1 /*
2 * Copyright (c) 2011 Jakub Zawadzki
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote
15 * products derived from this software without specific prior written
16 * permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #ifdef HAVE_CONFIG_H
32 #include <config.h>
33 #endif
34
35 #include "pcap-int.h"
36
37 #ifdef NEED_STRERROR_H
38 #include "strerror.h"
39 #endif
40
41 #include <errno.h>
42 #include <stdlib.h>
43 #include <unistd.h>
44 #include <string.h>
45 #include <sys/socket.h>
46 #include <arpa/inet.h>
47
48 #include <time.h>
49 #include <sys/time.h>
50 #include <netinet/in.h>
51 #include <linux/types.h>
52
53 #include <linux/netlink.h>
54 #include <linux/netfilter.h>
55 #include <linux/netfilter/nfnetlink.h>
56 #include <linux/netfilter/nfnetlink_log.h>
57 #include <linux/netfilter/nfnetlink_queue.h>
58
59 /* NOTE: if your program drops privileges after pcap_activate() it WON'T work with nfqueue.
60 * It took me quite some time to debug ;/
61 *
62 * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges,
63 * and in nfqueue we need to send verdict reply after recving packet.
64 *
65 * In tcpdump you can disable dropping privileges with -Z root
66 */
67
68 #include "pcap-netfilter-linux.h"
69
70 #define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg))))
71
72 #define NFLOG_IFACE "nflog"
73 #define NFQUEUE_IFACE "nfqueue"
74
75 typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t;
76
77 /*
78 * Private data for capturing on Linux netfilter sockets.
79 */
80 struct pcap_netfilter {
81 u_int packets_read; /* count of packets read with recvfrom() */
82 u_int packets_nobufs; /* ENOBUFS counter */
83 };
84
85 static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict);
86
87
88 static int
netfilter_read_linux(pcap_t * handle,int max_packets,pcap_handler callback,u_char * user)89 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
90 {
91 struct pcap_netfilter *handlep = handle->priv;
92 register u_char *bp, *ep;
93 int count = 0;
94 ssize_t len;
95
96 /*
97 * Has "pcap_breakloop()" been called?
98 */
99 if (handle->break_loop) {
100 /*
101 * Yes - clear the flag that indicates that it
102 * has, and return PCAP_ERROR_BREAK to indicate
103 * that we were told to break out of the loop.
104 */
105 handle->break_loop = 0;
106 return PCAP_ERROR_BREAK;
107 }
108 len = handle->cc;
109 if (len == 0) {
110 /*
111 * The buffer is empty; refill it.
112 *
113 * We ignore EINTR, as that might just be due to a signal
114 * being delivered - if the signal should interrupt the
115 * loop, the signal handler should call pcap_breakloop()
116 * to set handle->break_loop (we ignore it on other
117 * platforms as well).
118 */
119 do {
120 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
121 if (handle->break_loop) {
122 handle->break_loop = 0;
123 return PCAP_ERROR_BREAK;
124 }
125 if (errno == ENOBUFS)
126 handlep->packets_nobufs++;
127 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS));
128
129 if (len < 0) {
130 pcap_fmt_errmsg_for_errno(handle->errbuf,
131 PCAP_ERRBUF_SIZE, errno, "Can't receive packet");
132 return PCAP_ERROR;
133 }
134
135 bp = (unsigned char *)handle->buffer;
136 } else
137 bp = handle->bp;
138 ep = bp + len;
139 while (bp < ep) {
140 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp;
141 uint32_t msg_len;
142 nftype_t type = OTHER;
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 PCAP_ERROR_BREAK
147 * to indicate that we were told to break out of the loop,
148 * otherwise leave the flag set, so that the *next* call
149 * will break out of the loop without having read any
150 * packets, and return the number of packets we've
151 * processed so far.
152 */
153 if (handle->break_loop) {
154 handle->bp = bp;
155 handle->cc = (int)(ep - bp);
156 if (count == 0) {
157 handle->break_loop = 0;
158 return PCAP_ERROR_BREAK;
159 } else
160 return count;
161 }
162 /*
163 * NLMSG_SPACE(0) might be signed or might be unsigned,
164 * depending on whether the kernel defines NLMSG_ALIGNTO
165 * as 4, which older kernels do, or as 4U, which newer
166 * kernels do.
