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