Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 1294 insertions, 0 deletions

diff --git a/src/crimson/mon/MonClient.cc b/src/crimson/mon/MonClient.cc
new file mode 100644
index 000000000..9dfbb103a
--- /dev/null
+++ b/src/crimson/mon/MonClient.cc
@@ -0,0 +1,1111 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "MonClient.h"
+
+#include <random>
+
+#include <seastar/core/future-util.hh>
+#include <seastar/core/lowres_clock.hh>
+#include <seastar/core/shared_future.hh>
+#include <seastar/util/log.hh>
+
+#include "auth/AuthClientHandler.h"
+#include "auth/RotatingKeyRing.h"
+
+#include "common/hostname.h"
+
+#include "crimson/auth/KeyRing.h"
+#include "crimson/common/config_proxy.h"
+#include "crimson/common/log.h"
+#include "crimson/net/Connection.h"
+#include "crimson/net/Errors.h"
+#include "crimson/net/Messenger.h"
+
+#include "messages/MAuth.h"
+#include "messages/MAuthReply.h"
+#include "messages/MConfig.h"
+#include "messages/MLogAck.h"
+#include "messages/MMonCommand.h"
+#include "messages/MMonCommandAck.h"
+#include "messages/MMonGetMap.h"
+#include "messages/MMonGetVersion.h"
+#include "messages/MMonGetVersionReply.h"
+#include "messages/MMonMap.h"
+#include "messages/MMonSubscribe.h"
+#include "messages/MMonSubscribeAck.h"
+
+namespace {
+  seastar::logger& logger()
+  {
+    return crimson::get_logger(ceph_subsys_monc);
+  }
+}
+
+namespace crimson::mon {
+
+using crimson::common::local_conf;
+
+class Connection {
+public:
+  Connection(const AuthRegistry& auth_registry,
+             crimson::net::ConnectionRef conn,
+             KeyRing* keyring);
+  enum class auth_result_t {
+    success = 0,
+    failure,
+    canceled
+  };
+  seastar::future<> handle_auth_reply(Ref<MAuthReply> m);
+  // v1
+  seastar::future<auth_result_t> authenticate_v1(
+    epoch_t epoch,
+    const EntityName& name,
+    uint32_t want_keys);
+  // v2
+  seastar::future<auth_result_t> authenticate_v2();
+  auth::AuthClient::auth_request_t
+  get_auth_request(const EntityName& name,
+                   uint32_t want_keys);
+  using secret_t = string;
+  tuple<CryptoKey, secret_t, bufferlist>
+  handle_auth_reply_more(const ceph::buffer::list& bl);
+  int handle_auth_bad_method(uint32_t old_auth_method,
+                             int result,
+                             const std::vector<uint32_t>& allowed_methods,
+                             const std::vector<uint32_t>& allowed_modes);
+
+  // v1 and v2
+  tuple<CryptoKey, secret_t, int>
+  handle_auth_done(uint64_t new_global_id,
+                   const ceph::buffer::list& bl);
+  void close();
+  bool is_my_peer(const entity_addr_t& addr) const;
+  AuthAuthorizer* get_authorizer(entity_type_t peer) const;
+  KeyStore& get_keys();
+  seastar::future<> renew_tickets();
+  seastar::future<> renew_rotating_keyring();
+
+  crimson::net::ConnectionRef get_conn();
+
+private:
+  seastar::future<> setup_session(epoch_t epoch,
+                                  const EntityName& name);
+  std::unique_ptr<AuthClientHandler> create_auth(crimson::auth::method_t,
+                                                 uint64_t global_id,
+                                                 const EntityName& name,
+                                                 uint32_t want_keys);
+  enum class request_t {
+    rotating,
+    general,
+  };
+  seastar::future<std::optional<auth_result_t>> do_auth_single(request_t);
+  seastar::future<auth_result_t> do_auth(request_t);
+
+private:
+  bool closed = false;
+  // v1
+  seastar::shared_promise<Ref<MAuthReply>> reply;
+  // v2
+  using clock_t = seastar::lowres_system_clock;
+  clock_t::time_point auth_start;
+  crimson::auth::method_t auth_method = 0;
+  std::optional<seastar::promise<auth_result_t>> auth_done;
+  // v1 and v2
+  const AuthRegistry& auth_registry;
+  crimson::net::ConnectionRef conn;
+  std::unique_ptr<AuthClientHandler> auth;
+  std::unique_ptr<RotatingKeyRing> rotating_keyring;
+  uint64_t global_id = 0;
+  clock_t::time_point last_rotating_renew_sent;
+};
+
+Connection::Connection(const AuthRegistry& auth_registry,
+                       crimson::net::ConnectionRef conn,
+                       KeyRing* keyring)
+  : auth_registry{auth_registry},
+    conn{conn},
+    rotating_keyring{
+      std::make_unique<RotatingKeyRing>(nullptr,
+                                        CEPH_ENTITY_TYPE_OSD,
+                                        keyring)}
+{}
+
+seastar::future<> Connection::handle_auth_reply(Ref<MAuthReply> m)
+{
+  reply.set_value(m);
+  reply = {};
+  return seastar::now();
+}
+
+seastar::future<> Connection::renew_tickets()
+{
+  if (auth->need_tickets()) {
+    return do_auth(request_t::general).then([](auth_result_t r) {
+      if (r != auth_result_t::success)  {
+        throw std::system_error(
+	  make_error_code(
+	    crimson::net::error::negotiation_failure));
+      }
+    });
+  }
+  return seastar::now();
+}
+
+seastar::future<> Connection::renew_rotating_keyring()
+{
+  auto now = clock_t::now();
+  auto ttl = std::chrono::seconds{
+    static_cast<long>(crimson::common::local_conf()->auth_service_ticket_ttl)};
+  auto cutoff = now - ttl / 4;
+  if (!rotating_keyring->need_new_secrets(utime_t(cutoff))) {
+    return seastar::now();
+  }
+  if (now - last_rotating_renew_sent < std::chrono::seconds{1}) {
+    logger().info("renew_rotating_keyring called too often");
+    return seastar::now();
+  }
+  last_rotating_renew_sent = now;
+  return do_auth(request_t::rotating).then([](auth_result_t r) {
+    if (r != auth_result_t::success)  {
+      throw std::system_error(make_error_code(
+        crimson::net::error::negotiation_failure));
+    }
+  });
+}
+
+AuthAuthorizer* Connection::get_authorizer(entity_type_t peer) const
+{
+  if (auth) {
+    return auth->build_authorizer(peer);
+  } else {
