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 #include <pthread.h>
  29
  30 #include <common/common.h>
  31 #include <common/sessiond-comm/sessiond-comm.h>
  32 #include <lttng/location-internal.h>
  33 #include "lttng-sessiond.h"
  34 #include "kernel.h"
  35
  36 #include "session.h"
  37 #include "utils.h"
  38 #include "trace-ust.h"
  39 #include "timer.h"
  40
  41 /*
  42  * NOTES:
  43  *
  44  * No ltt_session.lock is taken here because those data structure are widely
  45  * spread across the lttng-tools code base so before caling functions below
  46  * that can read/write a session, the caller MUST acquire the session lock
  47  * using session_lock() and session_unlock().
  48  */
  49
  50 /*
  51  * Init tracing session list.
  52  *
  53  * Please see session.h for more explanation and correct usage of the list.
  54  */
  55 static struct ltt_session_list ltt_session_list = {
  56         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  57         .lock = PTHREAD_MUTEX_INITIALIZER,
  58         .removal_cond = PTHREAD_COND_INITIALIZER,
  59         .next_uuid = 0,
  60 };
  61
  62 /* These characters are forbidden in a session name. Used by validate_name. */
  63 static const char *forbidden_name_chars = "/";
  64
  65 /* Global hash table to keep the sessions, indexed by id. */
  66 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
  67
  68 /*
  69  * Validate the session name for forbidden characters.
  70  *
  71  * Return 0 on success else -1 meaning a forbidden char. has been found.
  72  */
  73 static int validate_name(const char *name)
  74 {
  75         int ret;
  76         char *tok, *tmp_name;
  77
  78         assert(name);
  79
  80         tmp_name = strdup(name);
  81         if (!tmp_name) {
  82                 /* ENOMEM here. */
  83                 ret = -1;
  84                 goto error;
  85         }
  86
  87         tok = strpbrk(tmp_name, forbidden_name_chars);
  88         if (tok) {
  89                 DBG("Session name %s contains a forbidden character", name);
  90                 /* Forbidden character has been found. */
  91                 ret = -1;
  92                 goto error;
  93         }
  94         ret = 0;
  95
  96 error:
  97         free(tmp_name);
  98         return ret;
  99 }
 100
 101 /*
 102  * Add a ltt_session structure to the global list.
 103  *
 104  * The caller MUST acquire the session list lock before.
 105  * Returns the unique identifier for the session.
 106  */
 107 static uint64_t add_session_list(struct ltt_session *ls)
 108 {
 109         assert(ls);
 110
 111         cds_list_add(&ls->list, &ltt_session_list.head);
 112         return ltt_session_list.next_uuid++;
 113 }
 114
 115 /*
 116  * Delete a ltt_session structure to the global list.
 117  *
 118  * The caller MUST acquire the session list lock before.
 119  */
 120 static void del_session_list(struct ltt_session *ls)
 121 {
 122         assert(ls);
 123
 124         cds_list_del(&ls->list);
 125 }
 126
 127 /*
 128  * Return a pointer to the session list.
 129  */
 130 struct ltt_session_list *session_get_list(void)
 131 {
 132         return &ltt_session_list;
 133 }
 134
 135 /*
 136  * Returns once the session list is empty.
 137  */
 138 void session_list_wait_empty(void)
 139 {
 140         pthread_mutex_lock(&ltt_session_list.lock);
 141         while (!cds_list_empty(&ltt_session_list.head)) {
 142                 pthread_cond_wait(&ltt_session_list.removal_cond,
 143                                 &ltt_session_list.lock);
 144         }
 145         pthread_mutex_unlock(&ltt_session_list.lock);
 146 }
 147
 148 /*
 149  * Acquire session list lock
 150  */
 151 void session_lock_list(void)
 152 {
 153         pthread_mutex_lock(&ltt_session_list.lock);
 154 }
 155
 156 /*
 157  * Try to acquire session list lock
 158  */
 159 int session_trylock_list(void)
 160 {
 161         return pthread_mutex_trylock(&ltt_session_list.lock);
 162 }
 163
 164 /*
 165  * Release session list lock
 166  */
 167 void session_unlock_list(void)
 168 {
 169         pthread_mutex_unlock(&ltt_session_list.lock);
 170 }
 171
 172 /*
 173  * Get the session's consumer destination type.