167 *
168 * ep - bp is of type ptrdiff_t, which is signed.
169 *
170 * To squelch warnings, we cast both to size_t, which
171 * is unsigned; ep >= bp, so the cast is safe.
172 */
173 if ((size_t)(ep - bp) < (size_t)NLMSG_SPACE(0)) {
174 /*
175 * There's less than one netlink message left
176 * in the buffer. Give up.
177 */
178 break;
179 }
180
181 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) {
182 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len);
183 return -1;
184 }
185
186 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
187 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
188 type = NFLOG;
189 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
190 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
191 type = NFQUEUE;
192
193 if (type != OTHER) {
194 const unsigned char *payload = NULL;
195 struct pcap_pkthdr pkth;
196
197 const struct nfgenmsg *nfg = NULL;
198 int id = 0;
199
200 if (handle->linktype != DLT_NFLOG) {
201 const struct nfattr *payload_attr = NULL;
202
203 if (nlh->nlmsg_len < HDR_LENGTH) {
204 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
205 return -1;
206 }
207
208 nfg = NLMSG_DATA(nlh);
209 if (nlh->nlmsg_len > HDR_LENGTH) {
210 struct nfattr *attr = NFM_NFA(nfg);
211 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
212
213 while (NFA_OK(attr, attr_len)) {
214 if (type == NFQUEUE) {
215 switch (NFA_TYPE(attr)) {
216 case NFQA_PACKET_HDR:
217 {
218 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
219
220 id = ntohl(pkt_hdr->packet_id);
221 break;
222 }
223 case NFQA_PAYLOAD:
224 payload_attr = attr;
225 break;
226 }
227
228 } else if (type == NFLOG) {
229 switch (NFA_TYPE(attr)) {
230 case NFULA_PAYLOAD:
231 payload_attr = attr;
232 break;
233 }
234 }
235 attr = NFA_NEXT(attr, attr_len);
236 }
237 }
238
239 if (payload_attr) {
240 payload = NFA_DATA(payload_attr);
241 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
242 }
243
244 } else {
245 payload = NLMSG_DATA(nlh);
246 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
247 }
248
249 if (payload) {
250 /* pkth.caplen = min (payload_len, handle->snapshot); */
251
252 gettimeofday(&pkth.ts, NULL);
253 if (handle->fcode.bf_insns == NULL ||
254 pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
255 {
256 handlep->packets_read++;
257 callback(user, &pkth, payload);
258 count++;
259 }
260 }
261
262 if (type == NFQUEUE) {
263 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
264 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
265 so nfg is always initialized to NLMSG_DATA(nlh). */
266 if (nfg != NULL)
267 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
268 }
269 }
270
271 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
272 /*
273 * If the message length would run past the end of the
274 * buffer, truncate it to the remaining space in the
275 * buffer.
276 *
277 * To squelch warnings, we cast ep - bp to uint32_t, which
278 * is unsigned and is the type of msg_len; ep >= bp, and
279 * len should fit in 32 bits (either it's set from an int
280 * or it's set from a recv() call with a buffer size that's
281 * an int, and we're assuming either ILP32 or LP64), so
282 * the cast is safe.
