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 "fd-limit.hpp"
  11 #include "health-sessiond.hpp"
  12 #include "lttng-sessiond.hpp"
  13 #include "register.hpp"
  14 #include "testpoint.hpp"
  15 #include "thread.hpp"
  16 #include "utils.hpp"
  17
  18 #include <common/futex.hpp>
  19 #include <common/macros.hpp>
  20 #include <common/shm.hpp>
  21 #include <common/utils.hpp>
  22
  23 #include <stddef.h>
  24 #include <stdlib.h>
  25 #include <sys/stat.h>
  26 #include <urcu.h>
  27
  28 namespace {
  29 struct thread_state {
  30         struct lttng_pipe *quit_pipe;
  31         struct ust_cmd_queue *ust_cmd_queue;
  32         sem_t ready;
  33         bool running;
  34         int application_socket;
  35 };
  36 } /* namespace */
  37
  38 /*
  39  * Creates the application socket.
  40  */
  41 static int create_application_socket()
  42 {
  43         int ret = 0;
  44         int apps_sock;
  45
  46         /* Create the application unix socket */
  47         apps_sock = lttcomm_create_unix_sock(the_config.apps_unix_sock_path.value);
  48         if (apps_sock < 0) {
  49                 ERR("Create unix sock failed: %s", the_config.apps_unix_sock_path.value);
  50                 ret = -1;
  51                 goto end;
  52         }
  53
  54         /* Set the cloexec flag */
  55         ret = utils_set_fd_cloexec(apps_sock);
  56         if (ret < 0) {
  57                 ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
  58                     "Continuing but note that the consumer daemon will have a "
  59                     "reference to this socket on exec()",
  60                     apps_sock);
  61         }
  62
  63         /* File permission MUST be 666 */
  64         ret = chmod(the_config.apps_unix_sock_path.value,
  65                     S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
  66         if (ret < 0) {
  67                 PERROR("Set file permissions failed on %s", 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(the_config.wait_shm_path.value, is_root);
  95         if (wait_shm_mmap == nullptr) {
  96                 goto error;
  97         }
  98
  99         /* Wake waiting process */
 100         futex_wait_update((int32_t *) wait_shm_mmap, active);
 101
 102         /* Apps notified successfully */
 103         return 0;
 104
 105 error:
 106         return -1;
 107 }
 108
 109 static void cleanup_application_registration_thread(void *data)
 110 {
 111         struct thread_state *thread_state = (struct thread_state *) data;
 112
 113         if (!data) {
 114                 return;
 115         }
 116
 117         lttng_pipe_destroy(thread_state->quit_pipe);
 118         free(thread_state);
 119 }
 120
 121 static void set_thread_status(struct thread_state *thread_state, bool running)
 122 {
 123         DBG("Marking application registration thread's state as %s", running ? "running" : "error");
 124         thread_state->running = running;
 125         sem_post(&thread_state->ready);
 126 }
 127
 128 static bool wait_thread_status(struct thread_state *thread_state)
 129 {
 130         DBG("Waiting for application registration thread to be ready");
 131         sem_wait(&thread_state->ready);
 132         if (thread_state->running) {
 133                 DBG("Application registration thread is ready");
 134         } else {
 135                 ERR("Initialization of application registration thread failed");
 136         }
 137
 138         return thread_state->running;
 139 }
 140
 141 static void thread_init_cleanup(void *data)
 142 {
 143         struct thread_state *thread_state = (struct thread_state *) data;
 144
 145         set_thread_status(thread_state, false);
 146 }
 147
 148 /*
 149  * This thread manage application registration.
 150  */
 151 static void *thread_application_registration(void *data)
 152 {
 153         int sock = -1, i, ret, err = -1;
 154         uint32_t nb_fd;
 155         struct lttng_poll_event events;
 156         /*
 157          * Gets allocated in this thread, enqueued to a global queue, dequeued
 158          * and freed in the manage apps thread.
