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 <systemd/sd-daemon.h>
  36
  37 #include "util.h"
  38 #include "log.h"
  39 #include "list.h"
  40 #include "tcpwrap.h"
  41 #include "def.h"
  42
  43 #define STREAMS_MAX 4096
  44 #define SERVER_FD_MAX 16
  45 #define TIMEOUT_MSEC ((int) (DEFAULT_EXIT_USEC/USEC_PER_MSEC))
  46
  47 typedef struct Stream Stream;
  48
  49 typedef struct Server {
  50         int syslog_fd;
  51         int kmsg_fd;
  52         int epoll_fd;
  53
  54         unsigned n_server_fd;
  55
  56         bool syslog_is_stream;
  57
  58         LIST_HEAD(Stream, streams);
  59         unsigned n_streams;
  60 } Server;
  61
  62 typedef enum StreamTarget {
  63         STREAM_SYSLOG,
  64         STREAM_KMSG
  65 } StreamTarget;
  66
  67 typedef enum StreamState {
  68         STREAM_TARGET,
  69         STREAM_PRIORITY,
  70         STREAM_PROCESS,
  71         STREAM_PREFIX,
  72         STREAM_RUNNING
  73 } StreamState;
  74
  75 struct Stream {
  76         Server *server;
  77
  78         StreamState state;
  79
  80         int fd;
  81
  82         StreamTarget target;
  83         int priority;
  84         char *process;
  85         pid_t pid;
  86         uid_t uid;
  87         gid_t gid;
  88
  89         bool prefix:1;
  90         bool tee_console:1;
  91
  92         char buffer[LINE_MAX+1];
  93         size_t length;
  94
  95         LIST_FIELDS(Stream, stream);
  96 };
  97
  98 static int stream_log(Stream *s, char *p, usec_t ts) {
  99
 100         char header_priority[16], header_time[64], header_pid[16];
 101         struct iovec iovec[5];
 102         int priority;
 103
 104         assert(s);
 105         assert(p);
 106
 107         priority = s->priority;
 108
 109         if (s->prefix)
 110                 parse_syslog_priority(&p, &priority);
 111
 112         if (*p == 0)
 113                 return 0;
 114
 115         /* Patch in configured facility if necessary */
 116         if ((priority & LOG_FACMASK) == 0)
 117                 priority = (s->priority & LOG_FACMASK) | priority;
 118
 119         /*
 120          * The format glibc uses to talk to the syslog daemon is:
 121          *
 122          *     <priority>time process[pid]: msg
 123          *
 124          * The format the kernel uses is:
 125          *
 126          *     <priority>msg\n
 127          *
 128          *  We extend the latter to include the process name and pid.
 129          */
 130
 131         snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
 132         char_array_0(header_priority);
 133
 134         if (s->target == STREAM_SYSLOG) {
 135                 time_t t;
 136                 struct tm *tm;
 137
 138                 t = (time_t) (ts / USEC_PER_SEC);
 139                 if (!(tm = localtime(&t)))
 140                         return -EINVAL;
 141
 142                 if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
 143                         return -EINVAL;
 144         }
 145
 146         snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) s->pid);
 147         char_array_0(header_pid);
 148
 149         zero(iovec);
 150         IOVEC_SET_STRING(iovec[0], header_priority);
 151
 152         if (s->target == STREAM_SYSLOG) {
 153                 struct msghdr msghdr;
 154                 union {
 155                         struct cmsghdr cmsghdr;
 156                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 157                 } control;
 158                 struct ucred *ucred;
 159
 160                 zero(control);
 161                 control.cmsghdr.cmsg_level = SOL_SOCKET;
 162                 control.cmsghdr.cmsg_type = SCM_CREDENTIALS;
 163                 control.cmsghdr.cmsg_len = CMSG_LEN(sizeof(struct ucred));
 164
 165                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 166                 ucred->pid = s->pid;
 167                 ucred->uid = s->uid;
 168                 ucred->gid = s->gid;
 169
 170                 IOVEC_SET_STRING(iovec[1], header_time);
 171                 IOVEC_SET_STRING(iovec[2], s->process);
 172                 IOVEC_SET_STRING(iovec[3], header_pid);
 173                 IOVEC_SET_STRING(iovec[4], p);
 174
 175                 /* When using syslog via SOCK_STREAM separate the messages by NUL chars */
 176                 if (s->server->syslog_is_stream)
 177                         iovec[4].iov_len++;
 178
 179                 zero(msghdr);
 180                 msghdr.msg_iov = iovec;
 181                 msghdr.msg_iovlen = ELEMENTSOF(iovec);
 182                 msghdr.msg_control = &control;
