01cdfdc00b670757e5fc46c842cdd5293aafc6b5
[lttng-tools.git] / 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
32 #include "session.h"
33 #include "utils.h"
34 #include "trace-ust.h"
35
36 /*
37 * NOTES:
38 *
39 * No ltt_session.lock is taken here because those data structure are widely
40 * spread across the lttng-tools code base so before caling functions below
41 * that can read/write a session, the caller MUST acquire the session lock
42 * using session_lock() and session_unlock().
43 */
44
45 /*
46 * Init tracing session list.
47 *
48 * Please see session.h for more explanation and correct usage of the list.
49 */
50 static struct ltt_session_list ltt_session_list = {
51 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
52 .lock = PTHREAD_MUTEX_INITIALIZER,
53 .next_uuid = 0,
54 };
55
56 /* These characters are forbidden in a session name. Used by validate_name. */
57 static const char *forbidden_name_chars = "/";
58
59 /* Global hash table to keep the sessions, indexed by id. */
60 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
61
62 /*
63 * Validate the session name for forbidden characters.
64 *
65 * Return 0 on success else -1 meaning a forbidden char. has been found.
66 */
67 static int validate_name(const char *name)
68 {
69 int ret;
70 char *tok, *tmp_name;
71
72 assert(name);
73
74 tmp_name = strdup(name);
75 if (!tmp_name) {
76 /* ENOMEM here. */
77 ret = -1;
78 goto error;
79 }
80
81 tok = strpbrk(tmp_name, forbidden_name_chars);
82 if (tok) {
83 DBG("Session name %s contains a forbidden character", name);
84 /* Forbidden character has been found. */
85 ret = -1;
86 goto error;
87 }
88 ret = 0;
89
90 error:
91 free(tmp_name);
92 return ret;
93 }
94
95 /*
96 * Add a ltt_session structure to the global list.
97 *
98 * The caller MUST acquire the session list lock before.
99 * Returns the unique identifier for the session.
100 */
101 static uint64_t add_session_list(struct ltt_session *ls)
102 {
103 assert(ls);
104
105 cds_list_add(&ls->list, &ltt_session_list.head);
106 return ltt_session_list.next_uuid++;
107 }
108
109 /*
110 * Delete a ltt_session structure to the global list.
111 *
112 * The caller MUST acquire the session list lock before.
113 */
114 static void del_session_list(struct ltt_session *ls)
115 {
116 assert(ls);
117
118 cds_list_del(&ls->list);
119 }
120
121 /*
122 * Return a pointer to the session list.
123 */
124 struct ltt_session_list *session_get_list(void)
125 {
126 return &ltt_session_list;
127 }
128
129 /*
130 * Acquire session list lock
131 */
132 void session_lock_list(void)
133 {
134 pthread_mutex_lock(&ltt_session_list.lock);
135 }
136
137 /*
138 * Release session list lock
139 */
140 void session_unlock_list(void)
141 {
142 pthread_mutex_unlock(&ltt_session_list.lock);
143 }
144
145 /*
146 * Get the session's consumer destination type.
147 *
148 * The caller must hold the session lock.
149 */
150 enum consumer_dst_type session_get_consumer_destination_type(
151 const struct ltt_session *session)
152 {
153 /*
154 * The output information is duplicated in both of those session types.
155 * Hence, it doesn't matter from which it is retrieved. However, it is
156 * possible for only one of them to be set.
157 */
158 return session->kernel_session ?
159 session->kernel_session->consumer->type :
160 session->ust_session->consumer->type;
161 }
162
163 /*
164 * Get the session's consumer network hostname.
165 * The caller must ensure that the destination is of type "net".
166 *
167 * The caller must hold the session lock.
168 */
169 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
170 {
171 const char *hostname = NULL;
172 const struct consumer_output *output;
173
174 output = session->kernel_session ?
175 session->kernel_session->consumer :
176 session->ust_session->consumer;
177
178 /*
179 * hostname is assumed to be the same for both control and data
180 * connections.
181 */
182 switch (output->dst.net.control.dtype) {
183 case LTTNG_DST_IPV4:
184 hostname = output->dst.net.control.dst.ipv4;
185 break;
186 case LTTNG_DST_IPV6:
187 hostname = output->dst.net.control.dst.ipv6;
188 break;
189 default:
190 abort();
191 }
192 return hostname;
193 }
194
195 /*
196 * Get the session's consumer network control and data ports.
