src/bin/lttng-sessiond/agent-thread.cpp

   1 /*
   2  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9
  10 #include <common/common.hpp>
  11 #include <common/sessiond-comm/sessiond-comm.hpp>
  12 #include <common/uri.hpp>
  13 #include <common/utils.hpp>
  14
  15 #include <common/compat/endian.hpp>
  16
  17 #include "fd-limit.hpp"
  18 #include "agent-thread.hpp"
  19 #include "agent.hpp"
  20 #include "lttng-sessiond.hpp"
  21 #include "session.hpp"
  22 #include "utils.hpp"
  23 #include "thread.hpp"
  24
  25 namespace {
  26 struct thread_notifiers {
  27         struct lttng_pipe *quit_pipe;
  28         sem_t ready;
  29 };
  30
  31 struct agent_app_id {
  32         pid_t pid;
  33         enum lttng_domain_type domain;
  34 };
  35
  36 struct agent_protocol_version {
  37         unsigned int major, minor;
  38 };
  39
  40 int agent_tracing_enabled = -1;
  41
  42 /*
  43  * Note that there is not port here. It's set after this URI is parsed so we
  44  * can let the user define a custom one. However, localhost is ALWAYS the
  45  * default listening address.
  46  */
  47 const char *default_reg_uri = "tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS;
  48 } /* namespace */
  49
  50 /*
  51  * Update agent application using the given socket. This is done just after
  52  * registration was successful.
  53  *
  54  * This will acquire the various sessions' lock; none must be held by the
  55  * caller.
  56  * The caller must hold the session list lock.
  57  */
  58 static void update_agent_app(const struct agent_app *app)
  59 {
  60         struct ltt_session *session, *stmp;
  61         struct ltt_session_list *list;
  62         struct agent *trigger_agent;
  63         struct lttng_ht_iter iter;
  64
  65         list = session_get_list();
  66         LTTNG_ASSERT(list);
  67
  68         cds_list_for_each_entry_safe(session, stmp, &list->head, list) {
  69                 if (!session_get(session)) {
  70                         continue;
  71                 }
  72
  73                 session_lock(session);
  74                 if (session->ust_session) {
  75                         const struct agent *agt;
  76
  77                         rcu_read_lock();
  78                         agt = trace_ust_find_agent(session->ust_session, app->domain);
  79                         if (agt) {
  80                                 agent_update(agt, app);
  81                         }
  82                         rcu_read_unlock();
  83                 }
  84                 session_unlock(session);
  85                 session_put(session);
  86         }
  87
  88         rcu_read_lock();
  89         /*
  90          * We are protected against the addition of new events by the session
  91          * list lock being held.
  92          */
  93         cds_lfht_for_each_entry(the_trigger_agents_ht_by_domain->ht,
  94                         &iter.iter, trigger_agent, node.node) {
  95                 agent_update(trigger_agent, app);
  96         }
  97         rcu_read_unlock();
  98 }
  99
 100 /*
 101  * Create and init socket from uri.
 102  */
 103 static struct lttcomm_sock *init_tcp_socket(void)
 104 {
 105         int ret;
 106         struct lttng_uri *uri = NULL;
 107         struct lttcomm_sock *sock = NULL;
 108         unsigned int port;
 109         bool bind_succeeded = false;
 110
 111         /*
 112          * This should never fail since the URI is hardcoded and the port is set
 113          * before this thread is launched.
