1 /* 2 * Copyright (c) 1983, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)syslog.c 8.5 (Berkeley) 4/29/95 30 * $FreeBSD: src/lib/libc/gen/syslog.c,v 1.39 2007/01/09 00:27:55 imp Exp $ 31 */ 32 33 #include "namespace.h" 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 #include <sys/syslog.h> 37 #include <sys/uio.h> 38 #include <sys/un.h> 39 #include <netdb.h> 40 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <paths.h> 44 #include <pthread.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <time.h> 49 #include <unistd.h> 50 51 #include <stdarg.h> 52 #include "un-namespace.h" 53 54 #include "libc_private.h" 55 56 static int LogFile = -1; /* fd for log */ 57 static int status; /* connection status */ 58 static int opened; /* have done openlog() */ 59 static int LogStat = 0; /* status bits, set by openlog() */ 60 static const char *LogTag = NULL; /* string to tag the entry with */ 61 static int LogFacility = LOG_USER; /* default facility code */ 62 static int LogMask = 0xff; /* mask of priorities to be logged */ 63 static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER; 64 65 #define THREAD_LOCK() \ 66 do { \ 67 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \ 68 } while(0) 69 #define THREAD_UNLOCK() \ 70 do { \ 71 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \ 72 } while(0) 73 74 static void disconnectlog(void); /* disconnect from syslogd */ 75 static void connectlog(void); /* (re)connect to syslogd */ 76 static void openlog_unlocked(const char *, int, int); 77 78 enum { 79 NOCONN = 0, 80 CONNDEF, 81 CONNPRIV, 82 }; 83 84 /* 85 * Format of the magic cookie passed through the stdio hook 86 */ 87 struct bufcookie { 88 char *base; /* start of buffer */ 89 int left; 90 }; 91 92 /* 93 * stdio write hook for writing to a static string buffer 94 * XXX: Maybe one day, dynamically allocate it so that the line length 95 * is `unlimited'. 96 */ 97 static int 98 writehook(void *cookie, const char *buf, int len) 99 { 100 struct bufcookie *h; /* private `handle' */ 101 102 h = (struct bufcookie *)cookie; 103 if (len > h->left) { 104 /* clip in case of wraparound */ 105 len = h->left; 106 } 107 if (len > 0) { 108 memcpy(h->base, buf, len); /* `write' it. */ 109 h->base += len; 110 h->left -= len; 111 } 112 return len; 113 } 114 115 /* 116 * syslog, vsyslog -- 117 * print message on log file; output is intended for syslogd(8). 118 */ 119 void 120 syslog(int pri, const char *fmt, ...) 121 { 122 va_list ap; 123 124 va_start(ap, fmt); 125 vsyslog(pri, fmt, ap); 126 va_end(ap); 127 } 128 129 void 130 vsyslog(int pri, const char *fmt, va_list ap) 131 { 132 char ch, *p; 133 time_t now; 134 int cnt, fd, saved_errno, maxtries; 135 char *stdp, tbuf[2048], fmt_cpy[1024], timbuf[26], errstr[64]; 136 FILE *fp, *fmt_fp; 137 struct bufcookie tbuf_cookie; 138 struct bufcookie fmt_cookie; 139 140 stdp = NULL; 141 142 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID 143 /* Check for invalid bits. */ 144 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) { 145 syslog(INTERNALLOG, 146 "syslog: unknown facility/priority: %x", pri); 147 pri &= LOG_PRIMASK|LOG_FACMASK; 148 } 149 150 saved_errno = errno; 151 152 THREAD_LOCK(); 153 154 /* Check priority against setlogmask values. */ 155 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask)) { 156 THREAD_UNLOCK(); 157 return; 158 } 159 160 /* Set default facility if none specified. */ 161 if ((pri & LOG_FACMASK) == 0) 162 pri |= LogFacility; 