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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD: src/sys/netinet/ip_divert.c,v 1.42.2.6 2003/01/23 21:06:45 sam Exp $
  34  * $DragonFly: src/sys/netinet/ip_divert.c,v 1.40 2008/10/21 13:51:01 sephe Exp $
  35  */
  36
  37 #define _IP_VHL
  38
  39 #include "opt_inet.h"
  40 #include "opt_ipfw.h"
  41 #include "opt_ipdivert.h"
  42 #include "opt_ipsec.h"
  43
  44 #ifndef INET
  45 #error "IPDIVERT requires INET."
  46 #endif
  47
  48 #include <sys/param.h>
  49 #include <sys/kernel.h>
  50 #include <sys/malloc.h>
  51 #include <sys/mbuf.h>
  52 #include <sys/socket.h>
  53 #include <sys/protosw.h>
  54 #include <sys/socketvar.h>
  55 #include <sys/sysctl.h>
  56 #include <sys/systm.h>
  57 #include <sys/proc.h>
  58 #include <sys/thread2.h>
  59 #include <sys/in_cksum.h>
  60 #include <sys/lock.h>
  61 #ifdef SMP
  62 #include <sys/msgport.h>
  63 #endif
  64
  65 #include <vm/vm_zone.h>
  66
  67 #include <net/if.h>
  68 #include <net/route.h>
  69 #ifdef SMP
  70 #include <net/netmsg2.h>
  71 #endif
  72
  73 #include <netinet/in.h>
  74 #include <netinet/in_systm.h>
  75 #include <netinet/ip.h>
  76 #include <netinet/in_pcb.h>
  77 #include <netinet/in_var.h>
  78 #include <netinet/ip_var.h>
  79 #include <netinet/ip_divert.h>
  80
  81 /*
  82  * Divert sockets
  83  */
  84
  85 /*
  86  * Allocate enough space to hold a full IP packet
  87  */
  88 #define DIVSNDQ         (65536 + 100)
  89 #define DIVRCVQ         (65536 + 100)
  90
  91 #define DIV_IS_OUTPUT(sin)      ((sin) == NULL || (sin)->sin_addr.s_addr == 0)
  92
  93 #define DIV_OUTPUT      0x10000
  94 #define DIV_INPUT       0x20000
  95
  96 /*
  97  * Divert sockets work in conjunction with ipfw, see the divert(4)
  98  * manpage for features.
  99  * Internally, packets selected by ipfw in ip_input() or ip_output(),
 100  * and never diverted before, are passed to the input queue of the
 101  * divert socket with a given 'divert_port' number (as specified in
 102  * the matching ipfw rule), and they are tagged with a 16 bit cookie
 103  * (representing the rule number of the matching ipfw rule), which
 104  * is passed to process reading from the socket.
 105  *
 106  * Packets written to the divert socket are again tagged with a cookie
 107  * (usually the same as above) and a destination address.
 108  * If the destination address is INADDR_ANY then the packet is
 109  * treated as outgoing and sent to ip_output(), otherwise it is
 110  * treated as incoming and sent to ip_input().
 111  * In both cases, the packet is tagged with the cookie.
 112  *
 113  * On reinjection, processing in ip_input() and ip_output()
 114  * will be exactly the same as for the original packet, except that
 115  * ipfw processing will start at the rule number after the one
 116  * written in the cookie (so, tagging a packet with a cookie of 0
 117  * will cause it to be effectively considered as a standard packet).
 118  */
 119
 120 /* Internal variables */
 121 static struct inpcbinfo divcbinfo;
 122
 123 static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
 124 static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
 125
 126 static struct mbuf *ip_divert(struct mbuf *, int, int);
 127
 128 /*
 129  * Initialize divert connection block queue.
 130  */
 131 void
 132 div_init(void)
 133 {
 134         in_pcbinfo_init(&divcbinfo);
 135         /*
 136          * XXX We don't use the hash list for divert IP, but it's easier
 137          * to allocate a one entry hash list than it is to check all
 138          * over the place for hashbase == NULL.
