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 * 4. 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 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char sccsid[] = "@(#)syslog.c 8.5 (Berkeley) 4/29/95"; 32 #endif /* LIBC_SCCS and not lint */ 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "namespace.h" 37 #include <sys/types.h> 38 #include <sys/socket.h> 39 #include <sys/syslog.h> 40 #include <sys/uio.h> 41 #include <sys/un.h> 42 #include <netdb.h> 43 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <paths.h> 47 #include <pthread.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <time.h> 52 #include <unistd.h> 53 54 #include <stdarg.h> 55 #include "un-namespace.h" 56 57 #include "libc_private.h" 58 59 static int LogFile = -1; /* fd for log */ 60 static int status; /* connection status */ 61 static int opened; /* have done openlog() */ 62 static int LogStat = 0; /* status bits, set by openlog() */ 63 static const char *LogTag = NULL; /* string to tag the entry with */ 64 static int LogFacility = LOG_USER; /* default facility code */ 65 static int LogMask = 0xff; /* mask of priorities to be logged */ 66 static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER; 67 68 #define THREAD_LOCK() \ 69 do { \ 70 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \ 71 } while(0) 72 #define THREAD_UNLOCK() \ 73 do { \ 74 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \ 75 } while(0) 76 77 static void disconnectlog(void); /* disconnect from syslogd */ 78 static void connectlog(void); /* (re)connect to syslogd */ 79 static void openlog_unlocked(const char *, int, int); 80 81 enum { 82 NOCONN = 0, 83 CONNDEF, 84 CONNPRIV, 85 }; 86 87 /* 88 * Format of the magic cookie passed through the stdio hook 89 */ 90 struct bufcookie { 91 char *base; /* start of buffer */ 92 int left; 93 }; 94 95 /* 96 * stdio write hook for writing to a static string buffer 97 * XXX: Maybe one day, dynamically allocate it so that the line length 98 * is `unlimited'. 99 */ 100 static int 101 writehook(void *cookie, const char *buf, int len) 102 { 103 struct bufcookie *h; /* private `handle' */ 104 105 h = (struct bufcookie *)cookie; 106 if (len > h->left) { 107 /* clip in case of wraparound */ 108 len = h->left; 109 } 110 if (len > 0) { 111 (void)memcpy(h->base, buf, len); /* `write' it. */ 112 h->base += len; 113 h->left -= len; 114 } 115 return len; 116 } 117 118 /* 119 * syslog, vsyslog -- 120 * print message on log file; output is intended for syslogd(8). 121 */ 122 void 123 syslog(int pri, const char *fmt, ...) 124 { 125 va_list ap; 126 127 va_start(ap, fmt); 128 vsyslog(pri, fmt, ap); 129 va_end(ap); 130 } 131 132 void 133 vsyslog(int pri, const char *fmt, va_list ap) 134 { 135 int cnt; 136 char ch, *p; 137 time_t now; 138 int fd, saved_errno; 139 char *stdp, tbuf[2048], fmt_cpy[1024], timbuf[26], errstr[64]; 140 FILE *fp, *fmt_fp; 141 struct bufcookie tbuf_cookie; 142 struct bufcookie fmt_cookie; 143 144 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID 145 /* Check for invalid bits. */ 146 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) { 147 syslog(INTERNALLOG, 148 "syslog: unknown facility/priority: %x", pri); 149 pri &= LOG_PRIMASK|LOG_FACMASK; 150 } 151 152 saved_errno = errno; 153 154 THREAD_LOCK(); 155 156 /* Check priority against setlogmask values. */ 157 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask)) { 158 THREAD_UNLOCK(); 159 return; 160 } 161 162 /* Set default facility if none specified. */ 163 if ((pri & LOG_FACMASK) == 0) 164 pri |= LogFacility; 165 166 /* Create the primary stdio