163 164 /* Create the primary stdio hook */ 165 tbuf_cookie.base = tbuf; 166 tbuf_cookie.left = sizeof(tbuf); 167 fp = fwopen(&tbuf_cookie, writehook); 168 if (fp == NULL) { 169 THREAD_UNLOCK(); 170 return; 171 } 172 173 /* Build the message. */ 174 time(&now); 175 fprintf(fp, "<%d>", pri); 176 fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4); 177 if (LogStat & LOG_PERROR) { 178 /* Transfer to string buffer */ 179 fflush(fp); 180 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left); 181 } 182 if (LogTag == NULL) 183 LogTag = _getprogname(); 184 if (LogTag != NULL) 185 fprintf(fp, "%s", LogTag); 186 if (LogStat & LOG_PID) 187 fprintf(fp, "[%d]", getpid()); 188 if (LogTag != NULL) 189 fprintf(fp, ": "); 190 191 /* Check to see if we can skip expanding the %m */ 192 if (strstr(fmt, "%m")) { 193 194 /* Create the second stdio hook */ 195 fmt_cookie.base = fmt_cpy; 196 fmt_cookie.left = sizeof(fmt_cpy) - 1; 197 fmt_fp = fwopen(&fmt_cookie, writehook); 198 if (fmt_fp == NULL) { 199 fclose(fp); 200 THREAD_UNLOCK(); 201 return; 202 } 203 204 /* 205 * Substitute error message for %m. Be careful not to 206 * molest an escaped percent "%%m". We want to pass it 207 * on untouched as the format is later parsed by vfprintf. 208 */ 209 for ( ; (ch = *fmt); ++fmt) { 210 if (ch == '%' && fmt[1] == 'm') { 211 ++fmt; 212 strerror_r(saved_errno, errstr, sizeof(errstr)); 213 fputs(errstr, fmt_fp); 214 } else if (ch == '%' && fmt[1] == '%') { 215 ++fmt; 216 fputc(ch, fmt_fp); 217 fputc(ch, fmt_fp); 218 } else { 219 fputc(ch, fmt_fp); 220 } 221 } 222 223 /* Null terminate if room */ 224 fputc(0, fmt_fp); 225 fclose(fmt_fp); 226 227 /* Guarantee null termination */ 228 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0'; 229 230 fmt = fmt_cpy; 231 } 232 233 vfprintf(fp, fmt, ap); 234 fclose(fp); 235 236 cnt = sizeof(tbuf) - tbuf_cookie.left; 237 238 /* Remove a trailing newline */ 239 if (tbuf[cnt - 1] == '\n') 240 cnt--; 241 242 /* Output to stderr if requested. */ 243 if (LogStat & LOG_PERROR) { 244 struct iovec iov[2]; 245 struct iovec *v = iov; 246 247 v->iov_base = stdp; 248 v->iov_len = cnt - (stdp - tbuf); 249 ++v; 250 v->iov_base = "\n"; 251 v->iov_len = 1; 252 _writev(STDERR_FILENO, iov, 2); 253 } 254 255 /* Get connected, output the message to the local logger. */ 256 if (!opened) 257 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0); 258 connectlog(); 259 260 /* 261 * If the send() fails, there are three likely scenarios: 262 * 1) syslogd was restarted 263 * 2) /var/run/log is out of socket buffer space, which 264 * in most cases means local DoS. 265 * 3) syslogd itself got stuck. 266 * 267 * We attempt to reconnect to /var/run/log to take care of 268 * case #1 and keep send()ing data to cover case #2 269 * to give syslogd a chance to empty its socket buffer. 270 * However, to deal with #3 we retry no more than 10 times 271 * for up to one second before giving up. Otherwise a 272 * broken syslogd will completely and utterly break the 273 * entire system == bad. 274 * 275 * If we are working with a privileged socket, then take 276 * only one attempt, because we don't want to freeze a 277 * critical application like su(1) or sshd(8). 