external/bsd/libpcap/dist/pcap-netfilter-linux.c

   1 /*      $NetBSD: pcap-netfilter-linux.c,v 1.3 2015/03/31 21:39:42 christos Exp $        */
   2
   3 /*
   4  * Copyright (c) 2011 Jakub Zawadzki
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  * notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  * notice, this list of conditions and the following disclaimer in the
  15  * documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote
  17  * products derived from this software without specific prior written
  18  * permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  23  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  24  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  30  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include <sys/cdefs.h>
  34 __RCSID("$NetBSD: pcap-netfilter-linux.c,v 1.3 2015/03/31 21:39:42 christos Exp $");
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include "config.h"
  38 #endif
  39
  40 #include "pcap-int.h"
  41
  42 #ifdef NEED_STRERROR_H
  43 #include "strerror.h"
  44 #endif
  45
  46 #include <errno.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49 #include <string.h>
  50 #include <sys/socket.h>
  51 #include <arpa/inet.h>
  52
  53 #include <time.h>
  54 #include <sys/time.h>
  55 #include <netinet/in.h>
  56 #include <linux/types.h>
  57
  58 #include <linux/netlink.h>
  59 #include <linux/netfilter.h>
  60 #include <linux/netfilter/nfnetlink.h>
  61 #include <linux/netfilter/nfnetlink_log.h>
  62 #include <linux/netfilter/nfnetlink_queue.h>
  63
  64 /* NOTE: if your program drops privilages after pcap_activate() it WON'T work with nfqueue.
  65  *       It took me quite some time to debug ;/
  66  *
  67  *       Sending any data to nfnetlink socket requires CAP_NET_ADMIN privilages,
  68  *       and in nfqueue we need to send verdict reply after recving packet.
  69  *
  70  *       In tcpdump you can disable dropping privilages with -Z root
  71  */
  72
  73 #include "pcap-netfilter-linux.h"
  74
  75 #define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg))))
  76
  77 #define NFLOG_IFACE "nflog"
  78 #define NFQUEUE_IFACE "nfqueue"
  79
  80 typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t;
  81
  82 /*
  83  * Private data for capturing on Linux netfilter sockets.
  84  */
  85 struct pcap_netfilter {
  86         u_int   packets_read;   /* count of packets read with recvfrom() */
  87 };
  88
  89 static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict);
  90
  91 static int
  92 netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
  93 {
  94         struct pcap_netfilter *handlep = handle->priv;
  95         const unsigned char *buf;
  96         int count = 0;
  97         int len;
  98
  99         /* ignore interrupt system call error */
 100         do {
 101                 len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
 102                 if (handle->break_loop) {
 103                         handle->break_loop = 0;
 104                         return -2;
 105                 }
 106         } while ((len == -1) && (errno == EINTR));
 107
 108         if (len < 0) {
 109                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno));
 110                 return -1;
 111         }
 112
 113         buf = handle->buffer;
 114         while (len >= NLMSG_SPACE(0)) {
 115                 const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf;
 116                 u_int32_t msg_len;
 117                 nftype_t type = OTHER;
 118
 119                 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) {
 120                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len);
 121                         return -1;
 122                 }
 123
 124                 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
 125                     NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
 126                         type = NFLOG;
 127                 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
 128                          NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
 129                         type = NFQUEUE;
 130
 131                 if (type != OTHER) {
 132                         const unsigned char *payload = NULL;
 133                         struct pcap_pkthdr pkth;
 134
 135                         const struct nfgenmsg *nfg = NULL;
 136                         int id = 0;
 137
 138                         if (handle->linktype != DLT_NFLOG) {
 139                                 const struct nfattr *payload_attr = NULL;
 140
 141                                 if (nlh->nlmsg_len < HDR_LENGTH) {
 142                                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
 143                                         return -1;
 144                                 }
 145
 146                                 nfg = NLMSG_DATA(nlh);
 147                                 if (nlh->nlmsg_len > HDR_LENGTH) {
 148                                         struct nfattr *attr = NFM_NFA(nfg);
 149                                         int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
 150
 151                                         while (NFA_OK(attr, attr_len)) {
 152                                                 if (type == NFQUEUE) {
 153                                                         switch (NFA_TYPE(attr)) {
 154                                                                 case NFQA_PACKET_HDR:
 155                                                                         {
 156                                                                                 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
 157
 158                                                                                 id = ntohl(pkt_hdr->packet_id);
 159                                                                                 break;
 160                                                                         }
 161                                                                 case NFQA_PAYLOAD:
 162                                                                         payload_attr = attr;
 163                                                                         break;
 164                                                         }
