src/common/sessiond-comm/sessiond-comm.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 it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; only version 2 of the License.
   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 with
  15  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  16  * Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #define _GNU_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/defaults.h>
  31
  32 #include "sessiond-comm.h"
  33
  34 /*
  35  * Human readable error message.
  36  */
  37 static const char *lttcomm_readable_code[] = {
  38         [ LTTCOMM_ERR_INDEX(LTTCOMM_OK) ] = "Success",
  39         [ LTTCOMM_ERR_INDEX(LTTCOMM_ERR) ] = "Unknown error",
  40         [ LTTCOMM_ERR_INDEX(LTTCOMM_UND) ] = "Undefined command",
  41         [ LTTCOMM_ERR_INDEX(LTTCOMM_NOT_IMPLEMENTED) ] = "Not implemented",
  42         [ LTTCOMM_ERR_INDEX(LTTCOMM_UNKNOWN_DOMAIN) ] = "Unknown tracing domain",
  43         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_SESSION) ] = "No session found",
  44         [ LTTCOMM_ERR_INDEX(LTTCOMM_LIST_FAIL) ] = "Unable to list traceable apps",
  45         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_APPS) ] = "No traceable apps found",
  46         [ LTTCOMM_ERR_INDEX(LTTCOMM_SESS_NOT_FOUND) ] = "Session name not found",
  47         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_TRACE) ] = "No trace found",
  48         [ LTTCOMM_ERR_INDEX(LTTCOMM_FATAL) ] = "Fatal error of the session daemon",
  49         [ LTTCOMM_ERR_INDEX(LTTCOMM_CREATE_DIR_FAIL) ] = "Create directory failed",
  50         [ LTTCOMM_ERR_INDEX(LTTCOMM_START_FAIL) ] = "Start trace failed",
  51         [ LTTCOMM_ERR_INDEX(LTTCOMM_STOP_FAIL) ] = "Stop trace failed",
  52         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_TRACEABLE) ] = "App is not traceable",
  53         [ LTTCOMM_ERR_INDEX(LTTCOMM_SELECT_SESS) ] = "A session MUST be selected",
  54         [ LTTCOMM_ERR_INDEX(LTTCOMM_EXIST_SESS) ] = "Session name already exist",
  55         [ LTTCOMM_ERR_INDEX(LTTCOMM_CONNECT_FAIL) ] = "Unable to connect to Unix socket",
  56         [ LTTCOMM_ERR_INDEX(LTTCOMM_APP_NOT_FOUND) ] = "Application not found",
  57         [ LTTCOMM_ERR_INDEX(LTTCOMM_EPERM) ] = "Permission denied",
  58         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_NA) ] = "Kernel tracer not available",
  59         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_VERSION) ] = "Kernel tracer version is not compatible",
  60         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_EVENT_EXIST) ] = "Kernel event already exists",
  61         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_SESS_FAIL) ] = "Kernel create session failed",
  62         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_FAIL) ] = "Kernel create channel failed",
  63         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_NOT_FOUND) ] = "Kernel channel not found",
  64         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_DISABLE_FAIL) ] = "Disable kernel channel failed",
  65         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_ENABLE_FAIL) ] = "Enable kernel channel failed",
  66         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CONTEXT_FAIL) ] = "Add kernel context failed",
  67         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_ENABLE_FAIL) ] = "Enable kernel event failed",
  68         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DISABLE_FAIL) ] = "Disable kernel event failed",
  69         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_META_FAIL) ] = "Opening metadata failed",
  70         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_START_FAIL) ] = "Starting kernel trace failed",
  71         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_STOP_FAIL) ] = "Stoping kernel trace failed",
  72         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CONSUMER_FAIL) ] = "Kernel consumer start failed",
  73         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_STREAM_FAIL) ] = "Kernel create stream failed",
  74         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DIR_FAIL) ] = "Kernel trace directory creation failed",
  75         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DIR_EXIST) ] = "Kernel trace directory already exist",
  76         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_NO_SESSION) ] = "No kernel session found",
  77         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_LIST_FAIL) ] = "Listing kernel events failed",
  78         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CALIBRATE_FAIL) ] = "UST calibration failed",
