Fix: liblttng-ctl: unreported truncations when copying strings
[lttng-tools.git] / src / lib / lttng-ctl / channel.c
1 /*
2 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * SPDX-License-Identifier: LGPL-2.1-only
5 *
6 */
7
8 #include <lttng/notification/notification-internal.h>
9 #include <lttng/notification/channel-internal.h>
10 #include <lttng/condition/condition-internal.h>
11 #include <lttng/endpoint.h>
12 #include <common/defaults.h>
13 #include <common/error.h>
14 #include <common/dynamic-buffer.h>
15 #include <common/utils.h>
16 #include <common/defaults.h>
17 #include <common/payload.h>
18 #include <common/payload-view.h>
19 #include <common/unix.h>
20 #include <assert.h>
21 #include "lttng-ctl-helper.h"
22 #include <common/compat/poll.h>
23
24 static
25 int handshake(struct lttng_notification_channel *channel);
26
27 /*
28 * Populates the reception buffer with the next complete message.
29 * The caller must acquire the channel's lock.
30 */
31 static
32 int receive_message(struct lttng_notification_channel *channel)
33 {
34 ssize_t ret;
35 struct lttng_notification_channel_message msg;
36
37 lttng_payload_clear(&channel->reception_payload);
38
39 ret = lttcomm_recv_unix_sock(channel->socket, &msg, sizeof(msg));
40 if (ret <= 0) {
41 ret = -1;
42 goto error;
43 }
44
45 if (msg.size > DEFAULT_MAX_NOTIFICATION_CLIENT_MESSAGE_PAYLOAD_SIZE) {
46 ret = -1;
47 goto error;
48 }
49
50 /* Add message header at buffer's start. */
51 ret = lttng_dynamic_buffer_append(&channel->reception_payload.buffer, &msg,
52 sizeof(msg));
53 if (ret) {
54 goto error;
55 }
56
57 /* Reserve space for the payload. */
58 ret = lttng_dynamic_buffer_set_size(&channel->reception_payload.buffer,
59 channel->reception_payload.buffer.size + msg.size);
60 if (ret) {
61 goto error;
62 }
63
64 /* Receive message payload. */
65 ret = lttcomm_recv_unix_sock(channel->socket,
66 channel->reception_payload.buffer.data + sizeof(msg), msg.size);
67 if (ret < (ssize_t) msg.size) {
68 ret = -1;
69 goto error;
70 }
71
72 /* Receive message fds. */
73 if (msg.fds != 0) {
74 ret = lttcomm_recv_payload_fds_unix_sock(channel->socket,
75 msg.fds, &channel->reception_payload);
76 if (ret < sizeof(int) * msg.fds) {
77 ret = -1;
78 goto error;
79 }
80 }
81 ret = 0;
82 end:
83 return ret;
84 error:
85 lttng_payload_clear(&channel->reception_payload);
86 goto end;
87 }
88
89 static
90 enum lttng_notification_channel_message_type get_current_message_type(
91 struct lttng_notification_channel *channel)
92 {
93 struct lttng_notification_channel_message *msg;
94
95 assert(channel->reception_payload.buffer.size >= sizeof(*msg));
96
97 msg = (struct lttng_notification_channel_message *)
98 channel->reception_payload.buffer.data;
99 return (enum lttng_notification_channel_message_type) msg->type;
100 }
101
102 static
103 struct lttng_notification *create_notification_from_current_message(
104 struct lttng_notification_channel *channel)
105 {
106 ssize_t ret;
107 struct lttng_notification *notification = NULL;
108
109 if (channel->reception_payload.buffer.size <=
110 sizeof(struct lttng_notification_channel_message)) {
111 goto end;
112 }
113
114 {
115 struct lttng_payload_view view = lttng_payload_view_from_payload(
116 &channel->reception_payload,
117 sizeof(struct lttng_notification_channel_message),
118 -1);
119
120 ret = lttng_notification_create_from_payload(
121 &view, &notification);
122 }
123
124 if (ret != channel->reception_payload.buffer.size -
125 sizeof(struct lttng_notification_channel_message)) {
126 lttng_notification_destroy(notification);
127 notification = NULL;
128 goto end;
129 }
130 end:
131 return notification;
132 }
133
134 struct lttng_notification_channel *lttng_notification_channel_create(
135 struct lttng_endpoint *endpoint)
136 {
137 int fd, ret;
138 bool is_in_tracing_group = false, is_root = false;
139 char *sock_path = NULL;
