src/common/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 _LGPL_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 #include <common/sessiond-comm/sessiond-comm.h>
  32
  33 #include "unix.h"
  34
  35 /*
  36  * Connect to unix socket using the path name.
  37  */
  38 LTTNG_HIDDEN
  39 int lttcomm_connect_unix_sock(const char *pathname)
  40 {
  41         struct sockaddr_un s_un;
  42         int fd, ret, closeret;
  43
  44         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
  45                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
  46                                 pathname, strlen(pathname) + 1,
  47                                 sizeof(s_un.sun_path));
  48                 ret = -ENAMETOOLONG;
  49                 goto error;
  50         }
  51
  52         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  53         if (fd < 0) {
  54                 PERROR("socket");
  55                 ret = fd;
  56                 goto error;
  57         }
  58
  59         memset(&s_un, 0, sizeof(s_un));
  60         s_un.sun_family = AF_UNIX;
  61         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
  62         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
  63
  64         ret = connect(fd, (struct sockaddr *) &s_un, sizeof(s_un));
  65         if (ret < 0) {
  66                 /*
  67                  * Don't print message on connect error, because connect is used in
  68                  * normal execution to detect if sessiond is alive.
  69                  */
  70                 goto error_connect;
  71         }
  72
  73         return fd;
  74
  75 error_connect:
  76         closeret = close(fd);
  77         if (closeret) {
  78                 PERROR("close");
  79         }
  80 error:
  81         return ret;
  82 }
  83
  84 /*
  85  * Do an accept(2) on the sock and return the new file descriptor. The socket
  86  * MUST be bind(2) before.
  87  */
  88 LTTNG_HIDDEN
  89 int lttcomm_accept_unix_sock(int sock)
  90 {
  91         int new_fd;
  92         struct sockaddr_un s_un;
  93         socklen_t len = sizeof(s_un);
  94
  95         /* Blocking call */
  96         new_fd = accept(sock, (struct sockaddr *) &s_un, &len);
  97         if (new_fd < 0) {
  98                 PERROR("accept");
  99         }
 100
 101         return new_fd;
 102 }
 103
 104 LTTNG_HIDDEN
 105 int lttcomm_create_anon_unix_socketpair(int *fds)
 106 {
 107         if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
 108                 PERROR("socketpair");
 109                 return -1;
 110         }
 111         return 0;
 112 }
 113
 114 /*
 115  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 116  * and return the fd.
 117  */
 118 LTTNG_HIDDEN
 119 int lttcomm_create_unix_sock(const char *pathname)
 120 {
 121         struct sockaddr_un s_un;
 122         int fd = -1;
 123         int ret = -1;
 124
 125         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
 126                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
 127                                 pathname, strlen(pathname) + 1,
 128                                 sizeof(s_un.sun_path));
 129                 ret = -ENAMETOOLONG;
 130                 goto error;
 131         }
 132
 133         /* Create server socket */
 134         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 135                 PERROR("socket");
 136                 goto error;
 137         }
 138
 139         memset(&s_un, 0, sizeof(s_un));
 140         s_un.sun_family = AF_UNIX;
 141         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
 142         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
 143
 144         /* Unlink the old file if present */
 145         (void) unlink(pathname);
 146         ret = bind(fd, (struct sockaddr *) &s_un, sizeof(s_un));
 147         if (ret < 0) {
 148                 PERROR("bind");
 149                 goto error;
 150         }
 151
 152         return fd;
 153
 154 error:
 155         if (fd >= 0) {
 156                 if (close(fd) < 0) {
 157                         PERROR("close create unix sock");
 158                 }
 159         }
 160         return ret;
 161 }
 162
 163 /*
 164  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 165  */
 166 LTTNG_HIDDEN
 167 int lttcomm_listen_unix_sock(int sock)
 168 {
 169         int ret;
 170
 171         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 172         if (ret < 0) {
 173                 PERROR("listen");
 174         }
 175
 176         return ret;
 177 }
 178
 179 /*
 180  * Receive data of size len in put that data into the buf param. Using recvmsg
 181  * API.