  79         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_VERSION) ] = "UST tracer version is not compatible",
  80         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_SESS_FAIL) ] = "UST create session failed",
  81         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_FAIL) ] = "UST create channel failed",
  82         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_EXIST) ] = "UST channel already exist",
  83         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_NOT_FOUND) ] = "UST channel not found",
  84         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_DISABLE_FAIL) ] = "Disable UST channel failed",
  85         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_ENABLE_FAIL) ] = "Enable UST channel failed",
  86         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_FAIL) ] = "Add UST context failed",
  87         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_ENABLE_FAIL) ] = "Enable UST event failed",
  88         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DISABLE_FAIL) ] = "Disable UST event failed",
  89         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_META_FAIL) ] = "Opening metadata failed",
  90         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_START_FAIL) ] = "Starting UST trace failed",
  91         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STOP_FAIL) ] = "Stoping UST trace failed",
  92         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER64_FAIL) ] = "64-bit UST consumer start failed",
  93         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER32_FAIL) ] = "32-bit UST consumer start failed",
  94         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STREAM_FAIL) ] = "UST create stream failed",
  95         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_FAIL) ] = "UST trace directory creation failed",
  96         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_EXIST) ] = "UST trace directory already exist",
  97         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_NO_SESSION) ] = "No UST session found",
  98         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_LIST_FAIL) ] = "Listing UST events failed",
  99         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_EXIST) ] = "UST event already exist",
 100         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_NOT_FOUND)] = "UST event not found",
 101         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_EXIST)] = "UST context already exist",
 102         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_INVAL)] = "UST invalid context",
 103         [ LTTCOMM_ERR_INDEX(CONSUMERD_COMMAND_SOCK_READY) ] = "consumerd command socket ready",
 104         [ LTTCOMM_ERR_INDEX(CONSUMERD_SUCCESS_RECV_FD) ] = "consumerd success on receiving fds",
 105         [ LTTCOMM_ERR_INDEX(CONSUMERD_ERROR_RECV_FD) ] = "consumerd error on receiving fds",
 106         [ LTTCOMM_ERR_INDEX(CONSUMERD_ERROR_RECV_CMD) ] = "consumerd error on receiving command",
 107         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_ERROR) ] = "consumerd error in polling thread",
 108         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_NVAL) ] = "consumerd polling on closed fd",
 109         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_HUP) ] = "consumerd all fd hung up",
 110         [ LTTCOMM_ERR_INDEX(CONSUMERD_EXIT_SUCCESS) ] = "consumerd exiting normally",
 111         [ LTTCOMM_ERR_INDEX(CONSUMERD_EXIT_FAILURE) ] = "consumerd exiting on error",
 112         [ LTTCOMM_ERR_INDEX(CONSUMERD_OUTFD_ERROR) ] = "consumerd error opening the tracefile",
 113         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_EBADF) ] = "consumerd splice EBADF",
 114         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_EINVAL) ] = "consumerd splice EINVAL",
 115         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ENOMEM) ] = "consumerd splice ENOMEM",
 116         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ESPIPE) ] = "consumerd splice ESPIPE",
 117         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_EVENT) ] = "Event not found",
 118 };
 119
 120 /*
 121  * Return ptr to string representing a human readable error code from the
 122  * lttcomm_return_code enum.
 123  *
 124  * These code MUST be negative in other to treat that as an error value.
 125  */
 126 const char *lttcomm_get_readable_code(enum lttcomm_return_code code)
 127 {
 128         int tmp_code = -code;
 129
 130         if (tmp_code >= LTTCOMM_OK && tmp_code < LTTCOMM_NR) {
 131                 return lttcomm_readable_code[LTTCOMM_ERR_INDEX(tmp_code)];
 132         }
 133
 134         return "Unknown error code";
 135 }
 136
 137 /*
 138  * Connect to unix socket using the path name.