 114          */
 115         ret = uri_parse(default_reg_uri, &uri);
 116         LTTNG_ASSERT(ret);
 117         LTTNG_ASSERT(the_config.agent_tcp_port.begin > 0);
 118         uri->port = the_config.agent_tcp_port.begin;
 119
 120         sock = lttcomm_alloc_sock_from_uri(uri);
 121         uri_free(uri);
 122         if (sock == NULL) {
 123                 ERR("agent allocating TCP socket");
 124                 goto error;
 125         }
 126
 127         ret = lttcomm_create_sock(sock);
 128         if (ret < 0) {
 129                 goto error;
 130         }
 131
 132         for (port = the_config.agent_tcp_port.begin;
 133                         port <= the_config.agent_tcp_port.end; port++) {
 134                 ret = lttcomm_sock_set_port(sock, (uint16_t) port);
 135                 if (ret) {
 136                         ERR("Failed to set port %u on socket",
 137                                         port);
 138                         goto error;
 139                 }
 140                 DBG3("Trying to bind on port %u", port);
 141                 ret = sock->ops->bind(sock);
 142                 if (!ret) {
 143                         bind_succeeded = true;
 144                         break;
 145                 }
 146
 147                 if (errno == EADDRINUSE) {
 148                         DBG("Failed to bind to port %u since it is already in use",
 149                                         port);
 150                 } else {
 151                         PERROR("Failed to bind to port %u", port);
 152                         goto error;
 153                 }
 154         }
 155
 156         if (!bind_succeeded) {
 157                 if (the_config.agent_tcp_port.begin ==
 158                                 the_config.agent_tcp_port.end) {
 159                         WARN("Another process is already using the agent port %i. "
 160                              "Agent support will be deactivated.",
 161                                         the_config.agent_tcp_port.begin);
 162                         goto error;
 163                 } else {
 164                         WARN("All ports in the range [%i, %i] are already in use. "
 165                              "Agent support will be deactivated.",
 166                                         the_config.agent_tcp_port.begin,
 167                                         the_config.agent_tcp_port.end);
 168                         goto error;
 169                 }
 170         }
 171
 172         ret = sock->ops->listen(sock, -1);
 173         if (ret < 0) {
 174                 goto error;
 175         }
 176
 177         DBG("Listening on TCP port %u and socket %d",
 178                         port, sock->fd);
 179
 180         return sock;
 181
 182 error:
 183         if (sock) {
 184                 lttcomm_destroy_sock(sock);
 185         }
 186         return NULL;
 187 }
 188
 189 /*
 190  * Close and destroy the given TCP socket.
 191  */
 192 static void destroy_tcp_socket(struct lttcomm_sock *sock)
 193 {
 194         int ret;
 195         uint16_t port;
 196
 197         LTTNG_ASSERT(sock);
 198
 199         ret = lttcomm_sock_get_port(sock, &port);
 200         if (ret) {
 201                 ERR("Failed to get port of agent TCP socket");
 202                 port = 0;
 203         }
 204
 205         DBG3("Destroy TCP socket on port %" PRIu16,
 206                         port);
 207
 208         /* This will return gracefully if fd is invalid. */
 209         sock->ops->close(sock);
 210         lttcomm_destroy_sock(sock);
 211 }
 212
 213 static const char *domain_type_str(enum lttng_domain_type domain_type)
 214 {
 215         switch (domain_type) {
 216         case LTTNG_DOMAIN_NONE:
 217                 return "none";
 218         case LTTNG_DOMAIN_KERNEL:
 219                 return "kernel";
 220         case LTTNG_DOMAIN_UST:
 221                 return "ust";
 222         case LTTNG_DOMAIN_JUL:
 223                 return "jul";
 224         case LTTNG_DOMAIN_LOG4J:
 225                 return "log4j";
 226         case LTTNG_DOMAIN_PYTHON:
 227                 return "python";
 228         default:
 229                 return "unknown";
 230         }
 231 }
 232
 233 static bool is_agent_protocol_version_supported(
 234                 const struct agent_protocol_version *version)
 235 {
 236         const bool is_supported = version->major == AGENT_MAJOR_VERSION &&
 237                         version->minor == AGENT_MINOR_VERSION;
 238
 239         if (!is_supported) {
 240                 WARN("Refusing agent connection: unsupported protocol version %ui.%ui, expected %i.%i",
 241                                 version->major, version->minor,
 242                                 AGENT_MAJOR_VERSION, AGENT_MINOR_VERSION);
 243         }
 244
 245         return is_supported;
 246 }
 247
 248 /*
 249  * Handle a new agent connection on the registration socket.
