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,
305 "Packet injection is not supported on netfilter devices");
306 return (-1);
307 }
308
309 struct my_nfattr {
310 uint16_t nfa_len;
311 uint16_t nfa_type;
312 void *data;
313 };
314
315 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)316 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)
317 {
318 char buf[1024] __attribute__ ((aligned));
319 memset(buf, 0, sizeof(buf));
320
321 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
322 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
323
324 struct sockaddr_nl snl;
325 static unsigned int seq_id;
326
327 if (!seq_id)
328 seq_id = time(NULL);
329 ++seq_id;
330
331 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
332 nlh->nlmsg_type = msg_type;
333 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
334 nlh->nlmsg_pid = 0; /* to kernel */
335 nlh->nlmsg_seq = seq_id;
336
337 nfg->nfgen_family = family;
338 nfg->version = NFNETLINK_V0;
339 nfg->res_id = htons(res_id);
340
341 if (mynfa) {
342 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
343
344 nfa->nfa_type = mynfa->nfa_type;
345 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
346 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
347 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
348 }
349
350 memset(&snl, 0, sizeof(snl));
351 snl.nl_family = AF_NETLINK;
352
353 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
354 return -1;
355
356 if (!ack)
357 return 0;
358
359 /* waiting for reply loop */
360 do {
361 socklen_t addrlen = sizeof(snl);
362 int len;
363
364 /* ignore interrupt system call error */
365 do {
366 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
367 } while ((len == -1) && (errno == EINTR));
368
369 if (len <= 0)
370 return len;
371
372 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
373 errno = EINVAL;
374 return -1;
375 }
376
377 nlh = (struct nlmsghdr *) buf;
378 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
379 continue;
380
381 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
382 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
383 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
384 errno = EBADMSG;
385 return -1;
386 }
387 errno = -(*((int *)NLMSG_DATA(nlh)));
388 return (errno == 0) ? 0 : -1;
389 }
390 nlh = NLMSG_NEXT(nlh, len);
391 }
392 } while (1);
393
394 return -1; /* never here */
395 }
396
397 static int
nflog_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)398 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
399 {
400 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
401 }
402
403 static int
nflog_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int8_t family)404 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
405 {
406 struct nfulnl_msg_config_cmd msg;
407 struct my_nfattr nfa;
408
409 msg.command = cmd;
410
411 nfa.data = &msg;
412 nfa.nfa_type = NFULA_CFG_CMD;
413 nfa.nfa_len = sizeof(msg);
414
415 return nflog_send_config_msg(handle, family, group_id, &nfa);
416 }
417
418 static int
nflog_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)419 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
420 {
421 struct nfulnl_msg_config_mode msg;
422 struct my_nfattr nfa;
423
424 msg.copy_range = htonl(copy_range);
425 msg.copy_mode = copy_mode;
426
427 nfa.data = &msg;
428 nfa.nfa_type = NFULA_CFG_MODE;
429 nfa.nfa_len = sizeof(msg);
430
431 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
432 }
433
434 static int
nfqueue_send_verdict(const pcap_t * handle,uint16_t group_id,u_int32_t id,u_int32_t verdict)435 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
436 {
437 struct nfqnl_msg_verdict_hdr msg;
438 struct my_nfattr nfa;
439
440 msg.id = htonl(id);
441 msg.verdict = htonl(verdict);
442
443 nfa.data = &msg;
444 nfa.nfa_type = NFQA_VERDICT_HDR;
445 nfa.nfa_len = sizeof(msg);
446
447 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
448 }
449
450 static int
nfqueue_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)451 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
452 {
453 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
454 }
455
456 static int
nfqueue_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int16_t pf)457 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
