1 /* $NetBSD: pcap-netfilter-linux.c,v 1.3 2015/03/31 21:39:42 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2011 Jakub Zawadzki 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote 17 * products derived from this software without specific prior written 18 * permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <sys/cdefs.h> 34 __RCSID("$NetBSD: pcap-netfilter-linux.c,v 1.3 2015/03/31 21:39:42 christos Exp $"); 35 36 #ifdef HAVE_CONFIG_H 37 #include "config.h" 38 #endif 39 40 #include "pcap-int.h" 41 42 #ifdef NEED_STRERROR_H 43 #include "strerror.h" 44 #endif 45 46 #include <errno.h> 47 #include <stdlib.h> 48 #include <unistd.h> 49 #include <string.h> 50 #include <sys/socket.h> 51 #include <arpa/inet.h> 52 53 #include <time.h> 54 #include <sys/time.h> 55 #include <netinet/in.h> 56 #include <linux/types.h> 57 58 #include <linux/netlink.h> 59 #include <linux/netfilter.h> 60 #include <linux/netfilter/nfnetlink.h> 61 #include <linux/netfilter/nfnetlink_log.h> 62 #include <linux/netfilter/nfnetlink_queue.h> 63 64 /* NOTE: if your program drops privilages after pcap_activate() it WON'T work with nfqueue. 65 * It took me quite some time to debug ;/ 66 * 67 * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privilages, 68 * and in nfqueue we need to send verdict reply after recving packet. 69 * 70 * In tcpdump you can disable dropping privilages with -Z root 71 */ 72 73 #include "pcap-netfilter-linux.h" 74 75 #define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) 76 77 #define NFLOG_IFACE "nflog" 78 #define NFQUEUE_IFACE "nfqueue" 79 80 typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t; 81 82 /* 83 * Private data for capturing on Linux netfilter sockets. 84 */ 85 struct pcap_netfilter { 86 u_int packets_read; /* count of packets read with recvfrom() */ 87 }; 88 89 static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict); 90 91 static int 92 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) 93 { 94 struct pcap_netfilter *handlep = handle->priv; 95 const unsigned char *buf; 96 int count = 0; 97 int len; 98 99 /* ignore interrupt system call error */ 100 do { 101 len = recv(handle->fd, handle->buffer, handle->bufsize, 0); 102 if (handle->break_loop) { 103 handle->break_loop = 0; 104 return -2; 105 } 106 } while ((len == -1) && (errno == EINTR)); 107 108 if (len < 0) { 109 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno)); 110 return -1; 111 } 112 113 buf = handle->buffer; 114 while (len >= NLMSG_SPACE(0)) { 115 const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf; 116 u_int32_t msg_len; 117 nftype_t type = OTHER; 118 119 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) { 120 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); 121 return -1; 122 } 123 124 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && 125 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) 126 type = NFLOG; 127 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE && 128 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET) 129 type = NFQUEUE; 130 131 if (type != OTHER) { 132 const unsigned char *payload = NULL; 133 struct pcap_pkthdr pkth; 134 135 const struct nfgenmsg *nfg = NULL; 136 int id = 0; 137 138 if (handle->linktype != DLT_NFLOG) { 139 const struct nfattr *payload_attr = NULL; 140 141 if (nlh->nlmsg_len < HDR_LENGTH) { 142 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); 143 return -1; 144 } 145 146 nfg = NLMSG_DATA(nlh); 147 if (nlh->nlmsg_len > HDR_LENGTH) { 148 struct nfattr *attr = NFM_NFA(nfg); 149 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); 150 151 while (NFA_OK(attr, attr_len)) { 152 if (type == NFQUEUE) { 153 switch (NFA_TYPE(attr)) { 154 case NFQA_PACKET_HDR: 155 { 156 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr); 157 158 id = ntohl(pkt_hdr->packet_id); 159 break; 160 } 161 case NFQA_PAYLOAD: 162 payload_attr = attr; 163 break; 164 } 165 166 } else if (type == NFLOG) { 167 switch (NFA_TYPE(attr)) { 168 case NFULA_PAYLOAD: 169 payload_attr = attr; 170 break; 171 } 172 } 173 attr = NFA_NEXT(attr, attr_len); 174 } 175 } 176 177 if (payload_attr) { 178 