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