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 static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict);
  78
  79 static int
  80 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
  81 {
  82         const unsigned char *buf;
  83         int count = 0;
  84         int len;
  85
  86         /* ignore interrupt system call error */
  87         do {
  88                 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
  89                 if (handle->break_loop) {
  90                         handle->break_loop = 0;
  91                         return -2;
  92                 }
  93         } while ((len == -1) && (errno == EINTR));
  94
  95         if (len < 0) {
  96                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno));
  97                 return -1;
  98         }
  99
 100         buf = handle->buffer;
 101         while (len >= NLMSG_SPACE(0)) {
 102                 const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf;
 103                 u_int32_t msg_len;
 104                 nftype_t type = OTHER;
 105
 106                 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) {
 107                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len);
 108                         return -1;
 109                 }
 110
 111                 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
 112                         NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
 113                                 type = NFLOG;
 114
 115                 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
 116                         NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
 117                                 type = NFQUEUE;
 118
 119                 if (type != OTHER) {
 120                         const unsigned char *payload = NULL;
 121                         struct pcap_pkthdr pkth;
 122
 123                         const struct nfgenmsg *nfg;
 124                         int id = 0;
 125
 126                         if (handle->linktype != DLT_NFLOG) {
 127                                 const struct nfattr *payload_attr = NULL;
 128
 129                                 if (nlh->nlmsg_len < HDR_LENGTH) {
 130                                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
 131                                         return -1;
 132                                 }
 133
 134                                 nfg = NLMSG_DATA(nlh);
 135                                 if (nlh->nlmsg_len > HDR_LENGTH) {
 136                                         struct nfattr *attr = NFM_NFA(nfg);
 137                                         int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
 138
 139                                         while (NFA_OK(attr, attr_len)) {
 140                                                 if (type == NFQUEUE) {
 141                                                         switch (NFA_TYPE(attr)) {
 142                                                                 case NFQA_PACKET_HDR:
 143                                                                         {
 144                                                                                 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
 145
 146                                                                                 id = ntohl(pkt_hdr->packet_id);
 147                                                                                 break;
 148                                                                         }
 149                                                                 case NFQA_PAYLOAD:
 150                                                                         payload_attr = attr;
 151                                                                         break;
 152                                                         }
 153
 154                                                 } else if (type == NFLOG) {
 155                                                         switch (NFA_TYPE(attr)) {
 156                                                                 case NFULA_PAYLOAD:
 157                                                                         payload_attr = attr;
 158                                                                         break;
 159                                                         }
 160                                                 }
 161                                                 attr = NFA_NEXT(attr, attr_len);
 162                                         }
 163                                 }
 164
 165                                 if (payload_attr) {
 166                                         payload = NFA_DATA(payload_attr);
 167                                         pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
 168                                 }
 169
 170                         } else {
 171                                 payload = NLMSG_DATA(nlh);
 172                                 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
 173                         }
 174
 175                         if (payload) {
 176                                 /* pkth.caplen = min (payload_len, handle->snapshot); */
 177
 178                                 gettimeofday(&pkth.ts, NULL);
 179                                 if (handle->fcode.bf_insns == NULL ||
 180                                                 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
 181                                 {
 182                                         handle->md.packets_read++;
