sys/netinet/ip_divert.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  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  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/sys/netinet/ip_divert.c,v 1.42.2.6 2003/01/23 21:06:45 sam Exp $
  30  */
  31
  32 #define _IP_VHL
  33
  34 #include "opt_inet.h"
  35 #include "opt_ipdivert.h"
  36 #include "opt_ipsec.h"
  37
  38 #ifndef INET
  39 #error "IPDIVERT requires INET."
  40 #endif
  41
  42 #include <sys/param.h>
  43 #include <sys/kernel.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mbuf.h>
  46 #include <sys/socket.h>
  47 #include <sys/protosw.h>
  48 #include <sys/socketvar.h>
  49 #include <sys/socketvar2.h>
  50 #include <sys/sysctl.h>
  51 #include <sys/systm.h>
  52 #include <sys/proc.h>
  53 #include <sys/priv.h>
  54 #include <sys/in_cksum.h>
  55 #include <sys/lock.h>
  56 #include <sys/msgport.h>
  57
  58 #include <net/if.h>
  59 #include <net/route.h>
  60
  61 #include <net/netmsg2.h>
  62 #include <net/netisr2.h>
  63 #include <sys/thread2.h>
  64 #include <sys/mplock2.h>
  65
  66 #include <netinet/in.h>
  67 #include <netinet/in_systm.h>
  68 #include <netinet/ip.h>
  69 #include <netinet/in_pcb.h>
  70 #include <netinet/in_var.h>
  71 #include <netinet/ip_var.h>
  72 #include <netinet/ip_divert.h>
  73
  74 /*
  75  * Divert sockets
  76  */
  77
  78 /*
  79  * Allocate enough space to hold a full IP packet
  80  */
  81 #define DIVSNDQ         (65536 + 100)
  82 #define DIVRCVQ         (65536 + 100)
  83
  84 #define DIV_IS_OUTPUT(sin)      ((sin) == NULL || (sin)->sin_addr.s_addr == 0)
  85
  86 #define DIV_OUTPUT      0x10000
  87 #define DIV_INPUT       0x20000
  88
  89 /*
  90  * Divert sockets work in conjunction with ipfw, see the divert(4)
  91  * manpage for features.
  92  * Internally, packets selected by ipfw in ip_input() or ip_output(),
  93  * and never diverted before, are passed to the input queue of the
  94  * divert socket with a given 'divert_port' number (as specified in
  95  * the matching ipfw rule), and they are tagged with a 16 bit cookie
  96  * (representing the rule number of the matching ipfw rule), which
  97  * is passed to process reading from the socket.
  98  *
  99  * Packets written to the divert socket are again tagged with a cookie
 100  * (usually the same as above) and a destination address.
 101  * If the destination address is INADDR_ANY then the packet is
 102  * treated as outgoing and sent to ip_output(), otherwise it is
 103  * treated as incoming and sent to ip_input().
 104  * In both cases, the packet is tagged with the cookie.
 105  *
 106  * On reinjection, processing in ip_input() and ip_output()
 107  * will be exactly the same as for the original packet, except that
 108  * ipfw processing will start at the rule number after the one
 109  * written in the cookie (so, tagging a packet with a cookie of 0
 110  * will cause it to be effectively considered as a standard packet).
 111  */
 112
 113 /* Internal variables */
 114 static struct inpcbinfo divcbinfo;
 115 static struct inpcbportinfo divcbportinfo;
 116
 117 static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
 118 static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
 119
 120 static struct mbuf *ip_divert(struct mbuf *, int, int);
 121
 122 /*
 123  * Initialize divert connection block queue.
 124  */
 125 void
 126 div_init(void)
 127 {
 128         in_pcbinfo_init(&divcbinfo, 0, FALSE);
 129         in_pcbportinfo_init(&divcbportinfo, 1, 0);
 130         /*
 131          * XXX We don't use the hash list for divert IP, but it's easier
 132          * to allocate a one entry hash list than it is to check all
 133          * over the place for hashbase == NULL.
