src/common/sessiond-comm/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 _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/common.h>
  31
  32 #include "unix.h"
  33
  34 /*
  35  * Connect to unix socket using the path name.
  36  */
  37 LTTNG_HIDDEN
  38 int lttcomm_connect_unix_sock(const char *pathname)
  39 {
  40         struct sockaddr_un sun;
  41         int fd, ret, closeret;
  42
  43         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  44         if (fd < 0) {
  45                 PERROR("socket");
  46                 ret = fd;
  47                 goto error;
  48         }
  49
  50         memset(&sun, 0, sizeof(sun));
  51         sun.sun_family = AF_UNIX;
  52         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
  53         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
  54
  55         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
  56         if (ret < 0) {
  57                 /*
  58                  * Don't print message on connect error, because connect is used in
  59                  * normal execution to detect if sessiond is alive.
  60                  */
  61                 goto error_connect;
  62         }
  63
  64         return fd;
  65
  66 error_connect:
  67         closeret = close(fd);
  68         if (closeret) {
  69                 PERROR("close");
  70         }
  71 error:
  72         return ret;
  73 }
  74
  75 /*
  76  * Do an accept(2) on the sock and return the new file descriptor. The socket
  77  * MUST be bind(2) before.
  78  */
  79 LTTNG_HIDDEN
  80 int lttcomm_accept_unix_sock(int sock)
  81 {
  82         int new_fd;
  83         struct sockaddr_un sun;
  84         socklen_t len = 0;
  85
  86         /* Blocking call */
  87         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
  88         if (new_fd < 0) {
  89                 PERROR("accept");
  90         }
  91
  92         return new_fd;
  93 }
  94
  95 /*
  96  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
  97  * and return the fd.
  98  */
  99 LTTNG_HIDDEN
 100 int lttcomm_create_unix_sock(const char *pathname)
 101 {
 102         struct sockaddr_un sun;
 103         int fd;
 104         int ret = -1;
 105
 106         /* Create server socket */
 107         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 108                 PERROR("socket");
 109                 goto error;
 110         }
 111
 112         memset(&sun, 0, sizeof(sun));
 113         sun.sun_family = AF_UNIX;
 114         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 115         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 116
 117         /* Unlink the old file if present */
 118         (void) unlink(pathname);
 119         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 120         if (ret < 0) {
 121                 PERROR("bind");
 122                 goto error;
 123         }
 124
 125         return fd;
 126
 127 error:
 128         if (fd >= 0) {
 129                 if (close(fd) < 0) {
 130                         PERROR("close create unix sock");
 131                 }
 132         }
 133         return ret;
 134 }
 135
 136 /*
 137  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 138  */
 139 LTTNG_HIDDEN
 140 int lttcomm_listen_unix_sock(int sock)
 141 {
 142         int ret;
 143
 144         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 145         if (ret < 0) {
 146                 PERROR("listen");
 147         }
 148
 149         return ret;
 150 }
 151
 152 /*
 153  * Receive data of size len in put that data into the buf param. Using recvmsg
 154  * API.
 155  *
 156  * Return the size of received data.
 157  */
 158 LTTNG_HIDDEN
 159 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 160 {
 161         struct msghdr msg;
 162         struct iovec iov[1];
 163         ssize_t ret = -1;
 164         size_t len_last;
 165
 166         memset(&msg, 0, sizeof(msg));
 167
 168         iov[0].iov_base = buf;
 169         iov[0].iov_len = len;
 170         msg.msg_iov = iov;
 171         msg.msg_iovlen = 1;
 172
 173         do {
 174                 len_last = iov[0].iov_len;
 175                 ret = recvmsg(sock, &msg, 0);
 176                 if (ret > 0) {
 177                         iov[0].iov_base += ret;
 178                         iov[0].iov_len -= ret;
 179                         assert(ret <= len_last);
 180                 }
 181         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 182         if (ret < 0) {
 183                 PERROR("recvmsg");
 184         } else if (ret > 0) {
 185                 ret = len;
 186         }
 187         /* Else ret = 0 meaning an orderly shutdown. */
 188
 189         return ret;
 190 }
 191
 192 /*
 193  * Send buf data of size len. Using sendmsg API.
 194  *
 195  * Return the size of sent data.
 196  */
 197 LTTNG_HIDDEN
 198 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 199 {
 200         struct msghdr msg;
 201         struct iovec iov[1];
 202         ssize_t ret = -1;
 203
 204         memset(&msg, 0, sizeof(msg));
 205
 206         iov[0].iov_base = buf;
 207         iov[0].iov_len = len;
 208         msg.msg_iov = iov;
 209         msg.msg_iovlen = 1;
 210
 211         ret = sendmsg(sock, &msg, 0);
 212         if (ret < 0) {
 213                 /*
 214                  * Only warn about EPIPE when quiet mode is deactivated.
 215                  * We consider EPIPE as expected.
