sysklogd/syslogd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini syslogd implementation for busybox
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
   8  *
   9  * "circular buffer" Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>
  10  *
  11  * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
  12  *
  13  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  14  */
  15
  16 #include "busybox.h"
  17 #include <paths.h>
  18 #include <sys/un.h>
  19
  20 /* SYSLOG_NAMES defined to pull some extra junk from syslog.h */
  21 #define SYSLOG_NAMES
  22 #include <sys/syslog.h>
  23 #include <sys/uio.h>
  24
  25 /* Path to the unix socket */
  26 static char dev_log_name[MAXPATHLEN];
  27
  28 /* Path for the file where all log messages are written */
  29 static const char *logFilePath = "/var/log/messages";
  30
  31 #if ENABLE_FEATURE_ROTATE_LOGFILE
  32 /* max size of message file before being rotated */
  33 static int logFileSize = 200 * 1024;
  34 /* number of rotated message files */
  35 static int logFileRotate = 1;
  36 #endif
  37
  38 /* interval between marks in seconds */
  39 static int markInterval = 20 * 60;
  40
  41 /* level of messages to be locally logged */
  42 static int logLevel = 8;
  43
  44 /* localhost's name */
  45 static char localHostName[64];
  46
  47 #if ENABLE_FEATURE_REMOTE_LOG
  48 #include <netinet/in.h>
  49 /* udp socket for logging to remote host */
  50 static int remoteFD = -1;
  51 static struct sockaddr_in remoteAddr;
  52 #endif
  53
  54
  55 /* NB: we may need 2x this amount on stack... */
  56 enum { MAX_READ = 1024 };
  57
  58
  59 /* options */
  60 /* Correct regardless of combination of CONFIG_xxx */
  61 enum {
  62         OPTBIT_mark = 0, // -m
  63         OPTBIT_nofork, // -n
  64         OPTBIT_outfile, // -O
  65         OPTBIT_loglevel, // -l
  66         OPTBIT_small, // -S
  67         USE_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,) // -s
  68         USE_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,) // -b
  69         USE_FEATURE_REMOTE_LOG(    OPTBIT_remote     ,) // -R
  70         USE_FEATURE_REMOTE_LOG(    OPTBIT_localtoo   ,) // -L
  71         USE_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,) // -C
  72
  73         OPT_mark        = 1 << OPTBIT_mark    ,
  74         OPT_nofork      = 1 << OPTBIT_nofork  ,
  75         OPT_outfile     = 1 << OPTBIT_outfile ,
  76         OPT_loglevel    = 1 << OPTBIT_loglevel,
  77         OPT_small       = 1 << OPTBIT_small   ,
  78         OPT_filesize    = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
  79         OPT_rotatecnt   = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
  80         OPT_remotelog   = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remote     )) + 0,
  81         OPT_locallog    = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_localtoo   )) + 0,
  82         OPT_circularlog = USE_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
  83 };
  84 #define OPTION_STR "m:nO:l:S" \
  85         USE_FEATURE_ROTATE_LOGFILE("s:" ) \
  86         USE_FEATURE_ROTATE_LOGFILE("b:" ) \
  87         USE_FEATURE_REMOTE_LOG(    "R:" ) \
  88         USE_FEATURE_REMOTE_LOG(    "L"  ) \
  89         USE_FEATURE_IPC_SYSLOG(    "C::")
  90 #define OPTION_DECL *opt_m, *opt_l \
  91         USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
  92         USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
  93         USE_FEATURE_REMOTE_LOG(    ,*opt_R) \
  94         USE_FEATURE_IPC_SYSLOG(    ,*opt_C = NULL)
  95 #define OPTION_PARAM &opt_m, &logFilePath, &opt_l \
  96         USE_FEATURE_ROTATE_LOGFILE(,&opt_s) \
  97         USE_FEATURE_ROTATE_LOGFILE(,&opt_b) \
  98         USE_FEATURE_REMOTE_LOG(    ,&opt_R) \
  99         USE_FEATURE_IPC_SYSLOG(    ,&opt_C)
 100
 101
 102 /* circular buffer variables/structures */
 103 #if ENABLE_FEATURE_IPC_SYSLOG
 104
 105
 106 #if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
 107 #error Sorry, you must set the syslogd buffer size to at least 4KB.