hook */ 167 tbuf_cookie.base = tbuf; 168 tbuf_cookie.left = sizeof(tbuf); 169 fp = fwopen(&tbuf_cookie, writehook); 170 if (fp == NULL) { 171 THREAD_UNLOCK(); 172 return; 173 } 174 175 /* Build the message. */ 176 (void)time(&now); 177 (void)fprintf(fp, "<%d>", pri); 178 (void)fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4); 179 if (LogStat & LOG_PERROR) { 180 /* Transfer to string buffer */ 181 (void)fflush(fp); 182 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left); 183 } 184 if (LogTag == NULL) 185 LogTag = _getprogname(); 186 if (LogTag != NULL) 187 (void)fprintf(fp, "%s", LogTag); 188 if (LogStat & LOG_PID) 189 (void)fprintf(fp, "[%d]", getpid()); 190 if (LogTag != NULL) { 191 (void)fprintf(fp, ": "); 192 } 193 194 /* Check to see if we can skip expanding the %m */ 195 if (strstr(fmt, "%m")) { 196 197 /* Create the second stdio hook */ 198 fmt_cookie.base = fmt_cpy; 199 fmt_cookie.left = sizeof(fmt_cpy) - 1; 200 fmt_fp = fwopen(&fmt_cookie, writehook); 201 if (fmt_fp == NULL) { 202 fclose(fp); 203 THREAD_UNLOCK(); 204 return; 205 } 206 207 /* 208 * Substitute error message for %m. Be careful not to 209 * molest an escaped percent "%%m". We want to pass it 210 * on untouched as the format is later parsed by vfprintf. 211 */ 212 for ( ; (ch = *fmt); ++fmt) { 213 if (ch == '%' && fmt[1] == 'm') { 214 ++fmt; 215 strerror_r(saved_errno, errstr, sizeof(errstr)); 216 fputs(errstr, fmt_fp); 217 } else if (ch == '%' && fmt[1] == '%') { 218 ++fmt; 219 fputc(ch, fmt_fp); 220 fputc(ch, fmt_fp); 221 } else { 222 fputc(ch, fmt_fp); 223 } 224 } 225 226 /* Null terminate if room */ 227 fputc(0, fmt_fp); 228 fclose(fmt_fp); 229 230 /* Guarantee null termination */ 231 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0'; 232 233 fmt = fmt_cpy; 234 } 235 236 (void)vfprintf(fp, fmt, ap); 237 (void)fclose(fp); 238 239 cnt = sizeof(tbuf) - tbuf_cookie.left; 240 241 /* Remove a trailing newline */ 242 if (tbuf[cnt - 1] == '\n') 243 cnt--; 244 245 /* Output to stderr if requested. */ 246 if (LogStat & LOG_PERROR) { 247 struct iovec iov[2]; 248 struct iovec *v = iov; 249 250 v->iov_base = stdp; 251 v->iov_len = cnt - (stdp - tbuf); 252 ++v; 253 v->iov_base = "\n"; 254 v->iov_len = 1; 255 (void)_writev(STDERR_FILENO, iov, 2); 256 } 257 258 /* Get connected, output the message to the local logger. */ 259 if (!opened) 260 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0); 261 connectlog(); 262 263 /* 264 * If the send() fails, there are two likely scenarios: 265 * 1) syslogd was restarted 266 * 2) /var/run/log is out of socket buffer space, which 267 * in most cases means local DoS. 268 * If the error does not indicate a full buffer, we address 269 * case #1 by attempting to reconnect to /var/run/log[priv] 270 * and resending the message once. 271 * 272 * If we are working with a privileged socket, the retry 273 * attempts end there, because we don't want to freeze a 274 * critical application like su(1) or sshd(8). 275 * 276 * Otherwise, we address case #2 by repeatedly retrying the 277 * send() to give syslogd a chance to empty its socket buffer. 278 */ 279 280 if (send(LogFile, tbuf, cnt, 0) < 0) { 281 if (errno != ENOBUFS) { 282 /* 283 * Scenario 1: syslogd was restarted 284 * reconnect and resend once 285 */ 286 disconnectlog(); 287 connectlog(); 288 if (send(LogFile, tbuf, cnt, 0) >= 0) { 289 THREAD_UNLOCK(); 290 return; 291 } 292 /* 293 * if the resend failed, fall through to 294 * possible scenario 2 295 */ 296 } 297 while (errno == ENOBUFS) { 298 /* 299 * Scenario 2: out of socket buffer space 300 * possible DoS, fail fast on a privileged 301 * socket 302 */ 303 if (status == CONNPRIV) 304 break; 305 _usleep(1); 306 if (send(LogFile, tbuf, cnt, 0) >= 0) { 307 THREAD_UNLOCK(); 308 return; 309 } 310 } 311 } else { 312 THREAD_UNLOCK(); 313 return; 314 } 315 316 /* 317 * Output the message to the console; try not to block 318 * as a blocking console should not stop other processes. 