pflogd.c revision 149380 
1/*	$OpenBSD: pflogd.c,v 1.33 2005/02/09 12:09:30 henning 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: head/contrib/pf/pflogd/pflogd.c 149380 2005-08-23 00:03:58Z csjp $");
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
59pcap_t *hpcap;
60static FILE *dpcap;
61
62int Debug = 0;
63static int snaplen = DEF_SNAPLEN;
64static int cur_snaplen = DEF_SNAPLEN;
65
66volatile sig_atomic_t gotsig_close, gotsig_alrm, gotsig_hup;
67
68char *filename = PFLOGD_LOG_FILE;
69char *interface = PFLOGD_DEFAULT_IF;
70char *filter = NULL;
71
72char errbuf[PCAP_ERRBUF_SIZE];
73
74int log_debug = 0;
75unsigned int delay = FLUSH_DELAY;
76
77char *copy_argv(char * const *);
78void  dump_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
79void  dump_packet_nobuf(u_char *, const struct pcap_pkthdr *, const u_char *);
80int   flush_buffer(FILE *);
81int   init_pcap(void);
82void  logmsg(int, const char *, ...);
83void  purge_buffer(void);
84int   reset_dump(void);
85int   scan_dump(FILE *, off_t);
86int   set_snaplen(int);
87void  set_suspended(int);
88void  sig_alrm(int);
89void  sig_close(int);
90void  sig_hup(int);
91void  usage(void);
92
93/* buffer must always be greater than snaplen */
94static int    bufpkt = 0;	/* number of packets in buffer */
95static int    buflen = 0;	/* allocated size of buffer */
96static char  *buffer = NULL;	/* packet buffer */
97static char  *bufpos = NULL;	/* position in buffer */
98static int    bufleft = 0;	/* bytes left in buffer */
99
100/* if error, stop logging but count dropped packets */
101static int suspended = -1;
102static long packets_dropped = 0;
103
104void
105set_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
115char *
116copy_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
141void
142logmsg(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
160usage(void)
161{
162	fprintf(stderr, "usage: pflogd [-Dx] [-d delay] [-f filename] ");
163	fprintf(stderr, "[-s snaplen] [expression]\n");
164	exit(1);
165}
166
167void
168sig_close(int sig)
169{
170	gotsig_close = 1;
171}
172
173void
174sig_hup(int sig)
175{
176	gotsig_hup = 1;
177}
178
179void
180sig_alrm(int sig)
181{
182	gotsig_alrm = 1;
183}
184
185void
186set_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
199int
200init_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	/* lock */
220	if (ioctl(pcap_fileno(hpcap), BIOCLOCK) < 0) {
221		logmsg(LOG_ERR, "BIOCLOCK: %s", strerror(errno));
222		return (-1);
223	}
224
225	return (0);
226}
227
228int
229set_snaplen(int snap)
230{
231	if (priv_set_snaplen(snap))
232		return (1);
233
234	if (cur_snaplen > snap)
235		purge_buffer();
236
237	cur_snaplen = snap;
238
239	return (0);
240}
241
242int
243reset_dump(void)
244{
245	struct pcap_file_header hdr;
246	struct stat st;
247	int fd;
248	FILE *fp;
249
250	if (hpcap == NULL)
251		return (-1);
252
253	if (dpcap) {
254		flush_buffer(dpcap);
255		fclose(dpcap);
256		dpcap = NULL;
257	}
258
259	/*
260	 * Basically reimplement pcap_dump_open() because it truncates
261	 * files and duplicates headers and such.