 108 #error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
 109 #endif
 110
 111 #include <sys/ipc.h>
 112 #include <sys/sem.h>
 113 #include <sys/shm.h>
 114
 115 /* our shared key */
 116 #define KEY_ID ((long)0x414e4547) /* "GENA" */
 117
 118 // Semaphore operation structures
 119 static struct shbuf_ds {
 120         int32_t size;   // size of data written
 121         int32_t head;   // start of message list
 122         int32_t tail;   // end of message list
 123         char data[1];   // data/messages
 124 } *shbuf;               // shared memory pointer
 125
 126 static int shmid = -1;   // ipc shared memory id
 127 static int s_semid = -1; // ipc semaphore id
 128 static int shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024);   // default shm size
 129
 130 static void ipcsyslog_cleanup(void)
 131 {
 132         if (shmid != -1) {
 133                 shmdt(shbuf);
 134         }
 135         if (shmid != -1) {
 136                 shmctl(shmid, IPC_RMID, NULL);
 137         }
 138         if (s_semid != -1) {
 139                 semctl(s_semid, 0, IPC_RMID, 0);
 140         }
 141 }
 142
 143 static void ipcsyslog_init(void)
 144 {
 145         shmid = shmget(KEY_ID, shm_size, IPC_CREAT | 1023);
 146         if (shmid == -1) {
 147                 bb_perror_msg_and_die("shmget");
 148         }
 149
 150         shbuf = shmat(shmid, NULL, 0);
 151         if (!shbuf) {
 152                 bb_perror_msg_and_die("shmat");
 153         }
 154
 155         shbuf->size = shm_size - offsetof(struct shbuf_ds, data);
 156         shbuf->head = shbuf->tail = 0;
 157
 158         // we'll trust the OS to set initial semval to 0 (let's hope)
 159         s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
 160         if (s_semid == -1) {
 161                 if (errno == EEXIST) {
 162                         s_semid = semget(KEY_ID, 2, 0);
 163                         if (s_semid != -1)
 164                                 return;
 165                 }
 166                 bb_perror_msg_and_die("semget");
 167         }
 168 }
 169
 170 /* write message to buffer */
 171 static void log_to_shmem(const char *msg, int len)
 172 {
 173         static /*const*/ struct sembuf SMwup[1] = { {1, -1, IPC_NOWAIT} };
 174         static /*const*/ struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };
 175
 176         int old_tail, new_tail;
 177         char *c;
 178
 179         if (semop(s_semid, SMwdn, 3) == -1) {
 180                 bb_perror_msg_and_die("SMwdn");
 181         }
 182
 183         /* Circular Buffer Algorithm:
 184          * --------------------------
 185          * tail == position where to store next syslog message.
 186          * head == position of next message to retrieve ("print").
 187          * if head == tail, there is no "unprinted" messages left.
 188          * head is typically advanced by separate "reader" program,
 189          * but if there isn't one, we have to do it ourself.
 190          * messages are NUL-separated.
 191          */
 192         len++; /* length with NUL included */
 193  again:
 194         old_tail = shbuf->tail;
 195         new_tail = old_tail + len;
 196         if (new_tail < shbuf->size) {
 197                 /* No need to move head if shbuf->head <= old_tail,
 198                  * else... */
 199                 if (old_tail < shbuf->head && shbuf->head <= new_tail) {
 200                         /* ...need to move head forward */
 201                         c = memchr(shbuf->data + new_tail, '\0',
 202                                            shbuf->size - new_tail);
 203                         if (!c) /* no NUL ahead of us, wrap around */
 204                                 c = memchr(shbuf->data, '\0', old_tail);
 205                         if (!c) { /* still nothing? point to this msg... */
 206                                 shbuf->head = old_tail;
 207                         } else {
 208                                 /* convert pointer to offset + skip NUL */
 209                                 shbuf->head = c - shbuf->data + 1;
 210                         }
 211                 }
 212                 /* store message, set new tail */
 213                 memcpy(shbuf->data + old_tail, msg, len);
 214                 shbuf->tail = new_tail;
 215         } else {
 216                 /* we need to break up the message and wrap it around */
 217                 /* k == available buffer space ahead of old tail */
 218                 int k = shbuf->size - old_tail - 1;
 219                 if (shbuf->head > old_tail) {
 220                         /* we are going to overwrite head, need to
 221                          * move it out of the way */
 222                         c = memchr(shbuf->data, '\0', old_tail);
 223                         if (!c) { /* nothing? point to this msg... */
 224                                 shbuf->head = old_tail;