+    return nullptr;
+  }
+}
+
+KeyStore& Connection::get_keys() {
+  return *rotating_keyring;
+}
+
+std::unique_ptr<AuthClientHandler>
+Connection::create_auth(crimson::auth::method_t protocol,
+                        uint64_t global_id,
+                        const EntityName& name,
+                        uint32_t want_keys)
+{
+  static crimson::common::CephContext cct;
+  std::unique_ptr<AuthClientHandler> auth;
+  auth.reset(AuthClientHandler::create(&cct,
+                                       protocol,
+                                       rotating_keyring.get()));
+  if (!auth) {
+    logger().error("no handler for protocol {}", protocol);
+    throw std::system_error(make_error_code(
+      crimson::net::error::negotiation_failure));
+  }
+  auth->init(name);
+  auth->set_want_keys(want_keys);
+  auth->set_global_id(global_id);
+  return auth;
+}
+
+seastar::future<>
+Connection::setup_session(epoch_t epoch,
+                          const EntityName& name)
+{
+  auto m = ceph::make_message<MAuth>();
+  m->protocol = CEPH_AUTH_UNKNOWN;
+  m->monmap_epoch = epoch;
+  __u8 struct_v = 1;
+  encode(struct_v, m->auth_payload);
+  std::vector<crimson::auth::method_t> auth_methods;
+  auth_registry.get_supported_methods(conn->get_peer_type(), &auth_methods);
+  encode(auth_methods, m->auth_payload);
+  encode(name, m->auth_payload);
+  encode(global_id, m->auth_payload);
+  return conn->send(m);
+}
+
+seastar::future<std::optional<Connection::auth_result_t>>
+Connection::do_auth_single(Connection::request_t what)
+{
+  auto m = make_message<MAuth>();
+  m->protocol = auth->get_protocol();
+  auth->prepare_build_request();
+  switch (what) {
+  case request_t::rotating:
+    auth->build_rotating_request(m->auth_payload);
+    break;
+  case request_t::general:
+    if (int ret = auth->build_request(m->auth_payload); ret) {
+      logger().error("missing/bad key for '{}'", local_conf()->name);
+      throw std::system_error(make_error_code(
+        crimson::net::error::negotiation_failure));
+    }
+    break;
+  default:
+    assert(0);
+  }
+  logger().info("sending {}", *m);
+  return conn->send(m).then([this] {
+    logger().info("waiting");
+    return reply.get_shared_future();
+  }).then([this] (Ref<MAuthReply> m) {
+    if (!m) {
+      ceph_assert(closed);
+      logger().info("do_auth: connection closed");
+      return seastar::make_ready_future<std::optional<Connection::auth_result_t>>(
+	std::make_optional(auth_result_t::canceled));
+    }
+    logger().info(
+      "do_auth: mon {} => {} returns {}: {}",
+      conn->get_messenger()->get_myaddr(),
+      conn->get_peer_addr(), *m, m->result);
+    auto p = m->result_bl.cbegin();
+    auto ret = auth->handle_response(m->result, p,
+				     nullptr, nullptr);
+    if (ret != 0 && ret != -EAGAIN) {
+      logger().error(
+	"do_auth: got error {} on mon {}",
+	ret,
+	conn->get_peer_addr());
+    }
+    return seastar::make_ready_future<std::optional<Connection::auth_result_t>>(
+      ret == -EAGAIN
+      ? std::nullopt
+      : std::make_optional(ret == 0
+	 ? auth_result_t::success
+	 : auth_result_t::failure
+      ));
+  });
+}
+
+seastar::future<Connection::auth_result_t>
+Connection::do_auth(Connection::request_t what) {
+  return seastar::repeat_until_value([this, what]() {
+    return do_auth_single(what);
+  });
+}
+
+seastar::future<Connection::auth_result_t>
+Connection::authenticate_v1(epoch_t epoch,
+                            const EntityName& name,
+                            uint32_t want_keys)
+{
+  return conn->keepalive().then([epoch, name, this] {
+    return setup_session(epoch, name);
+  }).then([this] {
+    return reply.get_shared_future();
+  }).then([name, want_keys, this](Ref<MAuthReply> m) {
+    if (!m) {
+      logger().error("authenticate_v1 canceled on {}", name);
+      return seastar::make_ready_future<auth_result_t>(auth_result_t::canceled);
+    }
+    global_id = m->global_id;
+    auth = create_auth(m->protocol, m->global_id, name, want_keys);
+    switch (auto p = m->result_bl.cbegin();
+            auth->handle_response(m->result, p,
+				  nullptr, nullptr)) {
+    case 0:
+      // none
+      return seastar::make_ready_future<auth_result_t>(auth_result_t::success);
+    case -EAGAIN:
+      // cephx
+      return do_auth(request_t::general);
+    default:
+      ceph_assert_always(0);
+    }
+  }).handle_exception([](auto ep) {
+    logger().error("authenticate_v1 failed with {}", ep);
+    return seastar::make_ready_future<auth_result_t>(auth_result_t::canceled);
+  });
+}
+
+seastar::future<Connection::auth_result_t> Connection::authenticate_v2()
+{
+  auth_start = seastar::lowres_system_clock::now();
+  return conn->send(make_message<MMonGetMap>()).then([this] {
+    auth_done.emplace();
+    return auth_done->get_future();
+  });
+}
+
+auth::AuthClient::auth_request_t
+Connection::get_auth_request(const EntityName& entity_name,
+                             uint32_t want_keys)
+{
+  // choose method
+  auth_method = [&] {
+    std::vector<crimson::auth::method_t> methods;
+    auth_registry.get_supported_methods(conn->get_peer_type(), &methods);
+    if (methods.empty()) {
+      logger().info("get_auth_request no methods is supported");
+      throw crimson::auth::error("no methods is supported");
+    }
+    return methods.front();
+  }();
+
+  std::vector<uint32_t> modes;
+  auth_registry.get_supported_modes(conn->get_peer_type(), auth_method,
+                                    &modes);
+  logger().info("method {} preferred_modes {}", auth_method, modes);
+  if (modes.empty()) {
+    throw crimson::auth::error("no modes is supported");
+  }
+  auth = create_auth(auth_method, global_id, entity_name, want_keys);
+
+  using ceph::encode;
+  bufferlist bl;
+  // initial request includes some boilerplate...
