src/bin/lttng-sessiond/register.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *               2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License, version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <stddef.h>
  21 #include <stdlib.h>
  22 #include <urcu.h>
  23 #include <common/futex.h>
  24 #include <common/macros.h>
  25 #include <common/utils.h>
  26 #include <sys/stat.h>
  27
  28 #include "register.h"
  29 #include "lttng-sessiond.h"
  30 #include "testpoint.h"
  31 #include "health-sessiond.h"
  32 #include "fd-limit.h"
  33 #include "shm.h"
  34 #include "utils.h"
  35 #include "thread.h"
  36
  37 struct thread_state {
  38         struct lttng_pipe *quit_pipe;
  39         struct ust_cmd_queue *ust_cmd_queue;
  40         sem_t ready;
  41         bool running;
  42         int application_socket;
  43 };
  44
  45 /*
  46  * Creates the application socket.
  47  */
  48 static int create_application_socket(void)
  49 {
  50         int ret = 0;
  51         int apps_sock;
  52         const mode_t old_umask = umask(0);
  53
  54         /* Create the application unix socket */
  55         apps_sock = lttcomm_create_unix_sock(config.apps_unix_sock_path.value);
  56         if (apps_sock < 0) {
  57                 ERR("Create unix sock failed: %s", config.apps_unix_sock_path.value);
  58                 ret = -1;
  59                 goto end;
  60         }
  61
  62         /* Set the cloexec flag */
  63         ret = utils_set_fd_cloexec(apps_sock);
  64         if (ret < 0) {
  65                 ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
  66                                 "Continuing but note that the consumer daemon will have a "
  67                                 "reference to this socket on exec()", apps_sock);
  68         }
  69
  70         /* File permission MUST be 666 */
  71         ret = chmod(config.apps_unix_sock_path.value,
  72                         S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
  73         if (ret < 0) {
  74                 PERROR("Set file permissions failed on %s",
  75                                 config.apps_unix_sock_path.value);
  76                 goto error_close_socket;
  77         }
  78
  79         DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
  80         ret = apps_sock;
  81 end:
  82         umask(old_umask);
  83         return ret;
  84 error_close_socket:
  85         if (close(apps_sock)) {
  86                 PERROR("Failed to close application socket in error path");
  87         }
  88         apps_sock = -1;
  89         ret = -1;
  90         goto end;
  91 }
  92
  93 /*
  94  * Notify UST applications using the shm mmap futex.
  95  */
  96 static int notify_ust_apps(int active, bool is_root)
  97 {
  98         char *wait_shm_mmap;
  99
 100         DBG("Notifying applications of session daemon state: %d", active);
 101
 102         /* See shm.c for this call implying mmap, shm and futex calls */
 103         wait_shm_mmap = shm_ust_get_mmap(config.wait_shm_path.value, is_root);
 104         if (wait_shm_mmap == NULL) {
 105                 goto error;
 106         }
 107
 108         /* Wake waiting process */
 109         futex_wait_update((int32_t *) wait_shm_mmap, active);
 110
 111         /* Apps notified successfully */
 112         return 0;
 113
 114 error:
 115         return -1;
 116 }
 117
 118 static void cleanup_application_registration_thread(void *data)
 119 {
 120         struct thread_state *thread_state = data;
 121
 122         if (!data) {
 123                 return;
 124         }
 125
 126         lttng_pipe_destroy(thread_state->quit_pipe);
 127         free(thread_state);
 128 }
 129
 130 static void set_thread_status(struct thread_state *thread_state, bool running)
 131 {
 132         DBG("Marking application registration thread's state as %s", running ? "running" : "error");
 133         thread_state->running = running;
 134         sem_post(&thread_state->ready);
 135 }
 136
 137 static bool wait_thread_status(struct thread_state *thread_state)
 138 {
 139         DBG("Waiting for application registration thread to be ready");
 140         sem_wait(&thread_state->ready);
 141         if (thread_state->running) {
 142                 DBG("Application registration thread is ready");
 143         } else {
 144                 ERR("Initialization of application registration thread failed");
 145         }
 146
 147         return thread_state->running;
 148 }
 149
 150 static void thread_init_cleanup(void *data)
 151 {
 152         struct thread_state *thread_state = data;
 153
 154         set_thread_status(thread_state, false);
 155 }
 156
 157 /*
 158  * This thread manage application registration.
 159  */
 160 static void *thread_application_registration(void *data)
 161 {
 162         int sock = -1, i, ret, pollfd, err = -1;
 163         uint32_t revents, nb_fd;
 164         struct lttng_poll_event events;
 165         /*
 166          * Gets allocated in this thread, enqueued to a global queue, dequeued
 167          * and freed in the manage apps thread.