 225                         } else { /* convert pointer to offset + skip NUL */
 226                                 shbuf->head = c - shbuf->data + 1;
 227                         }
 228                 }
 229                 /* copy what fits to the end of buffer, and repeat */
 230                 memcpy(shbuf->data + old_tail, msg, k);
 231                 msg += k;
 232                 len -= k;
 233                 shbuf->tail = 0;
 234                 goto again;
 235         }
 236         if (semop(s_semid, SMwup, 1) == -1) {
 237                 bb_perror_msg_and_die("SMwup");
 238         }
 239 }
 240 #else
 241 void ipcsyslog_cleanup(void);
 242 void ipcsyslog_init(void);
 243 void log_to_shmem(const char *msg);
 244
 245
 246 #endif /* FEATURE_IPC_SYSLOG */
 247
 248
 249 /* Print a message to the log file. */
 250 static void log_locally(char *msg)
 251 {
 252         int fd, len = strlen(msg);
 253
 254 #if ENABLE_FEATURE_IPC_SYSLOG
 255         if ((option_mask32 & OPT_circularlog) && shbuf) {
 256                 log_to_shmem(msg, len);
 257                 return;
 258         }
 259 #endif
 260
 261  again:
 262         fd = device_open(logFilePath, O_WRONLY | O_CREAT
 263                                         | O_NOCTTY | O_APPEND | O_NONBLOCK);
 264         if (fd >= 0) {
 265                 struct flock fl;
 266
 267                 fl.l_whence = SEEK_SET;
 268                 fl.l_start = 0;
 269                 fl.l_len = 1;
 270                 fl.l_type = F_WRLCK;
 271                 fcntl(fd, F_SETLKW, &fl);
 272
 273 #if ENABLE_FEATURE_ROTATE_LOGFILE
 274                 if (logFileSize) {
 275                         struct stat statf;
 276                         int r = fstat(fd, &statf);
 277                         if (!r && (statf.st_mode & S_IFREG)
 278                          && (lseek(fd, 0, SEEK_END) > logFileSize)
 279                         ) {
 280                                 if (logFileRotate) { /* always 0..99 */
 281                                         int i = strlen(logFilePath) + 3 + 1;
 282                                         char oldFile[i];
 283                                         char newFile[i];
 284                                         i = logFileRotate - 1;
 285                                         /* rename: f.8 -> f.9; f.7 -> f.8; ... */
 286                                         while (1) {
 287                                                 sprintf(newFile, "%s.%d", logFilePath, i);
 288                                                 if (i == 0) break;
 289                                                 sprintf(oldFile, "%s.%d", logFilePath, --i);
 290                                                 rename(oldFile, newFile);
 291                                         }
 292                                         /* newFile == "f.0" now */
 293                                         rename(logFilePath, newFile);
 294                                         fl.l_type = F_UNLCK;
 295                                         fcntl(fd, F_SETLKW, &fl);
 296                                         close(fd);
 297                                         goto again;
 298                                 }
 299                                 ftruncate(fd, 0);
 300                         }
 301                 }
 302 #endif
 303                 full_write(fd, msg, len);
 304                 fl.l_type = F_UNLCK;
 305                 fcntl(fd, F_SETLKW, &fl);
 306                 close(fd);
 307         } else {
 308                 /* cannot open logfile? - print to /dev/console then */
 309                 fd = device_open(_PATH_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
 310                 if (fd < 0)
 311                         fd = 2; /* then stderr, dammit */
 312                 full_write(fd, msg, len);
 313                 if (fd != 2)
 314                         close(fd);
 315         }
 316 }
 317
 318 static void parse_fac_prio_20(int pri, char *res20)
 319 {
 320         CODE *c_pri, *c_fac;
 321
 322         if (pri != 0) {
 323                 c_fac = facilitynames;
 324                 while (c_fac->c_name) {
 325                         if (c_fac->c_val != (LOG_FAC(pri) << 3)) {
 326                                 c_fac++; continue;
 327                         }
 328                         /* facility is found, look for prio */
 329                         c_pri = prioritynames;
 330                         while (c_pri->c_name) {
 331                                 if (c_pri->c_val != LOG_PRI(pri)) {
 332                                         c_pri++; continue;
 333                                 }
 334                                 snprintf(res20, 20, "%s.%s",
 335                                                 c_fac->c_name, c_pri->c_name);
 336                                 return;
