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