140 struct lttng_notification_channel *channel = NULL;
141
142 if (!endpoint ||
143 endpoint != lttng_session_daemon_notification_endpoint) {
144 goto end;
145 }
146
147 sock_path = zmalloc(LTTNG_PATH_MAX);
148 if (!sock_path) {
149 goto end;
150 }
151
152 channel = zmalloc(sizeof(struct lttng_notification_channel));
153 if (!channel) {
154 goto end;
155 }
156 channel->socket = -1;
157 pthread_mutex_init(&channel->lock, NULL);
158 lttng_payload_init(&channel->reception_payload);
159 CDS_INIT_LIST_HEAD(&channel->pending_notifications.list);
160
161 is_root = (getuid() == 0);
162 if (!is_root) {
163 is_in_tracing_group = lttng_check_tracing_group();
164 }
165
166 if (is_root || is_in_tracing_group) {
167 ret = lttng_strncpy(sock_path,
168 DEFAULT_GLOBAL_NOTIFICATION_CHANNEL_UNIX_SOCK,
169 LTTNG_PATH_MAX);
170 if (ret) {
171 ret = -LTTNG_ERR_INVALID;
172 goto error;
173 }
174
175 ret = lttcomm_connect_unix_sock(sock_path);
176 if (ret >= 0) {
177 fd = ret;
178 goto set_fd;
179 }
180 }
181
182 /* Fallback to local session daemon. */
183 ret = snprintf(sock_path, LTTNG_PATH_MAX,
184 DEFAULT_HOME_NOTIFICATION_CHANNEL_UNIX_SOCK,
185 utils_get_home_dir());
186 if (ret < 0 || ret >= LTTNG_PATH_MAX) {
187 goto error;
188 }
189
190 ret = lttcomm_connect_unix_sock(sock_path);
191 if (ret < 0) {
192 goto error;
193 }
194 fd = ret;
195
196 set_fd:
197 channel->socket = fd;
198
199 ret = handshake(channel);
200 if (ret) {
201 goto error;
202 }
203 end:
204 free(sock_path);
205 return channel;
206 error:
207 lttng_notification_channel_destroy(channel);
208 channel = NULL;
209 goto end;
210 }
211
212 enum lttng_notification_channel_status
213 lttng_notification_channel_get_next_notification(
214 struct lttng_notification_channel *channel,
215 struct lttng_notification **_notification)
216 {
217 int ret;
218 struct lttng_notification *notification = NULL;
219 enum lttng_notification_channel_status status =
220 LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
221 struct lttng_poll_event events;
222
223 if (!channel || !_notification) {
224 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
225 goto end;
226 }
227
228 pthread_mutex_lock(&channel->lock);
229
230 if (channel->pending_notifications.count) {
231 struct pending_notification *pending_notification;
232
233 assert(!cds_list_empty(&channel->pending_notifications.list));
234
235 /* Deliver one of the pending notifications. */
236 pending_notification = cds_list_first_entry(
237 &channel->pending_notifications.list,
238 struct pending_notification,
239 node);
240 notification = pending_notification->notification;
241 if (!notification) {
242 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
243 }
244 cds_list_del(&pending_notification->node);
245 channel->pending_notifications.count--;
246 free(pending_notification);
247 goto end_unlock;
248 }
249
250 /*
251 * Block on interruptible epoll/poll() instead of the message reception
252 * itself as the recvmsg() wrappers always restart on EINTR. We choose
253 * to wait using interruptible epoll/poll() in order to:
254 * 1) Return if a signal occurs,
255 * 2) Not deal with partially received messages.
256 *
257 * The drawback to this approach is that we assume that messages
258 * are complete/well formed. If a message is shorter than its
259 * announced length, receive_message() will block on recvmsg()
260 * and never return (even if a signal is received).
261 */
262 ret = lttng_poll_create(&events, 1, LTTNG_CLOEXEC);
263 if (ret < 0) {
264 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
265 goto end_unlock;
266 }
267 ret = lttng_poll_add(&events, channel->socket, LPOLLIN | LPOLLERR);
268 if (ret < 0) {
269 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
270 goto end_clean_poll;
271 }
272 ret = lttng_poll_wait_interruptible(&events, -1);
273 if (ret <= 0) {
274 status = (ret == -1 && errno == EINTR) ?
