1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1983, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include "namespace.h"
33 #include <sys/param.h>
34 #include <sys/socket.h>
35 #include <sys/syslog.h>
36 #include <sys/time.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 <stdbool.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <time.h>
50 #include <unistd.h>
51
52 #include <stdarg.h>
53 #include "un-namespace.h"
54
55 #include "libc_private.h"
56
57 /* Maximum number of characters of syslog message */
58 #define MAXLINE 8192
59
60 static int LogFile = -1; /* fd for log */
61 static bool connected; /* have done connect */
62 static int opened; /* have done openlog() */
63 static int LogStat = 0; /* status bits, set by openlog() */
64 static pid_t LogPid = -1; /* process id to tag the entry with */
65 static const char *LogTag = NULL; /* string to tag the entry with */
66 static int LogTagLength = -1; /* usable part of LogTag */
67 static int LogFacility = LOG_USER; /* default facility code */
68 static int LogMask = 0xff; /* mask of priorities to be logged */
69 static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER;
70
71 #define THREAD_LOCK() \
72 do { \
73 if (__isthreaded) _pthread_mutex_lock(&syslog_mutex); \
74 } while(0)
75 #define THREAD_UNLOCK() \
76 do { \
77 if (__isthreaded) _pthread_mutex_unlock(&syslog_mutex); \
78 } while(0)
79
80 /* RFC5424 defined value. */
81 #define NILVALUE "-"
82
83 static void disconnectlog(void); /* disconnect from syslogd */
84 static void connectlog(void); /* (re)connect to syslogd */
85 static void openlog_unlocked(const char *, int, int);
86 static void parse_tag(void); /* parse ident[NNN] if needed */
87
88 /*
89 * Format of the magic cookie passed through the stdio hook
90 */
91 struct bufcookie {
92 char *base; /* start of buffer */
93 int left;
94 };
95
96 /*
97 * stdio write hook for writing to a static string buffer
98 * XXX: Maybe one day, dynamically allocate it so that the line length
99 * is `unlimited'.
100 */
101 static int
writehook(void * cookie,const char * buf,int len)102 writehook(void *cookie, const char *buf, int len)
103 {
104 struct bufcookie *h; /* private `handle' */
105
106 h = (struct bufcookie *)cookie;
107 if (len > h->left) {
108 /* clip in case of wraparound */
109 len = h->left;
110 }
111 if (len > 0) {
112 (void)memcpy(h->base, buf, len); /* `write' it. */
113 h->base += len;
114 h->left -= len;
115 }
116 return len;
117 }
118
119 /*
120 * syslog, vsyslog --
121 * print message on log file; output is intended for syslogd(8).
122 */
123 void
syslog(int pri,const char * fmt,...)124 syslog(int pri, const char *fmt, ...)
125 {
126 va_list ap;
127
128 va_start(ap, fmt);
129 vsyslog(pri, fmt, ap);
130 va_end(ap);
131 }
132
133 static void
vsyslog1(int pri,const char * fmt,va_list ap)134 vsyslog1(int pri, const char *fmt, va_list ap)
135 {
136 struct timeval now;
137 struct tm tm;
138 char ch, *p;
139 long tz_offset;
140 int cnt, fd, saved_errno;
141 char hostname[MAXHOSTNAMELEN], *stdp, tbuf[MAXLINE], fmt_cpy[MAXLINE],
142 errstr[64], tz_sign;
143 FILE *fp, *fmt_fp;
144 struct bufcookie tbuf_cookie;
145 struct bufcookie fmt_cookie;
146
147 #define INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
148 /* Check for invalid bits. */
149 if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
150 syslog(INTERNALLOG,
151 "syslog: unknown facility/priority: %x", pri);
152 pri &= LOG_PRIMASK|LOG_FACMASK;
153 }
154
155 saved_errno = errno;
156
157 /* Check priority against setlogmask values. */
158 if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
159 return;
160
161 /* Set default facility if none specified. */
162 if ((pri & LOG_FACMASK) == 0)
163 pri |= LogFacility;
164
165 /* Create the primary stdio hook */
166 tbuf_cookie.base = tbuf;
167 tbuf_cookie.left = sizeof(tbuf);
168 fp = fwopen(&tbuf_cookie, writehook);
169 if (fp == NULL)
170 return;
171
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) {
178 tz_sign = '-';
179 tz_offset = -tm.tm_gmtoff;
180 } else {
181 tz_sign = '+';
182 tz_offset = tm.tm_gmtoff;
183 }
184
185 (void)fprintf(fp,
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);
192 } else
193 (void)fputs(NILVALUE " ", fp);
194 /* Hostname. */
195 (void)gethostname(hostname, sizeof(hostname));
196 (void)fprintf(fp, "%s ",
197 hostname[0] == '\0' ? NILVALUE : hostname);
198 if (LogStat & LOG_PERROR) {
199 /* Transfer to string buffer */
200 (void)fflush(fp);
201 stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
202 }
203 /* Application name. */
204 if (LogTag == NULL)
205 LogTag = _getprogname();
206 else if (LogTagLength == -1)
207 parse_tag();
208 if (LogTagLength > 0)
209 (void)fprintf(fp, "%.*s ", LogTagLength, LogTag);
210 else
211 (void)fprintf(fp, "%s ", LogTag == NULL ? NILVALUE : LogTag);
212 /*
213 * Provide the process ID regardless of whether LOG_PID has been
214 * specified, as it provides valuable information. Many
215 * applications tend not to use this, even though they should.