 139          */
 140         divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
 141         divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
 142         divcbinfo.wildcardhashbase = hashinit(1, M_PCB,
 143                                               &divcbinfo.wildcardhashmask);
 144         divcbinfo.ipi_zone = zinit("divcb", sizeof(struct inpcb),
 145                                    maxsockets, ZONE_INTERRUPT, 0);
 146         ip_divert_p = ip_divert;
 147 }
 148
 149 /*
 150  * IPPROTO_DIVERT is not a real IP protocol; don't allow any packets
 151  * with that protocol number to enter the system from the outside.
 152  */
 153 void
 154 div_input(struct mbuf *m, ...)
 155 {
 156         ipstat.ips_noproto++;
 157         m_freem(m);
 158 }
 159
 160 struct lwkt_port *
 161 div_soport(struct socket *so, struct sockaddr *nam,
 162            struct mbuf **mptr, int req)
 163 {
 164         struct sockaddr_in *sin;
 165         struct mbuf *m;
 166         int dir;
 167
 168         /* Except for send(), everything happens on CPU0 */
 169         if (req != PRU_SEND)
 170                 return cpu0_soport(so, nam, mptr, req);
 171
 172         sin = (struct sockaddr_in *)nam;
 173         m = *mptr;
 174         M_ASSERTPKTHDR(m);
 175
 176         m->m_pkthdr.rcvif = NULL;
 177         dir = DIV_IS_OUTPUT(sin) ? IP_MPORT_OUT : IP_MPORT_IN;
 178
 179         if (sin != NULL) {
 180                 int i;
 181
 182                 /*
 183                  * Try locating the interface, if we originally had one.
 184                  * This is done even for outgoing packets, since for a
 185                  * forwarded packet, there must be an interface attached.
 186                  *
 187                  * Find receive interface with the given name, stuffed
 188                  * (if it exists) in the sin_zero[] field.
 189                  * The name is user supplied data so don't trust its size
 190                  * or that it is zero terminated.
 191                  */
 192                 for (i = 0; sin->sin_zero[i] && i < sizeof(sin->sin_zero); i++)
 193                         ;
 194                 if (i > 0 && i < sizeof(sin->sin_zero))
 195                         m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
 196         }
 197
 198         if (dir == IP_MPORT_IN && m->m_pkthdr.rcvif == NULL) {
 199                 /*
 200                  * No luck with the name, check by IP address.
 201                  * Clear the port and the ifname to make sure
 202                  * there are no distractions for ifa_ifwithaddr.
 203                  *
 204                  * Be careful not to trash sin->sin_port; it will
 205                  * be used later in div_output().
 206                  */
 207                 struct ifaddr *ifa;
 208                 u_short sin_port;
 209
 210                 bzero(sin->sin_zero, sizeof(sin->sin_zero));
 211                 sin_port = sin->sin_port; /* save */
 212                 sin->sin_port = 0;
 213                 ifa = ifa_ifwithaddr((struct sockaddr *)sin);
 214                 if (ifa == NULL) {
 215                         m_freem(m);
 216                         *mptr = NULL;
 217                         return NULL;
 218                 }
 219                 sin->sin_port = sin_port; /* restore */
 220                 m->m_pkthdr.rcvif = ifa->ifa_ifp;
 221         }
 222
 223         return ip_mport(mptr, dir);
 224 }
 225
 226 /*
 227  * Divert a packet by passing it up to the divert socket at port 'port'.
 228  *
 229  * Setup generic address and protocol structures for div_input routine,
 230  * then pass them along with mbuf chain.
 231  */
 232 static void
 233 div_packet(struct mbuf *m, int incoming, int port)
 234 {
 235         struct sockaddr_in divsrc = { sizeof divsrc, AF_INET };
 236         struct inpcb *inp;
 237         struct socket *sa;
 238         struct m_tag *mtag;
 239         struct divert_info *divinfo;
 240         u_int16_t nport;
 241
 242         /* Locate the divert info */
 243         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 244         divinfo = m_tag_data(mtag);
 245         divsrc.sin_port = divinfo->skipto;
 246
 247         /*
 248          * Record receive interface address, if any.
 249          * But only for incoming packets.
