tools::wallet2::tr("List of valid fingerprints of allowed RPC servers")};
   const command_line::arg_descriptor<bool> daemon_ssl_allow_any_cert = {"daemon-ssl-allow-any-cert", tools::wallet2::tr("Allow any SSL certificate from the daemon"), false};
   const command_line::arg_descriptor<bool> testnet = {"testnet", tools::wallet2::tr("For testnet. Daemon must also be launched with --testnet flag"), false};
@@ -321,7 +321,7 @@ std::unique_ptr<tools::wallet2> make_basic(const boost::program_options::variabl
   auto device_derivation_path = command_line::get_arg(vm, opts.hw_device_derivation_path);
   auto daemon_ssl_private_key = command_line::get_arg(vm, opts.daemon_ssl_private_key);
   auto daemon_ssl_certificate = command_line::get_arg(vm, opts.daemon_ssl_certificate);
-  auto daemon_ssl_allowed_certificates = command_line::get_arg(vm, opts.daemon_ssl_allowed_certificates);
+  auto daemon_ssl_ca_file = command_line::get_arg(vm, opts.daemon_ssl_ca_certificates);
   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);
@@ -367,11 +367,11 @@ std::unique_ptr<tools::wallet2> make_basic(const boost::program_options::variabl
     // which both authenticates and encrypts
     const bool unencrypted_proxy =
       !real_daemon.ends_with(".onion") && !real_daemon.ends_with(".i2p") &&
-      daemon_ssl_allowed_certificates.empty() && daemon_ssl_allowed_fingerprints.empty();
+      daemon_ssl_ca_file.empty() && daemon_ssl_allowed_fingerprints.empty();
     THROW_WALLET_EXCEPTION_IF(
       unencrypted_proxy,
       tools::error::wallet_internal_error,
-      std::string{"Use of --"} + opts.proxy.name + " requires --" + opts.daemon_ssl_allowed_certificates.name + " or --" + opts.daemon_ssl_allowed_fingerprints.name + " or use of a .onion/.i2p domain"
+      std::string{"Use of --"} + opts.proxy.name + " requires --" + opts.daemon_ssl_ca_certificates.name + " or --" + opts.daemon_ssl_allowed_fingerprints.name + " or use of a .onion/.i2p domain"
     );
 
     const auto proxy_address = command_line::get_arg(vm, opts.proxy);
@@ -416,22 +416,11 @@ std::unique_ptr<tools::wallet2> make_basic(const boost::program_options::variabl
     catch (const std::exception &e) { }
   }
 
-  std::list<std::string> ssl_allowed_certificates;
-  for (const std::string &path: daemon_ssl_allowed_certificates)
-  {
-      ssl_allowed_certificates.push_back({});
-      if (!epee::file_io_utils::load_file_to_string(path, ssl_allowed_certificates.back()))
-      {
-        MERROR("Failed to load certificate: " << path);
-        ssl_allowed_certificates.back() = std::string();
-      }
-  }
-
   std::vector<std::vector<uint8_t>> ssl_allowed_fingerprints{ daemon_ssl_allowed_fingerprints.size() };
   std::transform(daemon_ssl_allowed_fingerprints.begin(), daemon_ssl_allowed_fingerprints.end(), ssl_allowed_fingerprints.begin(), epee::from_hex::vector);
 
