The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_divert.c

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    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  * 4. 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 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD$");
   32 
   33 #include "opt_inet.h"
   34 #include "opt_inet6.h"
   35 #include "opt_sctp.h"
   36 #ifndef INET
   37 #error "IPDIVERT requires INET"
   38 #endif
   39 
   40 #include <sys/param.h>
   41 #include <sys/eventhandler.h>
   42 #include <sys/kernel.h>
   43 #include <sys/lock.h>
   44 #include <sys/malloc.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/module.h>
   47 #include <sys/kernel.h>
   48 #include <sys/priv.h>
   49 #include <sys/proc.h>
   50 #include <sys/protosw.h>
   51 #include <sys/socket.h>
   52 #include <sys/socketvar.h>
   53 #include <sys/sysctl.h>
   54 #include <net/vnet.h>
   55 
   56 #include <net/if.h>
   57 #include <net/if_var.h>
   58 #include <net/netisr.h> 
   59 
   60 #include <netinet/in.h>
   61 #include <netinet/in_pcb.h>
   62 #include <netinet/in_systm.h>
   63 #include <netinet/in_var.h>
   64 #include <netinet/ip.h>
   65 #include <netinet/ip_var.h>
   66 #ifdef INET6
   67 #include <netinet/ip6.h>
   68 #include <netinet6/ip6_var.h>
   69 #endif
   70 #ifdef SCTP
   71 #include <netinet/sctp_crc32.h>
   72 #endif
   73 
   74 #include <security/mac/mac_framework.h>
   75 
   76 /*
   77  * Divert sockets
   78  */
   79 
   80 /*
   81  * Allocate enough space to hold a full IP packet
   82  */
   83 #define DIVSNDQ         (65536 + 100)
   84 #define DIVRCVQ         (65536 + 100)
   85 
   86 /*
   87  * Divert sockets work in conjunction with ipfw or other packet filters,
   88  * see the divert(4) manpage for features.
   89  * Packets are selected by the packet filter and tagged with an
   90  * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
   91  * the packet filter) and information on the matching filter rule for
   92  * subsequent reinjection. The divert_port is used to put the packet
   93  * on the corresponding divert socket, while the rule number is passed
   94  * up (at least partially) as the sin_port in the struct sockaddr.
   95  *
   96  * Packets written to the divert socket carry in sin_addr a
   97  * destination address, and in sin_port the number of the filter rule
   98  * after which to continue processing.
   99  * If the destination address is INADDR_ANY, the packet is treated as
  100  * as outgoing and sent to ip_output(); otherwise it is treated as
  101  * incoming and sent to ip_input().
  102  * Further, sin_zero carries some information on the interface,
  103  * which can be used in the reinject -- see comments in the code.
  104  *
  105  * On reinjection, processing in ip_input() and ip_output()
  106  * will be exactly the same as for the original packet, except that
  107  * packet filter processing will start at the rule number after the one
  108  * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
  109  * will apply the entire ruleset to the packet).
  110  */
  111 
  112 /* Internal variables. */
  113 static VNET_DEFINE(struct inpcbhead, divcb);
  114 static VNET_DEFINE(struct inpcbinfo, divcbinfo);
  115 
  116 #define V_divcb                         VNET(divcb)
  117 #define V_divcbinfo                     VNET(divcbinfo)
  118 
  119 static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
  120 static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
  121 
  122 static eventhandler_tag ip_divert_event_tag;
  123 
  124 /*
  125  * Initialize divert connection block queue.
  126  */
  127 static void
  128 div_zone_change(void *tag)
  129 {
  130 
  131         uma_zone_set_max(V_divcbinfo.ipi_zone, maxsockets);
  132 }
  133 
  134 static int
  135 div_inpcb_init(void *mem, int size, int flags)
  136 {
  137         struct inpcb *inp = mem;
  138 
  139         INP_LOCK_INIT(inp, "inp", "divinp");
  140         return (0);
  141 }
  142 
  143 static void
  144 div_inpcb_fini(void *mem, int size)
  145 {
  146         struct inpcb *inp = mem;
  147 
  148         INP_LOCK_DESTROY(inp);
  149 }
  150 
  151 static void
  152 div_init(void)
  153 {
  154 
  155         /*
  156          * XXX We don't use the hash list for divert IP, but it's easier to
  157          * allocate one-entry hash lists than it is to check all over the
  158          * place for hashbase == NULL.
