1 /*
2 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
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: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * packet filter subroutines for tcpdump
22 * Extraction/creation by Jeffrey Mogul, DECWRL
23 */
24
25 #ifndef lint
26 static const char rcsid[] _U_ =
27 "@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.91.2.2 2005/05/03 18:54:37 guy Exp $ (LBL)";
28 #endif
29
30 #ifdef HAVE_CONFIG_H
31 #include "config.h"
32 #endif
33
34 #include <sys/types.h>
35 #include <sys/time.h>
36 #include <sys/timeb.h>
37 #include <sys/socket.h>
38 #include <sys/file.h>
39 #include <sys/ioctl.h>
40 #include <net/pfilt.h>
41
42 struct mbuf;
43 struct rtentry;
44 #include <net/if.h>
45
46 #include <netinet/in.h>
47 #include <netinet/in_systm.h>
48 #include <netinet/ip.h>
49 #include <netinet/if_ether.h>
50 #include <netinet/ip_var.h>
51 #include <netinet/udp.h>
52 #include <netinet/udp_var.h>
53 #include <netinet/tcp.h>
54 #include <netinet/tcpip.h>
55
56 #include <ctype.h>
57 #include <errno.h>
58 #include <netdb.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 #include <unistd.h>
63
64 /*
65 * Make "pcap.h" not include "pcap-bpf.h"; we are going to include the
66 * native OS version, as we need various BPF ioctls from it.
67 */
68 #define PCAP_DONT_INCLUDE_PCAP_BPF_H
69 #include <net/bpf.h>
70
71 #include "pcap-int.h"
72
73 #ifdef HAVE_OS_PROTO_H
74 #include "os-proto.h"
75 #endif
76
77 static int pcap_setfilter_pf(pcap_t *, struct bpf_program *);
78
79 /*
80 * BUFSPACE is the size in bytes of the packet read buffer. Most tcpdump
81 * applications aren't going to need more than 200 bytes of packet header
82 * and the read shouldn't return more packets than packetfilter's internal
83 * queue limit (bounded at 256).
84 */
85 #define BUFSPACE (200 * 256)
86
87 static int
pcap_read_pf(pcap_t * pc,int cnt,pcap_handler callback,u_char * user)88 pcap_read_pf(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
89 {
90 register u_char *p, *bp;
91 struct bpf_insn *fcode;
92 register int cc, n, buflen, inc;
93 register struct enstamp *sp;
94 #ifdef LBL_ALIGN
95 struct enstamp stamp;
96 #endif
97 #ifdef PCAP_FDDIPAD
98 register int pad;
99 #endif
100
101 fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
102 again:
103 cc = pc->cc;
104 if (cc == 0) {
105 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
106 if (cc < 0) {
107 if (errno == EWOULDBLOCK)
108 return (0);
109 if (errno == EINVAL &&
110 lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
111 /*
112 * Due to a kernel bug, after 2^31 bytes,
113 * the kernel file offset overflows and
114 * read fails with EINVAL. The lseek()
115 * to 0 will fix things.
116 */
117 (void)lseek(pc->fd, 0L, SEEK_SET);
118 goto again;
119 }
120 snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
121 pcap_strerror(errno));
122 return (-1);
123 }
124 bp = pc->buffer + pc->offset;
125 } else
126 bp = pc->bp;
127 /*
128 * Loop through each packet.
129 */
130 n = 0;
131 #ifdef PCAP_FDDIPAD
132 pad = pc->fddipad;
133 #endif
134 while (cc > 0) {
135 /*
136 * Has "pcap_breakloop()" been called?
137 * If so, return immediately - if we haven't read any
138 * packets, clear the flag and return -2 to indicate
139 * that we were told to break out of the loop, otherwise
140 * leave the flag set, so that the *next* call will break
141 * out of the loop without having read any packets, and
142 * return the number of packets we've processed so far.
143 */
144 if (pc->break_loop) {
145 if (n == 0) {
146 pc->break_loop = 0;
147 return (-2);
148 } else {
149 pc->cc = cc;
150 pc->bp = bp;
151 return (n);
152 }
153 }
154 if (cc < sizeof(*sp)) {
155 snprintf(pc->errbuf, sizeof(pc->errbuf),
156 "pf short read (%d)", cc);
157 return (-1);
158 }
159 #ifdef LBL_ALIGN
160 if ((long)bp & 3) {
161 sp = &stamp;
162 memcpy((char *)sp, (char *)bp, sizeof(*sp));
163 } else
164 #endif
165 sp = (struct enstamp *)bp;
166 if (sp->ens_stamplen != sizeof(*sp)) {
167 snprintf(pc->errbuf, sizeof(pc->errbuf),
168 "pf short stamplen (%d)",
169 sp->ens_stamplen);
170 return (-1);
171 }
172
173 p = bp + sp->ens_stamplen;
174 buflen = sp->ens_count;
175 if (buflen > pc->snapshot)
176 buflen = pc->snapshot;
177
178 /* Calculate inc before possible pad update */
179 inc = ENALIGN(buflen + sp->ens_stamplen);
180 cc -= inc;
181 bp += inc;
182 pc->md.TotPkts++;
183 pc->md.TotDrops += sp->ens_dropped;
184 pc->md.TotMissed = sp->ens_ifoverflows;
185 if (pc->md.OrigMissed < 0)
186 pc->md.OrigMissed = pc->md.TotMissed;
187
188 /*
189 * Short-circuit evaluation: if using BPF filter
190 * in kernel, no need to do it now.
