Test fix: ignore stderr when generating random string
[lttng-tools.git] / src / bin / lttng-sessiond / session.c
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1/*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
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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.
91d76f53 7 *
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8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
d14d33bf 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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11 * GNU General Public License for more details.
12 *
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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.
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16 */
17
6c1c0768 18#define _LGPL_SOURCE
6c9cc2ab 19#include <limits.h>
d022620a 20#include <inttypes.h>
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21#include <stdio.h>
22#include <stdlib.h>
23#include <string.h>
a304c14c 24#include <sys/stat.h>
f6a9efaa 25#include <urcu.h>
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26#include <dirent.h>
27#include <sys/types.h>
5b74c7b1 28
990570ed 29#include <common/common.h>
db758600 30#include <common/sessiond-comm/sessiond-comm.h>
1e307fab 31
5b74c7b1 32#include "session.h"
23324029 33#include "utils.h"
5b74c7b1 34
8c0faa1d 35/*
b5541356 36 * NOTES:
8c0faa1d 37 *
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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
54d01ffb 41 * using session_lock() and session_unlock().
8c0faa1d 42 */
8c0faa1d 43
5b74c7b1 44/*
b5541356 45 * Init tracing session list.
5b74c7b1 46 *
b5541356 47 * Please see session.h for more explanation and correct usage of the list.
5b74c7b1 48 */
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49static struct ltt_session_list ltt_session_list = {
50 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
51 .lock = PTHREAD_MUTEX_INITIALIZER,
a24f7994 52 .next_uuid = 0,
b5541356 53};
5b74c7b1 54
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55/* These characters are forbidden in a session name. Used by validate_name. */
56static const char *forbidden_name_chars = "/";
57
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58/* Global hash table to keep the sessions, indexed by id. */
59static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
60
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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 */
66static 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
89error:
90 free(tmp_name);
91 return ret;
92}
93
5b74c7b1 94/*
050349bb 95 * Add a ltt_session structure to the global list.
5b74c7b1 96 *
050349bb 97 * The caller MUST acquire the session list lock before.
44e96653 98 * Returns the unique identifier for the session.
5b74c7b1 99 */
d022620a 100static uint64_t add_session_list(struct ltt_session *ls)
5b74c7b1 101{
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102 assert(ls);
103
5b74c7b1 104 cds_list_add(&ls->list, &ltt_session_list.head);
a24f7994 105 return ltt_session_list.next_uuid++;
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106}
107
108/*
050349bb 109 * Delete a ltt_session structure to the global list.
b5541356 110 *
050349bb 111 * The caller MUST acquire the session list lock before.
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112 */
113static void del_session_list(struct ltt_session *ls)
114{
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115 assert(ls);
116
5b74c7b1 117 cds_list_del(&ls->list);
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118}
119
b5541356 120/*
050349bb 121 * Return a pointer to the session list.
b5541356 122 */
54d01ffb 123struct ltt_session_list *session_get_list(void)
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124{
125 return &ltt_session_list;
126}
127
128/*
6c9cc2ab 129 * Acquire session list lock
b5541356 130 */
54d01ffb 131void session_lock_list(void)
b5541356 132{
6c9cc2ab 133 pthread_mutex_lock(&ltt_session_list.lock);
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134}
135
136/*
6c9cc2ab 137 * Release session list lock
b5541356 138 */
54d01ffb 139void session_unlock_list(void)
b5541356 140{
6c9cc2ab 141 pthread_mutex_unlock(&ltt_session_list.lock);
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142}
143
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144/*
145 * Allocate the ltt_sessions_ht_by_id HT.
146 */
147int ltt_sessions_ht_alloc(void)
148{
149 int ret = 0;
150
151 DBG("Allocating ltt_sessions_ht_by_id");
152 ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
153 if (!ltt_sessions_ht_by_id) {
154 ret = -1;
155 ERR("Failed to allocate ltt_sessions_ht_by_id");
156 goto end;
157 }
158end:
159 return ret;
160}
161
162/*
163 * Destroy the ltt_sessions_ht_by_id HT.
