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#include "diag-control.h" 37 38#ifdef NEED_STRERROR_H 39#include "strerror.h" 40#endif 41 42#include <errno.h> 43#include <stdlib.h> 44#include <unistd.h> 45#include <string.h> 46#include <sys/socket.h> 47#include <arpa/inet.h> 48 49#include <time.h> 50#include <sys/time.h> 51#include <netinet/in.h> 52#include <linux/types.h> 53 54#include <linux/netlink.h> 55#include <linux/netfilter.h> 56#include <linux/netfilter/nfnetlink.h> 57#include <linux/netfilter/nfnetlink_log.h> 58#include <linux/netfilter/nfnetlink_queue.h> 59 60/* NOTE: if your program drops privileges after pcap_activate() it WON'T work with nfqueue. 61 * It took me quite some time to debug ;/ 62 * 63 * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges, 64 * and in nfqueue we need to send verdict reply after recving packet. 65 * 66 * In tcpdump you can disable dropping privileges with -Z root 67 */ 68 69#include "pcap-netfilter-linux.h" 70 71#define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) 72 73#define NFLOG_IFACE "nflog" 74#define NFQUEUE_IFACE "nfqueue" 75 76typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t; 77 78/* 79 * Private data for capturing on Linux netfilter sockets. 80 */ 81struct pcap_netfilter { 82 u_int packets_read; /* count of packets read with recvfrom() */ 83 u_int packets_nobufs; /* ENOBUFS counter */ 84}; 85 86static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict); 87 88 89static int 90netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) 91{ 92 struct pcap_netfilter *handlep = handle->priv; 93 register u_char *bp, *ep; 94 int count = 0; 95 ssize_t len; 96 97 /* 98 * Has "pcap_breakloop()" been called? 99 */ 100 if (handle->break_loop) { 101 /* 102 * Yes - clear the flag that indicates that it 103 * has, and return PCAP_ERROR_BREAK to indicate 104 * that we were told to break out of the loop. 105 */ 106 handle->break_loop = 0; 107 return PCAP_ERROR_BREAK; 108 } 109 len = handle->cc; 110 if (len == 0) { 111 /* 112 * The buffer is empty; refill it. 113 * 114 * We ignore EINTR, as that might just be due to a signal 115 * being delivered - if the signal should interrupt the 116 * loop, the signal handler should call pcap_breakloop() 117 * to set handle->break_loop (we ignore it on other 118 * platforms as well). 119 */ 120 do { 121 len = recv(handle->fd, handle->buffer, handle->bufsize, 0); 122 if (handle->break_loop) { 123 handle->break_loop = 0; 124 return PCAP_ERROR_BREAK; 125 } 126 if (errno == ENOBUFS) 127 handlep->packets_nobufs++; 128 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS)); 129 130 if (len < 0) { 131 pcap_fmt_errmsg_for_errno(handle->errbuf, 132 PCAP_ERRBUF_SIZE, errno, "Can't receive packet"); 133 return PCAP_ERROR; 134 } 135 136 bp = (unsigned char *)handle->buffer; 137 } else 138 bp = handle->bp; 139 140 /* 141 * Loop through each message. 142 * 143 * This assumes that a single buffer of message will have 144 * <= INT_MAX packets, so the message count doesn't overflow. 145 */ 146 ep = bp + len; 147 while (bp < ep) { 148 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp; 149 uint32_t msg_len; 150 nftype_t type = OTHER; 151 /* 152 * Has "pcap_breakloop()" been called? 153 * If so, return immediately - if we haven't read any 154 * packets, clear the flag and return PCAP_ERROR_BREAK 155 * to indicate that we were told to break out of the loop, 156 * otherwise leave the flag set, so that the *next* call 157 * will break out of the loop without having read any 158 * packets, and return the number of packets we've 159 * processed so far. 160 */ 161 if (handle->break_loop) { 162 handle->bp = bp; 163 handle->cc = (int)(ep - bp); 164 if (count == 0) { 165 handle->break_loop = 0; 166 return PCAP_ERROR_BREAK; 167 } else 168 return count; 169 } 170 /* 171 * NLMSG_SPACE(0) might be signed or might be unsigned, 172 * depending on whether the kernel defines NLMSG_ALIGNTO 173 * as 4, which older kernels do, or as 4U, which newer 174 * kernels do. 175 * 176 * ep - bp is of type ptrdiff_t, which is signed. 