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 u_int packets_nobufs; /* ENOBUFS counter */ 83 }; 84 85 static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict); 86 87 88 static int 89 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) 90 { 91 struct pcap_netfilter *handlep = handle->priv; 92 const unsigned char *buf; 93 int count = 0; 94 int len; 95 96 /* ignore interrupt system call error */ 97 do { 98 len = recv(handle->fd, handle->buffer, handle->bufsize, 0); 99 if (handle->break_loop) { 100 handle->break_loop = 0; 101 return -2; 102 } 103 if(errno == ENOBUFS) handlep->packets_nobufs++; 104 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS)); 105 106 if (len < 0) { 107 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno)); 108 return -1; 109 } 110 111 buf = (unsigned char *)handle->buffer; 112 while ((u_int)len >= NLMSG_SPACE(0)) { 113 const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf; 114 u_int32_t msg_len; 115 nftype_t type = OTHER; 116 117 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) { 118 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); 119 return -1; 120 } 121 122 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && 123 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) 124 type = NFLOG; 125 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE && 126 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET) 127 type = NFQUEUE; 128 129 if (type != OTHER) { 130 const unsigned char *payload = NULL; 131 struct pcap_pkthdr pkth; 132 133 const struct nfgenmsg *nfg = NULL; 134 int id = 0; 135 136 if (handle->linktype != DLT_NFLOG) { 137 const struct nfattr *payload_attr = NULL; 138 139 if (nlh->nlmsg_len < HDR_LENGTH) { 140 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); 141 return -1; 142 } 143 144 nfg = NLMSG_DATA(nlh); 145 if (nlh->nlmsg_len > HDR_LENGTH) { 146 struct nfattr *attr = NFM_NFA(nfg); 147 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); 148 149 while (NFA_OK(attr, attr_len)) { 150 if (type == NFQUEUE) { 151 switch (NFA_TYPE(attr)) { 152 case NFQA_PACKET_HDR: 153 { 154 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr); 155 156 id = ntohl(pkt_hdr->packet_id); 157 break; 158 } 159 case NFQA_PAYLOAD: 160 payload_attr = attr; 161 break; 162 } 163 164 } else if (type == NFLOG) { 165 switch (NFA_TYPE(attr)) { 166 case NFULA_PAYLOAD: 167 payload_attr = attr; 168 break; 169 } 170 } 171 attr = NFA_NEXT(attr, attr_len); 172 } 173 } 174 175 if (payload_attr) { 176 payload = NFA_DATA(payload_attr); 177 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr); 178 } 179 180 } else { 181 payload = NLMSG_DATA(nlh); 182 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr)); 183 } 184 185 if (payload) { 186 /* pkth.caplen = min (payload_len, handle->snapshot); */ 187 188 gettimeofday(&pkth.ts, NULL); 189 if (handle->fcode.bf_insns == NULL || 190 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) 191 { 192 handlep->packets_read++; 193 callback(user, &pkth, payload); 194 count++; 195 } 196 } 197 198 if (type == NFQUEUE) { 199 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */ 200 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG, 201 so nfg is always initialized to NLMSG_DATA(nlh). */ 202 if (nfg != NULL) 203 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT); 204 } 205 } 206 207 msg_len = NLMSG_ALIGN(nlh->nlmsg_len); 208 if (msg_len > (u_int)len) 209 msg_len = (u_int)len; 210 211 len -= msg_len; 212 buf += msg_len; 213 } 214 return count; 215 } 216 217 static int 218 netfilter_set_datalink(pcap_t *handle, int dlt) 219 { 220 handle->linktype = dlt; 221 return 0; 222 } 223 224 static int 225 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) 226 { 227 struct pcap_netfilter *handlep = handle->priv; 228 229 stats->ps_recv = handlep->packets_read; 230 stats->ps_drop = handlep->packets_nobufs; 231 stats->ps_ifdrop = 0; 232 return 0; 233 } 234 235 static int 236 netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size) 237 { 238 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices"); 239 return (-1); 240 } 241 242 struct my_nfattr { 243 u_int16_t nfa_len; 244 u_int16_t nfa_type; 245 void *data; 246 }; 247 248 static int 249 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) 250 { 251 char buf[1024] __attribute__ ((aligned)); 252 253 struct nlmsghdr *nlh = (struct nlmsghdr *) buf; 254 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); 255 256 struct sockaddr_nl snl; 257 static unsigned int seq_id; 258 259 if (!seq_id) 260 seq_id = time(NULL); 261 ++seq_id; 262 263 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); 264 nlh->nlmsg_type = msg_type; 265 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0); 266 nlh->nlmsg_pid = 0; /* to kernel */ 267 nlh->nlmsg_seq = seq_id; 268 269 nfg->nfgen_family = family; 270 nfg->version = NFNETLINK_V0; 271 nfg->res_id = htons(res_id); 272 273 if (mynfa) { 274 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); 