1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1983, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __SCCSID("@(#)syslog.c 8.5 (Berkeley) 4/29/95"); 34 __FBSDID("$FreeBSD$"); 35 36 #include "namespace.h" 37 #include <sys/param.h> 38 #include <sys/socket.h> 39 #include <sys/syslog.h> 40 #include <sys/time.h> 41 #include <sys/uio.h> 42 #include <sys/un.h> 43 #include <netdb.h> 44 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <paths.h> 48 #include <pthread.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <time.h> 53 #include <unistd.h> 54 55 #include <stdarg.h> 56 #include "un-namespace.h" 57 58 #include "libc_private.h" 59 60 static int LogFile = -1; /* fd for log */ 61 static int status; /* connection status */ 62 static int opened; /* have done openlog() */ 63 static int LogStat = 0; /* status bits, set by openlog() */ 64 static const char *LogTag = NULL; /* string to tag the entry with */ 65 static int LogFacility = LOG_USER; /* default facility code */ 66 static int LogMask = 0xff; /* mask of priorities to be logged */ 67 static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER; 68 69 #define THREAD_LOCK() \ 70 do { \ 71 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \ 72 } while(0) 73 #define THREAD_UNLOCK() \ 74 do { \ 75 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \ 76 } while(0) 77 78 /* RFC5424 defined value. */ 79 #define NILVALUE "-" 80 81 static void disconnectlog(void); /* disconnect from syslogd */ 82 static void connectlog(void); /* (re)connect to syslogd */ 83 static void openlog_unlocked(const char *, int, int); 84 85 enum { 86 NOCONN = 0, 87 CONNDEF, 88 CONNPRIV, 89 }; 90 91 /* 92 * Format of the magic cookie passed through the stdio hook 93 */ 94 struct bufcookie { 95 char *base; /* start of buffer */ 96 int left; 97 }; 98 99 /* 100 * stdio write hook for writing to a static string buffer 101 * XXX: Maybe one day, dynamically allocate it so that the line length 102 * is `unlimited'. 103 */ 104 static int 105 writehook(void *cookie, const char *buf, int len) 106 { 107 struct bufcookie *h; /* private `handle' */ 108 109 h = (struct bufcookie *)cookie; 110 if (len > h->left) { 111 /* clip in case of wraparound */ 112 len = h->left; 113 } 114 if (len > 0) { 115 (void)memcpy(h->base, buf, len); /* `write' it. */ 116 h->base += len; 117 h->left -= len; 118 } 119 return len; 120 } 121 122 /* 123 * syslog, vsyslog -- 124 * print message on log file; output is intended for syslogd(8). 125 */ 126 void 127 syslog(int pri, const char *fmt, ...) 128 { 129 va_list ap; 130 131 va_start(ap, fmt); 132 vsyslog(pri, fmt, ap); 133 va_end(ap); 134 } 135 136 static void 137 vsyslog1(int pri, const char *fmt, va_list ap) 138 { 139 struct timeval now; 140 struct tm tm; 141 char ch, *p; 142 long tz_offset; 143 int cnt, fd, saved_errno; 144 char hostname[MAXHOSTNAMELEN], *stdp, tbuf[2048], fmt_cpy[1024], 145 errstr[64], tz_sign; 146 FILE *fp, *fmt_fp; 147 struct bufcookie tbuf_cookie; 148 struct bufcookie fmt_cookie; 149 150 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID 151 /* Check for invalid bits. */ 152 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) { 153 syslog(INTERNALLOG, 154 "syslog: unknown facility/priority: %x", pri); 155 pri &= LOG_PRIMASK|LOG_FACMASK; 156 } 157 158 saved_errno = errno; 159 160 /* Check priority against setlogmask values. */ 161 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask)) 162 return; 163 164 /* Set default facility if none specified. */ 165 if ((pri & LOG_FACMASK) == 0) 166 pri |= LogFacility; 167 168 /* Create the primary stdio hook */ 169 tbuf_cookie.base = tbuf; 170 tbuf_cookie.left = sizeof(tbuf); 171 fp = fwopen(&tbuf_cookie, writehook); 172 if (fp == NULL) 173 return; 174 175 /* Build the message according to RFC 5424. Tag and version. */ 176 (void)fprintf(fp, "<%d>1 ", pri); 177 /* Timestamp similar to RFC 3339. */ 178 if (gettimeofday(&now, NULL) == 0 && 179 localtime_r(&now.tv_sec, &tm) != NULL) { 180 if (tm.tm_gmtoff < 0) { 181 tz_sign = '-'; 182 tz_offset = -tm.tm_gmtoff; 183 } else { 184 tz_sign = '+'; 185 tz_offset = tm.tm_gmtoff; 186 } 187 188 (void)fprintf(fp, 189 "%04d-%02d-%02d" /* Date. */ 190 "T%02d:%02d:%02d.