  159          */
  160         in_pcbinfo_init(&V_divcbinfo, "div", &V_divcb, 1, 1, "divcb",
  161             div_inpcb_init, div_inpcb_fini, 0, IPI_HASHFIELDS_NONE);
  162 }
  163 
  164 static void
  165 div_destroy(void *unused __unused)
  166 {
  167 
  168         in_pcbinfo_destroy(&V_divcbinfo);
  169 }
  170 VNET_SYSUNINIT(divert, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
  171     div_destroy, NULL);
  172 
  173 /*
  174  * IPPROTO_DIVERT is not in the real IP protocol number space; this
  175  * function should never be called.  Just in case, drop any packets.
  176  */
  177 static int
  178 div_input(struct mbuf **mp, int *offp, int proto)
  179 {
  180         struct mbuf *m = *mp;
  181 
  182         KMOD_IPSTAT_INC(ips_noproto);
  183         m_freem(m);
  184         return (IPPROTO_DONE);
  185 }
  186 
  187 /*
  188  * Divert a packet by passing it up to the divert socket at port 'port'.
  189  *
  190  * Setup generic address and protocol structures for div_input routine,
  191  * then pass them along with mbuf chain.
  192  */
  193 static void
  194 divert_packet(struct mbuf *m, int incoming)
  195 {
  196         struct ip *ip;
  197         struct inpcb *inp;
  198         struct socket *sa;
  199         u_int16_t nport;
  200         struct sockaddr_in divsrc;
  201         struct m_tag *mtag;
  202 
  203         mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
  204         if (mtag == NULL) {
  205                 m_freem(m);
  206                 return;
  207         }
  208         /* Assure header */
  209         if (m->m_len < sizeof(struct ip) &&
  210             (m = m_pullup(m, sizeof(struct ip))) == NULL)
  211                 return;
  212         ip = mtod(m, struct ip *);
  213 
  214         /* Delayed checksums are currently not compatible with divert. */
  215         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  216                 in_delayed_cksum(m);
  217                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  218         }
  219 #ifdef SCTP
  220         if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
  221                 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
  222                 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
  223         }
  224 #endif
  225         bzero(&divsrc, sizeof(divsrc));
  226         divsrc.sin_len = sizeof(divsrc);
  227         divsrc.sin_family = AF_INET;
  228         /* record matching rule, in host format */
  229         divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
  230         /*
  231          * Record receive interface address, if any.
  232          * But only for incoming packets.
  233          */
  234         if (incoming) {
  235                 struct ifaddr *ifa;
  236                 struct ifnet *ifp;
  237 
  238                 /* Sanity check */
  239                 M_ASSERTPKTHDR(m);
  240 
  241                 /* Find IP address for receive interface */
  242                 ifp = m->m_pkthdr.rcvif;
  243                 if_addr_rlock(ifp);
  244                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  245                         if (ifa->ifa_addr->sa_family != AF_INET)
  246                                 continue;
  247                         divsrc.sin_addr =
  248                             ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
  249                         break;
  250                 }
  251                 if_addr_runlock(ifp);
  252         }
  253         /*
  254          * Record the incoming interface name whenever we have one.
  255          */
  256         if (m->m_pkthdr.rcvif) {
  257                 /*
  258                  * Hide the actual interface name in there in the 
  259                  * sin_zero array. XXX This needs to be moved to a
  260                  * different sockaddr type for divert, e.g.
  261                  * sockaddr_div with multiple fields like 
  262                  * sockaddr_dl. Presently we have only 7 bytes
  263                  * but that will do for now as most interfaces
  264                  * are 4 or less + 2 or less bytes for unit.
  265                  * There is probably a faster way of doing this,
  266                  * possibly taking it from the sockaddr_dl on the iface.
  267                  * This solves the problem of a P2P link and a LAN interface
  268                  * having the same address, which can result in the wrong
  269                  * interface being assigned to the packet when fed back
  270                  * into the divert socket. Theoretically if the daemon saves
  271                  * and re-uses the sockaddr_in as suggested in the man pages,
  272                  * this iface name will come along for the ride.
