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1 office 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
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 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 snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
131 pcap_strerror(errno));
132 return (-1);
133 }
134 bp = 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 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 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
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 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
236 pcap_strerror(errno));
237 return (-1);
238 }
239 return (ret);
240 }
241  
242 static int
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
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 p->fd = pfopen(p->opt.source, O_RDWR);
326 if (p->fd == -1 && errno == EACCES)
327 p->fd = pfopen(p->opt.source, O_RDONLY);
328 if (p->fd < 0) {
329 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
330 your system may not be properly configured; see the packetfilter(4) man page\n",
331 p->opt.source, pcap_strerror(errno));
332 goto bad;
333 }
334 pf->OrigMissed = -1;
335 enmode = ENTSTAMP|ENNONEXCL;
336 if (!p->opt.immediate)
337 enmode |= ENBATCH;
338 if (p->opt.promisc)
339 enmode |= ENPROMISC;
340 if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
341 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
342 pcap_strerror(errno));
343 goto bad;
344 }
345 #ifdef ENCOPYALL
346 /* Try to set COPYALL mode so that we see packets to ourself */
347 enmode = ENCOPYALL;
348 (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
349 #endif
350 /* set the backlog */
351 if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
352 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
353 pcap_strerror(errno));
354 goto bad;
355 }
356 /* discover interface type */
357 if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
358 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
359 pcap_strerror(errno));
360 goto bad;
361 }
362 /* HACK: to compile prior to Ultrix 4.2 */
363 #ifndef ENDT_FDDI
364 #define ENDT_FDDI 4
365 #endif
366 switch (devparams.end_dev_type) {
367  
368 case ENDT_10MB:
369 p->linktype = DLT_EN10MB;
370 p->offset = 2;
371 /*
372 * This is (presumably) a real Ethernet capture; give it a
373 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
374 * that an application can let you choose it, in case you're
375 * capturing DOCSIS traffic that a Cisco Cable Modem
376 * Termination System is putting out onto an Ethernet (it
377 * doesn't put an Ethernet header onto the wire, it puts raw
378 * DOCSIS frames out on the wire inside the low-level
379 * Ethernet framing).
380 */
381 p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
382 /*
383 * If that fails, just leave the list empty.
384 */
385 if (p->dlt_list != NULL) {
386 p->dlt_list[0] = DLT_EN10MB;
387 p->dlt_list[1] = DLT_DOCSIS;
388 p->dlt_count = 2;
389 }
390 break;
391  
392 case ENDT_FDDI:
393 p->linktype = DLT_FDDI;
394 break;
395  
396 #ifdef ENDT_SLIP
397 case ENDT_SLIP:
398 p->linktype = DLT_SLIP;
399 break;
400 #endif
401  
402 #ifdef ENDT_PPP
403 case ENDT_PPP:
404 p->linktype = DLT_PPP;
405 break;
406 #endif
407  
408 #ifdef ENDT_LOOPBACK
409 case ENDT_LOOPBACK:
410 /*
411 * It appears to use Ethernet framing, at least on
412 * Digital UNIX 4.0.
413 */
414 p->linktype = DLT_EN10MB;
415 p->offset = 2;
416 break;
417 #endif
418  
419 #ifdef ENDT_TRN
420 case ENDT_TRN:
421 p->linktype = DLT_IEEE802;
422 break;
423 #endif
424  
425 default:
426 /*
427 * XXX - what about ENDT_IEEE802? The pfilt.h header
428 * file calls this "IEEE 802 networks (non-Ethernet)",
429 * but that doesn't specify a specific link layer type;
430 * it could be 802.4, or 802.5 (except that 802.5 is
431 * ENDT_TRN), or 802.6, or 802.11, or.... That's why
432 * DLT_IEEE802 was hijacked to mean Token Ring in various
433 * BSDs, and why we went along with that hijacking.
434 *
435 * XXX - what about ENDT_HDLC and ENDT_NULL?
436 * Presumably, as ENDT_OTHER is just "Miscellaneous
437 * framing", there's not much we can do, as that
438 * doesn't specify a particular type of header.
