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