 168          */
 169         struct ust_command *ust_cmd = NULL;
 170         const bool is_root = (getuid() == 0);
 171         struct thread_state *thread_state = data;
 172         const int application_socket = thread_state->application_socket;
 173         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
 174                         thread_state->quit_pipe);
 175
 176         DBG("[thread] Manage application registration started");
 177
 178         pthread_cleanup_push(thread_init_cleanup, thread_state);
 179         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);
 180
 181         ret = lttcomm_listen_unix_sock(application_socket);
 182         if (ret < 0) {
 183                 goto error_listen;
 184         }
 185
 186         /*
 187          * Pass 2 as size here for the thread quit pipe and apps_sock. Nothing
 188          * more will be added to this poll set.
 189          */
 190         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
 191         if (ret < 0) {
 192                 goto error_create_poll;
 193         }
 194
 195         /* Add the application registration socket */
 196         ret = lttng_poll_add(&events, application_socket, LPOLLIN | LPOLLRDHUP);
 197         if (ret < 0) {
 198                 goto error_poll_add;
 199         }
 200
 201         /* Add the application registration socket */
 202         ret = lttng_poll_add(&events, quit_pipe_read_fd, LPOLLIN | LPOLLRDHUP);
 203         if (ret < 0) {
 204                 goto error_poll_add;
 205         }
 206
 207         set_thread_status(thread_state, true);
 208         pthread_cleanup_pop(0);
 209
 210         if (testpoint(sessiond_thread_registration_apps)) {
 211                 goto error_poll_add;
 212         }
 213
 214         while (1) {
 215                 DBG("Accepting application registration");
 216
 217                 /* Inifinite blocking call, waiting for transmission */
 218         restart:
 219                 health_poll_entry();
 220                 ret = lttng_poll_wait(&events, -1);
 221                 health_poll_exit();
 222                 if (ret < 0) {
 223                         /*
 224                          * Restart interrupted system call.
 225                          */
 226                         if (errno == EINTR) {
 227                                 goto restart;
 228                         }
 229                         goto error;
 230                 }
 231
 232                 nb_fd = ret;
 233
 234                 for (i = 0; i < nb_fd; i++) {
 235                         health_code_update();
 236
 237                         /* Fetch once the poll data */
 238                         revents = LTTNG_POLL_GETEV(&events, i);
 239                         pollfd = LTTNG_POLL_GETFD(&events, i);
 240
 241                         /* Thread quit pipe has been closed. Killing thread. */
 242                         if (pollfd == quit_pipe_read_fd) {
 243                                 err = 0;
 244                                 goto exit;
 245                         } else {
 246                                 /* Event on the registration socket */
 247                                 if (revents & LPOLLIN) {
 248                                         sock = lttcomm_accept_unix_sock(application_socket);
 249                                         if (sock < 0) {
 250                                                 goto error;
 251                                         }
 252
 253                                         /*
 254                                          * Set socket timeout for both receiving and ending.
 255                                          * app_socket_timeout is in seconds, whereas
 256                                          * lttcomm_setsockopt_rcv_timeout and
 257                                          * lttcomm_setsockopt_snd_timeout expect msec as
 258                                          * parameter.
 259                                          */
 260                                         if (config.app_socket_timeout >= 0) {
 261                                                 (void) lttcomm_setsockopt_rcv_timeout(sock,
 262                                                                 config.app_socket_timeout * 1000);
 263                                                 (void) lttcomm_setsockopt_snd_timeout(sock,
 264                                                                 config.app_socket_timeout * 1000);
 265                                         }
 266
 267                                         /*
 268                                          * Set the CLOEXEC flag. Return code is useless because
 269                                          * either way, the show must go on.
 270                                          */
 271                                         (void) utils_set_fd_cloexec(sock);
 272
 273                                         /* Create UST registration command for enqueuing */
 274                                         ust_cmd = zmalloc(sizeof(struct ust_command));
 275                                         if (ust_cmd == NULL) {
 276                                                 PERROR("ust command zmalloc");
 277                                                 ret = close(sock);
 278                                                 if (ret) {
 279                                                         PERROR("close");
 280                                                 }
 281                                                 sock = -1;
 282                                                 goto error;
 283                                         }
 284
 285                                         /*
 286                                          * Using message-based transmissions to ensure we don't
 287                                          * have to deal with partially received messages.
