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)
31static 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
59static int	LogFile = -1;		/* fd for log */
60static int	status;			/* connection status */
61static int	opened;			/* have done openlog() */
62static int	LogStat = 0;		/* status bits, set by openlog() */
63static const char *LogTag = NULL;	/* string to tag the entry with */
64static int	LogFacility = LOG_USER;	/* default facility code */
65static int	LogMask = 0xff;		/* mask of priorities to be logged */
66static 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
77static void	disconnectlog(void); /* disconnect from syslogd */
78static void	connectlog(void);	/* (re)connect to syslogd */
79static void	openlog_unlocked(const char *, int, int);
80
81enum {
82	NOCONN = 0,
83	CONNDEF,
84	CONNPRIV,
85};
86
87/*
88 * Format of the magic cookie passed through the stdio hook
89 */
90struct 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 */
100static int
101writehook(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 */
122void
123syslog(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
132void
133vsyslog(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() failed, 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	 * We attempt to reconnect to /var/run/log[priv] to take care of
269	 * case #1 and keep send()ing data to cover case #2
270	 * to give syslogd a chance to empty its socket buffer.
271	 *
272	 * If we are working with a priveleged socket, then take
273	 * only one attempt, because we don't want to freeze a
274	 * critical application like su(1) or sshd(8).
275	 *
276	 */
277
278	if (send(LogFile, tbuf, cnt, 0) < 0) {
279		if (errno != ENOBUFS) {
280			disconnectlog();
281			connectlog();
282		}
283		do {
284			if (status == CONNPRIV)
285				break;
286			_usleep(1);
287			if (send(LogFile, tbuf, cnt, 0) >= 0) {
288				THREAD_UNLOCK();
289				return;
290			}
291		} while (errno == ENOBUFS);
292	} else {
293		THREAD_UNLOCK();
294		return;
295	}
296
297	/*
298	 * Output the message to the console; try not to block
299	 * as a blocking console should not stop other processes.
300	 * Make sure the error reported is the one from the syslogd failure.
301	 */
302	if (LogStat & LOG_CONS &&
303	    (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >=
304	    0) {
305		struct iovec iov[2];
306		struct iovec *v = iov;
307
308		p = strchr(tbuf, '>') + 1;
309		v->iov_base = p;
310		v->iov_len = cnt - (p - tbuf);
311		++v;
312		v->iov_base = "\r\n";
313		v->iov_len = 2;
314		(void)_writev(fd, iov, 2);
315		(void)_close(fd);
316	}
317
318	THREAD_UNLOCK();
319}
320
321/* Should be called with mutex acquired */
322static void
323disconnectlog(void)
324{
325	/*
326	 * If the user closed the FD and opened another in the same slot,
327	 * that's their problem.  They should close it before calling on
328	 * system services.
329	 */
330	if (LogFile != -1) {
331		_close(LogFile);
332		LogFile = -1;
333	}
334	status = NOCONN;			/* retry connect */
335}
336
337/* Should be called with mutex acquired */
338static void
339connectlog(void)
340{
341	struct sockaddr_un SyslogAddr;	/* AF_UNIX address of local logger */
342
343	if (LogFile == -1) {
344		if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
345			return;
346		(void)_fcntl(LogFile, F_SETFD, FD_CLOEXEC);
347	}
348	if (LogFile != -1 && status == NOCONN) {
349		SyslogAddr.sun_len = sizeof(SyslogAddr);
350		SyslogAddr.sun_family = AF_UNIX;
351
352		/*
353		 * First try priveleged socket. If no success,
354		 * then try default socket.
355		 */
356		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG_PRIV,
357		    sizeof SyslogAddr.sun_path);
358		if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
359		    sizeof(SyslogAddr)) != -1)
360			status = CONNPRIV;
361
362		if (status == NOCONN) {
363			(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
364			    sizeof SyslogAddr.sun_path);
365			if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
366			    sizeof(SyslogAddr)) != -1)
367				status = CONNDEF;
368		}
369
370		if (status == NOCONN) {
371			/*
372			 * Try the old "/dev/log" path, for backward
373			 * compatibility.
374			 */
375			(void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
376			    sizeof SyslogAddr.sun_path);
377			if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
378			    sizeof(SyslogAddr)) != -1)
379				status = CONNDEF;
380		}
381
382		if (status == NOCONN) {
383			(void)_close(LogFile);
384			LogFile = -1;
385		}
386	}
387}
388
389static void
390openlog_unlocked(const char *ident, int logstat, int logfac)
391{
392	if (ident != NULL)
393		LogTag = ident;
394	LogStat = logstat;
395	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
396		LogFacility = logfac;
397
398	if (LogStat & LOG_NDELAY)	/* open immediately */
399		connectlog();
400
401	opened = 1;	/* ident and facility has been set */
402}
403
404void
405openlog(const char *ident, int logstat, int logfac)
406{
407	THREAD_LOCK();
408	openlog_unlocked(ident, logstat, logfac);
409	THREAD_UNLOCK();
410}
411
412
413void
414closelog(void)
415{
416	THREAD_LOCK();
417	if (LogFile != -1) {
418		(void)_close(LogFile);
419		LogFile = -1;
420	}
421	LogTag = NULL;
422	status = NOCONN;
423	THREAD_UNLOCK();
424}
425
426/* setlogmask -- set the log mask level */
427int
428setlogmask(int pmask)
429{
430	int omask;
431
432	THREAD_LOCK();
433	omask = LogMask;
434	if (pmask != 0)
435		LogMask = pmask;
436	THREAD_UNLOCK();
437	return (omask);
438}
439