  273                  * (see div_output for the other half of this.)
  274                  */ 
  275                 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
  276                     sizeof(divsrc.sin_zero));
  277         }
  278 
  279         /* Put packet on socket queue, if any */
  280         sa = NULL;
  281         nport = htons((u_int16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
  282         INP_INFO_RLOCK(&V_divcbinfo);
  283         LIST_FOREACH(inp, &V_divcb, inp_list) {
  284                 /* XXX why does only one socket match? */
  285                 if (inp->inp_lport == nport) {
  286                         INP_RLOCK(inp);
  287                         sa = inp->inp_socket;
  288                         SOCKBUF_LOCK(&sa->so_rcv);
  289                         if (sbappendaddr_locked(&sa->so_rcv,
  290                             (struct sockaddr *)&divsrc, m,
  291                             (struct mbuf *)0) == 0) {
  292                                 SOCKBUF_UNLOCK(&sa->so_rcv);
  293                                 sa = NULL;      /* force mbuf reclaim below */
  294                         } else
  295                                 sorwakeup_locked(sa);
  296                         INP_RUNLOCK(inp);
  297                         break;
  298                 }
  299         }
  300         INP_INFO_RUNLOCK(&V_divcbinfo);
  301         if (sa == NULL) {
  302                 m_freem(m);
  303                 KMOD_IPSTAT_INC(ips_noproto);
  304                 KMOD_IPSTAT_DEC(ips_delivered);
  305         }
  306 }
  307 
  308 /*
  309  * Deliver packet back into the IP processing machinery.
  310  *
  311  * If no address specified, or address is 0.0.0.0, send to ip_output();
  312  * otherwise, send to ip_input() and mark as having been received on
  313  * the interface with that address.
  314  */
  315 static int
  316 div_output(struct socket *so, struct mbuf *m, struct sockaddr_in *sin,
  317     struct mbuf *control)
  318 {
  319         struct ip *const ip = mtod(m, struct ip *);
  320         struct m_tag *mtag;
  321         struct ipfw_rule_ref *dt;
  322         int error = 0;
  323 
  324         /*
  325          * An mbuf may hasn't come from userland, but we pretend
  326          * that it has.
  327          */
  328         m->m_pkthdr.rcvif = NULL;
  329         m->m_nextpkt = NULL;
  330         M_SETFIB(m, so->so_fibnum);
  331 
  332         if (control)
  333                 m_freem(control);               /* XXX */
  334 
  335         mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
  336         if (mtag == NULL) {
  337                 /* this should be normal */
  338                 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
  339                     sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
  340                 if (mtag == NULL) {
  341                         error = ENOBUFS;
  342                         goto cantsend;
  343                 }
  344                 m_tag_prepend(m, mtag);
  345         }
  346         dt = (struct ipfw_rule_ref *)(mtag+1);
  347 
  348         /* Loopback avoidance and state recovery */
  349         if (sin) {
  350                 int i;
  351 
  352                 /* set the starting point. We provide a non-zero slot,
  353                  * but a non_matching chain_id to skip that info and use
  354                  * the rulenum/rule_id.
  355                  */
  356                 dt->slot = 1; /* dummy, chain_id is invalid */
  357                 dt->chain_id = 0;
  358                 dt->rulenum = sin->sin_port+1; /* host format ? */
  359                 dt->rule_id = 0;
  360                 /*
  361                  * Find receive interface with the given name, stuffed
  362                  * (if it exists) in the sin_zero[] field.
  363                  * The name is user supplied data so don't trust its size
  364                  * or that it is zero terminated.
  365                  */
  366                 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
  367                         ;
  368                 if ( i > 0 && i < sizeof(sin->sin_zero))
  369                         m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
  370         }
  371 
  372         /* Reinject packet into the system as incoming or outgoing */
  373         if (!sin || sin->sin_addr.s_addr == 0) {
  374                 struct mbuf *options = NULL;
  375                 struct inpcb *inp;
  376 
  377                 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
  378                 inp = sotoinpcb(so);
  379                 INP_RLOCK(inp);
  380                 switch (ip->ip_v) {
  381                 case IPVERSION:
  382                         /*
  383                          * Don't allow both user specified and setsockopt
  384                          * options, and don't allow packet length sizes that
  385                          * will crash.