payload = NFA_DATA(payload_attr); 179 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr); 180 } 181 182 } else { 183 payload = NLMSG_DATA(nlh); 184 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr)); 185 } 186 187 if (payload) { 188 /* pkth.caplen = min (payload_len, handle->snapshot); */ 189 190 gettimeofday(&pkth.ts, NULL); 191 if (handle->fcode.bf_insns == NULL || 192 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) 193 { 194 handlep->packets_read++; 195 callback(user, &pkth, payload); 196 count++; 197 } 198 } 199 200 if (type == NFQUEUE) { 201 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */ 202 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG, 203 so nfg is always initialized to NLMSG_DATA(nlh). */ 204 if (nfg != NULL) 205 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT); 206 } 207 } 208 209 msg_len = NLMSG_ALIGN(nlh->nlmsg_len); 210 if (msg_len > len) 211 msg_len = len; 212 213 len -= msg_len; 214 buf += msg_len; 215 } 216 return count; 217 } 218 219 static int 220 netfilter_set_datalink(pcap_t *handle, int dlt) 221 { 222 handle->linktype = dlt; 223 return 0; 224 } 225 226 static int 227 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) 228 { 229 struct pcap_netfilter *handlep = handle->priv; 230 231 stats->ps_recv = handlep->packets_read; 232 stats->ps_drop = 0; 233 stats->ps_ifdrop = 0; 234 return 0; 235 } 236 237 static int 238 netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size) 239 { 240 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices"); 241 return (-1); 242 } 243 244 struct my_nfattr { 245 u_int16_t nfa_len; 246 u_int16_t nfa_type; 247 void *data; 248 }; 249 250 static int 251 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) 252 { 253 char buf[1024] __attribute__ ((aligned)); 254 255 struct nlmsghdr *nlh = (struct nlmsghdr *) buf; 256 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); 257 258 struct sockaddr_nl snl; 259 static unsigned int seq_id; 260 261 if (!seq_id) 262 seq_id = time(NULL); 263 ++seq_id; 264 265 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); 266 nlh->nlmsg_type = msg_type; 267 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0); 268 nlh->nlmsg_pid = 0; /* to kernel */ 269 nlh->nlmsg_seq = seq_id; 270 271 nfg->nfgen_family = family; 272 nfg->version = NFNETLINK_V0; 273 nfg->res_id = htons(res_id); 274 275 if (mynfa) { 276 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); 277 278 nfa->nfa_type = mynfa->nfa_type; 279 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); 280 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); 281 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); 282 } 283 284 memset(&snl, 0, sizeof(snl)); 285 snl.nl_family = AF_NETLINK; 286 287 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) 288 return -1; 289 290 if (!ack) 291 return 0; 292 293 /* waiting for reply loop */ 294 do { 295 socklen_t addrlen = sizeof(snl); 296 int len; 297 298 /* ignore interrupt system call error */ 299 do { 300 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); 301 } while ((len == -1) && (errno == EINTR)); 302 303 if (len <= 0) 304 return len; 305 306 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { 307 errno = EINVAL; 308 return -1; 309 } 310 311 nlh = (struct nlmsghdr *) buf; 312 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ 313 continue; 314 315 while (len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) { 316 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { 317 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { 318 errno = EBADMSG; 319 return -1; 320 } 321 errno = -(*((int *)NLMSG_DATA(nlh))); 322 return (errno == 0) ? 