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