src/logger.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
  41 #define STREAMS_MAX 4096
  42 #define SERVER_FD_MAX 16
  43 #define TIMEOUT ((int) (5*60*MSEC_PER_SEC))
  44
  45 typedef struct Stream Stream;
  46
  47 typedef struct Server {
  48         int syslog_fd;
  49         int kmsg_fd;
  50         int epoll_fd;
  51
  52         unsigned n_server_fd;
  53
  54         bool syslog_is_stream;
  55
  56         LIST_HEAD(Stream, streams);
  57         unsigned n_streams;
  58 } Server;
  59
  60 typedef enum StreamTarget {
  61         STREAM_SYSLOG,
  62         STREAM_KMSG
  63 } StreamTarget;
  64
  65 typedef enum StreamState {
  66         STREAM_TARGET,
  67         STREAM_PRIORITY,
  68         STREAM_PROCESS,
  69         STREAM_PREFIX,
  70         STREAM_RUNNING
  71 } StreamState;
  72
  73 struct Stream {
  74         Server *server;
  75
  76         StreamState state;
  77
  78         int fd;
  79
  80         StreamTarget target;
  81         int priority;
  82         char *process;
  83         pid_t pid;
  84         uid_t uid;
  85         gid_t gid;
  86
  87         bool prefix:1;
  88         bool tee_console:1;
  89
  90         char buffer[LINE_MAX];
  91         size_t length;
  92
  93         LIST_FIELDS(Stream, stream);
  94 };
  95
  96 static void parse_priority(char **p, int *priority) {
  97         int a = 0, b = 0, c = 0;
  98         int k;
  99
 100         assert(p);
 101         assert(*p);
 102         assert(priority);
 103
 104         if ((*p)[0] != '<')
 105                 return;
 106
 107         if (!strchr(*p, '>'))
 108                 return;
 109
 110         if ((*p)[2] == '>') {
 111                 c = undecchar((*p)[1]);
 112                 k = 3;
 113         } else if ((*p)[3] == '>') {
 114                 b = undecchar((*p)[1]);
 115                 c = undecchar((*p)[2]);
 116                 k = 4;
 117         } else if ((*p)[4] == '>') {
 118                 a = undecchar((*p)[1]);
 119                 b = undecchar((*p)[2]);
 120                 c = undecchar((*p)[3]);
 121                 k = 5;
 122         } else
 123                 return;
 124
 125         if (a < 0 || b < 0 || c < 0)
 126                 return;
 127
 128         *priority = a*100+b*10+c;
 129         *p += k;
 130 }
 131
 132 static int stream_log(Stream *s, char *p, usec_t ts) {
 133
 134         char header_priority[16], header_time[64], header_pid[16];
 135         struct iovec iovec[5];
 136         int priority;
 137
 138         assert(s);
 139         assert(p);
 140
 141         priority = s->priority;
 142
 143         if (s->prefix)
 144                 parse_priority(&p, &priority);
 145
 146         if (*p == 0)
 147                 return 0;
 148
 149         /* Patch in LOG_USER facility if necessary */
 150         if ((priority & LOG_FACMASK) == 0)
 151                 priority = LOG_USER | LOG_PRI(priority);
 152
 153         /*
 154          * The format glibc uses to talk to the syslog daemon is:
 155          *
 156          *     <priority>time process[pid]: msg
 157          *
 158          * The format the kernel uses is:
 159          *
 160          *     <priority>msg\n
 161          *
 162          *  We extend the latter to include the process name and pid.