 134          */
 135         divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
 136         divcbinfo.portinfo = &divcbportinfo;
 137         divcbinfo.wildcardhashbase = hashinit(1, M_PCB,
 138                                               &divcbinfo.wildcardhashmask);
 139         divcbinfo.ipi_size = sizeof(struct inpcb);
 140         ip_divert_p = ip_divert;
 141 }
 142
 143 /*
 144  * IPPROTO_DIVERT is not a real IP protocol; don't allow any packets
 145  * with that protocol number to enter the system from the outside.
 146  */
 147 int
 148 div_input(struct mbuf **mp, int *offp, int proto)
 149 {
 150         struct mbuf *m = *mp;
 151
 152         ipstat.ips_noproto++;
 153         m_freem(m);
 154         return(IPPROTO_DONE);
 155 }
 156
 157 /*
 158  * Divert a packet by passing it up to the divert socket at port 'port'.
 159  *
 160  * Setup generic address and protocol structures for div_input routine,
 161  * then pass them along with mbuf chain.
 162  */
 163 static void
 164 div_packet(struct mbuf *m, int incoming, int port)
 165 {
 166         struct sockaddr_in divsrc = { sizeof divsrc, AF_INET };
 167         struct inpcb *inp;
 168         struct socket *sa;
 169         struct m_tag *mtag;
 170         struct divert_info *divinfo;
 171         u_int16_t nport;
 172
 173         ASSERT_IN_NETISR(0);
 174
 175         /* Locate the divert info */
 176         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 177         divinfo = m_tag_data(mtag);
 178         divsrc.sin_port = divinfo->skipto;
 179
 180         /*
 181          * Record receive interface address, if any.
 182          * But only for incoming packets.
 183          */
 184         divsrc.sin_addr.s_addr = 0;
 185         if (incoming) {
 186                 struct ifaddr_container *ifac;
 187
 188                 /* Find IP address for receive interface */
 189                 TAILQ_FOREACH(ifac, &m->m_pkthdr.rcvif->if_addrheads[mycpuid],
 190                               ifa_link) {
 191                         struct ifaddr *ifa = ifac->ifa;
 192
 193                         if (ifa->ifa_addr == NULL)
 194                                 continue;
 195                         if (ifa->ifa_addr->sa_family != AF_INET)
 196                                 continue;
 197                         divsrc.sin_addr =
 198                             ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
 199                         break;
 200                 }
 201         }
 202         /*
 203          * Record the incoming interface name whenever we have one.
 204          */
 205         if (m->m_pkthdr.rcvif) {
 206                 /*
 207                  * Hide the actual interface name in there in the
 208                  * sin_zero array. XXX This needs to be moved to a
 209                  * different sockaddr type for divert, e.g.
 210                  * sockaddr_div with multiple fields like
 211                  * sockaddr_dl. Presently we have only 7 bytes
 212                  * but that will do for now as most interfaces
 213                  * are 4 or less + 2 or less bytes for unit.
 214                  * There is probably a faster way of doing this,
 215                  * possibly taking it from the sockaddr_dl on the iface.
 216                  * This solves the problem of a P2P link and a LAN interface
 217                  * having the same address, which can result in the wrong
 218                  * interface being assigned to the packet when fed back
 219                  * into the divert socket. Theoretically if the daemon saves
 220                  * and re-uses the sockaddr_in as suggested in the man pages,
 221                  * this iface name will come along for the ride.
 222                  * (see div_output for the other half of this.)
 223                  */
 224                 ksnprintf(divsrc.sin_zero, sizeof divsrc.sin_zero, "%s",
 225                           m->m_pkthdr.rcvif->if_xname);
 226         }
 227
 228         /* Put packet on socket queue, if any */
 229         sa = NULL;
 230         nport = htons((u_int16_t)port);
 231
 232         /*
 233          * Following loop to locate the inpcb is MPSAFE since the inpcb
 234          * insertion/removal happens on the same CPU (CPU0).
