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 };
83
84 static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict);
85
86 static int
netfilter_read_linux(pcap_t * handle,int max_packets,pcap_handler callback,u_char * user)87 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
88 {
89 struct pcap_netfilter *handlep = handle->priv;
90 const unsigned char *buf;
91 int count = 0;
92 int len;
93
94 /* ignore interrupt system call error */
95 do {
96 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
97 if (handle->break_loop) {
98 handle->break_loop = 0;
99 return -2;
100 }
101 } while ((len == -1) && (errno == EINTR));
102
103 if (len < 0) {
104 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno));
105 return -1;
106 }
107
108 buf = handle->buffer;
109 while (len >= NLMSG_SPACE(0)) {
110 const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf;
111 u_int32_t msg_len;
112 nftype_t type = OTHER;
113
114 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) {
115 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len);
116 return -1;
117 }
118
119 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
120 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
121 type = NFLOG;
122 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
123 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
124 type = NFQUEUE;
125
126 if (type != OTHER) {
127 const unsigned char *payload = NULL;
128 struct pcap_pkthdr pkth;
129
130 const struct nfgenmsg *nfg = NULL;
131 int id = 0;
132
133 if (handle->linktype != DLT_NFLOG) {
134 const struct nfattr *payload_attr = NULL;
135
136 if (nlh->nlmsg_len < HDR_LENGTH) {
137 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
138 return -1;
139 }
140
141 nfg = NLMSG_DATA(nlh);
142 if (nlh->nlmsg_len > HDR_LENGTH) {
143 struct nfattr *attr = NFM_NFA(nfg);
144 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
145
146 while (NFA_OK(attr, attr_len)) {
147 if (type == NFQUEUE) {
148 switch (NFA_TYPE(attr)) {
149 case NFQA_PACKET_HDR:
150 {
151 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
152
153 id = ntohl(pkt_hdr->packet_id);
154 break;
155 }
156 case NFQA_PAYLOAD:
157 payload_attr = attr;
158 break;
159 }
160
161 } else if (type == NFLOG) {
162 switch (NFA_TYPE(attr)) {
163 case NFULA_PAYLOAD:
164 payload_attr = attr;
165 break;
166 }
167 }
168 attr = NFA_NEXT(attr, attr_len);
169 }
170 }
171
172 if (payload_attr) {
173 payload = NFA_DATA(payload_attr);
174 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
175 }
176
177 } else {
178 payload = NLMSG_DATA(nlh);
179 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
180 }
181
182 if (payload) {
183 /* pkth.caplen = min (payload_len, handle->snapshot); */
184
185 gettimeofday(&pkth.ts, NULL);
186 if (handle->fcode.bf_insns == NULL ||
187 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
188 {
189 handlep->packets_read++;
190 callback(user, &pkth, payload);
191 count++;
192 }
193 }
194
195 if (type == NFQUEUE) {
196 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
197 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
198 so nfg is always initialized to NLMSG_DATA(nlh). */
199 if (nfg != NULL)
200 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
201 }
202 }
203
204 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
205 if (msg_len > len)
206 msg_len = len;
207
208 len -= msg_len;
209 buf += msg_len;
210 }
211 return count;
212 }
213
214 static int
netfilter_set_datalink(pcap_t * handle,int dlt)215 netfilter_set_datalink(pcap_t *handle, int dlt)
216 {
217 handle->linktype = dlt;
218 return 0;
219 }
220
221 static int
netfilter_stats_linux(pcap_t * handle,struct pcap_stat * stats)222 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
223 {
224 struct pcap_netfilter *handlep = handle->priv;
225
226 stats->ps_recv = handlep->packets_read;
227 stats->ps_drop = 0;
228 stats->ps_ifdrop = 0;
229 return 0;
230 }
231
232 static int
netfilter_inject_linux(pcap_t * handle,const void * buf,size_t size)233 netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size)
234 {
235 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices");
236 return (-1);
237 }
238
239 struct my_nfattr {
240 u_int16_t nfa_len;
241 u_int16_t nfa_type;
242 void *data;
243 };
244
245 static int
netfilter_send_config_msg(const pcap_t * handle,u_int16_t msg_type,int ack,u_int8_t family,u_int16_t res_id,const struct my_nfattr * mynfa)246 netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa)
247 {
248 char buf[1024] __attribute__ ((aligned));
249
250 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
251 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
252
253 struct sockaddr_nl snl;
254 static unsigned int seq_id;
255
256 if (!seq_id)
257 seq_id = time(NULL);
258 ++seq_id;
259
260 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
261 nlh->nlmsg_type = msg_type;
262 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
263 nlh->nlmsg_pid = 0; /* to kernel */
264 nlh->nlmsg_seq = seq_id;
265
266 nfg->nfgen_family = family;
267 nfg->version = NFNETLINK_V0;
268 nfg->res_id = htons(res_id);
269
270 if (mynfa) {
271 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
272
273 nfa->nfa_type = mynfa->nfa_type;
274 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
