src/common/unix.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/stat.h>
  26 #include <sys/types.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29
  30 #include <common/common.h>
  31 #include <common/sessiond-comm/sessiond-comm.h>
  32
  33 #include "unix.h"
  34
  35 /*
  36  * Connect to unix socket using the path name.
  37  */
  38 LTTNG_HIDDEN
  39 int lttcomm_connect_unix_sock(const char *pathname)
  40 {
  41         struct sockaddr_un s_un;
  42         int fd, ret, closeret;
  43
  44         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
  45                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
  46                                 pathname, strlen(pathname) + 1,
  47                                 sizeof(s_un.sun_path));
  48                 ret = -ENAMETOOLONG;
  49                 goto error;
  50         }
  51
  52         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  53         if (fd < 0) {
  54                 PERROR("socket");
  55                 ret = fd;
  56                 goto error;
  57         }
  58
  59         memset(&s_un, 0, sizeof(s_un));
  60         s_un.sun_family = AF_UNIX;
  61         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
  62         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
  63
  64         ret = connect(fd, (struct sockaddr *) &s_un, sizeof(s_un));
  65         if (ret < 0) {
  66                 /*
  67                  * Don't print message on connect error, because connect is used in
  68                  * normal execution to detect if sessiond is alive.
  69                  */
  70                 goto error_connect;
  71         }
  72
  73         return fd;
  74
  75 error_connect:
  76         closeret = close(fd);
  77         if (closeret) {
  78                 PERROR("close");
  79         }
  80 error:
  81         return ret;
  82 }
  83
  84 /*
  85  * Do an accept(2) on the sock and return the new file descriptor. The socket
  86  * MUST be bind(2) before.
  87  */
  88 LTTNG_HIDDEN
  89 int lttcomm_accept_unix_sock(int sock)
  90 {
  91         int new_fd;
  92         struct sockaddr_un s_un;
  93         socklen_t len = sizeof(s_un);
  94
  95         /* Blocking call */
  96         new_fd = accept(sock, (struct sockaddr *) &s_un, &len);
  97         if (new_fd < 0) {
  98                 PERROR("accept");
  99         }
 100
 101         return new_fd;
 102 }
 103
 104 LTTNG_HIDDEN
 105 int lttcomm_create_anon_unix_socketpair(int *fds)
 106 {
 107         if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
 108                 PERROR("socketpair");
 109                 return -1;
 110         }
 111         return 0;
 112 }
 113
 114 /*
 115  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 116  * and return the fd.
 117  */
 118 LTTNG_HIDDEN
 119 int lttcomm_create_unix_sock(const char *pathname)
 120 {
 121         struct sockaddr_un s_un;
 122         int fd = -1;
 123         int ret = -1;
 124
 125         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
 126                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
 127                                 pathname, strlen(pathname) + 1,
 128                                 sizeof(s_un.sun_path));
 129                 ret = -ENAMETOOLONG;
 130                 goto error;
 131         }
 132
 133         /* Create server socket */
 134         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 135                 PERROR("socket");
 136                 goto error;
 137         }
 138
 139         memset(&s_un, 0, sizeof(s_un));
 140         s_un.sun_family = AF_UNIX;
 141         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
 142         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
 143
 144         /* Unlink the old file if present */
 145         (void) unlink(pathname);
 146         ret = bind(fd, (struct sockaddr *) &s_un, sizeof(s_un));
 147         if (ret < 0) {
 148                 PERROR("bind");
 149                 goto error;
 150         }
 151
 152         return fd;
 153
 154 error:
 155         if (fd >= 0) {
 156                 if (close(fd) < 0) {
 157                         PERROR("close create unix sock");
 158                 }
 159         }
 160         return ret;
 161 }
 162
 163 /*
 164  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 165  */
 166 LTTNG_HIDDEN
 167 int lttcomm_listen_unix_sock(int sock)
 168 {
 169         int ret;
 170
 171         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 172         if (ret < 0) {
 173                 PERROR("listen");
 174         }
 175
 176         return ret;
 177 }
 178
 179 /*
 180  * Receive data of size len in put that data into the buf param. Using recvmsg
 181  * API.
 182  *
 183  * Return the size of received data.