191 *
192 #ifdef PCAP_FDDIPAD
193 * Note: the filter code was generated assuming
194 * that pc->fddipad was the amount of padding
195 * before the header, as that's what's required
196 * in the kernel, so we run the filter before
197 * skipping that padding.
198 #endif
199 */
200 if (fcode == NULL ||
201 bpf_filter(fcode, p, sp->ens_count, buflen)) {
202 struct pcap_pkthdr h;
203 pc->md.TotAccepted++;
204 h.ts = sp->ens_tstamp;
205 #ifdef PCAP_FDDIPAD
206 h.len = sp->ens_count - pad;
207 #else
208 h.len = sp->ens_count;
209 #endif
210 #ifdef PCAP_FDDIPAD
211 p += pad;
212 buflen -= pad;
213 #endif
214 h.caplen = buflen;
215 (*callback)(user, &h, p);
216 if (++n >= cnt && cnt > 0) {
217 pc->cc = cc;
218 pc->bp = bp;
219 return (n);
220 }
221 }
222 }
223 pc->cc = 0;
224 return (n);
225 }
226
227 static int
pcap_inject_pf(pcap_t * p,const void * buf,size_t size)228 pcap_inject_pf(pcap_t *p, const void *buf, size_t size)
229 {
230 int ret;
231
232 ret = write(p->fd, buf, size);
233 if (ret == -1) {
234 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
235 pcap_strerror(errno));
236 return (-1);
237 }
238 return (ret);
239 }
240
241 static int
pcap_stats_pf(pcap_t * p,struct pcap_stat * ps)242 pcap_stats_pf(pcap_t *p, struct pcap_stat *ps)
243 {
244
245 /*
246 * If packet filtering is being done in the kernel:
247 *
248 * "ps_recv" counts only packets that passed the filter.
249 * This does not include packets dropped because we
250 * ran out of buffer space. (XXX - perhaps it should,
251 * by adding "ps_drop" to "ps_recv", for compatibility
252 * with some other platforms. On the other hand, on
253 * some platforms "ps_recv" counts only packets that
254 * passed the filter, and on others it counts packets
255 * that didn't pass the filter....)
256 *
257 * "ps_drop" counts packets that passed the kernel filter
258 * (if any) but were dropped because the input queue was
259 * full.
260 *
261 * "ps_ifdrop" counts packets dropped by the network
262 * inteface (regardless of whether they would have passed
263 * the input filter, of course).
264 *
265 * If packet filtering is not being done in the kernel:
266 *
267 * "ps_recv" counts only packets that passed the filter.
268 *
269 * "ps_drop" counts packets that were dropped because the
270 * input queue was full, regardless of whether they passed
271 * the userland filter.
272 *
273 * "ps_ifdrop" counts packets dropped by the network
274 * inteface (regardless of whether they would have passed
275 * the input filter, of course).
276 *
277 * These statistics don't include packets not yet read from
278 * the kernel by libpcap, but they may include packets not
279 * yet read from libpcap by the application.
280 */
281 ps->ps_recv = p->md.TotAccepted;
282 ps->ps_drop = p->md.TotDrops;
283 ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
284 return (0);
285 }
286
287 /*
288 * We include the OS's <net/bpf.h>, not our "pcap-bpf.h", so we probably
289 * don't get DLT_DOCSIS defined.
290 */
291 #ifndef DLT_DOCSIS
292 #define DLT_DOCSIS 143
293 #endif
294
295 pcap_t *
pcap_open_live(const char * device,int snaplen,int promisc,int to_ms,char * ebuf)296 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
297 char *ebuf)
298 {
299 pcap_t *p;
300 short enmode;
301 int backlog = -1; /* request the most */
302 struct enfilter Filter;
303 struct endevp devparams;
304
305 p = (pcap_t *)malloc(sizeof(*p));
306 if (p == NULL) {
307 snprintf(ebuf, PCAP_ERRBUF_SIZE,
308 "pcap_open_live: %s", pcap_strerror(errno));
309 return (0);
310 }
311 memset(p, 0, sizeof(*p));
312 /*
313 * Initially try a read/write open (to allow the inject
314 * method to work). If that fails due to permission
315 * issues, fall back to read-only. This allows a
316 * non-root user to be granted specific access to pcap
317 * capabilities via file permissions.
