src/stdout-syslog-bridge.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/socket.h>
  23 #include <sys/types.h>
  24 #include <assert.h>
  25 #include <time.h>
  26 #include <string.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <unistd.h>
  30 #include <sys/poll.h>
  31 #include <sys/epoll.h>
  32 #include <sys/un.h>
  33 #include <fcntl.h>
  34
  35 #include "util.h"
  36 #include "log.h"
  37 #include "list.h"
  38 #include "sd-daemon.h"
  39 #include "tcpwrap.h"
  40 #include "def.h"
  41
  42 #define STREAMS_MAX 4096
  43 #define SERVER_FD_MAX 16
  44 #define TIMEOUT_MSEC ((int) (DEFAULT_EXIT_USEC/USEC_PER_MSEC))
  45
  46 typedef struct Stream Stream;
  47
  48 typedef struct Server {
  49         int syslog_fd;
  50         int kmsg_fd;
  51         int epoll_fd;
  52
  53         unsigned n_server_fd;
  54
  55         bool syslog_is_stream;
  56
  57         LIST_HEAD(Stream, streams);
  58         unsigned n_streams;
  59 } Server;
  60
  61 typedef enum StreamTarget {
  62         STREAM_SYSLOG,
  63         STREAM_KMSG
  64 } StreamTarget;
  65
  66 typedef enum StreamState {
  67         STREAM_TARGET,
  68         STREAM_PRIORITY,
  69         STREAM_PROCESS,
  70         STREAM_PREFIX,
  71         STREAM_RUNNING
  72 } StreamState;
  73
  74 struct Stream {
  75         Server *server;
  76
  77         StreamState state;
  78
  79         int fd;
  80
  81         StreamTarget target;
  82         int priority;
  83         char *process;
  84         pid_t pid;
  85         uid_t uid;
  86         gid_t gid;
  87
  88         bool prefix:1;
  89         bool tee_console:1;
  90
  91         char buffer[LINE_MAX+1];
  92         size_t length;
  93
  94         LIST_FIELDS(Stream, stream);
  95 };
  96
  97 static int stream_log(Stream *s, char *p, usec_t ts) {
  98
  99         char header_priority[16], header_time[64], header_pid[16];
 100         struct iovec iovec[5];
 101         int priority;
 102
 103         assert(s);
 104         assert(p);
 105
 106         priority = s->priority;
 107
 108         if (s->prefix)
 109                 parse_syslog_priority(&p, &priority);
 110
 111         if (*p == 0)
 112                 return 0;
 113
 114         /* Patch in configured facility if necessary */
 115         if ((priority & LOG_FACMASK) == 0)
 116                 priority = (s->priority & LOG_FACMASK) | priority;
 117
 118         /*
 119          * The format glibc uses to talk to the syslog daemon is:
 120          *
 121          *     <priority>time process[pid]: msg
 122          *
 123          * The format the kernel uses is:
 124          *
 125          *     <priority>msg\n
 126          *
 127          *  We extend the latter to include the process name and pid.