 337                         }
 338                         /* prio not found, bail out */
 339                         break;
 340                 }
 341                 snprintf(res20, 20, "<%d>", pri);
 342         }
 343 }
 344
 345 /* len parameter is used only for "is there a timestamp?" check
 346  * NB: some callers cheat and supply 0 when they know
 347  * that there is no timestamp, short-cutting the test */
 348 static void timestamp_and_log(int pri, char *msg, int len)
 349 {
 350         time_t now;
 351         char *timestamp;
 352
 353         if (len < 16 || msg[3] != ' ' || msg[6] != ' '
 354          || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
 355         ) {
 356                 time(&now);
 357                 timestamp = ctime(&now) + 4;
 358         } else {
 359                 timestamp = msg;
 360                 msg += 16;
 361         }
 362         timestamp[15] = '\0';
 363
 364         /* Log message locally (to file or shared mem) */
 365         if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
 366                 if (LOG_PRI(pri) < logLevel) {
 367                         if (option_mask32 & OPT_small)
 368                                 msg = xasprintf("%s %s\n", timestamp, msg);
 369                         else {
 370                                 char res[20];
 371                                 parse_fac_prio_20(pri, res);
 372                                 msg = xasprintf("%s %s %s %s\n", timestamp, localHostName, res, msg);
 373                         }
 374                         log_locally(msg);
 375                         free(msg);
 376                 }
 377         }
 378 }
 379
 380 static void split_escape_and_log(char *tmpbuf, int len)
 381 {
 382         char line[len * 2 + 1]; /* gcc' cheap alloca */
 383         char *p = tmpbuf;
 384
 385         tmpbuf += len;
 386         while (p < tmpbuf) {
 387                 char c;
 388                 char *q = line;
 389                 int pri = (LOG_USER | LOG_NOTICE);
 390
 391                 if (*p == '<') {
 392                         /* Parse the magic priority number. */
 393                         pri = bb_strtou(p + 1, &p, 10);
 394                         if (*p == '>') p++;
 395                         if (pri & ~(LOG_FACMASK | LOG_PRIMASK)) {
 396                                 pri = (LOG_USER | LOG_NOTICE);
 397                         }
 398                 }
 399
 400                 while ((c = *p++)) {
 401                         if (c == '\n')
 402                                 c = ' ';
 403                         if (!(c & ~0x1f)) {
 404                                 *q++ = '^';
 405                                 c += '@'; /* ^@, ^A, ^B... */
 406                         }
 407                         *q++ = c;
 408                 }
 409                 *q = '\0';
 410                 /* now log it */
 411                 timestamp_and_log(pri, line, q - line);
 412         }
 413 }
 414
 415 static void quit_signal(int sig)
 416 {
 417         timestamp_and_log(LOG_SYSLOG | LOG_INFO, "System log daemon exiting", 0);
 418         puts("System log daemon exiting");
 419         unlink(dev_log_name);
 420         if (ENABLE_FEATURE_IPC_SYSLOG)
 421                 ipcsyslog_cleanup();
 422         exit(1);
 423 }
 424
 425 static void do_mark(int sig)
 426 {
 427         if (markInterval) {
 428                 timestamp_and_log(LOG_SYSLOG | LOG_INFO, "-- MARK --", 0);
 429                 alarm(markInterval);
 430         }
 431 }
 432
 433 static void do_syslogd(void) ATTRIBUTE_NORETURN;
 434 static void do_syslogd(void)
 435 {
 436         struct sockaddr_un sunx;
 437         socklen_t addrLength;
 438         int sock_fd;
 439         fd_set fds;
 440
 441         /* Set up signal handlers. */
 442         signal(SIGINT, quit_signal);
 443         signal(SIGTERM, quit_signal);
 444         signal(SIGQUIT, quit_signal);
 445         signal(SIGHUP, SIG_IGN);
 446         signal(SIGCHLD, SIG_IGN);
 447 #ifdef SIGCLD
 448         signal(SIGCLD, SIG_IGN);
 449 #endif
 450         signal(SIGALRM, do_mark);
 451         alarm(markInterval);
 452
 453         /* Unlink old /dev/log (or object it points to) */
 454         if (realpath(_PATH_LOG, dev_log_name) != NULL) {
 455                 unlink(dev_log_name);
 456         }
 457
 458         memset(&sunx, 0, sizeof(sunx));
 459         sunx.sun_family = AF_UNIX;
 460         strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
 461         sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
 462         addrLength = sizeof(sunx.sun_family) + strlen(sunx.sun_path);
 463         if (bind(sock_fd, (struct sockaddr *) &sunx, addrLength) < 0) {
 464                 bb_perror_msg_and_die("cannot connect to socket %s", dev_log_name);
 465         }
 466
 467         if (chmod(dev_log_name, 0666) < 0) {