275 LTTNG_NOTIFICATION_CHANNEL_STATUS_INTERRUPTED :
276 LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
277 goto end_clean_poll;
278 }
279
280 ret = receive_message(channel);
281 if (ret) {
282 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
283 goto end_clean_poll;
284 }
285
286 switch (get_current_message_type(channel)) {
287 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
288 notification = create_notification_from_current_message(
289 channel);
290 if (!notification) {
291 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
292 goto end_clean_poll;
293 }
294 break;
295 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
296 /* No payload to consume. */
297 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
298 break;
299 default:
300 /* Protocol error. */
301 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
302 goto end_clean_poll;
303 }
304
305 end_clean_poll:
306 lttng_poll_clean(&events);
307 end_unlock:
308 pthread_mutex_unlock(&channel->lock);
309 *_notification = notification;
310 end:
311 return status;
312 }
313
314 static
315 int enqueue_dropped_notification(
316 struct lttng_notification_channel *channel)
317 {
318 int ret = 0;
319 struct pending_notification *pending_notification;
320 struct cds_list_head *last_element =
321 channel->pending_notifications.list.prev;
322
323 pending_notification = caa_container_of(last_element,
324 struct pending_notification, node);
325 if (!pending_notification->notification) {
326 /*
327 * The last enqueued notification indicates dropped
328 * notifications; there is nothing to do as we group
329 * dropped notifications together.
330 */
331 goto end;
332 }
333
334 if (channel->pending_notifications.count >=
335 DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT &&
336 pending_notification->notification) {
337 /*
338 * Discard the last enqueued notification to indicate
339 * that notifications were dropped at this point.
340 */
341 lttng_notification_destroy(
342 pending_notification->notification);
343 pending_notification->notification = NULL;
344 goto end;
345 }
346
347 pending_notification = zmalloc(sizeof(*pending_notification));
348 if (!pending_notification) {
349 ret = -1;
350 goto end;
351 }
352 CDS_INIT_LIST_HEAD(&pending_notification->node);
353 cds_list_add(&pending_notification->node,
354 &channel->pending_notifications.list);
355 channel->pending_notifications.count++;
356 end:
357 return ret;
358 }
359
360 static
361 int enqueue_notification_from_current_message(
362 struct lttng_notification_channel *channel)
363 {
364 int ret = 0;
365 struct lttng_notification *notification;
366 struct pending_notification *pending_notification;
367
368 if (channel->pending_notifications.count >=
369 DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT) {
370 /* Drop the notification. */
371 ret = enqueue_dropped_notification(channel);
372 goto end;
373 }
374
375 pending_notification = zmalloc(sizeof(*pending_notification));
376 if (!pending_notification) {
377 ret = -1;
378 goto error;
379 }
380 CDS_INIT_LIST_HEAD(&pending_notification->node);
381
382 notification = create_notification_from_current_message(channel);
383 if (!notification) {
384 ret = -1;
385 goto error;
386 }
387
388 pending_notification->notification = notification;
389 cds_list_add(&pending_notification->node,
390 &channel->pending_notifications.list);
391 channel->pending_notifications.count++;
392 end:
393 return ret;
394 error:
395 free(pending_notification);
396 goto end;
397 }
398
399 enum lttng_notification_channel_status
400 lttng_notification_channel_has_pending_notification(
401 struct lttng_notification_channel *channel,
402 bool *_notification_pending)
403 {
404 int ret;
405 enum lttng_notification_channel_status status =
406 LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
407 struct lttng_poll_event events;
408
409 if (!channel || !_notification_pending) {
410 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
411 goto end;
412 }
413
414 pthread_mutex_lock(&channel->lock);
415
416 if (channel->pending_notifications.count) {
417 *_notification_pending = true;
418 goto end_unlock;
419 }
420
421 if (channel->socket < 0) {
422 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED;
423 goto end_unlock;
424 }
425
426 /*
427 * Check, without blocking, if data is available on the channel's
428 * socket. If there is data available, it is safe to read (blocking)
429 * on the socket for a message from the session daemon.