  386                          */
  387                         if ((((ip->ip_hl << 2) != sizeof(struct ip)) &&
  388                             inp->inp_options != NULL) ||
  389                             ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
  390                                 error = EINVAL;
  391                                 INP_RUNLOCK(inp);
  392                                 goto cantsend;
  393                         }
  394                         break;
  395 #ifdef INET6
  396                 case IPV6_VERSION >> 4:
  397                     {
  398                         struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
  399 
  400                         /* Don't allow packet length sizes that will crash */
  401                         if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
  402                                 error = EINVAL;
  403                                 INP_RUNLOCK(inp);
  404                                 goto cantsend;
  405                         }
  406                         break;
  407                     }
  408 #endif
  409                 default:
  410                         error = EINVAL;
  411                         INP_RUNLOCK(inp);
  412                         goto cantsend;
  413                 }
  414 
  415                 /* Send packet to output processing */
  416                 KMOD_IPSTAT_INC(ips_rawout);            /* XXX */
  417 
  418 #ifdef MAC
  419                 mac_inpcb_create_mbuf(inp, m);
  420 #endif
  421                 /*
  422                  * Get ready to inject the packet into ip_output().
  423                  * Just in case socket options were specified on the
  424                  * divert socket, we duplicate them.  This is done
  425                  * to avoid having to hold the PCB locks over the call
  426                  * to ip_output(), as doing this results in a number of
  427                  * lock ordering complexities.
  428                  *
  429                  * Note that we set the multicast options argument for
  430                  * ip_output() to NULL since it should be invariant that
  431                  * they are not present.
  432                  */
  433                 KASSERT(inp->inp_moptions == NULL,
  434                     ("multicast options set on a divert socket"));
  435                 /*
  436                  * XXXCSJP: It is unclear to me whether or not it makes
  437                  * sense for divert sockets to have options.  However,
  438                  * for now we will duplicate them with the INP locks
  439                  * held so we can use them in ip_output() without
  440                  * requring a reference to the pcb.
  441                  */
  442                 if (inp->inp_options != NULL) {
  443                         options = m_dup(inp->inp_options, M_NOWAIT);
  444                         if (options == NULL) {
  445                                 INP_RUNLOCK(inp);
  446                                 error = ENOBUFS;
  447                                 goto cantsend;
  448                         }
  449                 }
  450                 INP_RUNLOCK(inp);
  451 
  452                 switch (ip->ip_v) {
  453                 case IPVERSION:
  454                         error = ip_output(m, options, NULL,
  455                             ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
  456                             | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
  457                         break;
  458 #ifdef INET6
  459                 case IPV6_VERSION >> 4:
  460                         error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
  461                         break;
  462 #endif
  463                 }
  464                 if (options != NULL)
  465                         m_freem(options);
  466         } else {
  467                 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
  468                 if (m->m_pkthdr.rcvif == NULL) {
  469                         /*
  470                          * No luck with the name, check by IP address.
  471                          * Clear the port and the ifname to make sure
  472                          * there are no distractions for ifa_ifwithaddr.
  473                          */
  474                         struct  ifaddr *ifa;
  475 
  476                         bzero(sin->sin_zero, sizeof(sin->sin_zero));
  477                         sin->sin_port = 0;
  478                         ifa = ifa_ifwithaddr((struct sockaddr *) sin);
  479                         if (ifa == NULL) {
  480                                 error = EADDRNOTAVAIL;
  481                                 goto cantsend;
  482                         }
  483                         m->m_pkthdr.rcvif = ifa->ifa_ifp;
  484                         ifa_free(ifa);
  485                 }
  486 #ifdef MAC
  487                 mac_socket_create_mbuf(so, m);
  488 #endif
  489                 /* Send packet to input processing via netisr */
  490                 switch (ip->ip_v) {
  491                 case IPVERSION:
  492                         /*
  493                          * Restore M_BCAST flag when destination address is
  494                          * broadcast. It is expected by ip_tryforward().
