| 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 | |
| 32 | #include "session.h" |
| 33 | #include "utils.h" |
| 34 | |
| 35 | /* |
| 36 | * NOTES: |
| 37 | * |
| 38 | * No ltt_session.lock is taken here because those data structure are widely |
| 39 | * spread across the lttng-tools code base so before caling functions below |
| 40 | * that can read/write a session, the caller MUST acquire the session lock |
| 41 | * using session_lock() and session_unlock(). |
| 42 | */ |
| 43 | |
| 44 | /* |
| 45 | * Init tracing session list. |
| 46 | * |
| 47 | * Please see session.h for more explanation and correct usage of the list. |
| 48 | */ |
| 49 | static struct ltt_session_list ltt_session_list = { |
| 50 | .head = CDS_LIST_HEAD_INIT(ltt_session_list.head), |
| 51 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 52 | .next_uuid = 0, |
| 53 | }; |
| 54 | |
| 55 | /* These characters are forbidden in a session name. Used by validate_name. */ |
| 56 | static const char *forbidden_name_chars = "/"; |
| 57 | |
| 58 | /* Global hash table to keep the sessions, indexed by id. */ |
| 59 | static struct lttng_ht *ltt_sessions_ht_by_id = NULL; |
| 60 | |
| 61 | /* |
| 62 | * Validate the session name for forbidden characters. |
| 63 | * |
| 64 | * Return 0 on success else -1 meaning a forbidden char. has been found. |
| 65 | */ |
| 66 | static int validate_name(const char *name) |
| 67 | { |
| 68 | int ret; |
| 69 | char *tok, *tmp_name; |
| 70 | |
| 71 | assert(name); |
| 72 | |
| 73 | tmp_name = strdup(name); |
| 74 | if (!tmp_name) { |
| 75 | /* ENOMEM here. */ |
| 76 | ret = -1; |
| 77 | goto error; |
| 78 | } |
| 79 | |
| 80 | tok = strpbrk(tmp_name, forbidden_name_chars); |
| 81 | if (tok) { |
| 82 | DBG("Session name %s contains a forbidden character", name); |
| 83 | /* Forbidden character has been found. */ |
| 84 | ret = -1; |
| 85 | goto error; |
| 86 | } |
| 87 | ret = 0; |
| 88 | |
| 89 | error: |
| 90 | free(tmp_name); |
| 91 | return ret; |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * Add a ltt_session structure to the global list. |
| 96 | * |
| 97 | * The caller MUST acquire the session list lock before. |
| 98 | * Returns the unique identifier for the session. |
| 99 | */ |
| 100 | static uint64_t add_session_list(struct ltt_session *ls) |
| 101 | { |
| 102 | assert(ls); |
| 103 | |
| 104 | cds_list_add(&ls->list, <t_session_list.head); |
| 105 | return ltt_session_list.next_uuid++; |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * Delete a ltt_session structure to the global list. |
| 110 | * |
| 111 | * The caller MUST acquire the session list lock before. |
| 112 | */ |
| 113 | static void del_session_list(struct ltt_session *ls) |
| 114 | { |
| 115 | assert(ls); |
| 116 | |
| 117 | cds_list_del(&ls->list); |
| 118 | } |
| 119 | |
| 120 | /* |
| 121 | * Return a pointer to the session list. |
| 122 | */ |
| 123 | struct ltt_session_list *session_get_list(void) |
| 124 | { |
| 125 | return <t_session_list; |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * Acquire session list lock |
| 130 | */ |
| 131 | void session_lock_list(void) |
| 132 | { |
| 133 | pthread_mutex_lock(<t_session_list.lock); |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Release session list lock |
| 138 | */ |
| 139 | void session_unlock_list(void) |
| 140 | { |
| 141 | pthread_mutex_unlock(<t_session_list.lock); |
| 142 | } |
| 143 | |
| 144 | /* |
| 145 | * Allocate the ltt_sessions_ht_by_id HT. |
| 146 | * |
| 147 | * The session list lock must be held. |
| 148 | */ |
| 149 | int ltt_sessions_ht_alloc(void) |
| 150 | { |
| 151 | int ret = 0; |
| 152 | |
| 153 | DBG("Allocating ltt_sessions_ht_by_id"); |
| 154 | ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64); |
| 155 | if (!ltt_sessions_ht_by_id) { |
| 156 | ret = -1; |
| 157 | ERR("Failed to allocate ltt_sessions_ht_by_id"); |
| 158 | goto end; |
| 159 | } |
| 160 | end: |
| 161 | return ret; |
| 162 | } |
| 163 | |
| 164 | /* |
| 165 | * Destroy the ltt_sessions_ht_by_id HT. |
| 166 | * |
| 167 | * The session list lock must be held. |
| 168 | */ |
| 169 | static void ltt_sessions_ht_destroy(void) |