 235          */
 236         LIST_FOREACH(inp, &divcbinfo.pcblisthead, inp_list) {
 237                 if (inp->inp_flags & INP_PLACEMARKER)
 238                         continue;
 239                 if (inp->inp_lport == nport)
 240                         sa = inp->inp_socket;
 241         }
 242         if (sa) {
 243                 lwkt_gettoken(&sa->so_rcv.ssb_token);
 244                 if (ssb_appendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc, m, NULL) == 0)
 245                         m_freem(m);
 246                 else
 247                         sorwakeup(sa);
 248                 lwkt_reltoken(&sa->so_rcv.ssb_token);
 249         } else {
 250                 m_freem(m);
 251                 ipstat.ips_noproto++;
 252                 ipstat.ips_delivered--;
 253         }
 254 }
 255
 256 static void
 257 div_packet_handler(netmsg_t msg)
 258 {
 259         struct mbuf *m;
 260         int port, incoming = 0;
 261
 262         m = msg->packet.nm_packet;
 263
 264         port = msg->lmsg.u.ms_result32 & 0xffff;
 265         if (msg->lmsg.u.ms_result32 & DIV_INPUT)
 266                 incoming = 1;
 267         div_packet(m, incoming, port);
 268         /* no reply, msg embedded in mbuf */
 269 }
 270
 271 static void
 272 divert_packet(struct mbuf *m, int incoming)
 273 {
 274         struct m_tag *mtag;
 275         struct divert_info *divinfo;
 276         int port;
 277
 278         M_ASSERTPKTHDR(m);
 279
 280         /* Assure header */
 281         if (m->m_len < sizeof(struct ip) &&
 282             (m = m_pullup(m, sizeof(struct ip))) == NULL)
 283                 return;
 284
 285         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 286         KASSERT(mtag != NULL, ("%s no divert tag!", __func__));
 287         divinfo = m_tag_data(mtag);
 288
 289         port = divinfo->port;
 290         KASSERT(port != 0, ("%s: port=0", __func__));
 291
 292         if (mycpuid != 0) {
 293                 struct netmsg_packet *nmp;
 294
 295                 nmp = &m->m_hdr.mh_netmsg;
 296                 netmsg_init(&nmp->base, NULL, &netisr_apanic_rport,
 297                             0, div_packet_handler);
 298                 nmp->nm_packet = m;
 299
 300                 nmp->base.lmsg.u.ms_result32 = port; /* port is 16bits */
 301                 if (incoming)
 302                         nmp->base.lmsg.u.ms_result32 |= DIV_INPUT;
 303                 else
 304                         nmp->base.lmsg.u.ms_result32 |= DIV_OUTPUT;
 305
 306                 lwkt_sendmsg(netisr_cpuport(0), &nmp->base.lmsg);
 307         } else {
 308                 div_packet(m, incoming, port);
 309         }
 310 }
 311
 312 /*
 313  * Deliver packet back into the IP processing machinery.
 314  *
 315  * If no address specified, or address is 0.0.0.0, send to ip_output();
 316  * otherwise, send to ip_input() and mark as having been received on
 317  * the interface with that address.
 318  */
 319 static int
 320 div_output(struct socket *so, struct mbuf *m,
 321         struct sockaddr_in *sin, struct mbuf *control)
 322 {
 323         int error = 0;
 324         struct m_tag *mtag;
 325         struct divert_info *divinfo;
 326
 327         ASSERT_IN_NETISR(0);
 328
 329         if (control)
 330                 m_freem(control);               /* XXX */
 331
 332         /*
 333          * Prepare the tag for divert info. Note that a packet
 334          * with a 0 tag in mh_data is effectively untagged,
 335          * so we could optimize that case.