 159          */
 160         struct ust_command *ust_cmd = nullptr;
 161         const bool is_root = (getuid() == 0);
 162         struct thread_state *thread_state = (struct thread_state *) data;
 163         const int application_socket = thread_state->application_socket;
 164         const auto thread_quit_pipe_fd = lttng_pipe_get_readfd(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(the_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, thread_quit_pipe_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 (true) {
 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                         const auto revents = LTTNG_POLL_GETEV(&events, i);
 229                         const auto pollfd = LTTNG_POLL_GETFD(&events, i);
 230
 231                         /* Activity on thread quit pipe, closing. */
 232                         if (pollfd == thread_quit_pipe_fd) {
 233                                 err = 0;
 234                                 goto exit;
 235                         }
 236
 237                         /* Event on the registration socket. */
 238                         if (revents & LPOLLIN) {
 239                                 sock = lttcomm_accept_unix_sock(application_socket);
 240                                 if (sock < 0) {
 241                                         goto error;
 242                                 }
 243
 244                                 /*
 245                                  * Set socket timeout for both receiving and ending.
 246                                  * app_socket_timeout is in seconds, whereas
 247                                  * lttcomm_setsockopt_rcv_timeout and
 248                                  * lttcomm_setsockopt_snd_timeout expect msec as
 249                                  * parameter.
 250                                  */
 251                                 if (the_config.app_socket_timeout >= 0) {
 252                                         (void) lttcomm_setsockopt_rcv_timeout(
 253                                                 sock, the_config.app_socket_timeout * 1000);
 254                                         (void) lttcomm_setsockopt_snd_timeout(
 255                                                 sock, the_config.app_socket_timeout * 1000);
 256                                 }
 257
 258                                 /*
 259                                  * Set the CLOEXEC flag. Return code is useless because
 260                                  * either way, the show must go on.
 261                                  */
 262                                 (void) utils_set_fd_cloexec(sock);
 263
 264                                 /* Create UST registration command for enqueuing */
 265                                 ust_cmd = zmalloc<ust_command>();
 266                                 if (ust_cmd == nullptr) {
 267                                         PERROR("ust command zmalloc");
 268                                         ret = close(sock);
 269                                         if (ret) {
 270                                                 PERROR("close");
 271                                         }
 272                                         sock = -1;
 273                                         goto error;
 274                                 }
 275
 276                                 /*
 277                                  * Using message-based transmissions to ensure we don't
 278                                  * have to deal with partially received messages.
 279                                  */
 280                                 ret = lttng_fd_get(LTTNG_FD_APPS, 1);
 281                                 if (ret < 0) {
 282                                         ERR("Exhausted file descriptors allowed for applications.");
 283                                         free(ust_cmd);
 284                                         ret = close(sock);
 285                                         if (ret) {
 286                                                 PERROR("close");
 287                                         }
 288                                         sock = -1;
 289                                         continue;
 290                                 }
 291
 292                                 health_code_update();
 293                                 ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
 294                                 if (ret < 0) {
 295                                         free(ust_cmd);
 296                                         /* Close socket of the application. */
 297                                         ret = close(sock);
 298                                         if (ret) {
 299                                                 PERROR("close");
 300                                         }
 301                                         lttng_fd_put(LTTNG_FD_APPS, 1);
 302                                         sock = -1;
 303                                         continue;
 304                                 }
 305                                 health_code_update();
 306
 307                                 ust_cmd->sock = sock;
 308                                 sock = -1;
 309
 310                                 DBG("UST registration received with pid:%d ppid:%d uid:%d"
 311                                     " gid:%d sock:%d name:%s (version %d.%d)",
 312                                     ust_cmd->reg_msg.pid,
 313                                     ust_cmd->reg_msg.ppid,
 314                                     ust_cmd->reg_msg.uid,
 315                                     ust_cmd->reg_msg.gid,
 316                                     ust_cmd->sock,
 317                                     ust_cmd->reg_msg.name,
 318                                     ust_cmd->reg_msg.major,
 319                                     ust_cmd->reg_msg.minor);
 320
 321                                 /*
 322                                  * Lock free enqueue the registration request. The red pill
 323                                  * has been taken! This apps will be part of the *system*.