197 * The caller must ensure that the destination is of type "net".
198 *
199 * The caller must hold the session lock.
200 */
201 void session_get_net_consumer_ports(const struct ltt_session *session,
202 uint16_t *control_port, uint16_t *data_port)
203 {
204 const struct consumer_output *output;
205
206 output = session->kernel_session ?
207 session->kernel_session->consumer :
208 session->ust_session->consumer;
209 *control_port = output->dst.net.control.port;
210 *data_port = output->dst.net.data.port;
211 }
212
213 /*
214 * Allocate the ltt_sessions_ht_by_id HT.
215 *
216 * The session list lock must be held.
217 */
218 int ltt_sessions_ht_alloc(void)
219 {
220 int ret = 0;
221
222 DBG("Allocating ltt_sessions_ht_by_id");
223 ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
224 if (!ltt_sessions_ht_by_id) {
225 ret = -1;
226 ERR("Failed to allocate ltt_sessions_ht_by_id");
227 goto end;
228 }
229 end:
230 return ret;
231 }
232
233 /*
234 * Destroy the ltt_sessions_ht_by_id HT.
235 *
236 * The session list lock must be held.
237 */
238 static void ltt_sessions_ht_destroy(void)
239 {
240 if (!ltt_sessions_ht_by_id) {
241 return;
242 }
243 ht_cleanup_push(ltt_sessions_ht_by_id);
244 ltt_sessions_ht_by_id = NULL;
245 }
246
247 /*
248 * Add a ltt_session to the ltt_sessions_ht_by_id.
249 * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
250 * The session list lock must be held.
251 */
252 static void add_session_ht(struct ltt_session *ls)
253 {
254 int ret;
255
256 assert(ls);
257
258 if (!ltt_sessions_ht_by_id) {
259 ret = ltt_sessions_ht_alloc();
260 if (ret) {
261 ERR("Error allocating the sessions HT");
262 goto end;
263 }
264 }
265 lttng_ht_node_init_u64(&ls->node, ls->id);
266 lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
267
268 end:
269 return;
270 }
271
272 /*
273 * Test if ltt_sessions_ht_by_id is empty.
274 * Return 1 if empty, 0 if not empty.
275 * The session list lock must be held.
276 */
277 static int ltt_sessions_ht_empty(void)
278 {
279 int ret;
280
281 if (!ltt_sessions_ht_by_id) {
282 ret = 1;
283 goto end;
284 }
285
286 ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
287 end:
288 return ret;
289 }
290
291 /*
292 * Remove a ltt_session from the ltt_sessions_ht_by_id.
293 * If empty, the ltt_sessions_ht_by_id HT is freed.
294 * The session list lock must be held.
295 */
296 static void del_session_ht(struct ltt_session *ls)
297 {
298 struct lttng_ht_iter iter;
299 int ret;
300
301 assert(ls);
302 assert(ltt_sessions_ht_by_id);
303
304 iter.iter.node = &ls->node.node;
305 ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
306 assert(!ret);
307
308 if (ltt_sessions_ht_empty()) {
309 DBG("Empty ltt_sessions_ht_by_id, destroying it");
310 ltt_sessions_ht_destroy();
311 }
312 }
313
314 /*
315 * Acquire session lock
316 */
317 void session_lock(struct ltt_session *session)
318 {
319 assert(session);
320
321 pthread_mutex_lock(&session->lock);
322 }
323
324 /*
325 * Release session lock
326 */
327 void session_unlock(struct ltt_session *session)
328 {
329 assert(session);
330
331 pthread_mutex_unlock(&session->lock);
332 }
333
334 /*
335 * Return a ltt_session structure ptr that matches name. If no session found,
336 * NULL is returned. This must be called with the session list lock held using
337 * session_lock_list and session_unlock_list.
338 */
339 struct ltt_session *session_find_by_name(const char *name)
340 {
341 struct ltt_session *iter;
342
343 assert(name);
344
345 DBG2("Trying to find session by name %s", name);
346
347 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
348 if (strncmp(iter->name, name, NAME_MAX) == 0) {
349 goto found;
350 }
351 }
352
353 iter = NULL;
354
355 found:
356 return iter;
357 }
358
359 /*
360 * Return an ltt_session that matches the id. If no session is found,
361 * NULL is returned. This must be called with rcu_read_lock and
362 * session list lock held (to guarantee the lifetime of the session).
