src/bin/lttng-sessiond/session.c

   1 /*
   2  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <limits.h>
  20 #include <inttypes.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <urcu.h>
  26 #include <dirent.h>
  27 #include <sys/types.h>
  28
  29 #include <common/common.h>
  30 #include <common/sessiond-comm/sessiond-comm.h>
  31 #include <lttng/location-internal.h>
  32 #include "lttng-sessiond.h"
  33 #include "kernel.h"
  34
  35 #include "session.h"
  36 #include "utils.h"
  37 #include "trace-ust.h"
  38 #include "timer.h"
  39
  40 /*
  41  * NOTES:
  42  *
  43  * No ltt_session.lock is taken here because those data structure are widely
  44  * spread across the lttng-tools code base so before caling functions below
  45  * that can read/write a session, the caller MUST acquire the session lock
  46  * using session_lock() and session_unlock().
  47  */
  48
  49 /*
  50  * Init tracing session list.
  51  *
  52  * Please see session.h for more explanation and correct usage of the list.
  53  */
  54 static struct ltt_session_list ltt_session_list = {
  55         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  56         .lock = PTHREAD_MUTEX_INITIALIZER,
  57         .next_uuid = 0,
  58 };
  59
  60 /* These characters are forbidden in a session name. Used by validate_name. */
  61 static const char *forbidden_name_chars = "/";
  62
  63 /* Global hash table to keep the sessions, indexed by id. */
  64 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
  65
  66 /*
  67  * Validate the session name for forbidden characters.
  68  *
  69  * Return 0 on success else -1 meaning a forbidden char. has been found.
  70  */
  71 static int validate_name(const char *name)
  72 {
  73         int ret;
  74         char *tok, *tmp_name;
  75
  76         assert(name);
  77
  78         tmp_name = strdup(name);
  79         if (!tmp_name) {
  80                 /* ENOMEM here. */
  81                 ret = -1;
  82                 goto error;
  83         }
  84
  85         tok = strpbrk(tmp_name, forbidden_name_chars);
  86         if (tok) {
  87                 DBG("Session name %s contains a forbidden character", name);
  88                 /* Forbidden character has been found. */
  89                 ret = -1;
  90                 goto error;
  91         }
  92         ret = 0;
  93
  94 error:
  95         free(tmp_name);
  96         return ret;
  97 }
  98
  99 /*
 100  * Add a ltt_session structure to the global list.
 101  *
 102  * The caller MUST acquire the session list lock before.
 103  * Returns the unique identifier for the session.
 104  */
 105 static uint64_t add_session_list(struct ltt_session *ls)
 106 {
 107         assert(ls);
 108
 109         cds_list_add(&ls->list, &ltt_session_list.head);
 110         return ltt_session_list.next_uuid++;
 111 }
 112
 113 /*
 114  * Delete a ltt_session structure to the global list.
 115  *
 116  * The caller MUST acquire the session list lock before.
 117  */
 118 static void del_session_list(struct ltt_session *ls)
 119 {
 120         assert(ls);
 121
 122         cds_list_del(&ls->list);
 123 }
 124
 125 /*
 126  * Return a pointer to the session list.
 127  */
 128 struct ltt_session_list *session_get_list(void)
 129 {
 130         return &ltt_session_list;
 131 }
 132
 133 /*
 134  * Acquire session list lock
 135  */
 136 void session_lock_list(void)
 137 {
 138         pthread_mutex_lock(&ltt_session_list.lock);
 139 }
 140
 141 /*
 142  * Try to acquire session list lock
 143  */
 144 int session_trylock_list(void)
 145 {
 146         return pthread_mutex_trylock(&ltt_session_list.lock);
 147 }
 148
 149 /*
 150  * Release session list lock
 151  */
 152 void session_unlock_list(void)
 153 {
 154         pthread_mutex_unlock(&ltt_session_list.lock);
 155 }
 156
 157 /*
 158  * Get the session's consumer destination type.
 159  *
 160  * The caller must hold the session lock.