275 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
276 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
277 }
278
279 memset(&snl, 0, sizeof(snl));
280 snl.nl_family = AF_NETLINK;
281
282 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
283 return -1;
284
285 if (!ack)
286 return 0;
287
288 /* waiting for reply loop */
289 do {
290 socklen_t addrlen = sizeof(snl);
291 int len;
292
293 /* ignore interrupt system call error */
294 do {
295 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
296 } while ((len == -1) && (errno == EINTR));
297
298 if (len <= 0)
299 return len;
300
301 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
302 errno = EINVAL;
303 return -1;
304 }
305
306 nlh = (struct nlmsghdr *) buf;
307 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
308 continue;
309
310 while (len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) {
311 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
312 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
313 errno = EBADMSG;
314 return -1;
315 }
316 errno = -(*((int *)NLMSG_DATA(nlh)));
317 return (errno == 0) ? 0 : -1;
318 }
319 nlh = NLMSG_NEXT(nlh, len);
320 }
321 } while (1);
322
323 return -1; /* never here */
324 }
325
326 static int
nflog_send_config_msg(const pcap_t * handle,u_int8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)327 nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
328 {
329 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
330 }
331
332 static int
nflog_send_config_cmd(const pcap_t * handle,u_int16_t group_id,u_int8_t cmd,u_int8_t family)333 nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family)
334 {
335 struct nfulnl_msg_config_cmd msg;
336 struct my_nfattr nfa;
337
338 msg.command = cmd;
339
340 nfa.data = &msg;
341 nfa.nfa_type = NFULA_CFG_CMD;
342 nfa.nfa_len = sizeof(msg);
343
344 return nflog_send_config_msg(handle, family, group_id, &nfa);
345 }
346
347 static int
nflog_send_config_mode(const pcap_t * handle,u_int16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)348 nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
349 {
350 struct nfulnl_msg_config_mode msg;
351 struct my_nfattr nfa;
352
353 msg.copy_range = htonl(copy_range);
354 msg.copy_mode = copy_mode;
355
356 nfa.data = &msg;
357 nfa.nfa_type = NFULA_CFG_MODE;
358 nfa.nfa_len = sizeof(msg);
359
360 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
361 }
362
363 static int
nfqueue_send_verdict(const pcap_t * handle,u_int16_t group_id,u_int32_t id,u_int32_t verdict)364 nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict)
365 {
366 struct nfqnl_msg_verdict_hdr msg;
367 struct my_nfattr nfa;
368
369 msg.id = htonl(id);
370 msg.verdict = htonl(verdict);
371
372 nfa.data = &msg;
373 nfa.nfa_type = NFQA_VERDICT_HDR;
374 nfa.nfa_len = sizeof(msg);
375
376 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
377 }
378
379 static int
nfqueue_send_config_msg(const pcap_t * handle,u_int8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)380 nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
381 {
382 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
383 }
384
385 static int
nfqueue_send_config_cmd(const pcap_t * handle,u_int16_t group_id,u_int8_t cmd,u_int16_t pf)386 nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf)
387 {
388 struct nfqnl_msg_config_cmd msg;
389 struct my_nfattr nfa;
390
391 msg.command = cmd;
392 msg.pf = htons(pf);
393
394 nfa.data = &msg;
395 nfa.nfa_type = NFQA_CFG_CMD;
396 nfa.nfa_len = sizeof(msg);
397
398 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
399 }
400
401 static int
nfqueue_send_config_mode(const pcap_t * handle,u_int16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)402 nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
403 {
404 struct nfqnl_msg_config_params msg;
405 struct my_nfattr nfa;
406
407 msg.copy_range = htonl(copy_range);
408 msg.copy_mode = copy_mode;
409
410 nfa.data = &msg;
411 nfa.nfa_type = NFQA_CFG_PARAMS;
412 nfa.nfa_len = sizeof(msg);
413
414 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
415 }
416
417 static int
netfilter_activate(pcap_t * handle)418 netfilter_activate(pcap_t* handle)
419 {
420 const char *dev = handle->opt.source;
421 unsigned short groups[32];
422 int group_count = 0;
423 nftype_t type = OTHER;
424 int i;
425
426 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
427 dev += strlen(NFLOG_IFACE);
428 type = NFLOG;
429
430 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
431 dev += strlen(NFQUEUE_IFACE);
432 type = NFQUEUE;
433 }
434
435 if (type != OTHER && *dev == ':') {
436 dev++;
437 while (*dev) {
438 long int group_id;
439 char *end_dev;
440
441 if (group_count == 32) {
442 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
443 "Maximum 32 netfilter groups! dev: %s",
444 handle->opt.source);
445 return PCAP_ERROR;
446 }
447
448 group_id = strtol(dev, &end_dev, 0);
449 if (end_dev != dev) {
450 if (group_id < 0 || group_id > 65535) {
451 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
452 "Netfilter group range from 0 to 65535 (got %ld)",
453 group_id);
454 return PCAP_ERROR;
455 }
456
457 groups[group_count++] = (unsigned short) group_id;
458 dev = end_dev;
459 }
460 if (*dev != ',')
461 break;
462 dev++;
463 }
464 }
465
466 if (type == OTHER || *dev) {
