src/bin/lttng-sessiond/register.c

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