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/defaults.h>
  31 #include <common/error.h>
  32
  33 #include "unix.h"
  34
  35 /*
  36  * Connect to unix socket using the path name.
  37  */
  38 __attribute__((visibility("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 __attribute__((visibility("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 __attribute__((visibility("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         return ret;
 130 }
 131
 132 /*
 133  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 134  */
 135 __attribute__((visibility("hidden")))
 136 int lttcomm_listen_unix_sock(int sock)
 137 {
 138         int ret;
 139
 140         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 141         if (ret < 0) {
 142                 PERROR("listen");
 143         }
 144
 145         return ret;
 146 }
 147
 148 /*
 149  * Receive data of size len in put that data into the buf param. Using recvmsg
 150  * API.
 151  *
 152  * Return the size of received data.
 153  */
 154 __attribute__((visibility("hidden")))
 155 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 156 {
 157         struct msghdr msg;
 158         struct iovec iov[1];
 159         ssize_t ret = -1;
 160
 161         memset(&msg, 0, sizeof(msg));
 162
 163         iov[0].iov_base = buf;
 164         iov[0].iov_len = len;
 165         msg.msg_iov = iov;
 166         msg.msg_iovlen = 1;
 167
 168         do {
 169                 ret = recvmsg(sock, &msg, MSG_WAITALL);
 170         } while (ret < 0 && errno == EINTR);
 171         if (ret < 0) {
 172                 PERROR("recvmsg");
 173         }
 174
 175         return ret;
 176 }
 177
 178 /*
 179  * Send buf data of size len. Using sendmsg API.
 180  *
 181  * Return the size of sent data.
 182  */
 183 __attribute__((visibility("hidden")))
 184 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 185 {
 186         struct msghdr msg;
 187         struct iovec iov[1];
 188         ssize_t ret = -1;
 189
 190         memset(&msg, 0, sizeof(msg));
 191
 192         iov[0].iov_base = buf;
 193         iov[0].iov_len = len;
 194         msg.msg_iov = iov;
 195         msg.msg_iovlen = 1;
 196
 197         ret = sendmsg(sock, &msg, 0);
 198         if (ret < 0) {
 199                 /*
 200                  * Only warn about EPIPE when quiet mode is deactivated.
 201                  * We consider EPIPE as expected.
 202                  */
 203                 if (errno != EPIPE || !lttng_opt_quiet) {
 204                         PERROR("sendmsg");
 205                 }
 206         }
 207
 208         return ret;
 209 }
 210
 211 /*
 212  * Shutdown cleanly a unix socket.
 213  */
 214 __attribute__((visibility("hidden")))
 215 int lttcomm_close_unix_sock(int sock)
 216 {
 217         int ret, closeret;
 218
 219         /* Shutdown receptions and transmissions */
 220         ret = shutdown(sock, SHUT_RDWR);
 221         if (ret < 0) {
 222                 PERROR("shutdown");
 223         }
 224
 225         closeret = close(sock);
 226         if (closeret) {
 227                 PERROR("close");
 228         }
 229
 230         return ret;
 231 }
 232
 233 /*
 234  * Send a message accompanied by fd(s) over a unix socket.
 235  *
 236  * Returns the size of data sent, or negative error value.
 237  */
 238 __attribute__((visibility("hidden")))
 239 ssize_t lttcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 240 {
 241         struct msghdr msg;
 242         struct cmsghdr *cmptr;
 243         struct iovec iov[1];
 244         ssize_t ret = -1;
 245         unsigned int sizeof_fds = nb_fd * sizeof(int);
 246         char tmp[CMSG_SPACE(sizeof_fds)];
 247         char dummy = 0;
 248
 249         memset(&msg, 0, sizeof(msg));
 250
 251         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 252                 return -EINVAL;
 253
 254         msg.msg_control = (caddr_t)tmp;
 255         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 256
 257         cmptr = CMSG_FIRSTHDR(&msg);
 258         cmptr->cmsg_level = SOL_SOCKET;
 259         cmptr->cmsg_type = SCM_RIGHTS;
 260         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 261         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 262         /* Sum of the length of all control messages in the buffer: */
 263         msg.msg_controllen = cmptr->cmsg_len;
 264
 265         iov[0].iov_base = &dummy;
 266         iov[0].iov_len = 1;
 267         msg.msg_iov = iov;
 268         msg.msg_iovlen = 1;
 269
 270         do {
 271                 ret = sendmsg(sock, &msg, 0);
 272         } while (ret < 0 && errno == EINTR);
 273         if (ret < 0) {
 274                 /*
 275                  * Only warn about EPIPE when quiet mode is deactivated.
