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 <sys/un.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30
  31 #include <common/defaults.h>
  32
  33 #include "sessiond-comm.h"
  34
  35 /*
  36  * Human readable error message.
  37  */
  38 static const char *lttcomm_readable_code[] = {
  39         [ LTTCOMM_ERR_INDEX(LTTCOMM_OK) ] = "Success",
  40         [ LTTCOMM_ERR_INDEX(LTTCOMM_ERR) ] = "Unknown error",
  41         [ LTTCOMM_ERR_INDEX(LTTCOMM_UND) ] = "Undefined command",
  42         [ LTTCOMM_ERR_INDEX(LTTCOMM_NOT_IMPLEMENTED) ] = "Not implemented",
  43         [ LTTCOMM_ERR_INDEX(LTTCOMM_UNKNOWN_DOMAIN) ] = "Unknown tracing domain",
  44         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_SESSION) ] = "No session found",
  45         [ LTTCOMM_ERR_INDEX(LTTCOMM_LIST_FAIL) ] = "Unable to list traceable apps",
  46         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_APPS) ] = "No traceable apps found",
  47         [ LTTCOMM_ERR_INDEX(LTTCOMM_SESS_NOT_FOUND) ] = "Session name not found",
  48         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_TRACE) ] = "No trace found",
  49         [ LTTCOMM_ERR_INDEX(LTTCOMM_FATAL) ] = "Fatal error of the session daemon",
  50         [ LTTCOMM_ERR_INDEX(LTTCOMM_CREATE_FAIL) ] = "Create trace failed",
  51         [ LTTCOMM_ERR_INDEX(LTTCOMM_START_FAIL) ] = "Start trace failed",
  52         [ LTTCOMM_ERR_INDEX(LTTCOMM_STOP_FAIL) ] = "Stop trace failed",
  53         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_TRACEABLE) ] = "App is not traceable",
  54         [ LTTCOMM_ERR_INDEX(LTTCOMM_SELECT_SESS) ] = "A session MUST be selected",
  55         [ LTTCOMM_ERR_INDEX(LTTCOMM_EXIST_SESS) ] = "Session name already exist",
  56         [ LTTCOMM_ERR_INDEX(LTTCOMM_CONNECT_FAIL) ] = "Unable to connect to Unix socket",
  57         [ LTTCOMM_ERR_INDEX(LTTCOMM_APP_NOT_FOUND) ] = "Application not found",
  58         [ LTTCOMM_ERR_INDEX(LTTCOMM_EPERM) ] = "Permission denied",
  59         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_NA) ] = "Kernel tracer not available",
  60         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_VERSION) ] = "Kernel tracer version is not compatible",
  61         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_EVENT_EXIST) ] = "Kernel event already exists",
  62         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_SESS_FAIL) ] = "Kernel create session failed",
  63         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_FAIL) ] = "Kernel create channel failed",
  64         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_NOT_FOUND) ] = "Kernel channel not found",
  65         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_DISABLE_FAIL) ] = "Disable kernel channel failed",
  66         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CHAN_ENABLE_FAIL) ] = "Enable kernel channel failed",
  67         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CONTEXT_FAIL) ] = "Add kernel context failed",
  68         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_ENABLE_FAIL) ] = "Enable kernel event failed",
  69         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DISABLE_FAIL) ] = "Disable kernel event failed",
  70         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_META_FAIL) ] = "Opening metadata failed",
  71         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_START_FAIL) ] = "Starting kernel trace failed",
  72         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_STOP_FAIL) ] = "Stoping kernel trace failed",
  73         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_CONSUMER_FAIL) ] = "Kernel consumer start failed",
  74         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_STREAM_FAIL) ] = "Kernel create stream failed",
  75         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DIR_FAIL) ] = "Kernel trace directory creation failed",
  76         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_DIR_EXIST) ] = "Kernel trace directory already exist",
  77         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_NO_SESSION) ] = "No kernel session found",
  78         [ LTTCOMM_ERR_INDEX(LTTCOMM_KERN_LIST_FAIL) ] = "Listing kernel events failed",
  79         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_SESS_FAIL) ] = "UST create session failed",