 161  */
 162 enum consumer_dst_type session_get_consumer_destination_type(
 163                 const struct ltt_session *session)
 164 {
 165         /*
 166          * The output information is duplicated in both of those session types.
 167          * Hence, it doesn't matter from which it is retrieved. However, it is
 168          * possible for only one of them to be set.
 169          */
 170         return session->kernel_session ?
 171                         session->kernel_session->consumer->type :
 172                         session->ust_session->consumer->type;
 173 }
 174
 175 /*
 176  * Get the session's consumer network hostname.
 177  * The caller must ensure that the destination is of type "net".
 178  *
 179  * The caller must hold the session lock.
 180  */
 181 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
 182 {
 183         const char *hostname = NULL;
 184         const struct consumer_output *output;
 185
 186         output = session->kernel_session ?
 187                         session->kernel_session->consumer :
 188                         session->ust_session->consumer;
 189
 190         /*
 191          * hostname is assumed to be the same for both control and data
 192          * connections.
 193          */
 194         switch (output->dst.net.control.dtype) {
 195         case LTTNG_DST_IPV4:
 196                 hostname = output->dst.net.control.dst.ipv4;
 197                 break;
 198         case LTTNG_DST_IPV6:
 199                 hostname = output->dst.net.control.dst.ipv6;
 200                 break;
 201         default:
 202                 abort();
 203         }
 204         return hostname;
 205 }
 206
 207 /*
 208  * Get the session's consumer network control and data ports.
 209  * The caller must ensure that the destination is of type "net".
 210  *
 211  * The caller must hold the session lock.
 212  */
 213 void session_get_net_consumer_ports(const struct ltt_session *session,
 214                 uint16_t *control_port, uint16_t *data_port)
 215 {
 216         const struct consumer_output *output;
 217
 218         output = session->kernel_session ?
 219                         session->kernel_session->consumer :
 220                         session->ust_session->consumer;
 221         *control_port = output->dst.net.control.port;
 222         *data_port = output->dst.net.data.port;
 223 }
 224
 225 /*
 226  * Get the location of the latest trace archive produced by a rotation.
 227  *
 228  * The caller must hold the session lock.
 229  */
 230 struct lttng_trace_archive_location *session_get_trace_archive_location(
 231                 struct ltt_session *session)
 232 {
 233         struct lttng_trace_archive_location *location = NULL;
 234
 235         if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED) {
 236                 goto end;
 237         }
 238
 239         switch (session_get_consumer_destination_type(session)) {
 240         case CONSUMER_DST_LOCAL:
 241                 location = lttng_trace_archive_location_local_create(
 242                                 session->rotation_chunk.current_rotate_path);
 243                 break;
 244         case CONSUMER_DST_NET:
 245         {
 246                 const char *hostname;
 247                 uint16_t control_port, data_port;
 248
 249                 hostname = session_get_net_consumer_hostname(session);
 250                 session_get_net_consumer_ports(session,
 251                                 &control_port,
 252                                 &data_port);
 253                 location = lttng_trace_archive_location_relay_create(
 254                                 hostname,
 255                                 LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP,
 256                                 control_port, data_port,
 257                                 session->rotation_chunk.current_rotate_path);
 258                 break;
 259         }
 260         default:
 261                 abort();
 262         }
 263 end:
 264         return location;
 265 }
 266
 267 /*
 268  * Allocate the ltt_sessions_ht_by_id HT.
 269  *
 270  * The session list lock must be held.
 271  */
 272 int ltt_sessions_ht_alloc(void)
 273 {
 274         int ret = 0;
 275
 276         DBG("Allocating ltt_sessions_ht_by_id");
 277         ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 278         if (!ltt_sessions_ht_by_id) {
 279                 ret = -1;
 280                 ERR("Failed to allocate ltt_sessions_ht_by_id");
 281                 goto end;
 282         }
 283 end:
 284         return ret;
 285 }
 286
 287 /*
 288  * Destroy the ltt_sessions_ht_by_id HT.
 289  *
 290  * The session list lock must be held.
