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
  33 #include "session.h"
  34 #include "utils.h"
  35 #include "trace-ust.h"
  36 #include "timer.h"
  37
  38 /*
  39  * NOTES:
  40  *
  41  * No ltt_session.lock is taken here because those data structure are widely
  42  * spread across the lttng-tools code base so before caling functions below
  43  * that can read/write a session, the caller MUST acquire the session lock
  44  * using session_lock() and session_unlock().
  45  */
  46
  47 /*
  48  * Init tracing session list.
  49  *
  50  * Please see session.h for more explanation and correct usage of the list.
  51  */
  52 static struct ltt_session_list ltt_session_list = {
  53         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  54         .lock = PTHREAD_MUTEX_INITIALIZER,
  55         .next_uuid = 0,
  56 };
  57
  58 /* These characters are forbidden in a session name. Used by validate_name. */
  59 static const char *forbidden_name_chars = "/";
  60
  61 /* Global hash table to keep the sessions, indexed by id. */
  62 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
  63
  64 /*
  65  * Validate the session name for forbidden characters.
  66  *
  67  * Return 0 on success else -1 meaning a forbidden char. has been found.
  68  */
  69 static int validate_name(const char *name)
  70 {
  71         int ret;
  72         char *tok, *tmp_name;
  73
  74         assert(name);
  75
  76         tmp_name = strdup(name);
  77         if (!tmp_name) {
  78                 /* ENOMEM here. */
  79                 ret = -1;
  80                 goto error;
  81         }
  82
  83         tok = strpbrk(tmp_name, forbidden_name_chars);
  84         if (tok) {
  85                 DBG("Session name %s contains a forbidden character", name);
  86                 /* Forbidden character has been found. */
  87                 ret = -1;
  88                 goto error;
  89         }
  90         ret = 0;
  91
  92 error:
  93         free(tmp_name);
  94         return ret;
  95 }
  96
  97 /*
  98  * Add a ltt_session structure to the global list.
  99  *
 100  * The caller MUST acquire the session list lock before.
 101  * Returns the unique identifier for the session.
 102  */
 103 static uint64_t add_session_list(struct ltt_session *ls)
 104 {
 105         assert(ls);
 106
 107         cds_list_add(&ls->list, &ltt_session_list.head);
 108         return ltt_session_list.next_uuid++;
 109 }
 110
 111 /*
 112  * Delete a ltt_session structure to the global list.
 113  *
 114  * The caller MUST acquire the session list lock before.
 115  */
 116 static void del_session_list(struct ltt_session *ls)
 117 {
 118         assert(ls);
 119
 120         cds_list_del(&ls->list);
 121 }
 122
 123 /*
 124  * Return a pointer to the session list.
 125  */
 126 struct ltt_session_list *session_get_list(void)
 127 {
 128         return &ltt_session_list;
 129 }
 130
 131 /*
 132  * Acquire session list lock
 133  */
 134 void session_lock_list(void)
 135 {
 136         pthread_mutex_lock(&ltt_session_list.lock);
 137 }
 138
 139 /*
 140  * Try to acquire session list lock
 141  */
 142 int session_trylock_list(void)
 143 {
 144         return pthread_mutex_trylock(&ltt_session_list.lock);
 145 }
 146
 147 /*
 148  * Release session list lock
 149  */
 150 void session_unlock_list(void)
 151 {
 152         pthread_mutex_unlock(&ltt_session_list.lock);
 153 }
 154
 155 /*
 156  * Get the session's consumer destination type.
 157  *
 158  * The caller must hold the session lock.
 159  */
 160 enum consumer_dst_type session_get_consumer_destination_type(
 161                 const struct ltt_session *session)
 162 {
 163         /*
 164          * The output information is duplicated in both of those session types.
 165          * Hence, it doesn't matter from which it is retrieved. However, it is
 166          * possible for only one of them to be set.
 167          */
 168         return session->kernel_session ?