  80         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_FAIL) ] = "UST create channel failed",
  81         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_EXIST) ] = "UST channel already exist",
  82         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_NOT_FOUND) ] = "UST channel not found",
  83         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_DISABLE_FAIL) ] = "Disable UST channel failed",
  84         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_ENABLE_FAIL) ] = "Enable UST channel failed",
  85         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_FAIL) ] = "Add UST context failed",
  86         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_ENABLE_FAIL) ] = "Enable UST event failed",
  87         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DISABLE_FAIL) ] = "Disable UST event failed",
  88         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_META_FAIL) ] = "Opening metadata failed",
  89         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_START_FAIL) ] = "Starting UST trace failed",
  90         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STOP_FAIL) ] = "Stoping UST trace failed",
  91         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER64_FAIL) ] = "64-bit UST consumer start failed",
  92         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER32_FAIL) ] = "32-bit UST consumer start failed",
  93         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STREAM_FAIL) ] = "UST create stream failed",
  94         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_FAIL) ] = "UST trace directory creation failed",
  95         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_EXIST) ] = "UST trace directory already exist",
  96         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_NO_SESSION) ] = "No UST session found",
  97         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_LIST_FAIL) ] = "Listing UST events failed",
  98         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_EXIST) ] = "UST event already exist",
  99         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_NOT_FOUND)] = "UST event not found",
 100         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_EXIST)] = "UST context already exist",
 101         [ LTTCOMM_ERR_INDEX(CONSUMERD_COMMAND_SOCK_READY) ] = "consumerd command socket ready",
 102         [ LTTCOMM_ERR_INDEX(CONSUMERD_SUCCESS_RECV_FD) ] = "consumerd success on receiving fds",
 103         [ LTTCOMM_ERR_INDEX(CONSUMERD_ERROR_RECV_FD) ] = "consumerd error on receiving fds",
 104         [ LTTCOMM_ERR_INDEX(CONSUMERD_ERROR_RECV_CMD) ] = "consumerd error on receiving command",
 105         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_ERROR) ] = "consumerd error in polling thread",
 106         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_NVAL) ] = "consumerd polling on closed fd",
 107         [ LTTCOMM_ERR_INDEX(CONSUMERD_POLL_HUP) ] = "consumerd all fd hung up",
 108         [ LTTCOMM_ERR_INDEX(CONSUMERD_EXIT_SUCCESS) ] = "consumerd exiting normally",
 109         [ LTTCOMM_ERR_INDEX(CONSUMERD_EXIT_FAILURE) ] = "consumerd exiting on error",
 110         [ LTTCOMM_ERR_INDEX(CONSUMERD_OUTFD_ERROR) ] = "consumerd error opening the tracefile",
 111         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_EBADF) ] = "consumerd splice EBADF",
 112         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_EINVAL) ] = "consumerd splice EINVAL",
 113         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ENOMEM) ] = "consumerd splice ENOMEM",
 114         [ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ESPIPE) ] = "consumerd splice ESPIPE",
 115         [ LTTCOMM_ERR_INDEX(LTTCOMM_NO_EVENT) ] = "Event not found",
 116 };
 117
 118 /*
 119  * Return ptr to string representing a human readable error code from the
 120  * lttcomm_return_code enum.
 121  *
 122  * These code MUST be negative in other to treat that as an error value.
 123  */
 124 const char *lttcomm_get_readable_code(enum lttcomm_return_code code)
 125 {
 126         int tmp_code = -code;
 127
 128         if (tmp_code >= LTTCOMM_OK && tmp_code < LTTCOMM_NR) {
 129                 return lttcomm_readable_code[LTTCOMM_ERR_INDEX(tmp_code)];
 130         }
 131
 132         return "Unknown error code";
 133 }
 134
 135 /*
 136  * Connect to unix socket using the path name.