 165
 166                                                 } else if (type == NFLOG) {
 167                                                         switch (NFA_TYPE(attr)) {
 168                                                                 case NFULA_PAYLOAD:
 169                                                                         payload_attr = attr;
 170                                                                         break;
 171                                                         }
 172                                                 }
 173                                                 attr = NFA_NEXT(attr, attr_len);
 174                                         }
 175                                 }
 176
 177                                 if (payload_attr) {
 178                                         payload = NFA_DATA(payload_attr);
 179                                         pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
 180                                 }
 181
 182                         } else {
 183                                 payload = NLMSG_DATA(nlh);
 184                                 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
 185                         }
 186
 187                         if (payload) {
 188                                 /* pkth.caplen = min (payload_len, handle->snapshot); */
 189
 190                                 gettimeofday(&pkth.ts, NULL);
 191                                 if (handle->fcode.bf_insns == NULL ||
 192                                                 bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
 193                                 {
 194                                         handlep->packets_read++;
 195                                         callback(user, &pkth, payload);
 196                                         count++;
 197                                 }
 198                         }
 199
 200                         if (type == NFQUEUE) {
 201                                 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
 202                                 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
 203                                    so nfg is always initialized to NLMSG_DATA(nlh). */
 204                                 if (nfg != NULL)
 205                                         nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
 206                         }
 207                 }
 208
 209                 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
 210                 if (msg_len > len)
 211                         msg_len = len;
 212
 213                 len -= msg_len;
 214                 buf += msg_len;
 215         }
 216         return count;
 217 }
 218
 219 static int
 220 netfilter_set_datalink(pcap_t *handle, int dlt)
 221 {
 222         handle->linktype = dlt;
 223         return 0;
 224 }
 225
 226 static int
 227 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
 228 {
 229         struct pcap_netfilter *handlep = handle->priv;
 230
 231         stats->ps_recv = handlep->packets_read;
 232         stats->ps_drop = 0;
 233         stats->ps_ifdrop = 0;
 234         return 0;
 235 }
 236
 237 static int
 238 netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size)
 239 {
 240         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices");
 241         return (-1);
 242 }
 243
 244 struct my_nfattr {
 245         u_int16_t nfa_len;
 246         u_int16_t nfa_type;
 247         void *data;
 248 };
 249
 250 static int
 251 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)
 252 {
 253         char buf[1024] __attribute__ ((aligned));
 254
 255         struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
 256         struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
 257
 258         struct sockaddr_nl snl;
 259         static unsigned int seq_id;
 260
 261         if (!seq_id)
 262                 seq_id = time(NULL);
 263         ++seq_id;
 264
 265         nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
 266         nlh->nlmsg_type = msg_type;
 267         nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
 268         nlh->nlmsg_pid = 0;     /* to kernel */
 269         nlh->nlmsg_seq = seq_id;
 270
 271         nfg->nfgen_family = family;
 272         nfg->version = NFNETLINK_V0;
 273         nfg->res_id = htons(res_id);
 274
 275         if (mynfa) {
 276                 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
 277
 278                 nfa->nfa_type = mynfa->nfa_type;
 279                 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
 280                 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
 281                 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
 282         }
 283
 284         memset(&snl, 0, sizeof(snl));
 285         snl.nl_family = AF_NETLINK;
 286
 287         if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
 288                 return -1;
 289
 290         if (!ack)
 291                 return 0;
 292
 293         /* waiting for reply loop */
 294         do {
 295                 socklen_t addrlen = sizeof(snl);
 296                 int len;
 297
 298                 /* ignore interrupt system call error */
 299                 do {
 300                         len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
 301                 } while ((len == -1) && (errno == EINTR));
 302
 303                 if (len <= 0)
 304                         return len;
 305
 306                 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
 307                         errno = EINVAL;
 308                         return -1;
 309                 }
 310
 311                 nlh = (struct nlmsghdr *) buf;
 312                 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq)        /* if not from kernel or wrong sequence skip */
 313                         continue;
 314
 315                 while (len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) {
 316                         if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
 317                                 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
 318                                         errno = EBADMSG;