318 *
319 * XXX - we should have an API that has a flag that
320 * controls whether to open read-only or read-write,
321 * so that denial of permission to send (or inability
322 * to send, if sending packets isn't supported on
323 * the device in question) can be indicated at open
324 * time.
325 *
326 * XXX - we assume here that "pfopen()" does not, in fact, modify
327 * its argument, even though it takes a "char *" rather than a
328 * "const char *" as its first argument. That appears to be
329 * the case, at least on Digital UNIX 4.0.
330 */
331 p->fd = pfopen(device, O_RDWR);
332 if (p->fd == -1 && errno == EACCES)
333 p->fd = pfopen(device, O_RDONLY);
334 if (p->fd < 0) {
335 snprintf(ebuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
336 your system may not be properly configured; see the packetfilter(4) man page\n",
337 device, pcap_strerror(errno));
338 goto bad;
339 }
340 p->md.OrigMissed = -1;
341 enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
342 if (promisc)
343 enmode |= ENPROMISC;
344 if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
345 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
346 pcap_strerror(errno));
347 goto bad;
348 }
349 #ifdef ENCOPYALL
350 /* Try to set COPYALL mode so that we see packets to ourself */
351 enmode = ENCOPYALL;
352 (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
353 #endif
354 /* set the backlog */
355 if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
356 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
357 pcap_strerror(errno));
358 goto bad;
359 }
360 /* discover interface type */
361 if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
362 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
363 pcap_strerror(errno));
364 goto bad;
365 }
366 /* HACK: to compile prior to Ultrix 4.2 */
367 #ifndef ENDT_FDDI
368 #define ENDT_FDDI 4
369 #endif
370 switch (devparams.end_dev_type) {
371
372 case ENDT_10MB:
373 p->linktype = DLT_EN10MB;
374 p->offset = 2;
375 /*
376 * This is (presumably) a real Ethernet capture; give it a
377 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
378 * that an application can let you choose it, in case you're
379 * capturing DOCSIS traffic that a Cisco Cable Modem
380 * Termination System is putting out onto an Ethernet (it
381 * doesn't put an Ethernet header onto the wire, it puts raw
382 * DOCSIS frames out on the wire inside the low-level
383 * Ethernet framing).
384 */
385 p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
386 /*
387 * If that fails, just leave the list empty.
388 */
389 if (p->dlt_list != NULL) {
390 p->dlt_list[0] = DLT_EN10MB;
391 p->dlt_list[1] = DLT_DOCSIS;
392 p->dlt_count = 2;
393 }
394 break;
395
396 case ENDT_FDDI:
397 p->linktype = DLT_FDDI;
398 break;
399
400 #ifdef ENDT_SLIP
401 case ENDT_SLIP:
402 p->linktype = DLT_SLIP;
403 break;
404 #endif
405
406 #ifdef ENDT_PPP
407 case ENDT_PPP:
408 p->linktype = DLT_PPP;
409 break;
410 #endif
411
412 #ifdef ENDT_LOOPBACK
413 case ENDT_LOOPBACK:
414 /*
415 * It appears to use Ethernet framing, at least on
416 * Digital UNIX 4.0.
417 */
418 p->linktype = DLT_EN10MB;
419 p->offset = 2;
420 break;
421 #endif
422
423 #ifdef ENDT_TRN
424 case ENDT_TRN:
425 p->linktype = DLT_IEEE802;
426 break;
427 #endif
428
429 default:
430 /*
431 * XXX - what about ENDT_IEEE802? The pfilt.h header
432 * file calls this "IEEE 802 networks (non-Ethernet)",
433 * but that doesn't specify a specific link layer type;
434 * it could be 802.4, or 802.5 (except that 802.5 is
435 * ENDT_TRN), or 802.6, or 802.11, or.... That's why
436 * DLT_IEEE802 was hijacked to mean Token Ring in various
437 * BSDs, and why we went along with that hijacking.
438 *
439 * XXX - what about ENDT_HDLC and ENDT_NULL?
440 * Presumably, as ENDT_OTHER is just "Miscellaneous
441 * framing", there's not much we can do, as that
442 * doesn't specify a particular type of header.