430 *
431 * Since all commands wait for the session daemon's reply before
432 * releasing the channel's lock, the protocol only allows for
433 * notifications and "notification dropped" messages to come
434 * through. If we receive a different message type, it is
435 * considered a protocol error.
436 *
437 * Note that this function is not guaranteed not to block. This
438 * will block until our peer (the session daemon) has sent a complete
439 * message if we see data available on the socket. If the peer does
440 * not respect the protocol, this may block indefinitely.
441 */
442 ret = lttng_poll_create(&events, 1, LTTNG_CLOEXEC);
443 if (ret < 0) {
444 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
445 goto end_unlock;
446 }
447 ret = lttng_poll_add(&events, channel->socket, LPOLLIN | LPOLLERR);
448 if (ret < 0) {
449 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
450 goto end_clean_poll;
451 }
452 /* timeout = 0: return immediately. */
453 ret = lttng_poll_wait_interruptible(&events, 0);
454 if (ret == 0) {
455 /* No data available. */
456 *_notification_pending = false;
457 goto end_clean_poll;
458 } else if (ret < 0) {
459 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
460 goto end_clean_poll;
461 }
462
463 /* Data available on socket. */
464 ret = receive_message(channel);
465 if (ret) {
466 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
467 goto end_clean_poll;
468 }
469
470 switch (get_current_message_type(channel)) {
471 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
472 ret = enqueue_notification_from_current_message(channel);
473 if (ret) {
474 goto end_clean_poll;
475 }
476 *_notification_pending = true;
477 break;
478 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
479 ret = enqueue_dropped_notification(channel);
480 if (ret) {
481 goto end_clean_poll;
482 }
483 *_notification_pending = true;
484 break;
485 default:
486 /* Protocol error. */
487 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
488 goto end_clean_poll;
489 }
490
491 end_clean_poll:
492 lttng_poll_clean(&events);
493 end_unlock:
494 pthread_mutex_unlock(&channel->lock);
495 end:
496 return status;
497 }
498
499 static
500 int receive_command_reply(struct lttng_notification_channel *channel,
501 enum lttng_notification_channel_status *status)
502 {
503 int ret;
504 struct lttng_notification_channel_command_reply *reply;
505
506 while (true) {
507 enum lttng_notification_channel_message_type msg_type;
508
509 ret = receive_message(channel);
510 if (ret) {
511 goto end;
512 }
513
514 msg_type = get_current_message_type(channel);
515 switch (msg_type) {
516 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY:
517 goto exit_loop;
518 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
519 ret = enqueue_notification_from_current_message(
520 channel);
521 if (ret) {
522 goto end;
523 }
524 break;
525 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
526 ret = enqueue_dropped_notification(channel);
527 if (ret) {
528 goto end;
529 }
530 break;
531 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
532 {
533 struct lttng_notification_channel_command_handshake *handshake;
534
535 handshake = (struct lttng_notification_channel_command_handshake *)
536 (channel->reception_payload.buffer.data +
537 sizeof(struct lttng_notification_channel_message));
538 channel->version.major = handshake->major;
539 channel->version.minor = handshake->minor;
540 channel->version.set = true;
541 break;
542 }
543 default:
544 ret = -1;
545 goto end;
546 }
547 }
548
549 exit_loop:
550 if (channel->reception_payload.buffer.size <
551 (sizeof(struct lttng_notification_channel_message) +
552 sizeof(*reply))) {
553 /* Invalid message received. */
554 ret = -1;
555 goto end;
556 }
557
558 reply = (struct lttng_notification_channel_command_reply *)
559 (channel->reception_payload.buffer.data +
560 sizeof(struct lttng_notification_channel_message));
561 *status = (enum lttng_notification_channel_status) reply->status;
562 end:
563 return ret;
564 }
565
566 static
567 int handshake(struct lttng_notification_channel *channel)
568 {
569 ssize_t ret;
570 enum lttng_notification_channel_status status =
571 LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
572 struct lttng_notification_channel_command_handshake handshake = {
573 .major = LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR,
574 .minor = LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR,
575 };
576 struct lttng_notification_channel_message msg_header = {