 319                                         return -1;
 320                                 }
 321                                 errno = -(*((int *)NLMSG_DATA(nlh)));
 322                                 return (errno == 0) ? 0 : -1;
 323                         }
 324                         nlh = NLMSG_NEXT(nlh, len);
 325                 }
 326         } while (1);
 327
 328         return -1; /* never here */
 329 }
 330
 331 static int
 332 nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 333 {
 334         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
 335 }
 336
 337 static int
 338 nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family)
 339 {
 340         struct nfulnl_msg_config_cmd msg;
 341         struct my_nfattr nfa;
 342
 343         msg.command = cmd;
 344
 345         nfa.data = &msg;
 346         nfa.nfa_type = NFULA_CFG_CMD;
 347         nfa.nfa_len = sizeof(msg);
 348
 349         return nflog_send_config_msg(handle, family, group_id, &nfa);
 350 }
 351
 352 static int
 353 nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 354 {
 355         struct nfulnl_msg_config_mode msg;
 356         struct my_nfattr nfa;
 357
 358         msg.copy_range = htonl(copy_range);
 359         msg.copy_mode = copy_mode;
 360
 361         nfa.data = &msg;
 362         nfa.nfa_type = NFULA_CFG_MODE;
 363         nfa.nfa_len = sizeof(msg);
 364
 365         return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 366 }
 367
 368 static int
 369 nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict)
 370 {
 371         struct nfqnl_msg_verdict_hdr msg;
 372         struct my_nfattr nfa;
 373
 374         msg.id = htonl(id);
 375         msg.verdict = htonl(verdict);
 376
 377         nfa.data = &msg;
 378         nfa.nfa_type = NFQA_VERDICT_HDR;
 379         nfa.nfa_len = sizeof(msg);
 380
 381         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
 382 }
 383
 384 static int
 385 nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 386 {
 387         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
 388 }
 389
 390 static int
 391 nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf)
 392 {
 393         struct nfqnl_msg_config_cmd msg;
 394         struct my_nfattr nfa;
 395
 396         msg.command = cmd;
 397         msg.pf = htons(pf);
 398
 399         nfa.data = &msg;
 400         nfa.nfa_type = NFQA_CFG_CMD;
 401         nfa.nfa_len = sizeof(msg);
 402
 403         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 404 }
 405
 406 static int
 407 nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 408 {
 409         struct nfqnl_msg_config_params msg;
 410         struct my_nfattr nfa;
 411
 412         msg.copy_range = htonl(copy_range);
 413         msg.copy_mode = copy_mode;
 414
 415         nfa.data = &msg;
 416         nfa.nfa_type = NFQA_CFG_PARAMS;
 417         nfa.nfa_len = sizeof(msg);
 418
 419         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 420 }
 421
 422 static int
 423 netfilter_activate(pcap_t* handle)
 424 {
 425         const char *dev = handle->opt.source;
 426         unsigned short groups[32];
 427         int group_count = 0;
 428         nftype_t type = OTHER;
 429         int i;
 430
 431         if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
 432                 dev += strlen(NFLOG_IFACE);
 433                 type = NFLOG;
 434
 435         } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
 436                 dev += strlen(NFQUEUE_IFACE);
 437                 type = NFQUEUE;
 438         }
 439
 440         if (type != OTHER && *dev == ':') {
 441                 dev++;
 442                 while (*dev) {
 443                         long int group_id;
 444                         char *end_dev;
 445
 446                         if (group_count == 32) {
 447                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 448                                                 "Maximum 32 netfilter groups! dev: %s",
 449                                                 handle->opt.source);
 450                                 return PCAP_ERROR;
 451                         }
 452
 453                         group_id = strtol(dev, &end_dev, 0);
 454                         if (end_dev != dev) {
 455                                 if (group_id < 0 || group_id > 65535) {
 456                                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 457                                                         "Netfilter group range from 0 to 65535 (got %ld)",
 458                                                         group_id);
 459                                         return PCAP_ERROR;
 460                                 }
 461
 462                                 groups[group_count++] = (unsigned short) group_id;
 463                                 dev = end_dev;
 464                         }
 465                         if (*dev != ',')
 466                                 break;
 467                         dev++;
 468                 }
 469         }
 470
 471         if (type == OTHER || *dev) {
 472                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 473                                 "Can't get netfilter group(s) index from %s",
 474                                 handle->opt.source);
 475                 return PCAP_ERROR;
 476         }
 477
 478         /* if no groups, add default: 0 */
 479         if (!group_count) {
 480                 groups[0] = 0;
 481                 group_count = 1;
 482         }
 483
 484         /* Initialize some components of the pcap structure. */
 485         handle->bufsize = 128 + handle->snapshot;
 486         handle->offset = 0;
 487         handle->read_op = netfilter_read_linux;
 488         handle->inject_op = netfilter_inject_linux;
 489         handle->setfilter_op = install_bpf_program; /* no kernel filtering */
 490         handle->setdirection_op = NULL;
 491         handle->set_datalink_op = netfilter_set_datalink;
 492         handle->getnonblock_op = pcap_getnonblock_fd;
 493         handle->setnonblock_op = pcap_setnonblock_fd;
 494         handle->stats_op = netfilter_stats_linux;
 495
 496         /* Create netlink socket */
 497         handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 498         if (handle->fd < 0) {
