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