 169                         session->kernel_session->consumer->type :
 170                         session->ust_session->consumer->type;
 171 }
 172
 173 /*
 174  * Get the session's consumer network hostname.
 175  * The caller must ensure that the destination is of type "net".
 176  *
 177  * The caller must hold the session lock.
 178  */
 179 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
 180 {
 181         const char *hostname = NULL;
 182         const struct consumer_output *output;
 183
 184         output = session->kernel_session ?
 185                         session->kernel_session->consumer :
 186                         session->ust_session->consumer;
 187
 188         /*
 189          * hostname is assumed to be the same for both control and data
 190          * connections.
 191          */
 192         switch (output->dst.net.control.dtype) {
 193         case LTTNG_DST_IPV4:
 194                 hostname = output->dst.net.control.dst.ipv4;
 195                 break;
 196         case LTTNG_DST_IPV6:
 197                 hostname = output->dst.net.control.dst.ipv6;
 198                 break;
 199         default:
 200                 abort();
 201         }
 202         return hostname;
 203 }
 204
 205 /*
 206  * Get the session's consumer network control and data ports.
 207  * The caller must ensure that the destination is of type "net".
 208  *
 209  * The caller must hold the session lock.
 210  */
 211 void session_get_net_consumer_ports(const struct ltt_session *session,
 212                 uint16_t *control_port, uint16_t *data_port)
 213 {
 214         const struct consumer_output *output;
 215
 216         output = session->kernel_session ?
 217                         session->kernel_session->consumer :
 218                         session->ust_session->consumer;
 219         *control_port = output->dst.net.control.port;
 220         *data_port = output->dst.net.data.port;
 221 }
 222
 223 /*
 224  * Get the location of the latest trace archive produced by a rotation.
 225  *
 226  * The caller must hold the session lock.
 227  */
 228 struct lttng_trace_archive_location *session_get_trace_archive_location(
 229                 struct ltt_session *session)
 230 {
 231         struct lttng_trace_archive_location *location = NULL;
 232
 233         if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED) {
 234                 goto end;
 235         }
 236
 237         switch (session_get_consumer_destination_type(session)) {
 238         case CONSUMER_DST_LOCAL:
 239                 location = lttng_trace_archive_location_local_create(
 240                                 session->rotation_chunk.current_rotate_path);
 241                 break;
 242         case CONSUMER_DST_NET:
 243         {
 244                 const char *hostname;
 245                 uint16_t control_port, data_port;
 246
 247                 hostname = session_get_net_consumer_hostname(session);
 248                 session_get_net_consumer_ports(session,
 249                                 &control_port,
 250                                 &data_port);
 251                 location = lttng_trace_archive_location_relay_create(
 252                                 hostname,
 253                                 LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP,
 254                                 control_port, data_port,
 255                                 session->rotation_chunk.current_rotate_path);
 256                 break;
 257         }
 258         default:
 259                 abort();
 260         }
 261 end:
 262         return location;
 263 }
 264
 265 /*
 266  * Allocate the ltt_sessions_ht_by_id HT.
 267  *
 268  * The session list lock must be held.
 269  */
 270 int ltt_sessions_ht_alloc(void)
 271 {
 272         int ret = 0;
 273
 274         DBG("Allocating ltt_sessions_ht_by_id");
 275         ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 276         if (!ltt_sessions_ht_by_id) {
 277                 ret = -1;
 278                 ERR("Failed to allocate ltt_sessions_ht_by_id");
 279                 goto end;
 280         }
 281 end:
 282         return ret;
 283 }
 284
 285 /*
 286  * Destroy the ltt_sessions_ht_by_id HT.
 287  *
 288  * The session list lock must be held.
 289  */
 290 static void ltt_sessions_ht_destroy(void)
 291 {
 292         if (!ltt_sessions_ht_by_id) {
 293                 return;
 294         }
 295         ht_cleanup_push(ltt_sessions_ht_by_id);
 296         ltt_sessions_ht_by_id = NULL;
 297 }
 298
 299 /*
 300  * Add a ltt_session to the ltt_sessions_ht_by_id.