 468                 bb_perror_msg_and_die("cannot set permission on %s", dev_log_name);
 469         }
 470         if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
 471                 ipcsyslog_init();
 472         }
 473
 474         timestamp_and_log(LOG_SYSLOG | LOG_INFO, "syslogd started: BusyBox v" BB_VER, 0);
 475
 476         for (;;) {
 477                 FD_ZERO(&fds);
 478                 FD_SET(sock_fd, &fds);
 479
 480                 if (select(sock_fd + 1, &fds, NULL, NULL, NULL) < 0) {
 481                         if (errno == EINTR) {
 482                                 /* alarm may have happened. */
 483                                 continue;
 484                         }
 485                         bb_perror_msg_and_die("select");
 486                 }
 487
 488                 if (FD_ISSET(sock_fd, &fds)) {
 489                         int i;
 490 #define tmpbuf bb_common_bufsiz1
 491                         i = recv(sock_fd, tmpbuf, MAX_READ, 0);
 492                         if (i <= 0)
 493                                 bb_perror_msg_and_die("UNIX socket error");
 494                         /* TODO: maybe supress duplicates? */
 495 #if ENABLE_FEATURE_REMOTE_LOG
 496                         /* We are not modifying log messages in any way before send */
 497                         /* Remote site cannot trust _us_ anyway and need to do validation again */
 498                         if (option_mask32 & OPT_remotelog) {
 499                                 if (-1 == remoteFD) {
 500                                         remoteFD = socket(AF_INET, SOCK_DGRAM, 0);
 501                                 }
 502                                 if (-1 != remoteFD) {
 503                                         /* send message to remote logger, ignore possible error */
 504                                         sendto(remoteFD, tmpbuf, i, MSG_DONTWAIT,
 505                                                 (struct sockaddr *) &remoteAddr,
 506                                                 sizeof(remoteAddr));
 507                                 }
 508                         }
 509 #endif
 510                         tmpbuf[i] = '\0';
 511                         split_escape_and_log(tmpbuf, i);
 512 #undef tmpbuf
 513                 } /* FD_ISSET() */
 514         } /* for */
 515 }
 516
 517 int syslogd_main(int argc, char **argv)
 518 {
 519         char OPTION_DECL;
 520         char *p;
 521
 522         /* do normal option parsing */
 523         getopt32(argc, argv, OPTION_STR, OPTION_PARAM);
 524         if (option_mask32 & OPT_mark) // -m
 525                 markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
 526         //if (option_mask32 & OPT_nofork) // -n
 527         //if (option_mask32 & OPT_outfile) // -O
 528         if (option_mask32 & OPT_loglevel) // -l
 529                 logLevel = xatou_range(opt_l, 1, 8);
 530         //if (option_mask32 & OPT_small) // -S
 531 #if ENABLE_FEATURE_ROTATE_LOGFILE
 532         if (option_mask32 & OPT_filesize) // -s
 533                 logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
 534         if (option_mask32 & OPT_rotatecnt) // -b
 535                 logFileRotate = xatou_range(opt_b, 0, 99);
 536 #endif
 537 #if ENABLE_FEATURE_REMOTE_LOG
 538         if (option_mask32 & OPT_remotelog) { // -R
 539                 int port = 514;
 540                 p = strchr(opt_R, ':');
 541                 if (p) {
 542                         *p++ = '\0';
 543                         port = xatou16(p);
 544                 }
 545                 remoteAddr.sin_family = AF_INET;
 546                 /* FIXME: looks ip4-specific. need to do better */
 547                 remoteAddr.sin_addr = *(struct in_addr *) *(xgethostbyname(opt_R)->h_addr_list);
 548                 remoteAddr.sin_port = htons(port);
 549         }
 550         //if (option_mask32 & OPT_locallog) // -L
 551 #endif
 552 #if ENABLE_FEATURE_IPC_SYSLOG
 553         if ((option_mask32 & OPT_circularlog) && opt_C) // -C
 554                 shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;
 555 #endif
 556
 557         /* If they have not specified remote logging, then log locally */
 558         if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_remotelog))
 559                 option_mask32 |= OPT_locallog;
 560
 561         /* Store away localhost's name before the fork */
 562         gethostname(localHostName, sizeof(localHostName));
 563         p = strchr(localHostName, '.');
 564         if (p) {
 565                 *p = '\0';
 566         }
 567
 568         if (!(option_mask32 & OPT_nofork)) {
 569 #ifdef BB_NOMMU
 570                 vfork_daemon_rexec(0, 1, argc, argv, "-n");
 571 #else
 572                 xdaemon(0, 1);
 573 #endif
 574         }
 575         umask(0);
 576         do_syslogd();
 577
 578         return EXIT_SUCCESS;
 579 }