443 */
444 snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown data-link type %u",
445 devparams.end_dev_type);
446 goto bad;
447 }
448 /* set truncation */
449 #ifdef PCAP_FDDIPAD
450 if (p->linktype == DLT_FDDI) {
451 p->fddipad = PCAP_FDDIPAD;
452
453 /* packetfilter includes the padding in the snapshot */
454 snaplen += PCAP_FDDIPAD;
455 } else
456 p->fddipad = 0;
457 #endif
458 if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
459 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
460 pcap_strerror(errno));
461 goto bad;
462 }
463 p->snapshot = snaplen;
464 /* accept all packets */
465 memset(&Filter, 0, sizeof(Filter));
466 Filter.enf_Priority = 37; /* anything > 2 */
467 Filter.enf_FilterLen = 0; /* means "always true" */
468 if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
469 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
470 pcap_strerror(errno));
471 goto bad;
472 }
473
474 if (to_ms != 0) {
475 struct timeval timeout;
476 timeout.tv_sec = to_ms / 1000;
477 timeout.tv_usec = (to_ms * 1000) % 1000000;
478 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
479 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
480 pcap_strerror(errno));
481 goto bad;
482 }
483 }
484
485 p->bufsize = BUFSPACE;
486 p->buffer = (u_char*)malloc(p->bufsize + p->offset);
487 if (p->buffer == NULL) {
488 strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
489 goto bad;
490 }
491
492 /*
493 * "select()" and "poll()" work on packetfilter devices.
494 */
495 p->selectable_fd = p->fd;
496
497 p->read_op = pcap_read_pf;
498 p->inject_op = pcap_inject_pf;
499 p->setfilter_op = pcap_setfilter_pf;
500 p->setdirection_op = NULL; /* Not implemented. */
501 p->set_datalink_op = NULL; /* can't change data link type */
502 p->getnonblock_op = pcap_getnonblock_fd;
503 p->setnonblock_op = pcap_setnonblock_fd;
504 p->stats_op = pcap_stats_pf;
505 p->close_op = pcap_close_common;
506
507 return (p);
508 bad:
509 if (p->fd >= 0)
510 close(p->fd);
511 /*
512 * Get rid of any link-layer type list we allocated.
513 */
514 if (p->dlt_list != NULL)
515 free(p->dlt_list);
516 free(p);
517 return (NULL);
518 }
519
520 int
pcap_platform_finddevs(pcap_if_t ** alldevsp,char * errbuf)521 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
522 {
523 return (0);
524 }
525
526 static int
pcap_setfilter_pf(pcap_t * p,struct bpf_program * fp)527 pcap_setfilter_pf(pcap_t *p, struct bpf_program *fp)
528 {
529 struct bpf_version bv;
530
531 /*
532 * See if BIOCVERSION works. If not, we assume the kernel doesn't
533 * support BPF-style filters (it's not documented in the bpf(7)
534 * or packetfiler(7) man pages, but the code used to fail if
535 * BIOCSETF worked but BIOCVERSION didn't, and I've seen it do
536 * kernel filtering in DU 4.0, so presumably BIOCVERSION works
537 * there, at least).
538 */
539 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) >= 0) {
540 /*
541 * OK, we have the version of the BPF interpreter;
542 * is it the same major version as us, and the same
543 * or better minor version?
544 */
545 if (bv.bv_major == BPF_MAJOR_VERSION &&
546 bv.bv_minor >= BPF_MINOR_VERSION) {
547 /*
548 * Yes. Try to install the filter.
549 */
550 if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
551 snprintf(p->errbuf, sizeof(p->errbuf),
552 "BIOCSETF: %s", pcap_strerror(errno));
553 return (-1);
554 }
555
556 /*
557 * OK, that succeeded. We're doing filtering in
558 * the kernel. (We assume we don't have a
559 * userland filter installed - that'd require
560 * a previous version check to have failed but
561 * this one to succeed.)
562 *
563 * XXX - this message should be supplied to the
564 * application as a warning of some sort,
565 * except that if it's a GUI application, it's
566 * not clear that it should be displayed in
567 * a window to annoy the user.
568 */
569 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
570 p->md.use_bpf = 1;
571
572 /*
573 * Discard any previously-received packets,
574 * as they might have passed whatever filter
575 * was formerly in effect, but might not pass
576 * this filter (BIOCSETF discards packets buffered
577 * in the kernel, so you can lose packets in any
578 * case).
579 */
580 p->cc = 0;
581 return (0);
582 }
583
584 /*
585 * We can't use the kernel's BPF interpreter; don't give
586 * up, just log a message and be inefficient.
587 *
588 * XXX - this should really be supplied to the application
589 * as a warning of some sort.
590 */
591 fprintf(stderr,
592 "tcpdump: Requires BPF language %d.%d or higher; kernel is %d.%d\n",
593 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
594 bv.bv_major, bv.bv_minor);
595 }
596
597 /*
598 * We couldn't do filtering in the kernel; do it in userland.
599 */
600 if (install_bpf_program(p, fp) < 0)
601 return (-1);
602
603 /*
604 * XXX - this message should be supplied by the application as
605 * a warning of some sort.
606 */
607 fprintf(stderr, "tcpdump: Filtering in user process\n");
608 p->md.use_bpf = 0;
609 return (0);
610 }
611