 163          */
 164
 165         snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
 166         char_array_0(header_priority);
 167
 168         if (s->target == STREAM_SYSLOG) {
 169                 time_t t;
 170                 struct tm *tm;
 171
 172                 t = (time_t) (ts / USEC_PER_SEC);
 173                 if (!(tm = localtime(&t)))
 174                         return -EINVAL;
 175
 176                 if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
 177                         return -EINVAL;
 178         }
 179
 180         snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) s->pid);
 181         char_array_0(header_pid);
 182
 183         zero(iovec);
 184         IOVEC_SET_STRING(iovec[0], header_priority);
 185
 186         if (s->target == STREAM_SYSLOG) {
 187                 struct msghdr msghdr;
 188                 union {
 189                         struct cmsghdr cmsghdr;
 190                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 191                 } control;
 192                 struct ucred *ucred;
 193
 194                 zero(control);
 195                 control.cmsghdr.cmsg_level = SOL_SOCKET;
 196                 control.cmsghdr.cmsg_type = SCM_CREDENTIALS;
 197                 control.cmsghdr.cmsg_len = CMSG_LEN(sizeof(struct ucred));
 198
 199                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 200                 ucred->pid = s->pid;
 201                 ucred->uid = s->uid;
 202                 ucred->gid = s->gid;
 203
 204                 IOVEC_SET_STRING(iovec[1], header_time);
 205                 IOVEC_SET_STRING(iovec[2], s->process);
 206                 IOVEC_SET_STRING(iovec[3], header_pid);
 207                 IOVEC_SET_STRING(iovec[4], p);
 208
 209                 /* When using syslog via SOCK_STREAM separate the messages by NUL chars */
 210                 if (s->server->syslog_is_stream)
 211                         iovec[4].iov_len++;
 212
 213                 zero(msghdr);
 214                 msghdr.msg_iov = iovec;
 215                 msghdr.msg_iovlen = ELEMENTSOF(iovec);
 216                 msghdr.msg_control = &control;
 217                 msghdr.msg_controllen = control.cmsghdr.cmsg_len;
 218
 219                 for (;;) {
 220                         ssize_t n;
 221
 222                         if ((n = sendmsg(s->server->syslog_fd, &msghdr, MSG_NOSIGNAL)) < 0) {
 223
 224                                 if (errno == ESRCH) {
 225                                         pid_t our_pid;
 226
 227                                         /* Hmm, maybe the process this
 228                                          * line originates from is
 229                                          * dead? Then let's patch in
 230                                          * our own pid and retry,
 231                                          * since we have nothing
 232                                          * better */
 233
 234                                         our_pid = getpid();
 235
 236                                         if (ucred->pid != our_pid) {
 237                                                 ucred->pid = our_pid;
 238                                                 continue;
 239                                         }
 240                                 }
 241
 242                                 return -errno;
 243                         }
 244
 245                         if (!s->server->syslog_is_stream ||
 246                             (size_t) n >= IOVEC_TOTAL_SIZE(iovec, ELEMENTSOF(iovec)))
 247                                 break;
 248
 249                         IOVEC_INCREMENT(iovec, ELEMENTSOF(iovec), n);
 250                 }
 251
 252         } else if (s->target == STREAM_KMSG) {
 253                 IOVEC_SET_STRING(iovec[1], s->process);
 254                 IOVEC_SET_STRING(iovec[2], header_pid);
 255                 IOVEC_SET_STRING(iovec[3], p);
 256                 IOVEC_SET_STRING(iovec[4], (char*) "\n");
 257
 258                 if (writev(s->server->kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
 259                         return -errno;
 260         } else
 261                 assert_not_reached("Unknown log target");
 262
 263         if (s->tee_console) {
 264                 int console;
 265
 266                 if ((console = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC)) >= 0) {
 267                         IOVEC_SET_STRING(iovec[0], s->process);
 268                         IOVEC_SET_STRING(iovec[1], header_pid);
 269                         IOVEC_SET_STRING(iovec[2], p);
 270                         IOVEC_SET_STRING(iovec[3], (char*) "\n");
 271
 272                         writev(console, iovec, 4);
 273                 }
 274
 275         }
 276
 277         return 0;
 278 }
 279
