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 end;
  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 }
  84
  85 /*
  86  * Notify UST applications using the shm mmap futex.
  87  */
  88 static int notify_ust_apps(int active, bool is_root)
  89 {
  90         char *wait_shm_mmap;
  91
  92         DBG("Notifying applications of session daemon state: %d", active);
  93
  94         /* See shm.c for this call implying mmap, shm and futex calls */
  95         wait_shm_mmap = shm_ust_get_mmap(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_notifiers *notifiers = data;
 113
 114         lttng_pipe_destroy(notifiers->quit_pipe);
 115         free(notifiers);
 116 }
 117
 118 static void set_thread_status(struct thread_notifiers *notifiers, bool running)
 119 {
 120         DBG("Marking application registration thread's state as %s", running ? "running" : "error");
 121         notifiers->running = running;
 122         sem_post(&notifiers->ready);
 123 }
 124
 125 static bool wait_thread_status(struct thread_notifiers *notifiers)
 126 {
 127         DBG("Waiting for application registration thread to be ready");
 128         sem_wait(&notifiers->ready);
 129         if (notifiers->running) {
 130                 DBG("Application registration thread is ready");
 131         } else {
 132                 ERR("Initialization of application registration thread failed");
 133         }
 134
 135         return notifiers->running;
 136 }
 137
 138 static void thread_init_cleanup(void *data)
 139 {
 140         struct thread_notifiers *notifiers = data;
 141
 142         set_thread_status(notifiers, false);
 143 }
 144
 145 /*
 146  * This thread manage application registration.
 147  */
 148 static void *thread_application_registration(void *data)
 149 {
 150         int sock = -1, i, ret, pollfd, err = -1;
 151         int apps_sock = -1;
 152         uint32_t revents, nb_fd;
 153         struct lttng_poll_event events;
 154         /*
 155          * Gets allocated in this thread, enqueued to a global queue, dequeued
 156          * and freed in the manage apps thread.
 157          */
 158         struct ust_command *ust_cmd = NULL;
 159         const bool is_root = (getuid() == 0);
 160         struct thread_notifiers *notifiers = data;
 161         const int quit_pipe_read_fd = lttng_pipe_get_readfd(
 162                         notifiers->quit_pipe);
 163
 164         DBG("[thread] Manage application registration started");
 165
 166         pthread_cleanup_push(thread_init_cleanup, NULL);
 167         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);
 168
 169         apps_sock = create_application_socket();
 170         if (apps_sock < 0) {
 171                 goto error_listen;
 172         }
 173
 174         ret = lttcomm_listen_unix_sock(apps_sock);
 175         if (ret < 0) {
 176                 goto error_listen;
 177         }
 178
 179         set_thread_status(notifiers, true);
 180         pthread_cleanup_pop(0);
 181
 182         if (testpoint(sessiond_thread_registration_apps)) {
 183                 goto error_create_poll;
 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, apps_sock, 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         /* Notify all applications to register */
 208         ret = notify_ust_apps(1, is_root);
 209         if (ret < 0) {
 210                 ERR("Failed to notify applications or create the wait shared memory.\n"
 211                         "Execution continues but there might be problem for already\n"
 212                         "running applications that wishes to register.");
 213         }
 214
 215         while (1) {
 216                 DBG("Accepting application registration");
 217
 218                 /* Inifinite blocking call, waiting for transmission */
 219         restart:
 220                 health_poll_entry();
 221                 ret = lttng_poll_wait(&events, -1);
 222                 health_poll_exit();
 223                 if (ret < 0) {
 224                         /*
 225                          * Restart interrupted system call.