275 276 nfa->nfa_type = mynfa->nfa_type; 277 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); 278 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); 279 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); 280 } 281 282 memset(&snl, 0, sizeof(snl)); 283 snl.nl_family = AF_NETLINK; 284 285 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) 286 return -1; 287 288 if (!ack) 289 return 0; 290 291 /* waiting for reply loop */ 292 do { 293 socklen_t addrlen = sizeof(snl); 294 int len; 295 296 /* ignore interrupt system call error */ 297 do { 298 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); 299 } while ((len == -1) && (errno == EINTR)); 300 301 if (len <= 0) 302 return len; 303 304 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { 305 errno = EINVAL; 306 return -1; 307 } 308 309 nlh = (struct nlmsghdr *) buf; 310 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ 311 continue; 312 313 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) { 314 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { 315 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { 316 errno = EBADMSG; 317 return -1; 318 } 319 errno = -(*((int *)NLMSG_DATA(nlh))); 320 return (errno == 0) ? 0 : -1; 321 } 322 nlh = NLMSG_NEXT(nlh, len); 323 } 324 } while (1); 325 326 return -1; /* never here */ 327 } 328 329 static int 330 nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 331 { 332 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); 333 } 334 335 static int 336 nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family) 337 { 338 struct nfulnl_msg_config_cmd msg; 339 struct my_nfattr nfa; 340 341 msg.command = cmd; 342 343 nfa.data = &msg; 344 nfa.nfa_type = NFULA_CFG_CMD; 345 nfa.nfa_len = sizeof(msg); 346 347 return nflog_send_config_msg(handle, family, group_id, &nfa); 348 } 349 350 static int 351 nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 352 { 353 struct nfulnl_msg_config_mode msg; 354 struct my_nfattr nfa; 355 356 msg.copy_range = htonl(copy_range); 357 msg.copy_mode = copy_mode; 358 359 nfa.data = &msg; 360 nfa.nfa_type = NFULA_CFG_MODE; 361 nfa.nfa_len = sizeof(msg); 362 363 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 364 } 365 366 static int 367 nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict) 368 { 369 struct nfqnl_msg_verdict_hdr msg; 370 struct my_nfattr nfa; 371 372 msg.id = htonl(id); 373 msg.verdict = htonl(verdict); 374 375 nfa.data = &msg; 376 nfa.nfa_type = NFQA_VERDICT_HDR; 377 nfa.nfa_len = sizeof(msg); 378 379 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa); 380 } 381 382 static int 383 nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 384 { 385 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); 386 } 387 388 static int 389 nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf) 390 { 391 struct nfqnl_msg_config_cmd msg; 392 struct my_nfattr nfa; 393 394 msg.command = cmd; 395 msg.pf = htons(pf); 396 397 nfa.data = &msg; 398 nfa.nfa_type = NFQA_CFG_CMD; 399 nfa.nfa_len = sizeof(msg); 400 401 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 402 } 403 404 static int 405 nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 406 { 407 struct nfqnl_msg_config_params msg; 408 struct my_nfattr nfa; 409 410 msg.copy_range = htonl(copy_range); 411 msg.copy_mode = copy_mode; 412 413 nfa.data = &msg; 414 nfa.nfa_type = NFQA_CFG_PARAMS; 415 nfa.nfa_len = sizeof(msg); 416 417 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 418 } 419 420 static int 421 netfilter_activate(pcap_t* handle) 422 { 423 const char *dev = handle->opt.device; 424 unsigned short groups[32]; 425 int group_count = 0; 426 nftype_t type = OTHER; 427 int i; 428 429 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { 430 dev += strlen(NFLOG_IFACE); 431 type = NFLOG; 432 433 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) { 434 dev += strlen(NFQUEUE_IFACE); 435 type = NFQUEUE; 436 } 437 438 if (type != OTHER && *dev == ':') { 439 dev++; 440 while (*dev) { 441 long int group_id; 442 char *end_dev; 443 444 if (group_count == 32) { 445 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 446 "Maximum 32 netfilter groups! dev: %s", 447 handle->opt.device); 448 return PCAP_ERROR; 449 } 450 451 group_id = strtol(dev, &end_dev, 0); 452 if (end_dev != dev) { 453 if (group_id < 0 || group_id > 65535) { 454 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 455 "Netfilter group range from 0 to 65535 (got %ld)", 456 group_id); 457 return PCAP_ERROR; 458 } 459 460 groups[group_count++] = (unsigned short) group_id; 461 dev = end_dev; 462 } 463 if (*dev != ',') 464 break; 465 dev++; 466 } 467 } 468 469 if (type == OTHER || *dev) { 470 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 471 "Can't get netfilter group(s) index from %s", 472 handle->opt.device); 473 return PCAP_ERROR; 474 } 475 476 /* if no groups, add default: 0 */ 477 if (!group_count) { 478 groups[0] = 0; 479 group_count = 1; 480 } 481 