 139  */
 140 int lttcomm_connect_unix_sock(const char *pathname)
 141 {
 142         struct sockaddr_un sun;
 143         int fd;
 144         int ret;
 145
 146         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 147         if (fd < 0) {
 148                 perror("socket");
 149                 ret = fd;
 150                 goto error;
 151         }
 152
 153         memset(&sun, 0, sizeof(sun));
 154         sun.sun_family = AF_UNIX;
 155         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 156         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 157
 158         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
 159         if (ret < 0) {
 160                 /*
 161                  * Don't print message on connect error, because connect is used in
 162                  * normal execution to detect if sessiond is alive.
 163                  */
 164                 goto error_connect;
 165         }
 166
 167         return fd;
 168
 169 error_connect:
 170         close(fd);
 171 error:
 172         return ret;
 173 }
 174
 175 /*
 176  * Do an accept(2) on the sock and return the new file descriptor. The socket
 177  * MUST be bind(2) before.
 178  */
 179 int lttcomm_accept_unix_sock(int sock)
 180 {
 181         int new_fd;
 182         struct sockaddr_un sun;
 183         socklen_t len = 0;
 184
 185         /* Blocking call */
 186         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
 187         if (new_fd < 0) {
 188                 perror("accept");
 189         }
 190
 191         return new_fd;
 192 }
 193
 194 /*
 195  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 196  * and return the fd.
 197  */
 198 int lttcomm_create_unix_sock(const char *pathname)
 199 {
 200         struct sockaddr_un sun;
 201         int fd;
 202         int ret = -1;
 203
 204         /* Create server socket */
 205         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 206                 perror("socket");
 207                 goto error;
 208         }
 209
 210         memset(&sun, 0, sizeof(sun));
 211         sun.sun_family = AF_UNIX;
 212         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 213         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 214
 215         /* Unlink the old file if present */
 216         (void) unlink(pathname);
 217         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 218         if (ret < 0) {
 219                 perror("bind");
 220                 goto error;
 221         }
 222
 223         return fd;
 224
 225 error:
 226         return ret;
 227 }
 228
 229 /*
 230  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 231  */
 232 int lttcomm_listen_unix_sock(int sock)
 233 {
 234         int ret;
 235
 236         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 237         if (ret < 0) {
 238                 perror("listen");
 239         }
 240
 241         return ret;
 242 }
 243
 244 /*
 245  * Receive data of size len in put that data into the buf param. Using recvmsg
 246  * API.
 247  *
 248  * Return the size of received data.
 249  */
 250 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 251 {
 252         struct msghdr msg;
 253         struct iovec iov[1];
 254         ssize_t ret = -1;
 255
 256         memset(&msg, 0, sizeof(msg));
 257
 258         iov[0].iov_base = buf;
 259         iov[0].iov_len = len;
 260         msg.msg_iov = iov;
 261         msg.msg_iovlen = 1;
 262
 263         ret = recvmsg(sock, &msg, MSG_WAITALL);
 264         if (ret < 0) {
 265                 perror("recvmsg");
 266         }
 267
 268         return ret;
 269 }
 270
 271 /*
 272  * Send buf data of size len. Using sendmsg API.
 273  *
 274  * Return the size of sent data.
 275  */
 276 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 277 {
 278         struct msghdr msg;
 279         struct iovec iov[1];
 280         ssize_t ret = -1;
 281
 282         memset(&msg, 0, sizeof(msg));
 283
 284         iov[0].iov_base = buf;
 285         iov[0].iov_len = len;
 286         msg.msg_iov = iov;
 287         msg.msg_iovlen = 1;
 288
 289         ret = sendmsg(sock, &msg, 0);
 290         if (ret < 0) {
 291                 perror("sendmsg");
 292         }
 293
 294         return ret;
 295 }
 296
 297 /*
 298  * Shutdown cleanly a unix socket.
 299  */
 300 int lttcomm_close_unix_sock(int sock)
 301 {
 302         int ret;
 303
 304         /* Shutdown receptions and transmissions */
 305         ret = shutdown(sock, SHUT_RDWR);
 306         if (ret < 0) {
 307                 perror("shutdown");
 308         }
 309
 310         close(sock);
 311
 312         return ret;
 313 }
 314
 315 /*
 316  * Send a message accompanied by fd(s) over a unix socket.