 174  *
 175  * The caller must hold the session lock.
 176  */
 177 enum consumer_dst_type session_get_consumer_destination_type(
 178                 const struct ltt_session *session)
 179 {
 180         /*
 181          * The output information is duplicated in both of those session types.
 182          * Hence, it doesn't matter from which it is retrieved. However, it is
 183          * possible for only one of them to be set.
 184          */
 185         return session->kernel_session ?
 186                         session->kernel_session->consumer->type :
 187                         session->ust_session->consumer->type;
 188 }
 189
 190 /*
 191  * Get the session's consumer network hostname.
 192  * The caller must ensure that the destination is of type "net".
 193  *
 194  * The caller must hold the session lock.
 195  */
 196 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
 197 {
 198         const char *hostname = NULL;
 199         const struct consumer_output *output;
 200
 201         output = session->kernel_session ?
 202                         session->kernel_session->consumer :
 203                         session->ust_session->consumer;
 204
 205         /*
 206          * hostname is assumed to be the same for both control and data
 207          * connections.
 208          */
 209         switch (output->dst.net.control.dtype) {
 210         case LTTNG_DST_IPV4:
 211                 hostname = output->dst.net.control.dst.ipv4;
 212                 break;
 213         case LTTNG_DST_IPV6:
 214                 hostname = output->dst.net.control.dst.ipv6;
 215                 break;
 216         default:
 217                 abort();
 218         }
 219         return hostname;
 220 }
 221
 222 /*
 223  * Get the session's consumer network control and data ports.
 224  * The caller must ensure that the destination is of type "net".
 225  *
 226  * The caller must hold the session lock.
 227  */
 228 void session_get_net_consumer_ports(const struct ltt_session *session,
 229                 uint16_t *control_port, uint16_t *data_port)
 230 {
 231         const struct consumer_output *output;
 232
 233         output = session->kernel_session ?
 234                         session->kernel_session->consumer :
 235                         session->ust_session->consumer;
 236         *control_port = output->dst.net.control.port;
 237         *data_port = output->dst.net.data.port;
 238 }
 239
 240 /*
 241  * Get the location of the latest trace archive produced by a rotation.
 242  *
 243  * The caller must hold the session lock.
 244  */
 245 struct lttng_trace_archive_location *session_get_trace_archive_location(
 246                 struct ltt_session *session)
 247 {
 248         struct lttng_trace_archive_location *location = NULL;
 249
 250         if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED) {
 251                 goto end;
 252         }
 253
 254         switch (session_get_consumer_destination_type(session)) {
 255         case CONSUMER_DST_LOCAL:
 256                 location = lttng_trace_archive_location_local_create(
 257                                 session->rotation_chunk.current_rotate_path);
 258                 break;
 259         case CONSUMER_DST_NET:
 260         {
 261                 const char *hostname;
 262                 uint16_t control_port, data_port;
 263
 264                 hostname = session_get_net_consumer_hostname(session);
 265                 session_get_net_consumer_ports(session,
 266                                 &control_port,
 267                                 &data_port);
 268                 location = lttng_trace_archive_location_relay_create(
 269                                 hostname,
 270                                 LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP,
 271                                 control_port, data_port,
 272                                 session->rotation_chunk.current_rotate_path);
 273                 break;
 274         }
 275         default:
 276                 abort();
 277         }
 278 end:
 279         return location;
 280 }
 281
 282 /*
 283  * Allocate the ltt_sessions_ht_by_id HT.
 284  *
 285  * The session list lock must be held.
 286  */
 287 int ltt_sessions_ht_alloc(void)
 288 {
 289         int ret = 0;
 290
 291         DBG("Allocating ltt_sessions_ht_by_id");
 292         ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 293         if (!ltt_sessions_ht_by_id) {
 294                 ret = -1;
 295                 ERR("Failed to allocate ltt_sessions_ht_by_id");
 296                 goto end;
 297         }
 298 end:
 299         return ret;
 300 }
 301
 302 /*
 303  * Destroy the ltt_sessions_ht_by_id HT.
