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