 137  */
 138 int lttcomm_connect_unix_sock(const char *pathname)
 139 {
 140         struct sockaddr_un sun;
 141         int fd;
 142         int ret;
 143
 144         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 145         if (fd < 0) {
 146                 perror("socket");
 147                 ret = fd;
 148                 goto error;
 149         }
 150
 151         memset(&sun, 0, sizeof(sun));
 152         sun.sun_family = AF_UNIX;
 153         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 154         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 155
 156         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
 157         if (ret < 0) {
 158                 /*
 159                  * Don't print message on connect error, because connect is used in
 160                  * normal execution to detect if sessiond is alive.
 161                  */
 162                 goto error_connect;
 163         }
 164
 165         return fd;
 166
 167 error_connect:
 168         close(fd);
 169 error:
 170         return ret;
 171 }
 172
 173 /*
 174  * Do an accept(2) on the sock and return the new file descriptor. The socket
 175  * MUST be bind(2) before.
 176  */
 177 int lttcomm_accept_unix_sock(int sock)
 178 {
 179         int new_fd;
 180         struct sockaddr_un sun;
 181         socklen_t len = 0;
 182
 183         /* Blocking call */
 184         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
 185         if (new_fd < 0) {
 186                 perror("accept");
 187         }
 188
 189         return new_fd;
 190 }
 191
 192 /*
 193  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 194  * and return the fd.
 195  */
 196 int lttcomm_create_unix_sock(const char *pathname)
 197 {
 198         struct sockaddr_un sun;
 199         int fd;
 200         int ret = -1;
 201
 202         /* Create server socket */
 203         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 204                 perror("socket");
 205                 goto error;
 206         }
 207
 208         memset(&sun, 0, sizeof(sun));
 209         sun.sun_family = AF_UNIX;
 210         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 211         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 212
 213         /* Unlink the old file if present */
 214         (void) unlink(pathname);
 215         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 216         if (ret < 0) {
 217                 perror("bind");
 218                 goto error;
 219         }
 220
 221         return fd;
 222
 223 error:
 224         return ret;
 225 }
 226
 227 /*
 228  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 229  */
 230 int lttcomm_listen_unix_sock(int sock)
 231 {
 232         int ret;
 233
 234         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 235         if (ret < 0) {
 236                 perror("listen");
 237         }
 238
 239         return ret;
 240 }
 241
 242 /*
 243  * Receive data of size len in put that data into the buf param. Using recvmsg
 244  * API.
 245  *
 246  * Return the size of received data.
 247  */
 248 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 249 {
 250         struct msghdr msg = { 0 };
 251         struct iovec iov[1];
 252         ssize_t ret = -1;
 253
 254         iov[0].iov_base = buf;
 255         iov[0].iov_len = len;
 256         msg.msg_iov = iov;
 257         msg.msg_iovlen = 1;
 258
 259         ret = recvmsg(sock, &msg, 0);
 260         if (ret < 0) {
 261                 perror("recvmsg");
 262         }
 263
 264         return ret;
 265 }
 266
 267 /*
 268  * Send buf data of size len. Using sendmsg API.
 269  *
 270  * Return the size of sent data.
 271  */
 272 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 273 {
 274         struct msghdr msg = { 0 };
 275         struct iovec iov[1];
 276         ssize_t ret = -1;
 277
 278         iov[0].iov_base = buf;
 279         iov[0].iov_len = len;
 280         msg.msg_iov = iov;
 281         msg.msg_iovlen = 1;
 282
 283         ret = sendmsg(sock, &msg, 0);
 284         if (ret < 0) {
 285                 perror("sendmsg");
 286         }
 287
 288         return ret;
 289 }
 290
 291 /*
 292  * Shutdown cleanly a unix socket.
