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 #ifdef HAVE_CONFIG_H
26 #include "config.h"
27 #endif
28
29 #include <sys/types.h>
30 #include <sys/time.h>
31 #include <sys/timeb.h>
32 #include <sys/socket.h>
33 #include <sys/file.h>
34 #include <sys/ioctl.h>
35 #include <net/pfilt.h>
36
37 struct mbuf;
38 struct rtentry;
39 #include <net/if.h>
40
41 #include <netinet/in.h>
42 #include <netinet/in_systm.h>
43 #include <netinet/ip.h>
44 #include <netinet/if_ether.h>
45 #include <netinet/ip_var.h>
46 #include <netinet/udp.h>
47 #include <netinet/udp_var.h>
48 #include <netinet/tcp.h>
49 #include <netinet/tcpip.h>
50
51 #include <ctype.h>
52 #include <errno.h>
53 #include <netdb.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <unistd.h>
58
59 /*
60 * Make "pcap.h" not include "pcap/bpf.h"; we are going to include the
61 * native OS version, as we need various BPF ioctls from it.
62 */
63 #define PCAP_DONT_INCLUDE_PCAP_BPF_H
64 #include <net/bpf.h>
65
66 #include "pcap-int.h"
67
68 #ifdef HAVE_OS_PROTO_H
69 #include "os-proto.h"
70 #endif
71
72 /*
73 * FDDI packets are padded to make everything line up on a nice boundary.
74 */
75 #define PCAP_FDDIPAD 3
76
77 /*
78 * Private data for capturing on Ultrix and DEC OSF/1^WDigital UNIX^W^W
79 * Tru64 UNIX packetfilter devices.
80 */
81 struct pcap_pf {
82 int filtering_in_kernel; /* using kernel filter */
83 u_long TotPkts; /* can't oflow for 79 hrs on ether */
84 u_long TotAccepted; /* count accepted by filter */
85 u_long TotDrops; /* count of dropped packets */
86 long TotMissed; /* missed by i/f during this run */
87 long OrigMissed; /* missed by i/f before this run */
88 };
89
90 static int pcap_setfilter_pf(pcap_t *, struct bpf_program *);
91
92 /*
93 * BUFSPACE is the size in bytes of the packet read buffer. Most tcpdump
94 * applications aren't going to need more than 200 bytes of packet header
95 * and the read shouldn't return more packets than packetfilter's internal
96 * queue limit (bounded at 256).
97 */
98 #define BUFSPACE (200 * 256)
99
100 static int
pcap_read_pf(pcap_t * pc,int cnt,pcap_handler callback,u_char * user)101 pcap_read_pf(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
102 {
103 struct pcap_pf *pf = pc->priv;
104 register u_char *p, *bp;
105 register int cc, n, buflen, inc;
106 register struct enstamp *sp;
107 #ifdef LBL_ALIGN
108 struct enstamp stamp;
109 #endif
110 register u_int pad;
111
112 again:
113 cc = pc->cc;
114 if (cc == 0) {
115 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
116 if (cc < 0) {
117 if (errno == EWOULDBLOCK)
118 return (0);
119 if (errno == EINVAL &&
120 lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
121 /*
122 * Due to a kernel bug, after 2^31 bytes,
123 * the kernel file offset overflows and
124 * read fails with EINVAL. The lseek()
125 * to 0 will fix things.
126 */
127 (void)lseek(pc->fd, 0L, SEEK_SET);
128 goto again;
129 }
130 pcap_snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
131 pcap_strerror(errno));
132 return (-1);
133 }
134 bp = (u_char *)pc->buffer + pc->offset;
135 } else
136 bp = pc->bp;
137 /*
138 * Loop through each packet.
139 */
140 n = 0;
141 pad = pc->fddipad;
142 while (cc > 0) {
143 /*
144 * Has "pcap_breakloop()" been called?
145 * If so, return immediately - if we haven't read any
146 * packets, clear the flag and return -2 to indicate
147 * that we were told to break out of the loop, otherwise
148 * leave the flag set, so that the *next* call will break
149 * out of the loop without having read any packets, and
150 * return the number of packets we've processed so far.