177 * 178 * To squelch warnings, we cast both to size_t, which 179 * is unsigned; ep >= bp, so the cast is safe. 180 */ 181 if ((size_t)(ep - bp) < (size_t)NLMSG_SPACE(0)) { 182 /* 183 * There's less than one netlink message left 184 * in the buffer. Give up. 185 */ 186 break; 187 } 188 189 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) { 190 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len); 191 return -1; 192 } 193 194 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && 195 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) 196 type = NFLOG; 197 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE && 198 NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET) 199 type = NFQUEUE; 200 201 if (type != OTHER) { 202 const unsigned char *payload = NULL; 203 struct pcap_pkthdr pkth; 204 205 const struct nfgenmsg *nfg = NULL; 206 int id = 0; 207 208 if (handle->linktype != DLT_NFLOG) { 209 const struct nfattr *payload_attr = NULL; 210 211 if (nlh->nlmsg_len < HDR_LENGTH) { 212 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); 213 return -1; 214 } 215 216 nfg = NLMSG_DATA(nlh); 217 if (nlh->nlmsg_len > HDR_LENGTH) { 218 struct nfattr *attr = NFM_NFA(nfg); 219 int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); 220 221 while (NFA_OK(attr, attr_len)) { 222 if (type == NFQUEUE) { 223 switch (NFA_TYPE(attr)) { 224 case NFQA_PACKET_HDR: 225 { 226 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr); 227 228 id = ntohl(pkt_hdr->packet_id); 229 break; 230 } 231 case NFQA_PAYLOAD: 232 payload_attr = attr; 233 break; 234 } 235 236 } else if (type == NFLOG) { 237 switch (NFA_TYPE(attr)) { 238 case NFULA_PAYLOAD: 239 payload_attr = attr; 240 break; 241 } 242 } 243 attr = NFA_NEXT(attr, attr_len); 244 } 245 } 246 247 if (payload_attr) { 248 payload = NFA_DATA(payload_attr); 249 pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr); 250 } 251 252 } else { 253 payload = NLMSG_DATA(nlh); 254 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr)); 255 } 256 257 if (payload) { 258 /* pkth.caplen = min (payload_len, handle->snapshot); */ 259 260 gettimeofday(&pkth.ts, NULL); 261 if (handle->fcode.bf_insns == NULL || 262 pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) 263 { 264 handlep->packets_read++; 265 callback(user, &pkth, payload); 266 count++; 267 } 268 } 269 270 if (type == NFQUEUE) { 271 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */ 272 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG, 273 so nfg is always initialized to NLMSG_DATA(nlh). */ 274 if (nfg != NULL) 275 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT); 276 } 277 } 278 279 msg_len = NLMSG_ALIGN(nlh->nlmsg_len); 280 /* 281 * If the message length would run past the end of the 282 * buffer, truncate it to the remaining space in the 283 * buffer. 284 * 285 * To squelch warnings, we cast ep - bp to uint32_t, which 286 * is unsigned and is the type of msg_len; ep >= bp, and 287 * len should fit in 32 bits (either it's set from an int 288 * or it's set from a recv() call with a buffer size that's 289 * an int, and we're assuming either ILP32 or LP64), so 290 * the cast is safe. 291 */ 292 if (msg_len > (uint32_t)(ep - bp)) 293 msg_len = (uint32_t)(ep - bp); 294 295 bp += msg_len; 296 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) { 297 handle->bp = bp; 298 handle->cc = (int)(ep - bp); 299 if (handle->cc < 0) 300 handle->cc = 0; 301 return count; 302 } 303 } 304 305 handle->cc = 0; 306 return count; 307} 308 309static int 310netfilter_set_datalink(pcap_t *handle, int dlt) 311{ 312 handle->linktype = dlt; 313 return 0; 314} 315 316static int 317netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) 318{ 319 struct pcap_netfilter *handlep = handle->priv; 320 321 stats->ps_recv = handlep->packets_read; 322 stats->ps_drop = handlep->packets_nobufs; 323 stats->ps_ifdrop = 0; 324 return 0; 325} 326 327static int 328netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_) 329{ 330 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 331 "Packet injection is not supported