xref: /freebsd/contrib/pf/pflogd/pflogd.c (revision 22d6889b4d3eb8a5cb2aaaefe5bedb40e885b425) 
1 /*	$OpenBSD: pflogd.c,v 1.27 2004/02/13 19:01:57 otto Exp $	*/
2 
3 /*
4  * Copyright (c) 2001 Theo de Raadt
5  * Copyright (c) 2001 Can Erkin Acar
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  *    - Redistributions of source code must retain the above copyright
13  *      notice, this list of conditions and the following disclaimer.
14  *    - Redistributions in binary form must reproduce the above
15  *      copyright notice, this list of conditions and the following
16  *      disclaimer in the documentation and/or other materials provided
17  *      with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
22  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
23  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
25  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
26  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
27  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
29  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include <sys/types.h>
37 #include <sys/ioctl.h>
38 #include <sys/file.h>
39 #include <sys/stat.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44 #include <pcap-int.h>
45 #include <pcap.h>
46 #include <syslog.h>
47 #include <signal.h>
48 #include <errno.h>
49 #include <stdarg.h>
50 #include <fcntl.h>
51 #ifdef __FreeBSD__
52 #include "pidfile.h"
53 #else
54 #include <util.h>
55 #endif
56 
57 #include "pflogd.h"
58 
59 pcap_t *hpcap;
60 static FILE *dpcap;
61 
62 int Debug = 0;
63 static int snaplen = DEF_SNAPLEN;
64 static int cur_snaplen = DEF_SNAPLEN;
65 
66 volatile sig_atomic_t gotsig_close, gotsig_alrm, gotsig_hup;
67 
68 char *filename = PFLOGD_LOG_FILE;
69 char *interface = PFLOGD_DEFAULT_IF;
70 char *filter = NULL;
71 
72 char errbuf[PCAP_ERRBUF_SIZE];
73 
74 int log_debug = 0;
75 unsigned int delay = FLUSH_DELAY;
76 
77 char *copy_argv(char * const *);
78 void  dump_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
79 void  dump_packet_nobuf(u_char *, const struct pcap_pkthdr *, const u_char *);
80 int   flush_buffer(FILE *);
81 int   init_pcap(void);
82 void  logmsg(int, const char *, ...);
83 void  purge_buffer(void);
84 int   reset_dump(void);
85 int   scan_dump(FILE *, off_t);
86 int   set_snaplen(int);
87 void  set_suspended(int);
88 void  sig_alrm(int);
89 void  sig_close(int);
90 void  sig_hup(int);
91 void  usage(void);
92 
93 /* buffer must always be greater than snaplen */
94 static int    bufpkt = 0;	/* number of packets in buffer */
95 static int    buflen = 0;	/* allocated size of buffer */
96 static char  *buffer = NULL;	/* packet buffer */
97 static char  *bufpos = NULL;	/* position in buffer */
98 static int    bufleft = 0;	/* bytes left in buffer */
99 
100 /* if error, stop logging but count dropped packets */
101 static int suspended = -1;
102 static long packets_dropped = 0;
103 
104 void
105 set_suspended(int s)
106 {
107 	if (suspended == s)
108 		return;
109 
110 	suspended = s;
111 	setproctitle("[%s] -s %d -f %s",
112             suspended ? "suspended" : "running", cur_snaplen, filename);
113 }
114 
115 char *
116 copy_argv(char * const *argv)
117 {
118 	size_t len = 0, n;
119 	char *buf;
120 
121 	if (argv == NULL)
122 		return (NULL);
123 
124 	for (n = 0; argv[n]; n++)
125 		len += strlen(argv[n])+1;
126 	if (len == 0)
127 		return (NULL);
128 
129 	buf = malloc(len);
130 	if (buf == NULL)
131 		return (NULL);
132 
133 	strlcpy(buf, argv[0], len);
134 	for (n = 1; argv[n]; n++) {
135 		strlcat(buf, " ", len);
136 		strlcat(buf, argv[n], len);
137 	}
138 	return (buf);
139 }
140 
141 void
142 logmsg(int pri, const char *message, ...)