283 */
284 if (msg_len > (uint32_t)(ep - bp))
285 msg_len = (uint32_t)(ep - bp);
286
287 bp += msg_len;
288 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
289 handle->bp = bp;
290 handle->cc = (int)(ep - bp);
291 if (handle->cc < 0)
292 handle->cc = 0;
293 return count;
294 }
295 }
296
297 handle->cc = 0;
298 return count;
299 }
300
301 static int
netfilter_set_datalink(pcap_t * handle,int dlt)302 netfilter_set_datalink(pcap_t *handle, int dlt)
303 {
304 handle->linktype = dlt;
305 return 0;
306 }
307
308 static int
netfilter_stats_linux(pcap_t * handle,struct pcap_stat * stats)309 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
310 {
311 struct pcap_netfilter *handlep = handle->priv;
312
313 stats->ps_recv = handlep->packets_read;
314 stats->ps_drop = handlep->packets_nobufs;
315 stats->ps_ifdrop = 0;
316 return 0;
317 }
318
319 static int
netfilter_inject_linux(pcap_t * handle,const void * buf _U_,int size _U_)320 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_)
321 {
322 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
323 "Packet injection is not supported on netfilter devices");
324 return (-1);
325 }
326
327 struct my_nfattr {
328 uint16_t nfa_len;
329 uint16_t nfa_type;
330 void *data;
331 };
332
333 static int
netfilter_send_config_msg(const pcap_t * handle,uint16_t msg_type,int ack,u_int8_t family,u_int16_t res_id,const struct my_nfattr * mynfa)334 netfilter_send_config_msg(const pcap_t *handle, uint16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa)
335 {
336 char buf[1024] __attribute__ ((aligned));
337 memset(buf, 0, sizeof(buf));
338
339 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
340 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
341
342 struct sockaddr_nl snl;
343 static unsigned int seq_id;
344
345 if (!seq_id)
346 seq_id = time(NULL);
347 ++seq_id;
348
349 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
350 nlh->nlmsg_type = msg_type;
351 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
352 nlh->nlmsg_pid = 0; /* to kernel */
353 nlh->nlmsg_seq = seq_id;
354
355 nfg->nfgen_family = family;
356 nfg->version = NFNETLINK_V0;
357 nfg->res_id = htons(res_id);
358
359 if (mynfa) {
360 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
361
362 nfa->nfa_type = mynfa->nfa_type;
363 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
364 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
365 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
366 }
367
368 memset(&snl, 0, sizeof(snl));
369 snl.nl_family = AF_NETLINK;
370
371 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
372 return -1;
373
374 if (!ack)
375 return 0;
376
377 /* waiting for reply loop */
378 do {
379 socklen_t addrlen = sizeof(snl);
380 int len;
381
382 /* ignore interrupt system call error */
383 do {
384 /*
385 * The buffer is not so big that its size won't
386 * fit into an int.
387 */
388 len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
389 } while ((len == -1) && (errno == EINTR));
390
391 if (len <= 0)
392 return len;
393
394 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
395 errno = EINVAL;
396 return -1;
397 }
398
399 nlh = (struct nlmsghdr *) buf;
400 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
401 continue;
402
403 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
404 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
405 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
406 errno = EBADMSG;
407 return -1;
408 }
409 errno = -(*((int *)NLMSG_DATA(nlh)));
410 return (errno == 0) ? 0 : -1;
411 }
412 nlh = NLMSG_NEXT(nlh, len);
413 }
414 } while (1);
415
416 return -1; /* never here */
417 }
418
419 static int
nflog_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)420 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
421 {
422 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
423 }
424
425 static int
nflog_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int8_t family)426 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
427 {
428 struct nfulnl_msg_config_cmd msg;
429 struct my_nfattr nfa;
430
431 msg.command = cmd;
432
433 nfa.data = &msg;
434 nfa.nfa_type = NFULA_CFG_CMD;
435 nfa.nfa_len = sizeof(msg);
436
437 return nflog_send_config_msg(handle, family, group_id, &nfa);
438 }
439
440 static int
nflog_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)441 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
442 {
443 struct nfulnl_msg_config_mode msg;
444 struct my_nfattr nfa;
445
446 msg.copy_range = htonl(copy_range);
447 msg.copy_mode = copy_mode;
448
449 nfa.data = &msg;
450 nfa.nfa_type = NFULA_CFG_MODE;
451 nfa.nfa_len = sizeof(msg);
452