+  encode((char)AUTH_MODE_MON, bl);
+  encode(entity_name, bl);
+  encode(global_id, bl);
+  // and (maybe) some method-specific initial payload
+  auth->build_initial_request(&bl);
+  return {auth_method, modes, bl};
+}
+
+tuple<CryptoKey, Connection::secret_t, bufferlist>
+Connection::handle_auth_reply_more(const ceph::buffer::list& payload)
+{
+  CryptoKey session_key;
+  secret_t connection_secret;
+  bufferlist reply;
+  auto p = payload.cbegin();
+  int r = auth->handle_response(0, p, &session_key,	&connection_secret);
+  if (r == -EAGAIN) {
+    auth->prepare_build_request();
+    auth->build_request(reply);
+    logger().info(" responding with {} bytes", reply.length());
+    return {session_key, connection_secret, reply};
+  } else if (r < 0) {
+    logger().error(" handle_response returned {}",  r);
+    throw crimson::auth::error("unable to build auth");
+  } else {
+    logger().info("authenticated!");
+    std::terminate();
+  }
+}
+
+tuple<CryptoKey, Connection::secret_t, int>
+Connection::handle_auth_done(uint64_t new_global_id,
+                             const ceph::buffer::list& payload)
+{
+  global_id = new_global_id;
+  auth->set_global_id(global_id);
+  auto p = payload.begin();
+  CryptoKey session_key;
+  secret_t connection_secret;
+  int r = auth->handle_response(0, p, &session_key, &connection_secret);
+  conn->set_last_keepalive_ack(auth_start);
+  if (auth_done) {
+    auth_done->set_value(auth_result_t::success);
+    auth_done.reset();
+  }
+  return {session_key, connection_secret, r};
+}
+
+int Connection::handle_auth_bad_method(uint32_t old_auth_method,
+                                       int result,
+                                       const std::vector<uint32_t>& allowed_methods,
+                                       const std::vector<uint32_t>& allowed_modes)
+{
+  logger().info("old_auth_method {} result {} allowed_methods {}",
+                old_auth_method, cpp_strerror(result), allowed_methods);
+  std::vector<uint32_t> auth_supported;
+  auth_registry.get_supported_methods(conn->get_peer_type(), &auth_supported);
+  auto p = std::find(auth_supported.begin(), auth_supported.end(),
+                     old_auth_method);
+  assert(p != auth_supported.end());
+  p = std::find_first_of(std::next(p), auth_supported.end(),
+                         allowed_methods.begin(), allowed_methods.end());
+  if (p == auth_supported.end()) {
+    logger().error("server allowed_methods {} but i only support {}",
+                   allowed_methods, auth_supported);
+    assert(auth_done);
+    auth_done->set_exception(std::system_error(make_error_code(
+      crimson::net::error::negotiation_failure)));
+    return -EACCES;
+  }
+  auth_method = *p;
+  logger().info("will try {} next", auth_method);
+  return 0;
+}
+
+void Connection::close()
+{
+  reply.set_value(Ref<MAuthReply>(nullptr));
+  reply = {};
+  if (auth_done) {
+    auth_done->set_value(auth_result_t::canceled);
+    auth_done.reset();
+  }
+  if (conn && !std::exchange(closed, true)) {
+    conn->mark_down();
+  }
+}
+
+bool Connection::is_my_peer(const entity_addr_t& addr) const
+{
+  ceph_assert(conn);
+  return conn->get_peer_addr() == addr;
+}
+
+crimson::net::ConnectionRef Connection::get_conn() {
+  return conn;
+}
+
+Client::Client(crimson::net::Messenger& messenger,
+               crimson::common::AuthHandler& auth_handler)
+  // currently, crimson is OSD-only
+  : want_keys{CEPH_ENTITY_TYPE_MON |
+              CEPH_ENTITY_TYPE_OSD |
+              CEPH_ENTITY_TYPE_MGR},
+    timer{[this] { tick(); }},
+    msgr{messenger},
+    auth_registry{&cct},
+    auth_handler{auth_handler}
+{}
+
+Client::Client(Client&&) = default;
+Client::~Client() = default;
+
+seastar::future<> Client::start() {
+  entity_name = crimson::common::local_conf()->name;
+  auth_registry.refresh_config();
+  return load_keyring().then([this] {
+    return monmap.build_initial(crimson::common::local_conf(), false);
+  }).then([this] {
+    return authenticate();
+  }).then([this] {
+    auto interval =
+      std::chrono::duration_cast<seastar::lowres_clock::duration>(
+        std::chrono::duration<double>(
+          local_conf().get_val<double>("mon_client_ping_interval")));
+    timer.arm_periodic(interval);