 336          */
 337         mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, sizeof(*divinfo), M_NOWAIT);
 338         if (mtag == NULL) {
 339                 error = ENOBUFS;
 340                 goto cantsend;
 341         }
 342         m_tag_prepend(m, mtag);
 343
 344         /* Loopback avoidance and state recovery */
 345         divinfo = m_tag_data(mtag);
 346         if (sin)
 347                 divinfo->skipto = sin->sin_port;
 348         else
 349                 divinfo->skipto = 0;
 350
 351         /* Reinject packet into the system as incoming or outgoing */
 352         if (DIV_IS_OUTPUT(sin)) {
 353                 struct ip *const ip = mtod(m, struct ip *);
 354
 355                 /* Don't allow packet length sizes that will crash */
 356                 if ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len) {
 357                         error = EINVAL;
 358                         goto cantsend;
 359                 }
 360
 361                 /* Convert fields to host order for ip_output() */
 362                 ip->ip_len = ntohs(ip->ip_len);
 363                 ip->ip_off = ntohs(ip->ip_off);
 364
 365                 /* Send packet to output processing */
 366                 ipstat.ips_rawout++;                    /* XXX */
 367                 error = ip_output(m, NULL, NULL,
 368                             (so->so_options & SO_DONTROUTE) |
 369                             IP_ALLOWBROADCAST | IP_RAWOUTPUT,
 370                             NULL, NULL);
 371         } else {
 372                 ip_input(m);
 373         }
 374         return error;
 375
 376 cantsend:
 377         m_freem(m);
 378         return error;
 379 }
 380
 381 static void
 382 div_attach(netmsg_t msg)
 383 {
 384         struct socket *so = msg->attach.base.nm_so;
 385         int proto = msg->attach.nm_proto;
 386         struct pru_attach_info *ai = msg->attach.nm_ai;
 387         struct inpcb *inp;
 388         int error;
 389
 390         ASSERT_IN_NETISR(0);
 391
 392         inp  = so->so_pcb;
 393         if (inp)
 394                 panic("div_attach");
 395         error = priv_check_cred(ai->p_ucred, PRIV_ROOT, NULL_CRED_OKAY);
 396         if (error)
 397                 goto out;
 398
 399         error = soreserve(so, div_sendspace, div_recvspace, ai->sb_rlimit);
 400         if (error)
 401                 goto out;
 402         error = in_pcballoc(so, &divcbinfo);
 403         if (error)
 404                 goto out;
 405         inp = (struct inpcb *)so->so_pcb;
 406         inp->inp_ip_p = proto;
 407         inp->inp_flags |= INP_HDRINCL;
 408         /*
 409          * The socket is always "connected" because
 410          * we always know "where" to send the packet.
 411          */
 412         sosetstate(so, SS_ISCONNECTED);
 413         error = 0;
 414 out:
 415         lwkt_replymsg(&msg->attach.base.lmsg, error);
 416 }
 417
 418 static void
 419 div_detach(netmsg_t msg)
 420 {
 421         struct socket *so = msg->detach.base.nm_so;
 422         struct inpcb *inp;
 423
 424         ASSERT_IN_NETISR(0);
 425
 426         inp = so->so_pcb;
 427         if (inp == NULL)
 428                 panic("div_detach");
 429         in_pcbdetach(inp);
 430         lwkt_replymsg(&msg->detach.base.lmsg, 0);
 431 }
 432
 433 static void
 434 div_abort(netmsg_t msg)
 435 {
 436         /*
 437          * Divert socket does not support listen(2),
 438          * so this should never be called.
 439          */
 440         panic("div_abort is called");
 441 }
 442
 443 static void
 444 div_disconnect(netmsg_t msg)
 445 {
 446         struct socket *so = msg->disconnect.base.nm_so;
 447         int error;
 448
 449         ASSERT_IN_NETISR(0);
 450
 451         if (so->so_state & SS_ISCONNECTED) {
 452                 soisdisconnected(so);
 453                 error = 0;
 454         } else {
 455                 error = ENOTCONN;
 456         }
 457         lwkt_replymsg(&msg->disconnect.base.lmsg, error);
 458 }
 459
 460 static void
 461 div_bind(netmsg_t msg)
 462 {
 463         struct socket *so = msg->bind.base.nm_so;
 464         struct sockaddr *nam = msg->bind.nm_nam;
 465         int error;
 466
 467         ASSERT_IN_NETISR(0);
 468
 469         /*
 470          * in_pcbbind assumes that nam is a sockaddr_in
 471          * and in_pcbbind requires a valid address. Since divert
 472          * sockets don't we need to make sure the address is
 473          * filled in properly.