on netfilter devices"); 332 return (-1); 333} 334 335struct my_nfattr { 336 uint16_t nfa_len; 337 uint16_t nfa_type; 338 void *data; 339}; 340 341static int 342netfilter_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) 343{ 344 char buf[1024] __attribute__ ((aligned)); 345 memset(buf, 0, sizeof(buf)); 346 347 struct nlmsghdr *nlh = (struct nlmsghdr *) buf; 348 struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); 349 350 struct sockaddr_nl snl; 351 static unsigned int seq_id; 352 353 if (!seq_id) 354DIAG_OFF_NARROWING 355 seq_id = time(NULL); 356DIAG_ON_NARROWING 357 ++seq_id; 358 359 nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); 360 nlh->nlmsg_type = msg_type; 361 nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0); 362 nlh->nlmsg_pid = 0; /* to kernel */ 363 nlh->nlmsg_seq = seq_id; 364 365 nfg->nfgen_family = family; 366 nfg->version = NFNETLINK_V0; 367 nfg->res_id = htons(res_id); 368 369 if (mynfa) { 370 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); 371 372 nfa->nfa_type = mynfa->nfa_type; 373 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); 374 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); 375 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); 376 } 377 378 memset(&snl, 0, sizeof(snl)); 379 snl.nl_family = AF_NETLINK; 380 381 if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) 382 return -1; 383 384 if (!ack) 385 return 0; 386 387 /* waiting for reply loop */ 388 do { 389 socklen_t addrlen = sizeof(snl); 390 int len; 391 392 /* ignore interrupt system call error */ 393 do { 394 /* 395 * The buffer is not so big that its size won't 396 * fit into an int. 397 */ 398 len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); 399 } while ((len == -1) && (errno == EINTR)); 400 401 if (len <= 0) 402 return len; 403 404 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { 405 errno = EINVAL; 406 return -1; 407 } 408 409 nlh = (struct nlmsghdr *) buf; 410 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ 411 continue; 412 413 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) { 414 if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { 415 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { 416 errno = EBADMSG; 417 return -1; 418 } 419 errno = -(*((int *)NLMSG_DATA(nlh))); 420 return (errno == 0) ? 0 : -1; 421 } 422 nlh = NLMSG_NEXT(nlh, len); 423 } 424 } while (1); 425 426 return -1; /* never here */ 427} 428 429static int 430nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 431{ 432 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); 433} 434 435static int 436nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family) 437{ 438 struct nfulnl_msg_config_cmd msg; 439 struct my_nfattr nfa; 440 441 msg.command = cmd; 442 443 nfa.data = &msg; 444 nfa.nfa_type = NFULA_CFG_CMD; 445 nfa.nfa_len = sizeof(msg); 446 447 return nflog_send_config_msg(handle, family, group_id, &nfa); 448} 449 450static int 451nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 452{ 453 struct nfulnl_msg_config_mode msg; 454 struct my_nfattr nfa; 455 456 msg.copy_range = htonl(copy_range); 457 msg.copy_mode = copy_mode; 458 459 nfa.data = &msg; 460 nfa.nfa_type = NFULA_CFG_MODE; 461 nfa.nfa_len = sizeof(msg); 462 463 return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 464} 465 466static int 467nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict) 468{ 469 struct nfqnl_msg_verdict_hdr msg; 470 struct my_nfattr nfa; 471 472 msg.id = htonl(id); 473 msg.verdict = htonl(verdict); 474 475 nfa.data = &msg; 476 nfa.nfa_type = NFQA_VERDICT_HDR; 477 nfa.nfa_len = sizeof(msg); 478 479 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa); 480} 481 482static int 483nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) 484{ 485 return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); 486} 487 488static int 489nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf) 490{ 491 struct nfqnl_msg_config_cmd msg; 492 struct my_nfattr nfa; 493 494 msg.command = cmd; 495 msg.pf = htons(pf); 496 497 nfa.data = &msg; 498 