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         u_int   packets_nobufs; /* ENOBUFS counter */
  83 };
  84
  85 static int nfqueue_send_verdict(const pcap_t *handle, uint16_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         register u_char *bp, *ep;
  93         int count = 0;
  94         ssize_t len;
  95
  96         /*
  97          * Has "pcap_breakloop()" been called?
  98          */
  99         if (handle->break_loop) {
 100                 /*
 101                  * Yes - clear the flag that indicates that it
 102                  * has, and return PCAP_ERROR_BREAK to indicate
 103                  * that we were told to break out of the loop.
 104                  */
 105                 handle->break_loop = 0;
 106                 return PCAP_ERROR_BREAK;
 107         }
 108         len = handle->cc;
 109         if (len == 0) {
 110                 /*
 111                  * The buffer is empty; refill it.
 112                  *
 113                  * We ignore EINTR, as that might just be due to a signal
 114                  * being delivered - if the signal should interrupt the
 115                  * loop, the signal handler should call pcap_breakloop()
 116                  * to set handle->break_loop (we ignore it on other
 117                  * platforms as well).
 118                  */
 119                 do {
 120                         len = recv(handle->fd, handle->buffer, handle->bufsize, 0);
 121                         if (handle->break_loop) {
 122                                 handle->break_loop = 0;
 123                                 return PCAP_ERROR_BREAK;
 124                         }
 125                         if (errno == ENOBUFS)
 126                                 handlep->packets_nobufs++;
 127                 } while ((len == -1) && (errno == EINTR || errno == ENOBUFS));
 128
 129                 if (len < 0) {
 130                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 131                             PCAP_ERRBUF_SIZE, errno, "Can't receive packet");
 132                         return PCAP_ERROR;
 133                 }
 134
 135                 bp = (unsigned char *)handle->buffer;
 136         } else
 137                 bp = handle->bp;
 138         ep = bp + len;
 139         while (bp < ep) {
 140                 const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp;
 141                 uint32_t msg_len;
 142                 nftype_t type = OTHER;
 143                 /*
 144                  * Has "pcap_breakloop()" been called?
 145                  * If so, return immediately - if we haven't read any
 146                  * packets, clear the flag and return PCAP_ERROR_BREAK
 147                  * to indicate that we were told to break out of the loop,
 148                  * otherwise leave the flag set, so that the *next* call
 149                  * will break out of the loop without having read any
 150                  * packets, and return the number of packets we've
 151                  * processed so far.
 152                  */
 153                 if (handle->break_loop) {
 154                         handle->bp = bp;
 155                         handle->cc = (int)(ep - bp);
 156                         if (count == 0) {
 157                                 handle->break_loop = 0;
 158                                 return PCAP_ERROR_BREAK;
 159                         } else
 160                                 return count;
 161                 }
 162                 if (ep - bp < NLMSG_SPACE(0)) {
 163                         /*
 164                          * There's less than one netlink message left
 165                          * in the buffer.  Give up.