 182  *
 183  * Return the size of received data.
 184  */
 185 LTTNG_HIDDEN
 186 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 187 {
 188         struct msghdr msg;
 189         struct iovec iov[1];
 190         ssize_t ret = -1;
 191         size_t len_last;
 192
 193         memset(&msg, 0, sizeof(msg));
 194
 195         iov[0].iov_base = buf;
 196         iov[0].iov_len = len;
 197         msg.msg_iov = iov;
 198         msg.msg_iovlen = 1;
 199
 200         do {
 201                 len_last = iov[0].iov_len;
 202                 ret = lttng_recvmsg_nosigpipe(sock, &msg);
 203                 if (ret > 0) {
 204                         iov[0].iov_base += ret;
 205                         iov[0].iov_len -= ret;
 206                         assert(ret <= len_last);
 207                 }
 208         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 209         if (ret < 0) {
 210                 PERROR("recvmsg");
 211         } else if (ret > 0) {
 212                 ret = len;
 213         }
 214         /* Else ret = 0 meaning an orderly shutdown. */
 215
 216         return ret;
 217 }
 218
 219 /*
 220  * Send buf data of size len. Using sendmsg API.
 221  *
 222  * Return the size of sent data.
 223  */
 224 LTTNG_HIDDEN
 225 ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len)
 226 {
 227         struct msghdr msg;
 228         struct iovec iov[1];
 229         ssize_t ret = -1;
 230
 231         memset(&msg, 0, sizeof(msg));
 232
 233         iov[0].iov_base = (void *) buf;
 234         iov[0].iov_len = len;
 235         msg.msg_iov = iov;
 236         msg.msg_iovlen = 1;
 237
 238         ret = sendmsg(sock, &msg, 0);
 239         if (ret < 0) {
 240                 /*
 241                  * Only warn about EPIPE when quiet mode is deactivated.
 242                  * We consider EPIPE as expected.
 243                  */
 244                 if (errno != EPIPE || !lttng_opt_quiet) {
 245                         PERROR("sendmsg");
 246                 }
 247         }
 248
 249         return ret;
 250 }
 251
 252 /*
 253  * Shutdown cleanly a unix socket.
 254  */
 255 LTTNG_HIDDEN
 256 int lttcomm_close_unix_sock(int sock)
 257 {
 258         int ret, closeret;
 259
 260         /* Shutdown receptions and transmissions */
 261         ret = shutdown(sock, SHUT_RDWR);
 262         if (ret < 0) {
 263                 PERROR("shutdown");
 264         }
 265
 266         closeret = close(sock);
 267         if (closeret) {
 268                 PERROR("close");
 269         }
 270
 271         return ret;
 272 }
 273
 274 /*
 275  * Send a message accompanied by fd(s) over a unix socket.
 276  *
 277  * Returns the size of data sent, or negative error value.
 278  */
 279 LTTNG_HIDDEN
 280 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 281 {
 282         struct msghdr msg;
 283         struct cmsghdr *cmptr;
 284         struct iovec iov[1];
 285         ssize_t ret = -1;
 286         unsigned int sizeof_fds = nb_fd * sizeof(int);
 287         char tmp[CMSG_SPACE(sizeof_fds)];
 288         char dummy = 0;
 289
 290         memset(&msg, 0, sizeof(msg));
 291         memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
 292
 293         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 294                 return -EINVAL;
 295
 296         msg.msg_control = (caddr_t)tmp;
 297         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 298
 299         cmptr = CMSG_FIRSTHDR(&msg);
 300         if (!cmptr) {
 301                 return -1;
 302         }
 303         cmptr->cmsg_level = SOL_SOCKET;
 304         cmptr->cmsg_type = SCM_RIGHTS;
 305         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 306         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 307         /* Sum of the length of all control messages in the buffer: */
 308         msg.msg_controllen = cmptr->cmsg_len;
 309
 310         iov[0].iov_base = &dummy;
 311         iov[0].iov_len = 1;
 312         msg.msg_iov = iov;
 313         msg.msg_iovlen = 1;
 314
 315         do {
 316                 ret = sendmsg(sock, &msg, 0);
 317         } while (ret < 0 && errno == EINTR);
 318         if (ret < 0) {
 319                 /*
 320                  * Only warn about EPIPE when quiet mode is deactivated.