 183                                         callback(user, &pkth, payload);
 184                                         count++;
 185                                 }
 186                         }
 187
 188                         if (type == NFQUEUE) {
 189                                 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
 190                                 nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
 191                         }
 192                 }
 193
 194                 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
 195                 if (msg_len > len)
 196                         msg_len = len;
 197
 198                 len -= msg_len;
 199                 buf += msg_len;
 200         }
 201         return count;
 202 }
 203
 204 static int
 205 netfilter_set_datalink(pcap_t *handle, int dlt)
 206 {
 207         handle->linktype = dlt;
 208         return 0;
 209 }
 210
 211 static int
 212 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
 213 {
 214         stats->ps_recv = handle->md.packets_read;
 215         stats->ps_drop = 0;
 216         stats->ps_ifdrop = 0;
 217         return 0;
 218 }
 219
 220 static int
 221 netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size)
 222 {
 223         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices");
 224         return (-1);
 225 }
 226
 227 struct my_nfattr {
 228         u_int16_t nfa_len;
 229         u_int16_t nfa_type;
 230         void *data;
 231 };
 232
 233 static int
 234 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)
 235 {
 236         char buf[1024] __attribute__ ((aligned));
 237
 238         struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
 239         struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
 240
 241         struct sockaddr_nl snl;
 242         static unsigned int seq_id;
 243
 244         if (!seq_id)
 245                 seq_id = time(NULL);
 246         ++seq_id;
 247
 248         nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
 249         nlh->nlmsg_type = msg_type;
 250         nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
 251         nlh->nlmsg_pid = 0;     /* to kernel */
 252         nlh->nlmsg_seq = seq_id;
 253
 254         nfg->nfgen_family = family;
 255         nfg->version = NFNETLINK_V0;
 256         nfg->res_id = htons(res_id);
 257
 258         if (mynfa) {
 259                 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
 260
 261                 nfa->nfa_type = mynfa->nfa_type;
 262                 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
 263                 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
 264                 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
 265         }
 266
 267         memset(&snl, 0, sizeof(snl));
 268         snl.nl_family = AF_NETLINK;
 269
 270         if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
 271                 return -1;
 272
 273         if (!ack)
 274                 return 0;
 275
 276         /* waiting for reply loop */
 277         do {
 278                 socklen_t addrlen = sizeof(snl);
 279                 int len;
 280
 281                 /* ignore interrupt system call error */
 282                 do {
 283                         len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
 284                 } while ((len == -1) && (errno == EINTR));
 285
 286                 if (len <= 0)
 287                         return len;
 288
 289                 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
 290                         errno = EINVAL;
 291                         return -1;
 292                 }
 293
 294                 nlh = (struct nlmsghdr *) buf;
 295                 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq)        /* if not from kernel or wrong sequence skip */
 296                         continue;
 297
 298                 while (len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) {
 299                         if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
 300                                 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
 301                                         errno = EBADMSG;
 302                                         return -1;
 303                                 }
 304                                 errno = -(*((int *)NLMSG_DATA(nlh)));
 305                                 return (errno == 0) ? 0 : -1;
 306                         }
 307                         nlh = NLMSG_NEXT(nlh, len);
 308                 }
 309         } while (1);
 310
 311         return -1; /* never here */
 312 }
 313
 314 static int
 315 nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 316 {
 317         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
 318 }
 319
 320 static int
 321 nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family)
 322 {
 323         struct nfulnl_msg_config_cmd msg;
 324         struct my_nfattr nfa;
 325
 326         msg.command = cmd;
 327
 328         nfa.data = &msg;
 329         nfa.nfa_type = NFULA_CFG_CMD;
 330         nfa.nfa_len = sizeof(msg);
 331
 332         return nflog_send_config_msg(handle, family, group_id, &nfa);
 333 }
 334
 335 static int
 336 nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 337 {
 338         struct nfulnl_msg_config_mode msg;
 339         struct my_nfattr nfa;
 340
 341         msg.copy_range = htonl(copy_range);
 342         msg.copy_mode = copy_mode;
 343
 344         nfa.data = &msg;
 345         nfa.nfa_type = NFULA_CFG_MODE;
 346         nfa.nfa_len = sizeof(msg);
 347