 128          */
 129
 130         snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
 131         char_array_0(header_priority);
 132
 133         if (s->target == STREAM_SYSLOG) {
 134                 time_t t;
 135                 struct tm *tm;
 136
 137                 t = (time_t) (ts / USEC_PER_SEC);
 138                 if (!(tm = localtime(&t)))
 139                         return -EINVAL;
 140
 141                 if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
 142                         return -EINVAL;
 143         }
 144
 145         snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) s->pid);
 146         char_array_0(header_pid);
 147
 148         zero(iovec);
 149         IOVEC_SET_STRING(iovec[0], header_priority);
 150
 151         if (s->target == STREAM_SYSLOG) {
 152                 struct msghdr msghdr;
 153                 union {
 154                         struct cmsghdr cmsghdr;
 155                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 156                 } control;
 157                 struct ucred *ucred;
 158
 159                 zero(control);
 160                 control.cmsghdr.cmsg_level = SOL_SOCKET;
 161                 control.cmsghdr.cmsg_type = SCM_CREDENTIALS;
 162                 control.cmsghdr.cmsg_len = CMSG_LEN(sizeof(struct ucred));
 163
 164                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 165                 ucred->pid = s->pid;
 166                 ucred->uid = s->uid;
 167                 ucred->gid = s->gid;
 168
 169                 IOVEC_SET_STRING(iovec[1], header_time);
 170                 IOVEC_SET_STRING(iovec[2], s->process);
 171                 IOVEC_SET_STRING(iovec[3], header_pid);
 172                 IOVEC_SET_STRING(iovec[4], p);
 173
 174                 /* When using syslog via SOCK_STREAM separate the messages by NUL chars */
 175                 if (s->server->syslog_is_stream)
 176                         iovec[4].iov_len++;
 177
 178                 zero(msghdr);
 179                 msghdr.msg_iov = iovec;
 180                 msghdr.msg_iovlen = ELEMENTSOF(iovec);
 181                 msghdr.msg_control = &control;
 182                 msghdr.msg_controllen = control.cmsghdr.cmsg_len;
 183
 184                 for (;;) {
 185                         ssize_t n;
 186
 187                         if ((n = sendmsg(s->server->syslog_fd, &msghdr, MSG_NOSIGNAL)) < 0) {
 188
 189                                 if (errno == ESRCH) {
 190                                         pid_t our_pid;
 191
 192                                         /* Hmm, maybe the process this
 193                                          * line originates from is
 194                                          * dead? Then let's patch in
 195                                          * our own pid and retry,
 196                                          * since we have nothing
 197                                          * better */
 198
 199                                         our_pid = getpid();
 200
 201                                         if (ucred->pid != our_pid) {
 202                                                 ucred->pid = our_pid;
 203                                                 continue;
 204                                         }
 205                                 }
 206
 207                                 return -errno;
 208                         }
 209
 210                         if (!s->server->syslog_is_stream ||
 211                             (size_t) n >= IOVEC_TOTAL_SIZE(iovec, ELEMENTSOF(iovec)))
 212                                 break;
 213
 214                         IOVEC_INCREMENT(iovec, ELEMENTSOF(iovec), n);
 215                 }
 216
 217         } else if (s->target == STREAM_KMSG) {
 218                 IOVEC_SET_STRING(iovec[1], s->process);
 219                 IOVEC_SET_STRING(iovec[2], header_pid);
 220                 IOVEC_SET_STRING(iovec[3], p);
 221                 IOVEC_SET_STRING(iovec[4], (char*) "\n");
 222
 223                 if (writev(s->server->kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
 224                         return -errno;
 225         } else
 226                 assert_not_reached("Unknown log target");
 227
 228         if (s->tee_console) {
 229                 int console;
 230
 231                 if ((console = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC)) >= 0) {
 232                         IOVEC_SET_STRING(iovec[0], s->process);
 233                         IOVEC_SET_STRING(iovec[1], header_pid);
 234                         IOVEC_SET_STRING(iovec[2], p);
 235                         IOVEC_SET_STRING(iovec[3], (char*) "\n");
 236
 237                         writev(console, iovec, 4);
 238                 }
 239
 240         }
 241
 242         return 0;
 243 }
 244
 245 static int stream_line(Stream *s, char *p, usec_t ts) {
 246         int r;
 247
 248         assert(s);
 249         assert(p);