  495                          */
  496                         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
  497                                 m->m_flags |= M_MCAST;
  498                         else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
  499                                 m->m_flags |= M_BCAST;
  500                         netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
  501                         break;
  502 #ifdef INET6
  503                 case IPV6_VERSION >> 4:
  504                         netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
  505                         break;
  506 #endif
  507                 default:
  508                         error = EINVAL;
  509                         goto cantsend;
  510                 }
  511         }
  512 
  513         return (error);
  514 
  515 cantsend:
  516         m_freem(m);
  517         return (error);
  518 }
  519 
  520 static int
  521 div_attach(struct socket *so, int proto, struct thread *td)
  522 {
  523         struct inpcb *inp;
  524         int error;
  525 
  526         inp  = sotoinpcb(so);
  527         KASSERT(inp == NULL, ("div_attach: inp != NULL"));
  528         if (td != NULL) {
  529                 error = priv_check(td, PRIV_NETINET_DIVERT);
  530                 if (error)
  531                         return (error);
  532         }
  533         error = soreserve(so, div_sendspace, div_recvspace);
  534         if (error)
  535                 return error;
  536         INP_INFO_WLOCK(&V_divcbinfo);
  537         error = in_pcballoc(so, &V_divcbinfo);
  538         if (error) {
  539                 INP_INFO_WUNLOCK(&V_divcbinfo);
  540                 return error;
  541         }
  542         inp = (struct inpcb *)so->so_pcb;
  543         INP_INFO_WUNLOCK(&V_divcbinfo);
  544         inp->inp_ip_p = proto;
  545         inp->inp_vflag |= INP_IPV4;
  546         inp->inp_flags |= INP_HDRINCL;
  547         INP_WUNLOCK(inp);
  548         return 0;
  549 }
  550 
  551 static void
  552 div_detach(struct socket *so)
  553 {
  554         struct inpcb *inp;
  555 
  556         inp = sotoinpcb(so);
  557         KASSERT(inp != NULL, ("div_detach: inp == NULL"));
  558         INP_INFO_WLOCK(&V_divcbinfo);
  559         INP_WLOCK(inp);
  560         in_pcbdetach(inp);
  561         in_pcbfree(inp);
  562         INP_INFO_WUNLOCK(&V_divcbinfo);
  563 }
  564 
  565 static int
  566 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
  567 {
  568         struct inpcb *inp;
  569         int error;
  570 
  571         inp = sotoinpcb(so);
  572         KASSERT(inp != NULL, ("div_bind: inp == NULL"));
  573         /* in_pcbbind assumes that nam is a sockaddr_in
  574          * and in_pcbbind requires a valid address. Since divert
  575          * sockets don't we need to make sure the address is
  576          * filled in properly.
  577          * XXX -- divert should not be abusing in_pcbind
  578          * and should probably have its own family.
  579          */
  580         if (nam->sa_family != AF_INET)
  581                 return EAFNOSUPPORT;
  582         ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
  583         INP_INFO_WLOCK(&V_divcbinfo);
  584         INP_WLOCK(inp);
  585         INP_HASH_WLOCK(&V_divcbinfo);
  586         error = in_pcbbind(inp, nam, td->td_ucred);
  587         INP_HASH_WUNLOCK(&V_divcbinfo);
  588         INP_WUNLOCK(inp);
  589         INP_INFO_WUNLOCK(&V_divcbinfo);
  590         return error;
  591 }
  592 
  593 static int
  594 div_shutdown(struct socket *so)
  595 {
  596         struct inpcb *inp;
  597 
  598         inp = sotoinpcb(so);
  599         KASSERT(inp != NULL, ("div_shutdown: inp == NULL"));
  600         INP_WLOCK(inp);
  601         socantsendmore(so);
  602         INP_WUNLOCK(inp);
  603         return 0;
  604 }
  605 
  606 static int
  607 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
  608     struct mbuf *control, struct thread *td)
  609 {
  610 
  611         /* Packet must have a header (but that's about it) */
  612         if (m->m_len < sizeof (struct ip) &&
  613             (m = m_pullup(m, sizeof (struct ip))) == NULL) {
  614                 KMOD_IPSTAT_INC(ips_toosmall);
  615                 m_freem(m);
  616                 return EINVAL;
  617         }
  618 
  619         /* Send packet */
  620         return div_output(so, m, (struct sockaddr_in *)nam, control);
  621 }
  622 
  623 static void
  624 div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
  625 {
  626         struct in_addr faddr;
  627 
  628         faddr = ((struct sockaddr_in *)sa)->sin_addr;
  629         if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
  630                 return;
  631         if (PRC_IS_REDIRECT(cmd))
  632                 return;
  633 }
  634 
  635 static int
  636 div_pcblist(SYSCTL_HANDLER_ARGS)
  637 {
  638         int error, i, n;
  639         struct inpcb *inp, **inp_list;
  640         inp_gen_t gencnt;
  641         struct xinpgen xig;
  642 
  643         /*
  644          * The process of preparing the TCB list is too time-consuming and
  645          * resource-intensive to repeat twice on every request.