 216                  */
 217                 if (errno != EPIPE || !lttng_opt_quiet) {
 218                         PERROR("sendmsg");
 219                 }
 220         }
 221
 222         return ret;
 223 }
 224
 225 /*
 226  * Shutdown cleanly a unix socket.
 227  */
 228 LTTNG_HIDDEN
 229 int lttcomm_close_unix_sock(int sock)
 230 {
 231         int ret, closeret;
 232
 233         /* Shutdown receptions and transmissions */
 234         ret = shutdown(sock, SHUT_RDWR);
 235         if (ret < 0) {
 236                 PERROR("shutdown");
 237         }
 238
 239         closeret = close(sock);
 240         if (closeret) {
 241                 PERROR("close");
 242         }
 243
 244         return ret;
 245 }
 246
 247 /*
 248  * Send a message accompanied by fd(s) over a unix socket.
 249  *
 250  * Returns the size of data sent, or negative error value.
 251  */
 252 LTTNG_HIDDEN
 253 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 254 {
 255         struct msghdr msg;
 256         struct cmsghdr *cmptr;
 257         struct iovec iov[1];
 258         ssize_t ret = -1;
 259         unsigned int sizeof_fds = nb_fd * sizeof(int);
 260         char tmp[CMSG_SPACE(sizeof_fds)];
 261         char dummy = 0;
 262
 263         memset(&msg, 0, sizeof(msg));
 264         memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
 265
 266         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 267                 return -EINVAL;
 268
 269         msg.msg_control = (caddr_t)tmp;
 270         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 271
 272         cmptr = CMSG_FIRSTHDR(&msg);
 273         cmptr->cmsg_level = SOL_SOCKET;
 274         cmptr->cmsg_type = SCM_RIGHTS;
 275         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 276         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 277         /* Sum of the length of all control messages in the buffer: */
 278         msg.msg_controllen = cmptr->cmsg_len;
 279
 280         iov[0].iov_base = &dummy;
 281         iov[0].iov_len = 1;
 282         msg.msg_iov = iov;
 283         msg.msg_iovlen = 1;
 284
 285         do {
 286                 ret = sendmsg(sock, &msg, 0);
 287         } while (ret < 0 && errno == EINTR);
 288         if (ret < 0) {
 289                 /*
 290                  * Only warn about EPIPE when quiet mode is deactivated.
 291                  * We consider EPIPE as expected.
 292                  */
 293                 if (errno != EPIPE || !lttng_opt_quiet) {
 294                         PERROR("sendmsg");
 295                 }
 296         }
 297         return ret;
 298 }
 299
 300 /*
 301  * Recv a message accompanied by fd(s) from a unix socket.
 302  *
 303  * Returns the size of received data, or negative error value.
 304  *
 305  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 306  * actually received in nb_fd.
 307  */
 308 LTTNG_HIDDEN
 309 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 310 {
 311         struct iovec iov[1];
 312         ssize_t ret = 0;
 313         struct cmsghdr *cmsg;
 314         size_t sizeof_fds = nb_fd * sizeof(int);
 315         char recv_fd[CMSG_SPACE(sizeof_fds)];
 316         struct msghdr msg;
 317         char dummy;
 318
 319         memset(&msg, 0, sizeof(msg));
 320
 321         /* Prepare to receive the structures */
 322         iov[0].iov_base = &dummy;
 323         iov[0].iov_len = 1;
 324         msg.msg_iov = iov;
 325         msg.msg_iovlen = 1;
 326         msg.msg_control = recv_fd;
 327         msg.msg_controllen = sizeof(recv_fd);
 328
 329         do {
 330                 ret = recvmsg(sock, &msg, 0);
 331         } while (ret < 0 && errno == EINTR);
 332         if (ret < 0) {
 333                 PERROR("recvmsg fds");
 334                 goto end;
 335         }
 336         if (ret != 1) {
 337                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 338                                 ret, 1);
 339                 goto end;
 340         }
 341         if (msg.msg_flags & MSG_CTRUNC) {
 342                 fprintf(stderr, "Error: Control message truncated.\n");
 343                 ret = -1;
 344                 goto end;
 345         }
 346         cmsg = CMSG_FIRSTHDR(&msg);
 347         if (!cmsg) {
 348                 fprintf(stderr, "Error: Invalid control message header\n");
 349                 ret = -1;
 350                 goto end;
 351         }
 352         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 353                 fprintf(stderr, "Didn't received any fd\n");
 354                 ret = -1;
 355                 goto end;
 356         }
 357         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 358                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 359                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 360                 ret = -1;
 361                 goto end;
 362         }
 363         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 364         ret = sizeof_fds;
 365 end:
 366         return ret;
 367 }
 368
 369 /*
 370  * Send a message with credentials over a unix socket.
 371  *
 372  * Returns the size of data sent, or negative error value.