 250
 251         p = strstrip(p);
 252
 253         switch (s->state) {
 254
 255         case STREAM_TARGET:
 256                 if (streq(p, "syslog") || streq(p, "syslog+console"))
 257                         s->target = STREAM_SYSLOG;
 258                 else if (streq(p, "kmsg") || streq(p, "kmsg+console")) {
 259
 260                         if (s->server->kmsg_fd >= 0 && s->uid == 0)
 261                                 s->target = STREAM_KMSG;
 262                         else {
 263                                 log_warning("/dev/kmsg logging not available.");
 264                                 return -EPERM;
 265                         }
 266                 } else {
 267                         log_warning("Failed to parse log target line.");
 268                         return -EBADMSG;
 269                 }
 270
 271                 if (endswith(p, "+console"))
 272                         s->tee_console = true;
 273
 274                 s->state = STREAM_PRIORITY;
 275                 return 0;
 276
 277         case STREAM_PRIORITY:
 278                 if ((r = safe_atoi(p, &s->priority)) < 0) {
 279                         log_warning("Failed to parse log priority line: %m");
 280                         return r;
 281                 }
 282
 283                 if (s->priority < 0) {
 284                         log_warning("Log priority negative: %m");
 285                         return -ERANGE;
 286                 }
 287
 288                 s->state = STREAM_PROCESS;
 289                 return 0;
 290
 291         case STREAM_PROCESS:
 292                 if (!(s->process = strdup(p)))
 293                         return -ENOMEM;
 294
 295                 s->state = STREAM_PREFIX;
 296                 return 0;
 297
 298         case STREAM_PREFIX:
 299
 300                 if ((r = parse_boolean(p)) < 0)
 301                         return r;
 302
 303                 s->prefix = r;
 304                 s->state = STREAM_RUNNING;
 305                 return 0;
 306
 307         case STREAM_RUNNING:
 308                 return stream_log(s, p, ts);
 309         }
 310
 311         assert_not_reached("Unknown stream state");
 312 }
 313
 314 static int stream_scan(Stream *s, usec_t ts) {
 315         char *p;
 316         size_t remaining;
 317         int r = 0;
 318
 319         assert(s);
 320
 321         p = s->buffer;
 322         remaining = s->length;
 323         for (;;) {
 324                 char *end;
 325                 size_t skip;
 326
 327                 end = memchr(p, '\n', remaining);
 328                 if (!end) {
 329                         if (remaining >= LINE_MAX) {
 330                                 end = p + LINE_MAX;
 331                                 skip = LINE_MAX;
 332                         } else
 333                                 break;
 334                 } else
 335                         skip = end - p + 1;
 336
 337                 *end = 0;
 338
 339                 r = stream_line(s, p, ts);
 340                 if (r >= 0) {
 341                         remaining -= skip;
 342                         p += skip;
 343                 }
 344         }
 345
 346         if (p > s->buffer) {
 347                 memmove(s->buffer, p, remaining);
 348                 s->length = remaining;
 349         }
 350
 351         return r;
 352 }
 353
 354 static int stream_process(Stream *s, usec_t ts) {
 355         ssize_t l;
 356         int r;
 357         assert(s);
 358
 359         l = read(s->fd, s->buffer+s->length, LINE_MAX-s->length);
 360         if (l < 0) {
 361
 362                 if (errno == EAGAIN)
 363                         return 0;
 364
 365                 log_warning("Failed to read from stream: %m");
 366                 return -errno;
 367         }
 368
 369
 370         if (l == 0)
 371                 return 0;
 372
 373         s->length += l;
 374         r = stream_scan(s, ts);
 375
 376         if (r < 0)
 377                 return r;
 378
 379         return 1;
 380 }
 381
 382 static void stream_free(Stream *s) {
 383         assert(s);
 384
 385         if (s->server) {
 386                 assert(s->server->n_streams > 0);
 387                 s->server->n_streams--;
 388                 LIST_REMOVE(Stream, stream, s->server->streams, s);
 389
 390         }
 391
 392         if (s->fd >= 0) {
 393                 if (s->server)
 394                         epoll_ctl(s->server->epoll_fd, EPOLL_CTL_DEL, s->fd, NULL);
 395
 396                 close_nointr_nofail(s->fd);
 397         }
 398
 399         free(s->process);
 400         free(s);
 401 }
 402
 403 static int stream_new(Server *s, int server_fd) {
 404         Stream *stream;
 405         int fd;
 406         struct ucred ucred;
 407         socklen_t len = sizeof(ucred);
 408         struct epoll_event ev;
 409         int r;
 410
 411         assert(s);
 412
 413         if ((fd = accept4(server_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC)) < 0)
