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 #include <config.h>
32
33 #include "pcap-int.h"
34 #include "diag-control.h"
35
36 #ifdef NEED_STRERROR_H
37 #include "strerror.h"
38 #endif
39
40 #include <errno.h>
41 #include <stdlib.h>
42 #include <unistd.h>
43 #include <string.h>
44 #include <sys/socket.h>
45 #include <arpa/inet.h>
46
47 #include <time.h>
48 #include <sys/time.h>
49 #include <netinet/in.h>
50 #include <linux/types.h>
51
52 #include <linux/netlink.h>
53 #include <linux/netfilter.h>
54 #include <linux/netfilter/nfnetlink.h>
55 #include <linux/netfilter/nfnetlink_log.h>
56 #include <linux/netfilter/nfnetlink_queue.h>
57
58 /* NOTE: if your program drops privileges after pcap_activate() it WON'T work with nfqueue.
59 * It took me quite some time to debug ;/
60 *
61 * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges,
62 * and in nfqueue we need to send verdict reply after receiving packet.
63 *
64 * In tcpdump you can disable dropping privileges with -Z root
65 */
66
67 #include "pcap-netfilter-linux.h"
68
69 #define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg))))
70
71 #define NFLOG_IFACE "nflog"
72 #define NFQUEUE_IFACE "nfqueue"
73
74 typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t;
75
76 /*
77 * Private data for capturing on Linux netfilter sockets.
78 */
79 struct pcap_netfilter {
80 u_int packets_read; /* count of packets read with recvfrom() */
81 u_int packets_nobufs; /* ENOBUFS counter */
82 };
83
84 static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict);
85
86
87 static int
netfilter_read_linux(pcap_t * handle,int max_packets,pcap_handler callback,u_char * user)88 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
89 {
90 struct pcap_netfilter *handlep = handle->priv;
91 register u_char *bp, *ep;
92 int count = 0;
93 ssize_t len;
94
95 /*
96 * Has "pcap_breakloop()" been called?
97 */
98 if (handle->break_loop) {
99 /*
100 * Yes - clear the flag that indicates that it
101 * has, and return PCAP_ERROR_BREAK to indicate
102 * that we were told to break out of the loop.
103 */
104 handle->break_loop = 0;
105 return PCAP_ERROR_BREAK;
106 }
107 len = handle->cc;
108 if (len == 0) {
109 /*
110 * The buffer is empty; refill it.
111 *
112 * We ignore EINTR, as that might just be due to a signal
113 * being delivered - if the signal should interrupt the
114 * loop, the signal handler should call pcap_breakloop()
115 * to set handle->break_loop (we ignore it on other
116 * platforms as well).
117 */
118 do {
119 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
120 if (handle->break_loop) {
121 handle->break_loop = 0;
122 return PCAP_ERROR_BREAK;
123 }
124 if (len == -1 && errno == ENOBUFS)
125 handlep->packets_nobufs++;
126 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS));
127
128 if (len < 0) {
129 pcapint_fmt_errmsg_for_errno(handle->errbuf,
130 PCAP_ERRBUF_SIZE, errno, "Can't receive packet");
131 return PCAP_ERROR;
132 }
133
134 bp = (unsigned char *)handle->buffer;
135 } else
136 bp = handle->bp;
137
138 /*
139 * Loop through each message.
140 *
141 * This assumes that a single buffer of message will have
142 * <= INT_MAX packets, so the message count doesn't overflow.
143 */
144 ep = bp + len;
145 while (bp < ep) {
146 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp;
147 uint32_t msg_len;
148 nftype_t type = OTHER;
149 /*
150 * Has "pcap_breakloop()" been called?
151 * If so, return immediately - if we haven't read any
152 * packets, clear the flag and return PCAP_ERROR_BREAK
153 * to indicate that we were told to break out of the loop,
154 * otherwise leave the flag set, so that the *next* call
155 * will break out of the loop without having read any
156 * packets, and return the number of packets we've
157 * processed so far.
158 */
159 if (handle->break_loop) {
160 handle->bp = bp;
161 handle->cc = (int)(ep - bp);
162 if (count == 0) {
163 handle->break_loop = 0;
164 return PCAP_ERROR_BREAK;
165 } else
166 return count;
167 }
168 /*
169 * NLMSG_SPACE(0) might be signed or might be unsigned,
170 * depending on whether the kernel defines NLMSG_ALIGNTO
171 * as 4, which older kernels do, or as 4U, which newer
172 * kernels do.