439 */
440 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
441 "unknown data-link type %u", devparams.end_dev_type);
442 goto bad;
443 }
444 /* set truncation */
445 if (p->linktype == DLT_FDDI) {
446 p->fddipad = PCAP_FDDIPAD;
447  
448 /* packetfilter includes the padding in the snapshot */
449 p->snapshot += PCAP_FDDIPAD;
450 } else
451 p->fddipad = 0;
452 if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&p->snapshot) < 0) {
453 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
454 pcap_strerror(errno));
455 goto bad;
456 }
457 /* accept all packets */
458 memset(&Filter, 0, sizeof(Filter));
459 Filter.enf_Priority = 37; /* anything > 2 */
460 Filter.enf_FilterLen = 0; /* means "always true" */
461 if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
462 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
463 pcap_strerror(errno));
464 goto bad;
465 }
466  
467 if (p->opt.timeout != 0) {
468 struct timeval timeout;
469 timeout.tv_sec = p->opt.timeout / 1000;
470 timeout.tv_usec = (p->opt.timeout * 1000) % 1000000;
471 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
472 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
473 pcap_strerror(errno));
474 goto bad;
475 }
476 }
477  
478 p->bufsize = BUFSPACE;
479 p->buffer = (u_char*)malloc(p->bufsize + p->offset);
480 if (p->buffer == NULL) {
481 strlcpy(p->errbuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
482 goto bad;
483 }
484  
485 /*
486 * "select()" and "poll()" work on packetfilter devices.
487 */
488 p->selectable_fd = p->fd;
489  
490 p->read_op = pcap_read_pf;
491 p->inject_op = pcap_inject_pf;
492 p->setfilter_op = pcap_setfilter_pf;
493 p->setdirection_op = NULL; /* Not implemented. */
494 p->set_datalink_op = NULL; /* can't change data link type */
495 p->getnonblock_op = pcap_getnonblock_fd;
496 p->setnonblock_op = pcap_setnonblock_fd;
497 p->stats_op = pcap_stats_pf;
498  
499 return (0);
500 bad:
501 pcap_cleanup_live_common(p);
502 return (PCAP_ERROR);
503 }
504  
505 pcap_t *
506 pcap_create_interface(const char *device, char *ebuf)
507 {
508 pcap_t *p;
509  
510 p = pcap_create_common(device, ebuf, sizeof (struct pcap_pf));
511 if (p == NULL)
512 return (NULL);
513  
514 p->activate_op = pcap_activate_pf;
515 return (p);
516 }
517  
518 int
519 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
520 {
521 return (0);
522 }
523  
524 static int
525 pcap_setfilter_pf(pcap_t *p, struct bpf_program *fp)
526 {
527 struct pcap_pf *pf = p->priv;
528 struct bpf_version bv;
529  
530 /*
531 * See if BIOCVERSION works. If not, we assume the kernel doesn't
532 * support BPF-style filters (it's not documented in the bpf(7)
533 * or packetfiler(7) man pages, but the code used to fail if
534 * BIOCSETF worked but BIOCVERSION didn't, and I've seen it do
535 * kernel filtering in DU 4.0, so presumably BIOCVERSION works
536 * there, at least).
537 */
538 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) >= 0) {
539 /*
540 * OK, we have the version of the BPF interpreter;
541 * is it the same major version as us, and the same
542 * or better minor version?
543 */
544 if (bv.bv_major == BPF_MAJOR_VERSION &&
545 bv.bv_minor >= BPF_MINOR_VERSION) {
546 /*
547 * Yes. Try to install the filter.
548 */
549 if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
550 snprintf(p->errbuf, sizeof(p->errbuf),
551 "BIOCSETF: %s", pcap_strerror(errno));
552 return (-1);
553 }
554  
555 /*
556 * OK, that succeeded. We're doing filtering in
557 * the kernel. (We assume we don't have a
558 * userland filter installed - that'd require
559 * a previous version check to have failed but
560 * this one to succeed.)
561 *
562 * XXX - this message should be supplied to the
563 * application as a warning of some sort,
564 * except that if it's a GUI application, it's
565 * not clear that it should be displayed in
566 * a window to annoy the user.
567 */
568 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
569 pf->filtering_in_kernel = 1;
570  
571 /*
572 * Discard any previously-received packets,
573 * as they might have passed whatever filter
574 * was formerly in effect, but might not pass
575 * this filter (BIOCSETF discards packets buffered
576 * in the kernel, so you can lose packets in any
577 * case).
578 */
579 p->cc = 0;
580 return (0);
581 }
582  
583 /*
584 * We can't use the kernel's BPF interpreter; don't give
585 * up, just log a message and be inefficient.
586 *
587 * XXX - this should really be supplied to the application
588 * as a warning of some sort.
589 */
590 fprintf(stderr,
591 "tcpdump: Requires BPF language %d.%d or higher; kernel is %d.%d\n",
592 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
593 bv.bv_major, bv.bv_minor);
594 }
595  
596 /*
597 * We couldn't do filtering in the kernel; do it in userland.
598 */
599 if (install_bpf_program(p, fp) < 0)
600 return (-1);
601  
602 /*
603 * XXX - this message should be supplied by the application as
604 * a warning of some sort.
605 */
606 fprintf(stderr, "tcpdump: Filtering in user process\n");
607 pf->filtering_in_kernel = 0;
608 return (0);
609 }