 414                 return -errno;
 415
 416         if (s->n_streams >= STREAMS_MAX) {
 417                 log_warning("Too many connections, refusing connection.");
 418                 close_nointr_nofail(fd);
 419                 return 0;
 420         }
 421
 422         if (!socket_tcpwrap(fd, "systemd-stdout-syslog-bridge")) {
 423                 close_nointr_nofail(fd);
 424                 return 0;
 425         }
 426
 427         if (!(stream = new0(Stream, 1))) {
 428                 close_nointr_nofail(fd);
 429                 return -ENOMEM;
 430         }
 431
 432         stream->fd = fd;
 433
 434         if (getsockopt(stream->fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
 435                 r = -errno;
 436                 goto fail;
 437         }
 438
 439         if (shutdown(fd, SHUT_WR) < 0) {
 440                 r = -errno;
 441                 goto fail;
 442         }
 443
 444         zero(ev);
 445         ev.data.ptr = stream;
 446         ev.events = EPOLLIN;
 447         if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 448                 r = -errno;
 449                 goto fail;
 450         }
 451
 452         stream->pid = ucred.pid;
 453         stream->uid = ucred.uid;
 454         stream->gid = ucred.gid;
 455
 456         stream->server = s;
 457         LIST_PREPEND(Stream, stream, s->streams, stream);
 458         s->n_streams ++;
 459
 460         return 0;
 461
 462 fail:
 463         stream_free(stream);
 464         return r;
 465 }
 466
 467 static void server_done(Server *s) {
 468         unsigned i;
 469         assert(s);
 470
 471         while (s->streams)
 472                 stream_free(s->streams);
 473
 474         for (i = 0; i < s->n_server_fd; i++)
 475                 close_nointr_nofail(SD_LISTEN_FDS_START+i);
 476
 477         if (s->syslog_fd >= 0)
 478                 close_nointr_nofail(s->syslog_fd);
 479
 480         if (s->epoll_fd >= 0)
 481                 close_nointr_nofail(s->epoll_fd);
 482
 483         if (s->kmsg_fd >= 0)
 484                 close_nointr_nofail(s->kmsg_fd);
 485 }
 486
 487 static int server_init(Server *s, unsigned n_sockets) {
 488         int r;
 489         unsigned i;
 490         union {
 491                 struct sockaddr sa;
 492                 struct sockaddr_un un;
 493         } sa;
 494
 495         assert(s);
 496         assert(n_sockets > 0);
 497
 498         zero(*s);
 499
 500         s->n_server_fd = n_sockets;
 501         s->syslog_fd = -1;
 502         s->kmsg_fd = -1;
 503
 504         if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 505                 r = -errno;
 506                 log_error("Failed to create epoll object: %m");
 507                 goto fail;
 508         }
 509
 510         for (i = 0; i < n_sockets; i++) {
 511                 struct epoll_event ev;
 512                 int fd;
 513
 514                 fd = SD_LISTEN_FDS_START+i;
 515
 516                 if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_STREAM, 1)) < 0) {
 517                         log_error("Failed to determine file descriptor type: %s", strerror(-r));
 518                         goto fail;
 519                 }
 520
 521                 if (!r) {
 522                         log_error("Wrong file descriptor type.");
 523                         r = -EINVAL;
 524                         goto fail;
 525                 }
 526
 527                 /* We use ev.data.ptr instead of ev.data.fd here,
 528                  * since on 64bit archs fd is 32bit while a pointer is
 529                  * 64bit. To make sure we can easily distinguish fd
 530                  * values and pointer values we want to make sure to
 531                  * write the full field unconditionally. */
 532
 533                 zero(ev);
 534                 ev.events = EPOLLIN;
 535                 ev.data.ptr = INT_TO_PTR(fd);
 536                 if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 537                         r = -errno;
 538                         log_error("Failed to add server fd to epoll object: %m");
 539                         goto fail;
 540                 }
 541         }
 542
 543         zero(sa);
 544         sa.un.sun_family = AF_UNIX;
 545         strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
 546
 547         if ((s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 548                 r = -errno;
 549                 log_error("Failed to create log fd: %m");
 550                 goto fail;
 551         }
 552
 553         if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 554                 close_nointr_nofail(s->syslog_fd);
 555
 556                 if ((s->syslog_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) < 0) {
 557                         r = -errno;
 558                         log_error("Failed to create log fd: %m");
 559                         goto fail;
