26eda52d97d1ad992c7b534b461c121eee9b6d00
[lttng-tools.git] / src / common / unix.c
1 /*
2 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
3 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * SPDX-License-Identifier: GPL-2.0-only
6 *
7 */
8
9 #define _LGPL_SOURCE
10 #include <assert.h>
11 #include <limits.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <sys/stat.h>
16 #include <sys/types.h>
17 #include <unistd.h>
18 #include <errno.h>
19
20 #include <common/common.h>
21 #include <common/sessiond-comm/sessiond-comm.h>
22
23 #include "unix.h"
24
25 /*
26 * Connect to unix socket using the path name.
27 */
28 LTTNG_HIDDEN
29 int lttcomm_connect_unix_sock(const char *pathname)
30 {
31 struct sockaddr_un s_un;
32 int fd, ret, closeret;
33
34 if (strlen(pathname) >= sizeof(s_un.sun_path)) {
35 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
36 pathname, strlen(pathname) + 1,
37 sizeof(s_un.sun_path));
38 ret = -ENAMETOOLONG;
39 goto error;
40 }
41
42 fd = socket(PF_UNIX, SOCK_STREAM, 0);
43 if (fd < 0) {
44 PERROR("socket");
45 ret = fd;
46 goto error;
47 }
48
49 memset(&s_un, 0, sizeof(s_un));
50 s_un.sun_family = AF_UNIX;
51 strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
52 s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
53
54 ret = connect(fd, (struct sockaddr *) &s_un, sizeof(s_un));
55 if (ret < 0) {
56 /*
57 * Don't print message on connect error, because connect is used in
58 * normal execution to detect if sessiond is alive.
59 */
60 goto error_connect;
61 }
62
63 return fd;
64
65 error_connect:
66 closeret = close(fd);
67 if (closeret) {
68 PERROR("close");
69 }
70 error:
71 return ret;
72 }
73
74 /*
75 * Do an accept(2) on the sock and return the new file descriptor. The socket
76 * MUST be bind(2) before.
77 */
78 LTTNG_HIDDEN
79 int lttcomm_accept_unix_sock(int sock)
80 {
81 int new_fd;
82 struct sockaddr_un s_un;
83 socklen_t len = sizeof(s_un);
84
85 /* Blocking call */
86 new_fd = accept(sock, (struct sockaddr *) &s_un, &len);
87 if (new_fd < 0) {
88 PERROR("accept");
89 }
90
91 return new_fd;
92 }
93
94 LTTNG_HIDDEN
95 int lttcomm_create_anon_unix_socketpair(int *fds)
96 {
97 if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
98 PERROR("socketpair");
99 return -1;
100 }
101 return 0;
102 }
103
104 /*
105 * Creates a AF_UNIX local socket using pathname bind the socket upon creation
106 * and return the fd.
107 */
108 LTTNG_HIDDEN
109 int lttcomm_create_unix_sock(const char *pathname)
110 {
111 struct sockaddr_un s_un;
112 int fd = -1;
113 int ret = -1;
114
115 if (strlen(pathname) >= sizeof(s_un.sun_path)) {
116 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
117 pathname, strlen(pathname) + 1,
118 sizeof(s_un.sun_path));
119 ret = -ENAMETOOLONG;
120 goto error;
121 }
122
123 /* Create server socket */
124 if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
125 PERROR("socket");
126 goto error;
127 }
128
129 memset(&s_un, 0, sizeof(s_un));
130 s_un.sun_family = AF_UNIX;
131 strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
132 s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
133
134 /* Unlink the old file if present */
135 (void) unlink(pathname);
136 ret = bind(fd, (struct sockaddr *) &s_un, sizeof(s_un));
137 if (ret < 0) {
138 PERROR("bind");
139 goto error;
140 }
141
142 return fd;
143
144 error:
145 if (fd >= 0) {
146 if (close(fd) < 0) {
147 PERROR("close create unix sock");
148 }
149 }
150 return ret;
151 }
152
153 /*
154 * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
155 */
156 LTTNG_HIDDEN
157 int lttcomm_listen_unix_sock(int sock)
158 {
159 int ret;
160
161 ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
162 if (ret < 0) {
163 PERROR("listen");
164 }
165
166 return ret;
167 }
168
169 /*
170 * Receive data of size len in put that data into the buf param. Using recvmsg
171 * API.