 250  *
 251  * Returns 0 on success, or else a negative errno value.
 252  * On success, the resulting socket is returned through `agent_app_socket`
 253  * and the application's reported id is updated through `agent_app_id`.
 254  */
 255 static int accept_agent_connection(
 256                 struct lttcomm_sock *reg_sock,
 257                 struct agent_app_id *agent_app_id,
 258                 struct lttcomm_sock **agent_app_socket)
 259 {
 260         int ret;
 261         struct agent_protocol_version agent_version;
 262         ssize_t size;
 263         struct agent_register_msg msg;
 264         struct lttcomm_sock *new_sock;
 265
 266         LTTNG_ASSERT(reg_sock);
 267
 268         new_sock = reg_sock->ops->accept(reg_sock);
 269         if (!new_sock) {
 270                 ret = -ENOTCONN;
 271                 goto end;
 272         }
 273
 274         size = new_sock->ops->recvmsg(new_sock, &msg, sizeof(msg), 0);
 275         if (size < sizeof(msg)) {
 276                 if (size < 0) {
 277                         PERROR("Failed to register new agent application");
 278                 } else if (size != 0) {
 279                         ERR("Failed to register new agent application: invalid registration message length: expected length = %zu, message length = %zd",
 280                                         sizeof(msg), size);
 281                 } else {
 282                         DBG("Failed to register new agent application: connection closed");
 283                 }
 284                 ret = -EINVAL;
 285                 goto error_close_socket;
 286         }
 287
 288         agent_version = (struct agent_protocol_version) {
 289                 be32toh(msg.major_version),
 290                 be32toh(msg.minor_version),
 291         };
 292
 293         /* Test communication protocol version of the registering agent. */
 294         if (!is_agent_protocol_version_supported(&agent_version)) {
 295                 ret = -EINVAL;
 296                 goto error_close_socket;
 297         }
 298
 299         *agent_app_id = (struct agent_app_id) {
 300                 .pid = (pid_t) be32toh(msg.pid),
 301                 .domain = (lttng_domain_type) be32toh(msg.domain),
 302         };
 303
 304         DBG2("New registration for agent application: pid = %ld, domain = %s, socket fd = %d",
 305                         (long) agent_app_id->pid,
 306                         domain_type_str(agent_app_id->domain), new_sock->fd);
 307
 308         *agent_app_socket = new_sock;
 309         new_sock = NULL;
 310         ret = 0;
 311         goto end;
 312
 313 error_close_socket:
 314         new_sock->ops->close(new_sock);
 315         lttcomm_destroy_sock(new_sock);
 316 end:
 317         return ret;
 318 }
 319
 320 bool agent_tracing_is_enabled(void)
 321 {
 322         int enabled;
 323
 324         enabled = uatomic_read(&agent_tracing_enabled);
 325         LTTNG_ASSERT(enabled != -1);
 326         return enabled == 1;
 327 }
 328
 329 /*
 330  * Write agent TCP port using the rundir.
 331  */
 332 static int write_agent_port(uint16_t port)
 333 {
 334         return utils_create_pid_file(
 335                         (pid_t) port, the_config.agent_port_file_path.value);
 336 }
 337
 338 static
 339 void mark_thread_as_ready(struct thread_notifiers *notifiers)
 340 {
 341         DBG("Marking agent management thread as ready");
 342         sem_post(&notifiers->ready);
 343 }
 344
 345 static
 346 void wait_until_thread_is_ready(struct thread_notifiers *notifiers)
 347 {
 348         DBG("Waiting for agent management thread to be ready");
 349         sem_wait(&notifiers->ready);
 350         DBG("Agent management thread is ready");
 351 }
 352
 353 /*
 354  * This thread manage application notify communication.