 184  */
 185 LTTNG_HIDDEN
 186 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 187 {
 188         struct msghdr msg;
 189         struct iovec iov[1];
 190         ssize_t ret = -1;
 191         size_t len_last;
 192
 193         memset(&msg, 0, sizeof(msg));
 194
 195         iov[0].iov_base = buf;
 196         iov[0].iov_len = len;
 197         msg.msg_iov = iov;
 198         msg.msg_iovlen = 1;
 199
 200         do {
 201                 len_last = iov[0].iov_len;
 202                 ret = lttng_recvmsg_nosigpipe(sock, &msg);
 203                 if (ret > 0) {
 204                         iov[0].iov_base += ret;
 205                         iov[0].iov_len -= ret;
 206                         assert(ret <= len_last);
 207                 }
 208         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 209         if (ret < 0) {
 210                 PERROR("recvmsg");
 211         } else if (ret > 0) {
 212                 ret = len;
 213         }
 214         /* Else ret = 0 meaning an orderly shutdown. */
 215
 216         return ret;
 217 }
 218
 219 /*
 220  * Receive data of size len in put that data into the buf param. Using recvmsg
 221  * API. Only use with sockets set in non-blocking mode.
 222  *
 223  * Return the size of received data.
 224  */
 225 LTTNG_HIDDEN
 226 ssize_t lttcomm_recv_unix_sock_non_block(int sock, void *buf, size_t len)
 227 {
 228         struct msghdr msg;
 229         struct iovec iov[1];
 230         ssize_t ret;
 231
 232         memset(&msg, 0, sizeof(msg));
 233
 234         iov[0].iov_base = buf;
 235         iov[0].iov_len = len;
 236         msg.msg_iov = iov;
 237         msg.msg_iovlen = 1;
 238
 239 retry:
 240         ret = lttng_recvmsg_nosigpipe(sock, &msg);
 241         if (ret < 0) {
 242                 if (errno == EINTR) {
 243                         goto retry;
 244                 } else {
 245                         /*
 246                          * Only warn about EPIPE when quiet mode is
 247                          * deactivated.
 248                          * We consider EPIPE as expected.
 249                          */
 250                         if (errno != EPIPE || !lttng_opt_quiet) {
 251                                 PERROR("recvmsg");
 252                         }
 253                         goto end;
 254                 }
 255         }
 256         ret = len;
 257 end:
 258         return ret;
 259 }
 260
 261 /*
 262  * Send buf data of size len. Using sendmsg API.
 263  *
 264  * Return the size of sent data.
 265  */
 266 LTTNG_HIDDEN
 267 ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len)
 268 {
 269         struct msghdr msg;
 270         struct iovec iov[1];
 271         ssize_t ret;
 272
 273         memset(&msg, 0, sizeof(msg));
 274
 275         iov[0].iov_base = (void *) buf;
 276         iov[0].iov_len = len;
 277         msg.msg_iov = iov;
 278         msg.msg_iovlen = 1;
 279
 280         while (iov[0].iov_len) {
 281                 ret = sendmsg(sock, &msg, 0);
 282                 if (ret < 0) {
 283                         if (errno == EINTR) {
 284                                 continue;
 285                         } else {
 286                                 /*
 287                                  * Only warn about EPIPE when quiet mode is
 288                                  * deactivated.
 289                                  * We consider EPIPE as expected.
 290                                  */
 291                                 if (errno != EPIPE || !lttng_opt_quiet) {
 292                                         PERROR("sendmsg");
 293                                 }
 294                                 goto end;
 295                         }
 296                 }
 297                 iov[0].iov_len -= ret;
 298                 iov[0].iov_base += ret;
 299         }
 300         ret = len;
 301 end:
 302         return ret;
 303 }
 304
 305 /*
 306  * Send buf data of size len. Using sendmsg API.
 307  * Only use with non-blocking sockets. The difference with the blocking version
 308  * of the function is that this one does not retry to send on partial sends,
 309  * except if the interruption was caused by a signal (EINTR).
 310  *
 311  * Return the size of sent data.
