2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1983, 1988, 1993
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32 #include <sys/cdefs.h>
33 __SCCSID("@(#)syslog.c 8.5 (Berkeley) 4/29/95");
34 __FBSDID("$FreeBSD$");
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <sys/socket.h>
39 #include <sys/syslog.h>
56 #include "un-namespace.h"
58 #include "libc_private.h"
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;
69 #define THREAD_LOCK() \
71 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \
73 #define THREAD_UNLOCK() \
75 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \
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);
89 * Format of the magic cookie passed through the stdio hook
92 char *base; /* start of buffer */
97 * stdio write hook for writing to a static string buffer
98 * XXX: Maybe one day, dynamically allocate it so that the line length
102 writehook(void *cookie, const char *buf, int len)
104 struct bufcookie *h; /* private `handle' */
106 h = (struct bufcookie *)cookie;
108 /* clip in case of wraparound */
112 (void)memcpy(h->base, buf, len); /* `write' it. */
121 * print message on log file; output is intended for syslogd(8).
124 syslog(int pri, const char *fmt, ...)
129 vsyslog(pri, fmt, ap);
134 vsyslog1(int pri, const char *fmt, va_list ap)
140 int cnt, fd, saved_errno;
141 char hostname[MAXHOSTNAMELEN], *stdp, tbuf[2048], fmt_cpy[1024],
144 struct bufcookie tbuf_cookie;
145 struct bufcookie fmt_cookie;
147 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
148 /* Check for invalid bits. */
149 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
151 "syslog: unknown facility/priority: %x", pri);
152 pri &= LOG_PRIMASK|LOG_FACMASK;
157 /* Check priority against setlogmask values. */
158 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
161 /* Set default facility if none specified. */
162 if ((pri & LOG_FACMASK) == 0)
165 /* Create the primary stdio hook */
166 tbuf_cookie.base = tbuf;
167 tbuf_cookie.left = sizeof(tbuf);
168 fp = fwopen(&tbuf_cookie, writehook);
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) {
179 tz_offset = -tm.tm_gmtoff;
182 tz_offset = tm.tm_gmtoff;
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);
193 (void)fprintf(fp, "- ");
195 (void)gethostname(hostname, sizeof(hostname));
196 (void)fprintf(fp, "%s ", hostname);
197 if (LogStat & LOG_PERROR) {
198 /* Transfer to string buffer */
200 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
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.
209 LogTag = _getprogname();
210 (void)fprintf(fp, "%s %d - - ",
211 LogTag == NULL ? "-" : LogTag, getpid());
213 /* Check to see if we can skip expanding the %m */
214 if (strstr(fmt, "%m")) {
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) {
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.
230 for ( ; (ch = *fmt); ++fmt) {
231 if (ch == '%' && fmt[1] == 'm') {
233 strerror_r(saved_errno, errstr, sizeof(errstr));
234 fputs(errstr, fmt_fp);
235 } else if (ch == '%' && fmt[1] == '%') {
244 /* Null terminate if room */
248 /* Guarantee null termination */
249 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
254 (void)vfprintf(fp, fmt, ap);
257 cnt = sizeof(tbuf) - tbuf_cookie.left;
259 /* Remove a trailing newline */
260 if (tbuf[cnt - 1] == '\n')
263 /* Output to stderr if requested. */
264 if (LogStat & LOG_PERROR) {
266 struct iovec *v = iov;
269 v->iov_len = cnt - (stdp - tbuf);
273 (void)_writev(STDERR_FILENO, iov, 2);
276 /* Get connected, output the message to the local logger. */
278 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
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.
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).
294 * Otherwise, we address case #2 by repeatedly retrying the
295 * send() to give syslogd a chance to empty its socket buffer.
298 if (send(LogFile, tbuf, cnt, 0) < 0) {
299 if (errno != ENOBUFS) {
301 * Scenario 1: syslogd was restarted
302 * reconnect and resend once
306 if (send(LogFile, tbuf, cnt, 0) >= 0)
309 * if the resend failed, fall through to
310 * possible scenario 2
313 while (errno == ENOBUFS) {
315 * Scenario 2: out of socket buffer space
316 * possible DoS, fail fast on a privileged
319 if (status == CONNPRIV)
322 if (send(LogFile, tbuf, cnt, 0) >= 0)
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.
333 if (LogStat & LOG_CONS &&
334 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >=
337 struct iovec *v = iov;
339 p = strchr(tbuf, '>') + 3;
341 v->iov_len = cnt - (p - tbuf);
343 v->iov_base = "\r\n";
345 (void)_writev(fd, iov, 2);
351 syslog_cancel_cleanup(void *arg __unused)
358 vsyslog(int pri, const char *fmt, va_list ap)
362 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
363 vsyslog1(pri, fmt, ap);
364 pthread_cleanup_pop(1);
367 /* Should be called with mutex acquired */
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
380 status = NOCONN; /* retry connect */
383 /* Should be called with mutex acquired */
387 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */
390 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
394 if (LogFile != -1 && status == NOCONN) {
395 SyslogAddr.sun_len = sizeof(SyslogAddr);
396 SyslogAddr.sun_family = AF_UNIX;
399 * First try privileged socket. If no success,
400 * then try default socket.
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)
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)
416 if (status == NOCONN) {
418 * Try the old "/dev/log" path, for backward
421 (void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
422 sizeof SyslogAddr.sun_path);
423 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
424 sizeof(SyslogAddr)) != -1)
428 if (status == NOCONN) {
429 (void)_close(LogFile);
436 openlog_unlocked(const char *ident, int logstat, int logfac)
441 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
442 LogFacility = logfac;
444 if (LogStat & LOG_NDELAY) /* open immediately */
447 opened = 1; /* ident and facility has been set */
451 openlog(const char *ident, int logstat, int logfac)
455 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
456 openlog_unlocked(ident, logstat, logfac);
457 pthread_cleanup_pop(1);
466 (void)_close(LogFile);
474 /* setlogmask -- set the log mask level */
476 setlogmask(int pmask)