 355  */
 356 static void *thread_agent_management(void *data)
 357 {
 358         int i, ret, pollfd;
 359         uint32_t revents, nb_fd;
 360         struct lttng_poll_event events;
 361         struct lttcomm_sock *reg_sock;
 362         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 363         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
 364                         notifiers->quit_pipe);
 365
 366         DBG("Manage agent application registration.");
 367
 368         rcu_register_thread();
 369         rcu_thread_online();
 370
 371         /* Agent initialization call MUST be called before starting the thread. */
 372         LTTNG_ASSERT(the_agent_apps_ht_by_sock);
 373
 374         /* Create pollset with size 2, quit pipe and registration socket. */
 375         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
 376         if (ret < 0) {
 377                 goto error_poll_create;
 378         }
 379
 380         ret = lttng_poll_add(&events, quit_pipe_read_fd,
 381                         LPOLLIN | LPOLLERR);
 382         if (ret < 0) {
 383                 goto error_tcp_socket;
 384         }
 385
 386         reg_sock = init_tcp_socket();
 387         if (reg_sock) {
 388                 uint16_t port;
 389
 390                 ret = lttcomm_sock_get_port(reg_sock, &port);
 391                 LTTNG_ASSERT(ret == 0);
 392
 393                 ret = write_agent_port(port);
 394                 if (ret) {
 395                         ERR("Failed to create agent port file: agent tracing will be unavailable");
 396                         /* Don't prevent the launch of the sessiond on error. */
 397                         mark_thread_as_ready(notifiers);
 398                         goto error;
 399                 }
 400         } else {
 401                 /* Don't prevent the launch of the sessiond on error. */
 402                 mark_thread_as_ready(notifiers);
 403                 goto error_tcp_socket;
 404         }
 405
 406         /*
 407          * Signal that the agent thread is ready. The command thread
 408          * may start to query whether or not agent tracing is enabled.
 409          */
 410         uatomic_set(&agent_tracing_enabled, 1);
 411         mark_thread_as_ready(notifiers);
 412
 413         /* Add TCP socket to the poll set. */
 414         ret = lttng_poll_add(&events, reg_sock->fd,
 415                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 416         if (ret < 0) {
 417                 goto error;
 418         }
 419
 420         while (1) {
 421                 DBG3("Manage agent polling");
 422
 423                 /* Inifinite blocking call, waiting for transmission */
 424 restart:
 425                 ret = lttng_poll_wait(&events, -1);
 426                 DBG3("Manage agent return from poll on %d fds",
 427                                 LTTNG_POLL_GETNB(&events));
 428                 if (ret < 0) {
 429                         /*
 430                          * Restart interrupted system call.
 431                          */
 432                         if (errno == EINTR) {
 433                                 goto restart;
 434                         }
 435                         goto error;
 436                 }
 437                 nb_fd = ret;
 438                 DBG3("%d fd ready", nb_fd);
 439
 440                 for (i = 0; i < nb_fd; i++) {
 441                         /* Fetch once the poll data */
 442                         revents = LTTNG_POLL_GETEV(&events, i);
 443                         pollfd = LTTNG_POLL_GETFD(&events, i);
 444
 445                         /* Thread quit pipe has been closed. Killing thread. */
 446                         if (pollfd == quit_pipe_read_fd) {
 447                                 goto exit;
 448                         }
 449
 450                         /* Activity on the registration socket. */
 451                         if (revents & LPOLLIN) {
 452                                 struct agent_app_id new_app_id;
 453                                 struct agent_app *new_app = NULL;
 454                                 struct lttcomm_sock *new_app_socket;
 455                                 int new_app_socket_fd;
 456
 457                                 LTTNG_ASSERT(pollfd == reg_sock->fd);
 458
 459                                 ret = accept_agent_connection(
 460                                         reg_sock, &new_app_id, &new_app_socket);
 461                                 if (ret < 0) {
 462                                         /* Errors are already logged. */
 463                                         continue;
 464                                 }
 465
 466                                 /*
 467                                  * new_app_socket's ownership has been
 468                                  * transferred to the new agent app.
