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 #include "diag-control.h"
37
38 #ifdef NEED_STRERROR_H
39 #include "strerror.h"
40 #endif
41
42 #include <errno.h>
43 #include <stdlib.h>
44 #include <unistd.h>
45 #include <string.h>
46 #include <sys/socket.h>
47 #include <arpa/inet.h>
48
49 #include <time.h>
50 #include <sys/time.h>
51 #include <netinet/in.h>
52 #include <linux/types.h>
53
54 #include <linux/netlink.h>
55 #include <linux/netfilter.h>
56 #include <linux/netfilter/nfnetlink.h>
57 #include <linux/netfilter/nfnetlink_log.h>
58 #include <linux/netfilter/nfnetlink_queue.h>
59
60 /* NOTE: if your program drops privileges after pcap_activate() it WON'T work with nfqueue.
61 * It took me quite some time to debug ;/
62 *
63 * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges,
64 * and in nfqueue we need to send verdict reply after recving packet.
65 *
66 * In tcpdump you can disable dropping privileges with -Z root
67 */
68
69 #include "pcap-netfilter-linux.h"
70
71 #define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg))))
72
73 #define NFLOG_IFACE "nflog"
74 #define NFQUEUE_IFACE "nfqueue"
75
76 typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t;
77
78 /*
79 * Private data for capturing on Linux netfilter sockets.
80 */
81 struct pcap_netfilter {
82 u_int packets_read; /* count of packets read with recvfrom() */
83 u_int packets_nobufs; /* ENOBUFS counter */
84 };
85
86 static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict);
87
88
89 static int
netfilter_read_linux(pcap_t * handle,int max_packets,pcap_handler callback,u_char * user)90 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
91 {
92 struct pcap_netfilter *handlep = handle->priv;
93 register u_char *bp, *ep;
94 int count = 0;
95 ssize_t len;
96
97 /*
98 * Has "pcap_breakloop()" been called?
99 */
100 if (handle->break_loop) {
101 /*
102 * Yes - clear the flag that indicates that it
103 * has, and return PCAP_ERROR_BREAK to indicate
104 * that we were told to break out of the loop.
105 */
106 handle->break_loop = 0;
107 return PCAP_ERROR_BREAK;
108 }
109 len = handle->cc;
110 if (len == 0) {
111 /*
112 * The buffer is empty; refill it.
113 *
114 * We ignore EINTR, as that might just be due to a signal
115 * being delivered - if the signal should interrupt the
116 * loop, the signal handler should call pcap_breakloop()
117 * to set handle->break_loop (we ignore it on other
118 * platforms as well).
119 */
120 do {
121 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
122 if (handle->break_loop) {
123 handle->break_loop = 0;
124 return PCAP_ERROR_BREAK;
125 }
126 if (errno == ENOBUFS)
127 handlep->packets_nobufs++;
128 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS));
129
130 if (len < 0) {
131 pcap_fmt_errmsg_for_errno(handle->errbuf,
132 PCAP_ERRBUF_SIZE, errno, "Can't receive packet");
133 return PCAP_ERROR;
134 }
135
136 bp = (unsigned char *)handle->buffer;
137 } else
138 bp = handle->bp;
139
140 /*
141 * Loop through each message.
142 *
143 * This assumes that a single buffer of message will have
144 * <= INT_MAX packets, so the message count doesn't overflow.
145 */
146 ep = bp + len;
147 while (bp < ep) {
148 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp;
149 uint32_t msg_len;
150 nftype_t type = OTHER;
151 /*
152 * Has "pcap_breakloop()" been called?
153 * If so, return immediately - if we haven't read any
154 * packets, clear the flag and return PCAP_ERROR_BREAK
155 * to indicate that we were told to break out of the loop,
156 * otherwise leave the flag set, so that the *next* call
157 * will break out of the loop without having read any
158 * packets, and return the number of packets we've
159 * processed so far.
160 */
161 if (handle->break_loop) {
162 handle->bp = bp;
163 handle->cc = (int)(ep - bp);
164 if (count == 0) {
165 handle->break_loop = 0;
166 return PCAP_ERROR_BREAK;
167 } else
168 return count;
169 }
170 /*
171 * NLMSG_SPACE(0) might be signed or might be unsigned,
172 * depending on whether the kernel defines NLMSG_ALIGNTO
173 * as 4, which older kernels do, or as 4U, which newer
174 * kernels do.