262	 */
263	fd = priv_open_log();
264	if (fd < 0)
265		return (1);
266
267	fp = fdopen(fd, "a+");
268
269	if (fp == NULL) {
270		close(fd);
271		logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
272		return (1);
273	}
274	if (fstat(fileno(fp), &st) == -1) {
275		fclose(fp);
276		logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
277		return (1);
278	}
279
280	/* set FILE unbuffered, we do our own buffering */
281	if (setvbuf(fp, NULL, _IONBF, 0)) {
282		fclose(fp);
283		logmsg(LOG_ERR, "Failed to set output buffers");
284		return (1);
285	}
286
287#define TCPDUMP_MAGIC 0xa1b2c3d4
288
289	if (st.st_size == 0) {
290		if (snaplen != cur_snaplen) {
291			logmsg(LOG_NOTICE, "Using snaplen %d", snaplen);
292			if (set_snaplen(snaplen)) {
293				fclose(fp);
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
324int
325scan_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 */
398void
399dump_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		off_t pos = ftello(f);
422
423		/* try to undo header to prevent corruption */
424#ifdef __FreeBSD__
425		if (pos < sizeof(sh) ||
426		    ftruncate(fileno(f), pos - sizeof(sh))) {
427#else
428		if (pos < sizeof(*h) ||
429		    ftruncate(fileno(f), pos - sizeof(*h))) {
430#endif
431			logmsg(LOG_ERR, "Write failed, corrupted logfile!");
432			set_suspended(1);
433			gotsig_close = 1;
434			return;
435		}
436		goto error;
437	}
438
439	if (fwrite((char *)sp, h->caplen, 1, f) != 1)
440		goto error;
441
442	return;
443
444error:
445	set_suspended(1);
446	packets_dropped ++;
447	logmsg(LOG_ERR, "Logging suspended: fwrite: %s", strerror(errno));
448}
449
450int
451flush_buffer(FILE *f)
452{
453	off_t offset;
454	int len = bufpos - buffer;
455
456	if (len <= 0)
457		return (0);
458
459	offset = ftello(f);
460	if (offset == (off_t)-1) {
461		set_suspended(1);
462		logmsg(LOG_ERR, "Logging suspended: ftello: %s",
463		    strerror(errno));
464		return (1);
465	}
466
467	if (fwrite(buffer, len, 1, f) != 1) {
468		set_suspended(1);
469		logmsg(LOG_ERR, "Logging suspended: fwrite: %s",
470		    strerror(errno));
471		ftruncate(fileno(f), offset);
472		return (1);
473	}
474
475	set_suspended(0);
476	bufpos = buffer;
477	bufleft = buflen;
478	bufpkt = 0;
479
480	return (0);
481}
482
483void
484purge_buffer(void)
485{
486	packets_dropped += bufpkt;
487
488	set_suspended(0);
489	bufpos = buffer;
490	bufleft = buflen;
491	bufpkt = 0;
492}
493
494/* append packet to the buffer, flushing if necessary */
495void
496dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
497{
498	FILE *f = (FILE *)user;
499#ifdef __FreeBSD__
500	struct pcap_sf_pkthdr sh;
501	size_t len = sizeof(sh) + h->caplen;
502#else
503	size_t len = sizeof(*h) + h->caplen;
504#endif
505
506	if (len < sizeof(*h) || h->caplen > (size_t)cur_snaplen) {
507		logmsg(LOG_NOTICE, "invalid size %u (%u/%u), packet dropped",
508		       len, cur_snaplen, snaplen);
509		packets_dropped++;
510		return;
511	}
512
513	if (len <= bufleft)
514		goto append;
515
516	if (suspended) {
517		packets_dropped++;
518		return;
519	}
520
521	if (flush_buffer(f)) {
522		packets_dropped++;
523		return;
524	}
525
526	if (len > bufleft) {
527		dump_packet_nobuf(user, h, sp);
528		return;
529	}
530
531 append:
532#ifdef __FreeBSD__
533 	sh.ts.tv_sec = (bpf_int32)h->ts.tv_sec;
534 	sh.ts.tv_usec = (bpf_int32)h->ts.tv_usec;
535	sh.caplen = h->caplen;
536	sh.len = h->len;
537
538	memcpy(bufpos, &sh, sizeof(sh));
539	memcpy(bufpos + sizeof(sh), sp, h->caplen);
540#else
541	memcpy(bufpos, h, sizeof(*h));
542	memcpy(bufpos + sizeof(*h), sp, h->caplen);
543#endif
544
545	bufpos += len;
546	bufleft -= len;
547	bufpkt++;
548
549	return;
550}
551
552int
553main(int argc, char **argv)
554{
555	struct pcap_stat pstat;
556	int ch, np, Xflag = 0;
557	pcap_handler phandler = dump_packet;
558	char *errstr = NULL;
559
560#ifdef __FreeBSD__