143 {
144 	va_list ap;
145 	va_start(ap, message);
146 
147 	if (log_debug) {
148 		vfprintf(stderr, message, ap);
149 		fprintf(stderr, "\n");
150 	} else
151 		vsyslog(pri, message, ap);
152 	va_end(ap);
153 }
154 
155 #ifdef __FreeBSD__
156 __dead2 void
157 #else
158 __dead void
159 #endif
160 usage(void)
161 {
162 	fprintf(stderr, "usage: pflogd [-Dx] [-d delay] [-f filename] ");
163 	fprintf(stderr, "[-s snaplen] [expression]\n");
164 	exit(1);
165 }
166 
167 void
168 sig_close(int sig)
169 {
170 	gotsig_close = 1;
171 }
172 
173 void
174 sig_hup(int sig)
175 {
176 	gotsig_hup = 1;
177 }
178 
179 void
180 sig_alrm(int sig)
181 {
182 	gotsig_alrm = 1;
183 }
184 
185 void
186 set_pcap_filter(void)
187 {
188 	struct bpf_program bprog;
189 
190 	if (pcap_compile(hpcap, &bprog, filter, PCAP_OPT_FIL, 0) < 0)
191 		logmsg(LOG_WARNING, "%s", pcap_geterr(hpcap));
192 	else {
193 		if (pcap_setfilter(hpcap, &bprog) < 0)
194 			logmsg(LOG_WARNING, "%s", pcap_geterr(hpcap));
195 		pcap_freecode(&bprog);
196 	}
197 }
198 
199 int
200 init_pcap(void)
201 {
202 	hpcap = pcap_open_live(interface, snaplen, 1, PCAP_TO_MS, errbuf);
203 	if (hpcap == NULL) {
204 		logmsg(LOG_ERR, "Failed to initialize: %s", errbuf);
205 		return (-1);
206 	}
207 
208 	if (pcap_datalink(hpcap) != DLT_PFLOG) {
209 		logmsg(LOG_ERR, "Invalid datalink type");
210 		pcap_close(hpcap);
211 		hpcap = NULL;
212 		return (-1);
213 	}
214 
215 	set_pcap_filter();
216 
217 	cur_snaplen = snaplen = pcap_snapshot(hpcap);
218 
219 #ifdef __FreeBSD__
220 	/* We can not lock bpf devices ... yet */
221 #else
222 	/* lock */
223 	if (ioctl(pcap_fileno(hpcap), BIOCLOCK) < 0) {
224 		logmsg(LOG_ERR, "BIOCLOCK: %s", strerror(errno));
225 		return (-1);
226 	}
227 #endif
228 
229 	return (0);
230 }
231 
232 int
233 set_snaplen(int snap)
234 {
235 	if (priv_set_snaplen(snap))
236 		return (1);
237 
238 	if (cur_snaplen > snap)
239 		purge_buffer();
240 
241 	cur_snaplen = snap;
242 
243 	return (0);
244 }
245 
246 int
247 reset_dump(void)
248 {
249 	struct pcap_file_header hdr;
250 	struct stat st;
251 	int fd;
252 	FILE *fp;
253 
254 	if (hpcap == NULL)
255 		return (-1);
256 
257 	if (dpcap) {
258 		flush_buffer(dpcap);
259 		fclose(dpcap);
260 		dpcap = NULL;
261 	}
262 
263 	/*
264 	 * Basically reimplement pcap_dump_open() because it truncates
265 	 * files and duplicates headers and such.
266 	 */
267 	fd = priv_open_log();
268 	if (fd < 0)
269 		return (1);
270 
271 	fp = fdopen(fd, "a+");
272 
273 	if (fp == NULL) {
274 		logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
275 		return (1);
276 	}
277 	if (fstat(fileno(fp), &st) == -1) {
278 		logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
279 		return (1);
280 	}
281 
282 	/* set FILE unbuffered, we do our own buffering */
283 	if (setvbuf(fp, NULL, _IONBF, 0)) {
284 		logmsg(LOG_ERR, "Failed to set output buffers");
285 		return (1);
286 	}
287 
288 #define TCPDUMP_MAGIC 0xa1b2c3d4
289 
290 	if (st.st_size == 0) {
291 		if (snaplen != cur_snaplen) {
292 			logmsg(LOG_NOTICE, "Using snaplen %d", snaplen);
293 			if (set_snaplen(snaplen)) {
294 				logmsg(LOG_WARNING,
295 				    "Failed, using old settings");
296 			}
297 		}
298 		hdr.magic = TCPDUMP_MAGIC;
299 		hdr.version_major = PCAP_VERSION_MAJOR;
300 		hdr.version_minor = PCAP_VERSION_MINOR;
301 		hdr.thiszone = hpcap->tzoff;
302 		hdr.snaplen = hpcap->snapshot;
303 		hdr.sigfigs = 0;
304 		hdr.linktype = hpcap->linktype;
305 
306 		if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
307 			fclose(fp);
308 			return (1);
309 		}
310 	} else if (scan_dump(fp, st.st_size)) {
311 		/* XXX move file and continue? */
312 		fclose(fp);
313 		return (1);
314 	}
315 
316 	dpcap = fp;
317 
318 	set_suspended(0);
319 	flush_buffer(fp);
320 
321 	return (0);
322 }
323 
324 int
325 scan_dump(FILE *fp, off_t size)
326 {
327 	struct pcap_file_header hdr;
328 #ifdef __FreeBSD__
329 	struct pcap_sf_pkthdr ph;
330 #else
331 	struct pcap_pkthdr ph;
332 #endif
333 	off_t pos;
334 
335 	/*
336 	 * Must read the file, compare the header against our new
337 	 * options (in particular, snaplen) and adjust our options so
338 	 * that we generate a correct file. Furthermore, check the file
339 	 * for consistency so that we can append safely.