 474          * XXX -- divert should not be abusing in_pcbind
 475          * and should probably have its own family.
 476          */
 477         if (nam->sa_family != AF_INET) {
 478                 error = EAFNOSUPPORT;
 479         } else {
 480                 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
 481                 error = in_pcbbind(so->so_pcb, nam, msg->bind.nm_td);
 482         }
 483         lwkt_replymsg(&msg->bind.base.lmsg, error);
 484 }
 485
 486 static void
 487 div_shutdown(netmsg_t msg)
 488 {
 489         struct socket *so = msg->shutdown.base.nm_so;
 490
 491         ASSERT_IN_NETISR(0);
 492
 493         socantsendmore(so);
 494
 495         lwkt_replymsg(&msg->shutdown.base.lmsg, 0);
 496 }
 497
 498 static void
 499 div_send(netmsg_t msg)
 500 {
 501         struct socket *so = msg->send.base.nm_so;
 502         struct mbuf *m = msg->send.nm_m;
 503         struct sockaddr *nam = msg->send.nm_addr;
 504         struct mbuf *control = msg->send.nm_control;
 505         int error;
 506
 507         /* Length check already done in ip_hashfn() */
 508         KASSERT(m->m_len >= sizeof(struct ip), ("IP header not in one mbuf"));
 509
 510         /* Send packet */
 511         error = div_output(so, m, (struct sockaddr_in *)nam, control);
 512         lwkt_replymsg(&msg->send.base.lmsg, error);
 513 }
 514
 515 SYSCTL_DECL(_net_inet_divert);
 516 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, &divcbinfo, 1,
 517             in_pcblist_global, "S,xinpcb", "List of active divert sockets");
 518
 519 struct pr_usrreqs div_usrreqs = {
 520         .pru_abort = div_abort,
 521         .pru_accept = pr_generic_notsupp,
 522         .pru_attach = div_attach,
 523         .pru_bind = div_bind,
 524         .pru_connect = pr_generic_notsupp,
 525         .pru_connect2 = pr_generic_notsupp,
 526         .pru_control = in_control_dispatch,
 527         .pru_detach = div_detach,
 528         .pru_disconnect = div_disconnect,
 529         .pru_listen = pr_generic_notsupp,
 530         .pru_peeraddr = in_setpeeraddr_dispatch,
 531         .pru_rcvd = pr_generic_notsupp,
 532         .pru_rcvoob = pr_generic_notsupp,
 533         .pru_send = div_send,
 534         .pru_sense = pru_sense_null,
 535         .pru_shutdown = div_shutdown,
 536         .pru_sockaddr = in_setsockaddr_dispatch,
 537         .pru_sosend = sosend,
 538         .pru_soreceive = soreceive
 539 };
 540
 541 static struct mbuf *
 542 ip_divert_out(struct mbuf *m, int tee)
 543 {
 544         struct mbuf *clone = NULL;
 545         struct ip *ip = mtod(m, struct ip *);
 546
 547         /* Clone packet if we're doing a 'tee' */
 548         if (tee)
 549                 clone = m_dup(m, M_NOWAIT);
 550
 551         /*
 552          * XXX
 553          * delayed checksums are not currently compatible
 554          * with divert sockets.