175 *
176 * ep - bp is of type ptrdiff_t, which is signed.
177 *
178 * To squelch warnings, we cast both to size_t, which
179 * is unsigned; ep >= bp, so the cast is safe.
180 */
181 if ((size_t)(ep - bp) < (size_t)NLMSG_SPACE(0)) {
182 /*
183 * There's less than one netlink message left
184 * in the buffer. Give up.
185 */
186 break;
187 }
188
189 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) {
190 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len);
191 return -1;
192 }
193
194 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
195 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
196 type = NFLOG;
197 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
198 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
199 type = NFQUEUE;
200
201 if (type != OTHER) {
202 const unsigned char *payload = NULL;
203 struct pcap_pkthdr pkth;
204
205 const struct nfgenmsg *nfg = NULL;
206 int id = 0;
207
208 if (handle->linktype != DLT_NFLOG) {
209 const struct nfattr *payload_attr = NULL;
210
211 if (nlh->nlmsg_len < HDR_LENGTH) {
212 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
213 return -1;
214 }
215
216 nfg = NLMSG_DATA(nlh);
217 if (nlh->nlmsg_len > HDR_LENGTH) {
218 struct nfattr *attr = NFM_NFA(nfg);
219 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
220
221 while (NFA_OK(attr, attr_len)) {
222 if (type == NFQUEUE) {
223 switch (NFA_TYPE(attr)) {
224 case NFQA_PACKET_HDR:
225 {
226 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
227
228 id = ntohl(pkt_hdr->packet_id);
229 break;
230 }
231 case NFQA_PAYLOAD:
232 payload_attr = attr;
233 break;
234 }
235
236 } else if (type == NFLOG) {
237 switch (NFA_TYPE(attr)) {
238 case NFULA_PAYLOAD:
239 payload_attr = attr;
240 break;
241 }
242 }
243 attr = NFA_NEXT(attr, attr_len);
244 }
245 }
246
247 if (payload_attr) {
248 payload = NFA_DATA(payload_attr);
249 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
250 }
251
252 } else {
253 payload = NLMSG_DATA(nlh);
254 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
255 }
256
257 if (payload) {
258 /* pkth.caplen = min (payload_len, handle->snapshot); */
259
260 gettimeofday(&pkth.ts, NULL);
261 if (handle->fcode.bf_insns == NULL ||
262 pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
263 {
264 handlep->packets_read++;
265 callback(user, &pkth, payload);
266 count++;
267 }
268 }
269
270 if (type == NFQUEUE) {
271 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
272 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
273 so nfg is always initialized to NLMSG_DATA(nlh). */
274 if (nfg != NULL)
275 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
276 }
277 }
278
279 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
280 /*
281 * If the message length would run past the end of the
282 * buffer, truncate it to the remaining space in the
283 * buffer.
284 *
285 * To squelch warnings, we cast ep - bp to uint32_t, which
286 * is unsigned and is the type of msg_len; ep >= bp, and
287 * len should fit in 32 bits (either it's set from an int
288 * or it's set from a recv() call with a buffer size that's
289 * an int, and we're assuming either ILP32 or LP64), so
290 * the cast is safe.
