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 privilages 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 privilages,
63 * and in nfqueue we need to send verdict reply after recving packet.
64 *
65 * In tcpdump you can disable dropping privilages 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 int 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 = ep - bp;
156 if (count == 0) {
157 handle->break_loop = 0;
158 return PCAP_ERROR_BREAK;
159 } else
160 return count;
161 }
162 if (ep - bp < NLMSG_SPACE(0)) {
163 /*
164 * There's less than one netlink message left
165 * in the buffer. Give up.
166 */
167 break;
168 }
169
170 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) {
171 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len);
172 return -1;
173 }
174
175 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
176 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
177 type = NFLOG;
178 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
179 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
180 type = NFQUEUE;
181
182 if (type != OTHER) {
183 const unsigned char *payload = NULL;
184 struct pcap_pkthdr pkth;
185
186 const struct nfgenmsg *nfg = NULL;
187 int id = 0;
188
189 if (handle->linktype != DLT_NFLOG) {
190 const struct nfattr *payload_attr = NULL;
191
192 if (nlh->nlmsg_len < HDR_LENGTH) {
193 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
194 return -1;
195 }
196
197 nfg = NLMSG_DATA(nlh);
198 if (nlh->nlmsg_len > HDR_LENGTH) {
199 struct nfattr *attr = NFM_NFA(nfg);
200 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
201
202 while (NFA_OK(attr, attr_len)) {
203 if (type == NFQUEUE) {
204 switch (NFA_TYPE(attr)) {
205 case NFQA_PACKET_HDR:
206 {
207 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
208
209 id = ntohl(pkt_hdr->packet_id);
210 break;
211 }
212 case NFQA_PAYLOAD:
213 payload_attr = attr;
214 break;
215 }
216
217 } else if (type == NFLOG) {
218 switch (NFA_TYPE(attr)) {
219 case NFULA_PAYLOAD:
220 payload_attr = attr;
221 break;
222 }
223 }
224 attr = NFA_NEXT(attr, attr_len);
225 }
226 }
227
228 if (payload_attr) {
229 payload = NFA_DATA(payload_attr);
230 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
231 }
232
233 } else {
234 payload = NLMSG_DATA(nlh);
235 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
236 }
237
238 if (payload) {
239 /* pkth.caplen = min (payload_len, handle->snapshot); */
240
241 gettimeofday(&pkth.ts, NULL);
242 if (handle->fcode.bf_insns == NULL ||
243 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
244 {
245 handlep->packets_read++;
246 callback(user, &pkth, payload);
247 count++;
248 }
249 }
250
251 if (type == NFQUEUE) {
252 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
253 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
254 so nfg is always initialized to NLMSG_DATA(nlh). */
255 if (nfg != NULL)
256 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
257 }
258 }
259
260 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
261 /*
262 * If the message length would run past the end of the
263 * buffer, truncate it to the remaining space in the
264 * buffer.