+  });
+}
+
+seastar::future<> Client::load_keyring()
+{
+  if (!auth_registry.is_supported_method(msgr.get_mytype(), CEPH_AUTH_CEPHX)) {
+    return seastar::now();
+  } else {
+    return crimson::auth::load_from_keyring(&keyring).then([](KeyRing* keyring) {
+      return crimson::auth::load_from_keyfile(keyring);
+    }).then([](KeyRing* keyring) {
+      return crimson::auth::load_from_key(keyring);
+    }).then([](KeyRing*) {
+      return seastar::now();
+    });
+  }
+}
+
+void Client::tick()
+{
+  gate.dispatch_in_background(__func__, *this, [this] {
+    if (active_con) {
+      return seastar::when_all_succeed(active_con->get_conn()->keepalive(),
+                                       active_con->renew_tickets(),
+                                       active_con->renew_rotating_keyring()).then_unpack([] {});
+    } else {
+      return seastar::now();
+    }
+  });
+}
+
+bool Client::is_hunting() const {
+  return !active_con;
+}
+
+std::optional<seastar::future<>>
+Client::ms_dispatch(crimson::net::ConnectionRef conn, MessageRef m)
+{
+  bool dispatched = true;
+  gate.dispatch_in_background(__func__, *this, [this, conn, &m, &dispatched] {
+    // we only care about these message types
+    switch (m->get_type()) {
+    case CEPH_MSG_MON_MAP:
+      return handle_monmap(conn, boost::static_pointer_cast<MMonMap>(m));
+    case CEPH_MSG_AUTH_REPLY:
+      return handle_auth_reply(
+	conn, boost::static_pointer_cast<MAuthReply>(m));
+    case CEPH_MSG_MON_SUBSCRIBE_ACK:
+      return handle_subscribe_ack(
+	boost::static_pointer_cast<MMonSubscribeAck>(m));
+    case CEPH_MSG_MON_GET_VERSION_REPLY:
+      return handle_get_version_reply(
+	boost::static_pointer_cast<MMonGetVersionReply>(m));
+    case MSG_MON_COMMAND_ACK:
+      return handle_mon_command_ack(
+	boost::static_pointer_cast<MMonCommandAck>(m));
+    case MSG_LOGACK:
+      return handle_log_ack(
+	boost::static_pointer_cast<MLogAck>(m));
+    case MSG_CONFIG:
+      return handle_config(
+	boost::static_pointer_cast<MConfig>(m));
+    default:
+      dispatched = false;
+      return seastar::now();
+    }
+  });
+  return (dispatched ? std::make_optional(seastar::now()) : std::nullopt);
+}
+
+void Client::ms_handle_reset(crimson::net::ConnectionRef conn, bool /* is_replace */)
+{
+  gate.dispatch_in_background(__func__, *this, [this, conn] {
+    auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+			      [peer_addr = conn->get_peer_addr()](auto& mc) {
+				return mc->is_my_peer(peer_addr);
+			      });
+    if (found != pending_conns.end()) {
+      logger().warn("pending conn reset by {}", conn->get_peer_addr());
+      (*found)->close();
+      return seastar::now();
+    } else if (active_con && active_con->is_my_peer(conn->get_peer_addr())) {
+      logger().warn("active conn reset {}", conn->get_peer_addr());
+      active_con.reset();
+      return reopen_session(-1).then([this] {
+	send_pendings();
+	return seastar::now();
+      });
+    } else {
+      return seastar::now();
+    }
+  });
+}
+
+std::pair<std::vector<uint32_t>, std::vector<uint32_t>>
+Client::get_supported_auth_methods(int peer_type)
+{
+    std::vector<uint32_t> methods;
+    std::vector<uint32_t> modes;
+    auth_registry.get_supported_methods(peer_type, &methods, &modes);
+    return {methods, modes};
+}
+
+uint32_t Client::pick_con_mode(int peer_type,
+                               uint32_t auth_method,
+                               const std::vector<uint32_t>& preferred_modes)
+{
+  return auth_registry.pick_mode(peer_type, auth_method, preferred_modes);
+}
+
+AuthAuthorizeHandler* Client::get_auth_authorize_handler(int peer_type,
+                                                         int auth_method)
+{
+  return auth_registry.get_handler(peer_type, auth_method);
+}
+
+
+int Client::handle_auth_request(crimson::net::ConnectionRef con,
+                                AuthConnectionMetaRef auth_meta,
+                                bool more,
+                                uint32_t auth_method,
+                                const ceph::bufferlist& payload,
+                                ceph::bufferlist *reply)
+{
+  // for some channels prior to nautilus (osd heartbeat), we tolerate the lack of
+  // an authorizer.