 250          */
 251         divsrc.sin_addr.s_addr = 0;
 252         if (incoming) {
 253                 struct ifaddr_container *ifac;
 254
 255                 /* Find IP address for receive interface */
 256                 TAILQ_FOREACH(ifac, &m->m_pkthdr.rcvif->if_addrheads[mycpuid],
 257                               ifa_link) {
 258                         struct ifaddr *ifa = ifac->ifa;
 259
 260                         if (ifa->ifa_addr == NULL)
 261                                 continue;
 262                         if (ifa->ifa_addr->sa_family != AF_INET)
 263                                 continue;
 264                         divsrc.sin_addr =
 265                             ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
 266                         break;
 267                 }
 268         }
 269         /*
 270          * Record the incoming interface name whenever we have one.
 271          */
 272         if (m->m_pkthdr.rcvif) {
 273                 /*
 274                  * Hide the actual interface name in there in the
 275                  * sin_zero array. XXX This needs to be moved to a
 276                  * different sockaddr type for divert, e.g.
 277                  * sockaddr_div with multiple fields like
 278                  * sockaddr_dl. Presently we have only 7 bytes
 279                  * but that will do for now as most interfaces
 280                  * are 4 or less + 2 or less bytes for unit.
 281                  * There is probably a faster way of doing this,
 282                  * possibly taking it from the sockaddr_dl on the iface.
 283                  * This solves the problem of a P2P link and a LAN interface
 284                  * having the same address, which can result in the wrong
 285                  * interface being assigned to the packet when fed back
 286                  * into the divert socket. Theoretically if the daemon saves
 287                  * and re-uses the sockaddr_in as suggested in the man pages,
 288                  * this iface name will come along for the ride.
 289                  * (see div_output for the other half of this.)
 290                  */
 291                 ksnprintf(divsrc.sin_zero, sizeof divsrc.sin_zero,
 292                           m->m_pkthdr.rcvif->if_xname);
 293         }
 294
 295         /* Put packet on socket queue, if any */
 296         sa = NULL;
 297         nport = htons((u_int16_t)port);
 298
 299         /*
 300          * XXX
 301          * Following loop to locate the inpcb is MPSAFE since the inpcb
 302          * insertion/removal happens on the same CPU (CPU0), however,
 303          * saving/testing the socket pointer is not MPSAFE.  So we still
 304          * need to hold BGL here.
 305          */
 306         get_mplock();
 307         LIST_FOREACH(inp, &divcbinfo.pcblisthead, inp_list) {
 308                 if (inp->inp_flags & INP_PLACEMARKER)
 309                         continue;
 310                 if (inp->inp_lport == nport)
 311                         sa = inp->inp_socket;
 312         }
 313         if (sa) {
 314                 if (ssb_appendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc, m,
 315                                  (struct mbuf *)NULL) == 0)
 316                         m_freem(m);
 317                 else
 318                         sorwakeup(sa);
 319                 rel_mplock();
 320         } else {
 321                 rel_mplock();
 322                 m_freem(m);
 323                 ipstat.ips_noproto++;
 324                 ipstat.ips_delivered--;
 325         }
 326 }
 327
 328 #ifdef SMP
 329 static void
 330 div_packet_handler(struct netmsg *nmsg)
 331 {
 332         struct netmsg_packet *nmp;
 333         struct lwkt_msg *msg;
 334         struct mbuf *m;
 335         int port, incoming = 0;
 336
 337         nmp = (struct netmsg_packet *)nmsg;
 338         m = nmp->nm_packet;
 339
 340         msg = &nmsg->nm_lmsg;
 341         port = msg->u.ms_result32 & 0xffff;
 342         if (msg->u.ms_result32 & DIV_INPUT)
 343                 incoming = 1;
 344
 345         div_packet(m, incoming, port);
 346 }
 347 #endif  /* SMP */
 348
 349 static void
 350 divert_packet(struct mbuf *m, int incoming)
 351 {
 352         struct m_tag *mtag;
 353         struct divert_info *divinfo;
 354         int port;
 355
 356         M_ASSERTPKTHDR(m);
 357
 358         /* Assure header */
 359         if (m->m_len < sizeof(struct ip) &&
 360             (m = m_pullup(m, sizeof(struct ip))) == NULL)
 361                 return;