 304  *
 305  * The session list lock must be held.
 306  */
 307 static void ltt_sessions_ht_destroy(void)
 308 {
 309         if (!ltt_sessions_ht_by_id) {
 310                 return;
 311         }
 312         ht_cleanup_push(ltt_sessions_ht_by_id);
 313         ltt_sessions_ht_by_id = NULL;
 314 }
 315
 316 /*
 317  * Add a ltt_session to the ltt_sessions_ht_by_id.
 318  * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
 319  * The session list lock must be held.
 320  */
 321 static void add_session_ht(struct ltt_session *ls)
 322 {
 323         int ret;
 324
 325         assert(ls);
 326
 327         if (!ltt_sessions_ht_by_id) {
 328                 ret = ltt_sessions_ht_alloc();
 329                 if (ret) {
 330                         ERR("Error allocating the sessions HT");
 331                         goto end;
 332                 }
 333         }
 334         lttng_ht_node_init_u64(&ls->node, ls->id);
 335         lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
 336
 337 end:
 338         return;
 339 }
 340
 341 /*
 342  * Test if ltt_sessions_ht_by_id is empty.
 343  * Return 1 if empty, 0 if not empty.
 344  * The session list lock must be held.
 345  */
 346 static int ltt_sessions_ht_empty(void)
 347 {
 348         int ret;
 349
 350         if (!ltt_sessions_ht_by_id) {
 351                 ret = 1;
 352                 goto end;
 353         }
 354
 355         ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
 356 end:
 357         return ret;
 358 }
 359
 360 /*
 361  * Remove a ltt_session from the ltt_sessions_ht_by_id.
 362  * If empty, the ltt_sessions_ht_by_id HT is freed.
 363  * The session list lock must be held.
 364  */
 365 static void del_session_ht(struct ltt_session *ls)
 366 {
 367         struct lttng_ht_iter iter;
 368         int ret;
 369
 370         assert(ls);
 371         assert(ltt_sessions_ht_by_id);
 372
 373         iter.iter.node = &ls->node.node;
 374         ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
 375         assert(!ret);
 376
 377         if (ltt_sessions_ht_empty()) {
 378                 DBG("Empty ltt_sessions_ht_by_id, destroying it");
 379                 ltt_sessions_ht_destroy();
 380         }
 381 }
 382
 383 /*
 384  * Acquire session lock
 385  */
 386 void session_lock(struct ltt_session *session)
 387 {
 388         assert(session);
 389
 390         pthread_mutex_lock(&session->lock);
 391 }
 392
 393 /*
 394  * Release session lock
 395  */
 396 void session_unlock(struct ltt_session *session)
 397 {
 398         assert(session);
 399
 400         pthread_mutex_unlock(&session->lock);
 401 }
 402
 403 static
 404 void session_release(struct urcu_ref *ref)
 405 {
 406         int ret;
 407         struct ltt_ust_session *usess;
 408         struct ltt_kernel_session *ksess;
 409         struct ltt_session *session = container_of(ref, typeof(*session), ref);
 410
 411         usess = session->ust_session;
 412         ksess = session->kernel_session;
 413
 414         /* Clean kernel session teardown */
 415         kernel_destroy_session(ksess);
 416
 417         /* UST session teardown */
 418         if (usess) {
 419                 /* Close any relayd session */
 420                 consumer_output_send_destroy_relayd(usess->consumer);
 421
 422                 /* Destroy every UST application related to this session. */
 423                 ret = ust_app_destroy_trace_all(usess);
 424                 if (ret) {
 425                         ERR("Error in ust_app_destroy_trace_all");
 426                 }
 427
 428                 /* Clean up the rest. */
 429                 trace_ust_destroy_session(usess);
 430         }
 431
 432         /*
 433          * Must notify the kernel thread here to update it's poll set in order to
 434          * remove the channel(s)' fd just destroyed.