 317  *
 318  * Returns the size of data sent, or negative error value.
 319  */
 320 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 321 {
 322         struct msghdr msg;
 323         struct cmsghdr *cmptr;
 324         struct iovec iov[1];
 325         ssize_t ret = -1;
 326         unsigned int sizeof_fds = nb_fd * sizeof(int);
 327         char tmp[CMSG_SPACE(sizeof_fds)];
 328         char dummy = 0;
 329
 330         memset(&msg, 0, sizeof(msg));
 331
 332         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 333                 return -EINVAL;
 334
 335         msg.msg_control = (caddr_t)tmp;
 336         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 337
 338         cmptr = CMSG_FIRSTHDR(&msg);
 339         cmptr->cmsg_level = SOL_SOCKET;
 340         cmptr->cmsg_type = SCM_RIGHTS;
 341         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 342         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 343         /* Sum of the length of all control messages in the buffer: */
 344         msg.msg_controllen = cmptr->cmsg_len;
 345
 346         iov[0].iov_base = &dummy;
 347         iov[0].iov_len = 1;
 348         msg.msg_iov = iov;
 349         msg.msg_iovlen = 1;
 350
 351         ret = sendmsg(sock, &msg, 0);
 352         if (ret < 0) {
 353                 perror("sendmsg");
 354         }
 355         return ret;
 356 }
 357
 358 /*
 359  * Recv a message accompanied by fd(s) from a unix socket.
 360  *
 361  * Returns the size of received data, or negative error value.
 362  *
 363  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 364  * actually received in nb_fd.
 365  */
 366 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 367 {
 368         struct iovec iov[1];
 369         ssize_t ret = 0;
 370         struct cmsghdr *cmsg;
 371         size_t sizeof_fds = nb_fd * sizeof(int);
 372         char recv_fd[CMSG_SPACE(sizeof_fds)];
 373         struct msghdr msg;
 374         char dummy;
 375
 376         memset(&msg, 0, sizeof(msg));
 377
 378         /* Prepare to receive the structures */
 379         iov[0].iov_base = &dummy;
 380         iov[0].iov_len = 1;
 381         msg.msg_iov = iov;
 382         msg.msg_iovlen = 1;
 383         msg.msg_control = recv_fd;
 384         msg.msg_controllen = sizeof(recv_fd);
 385
 386         ret = recvmsg(sock, &msg, 0);
 387         if (ret < 0) {
 388                 perror("recvmsg fds");
 389                 goto end;
 390         }
 391         if (ret != 1) {
 392                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 393                                 ret, 1);
 394                 goto end;
 395         }
 396         if (msg.msg_flags & MSG_CTRUNC) {
 397                 fprintf(stderr, "Error: Control message truncated.\n");
 398                 ret = -1;
 399                 goto end;
 400         }
 401         cmsg = CMSG_FIRSTHDR(&msg);
 402         if (!cmsg) {
 403                 fprintf(stderr, "Error: Invalid control message header\n");
 404                 ret = -1;
 405                 goto end;
 406         }
 407         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 408                 fprintf(stderr, "Didn't received any fd\n");
 409                 ret = -1;
 410                 goto end;
 411         }
 412         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 413                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 414                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 415                 ret = -1;
 416                 goto end;
 417         }
 418         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 419         ret = sizeof_fds;
 420 end:
 421         return ret;
 422 }
 423
 424 /*
 425  * Send a message with credentials over a unix socket.
 426  *
 427  * Returns the size of data sent, or negative error value.