0 : -1; 323 } 324 nlh = NLMSG_NEXT(nlh, len); 325 } 326 } while (1); 327 328 return -1; /* never here */ 329 } 330 331 static int 332 nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 333 { 334 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); 335 } 336 337 static int 338 nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family) 339 { 340 struct nfulnl_msg_config_cmd msg; 341 struct my_nfattr nfa; 342 343 msg.command = cmd; 344 345 nfa.data = &msg; 346 nfa.nfa_type = NFULA_CFG_CMD; 347 nfa.nfa_len = sizeof(msg); 348 349 return nflog_send_config_msg(handle, family, group_id, &nfa); 350 } 351 352 static int 353 nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 354 { 355 struct nfulnl_msg_config_mode msg; 356 struct my_nfattr nfa; 357 358 msg.copy_range = htonl(copy_range); 359 msg.copy_mode = copy_mode; 360 361 nfa.data = &msg; 362 nfa.nfa_type = NFULA_CFG_MODE; 363 nfa.nfa_len = sizeof(msg); 364 365 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 366 } 367 368 static int 369 nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict) 370 { 371 struct nfqnl_msg_verdict_hdr msg; 372 struct my_nfattr nfa; 373 374 msg.id = htonl(id); 375 msg.verdict = htonl(verdict); 376 377 nfa.data = &msg; 378 nfa.nfa_type = NFQA_VERDICT_HDR; 379 nfa.nfa_len = sizeof(msg); 380 381 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa); 382 } 383 384 static int 385 nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 386 { 387 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); 388 } 389 390 static int 391 nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf) 392 { 393 struct nfqnl_msg_config_cmd msg; 394 struct my_nfattr nfa; 395 396 msg.command = cmd; 397 msg.pf = htons(pf); 398 399 nfa.data = &msg; 400 nfa.nfa_type = NFQA_CFG_CMD; 401 nfa.nfa_len = sizeof(msg); 402 403 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 404 } 405 406 static int 407 nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 408 { 409 struct nfqnl_msg_config_params msg; 410 struct my_nfattr nfa; 411 412 msg.copy_range = htonl(copy_range); 413 msg.copy_mode = copy_mode; 414 415 nfa.data = &msg; 416 nfa.nfa_type = NFQA_CFG_PARAMS; 417 nfa.nfa_len = sizeof(msg); 418 419 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 420 } 421 422 static int 423 netfilter_activate(pcap_t* handle) 424 { 425 const char *dev = handle->opt.source; 426 unsigned short groups[32]; 427 int group_count = 0; 428 nftype_t type = OTHER; 429 int i; 430 431 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { 432 dev += strlen(NFLOG_IFACE); 433 type = NFLOG; 434 435 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) { 436 dev += strlen(NFQUEUE_IFACE); 437 type = NFQUEUE; 438 } 439 440 if (type != OTHER && *dev == ':') { 441 dev++; 442 while (*dev) { 443 long int group_id; 444 char *end_dev; 445 446 if (group_count == 32) { 447 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 448 "Maximum 32 netfilter groups! dev: %s", 449 handle->opt.source); 450 return PCAP_ERROR; 451 } 452 453 group_id = strtol(dev, &end_dev, 0); 454 if (end_dev != dev) { 455 if (group_id < 0 || group_id > 65535) { 456 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 457 "Netfilter group range from 0 to 65535 (got %ld)", 458 group_id); 459 return PCAP_ERROR; 460 } 461 462 groups[group_count++] = (unsigned short) group_id; 463 dev = end_dev; 464 } 465 if (*dev != ',') 466 break; 467 dev++; 468 } 469 } 470 471 if (type == OTHER || *dev) { 472 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 473 "Can't get netfilter group(s) index from %s", 474 handle->opt.source); 475 return PCAP_ERROR; 476 } 477 478 /* if no groups, add default: 0 */ 479 if (!group_count) { 480 groups[0] = 0; 481 group_count = 1; 482 } 483 484 /* Initialize some components of the pcap structure. */ 485 handle->bufsize = 128 + handle->snapshot; 486 handle->offset = 0; 487 handle->read_op = netfilter_read_linux; 488 handle->inject_op = netfilter_inject_linux; 489 handle->setfilter_op = install_bpf_program; /* no kernel filtering */ 490 handle->setdirection_op = NULL; 491 handle->set_datalink_op = netfilter_set_datalink; 492 handle->getnonblock_op = pcap_getnonblock_fd; 493 handle->setnonblock_op = pcap_setnonblock_fd; 494 handle->stats_op = netfilter_stats_linux; 495 496 /* Create netlink socket */ 497 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 498 if (handle->fd < 0) { 499 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno)); 500 return PCAP_ERROR; 501 } 502 503 if (type == NFLOG) { 504 handle->linktype = DLT_NFLOG; 505 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 