 291  */
 292 static void ltt_sessions_ht_destroy(void)
 293 {
 294         if (!ltt_sessions_ht_by_id) {
 295                 return;
 296         }
 297         ht_cleanup_push(ltt_sessions_ht_by_id);
 298         ltt_sessions_ht_by_id = NULL;
 299 }
 300
 301 /*
 302  * Add a ltt_session to the ltt_sessions_ht_by_id.
 303  * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
 304  * The session list lock must be held.
 305  */
 306 static void add_session_ht(struct ltt_session *ls)
 307 {
 308         int ret;
 309
 310         assert(ls);
 311
 312         if (!ltt_sessions_ht_by_id) {
 313                 ret = ltt_sessions_ht_alloc();
 314                 if (ret) {
 315                         ERR("Error allocating the sessions HT");
 316                         goto end;
 317                 }
 318         }
 319         lttng_ht_node_init_u64(&ls->node, ls->id);
 320         lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
 321
 322 end:
 323         return;
 324 }
 325
 326 /*
 327  * Test if ltt_sessions_ht_by_id is empty.
 328  * Return 1 if empty, 0 if not empty.
 329  * The session list lock must be held.
 330  */
 331 static int ltt_sessions_ht_empty(void)
 332 {
 333         int ret;
 334
 335         if (!ltt_sessions_ht_by_id) {
 336                 ret = 1;
 337                 goto end;
 338         }
 339
 340         ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
 341 end:
 342         return ret;
 343 }
 344
 345 /*
 346  * Remove a ltt_session from the ltt_sessions_ht_by_id.
 347  * If empty, the ltt_sessions_ht_by_id HT is freed.
 348  * The session list lock must be held.
 349  */
 350 static void del_session_ht(struct ltt_session *ls)
 351 {
 352         struct lttng_ht_iter iter;
 353         int ret;
 354
 355         assert(ls);
 356         assert(ltt_sessions_ht_by_id);
 357
 358         iter.iter.node = &ls->node.node;
 359         ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
 360         assert(!ret);
 361
 362         if (ltt_sessions_ht_empty()) {
 363                 DBG("Empty ltt_sessions_ht_by_id, destroying it");
 364                 ltt_sessions_ht_destroy();
 365         }
 366 }
 367
 368 /*
 369  * Acquire session lock
 370  */
 371 void session_lock(struct ltt_session *session)
 372 {
 373         assert(session);
 374
 375         pthread_mutex_lock(&session->lock);
 376 }
 377
 378 /*
 379  * Release session lock
 380  */
 381 void session_unlock(struct ltt_session *session)
 382 {
 383         assert(session);
 384
 385         pthread_mutex_unlock(&session->lock);
 386 }
 387
 388 static
 389 void session_release(struct urcu_ref *ref)
 390 {
 391         int ret;
 392         struct ltt_ust_session *usess;
 393         struct ltt_kernel_session *ksess;
 394         struct ltt_session *session = container_of(ref, typeof(*session), ref);
 395
 396         usess = session->ust_session;
 397         ksess = session->kernel_session;
 398
 399         /* Clean kernel session teardown */
 400         kernel_destroy_session(ksess);
 401
 402         /* UST session teardown */
 403         if (usess) {
 404                 /* Close any relayd session */
 405                 consumer_output_send_destroy_relayd(usess->consumer);
 406
 407                 /* Destroy every UST application related to this session. */
 408                 ret = ust_app_destroy_trace_all(usess);
 409                 if (ret) {
 410                         ERR("Error in ust_app_destroy_trace_all");
 411                 }
 412
 413                 /* Clean up the rest. */
 414                 trace_ust_destroy_session(usess);
 415         }
 416
 417         /*
 418          * Must notify the kernel thread here to update it's poll set in order to
 419          * remove the channel(s)' fd just destroyed.