 348         return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 349 }
 350
 351 static int
 352 nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict)
 353 {
 354         struct nfqnl_msg_verdict_hdr msg;
 355         struct my_nfattr nfa;
 356
 357         msg.id = htonl(id);
 358         msg.verdict = htonl(verdict);
 359
 360         nfa.data = &msg;
 361         nfa.nfa_type = NFQA_VERDICT_HDR;
 362         nfa.nfa_len = sizeof(msg);
 363
 364         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
 365 }
 366
 367 static int
 368 nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 369 {
 370         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
 371 }
 372
 373 static int
 374 nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf)
 375 {
 376         struct nfqnl_msg_config_cmd msg;
 377         struct my_nfattr nfa;
 378
 379         msg.command = cmd;
 380         msg.pf = htons(pf);
 381
 382         nfa.data = &msg;
 383         nfa.nfa_type = NFQA_CFG_CMD;
 384         nfa.nfa_len = sizeof(msg);
 385
 386         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 387 }
 388
 389 static int
 390 nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 391 {
 392         struct nfqnl_msg_config_params msg;
 393         struct my_nfattr nfa;
 394
 395         msg.copy_range = htonl(copy_range);
 396         msg.copy_mode = copy_mode;
 397
 398         nfa.data = &msg;
 399         nfa.nfa_type = NFQA_CFG_PARAMS;
 400         nfa.nfa_len = sizeof(msg);
 401
 402         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 403 }
 404
 405 static int
 406 netfilter_activate(pcap_t* handle)
 407 {
 408         const char *dev = handle->opt.source;
 409         unsigned short groups[32];
 410         int group_count = 0;
 411         nftype_t type = OTHER;
 412         int i;
 413
 414         if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
 415                 dev += strlen(NFLOG_IFACE);
 416                 type = NFLOG;
 417
 418         } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
 419                 dev += strlen(NFQUEUE_IFACE);
 420                 type = NFQUEUE;
 421         }
 422
 423         if (type != OTHER && *dev == ':') {
 424                 dev++;
 425                 while (*dev) {
 426                         long int group_id;
 427                         char *end_dev;
 428
 429                         if (group_count == 32) {
 430                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 431                                                 "Maximum 32 netfilter groups! dev: %s",
 432                                                 handle->opt.source);
 433                                 return PCAP_ERROR;
 434                         }
 435
 436                         group_id = strtol(dev, &end_dev, 0);
 437                         if (end_dev != dev) {
 438                                 if (group_id < 0 || group_id > 65535) {
 439                                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 440                                                         "Netfilter group range from 0 to 65535 (got %ld)",
 441                                                         group_id);
 442                                         return PCAP_ERROR;
 443                                 }
 444
 445                                 groups[group_count++] = (unsigned short) group_id;
 446                                 dev = end_dev;
 447                         }
 448                         if (*dev != ',')
 449                                 break;
 450                         dev++;
 451                 }
 452         }
 453
 454         if (type == OTHER || *dev) {
 455                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 456                                 "Can't get netfilter group(s) index from %s",
 457                                 handle->opt.source);
 458                 return PCAP_ERROR;
 459         }
 460
 461         /* if no groups, add default: 0 */
 462         if (!group_count) {
 463                 groups[0] = 0;
 464                 group_count = 1;
 465         }
 466
 467         /* Initialize some components of the pcap structure. */
 468         handle->bufsize = 128 + handle->snapshot;
 469         handle->offset = 0;
 470         handle->read_op = netfilter_read_linux;
 471         handle->inject_op = netfilter_inject_linux;
 472         handle->setfilter_op = install_bpf_program; /* no kernel filtering */
 473         handle->setdirection_op = NULL;
 474         handle->set_datalink_op = NULL;
 475         handle->set_datalink_op = netfilter_set_datalink;
 476         handle->getnonblock_op = pcap_getnonblock_fd;
 477         handle->setnonblock_op = pcap_setnonblock_fd;
 478         handle->stats_op = netfilter_stats_linux;
 479
 480         /* Create netlink socket */
 481         handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 482         if (handle->fd < 0) {
 483                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno));
 484                 return PCAP_ERROR;
 485         }
 486
 487         if (type == NFLOG) {
 488                 handle->linktype = DLT_NFLOG;
 489                 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 490                 if (handle->dlt_list != NULL) {
 491                         handle->dlt_list[0] = DLT_NFLOG;
 492                         handle->dlt_list[1] = DLT_IPV4;
 493                         handle->dlt_count = 2;
 494                 }
 495
 496         } else
 497                 handle->linktype = DLT_IPV4;
 498
 499         handle->buffer = malloc(handle->bufsize);