506 if (handle->dlt_list != NULL) { 507 handle->dlt_list[0] = DLT_NFLOG; 508 handle->dlt_list[1] = DLT_IPV4; 509 handle->dlt_count = 2; 510 } 511 512 } else 513 handle->linktype = DLT_IPV4; 514 515 handle->buffer = malloc(handle->bufsize); 516 if (!handle->buffer) { 517 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno)); 518 goto close_fail; 519 } 520 521 if (type == NFLOG) { 522 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 523 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); 524 goto close_fail; 525 } 526 527 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 528 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); 529 goto close_fail; 530 } 531 532 /* Bind socket to the nflog groups */ 533 for (i = 0; i < group_count; i++) { 534 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 535 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); 536 goto close_fail; 537 } 538 539 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { 540 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno)); 541 goto close_fail; 542 } 543 } 544 545 } else { 546 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 547 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); 548 goto close_fail; 549 } 550 551 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 552 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); 553 goto close_fail; 554 } 555 556 /* Bind socket to the nfqueue groups */ 557 for (i = 0; i < group_count; i++) { 558 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 559 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); 560 goto close_fail; 561 } 562 563 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { 564 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno)); 565 goto close_fail; 566 } 567 } 568 } 569 570 if (handle->opt.rfmon) { 571 /* 572 * Monitor mode doesn't apply to netfilter devices. 573 */ 574 pcap_cleanup_live_common(handle); 575 return PCAP_ERROR_RFMON_NOTSUP; 576 } 577 578 if (handle->opt.buffer_size != 0) { 579 /* 580 * Set the socket buffer size to the specified value. 581 */ 582 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { 583 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno)); 584 goto close_fail; 585 } 586 } 587 588 handle->selectable_fd = handle->fd; 589 return 0; 590 591 close_fail: 592 pcap_cleanup_live_common(handle); 593 return PCAP_ERROR; 594 } 595 596 pcap_t * 597 netfilter_create(const char *device, char *ebuf, int *is_ours) 598 { 599 const char *cp; 600 pcap_t *p; 601 602 /* Does this look like an netfilter device? */ 603 cp = strrchr(device, '/'); 604 if (cp == NULL) 605 cp = device; 606 607 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */ 608 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0) 609 cp += sizeof NFLOG_IFACE - 1; 610 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0) 611 cp += sizeof NFQUEUE_IFACE - 1; 612 else { 613 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */ 614 *is_ours = 0; 615 return NULL; 616 } 617 618 /* 619 * Yes - is that either the end of the name, or is it followed 620 * by a colon? 621 */ 622 if (*cp != ':' && *cp != '\0') { 623 /* Nope */ 624 *is_ours = 0; 625 return NULL; 626 } 627 628 /* OK, it's probably ours. */ 629 *is_ours = 1; 630 631 p = pcap_create_common(device, ebuf, sizeof (struct pcap_netfilter)); 632 if (p == NULL) 633 return (NULL); 634 635 p->activate_op = netfilter_activate; 636 return (p); 637 } 638 639 int 640 netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str) 641 { 642 int sock; 643 644 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 645 if (sock < 0) { 646 /* if netlink is not supported this is not fatal */ 647 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) 648 return 0; 649 snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s", 650 errno, pcap_strerror(errno)); 651 return -1; 652 } 653 close(sock); 654 655 if (pcap_add_if(alldevsp, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0) 656 return -1; 657 if (pcap_add_if(alldevsp, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0) 658 return -1; 659 return 0; 660 } 661