 420          */
 421         ret = notify_thread_pipe(kernel_poll_pipe[1]);
 422         if (ret < 0) {
 423                 PERROR("write kernel poll pipe");
 424         }
 425
 426         DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
 427         pthread_mutex_destroy(&session->lock);
 428
 429         consumer_output_put(session->consumer);
 430         snapshot_destroy(&session->snapshot);
 431         del_session_list(session);
 432         del_session_ht(session);
 433         free(session);
 434 }
 435
 436 /*
 437  * Acquire a reference to a session.
 438  * This function may fail (return false); its return value must be checked.
 439  */
 440 bool session_get(struct ltt_session *session)
 441 {
 442         return urcu_ref_get_unless_zero(&session->ref);
 443 }
 444
 445 /*
 446  * Release a reference to a session.
 447  */
 448 void session_put(struct ltt_session *session)
 449 {
 450         /*
 451          * The session list lock must be held as any session_put()
 452          * may cause the removal of the session from the session_list.
 453          */
 454         ASSERT_LOCKED(ltt_session_list.lock);
 455         assert(session->ref.refcount);
 456         urcu_ref_put(&session->ref, session_release);
 457 }
 458
 459 /*
 460  * Destroy a session.
 461  *
 462  * This method does not immediately release/free the session as other
 463  * components may still hold a reference to the session. However,
 464  * the session should no longer be presented to the user.
 465  *
 466  * Releases the session list's reference to the session
 467  * and marks it as destroyed. Iterations on the session list should be
 468  * mindful of the "destroyed" flag.
 469  */
 470 void session_destroy(struct ltt_session *session)
 471 {
 472         assert(!session->destroyed);
 473         session->destroyed = true;
 474         session_put(session);
 475 }
 476
 477 /*
 478  * Return a ltt_session structure ptr that matches name. If no session found,
 479  * NULL is returned. This must be called with the session list lock held using
 480  * session_lock_list and session_unlock_list.
 481  * A reference to the session is implicitly acquired by this function.
 482  */
 483 struct ltt_session *session_find_by_name(const char *name)
 484 {
 485         struct ltt_session *iter;
 486
 487         assert(name);
 488         ASSERT_LOCKED(ltt_session_list.lock);
 489
 490         DBG2("Trying to find session by name %s", name);
 491
 492         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
 493                 if (!strncmp(iter->name, name, NAME_MAX) &&
 494                                 !iter->destroyed) {
 495                         goto found;
 496                 }
 497         }
 498
 499         return NULL;
 500 found:
 501         return session_get(iter) ? iter : NULL;
 502 }
 503
 504 /*
 505  * Return an ltt_session that matches the id. If no session is found,
 506  * NULL is returned. This must be called with rcu_read_lock and
 507  * session list lock held (to guarantee the lifetime of the session).
 508  */
 509 struct ltt_session *session_find_by_id(uint64_t id)
 510 {
 511         struct lttng_ht_node_u64 *node;
 512         struct lttng_ht_iter iter;
 513         struct ltt_session *ls;
 514
 515         ASSERT_LOCKED(ltt_session_list.lock);
 516
 517         if (!ltt_sessions_ht_by_id) {
 518                 goto end;
 519         }
 520
 521         lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
 522         node = lttng_ht_iter_get_node_u64(&iter);
 523         if (node == NULL) {
 524                 goto end;
 525         }
 526         ls = caa_container_of(node, struct ltt_session, node);
 527
 528         DBG3("Session %" PRIu64 " found by id.", id);
 529         return session_get(ls) ? ls : NULL;
 530
 531 end:
 532         DBG3("Session %" PRIu64 " NOT found by id", id);
 533         return NULL;
 534 }
 535
 536 /*
 537  * Create a brand new session and add it to the session list.