 500         if (!handle->buffer) {
 501                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno));
 502                 goto close_fail;
 503         }
 504
 505         if (type == NFLOG) {
 506                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 507                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
 508                         goto close_fail;
 509                 }
 510
 511                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 512                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
 513                         goto close_fail;
 514                 }
 515
 516                 /* Bind socket to the nflog groups */
 517                 for (i = 0; i < group_count; i++) {
 518                         if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 519                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
 520                                 goto close_fail;
 521                         }
 522
 523                         if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
 524                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno));
 525                                 goto close_fail;
 526                         }
 527                 }
 528
 529         } else {
 530                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 531                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
 532                         goto close_fail;
 533                 }
 534
 535                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 536                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
 537                         goto close_fail;
 538                 }
 539
 540                 /* Bind socket to the nfqueue groups */
 541                 for (i = 0; i < group_count; i++) {
 542                         if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 543                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
 544                                 goto close_fail;
 545                         }
 546
 547                         if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
 548                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno));
 549                                 goto close_fail;
 550                         }
 551                 }
 552         }
 553
 554         if (handle->opt.rfmon) {
 555                 /*
 556                  * Monitor mode doesn't apply to netfilter devices.
 557                  */
 558                 pcap_cleanup_live_common(handle);
 559                 return PCAP_ERROR_RFMON_NOTSUP;
 560         }
 561
 562         if (handle->opt.buffer_size != 0) {
 563                 /*
 564                  * Set the socket buffer size to the specified value.
 565                  */
 566                 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
 567                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno));
 568                         goto close_fail;
 569                 }
 570         }
 571
 572         handle->selectable_fd = handle->fd;
 573         return 0;
 574
 575 close_fail:
 576         pcap_cleanup_live_common(handle);
 577         return PCAP_ERROR;
 578 }
 579
 580 pcap_t *
 581 netfilter_create(const char *device, char *ebuf, int *is_ours)
 582 {
 583         const char *cp;
 584         pcap_t *p;
 585
 586         /* Does this look like an netfilter device? */
 587         cp = strrchr(device, '/');
 588         if (cp == NULL)
 589                 cp = device;
 590
 591         /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
 592         if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
 593                 cp += sizeof NFLOG_IFACE - 1;
 594         else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
 595                 cp += sizeof NFQUEUE_IFACE - 1;
 596         else {
 597                 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
 598                 *is_ours = 0;
 599                 return NULL;
 600         }
 601
 602         /*
 603          * Yes - is that either the end of the name, or is it followed
 604          * by a colon?
 605          */
 606         if (*cp != ':' && *cp != '\0') {
 607                 /* Nope */
 608                 *is_ours = 0;
 609                 return NULL;
 610         }
 611
 612         /* OK, it's probably ours. */
 613         *is_ours = 1;
 614
 615         p = pcap_create_common(device, ebuf);
 616         if (p == NULL)
 617                 return (NULL);
 618
 619         p->activate_op = netfilter_activate;
 620         return (p);
 621 }
 622
 623 int
 624 netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str)
 625 {
 626         pcap_if_t *found_dev = *alldevsp;
 627         int sock;
 628
 629         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 630         if (sock < 0) {
 631                 /* if netlink is not supported this is not fatal */
 632                 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
 633                         return 0;
 634                 snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s",
 635                         errno, pcap_strerror(errno));
 636                 return -1;
 637         }
 638         close(sock);
 639
 640         if (pcap_add_if(&found_dev, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0)
 641                 return -1;
 642         if (pcap_add_if(&found_dev, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0)
 643                 return -1;
 644         return 0;
 645 }