216 */
217 if (LogTagLength <= 0)
218 LogPid = getpid();
219 (void)fprintf(fp, "%d ", (int)LogPid);
220 /* Message ID. */
221 (void)fputs(NILVALUE " ", fp);
222 /* Structured data. */
223 (void)fputs(NILVALUE " ", fp);
224
225 /* Check to see if we can skip expanding the %m */
226 if (strstr(fmt, "%m")) {
227
228 /* Create the second stdio hook */
229 fmt_cookie.base = fmt_cpy;
230 fmt_cookie.left = sizeof(fmt_cpy) - 1;
231 fmt_fp = fwopen(&fmt_cookie, writehook);
232 if (fmt_fp == NULL) {
233 fclose(fp);
234 return;
235 }
236
237 /*
238 * Substitute error message for %m. Be careful not to
239 * molest an escaped percent "%%m". We want to pass it
240 * on untouched as the format is later parsed by vfprintf.
241 */
242 for ( ; (ch = *fmt); ++fmt) {
243 if (ch == '%' && fmt[1] == 'm') {
244 ++fmt;
245 strerror_r(saved_errno, errstr, sizeof(errstr));
246 fputs(errstr, fmt_fp);
247 } else if (ch == '%' && fmt[1] == '%') {
248 ++fmt;
249 fputc(ch, fmt_fp);
250 fputc(ch, fmt_fp);
251 } else {
252 fputc(ch, fmt_fp);
253 }
254 }
255
256 /* Null terminate if room */
257 fputc(0, fmt_fp);
258 fclose(fmt_fp);
259
260 /* Guarantee null termination */
261 fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
262
263 fmt = fmt_cpy;
264 }
265
266 /* Message. */
267 (void)vfprintf(fp, fmt, ap);
268 (void)fclose(fp);
269
270 cnt = sizeof(tbuf) - tbuf_cookie.left;
271
272 /* Remove a trailing newline */
273 if (tbuf[cnt - 1] == '\n')
274 cnt--;
275
276 /* Output to stderr if requested. */
277 if (LogStat & LOG_PERROR) {
278 struct iovec iov[2];
279 struct iovec *v = iov;
280
281 v->iov_base = stdp;
282 v->iov_len = cnt - (stdp - tbuf);
283 ++v;
284 v->iov_base = "\n";
285 v->iov_len = 1;
286 (void)_writev(STDERR_FILENO, iov, 2);
287 }
288
289 /* Get connected, output the message to the local logger. */
290 if (!opened)
291 openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
292 connectlog();
293
294 /*
295 * If the send() failed, there are two likely scenarios:
296 * 1) syslogd was restarted. In this case make one (only) attempt
297 * to reconnect.
298 * 2) We filled our buffer due to syslogd not being able to read
299 * as fast as we write. In this case prefer to lose the current
300 * message rather than whole buffer of previously logged data.
301 */
302 if (send(LogFile, tbuf, cnt, 0) < 0) {
303 if (errno != ENOBUFS) {
304 disconnectlog();
305 connectlog();
306 if (send(LogFile, tbuf, cnt, 0) >= 0)
307 return;
308 }
309 } else
310 return;
311
312 /*
313 * Output the message to the console; try not to block
314 * as a blocking console should not stop other processes.
315 * Make sure the error reported is the one from the syslogd failure.