467 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
468 "Can't get netfilter group(s) index from %s",
469 handle->opt.source);
470 return PCAP_ERROR;
471 }
472
473 /* if no groups, add default: 0 */
474 if (!group_count) {
475 groups[0] = 0;
476 group_count = 1;
477 }
478
479 /* Initialize some components of the pcap structure. */
480 handle->bufsize = 128 + handle->snapshot;
481 handle->offset = 0;
482 handle->read_op = netfilter_read_linux;
483 handle->inject_op = netfilter_inject_linux;
484 handle->setfilter_op = install_bpf_program; /* no kernel filtering */
485 handle->setdirection_op = NULL;
486 handle->set_datalink_op = netfilter_set_datalink;
487 handle->getnonblock_op = pcap_getnonblock_fd;
488 handle->setnonblock_op = pcap_setnonblock_fd;
489 handle->stats_op = netfilter_stats_linux;
490
491 /* Create netlink socket */
492 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
493 if (handle->fd < 0) {
494 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno));
495 return PCAP_ERROR;
496 }
497
498 if (type == NFLOG) {
499 handle->linktype = DLT_NFLOG;
500 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
501 if (handle->dlt_list != NULL) {
502 handle->dlt_list[0] = DLT_NFLOG;
503 handle->dlt_list[1] = DLT_IPV4;
504 handle->dlt_count = 2;
505 }
506
507 } else
508 handle->linktype = DLT_IPV4;
509
510 handle->buffer = malloc(handle->bufsize);
511 if (!handle->buffer) {
512 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno));
513 goto close_fail;
514 }
515
516 if (type == NFLOG) {
517 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
518 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
519 goto close_fail;
520 }
521
522 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
523 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
524 goto close_fail;
525 }
526
527 /* Bind socket to the nflog groups */
528 for (i = 0; i < group_count; i++) {
529 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
530 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
531 goto close_fail;
532 }
533
534 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
535 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno));
536 goto close_fail;
537 }
538 }
539
540 } else {
541 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
542 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
543 goto close_fail;
544 }
545
546 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
547 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
548 goto close_fail;
549 }
550
551 /* Bind socket to the nfqueue groups */
552 for (i = 0; i < group_count; i++) {
553 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
554 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
555 goto close_fail;
556 }
557
558 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
559 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno));
560 goto close_fail;
561 }
562 }
563 }
564
565 if (handle->opt.rfmon) {
566 /*
567 * Monitor mode doesn't apply to netfilter devices.
568 */
569 pcap_cleanup_live_common(handle);
570 return PCAP_ERROR_RFMON_NOTSUP;
571 }
572
573 if (handle->opt.buffer_size != 0) {
574 /*
575 * Set the socket buffer size to the specified value.
576 */
577 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
578 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno));
579 goto close_fail;
580 }
581 }
582
583 handle->selectable_fd = handle->fd;
584 return 0;
585
586 close_fail:
587 pcap_cleanup_live_common(handle);
588 return PCAP_ERROR;
589 }
590
591 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)592 netfilter_create(const char *device, char *ebuf, int *is_ours)
593 {
594 const char *cp;
595 pcap_t *p;
596
597 /* Does this look like an netfilter device? */
598 cp = strrchr(device, '/');
599 if (cp == NULL)
600 cp = device;
601
602 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
603 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
604 cp += sizeof NFLOG_IFACE - 1;
605 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
606 cp += sizeof NFQUEUE_IFACE - 1;
607 else {
608 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
609 *is_ours = 0;
610 return NULL;
611 }
612
613 /*
614 * Yes - is that either the end of the name, or is it followed
615 * by a colon?
616 */
617 if (*cp != ':' && *cp != '\0') {
618 /* Nope */
619 *is_ours = 0;
620 return NULL;
621 }
622
623 /* OK, it's probably ours. */
624 *is_ours = 1;
625
626 p = pcap_create_common(device, ebuf, sizeof (struct pcap_netfilter));
627 if (p == NULL)
628 return (NULL);
629
630 p->activate_op = netfilter_activate;
631 return (p);
632 }
633
634 int
netfilter_findalldevs(pcap_if_t ** alldevsp,char * err_str)635 netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str)
636 {
637 int sock;
638
639 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
640 if (sock < 0) {
641 /* if netlink is not supported this is not fatal */
642 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
643 return 0;
644 snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s",
645 errno, pcap_strerror(errno));
646 return -1;
647 }
648 close(sock);
649
650 if (pcap_add_if(alldevsp, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0)
651 return -1;
652 if (pcap_add_if(alldevsp, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0)
653 return -1;
654 return 0;
655 }
656