172 *
173 * Return the size of received data.
174 */
175 LTTNG_HIDDEN
176 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
177 {
178 struct msghdr msg;
179 struct iovec iov[1];
180 ssize_t ret = -1;
181 size_t len_last;
182
183 memset(&msg, 0, sizeof(msg));
184
185 iov[0].iov_base = buf;
186 iov[0].iov_len = len;
187 msg.msg_iov = iov;
188 msg.msg_iovlen = 1;
189
190 do {
191 len_last = iov[0].iov_len;
192 ret = lttng_recvmsg_nosigpipe(sock, &msg);
193 if (ret > 0) {
194 iov[0].iov_base += ret;
195 iov[0].iov_len -= ret;
196 assert(ret <= len_last);
197 }
198 } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
199 if (ret < 0) {
200 PERROR("recvmsg");
201 } else if (ret > 0) {
202 ret = len;
203 }
204 /* Else ret = 0 meaning an orderly shutdown. */
205
206 return ret;
207 }
208
209 /*
210 * Receive data of size len in put that data into the buf param. Using recvmsg
211 * API. Only use with sockets set in non-blocking mode.
212 *
213 * Return the size of received data.
214 */
215 LTTNG_HIDDEN
216 ssize_t lttcomm_recv_unix_sock_non_block(int sock, void *buf, size_t len)
217 {
218 struct msghdr msg;
219 struct iovec iov[1];
220 ssize_t ret;
221
222 memset(&msg, 0, sizeof(msg));
223
224 iov[0].iov_base = buf;
225 iov[0].iov_len = len;
226 msg.msg_iov = iov;
227 msg.msg_iovlen = 1;
228
229 retry:
230 ret = lttng_recvmsg_nosigpipe(sock, &msg);
231 if (ret < 0) {
232 if (errno == EINTR) {
233 goto retry;
234 } else {
235 /* We consider EPIPE and EAGAIN as expected. */
236 if (!lttng_opt_quiet &&
237 (errno != EPIPE && errno != EAGAIN)) {
238 PERROR("recvmsg");
239 }
240 goto end;
241 }
242 }
243 ret = len;
244 end:
245 return ret;
246 }
247
248 /*
249 * Send buf data of size len. Using sendmsg API.
250 *
251 * Return the size of sent data.
252 */
253 LTTNG_HIDDEN
254 ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len)
255 {
256 struct msghdr msg;
257 struct iovec iov[1];
258 ssize_t ret;
259
260 memset(&msg, 0, sizeof(msg));
261
262 iov[0].iov_base = (void *) buf;
263 iov[0].iov_len = len;
264 msg.msg_iov = iov;
265 msg.msg_iovlen = 1;
266
267 while (iov[0].iov_len) {
268 ret = sendmsg(sock, &msg, 0);
269 if (ret < 0) {
270 if (errno == EINTR) {
271 continue;
272 } else {
273 /*
274 * Only warn about EPIPE when quiet mode is
275 * deactivated.
276 * We consider EPIPE as expected.
277 */
278 if (errno != EPIPE || !lttng_opt_quiet) {
279 PERROR("sendmsg");
280 }
281 goto end;
282 }
283 }
284 iov[0].iov_len -= ret;
285 iov[0].iov_base += ret;
286 }
287 ret = len;
288 end:
289 return ret;
290 }
291
292 /*
293 * Send buf data of size len. Using sendmsg API.
294 * Only use with non-blocking sockets. The difference with the blocking version
295 * of the function is that this one does not retry to send on partial sends,
296 * except if the interruption was caused by a signal (EINTR).
297 *
298 * Return the size of sent data.