 280 static int stream_line(Stream *s, char *p, usec_t ts) {
 281         int r;
 282
 283         assert(s);
 284         assert(p);
 285
 286         p = strstrip(p);
 287
 288         switch (s->state) {
 289
 290         case STREAM_TARGET:
 291                 if (streq(p, "syslog") || streq(p, "syslog+console"))
 292                         s->target = STREAM_SYSLOG;
 293                 else if (streq(p, "kmsg") || streq(p, "kmsg+console")) {
 294
 295                         if (s->server->kmsg_fd >= 0 && s->uid == 0)
 296                                 s->target = STREAM_KMSG;
 297                         else {
 298                                 log_warning("/dev/kmsg logging not available.");
 299                                 return -EPERM;
 300                         }
 301                 } else {
 302                         log_warning("Failed to parse log target line.");
 303                         return -EBADMSG;
 304                 }
 305
 306                 if (endswith(p, "+console"))
 307                         s->tee_console = true;
 308
 309                 s->state = STREAM_PRIORITY;
 310                 return 0;
 311
 312         case STREAM_PRIORITY:
 313                 if ((r = safe_atoi(p, &s->priority)) < 0) {
 314                         log_warning("Failed to parse log priority line: %m");
 315                         return r;
 316                 }
 317
 318                 if (s->priority < 0) {
 319                         log_warning("Log priority negative: %m");
 320                         return -ERANGE;
 321                 }
 322
 323                 s->state = STREAM_PROCESS;
 324                 return 0;
 325
 326         case STREAM_PROCESS:
 327                 if (!(s->process = strdup(p)))
 328                         return -ENOMEM;
 329
 330                 s->state = STREAM_PREFIX;
 331                 return 0;
 332
 333         case STREAM_PREFIX:
 334
 335                 if ((r = parse_boolean(p)) < 0)
 336                         return r;
 337
 338                 s->prefix = r;
 339                 s->state = STREAM_RUNNING;
 340                 return 0;
 341
 342         case STREAM_RUNNING:
 343                 return stream_log(s, p, ts);
 344         }
 345
 346         assert_not_reached("Unknown stream state");
 347 }
 348
 349 static int stream_scan(Stream *s, usec_t ts) {
 350         char *p;
 351         size_t remaining;
 352         int r = 0;
 353
 354         assert(s);
 355
 356         p = s->buffer;
 357         remaining = s->length;
 358         for (;;) {
 359                 char *newline;
 360
 361                 if (!(newline = memchr(p, '\n', remaining)))
 362                         break;
 363
 364                 *newline = 0;
 365
 366                 if ((r = stream_line(s, p, ts)) >= 0) {
 367                         remaining -= newline-p+1;
 368                         p = newline+1;
 369                 }
 370         }
 371
 372         if (p > s->buffer) {
 373                 memmove(s->buffer, p, remaining);
 374                 s->length = remaining;
 375         }
 376
 377         return r;
 378 }
 379
 380 static int stream_process(Stream *s, usec_t ts) {
 381         ssize_t l;
 382         int r;
 383         assert(s);
 384
 385         if ((l = read(s->fd, s->buffer+s->length, LINE_MAX-s->length)) < 0) {
 386
 387                 if (errno == EAGAIN)
 388                         return 0;
 389
 390                 log_warning("Failed to read from stream: %m");
 391                 return -errno;
 392         }
 393
 394
 395         if (l == 0)
 396                 return 0;
 397
 398         s->length += l;
 399         r = stream_scan(s, ts);
 400
 401         if (r < 0)
 402                 return r;
 403
 404         return 1;
 405 }
 406
 407 static void stream_free(Stream *s) {
 408         assert(s);
 409
 410         if (s->server) {
 411                 assert(s->server->n_streams > 0);
 412                 s->server->n_streams--;
 413                 LIST_REMOVE(Stream, stream, s->server->streams, s);
 414
 415         }
 416
 417         if (s->fd >= 0) {
 418                 if (s->server)
 419                         epoll_ctl(s->server->epoll_fd, EPOLL_CTL_DEL, s->fd, NULL);
 420
 421                 close_nointr_nofail(s->fd);
 422         }
 423
 424         free(s->process);
 425         free(s);
 426 }
 427
 428 static int stream_new(Server *s, int server_fd) {
 429         Stream *stream;
 430         int fd;
 431         struct ucred ucred;
 432         socklen_t len = sizeof(ucred);
 433         struct epoll_event ev;
 434         int r;
 435
 436         assert(s);
 437
 438         if ((fd = accept4(server_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC)) < 0)
 439                 return -errno;
 440
 441         if (s->n_streams >= STREAMS_MAX) {