151 */
152 if (pc->break_loop) {
153 if (n == 0) {
154 pc->break_loop = 0;
155 return (-2);
156 } else {
157 pc->cc = cc;
158 pc->bp = bp;
159 return (n);
160 }
161 }
162 if (cc < sizeof(*sp)) {
163 pcap_snprintf(pc->errbuf, sizeof(pc->errbuf),
164 "pf short read (%d)", cc);
165 return (-1);
166 }
167 #ifdef LBL_ALIGN
168 if ((long)bp & 3) {
169 sp = &stamp;
170 memcpy((char *)sp, (char *)bp, sizeof(*sp));
171 } else
172 #endif
173 sp = (struct enstamp *)bp;
174 if (sp->ens_stamplen != sizeof(*sp)) {
175 pcap_snprintf(pc->errbuf, sizeof(pc->errbuf),
176 "pf short stamplen (%d)",
177 sp->ens_stamplen);
178 return (-1);
179 }
180
181 p = bp + sp->ens_stamplen;
182 buflen = sp->ens_count;
183 if (buflen > pc->snapshot)
184 buflen = pc->snapshot;
185
186 /* Calculate inc before possible pad update */
187 inc = ENALIGN(buflen + sp->ens_stamplen);
188 cc -= inc;
189 bp += inc;
190 pf->TotPkts++;
191 pf->TotDrops += sp->ens_dropped;
192 pf->TotMissed = sp->ens_ifoverflows;
193 if (pf->OrigMissed < 0)
194 pf->OrigMissed = pf->TotMissed;
195
196 /*
197 * Short-circuit evaluation: if using BPF filter
198 * in kernel, no need to do it now - we already know
199 * the packet passed the filter.
200 *
201 * Note: the filter code was generated assuming
202 * that pc->fddipad was the amount of padding
203 * before the header, as that's what's required
204 * in the kernel, so we run the filter before
205 * skipping that padding.
206 */
207 if (pf->filtering_in_kernel ||
208 bpf_filter(pc->fcode.bf_insns, p, sp->ens_count, buflen)) {
209 struct pcap_pkthdr h;
210 pf->TotAccepted++;
211 h.ts = sp->ens_tstamp;
212 h.len = sp->ens_count - pad;
213 p += pad;
214 buflen -= pad;
215 h.caplen = buflen;
216 (*callback)(user, &h, p);
217 if (++n >= cnt && !PACKET_COUNT_IS_UNLIMITED(cnt)) {
218 pc->cc = cc;
219 pc->bp = bp;
220 return (n);
221 }
222 }
223 }
224 pc->cc = 0;
225 return (n);
226 }
227
228 static int
pcap_inject_pf(pcap_t * p,const void * buf,size_t size)229 pcap_inject_pf(pcap_t *p, const void *buf, size_t size)
230 {
231 int ret;
232
233 ret = write(p->fd, buf, size);
234 if (ret == -1) {
235 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
236 pcap_strerror(errno));
237 return (-1);
238 }
239 return (ret);
240 }
241
242 static int
pcap_stats_pf(pcap_t * p,struct pcap_stat * ps)243 pcap_stats_pf(pcap_t *p, struct pcap_stat *ps)
244 {
245 struct pcap_pf *pf = p->priv;
246
247 /*
248 * If packet filtering is being done in the kernel:
249 *
250 * "ps_recv" counts only packets that passed the filter.
251 * This does not include packets dropped because we
252 * ran out of buffer space. (XXX - perhaps it should,
253 * by adding "ps_drop" to "ps_recv", for compatibility
254 * with some other platforms. On the other hand, on
255 * some platforms "ps_recv" counts only packets that
256 * passed the filter, and on others it counts packets
257 * that didn't pass the filter....)
258 *
259 * "ps_drop" counts packets that passed the kernel filter
260 * (if any) but were dropped because the input queue was
261 * full.