458 {
459 struct nfqnl_msg_config_cmd msg;
460 struct my_nfattr nfa;
461
462 msg.command = cmd;
463 msg.pf = htons(pf);
464
465 nfa.data = &msg;
466 nfa.nfa_type = NFQA_CFG_CMD;
467 nfa.nfa_len = sizeof(msg);
468
469 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
470 }
471
472 static int
nfqueue_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)473 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
474 {
475 struct nfqnl_msg_config_params msg;
476 struct my_nfattr nfa;
477
478 msg.copy_range = htonl(copy_range);
479 msg.copy_mode = copy_mode;
480
481 nfa.data = &msg;
482 nfa.nfa_type = NFQA_CFG_PARAMS;
483 nfa.nfa_len = sizeof(msg);
484
485 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
486 }
487
488 static int
netfilter_activate(pcap_t * handle)489 netfilter_activate(pcap_t* handle)
490 {
491 const char *dev = handle->opt.device;
492 unsigned short groups[32];
493 int group_count = 0;
494 nftype_t type = OTHER;
495 int i;
496
497 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
498 dev += strlen(NFLOG_IFACE);
499 type = NFLOG;
500
501 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
502 dev += strlen(NFQUEUE_IFACE);
503 type = NFQUEUE;
504 }
505
506 if (type != OTHER && *dev == ':') {
507 dev++;
508 while (*dev) {
509 long int group_id;
510 char *end_dev;
511
512 if (group_count == 32) {
513 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
514 "Maximum 32 netfilter groups! dev: %s",
515 handle->opt.device);
516 return PCAP_ERROR;
517 }
518
519 group_id = strtol(dev, &end_dev, 0);
520 if (end_dev != dev) {
521 if (group_id < 0 || group_id > 65535) {
522 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
523 "Netfilter group range from 0 to 65535 (got %ld)",
524 group_id);
525 return PCAP_ERROR;
526 }
527
528 groups[group_count++] = (unsigned short) group_id;
529 dev = end_dev;
530 }
531 if (*dev != ',')
532 break;
533 dev++;
534 }
535 }
536
537 if (type == OTHER || *dev) {
538 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
539 "Can't get netfilter group(s) index from %s",
540 handle->opt.device);
541 return PCAP_ERROR;
542 }
543
544 /* if no groups, add default: 0 */
545 if (!group_count) {
546 groups[0] = 0;
547 group_count = 1;
548 }
549
550 /*
551 * Turn a negative snapshot value (invalid), a snapshot value of
552 * 0 (unspecified), or a value bigger than the normal maximum
553 * value, into the maximum allowed value.
554 *
555 * If some application really *needs* a bigger snapshot
556 * length, we should just increase MAXIMUM_SNAPLEN.
557 */
558 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
559 handle->snapshot = MAXIMUM_SNAPLEN;
560
561 /* Initialize some components of the pcap structure. */
562 handle->bufsize = 128 + handle->snapshot;
563 handle->offset = 0;
564 handle->read_op = netfilter_read_linux;
565 handle->inject_op = netfilter_inject_linux;
566 handle->setfilter_op = install_bpf_program; /* no kernel filtering */
567 handle->setdirection_op = NULL;
568 handle->set_datalink_op = netfilter_set_datalink;
569 handle->getnonblock_op = pcap_getnonblock_fd;
570 handle->setnonblock_op = pcap_setnonblock_fd;
571 handle->stats_op = netfilter_stats_linux;
572
573 /* Create netlink socket */
574 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
575 if (handle->fd < 0) {
576 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
577 errno, "Can't create raw socket");
578 return PCAP_ERROR;
579 }
580
581 if (type == NFLOG) {
582 handle->linktype = DLT_NFLOG;
583 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
584 if (handle->dlt_list != NULL) {
585 handle->dlt_list[0] = DLT_NFLOG;
586 handle->dlt_list[1] = DLT_IPV4;
587 handle->dlt_count = 2;
588 }
589
590 } else
591 handle->linktype = DLT_IPV4;
592
593 handle->buffer = malloc(handle->bufsize);
594 if (!handle->buffer) {
595 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
596 errno, "Can't allocate dump buffer");
597 goto close_fail;
598 }
599
600 if (type == NFLOG) {
601 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
602 pcap_fmt_errmsg_for_errno(handle->errbuf,
603 PCAP_ERRBUF_SIZE, errno,
604 "NFULNL_CFG_CMD_PF_UNBIND");
605 goto close_fail;
606 }
607
608 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