 183                 msghdr.msg_controllen = control.cmsghdr.cmsg_len;
 184
 185                 for (;;) {
 186                         ssize_t n;
 187
 188                         if ((n = sendmsg(s->server->syslog_fd, &msghdr, MSG_NOSIGNAL)) < 0) {
 189
 190                                 if (errno == ESRCH) {
 191                                         pid_t our_pid;
 192
 193                                         /* Hmm, maybe the process this
 194                                          * line originates from is
 195                                          * dead? Then let's patch in
 196                                          * our own pid and retry,
 197                                          * since we have nothing
 198                                          * better */
 199
 200                                         our_pid = getpid();
 201
 202                                         if (ucred->pid != our_pid) {
 203                                                 ucred->pid = our_pid;
 204                                                 continue;
 205                                         }
 206                                 }
 207
 208                                 return -errno;
 209                         }
 210
 211                         if (!s->server->syslog_is_stream ||
 212                             (size_t) n >= IOVEC_TOTAL_SIZE(iovec, ELEMENTSOF(iovec)))
 213                                 break;
 214
 215                         IOVEC_INCREMENT(iovec, ELEMENTSOF(iovec), n);
 216                 }
 217
 218         } else if (s->target == STREAM_KMSG) {
 219                 IOVEC_SET_STRING(iovec[1], s->process);
 220                 IOVEC_SET_STRING(iovec[2], header_pid);
 221                 IOVEC_SET_STRING(iovec[3], p);
 222                 IOVEC_SET_STRING(iovec[4], (char*) "\n");
 223
 224                 if (writev(s->server->kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
 225                         return -errno;
 226         } else
 227                 assert_not_reached("Unknown log target");
 228
 229         if (s->tee_console) {
 230                 int console;
 231
 232                 if ((console = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC)) >= 0) {
 233                         IOVEC_SET_STRING(iovec[0], s->process);
 234                         IOVEC_SET_STRING(iovec[1], header_pid);
 235                         IOVEC_SET_STRING(iovec[2], p);
 236                         IOVEC_SET_STRING(iovec[3], (char*) "\n");
 237
 238                         writev(console, iovec, 4);
 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         if (l == 0)
 370                 return 0;
 371
 372         s->length += l;
 373         r = stream_scan(s, ts);
 374
 375         if (r < 0)
 376                 return r;
 377
 378         return 1;
 379 }
 380
 381 static void stream_free(Stream *s) {
 382         assert(s);
 383
 384         if (s->server) {
 385                 assert(s->server->n_streams > 0);
 386                 s->server->n_streams--;
 387                 LIST_REMOVE(Stream, stream, s->server->streams, s);
 388
 389         }
 390
 391         if (s->fd >= 0) {
 392                 if (s->server)
 393                         epoll_ctl(s->server->epoll_fd, EPOLL_CTL_DEL, s->fd, NULL);
 394
 395                 close_nointr_nofail(s->fd);
 396         }
 397
 398         free(s->process);
 399         free(s);
 400 }
 401
 402 static int stream_new(Server *s, int server_fd) {
 403         Stream *stream;
 404         int fd;
 405         struct ucred ucred;
 406         socklen_t len = sizeof(ucred);
 407         struct epoll_event ev;
 408         int r;
 409
 410         assert(s);
 411         assert(server_fd >= 0);
 412
 413         fd = accept4(server_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
 414         if (fd < 0)
 415                 return -errno;
 416
 417         if (s->n_streams >= STREAMS_MAX) {
 418                 log_warning("Too many connections, refusing connection.");
 419                 close_nointr_nofail(fd);
 420                 return 0;
 421         }
 422
 423         if (!socket_tcpwrap(fd, "systemd-stdout-syslog-bridge")) {
 424                 close_nointr_nofail(fd);
 425                 return 0;
 426         }
 427
 428         if (!(stream = new0(Stream, 1))) {
 429                 close_nointr_nofail(fd);
 430                 return -ENOMEM;
 431         }
 432
 433         stream->fd = fd;
 434
 435         if (getsockopt(stream->fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