173 *
174 * ep - bp is of type ptrdiff_t, which is signed.
175 *
176 * To squelch warnings, we cast both to size_t, which
177 * is unsigned; ep >= bp, so the cast is safe.
178 */
179 if ((size_t)(ep - bp) < (size_t)NLMSG_SPACE(0)) {
180 /*
181 * There's less than one netlink message left
182 * in the buffer. Give up.
183 */
184 break;
185 }
186
187 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) {
188 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len);
189 return -1;
190 }
191
192 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
193 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
194 type = NFLOG;
195 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
196 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
197 type = NFQUEUE;
198
199 if (type != OTHER) {
200 const unsigned char *payload = NULL;
201 struct pcap_pkthdr pkth;
202
203 const struct nfgenmsg *nfg = NULL;
204 int id = 0;
205
206 if (handle->linktype != DLT_NFLOG) {
207 const struct nfattr *payload_attr = NULL;
208
209 if (nlh->nlmsg_len < HDR_LENGTH) {
210 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
211 return -1;
212 }
213
214 nfg = NLMSG_DATA(nlh);
215 if (nlh->nlmsg_len > HDR_LENGTH) {
216 struct nfattr *attr = NFM_NFA(nfg);
217 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
218
219 while (NFA_OK(attr, attr_len)) {
220 if (type == NFQUEUE) {
221 switch (NFA_TYPE(attr)) {
222 case NFQA_PACKET_HDR:
223 {
224 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
225
226 id = ntohl(pkt_hdr->packet_id);
227 break;
228 }
229 case NFQA_PAYLOAD:
230 payload_attr = attr;
231 break;
232 }
233
234 } else if (type == NFLOG) {
235 switch (NFA_TYPE(attr)) {
236 case NFULA_PAYLOAD:
237 payload_attr = attr;
238 break;
239 }
240 }
241 attr = NFA_NEXT(attr, attr_len);
242 }
243 }
244
245 if (payload_attr) {
246 payload = NFA_DATA(payload_attr);
247 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
248 }
249
250 } else {
251 payload = NLMSG_DATA(nlh);
252 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
253 }
254
255 if (payload) {
256 /* pkth.caplen = min (payload_len, handle->snapshot); */
257
258 gettimeofday(&pkth.ts, NULL);
259 if (handle->fcode.bf_insns == NULL ||
260 pcapint_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
261 {
262 handlep->packets_read++;
263 callback(user, &pkth, payload);
264 count++;
265 }
266 }
267
268 if (type == NFQUEUE) {
269 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
270 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
271 so nfg is always initialized to NLMSG_DATA(nlh). */
272 if (nfg != NULL)
273 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
274 }
275 }
276
277 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
278 /*
279 * If the message length would run past the end of the
280 * buffer, truncate it to the remaining space in the
281 * buffer.
282 *
283 * To squelch warnings, we cast ep - bp to uint32_t, which
284 * is unsigned and is the type of msg_len; ep >= bp, and
285 * len should fit in 32 bits (either it's set from an int
286 * or it's set from a recv() call with a buffer size that's
287 * an int, and we're assuming either ILP32 or LP64), so
288 * the cast is safe.
