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 static void disconnectlog(void); /* disconnect from syslogd */ 79 static void connectlog(void); /* (re)connect to syslogd */ 80 static void openlog_unlocked(const char *, int, int); 81 82 enum { 83 NOCONN = 0, 84 CONNDEF, 85 CONNPRIV, 86 }; 87 88 /* 89 * Format of the magic cookie passed through the stdio hook 90 */ 91 struct bufcookie { 92 char *base; /* start of buffer */ 93 int left; 94 }; 95 96 /* 97 * stdio write hook for writing to a static string buffer 98 * XXX: Maybe one day, dynamically allocate it so that the line length 99 * is `unlimited'. 100 */ 101 static int 102 writehook(void *cookie, const char *buf, int len) 103 { 104 struct bufcookie *h; /* private `handle' */ 105 106 h = (struct bufcookie *)cookie; 107 if (len > h->left) { 108 /* clip in case of wraparound */ 109 len = h->left; 110 } 111 if (len > 0) { 112 (void)memcpy(h->base, buf, len); /* `write' it. */ 113 h->base += len; 114 h->left -= len; 115 } 116 return len; 117 } 118 119 /* 120 * syslog, vsyslog -- 121 * print message on log file; output is intended for syslogd(8). 122 */ 123 void 124 syslog(int pri, const char *fmt, ...) 125 { 126 va_list ap; 127 128 va_start(ap, fmt); 129 vsyslog(pri, fmt, ap); 130 va_end(ap); 131 } 132 133 static void 134 vsyslog1(int pri, const char *fmt, va_list ap) 135 { 136 struct timeval now; 137 struct tm tm; 138 char ch, *p; 139 long tz_offset; 140 int cnt, fd, saved_errno; 141 char hostname[MAXHOSTNAMELEN], *stdp, tbuf[2048], fmt_cpy[1024], 142 errstr[64], tz_sign; 143 FILE *fp, *fmt_fp; 144 struct bufcookie tbuf_cookie; 145 struct bufcookie fmt_cookie; 146 147 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID 148 /* Check for invalid bits. */ 149 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) { 150 syslog(INTERNALLOG, 151 "syslog: unknown facility/priority: %x", pri); 152 pri &= LOG_PRIMASK|LOG_FACMASK; 153 } 154 155 saved_errno = errno; 156 157 /* Check priority against setlogmask values. */ 158 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask)) 159 return; 160 161 /* Set default facility if none specified. */ 162 if ((pri & LOG_FACMASK) == 0) 163 pri |= LogFacility; 164 165 /* Create the primary stdio hook */ 166 tbuf_cookie.base = tbuf; 167 tbuf_cookie.left = sizeof(tbuf); 168 fp = fwopen(&tbuf_cookie, writehook); 169 if (fp == NULL) 170 return; 171 172 /* Build the message according to RFC 5424. Tag and version. */ 173 (void)fprintf(fp, "<%d>1 ", pri); 174 /* Timestamp similar to RFC 3339. */ 175 if (gettimeofday(&now, NULL) == 0 && 176 localtime_r(&now.tv_sec, &tm) != NULL) { 177 if (tm.tm_gmtoff < 0) { 178 tz_sign = '-'; 179 tz_offset = -tm.tm_gmtoff; 180 } else { 181 tz_sign = '+'; 182 tz_offset = tm.tm_gmtoff; 183 } 184 185 (void)fprintf(fp, 186 "%04d-%02d-%02d" /* Date. */ 187 "T%02d:%02d:%02d.%06ld" /* Time. */ 188 "%c%02ld:%02ld ", /* Time zone offset. */ 189 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 190 tm.tm_hour, tm.tm_min, tm.tm_sec, now.tv_usec, 191 tz_sign, tz_offset / 3600, (tz_offset % 3600) / 60); 192 } else 193 (void)fprintf(fp, "- "); 194 /* Hostname. */ 195 (void)gethostname(hostname, sizeof(hostname)); 196 (void)fprintf(fp, "%s ", hostname); 197 if (LogStat & LOG_PERROR) { 198 /* Transfer to string buffer */ 199 (void)fflush(fp); 200 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left); 201 } 202 /* 203 * Application name, process ID, message ID and structured data. 204 * Provide the process ID regardless of whether LOG_PID has been 205 * specified, as it provides valuable information. Many 206 * applications tend not to use this, even though they should. 