+  if (payload.length() == 0) {
+    if (con->get_messenger()->get_require_authorizer()) {
+      return -EACCES;
+    } else {
+      auth_handler.handle_authentication({}, {});
+      return 1;
+    }
+  }
+  auth_meta->auth_mode = payload[0];
+  if (auth_meta->auth_mode < AUTH_MODE_AUTHORIZER ||
+      auth_meta->auth_mode > AUTH_MODE_AUTHORIZER_MAX) {
+    return -EACCES;
+  }
+  AuthAuthorizeHandler* ah = get_auth_authorize_handler(con->get_peer_type(),
+                                                        auth_method);
+  if (!ah) {
+    logger().error("no AuthAuthorizeHandler found for auth method: {}",
+                   auth_method);
+    return -EOPNOTSUPP;
+  }
+  auto authorizer_challenge = &auth_meta->authorizer_challenge;
+  if (auth_meta->skip_authorizer_challenge) {
+    logger().info("skipping challenge on {}", con);
+    authorizer_challenge = nullptr;
+  }
+  bool was_challenge = (bool)auth_meta->authorizer_challenge;
+  EntityName name;
+  AuthCapsInfo caps_info;
+  bool is_valid = ah->verify_authorizer(
+    &cct,
+    active_con->get_keys(),
+    payload,
+    auth_meta->get_connection_secret_length(),
+    reply,
+    &name,
+    &active_con->get_conn()->peer_global_id,
+    &caps_info,
+    &auth_meta->session_key,
+    &auth_meta->connection_secret,
+    authorizer_challenge);
+  if (is_valid) {
+    auth_handler.handle_authentication(name, caps_info);
+    return 1;
+  }
+  if (!more && !was_challenge && auth_meta->authorizer_challenge) {
+    logger().info("added challenge on {}", con);
+    return 0;
+  } else {
+    logger().info("bad authorizer on {}", con);
+    return -EACCES;
+  }
+}
+
+auth::AuthClient::auth_request_t
+Client::get_auth_request(crimson::net::ConnectionRef con,
+                         AuthConnectionMetaRef auth_meta)
+{
+  logger().info("get_auth_request(con={}, auth_method={})",
+                con, auth_meta->auth_method);
+  // connection to mon?
+  if (con->get_peer_type() == CEPH_ENTITY_TYPE_MON) {
+    auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+                              [peer_addr = con->get_peer_addr()](auto& mc) {
+                                return mc->is_my_peer(peer_addr);
+                              });
+    if (found == pending_conns.end()) {
+      throw crimson::auth::error{"unknown connection"};
+    }
+    return (*found)->get_auth_request(entity_name, want_keys);
+  } else {
+    // generate authorizer
+    if (!active_con) {
+      logger().error(" but no auth handler is set up");
+      throw crimson::auth::error("no auth available");
+    }
+    auto authorizer = active_con->get_authorizer(con->get_peer_type());
+    if (!authorizer) {
+      logger().error("failed to build_authorizer for type {}",
+                     ceph_entity_type_name(con->get_peer_type()));
+      throw crimson::auth::error("unable to build auth");
+    }
+    auth_meta->authorizer.reset(authorizer);
+    auth_meta->auth_method = authorizer->protocol;
+    vector<uint32_t> modes;
+    auth_registry.get_supported_modes(con->get_peer_type(),
+                                      auth_meta->auth_method,
+                                      &modes);
+    return {authorizer->protocol, modes, authorizer->bl};
+  }
+}
+
+ceph::bufferlist Client::handle_auth_reply_more(crimson::net::ConnectionRef conn,
+                                                AuthConnectionMetaRef auth_meta,
+                                                const bufferlist& bl)
+{
+  if (conn->get_peer_type() == CEPH_ENTITY_TYPE_MON) {
+    auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+                              [peer_addr = conn->get_peer_addr()](auto& mc) {
+                                return mc->is_my_peer(peer_addr);
+                              });
+    if (found == pending_conns.end()) {
+      throw crimson::auth::error{"unknown connection"};
+    }
+    bufferlist reply;
+    tie(auth_meta->session_key, auth_meta->connection_secret, reply) =
+      (*found)->handle_auth_reply_more(bl);
+    return reply;
+  } else {
+    // authorizer challenges
+    if (!active_con || !auth_meta->authorizer) {
+      logger().error("no authorizer?");
+      throw crimson::auth::error("no auth available");
+    }
+    auth_meta->authorizer->add_challenge(&cct, bl);
+    return auth_meta->authorizer->bl;
+  }
+}
+
+int Client::handle_auth_done(crimson::net::ConnectionRef conn,
+                             AuthConnectionMetaRef auth_meta,
+                             uint64_t global_id,
+                             uint32_t con_mode,
+                             const bufferlist& bl)
+{
+  if (conn->get_peer_type() == CEPH_ENTITY_TYPE_MON) {
+    auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+                              [peer_addr = conn->get_peer_addr()](auto& mc) {
+                                return mc->is_my_peer(peer_addr);
+                              });
+    if (found == pending_conns.end()) {
+      return -ENOENT;
+    }
+    int r = 0;
+    tie(auth_meta->session_key, auth_meta->connection_secret, r) =
+      (*found)->handle_auth_done(global_id, bl);
+    return r;
+  } else {
+    // verify authorizer reply
+    auto p = bl.begin();
+    if (!auth_meta->authorizer->verify_reply(p, &auth_meta->connection_secret)) {
+      logger().error("failed verifying authorizer reply");
+      return -EACCES;
+    }
+    auth_meta->session_key = auth_meta->authorizer->session_key;
+    return 0;
+  }
+}
+
+ // Handle server's indication that the previous auth attempt failed
+int Client::handle_auth_bad_method(crimson::net::ConnectionRef conn,
+                                   AuthConnectionMetaRef auth_meta,
+                                   uint32_t old_auth_method,
+                                   int result,
+                                   const std::vector<uint32_t>& allowed_methods,
+                                   const std::vector<uint32_t>& allowed_modes)
+{
+  if (conn->get_peer_type() == CEPH_ENTITY_TYPE_MON) {
+    auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+                              [peer_addr = conn->get_peer_addr()](auto& mc) {
+                                return mc->is_my_peer(peer_addr);
+                              });
+    if (found != pending_conns.end()) {
+      return (*found)->handle_auth_bad_method(
+	old_auth_method, result,
+	allowed_methods, allowed_modes);
+    } else {
+      return -ENOENT;
+    }
+  } else {
+    // huh...