 373  */
 374 LTTNG_HIDDEN
 375 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 376 {
 377         struct msghdr msg;
 378         struct iovec iov[1];
 379         ssize_t ret = -1;
 380 #ifdef __linux__
 381         struct cmsghdr *cmptr;
 382         size_t sizeof_cred = sizeof(lttng_sock_cred);
 383         char anc_buf[CMSG_SPACE(sizeof_cred)];
 384         lttng_sock_cred *creds;
 385 #endif /* __linux__ */
 386
 387         memset(&msg, 0, sizeof(msg));
 388         memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
 389
 390         iov[0].iov_base = buf;
 391         iov[0].iov_len = len;
 392         msg.msg_iov = iov;
 393         msg.msg_iovlen = 1;
 394
 395 #ifdef __linux__
 396         msg.msg_control = (caddr_t) anc_buf;
 397         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 398
 399         cmptr = CMSG_FIRSTHDR(&msg);
 400         cmptr->cmsg_level = SOL_SOCKET;
 401         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 402         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 403
 404         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 405
 406         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 407         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 408         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 409 #endif /* __linux__ */
 410
 411         do {
 412                 ret = sendmsg(sock, &msg, 0);
 413         } while (ret < 0 && errno == EINTR);
 414         if (ret < 0) {
 415                 /*
 416                  * Only warn about EPIPE when quiet mode is deactivated.
 417                  * We consider EPIPE as expected.
 418                  */
 419                 if (errno != EPIPE || !lttng_opt_quiet) {
 420                         PERROR("sendmsg");
 421                 }
 422         }
 423         return ret;
 424 }
 425
 426 /*
 427  * Recv a message accompanied with credentials from a unix socket.
 428  *
 429  * Returns the size of received data, or negative error value.
 430  */
 431 LTTNG_HIDDEN
 432 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 433                 lttng_sock_cred *creds)
 434 {
 435         struct msghdr msg;
 436         struct iovec iov[1];
 437         ssize_t ret;
 438 #ifdef __linux__
 439         struct cmsghdr *cmptr;
 440         size_t sizeof_cred = sizeof(lttng_sock_cred);
 441         char anc_buf[CMSG_SPACE(sizeof_cred)];
 442 #endif  /* __linux__ */
 443
 444         memset(&msg, 0, sizeof(msg));
 445
 446         /* Not allowed */
 447         if (creds == NULL) {
 448                 ret = -1;
 449                 goto end;
 450         }
 451
 452         /* Prepare to receive the structures */
 453         iov[0].iov_base = buf;
 454         iov[0].iov_len = len;
 455         msg.msg_iov = iov;
 456         msg.msg_iovlen = 1;
 457
 458 #ifdef __linux__
 459         msg.msg_control = anc_buf;
 460         msg.msg_controllen = sizeof(anc_buf);
 461 #endif /* __linux__ */
 462
 463         do {
 464                 ret = recvmsg(sock, &msg, 0);
 465         } while (ret < 0 && errno == EINTR);
 466         if (ret < 0) {
 467                 PERROR("recvmsg fds");
 468                 goto end;
 469         }
 470
 471 #ifdef __linux__
 472         if (msg.msg_flags & MSG_CTRUNC) {
 473                 fprintf(stderr, "Error: Control message truncated.\n");
 474                 ret = -1;
 475                 goto end;
 476         }
 477
 478         cmptr = CMSG_FIRSTHDR(&msg);
 479         if (cmptr == NULL) {
 480                 fprintf(stderr, "Error: Invalid control message header\n");
 481                 ret = -1;
 482                 goto end;
 483         }
 484
 485         if (cmptr->cmsg_level != SOL_SOCKET ||
 486                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 487                 fprintf(stderr, "Didn't received any credentials\n");
 488                 ret = -1;
 489                 goto end;
 490         }
 491
 492         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 493                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 494                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 495                 ret = -1;
 496                 goto end;
 497         }
 498
 499         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 500 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 501         {
 502                 int peer_ret;
 503
 504                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 505                 if (peer_ret != 0) {
 506                         return peer_ret;
 507                 }
 508         }
 509 #else
 510 #error "Please implement credential support for your OS."
 511 #endif  /* __linux__ */
 512
 513 end:
 514         return ret;
 515 }
 516
 517 /*
 518  * Set socket option to use credentials passing.
 519  */
 520 #ifdef __linux__
 521 LTTNG_HIDDEN
 522 int lttcomm_setsockopt_creds_unix_sock(int sock)
 523 {
 524         int ret, on = 1;
 525
 526         /* Set socket for credentials retrieval */
 527         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 528         if (ret < 0) {
 529                 PERROR("setsockopt creds unix sock");
 530         }
 531         return ret;
 532 }
 533 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 534 LTTNG_HIDDEN
 535 int lttcomm_setsockopt_creds_unix_sock(int sock)
 536 {
 537         return 0;
 538 }
 539 #else
 540 #error "Please implement credential support for your OS."
 541 #endif /* __linux__ */