262 *
263 * "ps_ifdrop" counts packets dropped by the network
264 * inteface (regardless of whether they would have passed
265 * the input filter, of course).
266 *
267 * If packet filtering is not being done in the kernel:
268 *
269 * "ps_recv" counts only packets that passed the filter.
270 *
271 * "ps_drop" counts packets that were dropped because the
272 * input queue was full, regardless of whether they passed
273 * the userland filter.
274 *
275 * "ps_ifdrop" counts packets dropped by the network
276 * inteface (regardless of whether they would have passed
277 * the input filter, of course).
278 *
279 * These statistics don't include packets not yet read from
280 * the kernel by libpcap, but they may include packets not
281 * yet read from libpcap by the application.
282 */
283 ps->ps_recv = pf->TotAccepted;
284 ps->ps_drop = pf->TotDrops;
285 ps->ps_ifdrop = pf->TotMissed - pf->OrigMissed;
286 return (0);
287 }
288
289 /*
290 * We include the OS's <net/bpf.h>, not our "pcap/bpf.h", so we probably
291 * don't get DLT_DOCSIS defined.
292 */
293 #ifndef DLT_DOCSIS
294 #define DLT_DOCSIS 143
295 #endif
296
297 static int
pcap_activate_pf(pcap_t * p)298 pcap_activate_pf(pcap_t *p)
299 {
300 struct pcap_pf *pf = p->priv;
301 short enmode;
302 int backlog = -1; /* request the most */
303 struct enfilter Filter;
304 struct endevp devparams;
305
306 /*
307 * Initially try a read/write open (to allow the inject
308 * method to work). If that fails due to permission
309 * issues, fall back to read-only. This allows a
310 * non-root user to be granted specific access to pcap
311 * capabilities via file permissions.
312 *
313 * XXX - we should have an API that has a flag that
314 * controls whether to open read-only or read-write,
315 * so that denial of permission to send (or inability
316 * to send, if sending packets isn't supported on
317 * the device in question) can be indicated at open
318 * time.
319 *
320 * XXX - we assume here that "pfopen()" does not, in fact, modify
321 * its argument, even though it takes a "char *" rather than a
322 * "const char *" as its first argument. That appears to be
323 * the case, at least on Digital UNIX 4.0.
324 *
325 * XXX - is there an error that means "no such device"? Is
326 * there one that means "that device doesn't support pf"?
327 */
328 p->fd = pfopen(p->opt.device, O_RDWR);
329 if (p->fd == -1 && errno == EACCES)
330 p->fd = pfopen(p->opt.device, O_RDONLY);
331 if (p->fd < 0) {
332 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
333 your system may not be properly configured; see the packetfilter(4) man page\n",
334 p->opt.device, pcap_strerror(errno));
335 goto bad;
336 }
337 pf->OrigMissed = -1;
338 enmode = ENTSTAMP|ENNONEXCL;
339 if (!p->opt.immediate)
340 enmode |= ENBATCH;
341 if (p->opt.promisc)
342 enmode |= ENPROMISC;
343 if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
344 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
345 pcap_strerror(errno));
346 goto bad;
347 }
348 #ifdef ENCOPYALL
349 /* Try to set COPYALL mode so that we see packets to ourself */
350 enmode = ENCOPYALL;
351 (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
352 #endif
353 /* set the backlog */
354 if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
355 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
356 pcap_strerror(errno));
357 goto bad;
358 }
359 /* discover interface type */
360 if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
361 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
362 pcap_strerror(errno));
363 goto bad;
364 }
365 /* HACK: to compile prior to Ultrix 4.2 */
366 #ifndef ENDT_FDDI
367 #define ENDT_FDDI 4
368 #endif
369 switch (devparams.end_dev_type) {
370
371 case ENDT_10MB:
372 p->linktype = DLT_EN10MB;
373 p->offset = 2;
374 /*
375 * This is (presumably) a real Ethernet capture; give it a
376 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
377 * that an application can let you choose it, in case you're
378 * capturing DOCSIS traffic that a Cisco Cable Modem
379 * Termination System is putting out onto an Ethernet (it
380 * doesn't put an Ethernet header onto the wire, it puts raw
381 * DOCSIS frames out on the wire inside the low-level
382 * Ethernet framing).