+    logger().info("hmm, they didn't like {} result {}",
+                  old_auth_method, cpp_strerror(result));
+    return -EACCES;
+  }
+}
+
+seastar::future<> Client::handle_monmap(crimson::net::ConnectionRef conn,
+                                        Ref<MMonMap> m)
+{
+  monmap.decode(m->monmapbl);
+  const auto peer_addr = conn->get_peer_addr();
+  auto cur_mon = monmap.get_name(peer_addr);
+  logger().info("got monmap {}, mon.{}, is now rank {}",
+                 monmap.epoch, cur_mon, monmap.get_rank(cur_mon));
+  sub.got("monmap", monmap.get_epoch());
+
+  if (monmap.get_addr_name(peer_addr, cur_mon)) {
+    if (active_con) {
+      logger().info("handle_monmap: renewing tickets");
+      return seastar::when_all_succeed(
+	active_con->renew_tickets(),
+	active_con->renew_rotating_keyring()).then_unpack([](){
+	  logger().info("handle_mon_map: renewed tickets");
+	});
+    } else {
+      return seastar::now();
+    }
+  } else {
+    logger().warn("mon.{} went away", cur_mon);
+    return reopen_session(-1).then([this] {
+      send_pendings();
+      return seastar::now();
+    });
+  }
+}
+
+seastar::future<> Client::handle_auth_reply(crimson::net::ConnectionRef conn,
+                                            Ref<MAuthReply> m)
+{
+  logger().info(
+    "handle_auth_reply mon {} => {} returns {}: {}",
+    conn->get_messenger()->get_myaddr(),
+    conn->get_peer_addr(), *m, m->result);
+  auto found = std::find_if(pending_conns.begin(), pending_conns.end(),
+                            [peer_addr = conn->get_peer_addr()](auto& mc) {
+                              return mc->is_my_peer(peer_addr);
+                            });
+  if (found != pending_conns.end()) {
+    return (*found)->handle_auth_reply(m);
+  } else if (active_con) {
+    return active_con->handle_auth_reply(m);
+  } else {
+    logger().error("unknown auth reply from {}", conn->get_peer_addr());
+    return seastar::now();
+  }
+}
+
+seastar::future<> Client::handle_subscribe_ack(Ref<MMonSubscribeAck> m)
+{
+  sub.acked(m->interval);
+  return seastar::now();
+}
+
+Client::get_version_t Client::get_version(const std::string& map)
+{
+  auto m = make_message<MMonGetVersion>();
+  auto tid = ++last_version_req_id;
+  m->handle = tid;
+  m->what = map;
+  auto& req = version_reqs[tid];
+  return send_message(m).then([&req] {
+    return req.get_future();
+  });
+}
+
+seastar::future<>
+Client::handle_get_version_reply(Ref<MMonGetVersionReply> m)
+{
+  if (auto found = version_reqs.find(m->handle);
+      found != version_reqs.end()) {
+    auto& result = found->second;
+    logger().trace("{}: {} returns {}",
+                 __func__, m->handle, m->version);
+    result.set_value(std::make_tuple(m->version, m->oldest_version));
+    version_reqs.erase(found);
+  } else {
+    logger().warn("{}: version request with handle {} not found",
+                __func__, m->handle);
+  }
+  return seastar::now();
+}
+
+seastar::future<> Client::handle_mon_command_ack(Ref<MMonCommandAck> m)
+{
+  const auto tid = m->get_tid();
+  if (auto found = mon_commands.find(tid);
+      found != mon_commands.end()) {
+    auto& result = found->second;
+    logger().trace("{} {}", __func__, tid);
+    result.set_value(std::make_tuple(m->r, m->rs, std::move(m->get_data())));
+    mon_commands.erase(found);
+  } else {
+    logger().warn("{} {} not found", __func__, tid);
+  }
+  return seastar::now();
+}
+
+seastar::future<> Client::handle_log_ack(Ref<MLogAck> m)
+{
+  // XXX
+  return seastar::now();
+}
+
+seastar::future<> Client::handle_config(Ref<MConfig> m)
+{
+  return crimson::common::local_conf().set_mon_vals(m->config);
+}
+
+std::vector<unsigned> Client::get_random_mons(unsigned n) const
+{
+  uint16_t min_priority = std::numeric_limits<uint16_t>::max();
+  for (const auto& m : monmap.mon_info) {
+    if (m.second.priority < min_priority) {
+      min_priority = m.second.priority;
+    }
+  }
+  vector<unsigned> ranks;
+  for (auto [name, info] : monmap.mon_info) {
+    if (info.priority == min_priority) {
+      ranks.push_back(monmap.get_rank(name));
+    }
+  }
+  std::random_device rd;
+  std::default_random_engine rng{rd()};
+  std::shuffle(ranks.begin(), ranks.end(), rng);
+  if (n == 0 || n > ranks.size()) {
+    return ranks;
+  } else {
+    return {ranks.begin(), ranks.begin() + n};
+  }
+}
+
+seastar::future<> Client::authenticate()
+{
+  return reopen_session(-1).then([this] {
+    send_pendings();
+    return seastar::now();
+  });
+}
+
+seastar::future<> Client::stop()
+{
+  logger().info("{}", __func__);
+  auto fut = gate.close();
+  timer.cancel();
+  for (auto& pending_con : pending_conns) {
+    pending_con->close();
+  }
+  if (active_con) {
+    active_con->close();
+  }
+  return fut;
+}
+
+seastar::future<> Client::reopen_session(int rank)
+{
+  logger().info("{} to mon.{}", __func__, rank);
+  vector<unsigned> mons;
+  if (rank >= 0) {
+    mons.push_back(rank);
+  } else {
+    const auto parallel =
+      crimson::common::local_conf().get_val<uint64_t>("mon_client_hunt_parallel");
+    mons = get_random_mons(parallel);
+  }
+  pending_conns.reserve(mons.size());
+  return seastar::parallel_for_each(mons, [this](auto rank) {
