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,
 305             "Packet injection is not supported on netfilter devices");
 306         return (-1);
 307 }
 308
 309 struct my_nfattr {
 310         uint16_t nfa_len;
 311         uint16_t nfa_type;
 312         void *data;
 313 };
 314
 315 static int
 316 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)
 317 {
 318         char buf[1024] __attribute__ ((aligned));
 319
 320         struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
 321         struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr));
 322
 323         struct sockaddr_nl snl;
 324         static unsigned int seq_id;
 325
 326         if (!seq_id)
 327                 seq_id = time(NULL);
 328         ++seq_id;
 329
 330         nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
 331         nlh->nlmsg_type = msg_type;
 332         nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
 333         nlh->nlmsg_pid = 0;     /* to kernel */
 334         nlh->nlmsg_seq = seq_id;
 335
 336         nfg->nfgen_family = family;
 337         nfg->version = NFNETLINK_V0;
 338         nfg->res_id = htons(res_id);
 339
 340         if (mynfa) {
 341                 struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len));
 342
 343                 nfa->nfa_type = mynfa->nfa_type;
 344                 nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len);
 345                 memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len);
 346                 nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len);
 347         }
 348
 349         memset(&snl, 0, sizeof(snl));
 350         snl.nl_family = AF_NETLINK;
 351
 352         if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
 353                 return -1;
 354
 355         if (!ack)
 356                 return 0;
 357
 358         /* waiting for reply loop */
 359         do {
 360                 socklen_t addrlen = sizeof(snl);
 361                 int len;
 362
 363                 /* ignore interrupt system call error */
 364                 do {
 365                         /*
 366                          * The buffer is not so big that its size won't
 367                          * fit into an int.
 368                          */
 369                         len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen);
 370                 } while ((len == -1) && (errno == EINTR));
 371
 372                 if (len <= 0)
 373                         return len;
 374
 375                 if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) {
 376                         errno = EINVAL;
 377                         return -1;
 378                 }
 379
 380                 nlh = (struct nlmsghdr *) buf;
 381                 if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq)        /* if not from kernel or wrong sequence skip */
 382                         continue;
 383
 384                 while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) {
 385                         if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) {
 386                                 if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) {
 387                                         errno = EBADMSG;
 388                                         return -1;
 389                                 }
 390                                 errno = -(*((int *)NLMSG_DATA(nlh)));
 391                                 return (errno == 0) ? 0 : -1;
 392                         }
 393                         nlh = NLMSG_NEXT(nlh, len);
 394                 }
 395         } while (1);
 396
 397         return -1; /* never here */
 398 }
 399
 400 static int
 401 nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 402 {
 403         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
 404 }
 405
 406 static int
 407 nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family)
 408 {
 409         struct nfulnl_msg_config_cmd msg;
 410         struct my_nfattr nfa;
 411
 412         msg.command = cmd;
 413
 414         nfa.data = &msg;
 415         nfa.nfa_type = NFULA_CFG_CMD;
 416         nfa.nfa_len = sizeof(msg);
 417
 418         return nflog_send_config_msg(handle, family, group_id, &nfa);
 419 }
 420
 421 static int
 422 nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 423 {
 424         struct nfulnl_msg_config_mode msg;
 425         struct my_nfattr nfa;
 426
 427         msg.copy_range = htonl(copy_range);
 428         msg.copy_mode = copy_mode;
 429
 430         nfa.data = &msg;
 431         nfa.nfa_type = NFULA_CFG_MODE;
 432         nfa.nfa_len = sizeof(msg);
 433
 434         return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 435 }
 436
 437 static int
 438 nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict)
 439 {
 440         struct nfqnl_msg_verdict_hdr msg;
 441         struct my_nfattr nfa;
 442
 443         msg.id = htonl(id);
 444         msg.verdict = htonl(verdict);
 445
 446         nfa.data = &msg;
 447         nfa.nfa_type = NFQA_VERDICT_HDR;
 448         nfa.nfa_len = sizeof(msg);
 449
 450         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
 451 }
 452
 453 static int
 454 nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
 455 {
 456         return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
 457 }
 458
 459 static int
 460 nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf)
 461 {
 462         struct nfqnl_msg_config_cmd msg;
 463         struct my_nfattr nfa;
 464
 465         msg.command = cmd;
 466         msg.pf = htons(pf);
 467
 468         nfa.data = &msg;
 469         nfa.nfa_type = NFQA_CFG_CMD;
 470         nfa.nfa_len = sizeof(msg);
 471
 472         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 473 }
 474
 475 static int
 476 nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
 477 {
 478         struct nfqnl_msg_config_params msg;
 479         struct my_nfattr nfa;
 480
