src/bin/lttng-sessiond/register.cpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   3  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  * Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-only
   7  *
   8  */
   9
  10 #include <stddef.h>
  11 #include <stdlib.h>
  12 #include <urcu.h>
  13 #include <common/futex.hpp>
  14 #include <common/macros.hpp>
  15 #include <common/shm.hpp>
  16 #include <common/utils.hpp>
  17 #include <sys/stat.h>
  18
  19 #include "register.hpp"
  20 #include "lttng-sessiond.hpp"
  21 #include "testpoint.hpp"
  22 #include "health-sessiond.hpp"
  23 #include "fd-limit.hpp"
  24 #include "utils.hpp"
  25 #include "thread.hpp"
  26
  27 namespace {
  28 struct thread_state {
  29         struct lttng_pipe *quit_pipe;
  30         struct ust_cmd_queue *ust_cmd_queue;
  31         sem_t ready;
  32         bool running;
  33         int application_socket;
  34 };
  35 } /* namespace */
  36
  37 /*
  38  * Creates the application socket.
  39  */
  40 static int create_application_socket(void)
  41 {
  42         int ret = 0;
  43         int apps_sock;
  44         const mode_t old_umask = umask(0);
  45
  46         /* Create the application unix socket */
  47         apps_sock = lttcomm_create_unix_sock(
  48                         the_config.apps_unix_sock_path.value);
  49         if (apps_sock < 0) {
  50                 ERR("Create unix sock failed: %s",
  51                                 the_config.apps_unix_sock_path.value);
  52                 ret = -1;
  53                 goto end;
  54         }
  55
  56         /* Set the cloexec flag */
  57         ret = utils_set_fd_cloexec(apps_sock);
  58         if (ret < 0) {
  59                 ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
  60                                 "Continuing but note that the consumer daemon will have a "
  61                                 "reference to this socket on exec()", apps_sock);
  62         }
  63
  64         /* File permission MUST be 666 */
  65         ret = chmod(the_config.apps_unix_sock_path.value,
  66                         S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
  67                                         S_IWOTH);
  68         if (ret < 0) {
  69                 PERROR("Set file permissions failed on %s",
  70                                 the_config.apps_unix_sock_path.value);
  71                 goto error_close_socket;
  72         }
  73
  74         DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
  75         ret = apps_sock;
  76 end:
  77         umask(old_umask);
  78         return ret;
  79 error_close_socket:
  80         if (close(apps_sock)) {
  81                 PERROR("Failed to close application socket in error path");
  82         }
  83         apps_sock = -1;
  84         ret = -1;
  85         goto end;
  86 }
  87
  88 /*
  89  * Notify UST applications using the shm mmap futex.
  90  */
  91 static int notify_ust_apps(int active, bool is_root)
  92 {
  93         char *wait_shm_mmap;
  94
  95         DBG("Notifying applications of session daemon state: %d", active);
  96
  97         /* See shm.c for this call implying mmap, shm and futex calls */
  98         wait_shm_mmap = shm_ust_get_mmap(
  99                         the_config.wait_shm_path.value, is_root);
 100         if (wait_shm_mmap == NULL) {
 101                 goto error;
 102         }
 103
 104         /* Wake waiting process */
 105         futex_wait_update((int32_t *) wait_shm_mmap, active);
 106
 107         /* Apps notified successfully */
 108         return 0;
 109
 110 error:
 111         return -1;
 112 }
 113
 114 static void cleanup_application_registration_thread(void *data)
 115 {
 116         struct thread_state *thread_state = (struct thread_state *) data;
 117
 118         if (!data) {
 119                 return;
 120         }
 121
 122         lttng_pipe_destroy(thread_state->quit_pipe);
 123         free(thread_state);
 124 }
 125
 126 static void set_thread_status(struct thread_state *thread_state, bool running)
 127 {
 128         DBG("Marking application registration thread's state as %s", running ? "running" : "error");
 129         thread_state->running = running;
 130         sem_post(&thread_state->ready);
 131 }
 132
 133 static bool wait_thread_status(struct thread_state *thread_state)
 134 {
 135         DBG("Waiting for application registration thread to be ready");
 136         sem_wait(&thread_state->ready);
 137         if (thread_state->running) {
 138                 DBG("Application registration thread is ready");
 139         } else {
 140                 ERR("Initialization of application registration thread failed");
 141         }
 142
 143         return thread_state->running;
 144 }
 145
 146 static void thread_init_cleanup(void *data)
 147 {
 148         struct thread_state *thread_state = (struct thread_state *) data;
 149
 150         set_thread_status(thread_state, false);
 151 }
 152
 153 /*
 154  * This thread manage application registration.
 155  */
 156 static void *thread_application_registration(void *data)
 157 {
 158         int sock = -1, i, ret, pollfd, err = -1;
 159         uint32_t revents, nb_fd;
 160         struct lttng_poll_event events;
 161         /*
 162          * Gets allocated in this thread, enqueued to a global queue, dequeued
 163          * and freed in the manage apps thread.
