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, uint16_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 register u_char *bp, *ep; 93 int count = 0; 94 int len; 95 96 /* 97 * Has "pcap_breakloop()" been called? 98 */ 99 if (handle->break_loop) { 100 /* 101 * Yes - clear the flag that indicates that it 102 * has, and return PCAP_ERROR_BREAK to indicate 103 * that we were told to break out of the loop. 104 */ 105 handle->break_loop = 0; 106 return PCAP_ERROR_BREAK; 107 } 108 len = handle->cc; 109 if (len == 0) { 110 /* 111 * The buffer is empty; refill it. 112 * 113 * We ignore EINTR, as that might just be due to a signal 114 * being delivered - if the signal should interrupt the 115 * loop, the signal handler should call pcap_breakloop() 116 * to set handle->break_loop (we ignore it on other 117 * platforms as well). 118 */ 119 do { 120 len = recv(handle->fd, handle->buffer, handle->bufsize, 0); 121 if (handle->break_loop) { 122 handle->break_loop = 0; 123 return PCAP_ERROR_BREAK; 124 } 125 if (errno == ENOBUFS) 126 handlep->packets_nobufs++; 127 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS)); 128 129 if (len < 0) { 130 pcap_fmt_errmsg_for_errno(handle->errbuf, 131 PCAP_ERRBUF_SIZE, errno, "Can't receive packet"); 132 return PCAP_ERROR; 133 } 134 135 bp = (unsigned char *)handle->buffer; 136 } else 137 bp = handle->bp; 138 ep = bp + len; 139 while (bp < ep) { 140 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp; 141 uint32_t msg_len; 142 nftype_t type = OTHER; 143 /* 144 * Has "pcap_breakloop()" been called? 145 * If so, return immediately - if we haven't read any 146 * packets, clear the flag and return PCAP_ERROR_BREAK 147 * to indicate that we were told to break out of the loop, 148 * otherwise leave the flag set, so that the *next* call 149 * will break out of the loop without having read any 150 * packets, and return the number of packets we've 151 * processed so far. 152 */ 153 if (handle->break_loop) { 154 handle->bp = bp; 155 handle->cc = ep - bp; 156 if (count == 0) { 157 handle->break_loop = 0; 158 return PCAP_ERROR_BREAK; 159 } else 160 return count; 161 } 162 if (ep - bp < NLMSG_SPACE(0)) { 163 /* 164 * There's less than one netlink message left 165 * in the buffer. Give up. 166 */ 167 break; 168 } 169 170 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) { 171 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); 172 return -1; 173 } 174 175 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && 176 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) 177 type = NFLOG; 178 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE && 179 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET) 180 type = NFQUEUE; 181 182 if (type != OTHER) { 183 const unsigned char *payload = NULL; 184 struct pcap_pkthdr pkth; 185 186 const struct nfgenmsg *nfg = NULL; 187 int id = 0; 188 189 if (handle->linktype != DLT_NFLOG) { 190 const struct nfattr *payload_attr = NULL; 191 192 if (nlh->nlmsg_len < HDR_LENGTH) { 193 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); 194 return -1; 195 } 196 197 nfg = NLMSG_DATA(nlh); 198 if (nlh->nlmsg_len > HDR_LENGTH) { 199 struct nfattr *attr = NFM_NFA(nfg); 200 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); 201 202 while (NFA_OK(attr, attr_len)) { 203 if (type == NFQUEUE) { 204 switch (NFA_TYPE(attr)) { 205 case NFQA_PACKET_HDR: 206 { 207 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr); 208 209 id = ntohl(pkt_hdr->packet_id); 210 break; 211 } 212 case NFQA_PAYLOAD: 213 payload_attr = attr; 214 break; 215 } 216 217 } else if (type == NFLOG) { 218 switch (NFA_TYPE(attr)) { 219 case NFULA_PAYLOAD: 220 payload_attr = attr; 221 break; 222 } 223 } 224 attr = NFA_NEXT(attr, attr_len); 225 } 226 } 227 228 if (payload_attr) { 229 payload = NFA_DATA(payload_attr); 230 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr); 231 } 232 233 } else { 234 payload = NLMSG_DATA(nlh); 235 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr)); 236 } 237 238 if (payload) { 239 /* pkth.caplen = min (payload_len, handle->snapshot); */ 240 241 gettimeofday(&pkth.ts, NULL); 242 if (handle->fcode.bf_insns == NULL || 243 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) 244 { 245 handlep->packets_read++; 246 callback(user, &pkth, payload); 247 count++; 248 } 249 } 250 251 if (type == NFQUEUE) { 252 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */ 253 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG, 254 so nfg is always initialized to NLMSG_DATA(nlh). */ 255 if (nfg != NULL) 256 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT); 257 } 258 } 259 260 msg_len = NLMSG_ALIGN(nlh->nlmsg_len); 261 /* 262 * If the message length would run past the end of the 263 * buffer, truncate it to the remaining space in the 264 * buffer. 