| 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 | #include <assert.h> |
| 10 | |
| 11 | #include <common/common.h> |
| 12 | #include <common/sessiond-comm/sessiond-comm.h> |
| 13 | #include <common/uri.h> |
| 14 | #include <common/utils.h> |
| 15 | |
| 16 | #include <common/compat/endian.h> |
| 17 | |
| 18 | #include "fd-limit.h" |
| 19 | #include "agent-thread.h" |
| 20 | #include "agent.h" |
| 21 | #include "lttng-sessiond.h" |
| 22 | #include "session.h" |
| 23 | #include "utils.h" |
| 24 | #include "thread.h" |
| 25 | |
| 26 | struct thread_notifiers { |
| 27 | struct lttng_pipe *quit_pipe; |
| 28 | sem_t ready; |
| 29 | }; |
| 30 | |
| 31 | static int agent_tracing_enabled = -1; |
| 32 | |
| 33 | /* |
| 34 | * Note that there is not port here. It's set after this URI is parsed so we |
| 35 | * can let the user define a custom one. However, localhost is ALWAYS the |
| 36 | * default listening address. |
| 37 | */ |
| 38 | static const char *default_reg_uri = |
| 39 | "tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS; |
| 40 | |
| 41 | /* |
| 42 | * Update agent application using the given socket. This is done just after |
| 43 | * registration was successful. |
| 44 | * |
| 45 | * This is a quite heavy call in terms of locking since the session list lock |
| 46 | * AND session lock are acquired. |
| 47 | */ |
| 48 | static void update_agent_app(struct agent_app *app) |
| 49 | { |
| 50 | struct ltt_session *session, *stmp; |
| 51 | struct ltt_session_list *list; |
| 52 | |
| 53 | list = session_get_list(); |
| 54 | assert(list); |
| 55 | |
| 56 | session_lock_list(); |
| 57 | cds_list_for_each_entry_safe(session, stmp, &list->head, list) { |
| 58 | if (!session_get(session)) { |
| 59 | continue; |
| 60 | } |
| 61 | |
| 62 | session_lock(session); |
| 63 | if (session->ust_session) { |
| 64 | struct agent *agt; |
| 65 | |
| 66 | rcu_read_lock(); |
| 67 | agt = trace_ust_find_agent(session->ust_session, app->domain); |
| 68 | if (agt) { |
| 69 | agent_update(agt, app->sock->fd); |
| 70 | } |
| 71 | rcu_read_unlock(); |
| 72 | } |
| 73 | session_unlock(session); |
| 74 | session_put(session); |
| 75 | } |
| 76 | session_unlock_list(); |
| 77 | } |
| 78 | |
| 79 | /* |
| 80 | * Create and init socket from uri. |
| 81 | */ |
| 82 | static struct lttcomm_sock *init_tcp_socket(void) |
| 83 | { |
| 84 | int ret; |
| 85 | struct lttng_uri *uri = NULL; |
| 86 | struct lttcomm_sock *sock = NULL; |
| 87 | unsigned int port; |
| 88 | bool bind_succeeded = false; |
| 89 | |
| 90 | /* |
| 91 | * This should never fail since the URI is hardcoded and the port is set |
| 92 | * before this thread is launched. |
| 93 | */ |
| 94 | ret = uri_parse(default_reg_uri, &uri); |
| 95 | assert(ret); |
| 96 | assert(config.agent_tcp_port.begin > 0); |
| 97 | uri->port = config.agent_tcp_port.begin; |
| 98 | |
| 99 | sock = lttcomm_alloc_sock_from_uri(uri); |
| 100 | uri_free(uri); |
| 101 | if (sock == NULL) { |
| 102 | ERR("[agent-thread] agent allocating TCP socket"); |
| 103 | goto error; |
| 104 | } |
| 105 | |
| 106 | ret = lttcomm_create_sock(sock); |
| 107 | if (ret < 0) { |
| 108 | goto error; |
| 109 | } |
| 110 | |
| 111 | for (port = config.agent_tcp_port.begin; |