299 */
300 LTTNG_HIDDEN
301 ssize_t lttcomm_send_unix_sock_non_block(int sock, const void *buf, size_t len)
302 {
303 struct msghdr msg;
304 struct iovec iov[1];
305 ssize_t ret;
306
307 memset(&msg, 0, sizeof(msg));
308
309 iov[0].iov_base = (void *) buf;
310 iov[0].iov_len = len;
311 msg.msg_iov = iov;
312 msg.msg_iovlen = 1;
313
314 retry:
315 ret = sendmsg(sock, &msg, 0);
316 if (ret < 0) {
317 if (errno == EINTR) {
318 goto retry;
319 } else {
320 /* We consider EPIPE and EAGAIN as expected. */
321 if (!lttng_opt_quiet &&
322 (errno != EPIPE && errno != EAGAIN)) {
323 PERROR("sendmsg");
324 }
325 goto end;
326 }
327 }
328 ret = len;
329 end:
330 return ret;
331 }
332
333 /*
334 * Shutdown cleanly a unix socket.
335 */
336 LTTNG_HIDDEN
337 int lttcomm_close_unix_sock(int sock)
338 {
339 int ret, closeret;
340
341 /* Shutdown receptions and transmissions */
342 ret = shutdown(sock, SHUT_RDWR);
343 if (ret < 0) {
344 PERROR("shutdown");
345 }
346
347 closeret = close(sock);
348 if (closeret) {
349 PERROR("close");
350 }
351
352 return ret;
353 }
354
355 /*
356 * Send a message accompanied by fd(s) over a unix socket.
357 *
358 * Returns the size of data sent, or negative error value.
359 */
360 LTTNG_HIDDEN
361 ssize_t lttcomm_send_fds_unix_sock(int sock, const int *fds, size_t nb_fd)
362 {
363 struct msghdr msg;
364 struct cmsghdr *cmptr;
365 struct iovec iov[1];
366 ssize_t ret = -1;
367 unsigned int sizeof_fds = nb_fd * sizeof(int);
368 char tmp[CMSG_SPACE(sizeof_fds)];
369 char dummy = 0;
370
371 memset(&msg, 0, sizeof(msg));
372 memset(tmp, 0, sizeof(tmp));
373
374 if (nb_fd > LTTCOMM_MAX_SEND_FDS)
375 return -EINVAL;
376
377 msg.msg_control = (caddr_t)tmp;
378 msg.msg_controllen = CMSG_LEN(sizeof_fds);
379
380 cmptr = CMSG_FIRSTHDR(&msg);
381 if (!cmptr) {
382 return -1;
383 }
384
385 cmptr->cmsg_level = SOL_SOCKET;
386 cmptr->cmsg_type = SCM_RIGHTS;
387 cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
388 memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
389 /* Sum of the length of all control messages in the buffer: */
390 msg.msg_controllen = cmptr->cmsg_len;
391
392 iov[0].iov_base = &dummy;
393 iov[0].iov_len = 1;
394 msg.msg_iov = iov;
395 msg.msg_iovlen = 1;
396
397 do {
398 ret = sendmsg(sock, &msg, 0);
399 } while (ret < 0 && errno == EINTR);
400 if (ret < 0) {
401 /*
402 * Only warn about EPIPE when quiet mode is deactivated.
403 * We consider EPIPE as expected.
404 */
405 if (errno != EPIPE || !lttng_opt_quiet) {
406 PERROR("sendmsg");
407 }
408 }
409 return ret;
410 }
411
412 /*
413 * Recv a message accompanied by fd(s) from a unix socket.
414 *
415 * Returns the size of received data, or negative error value.
416 *
417 * Expect at most "nb_fd" file descriptors. Returns the number of fd
418 * actually received in nb_fd.