 560                 }
 561
 562                 if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 563                         r = -errno;
 564                         log_error("Failed to connect log socket to /dev/log: %m");
 565                         goto fail;
 566                 }
 567
 568                 s->syslog_is_stream = true;
 569         } else
 570                 s->syslog_is_stream = false;
 571
 572         /* /dev/kmsg logging is strictly optional */
 573         if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0)
 574                 log_warning("Failed to open /dev/kmsg for logging, disabling kernel log buffer support: %m");
 575
 576         return 0;
 577
 578 fail:
 579         server_done(s);
 580         return r;
 581 }
 582
 583 static int process_event(Server *s, struct epoll_event *ev) {
 584         int r;
 585
 586         assert(s);
 587
 588         /* Yes, this is a bit ugly, we assume that that valid pointers
 589          * are > SD_LISTEN_FDS_START+SERVER_FD_MAX. Which is certainly
 590          * true on Linux (and probably most other OSes, too, since the
 591          * first 4k usually are part of a separate null pointer
 592          * dereference page. */
 593
 594         if (PTR_TO_INT(ev->data.ptr) >= SD_LISTEN_FDS_START &&
 595             PTR_TO_INT(ev->data.ptr) < SD_LISTEN_FDS_START+(int)s->n_server_fd) {
 596
 597                 if (ev->events != EPOLLIN) {
 598                         log_info("Got invalid event from epoll. (1)");
 599                         return -EIO;
 600                 }
 601
 602                 if ((r = stream_new(s, PTR_TO_INT(ev->data.ptr))) < 0) {
 603                         log_info("Failed to accept new connection: %s", strerror(-r));
 604                         return r;
 605                 }
 606
 607         } else {
 608                 usec_t ts;
 609                 Stream *stream = ev->data.ptr;
 610
 611                 ts = now(CLOCK_REALTIME);
 612
 613                 if (!(ev->events & EPOLLIN)) {
 614                         log_info("Got invalid event from epoll. (2)");
 615                         stream_free(stream);
 616                         return 0;
 617                 }
 618
 619                 if ((r = stream_process(stream, ts)) <= 0) {
 620
 621                         if (r < 0)
 622                                 log_info("Got error on stream: %s", strerror(-r));
 623
 624                         stream_free(stream);
 625                         return 0;
 626                 }
 627         }
 628
 629         return 0;
 630 }
 631
 632 int main(int argc, char *argv[]) {
 633         Server server;
 634         int r = EXIT_FAILURE, n;
 635
 636         if (getppid() != 1) {
 637                 log_error("This program should be invoked by init only.");
 638                 return EXIT_FAILURE;
 639         }
 640
 641         if (argc > 1) {
 642                 log_error("This program does not take arguments.");
 643                 return EXIT_FAILURE;
 644         }
 645
 646         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 647         log_parse_environment();
 648         log_open();
 649
 650         umask(0022);
 651
 652         n = sd_listen_fds(true);
 653         if (n < 0) {
 654                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 655                 return EXIT_FAILURE;
 656         }
 657
 658         if (n <= 0 || n > SERVER_FD_MAX) {
 659                 log_error("No or too many file descriptors passed.");
 660                 return EXIT_FAILURE;
 661         }
 662
 663         if (server_init(&server, (unsigned) n) < 0)
 664                 return EXIT_FAILURE;
 665
 666         log_debug("systemd-stdout-syslog-bridge running as pid %lu", (unsigned long) getpid());
 667
 668         sd_notify(false,
 669                   "READY=1\n"
 670                   "STATUS=Processing requests...");
 671
 672         for (;;) {
 673                 struct epoll_event event;
 674                 int k;
 675
 676                 if ((k = epoll_wait(server.epoll_fd,
 677                                     &event, 1,
 678                                     server.n_streams <= 0 ? TIMEOUT_MSEC : -1)) < 0) {
 679
 680                         if (errno == EINTR)
 681                                 continue;
 682
 683                         log_error("epoll_wait() failed: %m");
 684                         goto fail;
 685                 }
 686
 687                 if (k <= 0)
 688                         break;
 689
 690                 if (process_event(&server, &event) < 0)
 691                         goto fail;
 692         }
 693
 694         r = EXIT_SUCCESS;
 695
 696         log_debug("systemd-stdout-syslog-bridge stopped as pid %lu", (unsigned long) getpid());
 697
 698 fail:
 699         sd_notify(false,
 700                   "STATUS=Shutting down...");
 701
 702         server_done(&server);
 703
 704         return r;
 705 }