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_CALIBRATE_FAIL) ] = "UST calibration failed",
  80         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_VERSION) ] = "UST tracer version is not compatible",
  81         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_SESS_FAIL) ] = "UST create session failed",
  82         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_FAIL) ] = "UST create channel failed",
  83         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_EXIST) ] = "UST channel already exist",
  84         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_NOT_FOUND) ] = "UST channel not found",
  85         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_DISABLE_FAIL) ] = "Disable UST channel failed",
  86         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CHAN_ENABLE_FAIL) ] = "Enable UST channel failed",
  87         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_FAIL) ] = "Add UST context failed",
  88         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_ENABLE_FAIL) ] = "Enable UST event failed",
  89         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DISABLE_FAIL) ] = "Disable UST event failed",
  90         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_META_FAIL) ] = "Opening metadata failed",
  91         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_START_FAIL) ] = "Starting UST trace failed",
  92         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STOP_FAIL) ] = "Stoping UST trace failed",
  93         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER64_FAIL) ] = "64-bit UST consumer start failed",
  94         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONSUMER32_FAIL) ] = "32-bit UST consumer start failed",
  95         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_STREAM_FAIL) ] = "UST create stream failed",
  96         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_FAIL) ] = "UST trace directory creation failed",
  97         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_DIR_EXIST) ] = "UST trace directory already exist",
  98         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_NO_SESSION) ] = "No UST session found",
  99         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_LIST_FAIL) ] = "Listing UST events failed",
 100         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_EXIST) ] = "UST event already exist",
 101         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_EVENT_NOT_FOUND)] = "UST event not found",
 102         [ LTTCOMM_ERR_INDEX(LTTCOMM_UST_CONTEXT_EXIST)] = "UST context already exist",
 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 = { 0 };
 253         struct iovec iov[1];
 254         ssize_t ret = -1;
 255
 256         iov[0].iov_base = buf;
 257         iov[0].iov_len = len;
 258         msg.msg_iov = iov;
 259         msg.msg_iovlen = 1;
 260
 261         ret = recvmsg(sock, &msg, 0);
 262         if (ret < 0) {
 263                 perror("recvmsg");
 264         }
 265
 266         return ret;
 267 }
 268
 269 /*
 270  * Send buf data of size len. Using sendmsg API.
 271  *
 272  * Return the size of sent data.
 273  */
 274 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 275 {
 276         struct msghdr msg = { 0 };
 277         struct iovec iov[1];
 278         ssize_t ret = -1;
 279
 280         iov[0].iov_base = buf;
 281         iov[0].iov_len = len;
 282         msg.msg_iov = iov;
 283         msg.msg_iovlen = 1;
 284
 285         ret = sendmsg(sock, &msg, 0);
 286         if (ret < 0) {
 287                 perror("sendmsg");
 288         }
 289
 290         return ret;
 291 }
 292
 293 /*
 294  * Shutdown cleanly a unix socket.
 295  */
 296 int lttcomm_close_unix_sock(int sock)
 297 {
 298         int ret;
 299
 300         /* Shutdown receptions and transmissions */
 301         ret = shutdown(sock, SHUT_RDWR);
 302         if (ret < 0) {
 303                 perror("shutdown");
 304         }
 305
 306         return ret;
 307 }
 308
 309 /*
 310  * Send a message accompanied by fd(s) over a unix socket.
 311  *
 312  * Returns the size of data sent, or negative error value.
 313  */
 314 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 315 {
 316         struct msghdr msg = { 0 };
 317         struct cmsghdr *cmptr;
 318         struct iovec iov[1];
 319         ssize_t ret = -1;
 320         unsigned int sizeof_fds = nb_fd * sizeof(int);
 321         char tmp[CMSG_SPACE(sizeof_fds)];
 322         char dummy = 0;
 323
 324         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 325                 return -EINVAL;
 326
 327         msg.msg_control = (caddr_t)tmp;
 328         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 329
 330         cmptr = CMSG_FIRSTHDR(&msg);
 331         cmptr->cmsg_level = SOL_SOCKET;
 332         cmptr->cmsg_type = SCM_RIGHTS;
 333         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 334         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 335         /* Sum of the length of all control messages in the buffer: */
 336         msg.msg_controllen = cmptr->cmsg_len;
 337
 338         iov[0].iov_base = &dummy;
 339         iov[0].iov_len = 1;
 340         msg.msg_iov = iov;
 341         msg.msg_iovlen = 1;
 342
 343         ret = sendmsg(sock, &msg, 0);
 344         if (ret < 0) {
 345                 perror("sendmsg");
 346         }
 347         return ret;
 348 }
 349
 350 /*
 351  * Recv a message accompanied by fd(s) from a unix socket.
 352  *
 353  * Returns the size of received data, or negative error value.
 354  *
 355  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 356  * actually received in nb_fd.