| 170 | { |
| 171 | if (!ltt_sessions_ht_by_id) { |
| 172 | return; |
| 173 | } |
| 174 | ht_cleanup_push(ltt_sessions_ht_by_id); |
| 175 | ltt_sessions_ht_by_id = NULL; |
| 176 | } |
| 177 | |
| 178 | /* |
| 179 | * Add a ltt_session to the ltt_sessions_ht_by_id. |
| 180 | * If unallocated, the ltt_sessions_ht_by_id HT is allocated. |
| 181 | * The session list lock must be held. |
| 182 | */ |
| 183 | static void add_session_ht(struct ltt_session *ls) |
| 184 | { |
| 185 | int ret; |
| 186 | |
| 187 | assert(ls); |
| 188 | |
| 189 | if (!ltt_sessions_ht_by_id) { |
| 190 | ret = ltt_sessions_ht_alloc(); |
| 191 | if (ret) { |
| 192 | ERR("Error allocating the sessions HT"); |
| 193 | goto end; |
| 194 | } |
| 195 | } |
| 196 | lttng_ht_node_init_u64(&ls->node, ls->id); |
| 197 | lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node); |
| 198 | |
| 199 | end: |
| 200 | return; |
| 201 | } |
| 202 | |
| 203 | /* |
| 204 | * Test if ltt_sessions_ht_by_id is empty. |
| 205 | * Return 1 if empty, 0 if not empty. |
| 206 | * The session list lock must be held. |
| 207 | */ |
| 208 | static int ltt_sessions_ht_empty(void) |
| 209 | { |
| 210 | int ret; |
| 211 | |
| 212 | if (!ltt_sessions_ht_by_id) { |
| 213 | ret = 1; |
| 214 | goto end; |
| 215 | } |
| 216 | |
| 217 | ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1; |
| 218 | end: |
| 219 | return ret; |
| 220 | } |
| 221 | |
| 222 | /* |
| 223 | * Remove a ltt_session from the ltt_sessions_ht_by_id. |
| 224 | * If empty, the ltt_sessions_ht_by_id HT is freed. |
| 225 | * The session list lock must be held. |
| 226 | */ |
| 227 | static void del_session_ht(struct ltt_session *ls) |
| 228 | { |
| 229 | struct lttng_ht_iter iter; |
| 230 | int ret; |
| 231 | |
| 232 | assert(ls); |
| 233 | assert(ltt_sessions_ht_by_id); |
| 234 | |
| 235 | iter.iter.node = &ls->node.node; |
| 236 | ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter); |
| 237 | assert(!ret); |
| 238 | |
| 239 | if (ltt_sessions_ht_empty()) { |
| 240 | DBG("Empty ltt_sessions_ht_by_id, destroying it"); |
| 241 | ltt_sessions_ht_destroy(); |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | /* |
| 246 | * Acquire session lock |
| 247 | */ |
| 248 | void session_lock(struct ltt_session *session) |
| 249 | { |
| 250 | assert(session); |
| 251 | |
| 252 | pthread_mutex_lock(&session->lock); |
| 253 | } |
| 254 | |
| 255 | /* |
| 256 | * Release session lock |
| 257 | */ |
| 258 | void session_unlock(struct ltt_session *session) |
| 259 | { |
| 260 | assert(session); |
| 261 | |
| 262 | pthread_mutex_unlock(&session->lock); |
| 263 | } |
| 264 | |
| 265 | /* |
| 266 | * Return a ltt_session structure ptr that matches name. If no session found, |
| 267 | * NULL is returned. This must be called with the session list lock held using |
| 268 | * session_lock_list and session_unlock_list. |
| 269 | */ |
| 270 | struct ltt_session *session_find_by_name(const char *name) |
| 271 | { |
| 272 | struct ltt_session *iter; |
| 273 | |
| 274 | assert(name); |
| 275 | |
| 276 | DBG2("Trying to find session by name %s", name); |
| 277 | |
| 278 | cds_list_for_each_entry(iter, <t_session_list.head, list) { |
| 279 | if (strncmp(iter->name, name, NAME_MAX) == 0) { |
| 280 | goto found; |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | iter = NULL; |
| 285 | |
| 286 | found: |
| 287 | return iter; |
| 288 | } |
| 289 | |
| 290 | /* |
| 291 | * Return an ltt_session that matches the id. If no session is found, |
| 292 | * NULL is returned. This must be called with rcu_read_lock and |
| 293 | * session list lock held (to guarantee the lifetime of the session). |
| 294 | */ |
| 295 | struct ltt_session *session_find_by_id(uint64_t id) |
| 296 | { |
| 297 | struct lttng_ht_node_u64 *node; |
| 298 | struct lttng_ht_iter iter; |
| 299 | struct ltt_session *ls; |
| 300 | |
| 301 | if (!ltt_sessions_ht_by_id) { |
| 302 | goto end; |
| 303 | } |
| 304 | |
| 305 | lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter); |
| 306 | node = lttng_ht_iter_get_node_u64(&iter); |
| 307 | if (node == NULL) { |
| 308 | goto end; |
| 309 | } |
| 310 | ls = caa_container_of(node, struct ltt_session, node); |