383 */
384 p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
385 /*
386 * If that fails, just leave the list empty.
387 */
388 if (p->dlt_list != NULL) {
389 p->dlt_list[0] = DLT_EN10MB;
390 p->dlt_list[1] = DLT_DOCSIS;
391 p->dlt_count = 2;
392 }
393 break;
394
395 case ENDT_FDDI:
396 p->linktype = DLT_FDDI;
397 break;
398
399 #ifdef ENDT_SLIP
400 case ENDT_SLIP:
401 p->linktype = DLT_SLIP;
402 break;
403 #endif
404
405 #ifdef ENDT_PPP
406 case ENDT_PPP:
407 p->linktype = DLT_PPP;
408 break;
409 #endif
410
411 #ifdef ENDT_LOOPBACK
412 case ENDT_LOOPBACK:
413 /*
414 * It appears to use Ethernet framing, at least on
415 * Digital UNIX 4.0.
416 */
417 p->linktype = DLT_EN10MB;
418 p->offset = 2;
419 break;
420 #endif
421
422 #ifdef ENDT_TRN
423 case ENDT_TRN:
424 p->linktype = DLT_IEEE802;
425 break;
426 #endif
427
428 default:
429 /*
430 * XXX - what about ENDT_IEEE802? The pfilt.h header
431 * file calls this "IEEE 802 networks (non-Ethernet)",
432 * but that doesn't specify a specific link layer type;
433 * it could be 802.4, or 802.5 (except that 802.5 is
434 * ENDT_TRN), or 802.6, or 802.11, or.... That's why
435 * DLT_IEEE802 was hijacked to mean Token Ring in various
436 * BSDs, and why we went along with that hijacking.
437 *
438 * XXX - what about ENDT_HDLC and ENDT_NULL?
439 * Presumably, as ENDT_OTHER is just "Miscellaneous
440 * framing", there's not much we can do, as that
441 * doesn't specify a particular type of header.
442 */
443 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
444 "unknown data-link type %u", devparams.end_dev_type);
445 goto bad;
446 }
447 /* set truncation */
448 if (p->linktype == DLT_FDDI) {
449 p->fddipad = PCAP_FDDIPAD;
450
451 /* packetfilter includes the padding in the snapshot */
452 p->snapshot += PCAP_FDDIPAD;
453 } else
454 p->fddipad = 0;
455 if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&p->snapshot) < 0) {
456 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
457 pcap_strerror(errno));
458 goto bad;
459 }
460 /* accept all packets */
461 memset(&Filter, 0, sizeof(Filter));
462 Filter.enf_Priority = 37; /* anything > 2 */
463 Filter.enf_FilterLen = 0; /* means "always true" */
464 if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
465 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
466 pcap_strerror(errno));
467 goto bad;
468 }
469
470 if (p->opt.timeout != 0) {
471 struct timeval timeout;
472 timeout.tv_sec = p->opt.timeout / 1000;
473 timeout.tv_usec = (p->opt.timeout * 1000) % 1000000;
474 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
475 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
476 pcap_strerror(errno));
477 goto bad;
478 }
479 }
480
481 p->bufsize = BUFSPACE;
482 p->buffer = malloc(p->bufsize + p->offset);
483 if (p->buffer == NULL) {
484 strlcpy(p->errbuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
485 goto bad;
486 }
487
488 /*
489 * "select()" and "poll()" work on packetfilter devices.