 293  */
 294 int lttcomm_close_unix_sock(int sock)
 295 {
 296         int ret;
 297
 298         /* Shutdown receptions and transmissions */
 299         ret = shutdown(sock, SHUT_RDWR);
 300         if (ret < 0) {
 301                 perror("shutdown");
 302         }
 303
 304         return ret;
 305 }
 306
 307 /*
 308  * Send a message accompanied by fd(s) over a unix socket.
 309  *
 310  * Returns the size of data sent, or negative error value.
 311  */
 312 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 313 {
 314         struct msghdr msg = { 0 };
 315         struct cmsghdr *cmptr;
 316         struct iovec iov[1];
 317         ssize_t ret = -1;
 318         unsigned int sizeof_fds = nb_fd * sizeof(int);
 319         char tmp[CMSG_SPACE(sizeof_fds)];
 320         char dummy = 0;
 321
 322         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 323                 return -EINVAL;
 324
 325         msg.msg_control = (caddr_t)tmp;
 326         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 327
 328         cmptr = CMSG_FIRSTHDR(&msg);
 329         cmptr->cmsg_level = SOL_SOCKET;
 330         cmptr->cmsg_type = SCM_RIGHTS;
 331         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 332         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 333         /* Sum of the length of all control messages in the buffer: */
 334         msg.msg_controllen = cmptr->cmsg_len;
 335
 336         iov[0].iov_base = &dummy;
 337         iov[0].iov_len = 1;
 338         msg.msg_iov = iov;
 339         msg.msg_iovlen = 1;
 340
 341         ret = sendmsg(sock, &msg, 0);
 342         if (ret < 0) {
 343                 perror("sendmsg");
 344         }
 345         return ret;
 346 }
 347
 348 /*
 349  * Recv a message accompanied by fd(s) from a unix socket.
 350  *
 351  * Returns the size of received data, or negative error value.
 352  *
 353  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 354  * actually received in nb_fd.
 355  */
 356 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 357 {
 358         struct iovec iov[1];
 359         ssize_t ret = 0;
 360         struct cmsghdr *cmsg;
 361         size_t sizeof_fds = nb_fd * sizeof(int);
 362         char recv_fd[CMSG_SPACE(sizeof_fds)];
 363         struct msghdr msg = { 0 };
 364         char dummy;
 365
 366         /* Prepare to receive the structures */
 367         iov[0].iov_base = &dummy;
 368         iov[0].iov_len = 1;
 369         msg.msg_iov = iov;
 370         msg.msg_iovlen = 1;
 371         msg.msg_control = recv_fd;
 372         msg.msg_controllen = sizeof(recv_fd);
 373
 374         ret = recvmsg(sock, &msg, 0);
 375         if (ret < 0) {
 376                 perror("recvmsg fds");
 377                 goto end;
 378         }
 379         if (ret != 1) {
 380                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 381                                 ret, 1);
 382                 goto end;
 383         }
 384         if (msg.msg_flags & MSG_CTRUNC) {
 385                 fprintf(stderr, "Error: Control message truncated.\n");
 386                 ret = -1;
 387                 goto end;
 388         }
 389         cmsg = CMSG_FIRSTHDR(&msg);
 390         if (!cmsg) {
 391                 fprintf(stderr, "Error: Invalid control message header\n");
 392                 ret = -1;
 393                 goto end;
 394         }
 395         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 396                 fprintf(stderr, "Didn't received any fd\n");
 397                 ret = -1;
 398                 goto end;
 399         }
 400         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 401                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 402                                 cmsg->cmsg_len, CMSG_LEN(sizeof_fds));
 403                 ret = -1;
 404                 goto end;
 405         }
 406         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 407         ret = sizeof_fds;
 408 end:
 409         return ret;
 410 }
 411
 412 /*
 413  * Send a message with credentials over a unix socket.