nfa.nfa_type = NFQA_CFG_CMD; 499 nfa.nfa_len = sizeof(msg); 500 501 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 502} 503 504static int 505nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) 506{ 507 struct nfqnl_msg_config_params msg; 508 struct my_nfattr nfa; 509 510 msg.copy_range = htonl(copy_range); 511 msg.copy_mode = copy_mode; 512 513 nfa.data = &msg; 514 nfa.nfa_type = NFQA_CFG_PARAMS; 515 nfa.nfa_len = sizeof(msg); 516 517 return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); 518} 519 520static int 521netfilter_activate(pcap_t* handle) 522{ 523 const char *dev = handle->opt.device; 524 unsigned short groups[32]; 525 int group_count = 0; 526 nftype_t type = OTHER; 527 int i; 528 529 if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { 530 dev += strlen(NFLOG_IFACE); 531 type = NFLOG; 532 533 } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) { 534 dev += strlen(NFQUEUE_IFACE); 535 type = NFQUEUE; 536 } 537 538 if (type != OTHER && *dev == ':') { 539 dev++; 540 while (*dev) { 541 long int group_id; 542 char *end_dev; 543 544 if (group_count == 32) { 545 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 546 "Maximum 32 netfilter groups! dev: %s", 547 handle->opt.device); 548 return PCAP_ERROR; 549 } 550 551 group_id = strtol(dev, &end_dev, 0); 552 if (end_dev != dev) { 553 if (group_id < 0 || group_id > 65535) { 554 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 555 "Netfilter group range from 0 to 65535 (got %ld)", 556 group_id); 557 return PCAP_ERROR; 558 } 559 560 groups[group_count++] = (unsigned short) group_id; 561 dev = end_dev; 562 } 563 if (*dev != ',') 564 break; 565 dev++; 566 } 567 } 568 569 if (type == OTHER || *dev) { 570 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 571 "Can't get netfilter group(s) index from %s", 572 handle->opt.device); 573 return PCAP_ERROR; 574 } 575 576 /* if no groups, add default: 0 */ 577 if (!group_count) { 578 groups[0] = 0; 579 group_count = 1; 580 } 581 582 /* 583 * Turn a negative snapshot value (invalid), a snapshot value of 584 * 0 (unspecified), or a value bigger than the normal maximum 585 * value, into the maximum allowed value. 586 * 587 * If some application really *needs* a bigger snapshot 588 * length, we should just increase MAXIMUM_SNAPLEN. 589 */ 590 if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN) 591 handle->snapshot = MAXIMUM_SNAPLEN; 592 593 /* Initialize some components of the pcap structure. */ 594 handle->bufsize = 128 + handle->snapshot; 595 handle->offset = 0; 596 handle->read_op = netfilter_read_linux; 597 handle->inject_op = netfilter_inject_linux; 598 handle->setfilter_op = install_bpf_program; /* no kernel filtering */ 599 handle->setdirection_op = NULL; 600 handle->set_datalink_op = netfilter_set_datalink; 601 handle->getnonblock_op = pcap_getnonblock_fd; 602 handle->setnonblock_op = pcap_setnonblock_fd; 603 handle->stats_op = netfilter_stats_linux; 604 605 /* Create netlink socket */ 606 handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 607 if (handle->fd < 0) { 608 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, 609 errno, "Can't create raw socket"); 610 return PCAP_ERROR; 611 } 612 613 if (type == NFLOG) { 614 handle->linktype = DLT_NFLOG; 615 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 616 if (handle->dlt_list != NULL) { 617 handle->dlt_list[0] = DLT_NFLOG; 618 handle->dlt_list[1] = DLT_IPV4; 619 handle->dlt_count = 2; 620 } 621 622 } else 623 handle->linktype = DLT_IPV4; 624 625 handle->buffer = malloc(handle->bufsize); 626 if (!handle->buffer) { 627 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, 628 errno, "Can't allocate dump buffer"); 629 goto close_fail; 630 } 631 632 if (type == NFLOG) { 633 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 634 pcap_fmt_errmsg_for_errno(handle->errbuf, 635 PCAP_ERRBUF_SIZE, errno, 636 "NFULNL_CFG_CMD_PF_UNBIND"); 637 goto close_fail; 638 } 639 640 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 641 pcap_fmt_errmsg_for_errno(handle->errbuf, 642 PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND"); 