 469                                  */
 470                                 new_app = agent_create_app(new_app_id.pid,
 471                                                 new_app_id.domain,
 472                                                 new_app_socket);
 473                                 if (!new_app) {
 474                                         new_app_socket->ops->close(
 475                                                         new_app_socket);
 476                                         continue;
 477                                 }
 478                                 new_app_socket_fd = new_app_socket->fd;
 479                                 new_app_socket = NULL;
 480
 481                                 /*
 482                                  * Since this is a command socket (write then
 483                                  * read), only add poll error event to only
 484                                  * detect shutdown.
 485                                  */
 486                                 ret = lttng_poll_add(&events, new_app_socket_fd,
 487                                                 LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 488                                 if (ret < 0) {
 489                                         agent_destroy_app(new_app);
 490                                         continue;
 491                                 }
 492
 493                                 /*
 494                                  * Prevent sessions from being modified while
 495                                  * the agent application's configuration is
 496                                  * updated.
 497                                  */
 498                                 session_lock_list();
 499
 500                                 /*
 501                                  * Update the newly registered applications's
 502                                  * configuration.
 503                                  */
 504                                 update_agent_app(new_app);
 505
 506                                 ret = agent_send_registration_done(new_app);
 507                                 if (ret < 0) {
 508                                         agent_destroy_app(new_app);
 509                                         /* Removing from the poll set. */
 510                                         ret = lttng_poll_del(&events,
 511                                                         new_app_socket_fd);
 512                                         if (ret < 0) {
 513                                                 session_unlock_list();
 514                                                 goto error;
 515                                         }
 516                                         continue;
 517                                 }
 518
 519                                 /* Publish the new agent app. */
 520                                 agent_add_app(new_app);
 521
 522                                 session_unlock_list();
 523                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 524                                 /* Removing from the poll set */
 525                                 ret = lttng_poll_del(&events, pollfd);
 526                                 if (ret < 0) {
 527                                         goto error;
 528                                 }
 529                                 agent_destroy_app_by_sock(pollfd);
 530                         } else {
 531                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 532                                 goto error;
 533                         }
 534                 }
 535         }
 536
 537 exit:
 538         /* Whatever happens, try to delete it and exit. */
 539         (void) lttng_poll_del(&events, reg_sock->fd);
 540 error:
 541         destroy_tcp_socket(reg_sock);
 542 error_tcp_socket:
 543         lttng_poll_clean(&events);
 544 error_poll_create:
 545         uatomic_set(&agent_tracing_enabled, 0);
 546         DBG("Cleaning up and stopping.");
 547         rcu_thread_offline();
 548         rcu_unregister_thread();
 549         return NULL;
 550 }
 551
 552 static bool shutdown_agent_management_thread(void *data)
 553 {
 554         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 555         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 556
 557         return notify_thread_pipe(write_fd) == 1;
 558 }
 559
 560 static void cleanup_agent_management_thread(void *data)
 561 {
 562         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 563
 564         lttng_pipe_destroy(notifiers->quit_pipe);
 565         sem_destroy(&notifiers->ready);
 566         free(notifiers);
 567 }
 568
 569 bool launch_agent_management_thread(void)
 570 {
 571         struct thread_notifiers *notifiers;
 572         struct lttng_thread *thread;
 573
 574         notifiers = zmalloc<thread_notifiers>();
 575         if (!notifiers) {
 576                 goto error_alloc;
 577         }
 578
 579         sem_init(&notifiers->ready, 0, 0);
 580         notifiers->quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 581         if (!notifiers->quit_pipe) {
 582                 goto error;
 583         }
 584         thread = lttng_thread_create("Agent management",
 585                         thread_agent_management,
 586                         shutdown_agent_management_thread,
 587                         cleanup_agent_management_thread,
 588                         notifiers);
 589         if (!thread) {
 590                 goto error;
 591         }
 592         wait_until_thread_is_ready(notifiers);
 593         lttng_thread_put(thread);
 594         return true;
 595 error:
 596         cleanup_agent_management_thread(notifiers);
 597 error_alloc:
 598         return false;
 599 }