 481         msg.copy_range = htonl(copy_range);
 482         msg.copy_mode = copy_mode;
 483
 484         nfa.data = &msg;
 485         nfa.nfa_type = NFQA_CFG_PARAMS;
 486         nfa.nfa_len = sizeof(msg);
 487
 488         return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
 489 }
 490
 491 static int
 492 netfilter_activate(pcap_t* handle)
 493 {
 494         const char *dev = handle->opt.device;
 495         unsigned short groups[32];
 496         int group_count = 0;
 497         nftype_t type = OTHER;
 498         int i;
 499
 500         if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
 501                 dev += strlen(NFLOG_IFACE);
 502                 type = NFLOG;
 503
 504         } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
 505                 dev += strlen(NFQUEUE_IFACE);
 506                 type = NFQUEUE;
 507         }
 508
 509         if (type != OTHER && *dev == ':') {
 510                 dev++;
 511                 while (*dev) {
 512                         long int group_id;
 513                         char *end_dev;
 514
 515                         if (group_count == 32) {
 516                                 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 517                                                 "Maximum 32 netfilter groups! dev: %s",
 518                                                 handle->opt.device);
 519                                 return PCAP_ERROR;
 520                         }
 521
 522                         group_id = strtol(dev, &end_dev, 0);
 523                         if (end_dev != dev) {
 524                                 if (group_id < 0 || group_id > 65535) {
 525                                         pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 526                                                         "Netfilter group range from 0 to 65535 (got %ld)",
 527                                                         group_id);
 528                                         return PCAP_ERROR;
 529                                 }
 530
 531                                 groups[group_count++] = (unsigned short) group_id;
 532                                 dev = end_dev;
 533                         }
 534                         if (*dev != ',')
 535                                 break;
 536                         dev++;
 537                 }
 538         }
 539
 540         if (type == OTHER || *dev) {
 541                 pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 542                                 "Can't get netfilter group(s) index from %s",
 543                                 handle->opt.device);
 544                 return PCAP_ERROR;
 545         }
 546
 547         /* if no groups, add default: 0 */
 548         if (!group_count) {
 549                 groups[0] = 0;
 550                 group_count = 1;
 551         }
 552
 553         /*
 554          * Turn a negative snapshot value (invalid), a snapshot value of
 555          * 0 (unspecified), or a value bigger than the normal maximum
 556          * value, into the maximum allowed value.
 557          *
 558          * If some application really *needs* a bigger snapshot
 559          * length, we should just increase MAXIMUM_SNAPLEN.
 560          */
 561         if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
 562                 handle->snapshot = MAXIMUM_SNAPLEN;
 563
 564         /* Initialize some components of the pcap structure. */
 565         handle->bufsize = 128 + handle->snapshot;
 566         handle->offset = 0;
 567         handle->read_op = netfilter_read_linux;
 568         handle->inject_op = netfilter_inject_linux;
 569         handle->setfilter_op = install_bpf_program; /* no kernel filtering */
 570         handle->setdirection_op = NULL;
 571         handle->set_datalink_op = netfilter_set_datalink;
 572         handle->getnonblock_op = pcap_getnonblock_fd;
 573         handle->setnonblock_op = pcap_setnonblock_fd;
 574         handle->stats_op = netfilter_stats_linux;
 575
 576         /* Create netlink socket */
 577         handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 578         if (handle->fd < 0) {
 579                 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 580                     errno, "Can't create raw socket");
 581                 return PCAP_ERROR;
 582         }
 583
 584         if (type == NFLOG) {
 585                 handle->linktype = DLT_NFLOG;
 586                 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
 587                 if (handle->dlt_list != NULL) {
 588                         handle->dlt_list[0] = DLT_NFLOG;
 589                         handle->dlt_list[1] = DLT_IPV4;
 590                         handle->dlt_count = 2;
 591                 }
 592
 593         } else
 594                 handle->linktype = DLT_IPV4;
 595
 596         handle->buffer = malloc(handle->bufsize);
 597         if (!handle->buffer) {
 598                 pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 599                     errno, "Can't allocate dump buffer");
 600                 goto close_fail;
 601         }
 602
 603         if (type == NFLOG) {
 604                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 605                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 606                             PCAP_ERRBUF_SIZE, errno,
 607                             "NFULNL_CFG_CMD_PF_UNBIND");
 608                         goto close_fail;
 609                 }
 610
 611                 if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 612                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 613                             PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
 614                         goto close_fail;
 615                 }
 616
 617                 /* Bind socket to the nflog groups */
 618                 for (i = 0; i < group_count; i++) {