291 */
292 if (msg_len > (uint32_t)(ep - bp))
293 msg_len = (uint32_t)(ep - bp);
294
295 bp += msg_len;
296 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
297 handle->bp = bp;
298 handle->cc = (int)(ep - bp);
299 if (handle->cc < 0)
300 handle->cc = 0;
301 return count;
302 }
303 }
304
305 handle->cc = 0;
306 return count;
307 }
308
309 static int
netfilter_set_datalink(pcap_t * handle,int dlt)310 netfilter_set_datalink(pcap_t *handle, int dlt)
311 {
312 handle->linktype = dlt;
313 return 0;
314 }
315
316 static int
netfilter_stats_linux(pcap_t * handle,struct pcap_stat * stats)317 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
318 {
319 struct pcap_netfilter *handlep = handle->priv;
320
321 stats->ps_recv = handlep->packets_read;
322 stats->ps_drop = handlep->packets_nobufs;
323 stats->ps_ifdrop = 0;
324 return 0;
325 }
326
327 static int
netfilter_inject_linux(pcap_t * handle,const void * buf _U_,int size _U_)328 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_)
329 {
330 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
331 "Packet injection is not supported on netfilter devices");
332 return (-1);
333 }
334
335 struct my_nfattr {
336 uint16_t nfa_len;
337 uint16_t nfa_type;
338 void *data;
339 };
340
341 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)342 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)
343 {
344 char buf[1024] __attribute__ ((aligned));
345 memset(buf, 0, sizeof(buf));
346
347 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
348 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
349
350 struct sockaddr_nl snl;
351 static unsigned int seq_id;
352
353 if (!seq_id)
354 DIAG_OFF_NARROWING
355 seq_id = time(NULL);
356 DIAG_ON_NARROWING
357 ++seq_id;
358
359 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
360 nlh->nlmsg_type = msg_type;
361 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
362 nlh->nlmsg_pid = 0; /* to kernel */
363 nlh->nlmsg_seq = seq_id;
364
365 nfg->nfgen_family = family;
366 nfg->version = NFNETLINK_V0;
367 nfg->res_id = htons(res_id);
368
369 if (mynfa) {
370 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
371
372 nfa->nfa_type = mynfa->nfa_type;
373 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
374 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
375 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
376 }
377
378 memset(&snl, 0, sizeof(snl));
379 snl.nl_family = AF_NETLINK;
380
381 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
382 return -1;
383
384 if (!ack)
385 return 0;
386
387 /* waiting for reply loop */
388 do {
389 socklen_t addrlen = sizeof(snl);
390 int len;
391
392 /* ignore interrupt system call error */
393 do {
394 /*
395 * The buffer is not so big that its size won't
396 * fit into an int.
397 */
398 len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
399 } while ((len == -1) && (errno == EINTR));
400
401 if (len <= 0)
402 return len;
403
404 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
405 errno = EINVAL;
406 return -1;
407 }
408
409 nlh = (struct nlmsghdr *) buf;
410 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
411 continue;
412
413 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
414 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
415 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
416 errno = EBADMSG;
417 return -1;
418 }
419 errno = -(*((int *)NLMSG_DATA(nlh)));
420 return (errno == 0) ? 0 : -1;
421 }
422 nlh = NLMSG_NEXT(nlh, len);
423 }
424 } while (1);
425
426 return -1; /* never here */
427 }
428
429 static int
nflog_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)430 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
431 {
432 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
433 }
434
435 static int
nflog_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int8_t family)436 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
437 {
438 struct nfulnl_msg_config_cmd msg;
439 struct my_nfattr nfa;
440
441 msg.command = cmd;
442
443 nfa.data = &msg;
444 nfa.nfa_type = NFULA_CFG_CMD;
445 nfa.nfa_len = sizeof(msg);
446
447 return nflog_send_config_msg(handle, family, group_id, &nfa);
448 }
449
450 static int
nflog_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)451 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
452 {
453 struct nfulnl_msg_config_mode msg;
454 struct my_nfattr nfa;
455
456 msg.copy_range = htonl(copy_range);
457 msg.copy_mode = copy_mode;
458
459 nfa.data = &msg;
460 nfa.nfa_type = NFULA_CFG_MODE;
461 nfa.nfa_len = sizeof(msg);
462
463 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
464 }
465
