xref: /freebsd/contrib/pf/pflogd/pflogd.c (revision 6b3455a7665208c366849f0b2b3bc916fb97516e) 
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 	struct pcap_pkthdr ph;
329 	off_t pos;
330 
331 	/*
332 	 * Must read the file, compare the header against our new
333 	 * options (in particular, snaplen) and adjust our options so
334 	 * that we generate a correct file. Furthermore, check the file
335 	 * for consistency so that we can append safely.
336 	 *
337 	 * XXX this may take a long time for large logs.
338 	 */
339 	(void) fseek(fp, 0L, SEEK_SET);
340 
341 	if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
342 		logmsg(LOG_ERR, "Short file header");
343 		return (1);
344 	}
345 
346 	if (hdr.magic != TCPDUMP_MAGIC ||
347 	    hdr.version_major != PCAP_VERSION_MAJOR ||
348 	    hdr.version_minor != PCAP_VERSION_MINOR ||
349 	    hdr.linktype != hpcap->linktype ||
350 	    hdr.snaplen > PFLOGD_MAXSNAPLEN) {
351 		logmsg(LOG_ERR, "Invalid/incompatible log file, move it away");
352 		return (1);
353 	}
354 
355 	pos = sizeof(hdr);
356 
357 	while (!feof(fp)) {
358 		off_t len = fread((char *)&ph, 1, sizeof(ph), fp);
359 		if (len == 0)
360 			break;
361 
362 		if (len != sizeof(ph))
363 			goto error;
364 		if (ph.caplen > hdr.snaplen || ph.caplen > PFLOGD_MAXSNAPLEN)
365 			goto error;
366 		pos += sizeof(ph) + ph.caplen;
367 		if (pos > size)
368 			goto error;
369 		fseek(fp, ph.caplen, SEEK_CUR);
370 	}
371 
372 	if (pos != size)
373 		goto error;
374 
375 	if (hdr.snaplen != cur_snaplen) {
376 		logmsg(LOG_WARNING,
377 		       "Existing file has different snaplen %u, using it",
378 		       hdr.snaplen);
379 		if (set_snaplen(hdr.snaplen)) {
380 			logmsg(LOG_WARNING,
381 			       "Failed, using old settings, offset %llu",
382 			       (unsigned long long) size);
383 		}
384 	}
385 
386 	return (0);
387 
388  error:
389 	logmsg(LOG_ERR, "Corrupted log file.");
390 	return (1);
391 }
392 
393 /* dump a packet directly to the stream, which is unbuffered */
394 void
395 dump_packet_nobuf(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
396 {
397 	FILE *f = (FILE *)user;
398 
399 	if (suspended) {
400 		packets_dropped++;
401 		return;
402 	}
403 
404 	if (fwrite((char *)h, sizeof(*h), 1, f) != 1) {
405 		/* try to undo header to prevent corruption */
406 		off_t pos = ftello(f);
407 		if (pos < sizeof(*h) ||
408 		    ftruncate(fileno(f), pos - sizeof(*h))) {
409 			logmsg(LOG_ERR, "Write failed, corrupted logfile!");
410 			set_suspended(1);
411 			gotsig_close = 1;
412 			return;
413 		}
414 		goto error;
415 	}
416 
417 	if (fwrite((char *)sp, h->caplen, 1, f) != 1)
418 		goto error;
419 
420 	return;
421 
422 error:
423 	set_suspended(1);
424 	packets_dropped ++;
425 	logmsg(LOG_ERR, "Logging suspended: fwrite: %s", strerror(errno));
426 }
427 
428 int
429 flush_buffer(FILE *f)
430 {
431 	off_t offset;
432 	int len = bufpos - buffer;
433 
434 	if (len <= 0)
435 		return (0);
436 
437 	offset = ftello(f);
438 	if (offset == (off_t)-1) {
439 		set_suspended(1);
440 		logmsg(LOG_ERR, "Logging suspended: ftello: %s",
441 		    strerror(errno));
442 		return (1);
443 	}
444 
445 	if (fwrite(buffer, len, 1, f) != 1) {
446 		set_suspended(1);
447 		logmsg(LOG_ERR, "Logging suspended: fwrite: %s",
448 		    strerror(errno));
449 		ftruncate(fileno(f), offset);
450 		return (1);
451 	}
452 
453 	set_suspended(0);
454 	bufpos = buffer;
455 	bufleft = buflen;
456 	bufpkt = 0;
457 
458 	return (0);
459 }
460 
461 void
462 purge_buffer(void)
463 {
464 	packets_dropped += bufpkt;
465 
466 	set_suspended(0);
467 	bufpos = buffer;
468 	bufleft = buflen;
469 	bufpkt = 0;
470 }
471 
472 /* append packet to the buffer, flushing if necessary */
473 void
474 dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
475 {
476 	FILE *f = (FILE *)user;
477 	size_t len = sizeof(*h) + h->caplen;
478 
479 	if (len < sizeof(*h) || h->caplen > (size_t)cur_snaplen) {
480 		logmsg(LOG_NOTICE, "invalid size %u (%u/%u), packet dropped",
481 		       len, cur_snaplen, snaplen);