 362
 363         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 364         KASSERT(mtag != NULL, ("%s no divert tag!", __func__));
 365         divinfo = m_tag_data(mtag);
 366
 367         port = divinfo->port;
 368         KASSERT(port != 0, ("%s: port=0", __func__));
 369
 370 #ifdef SMP
 371         if (mycpuid != 0) {
 372                 struct netmsg_packet *nmp;
 373                 struct lwkt_msg *msg;
 374
 375                 nmp = &m->m_hdr.mh_netmsg;
 376                 netmsg_init(&nmp->nm_netmsg, &netisr_apanic_rport, MSGF_MPSAFE,
 377                             div_packet_handler);
 378                 nmp->nm_packet = m;
 379
 380                 msg = &nmp->nm_netmsg.nm_lmsg;
 381                 msg->u.ms_result32 = port; /* port is 16bits */
 382                 if (incoming)
 383                         msg->u.ms_result32 |= DIV_INPUT;
 384                 else
 385                         msg->u.ms_result32 |= DIV_OUTPUT;
 386
 387                 lwkt_sendmsg(cpu_portfn(0), &nmp->nm_netmsg.nm_lmsg);
 388         } else
 389 #endif
 390         div_packet(m, incoming, port);
 391 }
 392
 393 /*
 394  * Deliver packet back into the IP processing machinery.
 395  *
 396  * If no address specified, or address is 0.0.0.0, send to ip_output();
 397  * otherwise, send to ip_input() and mark as having been received on
 398  * the interface with that address.
 399  */
 400 static int
 401 div_output(struct socket *so, struct mbuf *m,
 402         struct sockaddr_in *sin, struct mbuf *control)
 403 {
 404         int error = 0;
 405         struct m_tag *mtag;
 406         struct divert_info *divinfo;
 407
 408         if (control)
 409                 m_freem(control);               /* XXX */
 410
 411         /*
 412          * Prepare the tag for divert info. Note that a packet
 413          * with a 0 tag in mh_data is effectively untagged,
 414          * so we could optimize that case.
 415          */
 416         mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, sizeof(*divinfo), MB_DONTWAIT);
 417         if (mtag == NULL) {
 418                 error = ENOBUFS;
 419                 goto cantsend;
 420         }
 421         m_tag_prepend(m, mtag);
 422
 423         /* Loopback avoidance and state recovery */
 424         divinfo = m_tag_data(mtag);
 425         if (sin)
 426                 divinfo->skipto = sin->sin_port;
 427         else
 428                 divinfo->skipto = 0;
 429
 430         /* Reinject packet into the system as incoming or outgoing */
 431         if (DIV_IS_OUTPUT(sin)) {
 432                 struct ip *const ip = mtod(m, struct ip *);
 433
 434                 /* Don't allow packet length sizes that will crash */
 435                 if ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len) {
 436                         error = EINVAL;
 437                         goto cantsend;
 438                 }
 439
 440                 /* Convert fields to host order for ip_output() */
 441                 ip->ip_len = ntohs(ip->ip_len);
 442                 ip->ip_off = ntohs(ip->ip_off);
 443
 444                 /* Send packet to output processing */
 445                 ipstat.ips_rawout++;                    /* XXX */
 446                 error = ip_output(m, NULL, NULL,
 447                             (so->so_options & SO_DONTROUTE) |
 448                             IP_ALLOWBROADCAST | IP_RAWOUTPUT,
 449                             NULL, NULL);
 450         } else {
 451                 ip_input(m);
 452         }
 453         return error;
 454
 455 cantsend:
 456         m_freem(m);
 457         return error;
 458 }
 459
 460 static int
 461 div_attach(struct socket *so, int proto, struct pru_attach_info *ai)
 462 {
 463         struct inpcb *inp;
 464         int error;
 465
 466         inp  = so->so_pcb;
 467         if (inp)
 468                 panic("div_attach");
 469         if ((error = suser_cred(ai->p_ucred, NULL_CRED_OKAY)) != 0)
 470                 return error;
 471
 472         error = soreserve(so, div_sendspace, div_recvspace, ai->sb_rlimit);
 473         if (error)
 474                 return error;
 475         error = in_pcballoc(so, &divcbinfo);
 476         if (error)
 477                 return error;
 478         inp = (struct inpcb *)so->so_pcb;
 479         inp->inp_ip_p = proto;
 480         inp->inp_vflag |= INP_IPV4;
 481         inp->inp_flags |= INP_HDRINCL;
 482         /*
 483          * The socket is always "connected" because
 484          * we always know "where" to send the packet.