 436                 r = -errno;
 437                 goto fail;
 438         }
 439
 440         if (shutdown(fd, SHUT_WR) < 0) {
 441                 r = -errno;
 442                 goto fail;
 443         }
 444
 445         zero(ev);
 446         ev.data.ptr = stream;
 447         ev.events = EPOLLIN;
 448         if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 449                 r = -errno;
 450                 goto fail;
 451         }
 452
 453         stream->pid = ucred.pid;
 454         stream->uid = ucred.uid;
 455         stream->gid = ucred.gid;
 456
 457         stream->server = s;
 458         LIST_PREPEND(Stream, stream, s->streams, stream);
 459         s->n_streams ++;
 460
 461         return 0;
 462
 463 fail:
 464         stream_free(stream);
 465         return r;
 466 }
 467
 468 static void server_done(Server *s) {
 469         unsigned i;
 470         assert(s);
 471
 472         while (s->streams)
 473                 stream_free(s->streams);
 474
 475         for (i = 0; i < s->n_server_fd; i++)
 476                 close_nointr_nofail(SD_LISTEN_FDS_START+i);
 477
 478         if (s->syslog_fd >= 0)
 479                 close_nointr_nofail(s->syslog_fd);
 480
 481         if (s->epoll_fd >= 0)
 482                 close_nointr_nofail(s->epoll_fd);
 483
 484         if (s->kmsg_fd >= 0)
 485                 close_nointr_nofail(s->kmsg_fd);
 486 }
 487
 488 static int server_init(Server *s, unsigned n_sockets) {
 489         int r;
 490         unsigned i;
 491         union {
 492                 struct sockaddr sa;
 493                 struct sockaddr_un un;
 494         } sa;
 495
 496         assert(s);
 497         assert(n_sockets > 0);
 498
 499         zero(*s);
 500
 501         s->n_server_fd = n_sockets;
 502         s->syslog_fd = -1;
 503         s->kmsg_fd = -1;
 504
 505         if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 506                 r = -errno;
 507                 log_error("Failed to create epoll object: %m");
 508                 goto fail;
 509         }
 510
 511         for (i = 0; i < n_sockets; i++) {
 512                 struct epoll_event ev;
 513                 int fd;
 514
 515                 fd = SD_LISTEN_FDS_START+i;
 516
 517                 if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_STREAM, 1)) < 0) {
 518                         log_error("Failed to determine file descriptor type: %s", strerror(-r));
 519                         goto fail;
 520                 }
 521
 522                 if (!r) {
 523                         log_error("Wrong file descriptor type.");
 524                         r = -EINVAL;
 525                         goto fail;
 526                 }
 527
 528                 /* We use ev.data.ptr instead of ev.data.fd here,
 529                  * since on 64bit archs fd is 32bit while a pointer is
 530                  * 64bit. To make sure we can easily distinguish fd
 531                  * values and pointer values we want to make sure to
 532                  * write the full field unconditionally. */
 533
 534                 zero(ev);
 535                 ev.events = EPOLLIN;
 536                 ev.data.ptr = INT_TO_PTR(fd);
 537                 if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 538                         r = -errno;
 539                         log_error("Failed to add server fd to epoll object: %m");
 540                         goto fail;
 541                 }
 542         }
 543
 544         zero(sa);
 545         sa.un.sun_family = AF_UNIX;
 546         strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
 547
 548         if ((s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 549                 r = -errno;
 550                 log_error("Failed to create log fd: %m");
 551                 goto fail;
 552         }
 553
 554         if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 555                 close_nointr_nofail(s->syslog_fd);
 556
 557                 if ((s->syslog_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) < 0) {
 558                         r = -errno;
 559                         log_error("Failed to create log fd: %m");
 560                         goto fail;
 561                 }
 562
 563                 if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 564                         r = -errno;
 565                         log_error("Failed to connect log socket to /dev/log: %m");
 566                         goto fail;
 567                 }
 568
 569                 s->syslog_is_stream = true;
 570         } else
