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