| 311 | |
| 312 | DBG3("Session %" PRIu64 " found by id.", id); |
| 313 | return ls; |
| 314 | |
| 315 | end: |
| 316 | DBG3("Session %" PRIu64 " NOT found by id", id); |
| 317 | return NULL; |
| 318 | } |
| 319 | |
| 320 | /* |
| 321 | * Delete session from the session list and free the memory. |
| 322 | * |
| 323 | * Return -1 if no session is found. On success, return 1; |
| 324 | * Should *NOT* be called with RCU read-side lock held. |
| 325 | */ |
| 326 | int session_destroy(struct ltt_session *session) |
| 327 | { |
| 328 | /* Safety check */ |
| 329 | assert(session); |
| 330 | |
| 331 | DBG("Destroying session %s", session->name); |
| 332 | del_session_list(session); |
| 333 | pthread_mutex_destroy(&session->lock); |
| 334 | del_session_ht(session); |
| 335 | |
| 336 | consumer_output_put(session->consumer); |
| 337 | snapshot_destroy(&session->snapshot); |
| 338 | free(session); |
| 339 | |
| 340 | return LTTNG_OK; |
| 341 | } |
| 342 | |
| 343 | /* |
| 344 | * Create a brand new session and add it to the session list. |
| 345 | */ |
| 346 | int session_create(char *name, uid_t uid, gid_t gid) |
| 347 | { |
| 348 | int ret; |
| 349 | struct ltt_session *new_session; |
| 350 | |
| 351 | /* Allocate session data structure */ |
| 352 | new_session = zmalloc(sizeof(struct ltt_session)); |
| 353 | if (new_session == NULL) { |
| 354 | PERROR("zmalloc"); |
| 355 | ret = LTTNG_ERR_FATAL; |
| 356 | goto error_malloc; |
| 357 | } |
| 358 | |
| 359 | /* Define session name */ |
| 360 | if (name != NULL) { |
| 361 | if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) { |
| 362 | ret = LTTNG_ERR_FATAL; |
| 363 | goto error_asprintf; |
| 364 | } |
| 365 | } else { |
| 366 | ERR("No session name given"); |
| 367 | ret = LTTNG_ERR_FATAL; |
| 368 | goto error; |
| 369 | } |
| 370 | |
| 371 | ret = validate_name(name); |
| 372 | if (ret < 0) { |
| 373 | ret = LTTNG_ERR_SESSION_INVALID_CHAR; |
| 374 | goto error; |
| 375 | } |
| 376 | |
| 377 | ret = gethostname(new_session->hostname, sizeof(new_session->hostname)); |
| 378 | if (ret < 0) { |
| 379 | if (errno == ENAMETOOLONG) { |
| 380 | new_session->hostname[sizeof(new_session->hostname) - 1] = '\0'; |
| 381 | } else { |
| 382 | ret = LTTNG_ERR_FATAL; |
| 383 | goto error; |
| 384 | } |
| 385 | } |
| 386 | |
| 387 | /* Init kernel session */ |
| 388 | new_session->kernel_session = NULL; |
| 389 | new_session->ust_session = NULL; |
| 390 | |
| 391 | /* Init lock */ |
| 392 | pthread_mutex_init(&new_session->lock, NULL); |
| 393 | |
| 394 | new_session->uid = uid; |
| 395 | new_session->gid = gid; |
| 396 | |
| 397 | ret = snapshot_init(&new_session->snapshot); |
| 398 | if (ret < 0) { |
| 399 | ret = LTTNG_ERR_NOMEM; |
| 400 | goto error; |
| 401 | } |
| 402 | |
| 403 | /* Add new session to the session list */ |
| 404 | session_lock_list(); |
| 405 | new_session->id = add_session_list(new_session); |
| 406 | /* |
| 407 | * Add the new session to the ltt_sessions_ht_by_id. |
| 408 | * No ownership is taken by the hash table; it is merely |
| 409 | * a wrapper around the session list used for faster access |
| 410 | * by session id. |
| 411 | */ |
| 412 | add_session_ht(new_session); |
| 413 | session_unlock_list(); |
| 414 | |
| 415 | /* |
| 416 | * Consumer is let to NULL since the create_session_uri command will set it |
| 417 | * up and, if valid, assign it to the session. |
| 418 | */ |
| 419 | DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d", |
| 420 | name, new_session->id, new_session->uid, new_session->gid); |
| 421 | |
| 422 | return LTTNG_OK; |
| 423 | |
| 424 | error: |
| 425 | error_asprintf: |
| 426 | free(new_session); |
| 427 | |
| 428 | error_malloc: |
| 429 | return ret; |
| 430 | } |
| 431 | |
| 432 | /* |
| 433 | * Check if the UID or GID match the session. Root user has access to all |
| 434 | * sessions. |
| 435 | */ |
| 436 | int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid) |
| 437 | { |
| 438 | assert(session); |
| 439 | |
| 440 | if (uid != session->uid && gid != session->gid && uid != 0) { |
| 441 | return 0; |
| 442 | } else { |
| 443 | return 1; |
| 444 | } |
| 445 | } |