 164          */
 165         struct ust_command *ust_cmd = NULL;
 166         const bool is_root = (getuid() == 0);
 167         struct thread_state *thread_state = (struct thread_state *) data;
 168         const int application_socket = thread_state->application_socket;
 169         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
 170                         thread_state->quit_pipe);
 171
 172         DBG("[thread] Manage application registration started");
 173
 174         pthread_cleanup_push(thread_init_cleanup, thread_state);
 175         health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);
 176
 177         ret = lttcomm_listen_unix_sock(application_socket);
 178         if (ret < 0) {
 179                 goto error_listen;
 180         }
 181
 182         /*
 183          * Pass 2 as size here for the thread quit pipe and apps_sock. Nothing
 184          * more will be added to this poll set.
 185          */
 186         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
 187         if (ret < 0) {
 188                 goto error_create_poll;
 189         }
 190
 191         /* Add the application registration socket */
 192         ret = lttng_poll_add(&events, application_socket, LPOLLIN | LPOLLRDHUP);
 193         if (ret < 0) {
 194                 goto error_poll_add;
 195         }
 196
 197         /* Add the application registration socket */
 198         ret = lttng_poll_add(&events, quit_pipe_read_fd, LPOLLIN | LPOLLRDHUP);
 199         if (ret < 0) {
 200                 goto error_poll_add;
 201         }
 202
 203         set_thread_status(thread_state, true);
 204         pthread_cleanup_pop(0);
 205
 206         if (testpoint(sessiond_thread_registration_apps)) {
 207                 goto error_poll_add;
 208         }
 209
 210         while (1) {
 211                 DBG("Accepting application registration");
 212
 213                 /* Inifinite blocking call, waiting for transmission */
 214         restart:
 215                 health_poll_entry();
 216                 ret = lttng_poll_wait(&events, -1);
 217                 health_poll_exit();
 218                 if (ret < 0) {
 219                         /*
 220                          * Restart interrupted system call.
 221                          */
 222                         if (errno == EINTR) {
 223                                 goto restart;
 224                         }
 225                         goto error;
 226                 }
 227
 228                 nb_fd = ret;
 229
 230                 for (i = 0; i < nb_fd; i++) {
 231                         health_code_update();
 232
 233                         /* Fetch once the poll data */
 234                         revents = LTTNG_POLL_GETEV(&events, i);
 235                         pollfd = LTTNG_POLL_GETFD(&events, i);
 236
 237                         /* Thread quit pipe has been closed. Killing thread. */
 238                         if (pollfd == quit_pipe_read_fd) {
 239                                 err = 0;
 240                                 goto exit;
 241                         } else {
 242                                 /* Event on the registration socket */
 243                                 if (revents & LPOLLIN) {
 244                                         sock = lttcomm_accept_unix_sock(application_socket);
 245                                         if (sock < 0) {
 246                                                 goto error;
 247                                         }
 248
 249                                         /*
 250                                          * Set socket timeout for both receiving and ending.
 251                                          * app_socket_timeout is in seconds, whereas
 252                                          * lttcomm_setsockopt_rcv_timeout and
 253                                          * lttcomm_setsockopt_snd_timeout expect msec as
 254                                          * parameter.
 255                                          */
 256                                         if (the_config.app_socket_timeout >= 0) {
 257                                                 (void) lttcomm_setsockopt_rcv_timeout(sock,
 258                                                                 the_config.app_socket_timeout * 1000);
 259                                                 (void) lttcomm_setsockopt_snd_timeout(sock,
 260                                                                 the_config.app_socket_timeout * 1000);
 261                                         }
 262
 263                                         /*
 264                                          * Set the CLOEXEC flag. Return code is useless because
 265                                          * either way, the show must go on.
 266                                          */
 267                                         (void) utils_set_fd_cloexec(sock);
 268
 269                                         /* Create UST registration command for enqueuing */
 270                                         ust_cmd = zmalloc<ust_command>();
 271                                         if (ust_cmd == NULL) {
 272                                                 PERROR("ust command zmalloc");
 273                                                 ret = close(sock);
 274                                                 if (ret) {
 275                                                         PERROR("close");
 276                                                 }
 277                                                 sock = -1;
 278                                                 goto error;
 279                                         }
 280
 281                                         /*
 282                                          * Using message-based transmissions to ensure we don't
 283                                          * have to deal with partially received messages.