 288                                          */
 289                                         ret = lttng_fd_get(LTTNG_FD_APPS, 1);
 290                                         if (ret < 0) {
 291                                                 ERR("Exhausted file descriptors allowed for applications.");
 292                                                 free(ust_cmd);
 293                                                 ret = close(sock);
 294                                                 if (ret) {
 295                                                         PERROR("close");
 296                                                 }
 297                                                 sock = -1;
 298                                                 continue;
 299                                         }
 300
 301                                         health_code_update();
 302                                         ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
 303                                         if (ret < 0) {
 304                                                 free(ust_cmd);
 305                                                 /* Close socket of the application. */
 306                                                 ret = close(sock);
 307                                                 if (ret) {
 308                                                         PERROR("close");
 309                                                 }
 310                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 311                                                 sock = -1;
 312                                                 continue;
 313                                         }
 314                                         health_code_update();
 315
 316                                         ust_cmd->sock = sock;
 317                                         sock = -1;
 318
 319                                         DBG("UST registration received with pid:%d ppid:%d uid:%d"
 320                                                         " gid:%d sock:%d name:%s (version %d.%d)",
 321                                                         ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
 322                                                         ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
 323                                                         ust_cmd->sock, ust_cmd->reg_msg.name,
 324                                                         ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
 325
 326                                         /*
 327                                          * Lock free enqueue the registration request. The red pill
 328                                          * has been taken! This apps will be part of the *system*.
 329                                          */
 330                                         cds_wfcq_enqueue(&thread_state->ust_cmd_queue->head,
 331                                                         &thread_state->ust_cmd_queue->tail,
 332                                                         &ust_cmd->node);
 333
 334                                         /*
 335                                          * Wake the registration queue futex. Implicit memory
 336                                          * barrier with the exchange in cds_wfcq_enqueue.
 337                                          */
 338                                         futex_nto1_wake(&thread_state->ust_cmd_queue->futex);
 339                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 340                                         ERR("Register apps socket poll error");
 341                                         goto error;
 342                                 } else {
 343                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 344                                         goto error;
 345                                 }
 346                         }
 347                 }
 348         }
 349
 350 exit:
 351 error:
 352         /* Notify that the registration thread is gone */
 353         notify_ust_apps(0, is_root);
 354
 355         ret = close(application_socket);
 356         if (ret) {
 357                 PERROR("Failed to close application registration socket");
 358         }
 359         if (sock >= 0) {
 360                 ret = close(sock);
 361                 if (ret) {
 362                         PERROR("Failed to close application socket");
 363                 }
 364                 lttng_fd_put(LTTNG_FD_APPS, 1);
 365         }
 366         unlink(config.apps_unix_sock_path.value);
 367
 368 error_poll_add:
 369         lttng_poll_clean(&events);
 370 error_listen:
 371 error_create_poll:
 372         DBG("UST Registration thread cleanup complete");
 373         if (err) {
 374                 health_error();
 375                 ERR("Health error occurred in %s", __func__);
 376         }
 377         health_unregister(health_sessiond);
 378         return NULL;
 379 }
 380
 381 static bool shutdown_application_registration_thread(void *data)
 382 {
 383         struct thread_state *thread_state = data;
 384         const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);
 385
 386         return notify_thread_pipe(write_fd) == 1;
 387 }
 388
 389 struct lttng_thread *launch_application_registration_thread(
 390                 struct ust_cmd_queue *cmd_queue)
 391 {
 392         int ret;
 393         struct lttng_pipe *quit_pipe;
 394         struct thread_state *thread_state = NULL;
 395         struct lttng_thread *thread = NULL;
 396         const bool is_root = (getuid() == 0);
 397         int application_socket = -1;
 398
 399         thread_state = zmalloc(sizeof(*thread_state));
 400         if (!thread_state) {
 401                 goto error_alloc;
 402         }
 403         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 404         if (!quit_pipe) {
 405                 goto error;
 406         }
 407         thread_state->quit_pipe = quit_pipe;
 408         thread_state->ust_cmd_queue = cmd_queue;
 409         application_socket = create_application_socket();
 410         if (application_socket < 0) {
 411                 goto error;
 412         }
 413         thread_state->application_socket = application_socket;
 414         sem_init(&thread_state->ready, 0, 0);
 415
 416         thread = lttng_thread_create("UST application registration",
 417                         thread_application_registration,
 418                         shutdown_application_registration_thread,
 419                         cleanup_application_registration_thread,
 420                         thread_state);
 421         if (!thread) {
 422                 goto error;
 423         }
 424         /*
 425          * The application registration thread now owns the application socket
 426          * and the global thread state. The thread state is used to wait for
 427          * the thread's status, but its ownership now belongs to the thread.
 428          */
 429         application_socket = -1;
 430         if (!wait_thread_status(thread_state)) {
 431                 thread_state = NULL;
 432                 goto error;
 433         }
 434
 435         /* Notify all applications to register. */
 436         ret = notify_ust_apps(1, is_root);
 437         if (ret < 0) {
 438                 ERR("Failed to notify applications or create the wait shared memory.\n"
 439                         "Execution continues but there might be problems for already\n"
 440                         "running applications that wishes to register.");
 441         }
 442
 443         return thread;
 444 error:
 445         lttng_thread_put(thread);
 446         cleanup_application_registration_thread(thread_state);
 447         if (application_socket >= 0) {
 448                 if (close(application_socket)) {
 449                         PERROR("Failed to close application registration socket");
 450                 }
 451         }
 452 error_alloc:
 453         return NULL;
 454 }