 301  * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
 302  * The session list lock must be held.
 303  */
 304 static void add_session_ht(struct ltt_session *ls)
 305 {
 306         int ret;
 307
 308         assert(ls);
 309
 310         if (!ltt_sessions_ht_by_id) {
 311                 ret = ltt_sessions_ht_alloc();
 312                 if (ret) {
 313                         ERR("Error allocating the sessions HT");
 314                         goto end;
 315                 }
 316         }
 317         lttng_ht_node_init_u64(&ls->node, ls->id);
 318         lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
 319
 320 end:
 321         return;
 322 }
 323
 324 /*
 325  * Test if ltt_sessions_ht_by_id is empty.
 326  * Return 1 if empty, 0 if not empty.
 327  * The session list lock must be held.
 328  */
 329 static int ltt_sessions_ht_empty(void)
 330 {
 331         int ret;
 332
 333         if (!ltt_sessions_ht_by_id) {
 334                 ret = 1;
 335                 goto end;
 336         }
 337
 338         ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
 339 end:
 340         return ret;
 341 }
 342
 343 /*
 344  * Remove a ltt_session from the ltt_sessions_ht_by_id.
 345  * If empty, the ltt_sessions_ht_by_id HT is freed.
 346  * The session list lock must be held.
 347  */
 348 static void del_session_ht(struct ltt_session *ls)
 349 {
 350         struct lttng_ht_iter iter;
 351         int ret;
 352
 353         assert(ls);
 354         assert(ltt_sessions_ht_by_id);
 355
 356         iter.iter.node = &ls->node.node;
 357         ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
 358         assert(!ret);
 359
 360         if (ltt_sessions_ht_empty()) {
 361                 DBG("Empty ltt_sessions_ht_by_id, destroying it");
 362                 ltt_sessions_ht_destroy();
 363         }
 364 }
 365
 366 /*
 367  * Acquire session lock
 368  */
 369 void session_lock(struct ltt_session *session)
 370 {
 371         assert(session);
 372
 373         pthread_mutex_lock(&session->lock);
 374 }
 375
 376 /*
 377  * Release session lock
 378  */
 379 void session_unlock(struct ltt_session *session)
 380 {
 381         assert(session);
 382
 383         pthread_mutex_unlock(&session->lock);
 384 }
 385
 386 /*
 387  * Return a ltt_session structure ptr that matches name. If no session found,
 388  * NULL is returned. This must be called with the session list lock held using
 389  * session_lock_list and session_unlock_list.
 390  */
 391 struct ltt_session *session_find_by_name(const char *name)
 392 {
 393         struct ltt_session *iter;
 394
 395         assert(name);
 396
 397         DBG2("Trying to find session by name %s", name);
 398
 399         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
 400                 if (strncmp(iter->name, name, NAME_MAX) == 0) {
 401                         goto found;
 402                 }
 403         }
 404
 405         iter = NULL;
 406
 407 found:
 408         return iter;
 409 }
 410
 411 /*
 412  * Return an ltt_session that matches the id. If no session is found,
 413  * NULL is returned. This must be called with rcu_read_lock and
 414  * session list lock held (to guarantee the lifetime of the session).
 415  */
 416 struct ltt_session *session_find_by_id(uint64_t id)
 417 {
 418         struct lttng_ht_node_u64 *node;
 419         struct lttng_ht_iter iter;
 420         struct ltt_session *ls;
 421
 422         if (!ltt_sessions_ht_by_id) {
 423                 goto end;
 424         }
 425
 426         lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
 427         node = lttng_ht_iter_get_node_u64(&iter);
 428         if (node == NULL) {
 429                 goto end;
 430         }
 431         ls = caa_container_of(node, struct ltt_session, node);
 432
 433         DBG3("Session %" PRIu64 " found by id.", id);
 434         return ls;
 435
 436 end:
 437         DBG3("Session %" PRIu64 " NOT found by id", id);
 438         return NULL;
 439 }
 440
 441 /*
 442  * Delete session from the session list and free the memory.