+    // TODO: connect to multiple addrs
+    auto peer = monmap.get_addrs(rank).pick_addr(msgr.get_myaddr().get_type());
+    if (peer == entity_addr_t{}) {
+      // crimson msgr only uses the first bound addr
+      logger().warn("mon.{} does not have an addr compatible with me", rank);
+      return seastar::now();
+    }
+    logger().info("connecting to mon.{}", rank);
+    return seastar::futurize_invoke(
+        [peer, this] () -> seastar::future<Connection::auth_result_t> {
+      auto conn = msgr.connect(peer, CEPH_ENTITY_TYPE_MON);
+      auto& mc = pending_conns.emplace_back(
+	std::make_unique<Connection>(auth_registry, conn, &keyring));
+      if (conn->get_peer_addr().is_msgr2()) {
+        return mc->authenticate_v2();
+      } else {
+        return mc->authenticate_v1(monmap.get_epoch(), entity_name, want_keys)
+          .handle_exception([conn](auto ep) {
+            conn->mark_down();
+            return seastar::make_exception_future<Connection::auth_result_t>(ep);
+          });
+      }
+    }).then([peer, this](auto result) {
+      if (result == Connection::auth_result_t::success) {
+        _finish_auth(peer);
+      }
+      logger().debug("reopen_session mon connection attempts complete");
+    }).handle_exception([](auto ep) {
+      logger().error("mon connections failed with ep {}", ep);
+      return seastar::make_exception_future(ep);
+    });
+  }).then([this] {
+    if (!active_con) {
+      return seastar::make_exception_future(
+	  crimson::common::system_shutdown_exception());
+    }
+    return active_con->renew_rotating_keyring();
+  });
+}
+
+void Client::_finish_auth(const entity_addr_t& peer)
+{
+  if (!is_hunting()) {
+    return;
+  }
+  logger().info("found mon.{}", monmap.get_name(peer));
+
+  auto found = std::find_if(
+    pending_conns.begin(), pending_conns.end(),
+    [peer](auto& conn) {
+      return conn->is_my_peer(peer);
+  });
+  if (found == pending_conns.end()) {
+    // Happens if another connection has won the race
+    ceph_assert(active_con && pending_conns.empty());
+    logger().info("no pending connection for mon.{}, peer {}",
+      monmap.get_name(peer), peer);
+    return;
+  }
+
+  ceph_assert(!active_con && !pending_conns.empty());
+  active_con = std::move(*found);
+  found->reset();
+  for (auto& conn : pending_conns) {
+    if (conn) {
+      conn->close();
+    }
+  }
+  pending_conns.clear();
+}
+
+Client::command_result_t
+Client::run_command(const std::vector<std::string>& cmd,
+                    const bufferlist& bl)
+{
+  auto m = make_message<MMonCommand>(monmap.fsid);
+  auto tid = ++last_mon_command_id;
+  m->set_tid(tid);
+  m->cmd = cmd;
+  m->set_data(bl);
+  auto& req = mon_commands[tid];
+  return send_message(m).then([&req] {
+    return req.get_future();
+  });
+}
+
+seastar::future<> Client::send_message(MessageRef m)
+{
+  if (active_con) {
+    if (!pending_messages.empty()) {
+      send_pendings();
+    }
+    return active_con->get_conn()->send(m);
+  }
+  auto& delayed = pending_messages.emplace_back(m);
+  return delayed.pr.get_future();
+}
+
+void Client::send_pendings()
+{
+  if (active_con) {
+    for (auto& m : pending_messages) {
+      (void) active_con->get_conn()->send(m.msg);
+      m.pr.set_value();
+    }
+    pending_messages.clear();
+  }
+}
+
+bool Client::sub_want(const std::string& what, version_t start, unsigned flags)
+{
+  return sub.want(what, start, flags);
+}
+
+void Client::sub_got(const std::string& what, version_t have)
+{
+  sub.got(what, have);
+}
+
+void Client::sub_unwant(const std::string& what)
+{
+  sub.unwant(what);
+}
+
+bool Client::sub_want_increment(const std::string& what,
+                                version_t start,
+                                unsigned flags)
+{
+  return sub.inc_want(what, start, flags);
+}
+
+seastar::future<> Client::renew_subs()
+{
+  if (!sub.have_new()) {
+    logger().warn("{} - empty", __func__);
+    return seastar::now();
+  }
+  logger().trace("{}", __func__);
+
+  auto m = make_message<MMonSubscribe>();
+  m->what = sub.get_subs();
+  m->hostname = ceph_get_short_hostname();
+  return send_message(m).then([this] {
+    sub.renewed();
+  });
+}
+
+void Client::print(std::ostream& out) const
+{
+  out << "mon." << entity_name;
+}
+
+} // namespace crimson::mon
diff --git a/src/crimson/mon/MonClient.h b/src/crimson/mon/MonClient.h
new file mode 100644
index 000000000..e7d2df863
--- /dev/null
+++ b/src/crimson/mon/MonClient.h
@@ -0,0 +1,183 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#pragma once
+
+#include <memory>
+
+#include <seastar/core/future.hh>
+#include <seastar/core/gate.hh>
+#include <seastar/core/lowres_clock.hh>
+#include <seastar/core/timer.hh>
+
+#include "auth/AuthRegistry.h"
+#include "auth/KeyRing.h"
+#include "common/ceph_context.h"
+
+#include "crimson/auth/AuthClient.h"
+#include "crimson/auth/AuthServer.h"
+#include "crimson/common/auth_handler.h"
+#include "crimson/common/gated.h"
+#include "crimson/net/Dispatcher.h"
+#include "crimson/net/Fwd.h"
+
+#include "mon/MonMap.h"
+
+#include "mon/MonSub.h"
+
+template<typename Message> using Ref = boost::intrusive_ptr<Message>;
+namespace crimson::net {