 166                          */
 167                         break;
 168                 }
 169
 170                 if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) {
 171                         pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len);
 172                         return -1;
 173                 }
 174
 175                 if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
 176                     NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
 177                         type = NFLOG;
 178                 else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
 179                          NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
 180                         type = NFQUEUE;
 181
 182                 if (type != OTHER) {
 183                         const unsigned char *payload = NULL;
 184                         struct pcap_pkthdr pkth;
 185
 186                         const struct nfgenmsg *nfg = NULL;
 187                         int id = 0;
 188
 189                         if (handle->linktype != DLT_NFLOG) {
 190                                 const struct nfattr *payload_attr = NULL;
 191
 192                                 if (nlh->nlmsg_len < HDR_LENGTH) {
 193                                         pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len);
 194                                         return -1;
 195                                 }
 196
 197                                 nfg = NLMSG_DATA(nlh);
 198                                 if (nlh->nlmsg_len > HDR_LENGTH) {
 199                                         struct nfattr *attr = NFM_NFA(nfg);
 200                                         int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
 201
 202                                         while (NFA_OK(attr, attr_len)) {
 203                                                 if (type == NFQUEUE) {
 204                                                         switch (NFA_TYPE(attr)) {
 205                                                                 case NFQA_PACKET_HDR:
 206                                                                         {
 207                                                                                 const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
 208
 209                                                                                 id = ntohl(pkt_hdr->packet_id);
 210                                                                                 break;
 211                                                                         }
 212                                                                 case NFQA_PAYLOAD:
 213                                                                         payload_attr = attr;
 214                                                                         break;
 215                                                         }
 216
 217                                                 } else if (type == NFLOG) {
 218                                                         switch (NFA_TYPE(attr)) {
 219                                                                 case NFULA_PAYLOAD:
 220                                                                         payload_attr = attr;
 221                                                                         break;
 222                                                         }
 223                                                 }
 224                                                 attr = NFA_NEXT(attr, attr_len);
 225                                         }
 226                                 }
 227
 228                                 if (payload_attr) {
 229                                         payload = NFA_DATA(payload_attr);
 230                                         pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr);
 231                                 }
 232
 233                         } else {
 234                                 payload = NLMSG_DATA(nlh);
 235                                 pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr));
 236                         }
 237
 238                         if (payload) {
 239                                 /* pkth.caplen = min (payload_len, handle->snapshot); */
 240
 241                                 gettimeofday(&pkth.ts, NULL);
 242                                 if (handle->fcode.bf_insns == NULL ||
 243                                                 pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
 244                                 {
 245                                         handlep->packets_read++;
 246                                         callback(user, &pkth, payload);
 247                                         count++;
 248                                 }
 249                         }
 250
 251                         if (type == NFQUEUE) {
 252                                 /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
 253                                 /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG,
 254                                    so nfg is always initialized to NLMSG_DATA(nlh). */
 255                                 if (nfg != NULL)
 256                                         nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
 257                         }
 258                 }
 259
 260                 msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
 261                 /*
 262                  * If the message length would run past the end of the
 263                  * buffer, truncate it to the remaining space in the
 264                  * buffer.
 265                  */
 266                 if (msg_len > ep - bp)
 267                         msg_len = (uint32_t)(ep - bp);
 268
 269                 bp += msg_len;
 270                 if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
 271                         handle->bp = bp;
 272                         handle->cc = (int)(ep - bp);
 273                         if (handle->cc < 0)
 274                                 handle->cc = 0;
 275                         return count;
 276                 }
 277         }
 278
 279         handle->cc = 0;
 280         return count;
 281 }
 282
 283 static int
 284 netfilter_set_datalink(pcap_t *handle, int dlt)
 285 {
 286         handle->linktype = dlt;
 287         return 0;
 288 }
 289
 290 static int
 291 netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats)
 292 {
 293         struct pcap_netfilter *handlep = handle->priv;
 294
 295         stats->ps_recv = handlep->packets_read;
 296         stats->ps_drop = handlep->packets_nobufs;
 297         stats->ps_ifdrop = 0;
 298         return 0;
 299 }
 300
 301 static int
 302 netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_)
 303 {
 304         pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices");
 305         return (-1);
 306 }
 307
 308 struct my_nfattr {
 309         uint16_t nfa_len;
 310         uint16_t nfa_type;
 311         void *data;
 312 };
 313
 314 static int
 315 netfilter_send_config_msg(const pcap_t *handle, uint16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa)
 316 {
 317         char buf[1024] __attribute__ ((aligned));
 318
 319         struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
 320         struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
 321
 322         struct sockaddr_nl snl;
 323         static unsigned int seq_id;
 324
 325         if (!seq_id)
 326                 seq_id = time(NULL);
 327         ++seq_id;
 328
 329         nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
 330         nlh->nlmsg_type = msg_type;
 331         nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
 332         nlh->nlmsg_pid = 0;     /* to kernel */
 333         nlh->nlmsg_seq = seq_id;
 334
 335         nfg->nfgen_family = family;
 336         nfg->version = NFNETLINK_V0;
 337         nfg->res_id = htons(res_id);
 338
 339         if (mynfa) {
 340                 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
 341
 342                 nfa->nfa_type = mynfa->nfa_type;
 343                 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
 344                 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
 345                 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
 346         }
 347
 348         memset(&snl, 0, sizeof(snl));
 349         snl.nl_family = AF_NETLINK;
 350
 351         if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
 352                 return -1;
 353
 354         if (!ack)
 355                 return 0;
 356
 357         /* waiting for reply loop */
 358         do {
 359                 socklen_t addrlen = sizeof(snl);
 360                 int len;
 361
 362                 /* ignore interrupt system call error */
 363                 do {
 364                         /*
 365                          * The buffer is not so big that its size won't
 366                          * fit into an int.