 312  */
 313 LTTNG_HIDDEN
 314 ssize_t lttcomm_send_unix_sock_non_block(int sock, const void *buf, size_t len)
 315 {
 316         struct msghdr msg;
 317         struct iovec iov[1];
 318         ssize_t ret;
 319
 320         memset(&msg, 0, sizeof(msg));
 321
 322         iov[0].iov_base = (void *) buf;
 323         iov[0].iov_len = len;
 324         msg.msg_iov = iov;
 325         msg.msg_iovlen = 1;
 326
 327 retry:
 328         ret = sendmsg(sock, &msg, 0);
 329         if (ret < 0) {
 330                 if (errno == EINTR) {
 331                         goto retry;
 332                 } else {
 333                         /*
 334                          * Only warn about EPIPE when quiet mode is
 335                          * deactivated.
 336                          * We consider EPIPE as expected.
 337                          */
 338                         if (errno != EPIPE || !lttng_opt_quiet) {
 339                                 PERROR("sendmsg");
 340                         }
 341                         goto end;
 342                 }
 343         }
 344         ret = len;
 345 end:
 346         return ret;
 347 }
 348
 349 /*
 350  * Shutdown cleanly a unix socket.
 351  */
 352 LTTNG_HIDDEN
 353 int lttcomm_close_unix_sock(int sock)
 354 {
 355         int ret, closeret;
 356
 357         /* Shutdown receptions and transmissions */
 358         ret = shutdown(sock, SHUT_RDWR);
 359         if (ret < 0) {
 360                 PERROR("shutdown");
 361         }
 362
 363         closeret = close(sock);
 364         if (closeret) {
 365                 PERROR("close");
 366         }
 367
 368         return ret;
 369 }
 370
 371 /*
 372  * Send a message accompanied by fd(s) over a unix socket.
 373  *
 374  * Returns the size of data sent, or negative error value.
 375  */
 376 LTTNG_HIDDEN
 377 ssize_t lttcomm_send_fds_unix_sock(int sock, const int *fds, size_t nb_fd)
 378 {
 379         struct msghdr msg;
 380         struct cmsghdr *cmptr;
 381         struct iovec iov[1];
 382         ssize_t ret = -1;
 383         unsigned int sizeof_fds = nb_fd * sizeof(int);
 384         char tmp[CMSG_SPACE(sizeof_fds)];
 385         char dummy = 0;
 386
 387         memset(&msg, 0, sizeof(msg));
 388         memset(tmp, 0, sizeof(tmp));
 389
 390         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 391                 return -EINVAL;
 392
 393         msg.msg_control = (caddr_t)tmp;
 394         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 395
 396         cmptr = CMSG_FIRSTHDR(&msg);
 397         if (!cmptr) {
 398                 return -1;
 399         }
 400
 401         cmptr->cmsg_level = SOL_SOCKET;
 402         cmptr->cmsg_type = SCM_RIGHTS;
 403         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 404         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 405         /* Sum of the length of all control messages in the buffer: */
 406         msg.msg_controllen = cmptr->cmsg_len;
 407
 408         iov[0].iov_base = &dummy;
 409         iov[0].iov_len = 1;
 410         msg.msg_iov = iov;
 411         msg.msg_iovlen = 1;
 412
 413         do {
 414                 ret = sendmsg(sock, &msg, 0);
 415         } while (ret < 0 && errno == EINTR);
 416         if (ret < 0) {
 417                 /*
 418                  * Only warn about EPIPE when quiet mode is deactivated.
 419                  * We consider EPIPE as expected.
 420                  */
 421                 if (errno != EPIPE || !lttng_opt_quiet) {
 422                         PERROR("sendmsg");
 423                 }
 424         }
 425         return ret;
 426 }
 427
 428 /*
 429  * Recv a message accompanied by fd(s) from a unix socket.
 430  *
 431  * Returns the size of received data, or negative error value.
 432  *
 433  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 434  * actually received in nb_fd.