 485          */
 486         so->so_state |= SS_ISCONNECTED;
 487         return 0;
 488 }
 489
 490 static int
 491 div_detach(struct socket *so)
 492 {
 493         struct inpcb *inp;
 494
 495         inp = so->so_pcb;
 496         if (inp == NULL)
 497                 panic("div_detach");
 498         in_pcbdetach(inp);
 499         return 0;
 500 }
 501
 502 static int
 503 div_abort(struct socket *so)
 504 {
 505         soisdisconnected(so);
 506         return div_detach(so);
 507 }
 508
 509 static int
 510 div_disconnect(struct socket *so)
 511 {
 512         if (!(so->so_state & SS_ISCONNECTED))
 513                 return ENOTCONN;
 514         return div_abort(so);
 515 }
 516
 517 static int
 518 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
 519 {
 520         int error;
 521
 522         /*
 523          * in_pcbbind assumes that nam is a sockaddr_in
 524          * and in_pcbbind requires a valid address. Since divert
 525          * sockets don't we need to make sure the address is
 526          * filled in properly.
 527          * XXX -- divert should not be abusing in_pcbind
 528          * and should probably have its own family.
 529          */
 530         if (nam->sa_family != AF_INET) {
 531                 error = EAFNOSUPPORT;
 532         } else {
 533                 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
 534                 error = in_pcbbind(so->so_pcb, nam, td);
 535         }
 536         return error;
 537 }
 538
 539 static int
 540 div_shutdown(struct socket *so)
 541 {
 542         socantsendmore(so);
 543         return 0;
 544 }
 545
 546 static int
 547 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
 548          struct mbuf *control, struct thread *td)
 549 {
 550         /* Length check already done in ip_mport() */
 551         KASSERT(m->m_len >= sizeof(struct ip), ("IP header not in one mbuf"));
 552
 553         /* Send packet */
 554         return div_output(so, m, (struct sockaddr_in *)nam, control);
 555 }
 556
 557 SYSCTL_DECL(_net_inet_divert);
 558 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, &divcbinfo, 0,
 559             in_pcblist_global, "S,xinpcb", "List of active divert sockets");
 560
 561 struct pr_usrreqs div_usrreqs = {
 562         .pru_abort = div_abort,
 563         .pru_accept = pru_accept_notsupp,
 564         .pru_attach = div_attach,
 565         .pru_bind = div_bind,
 566         .pru_connect = pru_connect_notsupp,
 567         .pru_connect2 = pru_connect2_notsupp,
 568         .pru_control = in_control,
 569         .pru_detach = div_detach,
 570         .pru_disconnect = div_disconnect,
 571         .pru_listen = pru_listen_notsupp,
 572         .pru_peeraddr = in_setpeeraddr,
 573         .pru_rcvd = pru_rcvd_notsupp,
 574         .pru_rcvoob = pru_rcvoob_notsupp,
 575         .pru_send = div_send,
 576         .pru_sense = pru_sense_null,
 577         .pru_shutdown = div_shutdown,
 578         .pru_sockaddr = in_setsockaddr,
 579         .pru_sosend = sosend,
 580         .pru_soreceive = soreceive,
 581         .pru_sopoll = sopoll
 582 };
 583
 584 static struct mbuf *
 585 ip_divert_out(struct mbuf *m, int tee)
 586 {
 587         struct mbuf *clone = NULL;
 588         struct ip *ip = mtod(m, struct ip *);
 589
 590         /* Clone packet if we're doing a 'tee' */
 591         if (tee)
 592                 clone = m_dup(m, MB_DONTWAIT);
 593
 594         /*
 595          * XXX
 596          * delayed checksums are not currently compatible
 597          * with divert sockets.