 414  *
 415  * Returns the size of data sent, or negative error value.
 416  */
 417 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 418 {
 419         struct msghdr msg = { 0 };
 420         struct cmsghdr *cmptr;
 421         struct iovec iov[1];
 422         ssize_t ret = -1;
 423         struct ucred *creds;
 424         size_t sizeof_cred = sizeof(struct ucred);
 425         char anc_buf[CMSG_SPACE(sizeof_cred)];
 426
 427         iov[0].iov_base = buf;
 428         iov[0].iov_len = len;
 429         msg.msg_iov = iov;
 430         msg.msg_iovlen = 1;
 431
 432         msg.msg_control = (caddr_t) anc_buf;
 433         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 434
 435         cmptr = CMSG_FIRSTHDR(&msg);
 436         cmptr->cmsg_level = SOL_SOCKET;
 437         cmptr->cmsg_type = SCM_CREDENTIALS;
 438         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 439
 440         creds = (struct ucred *) CMSG_DATA(cmptr);
 441
 442         creds->uid = geteuid();
 443         creds->gid = getegid();
 444         creds->pid = getpid();
 445
 446         ret = sendmsg(sock, &msg, 0);
 447         if (ret < 0) {
 448                 perror("sendmsg");
 449         }
 450
 451         return ret;
 452 }
 453
 454 /*
 455  * Recv a message accompanied with credentials from a unix socket.
 456  *
 457  * Returns the size of received data, or negative error value.
 458  */
 459 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 460                 struct ucred *creds)
 461 {
 462         struct msghdr msg = { 0 };
 463         struct cmsghdr *cmptr;
 464         struct iovec iov[1];
 465         ssize_t ret;
 466         size_t sizeof_cred = sizeof(struct ucred);
 467         char anc_buf[CMSG_SPACE(sizeof_cred)];
 468
 469         /* Not allowed */
 470         if (creds == NULL) {
 471                 ret = -1;
 472                 goto end;
 473         }
 474
 475         /* Prepare to receive the structures */
 476         iov[0].iov_base = buf;
 477         iov[0].iov_len = len;
 478         msg.msg_iov = iov;
 479         msg.msg_iovlen = 1;
 480
 481         msg.msg_control = anc_buf;
 482         msg.msg_controllen = sizeof(anc_buf);
 483
 484         ret = recvmsg(sock, &msg, 0);
 485         if (ret < 0) {
 486                 perror("recvmsg fds");
 487                 goto end;
 488         }
 489
 490         if (msg.msg_flags & MSG_CTRUNC) {
 491                 fprintf(stderr, "Error: Control message truncated.\n");
 492                 ret = -1;
 493                 goto end;
 494         }
 495
 496         cmptr = CMSG_FIRSTHDR(&msg);
 497         if (cmptr == NULL) {
 498                 fprintf(stderr, "Error: Invalid control message header\n");
 499                 ret = -1;
 500                 goto end;
 501         }
 502
 503         if (cmptr->cmsg_level != SOL_SOCKET ||
 504                         cmptr->cmsg_type != SCM_CREDENTIALS) {
 505                 fprintf(stderr, "Didn't received any credentials\n");
 506                 ret = -1;
 507                 goto end;
 508         }
 509
 510         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 511                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 512                                 cmptr->cmsg_len, CMSG_LEN(sizeof_cred));
 513                 ret = -1;
 514                 goto end;
 515         }
 516
 517         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 518
 519 end:
 520         return ret;
 521 }
 522
 523 /*
 524  * Set socket option to use credentials passing.
 525  */
 526 int lttcomm_setsockopt_creds_unix_sock(int sock)
 527 {
 528         int ret, on = 1;
 529
 530         /* Set socket for credentials retrieval */
 531         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 532         if (ret < 0) {
 533                 perror("setsockopt creds unix sock");
 534         }
 535
 536         return ret;
 537 }