 276                  * We consider EPIPE as expected.
 277                  */
 278                 if (errno != EPIPE || !lttng_opt_quiet) {
 279                         PERROR("sendmsg");
 280                 }
 281         }
 282         return ret;
 283 }
 284
 285 /*
 286  * Recv a message accompanied by fd(s) from a unix socket.
 287  *
 288  * Returns the size of received data, or negative error value.
 289  *
 290  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 291  * actually received in nb_fd.
 292  */
 293 __attribute__((visibility("hidden")))
 294 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 295 {
 296         struct iovec iov[1];
 297         ssize_t ret = 0;
 298         struct cmsghdr *cmsg;
 299         size_t sizeof_fds = nb_fd * sizeof(int);
 300         char recv_fd[CMSG_SPACE(sizeof_fds)];
 301         struct msghdr msg;
 302         char dummy;
 303
 304         memset(&msg, 0, sizeof(msg));
 305
 306         /* Prepare to receive the structures */
 307         iov[0].iov_base = &dummy;
 308         iov[0].iov_len = 1;
 309         msg.msg_iov = iov;
 310         msg.msg_iovlen = 1;
 311         msg.msg_control = recv_fd;
 312         msg.msg_controllen = sizeof(recv_fd);
 313
 314         do {
 315                 ret = recvmsg(sock, &msg, 0);
 316         } while (ret < 0 && errno == EINTR);
 317         if (ret < 0) {
 318                 PERROR("recvmsg fds");
 319                 goto end;
 320         }
 321         if (ret != 1) {
 322                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 323                                 ret, 1);
 324                 goto end;
 325         }
 326         if (msg.msg_flags & MSG_CTRUNC) {
 327                 fprintf(stderr, "Error: Control message truncated.\n");
 328                 ret = -1;
 329                 goto end;
 330         }
 331         cmsg = CMSG_FIRSTHDR(&msg);
 332         if (!cmsg) {
 333                 fprintf(stderr, "Error: Invalid control message header\n");
 334                 ret = -1;
 335                 goto end;
 336         }
 337         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 338                 fprintf(stderr, "Didn't received any fd\n");
 339                 ret = -1;
 340                 goto end;
 341         }
 342         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 343                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 344                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 345                 ret = -1;
 346                 goto end;
 347         }
 348         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 349         ret = sizeof_fds;
 350 end:
 351         return ret;
 352 }
 353
 354 /*
 355  * Send a message with credentials over a unix socket.
 356  *
 357  * Returns the size of data sent, or negative error value.
 358  */
 359 __attribute__((visibility("hidden")))
 360 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 361 {
 362         struct msghdr msg;
 363         struct iovec iov[1];
 364         ssize_t ret = -1;
 365 #ifdef __linux__
 366         struct cmsghdr *cmptr;
 367         size_t sizeof_cred = sizeof(lttng_sock_cred);
 368         char anc_buf[CMSG_SPACE(sizeof_cred)];
 369         lttng_sock_cred *creds;
 370 #endif /* __linux__ */
 371
 372         memset(&msg, 0, sizeof(msg));
 373
 374         iov[0].iov_base = buf;
 375         iov[0].iov_len = len;
 376         msg.msg_iov = iov;
 377         msg.msg_iovlen = 1;
 378
 379 #ifdef __linux__
 380         msg.msg_control = (caddr_t) anc_buf;
 381         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 382
 383         cmptr = CMSG_FIRSTHDR(&msg);
 384         cmptr->cmsg_level = SOL_SOCKET;
 385         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 386         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 387
 388         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 389
 390         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 391         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 392         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 393 #endif /* __linux__ */
 394
 395         do {
 396                 ret = sendmsg(sock, &msg, 0);
 397         } while (ret < 0 && errno == EINTR);
 398         if (ret < 0) {
 399                 /*
 400                  * Only warn about EPIPE when quiet mode is deactivated.