265 */
266 if (msg_len > ep - bp)
267 msg_len = ep - bp;
268
269 bp += msg_len;
270 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
271 handle->bp = bp;
272 handle->cc = ep - bp;
273 if (handle->cc < 0)
274 handle->cc = 0;
275 return count;
276 }
277 }
278
279 handle->cc = 0;
280 return count;
281 }
282
283 static int
netfilter_set_datalink(pcap_t * handle,int dlt)284 netfilter_set_datalink(pcap_t *handle, int dlt)
285 {
286 handle->linktype = dlt;
287 return 0;
288 }
289
290 static int
netfilter_stats_linux(pcap_t * handle,struct pcap_stat * stats)291 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
292 {
293 struct pcap_netfilter *handlep = handle->priv;
294
295 stats->ps_recv = handlep->packets_read;
296 stats->ps_drop = handlep->packets_nobufs;
297 stats->ps_ifdrop = 0;
298 return 0;
299 }
300
301 static int
netfilter_inject_linux(pcap_t * handle,const void * buf _U_,size_t size _U_)302 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_)
303 {
304 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices");
305 return (-1);
306 }
307
308 struct my_nfattr {
309 uint16_t nfa_len;
310 uint16_t nfa_type;
311 void *data;
312 };
313
314 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)315 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)
316 {
317 char buf[1024] __attribute__ ((aligned));
318
319 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
320 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
321
322 struct sockaddr_nl snl;
323 static unsigned int seq_id;
324
325 if (!seq_id)
326 seq_id = time(NULL);
327 ++seq_id;
328
329 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
330 nlh->nlmsg_type = msg_type;
331 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
332 nlh->nlmsg_pid = 0; /* to kernel */
333 nlh->nlmsg_seq = seq_id;
334
335 nfg->nfgen_family = family;
336 nfg->version = NFNETLINK_V0;
337 nfg->res_id = htons(res_id);
338
339 if (mynfa) {
340 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
341
342 nfa->nfa_type = mynfa->nfa_type;
343 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
344 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
345 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
346 }
347
348 memset(&snl, 0, sizeof(snl));
349 snl.nl_family = AF_NETLINK;
350
351 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
352 return -1;
353
354 if (!ack)
355 return 0;
356
357 /* waiting for reply loop */
358 do {
359 socklen_t addrlen = sizeof(snl);
360 int len;
361
362 /* ignore interrupt system call error */
363 do {
364 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
365 } while ((len == -1) && (errno == EINTR));
366
367 if (len <= 0)
368 return len;
369
370 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
371 errno = EINVAL;
372 return -1;
373 }
374
375 nlh = (struct nlmsghdr *) buf;
376 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
377 continue;
378
379 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
380 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
381 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
382 errno = EBADMSG;
383 return -1;
384 }
385 errno = -(*((int *)NLMSG_DATA(nlh)));
386 return (errno == 0) ? 0 : -1;
387 }
388 nlh = NLMSG_NEXT(nlh, len);
389 }
390 } while (1);
391
392 return -1; /* never here */
393 }
394
395 static int
nflog_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)396 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
397 {
398 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
399 }
400
401 static int
nflog_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int8_t family)402 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
403 {
404 struct nfulnl_msg_config_cmd msg;
405 struct my_nfattr nfa;
406
407 msg.command = cmd;
408
409 nfa.data = &msg;
410 nfa.nfa_type = NFULA_CFG_CMD;
411 nfa.nfa_len = sizeof(msg);
412
413 return nflog_send_config_msg(handle, family, group_id, &nfa);
414 }
415
416 static int
nflog_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)417 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
418 {
419 struct nfulnl_msg_config_mode msg;
420 struct my_nfattr nfa;
421
422 msg.copy_range = htonl(copy_range);
423 msg.copy_mode = copy_mode;
424
425 nfa.data = &msg;
426 nfa.nfa_type = NFULA_CFG_MODE;
427 nfa.nfa_len = sizeof(msg);
428
429 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
430 }
431
432 static int
nfqueue_send_verdict(const pcap_t * handle,uint16_t group_id,u_int32_t id,u_int32_t verdict)433 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
434 {