319 * Make sure the error reported is the one from the syslogd failure. 320 */ 321 if (LogStat & LOG_CONS && 322 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >= 323 0) { 324 struct iovec iov[2]; 325 struct iovec *v = iov; 326 327 p = strchr(tbuf, '>') + 1; 328 v->iov_base = p; 329 v->iov_len = cnt - (p - tbuf); 330 ++v; 331 v->iov_base = "\r\n"; 332 v->iov_len = 2; 333 (void)_writev(fd, iov, 2); 334 (void)_close(fd); 335 } 336 337 THREAD_UNLOCK(); 338 } 339 340 /* Should be called with mutex acquired */ 341 static void 342 disconnectlog(void) 343 { 344 /* 345 * If the user closed the FD and opened another in the same slot, 346 * that's their problem. They should close it before calling on 347 * system services. 348 */ 349 if (LogFile != -1) { 350 _close(LogFile); 351 LogFile = -1; 352 } 353 status = NOCONN; /* retry connect */ 354 } 355 356 /* Should be called with mutex acquired */ 357 static void 358 connectlog(void) 359 { 360 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */ 361 362 if (LogFile == -1) { 363 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 364 0)) == -1) 365 return; 366 } 367 if (LogFile != -1 && status == NOCONN) { 368 SyslogAddr.sun_len = sizeof(SyslogAddr); 369 SyslogAddr.sun_family = AF_UNIX; 370 371 /* 372 * First try privileged socket. If no success, 373 * then try default socket. 374 */ 375 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV, 376 sizeof SyslogAddr.sun_path); 377 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 378 sizeof(SyslogAddr)) != -1) 379 status = CONNPRIV; 380 381 if (status == NOCONN) { 382 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG, 383 sizeof SyslogAddr.sun_path); 384 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 385 sizeof(SyslogAddr)) != -1) 386 status = CONNDEF; 387 } 388 389 if (status == NOCONN) { 390 /* 391 * Try the old "/dev/log" path, for backward 392 * compatibility. 393 */ 394 (void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG, 395 sizeof SyslogAddr.sun_path); 396 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr, 397 sizeof(SyslogAddr)) != -1) 398 status = CONNDEF; 399 } 400 401 if (status == NOCONN) { 402 (void)_close(LogFile); 403 LogFile = -1; 404 } 405 } 406 } 407 408 static void 409 openlog_unlocked(const char *ident, int logstat, int logfac) 410 { 411 if (ident != NULL) 412 LogTag = ident; 413 LogStat = logstat; 414 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) 415 LogFacility = logfac; 416 417 if (LogStat & LOG_NDELAY) /* open immediately */ 418 connectlog(); 419 420 opened = 1; /* ident and facility has been set */ 421 } 422 423 void 424 openlog(const char *ident, int logstat, int logfac) 425 { 426 THREAD_LOCK(); 427 openlog_unlocked(ident, logstat, logfac); 428 THREAD_UNLOCK(); 429 } 430 431 432 void 433 closelog(void) 434 { 435 THREAD_LOCK(); 436 if (LogFile != -1) { 437 (void)_close(LogFile); 438 LogFile = -1; 439 } 440 LogTag = NULL; 441 status = NOCONN; 442 THREAD_UNLOCK(); 443 } 444 445 /* setlogmask -- set the log mask level */ 446 int 447 setlogmask(int pmask) 448 { 449 int omask; 450 451 THREAD_LOCK(); 452 omask = LogMask; 453 if (pmask != 0) 454 LogMask = pmask; 455 THREAD_UNLOCK(); 456 return (omask); 457 } 458