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