453 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
454 }
455
456 static int
nfqueue_send_verdict(const pcap_t * handle,uint16_t group_id,u_int32_t id,u_int32_t verdict)457 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
458 {
459 struct nfqnl_msg_verdict_hdr msg;
460 struct my_nfattr nfa;
461
462 msg.id = htonl(id);
463 msg.verdict = htonl(verdict);
464
465 nfa.data = &msg;
466 nfa.nfa_type = NFQA_VERDICT_HDR;
467 nfa.nfa_len = sizeof(msg);
468
469 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
470 }
471
472 static int
nfqueue_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)473 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
474 {
475 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
476 }
477
478 static int
nfqueue_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int16_t pf)479 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
480 {
481 struct nfqnl_msg_config_cmd msg;
482 struct my_nfattr nfa;
483
484 msg.command = cmd;
485 msg.pf = htons(pf);
486
487 nfa.data = &msg;
488 nfa.nfa_type = NFQA_CFG_CMD;
489 nfa.nfa_len = sizeof(msg);
490
491 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
492 }
493
494 static int
nfqueue_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)495 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
496 {
497 struct nfqnl_msg_config_params msg;
498 struct my_nfattr nfa;
499
500 msg.copy_range = htonl(copy_range);
501 msg.copy_mode = copy_mode;
502
503 nfa.data = &msg;
504 nfa.nfa_type = NFQA_CFG_PARAMS;
505 nfa.nfa_len = sizeof(msg);
506
507 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
508 }
509
510 static int
netfilter_activate(pcap_t * handle)511 netfilter_activate(pcap_t* handle)
512 {
513 const char *dev = handle->opt.device;
514 unsigned short groups[32];
515 int group_count = 0;
516 nftype_t type = OTHER;
517 int i;
518
519 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
520 dev += strlen(NFLOG_IFACE);
521 type = NFLOG;
522
523 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
524 dev += strlen(NFQUEUE_IFACE);
525 type = NFQUEUE;
526 }
527
528 if (type != OTHER && *dev == ':') {
529 dev++;
530 while (*dev) {
531 long int group_id;
532 char *end_dev;
533
534 if (group_count == 32) {
535 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
536 "Maximum 32 netfilter groups! dev: %s",
537 handle->opt.device);
538 return PCAP_ERROR;
539 }
540
541 group_id = strtol(dev, &end_dev, 0);
542 if (end_dev != dev) {
543 if (group_id < 0 || group_id > 65535) {
544 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
545 "Netfilter group range from 0 to 65535 (got %ld)",
546 group_id);
547 return PCAP_ERROR;
548 }
549
550 groups[group_count++] = (unsigned short) group_id;
551 dev = end_dev;
552 }
553 if (*dev != ',')
554 break;
555 dev++;
556 }
557 }
558
559 if (type == OTHER || *dev) {
560 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
561 "Can't get netfilter group(s) index from %s",
562 handle->opt.device);
563 return PCAP_ERROR;
564 }
565
566 /* if no groups, add default: 0 */
567 if (!group_count) {
568 groups[0] = 0;
569 group_count = 1;
570 }
571
572 /*
573 * Turn a negative snapshot value (invalid), a snapshot value of
574 * 0 (unspecified), or a value bigger than the normal maximum
575 * value, into the maximum allowed value.
576 *
577 * If some application really *needs* a bigger snapshot
578 * length, we should just increase MAXIMUM_SNAPLEN.
579 */
580 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
581 handle->snapshot = MAXIMUM_SNAPLEN;
582
583 /* Initialize some components of the pcap structure. */
584 handle->bufsize = 128 + handle->snapshot;
585 handle->offset = 0;
586 handle->read_op = netfilter_read_linux;
587 handle->inject_op = netfilter_inject_linux;
588 handle->setfilter_op = install_bpf_program; /* no kernel filtering */
589 handle->setdirection_op = NULL;
590 handle->set_datalink_op = netfilter_set_datalink;
591 handle->getnonblock_op = pcap_getnonblock_fd;
592 handle->setnonblock_op = pcap_setnonblock_fd;
593 handle->stats_op = netfilter_stats_linux;
594
595 /* Create netlink socket */
596 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
597 if (handle->fd < 0) {
598 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
599 errno, "Can't create raw socket");
600 return PCAP_ERROR;
601 }
602
603 if (type == NFLOG) {
604 handle->linktype = DLT_NFLOG;
605 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
606 if (handle->dlt_list != NULL) {
607 handle->dlt_list[0] = DLT_NFLOG;
608 handle->dlt_list[1] = DLT_IPV4;
609 handle->dlt_count = 2;
610 }
611
612 } else
613 handle->linktype = DLT_IPV4;
614
615 handle->buffer = malloc(handle->bufsize);
