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