src/bin/lttng-sessiond/register.c

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