419 */
420 LTTNG_HIDDEN
421 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
422 {
423 struct iovec iov[1];
424 ssize_t ret = 0;
425 struct cmsghdr *cmsg;
426 size_t sizeof_fds = nb_fd * sizeof(int);
427
428 #ifdef __linux__
429 /* Account for the struct ucred cmsg in the buffer size */
430 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds) + CMSG_SPACE(sizeof(struct ucred))
431 #else
432 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds)
433 #endif /* __linux__ */
434
435 char recv_buf[LTTNG_SOCK_RECV_FDS_BUF_SIZE];
436 struct msghdr msg;
437 char dummy;
438
439 memset(&msg, 0, sizeof(msg));
440
441 /* Prepare to receive the structures */
442 iov[0].iov_base = &dummy;
443 iov[0].iov_len = 1;
444 msg.msg_iov = iov;
445 msg.msg_iovlen = 1;
446
447 cmsg = (struct cmsghdr *) recv_buf;
448 cmsg->cmsg_len = CMSG_LEN(sizeof_fds);
449 cmsg->cmsg_level = SOL_SOCKET;
450 cmsg->cmsg_type = SCM_RIGHTS;
451
452 msg.msg_control = cmsg;
453 msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
454 msg.msg_flags = 0;
455
456 do {
457 ret = recvmsg(sock, &msg, 0);
458 } while (ret < 0 && errno == EINTR);
459 if (ret < 0) {
460 PERROR("recvmsg fds");
461 goto end;
462 }
463
464 if (ret != 1) {
465 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
466 ret, 1);
467 goto end;
468 }
469
470 if (msg.msg_flags & MSG_CTRUNC) {
471 fprintf(stderr, "Error: Control message truncated.\n");
472 ret = -1;
473 goto end;
474 }
475
476 /*
477 * If the socket was configured with SO_PASSCRED, the kernel will add a
478 * control message (cmsg) to the ancillary data of the unix socket. We
479 * need to expect a cmsg of the SCM_CREDENTIALS as the first control
480 * message.
481 */
482 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
483 if (cmsg->cmsg_level != SOL_SOCKET) {
484 fprintf(stderr, "Error: The socket needs to be of type SOL_SOCKET\n");
485 ret = -1;
486 goto end;
487 }
488 if (cmsg->cmsg_type == SCM_RIGHTS) {
489 /*
490 * We found the controle message for file descriptors,
491 * now copy the fds to the fds ptr and return success.
492 */
493 if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
494 fprintf(stderr, "Error: Received %zu bytes of"
495 "ancillary data for FDs, expected %zu\n",
496 (size_t) cmsg->cmsg_len,
497 (size_t) CMSG_LEN(sizeof_fds));
498 ret = -1;
499 goto end;
500 }
501 memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
502 ret = sizeof_fds;
503 goto end;
504 }
505 #ifdef __linux__
506 if (cmsg->cmsg_type == SCM_CREDENTIALS) {
507 /*
508 * Expect credentials to be sent when expecting fds even
509 * if no credential were include in the send(). The
510 * kernel adds them...
511 */
512 ret = -1;
513 }
514 #endif /* __linux__ */
515 }
516 end:
517 return ret;
518 }
519
520 /*
521 * Send a message with credentials over a unix socket.
522 *
523 * Returns the size of data sent, or negative error value.
524 */
525 LTTNG_HIDDEN
526 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
527 {
528 struct msghdr msg;
529 struct iovec iov[1];
530 ssize_t ret = -1;
531 #ifdef __linux__
532 struct cmsghdr *cmptr;
533 size_t sizeof_cred = sizeof(lttng_sock_cred);
534 char anc_buf[CMSG_SPACE(sizeof_cred)];
535 lttng_sock_cred *creds;
536
537 memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
538 #endif /* __linux__ */
539
540 memset(&msg, 0, sizeof(msg));
541
542 iov[0].iov_base = buf;
543 iov[0].iov_len = len;
544 msg.msg_iov = iov;
545 msg.msg_iovlen = 1;
546
547 #ifdef __linux__
548 msg.msg_control = (caddr_t) anc_buf;
549 msg.msg_controllen = CMSG_LEN(sizeof_cred);
550
551 cmptr = CMSG_FIRSTHDR(&msg);
552 if (!cmptr) {
553 return -1;
554 }
555 cmptr->cmsg_level = SOL_SOCKET;
556 cmptr->cmsg_type = LTTNG_SOCK_CREDS;
557 cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
558
559 creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
560
561 LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
562 LTTNG_SOCK_SET_GID_CRED(creds, getegid());
563 LTTNG_SOCK_SET_PID_CRED(creds, getpid());
564 #endif /* __linux__ */
565
566 do {
567 ret = sendmsg(sock, &msg, 0);
568 } while (ret < 0 && errno == EINTR);
569 if (ret < 0) {
570 /*
571 * Only warn about EPIPE when quiet mode is deactivated.