 321                  * We consider EPIPE as expected.
 322                  */
 323                 if (errno != EPIPE || !lttng_opt_quiet) {
 324                         PERROR("sendmsg");
 325                 }
 326         }
 327         return ret;
 328 }
 329
 330 /*
 331  * Recv a message accompanied by fd(s) from a unix socket.
 332  *
 333  * Returns the size of received data, or negative error value.
 334  *
 335  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 336  * actually received in nb_fd.
 337  */
 338 LTTNG_HIDDEN
 339 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 340 {
 341         struct iovec iov[1];
 342         ssize_t ret = 0;
 343         struct cmsghdr *cmsg;
 344         size_t sizeof_fds = nb_fd * sizeof(int);
 345         char recv_fd[CMSG_SPACE(sizeof_fds)];
 346         struct msghdr msg;
 347         char dummy;
 348
 349         memset(&msg, 0, sizeof(msg));
 350
 351         /* Prepare to receive the structures */
 352         iov[0].iov_base = &dummy;
 353         iov[0].iov_len = 1;
 354         msg.msg_iov = iov;
 355         msg.msg_iovlen = 1;
 356         msg.msg_control = recv_fd;
 357         msg.msg_controllen = sizeof(recv_fd);
 358
 359         do {
 360                 ret = recvmsg(sock, &msg, 0);
 361         } while (ret < 0 && errno == EINTR);
 362         if (ret < 0) {
 363                 PERROR("recvmsg fds");
 364                 goto end;
 365         }
 366         if (ret != 1) {
 367                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 368                                 ret, 1);
 369                 goto end;
 370         }
 371         if (msg.msg_flags & MSG_CTRUNC) {
 372                 fprintf(stderr, "Error: Control message truncated.\n");
 373                 ret = -1;
 374                 goto end;
 375         }
 376         cmsg = CMSG_FIRSTHDR(&msg);
 377         if (!cmsg) {
 378                 fprintf(stderr, "Error: Invalid control message header\n");
 379                 ret = -1;
 380                 goto end;
 381         }
 382         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 383                 fprintf(stderr, "Didn't received any fd\n");
 384                 ret = -1;
 385                 goto end;
 386         }
 387         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 388                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 389                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 390                 ret = -1;
 391                 goto end;
 392         }
 393         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 394         ret = sizeof_fds;
 395 end:
 396         return ret;
 397 }
 398
 399 /*
 400  * Send a message with credentials over a unix socket.
 401  *
 402  * Returns the size of data sent, or negative error value.
 403  */
 404 LTTNG_HIDDEN
 405 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 406 {
 407         struct msghdr msg;
 408         struct iovec iov[1];
 409         ssize_t ret = -1;
 410 #ifdef __linux__
 411         struct cmsghdr *cmptr;
 412         size_t sizeof_cred = sizeof(lttng_sock_cred);
 413         char anc_buf[CMSG_SPACE(sizeof_cred)];
 414         lttng_sock_cred *creds;
 415
 416         memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
 417 #endif /* __linux__ */
 418
 419         memset(&msg, 0, sizeof(msg));
 420
 421         iov[0].iov_base = buf;
 422         iov[0].iov_len = len;
 423         msg.msg_iov = iov;
 424         msg.msg_iovlen = 1;
 425
 426 #ifdef __linux__
 427         msg.msg_control = (caddr_t) anc_buf;
 428         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 429
 430         cmptr = CMSG_FIRSTHDR(&msg);
 431         if (!cmptr) {
 432                 return -1;
 433         }
 434         cmptr->cmsg_level = SOL_SOCKET;
 435         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 436         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 437
 438         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 439
 440         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 441         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 442         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 443 #endif /* __linux__ */
 444
 445         do {
 446                 ret = sendmsg(sock, &msg, 0);
 447         } while (ret < 0 && errno == EINTR);
 448         if (ret < 0) {
 449                 /*
 450                  * Only warn about EPIPE when quiet mode is deactivated.