 435          */
 436         ret = notify_thread_pipe(kernel_poll_pipe[1]);
 437         if (ret < 0) {
 438                 PERROR("write kernel poll pipe");
 439         }
 440
 441         DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
 442         pthread_mutex_destroy(&session->lock);
 443
 444         consumer_output_put(session->consumer);
 445         snapshot_destroy(&session->snapshot);
 446
 447         ASSERT_LOCKED(ltt_session_list.lock);
 448         del_session_list(session);
 449         del_session_ht(session);
 450         pthread_cond_broadcast(&ltt_session_list.removal_cond);
 451         free(session);
 452 }
 453
 454 /*
 455  * Acquire a reference to a session.
 456  * This function may fail (return false); its return value must be checked.
 457  */
 458 bool session_get(struct ltt_session *session)
 459 {
 460         return urcu_ref_get_unless_zero(&session->ref);
 461 }
 462
 463 /*
 464  * Release a reference to a session.
 465  */
 466 void session_put(struct ltt_session *session)
 467 {
 468         /*
 469          * The session list lock must be held as any session_put()
 470          * may cause the removal of the session from the session_list.
 471          */
 472         ASSERT_LOCKED(ltt_session_list.lock);
 473         assert(session->ref.refcount);
 474         urcu_ref_put(&session->ref, session_release);
 475 }
 476
 477 /*
 478  * Destroy a session.
 479  *
 480  * This method does not immediately release/free the session as other
 481  * components may still hold a reference to the session. However,
 482  * the session should no longer be presented to the user.
 483  *
 484  * Releases the session list's reference to the session
 485  * and marks it as destroyed. Iterations on the session list should be
 486  * mindful of the "destroyed" flag.
 487  */
 488 void session_destroy(struct ltt_session *session)
 489 {
 490         assert(!session->destroyed);
 491         session->destroyed = true;
 492         session_put(session);
 493 }
 494
 495 /*
 496  * Return a ltt_session structure ptr that matches name. If no session found,
 497  * NULL is returned. This must be called with the session list lock held using
 498  * session_lock_list and session_unlock_list.
 499  * A reference to the session is implicitly acquired by this function.
 500  */
 501 struct ltt_session *session_find_by_name(const char *name)
 502 {
 503         struct ltt_session *iter;
 504
 505         assert(name);
 506         ASSERT_LOCKED(ltt_session_list.lock);
 507
 508         DBG2("Trying to find session by name %s", name);
 509
 510         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
 511                 if (!strncmp(iter->name, name, NAME_MAX) &&
 512                                 !iter->destroyed) {
 513                         goto found;
 514                 }
 515         }
 516
 517         return NULL;
 518 found:
 519         return session_get(iter) ? iter : NULL;
 520 }
 521
 522 /*
 523  * Return an ltt_session that matches the id. If no session is found,
 524  * NULL is returned. This must be called with rcu_read_lock and
 525  * session list lock held (to guarantee the lifetime of the session).
 526  */
 527 struct ltt_session *session_find_by_id(uint64_t id)
 528 {
 529         struct lttng_ht_node_u64 *node;
 530         struct lttng_ht_iter iter;
 531         struct ltt_session *ls;
 532
 533         ASSERT_LOCKED(ltt_session_list.lock);
 534
 535         if (!ltt_sessions_ht_by_id) {
 536                 goto end;
 537         }
 538
 539         lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
 540         node = lttng_ht_iter_get_node_u64(&iter);
 541         if (node == NULL) {
 542                 goto end;
 543         }
 544         ls = caa_container_of(node, struct ltt_session, node);
 545
 546         DBG3("Session %" PRIu64 " found by id.", id);
 547         return session_get(ls) ? ls : NULL;
 548
 549 end:
 550         DBG3("Session %" PRIu64 " NOT found by id", id);
 551         return NULL;
 552 }
 553
 554 /*
 555  * Create a brand new session and add it to the session list.