 499                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno));
 500                 return PCAP_ERROR;
 501         }
 502
 503         if (type == NFLOG) {
 504                 handle->linktype = DLT_NFLOG;
 505                 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 506                 if (handle->dlt_list != NULL) {
 507                         handle->dlt_list[0] = DLT_NFLOG;
 508                         handle->dlt_list[1] = DLT_IPV4;
 509                         handle->dlt_count = 2;
 510                 }
 511
 512         } else
 513                 handle->linktype = DLT_IPV4;
 514
 515         handle->buffer = malloc(handle->bufsize);
 516         if (!handle->buffer) {
 517                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno));
 518                 goto close_fail;
 519         }
 520
 521         if (type == NFLOG) {
 522                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 523                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
 524                         goto close_fail;
 525                 }
 526
 527                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 528                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
 529                         goto close_fail;
 530                 }
 531
 532                 /* Bind socket to the nflog groups */
 533                 for (i = 0; i < group_count; i++) {
 534                         if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 535                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
 536                                 goto close_fail;
 537                         }
 538
 539                         if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
 540                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno));
 541                                 goto close_fail;
 542                         }
 543                 }
 544
 545         } else {
 546                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 547                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
 548                         goto close_fail;
 549                 }
 550
 551                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 552                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
 553                         goto close_fail;
 554                 }
 555
 556                 /* Bind socket to the nfqueue groups */
 557                 for (i = 0; i < group_count; i++) {
 558                         if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 559                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
 560                                 goto close_fail;
 561                         }
 562
 563                         if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
 564                                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno));
 565                                 goto close_fail;
 566                         }
 567                 }
 568         }
 569
 570         if (handle->opt.rfmon) {
 571                 /*
 572                  * Monitor mode doesn't apply to netfilter devices.
 573                  */
 574                 pcap_cleanup_live_common(handle);
 575                 return PCAP_ERROR_RFMON_NOTSUP;
 576         }
 577
 578         if (handle->opt.buffer_size != 0) {
 579                 /*
 580                  * Set the socket buffer size to the specified value.
 581                  */
 582                 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
 583                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno));
 584                         goto close_fail;
 585                 }
 586         }
 587
 588         handle->selectable_fd = handle->fd;
 589         return 0;
 590
 591 close_fail:
 592         pcap_cleanup_live_common(handle);
 593         return PCAP_ERROR;
 594 }
 595
 596 pcap_t *
 597 netfilter_create(const char *device, char *ebuf, int *is_ours)
 598 {
 599         const char *cp;
 600         pcap_t *p;
 601
 602         /* Does this look like an netfilter device? */
 603         cp = strrchr(device, '/');
 604         if (cp == NULL)
 605                 cp = device;
 606
 607         /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
 608         if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
 609                 cp += sizeof NFLOG_IFACE - 1;
 610         else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
 611                 cp += sizeof NFQUEUE_IFACE - 1;
 612         else {
 613                 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
 614                 *is_ours = 0;
 615                 return NULL;
 616         }
 617
 618         /*
 619          * Yes - is that either the end of the name, or is it followed
 620          * by a colon?
 621          */
 622         if (*cp != ':' && *cp != '\0') {
 623                 /* Nope */
 624                 *is_ours = 0;
 625                 return NULL;
 626         }
 627
 628         /* OK, it's probably ours. */
 629         *is_ours = 1;
 630
 631         p = pcap_create_common(device, ebuf, sizeof (struct pcap_netfilter));
 632         if (p == NULL)
 633                 return (NULL);
 634
 635         p->activate_op = netfilter_activate;
 636         return (p);
 637 }
 638
 639 int
 640 netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str)
 641 {
 642         int sock;
 643
 644         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 645         if (sock < 0) {
 646                 /* if netlink is not supported this is not fatal */
 647                 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
 648                         return 0;
 649                 snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s",
 650                         errno, pcap_strerror(errno));
 651                 return -1;
 652         }
 653         close(sock);
 654
 655         if (pcap_add_if(alldevsp, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0)
 656                 return -1;
 657         if (pcap_add_if(alldevsp, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0)
 658                 return -1;
 659         return 0;
 660 }