435 struct nfqnl_msg_verdict_hdr msg;
436 struct my_nfattr nfa;
437
438 msg.id = htonl(id);
439 msg.verdict = htonl(verdict);
440
441 nfa.data = &msg;
442 nfa.nfa_type = NFQA_VERDICT_HDR;
443 nfa.nfa_len = sizeof(msg);
444
445 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
446 }
447
448 static int
nfqueue_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)449 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
450 {
451 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
452 }
453
454 static int
nfqueue_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int16_t pf)455 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
456 {
457 struct nfqnl_msg_config_cmd msg;
458 struct my_nfattr nfa;
459
460 msg.command = cmd;
461 msg.pf = htons(pf);
462
463 nfa.data = &msg;
464 nfa.nfa_type = NFQA_CFG_CMD;
465 nfa.nfa_len = sizeof(msg);
466
467 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
468 }
469
470 static int
nfqueue_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)471 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
472 {
473 struct nfqnl_msg_config_params msg;
474 struct my_nfattr nfa;
475
476 msg.copy_range = htonl(copy_range);
477 msg.copy_mode = copy_mode;
478
479 nfa.data = &msg;
480 nfa.nfa_type = NFQA_CFG_PARAMS;
481 nfa.nfa_len = sizeof(msg);
482
483 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
484 }
485
486 static int
netfilter_activate(pcap_t * handle)487 netfilter_activate(pcap_t* handle)
488 {
489 const char *dev = handle->opt.device;
490 unsigned short groups[32];
491 int group_count = 0;
492 nftype_t type = OTHER;
493 int i;
494
495 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
496 dev += strlen(NFLOG_IFACE);
497 type = NFLOG;
498
499 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
500 dev += strlen(NFQUEUE_IFACE);
501 type = NFQUEUE;
502 }
503
504 if (type != OTHER && *dev == ':') {
505 dev++;
506 while (*dev) {
507 long int group_id;
508 char *end_dev;
509
510 if (group_count == 32) {
511 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
512 "Maximum 32 netfilter groups! dev: %s",
513 handle->opt.device);
514 return PCAP_ERROR;
515 }
516
517 group_id = strtol(dev, &end_dev, 0);
518 if (end_dev != dev) {
519 if (group_id < 0 || group_id > 65535) {
520 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
521 "Netfilter group range from 0 to 65535 (got %ld)",
522 group_id);
523 return PCAP_ERROR;
524 }
525
526 groups[group_count++] = (unsigned short) group_id;
527 dev = end_dev;
528 }
529 if (*dev != ',')
530 break;
531 dev++;
532 }
533 }
534
535 if (type == OTHER || *dev) {
536 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
537 "Can't get netfilter group(s) index from %s",
538 handle->opt.device);
539 return PCAP_ERROR;
540 }
541
542 /* if no groups, add default: 0 */
543 if (!group_count) {
544 groups[0] = 0;
545 group_count = 1;
546 }
547
548 /*
549 * Turn a negative snapshot value (invalid), a snapshot value of
550 * 0 (unspecified), or a value bigger than the normal maximum
551 * value, into the maximum allowed value.
552 *
553 * If some application really *needs* a bigger snapshot
554 * length, we should just increase MAXIMUM_SNAPLEN.
555 */
556 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
557 handle->snapshot = MAXIMUM_SNAPLEN;
558
559 /* Initialize some components of the pcap structure. */
560 handle->bufsize = 128 + handle->snapshot;
561 handle->offset = 0;
562 handle->read_op = netfilter_read_linux;
563 handle->inject_op = netfilter_inject_linux;
564 handle->setfilter_op = install_bpf_program; /* no kernel filtering */
565 handle->setdirection_op = NULL;
566 handle->set_datalink_op = netfilter_set_datalink;
567 handle->getnonblock_op = pcap_getnonblock_fd;
568 handle->setnonblock_op = pcap_setnonblock_fd;
569 handle->stats_op = netfilter_stats_linux;
570
571 /* Create netlink socket */
572 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
573 if (handle->fd < 0) {
574 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
575 errno, "Can't create raw socket");
576 return PCAP_ERROR;
577 }
578
579 if (type == NFLOG) {
580 handle->linktype = DLT_NFLOG;
581 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
582 if (handle->dlt_list != NULL) {
583 handle->dlt_list[0] = DLT_NFLOG;
584 handle->dlt_list[1] = DLT_IPV4;
585 handle->dlt_count = 2;
586 }
587
588 } else
589 handle->linktype = DLT_IPV4;
590
591 handle->buffer = malloc(handle->bufsize);
592 if (!handle->buffer) {
593 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
594 errno, "Can't allocate dump buffer");