577 .type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE,
578 .size = sizeof(handshake),
579 };
580 char send_buffer[sizeof(msg_header) + sizeof(handshake)];
581
582 memcpy(send_buffer, &msg_header, sizeof(msg_header));
583 memcpy(send_buffer + sizeof(msg_header), &handshake, sizeof(handshake));
584
585 pthread_mutex_lock(&channel->lock);
586
587 ret = lttcomm_send_creds_unix_sock(channel->socket, send_buffer,
588 sizeof(send_buffer));
589 if (ret < 0) {
590 goto end_unlock;
591 }
592
593 /* Receive handshake info from the sessiond. */
594 ret = receive_command_reply(channel, &status);
595 if (ret < 0) {
596 goto end_unlock;
597 }
598
599 if (!channel->version.set) {
600 ret = -1;
601 goto end_unlock;
602 }
603
604 if (channel->version.major != LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR) {
605 ret = -1;
606 goto end_unlock;
607 }
608
609 end_unlock:
610 pthread_mutex_unlock(&channel->lock);
611 return ret;
612 }
613
614 static
615 enum lttng_notification_channel_status send_condition_command(
616 struct lttng_notification_channel *channel,
617 enum lttng_notification_channel_message_type type,
618 const struct lttng_condition *condition)
619 {
620 int socket;
621 ssize_t ret;
622 enum lttng_notification_channel_status status =
623 LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
624 struct lttng_payload payload;
625 struct lttng_notification_channel_message cmd_header = {
626 .type = (int8_t) type,
627 };
628
629 lttng_payload_init(&payload);
630
631 if (!channel) {
632 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
633 goto end;
634 }
635
636 assert(type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE ||
637 type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE);
638
639 pthread_mutex_lock(&channel->lock);
640 socket = channel->socket;
641
642 if (!lttng_condition_validate(condition)) {
643 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
644 goto end_unlock;
645 }
646
647 ret = lttng_dynamic_buffer_append(&payload.buffer, &cmd_header,
648 sizeof(cmd_header));
649 if (ret) {
650 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
651 goto end_unlock;
652 }
653
654 ret = lttng_condition_serialize(condition, &payload);
655 if (ret) {
656 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
657 goto end_unlock;
658 }
659
660 /* Update payload length. */
661 ((struct lttng_notification_channel_message *) payload.buffer.data)->size =
662 (uint32_t) (payload.buffer.size - sizeof(cmd_header));
663
664 {
665 struct lttng_payload_view pv =
666 lttng_payload_view_from_payload(
667 &payload, 0, -1);
668 const int fd_count =
669 lttng_payload_view_get_fd_handle_count(&pv);
670
671 /* Update fd count. */
672 ((struct lttng_notification_channel_message *) payload.buffer.data)->fds =
673 (uint32_t) fd_count;
674
675 ret = lttcomm_send_unix_sock(
676 socket, pv.buffer.data, pv.buffer.size);
677 if (ret < 0) {
678 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
679 goto end_unlock;
680 }
681
682 /* Pass fds if present. */
683 if (fd_count > 0) {
684 ret = lttcomm_send_payload_view_fds_unix_sock(socket,
685 &pv);
686 if (ret < 0) {
687 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
688 goto end_unlock;
689 }
690 }
691 }
692
693 ret = receive_command_reply(channel, &status);
694 if (ret < 0) {
695 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
696 goto end_unlock;
697 }
698 end_unlock:
699 pthread_mutex_unlock(&channel->lock);
700 end:
701 lttng_payload_reset(&payload);
702 return status;
703 }
704
705 enum lttng_notification_channel_status lttng_notification_channel_subscribe(
706 struct lttng_notification_channel *channel,
707 const struct lttng_condition *condition)
708 {
709 return send_condition_command(channel,
710 LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE,
711 condition);
712 }
713
714 enum lttng_notification_channel_status lttng_notification_channel_unsubscribe(
715 struct lttng_notification_channel *channel,
716 const struct lttng_condition *condition)
717 {
718 return send_condition_command(channel,
719 LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE,
720 condition);
721 }
722
723 void lttng_notification_channel_destroy(
724 struct lttng_notification_channel *channel)
725 {
726 if (!channel) {
727 return;
728 }
729
730 if (channel->socket >= 0) {
731 (void) lttcomm_close_unix_sock(channel->socket);
732 }
733 pthread_mutex_destroy(&channel->lock);
734 lttng_payload_reset(&channel->reception_payload);
735 free(channel);
736 }
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