466 static int
nfqueue_send_verdict(const pcap_t * handle,uint16_t group_id,u_int32_t id,u_int32_t verdict)467 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
468 {
469 struct nfqnl_msg_verdict_hdr msg;
470 struct my_nfattr nfa;
471
472 msg.id = htonl(id);
473 msg.verdict = htonl(verdict);
474
475 nfa.data = &msg;
476 nfa.nfa_type = NFQA_VERDICT_HDR;
477 nfa.nfa_len = sizeof(msg);
478
479 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
480 }
481
482 static int
nfqueue_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)483 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
484 {
485 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
486 }
487
488 static int
nfqueue_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int16_t pf)489 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
490 {
491 struct nfqnl_msg_config_cmd msg;
492 struct my_nfattr nfa;
493
494 msg.command = cmd;
495 msg.pf = htons(pf);
496
497 nfa.data = &msg;
498 nfa.nfa_type = NFQA_CFG_CMD;
499 nfa.nfa_len = sizeof(msg);
500
501 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
502 }
503
504 static int
nfqueue_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)505 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
506 {
507 struct nfqnl_msg_config_params msg;
508 struct my_nfattr nfa;
509
510 msg.copy_range = htonl(copy_range);
511 msg.copy_mode = copy_mode;
512
513 nfa.data = &msg;
514 nfa.nfa_type = NFQA_CFG_PARAMS;
515 nfa.nfa_len = sizeof(msg);
516
517 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
518 }
519
520 static int
netfilter_activate(pcap_t * handle)521 netfilter_activate(pcap_t* handle)
522 {
523 const char *dev = handle->opt.device;
524 unsigned short groups[32];
525 int group_count = 0;
526 nftype_t type = OTHER;
527 int i;
528
529 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
530 dev += strlen(NFLOG_IFACE);
531 type = NFLOG;
532
533 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
534 dev += strlen(NFQUEUE_IFACE);
535 type = NFQUEUE;
536 }
537
538 if (type != OTHER && *dev == ':') {
539 dev++;
540 while (*dev) {
541 long int group_id;
542 char *end_dev;
543
544 if (group_count == 32) {
545 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
546 "Maximum 32 netfilter groups! dev: %s",
547 handle->opt.device);
548 return PCAP_ERROR;
549 }
550
551 group_id = strtol(dev, &end_dev, 0);
552 if (end_dev != dev) {
553 if (group_id < 0 || group_id > 65535) {
554 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
555 "Netfilter group range from 0 to 65535 (got %ld)",
556 group_id);
557 return PCAP_ERROR;
558 }
559
560 groups[group_count++] = (unsigned short) group_id;
561 dev = end_dev;
562 }
563 if (*dev != ',')
564 break;
565 dev++;
566 }
567 }
568
569 if (type == OTHER || *dev) {
570 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
571 "Can't get netfilter group(s) index from %s",
572 handle->opt.device);
573 return PCAP_ERROR;
574 }
575
576 /* if no groups, add default: 0 */
577 if (!group_count) {
578 groups[0] = 0;
579 group_count = 1;
580 }
581
582 /*
583 * Turn a negative snapshot value (invalid), a snapshot value of
584 * 0 (unspecified), or a value bigger than the normal maximum
585 * value, into the maximum allowed value.
586 *
587 * If some application really *needs* a bigger snapshot
588 * length, we should just increase MAXIMUM_SNAPLEN.
589 */
590 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
591 handle->snapshot = MAXIMUM_SNAPLEN;
592
593 /* Initialize some components of the pcap structure. */
594 handle->bufsize = 128 + handle->snapshot;
595 handle->offset = 0;
596 handle->read_op = netfilter_read_linux;
597 handle->inject_op = netfilter_inject_linux;
598 handle->setfilter_op = install_bpf_program; /* no kernel filtering */
599 handle->setdirection_op = NULL;
600 handle->set_datalink_op = netfilter_set_datalink;
601 handle->getnonblock_op = pcap_getnonblock_fd;
602 handle->setnonblock_op = pcap_setnonblock_fd;
603 handle->stats_op = netfilter_stats_linux;
604
605 /* Create netlink socket */
606 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
607 if (handle->fd < 0) {
608 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
609 errno, "Can't create raw socket");
610 return PCAP_ERROR;
611 }
612
613 if (type == NFLOG) {
614 handle->linktype = DLT_NFLOG;
615 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
616 if (handle->dlt_list != NULL) {
617 handle->dlt_list[0] = DLT_NFLOG;
618 handle->dlt_list[1] = DLT_IPV4;
619 handle->dlt_count = 2;
620 }
621
622 } else
623 handle->linktype = DLT_IPV4;
624
625 handle->buffer = malloc(handle->bufsize);
626 if (!handle->buffer) {
