The Tcpdump Group git mirrors - libpcap/blob - pcap-netfilter-linux.c

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