Fix: HT must not be destroyed with a rcu_read_lock held
[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
18#define _GNU_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>
5b74c7b1 26
990570ed 27#include <common/common.h>
db758600 28#include <common/sessiond-comm/sessiond-comm.h>
1e307fab 29
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30#include "session.h"
31
8c0faa1d 32/*
b5541356 33 * NOTES:
8c0faa1d 34 *
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35 * No ltt_session.lock is taken here because those data structure are widely
36 * spread across the lttng-tools code base so before caling functions below
37 * that can read/write a session, the caller MUST acquire the session lock
54d01ffb 38 * using session_lock() and session_unlock().
8c0faa1d 39 */
8c0faa1d 40
5b74c7b1 41/*
b5541356 42 * Init tracing session list.
5b74c7b1 43 *
b5541356 44 * Please see session.h for more explanation and correct usage of the list.
5b74c7b1 45 */
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46static struct ltt_session_list ltt_session_list = {
47 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
48 .lock = PTHREAD_MUTEX_INITIALIZER,
a24f7994 49 .next_uuid = 0,
b5541356 50};
5b74c7b1 51
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52/* These characters are forbidden in a session name. Used by validate_name. */
53static const char *forbidden_name_chars = "/";
54
55/*
56 * Validate the session name for forbidden characters.
57 *
58 * Return 0 on success else -1 meaning a forbidden char. has been found.
59 */
60static int validate_name(const char *name)
61{
62 int ret;
63 char *tok, *tmp_name;
64
65 assert(name);
66
67 tmp_name = strdup(name);
68 if (!tmp_name) {
69 /* ENOMEM here. */
70 ret = -1;
71 goto error;
72 }
73
74 tok = strpbrk(tmp_name, forbidden_name_chars);
75 if (tok) {
76 DBG("Session name %s contains a forbidden character", name);
77 /* Forbidden character has been found. */
78 ret = -1;
79 goto error;
80 }
81 ret = 0;
82
83error:
84 free(tmp_name);
85 return ret;
86}
87
5b74c7b1 88/*
050349bb 89 * Add a ltt_session structure to the global list.
5b74c7b1 90 *
050349bb 91 * The caller MUST acquire the session list lock before.
44e96653 92 * Returns the unique identifier for the session.
5b74c7b1 93 */
d022620a 94static uint64_t add_session_list(struct ltt_session *ls)
5b74c7b1 95{
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96 assert(ls);
97
5b74c7b1 98 cds_list_add(&ls->list, &ltt_session_list.head);
a24f7994 99 return ltt_session_list.next_uuid++;
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100}
101
102/*
050349bb 103 * Delete a ltt_session structure to the global list.
b5541356 104 *
050349bb 105 * The caller MUST acquire the session list lock before.
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106 */
107static void del_session_list(struct ltt_session *ls)
108{
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109 assert(ls);
110
5b74c7b1 111 cds_list_del(&ls->list);
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112}
113
b5541356 114/*
050349bb 115 * Return a pointer to the session list.
b5541356 116 */
54d01ffb 117struct ltt_session_list *session_get_list(void)
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118{
119 return &ltt_session_list;
120}
121
122/*
6c9cc2ab 123 * Acquire session list lock
b5541356 124 */
54d01ffb 125void session_lock_list(void)
b5541356 126{
6c9cc2ab 127 pthread_mutex_lock(&ltt_session_list.lock);
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128}
129
130/*
6c9cc2ab 131 * Release session list lock
b5541356 132 */
54d01ffb 133void session_unlock_list(void)
b5541356 134{
6c9cc2ab 135 pthread_mutex_unlock(&ltt_session_list.lock);
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136}
137
138/*
6c9cc2ab 139 * Acquire session lock
b5541356 140 */
54d01ffb 141void session_lock(struct ltt_session *session)
b5541356 142{
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143 assert(session);
144
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145 pthread_mutex_lock(&session->lock);
146}
b5541356 147
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148/*
149 * Release session lock
150 */
54d01ffb 151void session_unlock(struct ltt_session *session)
6c9cc2ab 152{
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153 assert(session);
154
6c9cc2ab 155 pthread_mutex_unlock(&session->lock);
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156}
157
5b74c7b1 158/*
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159 * Return a ltt_session structure ptr that matches name. If no session found,
160 * NULL is returned. This must be called with the session lock held using
161 * session_lock_list and session_unlock_list.