%06ld" /* Time. */ 191 "%c%02ld:%02ld ", /* Time zone offset. */ 192 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 193 tm.tm_hour, tm.tm_min, tm.tm_sec, now.tv_usec, 194 tz_sign, tz_offset / 3600, (tz_offset % 3600) / 60); 195 } else 196 (void)fputs(NILVALUE " ", fp); 197 /* Hostname. */ 198 (void)gethostname(hostname, sizeof(hostname)); 199 (void)fprintf(fp, "%s ", 200 hostname[0] == '\0' ? NILVALUE : hostname); 201 if (LogStat & LOG_PERROR) { 202 /* Transfer to string buffer */ 203 (void)fflush(fp); 204 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left); 205 } 206 /* Application name. */ 207 if (LogTag == NULL) 208 LogTag = _getprogname(); 209 (void)fprintf(fp, "%s ", LogTag == NULL ? NILVALUE : LogTag); 210 /* 211 * Provide the process ID regardless of whether LOG_PID has been 212 * specified, as it provides valuable information. Many 213 * applications tend not to use this, even though they should. 214 */ 215 (void)fprintf(fp, "%d ", getpid()); 216 /* Message ID. */ 217 (void)fputs(NILVALUE " ", fp); 218 /* Structured data. */ 219 (void)fputs(NILVALUE " ", fp); 220 221 /* Check to see if we can skip expanding the %m */ 222 if (strstr(fmt, "%m")) { 223 224 /* Create the second stdio hook */ 225 fmt_cookie.base = fmt_cpy; 226 fmt_cookie.left = sizeof(fmt_cpy) - 1; 227 fmt_fp = fwopen(&fmt_cookie, writehook); 228 if (fmt_fp == NULL) { 229 fclose(fp); 230 return; 231 } 232 233 /* 234 * Substitute error message for %m. Be careful not to 235 * molest an escaped percent "%%m". We want to pass it 236 * on untouched as the format is later parsed by vfprintf. 237 */ 238 for ( ; (ch = *fmt); ++fmt) { 239 if (ch == '%' && fmt[1] == 'm') { 240 ++fmt; 241 strerror_r(saved_errno, errstr, sizeof(errstr)); 242 fputs(errstr, fmt_fp); 243 } else if (ch == '%' && fmt[1] == '%') { 244 ++fmt; 245 fputc(ch, fmt_fp); 246 fputc(ch, fmt_fp); 247 } else { 248 fputc(ch, fmt_fp); 249 } 250 } 251 252 /* Null terminate if room */ 253 fputc(0, fmt_fp); 254 fclose(fmt_fp); 255 256 /* Guarantee null termination */ 257 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0'; 258 259 fmt = fmt_cpy; 260 } 261 262 /* Message. */ 263 (void)vfprintf(fp, fmt, ap); 264 (void)fclose(fp); 265 266 cnt = sizeof(tbuf) - tbuf_cookie.left; 267 268 /* Remove a trailing newline */ 269 if (tbuf[cnt - 1] == '\n') 270 cnt--; 271 272 /* Output to stderr if requested. */ 273 if (LogStat & LOG_PERROR) { 274 struct iovec iov[2]; 275 struct iovec *v = iov; 276 277 v->iov_base = stdp; 278 v->iov_len = cnt - (stdp - tbuf); 279 ++v; 280 v->iov_base = "\n"; 281 v->iov_len = 1; 282 (void)_writev(STDERR_FILENO, iov, 2); 283 } 284 285 /* Get connected, output the message to the local logger. */ 286 if (!opened) 287 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0); 288 connectlog(); 289 290 /* 291 * If the send() fails, there are two likely scenarios: 292 * 1) syslogd was restarted 293 * 2) /var/run/log is out of socket buffer space, which 294 * in most cases means local DoS. 295 * If the error does not indicate a full buffer, we address 296 * case #1 by attempting to reconnect to /var/run/log[priv] 297 * and resending the message once. 298 * 299 * If we are working with a privileged socket, the retry 300 * attempts end there, because we don't want to freeze a 301 * critical application like su(1) or sshd(8). 302 * 303 * Otherwise, we address case #2 by repeatedly retrying the 304 * send() to give syslogd a chance to empty its socket buffer. 