289 */
290 if (msg_len > (uint32_t)(ep - bp))
291 msg_len = (uint32_t)(ep - bp);
292
293 bp += msg_len;
294 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
295 handle->bp = bp;
296 handle->cc = (int)(ep - bp);
297 if (handle->cc < 0)
298 handle->cc = 0;
299 return count;
300 }
301 }
302
303 handle->cc = 0;
304 return count;
305 }
306
307 static int
netfilter_set_datalink(pcap_t * handle,int dlt)308 netfilter_set_datalink(pcap_t *handle, int dlt)
309 {
310 handle->linktype = dlt;
311 return 0;
312 }
313
314 static int
netfilter_stats_linux(pcap_t * handle,struct pcap_stat * stats)315 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
316 {
317 struct pcap_netfilter *handlep = handle->priv;
318
319 stats->ps_recv = handlep->packets_read;
320 stats->ps_drop = handlep->packets_nobufs;
321 stats->ps_ifdrop = 0;
322 return 0;
323 }
324
325 static int
netfilter_inject_linux(pcap_t * handle,const void * buf _U_,int size _U_)326 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_)
327 {
328 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
329 "Packet injection is not supported on netfilter devices");
330 return (-1);
331 }
332
333 struct my_nfattr {
334 uint16_t nfa_len;
335 uint16_t nfa_type;
336 void *data;
337 };
338
339 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)340 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)
341 {
342 char buf[1024] __attribute__ ((aligned));
343 memset(buf, 0, sizeof(buf));
344
345 struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
346 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
347
348 struct sockaddr_nl snl;
349 static unsigned int seq_id;
350
351 if (!seq_id)
352 DIAG_OFF_NARROWING
353 seq_id = time(NULL);
354 DIAG_ON_NARROWING
355 ++seq_id;
356
357 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
358 nlh->nlmsg_type = msg_type;
359 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
360 nlh->nlmsg_pid = 0; /* to kernel */
361 nlh->nlmsg_seq = seq_id;
362
363 nfg->nfgen_family = family;
364 nfg->version = NFNETLINK_V0;
365 nfg->res_id = htons(res_id);
366
367 if (mynfa) {
368 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
369
370 nfa->nfa_type = mynfa->nfa_type;
371 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
372 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
373 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
374 }
375
376 memset(&snl, 0, sizeof(snl));
377 snl.nl_family = AF_NETLINK;
378
379 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
380 return -1;
381
382 if (!ack)
383 return 0;
384
385 /* waiting for reply loop */
386 do {
387 socklen_t addrlen = sizeof(snl);
388 int len;
389
390 /* ignore interrupt system call error */
391 do {
392 /*
393 * The buffer is not so big that its size won't
394 * fit into an int.
395 */
396 len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
397 } while ((len == -1) && (errno == EINTR));
398
399 if (len <= 0)
400 return len;
401
402 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
403 errno = EINVAL;
404 return -1;
405 }
406
407 nlh = (struct nlmsghdr *) buf;
408 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */
409 continue;
410
411 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
412 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
413 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
414 errno = EBADMSG;
415 return -1;
416 }
417 errno = -(*((int *)NLMSG_DATA(nlh)));
418 return (errno == 0) ? 0 : -1;
419 }
420 nlh = NLMSG_NEXT(nlh, len);
421 }
422 } while (1);
423
424 return -1; /* never here */
425 }
426
427 static int
nflog_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)428 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
429 {
430 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
431 }
432
433 static int
nflog_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int8_t family)434 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
435 {
436 struct nfulnl_msg_config_cmd msg;
437 struct my_nfattr nfa;
438
439 msg.command = cmd;
440
441 nfa.data = &msg;
442 nfa.nfa_type = NFULA_CFG_CMD;
443 nfa.nfa_len = sizeof(msg);
444
445 return nflog_send_config_msg(handle, family, group_id, &nfa);
446 }
447
448 static int
nflog_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)449 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
450 {
451 struct nfulnl_msg_config_mode msg;
452 struct my_nfattr nfa;
453
454 msg.copy_range = htonl(copy_range);
455 msg.copy_mode = copy_mode;
456
457 nfa.data = &msg;
458 nfa.nfa_type = NFULA_CFG_MODE;
459 nfa.nfa_len = sizeof(msg);
460
461 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
462 }
463
464 static int
nfqueue_send_verdict(const pcap_t * handle,uint16_t group_id,u_int32_t id,u_int32_t verdict)465 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