 598          */
 599         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 600                 in_delayed_cksum(m);
 601                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 602         }
 603
 604         /* Restore packet header fields to original values */
 605         ip->ip_len = htons(ip->ip_len);
 606         ip->ip_off = htons(ip->ip_off);
 607
 608         /* Deliver packet to divert input routine */
 609         divert_packet(m, 0);
 610
 611         /* If 'tee', continue with original packet */
 612         return clone;
 613 }
 614
 615 static struct mbuf *
 616 ip_divert_in(struct mbuf *m, int tee)
 617 {
 618         struct mbuf *clone = NULL;
 619         struct ip *ip = mtod(m, struct ip *);
 620         struct m_tag *mtag;
 621
 622         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 623                 const struct divert_info *divinfo;
 624                 u_short frag_off;
 625                 int hlen;
 626
 627                 /*
 628                  * Only trust divert info in the fragment
 629                  * at offset 0.
 630                  */
 631                 frag_off = ip->ip_off << 3;
 632                 if (frag_off != 0) {
 633                         mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 634                         m_tag_delete(m, mtag);
 635                 }
 636
 637                 /*
 638                  * Attempt reassembly; if it succeeds, proceed.
 639                  * ip_reass() will return a different mbuf.
 640                  */
 641                 m = ip_reass(m);
 642                 if (m == NULL)
 643                         return NULL;
 644                 ip = mtod(m, struct ip *);
 645
 646                 /* Caller need to redispatch the packet, if it is for us */
 647                 m->m_pkthdr.fw_flags |= FW_MBUF_REDISPATCH;
 648
 649                 /*
 650                  * Get the header length of the reassembled
 651                  * packet
 652                  */
 653                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 654
 655                 /*
 656                  * Restore original checksum before diverting
 657                  * packet
 658                  */
 659                 ip->ip_len += hlen;
 660                 ip->ip_len = htons(ip->ip_len);
 661                 ip->ip_off = htons(ip->ip_off);
 662                 ip->ip_sum = 0;
 663                 if (hlen == sizeof(struct ip))
 664                         ip->ip_sum = in_cksum_hdr(ip);
 665                 else
 666                         ip->ip_sum = in_cksum(m, hlen);
 667                 ip->ip_off = ntohs(ip->ip_off);
 668                 ip->ip_len = ntohs(ip->ip_len);
 669
 670                 /*
 671                  * Only use the saved divert info
 672                  */
 673                 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
 674                 if (mtag == NULL) {
 675                         /* Wrongly configured ipfw */
 676                         kprintf("ip_input no divert info\n");
 677                         m_freem(m);
 678                         return NULL;
 679                 }
 680                 divinfo = m_tag_data(mtag);
 681                 tee = divinfo->tee;
 682         }
 683
 684         /*
 685          * Divert or tee packet to the divert protocol if
 686          * required.
 687          */
 688
 689         /* Clone packet if we're doing a 'tee' */
 690         if (tee)
 691                 clone = m_dup(m, MB_DONTWAIT);
 692
 693         /*
 694          * Restore packet header fields to original
 695          * values
 696          */
 697         ip->ip_len = htons(ip->ip_len);
 698         ip->ip_off = htons(ip->ip_off);
 699
 700         /* Deliver packet to divert input routine */
 701         divert_packet(m, 1);
 702
 703         /* Catch invalid reference */
 704         m = NULL;
 705         ip = NULL;
 706
 707         ipstat.ips_delivered++;
 708
 709         /* If 'tee', continue with original packet */
 710         if (clone != NULL) {
 711                 /*
 712                  * Complete processing of the packet.
 713                  * XXX Better safe than sorry, remove the DIVERT tag.
 714                  */
 715                 mtag = m_tag_find(clone, PACKET_TAG_IPFW_DIVERT, NULL);
 716                 KKASSERT(mtag != NULL);
 717                 m_tag_delete(clone, mtag);
 718         }
 719         return clone;
 720 }
 721
 722 static struct mbuf *
 723 ip_divert(struct mbuf *m, int tee, int incoming)
 724 {
 725         struct mbuf *ret;
 726
 727         if (incoming)
 728                 ret = ip_divert_in(m, tee);
 729         else
 730                 ret = ip_divert_out(m, tee);
 731         return ret;
 732 }