482 		packets_dropped++;
483 		return;
484 	}
485 
486 	if (len <= bufleft)
487 		goto append;
488 
489 	if (suspended) {
490 		packets_dropped++;
491 		return;
492 	}
493 
494 	if (flush_buffer(f)) {
495 		packets_dropped++;
496 		return;
497 	}
498 
499 	if (len > bufleft) {
500 		dump_packet_nobuf(user, h, sp);
501 		return;
502 	}
503 
504  append:
505 	memcpy(bufpos, h, sizeof(*h));
506 	memcpy(bufpos + sizeof(*h), sp, h->caplen);
507 
508 	bufpos += len;
509 	bufleft -= len;
510 	bufpkt++;
511 
512 	return;
513 }
514 
515 int
516 main(int argc, char **argv)
517 {
518 	struct pcap_stat pstat;
519 	int ch, np, Xflag = 0;
520 	pcap_handler phandler = dump_packet;
521 
522 #ifdef __FreeBSD__
523 	/* another ?paranoid? safety measure we do not have */
524 #else
525 	closefrom(STDERR_FILENO + 1);
526 #endif
527 
528 	while ((ch = getopt(argc, argv, "Dxd:s:f:")) != -1) {
529 		switch (ch) {
530 		case 'D':
531 			Debug = 1;
532 			break;
533 		case 'd':
534 			delay = atoi(optarg);
535 			if (delay < 5 || delay > 60*60)
536 				usage();
537 			break;
538 		case 'f':
539 			filename = optarg;
540 			break;
541 		case 's':
542 			snaplen = atoi(optarg);
543 			if (snaplen <= 0)
544 				snaplen = DEF_SNAPLEN;
545 			if (snaplen > PFLOGD_MAXSNAPLEN)
546 				snaplen = PFLOGD_MAXSNAPLEN;
547 			break;
548 		case 'x':
549 			Xflag++;
550 			break;
551 		default:
552 			usage();
553 		}
554 
555 	}
556 
557 	log_debug = Debug;
558 	argc -= optind;
559 	argv += optind;
560 
561 	if (!Debug) {
562 		openlog("pflogd", LOG_PID | LOG_CONS, LOG_DAEMON);
563 		if (daemon(0, 0)) {
564 			logmsg(LOG_WARNING, "Failed to become daemon: %s",
565 			    strerror(errno));
566 		}
567 		pidfile(NULL);
568 	}
569 
570 	(void)umask(S_IRWXG | S_IRWXO);
571 
572 	/* filter will be used by the privileged process */
573 	if (argc) {
574 		filter = copy_argv(argv);
575 		if (filter == NULL)
576 			logmsg(LOG_NOTICE, "Failed to form filter expression");
577 	}
578 
579 	/* initialize pcap before dropping privileges */
580 	if (init_pcap()) {
581 		logmsg(LOG_ERR, "Exiting, init failure");
582 		exit(1);
583 	}
584 
585 	/* Privilege separation begins here */
586 	if (priv_init()) {
587 		logmsg(LOG_ERR, "unable to privsep");
588 		exit(1);
589 	}
590 
591 	setproctitle("[initializing]");
592 	/* Process is now unprivileged and inside a chroot */
593 	signal(SIGTERM, sig_close);
594 	signal(SIGINT, sig_close);
595 	signal(SIGQUIT, sig_close);
596 	signal(SIGALRM, sig_alrm);
597 	signal(SIGHUP, sig_hup);
598 	alarm(delay);
599 
600 	buffer = malloc(PFLOGD_BUFSIZE);
601 
602 	if (buffer == NULL) {
603 		logmsg(LOG_WARNING, "Failed to allocate output buffer");
604 		phandler = dump_packet_nobuf;
605 	} else {
606 		bufleft = buflen = PFLOGD_BUFSIZE;
607 		bufpos = buffer;
608 		bufpkt = 0;
609 	}
610 
611 	if (reset_dump()) {
612 		if (Xflag)
613 			return (1);
614 
615 		logmsg(LOG_ERR, "Logging suspended: open error");
616 		set_suspended(1);
617 	} else if (Xflag)
618 		return (0);
619 
620 	while (1) {
621 		np = pcap_dispatch(hpcap, PCAP_NUM_PKTS,
622 		    dump_packet, (u_char *)dpcap);
623 		if (np < 0)
624 			logmsg(LOG_NOTICE, "%s", pcap_geterr(hpcap));
625 
626 		if (gotsig_close)
627 			break;
628 		if (gotsig_hup) {
629 			if (reset_dump()) {
630 				logmsg(LOG_ERR,
631 				    "Logging suspended: open error");
632 				set_suspended(1);
633 			}
634 			gotsig_hup = 0;
635 		}
636 
637 		if (gotsig_alrm) {
638 			if (dpcap)
639 				flush_buffer(dpcap);
640 			gotsig_alrm = 0;
641 			alarm(delay);
642 		}
643 	}
644 
645 	logmsg(LOG_NOTICE, "Exiting");
646 	if (dpcap) {
647 		flush_buffer(dpcap);
648 		fclose(dpcap);
649 	}
650 	purge_buffer();
651 
652 	if (pcap_stats(hpcap, &pstat) < 0)
653 		logmsg(LOG_WARNING, "Reading stats: %s", pcap_geterr(hpcap));
654 	else
655 		logmsg(LOG_NOTICE,
656 		    "%u packets received, %u/%u dropped (kernel/pflogd)",
657 		    pstat.ps_recv, pstat.ps_drop, packets_dropped);
658 
659 	pcap_close(hpcap);
660 	if (!Debug)
661 		closelog();
662 	return (0);
663 }
664