   std::unique_ptr<tools::wallet2> wallet(new tools::wallet2(nettype, kdf_rounds, unattended));
-  wallet->init(std::move(daemon_address), std::move(login), std::move(proxy), 0, *trusted_daemon, ssl_support, std::make_pair(daemon_ssl_private_key, daemon_ssl_certificate), ssl_allowed_certificates, ssl_allowed_fingerprints, daemon_ssl_allow_any_cert);
+  wallet->init(std::move(daemon_address), std::move(login), std::move(proxy), 0, *trusted_daemon, ssl_support, std::make_pair(daemon_ssl_private_key, daemon_ssl_certificate), std::move(daemon_ssl_ca_file), ssl_allowed_fingerprints, daemon_ssl_allow_any_cert);
   boost::filesystem::path ringdb_path = command_line::get_arg(vm, opts.shared_ringdb_dir);
   wallet->set_ring_database(ringdb_path.string());
   wallet->get_message_store().set_options(vm);
@@ -1100,7 +1089,7 @@ void wallet2::init_options(boost::program_options::options_description& desc_par
   command_line::add_arg(desc_params, opts.daemon_ssl);
   command_line::add_arg(desc_params, opts.daemon_ssl_private_key);
   command_line::add_arg(desc_params, opts.daemon_ssl_certificate);
-  command_line::add_arg(desc_params, opts.daemon_ssl_allowed_certificates);
+  command_line::add_arg(desc_params, opts.daemon_ssl_ca_certificates);
   command_line::add_arg(desc_params, opts.daemon_ssl_allowed_fingerprints);
   command_line::add_arg(desc_params, opts.daemon_ssl_allow_any_cert);
   command_line::add_arg(desc_params, opts.testnet);
@@ -1156,7 +1145,7 @@ std::unique_ptr<wallet2> wallet2::make_dummy(const boost::program_options::varia
 //----------------------------------------------------------------------------------------------------
 bool wallet2::set_daemon(std::string daemon_address, boost::optional<epee::net_utils::http::login> daemon_login, bool trusted_daemon,
     epee::net_utils::ssl_support_t ssl_support, const std::pair<std::string, std::string> &private_key_and_certificate_path,
-    const std::list<std::string> &allowed_certificates, const std::vector<std::vector<uint8_t>> &allowed_fingerprints,
+    std::string ca_file, const std::vector<std::vector<uint8_t>> &allowed_fingerprints,
     bool allow_any_cert)
 {
   if(m_http_client.is_connected())
@@ -1166,17 +1155,17 @@ bool wallet2::set_daemon(std::string daemon_address, boost::optional<epee::net_u
   m_trusted_daemon = trusted_daemon;
 
   MINFO("setting daemon to " << get_daemon_address());
-  return m_http_client.set_server(get_daemon_address(), get_daemon_login(), ssl_support, private_key_and_certificate_path, allowed_certificates, allowed_fingerprints, allow_any_cert);
+  return m_http_client.set_server(get_daemon_address(), get_daemon_login(), ssl_support, private_key_and_certificate_path, std::move(ca_file), allowed_fingerprints, allow_any_cert);
 }
 //----------------------------------------------------------------------------------------------------
-bool wallet2::init(std::string daemon_address, boost::optional<epee::net_utils::http::login> daemon_login, boost::asio::ip::tcp::endpoint proxy, uint64_t upper_transaction_weight_limit, bool trusted_daemon, epee::net_utils::ssl_support_t ssl_support, const std::pair<std::string, std::string> &private_key_and_certificate_path, const std::list<std::string> &allowed_certificates, const std::vector<std::vector<uint8_t>> &allowed_fingerprints, bool allow_any_cert)
+bool wallet2::init(std::string daemon_address, boost::optional<epee::net_utils::http::login> daemon_login, boost::asio::ip::tcp::endpoint proxy, uint64_t upper_transaction_weight_limit, bool trusted_daemon, epee::net_utils::ssl_support_t ssl_support, const std::pair<std::string, std::string> &private_key_and_certificate_path, std::string ca_file, const std::vector<std::vector<uint8_t>> &allowed_fingerprints, bool allow_any_cert)
 {
   m_checkpoints.init_default_checkpoints(m_nettype);
   m_is_initialized = true;
   m_upper_transaction_weight_limit = upper_transaction_weight_limit;
   if (proxy != boost::asio::ip::tcp::endpoint{})
     m_http_client.set_connector(net::socks::connector{std::move(proxy)});
-  return set_daemon(daemon_address, daemon_login, trusted_daemon, ssl_support, private_key_and_certificate_path, allowed_certificates, allowed_fingerprints, allow_any_cert);
+  return set_daemon(daemon_address, daemon_login, trusted_daemon, ssl_support, private_key_and_certificate_path, std::move(ca_file), allowed_fingerprints, allow_any_cert);
 }
 //----------------------------------------------------------------------------------------------------
 bool wallet2::is_deterministic() const
diff --git a/src/wallet/wallet2.h b/src/wallet/wallet2.h
index a24127800..58dc5f082 100644
--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@@ -691,13 +691,13 @@ namespace tools
       bool trusted_daemon = true,
       epee::net_utils::ssl_support_t ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_autodetect,
       const std::pair<std::string, std::string> &private_key_and_certificate_path = {},
-      const std::list<std::string> &allowed_certificates = {}, const std::vector<std::vector<uint8_t>> &allowed_fingerprints = {},
+      std::string ca_file = {}, const std::vector<std::vector<uint8_t>> &allowed_fingerprints = {},
       bool allow_any_cert = false);
     bool set_daemon(std::string daemon_address = "http://localhost:8080",
       boost::optional<epee::net_utils::http::login> daemon_login = boost::none, bool trusted_daemon = true,
       epee::net_utils::ssl_support_t ssl_support = epee::net_utils::ssl_support_t::e_ssl_support_autodetect,
       const std::pair<std::string, std::string> &private_key_and_certificate_path = {},
-      const std::list<std::string> &allowed_certificates = {}, const std::vector<std::vector<uint8_t>> &allowed_fingerprints = {},
+      std::string ca_file = {}, const std::vector<std::vector<uint8_t>> &allowed_fingerprints = {},
       bool allow_any_cert = false);
 