616 if (!handle->buffer) {
617 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
618 errno, "Can't allocate dump buffer");
619 goto close_fail;
620 }
621
622 if (type == NFLOG) {
623 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
624 pcap_fmt_errmsg_for_errno(handle->errbuf,
625 PCAP_ERRBUF_SIZE, errno,
626 "NFULNL_CFG_CMD_PF_UNBIND");
627 goto close_fail;
628 }
629
630 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
631 pcap_fmt_errmsg_for_errno(handle->errbuf,
632 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
633 goto close_fail;
634 }
635
636 /* Bind socket to the nflog groups */
637 for (i = 0; i < group_count; i++) {
638 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
639 pcap_fmt_errmsg_for_errno(handle->errbuf,
640 PCAP_ERRBUF_SIZE, errno,
641 "Can't listen on group index");
642 goto close_fail;
643 }
644
645 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
646 pcap_fmt_errmsg_for_errno(handle->errbuf,
647 PCAP_ERRBUF_SIZE, errno,
648 "NFULNL_COPY_PACKET");
649 goto close_fail;
650 }
651 }
652
653 } else {
654 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
655 pcap_fmt_errmsg_for_errno(handle->errbuf,
656 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
657 goto close_fail;
658 }
659
660 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
661 pcap_fmt_errmsg_for_errno(handle->errbuf,
662 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
663 goto close_fail;
664 }
665
666 /* Bind socket to the nfqueue groups */
667 for (i = 0; i < group_count; i++) {
668 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
669 pcap_fmt_errmsg_for_errno(handle->errbuf,
670 PCAP_ERRBUF_SIZE, errno,
671 "Can't listen on group index");
672 goto close_fail;
673 }
674
675 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
676 pcap_fmt_errmsg_for_errno(handle->errbuf,
677 PCAP_ERRBUF_SIZE, errno,
678 "NFQNL_COPY_PACKET");
679 goto close_fail;
680 }
681 }
682 }
683
684 if (handle->opt.rfmon) {
685 /*
686 * Monitor mode doesn't apply to netfilter devices.
687 */
688 pcap_cleanup_live_common(handle);
689 return PCAP_ERROR_RFMON_NOTSUP;
690 }
691
692 if (handle->opt.buffer_size != 0) {
693 /*
694 * Set the socket buffer size to the specified value.
695 */
696 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
697 pcap_fmt_errmsg_for_errno(handle->errbuf,
698 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
699 goto close_fail;
700 }
701 }
702
703 handle->selectable_fd = handle->fd;
704 return 0;
705
706 close_fail:
707 pcap_cleanup_live_common(handle);
708 return PCAP_ERROR;
709 }
710
711 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)712 netfilter_create(const char *device, char *ebuf, int *is_ours)
713 {
714 const char *cp;
715 pcap_t *p;
716
717 /* Does this look like an netfilter device? */
718 cp = strrchr(device, '/');
719 if (cp == NULL)
720 cp = device;
721
722 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
723 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
724 cp += sizeof NFLOG_IFACE - 1;
725 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
726 cp += sizeof NFQUEUE_IFACE - 1;
727 else {
728 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
729 *is_ours = 0;
730 return NULL;
731 }
732
733 /*
734 * Yes - is that either the end of the name, or is it followed
735 * by a colon?
736 */
737 if (*cp != ':' && *cp != '\0') {
738 /* Nope */
739 *is_ours = 0;
740 return NULL;
741 }
742
743 /* OK, it's probably ours. */
744 *is_ours = 1;
745
746 p = PCAP_CREATE_COMMON(ebuf, struct pcap_netfilter);
747 if (p == NULL)
748 return (NULL);
749
750 p->activate_op = netfilter_activate;
751 return (p);
752 }
753
754 int
netfilter_findalldevs(pcap_if_list_t * devlistp,char * err_str)755 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
756 {
757 int sock;
758
759 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
760 if (sock < 0) {
761 /* if netlink is not supported this is not fatal */
762 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
763 return 0;
764 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
765 errno, "Can't open netlink socket");
766 return -1;
767 }
768 close(sock);
769
770 /*
771 * The notion of "connected" vs. "disconnected" doesn't apply.
772 * XXX - what about "up" and "running"?
773 */
774 if (add_dev(devlistp, NFLOG_IFACE,
775 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
776 "Linux netfilter log (NFLOG) interface", err_str) == NULL)
777 return -1;
778 if (add_dev(devlistp, NFQUEUE_IFACE,
779 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
780 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
781 return -1;
782 return 0;
783 }
784