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