2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1983, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
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8 * modification, are permitted provided that the following conditions
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32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)syslog.c 8.5 (Berkeley) 4/29/95";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
38 #include "namespace.h"
39 #include <sys/types.h>
40 #include <sys/socket.h>
41 #include <sys/syslog.h>
57 #include "un-namespace.h"
59 #include "libc_private.h"
61 static int LogFile = -1; /* fd for log */
62 static int status; /* connection status */
63 static int opened; /* have done openlog() */
64 static int LogStat = 0; /* status bits, set by openlog() */
65 static const char *LogTag = NULL; /* string to tag the entry with */
66 static int LogFacility = LOG_USER; /* default facility code */
67 static int LogMask = 0xff; /* mask of priorities to be logged */
68 static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER;
70 #define THREAD_LOCK() \
72 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \
74 #define THREAD_UNLOCK() \
76 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \
79 static void disconnectlog(void); /* disconnect from syslogd */
80 static void connectlog(void); /* (re)connect to syslogd */
81 static void openlog_unlocked(const char *, int, int);
90 * Format of the magic cookie passed through the stdio hook
93 char *base; /* start of buffer */
98 * stdio write hook for writing to a static string buffer
99 * XXX: Maybe one day, dynamically allocate it so that the line length
103 writehook(void *cookie, const char *buf, int len)
105 struct bufcookie *h; /* private `handle' */
107 h = (struct bufcookie *)cookie;
109 /* clip in case of wraparound */
113 (void)memcpy(h->base, buf, len); /* `write' it. */
122 * print message on log file; output is intended for syslogd(8).
125 syslog(int pri, const char *fmt, ...)
130 vsyslog(pri, fmt, ap);
135 vsyslog1(int pri, const char *fmt, va_list ap)
141 char *stdp, tbuf[2048], fmt_cpy[1024], timbuf[26], errstr[64];
143 struct bufcookie tbuf_cookie;
144 struct bufcookie fmt_cookie;
146 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
147 /* Check for invalid bits. */
148 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
150 "syslog: unknown facility/priority: %x", pri);
151 pri &= LOG_PRIMASK|LOG_FACMASK;
156 /* Check priority against setlogmask values. */
157 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
160 /* Set default facility if none specified. */
161 if ((pri & LOG_FACMASK) == 0)
164 /* Create the primary stdio hook */
165 tbuf_cookie.base = tbuf;
166 tbuf_cookie.left = sizeof(tbuf);
167 fp = fwopen(&tbuf_cookie, writehook);
171 /* Build the message. */
173 (void)fprintf(fp, "<%d>", pri);
174 (void)fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4);
175 if (LogStat & LOG_PERROR) {
176 /* Transfer to string buffer */
178 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
181 LogTag = _getprogname();
183 (void)fprintf(fp, "%s", LogTag);
184 if (LogStat & LOG_PID)
185 (void)fprintf(fp, "[%d]", getpid());
186 if (LogTag != NULL) {
187 (void)fprintf(fp, ": ");
190 /* Check to see if we can skip expanding the %m */
191 if (strstr(fmt, "%m")) {
193 /* Create the second stdio hook */
194 fmt_cookie.base = fmt_cpy;
195 fmt_cookie.left = sizeof(fmt_cpy) - 1;
196 fmt_fp = fwopen(&fmt_cookie, writehook);
197 if (fmt_fp == NULL) {
203 * Substitute error message for %m. Be careful not to
204 * molest an escaped percent "%%m". We want to pass it
205 * on untouched as the format is later parsed by vfprintf.