| 112 | port <= config.agent_tcp_port.end; port++) { |
| 113 | ret = lttcomm_sock_set_port(sock, (uint16_t) port); |
| 114 | if (ret) { |
| 115 | ERR("[agent-thread] Failed to set port %u on socket", |
| 116 | port); |
| 117 | goto error; |
| 118 | } |
| 119 | DBG3("[agent-thread] Trying to bind on port %u", port); |
| 120 | ret = sock->ops->bind(sock); |
| 121 | if (!ret) { |
| 122 | bind_succeeded = true; |
| 123 | break; |
| 124 | } |
| 125 | |
| 126 | if (errno == EADDRINUSE) { |
| 127 | DBG("Failed to bind to port %u since it is already in use", |
| 128 | port); |
| 129 | } else { |
| 130 | PERROR("Failed to bind to port %u", port); |
| 131 | goto error; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | if (!bind_succeeded) { |
| 136 | if (config.agent_tcp_port.begin == config.agent_tcp_port.end) { |
| 137 | WARN("Another process is already using the agent port %i. " |
| 138 | "Agent support will be deactivated.", |
| 139 | config.agent_tcp_port.begin); |
| 140 | goto error; |
| 141 | } else { |
| 142 | WARN("All ports in the range [%i, %i] are already in use. " |
| 143 | "Agent support will be deactivated.", |
| 144 | config.agent_tcp_port.begin, |
| 145 | config.agent_tcp_port.end); |
| 146 | goto error; |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | ret = sock->ops->listen(sock, -1); |
| 151 | if (ret < 0) { |
| 152 | goto error; |
| 153 | } |
| 154 | |
| 155 | DBG("[agent-thread] Listening on TCP port %u and socket %d", |
| 156 | port, sock->fd); |
| 157 | |
| 158 | return sock; |
| 159 | |
| 160 | error: |
| 161 | if (sock) { |
| 162 | lttcomm_destroy_sock(sock); |
| 163 | } |
| 164 | return NULL; |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * Close and destroy the given TCP socket. |
| 169 | */ |
| 170 | static void destroy_tcp_socket(struct lttcomm_sock *sock) |
| 171 | { |
| 172 | int ret; |
| 173 | uint16_t port; |
| 174 | |
| 175 | assert(sock); |
| 176 | |
| 177 | ret = lttcomm_sock_get_port(sock, &port); |
| 178 | if (ret) { |
| 179 | ERR("[agent-thread] Failed to get port of agent TCP socket"); |
| 180 | port = 0; |
| 181 | } |
| 182 | |
| 183 | DBG3("[agent-thread] Destroy TCP socket on port %" PRIu16, |
| 184 | port); |
| 185 | |
| 186 | /* This will return gracefully if fd is invalid. */ |
| 187 | sock->ops->close(sock); |
| 188 | lttcomm_destroy_sock(sock); |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * Handle a new agent registration using the reg socket. After that, a new |
| 193 | * agent application is added to the global hash table and attach to an UST app |
| 194 | * object. If r_app is not NULL, the created app is set to the pointer. |
| 195 | * |
| 196 | * Return the new FD created upon accept() on success or else a negative errno |
| 197 | * value. |
| 198 | */ |
| 199 | static int handle_registration(struct lttcomm_sock *reg_sock, |
| 200 | struct agent_app **r_app) |
| 201 | { |
| 202 | int ret; |
| 203 | pid_t pid; |
| 204 | uint32_t major_version, minor_version; |
| 205 | ssize_t size; |
| 206 | enum lttng_domain_type domain; |
| 207 | struct agent_app *app; |
| 208 | struct agent_register_msg msg; |
| 209 | struct lttcomm_sock *new_sock; |
| 210 | |
| 211 | assert(reg_sock); |
| 212 | |
| 213 | new_sock = reg_sock->ops->accept(reg_sock); |