363 */
364 struct ltt_session *session_find_by_id(uint64_t id)
365 {
366 struct lttng_ht_node_u64 *node;
367 struct lttng_ht_iter iter;
368 struct ltt_session *ls;
369
370 if (!ltt_sessions_ht_by_id) {
371 goto end;
372 }
373
374 lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
375 node = lttng_ht_iter_get_node_u64(&iter);
376 if (node == NULL) {
377 goto end;
378 }
379 ls = caa_container_of(node, struct ltt_session, node);
380
381 DBG3("Session %" PRIu64 " found by id.", id);
382 return ls;
383
384 end:
385 DBG3("Session %" PRIu64 " NOT found by id", id);
386 return NULL;
387 }
388
389 /*
390 * Delete session from the session list and free the memory.
391 *
392 * Return -1 if no session is found. On success, return 1;
393 * Should *NOT* be called with RCU read-side lock held.
394 */
395 int session_destroy(struct ltt_session *session)
396 {
397 /* Safety check */
398 assert(session);
399
400 DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
401 del_session_list(session);
402 pthread_mutex_destroy(&session->lock);
403 del_session_ht(session);
404
405 consumer_output_put(session->consumer);
406 snapshot_destroy(&session->snapshot);
407 free(session);
408
409 return LTTNG_OK;
410 }
411
412 /*
413 * Create a brand new session and add it to the session list.
414 */
415 int session_create(char *name, uid_t uid, gid_t gid)
416 {
417 int ret;
418 struct ltt_session *new_session;
419
420 /* Allocate session data structure */
421 new_session = zmalloc(sizeof(struct ltt_session));
422 if (new_session == NULL) {
423 PERROR("zmalloc");
424 ret = LTTNG_ERR_FATAL;
425 goto error_malloc;
426 }
427
428 /* Define session name */
429 if (name != NULL) {
430 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
431 ret = LTTNG_ERR_FATAL;
432 goto error_asprintf;
433 }
434 } else {
435 ERR("No session name given");
436 ret = LTTNG_ERR_FATAL;
437 goto error;
438 }
439
440 ret = validate_name(name);
441 if (ret < 0) {
442 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
443 goto error;
444 }
445
446 ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
447 if (ret < 0) {
448 if (errno == ENAMETOOLONG) {
449 new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
450 } else {
451 ret = LTTNG_ERR_FATAL;
452 goto error;
453 }
454 }
455
456 /* Init kernel session */
457 new_session->kernel_session = NULL;
458 new_session->ust_session = NULL;
459
460 /* Init lock */
461 pthread_mutex_init(&new_session->lock, NULL);
462
463 new_session->uid = uid;
464 new_session->gid = gid;
465
466 ret = snapshot_init(&new_session->snapshot);
467 if (ret < 0) {
468 ret = LTTNG_ERR_NOMEM;
469 goto error;
470 }
471
472 new_session->rotate_pending = false;
473 new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
474 new_session->rotate_pending_relay = false;
475 new_session->rotate_relay_pending_timer_enabled = false;
476 new_session->rotate_timer = false;
477
478 /* Add new session to the session list */
479 session_lock_list();
480 new_session->id = add_session_list(new_session);
481 /*
482 * Add the new session to the ltt_sessions_ht_by_id.
483 * No ownership is taken by the hash table; it is merely
484 * a wrapper around the session list used for faster access
485 * by session id.
486 */
487 add_session_ht(new_session);
488 session_unlock_list();
489
490 /*
491 * Consumer is let to NULL since the create_session_uri command will set it
492 * up and, if valid, assign it to the session.
493 */
494 DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
495 name, new_session->id, new_session->uid, new_session->gid);
496
497 return LTTNG_OK;
498
499 error:
500 error_asprintf:
501 free(new_session);
502
503 error_malloc:
504 return ret;
505 }
506
507 /*
508 * Check if the UID or GID match the session. Root user has access to all
509 * sessions.
510 */
511 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
512 {
513 assert(session);
514
515 if (uid != session->uid && gid != session->gid && uid != 0) {
516 return 0;
517 } else {
518 return 1;
519 }
520 }
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