207 */ 208 if (LogTag == NULL) 209 LogTag = _getprogname(); 210 (void)fprintf(fp, "%s %d - - ", 211 LogTag == NULL ? "-" : LogTag, getpid()); 212 213 /* Check to see if we can skip expanding the %m */ 214 if (strstr(fmt, "%m")) { 215 216 /* Create the second stdio hook */ 217 fmt_cookie.base = fmt_cpy; 218 fmt_cookie.left = sizeof(fmt_cpy) - 1; 219 fmt_fp = fwopen(&fmt_cookie, writehook); 220 if (fmt_fp == NULL) { 221 fclose(fp); 222 return; 223 } 224 225 /* 226 * Substitute error message for %m. Be careful not to 227 * molest an escaped percent "%%m". We want to pass it 228 * on untouched as the format is later parsed by vfprintf. 229 */ 230 for ( ; (ch = *fmt); ++fmt) { 231 if (ch == '%' && fmt[1] == 'm') { 232 ++fmt; 233 strerror_r(saved_errno, errstr, sizeof(errstr)); 234 fputs(errstr, fmt_fp); 235 } else if (ch == '%' && fmt[1] == '%') { 236 ++fmt; 237 fputc(ch, fmt_fp); 238 fputc(ch, fmt_fp); 239 } else { 240 fputc(ch, fmt_fp); 241 } 242 } 243 244 /* Null terminate if room */ 245 fputc(0, fmt_fp); 246 fclose(fmt_fp); 247 248 /* Guarantee null termination */ 249 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0'; 250 251 fmt = fmt_cpy; 252 } 253 254 (void)vfprintf(fp, fmt, ap); 255 (void)fclose(fp); 256 257 cnt = sizeof(tbuf) - tbuf_cookie.left; 258 259 /* Remove a trailing newline */ 260 if (tbuf[cnt - 1] == '\n') 261 cnt--; 262 263 /* Output to stderr if requested. */ 264 if (LogStat & LOG_PERROR) { 265 struct iovec iov[2]; 266 struct iovec *v = iov; 267 268 v->iov_base = stdp; 269 v->iov_len = cnt - (stdp - tbuf); 270 ++v; 271 v->iov_base = "\n"; 272 v->iov_len = 1; 273 (void)_writev(STDERR_FILENO, iov, 2); 274 } 275 276 /* Get connected, output the message to the local logger. */ 277 if (!opened) 278 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0); 279 connectlog(); 280 281 /* 282 * If the send() fails, there are two likely scenarios: 283 * 1) syslogd was restarted 284 * 2) /var/run/log is out of socket buffer space, which 285 * in most cases means local DoS. 286 * If the error does not indicate a full buffer, we address 287 * case #1 by attempting to reconnect to /var/run/log[priv] 288 * and resending the message once. 289 * 290 * If we are working with a privileged socket, the retry 291 * attempts end there, because we don't want to freeze a 292 * critical application like su(1) or sshd(8). 293 * 294 * Otherwise, we address case #2 by repeatedly retrying the 295 * send() to give syslogd a chance to empty its socket buffer. 296 */ 297 298 if (send(LogFile, tbuf, cnt, 0) < 0) { 299 if (errno != ENOBUFS) { 300 /* 301 * Scenario 1: syslogd was restarted 302 * reconnect and resend once 303 */ 304 disconnectlog(); 305 connectlog(); 306 if (send(LogFile, tbuf, cnt, 0) >= 0) 307 return; 308 /* 309 * if the resend failed, fall through to 310 * possible scenario 2 311 */ 312 } 313 while (errno == ENOBUFS) { 314 /* 315 * Scenario 2: out of socket buffer space 316 * possible DoS, fail fast on a privileged 317 * socket 318 */ 319 if (status == CONNPRIV) 320 break; 321 _usleep(1); 322 if (send(LogFile, tbuf, cnt, 0) >= 0) 323 return; 324 } 325 } else 326 return; 327 328 /* 329 * Output the message to the console; try not to block 330 * as a blocking console should not stop other processes. 331 * Make sure the error reported is the one from the syslogd failure. 