207 for ( ; (ch = *fmt); ++fmt) {
208 if (ch == '%' && fmt[1] == 'm') {
210 strerror_r(saved_errno, errstr, sizeof(errstr));
211 fputs(errstr, fmt_fp);
212 } else if (ch == '%' && fmt[1] == '%') {
221 /* Null terminate if room */
225 /* Guarantee null termination */
226 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
231 (void)vfprintf(fp, fmt, ap);
234 cnt = sizeof(tbuf) - tbuf_cookie.left;
236 /* Remove a trailing newline */
237 if (tbuf[cnt - 1] == '\n')
240 /* Output to stderr if requested. */
241 if (LogStat & LOG_PERROR) {
243 struct iovec *v = iov;
246 v->iov_len = cnt - (stdp - tbuf);
250 (void)_writev(STDERR_FILENO, iov, 2);
253 /* Get connected, output the message to the local logger. */
255 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
259 * If the send() fails, there are two likely scenarios:
260 * 1) syslogd was restarted
261 * 2) /var/run/log is out of socket buffer space, which
262 * in most cases means local DoS.
263 * If the error does not indicate a full buffer, we address
264 * case #1 by attempting to reconnect to /var/run/log[priv]
265 * and resending the message once.
267 * If we are working with a privileged socket, the retry
268 * attempts end there, because we don't want to freeze a
269 * critical application like su(1) or sshd(8).
271 * Otherwise, we address case #2 by repeatedly retrying the
272 * send() to give syslogd a chance to empty its socket buffer.
275 if (send(LogFile, tbuf, cnt, 0) < 0) {
276 if (errno != ENOBUFS) {
278 * Scenario 1: syslogd was restarted
279 * reconnect and resend once
283 if (send(LogFile, tbuf, cnt, 0) >= 0)
286 * if the resend failed, fall through to
287 * possible scenario 2
290 while (errno == ENOBUFS) {
292 * Scenario 2: out of socket buffer space
293 * possible DoS, fail fast on a privileged
296 if (status == CONNPRIV)
299 if (send(LogFile, tbuf, cnt, 0) >= 0)
306 * Output the message to the console; try not to block
307 * as a blocking console should not stop other processes.
308 * Make sure the error reported is the one from the syslogd failure.
310 if (LogStat & LOG_CONS &&
311 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >=
314 struct iovec *v = iov;
316 p = strchr(tbuf, '>') + 1;
318 v->iov_len = cnt - (p - tbuf);
320 v->iov_base = "\r\n";
322 (void)_writev(fd, iov, 2);
328 syslog_cancel_cleanup(void *arg __unused)
335 vsyslog(int pri, const char *fmt, va_list ap)
339 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
340 vsyslog1(pri, fmt, ap);
341 pthread_cleanup_pop(1);
344 /* Should be called with mutex acquired */
349 * If the user closed the FD and opened another in the same slot,
350 * that's their problem. They should close it before calling on
357 status = NOCONN; /* retry connect */
360 /* Should be called with mutex acquired */
364 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */
367 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
371 if (LogFile != -1 && status == NOCONN) {
372 SyslogAddr.sun_len = sizeof(SyslogAddr);
373 SyslogAddr.sun_family = AF_UNIX;
376 * First try privileged socket. If no success,
377 * then try default socket.
379 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV,
380 sizeof SyslogAddr.sun_path);
381 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
382 sizeof(SyslogAddr)) != -1)
385 if (status == NOCONN) {
386 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
387 sizeof SyslogAddr.sun_path);
388 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
389 sizeof(SyslogAddr)) != -1)
393 if (status == NOCONN) {
395 * Try the old "/dev/log" path, for backward
398 (void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
399 sizeof SyslogAddr.sun_path);
400 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
401 sizeof(SyslogAddr)) != -1)
405 if (status == NOCONN) {
406 (void)_close(LogFile);
413 openlog_unlocked(const char *ident, int logstat, int logfac)
418 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
419 LogFacility = logfac;
421 if (LogStat & LOG_NDELAY) /* open immediately */
424 opened = 1; /* ident and facility has been set */
428 openlog(const char *ident, int logstat, int logfac)
432 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
433 openlog_unlocked(ident, logstat, logfac);
434 pthread_cleanup_pop(1);
443 (void)_close(LogFile);
451 /* setlogmask -- set the log mask level */
453 setlogmask(int pmask)