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