490 */
491 p->selectable_fd = p->fd;
492
493 p->read_op = pcap_read_pf;
494 p->inject_op = pcap_inject_pf;
495 p->setfilter_op = pcap_setfilter_pf;
496 p->setdirection_op = NULL; /* Not implemented. */
497 p->set_datalink_op = NULL; /* can't change data link type */
498 p->getnonblock_op = pcap_getnonblock_fd;
499 p->setnonblock_op = pcap_setnonblock_fd;
500 p->stats_op = pcap_stats_pf;
501
502 return (0);
503 bad:
504 pcap_cleanup_live_common(p);
505 return (PCAP_ERROR);
506 }
507
508 pcap_t *
pcap_create_interface(const char * device _U_,char * ebuf)509 pcap_create_interface(const char *device _U_, char *ebuf)
510 {
511 pcap_t *p;
512
513 p = pcap_create_common(ebuf, sizeof (struct pcap_pf));
514 if (p == NULL)
515 return (NULL);
516
517 p->activate_op = pcap_activate_pf;
518 return (p);
519 }
520
521 /*
522 * XXX - is there an error from pfopen() that means "no such device"?
523 * Is there one that means "that device doesn't support pf"?
524 */
525 static int
can_be_bound(const char * name _U_)526 can_be_bound(const char *name _U_)
527 {
528 return (1);
529 }
530
531 int
pcap_platform_finddevs(pcap_if_t ** alldevsp,char * errbuf)532 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
533 {
534 return (pcap_findalldevs_interfaces(alldevsp, errbuf, can_be_bound));
535 }
536
537 static int
pcap_setfilter_pf(pcap_t * p,struct bpf_program * fp)538 pcap_setfilter_pf(pcap_t *p, struct bpf_program *fp)
539 {
540 struct pcap_pf *pf = p->priv;
541 struct bpf_version bv;
542
543 /*
544 * See if BIOCVERSION works. If not, we assume the kernel doesn't
545 * support BPF-style filters (it's not documented in the bpf(7)
546 * or packetfiler(7) man pages, but the code used to fail if
547 * BIOCSETF worked but BIOCVERSION didn't, and I've seen it do
548 * kernel filtering in DU 4.0, so presumably BIOCVERSION works
549 * there, at least).
550 */
551 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) >= 0) {
552 /*
553 * OK, we have the version of the BPF interpreter;
554 * is it the same major version as us, and the same
555 * or better minor version?
556 */
557 if (bv.bv_major == BPF_MAJOR_VERSION &&
558 bv.bv_minor >= BPF_MINOR_VERSION) {
559 /*
560 * Yes. Try to install the filter.
561 */
562 if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
563 pcap_snprintf(p->errbuf, sizeof(p->errbuf),
564 "BIOCSETF: %s", pcap_strerror(errno));
565 return (-1);
566 }
567
568 /*
569 * OK, that succeeded. We're doing filtering in
570 * the kernel. (We assume we don't have a
571 * userland filter installed - that'd require
572 * a previous version check to have failed but
573 * this one to succeed.)
574 *
575 * XXX - this message should be supplied to the
576 * application as a warning of some sort,
577 * except that if it's a GUI application, it's
578 * not clear that it should be displayed in
579 * a window to annoy the user.
580 */
581 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
582 pf->filtering_in_kernel = 1;
583
584 /*
585 * Discard any previously-received packets,
586 * as they might have passed whatever filter
587 * was formerly in effect, but might not pass
588 * this filter (BIOCSETF discards packets buffered
589 * in the kernel, so you can lose packets in any
590 * case).
591 */
592 p->cc = 0;
593 return (0);
594 }
595
596 /*
597 * We can't use the kernel's BPF interpreter; don't give
598 * up, just log a message and be inefficient.
599 *
600 * XXX - this should really be supplied to the application
601 * as a warning of some sort.
602 */
603 fprintf(stderr,
604 "tcpdump: Requires BPF language %d.%d or higher; kernel is %d.%d\n",
605 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
606 bv.bv_major, bv.bv_minor);
607 }
608
609 /*
610 * We couldn't do filtering in the kernel; do it in userland.
611 */
612 if (install_bpf_program(p, fp) < 0)
613 return (-1);
614
615 /*
616 * XXX - this message should be supplied by the application as
617 * a warning of some sort.
618 */
619 fprintf(stderr, "tcpdump: Filtering in user process\n");
620 pf->filtering_in_kernel = 0;
621 return (0);
622 }
623