164 */
165void ltt_sessions_ht_destroy(void)
166{
167 if (!ltt_sessions_ht_by_id) {
168 return;
169 }
170 ht_cleanup_push(ltt_sessions_ht_by_id);
171 ltt_sessions_ht_by_id = NULL;
172}
173
174/*
175 * Add a ltt_session to the ltt_sessions_ht_by_id.
176 * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
177 * The session list lock must be held.
178 */
179static void add_session_ht(struct ltt_session *ls)
180{
181 int ret;
182
183 assert(ls);
184
185 if (!ltt_sessions_ht_by_id) {
186 ret = ltt_sessions_ht_alloc();
187 if (ret) {
188 ERR("Error allocating the sessions HT");
189 goto end;
190 }
191 }
192 lttng_ht_node_init_u64(&ls->node, ls->id);
193 lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
194
195end:
196 return;
197}
198
199/*
200 * Test if ltt_sessions_ht_by_id is empty.
201 * Return 1 if empty, 0 if not empty.
202 * The session list lock must be held.
203 */
def88971 204static int ltt_sessions_ht_empty(void)
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205{
206 int ret;
207
208 if (!ltt_sessions_ht_by_id) {
209 ret = 1;
210 goto end;
211 }
212
213 ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
214end:
215 return ret;
216}
217
218/*
219 * Remove a ltt_session from the ltt_sessions_ht_by_id.
220 * If empty, the ltt_sessions_ht_by_id HT is freed.
221 * The session list lock must be held.
222 */
223static void del_session_ht(struct ltt_session *ls)
224{
225 struct lttng_ht_iter iter;
226 int ret;
227
228 assert(ls);
229 assert(ltt_sessions_ht_by_id);
230
231 iter.iter.node = &ls->node.node;
232 ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
233 assert(!ret);
234
235 if (ltt_sessions_ht_empty()) {
236 DBG("Empty ltt_sessions_ht_by_id, destroying it");
237 ltt_sessions_ht_destroy();
238 }
239}
240
b5541356 241/*
6c9cc2ab 242 * Acquire session lock
b5541356 243 */
54d01ffb 244void session_lock(struct ltt_session *session)
b5541356 245{
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246 assert(session);
247
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248 pthread_mutex_lock(&session->lock);
249}
b5541356 250
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251/*
252 * Release session lock
253 */
54d01ffb 254void session_unlock(struct ltt_session *session)
6c9cc2ab 255{
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256 assert(session);
257
6c9cc2ab 258 pthread_mutex_unlock(&session->lock);
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259}
260
5b74c7b1 261/*
74babd95 262 * Return a ltt_session structure ptr that matches name. If no session found,
23324029 263 * NULL is returned. This must be called with the session list lock held using
74babd95 264 * session_lock_list and session_unlock_list.
5b74c7b1 265 */
58a1a227 266struct ltt_session *session_find_by_name(const char *name)
5b74c7b1 267{
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268 struct ltt_session *iter;
269
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270 assert(name);
271
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272 DBG2("Trying to find session by name %s", name);
273
5b74c7b1 274 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
1b110e1b 275 if (strncmp(iter->name, name, NAME_MAX) == 0) {
74babd95 276 goto found;
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277 }
278 }
279
74babd95 280 iter = NULL;
5b74c7b1 281
74babd95 282found:
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283 return iter;
284}
285
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286/*
287 * Return an ltt_session that matches the id. If no session is found,
288 * NULL is returned. This must be called with rcu_read_lock and
289 * session list lock held (to guarantee the lifetime of the session).
290 */
291struct ltt_session *session_find_by_id(uint64_t id)
292{
293 struct lttng_ht_node_u64 *node;
294 struct lttng_ht_iter iter;
295 struct ltt_session *ls;
296
297 lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
298 node = lttng_ht_iter_get_node_u64(&iter);
299 if (node == NULL) {
300 goto error;
301 }
302 ls = caa_container_of(node, struct ltt_session, node);
303
304 DBG3("Session %" PRIu64 " found by id.", id);
305 return ls;
306
307error:
308 DBG3("Session %" PRIu64 " NOT found by id", id);
309 return NULL;
310}
311
5b74c7b1 312/*
050349bb 313 * Delete session from the session list and free the memory.