 435  */
 436 LTTNG_HIDDEN
 437 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 438 {
 439         struct iovec iov[1];
 440         ssize_t ret = 0;
 441         struct cmsghdr *cmsg;
 442         size_t sizeof_fds = nb_fd * sizeof(int);
 443
 444 #ifdef __linux__
 445 /* Account for the struct ucred cmsg in the buffer size */
 446 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds) + CMSG_SPACE(sizeof(struct ucred))
 447 #else
 448 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds)
 449 #endif /* __linux__ */
 450
 451         char recv_buf[LTTNG_SOCK_RECV_FDS_BUF_SIZE];
 452         struct msghdr msg;
 453         char dummy;
 454
 455         memset(&msg, 0, sizeof(msg));
 456
 457         /* Prepare to receive the structures */
 458         iov[0].iov_base = &dummy;
 459         iov[0].iov_len = 1;
 460         msg.msg_iov = iov;
 461         msg.msg_iovlen = 1;
 462
 463         cmsg = (struct cmsghdr *) recv_buf;
 464         cmsg->cmsg_len = CMSG_LEN(sizeof_fds);
 465         cmsg->cmsg_level = SOL_SOCKET;
 466         cmsg->cmsg_type = SCM_RIGHTS;
 467
 468         msg.msg_control = cmsg;
 469         msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
 470         msg.msg_flags = 0;
 471
 472         do {
 473                 ret = recvmsg(sock, &msg, 0);
 474         } while (ret < 0 && errno == EINTR);
 475         if (ret < 0) {
 476                 PERROR("recvmsg fds");
 477                 goto end;
 478         }
 479
 480         if (ret != 1) {
 481                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 482                                 ret, 1);
 483                 goto end;
 484         }
 485
 486         if (msg.msg_flags & MSG_CTRUNC) {
 487                 fprintf(stderr, "Error: Control message truncated.\n");
 488                 ret = -1;
 489                 goto end;
 490         }
 491
 492         /*
 493          * If the socket was configured with SO_PASSCRED, the kernel will add a
 494          * control message (cmsg) to the ancillary data of the unix socket. We
 495          * need to expect a cmsg of the SCM_CREDENTIALS as the first control
 496          * message.
 497          */
 498         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 499                 if (cmsg->cmsg_level != SOL_SOCKET) {
 500                         fprintf(stderr, "Error: The socket needs to be of type SOL_SOCKET\n");
 501                         ret = -1;
 502                         goto end;
 503                 }
 504                 if (cmsg->cmsg_type == SCM_RIGHTS) {
 505                         /*
 506                          * We found the controle message for file descriptors,
 507                          * now copy the fds to the fds ptr and return success.
 508                          */
 509                         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 510                                 fprintf(stderr, "Error: Received %zu bytes of"
 511                                         "ancillary data for FDs, expected %zu\n",
 512                                         (size_t) cmsg->cmsg_len,
 513                                         (size_t) CMSG_LEN(sizeof_fds));
 514                                 ret = -1;
 515                                 goto end;
 516                         }
 517                         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 518                         ret = sizeof_fds;
 519                         goto end;
 520                 }
 521 #ifdef __linux__
 522                 if (cmsg->cmsg_type == SCM_CREDENTIALS) {
 523                         /*
 524                          * Expect credentials to be sent when expecting fds even
 525                          * if no credential were include in the send(). The
 526                          * kernel adds them...
 527                          */
 528                         ret = -1;
 529                 }
 530 #endif /* __linux__ */
 531         }
 532 end:
 533         return ret;
 534 }
 535
 536 /*
 537  * Send a message with credentials over a unix socket.
 538  *
 539  * Returns the size of data sent, or negative error value.
 540  */
 541 LTTNG_HIDDEN
 542 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 543 {
 544         struct msghdr msg;
 545         struct iovec iov[1];
 546         ssize_t ret = -1;
 547 #ifdef __linux__
 548         struct cmsghdr *cmptr;
 549         size_t sizeof_cred = sizeof(lttng_sock_cred);
 550         char anc_buf[CMSG_SPACE(sizeof_cred)];
 551         lttng_sock_cred *creds;
 552
 553         memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
 554 #endif /* __linux__ */
 555
 556         memset(&msg, 0, sizeof(msg));
 557
 558         iov[0].iov_base = buf;
 559         iov[0].iov_len = len;
 560         msg.msg_iov = iov;
 561         msg.msg_iovlen = 1;
 562
 563 #ifdef __linux__
 564         msg.msg_control = (caddr_t) anc_buf;
 565         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 566
 567         cmptr = CMSG_FIRSTHDR(&msg);
 568         if (!cmptr) {
 569                 return -1;
 570         }
 571         cmptr->cmsg_level = SOL_SOCKET;
 572         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 573         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 574
 575         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 576
 577         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 578         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 579         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 580 #endif /* __linux__ */
 581
 582         do {
 583                 ret = sendmsg(sock, &msg, 0);
 584         } while (ret < 0 && errno == EINTR);
 585         if (ret < 0) {
 586                 /*
 587                  * Only warn about EPIPE when quiet mode is deactivated.