     void stop() { m_run.store(false, std::memory_order_relaxed); m_message_store.stop(); }
diff --git a/src/wallet/wallet_rpc_server.cpp b/src/wallet/wallet_rpc_server.cpp
index 92265d954..7824ed62e 100644
--- a/src/wallet/wallet_rpc_server.cpp
+++ b/src/wallet/wallet_rpc_server.cpp
@@ -68,7 +68,7 @@ namespace
   const command_line::arg_descriptor<std::string> arg_rpc_ssl = {"rpc-ssl", tools::wallet2::tr("Enable SSL on wallet RPC connections: enabled|disabled|autodetect"), "autodetect"};
   const command_line::arg_descriptor<std::string> arg_rpc_ssl_private_key = {"rpc-ssl-private-key", tools::wallet2::tr("Path to a PEM format private key"), ""};
   const command_line::arg_descriptor<std::string> arg_rpc_ssl_certificate = {"rpc-ssl-certificate", tools::wallet2::tr("Path to a PEM format certificate"), ""};
-  const command_line::arg_descriptor<std::vector<std::string>> arg_rpc_ssl_allowed_certificates = {"rpc-ssl-allowed-certificates", tools::wallet2::tr("List of paths to PEM format certificates of allowed RPC servers (all allowed if empty)")};
+  const command_line::arg_descriptor<std::string> arg_rpc_ssl_ca_certificates = {"rpc-ssl-ca-certificates", tools::wallet2::tr("Path to file containing concatenated PEM format certificate(s) to replace system CA(s).")};
   const command_line::arg_descriptor<std::vector<std::string>> arg_rpc_ssl_allowed_fingerprints = {"rpc-ssl-allowed-fingerprints", tools::wallet2::tr("List of certificate fingerprints to allow")};
 
   constexpr const char default_rpc_username[] = "monero";
@@ -247,7 +247,7 @@ namespace tools
 
     auto rpc_ssl_private_key = command_line::get_arg(vm, arg_rpc_ssl_private_key);
     auto rpc_ssl_certificate = command_line::get_arg(vm, arg_rpc_ssl_certificate);
-    auto rpc_ssl_allowed_certificates = command_line::get_arg(vm, arg_rpc_ssl_allowed_certificates);
+    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;
@@ -256,16 +256,6 @@ namespace tools
       MERROR("Invalid argument for " << std::string(arg_rpc_ssl.name));
       return false;
     }
-    std::list<std::string> allowed_certificates;
-    for (const std::string &path: rpc_ssl_allowed_certificates)
-    {
-        allowed_certificates.push_back({});
-        if (!epee::file_io_utils::load_file_to_string(path, allowed_certificates.back()))
-        {
-          MERROR("Failed to load certificate: " << path);
-          allowed_certificates.back() = std::string();
-        }
-    }
 