627 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
628 errno, "Can't allocate dump buffer");
629 goto close_fail;
630 }
631
632 if (type == NFLOG) {
633 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
634 pcap_fmt_errmsg_for_errno(handle->errbuf,
635 PCAP_ERRBUF_SIZE, errno,
636 "NFULNL_CFG_CMD_PF_UNBIND");
637 goto close_fail;
638 }
639
640 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
641 pcap_fmt_errmsg_for_errno(handle->errbuf,
642 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
643 goto close_fail;
644 }
645
646 /* Bind socket to the nflog groups */
647 for (i = 0; i < group_count; i++) {
648 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
649 pcap_fmt_errmsg_for_errno(handle->errbuf,
650 PCAP_ERRBUF_SIZE, errno,
651 "Can't listen on group index");
652 goto close_fail;
653 }
654
655 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
656 pcap_fmt_errmsg_for_errno(handle->errbuf,
657 PCAP_ERRBUF_SIZE, errno,
658 "NFULNL_COPY_PACKET");
659 goto close_fail;
660 }
661 }
662
663 } else {
664 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
665 pcap_fmt_errmsg_for_errno(handle->errbuf,
666 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
667 goto close_fail;
668 }
669
670 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
671 pcap_fmt_errmsg_for_errno(handle->errbuf,
672 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
673 goto close_fail;
674 }
675
676 /* Bind socket to the nfqueue groups */
677 for (i = 0; i < group_count; i++) {
678 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
679 pcap_fmt_errmsg_for_errno(handle->errbuf,
680 PCAP_ERRBUF_SIZE, errno,
681 "Can't listen on group index");
682 goto close_fail;
683 }
684
685 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
686 pcap_fmt_errmsg_for_errno(handle->errbuf,
687 PCAP_ERRBUF_SIZE, errno,
688 "NFQNL_COPY_PACKET");
689 goto close_fail;
690 }
691 }
692 }
693
694 if (handle->opt.rfmon) {
695 /*
696 * Monitor mode doesn't apply to netfilter devices.
697 */
698 pcap_cleanup_live_common(handle);
699 return PCAP_ERROR_RFMON_NOTSUP;
700 }
701
702 if (handle->opt.buffer_size != 0) {
703 /*
704 * Set the socket buffer size to the specified value.
705 */
706 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
707 pcap_fmt_errmsg_for_errno(handle->errbuf,
708 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
709 goto close_fail;
710 }
711 }
712
713 handle->selectable_fd = handle->fd;
714 return 0;
715
716 close_fail:
717 pcap_cleanup_live_common(handle);
718 return PCAP_ERROR;
719 }
720
721 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)722 netfilter_create(const char *device, char *ebuf, int *is_ours)
723 {
724 const char *cp;
725 pcap_t *p;
726
727 /* Does this look like an netfilter device? */
728 cp = strrchr(device, '/');
729 if (cp == NULL)
730 cp = device;
731
732 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
733 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
734 cp += sizeof NFLOG_IFACE - 1;
735 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
736 cp += sizeof NFQUEUE_IFACE - 1;
737 else {
738 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
739 *is_ours = 0;
740 return NULL;
741 }
742
743 /*
744 * Yes - is that either the end of the name, or is it followed
745 * by a colon?
746 */
747 if (*cp != ':' && *cp != '\0') {
748 /* Nope */
749 *is_ours = 0;
750 return NULL;
751 }
752
753 /* OK, it's probably ours. */
754 *is_ours = 1;
755
756 p = PCAP_CREATE_COMMON(ebuf, struct pcap_netfilter);
757 if (p == NULL)
758 return (NULL);
759
760 p->activate_op = netfilter_activate;
761 return (p);
762 }
763
764 int
netfilter_findalldevs(pcap_if_list_t * devlistp,char * err_str)765 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
766 {
767 int sock;
768
769 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
770 if (sock < 0) {
771 /* if netlink is not supported this is not fatal */
772 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
773 return 0;
774 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
775 errno, "Can't open netlink socket");
776 return -1;
777 }
778 close(sock);
779
780 /*
781 * The notion of "connected" vs. "disconnected" doesn't apply.
782 * XXX - what about "up" and "running"?
783 */
784 if (add_dev(devlistp, NFLOG_IFACE,
785 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
786 "Linux netfilter log (NFLOG) interface", err_str) == NULL)
787 return -1;
788 if (add_dev(devlistp, NFQUEUE_IFACE,
789 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
790 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
791 return -1;
792 return 0;
793 }
794