340 	 *
341 	 * XXX this may take a long time for large logs.
342 	 */
343 	(void) fseek(fp, 0L, SEEK_SET);
344 
345 	if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
346 		logmsg(LOG_ERR, "Short file header");
347 		return (1);
348 	}
349 
350 	if (hdr.magic != TCPDUMP_MAGIC ||
351 	    hdr.version_major != PCAP_VERSION_MAJOR ||
352 	    hdr.version_minor != PCAP_VERSION_MINOR ||
353 	    hdr.linktype != hpcap->linktype ||
354 	    hdr.snaplen > PFLOGD_MAXSNAPLEN) {
355 		logmsg(LOG_ERR, "Invalid/incompatible log file, move it away");
356 		return (1);
357 	}
358 
359 	pos = sizeof(hdr);
360 
361 	while (!feof(fp)) {
362 		off_t len = fread((char *)&ph, 1, sizeof(ph), fp);
363 		if (len == 0)
364 			break;
365 
366 		if (len != sizeof(ph))
367 			goto error;
368 		if (ph.caplen > hdr.snaplen || ph.caplen > PFLOGD_MAXSNAPLEN)
369 			goto error;
370 		pos += sizeof(ph) + ph.caplen;
371 		if (pos > size)
372 			goto error;
373 		fseek(fp, ph.caplen, SEEK_CUR);
374 	}
375 
376 	if (pos != size)
377 		goto error;
378 
379 	if (hdr.snaplen != cur_snaplen) {
380 		logmsg(LOG_WARNING,
381 		       "Existing file has different snaplen %u, using it",
382 		       hdr.snaplen);
383 		if (set_snaplen(hdr.snaplen)) {
384 			logmsg(LOG_WARNING,
385 			       "Failed, using old settings, offset %llu",
386 			       (unsigned long long) size);
387 		}
388 	}
389 
390 	return (0);
391 
392  error:
393 	logmsg(LOG_ERR, "Corrupted log file.");
394 	return (1);
395 }
396 
397 /* dump a packet directly to the stream, which is unbuffered */
398 void
399 dump_packet_nobuf(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
400 {
401 	FILE *f = (FILE *)user;
402 #ifdef __FreeBSD__
403 	struct pcap_sf_pkthdr sh;
404 #endif
405 
406 	if (suspended) {
407 		packets_dropped++;
408 		return;
409 	}
410 
411 #ifdef __FreeBSD__
412 	sh.ts.tv_sec = (bpf_int32)h->ts.tv_sec;
413 	sh.ts.tv_usec = (bpf_int32)h->ts.tv_usec;
414 	sh.caplen = h->caplen;
415 	sh.len = h->len;
416 
417 	if (fwrite((char *)&sh, sizeof(sh), 1, f) != 1) {
418 #else
419 	if (fwrite((char *)h, sizeof(*h), 1, f) != 1) {
420 #endif
421 		/* try to undo header to prevent corruption */
422 		off_t pos = ftello(f);
423 #ifdef __FreeBSD__
424 		if (pos < sizeof(sh) ||
425 		    ftruncate(fileno(f), pos - sizeof(sh))) {
426 #else
427 		if (pos < sizeof(*h) ||
428 		    ftruncate(fileno(f), pos - sizeof(*h))) {
429 #endif
430 			logmsg(LOG_ERR, "Write failed, corrupted logfile!");
431 			set_suspended(1);
432 			gotsig_close = 1;
433 			return;
434 		}
435 		goto error;
436 	}
437 
438 	if (fwrite((char *)sp, h->caplen, 1, f) != 1)
439 		goto error;
440 
441 	return;
442 
443 error:
444 	set_suspended(1);
445 	packets_dropped ++;
446 	logmsg(LOG_ERR, "Logging suspended: fwrite: %s", strerror(errno));
447 }
448 
449 int
450 flush_buffer(FILE *f)
451 {
452 	off_t offset;
453 	int len = bufpos - buffer;
