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