265 */ 266 if (msg_len > ep - bp) 267 msg_len = ep - bp; 268 269 bp += msg_len; 270 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) { 271 handle->bp = bp; 272 handle->cc = ep - bp; 273 if (handle->cc < 0) 274 handle->cc = 0; 275 return count; 276 } 277 } 278 279 handle->cc = 0; 280 return count; 281 } 282 283 static int 284 netfilter_set_datalink(pcap_t *handle, int dlt) 285 { 286 handle->linktype = dlt; 287 return 0; 288 } 289 290 static int 291 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) 292 { 293 struct pcap_netfilter *handlep = handle->priv; 294 295 stats->ps_recv = handlep->packets_read; 296 stats->ps_drop = handlep->packets_nobufs; 297 stats->ps_ifdrop = 0; 298 return 0; 299 } 300 301 static int 302 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_) 303 { 304 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices"); 305 return (-1); 306 } 307 308 struct my_nfattr { 309 uint16_t nfa_len; 310 uint16_t nfa_type; 311 void *data; 312 }; 313 314 static int 315 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) 316 { 317 char buf[1024] __attribute__ ((aligned)); 318 319 struct nlmsghdr *nlh = (struct nlmsghdr *) buf; 320 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); 321 322 struct sockaddr_nl snl; 323 static unsigned int seq_id; 324 325 if (!seq_id) 326 seq_id = time(NULL); 327 ++seq_id; 328 329 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); 330 nlh->nlmsg_type = msg_type; 331 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0); 332 nlh->nlmsg_pid = 0; /* to kernel */ 333 nlh->nlmsg_seq = seq_id; 334 335 nfg->nfgen_family = family; 336 nfg->version = NFNETLINK_V0; 337 nfg->res_id = htons(res_id); 338 339 if (mynfa) { 340 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); 341 342 nfa->nfa_type = mynfa->nfa_type; 343 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); 344 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); 345 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); 346 } 347 348 memset(&snl, 0, sizeof(snl)); 349 snl.nl_family = AF_NETLINK; 350 351 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) 352 return -1; 353 354 if (!ack) 355 return 0; 356 357 /* waiting for reply loop */ 358 do { 359 socklen_t addrlen = sizeof(snl); 360 int len; 361 362 /* ignore interrupt system call error */ 363 do { 364 len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); 365 } while ((len == -1) && (errno == EINTR)); 366 367 if (len <= 0) 368 return len; 369 370 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { 371 errno = EINVAL; 372 return -1; 373 } 374 375 nlh = (struct nlmsghdr *) buf; 376 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ 377 continue; 378 379 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) { 380 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { 381 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { 382 errno = EBADMSG; 383 return -1; 384 } 385 errno = -(*((int *)NLMSG_DATA(nlh))); 386 return (errno == 0) ? 0 : -1; 387 } 388 nlh = NLMSG_NEXT(nlh, len); 389 } 390 } while (1); 391 392 return -1; /* never here */ 393 } 394 395 static int 396 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 397 { 398 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); 399 } 400 401 static int 402 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family) 403 { 404 struct nfulnl_msg_config_cmd msg; 405 struct my_nfattr nfa; 406 407 msg.command = cmd; 408 409 nfa.data = &msg; 410 nfa.nfa_type = NFULA_CFG_CMD; 411 nfa.nfa_len = sizeof(msg); 412 413 return nflog_send_config_msg(handle, family, group_id, &nfa); 414 } 415 416 static int 417 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 418 { 419 struct nfulnl_msg_config_mode msg; 420 struct my_nfattr nfa; 421 422 msg.copy_range = htonl(copy_range); 423 msg.copy_mode = copy_mode; 424 425 nfa.data = &msg; 426 nfa.nfa_type = NFULA_CFG_MODE; 427 nfa.nfa_len = sizeof(msg); 428 429 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 430 } 431 432 static int 433 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict) 