 226                          */
 227                         if (errno == EINTR) {
 228                                 goto restart;
 229                         }
 230                         goto error;
 231                 }
 232
 233                 nb_fd = ret;
 234
 235                 for (i = 0; i < nb_fd; i++) {
 236                         health_code_update();
 237
 238                         /* Fetch once the poll data */
 239                         revents = LTTNG_POLL_GETEV(&events, i);
 240                         pollfd = LTTNG_POLL_GETFD(&events, i);
 241
 242                         /* Thread quit pipe has been closed. Killing thread. */
 243                         if (pollfd == quit_pipe_read_fd) {
 244                                 err = 0;
 245                                 goto exit;
 246                         } else {
 247                                 /* Event on the registration socket */
 248                                 if (revents & LPOLLIN) {
 249                                         sock = lttcomm_accept_unix_sock(apps_sock);
 250                                         if (sock < 0) {
 251                                                 goto error;
 252                                         }
 253
 254                                         /*
 255                                          * Set socket timeout for both receiving and ending.
 256                                          * app_socket_timeout is in seconds, whereas
 257                                          * lttcomm_setsockopt_rcv_timeout and
 258                                          * lttcomm_setsockopt_snd_timeout expect msec as
 259                                          * parameter.
 260                                          */
 261                                         if (config.app_socket_timeout >= 0) {
 262                                                 (void) lttcomm_setsockopt_rcv_timeout(sock,
 263                                                                 config.app_socket_timeout * 1000);
 264                                                 (void) lttcomm_setsockopt_snd_timeout(sock,
 265                                                                 config.app_socket_timeout * 1000);
 266                                         }
 267
 268                                         /*
 269                                          * Set the CLOEXEC flag. Return code is useless because
 270                                          * either way, the show must go on.
 271                                          */
 272                                         (void) utils_set_fd_cloexec(sock);
 273
 274                                         /* Create UST registration command for enqueuing */
 275                                         ust_cmd = zmalloc(sizeof(struct ust_command));
 276                                         if (ust_cmd == NULL) {
 277                                                 PERROR("ust command zmalloc");
 278                                                 ret = close(sock);
 279                                                 if (ret) {
 280                                                         PERROR("close");
 281                                                 }
 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(&notifiers->ust_cmd_queue->head,
 331                                                         &notifiers->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(&notifiers->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         if (apps_sock >= 0) {
 356                 ret = close(apps_sock);
 357                 if (ret) {
 358                         PERROR("close");
 359                 }
 360         }
 361         if (sock >= 0) {
 362                 ret = close(sock);
 363                 if (ret) {
 364                         PERROR("close");
 365                 }
 366                 lttng_fd_put(LTTNG_FD_APPS, 1);
 367         }
 368         unlink(config.apps_unix_sock_path.value);
 369
 370 error_poll_add:
 371         lttng_poll_clean(&events);
 372 error_listen:
 373 error_create_poll:
 374         DBG("UST Registration thread cleanup complete");
 375         if (err) {
 376                 health_error();
 377                 ERR("Health error occurred in %s", __func__);
 378         }
 379         health_unregister(health_sessiond);
 380         return NULL;
 381 }
 382
 383 static bool shutdown_application_registration_thread(void *data)
 384 {
 385         struct thread_notifiers *notifiers = data;
 386         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 387
 388         return notify_thread_pipe(write_fd) == 1;
 389 }
 390
 391 struct lttng_thread *launch_application_registration_thread(
 392                 struct ust_cmd_queue *cmd_queue)
 393 {
 394         struct lttng_pipe *quit_pipe;
 395         struct thread_notifiers *notifiers = NULL;
 396         struct lttng_thread *thread;
 397
 398         notifiers = zmalloc(sizeof(*notifiers));
 399         if (!notifiers) {
 400                 goto error_alloc;
 401         }
 402         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 403         if (!quit_pipe) {
 404                 goto error;
 405         }
 406         notifiers->quit_pipe = quit_pipe;
 407         notifiers->ust_cmd_queue = cmd_queue;
 408         sem_init(&notifiers->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                         notifiers);
 415         if (!thread) {
 416                 goto error;
 417         }
 418         if (!wait_thread_status(notifiers)) {
 419                 lttng_thread_put(thread);
 420                 thread = NULL;
 421         }
 422         return thread;
 423 error:
 424         cleanup_application_registration_thread(notifiers);
 425 error_alloc:
 426         return NULL;
 427 }