 428  */
 429 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 430 {
 431         struct msghdr msg;
 432         struct iovec iov[1];
 433         ssize_t ret = -1;
 434 #ifdef __linux__
 435         struct cmsghdr *cmptr;
 436         size_t sizeof_cred = sizeof(lttng_sock_cred);
 437         char anc_buf[CMSG_SPACE(sizeof_cred)];
 438         lttng_sock_cred *creds;
 439 #endif /* __linux__ */
 440
 441         memset(&msg, 0, sizeof(msg));
 442
 443         iov[0].iov_base = buf;
 444         iov[0].iov_len = len;
 445         msg.msg_iov = iov;
 446         msg.msg_iovlen = 1;
 447
 448 #ifdef __linux__
 449         msg.msg_control = (caddr_t) anc_buf;
 450         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 451
 452         cmptr = CMSG_FIRSTHDR(&msg);
 453         cmptr->cmsg_level = SOL_SOCKET;
 454         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 455         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 456
 457         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 458
 459         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 460         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 461         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 462 #endif /* __linux__ */
 463
 464         ret = sendmsg(sock, &msg, 0);
 465         if (ret < 0) {
 466                 perror("sendmsg");
 467         }
 468
 469         return ret;
 470 }
 471
 472 /*
 473  * Recv a message accompanied with credentials from a unix socket.
 474  *
 475  * Returns the size of received data, or negative error value.
 476  */
 477 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 478                 lttng_sock_cred *creds)
 479 {
 480         struct msghdr msg;
 481         struct iovec iov[1];
 482         ssize_t ret;
 483 #ifdef __linux__
 484         struct cmsghdr *cmptr;
 485         size_t sizeof_cred = sizeof(lttng_sock_cred);
 486         char anc_buf[CMSG_SPACE(sizeof_cred)];
 487 #endif  /* __linux__ */
 488
 489         memset(&msg, 0, sizeof(msg));
 490
 491         /* Not allowed */
 492         if (creds == NULL) {
 493                 ret = -1;
 494                 goto end;
 495         }
 496
 497         /* Prepare to receive the structures */
 498         iov[0].iov_base = buf;
 499         iov[0].iov_len = len;
 500         msg.msg_iov = iov;
 501         msg.msg_iovlen = 1;
 502
 503 #ifdef __linux__
 504         msg.msg_control = anc_buf;
 505         msg.msg_controllen = sizeof(anc_buf);
 506 #endif /* __linux__ */
 507
 508         ret = recvmsg(sock, &msg, 0);
 509         if (ret < 0) {
 510                 perror("recvmsg fds");
 511                 goto end;
 512         }
 513
 514 #ifdef __linux__
 515         if (msg.msg_flags & MSG_CTRUNC) {
 516                 fprintf(stderr, "Error: Control message truncated.\n");
 517                 ret = -1;
 518                 goto end;
 519         }
 520
 521         cmptr = CMSG_FIRSTHDR(&msg);
 522         if (cmptr == NULL) {
 523                 fprintf(stderr, "Error: Invalid control message header\n");
 524                 ret = -1;
 525                 goto end;
 526         }
 527
 528         if (cmptr->cmsg_level != SOL_SOCKET ||
 529                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 530                 fprintf(stderr, "Didn't received any credentials\n");
 531                 ret = -1;
 532                 goto end;
 533         }
 534
 535         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 536                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 537                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 538                 ret = -1;
 539                 goto end;
 540         }
 541
 542         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 543 #elif defined(__FreeBSD__)
 544         {
 545                 int peer_ret;
 546
 547                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 548                 if (peer_ret != 0) {
 549                         return peer_ret;
 550                 }
 551 #else
 552 #error "Please implement credential support for your OS."
 553 #endif  /* __linux__ */
 554
 555 end:
 556         return ret;
 557 }
 558
 559 /*
 560  * Set socket option to use credentials passing.
 561  */
 562 #ifdef __linux__
 563 int lttcomm_setsockopt_creds_unix_sock(int sock)
 564 {
 565         int ret, on = 1;
 566
 567         /* Set socket for credentials retrieval */
 568         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 569         if (ret < 0) {
 570                 perror("setsockopt creds unix sock");
 571         }
 572         return ret;
 573 }
 574 #elif defined(__FreeBSD__)
 575 int lttcomm_setsockopt_creds_unix_sock(int sock)
 576 {
 577         return 0;
 578 }
 579 #else
 580 #error "Please implement credential support for your OS."
 581 #endif /* __linux__ */