 555          */
 556         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 557                 in_delayed_cksum(m);
 558                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 559         }
 560
 561         /* Restore packet header fields to original values */
 562         ip->ip_len = htons(ip->ip_len);
 563         ip->ip_off = htons(ip->ip_off);
 564
 565         /* Deliver packet to divert input routine */
 566         divert_packet(m, 0);
 567
 568         /* If 'tee', continue with original packet */
 569         return clone;
 570 }
 571
 572 static struct mbuf *
 573 ip_divert_in(struct mbuf *m, int tee)
 574 {
 575         struct mbuf *clone = NULL;
 576         struct ip *ip = mtod(m, struct ip *);
 577         struct m_tag *mtag;
 578
 579         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 580                 const struct divert_info *divinfo;
 581                 u_short frag_off;
 582                 int hlen;
 583
 584                 /*
 585                  * Only trust divert info in the fragment
 586                  * at offset 0.
 587                  */
 588                 frag_off = ip->ip_off << 3;
 589                 if (frag_off != 0) {
 590                         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 591                         m_tag_delete(m, mtag);
 592                 }
 593
 594                 /*
 595                  * Attempt reassembly; if it succeeds, proceed.
 596                  * ip_reass() will return a different mbuf.
 597                  */
 598                 m = ip_reass(m);
 599                 if (m == NULL)
 600                         return NULL;
 601                 ip = mtod(m, struct ip *);
 602
 603                 /* Caller need to redispatch the packet, if it is for us */
 604                 m->m_pkthdr.fw_flags |= FW_MBUF_REDISPATCH;
 605
 606                 /*
 607                  * Get the header length of the reassembled
 608                  * packet
 609                  */
 610                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 611
 612                 /*
 613                  * Restore original checksum before diverting
 614                  * packet
 615                  */
 616                 ip->ip_len += hlen;
 617                 ip->ip_len = htons(ip->ip_len);
 618                 ip->ip_off = htons(ip->ip_off);
 619                 ip->ip_sum = 0;
 620                 if (hlen == sizeof(struct ip))
 621                         ip->ip_sum = in_cksum_hdr(ip);
 622                 else
 623                         ip->ip_sum = in_cksum(m, hlen);
 624                 ip->ip_off = ntohs(ip->ip_off);
 625                 ip->ip_len = ntohs(ip->ip_len);
 626
 627                 /*
 628                  * Only use the saved divert info
 629                  */
 630                 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 631                 if (mtag == NULL) {
 632                         /* Wrongly configured ipfw */
 633                         kprintf("ip_input no divert info\n");
 634                         m_freem(m);
 635                         return NULL;
 636                 }
 637                 divinfo = m_tag_data(mtag);
 638                 tee = divinfo->tee;
 639         }
 640
 641         /*
 642          * Divert or tee packet to the divert protocol if
 643          * required.
 644          */
 645
 646         /* Clone packet if we're doing a 'tee' */
 647         if (tee)
 648                 clone = m_dup(m, M_NOWAIT);
 649
 650         /*
 651          * Restore packet header fields to original
 652          * values
 653          */
 654         ip->ip_len = htons(ip->ip_len);
 655         ip->ip_off = htons(ip->ip_off);
 656
 657         /* Deliver packet to divert input routine */
 658         divert_packet(m, 1);
 659
 660         /* Catch invalid reference */
 661         m = NULL;
 662         ip = NULL;
 663
 664         ipstat.ips_delivered++;
 665
 666         /* If 'tee', continue with original packet */
 667         if (clone != NULL) {
 668                 /*
 669                  * Complete processing of the packet.
 670                  * XXX Better safe than sorry, remove the DIVERT tag.
 671                  */
 672                 mtag = m_tag_find(clone, PACKET_TAG_IPFW_DIVERT, NULL);
 673                 KKASSERT(mtag != NULL);
 674                 m_tag_delete(clone, mtag);
 675         }
 676         return clone;
 677 }
 678
 679 static struct mbuf *
 680 ip_divert(struct mbuf *m, int tee, int incoming)
 681 {
 682         struct mbuf *ret;
 683
 684         if (incoming)
 685                 ret = ip_divert_in(m, tee);
 686         else
 687                 ret = ip_divert_out(m, tee);
 688         return ret;
 689 }