305 */ 306 307 if (send(LogFile, tbuf, cnt, 0) < 0) { 308 if (errno != ENOBUFS) { 309 /* 310 * Scenario 1: syslogd was restarted 311 * reconnect and resend once 312 */ 313 disconnectlog(); 314 connectlog(); 315 if (send(LogFile, tbuf, cnt, 0) >= 0) 316 return; 317 /* 318 * if the resend failed, fall through to 319 * possible scenario 2 320 */ 321 } 322 while (errno == ENOBUFS) { 323 /* 324 * Scenario 2: out of socket buffer space 325 * possible DoS, fail fast on a privileged 326 * socket 327 */ 328 if (status == CONNPRIV) 329 break; 330 _usleep(1); 331 if (send(LogFile, tbuf, cnt, 0) >= 0) 332 return; 333 } 334 } else 335 return; 336 337 /* 338 * Output the message to the console; try not to block 339 * as a blocking console should not stop other processes. 340 * Make sure the error reported is the one from the syslogd failure. 341 */ 342 if (LogStat & LOG_CONS && 343 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >= 344 0) { 345 struct iovec iov[2]; 346 struct iovec *v = iov; 347 348 p = strchr(tbuf, '>') + 3; 349 v->iov_base = p; 350 v->iov_len = cnt - (p - tbuf); 351 ++v; 352 v->iov_base = "\r\n"; 353 v->iov_len = 2; 354 (void)_writev(fd, iov, 2); 355 (void)_close(fd); 356 } 357 } 358 359 static void 360 syslog_cancel_cleanup(void *arg __unused) 361 { 362 363 THREAD_UNLOCK(); 364 } 365 366 void 367 vsyslog(int pri, const char *fmt, va_list ap) 368 { 369 370 THREAD_LOCK(); 371 pthread_cleanup_push(syslog_cancel_cleanup, NULL); 372 vsyslog1(pri, fmt, ap); 373 pthread_cleanup_pop(1); 374 } 375 376 /* Should be called with mutex acquired */ 377 static void 378 disconnectlog(void) 379 { 380 /* 381 * If the user closed the FD and opened another in the same slot, 382 * that's their problem. They should close it before calling on 383 * system services. 384 */ 385 if (LogFile != -1) { 386 _close(LogFile); 387 LogFile = -1; 388 } 389 status = NOCONN; /* retry connect */ 390 } 391 392 /* Should be called with mutex acquired */ 393 static void 394 connectlog(void) 395 { 396 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */ 397 398 if (LogFile == -1) { 399 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 400 0)) == -1) 401 return; 402 } 403 if (LogFile != -1 && status == NOCONN) { 404 SyslogAddr.sun_len = sizeof(SyslogAddr); 405 SyslogAddr.sun_family = AF_UNIX; 406 407 /* 408 * First try privileged socket. If no success, 409 * then try default socket. 410 */ 411 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV, 412 sizeof SyslogAddr.sun_path); 413 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 414 sizeof(SyslogAddr)) != -1) 415 status = CONNPRIV; 416 417 if (status == NOCONN) { 418 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG, 419 sizeof SyslogAddr.sun_path); 420 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 421 sizeof(SyslogAddr)) != -1) 422 status = CONNDEF; 423 } 424 425 if (status == NOCONN) { 426 /* 427 * Try the old "/dev/log" path, for backward 428 * compatibility. 429 */ 430 (void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG, 431 sizeof SyslogAddr.sun_path); 432 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 433 sizeof(SyslogAddr)) != -1) 434 status = CONNDEF; 435 } 436 437 if (status == NOCONN) { 438 (void)_close(LogFile); 439 LogFile = -1; 440 } 441 } 442 } 443 444 static void 445 openlog_unlocked(const char *ident, int logstat, int logfac) 446 { 447 if (ident != NULL) 448 LogTag = ident; 449 LogStat = logstat; 450 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) 451 LogFacility = logfac; 452 453 if (LogStat & LOG_NDELAY) /* open immediately */ 454 connectlog(); 455 456 opened = 1; /* ident and facility has been set */ 457 } 458 459 void 460 openlog(const char *ident, int logstat, int logfac) 461 { 462 463 THREAD_LOCK(); 464 pthread_cleanup_push(syslog_cancel_cleanup, NULL); 465 openlog_unlocked(ident, logstat, logfac); 466 pthread_cleanup_pop(1); 467 } 468 469 470 void 471 closelog(void) 472 { 473 THREAD_LOCK(); 474 if (LogFile != -1) { 475 (void)_close(LogFile); 476 LogFile = -1; 477 } 478 LogTag = NULL; 479 status = NOCONN; 480 THREAD_UNLOCK(); 481 } 482 483 /* setlogmask -- set the log mask level */ 484 int 485 setlogmask(int pmask) 486 { 487 int omask; 488 489 THREAD_LOCK(); 490 omask = LogMask; 491 if (pmask != 0) 492 LogMask = pmask; 493 THREAD_UNLOCK(); 494 return (omask); 495 } 496