 442                 log_warning("Too many connections, refusing connection.");
 443                 close_nointr_nofail(fd);
 444                 return 0;
 445         }
 446
 447         if (!socket_tcpwrap(fd, "systemd-logger")) {
 448                 close_nointr_nofail(fd);
 449                 return 0;
 450         }
 451
 452         if (!(stream = new0(Stream, 1))) {
 453                 close_nointr_nofail(fd);
 454                 return -ENOMEM;
 455         }
 456
 457         stream->fd = fd;
 458
 459         if (getsockopt(stream->fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
 460                 r = -errno;
 461                 goto fail;
 462         }
 463
 464         if (shutdown(fd, SHUT_WR) < 0) {
 465                 r = -errno;
 466                 goto fail;
 467         }
 468
 469         zero(ev);
 470         ev.data.ptr = stream;
 471         ev.events = EPOLLIN;
 472         if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 473                 r = -errno;
 474                 goto fail;
 475         }
 476
 477         stream->pid = ucred.pid;
 478         stream->uid = ucred.uid;
 479         stream->gid = ucred.gid;
 480
 481         stream->server = s;
 482         LIST_PREPEND(Stream, stream, s->streams, stream);
 483         s->n_streams ++;
 484
 485         return 0;
 486
 487 fail:
 488         stream_free(stream);
 489         return r;
 490 }
 491
 492 static void server_done(Server *s) {
 493         unsigned i;
 494         assert(s);
 495
 496         while (s->streams)
 497                 stream_free(s->streams);
 498
 499         for (i = 0; i < s->n_server_fd; i++)
 500                 close_nointr_nofail(SD_LISTEN_FDS_START+i);
 501
 502         if (s->syslog_fd >= 0)
 503                 close_nointr_nofail(s->syslog_fd);
 504
 505         if (s->epoll_fd >= 0)
 506                 close_nointr_nofail(s->epoll_fd);
 507
 508         if (s->kmsg_fd >= 0)
 509                 close_nointr_nofail(s->kmsg_fd);
 510 }
 511
 512 static int server_init(Server *s, unsigned n_sockets) {
 513         int r;
 514         unsigned i;
 515         union {
 516                 struct sockaddr sa;
 517                 struct sockaddr_un un;
 518         } sa;
 519
 520         assert(s);
 521         assert(n_sockets > 0);
 522
 523         zero(*s);
 524
 525         s->n_server_fd = n_sockets;
 526         s->syslog_fd = -1;
 527         s->kmsg_fd = -1;
 528
 529         if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 530                 r = -errno;
 531                 log_error("Failed to create epoll object: %m");
 532                 goto fail;
 533         }
 534
 535         for (i = 0; i < n_sockets; i++) {
 536                 struct epoll_event ev;
 537                 int fd;
 538
 539                 fd = SD_LISTEN_FDS_START+i;
 540
 541                 if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_STREAM, 1)) < 0) {
 542                         log_error("Failed to determine file descriptor type: %s", strerror(-r));
 543                         goto fail;
 544                 }
 545
 546                 if (!r) {
 547                         log_error("Wrong file descriptor type.");
 548                         r = -EINVAL;
 549                         goto fail;
 550                 }
 551
 552                 /* We use ev.data.ptr instead of ev.data.fd here,
 553                  * since on 64bit archs fd is 32bit while a pointer is
 554                  * 64bit. To make sure we can easily distinguish fd
 555                  * values and pointer values we want to make sure to
 556                  * write the full field unconditionally. */
 557
 558                 zero(ev);
 559                 ev.events = EPOLLIN;
 560                 ev.data.ptr = INT_TO_PTR(fd);
 561                 if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
 562                         r = -errno;
 563                         log_error("Failed to add server fd to epoll object: %m");
 564                         goto fail;
 565                 }
 566         }
 567
 568         zero(sa);
 569         sa.un.sun_family = AF_UNIX;
 570         strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
 571
 572         if ((s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 573                 r = -errno;
 574                 log_error("Failed to create log fd: %m");
 575                 goto fail;
 576         }
 577
 578         if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 579                 close_nointr_nofail(s->syslog_fd);
 580
 581                 if ((s->syslog_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) < 0) {
 582                         r = -errno;
 583                         log_error("Failed to create log fd: %m");
 584                         goto fail;
 585                 }
 586