 357  */
 358 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 359 {
 360         struct iovec iov[1];
 361         ssize_t ret = 0;
 362         struct cmsghdr *cmsg;
 363         size_t sizeof_fds = nb_fd * sizeof(int);
 364         char recv_fd[CMSG_SPACE(sizeof_fds)];
 365         struct msghdr msg = { 0 };
 366         char dummy;
 367
 368         /* Prepare to receive the structures */
 369         iov[0].iov_base = &dummy;
 370         iov[0].iov_len = 1;
 371         msg.msg_iov = iov;
 372         msg.msg_iovlen = 1;
 373         msg.msg_control = recv_fd;
 374         msg.msg_controllen = sizeof(recv_fd);
 375
 376         ret = recvmsg(sock, &msg, 0);
 377         if (ret < 0) {
 378                 perror("recvmsg fds");
 379                 goto end;
 380         }
 381         if (ret != 1) {
 382                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 383                                 ret, 1);
 384                 goto end;
 385         }
 386         if (msg.msg_flags & MSG_CTRUNC) {
 387                 fprintf(stderr, "Error: Control message truncated.\n");
 388                 ret = -1;
 389                 goto end;
 390         }
 391         cmsg = CMSG_FIRSTHDR(&msg);
 392         if (!cmsg) {
 393                 fprintf(stderr, "Error: Invalid control message header\n");
 394                 ret = -1;
 395                 goto end;
 396         }
 397         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 398                 fprintf(stderr, "Didn't received any fd\n");
 399                 ret = -1;
 400                 goto end;
 401         }
 402         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 403                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 404                                 cmsg->cmsg_len, CMSG_LEN(sizeof_fds));
 405                 ret = -1;
 406                 goto end;
 407         }
 408         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 409         ret = sizeof_fds;
 410 end:
 411         return ret;
 412 }
 413
 414 /*
 415  * Send a message with credentials over a unix socket.
 416  *
 417  * Returns the size of data sent, or negative error value.
 418  */
 419 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 420 {
 421         struct msghdr msg = { 0 };
 422         struct cmsghdr *cmptr;
 423         struct iovec iov[1];
 424         ssize_t ret = -1;
 425         struct ucred *creds;
 426         size_t sizeof_cred = sizeof(struct ucred);
 427         char anc_buf[CMSG_SPACE(sizeof_cred)];
 428
 429         iov[0].iov_base = buf;
 430         iov[0].iov_len = len;
 431         msg.msg_iov = iov;
 432         msg.msg_iovlen = 1;
 433
 434         msg.msg_control = (caddr_t) anc_buf;
 435         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 436
 437         cmptr = CMSG_FIRSTHDR(&msg);
 438         cmptr->cmsg_level = SOL_SOCKET;
 439         cmptr->cmsg_type = SCM_CREDENTIALS;
 440         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 441
 442         creds = (struct ucred *) CMSG_DATA(cmptr);
 443
 444         creds->uid = geteuid();
 445         creds->gid = getegid();
 446         creds->pid = getpid();
 447
 448         ret = sendmsg(sock, &msg, 0);
 449         if (ret < 0) {
 450                 perror("sendmsg");
 451         }
 452
 453         return ret;
 454 }
 455
 456 /*
 457  * Recv a message accompanied with credentials from a unix socket.
 458  *
 459  * Returns the size of received data, or negative error value.
 460  */
 461 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 462                 struct ucred *creds)
 463 {
 464         struct msghdr msg = { 0 };
 465         struct cmsghdr *cmptr;
 466         struct iovec iov[1];
 467         ssize_t ret;
 468         size_t sizeof_cred = sizeof(struct ucred);
 469         char anc_buf[CMSG_SPACE(sizeof_cred)];
 470
 471         /* Not allowed */
 472         if (creds == NULL) {
 473                 ret = -1;
 474                 goto end;
 475         }
 476
 477         /* Prepare to receive the structures */
 478         iov[0].iov_base = buf;
 479         iov[0].iov_len = len;
 480         msg.msg_iov = iov;
 481         msg.msg_iovlen = 1;
 482
 483         msg.msg_control = anc_buf;
 484         msg.msg_controllen = sizeof(anc_buf);
 485
 486         ret = recvmsg(sock, &msg, 0);
 487         if (ret < 0) {
 488                 perror("recvmsg fds");
 489                 goto end;
 490         }
 491
 492         if (msg.msg_flags & MSG_CTRUNC) {
 493                 fprintf(stderr, "Error: Control message truncated.\n");
 494                 ret = -1;
 495                 goto end;
 496         }
 497
 498         cmptr = CMSG_FIRSTHDR(&msg);
 499         if (cmptr == NULL) {
 500                 fprintf(stderr, "Error: Invalid control message header\n");
 501                 ret = -1;
 502                 goto end;
 503         }
 504
 505         if (cmptr->cmsg_level != SOL_SOCKET ||
 506                         cmptr->cmsg_type != SCM_CREDENTIALS) {
 507                 fprintf(stderr, "Didn't received any credentials\n");
 508                 ret = -1;
 509                 goto end;
 510         }
 511
 512         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 513                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 514                                 cmptr->cmsg_len, CMSG_LEN(sizeof_cred));
 515                 ret = -1;
 516                 goto end;
 517         }
 518
 519         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 520
 521 end:
 522         return ret;
 523 }
 524
 525 /*
 526  * Set socket option to use credentials passing.
 527  */
 528 int lttcomm_setsockopt_creds_unix_sock(int sock)
 529 {
 530         int ret, on = 1;
 531
 532         /* Set socket for credentials retrieval */
 533         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 534         if (ret < 0) {
 535                 perror("setsockopt creds unix sock");
 536         }
 537
 538         return ret;
 539 }