5b74c7b1 314 *
050349bb 315 * Return -1 if no session is found. On success, return 1;
36b588ed 316 * Should *NOT* be called with RCU read-side lock held.
5b74c7b1 317 */
271933a4 318int session_destroy(struct ltt_session *session)
5b74c7b1 319{
271933a4 320 /* Safety check */
0525e9ae 321 assert(session);
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322
323 DBG("Destroying session %s", session->name);
324 del_session_list(session);
271933a4 325 pthread_mutex_destroy(&session->lock);
23324029 326 del_session_ht(session);
07424f16 327
6addfa37 328 consumer_output_put(session->consumer);
6dc3064a 329 snapshot_destroy(&session->snapshot);
271933a4 330 free(session);
5b74c7b1 331
f73fabfd 332 return LTTNG_OK;
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333}
334
335/*
050349bb 336 * Create a brand new session and add it to the session list.
5b74c7b1 337 */
dec56f6c 338int session_create(char *name, uid_t uid, gid_t gid)
5b74c7b1 339{
f3ed775e 340 int ret;
5b74c7b1 341 struct ltt_session *new_session;
e07ae692 342
5b74c7b1 343 /* Allocate session data structure */
ba7f0ae5 344 new_session = zmalloc(sizeof(struct ltt_session));
5b74c7b1 345 if (new_session == NULL) {
df0f840b 346 PERROR("zmalloc");
f73fabfd 347 ret = LTTNG_ERR_FATAL;
f3ed775e 348 goto error_malloc;
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349 }
350
f3ed775e 351 /* Define session name */
5b74c7b1 352 if (name != NULL) {
74babd95 353 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
f73fabfd 354 ret = LTTNG_ERR_FATAL;
f3ed775e 355 goto error_asprintf;
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356 }
357 } else {
f3ed775e 358 ERR("No session name given");
f73fabfd 359 ret = LTTNG_ERR_FATAL;
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360 goto error;
361 }
362
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363 ret = validate_name(name);
364 if (ret < 0) {
365 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
366 goto error;
367 }
368
d3e2ba59 369 ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
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370 if (ret < 0) {
371 if (errno == ENAMETOOLONG) {
372 new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
373 } else {
374 ret = LTTNG_ERR_FATAL;
375 goto error;
376 }
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377 }
378
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379 /* Init kernel session */
380 new_session->kernel_session = NULL;
f6a9efaa 381 new_session->ust_session = NULL;
1657e9bb 382
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383 /* Init lock */
384 pthread_mutex_init(&new_session->lock, NULL);
5b74c7b1 385
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386 new_session->uid = uid;
387 new_session->gid = gid;
388
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389 ret = snapshot_init(&new_session->snapshot);
390 if (ret < 0) {
391 ret = LTTNG_ERR_NOMEM;
392 goto error;
393 }
394
b5541356 395 /* Add new session to the session list */
54d01ffb 396 session_lock_list();
a991f516 397 new_session->id = add_session_list(new_session);
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398 /*
399 * Add the new session to the ltt_sessions_ht_by_id.
400 * No ownership is taken by the hash table; it is merely
401 * a wrapper around the session list used for faster access
402 * by session id.
403 */
404 add_session_ht(new_session);
54d01ffb 405 session_unlock_list();
b5541356 406
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407 /*
408 * Consumer is let to NULL since the create_session_uri command will set it
409 * up and, if valid, assign it to the session.
410 */
d022620a
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411 DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
412 name, new_session->id, new_session->uid, new_session->gid);
b082db07 413
f73fabfd 414 return LTTNG_OK;
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415
416error:
f3ed775e 417error_asprintf:
0e428499 418 free(new_session);
5b74c7b1 419
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420error_malloc:
421 return ret;
5b74c7b1 422}
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423
424/*
425 * Check if the UID or GID match the session. Root user has access to all
426 * sessions.
427 */
428int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
429{
430 assert(session);
431
432 if (uid != session->uid && gid != session->gid && uid != 0) {
433 return 0;
434 } else {
435 return 1;
436 }
437}
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