434 { 435 struct nfqnl_msg_verdict_hdr msg; 436 struct my_nfattr nfa; 437 438 msg.id = htonl(id); 439 msg.verdict = htonl(verdict); 440 441 nfa.data = &msg; 442 nfa.nfa_type = NFQA_VERDICT_HDR; 443 nfa.nfa_len = sizeof(msg); 444 445 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa); 446 } 447 448 static int 449 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 450 { 451 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); 452 } 453 454 static int 455 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf) 456 { 457 struct nfqnl_msg_config_cmd msg; 458 struct my_nfattr nfa; 459 460 msg.command = cmd; 461 msg.pf = htons(pf); 462 463 nfa.data = &msg; 464 nfa.nfa_type = NFQA_CFG_CMD; 465 nfa.nfa_len = sizeof(msg); 466 467 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 468 } 469 470 static int 471 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 472 { 473 struct nfqnl_msg_config_params msg; 474 struct my_nfattr nfa; 475 476 msg.copy_range = htonl(copy_range); 477 msg.copy_mode = copy_mode; 478 479 nfa.data = &msg; 480 nfa.nfa_type = NFQA_CFG_PARAMS; 481 nfa.nfa_len = sizeof(msg); 482 483 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 484 } 485 486 static int 487 netfilter_activate(pcap_t* handle) 488 { 489 const char *dev = handle->opt.device; 490 unsigned short groups[32]; 491 int group_count = 0; 492 nftype_t type = OTHER; 493 int i; 494 495 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { 496 dev += strlen(NFLOG_IFACE); 497 type = NFLOG; 498 499 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) { 500 dev += strlen(NFQUEUE_IFACE); 501 type = NFQUEUE; 502 } 503 504 if (type != OTHER && *dev == ':') { 505 dev++; 506 while (*dev) { 507 long int group_id; 508 char *end_dev; 509 510 if (group_count == 32) { 511 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 512 "Maximum 32 netfilter groups! dev: %s", 513 handle->opt.device); 514 return PCAP_ERROR; 515 } 516 517 group_id = strtol(dev, &end_dev, 0); 518 if (end_dev != dev) { 519 if (group_id < 0 || group_id > 65535) { 520 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 521 "Netfilter group range from 0 to 65535 (got %ld)", 522 group_id); 523 return PCAP_ERROR; 524 } 525 526 groups[group_count++] = (unsigned short) group_id; 527 dev = end_dev; 528 } 529 if (*dev != ',') 530 break; 531 dev++; 532 } 533 } 534 535 if (type == OTHER || *dev) { 536 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 537 "Can't get netfilter group(s) index from %s", 538 handle->opt.device); 539 return PCAP_ERROR; 540 } 541 542 /* if no groups, add default: 0 */ 543 if (!group_count) { 544 groups[0] = 0; 545 group_count = 1; 546 } 547 548 /* 549 * Turn a negative snapshot value (invalid), a snapshot value of 550 * 0 (unspecified), or a value bigger than the normal maximum 551 * value, into the maximum allowed value. 552 * 553 * If some application really *needs* a bigger snapshot 554 * length, we should just increase MAXIMUM_SNAPLEN. 555 */ 556 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN) 557 handle->snapshot = MAXIMUM_SNAPLEN; 558 559 /* Initialize some components of the pcap structure. */ 560 handle->bufsize = 128 + handle->snapshot; 561 handle->offset = 0; 562 handle->read_op = netfilter_read_linux; 563 handle->inject_op = netfilter_inject_linux; 564 handle->setfilter_op = install_bpf_program; /* no kernel filtering */ 565 handle->setdirection_op = NULL; 566 handle->set_datalink_op = netfilter_set_datalink; 567 handle->getnonblock_op = pcap_getnonblock_fd; 568 handle->setnonblock_op = pcap_setnonblock_fd; 569 handle->stats_op = netfilter_stats_linux; 570 571 /* Create netlink socket */ 572 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 573 if (handle->fd < 0) { 574 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, 575 errno, "Can't create raw socket"); 576 return PCAP_ERROR; 577 } 578 579 if (type == NFLOG) { 580 handle->linktype = DLT_NFLOG; 581 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 582 if (handle->dlt_list != NULL) { 583 handle->dlt_list[0] = DLT_NFLOG; 584 handle->dlt_list[1] = DLT_IPV4; 585 handle->dlt_count = 2; 586 } 587 588 } else 589 handle->linktype = DLT_IPV4; 590 591 handle->buffer = malloc(handle->bufsize); 592 if (!handle->buffer) { 593 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, 594 errno, "Can't allocate dump buffer"); 595 goto close_fail; 596 } 597 598 if (type == NFLOG) { 599 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 600 pcap_fmt_errmsg_for_errno(handle->errbuf, 601 PCAP_ERRBUF_SIZE, errno, 602 "NFULNL_CFG_CMD_PF_UNBIND"); 603 goto close_fail; 604 } 605 606 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 607 pcap_fmt_errmsg_for_errno(handle->errbuf, 608 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND"); 609 goto close_fail; 610 } 611 612 /* Bind socket to the nflog groups */ 613 for (i = 0; i < group_count; i++) { 614 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 615 pcap_fmt_errmsg_for_errno(handle->errbuf, 616 PCAP_ERRBUF_SIZE, errno, 617 "Can't listen on group group index"); 618 goto close_fail; 619 } 620 621 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { 622 pcap_fmt_errmsg_for_errno(handle->errbuf, 623 PCAP_ERRBUF_SIZE, errno, 624 "NFULNL_COPY_PACKET"); 625 goto close_fail; 626 } 627 } 628 629 } else { 630 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 631 pcap_fmt_errmsg_for_errno(handle->errbuf, 632 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND"); 633 goto close_fail; 634 } 635 636 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 637 pcap_fmt_errmsg_for_errno(handle->errbuf, 638 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND"); 639 goto close_fail; 640 } 641 642 /* Bind socket to the nfqueue groups */ 643 for (i = 0; i < group_count; i++) { 644 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 645 pcap_fmt_errmsg_for_errno(handle->errbuf, 646 PCAP_ERRBUF_SIZE, errno, 647 "Can't listen on group group index"); 648 goto close_fail; 649 } 650 651 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { 652 pcap_fmt_errmsg_for_errno(handle->errbuf, 653 PCAP_ERRBUF_SIZE, errno, 654 "NFQNL_COPY_PACKET"); 655 goto close_fail; 656 } 657 } 658 } 659 660 if (handle->opt.rfmon) { 661 /* 662 * Monitor mode doesn't apply to netfilter devices. 663 */ 664 pcap_cleanup_live_common(handle); 665 return PCAP_ERROR_RFMON_NOTSUP; 666 } 667 668 if (handle->opt.buffer_size != 0) { 669 /* 670 * Set the socket buffer size to the specified value. 671 */ 672 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { 673 pcap_fmt_errmsg_for_errno(handle->errbuf, 674 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF"); 675 goto close_fail; 676 } 677 } 678 679 handle->selectable_fd = handle->fd; 680 return 0; 681 682 close_fail: 683 pcap_cleanup_live_common(handle); 684 return PCAP_ERROR; 685 } 686 687 pcap_t * 688 netfilter_create(const char *device, char *ebuf, int *is_ours) 689 { 690 const char *cp; 691 pcap_t *p; 692 693 /* Does this look like an netfilter device? */ 694 cp = strrchr(device, '/'); 695 if (cp == NULL) 696 cp = device; 697 698 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */ 699 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0) 700 cp += sizeof NFLOG_IFACE - 1; 701 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0) 702 cp += sizeof NFQUEUE_IFACE - 1; 703 else { 704 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */ 705 *is_ours = 0; 706 return NULL; 707 } 708 709 /* 710 * Yes - is that either the end of the name, or is it followed 711 * by a colon? 712 */ 713 if (*cp != ':' && *cp != '\0') { 714 /* Nope */ 715 *is_ours = 0; 716 return NULL; 717 } 718 719 /* OK, it's probably ours. */ 720 *is_ours = 1; 721 722 p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter)); 723 if (p == NULL) 724 return (NULL); 725 726 p->activate_op = netfilter_activate; 727 return (p); 728 } 729 730 int 731 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str) 732 { 733 int sock; 734 735 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 736 if (sock < 0) { 737 /* if netlink is not supported this is not fatal */ 738 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) 739 return 0; 740 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE, 741 errno, "Can't open netlink socket"); 742 return -1; 743 } 744 close(sock); 745 746 /* 747 * The notion of "connected" vs. "disconnected" doesn't apply. 748 * XXX - what about "up" and "running"? 749 */ 750 if (add_dev(devlistp, NFLOG_IFACE, 751 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, 752 "Linux netfilter log (NFLOG) interface", err_str) == NULL) 753 return -1; 754 if (add_dev(devlistp, NFQUEUE_IFACE, 755 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, 756 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL) 757 return -1; 758 return 0; 759 } 760