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 static void 130 vsyslog_unlocked(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 /* Check priority against setlogmask values. */ 153 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask)) 154 return; 155 156 /* Set default facility if none specified. */ 157 if ((pri & LOG_FACMASK) == 0) 158 pri |= LogFacility; 159 160 /* Create the primary stdio hook */ 161 tbuf_cookie.base = tbuf; 162 tbuf_cookie.left = sizeof(tbuf); 163 fp = fwopen(&tbuf_cookie, writehook); 164 if (fp == NULL) 165 return; 166 167 /* Build the message. */ 168 time(&now); 169 fprintf(fp, "<%d>", pri); 170 fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4); 171 if (LogStat & LOG_PERROR) { 172 /* Transfer to string buffer */ 173 fflush(fp); 174 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left); 175 } 176 if (LogTag == NULL) 177 LogTag = _getprogname(); 178 if (LogTag != NULL) 179 fprintf(fp, "%s", LogTag); 180 if (LogStat & LOG_PID) 181 fprintf(fp, "[%d]", getpid()); 182 if (LogTag != NULL) 183 fprintf(fp, ": "); 184 185 /* Check to see if we can skip expanding the %m */ 186 if (strstr(fmt, "%m")) { 187 188 /* Create the second stdio hook */ 189 fmt_cookie.base = fmt_cpy; 190 fmt_cookie.left = sizeof(fmt_cpy) - 1; 191 fmt_fp = fwopen(&fmt_cookie, writehook); 192 if (fmt_fp == NULL) { 193 fclose(fp); 194 return; 195 } 196 197 /* 198 * Substitute error message for %m. Be careful not to 199 * molest an escaped percent "%%m". We want to pass it 200 * on untouched as the format is later parsed by vfprintf. 201 */ 202 for ( ; (ch = *fmt); ++fmt) { 203 if (ch == '%' && fmt[1] == 'm') { 204 ++fmt; 205 strerror_r(saved_errno, errstr, sizeof(errstr)); 206 fputs(errstr, fmt_fp); 207 } else if (ch == '%' && fmt[1] == '%') { 208 ++fmt; 209 fputc(ch, fmt_fp); 210 fputc(ch, fmt_fp); 211 } else { 212 fputc(ch, fmt_fp); 213 } 214 } 215 216 /* Null terminate if room */ 217 fputc(0, fmt_fp); 218 fclose(fmt_fp); 219 220 /* Guarantee null termination */ 221 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0'; 222 223 fmt = fmt_cpy; 224 } 225 226 vfprintf(fp, fmt, ap); 227 fclose(fp); 228 229 cnt = sizeof(tbuf) - tbuf_cookie.left; 230 231 /* Remove a trailing newline */ 232 if (tbuf[cnt - 1] == '\n') 233 cnt--; 234 235 /* Output to stderr if requested. */ 236 if (LogStat & LOG_PERROR) { 237 struct iovec iov[2]; 238 struct iovec *v = iov; 239 240 v->iov_base = stdp; 241 v->iov_len = cnt - (stdp - tbuf); 242 ++v; 243 v->iov_base = "\n"; 244 v->iov_len = 1; 245 _writev(STDERR_FILENO, iov, 2); 246 } 247 248 /* Get connected, output the message to the local logger. */ 249 if (!opened) 250 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0); 251 connectlog(); 252 253 /* 254 * If the send() fails, there are three likely scenarios: 255 * 1) syslogd was restarted 256 * 2) /var/run/log is out of socket buffer space, which 257 * in most cases means local DoS. 258 * 3) syslogd itself got stuck. 259 * 260 * We attempt to reconnect to /var/run/log to take care of 261 * case #1 and keep send()ing data to cover case #2 262 * to give syslogd a chance to empty its socket buffer. 263 * However, to deal with #3 we retry no more than 10 times 264 * for up to one second before giving up. Otherwise a 265 * broken syslogd will completely and utterly break the 266 * entire system == bad. 267 * 268 * If we are working with a privileged socket, then take 269 * only one attempt, because we don't want to freeze a 270 * critical application like su(1) or sshd(8). 