466 {
467 struct nfqnl_msg_verdict_hdr msg;
468 struct my_nfattr nfa;
469
470 msg.id = htonl(id);
471 msg.verdict = htonl(verdict);
472
473 nfa.data = &msg;
474 nfa.nfa_type = NFQA_VERDICT_HDR;
475 nfa.nfa_len = sizeof(msg);
476
477 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
478 }
479
480 static int
nfqueue_send_config_msg(const pcap_t * handle,uint8_t family,u_int16_t group_id,const struct my_nfattr * mynfa)481 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
482 {
483 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
484 }
485
486 static int
nfqueue_send_config_cmd(const pcap_t * handle,uint16_t group_id,u_int8_t cmd,u_int16_t pf)487 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
488 {
489 struct nfqnl_msg_config_cmd msg;
490 struct my_nfattr nfa;
491
492 msg.command = cmd;
493 msg.pf = htons(pf);
494
495 nfa.data = &msg;
496 nfa.nfa_type = NFQA_CFG_CMD;
497 nfa.nfa_len = sizeof(msg);
498
499 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
500 }
501
502 static int
nfqueue_send_config_mode(const pcap_t * handle,uint16_t group_id,u_int8_t copy_mode,u_int32_t copy_range)503 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
504 {
505 struct nfqnl_msg_config_params msg;
506 struct my_nfattr nfa;
507
508 msg.copy_range = htonl(copy_range);
509 msg.copy_mode = copy_mode;
510
511 nfa.data = &msg;
512 nfa.nfa_type = NFQA_CFG_PARAMS;
513 nfa.nfa_len = sizeof(msg);
514
515 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
516 }
517
518 static int
netfilter_activate(pcap_t * handle)519 netfilter_activate(pcap_t* handle)
520 {
521 const char *dev = handle->opt.device;
522 unsigned short groups[32];
523 int group_count = 0;
524 nftype_t type = OTHER;
525 int i;
526
527 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
528 dev += strlen(NFLOG_IFACE);
529 type = NFLOG;
530
531 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
532 dev += strlen(NFQUEUE_IFACE);
533 type = NFQUEUE;
534 }
535
536 if (type != OTHER && *dev == ':') {
537 dev++;
538 while (*dev) {
539 long int group_id;
540 char *end_dev;
541
542 if (group_count == 32) {
543 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
544 "Maximum 32 netfilter groups! dev: %s",
545 handle->opt.device);
546 return PCAP_ERROR;
547 }
548
549 group_id = strtol(dev, &end_dev, 0);
550 if (end_dev != dev) {
551 if (group_id < 0 || group_id > 65535) {
552 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
553 "Netfilter group range from 0 to 65535 (got %ld)",
554 group_id);
555 return PCAP_ERROR;
556 }
557
558 groups[group_count++] = (unsigned short) group_id;
559 dev = end_dev;
560 }
561 if (*dev != ',')
562 break;
563 dev++;
564 }
565 }
566
567 if (type == OTHER || *dev) {
568 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
569 "Can't get netfilter group(s) index from %s",
570 handle->opt.device);
571 return PCAP_ERROR;
572 }
573
574 /* if no groups, add default: 0 */
575 if (!group_count) {
576 groups[0] = 0;
577 group_count = 1;
578 }
579
580 /*
581 * Turn a negative snapshot value (invalid), a snapshot value of
582 * 0 (unspecified), or a value bigger than the normal maximum
583 * value, into the maximum allowed value.
584 *
585 * If some application really *needs* a bigger snapshot
586 * length, we should just increase MAXIMUM_SNAPLEN.
587 */
588 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
589 handle->snapshot = MAXIMUM_SNAPLEN;
590
591 /* Initialize some components of the pcap structure. */
592 handle->bufsize = 128 + handle->snapshot;
593 handle->offset = 0;
594 handle->read_op = netfilter_read_linux;
595 handle->inject_op = netfilter_inject_linux;
596 handle->setfilter_op = pcapint_install_bpf_program; /* no kernel filtering */
597 handle->setdirection_op = NULL;
598 handle->set_datalink_op = netfilter_set_datalink;
599 handle->getnonblock_op = pcapint_getnonblock_fd;
600 handle->setnonblock_op = pcapint_setnonblock_fd;
601 handle->stats_op = netfilter_stats_linux;
602
603 /* Create netlink socket */
604 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
605 if (handle->fd < 0) {
606 pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
607 errno, "Can't create raw socket");
608 return PCAP_ERROR;
609 }
610
611 if (type == NFLOG) {
612 handle->linktype = DLT_NFLOG;
613 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
614 if (handle->dlt_list == NULL) {
615 pcapint_fmt_errmsg_for_errno(handle->errbuf,
616 PCAP_ERRBUF_SIZE, errno,
617 "Can't allocate DLT list");
618 goto close_fail;
619 }
620 handle->dlt_list[0] = DLT_NFLOG;
621 handle->dlt_list[1] = DLT_IPV4;
622 handle->dlt_count = 2;
623 } else
624 handle->linktype = DLT_IPV4;
625
626 handle->buffer = malloc(handle->bufsize);