| 214 | if (!new_sock) { |
| 215 | ret = -ENOTCONN; |
| 216 | goto error; |
| 217 | } |
| 218 | |
| 219 | size = new_sock->ops->recvmsg(new_sock, &msg, sizeof(msg), 0); |
| 220 | if (size < sizeof(msg)) { |
| 221 | ret = -EINVAL; |
| 222 | goto error_socket; |
| 223 | } |
| 224 | domain = be32toh(msg.domain); |
| 225 | pid = be32toh(msg.pid); |
| 226 | major_version = be32toh(msg.major_version); |
| 227 | minor_version = be32toh(msg.minor_version); |
| 228 | |
| 229 | /* Test communication protocol version of the registring agent. */ |
| 230 | if (major_version != AGENT_MAJOR_VERSION) { |
| 231 | ret = -EINVAL; |
| 232 | goto error_socket; |
| 233 | } |
| 234 | if (minor_version != AGENT_MINOR_VERSION) { |
| 235 | ret = -EINVAL; |
| 236 | goto error_socket; |
| 237 | } |
| 238 | |
| 239 | DBG2("[agent-thread] New registration for pid %d domain %d on socket %d", |
| 240 | pid, domain, new_sock->fd); |
| 241 | |
| 242 | app = agent_create_app(pid, domain, new_sock); |
| 243 | if (!app) { |
| 244 | ret = -ENOMEM; |
| 245 | goto error_socket; |
| 246 | } |
| 247 | |
| 248 | /* |
| 249 | * Add before assigning the socket value to the UST app so it can be found |
| 250 | * concurrently. |
| 251 | */ |
| 252 | agent_add_app(app); |
| 253 | |
| 254 | /* |
| 255 | * We don't need to attach the agent app to the app. If we ever do so, we |
| 256 | * should consider both registration order of agent before app and app |
| 257 | * before agent. |
| 258 | */ |
| 259 | |
| 260 | if (r_app) { |
| 261 | *r_app = app; |
| 262 | } |
| 263 | |
| 264 | return new_sock->fd; |
| 265 | |
| 266 | error_socket: |
| 267 | new_sock->ops->close(new_sock); |
| 268 | lttcomm_destroy_sock(new_sock); |
| 269 | error: |
| 270 | return ret; |
| 271 | } |
| 272 | |
| 273 | bool agent_tracing_is_enabled(void) |
| 274 | { |
| 275 | int enabled; |
| 276 | |
| 277 | enabled = uatomic_read(&agent_tracing_enabled); |
| 278 | assert(enabled != -1); |
| 279 | return enabled == 1; |
| 280 | } |
| 281 | |
| 282 | /* |
| 283 | * Write agent TCP port using the rundir. |
| 284 | */ |
| 285 | static int write_agent_port(uint16_t port) |
| 286 | { |
| 287 | return utils_create_pid_file((pid_t) port, |
| 288 | config.agent_port_file_path.value); |
| 289 | } |
| 290 | |
| 291 | static |
| 292 | void mark_thread_as_ready(struct thread_notifiers *notifiers) |
| 293 | { |
| 294 | DBG("Marking agent management thread as ready"); |
| 295 | sem_post(¬ifiers->ready); |
| 296 | } |
| 297 | |
| 298 | static |
| 299 | void wait_until_thread_is_ready(struct thread_notifiers *notifiers) |
| 300 | { |
| 301 | DBG("Waiting for agent management thread to be ready"); |
| 302 | sem_wait(¬ifiers->ready); |
| 303 | DBG("Agent management thread is ready"); |
| 304 | } |
| 305 | |
| 306 | /* |
| 307 | * This thread manage application notify communication. |
| 308 | */ |
| 309 | static void *thread_agent_management(void *data) |
| 310 | { |
| 311 | int i, ret, pollfd; |
| 312 | uint32_t revents, nb_fd; |
| 313 | struct lttng_poll_event events; |
| 314 | struct lttcomm_sock *reg_sock; |
| 315 | struct thread_notifiers *notifiers = data; |
| 316 | const int quit_pipe_read_fd = lttng_pipe_get_readfd( |
| 317 | notifiers->quit_pipe); |