 367                          */
 368                         len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
 369                 } while ((len == -1) && (errno == EINTR));
 370
 371                 if (len <= 0)
 372                         return len;
 373
 374                 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
 375                         errno = EINVAL;
 376                         return -1;
 377                 }
 378
 379                 nlh = (struct nlmsghdr *) buf;
 380                 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq)        /* if not from kernel or wrong sequence skip */
 381                         continue;
 382
 383                 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
 384                         if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
 385                                 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
 386                                         errno = EBADMSG;
 387                                         return -1;
 388                                 }
 389                                 errno = -(*((int *)NLMSG_DATA(nlh)));
 390                                 return (errno == 0) ? 0 : -1;
 391                         }
 392                         nlh = NLMSG_NEXT(nlh, len);
 393                 }
 394         } while (1);
 395
 396         return -1; /* never here */
 397 }
 398
 399 static int
 400 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 401 {
 402         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
 403 }
 404
 405 static int
 406 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
 407 {
 408         struct nfulnl_msg_config_cmd msg;
 409         struct my_nfattr nfa;
 410
 411         msg.command = cmd;
 412
 413         nfa.data = &msg;
 414         nfa.nfa_type = NFULA_CFG_CMD;
 415         nfa.nfa_len = sizeof(msg);
 416
 417         return nflog_send_config_msg(handle, family, group_id, &nfa);
 418 }
 419
 420 static int
 421 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 422 {
 423         struct nfulnl_msg_config_mode msg;
 424         struct my_nfattr nfa;
 425
 426         msg.copy_range = htonl(copy_range);
 427         msg.copy_mode = copy_mode;
 428
 429         nfa.data = &msg;
 430         nfa.nfa_type = NFULA_CFG_MODE;
 431         nfa.nfa_len = sizeof(msg);
 432
 433         return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 434 }
 435
 436 static int
 437 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
 438 {
 439         struct nfqnl_msg_verdict_hdr msg;
 440         struct my_nfattr nfa;
 441
 442         msg.id = htonl(id);
 443         msg.verdict = htonl(verdict);
 444
 445         nfa.data = &msg;
 446         nfa.nfa_type = NFQA_VERDICT_HDR;
 447         nfa.nfa_len = sizeof(msg);
 448
 449         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
 450 }
 451
 452 static int
 453 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 454 {
 455         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
 456 }
 457
 458 static int
 459 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
 460 {
 461         struct nfqnl_msg_config_cmd msg;
 462         struct my_nfattr nfa;
 463
 464         msg.command = cmd;
 465         msg.pf = htons(pf);
 466
 467         nfa.data = &msg;
 468         nfa.nfa_type = NFQA_CFG_CMD;
 469         nfa.nfa_len = sizeof(msg);
 470
 471         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 472 }
 473
 474 static int
 475 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 476 {
 477         struct nfqnl_msg_config_params msg;
 478         struct my_nfattr nfa;
 479
 480         msg.copy_range = htonl(copy_range);
 481         msg.copy_mode = copy_mode;
 482
 483         nfa.data = &msg;
 484         nfa.nfa_type = NFQA_CFG_PARAMS;
 485         nfa.nfa_len = sizeof(msg);
 486
 487         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 488 }
 489
 490 static int
 491 netfilter_activate(pcap_t* handle)
 492 {
 493         const char *dev = handle->opt.device;
 494         unsigned short groups[32];
 495         int group_count = 0;
 496         nftype_t type = OTHER;
 497         int i;
 498
 499         if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
 500                 dev += strlen(NFLOG_IFACE);
 501                 type = NFLOG;
 502
 503         } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
 504                 dev += strlen(NFQUEUE_IFACE);
 505                 type = NFQUEUE;
 506         }
 507
 508         if (type != OTHER && *dev == ':') {
 509                 dev++;
 510                 while (*dev) {
 511                         long int group_id;
 512                         char *end_dev;
 513
 514                         if (group_count == 32) {
 515                                 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 516                                                 "Maximum 32 netfilter groups! dev: %s",
 517                                                 handle->opt.device);
 518                                 return PCAP_ERROR;
 519                         }
 520
 521                         group_id = strtol(dev, &end_dev, 0);