572 * We consider EPIPE as expected.
573 */
574 if (errno != EPIPE || !lttng_opt_quiet) {
575 PERROR("sendmsg");
576 }
577 }
578 return ret;
579 }
580
581 /*
582 * Recv a message accompanied with credentials from a unix socket.
583 *
584 * Returns the size of received data, or negative error value.
585 */
586 LTTNG_HIDDEN
587 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
588 lttng_sock_cred *creds)
589 {
590 struct msghdr msg;
591 struct iovec iov[1];
592 ssize_t ret;
593 size_t len_last;
594 #ifdef __linux__
595 struct cmsghdr *cmptr;
596 size_t sizeof_cred = sizeof(lttng_sock_cred);
597 char anc_buf[CMSG_SPACE(sizeof_cred)];
598 #endif /* __linux__ */
599
600 memset(&msg, 0, sizeof(msg));
601
602 /* Not allowed */
603 if (creds == NULL) {
604 ret = -1;
605 goto end;
606 }
607
608 /* Prepare to receive the structures */
609 iov[0].iov_base = buf;
610 iov[0].iov_len = len;
611 msg.msg_iov = iov;
612 msg.msg_iovlen = 1;
613
614 #ifdef __linux__
615 msg.msg_control = anc_buf;
616 msg.msg_controllen = sizeof(anc_buf);
617 #endif /* __linux__ */
618
619 do {
620 len_last = iov[0].iov_len;
621 ret = recvmsg(sock, &msg, 0);
622 if (ret > 0) {
623 iov[0].iov_base += ret;
624 iov[0].iov_len -= ret;
625 assert(ret <= len_last);
626 }
627 } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
628 if (ret < 0) {
629 PERROR("recvmsg fds");
630 goto end;
631 } else if (ret > 0) {
632 ret = len;
633 }
634 /* Else ret = 0 meaning an orderly shutdown. */
635
636 #ifdef __linux__
637 if (msg.msg_flags & MSG_CTRUNC) {
638 fprintf(stderr, "Error: Control message truncated.\n");
639 ret = -1;
640 goto end;
641 }
642
643 cmptr = CMSG_FIRSTHDR(&msg);
644 if (cmptr == NULL) {
645 fprintf(stderr, "Error: Invalid control message header\n");
646 ret = -1;
647 goto end;
648 }
649
650 if (cmptr->cmsg_level != SOL_SOCKET ||
651 cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
652 fprintf(stderr, "Didn't received any credentials\n");
653 ret = -1;
654 goto end;
655 }
656
657 if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
658 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
659 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
660 ret = -1;
661 goto end;
662 }
663
664 memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
665 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
666 {
667 int peer_ret;
668
669 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
670 if (peer_ret != 0) {
671 return peer_ret;
672 }
673 }
674 #else
675 #error "Please implement credential support for your OS."
676 #endif /* __linux__ */
677
678 end:
679 return ret;
680 }
681
682 /*
683 * Set socket option to use credentials passing.
684 */
685 #ifdef __linux__
686 LTTNG_HIDDEN
687 int lttcomm_setsockopt_creds_unix_sock(int sock)
688 {
689 int ret, on = 1;
690
691 /* Set socket for credentials retrieval */
692 ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
693 if (ret < 0) {
694 PERROR("setsockopt creds unix sock");
695 }
696 return ret;
697 }
698 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
699 LTTNG_HIDDEN
700 int lttcomm_setsockopt_creds_unix_sock(int sock)
701 {
702 return 0;
703 }
704 #else
705 #error "Please implement credential support for your OS."
706 #endif /* __linux__ */
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