 451                  * We consider EPIPE as expected.
 452                  */
 453                 if (errno != EPIPE || !lttng_opt_quiet) {
 454                         PERROR("sendmsg");
 455                 }
 456         }
 457         return ret;
 458 }
 459
 460 /*
 461  * Recv a message accompanied with credentials from a unix socket.
 462  *
 463  * Returns the size of received data, or negative error value.
 464  */
 465 LTTNG_HIDDEN
 466 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 467                 lttng_sock_cred *creds)
 468 {
 469         struct msghdr msg;
 470         struct iovec iov[1];
 471         ssize_t ret;
 472         size_t len_last;
 473 #ifdef __linux__
 474         struct cmsghdr *cmptr;
 475         size_t sizeof_cred = sizeof(lttng_sock_cred);
 476         char anc_buf[CMSG_SPACE(sizeof_cred)];
 477 #endif  /* __linux__ */
 478
 479         memset(&msg, 0, sizeof(msg));
 480
 481         /* Not allowed */
 482         if (creds == NULL) {
 483                 ret = -1;
 484                 goto end;
 485         }
 486
 487         /* Prepare to receive the structures */
 488         iov[0].iov_base = buf;
 489         iov[0].iov_len = len;
 490         msg.msg_iov = iov;
 491         msg.msg_iovlen = 1;
 492
 493 #ifdef __linux__
 494         msg.msg_control = anc_buf;
 495         msg.msg_controllen = sizeof(anc_buf);
 496 #endif /* __linux__ */
 497
 498         do {
 499                 len_last = iov[0].iov_len;
 500                 ret = recvmsg(sock, &msg, 0);
 501                 if (ret > 0) {
 502                         iov[0].iov_base += ret;
 503                         iov[0].iov_len -= ret;
 504                         assert(ret <= len_last);
 505                 }
 506         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 507         if (ret < 0) {
 508                 PERROR("recvmsg fds");
 509                 goto end;
 510         } else if (ret > 0) {
 511                 ret = len;
 512         }
 513         /* Else ret = 0 meaning an orderly shutdown. */
 514
 515 #ifdef __linux__
 516         if (msg.msg_flags & MSG_CTRUNC) {
 517                 fprintf(stderr, "Error: Control message truncated.\n");
 518                 ret = -1;
 519                 goto end;
 520         }
 521
 522         cmptr = CMSG_FIRSTHDR(&msg);
 523         if (cmptr == NULL) {
 524                 fprintf(stderr, "Error: Invalid control message header\n");
 525                 ret = -1;
 526                 goto end;
 527         }
 528
 529         if (cmptr->cmsg_level != SOL_SOCKET ||
 530                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 531                 fprintf(stderr, "Didn't received any credentials\n");
 532                 ret = -1;
 533                 goto end;
 534         }
 535
 536         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 537                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 538                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 539                 ret = -1;
 540                 goto end;
 541         }
 542
 543         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 544 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__))
 545         {
 546                 int peer_ret;
 547
 548                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 549                 if (peer_ret != 0) {
 550                         return peer_ret;
 551                 }
 552         }
 553 #else
 554 #error "Please implement credential support for your OS."
 555 #endif  /* __linux__ */
 556
 557 end:
 558         return ret;
 559 }
 560
 561 /*
 562  * Set socket option to use credentials passing.
 563  */
 564 #ifdef __linux__
 565 LTTNG_HIDDEN
 566 int lttcomm_setsockopt_creds_unix_sock(int sock)
 567 {
 568         int ret, on = 1;
 569
 570         /* Set socket for credentials retrieval */
 571         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 572         if (ret < 0) {
 573                 PERROR("setsockopt creds unix sock");
 574         }
 575         return ret;
 576 }
 577 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__))
 578 LTTNG_HIDDEN
 579 int lttcomm_setsockopt_creds_unix_sock(int sock)
 580 {
 581         return 0;
 582 }
 583 #else
 584 #error "Please implement credential support for your OS."
 585 #endif /* __linux__ */