 522                         if (end_dev != dev) {
 523                                 if (group_id < 0 || group_id > 65535) {
 524                                         pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 525                                                         "Netfilter group range from 0 to 65535 (got %ld)",
 526                                                         group_id);
 527                                         return PCAP_ERROR;
 528                                 }
 529
 530                                 groups[group_count++] = (unsigned short) group_id;
 531                                 dev = end_dev;
 532                         }
 533                         if (*dev != ',')
 534                                 break;
 535                         dev++;
 536                 }
 537         }
 538
 539         if (type == OTHER || *dev) {
 540                 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 541                                 "Can't get netfilter group(s) index from %s",
 542                                 handle->opt.device);
 543                 return PCAP_ERROR;
 544         }
 545
 546         /* if no groups, add default: 0 */
 547         if (!group_count) {
 548                 groups[0] = 0;
 549                 group_count = 1;
 550         }
 551
 552         /*
 553          * Turn a negative snapshot value (invalid), a snapshot value of
 554          * 0 (unspecified), or a value bigger than the normal maximum
 555          * value, into the maximum allowed value.
 556          *
 557          * If some application really *needs* a bigger snapshot
 558          * length, we should just increase MAXIMUM_SNAPLEN.
 559          */
 560         if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
 561                 handle->snapshot = MAXIMUM_SNAPLEN;
 562
 563         /* Initialize some components of the pcap structure. */
 564         handle->bufsize = 128 + handle->snapshot;
 565         handle->offset = 0;
 566         handle->read_op = netfilter_read_linux;
 567         handle->inject_op = netfilter_inject_linux;
 568         handle->setfilter_op = install_bpf_program; /* no kernel filtering */
 569         handle->setdirection_op = NULL;
 570         handle->set_datalink_op = netfilter_set_datalink;
 571         handle->getnonblock_op = pcap_getnonblock_fd;
 572         handle->setnonblock_op = pcap_setnonblock_fd;
 573         handle->stats_op = netfilter_stats_linux;
 574
 575         /* Create netlink socket */
 576         handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 577         if (handle->fd < 0) {
 578                 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 579                     errno, "Can't create raw socket");
 580                 return PCAP_ERROR;
 581         }
 582
 583         if (type == NFLOG) {
 584                 handle->linktype = DLT_NFLOG;
 585                 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 586                 if (handle->dlt_list != NULL) {
 587                         handle->dlt_list[0] = DLT_NFLOG;
 588                         handle->dlt_list[1] = DLT_IPV4;
 589                         handle->dlt_count = 2;
 590                 }
 591
 592         } else
 593                 handle->linktype = DLT_IPV4;
 594
 595         handle->buffer = malloc(handle->bufsize);
 596         if (!handle->buffer) {
 597                 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 598                     errno, "Can't allocate dump buffer");
 599                 goto close_fail;
 600         }
 601
 602         if (type == NFLOG) {
 603                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 604                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 605                             PCAP_ERRBUF_SIZE, errno,
 606                             "NFULNL_CFG_CMD_PF_UNBIND");
 607                         goto close_fail;
 608                 }
 609
 610                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 611                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 612                             PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
 613                         goto close_fail;
 614                 }
 615
 616                 /* Bind socket to the nflog groups */
 617                 for (i = 0; i < group_count; i++) {
 618                         if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 619                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 620                                     PCAP_ERRBUF_SIZE, errno,
 621                                     "Can't listen on group group index");
 622                                 goto close_fail;
 623                         }
 624
 625                         if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
 626                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 627                                     PCAP_ERRBUF_SIZE, errno,
 628                                     "NFULNL_COPY_PACKET");
 629                                 goto close_fail;
 630                         }