| 318 | |
| 319 | DBG("[agent-thread] Manage agent application registration."); |
| 320 | |
| 321 | rcu_register_thread(); |
| 322 | rcu_thread_online(); |
| 323 | |
| 324 | /* Agent initialization call MUST be called before starting the thread. */ |
| 325 | assert(agent_apps_ht_by_sock); |
| 326 | |
| 327 | /* Create pollset with size 2, quit pipe and registration socket. */ |
| 328 | ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC); |
| 329 | if (ret < 0) { |
| 330 | goto error_poll_create; |
| 331 | } |
| 332 | |
| 333 | ret = lttng_poll_add(&events, quit_pipe_read_fd, |
| 334 | LPOLLIN | LPOLLERR); |
| 335 | if (ret < 0) { |
| 336 | goto error_tcp_socket; |
| 337 | } |
| 338 | |
| 339 | reg_sock = init_tcp_socket(); |
| 340 | if (reg_sock) { |
| 341 | uint16_t port; |
| 342 | |
| 343 | assert(lttcomm_sock_get_port(reg_sock, &port) == 0); |
| 344 | |
| 345 | ret = write_agent_port(port); |
| 346 | if (ret) { |
| 347 | ERR("[agent-thread] Failed to create agent port file: agent tracing will be unavailable"); |
| 348 | /* Don't prevent the launch of the sessiond on error. */ |
| 349 | mark_thread_as_ready(notifiers); |
| 350 | goto error; |
| 351 | } |
| 352 | } else { |
| 353 | /* Don't prevent the launch of the sessiond on error. */ |
| 354 | mark_thread_as_ready(notifiers); |
| 355 | goto error_tcp_socket; |
| 356 | } |
| 357 | |
| 358 | /* |
| 359 | * Signal that the agent thread is ready. The command thread |
| 360 | * may start to query whether or not agent tracing is enabled. |
| 361 | */ |
| 362 | uatomic_set(&agent_tracing_enabled, 1); |
| 363 | mark_thread_as_ready(notifiers); |
| 364 | |
| 365 | /* Add TCP socket to poll set. */ |
| 366 | ret = lttng_poll_add(&events, reg_sock->fd, |
| 367 | LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP); |
| 368 | if (ret < 0) { |
| 369 | goto error; |
| 370 | } |
| 371 | |
| 372 | while (1) { |
| 373 | DBG3("[agent-thread] Manage agent polling"); |
| 374 | |
| 375 | /* Inifinite blocking call, waiting for transmission */ |
| 376 | restart: |
| 377 | ret = lttng_poll_wait(&events, -1); |
| 378 | DBG3("[agent-thread] Manage agent return from poll on %d fds", |
| 379 | LTTNG_POLL_GETNB(&events)); |
| 380 | if (ret < 0) { |
| 381 | /* |
| 382 | * Restart interrupted system call. |
| 383 | */ |
| 384 | if (errno == EINTR) { |
| 385 | goto restart; |
| 386 | } |
| 387 | goto error; |
| 388 | } |
| 389 | nb_fd = ret; |
| 390 | DBG3("[agent-thread] %d fd ready", nb_fd); |
| 391 | |
| 392 | for (i = 0; i < nb_fd; i++) { |
| 393 | /* Fetch once the poll data */ |
| 394 | revents = LTTNG_POLL_GETEV(&events, i); |
| 395 | pollfd = LTTNG_POLL_GETFD(&events, i); |
| 396 | |
| 397 | /* Thread quit pipe has been closed. Killing thread. */ |
| 398 | if (pollfd == quit_pipe_read_fd) { |
| 399 | goto exit; |
| 400 | } |
| 401 | |
| 402 | if (revents & LPOLLIN) { |
| 403 | int new_fd; |
| 404 | struct agent_app *app = NULL; |
| 405 | |
| 406 | assert(pollfd == reg_sock->fd); |
| 407 | new_fd = handle_registration(reg_sock, &app); |
| 408 | if (new_fd < 0) { |
| 409 | continue; |
| 410 | } |
| 411 | /* Should not have a NULL app on success. */ |
| 412 | assert(app); |
| 413 | |
| 414 | /* |
| 415 | * Since this is a command socket (write then read), |