627 if (!handle->buffer) {
628 pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
629 errno, "Can't allocate dump buffer");
630 goto close_fail;
631 }
632
633 if (type == NFLOG) {
634 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
635 pcapint_fmt_errmsg_for_errno(handle->errbuf,
636 PCAP_ERRBUF_SIZE, errno,
637 "NFULNL_CFG_CMD_PF_UNBIND");
638 goto close_fail;
639 }
640
641 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
642 pcapint_fmt_errmsg_for_errno(handle->errbuf,
643 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
644 goto close_fail;
645 }
646
647 /* Bind socket to the nflog groups */
648 for (i = 0; i < group_count; i++) {
649 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
650 pcapint_fmt_errmsg_for_errno(handle->errbuf,
651 PCAP_ERRBUF_SIZE, errno,
652 "Can't listen on group index");
653 goto close_fail;
654 }
655
656 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
657 pcapint_fmt_errmsg_for_errno(handle->errbuf,
658 PCAP_ERRBUF_SIZE, errno,
659 "NFULNL_COPY_PACKET");
660 goto close_fail;
661 }
662 }
663
664 } else {
665 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
666 pcapint_fmt_errmsg_for_errno(handle->errbuf,
667 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
668 goto close_fail;
669 }
670
671 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
672 pcapint_fmt_errmsg_for_errno(handle->errbuf,
673 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
674 goto close_fail;
675 }
676
677 /* Bind socket to the nfqueue groups */
678 for (i = 0; i < group_count; i++) {
679 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
680 pcapint_fmt_errmsg_for_errno(handle->errbuf,
681 PCAP_ERRBUF_SIZE, errno,
682 "Can't listen on group index");
683 goto close_fail;
684 }
685
686 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
687 pcapint_fmt_errmsg_for_errno(handle->errbuf,
688 PCAP_ERRBUF_SIZE, errno,
689 "NFQNL_COPY_PACKET");
690 goto close_fail;
691 }
692 }
693 }
694
695 if (handle->opt.rfmon) {
696 /*
697 * Monitor mode doesn't apply to netfilter devices.
698 */
699 pcapint_cleanup_live_common(handle);
700 return PCAP_ERROR_RFMON_NOTSUP;
701 }
702
703 if (handle->opt.buffer_size != 0) {
704 /*
705 * Set the socket buffer size to the specified value.
706 */
707 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
708 pcapint_fmt_errmsg_for_errno(handle->errbuf,
709 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
710 goto close_fail;
711 }
712 }
713
714 handle->selectable_fd = handle->fd;
715 return 0;
716
717 close_fail:
718 pcapint_cleanup_live_common(handle);
719 return PCAP_ERROR;
720 }
721
722 pcap_t *
netfilter_create(const char * device,char * ebuf,int * is_ours)723 netfilter_create(const char *device, char *ebuf, int *is_ours)
724 {
725 const char *cp;
726 pcap_t *p;
727
728 /* Does this look like an netfilter device? */
729 cp = strrchr(device, '/');
730 if (cp == NULL)
731 cp = device;
732
733 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
734 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
735 cp += sizeof NFLOG_IFACE - 1;
736 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
737 cp += sizeof NFQUEUE_IFACE - 1;
738 else {
739 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
740 *is_ours = 0;
741 return NULL;
742 }
743
744 /*
745 * Yes - is that either the end of the name, or is it followed
746 * by a colon?
747 */
748 if (*cp != ':' && *cp != '\0') {
749 /* Nope */
750 *is_ours = 0;
751 return NULL;
752 }
753
754 /* OK, it's probably ours. */
755 *is_ours = 1;
756
757 p = PCAP_CREATE_COMMON(ebuf, struct pcap_netfilter);
758 if (p == NULL)
759 return (NULL);
760
761 p->activate_op = netfilter_activate;
762 return (p);
763 }
764
765 int
netfilter_findalldevs(pcap_if_list_t * devlistp,char * err_str)766 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
767 {
768 int sock;
769
770 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
771 if (sock < 0) {
772 /* if netlink is not supported this is not fatal */
773 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
774 return 0;
775 pcapint_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
776 errno, "Can't open netlink socket");
777 return -1;
778 }
779 close(sock);
780
781 /*
782 * The notion of "connected" vs. "disconnected" doesn't apply.
783 * XXX - what about "up" and "running"?
784 */
785 if (pcapint_add_dev(devlistp, NFLOG_IFACE,
786 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
787 "Linux netfilter log (NFLOG) interface", err_str) == NULL)
788 return -1;
789 if (pcapint_add_dev(devlistp, NFQUEUE_IFACE,
790 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
791 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
792 return -1;
793 return 0;
794 }
795