 631                 }
 632
 633         } else {
 634                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 635                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 636                             PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
 637                         goto close_fail;
 638                 }
 639
 640                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 641                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 642                             PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
 643                         goto close_fail;
 644                 }
 645
 646                 /* Bind socket to the nfqueue groups */
 647                 for (i = 0; i < group_count; i++) {
 648                         if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 649                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 650                                     PCAP_ERRBUF_SIZE, errno,
 651                                     "Can't listen on group group index");
 652                                 goto close_fail;
 653                         }
 654
 655                         if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
 656                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 657                                     PCAP_ERRBUF_SIZE, errno,
 658                                     "NFQNL_COPY_PACKET");
 659                                 goto close_fail;
 660                         }
 661                 }
 662         }
 663
 664         if (handle->opt.rfmon) {
 665                 /*
 666                  * Monitor mode doesn't apply to netfilter devices.
 667                  */
 668                 pcap_cleanup_live_common(handle);
 669                 return PCAP_ERROR_RFMON_NOTSUP;
 670         }
 671
 672         if (handle->opt.buffer_size != 0) {
 673                 /*
 674                  * Set the socket buffer size to the specified value.
 675                  */
 676                 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
 677                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 678                             PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
 679                         goto close_fail;
 680                 }
 681         }
 682
 683         handle->selectable_fd = handle->fd;
 684         return 0;
 685
 686 close_fail:
 687         pcap_cleanup_live_common(handle);
 688         return PCAP_ERROR;
 689 }
 690
 691 pcap_t *
 692 netfilter_create(const char *device, char *ebuf, int *is_ours)
 693 {
 694         const char *cp;
 695         pcap_t *p;
 696
 697         /* Does this look like an netfilter device? */
 698         cp = strrchr(device, '/');
 699         if (cp == NULL)
 700                 cp = device;
 701
 702         /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
 703         if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
 704                 cp += sizeof NFLOG_IFACE - 1;
 705         else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
 706                 cp += sizeof NFQUEUE_IFACE - 1;
 707         else {
 708                 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
 709                 *is_ours = 0;
 710                 return NULL;
 711         }
 712
 713         /*
 714          * Yes - is that either the end of the name, or is it followed
 715          * by a colon?
 716          */
 717         if (*cp != ':' && *cp != '\0') {
 718                 /* Nope */
 719                 *is_ours = 0;
 720                 return NULL;
 721         }
 722
 723         /* OK, it's probably ours. */
 724         *is_ours = 1;
 725
 726         p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter));
 727         if (p == NULL)
 728                 return (NULL);
 729
 730         p->activate_op = netfilter_activate;
 731         return (p);
 732 }
 733
 734 int
 735 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
 736 {
 737         int sock;
 738
 739         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 740         if (sock < 0) {
 741                 /* if netlink is not supported this is not fatal */
 742                 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
 743                         return 0;
 744                 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
 745                     errno, "Can't open netlink socket");
 746                 return -1;
 747         }
 748         close(sock);
 749
 750         /*
 751          * The notion of "connected" vs. "disconnected" doesn't apply.
 752          * XXX - what about "up" and "running"?
 753          */
 754         if (add_dev(devlistp, NFLOG_IFACE,
 755             PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
 756             "Linux netfilter log (NFLOG) interface", err_str) == NULL)
 757                 return -1;
 758         if (add_dev(devlistp, NFQUEUE_IFACE,
 759             PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
 760             "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
 761                 return -1;
 762         return 0;
 763 }