561	/* another ?paranoid? safety measure we do not have */
562#else
563	closefrom(STDERR_FILENO + 1);
564#endif
565
566	while ((ch = getopt(argc, argv, "Dxd:s:f:")) != -1) {
567		switch (ch) {
568		case 'D':
569			Debug = 1;
570			break;
571		case 'd':
572#ifdef __OpenBSD__
573			delay = strtonum(optarg, 5, 60*60, &errstr);
574			if (errstr)
575#else
576			delay = strtol(optarg, &errstr, 10);
577			if ((delay < 5) || (delay > 60*60) ||
578			    ((errstr != NULL) && (*errstr != '\0')))
579#endif
580				usage();
581			break;
582		case 'f':
583			filename = optarg;
584			break;
585		case 's':
586#ifdef __OpenBSD__
587			snaplen = strtonum(optarg, 0, PFLOGD_MAXSNAPLEN,
588			    &errstr);
589			if (snaplen <= 0)
590				snaplen = DEF_SNAPLEN;
591			if (errstr)
592				snaplen = PFLOGD_MAXSNAPLEN;
593#else
594			snaplen = strtol(optarg, &errstr, 10);
595			if (snaplen <= 0)
596				snaplen = DEF_SNAPLEN;
597			if ((snaplen > PFLOGD_MAXSNAPLEN) ||
598			    ((errstr != NULL) && (*errstr != '\0')))
599				snaplen = PFLOGD_MAXSNAPLEN;
600#endif
601			break;
602		case 'x':
603			Xflag++;
604			break;
605		default:
606			usage();
607		}
608
609	}
610
611	log_debug = Debug;
612	argc -= optind;
613	argv += optind;
614
615	if (!Debug) {
616		openlog("pflogd", LOG_PID | LOG_CONS, LOG_DAEMON);
617		if (daemon(0, 0)) {
618			logmsg(LOG_WARNING, "Failed to become daemon: %s",
619			    strerror(errno));
620		}
621		pidfile(NULL);
622	}
623
624	tzset();
625	(void)umask(S_IRWXG | S_IRWXO);
626
627	/* filter will be used by the privileged process */
628	if (argc) {
629		filter = copy_argv(argv);
630		if (filter == NULL)
631			logmsg(LOG_NOTICE, "Failed to form filter expression");
632	}
633
634	/* initialize pcap before dropping privileges */
635	if (init_pcap()) {
636		logmsg(LOG_ERR, "Exiting, init failure");
637		exit(1);
638	}
639
640	/* Privilege separation begins here */
641	if (priv_init()) {
642		logmsg(LOG_ERR, "unable to privsep");
643		exit(1);
644	}
645
646	setproctitle("[initializing]");
647	/* Process is now unprivileged and inside a chroot */
648	signal(SIGTERM, sig_close);
649	signal(SIGINT, sig_close);
650	signal(SIGQUIT, sig_close);
651	signal(SIGALRM, sig_alrm);
652	signal(SIGHUP, sig_hup);
653	alarm(delay);
654
655	buffer = malloc(PFLOGD_BUFSIZE);
656
657	if (buffer == NULL) {
658		logmsg(LOG_WARNING, "Failed to allocate output buffer");
659		phandler = dump_packet_nobuf;
660	} else {
661		bufleft = buflen = PFLOGD_BUFSIZE;
662		bufpos = buffer;
663		bufpkt = 0;
664	}
665
666	if (reset_dump()) {
667		if (Xflag)
668			return (1);
669
670		logmsg(LOG_ERR, "Logging suspended: open error");
671		set_suspended(1);
672	} else if (Xflag)
673		return (0);
674
675	while (1) {
676		np = pcap_dispatch(hpcap, PCAP_NUM_PKTS,
677		    phandler, (u_char *)dpcap);
678		if (np < 0) {
679#ifdef __FreeBSD__
680			if (errno == ENXIO) {
681				logmsg(LOG_ERR,
682				    "Device not/no longer configured");
683				break;
684			}
685#endif
686			logmsg(LOG_NOTICE, "%s", pcap_geterr(hpcap));
687		}
688
689		if (gotsig_close)
690			break;
691		if (gotsig_hup) {
692			if (reset_dump()) {
693				logmsg(LOG_ERR,
694				    "Logging suspended: open error");
695				set_suspended(1);
696			}
697			gotsig_hup = 0;
698		}
699
700		if (gotsig_alrm) {
701			if (dpcap)
702				flush_buffer(dpcap);
703			gotsig_alrm = 0;
704			alarm(delay);
705		}
706	}
707
708	logmsg(LOG_NOTICE, "Exiting");
709	if (dpcap) {
710		flush_buffer(dpcap);
711		fclose(dpcap);
712	}
713	purge_buffer();
714
715	if (pcap_stats(hpcap, &pstat) < 0)
716		logmsg(LOG_WARNING, "Reading stats: %s", pcap_geterr(hpcap));
717	else
718		logmsg(LOG_NOTICE,
719		    "%u packets received, %u/%u dropped (kernel/pflogd)",
720		    pstat.ps_recv, pstat.ps_drop, packets_dropped);
721
722	pcap_close(hpcap);
723	if (!Debug)
724		closelog();
725	return (0);
726}
727