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 #define _LGPL_SOURCE
  21 #include <assert.h>
  22 #include <limits.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <sys/stat.h>
  27 #include <sys/types.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30
  31 #include <common/common.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 sun;
  42         int fd, ret, closeret;
  43
  44         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  45         if (fd < 0) {
  46                 PERROR("socket");
  47                 ret = fd;
  48                 goto error;
  49         }
  50
  51         memset(&sun, 0, sizeof(sun));
  52         sun.sun_family = AF_UNIX;
  53         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
  54         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
  55
  56         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
  57         if (ret < 0) {
  58                 /*
  59                  * Don't print message on connect error, because connect is used in
  60                  * normal execution to detect if sessiond is alive.
  61                  */
  62                 goto error_connect;
  63         }
  64
  65         return fd;
  66
  67 error_connect:
  68         closeret = close(fd);
  69         if (closeret) {
  70                 PERROR("close");
  71         }
  72 error:
  73         return ret;
  74 }
  75
  76 /*
  77  * Do an accept(2) on the sock and return the new file descriptor. The socket
  78  * MUST be bind(2) before.
  79  */
  80 LTTNG_HIDDEN
  81 int lttcomm_accept_unix_sock(int sock)
  82 {
  83         int new_fd;
  84         struct sockaddr_un sun;
  85         socklen_t len = 0;
  86
  87         /* Blocking call */
  88         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
  89         if (new_fd < 0) {
  90                 PERROR("accept");
  91         }
  92
  93         return new_fd;
  94 }
  95
  96 LTTNG_HIDDEN
  97 int lttcomm_create_anon_unix_socketpair(int *fds)
  98 {
  99         if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
 100                 PERROR("socketpair");
 101                 return -1;
 102         }
 103         return 0;
 104 }
 105
 106 /*
 107  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 108  * and return the fd.
 109  */
 110 LTTNG_HIDDEN
 111 int lttcomm_create_unix_sock(const char *pathname)
 112 {
 113         struct sockaddr_un sun;
 114         int fd;
 115         int ret = -1;
 116
 117         /* Create server socket */
 118         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 119                 PERROR("socket");
 120                 goto error;
 121         }
 122
 123         memset(&sun, 0, sizeof(sun));
 124         sun.sun_family = AF_UNIX;
 125         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 126         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 127
 128         /* Unlink the old file if present */
 129         (void) unlink(pathname);
 130         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 131         if (ret < 0) {
 132                 PERROR("bind");
 133                 goto error;
 134         }
 135
 136         return fd;
 137
 138 error:
 139         if (fd >= 0) {
 140                 if (close(fd) < 0) {
 141                         PERROR("close create unix sock");
 142                 }
 143         }
 144         return ret;
 145 }
 146
 147 /*
 148  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 149  */
 150 LTTNG_HIDDEN
 151 int lttcomm_listen_unix_sock(int sock)
 152 {
 153         int ret;
 154
 155         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 156         if (ret < 0) {
 157                 PERROR("listen");
 158         }
 159
 160         return ret;
 161 }
 162
 163 /*
 164  * Receive data of size len in put that data into the buf param. Using recvmsg
 165  * API.
 166  *
 167  * Return the size of received data.
 168  */
 169 LTTNG_HIDDEN
 170 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 171 {
 172         struct msghdr msg;
 173         struct iovec iov[1];
 174         ssize_t ret = -1;
 175         size_t len_last;
 176
 177         memset(&msg, 0, sizeof(msg));
 178
 179         iov[0].iov_base = buf;
 180         iov[0].iov_len = len;
 181         msg.msg_iov = iov;
 182         msg.msg_iovlen = 1;
 183
 184         do {
 185                 len_last = iov[0].iov_len;
 186                 ret = recvmsg(sock, &msg, MSG_NOSIGNAL);
 187                 if (ret > 0) {
 188                         iov[0].iov_base += ret;
 189                         iov[0].iov_len -= ret;
 190                         assert(ret <= len_last);
 191                 }
 192         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 193         if (ret < 0) {
 194                 PERROR("recvmsg");
 195         } else if (ret > 0) {
 196                 ret = len;
 197         }
 198         /* Else ret = 0 meaning an orderly shutdown. */
 199
 200         return ret;
 201 }
 202
 203 /*
 204  * Send buf data of size len. Using sendmsg API.
 205  *
 206  * Return the size of sent data.
 207  */
 208 LTTNG_HIDDEN
 209 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 210 {
 211         struct msghdr msg;
 212         struct iovec iov[1];
 213         ssize_t ret = -1;
 214
 215         memset(&msg, 0, sizeof(msg));
 216
 217         iov[0].iov_base = buf;
 218         iov[0].iov_len = len;
 219         msg.msg_iov = iov;
 220         msg.msg_iovlen = 1;
 221
 222         ret = sendmsg(sock, &msg, 0);
 223         if (ret < 0) {
 224                 /*
 225                  * Only warn about EPIPE when quiet mode is deactivated.
 226                  * We consider EPIPE as expected.