 324                                  */
 325                                 cds_wfcq_head_ptr_t head;
 326                                 head.h = &thread_state->ust_cmd_queue->head;
 327                                 cds_wfcq_enqueue(
 328                                         head, &thread_state->ust_cmd_queue->tail, &ust_cmd->node);
 329
 330                                 /*
 331                                  * Wake the registration queue futex. Implicit memory
 332                                  * barrier with the exchange in cds_wfcq_enqueue.
 333                                  */
 334                                 futex_nto1_wake(&thread_state->ust_cmd_queue->futex);
 335                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 336                                 ERR("Register apps socket poll error");
 337                                 goto error;
 338                         } else {
 339                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 340                                 goto error;
 341                         }
 342                 }
 343         }
 344
 345 exit:
 346 error:
 347         /* Notify that the registration thread is gone */
 348         notify_ust_apps(0, is_root);
 349
 350         ret = close(application_socket);
 351         if (ret) {
 352                 PERROR("Failed to close application registration socket");
 353         }
 354         if (sock >= 0) {
 355                 ret = close(sock);
 356                 if (ret) {
 357                         PERROR("Failed to close application socket");
 358                 }
 359                 lttng_fd_put(LTTNG_FD_APPS, 1);
 360         }
 361         unlink(the_config.apps_unix_sock_path.value);
 362
 363 error_poll_add:
 364         lttng_poll_clean(&events);
 365 error_listen:
 366 error_create_poll:
 367         DBG("UST Registration thread cleanup complete");
 368         if (err) {
 369                 health_error();
 370                 ERR("Health error occurred in %s", __func__);
 371         }
 372         health_unregister(the_health_sessiond);
 373         return nullptr;
 374 }
 375
 376 static bool shutdown_application_registration_thread(void *data)
 377 {
 378         struct thread_state *thread_state = (struct thread_state *) data;
 379         const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);
 380
 381         return notify_thread_pipe(write_fd) == 1;
 382 }
 383
 384 struct lttng_thread *launch_application_registration_thread(struct ust_cmd_queue *cmd_queue)
 385 {
 386         int ret;
 387         struct lttng_pipe *quit_pipe;
 388         struct thread_state *thread_state = nullptr;
 389         struct lttng_thread *thread = nullptr;
 390         const bool is_root = (getuid() == 0);
 391         int application_socket = -1;
 392
 393         thread_state = zmalloc<struct thread_state>();
 394         if (!thread_state) {
 395                 goto error_alloc;
 396         }
 397         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 398         if (!quit_pipe) {
 399                 goto error;
 400         }
 401         thread_state->quit_pipe = quit_pipe;
 402         thread_state->ust_cmd_queue = cmd_queue;
 403         application_socket = create_application_socket();
 404         if (application_socket < 0) {
 405                 goto error;
 406         }
 407         thread_state->application_socket = application_socket;
 408         sem_init(&thread_state->ready, 0, 0);
 409
 410         thread = lttng_thread_create("UST application registration",
 411                                      thread_application_registration,
 412                                      shutdown_application_registration_thread,
 413                                      cleanup_application_registration_thread,
 414                                      thread_state);
 415         if (!thread) {
 416                 goto error;
 417         }
 418         /*
 419          * The application registration thread now owns the application socket
 420          * and the global thread state. The thread state is used to wait for
 421          * the thread's status, but its ownership now belongs to the thread.
 422          */
 423         application_socket = -1;
 424         if (!wait_thread_status(thread_state)) {
 425                 thread_state = nullptr;
 426                 goto error;
 427         }
 428
 429         /* Notify all applications to register. */
 430         ret = notify_ust_apps(1, is_root);
 431         if (ret < 0) {
 432                 ERR("Failed to notify applications or create the wait shared memory.\n"
 433                     "Execution continues but there might be problems for already\n"
 434                     "running applications that wishes to register.");
 435         }
 436
 437         return thread;
 438 error:
 439         lttng_thread_put(thread);
 440         cleanup_application_registration_thread(thread_state);
 441         if (application_socket >= 0) {
 442                 if (close(application_socket)) {
 443                         PERROR("Failed to close application registration socket");
 444                 }
 445         }
 446 error_alloc:
 447         return nullptr;
 448 }