     std::vector<std::vector<uint8_t>> allowed_fingerprints{ rpc_ssl_allowed_fingerprints.size() };
     std::transform(rpc_ssl_allowed_fingerprints.begin(), rpc_ssl_allowed_fingerprints.end(), allowed_fingerprints.begin(), epee::from_hex::vector);
@@ -277,7 +267,7 @@ namespace tools
     auto rng = [](size_t len, uint8_t *ptr) { return crypto::rand(len, ptr); };
     return epee::http_server_impl_base<wallet_rpc_server, connection_context>::init(
       rng, std::move(bind_port), std::move(rpc_config->bind_ip), std::move(rpc_config->access_control_origins), std::move(http_login),
-      rpc_ssl_support, std::make_pair(rpc_ssl_private_key, rpc_ssl_certificate), std::move(allowed_certificates), std::move(allowed_fingerprints)
+      rpc_ssl_support, std::make_pair(rpc_ssl_private_key, rpc_ssl_certificate), std::move(rpc_ssl_ca_file), std::move(allowed_fingerprints)
     );
   }
   //------------------------------------------------------------------------------------------------------------------------------
@@ -4070,7 +4060,7 @@ namespace tools
       for (auto c: fp)
         v.push_back(c);
     }
-    if (!m_wallet->set_daemon(req.address, boost::none, req.trusted, ssl_support, std::make_pair(req.ssl_private_key_path, req.ssl_certificate_path), req.ssl_allowed_certificates, ssl_allowed_fingerprints, req.ssl_allow_any_cert))
+    if (!m_wallet->set_daemon(req.address, boost::none, req.trusted, ssl_support, std::make_pair(req.ssl_private_key_path, req.ssl_certificate_path), std::move(req.ssl_ca_file), ssl_allowed_fingerprints, req.ssl_allow_any_cert))
     {
       er.code = WALLET_RPC_ERROR_CODE_NO_DAEMON_CONNECTION;
       er.message = std::string("Unable to set daemon");
@@ -4278,7 +4268,7 @@ int main(int argc, char** argv) {
   command_line::add_arg(desc_params, arg_rpc_ssl);
   command_line::add_arg(desc_params, arg_rpc_ssl_private_key);
   command_line::add_arg(desc_params, arg_rpc_ssl_certificate);
-  command_line::add_arg(desc_params, arg_rpc_ssl_allowed_certificates);
+  command_line::add_arg(desc_params, arg_rpc_ssl_ca_certificates);
   command_line::add_arg(desc_params, arg_rpc_ssl_allowed_fingerprints);
 
   daemonizer::init_options(hidden_options, desc_params);
diff --git a/src/wallet/wallet_rpc_server_commands_defs.h b/src/wallet/wallet_rpc_server_commands_defs.h
index 7984f6584..4c945ab41 100644
--- a/src/wallet/wallet_rpc_server_commands_defs.h
+++ b/src/wallet/wallet_rpc_server_commands_defs.h
@@ -2448,7 +2448,7 @@ namespace wallet_rpc
       std::string ssl_support; // disabled, enabled, autodetect
       std::string ssl_private_key_path;
       std::string ssl_certificate_path;
-      std::list<std::string> ssl_allowed_certificates;
+      std::string ssl_ca_file;
       std::vector<std::string> ssl_allowed_fingerprints;
       bool ssl_allow_any_cert;
 
@@ -2458,7 +2458,7 @@ namespace wallet_rpc
         KV_SERIALIZE_OPT(ssl_support, (std::string)"autodetect")
         KV_SERIALIZE(ssl_private_key_path)
         KV_SERIALIZE(ssl_certificate_path)
-        KV_SERIALIZE(ssl_allowed_certificates)
+        KV_SERIALIZE(ssl_ca_file)
         KV_SERIALIZE(ssl_allowed_fingerprints)
         KV_SERIALIZE_OPT(ssl_allow_any_cert, false)
       END_KV_SERIALIZE_MAP()