 587                 if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
 588                         r = -errno;
 589                         log_error("Failed to connect log socket to /dev/log: %m");
 590                         goto fail;
 591                 }
 592
 593                 s->syslog_is_stream = true;
 594         } else
 595                 s->syslog_is_stream = false;
 596
 597         /* /dev/kmsg logging is strictly optional */
 598         if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0)
 599                 log_warning("Failed to open /dev/kmsg for logging, disabling kernel log buffer support: %m");
 600
 601         return 0;
 602
 603 fail:
 604         server_done(s);
 605         return r;
 606 }
 607
 608 static int process_event(Server *s, struct epoll_event *ev) {
 609         int r;
 610
 611         assert(s);
 612
 613         /* Yes, this is a bit ugly, we assume that that valid pointers
 614          * are > SD_LISTEN_FDS_START+SERVER_FD_MAX. Which is certainly
 615          * true on Linux (and probably most other OSes, too, since the
 616          * first 4k usually are part of a separate null pointer
 617          * dereference page. */
 618
 619         if (PTR_TO_INT(ev->data.ptr) >= SD_LISTEN_FDS_START &&
 620             PTR_TO_INT(ev->data.ptr) < SD_LISTEN_FDS_START+(int)s->n_server_fd) {
 621
 622                 if (ev->events != EPOLLIN) {
 623                         log_info("Got invalid event from epoll. (1)");
 624                         return -EIO;
 625                 }
 626
 627                 if ((r = stream_new(s, PTR_TO_INT(ev->data.ptr))) < 0) {
 628                         log_info("Failed to accept new connection: %s", strerror(-r));
 629                         return r;
 630                 }
 631
 632         } else {
 633                 usec_t ts;
 634                 Stream *stream = ev->data.ptr;
 635
 636                 ts = now(CLOCK_REALTIME);
 637
 638                 if (!(ev->events & EPOLLIN)) {
 639                         log_info("Got invalid event from epoll. (2)");
 640                         stream_free(stream);
 641                         return 0;
 642                 }
 643
 644                 if ((r = stream_process(stream, ts)) <= 0) {
 645
 646                         if (r < 0)
 647                                 log_info("Got error on stream: %s", strerror(-r));
 648
 649                         stream_free(stream);
 650                         return 0;
 651                 }
 652         }
 653
 654         return 0;
 655 }
 656
 657 int main(int argc, char *argv[]) {
 658         Server server;
 659         int r = EXIT_FAILURE, n;
 660
 661         if (getppid() != 1) {
 662                 log_error("This program should be invoked by init only.");
 663                 return EXIT_FAILURE;
 664         }
 665
 666         if (argc > 1) {
 667                 log_error("This program does not take arguments.");
 668                 return EXIT_FAILURE;
 669         }
 670
 671         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 672         log_parse_environment();
 673         log_open();
 674
 675         if ((n = sd_listen_fds(true)) < 0) {
 676                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 677                 return EXIT_FAILURE;
 678         }
 679
 680         if (n <= 0 || n > SERVER_FD_MAX) {
 681                 log_error("No or too many file descriptors passed.");
 682                 return EXIT_FAILURE;
 683         }
 684
 685         if (server_init(&server, (unsigned) n) < 0)
 686                 return EXIT_FAILURE;
 687
 688         log_debug("systemd-logger running as pid %lu", (unsigned long) getpid());
 689
 690         sd_notify(false,
 691                   "READY=1\n"
 692                   "STATUS=Processing requests...");
 693
 694         for (;;) {
 695                 struct epoll_event event;
 696                 int k;
 697
 698                 if ((k = epoll_wait(server.epoll_fd,
 699                                     &event, 1,
 700                                     server.n_streams <= 0 ? TIMEOUT : -1)) < 0) {
 701
 702                         if (errno == EINTR)
 703                                 continue;
 704
 705                         log_error("epoll_wait() failed: %m");
 706                         goto fail;
 707                 }
 708
 709                 if (k <= 0)
 710                         break;
 711
 712                 if (process_event(&server, &event) < 0)
 713                         goto fail;
 714         }
 715
 716         r = EXIT_SUCCESS;
 717
 718         log_debug("systemd-logger stopped as pid %lu", (unsigned long) getpid());
 719
 720 fail:
 721         sd_notify(false,
 722                   "STATUS=Shutting down...");
 723
 724         server_done(&server);
 725
 726         return r;
 727 }