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