454 
455 	if (len <= 0)
456 		return (0);
457 
458 	offset = ftello(f);
459 	if (offset == (off_t)-1) {
460 		set_suspended(1);
461 		logmsg(LOG_ERR, "Logging suspended: ftello: %s",
462 		    strerror(errno));
463 		return (1);
464 	}
465 
466 	if (fwrite(buffer, len, 1, f) != 1) {
467 		set_suspended(1);
468 		logmsg(LOG_ERR, "Logging suspended: fwrite: %s",
469 		    strerror(errno));
470 		ftruncate(fileno(f), offset);
471 		return (1);
472 	}
473 
474 	set_suspended(0);
475 	bufpos = buffer;
476 	bufleft = buflen;
477 	bufpkt = 0;
478 
479 	return (0);
480 }
481 
482 void
483 purge_buffer(void)
484 {
485 	packets_dropped += bufpkt;
486 
487 	set_suspended(0);
488 	bufpos = buffer;
489 	bufleft = buflen;
490 	bufpkt = 0;
491 }
492 
493 /* append packet to the buffer, flushing if necessary */
494 void
495 dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
496 {
497 	FILE *f = (FILE *)user;
498 #ifdef __FreeBSD__
499 	struct pcap_sf_pkthdr sh;
500 	size_t len = sizeof(sh) + h->caplen;
501 #else
502 	size_t len = sizeof(*h) + h->caplen;
503 #endif
504 
505 	if (len < sizeof(*h) || h->caplen > (size_t)cur_snaplen) {
506 		logmsg(LOG_NOTICE, "invalid size %u (%u/%u), packet dropped",
507 		       len, cur_snaplen, snaplen);
508 		packets_dropped++;
509 		return;
510 	}
511 
512 	if (len <= bufleft)
513 		goto append;
514 
515 	if (suspended) {
516 		packets_dropped++;
517 		return;
518 	}
519 
520 	if (flush_buffer(f)) {
521 		packets_dropped++;
522 		return;
523 	}
524 
525 	if (len > bufleft) {
526 		dump_packet_nobuf(user, h, sp);
527 		return;
528 	}
529 
530  append:
531 #ifdef __FreeBSD__
532  	sh.ts.tv_sec = (bpf_int32)h->ts.tv_sec;
533  	sh.ts.tv_usec = (bpf_int32)h->ts.tv_usec;
534 	sh.caplen = h->caplen;
535 	sh.len = h->len;
536 
537 	memcpy(bufpos, &sh, sizeof(sh));
538 	memcpy(bufpos + sizeof(sh), sp, h->caplen);
539 #else
540 	memcpy(bufpos, h, sizeof(*h));
541 	memcpy(bufpos + sizeof(*h), sp, h->caplen);
542 #endif
543 
544 	bufpos += len;
545 	bufleft -= len;
546 	bufpkt++;
547 
548 	return;
549 }
550 
551 int
552 main(int argc, char **argv)
553 {
554 	struct pcap_stat pstat;
555 	int ch, np, Xflag = 0;
556 	pcap_handler phandler = dump_packet;
557 
558 #ifdef __FreeBSD__
559 	/* another ?paranoid? safety measure we do not have */
560 #else
561 	closefrom(STDERR_FILENO + 1);
562 #endif
563 
564 	while ((ch = getopt(argc, argv, "Dxd:s:f:")) != -1) {
565 		switch (ch) {
566 		case 'D':
567 			Debug = 1;
568 			break;
569 		case 'd':
570 			delay = atoi(optarg);
571 			if (delay < 5 || delay > 60*60)
572 				usage();
573 			break;
574 		case 'f':
575 			filename = optarg;
576 			break;
577 		case 's':
578 			snaplen = atoi(optarg);
579 			if (snaplen <= 0)
580 				snaplen = DEF_SNAPLEN;
581 			if (snaplen > PFLOGD_MAXSNAPLEN)
582 				snaplen = PFLOGD_MAXSNAPLEN;
583 			break;
584 		case 'x':