278 * 279 */ 280 if (send(LogFile, tbuf, cnt, 0) < 0) { 281 if (errno != ENOBUFS) { 282 disconnectlog(); 283 connectlog(); 284 } 285 for (maxtries = 10; maxtries; --maxtries) { 286 if (send(LogFile, tbuf, cnt, 0) >= 0) { 287 THREAD_UNLOCK(); 288 return; 289 } 290 if (status == CONNPRIV) 291 break; 292 if (errno != ENOBUFS) 293 break; 294 _usleep(1000000 / 10); 295 } 296 } else { 297 THREAD_UNLOCK(); 298 return; 299 } 300 301 /* 302 * Output the message to the console; try not to block 303 * as a blocking console should not stop other processes. 304 * Make sure the error reported is the one from the syslogd failure. 305 */ 306 if ((LogStat & LOG_CONS) && 307 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >= 0) { 308 struct iovec iov[2]; 309 struct iovec *v = iov; 310 311 p = strchr(tbuf, '>') + 1; 312 v->iov_base = p; 313 v->iov_len = cnt - (p - tbuf); 314 ++v; 315 v->iov_base = "\r\n"; 316 v->iov_len = 2; 317 _writev(fd, iov, 2); 318 _close(fd); 319 } 320 321 THREAD_UNLOCK(); 322 } 323 324 /* Should be called with mutex acquired */ 325 static void 326 disconnectlog(void) 327 { 328 /* 329 * If the user closed the FD and opened another in the same slot, 330 * that's their problem. They should close it before calling on 331 * system services. 332 */ 333 if (LogFile != -1) { 334 _close(LogFile); 335 LogFile = -1; 336 } 337 status = NOCONN; /* retry connect */ 338 } 339 340 /* Should be called with mutex acquired */ 341 static void 342 connectlog(void) 343 { 344 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */ 345 346 if (LogFile == -1) { 347 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM, 0)) == -1) 348 return; 349 _fcntl(LogFile, F_SETFD, 1); 350 } 351 if (LogFile != -1 && status == NOCONN) { 352 SyslogAddr.sun_len = sizeof(SyslogAddr); 353 SyslogAddr.sun_family = AF_UNIX; 354 355 /* 356 * First try privileged socket. If no success, 357 * then try default socket. 358 */ 359 strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV, 360 sizeof SyslogAddr.sun_path); 361 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 362 sizeof(SyslogAddr)) != -1) 363 status = CONNPRIV; 364 365 if (status == NOCONN) { 366 strncpy(SyslogAddr.sun_path, _PATH_LOG, 367 sizeof SyslogAddr.sun_path); 368 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 369 sizeof(SyslogAddr)) != -1) 370 status = CONNDEF; 371 } 372 373 if (status == NOCONN) { 374 /* 375 * Try the old "/dev/log" path, for backward 376 * compatibility. 377 */ 378 strncpy(SyslogAddr.sun_path, _PATH_OLDLOG, 379 sizeof SyslogAddr.sun_path); 380 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 381 sizeof(SyslogAddr)) != -1) 382 status = CONNDEF; 383 } 384 385 if (status == NOCONN) { 386 _close(LogFile); 387 LogFile = -1; 388 } 389 } 390 } 391 392 static void 393 openlog_unlocked(const char *ident, int logstat, int logfac) 394 { 395 if (ident != NULL) 396 LogTag = ident; 397 LogStat = logstat; 398 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) 399 LogFacility = logfac; 400 401 if (LogStat & LOG_NDELAY) /* open immediately */ 402 connectlog(); 403 404 opened = 1; /* ident and facility has been set */ 405 } 406 407 void 408 openlog(const char *ident, int logstat, int logfac) 409 { 410 THREAD_LOCK(); 411 openlog_unlocked(ident, logstat, logfac); 412 THREAD_UNLOCK(); 413 } 414 415 416 void 417 closelog(void) 418 { 419 THREAD_LOCK(); 420 _close(LogFile); 421 LogFile = -1; 422 LogTag = NULL; 423 status = NOCONN; 424 THREAD_UNLOCK(); 425 } 426 427 /* setlogmask -- set the log mask level */ 428 int 429 setlogmask(int pmask) 430 { 431 int omask; 432 433 THREAD_LOCK(); 434 omask = LogMask; 435 if (pmask != 0) 436 LogMask = pmask; 437 THREAD_UNLOCK(); 438 return (omask); 439 } 440