 284                                          */
 285                                         ret = lttng_fd_get(LTTNG_FD_APPS, 1);
 286                                         if (ret < 0) {
 287                                                 ERR("Exhausted file descriptors allowed for applications.");
 288                                                 free(ust_cmd);
 289                                                 ret = close(sock);
 290                                                 if (ret) {
 291                                                         PERROR("close");
 292                                                 }
 293                                                 sock = -1;
 294                                                 continue;
 295                                         }
 296
 297                                         health_code_update();
 298                                         ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
 299                                         if (ret < 0) {
 300                                                 free(ust_cmd);
 301                                                 /* Close socket of the application. */
 302                                                 ret = close(sock);
 303                                                 if (ret) {
 304                                                         PERROR("close");
 305                                                 }
 306                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 307                                                 sock = -1;
 308                                                 continue;
 309                                         }
 310                                         health_code_update();
 311
 312                                         ust_cmd->sock = sock;
 313                                         sock = -1;
 314
 315                                         DBG("UST registration received with pid:%d ppid:%d uid:%d"
 316                                                         " gid:%d sock:%d name:%s (version %d.%d)",
 317                                                         ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
 318                                                         ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
 319                                                         ust_cmd->sock, ust_cmd->reg_msg.name,
 320                                                         ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
 321
 322                                         /*
 323                                          * Lock free enqueue the registration request. The red pill
 324                                          * has been taken! This apps will be part of the *system*.
 325                                          */
 326                                         cds_wfcq_head_ptr_t head;
 327                                         head.h = &thread_state->ust_cmd_queue->head;
 328                                         cds_wfcq_enqueue(head,
 329                                                         &thread_state->ust_cmd_queue->tail,
 330                                                         &ust_cmd->node);
 331
 332                                         /*
 333                                          * Wake the registration queue futex. Implicit memory
 334                                          * barrier with the exchange in cds_wfcq_enqueue.
 335                                          */
 336                                         futex_nto1_wake(&thread_state->ust_cmd_queue->futex);
 337                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 338                                         ERR("Register apps socket poll error");
 339                                         goto error;
 340                                 } else {
 341                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 342                                         goto error;
 343                                 }
 344                         }
 345                 }
 346         }
 347
 348 exit:
 349 error:
 350         /* Notify that the registration thread is gone */
 351         notify_ust_apps(0, is_root);
 352
 353         ret = close(application_socket);
 354         if (ret) {
 355                 PERROR("Failed to close application registration socket");
 356         }
 357         if (sock >= 0) {
 358                 ret = close(sock);
 359                 if (ret) {
 360                         PERROR("Failed to close application socket");
 361                 }
 362                 lttng_fd_put(LTTNG_FD_APPS, 1);
 363         }
 364         unlink(the_config.apps_unix_sock_path.value);
 365
 366 error_poll_add:
 367         lttng_poll_clean(&events);
 368 error_listen:
 369 error_create_poll:
 370         DBG("UST Registration thread cleanup complete");
 371         if (err) {
 372                 health_error();
 373                 ERR("Health error occurred in %s", __func__);
 374         }
 375         health_unregister(the_health_sessiond);
 376         return NULL;
 377 }
 378
 379 static bool shutdown_application_registration_thread(void *data)
 380 {
 381         struct thread_state *thread_state = (struct thread_state *) data;
 382         const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);
 383
 384         return notify_thread_pipe(write_fd) == 1;
 385 }
 386
 387 struct lttng_thread *launch_application_registration_thread(
 388                 struct ust_cmd_queue *cmd_queue)
 389 {
 390         int ret;
 391         struct lttng_pipe *quit_pipe;
 392         struct thread_state *thread_state = NULL;
 393         struct lttng_thread *thread = NULL;
 394         const bool is_root = (getuid() == 0);
 395         int application_socket = -1;
 396
 397         thread_state = zmalloc<struct thread_state>();
 398         if (!thread_state) {
 399                 goto error_alloc;
 400         }
 401         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 402         if (!quit_pipe) {
 403                 goto error;
 404         }
 405         thread_state->quit_pipe = quit_pipe;
 406         thread_state->ust_cmd_queue = cmd_queue;
 407         application_socket = create_application_socket();
 408         if (application_socket < 0) {
 409                 goto error;
 410         }
 411         thread_state->application_socket = application_socket;
 412         sem_init(&thread_state->ready, 0, 0);
 413
 414         thread = lttng_thread_create("UST application registration",
 415                         thread_application_registration,
 416                         shutdown_application_registration_thread,
 417                         cleanup_application_registration_thread,
 418                         thread_state);
 419         if (!thread) {
 420                 goto error;
 421         }
 422         /*
 423          * The application registration thread now owns the application socket
 424          * and the global thread state. The thread state is used to wait for
 425          * the thread's status, but its ownership now belongs to the thread.
 426          */
 427         application_socket = -1;
 428         if (!wait_thread_status(thread_state)) {
 429                 thread_state = NULL;
 430                 goto error;
 431         }
 432
 433         /* Notify all applications to register. */
 434         ret = notify_ust_apps(1, is_root);
 435         if (ret < 0) {
 436                 ERR("Failed to notify applications or create the wait shared memory.\n"
 437                         "Execution continues but there might be problems for already\n"
 438                         "running applications that wishes to register.");
 439         }
 440
 441         return thread;
 442 error:
 443         lttng_thread_put(thread);
 444         cleanup_application_registration_thread(thread_state);
 445         if (application_socket >= 0) {
 446                 if (close(application_socket)) {
 447                         PERROR("Failed to close application registration socket");
 448                 }
 449         }
 450 error_alloc:
 451         return NULL;
 452 }