 571                 s->syslog_is_stream = false;
 572
 573         /* /dev/kmsg logging is strictly optional */
 574         if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0)
 575                 log_warning("Failed to open /dev/kmsg for logging, disabling kernel log buffer support: %m");
 576
 577         return 0;
 578
 579 fail:
 580         server_done(s);
 581         return r;
 582 }
 583
 584 static int process_event(Server *s, struct epoll_event *ev) {
 585         int r;
 586
 587         assert(s);
 588
 589         /* Yes, this is a bit ugly, we assume that that valid pointers
 590          * are > SD_LISTEN_FDS_START+SERVER_FD_MAX. Which is certainly
 591          * true on Linux (and probably most other OSes, too, since the
 592          * first 4k usually are part of a separate null pointer
 593          * dereference page. */
 594
 595         if (PTR_TO_INT(ev->data.ptr) >= SD_LISTEN_FDS_START &&
 596             PTR_TO_INT(ev->data.ptr) < SD_LISTEN_FDS_START+(int)s->n_server_fd) {
 597
 598                 if (ev->events != EPOLLIN) {
 599                         log_info("Got invalid event from epoll. (1)");
 600                         return -EIO;
 601                 }
 602
 603                 if ((r = stream_new(s, PTR_TO_INT(ev->data.ptr))) < 0) {
 604                         log_info("Failed to accept new connection: %s", strerror(-r));
 605                         return r;
 606                 }
 607
 608         } else {
 609                 usec_t ts;
 610                 Stream *stream = ev->data.ptr;
 611
 612                 ts = now(CLOCK_REALTIME);
 613
 614                 if (!(ev->events & EPOLLIN)) {
 615                         log_info("Got invalid event from epoll. (2)");
 616                         stream_free(stream);
 617                         return 0;
 618                 }
 619
 620                 if ((r = stream_process(stream, ts)) <= 0) {
 621
 622                         if (r < 0)
 623                                 log_info("Got error on stream: %s", strerror(-r));
 624
 625                         stream_free(stream);
 626                         return 0;
 627                 }
 628         }
 629
 630         return 0;
 631 }
 632
 633 int main(int argc, char *argv[]) {
 634         Server server;
 635         int r = EXIT_FAILURE, n;
 636
 637         if (getppid() != 1) {
 638                 log_error("This program should be invoked by init only.");
 639                 return EXIT_FAILURE;
 640         }
 641
 642         if (argc > 1) {
 643                 log_error("This program does not take arguments.");
 644                 return EXIT_FAILURE;
 645         }
 646
 647         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 648         log_parse_environment();
 649         log_open();
 650
 651         umask(0022);
 652
 653         n = sd_listen_fds(true);
 654         if (n < 0) {
 655                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 656                 return EXIT_FAILURE;
 657         }
 658
 659         if (n <= 0 || n > SERVER_FD_MAX) {
 660                 log_error("No or too many file descriptors passed.");
 661                 return EXIT_FAILURE;
 662         }
 663
 664         if (server_init(&server, (unsigned) n) < 0)
 665                 return EXIT_FAILURE;
 666
 667         log_debug("systemd-stdout-syslog-bridge running as pid %lu", (unsigned long) getpid());
 668
 669         sd_notify(false,
 670                   "READY=1\n"
 671                   "STATUS=Processing requests...");
 672
 673         for (;;) {
 674                 struct epoll_event event;
 675                 int k;
 676
 677                 if ((k = epoll_wait(server.epoll_fd,
 678                                     &event, 1,
 679                                     server.n_streams <= 0 ? TIMEOUT_MSEC : -1)) < 0) {
 680
 681                         if (errno == EINTR)
 682                                 continue;
 683
 684                         log_error("epoll_wait() failed: %m");
 685                         goto fail;
 686                 }
 687
 688                 if (k <= 0)
 689                         break;
 690
 691                 if (process_event(&server, &event) < 0)
 692                         goto fail;
 693         }
 694
 695         r = EXIT_SUCCESS;
 696
 697         log_debug("systemd-stdout-syslog-bridge stopped as pid %lu", (unsigned long) getpid());
 698
 699 fail:
 700         sd_notify(false,
 701                   "STATUS=Shutting down...");
 702
 703         server_done(&server);
 704
 705         return r;
 706 }