643 goto close_fail; 644 } 645 646 /* Bind socket to the nflog groups */ 647 for (i = 0; i < group_count; i++) { 648 if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 649 pcap_fmt_errmsg_for_errno(handle->errbuf, 650 PCAP_ERRBUF_SIZE, errno, 651 "Can't listen on group index"); 652 goto close_fail; 653 } 654 655 if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { 656 pcap_fmt_errmsg_for_errno(handle->errbuf, 657 PCAP_ERRBUF_SIZE, errno, 658 "NFULNL_COPY_PACKET"); 659 goto close_fail; 660 } 661 } 662 663 } else { 664 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { 665 pcap_fmt_errmsg_for_errno(handle->errbuf, 666 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND"); 667 goto close_fail; 668 } 669 670 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { 671 pcap_fmt_errmsg_for_errno(handle->errbuf, 672 PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND"); 673 goto close_fail; 674 } 675 676 /* Bind socket to the nfqueue groups */ 677 for (i = 0; i < group_count; i++) { 678 if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { 679 pcap_fmt_errmsg_for_errno(handle->errbuf, 680 PCAP_ERRBUF_SIZE, errno, 681 "Can't listen on group index"); 682 goto close_fail; 683 } 684 685 if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { 686 pcap_fmt_errmsg_for_errno(handle->errbuf, 687 PCAP_ERRBUF_SIZE, errno, 688 "NFQNL_COPY_PACKET"); 689 goto close_fail; 690 } 691 } 692 } 693 694 if (handle->opt.rfmon) { 695 /* 696 * Monitor mode doesn't apply to netfilter devices. 697 */ 698 pcap_cleanup_live_common(handle); 699 return PCAP_ERROR_RFMON_NOTSUP; 700 } 701 702 if (handle->opt.buffer_size != 0) { 703 /* 704 * Set the socket buffer size to the specified value. 705 */ 706 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { 707 pcap_fmt_errmsg_for_errno(handle->errbuf, 708 PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF"); 709 goto close_fail; 710 } 711 } 712 713 handle->selectable_fd = handle->fd; 714 return 0; 715 716close_fail: 717 pcap_cleanup_live_common(handle); 718 return PCAP_ERROR; 719} 720 721pcap_t * 722netfilter_create(const char *device, char *ebuf, int *is_ours) 723{ 724 const char *cp; 725 pcap_t *p; 726 727 /* Does this look like an netfilter device? */ 728 cp = strrchr(device, '/'); 729 if (cp == NULL) 730 cp = device; 731 732 /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */ 733 if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0) 734 cp += sizeof NFLOG_IFACE - 1; 735 else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0) 736 cp += sizeof NFQUEUE_IFACE - 1; 737 else { 738 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */ 739 *is_ours = 0; 740 return NULL; 741 } 742 743 /* 744 * Yes - is that either the end of the name, or is it followed 745 * by a colon? 746 */ 747 if (*cp != ':' && *cp != '\0') { 748 /* Nope */ 749 *is_ours = 0; 750 return NULL; 751 } 752 753 /* OK, it's probably ours. */ 754 *is_ours = 1; 755 756 p = PCAP_CREATE_COMMON(ebuf, struct pcap_netfilter); 757 if (p == NULL) 758 return (NULL); 759 760 p->activate_op = netfilter_activate; 761 return (p); 762} 763 764int 765netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str) 766{ 767 int sock; 768 769 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); 770 if (sock < 0) { 771 /* if netlink is not supported this is not fatal */ 772 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) 773 return 0; 774 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE, 775 errno, "Can't open netlink socket"); 776 return -1; 777 } 778 close(sock); 779 780 /* 781 * The notion of "connected" vs. "disconnected" doesn't apply. 782 * XXX - what about "up" and "running"? 783 */ 784 if (add_dev(devlistp, NFLOG_IFACE, 785 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, 786 "Linux netfilter log (NFLOG) interface", err_str) == NULL) 787 return -1; 788 if (add_dev(devlistp, NFQUEUE_IFACE, 789 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, 790 "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL) 791 return -1; 792 return 0; 793} 794