 538  */
 539 int session_create(char *name, uid_t uid, gid_t gid)
 540 {
 541         int ret;
 542         struct ltt_session *new_session;
 543
 544         /* Allocate session data structure */
 545         new_session = zmalloc(sizeof(struct ltt_session));
 546         if (new_session == NULL) {
 547                 PERROR("zmalloc");
 548                 ret = LTTNG_ERR_FATAL;
 549                 goto error_malloc;
 550         }
 551
 552         urcu_ref_init(&new_session->ref);
 553
 554         /* Define session name */
 555         if (name != NULL) {
 556                 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
 557                         ret = LTTNG_ERR_FATAL;
 558                         goto error_asprintf;
 559                 }
 560         } else {
 561                 ERR("No session name given");
 562                 ret = LTTNG_ERR_FATAL;
 563                 goto error;
 564         }
 565
 566         ret = validate_name(name);
 567         if (ret < 0) {
 568                 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
 569                 goto error;
 570         }
 571
 572         ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
 573         if (ret < 0) {
 574                 if (errno == ENAMETOOLONG) {
 575                         new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
 576                 } else {
 577                         ret = LTTNG_ERR_FATAL;
 578                         goto error;
 579                 }
 580         }
 581
 582         /* Init kernel session */
 583         new_session->kernel_session = NULL;
 584         new_session->ust_session = NULL;
 585
 586         /* Init lock */
 587         pthread_mutex_init(&new_session->lock, NULL);
 588
 589         new_session->uid = uid;
 590         new_session->gid = gid;
 591
 592         ret = snapshot_init(&new_session->snapshot);
 593         if (ret < 0) {
 594                 ret = LTTNG_ERR_NOMEM;
 595                 goto error;
 596         }
 597
 598         new_session->rotation_pending_local = false;
 599         new_session->rotation_pending_relay = false;
 600         new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
 601
 602         new_session->rotation_pending_check_timer_enabled = false;
 603         new_session->rotation_schedule_timer_enabled = false;
 604
 605         /* Add new session to the session list */
 606         session_lock_list();
 607         new_session->id = add_session_list(new_session);
 608         /*
 609          * Add the new session to the ltt_sessions_ht_by_id.
 610          * No ownership is taken by the hash table; it is merely
 611          * a wrapper around the session list used for faster access
 612          * by session id.
 613          */
 614         add_session_ht(new_session);
 615         session_unlock_list();
 616
 617         /*
 618          * Consumer is let to NULL since the create_session_uri command will set it
 619          * up and, if valid, assign it to the session.
 620          */
 621         DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
 622                         name, new_session->id, new_session->uid, new_session->gid);
 623
 624         return LTTNG_OK;
 625
 626 error:
 627 error_asprintf:
 628         free(new_session);
 629
 630 error_malloc:
 631         return ret;
 632 }
 633
 634 /*
 635  * Check if the UID or GID match the session. Root user has access to all
 636  * sessions.
 637  */
 638 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
 639 {
 640         assert(session);
 641
 642         if (uid != session->uid && gid != session->gid && uid != 0) {
 643                 return 0;
 644         } else {
 645                 return 1;
 646         }
 647 }
 648
 649 /*
 650  * Set a session's rotation state and reset all associated state.
 651  *
 652  * This function resets the rotation state (check timers, pending
 653  * flags, etc.) and sets the result of the last rotation. The result
 654  * can be queries by a liblttng-ctl client.
 655  *
 656  * Be careful of the result passed to this function. For instance,
 657  * on failure to launch a rotation, a client will expect the rotation
 658  * state to be set to "NO_ROTATION". If an error occured while the
 659  * rotation was "ONGOING", result should be set to "ERROR", which will
 660  * allow a client to report it.
 661  *
 662  * Must be called with the session and session_list locks held.
 663  */
 664 int session_reset_rotation_state(struct ltt_session *session,
 665                 enum lttng_rotation_state result)
 666 {
 667         int ret = 0;
 668
 669         ASSERT_LOCKED(ltt_session_list.lock);
 670         ASSERT_LOCKED(session->lock);
 671
 672         session->rotation_pending_local = false;
 673         session->rotation_pending_relay = false;
 674         session->rotated_after_last_stop = false;
 675         session->rotation_state = result;
 676         if (session->rotation_pending_check_timer_enabled) {
 677                 ret = timer_session_rotation_pending_check_stop(session);
 678         }
 679         return ret;
 680 }