 227                  */
 228                 if (errno != EPIPE || !lttng_opt_quiet) {
 229                         PERROR("sendmsg");
 230                 }
 231         }
 232
 233         return ret;
 234 }
 235
 236 /*
 237  * Shutdown cleanly a unix socket.
 238  */
 239 LTTNG_HIDDEN
 240 int lttcomm_close_unix_sock(int sock)
 241 {
 242         int ret, closeret;
 243
 244         /* Shutdown receptions and transmissions */
 245         ret = shutdown(sock, SHUT_RDWR);
 246         if (ret < 0) {
 247                 PERROR("shutdown");
 248         }
 249
 250         closeret = close(sock);
 251         if (closeret) {
 252                 PERROR("close");
 253         }
 254
 255         return ret;
 256 }
 257
 258 /*
 259  * Send a message accompanied by fd(s) over a unix socket.
 260  *
 261  * Returns the size of data sent, or negative error value.
 262  */
 263 LTTNG_HIDDEN
 264 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 265 {
 266         struct msghdr msg;
 267         struct cmsghdr *cmptr;
 268         struct iovec iov[1];
 269         ssize_t ret = -1;
 270         unsigned int sizeof_fds = nb_fd * sizeof(int);
 271         char tmp[CMSG_SPACE(sizeof_fds)];
 272         char dummy = 0;
 273
 274         memset(&msg, 0, sizeof(msg));
 275         memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
 276
 277         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 278                 return -EINVAL;
 279
 280         msg.msg_control = (caddr_t)tmp;
 281         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 282
 283         cmptr = CMSG_FIRSTHDR(&msg);
 284         if (!cmptr) {
 285                 return -1;
 286         }
 287         cmptr->cmsg_level = SOL_SOCKET;
 288         cmptr->cmsg_type = SCM_RIGHTS;
 289         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 290         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 291         /* Sum of the length of all control messages in the buffer: */
 292         msg.msg_controllen = cmptr->cmsg_len;
 293
 294         iov[0].iov_base = &dummy;
 295         iov[0].iov_len = 1;
 296         msg.msg_iov = iov;
 297         msg.msg_iovlen = 1;
 298
 299         do {
 300                 ret = sendmsg(sock, &msg, 0);
 301         } while (ret < 0 && errno == EINTR);
 302         if (ret < 0) {
 303                 /*
 304                  * Only warn about EPIPE when quiet mode is deactivated.
 305                  * We consider EPIPE as expected.
 306                  */
 307                 if (errno != EPIPE || !lttng_opt_quiet) {
 308                         PERROR("sendmsg");
 309                 }
 310         }
 311         return ret;
 312 }
 313
 314 /*
 315  * Recv a message accompanied by fd(s) from a unix socket.
 316  *
 317  * Returns the size of received data, or negative error value.
 318  *
 319  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 320  * actually received in nb_fd.
 321  */
 322 LTTNG_HIDDEN
 323 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 324 {
 325         struct iovec iov[1];
 326         ssize_t ret = 0;
 327         struct cmsghdr *cmsg;
 328         size_t sizeof_fds = nb_fd * sizeof(int);
 329         char recv_fd[CMSG_SPACE(sizeof_fds)];
 330         struct msghdr msg;
 331         char dummy;
 332
 333         memset(&msg, 0, sizeof(msg));
 334
 335         /* Prepare to receive the structures */
 336         iov[0].iov_base = &dummy;
 337         iov[0].iov_len = 1;
 338         msg.msg_iov = iov;
 339         msg.msg_iovlen = 1;
 340         msg.msg_control = recv_fd;
 341         msg.msg_controllen = sizeof(recv_fd);
 342
 343         do {
 344                 ret = recvmsg(sock, &msg, 0);
 345         } while (ret < 0 && errno == EINTR);
 346         if (ret < 0) {
 347                 PERROR("recvmsg fds");
 348                 goto end;
 349         }
 350         if (ret != 1) {
 351                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 352                                 ret, 1);
 353                 goto end;
 354         }
 355         if (msg.msg_flags & MSG_CTRUNC) {
 356                 fprintf(stderr, "Error: Control message truncated.\n");
 357                 ret = -1;
 358                 goto end;
 359         }
 360         cmsg = CMSG_FIRSTHDR(&msg);
 361         if (!cmsg) {
 362                 fprintf(stderr, "Error: Invalid control message header\n");
 363                 ret = -1;
 364                 goto end;
 365         }
 366         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 367                 fprintf(stderr, "Didn't received any fd\n");
 368                 ret = -1;
 369                 goto end;
 370         }
 371         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 372                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 373                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 374                 ret = -1;
 375                 goto end;
 376         }
 377         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 378         ret = sizeof_fds;
 379 end:
 380         return ret;
 381 }
 382
 383 /*
 384  * Send a message with credentials over a unix socket.
 385  *
 386  * Returns the size of data sent, or negative error value.