585 			Xflag++;
586 			break;
587 		default:
588 			usage();
589 		}
590 
591 	}
592 
593 	log_debug = Debug;
594 	argc -= optind;
595 	argv += optind;
596 
597 	if (!Debug) {
598 		openlog("pflogd", LOG_PID | LOG_CONS, LOG_DAEMON);
599 		if (daemon(0, 0)) {
600 			logmsg(LOG_WARNING, "Failed to become daemon: %s",
601 			    strerror(errno));
602 		}
603 		pidfile(NULL);
604 	}
605 
606 	(void)umask(S_IRWXG | S_IRWXO);
607 
608 	/* filter will be used by the privileged process */
609 	if (argc) {
610 		filter = copy_argv(argv);
611 		if (filter == NULL)
612 			logmsg(LOG_NOTICE, "Failed to form filter expression");
613 	}
614 
615 	/* initialize pcap before dropping privileges */
616 	if (init_pcap()) {
617 		logmsg(LOG_ERR, "Exiting, init failure");
618 		exit(1);
619 	}
620 
621 	/* Privilege separation begins here */
622 	if (priv_init()) {
623 		logmsg(LOG_ERR, "unable to privsep");
624 		exit(1);
625 	}
626 
627 	setproctitle("[initializing]");
628 	/* Process is now unprivileged and inside a chroot */
629 	signal(SIGTERM, sig_close);
630 	signal(SIGINT, sig_close);
631 	signal(SIGQUIT, sig_close);
632 	signal(SIGALRM, sig_alrm);
633 	signal(SIGHUP, sig_hup);
634 	alarm(delay);
635 
636 	buffer = malloc(PFLOGD_BUFSIZE);
637 
638 	if (buffer == NULL) {
639 		logmsg(LOG_WARNING, "Failed to allocate output buffer");
640 		phandler = dump_packet_nobuf;
641 	} else {
642 		bufleft = buflen = PFLOGD_BUFSIZE;
643 		bufpos = buffer;
644 		bufpkt = 0;
645 	}
646 
647 	if (reset_dump()) {
648 		if (Xflag)
649 			return (1);
650 
651 		logmsg(LOG_ERR, "Logging suspended: open error");
652 		set_suspended(1);
653 	} else if (Xflag)
654 		return (0);
655 
656 	while (1) {
657 		np = pcap_dispatch(hpcap, PCAP_NUM_PKTS,
658 		    dump_packet, (u_char *)dpcap);
659 		if (np < 0) {
660 #ifdef __FreeBSD__
661 			if (errno == ENXIO) {
662 				logmsg(LOG_ERR,
663 				    "Device not/no longer configured");
664 				break;
665 			}
666 #endif
667 			logmsg(LOG_NOTICE, "%s", pcap_geterr(hpcap));
668 		}
669 
670 		if (gotsig_close)
671 			break;
672 		if (gotsig_hup) {
673 			if (reset_dump()) {
674 				logmsg(LOG_ERR,
675 				    "Logging suspended: open error");
676 				set_suspended(1);
677 			}
678 			gotsig_hup = 0;
679 		}
680 
681 		if (gotsig_alrm) {
682 			if (dpcap)
683 				flush_buffer(dpcap);
684 			gotsig_alrm = 0;
685 			alarm(delay);
686 		}
687 	}
688 
689 	logmsg(LOG_NOTICE, "Exiting");
690 	if (dpcap) {
691 		flush_buffer(dpcap);
692 		fclose(dpcap);
693 	}
694 	purge_buffer();
695 
696 	if (pcap_stats(hpcap, &pstat) < 0)
697 		logmsg(LOG_WARNING, "Reading stats: %s", pcap_geterr(hpcap));
698 	else
699 		logmsg(LOG_NOTICE,
700 		    "%u packets received, %u/%u dropped (kernel/pflogd)",
701 		    pstat.ps_recv, pstat.ps_drop, packets_dropped);
702 
703 	pcap_close(hpcap);
704 	if (!Debug)
705 		closelog();
706 	return (0);
707 }
708