5b74c7b1 162 */
58a1a227 163struct ltt_session *session_find_by_name(const char *name)
5b74c7b1 164{
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165 struct ltt_session *iter;
166
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167 assert(name);
168
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169 DBG2("Trying to find session by name %s", name);
170
5b74c7b1 171 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
1b110e1b 172 if (strncmp(iter->name, name, NAME_MAX) == 0) {
74babd95 173 goto found;
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174 }
175 }
176
74babd95 177 iter = NULL;
5b74c7b1 178
74babd95 179found:
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180 return iter;
181}
182
183/*
050349bb 184 * Delete session from the session list and free the memory.
5b74c7b1 185 *
050349bb 186 * Return -1 if no session is found. On success, return 1;
36b588ed 187 * Should *NOT* be called with RCU read-side lock held.
5b74c7b1 188 */
271933a4 189int session_destroy(struct ltt_session *session)
5b74c7b1 190{
271933a4 191 /* Safety check */
0525e9ae 192 assert(session);
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193
194 DBG("Destroying session %s", session->name);
195 del_session_list(session);
271933a4 196 pthread_mutex_destroy(&session->lock);
07424f16 197
07424f16 198 consumer_destroy_output(session->consumer);
6dc3064a 199 snapshot_destroy(&session->snapshot);
271933a4 200 free(session);
5b74c7b1 201
f73fabfd 202 return LTTNG_OK;
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203}
204
205/*
050349bb 206 * Create a brand new session and add it to the session list.
5b74c7b1 207 */
dec56f6c 208int session_create(char *name, uid_t uid, gid_t gid)
5b74c7b1 209{
f3ed775e 210 int ret;
5b74c7b1 211 struct ltt_session *new_session;
e07ae692 212
5b74c7b1 213 /* Allocate session data structure */
ba7f0ae5 214 new_session = zmalloc(sizeof(struct ltt_session));
5b74c7b1 215 if (new_session == NULL) {
df0f840b 216 PERROR("zmalloc");
f73fabfd 217 ret = LTTNG_ERR_FATAL;
f3ed775e 218 goto error_malloc;
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219 }
220
f3ed775e 221 /* Define session name */
5b74c7b1 222 if (name != NULL) {
74babd95 223 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
f73fabfd 224 ret = LTTNG_ERR_FATAL;
f3ed775e 225 goto error_asprintf;
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226 }
227 } else {
f3ed775e 228 ERR("No session name given");
f73fabfd 229 ret = LTTNG_ERR_FATAL;
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230 goto error;
231 }
232
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233 ret = validate_name(name);
234 if (ret < 0) {
235 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
236 goto error;
237 }
238
d3e2ba59 239 ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
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240 if (ret < 0) {
241 if (errno == ENAMETOOLONG) {
242 new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
243 } else {
244 ret = LTTNG_ERR_FATAL;
245 goto error;
246 }
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247 }
248
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249 /* Init kernel session */
250 new_session->kernel_session = NULL;
f6a9efaa 251 new_session->ust_session = NULL;
1657e9bb 252
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253 /* Init lock */
254 pthread_mutex_init(&new_session->lock, NULL);
5b74c7b1 255
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256 new_session->uid = uid;
257 new_session->gid = gid;
258
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259 ret = snapshot_init(&new_session->snapshot);
260 if (ret < 0) {
261 ret = LTTNG_ERR_NOMEM;
262 goto error;
263 }
264
b5541356 265 /* Add new session to the session list */
54d01ffb 266 session_lock_list();
a991f516 267 new_session->id = add_session_list(new_session);
54d01ffb 268 session_unlock_list();
b5541356 269
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270 /*
271 * Consumer is let to NULL since the create_session_uri command will set it
272 * up and, if valid, assign it to the session.
273 */
274
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275 DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
276 name, new_session->id, new_session->uid, new_session->gid);
b082db07 277
f73fabfd 278 return LTTNG_OK;
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279
280error:
f3ed775e 281error_asprintf:
0e428499 282 free(new_session);
5b74c7b1 283
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284error_malloc:
285 return ret;
5b74c7b1 286}
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287
288/*
289 * Check if the UID or GID match the session. Root user has access to all
290 * sessions.
291 */
292int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
293{
294 assert(session);
295
296 if (uid != session->uid && gid != session->gid && uid != 0) {
297 return 0;
298 } else {
299 return 1;
300 }
301}
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