+  class Messenger;
+}
+
+struct AuthAuthorizeHandler;
+class MAuthReply;
+struct MMonMap;
+struct MMonSubscribeAck;
+struct MMonGetVersionReply;
+struct MMonCommandAck;
+struct MLogAck;
+struct MConfig;
+
+namespace crimson::mon {
+
+class Connection;
+
+class Client : public crimson::net::Dispatcher,
+	       public crimson::auth::AuthClient,
+	       public crimson::auth::AuthServer
+{
+  EntityName entity_name;
+  KeyRing keyring;
+  const uint32_t want_keys;
+
+  MonMap monmap;
+  std::unique_ptr<Connection> active_con;
+  std::vector<std::unique_ptr<Connection>> pending_conns;
+  seastar::timer<seastar::lowres_clock> timer;
+
+  crimson::net::Messenger& msgr;
+
+  // commands
+  using get_version_t = seastar::future<std::tuple<version_t, version_t>>;
+
+  ceph_tid_t last_version_req_id = 0;
+  std::map<ceph_tid_t, typename get_version_t::promise_type> version_reqs;
+
+  ceph_tid_t last_mon_command_id = 0;
+  using command_result_t =
+    seastar::future<std::tuple<std::int32_t, string, ceph::bufferlist>>;
+  std::map<ceph_tid_t, typename command_result_t::promise_type> mon_commands;
+
+  MonSub sub;
+
+public:
+  Client(crimson::net::Messenger&, crimson::common::AuthHandler&);
+  Client(Client&&);
+  ~Client();
+  seastar::future<> start();
+  seastar::future<> stop();
+
+  const uuid_d& get_fsid() const {
+    return monmap.fsid;
+  }
+  get_version_t get_version(const std::string& map);
+  command_result_t run_command(const std::vector<std::string>& cmd,
+			       const bufferlist& bl);
+  seastar::future<> send_message(MessageRef);
+  bool sub_want(const std::string& what, version_t start, unsigned flags);
+  void sub_got(const std::string& what, version_t have);
+  void sub_unwant(const std::string& what);
+  bool sub_want_increment(const std::string& what, version_t start, unsigned flags);
+  seastar::future<> renew_subs();
+
+  void print(std::ostream&) const;
+private:
+  // AuthServer methods
+  std::pair<std::vector<uint32_t>, std::vector<uint32_t>>
+  get_supported_auth_methods(int peer_type) final;
+  uint32_t pick_con_mode(int peer_type,
+			 uint32_t auth_method,
+			 const std::vector<uint32_t>& preferred_modes) final;
+  AuthAuthorizeHandler* get_auth_authorize_handler(int peer_type,
+						   int auth_method) final;
+  int handle_auth_request(crimson::net::ConnectionRef conn,
+			  AuthConnectionMetaRef auth_meta,
+			  bool more,
+			  uint32_t auth_method,
+			  const ceph::bufferlist& payload,
+			  ceph::bufferlist *reply) final;
+
+  crimson::common::CephContext cct; // for auth_registry
+  AuthRegistry auth_registry;
+  crimson::common::AuthHandler& auth_handler;
+
+  // AuthClient methods
+  crimson::auth::AuthClient::auth_request_t
+  get_auth_request(crimson::net::ConnectionRef conn,
+		   AuthConnectionMetaRef auth_meta) final;
+
+   // Handle server's request to continue the handshake
+  ceph::bufferlist handle_auth_reply_more(crimson::net::ConnectionRef conn,
+					  AuthConnectionMetaRef auth_meta,
+					  const bufferlist& bl) final;
+
+   // Handle server's indication that authentication succeeded
+  int handle_auth_done(crimson::net::ConnectionRef conn,
+		       AuthConnectionMetaRef auth_meta,
+		       uint64_t global_id,
+		       uint32_t con_mode,
+		       const bufferlist& bl) final;
+
+   // Handle server's indication that the previous auth attempt failed
+  int handle_auth_bad_method(crimson::net::ConnectionRef conn,
+			     AuthConnectionMetaRef auth_meta,
+			     uint32_t old_auth_method,
+			     int result,
+			     const std::vector<uint32_t>& allowed_methods,
+			     const std::vector<uint32_t>& allowed_modes) final;
+
+private:
+  void tick();
+
+  std::optional<seastar::future<>> ms_dispatch(crimson::net::ConnectionRef conn,
+                                               MessageRef m) override;
+  void ms_handle_reset(crimson::net::ConnectionRef conn, bool is_replace) override;
+
+  seastar::future<> handle_monmap(crimson::net::ConnectionRef conn,
+				  Ref<MMonMap> m);
+  seastar::future<> handle_auth_reply(crimson::net::ConnectionRef conn,
+				      Ref<MAuthReply> m);
+  seastar::future<> handle_subscribe_ack(Ref<MMonSubscribeAck> m);
+  seastar::future<> handle_get_version_reply(Ref<MMonGetVersionReply> m);
+  seastar::future<> handle_mon_command_ack(Ref<MMonCommandAck> m);
+  seastar::future<> handle_log_ack(Ref<MLogAck> m);
+  seastar::future<> handle_config(Ref<MConfig> m);
+
+  void send_pendings();
+private:
+  seastar::future<> load_keyring();
+  seastar::future<> authenticate();
+
+  bool is_hunting() const;
+  seastar::future<> reopen_session(int rank);
+  std::vector<unsigned> get_random_mons(unsigned n) const;
+  seastar::future<> _add_conn(unsigned rank, uint64_t global_id);
+  void _finish_auth(const entity_addr_t& peer);
+  crimson::common::Gated gate;
+
+  // messages that are waiting for the active_con to be available
+  struct pending_msg_t {
+    pending_msg_t(MessageRef& m) : msg(m) {}
+    MessageRef msg;
+    seastar::promise<> pr;
+  };
+  std::deque<pending_msg_t> pending_messages;
+};
+
+inline std::ostream& operator<<(std::ostream& out, const Client& client) {
+  client.print(out);
+  return out;
+}
+
+} // namespace crimson::mon