271 * 272 */ 273 if (send(LogFile, tbuf, cnt, 0) < 0) { 274 if (errno != ENOBUFS) { 275 disconnectlog(); 276 connectlog(); 277 } 278 for (maxtries = 10; maxtries; --maxtries) { 279 if (send(LogFile, tbuf, cnt, 0) >= 0) 280 return; 281 if (status == CONNPRIV) 282 break; 283 if (errno != ENOBUFS) 284 break; 285 _usleep(1000000 / 10); 286 } 287 } else { 288 return; 289 } 290 291 /* 292 * Output the message to the console; try not to block 293 * as a blocking console should not stop other processes. 294 * Make sure the error reported is the one from the syslogd failure. 295 */ 296 if ((LogStat & LOG_CONS) && 297 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >= 0) { 298 struct iovec iov[2]; 299 struct iovec *v = iov; 300 301 p = strchr(tbuf, '>') + 1; 302 v->iov_base = p; 303 v->iov_len = cnt - (p - tbuf); 304 ++v; 305 v->iov_base = "\r\n"; 306 v->iov_len = 2; 307 _writev(fd, iov, 2); 308 _close(fd); 309 } 310 } 311 312 void 313 vsyslog(int pri, const char *fmt, va_list ap) 314 { 315 THREAD_LOCK(); 316 vsyslog_unlocked(pri, fmt, ap); 317 THREAD_UNLOCK(); 318 } 319 320 /* Should be called with mutex acquired */ 321 static void 322 disconnectlog(void) 323 { 324 /* 325 * If the user closed the FD and opened another in the same slot, 326 * that's their problem. They should close it before calling on 327 * system services. 328 */ 329 if (LogFile != -1) { 330 _close(LogFile); 331 LogFile = -1; 332 } 333 status = NOCONN; /* retry connect */ 334 } 335 336 /* Should be called with mutex acquired */ 337 static void 338 connectlog(void) 339 { 340 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */ 341 342 if (LogFile == -1) { 343 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 344 0)) == -1) 345 return; 346 } 347 if (LogFile != -1 && status == NOCONN) { 348 SyslogAddr.sun_len = sizeof(SyslogAddr); 349 SyslogAddr.sun_family = AF_UNIX; 350 351 /* 352 * First try privileged socket. If no success, 353 * then try default socket. 354 */ 355 strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV, 356 sizeof SyslogAddr.sun_path); 357 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 358 sizeof(SyslogAddr)) != -1) 359 status = CONNPRIV; 360 361 if (status == NOCONN) { 362 strncpy(SyslogAddr.sun_path, _PATH_LOG, 363 sizeof SyslogAddr.sun_path); 364 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 365 sizeof(SyslogAddr)) != -1) 366 status = CONNDEF; 367 } 368 369 if (status == NOCONN) { 370 /* 371 * Try the old "/dev/log" path, for backward 372 * compatibility. 373 */ 374 strncpy(SyslogAddr.sun_path, _PATH_OLDLOG, 375 sizeof SyslogAddr.sun_path); 376 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 377 sizeof(SyslogAddr)) != -1) 378 status = CONNDEF; 379 } 380 381 if (status == NOCONN) { 382 _close(LogFile); 383 LogFile = -1; 384 } 385 } 386 } 387 388 static void 389 openlog_unlocked(const char *ident, int logstat, int logfac) 390 { 391 if (ident != NULL) 392 LogTag = ident; 393 LogStat = logstat; 394 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) 395 LogFacility = logfac; 396 397 if (LogStat & LOG_NDELAY) /* open immediately */ 398 connectlog(); 399 400 opened = 1; /* ident and facility has been set */ 401 } 402 403 void 404 openlog(const char *ident, int logstat, int logfac) 405 { 406 THREAD_LOCK(); 407 openlog_unlocked(ident, logstat, logfac); 408 THREAD_UNLOCK(); 409 } 410 411 412 void 413 closelog(void) 414 { 415 THREAD_LOCK(); 416 if (LogFile != -1) { 417 _close(LogFile); 418 LogFile = -1; 419 } 420 LogTag = NULL; 421 status = NOCONN; 422 THREAD_UNLOCK(); 423 } 424 425 /* setlogmask -- set the log mask level */ 426 int 427 setlogmask(int pmask) 428 { 429 int omask; 430 431 THREAD_LOCK(); 432 omask = LogMask; 433 if (pmask != 0) 434 LogMask = pmask; 435 THREAD_UNLOCK(); 436 return (omask); 437 } 438