 556  */
 557 int session_create(char *name, uid_t uid, gid_t gid)
 558 {
 559         int ret;
 560         struct ltt_session *new_session;
 561
 562         /* Allocate session data structure */
 563         new_session = zmalloc(sizeof(struct ltt_session));
 564         if (new_session == NULL) {
 565                 PERROR("zmalloc");
 566                 ret = LTTNG_ERR_FATAL;
 567                 goto error_malloc;
 568         }
 569
 570         urcu_ref_init(&new_session->ref);
 571
 572         /* Define session name */
 573         if (name != NULL) {
 574                 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
 575                         ret = LTTNG_ERR_FATAL;
 576                         goto error_asprintf;
 577                 }
 578         } else {
 579                 ERR("No session name given");
 580                 ret = LTTNG_ERR_FATAL;
 581                 goto error;
 582         }
 583
 584         ret = validate_name(name);
 585         if (ret < 0) {
 586                 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
 587                 goto error;
 588         }
 589
 590         ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
 591         if (ret < 0) {
 592                 if (errno == ENAMETOOLONG) {
 593                         new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
 594                 } else {
 595                         ret = LTTNG_ERR_FATAL;
 596                         goto error;
 597                 }
 598         }
 599
 600         /* Init kernel session */
 601         new_session->kernel_session = NULL;
 602         new_session->ust_session = NULL;
 603
 604         /* Init lock */
 605         pthread_mutex_init(&new_session->lock, NULL);
 606
 607         new_session->uid = uid;
 608         new_session->gid = gid;
 609
 610         ret = snapshot_init(&new_session->snapshot);
 611         if (ret < 0) {
 612                 ret = LTTNG_ERR_NOMEM;
 613                 goto error;
 614         }
 615
 616         new_session->rotation_pending_local = false;
 617         new_session->rotation_pending_relay = false;
 618         new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
 619
 620         new_session->rotation_pending_check_timer_enabled = false;
 621         new_session->rotation_schedule_timer_enabled = false;
 622
 623         /* Add new session to the session list */
 624         session_lock_list();
 625         new_session->id = add_session_list(new_session);
 626         /*
 627          * Add the new session to the ltt_sessions_ht_by_id.
 628          * No ownership is taken by the hash table; it is merely
 629          * a wrapper around the session list used for faster access
 630          * by session id.
 631          */
 632         add_session_ht(new_session);
 633         session_unlock_list();
 634
 635         /*
 636          * Consumer is let to NULL since the create_session_uri command will set it
 637          * up and, if valid, assign it to the session.
 638          */
 639         DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
 640                         name, new_session->id, new_session->uid, new_session->gid);
 641
 642         return LTTNG_OK;
 643
 644 error:
 645 error_asprintf:
 646         free(new_session);
 647
 648 error_malloc:
 649         return ret;
 650 }
 651
 652 /*
 653  * Check if the UID or GID match the session. Root user has access to all
 654  * sessions.
 655  */
 656 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
 657 {
 658         assert(session);
 659
 660         if (uid != session->uid && gid != session->gid && uid != 0) {
 661                 return 0;
 662         } else {
 663                 return 1;
 664         }
 665 }
 666
 667 /*
 668  * Set a session's rotation state and reset all associated state.
 669  *
 670  * This function resets the rotation state (check timers, pending
 671  * flags, etc.) and sets the result of the last rotation. The result
 672  * can be queries by a liblttng-ctl client.
 673  *
 674  * Be careful of the result passed to this function. For instance,
 675  * on failure to launch a rotation, a client will expect the rotation
 676  * state to be set to "NO_ROTATION". If an error occured while the
 677  * rotation was "ONGOING", result should be set to "ERROR", which will
 678  * allow a client to report it.
 679  *
 680  * Must be called with the session and session_list locks held.
 681  */
 682 int session_reset_rotation_state(struct ltt_session *session,
 683                 enum lttng_rotation_state result)
 684 {
 685         int ret = 0;
 686
 687         ASSERT_LOCKED(ltt_session_list.lock);
 688         ASSERT_LOCKED(session->lock);
 689
 690         session->rotation_pending_local = false;
 691         session->rotation_pending_relay = false;
 692         session->rotated_after_last_stop = false;
 693         session->rotation_state = result;
 694         if (session->rotation_pending_check_timer_enabled) {
 695                 ret = timer_session_rotation_pending_check_stop(session);
 696         }
 697         return ret;
 698 }