  646          */
  647         if (req->oldptr == 0) {
  648                 n = V_divcbinfo.ipi_count;
  649                 n += imax(n / 8, 10);
  650                 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
  651                 return 0;
  652         }
  653 
  654         if (req->newptr != 0)
  655                 return EPERM;
  656 
  657         /*
  658          * OK, now we're committed to doing something.
  659          */
  660         INP_INFO_RLOCK(&V_divcbinfo);
  661         gencnt = V_divcbinfo.ipi_gencnt;
  662         n = V_divcbinfo.ipi_count;
  663         INP_INFO_RUNLOCK(&V_divcbinfo);
  664 
  665         error = sysctl_wire_old_buffer(req,
  666             2 * sizeof(xig) + n*sizeof(struct xinpcb));
  667         if (error != 0)
  668                 return (error);
  669 
  670         bzero(&xig, sizeof(xig));
  671         xig.xig_len = sizeof xig;
  672         xig.xig_count = n;
  673         xig.xig_gen = gencnt;
  674         xig.xig_sogen = so_gencnt;
  675         error = SYSCTL_OUT(req, &xig, sizeof xig);
  676         if (error)
  677                 return error;
  678 
  679         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
  680         if (inp_list == NULL)
  681                 return ENOMEM;
  682         
  683         INP_INFO_RLOCK(&V_divcbinfo);
  684         for (inp = LIST_FIRST(V_divcbinfo.ipi_listhead), i = 0; inp && i < n;
  685              inp = LIST_NEXT(inp, inp_list)) {
  686                 INP_WLOCK(inp);
  687                 if (inp->inp_gencnt <= gencnt &&
  688                     cr_canseeinpcb(req->td->td_ucred, inp) == 0) {
  689                         in_pcbref(inp);
  690                         inp_list[i++] = inp;
  691                 }
  692                 INP_WUNLOCK(inp);
  693         }
  694         INP_INFO_RUNLOCK(&V_divcbinfo);
  695         n = i;
  696 
  697         error = 0;
  698         for (i = 0; i < n; i++) {
  699                 inp = inp_list[i];
  700                 INP_RLOCK(inp);
  701                 if (inp->inp_gencnt <= gencnt) {
  702                         struct xinpcb xi;
  703                         bzero(&xi, sizeof(xi));
  704                         xi.xi_len = sizeof xi;
  705                         /* XXX should avoid extra copy */
  706                         bcopy(inp, &xi.xi_inp, sizeof *inp);
  707                         if (inp->inp_socket)
  708                                 sotoxsocket(inp->inp_socket, &xi.xi_socket);
  709                         INP_RUNLOCK(inp);
  710                         error = SYSCTL_OUT(req, &xi, sizeof xi);
  711                 } else
  712                         INP_RUNLOCK(inp);
  713         }
  714         INP_INFO_WLOCK(&V_divcbinfo);
  715         for (i = 0; i < n; i++) {
  716                 inp = inp_list[i];
  717                 INP_RLOCK(inp);
  718                 if (!in_pcbrele_rlocked(inp))
  719                         INP_RUNLOCK(inp);
  720         }
  721         INP_INFO_WUNLOCK(&V_divcbinfo);
  722 
  723         if (!error) {
  724                 /*
  725                  * Give the user an updated idea of our state.
  726                  * If the generation differs from what we told
  727                  * her before, she knows that something happened
  728                  * while we were processing this request, and it
  729                  * might be necessary to retry.