595 goto close_fail;
596 }
597
598 if (type == NFLOG) {
599 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
600 pcap_fmt_errmsg_for_errno(handle->errbuf,
601 PCAP_ERRBUF_SIZE, errno,
602 "NFULNL_CFG_CMD_PF_UNBIND");
603 goto close_fail;
604 }
605
606 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
607 pcap_fmt_errmsg_for_errno(handle->errbuf,
608 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
609 goto close_fail;
610 }
611
612 /* Bind socket to the nflog groups */
613 for (i = 0; i < group_count; i++) {
614 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
615 pcap_fmt_errmsg_for_errno(handle->errbuf,
616 PCAP_ERRBUF_SIZE, errno,
617 "Can't listen on group group index");
618 goto close_fail;
619 }
620
621 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
622 pcap_fmt_errmsg_for_errno(handle->errbuf,
623 PCAP_ERRBUF_SIZE, errno,
624 "NFULNL_COPY_PACKET");
625 goto close_fail;
626 }
627 }
628
629 } else {
630 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
631 pcap_fmt_errmsg_for_errno(handle->errbuf,
632 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
633 goto close_fail;
634 }
635
636 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
637 pcap_fmt_errmsg_for_errno(handle->errbuf,
638 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
639 goto close_fail;
640 }
641
642 /* Bind socket to the nfqueue groups */
643 for (i = 0; i < group_count; i++) {
644 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
645 pcap_fmt_errmsg_for_errno(handle->errbuf,
646 PCAP_ERRBUF_SIZE, errno,
647 "Can't listen on group group index");
648 goto close_fail;
649 }
650
651 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
652 pcap_fmt_errmsg_for_errno(handle->errbuf,
653 PCAP_ERRBUF_SIZE, errno,
654 "NFQNL_COPY_PACKET");
655 goto close_fail;
656 }
657 }
658 }
659
660 if (handle->opt.rfmon) {
661 /*
662 * Monitor mode doesn't apply to netfilter devices.
663 */
664 pcap_cleanup_live_common(handle);
665 return PCAP_ERROR_RFMON_NOTSUP;
666 }
667
668 if (handle->opt.buffer_size != 0) {
669 /*
670 * Set the socket buffer size to the specified value.
671 */
672 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
673 pcap_fmt_errmsg_for_errno(handle->errbuf,
674 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
675 goto close_fail;
676 }
677 }
678
679 handle->selectable_fd = handle->fd;
680 return 0;
681
682 close_fail:
683 pcap_cleanup_live_common(handle);
684 return PCAP_ERROR;
685 }
686
687 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)688 netfilter_create(const char *device, char *ebuf, int *is_ours)
689 {
690 const char *cp;
691 pcap_t *p;
692
693 /* Does this look like an netfilter device? */
694 cp = strrchr(device, '/');
695 if (cp == NULL)
696 cp = device;
697
698 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
699 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
700 cp += sizeof NFLOG_IFACE - 1;
701 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
702 cp += sizeof NFQUEUE_IFACE - 1;
703 else {
704 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
705 *is_ours = 0;
706 return NULL;
707 }
708
709 /*
710 * Yes - is that either the end of the name, or is it followed
711 * by a colon?
712 */
713 if (*cp != ':' && *cp != '\0') {
714 /* Nope */
715 *is_ours = 0;
716 return NULL;
717 }
718
719 /* OK, it's probably ours. */
720 *is_ours = 1;
721
722 p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter));
723 if (p == NULL)
724 return (NULL);
725
726 p->activate_op = netfilter_activate;
727 return (p);
728 }
729
730 int
netfilter_findalldevs(pcap_if_list_t * devlistp,char * err_str)731 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
732 {
733 int sock;
734
735 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
736 if (sock < 0) {
737 /* if netlink is not supported this is not fatal */
738 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
739 return 0;
740 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
741 errno, "Can't open netlink socket");
742 return -1;
743 }
744 close(sock);
745
746 /*
747 * The notion of "connected" vs. "disconnected" doesn't apply.
748 * XXX - what about "up" and "running"?
749 */
750 if (add_dev(devlistp, NFLOG_IFACE,
751 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
752 "Linux netfilter log (NFLOG) interface", err_str) == NULL)
753 return -1;
754 if (add_dev(devlistp, NFQUEUE_IFACE,
755 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
756 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
757 return -1;
758 return 0;
759 }
760