 387  */
 388 LTTNG_HIDDEN
 389 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 390 {
 391         struct msghdr msg;
 392         struct iovec iov[1];
 393         ssize_t ret = -1;
 394 #ifdef __linux__
 395         struct cmsghdr *cmptr;
 396         size_t sizeof_cred = sizeof(lttng_sock_cred);
 397         char anc_buf[CMSG_SPACE(sizeof_cred)];
 398         lttng_sock_cred *creds;
 399 #endif /* __linux__ */
 400
 401         memset(&msg, 0, sizeof(msg));
 402         memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
 403
 404         iov[0].iov_base = buf;
 405         iov[0].iov_len = len;
 406         msg.msg_iov = iov;
 407         msg.msg_iovlen = 1;
 408
 409 #ifdef __linux__
 410         msg.msg_control = (caddr_t) anc_buf;
 411         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 412
 413         cmptr = CMSG_FIRSTHDR(&msg);
 414         if (!cmptr) {
 415                 return -1;
 416         }
 417         cmptr->cmsg_level = SOL_SOCKET;
 418         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 419         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 420
 421         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 422
 423         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 424         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 425         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 426 #endif /* __linux__ */
 427
 428         do {
 429                 ret = sendmsg(sock, &msg, 0);
 430         } while (ret < 0 && errno == EINTR);
 431         if (ret < 0) {
 432                 /*
 433                  * Only warn about EPIPE when quiet mode is deactivated.
 434                  * We consider EPIPE as expected.
 435                  */
 436                 if (errno != EPIPE || !lttng_opt_quiet) {
 437                         PERROR("sendmsg");
 438                 }
 439         }
 440         return ret;
 441 }
 442
 443 /*
 444  * Recv a message accompanied with credentials from a unix socket.
 445  *
 446  * Returns the size of received data, or negative error value.
 447  */
 448 LTTNG_HIDDEN
 449 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 450                 lttng_sock_cred *creds)
 451 {
 452         struct msghdr msg;
 453         struct iovec iov[1];
 454         ssize_t ret;
 455         size_t len_last;
 456 #ifdef __linux__
 457         struct cmsghdr *cmptr;
 458         size_t sizeof_cred = sizeof(lttng_sock_cred);
 459         char anc_buf[CMSG_SPACE(sizeof_cred)];
 460 #endif  /* __linux__ */
 461
 462         memset(&msg, 0, sizeof(msg));
 463
 464         /* Not allowed */
 465         if (creds == NULL) {
 466                 ret = -1;
 467                 goto end;
 468         }
 469
 470         /* Prepare to receive the structures */
 471         iov[0].iov_base = buf;
 472         iov[0].iov_len = len;
 473         msg.msg_iov = iov;
 474         msg.msg_iovlen = 1;
 475
 476 #ifdef __linux__
 477         msg.msg_control = anc_buf;
 478         msg.msg_controllen = sizeof(anc_buf);
 479 #endif /* __linux__ */
 480
 481         do {
 482                 len_last = iov[0].iov_len;
 483                 ret = recvmsg(sock, &msg, 0);
 484                 if (ret > 0) {
 485                         iov[0].iov_base += ret;
 486                         iov[0].iov_len -= ret;
 487                         assert(ret <= len_last);
 488                 }
 489         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 490         if (ret < 0) {
 491                 PERROR("recvmsg fds");
 492                 goto end;
 493         } else if (ret > 0) {
 494                 ret = len;
 495         }
 496         /* Else ret = 0 meaning an orderly shutdown. */
 497
 498 #ifdef __linux__
 499         if (msg.msg_flags & MSG_CTRUNC) {
 500                 fprintf(stderr, "Error: Control message truncated.\n");
 501                 ret = -1;
 502                 goto end;
 503         }
 504
 505         cmptr = CMSG_FIRSTHDR(&msg);
 506         if (cmptr == NULL) {
 507                 fprintf(stderr, "Error: Invalid control message header\n");
 508                 ret = -1;
 509                 goto end;
 510         }
 511
 512         if (cmptr->cmsg_level != SOL_SOCKET ||
 513                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 514                 fprintf(stderr, "Didn't received any credentials\n");
 515                 ret = -1;
 516                 goto end;
 517         }
 518
 519         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 520                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 521                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 522                 ret = -1;
 523                 goto end;
 524         }
 525
 526         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 527 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 528         {
 529                 int peer_ret;
 530
 531                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 532                 if (peer_ret != 0) {
 533                         return peer_ret;
 534                 }
 535         }
 536 #else
 537 #error "Please implement credential support for your OS."
 538 #endif  /* __linux__ */
 539
 540 end:
 541         return ret;
 542 }
 543
 544 /*
 545  * Set socket option to use credentials passing.
 546  */
 547 #ifdef __linux__
 548 LTTNG_HIDDEN
 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         return ret;
 559 }
 560 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 561 LTTNG_HIDDEN
 562 int lttcomm_setsockopt_creds_unix_sock(int sock)
 563 {
 564         return 0;
 565 }
 566 #else
 567 #error "Please implement credential support for your OS."
 568 #endif /* __linux__ */