482 /* Initialize some components of the pcap structure. */ 483 handle->bufsize = 128 + handle->snapshot; 484 handle->offset = 0; 485 handle->read_op = netfilter_read_linux; 486 handle->inject_op = netfilter_inject_linux; 487 handle->setfilter_op = install_bpf_program; /* no kernel filtering */ 488 handle->setdirection_op = NULL; 489 handle->set_datalink_op = netfilter_set_datalink; 490 handle->getnonblock_op = pcap_getnonblock_fd; 491 handle->setnonblock_op = pcap_setnonblock_fd; 492 handle->stats_op = netfilter_stats_linux; 493 494 /* Create netlink socket */ 495 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 496 if (handle->fd < 0) { 497 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno)); 498 return PCAP_ERROR; 499 } 500 501 if (type == NFLOG) { 502 handle->linktype = DLT_NFLOG; 503 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 504 if (handle->dlt_list != NULL) { 505 handle->dlt_list[0] = DLT_NFLOG; 506 handle->dlt_list[1] = DLT_IPV4; 507 handle->dlt_count = 2; 508 } 509 510 } else 511 handle->linktype = DLT_IPV4; 512 513 handle->buffer = malloc(handle->bufsize); 514 if (!handle->buffer) { 515 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno)); 516 goto close_fail; 517 } 518 519 if (type == NFLOG) { 520 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 521 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); 522 goto close_fail; 523 } 524 525 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 526 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); 527 goto close_fail; 528 } 529 530 /* Bind socket to the nflog groups */ 531 for (i = 0; i < group_count; i++) { 532 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 533 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); 534 goto close_fail; 535 } 536 537 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { 538 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno)); 539 goto close_fail; 540 } 541 } 542 543 } else { 544 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 545 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); 546 goto close_fail; 547 } 548 549 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 550 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); 551 goto close_fail; 552 } 553 554 /* Bind socket to the nfqueue groups */ 555 for (i = 0; i < group_count; i++) { 556 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 557 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); 558 goto close_fail; 559 } 560 561 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { 562 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno)); 563 goto close_fail; 564 } 565 } 566 } 567 568 if (handle->opt.rfmon) { 569 /* 570 * Monitor mode doesn't apply to netfilter devices. 571 */ 572 pcap_cleanup_live_common(handle); 573 return PCAP_ERROR_RFMON_NOTSUP; 574 } 575 576 if (handle->opt.buffer_size != 0) { 577 /* 578 * Set the socket buffer size to the specified value. 579 */ 580 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { 581 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno)); 582 goto close_fail; 583 } 584 } 585 586 handle->selectable_fd = handle->fd; 587 return 0; 588 589 close_fail: 590 pcap_cleanup_live_common(handle); 591 return PCAP_ERROR; 592 } 593 594 pcap_t * 595 netfilter_create(const char *device, char *ebuf, int *is_ours) 596 { 597 const char *cp; 598 pcap_t *p; 599 600 /* Does this look like an netfilter device? */ 601 cp = strrchr(device, '/'); 602 if (cp == NULL) 603 cp = device; 604 605 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */ 606 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0) 607 cp += sizeof NFLOG_IFACE - 1; 608 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0) 609 cp += sizeof NFQUEUE_IFACE - 1; 610 else { 611 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */ 612 *is_ours = 0; 613 return NULL; 614 } 615 616 /* 617 * Yes - is that either the end of the name, or is it followed 618 * by a colon? 619 */ 620 if (*cp != ':' && *cp != '\0') { 621 /* Nope */ 622 *is_ours = 0; 623 return NULL; 624 } 625 626 /* OK, it's probably ours. */ 627 *is_ours = 1; 628 629 p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter)); 630 if (p == NULL) 631 return (NULL); 632 633 p->activate_op = netfilter_activate; 634 return (p); 635 } 636 637 int 638 netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str) 639 { 640 int sock; 641 642 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 643 if (sock < 0) { 644 /* if netlink is not supported this is not fatal */ 645 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) 646 return 0; 647 pcap_snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s", 648 errno, pcap_strerror(errno)); 649 return -1; 650 } 651 close(sock); 652 653 if (pcap_add_if(alldevsp, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0) 654 return -1; 655 if (pcap_add_if(alldevsp, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0) 656 return -1; 657 return 0; 658 } 659