 401                  * We consider EPIPE as expected.
 402                  */
 403                 if (errno != EPIPE || !lttng_opt_quiet) {
 404                         PERROR("sendmsg");
 405                 }
 406         }
 407         return ret;
 408 }
 409
 410 /*
 411  * Recv a message accompanied with credentials from a unix socket.
 412  *
 413  * Returns the size of received data, or negative error value.
 414  */
 415 __attribute__((visibility("hidden")))
 416 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 417                 lttng_sock_cred *creds)
 418 {
 419         struct msghdr msg;
 420         struct iovec iov[1];
 421         ssize_t ret;
 422 #ifdef __linux__
 423         struct cmsghdr *cmptr;
 424         size_t sizeof_cred = sizeof(lttng_sock_cred);
 425         char anc_buf[CMSG_SPACE(sizeof_cred)];
 426 #endif  /* __linux__ */
 427
 428         memset(&msg, 0, sizeof(msg));
 429
 430         /* Not allowed */
 431         if (creds == NULL) {
 432                 ret = -1;
 433                 goto end;
 434         }
 435
 436         /* Prepare to receive the structures */
 437         iov[0].iov_base = buf;
 438         iov[0].iov_len = len;
 439         msg.msg_iov = iov;
 440         msg.msg_iovlen = 1;
 441
 442 #ifdef __linux__
 443         msg.msg_control = anc_buf;
 444         msg.msg_controllen = sizeof(anc_buf);
 445 #endif /* __linux__ */
 446
 447         do {
 448                 ret = recvmsg(sock, &msg, 0);
 449         } while (ret < 0 && errno == EINTR);
 450         if (ret < 0) {
 451                 PERROR("recvmsg fds");
 452                 goto end;
 453         }
 454
 455 #ifdef __linux__
 456         if (msg.msg_flags & MSG_CTRUNC) {
 457                 fprintf(stderr, "Error: Control message truncated.\n");
 458                 ret = -1;
 459                 goto end;
 460         }
 461
 462         cmptr = CMSG_FIRSTHDR(&msg);
 463         if (cmptr == NULL) {
 464                 fprintf(stderr, "Error: Invalid control message header\n");
 465                 ret = -1;
 466                 goto end;
 467         }
 468
 469         if (cmptr->cmsg_level != SOL_SOCKET ||
 470                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 471                 fprintf(stderr, "Didn't received any credentials\n");
 472                 ret = -1;
 473                 goto end;
 474         }
 475
 476         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 477                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 478                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 479                 ret = -1;
 480                 goto end;
 481         }
 482
 483         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 484 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 485         {
 486                 int peer_ret;
 487
 488                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 489                 if (peer_ret != 0) {
 490                         return peer_ret;
 491                 }
 492         }
 493 #else
 494 #error "Please implement credential support for your OS."
 495 #endif  /* __linux__ */
 496
 497 end:
 498         return ret;
 499 }
 500
 501 /*
 502  * Set socket option to use credentials passing.
 503  */
 504 #ifdef __linux__
 505 __attribute__((visibility("hidden")))
 506 int lttcomm_setsockopt_creds_unix_sock(int sock)
 507 {
 508         int ret, on = 1;
 509
 510         /* Set socket for credentials retrieval */
 511         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 512         if (ret < 0) {
 513                 PERROR("setsockopt creds unix sock");
 514         }
 515         return ret;
 516 }
 517 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 518 __attribute__((visibility("hidden")))
 519 int lttcomm_setsockopt_creds_unix_sock(int sock)
 520 {
 521         return 0;
 522 }
 523 #else
 524 #error "Please implement credential support for your OS."
 525 #endif /* __linux__ */