 619                         if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 620                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 621                                     PCAP_ERRBUF_SIZE, errno,
 622                                     "Can't listen on group group index");
 623                                 goto close_fail;
 624                         }
 625
 626                         if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
 627                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 628                                     PCAP_ERRBUF_SIZE, errno,
 629                                     "NFULNL_COPY_PACKET");
 630                                 goto close_fail;
 631                         }
 632                 }
 633
 634         } else {
 635                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
 636                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 637                             PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND");
 638                         goto close_fail;
 639                 }
 640
 641                 if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
 642                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 643                             PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
 644                         goto close_fail;
 645                 }
 646
 647                 /* Bind socket to the nfqueue groups */
 648                 for (i = 0; i < group_count; i++) {
 649                         if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
 650                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 651                                     PCAP_ERRBUF_SIZE, errno,
 652                                     "Can't listen on group group index");
 653                                 goto close_fail;
 654                         }
 655
 656                         if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
 657                                 pcap_fmt_errmsg_for_errno(handle->errbuf,
 658                                     PCAP_ERRBUF_SIZE, errno,
 659                                     "NFQNL_COPY_PACKET");
 660                                 goto close_fail;
 661                         }
 662                 }
 663         }
 664
 665         if (handle->opt.rfmon) {
 666                 /*
 667                  * Monitor mode doesn't apply to netfilter devices.
 668                  */
 669                 pcap_cleanup_live_common(handle);
 670                 return PCAP_ERROR_RFMON_NOTSUP;
 671         }
 672
 673         if (handle->opt.buffer_size != 0) {
 674                 /*
 675                  * Set the socket buffer size to the specified value.
 676                  */
 677                 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) {
 678                         pcap_fmt_errmsg_for_errno(handle->errbuf,
 679                             PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
 680                         goto close_fail;
 681                 }
 682         }
 683
 684         handle->selectable_fd = handle->fd;
 685         return 0;
 686
 687 close_fail:
 688         pcap_cleanup_live_common(handle);
 689         return PCAP_ERROR;
 690 }
 691
 692 pcap_t *
 693 netfilter_create(const char *device, char *ebuf, int *is_ours)
 694 {
 695         const char *cp;
 696         pcap_t *p;
 697
 698         /* Does this look like an netfilter device? */
 699         cp = strrchr(device, '/');
 700         if (cp == NULL)
 701                 cp = device;
 702
 703         /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
 704         if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
 705                 cp += sizeof NFLOG_IFACE - 1;
 706         else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
 707                 cp += sizeof NFQUEUE_IFACE - 1;
 708         else {
 709                 /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
 710                 *is_ours = 0;
 711                 return NULL;
 712         }
 713
 714         /*
 715          * Yes - is that either the end of the name, or is it followed
 716          * by a colon?
 717          */
 718         if (*cp != ':' && *cp != '\0') {
 719                 /* Nope */
 720                 *is_ours = 0;
 721                 return NULL;
 722         }
 723
 724         /* OK, it's probably ours. */
 725         *is_ours = 1;
 726
 727         p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter));
 728         if (p == NULL)
 729                 return (NULL);
 730
 731         p->activate_op = netfilter_activate;
 732         return (p);
 733 }
 734
 735 int
 736 netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
 737 {
 738         int sock;
 739
 740         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
 741         if (sock < 0) {
 742                 /* if netlink is not supported this is not fatal */
 743                 if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
 744                         return 0;
 745                 pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
 746                     errno, "Can't open netlink socket");
 747                 return -1;
 748         }
 749         close(sock);
 750
 751         /*
 752          * The notion of "connected" vs. "disconnected" doesn't apply.
 753          * XXX - what about "up" and "running"?
 754          */
 755         if (add_dev(devlistp, NFLOG_IFACE,
 756             PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
 757             "Linux netfilter log (NFLOG) interface", err_str) == NULL)
 758                 return -1;
 759         if (add_dev(devlistp, NFQUEUE_IFACE,
 760             PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
 761             "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
 762                 return -1;
 763         return 0;
 764 }