332 */ 333 if (LogStat & LOG_CONS && 334 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >= 335 0) { 336 struct iovec iov[2]; 337 struct iovec *v = iov; 338 339 p = strchr(tbuf, '>') + 3; 340 v->iov_base = p; 341 v->iov_len = cnt - (p - tbuf); 342 ++v; 343 v->iov_base = "\r\n"; 344 v->iov_len = 2; 345 (void)_writev(fd, iov, 2); 346 (void)_close(fd); 347 } 348 } 349 350 static void 351 syslog_cancel_cleanup(void *arg __unused) 352 { 353 354 THREAD_UNLOCK(); 355 } 356 357 void 358 vsyslog(int pri, const char *fmt, va_list ap) 359 { 360 361 THREAD_LOCK(); 362 pthread_cleanup_push(syslog_cancel_cleanup, NULL); 363 vsyslog1(pri, fmt, ap); 364 pthread_cleanup_pop(1); 365 } 366 367 /* Should be called with mutex acquired */ 368 static void 369 disconnectlog(void) 370 { 371 /* 372 * If the user closed the FD and opened another in the same slot, 373 * that's their problem. They should close it before calling on 374 * system services. 375 */ 376 if (LogFile != -1) { 377 _close(LogFile); 378 LogFile = -1; 379 } 380 status = NOCONN; /* retry connect */ 381 } 382 383 /* Should be called with mutex acquired */ 384 static void 385 connectlog(void) 386 { 387 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */ 388 389 if (LogFile == -1) { 390 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 391 0)) == -1) 392 return; 393 } 394 if (LogFile != -1 && status == NOCONN) { 395 SyslogAddr.sun_len = sizeof(SyslogAddr); 396 SyslogAddr.sun_family = AF_UNIX; 397 398 /* 399 * First try privileged socket. If no success, 400 * then try default socket. 401 */ 402 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV, 403 sizeof SyslogAddr.sun_path); 404 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 405 sizeof(SyslogAddr)) != -1) 406 status = CONNPRIV; 407 408 if (status == NOCONN) { 409 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG, 410 sizeof SyslogAddr.sun_path); 411 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 412 sizeof(SyslogAddr)) != -1) 413 status = CONNDEF; 414 } 415 416 if (status == NOCONN) { 417 /* 418 * Try the old "/dev/log" path, for backward 419 * compatibility. 420 */ 421 (void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG, 422 sizeof SyslogAddr.sun_path); 423 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 424 sizeof(SyslogAddr)) != -1) 425 status = CONNDEF; 426 } 427 428 if (status == NOCONN) { 429 (void)_close(LogFile); 430 LogFile = -1; 431 } 432 } 433 } 434 435 static void 436 openlog_unlocked(const char *ident, int logstat, int logfac) 437 { 438 if (ident != NULL) 439 LogTag = ident; 440 LogStat = logstat; 441 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) 442 LogFacility = logfac; 443 444 if (LogStat & LOG_NDELAY) /* open immediately */ 445 connectlog(); 446 447 opened = 1; /* ident and facility has been set */ 448 } 449 450 void 451 openlog(const char *ident, int logstat, int logfac) 452 { 453 454 THREAD_LOCK(); 455 pthread_cleanup_push(syslog_cancel_cleanup, NULL); 456 openlog_unlocked(ident, logstat, logfac); 457 pthread_cleanup_pop(1); 458 } 459 460 461 void 462 closelog(void) 463 { 464 THREAD_LOCK(); 465 if (LogFile != -1) { 466 (void)_close(LogFile); 467 LogFile = -1; 468 } 469 LogTag = NULL; 470 status = NOCONN; 471 THREAD_UNLOCK(); 472 } 473 474 /* setlogmask -- set the log mask level */ 475 int 476 setlogmask(int pmask) 477 { 478 int omask; 479 480 THREAD_LOCK(); 481 omask = LogMask; 482 if (pmask != 0) 483 LogMask = pmask; 484 THREAD_UNLOCK(); 485 return (omask); 486 } 487