609 pcap_fmt_errmsg_for_errno(handle->errbuf,
610 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
611 goto close_fail;
612 }
613
614 /* Bind socket to the nflog groups */
615 for (i = 0; i < group_count; i++) {
616 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
617 pcap_fmt_errmsg_for_errno(handle->errbuf,
618 PCAP_ERRBUF_SIZE, errno,
619 "Can't listen on group group index");
620 goto close_fail;
621 }
622
623 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
624 pcap_fmt_errmsg_for_errno(handle->errbuf,
625 PCAP_ERRBUF_SIZE, errno,
626 "NFULNL_COPY_PACKET");
627 goto close_fail;
628 }
629 }
630
631 } else {
632 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
633 pcap_fmt_errmsg_for_errno(handle->errbuf,
634 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
635 goto close_fail;
636 }
637
638 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
639 pcap_fmt_errmsg_for_errno(handle->errbuf,
640 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
641 goto close_fail;
642 }
643
644 /* Bind socket to the nfqueue groups */
645 for (i = 0; i < group_count; i++) {
646 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
647 pcap_fmt_errmsg_for_errno(handle->errbuf,
648 PCAP_ERRBUF_SIZE, errno,
649 "Can't listen on group group index");
650 goto close_fail;
651 }
652
653 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
654 pcap_fmt_errmsg_for_errno(handle->errbuf,
655 PCAP_ERRBUF_SIZE, errno,
656 "NFQNL_COPY_PACKET");
657 goto close_fail;
658 }
659 }
660 }
661
662 if (handle->opt.rfmon) {
663 /*
664 * Monitor mode doesn't apply to netfilter devices.
665 */
666 pcap_cleanup_live_common(handle);
667 return PCAP_ERROR_RFMON_NOTSUP;
668 }
669
670 if (handle->opt.buffer_size != 0) {
671 /*
672 * Set the socket buffer size to the specified value.
673 */
674 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
675 pcap_fmt_errmsg_for_errno(handle->errbuf,
676 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
677 goto close_fail;
678 }
679 }
680
681 handle->selectable_fd = handle->fd;
682 return 0;
683
684 close_fail:
685 pcap_cleanup_live_common(handle);
686 return PCAP_ERROR;
687 }
688
689 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)690 netfilter_create(const char *device, char *ebuf, int *is_ours)
691 {
692 const char *cp;
693 pcap_t *p;
694
695 /* Does this look like an netfilter device? */
696 cp = strrchr(device, '/');
697 if (cp == NULL)
698 cp = device;
699
700 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
701 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
702 cp += sizeof NFLOG_IFACE - 1;
703 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
704 cp += sizeof NFQUEUE_IFACE - 1;
705 else {
706 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
707 *is_ours = 0;
708 return NULL;
709 }
710
711 /*
712 * Yes - is that either the end of the name, or is it followed
713 * by a colon?
714 */
715 if (*cp != ':' && *cp != '\0') {
716 /* Nope */
717 *is_ours = 0;
718 return NULL;
719 }
720
721 /* OK, it's probably ours. */
722 *is_ours = 1;
723
724 p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter));
725 if (p == NULL)
726 return (NULL);
727
728 p->activate_op = netfilter_activate;
729 return (p);
730 }
731
732 int
netfilter_findalldevs(pcap_if_list_t * devlistp,char * err_str)733 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
734 {
735 int sock;
736
737 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
738 if (sock < 0) {
739 /* if netlink is not supported this is not fatal */
740 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
741 return 0;
742 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
743 errno, "Can't open netlink socket");
744 return -1;
745 }
746 close(sock);
747
748 /*
749 * The notion of "connected" vs. "disconnected" doesn't apply.
750 * XXX - what about "up" and "running"?
751 */
752 if (add_dev(devlistp, NFLOG_IFACE,
753 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
754 "Linux netfilter log (NFLOG) interface", err_str) == NULL)
755 return -1;
756 if (add_dev(devlistp, NFQUEUE_IFACE,
757 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
758 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
759 return -1;
760 return 0;
761 }
762