 443  *
 444  * Return -1 if no session is found.  On success, return 1;
 445  * Should *NOT* be called with RCU read-side lock held.
 446  */
 447 int session_destroy(struct ltt_session *session)
 448 {
 449         /* Safety check */
 450         assert(session);
 451
 452         DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
 453         del_session_list(session);
 454         pthread_mutex_destroy(&session->lock);
 455         del_session_ht(session);
 456
 457         consumer_output_put(session->consumer);
 458         snapshot_destroy(&session->snapshot);
 459         free(session);
 460
 461         return LTTNG_OK;
 462 }
 463
 464 /*
 465  * Create a brand new session and add it to the session list.
 466  */
 467 int session_create(char *name, uid_t uid, gid_t gid)
 468 {
 469         int ret;
 470         struct ltt_session *new_session;
 471
 472         /* Allocate session data structure */
 473         new_session = zmalloc(sizeof(struct ltt_session));
 474         if (new_session == NULL) {
 475                 PERROR("zmalloc");
 476                 ret = LTTNG_ERR_FATAL;
 477                 goto error_malloc;
 478         }
 479
 480         /* Define session name */
 481         if (name != NULL) {
 482                 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
 483                         ret = LTTNG_ERR_FATAL;
 484                         goto error_asprintf;
 485                 }
 486         } else {
 487                 ERR("No session name given");
 488                 ret = LTTNG_ERR_FATAL;
 489                 goto error;
 490         }
 491
 492         ret = validate_name(name);
 493         if (ret < 0) {
 494                 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
 495                 goto error;
 496         }
 497
 498         ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
 499         if (ret < 0) {
 500                 if (errno == ENAMETOOLONG) {
 501                         new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
 502                 } else {
 503                         ret = LTTNG_ERR_FATAL;
 504                         goto error;
 505                 }
 506         }
 507
 508         /* Init kernel session */
 509         new_session->kernel_session = NULL;
 510         new_session->ust_session = NULL;
 511
 512         /* Init lock */
 513         pthread_mutex_init(&new_session->lock, NULL);
 514
 515         new_session->uid = uid;
 516         new_session->gid = gid;
 517
 518         ret = snapshot_init(&new_session->snapshot);
 519         if (ret < 0) {
 520                 ret = LTTNG_ERR_NOMEM;
 521                 goto error;
 522         }
 523
 524         new_session->rotation_pending_local = false;
 525         new_session->rotation_pending_relay = false;
 526         new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
 527
 528         new_session->rotation_pending_check_timer_enabled = false;
 529         new_session->rotation_schedule_timer_enabled = false;
 530
 531         /* Add new session to the session list */
 532         session_lock_list();
 533         new_session->id = add_session_list(new_session);
 534         /*
 535          * Add the new session to the ltt_sessions_ht_by_id.
 536          * No ownership is taken by the hash table; it is merely
 537          * a wrapper around the session list used for faster access
 538          * by session id.
 539          */
 540         add_session_ht(new_session);
 541         session_unlock_list();
 542
 543         /*
 544          * Consumer is let to NULL since the create_session_uri command will set it
 545          * up and, if valid, assign it to the session.
 546          */
 547         DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
 548                         name, new_session->id, new_session->uid, new_session->gid);
 549
 550         return LTTNG_OK;
 551
 552 error:
 553 error_asprintf:
 554         free(new_session);
 555
 556 error_malloc:
 557         return ret;
 558 }
 559
 560 /*
 561  * Check if the UID or GID match the session. Root user has access to all
 562  * sessions.
 563  */
 564 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
 565 {
 566         assert(session);
 567
 568         if (uid != session->uid && gid != session->gid && uid != 0) {
 569                 return 0;
 570         } else {
 571                 return 1;
 572         }
 573 }