| 416 | * only add poll error event to only detect shutdown. |
| 417 | */ |
| 418 | ret = lttng_poll_add(&events, new_fd, |
| 419 | LPOLLERR | LPOLLHUP | LPOLLRDHUP); |
| 420 | if (ret < 0) { |
| 421 | agent_destroy_app_by_sock(new_fd); |
| 422 | continue; |
| 423 | } |
| 424 | |
| 425 | /* Update newly registered app. */ |
| 426 | update_agent_app(app); |
| 427 | |
| 428 | /* On failure, the poll will detect it and clean it up. */ |
| 429 | ret = agent_send_registration_done(app); |
| 430 | if (ret < 0) { |
| 431 | /* Removing from the poll set */ |
| 432 | ret = lttng_poll_del(&events, new_fd); |
| 433 | if (ret < 0) { |
| 434 | goto error; |
| 435 | } |
| 436 | agent_destroy_app_by_sock(new_fd); |
| 437 | continue; |
| 438 | } |
| 439 | } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) { |
| 440 | /* Removing from the poll set */ |
| 441 | ret = lttng_poll_del(&events, pollfd); |
| 442 | if (ret < 0) { |
| 443 | goto error; |
| 444 | } |
| 445 | agent_destroy_app_by_sock(pollfd); |
| 446 | } else { |
| 447 | ERR("Unexpected poll events %u for sock %d", revents, pollfd); |
| 448 | goto error; |
| 449 | } |
| 450 | } |
| 451 | } |
| 452 | |
| 453 | exit: |
| 454 | /* Whatever happens, try to delete it and exit. */ |
| 455 | (void) lttng_poll_del(&events, reg_sock->fd); |
| 456 | error: |
| 457 | destroy_tcp_socket(reg_sock); |
| 458 | error_tcp_socket: |
| 459 | lttng_poll_clean(&events); |
| 460 | error_poll_create: |
| 461 | uatomic_set(&agent_tracing_enabled, 0); |
| 462 | DBG("[agent-thread] Cleaning up and stopping."); |
| 463 | rcu_thread_offline(); |
| 464 | rcu_unregister_thread(); |
| 465 | return NULL; |
| 466 | } |
| 467 | |
| 468 | static bool shutdown_agent_management_thread(void *data) |
| 469 | { |
| 470 | struct thread_notifiers *notifiers = data; |
| 471 | const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe); |
| 472 | |
| 473 | return notify_thread_pipe(write_fd) == 1; |
| 474 | } |
| 475 | |
| 476 | static void cleanup_agent_management_thread(void *data) |
| 477 | { |
| 478 | struct thread_notifiers *notifiers = data; |
| 479 | |
| 480 | lttng_pipe_destroy(notifiers->quit_pipe); |
| 481 | sem_destroy(¬ifiers->ready); |
| 482 | free(notifiers); |
| 483 | } |
| 484 | |
| 485 | bool launch_agent_management_thread(void) |
| 486 | { |
| 487 | struct thread_notifiers *notifiers; |
| 488 | struct lttng_thread *thread; |
| 489 | |
| 490 | notifiers = zmalloc(sizeof(*notifiers)); |
| 491 | if (!notifiers) { |
| 492 | goto error_alloc; |
| 493 | } |
| 494 | |
| 495 | sem_init(¬ifiers->ready, 0, 0); |
| 496 | notifiers->quit_pipe = lttng_pipe_open(FD_CLOEXEC); |
| 497 | if (!notifiers->quit_pipe) { |
| 498 | goto error; |
| 499 | } |
| 500 | thread = lttng_thread_create("Agent management", |
| 501 | thread_agent_management, |
| 502 | shutdown_agent_management_thread, |
| 503 | cleanup_agent_management_thread, |
| 504 | notifiers); |
| 505 | if (!thread) { |
| 506 | goto error; |
| 507 | } |
| 508 | wait_until_thread_is_ready(notifiers); |
| 509 | lttng_thread_put(thread); |
| 510 | return true; |
| 511 | error: |
| 512 | cleanup_agent_management_thread(notifiers); |
| 513 | error_alloc: |
| 514 | return false; |
| 515 | } |