316 */
317 if (LogStat & LOG_CONS &&
318 (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >=
319 0) {
320 struct iovec iov[2];
321 struct iovec *v = iov;
322
323 p = strchr(tbuf, '>') + 3;
324 v->iov_base = p;
325 v->iov_len = cnt - (p - tbuf);
326 ++v;
327 v->iov_base = "\r\n";
328 v->iov_len = 2;
329 (void)_writev(fd, iov, 2);
330 (void)_close(fd);
331 }
332 }
333
334 static void
syslog_cancel_cleanup(void * arg __unused)335 syslog_cancel_cleanup(void *arg __unused)
336 {
337
338 THREAD_UNLOCK();
339 }
340
341 void
vsyslog(int pri,const char * fmt,va_list ap)342 vsyslog(int pri, const char *fmt, va_list ap)
343 {
344
345 THREAD_LOCK();
346 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
347 vsyslog1(pri, fmt, ap);
348 pthread_cleanup_pop(1);
349 }
350
351 /* Should be called with mutex acquired */
352 static void
disconnectlog(void)353 disconnectlog(void)
354 {
355 /*
356 * If the user closed the FD and opened another in the same slot,
357 * that's their problem. They should close it before calling on
358 * system services.
359 */
360 if (LogFile != -1) {
361 _close(LogFile);
362 LogFile = -1;
363 }
364 connected = false; /* retry connect */
365 }
366
367 /* Should be called with mutex acquired */
368 static void
connectlog(void)369 connectlog(void)
370 {
371 struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */
372
373 if (LogFile == -1) {
374 socklen_t len;
375
376 if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
377 0)) == -1)
378 return;
379 if (_getsockopt(LogFile, SOL_SOCKET, SO_SNDBUF, &len,
380 &(socklen_t){sizeof(len)}) == 0) {
381 if (len < MAXLINE) {
382 len = MAXLINE;
383 (void)_setsockopt(LogFile, SOL_SOCKET, SO_SNDBUF,
384 &len, sizeof(len));
385 }
386 }
387 }
388 if (!connected) {
389 SyslogAddr.sun_len = sizeof(SyslogAddr);
390 SyslogAddr.sun_family = AF_UNIX;
391
392 (void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
393 sizeof SyslogAddr.sun_path);
394 if (_connect(LogFile, (struct sockaddr *)&SyslogAddr,
395 sizeof(SyslogAddr)) != -1)
396 connected = true;
397 else {
398 (void)_close(LogFile);
399 LogFile = -1;
400 }
401 }
402 }
403
404 static void
openlog_unlocked(const char * ident,int logstat,int logfac)405 openlog_unlocked(const char *ident, int logstat, int logfac)
406 {
407 if (ident != NULL) {
408 LogTag = ident;
409 LogTagLength = -1;
410 }
411 LogStat = logstat;
412 parse_tag();
413 if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
414 LogFacility = logfac;
415
416 if (LogStat & LOG_NDELAY) /* open immediately */
417 connectlog();
418
419 opened = 1; /* ident and facility has been set */
420 }
421
422 void
openlog(const char * ident,int logstat,int logfac)423 openlog(const char *ident, int logstat, int logfac)
424 {
425
426 THREAD_LOCK();
427 pthread_cleanup_push(syslog_cancel_cleanup, NULL);
428 openlog_unlocked(ident, logstat, logfac);
429 pthread_cleanup_pop(1);
430 }
431
432
433 void
closelog(void)434 closelog(void)
435 {
436 THREAD_LOCK();
437 if (LogFile != -1) {
438 (void)_close(LogFile);
439 LogFile = -1;
440 }
441 LogTag = NULL;
442 LogTagLength = -1;
443 connected = false;
444 THREAD_UNLOCK();
445 }
446
447 /* setlogmask -- set the log mask level */
448 int
setlogmask(int pmask)449 setlogmask(int pmask)
450 {
451 int omask;
452
453 THREAD_LOCK();
454 omask = LogMask;
455 if (pmask != 0)
456 LogMask = pmask;
457 THREAD_UNLOCK();
458 return (omask);
459 }
460
461 /*
462 * Obtain LogPid from LogTag formatted as per RFC 3164,
463 * Section 5.3 Originating Process Information:
464 *
465 * ident[NNN]
466 */
467 static void
parse_tag(void)468 parse_tag(void)
469 {
470 char *begin, *end, *p;
471 pid_t pid;
472
473 if (LogTag == NULL || (LogStat & LOG_PID) != 0)
474 return;
475 /*
476 * LogTagLength is -1 if LogTag was not parsed yet.
477 * Avoid multiple passes over same LogTag.
478 */
479 LogTagLength = 0;
480
481 /* Check for presence of opening [ and non-empty ident. */
482 if ((begin = strchr(LogTag, '[')) == NULL || begin == LogTag)
483 return;
484 /* Check for presence of closing ] at the very end and non-empty pid. */
485 if ((end = strchr(begin + 1, ']')) == NULL || end[1] != 0 ||
486 (end - begin) < 2)
487 return;
488
489 /* Check for pid to contain digits only. */
490 pid = (pid_t)strtol(begin + 1, &p, 10);
491 if (p != end)
492 return;
493
494 LogPid = pid;
495 LogTagLength = begin - LogTag;
496 }
497