 588                  * We consider EPIPE as expected.
 589                  */
 590                 if (errno != EPIPE || !lttng_opt_quiet) {
 591                         PERROR("sendmsg");
 592                 }
 593         }
 594         return ret;
 595 }
 596
 597 /*
 598  * Recv a message accompanied with credentials from a unix socket.
 599  *
 600  * Returns the size of received data, or negative error value.
 601  */
 602 LTTNG_HIDDEN
 603 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 604                 lttng_sock_cred *creds)
 605 {
 606         struct msghdr msg;
 607         struct iovec iov[1];
 608         ssize_t ret;
 609         size_t len_last;
 610 #ifdef __linux__
 611         struct cmsghdr *cmptr;
 612         size_t sizeof_cred = sizeof(lttng_sock_cred);
 613         char anc_buf[CMSG_SPACE(sizeof_cred)];
 614 #endif  /* __linux__ */
 615
 616         memset(&msg, 0, sizeof(msg));
 617
 618         /* Not allowed */
 619         if (creds == NULL) {
 620                 ret = -1;
 621                 goto end;
 622         }
 623
 624         /* Prepare to receive the structures */
 625         iov[0].iov_base = buf;
 626         iov[0].iov_len = len;
 627         msg.msg_iov = iov;
 628         msg.msg_iovlen = 1;
 629
 630 #ifdef __linux__
 631         msg.msg_control = anc_buf;
 632         msg.msg_controllen = sizeof(anc_buf);
 633 #endif /* __linux__ */
 634
 635         do {
 636                 len_last = iov[0].iov_len;
 637                 ret = recvmsg(sock, &msg, 0);
 638                 if (ret > 0) {
 639                         iov[0].iov_base += ret;
 640                         iov[0].iov_len -= ret;
 641                         assert(ret <= len_last);
 642                 }
 643         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 644         if (ret < 0) {
 645                 PERROR("recvmsg fds");
 646                 goto end;
 647         } else if (ret > 0) {
 648                 ret = len;
 649         }
 650         /* Else ret = 0 meaning an orderly shutdown. */
 651
 652 #ifdef __linux__
 653         if (msg.msg_flags & MSG_CTRUNC) {
 654                 fprintf(stderr, "Error: Control message truncated.\n");
 655                 ret = -1;
 656                 goto end;
 657         }
 658
 659         cmptr = CMSG_FIRSTHDR(&msg);
 660         if (cmptr == NULL) {
 661                 fprintf(stderr, "Error: Invalid control message header\n");
 662                 ret = -1;
 663                 goto end;
 664         }
 665
 666         if (cmptr->cmsg_level != SOL_SOCKET ||
 667                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 668                 fprintf(stderr, "Didn't received any credentials\n");
 669                 ret = -1;
 670                 goto end;
 671         }
 672
 673         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 674                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 675                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 676                 ret = -1;
 677                 goto end;
 678         }
 679
 680         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 681 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 682         {
 683                 int peer_ret;
 684
 685                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 686                 if (peer_ret != 0) {
 687                         return peer_ret;
 688                 }
 689         }
 690 #else
 691 #error "Please implement credential support for your OS."
 692 #endif  /* __linux__ */
 693
 694 end:
 695         return ret;
 696 }
 697
 698 /*
 699  * Set socket option to use credentials passing.
 700  */
 701 #ifdef __linux__
 702 LTTNG_HIDDEN
 703 int lttcomm_setsockopt_creds_unix_sock(int sock)
 704 {
 705         int ret, on = 1;
 706
 707         /* Set socket for credentials retrieval */
 708         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 709         if (ret < 0) {
 710                 PERROR("setsockopt creds unix sock");
 711         }
 712         return ret;
 713 }
 714 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 715 LTTNG_HIDDEN
 716 int lttcomm_setsockopt_creds_unix_sock(int sock)
 717 {
 718         return 0;
 719 }
 720 #else
 721 #error "Please implement credential support for your OS."
 722 #endif /* __linux__ */