  730                  */
  731                 INP_INFO_RLOCK(&V_divcbinfo);
  732                 xig.xig_gen = V_divcbinfo.ipi_gencnt;
  733                 xig.xig_sogen = so_gencnt;
  734                 xig.xig_count = V_divcbinfo.ipi_count;
  735                 INP_INFO_RUNLOCK(&V_divcbinfo);
  736                 error = SYSCTL_OUT(req, &xig, sizeof xig);
  737         }
  738         free(inp_list, M_TEMP);
  739         return error;
  740 }
  741 
  742 #ifdef SYSCTL_NODE
  743 static SYSCTL_NODE(_net_inet, IPPROTO_DIVERT, divert, CTLFLAG_RW, 0,
  744     "IPDIVERT");
  745 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLTYPE_OPAQUE | CTLFLAG_RD,
  746     NULL, 0, div_pcblist, "S,xinpcb", "List of active divert sockets");
  747 #endif
  748 
  749 struct pr_usrreqs div_usrreqs = {
  750         .pru_attach =           div_attach,
  751         .pru_bind =             div_bind,
  752         .pru_control =          in_control,
  753         .pru_detach =           div_detach,
  754         .pru_peeraddr =         in_getpeeraddr,
  755         .pru_send =             div_send,
  756         .pru_shutdown =         div_shutdown,
  757         .pru_sockaddr =         in_getsockaddr,
  758         .pru_sosetlabel =       in_pcbsosetlabel
  759 };
  760 
  761 struct protosw div_protosw = {
  762         .pr_type =              SOCK_RAW,
  763         .pr_protocol =          IPPROTO_DIVERT,
  764         .pr_flags =             PR_ATOMIC|PR_ADDR,
  765         .pr_input =             div_input,
  766         .pr_ctlinput =          div_ctlinput,
  767         .pr_ctloutput =         ip_ctloutput,
  768         .pr_init =              div_init,
  769         .pr_usrreqs =           &div_usrreqs
  770 };
  771 
  772 static int
  773 div_modevent(module_t mod, int type, void *unused)
  774 {
  775         int err = 0;
  776 
  777         switch (type) {
  778         case MOD_LOAD:
  779                 /*
  780                  * Protocol will be initialized by pf_proto_register().
  781                  * We don't have to register ip_protox because we are not
  782                  * a true IP protocol that goes over the wire.
  783                  */
  784                 err = pf_proto_register(PF_INET, &div_protosw);
  785                 if (err != 0)
  786                         return (err);
  787                 ip_divert_ptr = divert_packet;
  788                 ip_divert_event_tag = EVENTHANDLER_REGISTER(maxsockets_change,
  789                     div_zone_change, NULL, EVENTHANDLER_PRI_ANY);
  790                 break;
  791         case MOD_QUIESCE:
  792                 /*
  793                  * IPDIVERT may normally not be unloaded because of the
  794                  * potential race conditions.  Tell kldunload we can't be
  795                  * unloaded unless the unload is forced.
  796                  */
  797                 err = EPERM;
  798                 break;
  799         case MOD_UNLOAD:
  800                 /*
  801                  * Forced unload.
  802                  *
  803                  * Module ipdivert can only be unloaded if no sockets are
  804                  * connected.  Maybe this can be changed later to forcefully
  805                  * disconnect any open sockets.
  806                  *
  807                  * XXXRW: Note that there is a slight race here, as a new
  808                  * socket open request could be spinning on the lock and then
  809                  * we destroy the lock.
  810                  */
  811                 INP_INFO_WLOCK(&V_divcbinfo);
  812                 if (V_divcbinfo.ipi_count != 0) {
  813                         err = EBUSY;
  814                         INP_INFO_WUNLOCK(&V_divcbinfo);
  815                         break;
  816                 }
  817                 ip_divert_ptr = NULL;
  818                 err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
  819                 INP_INFO_WUNLOCK(&V_divcbinfo);
  820 #ifndef VIMAGE
  821                 div_destroy(NULL);
  822 #endif
  823                 EVENTHANDLER_DEREGISTER(maxsockets_change, ip_divert_event_tag);
  824                 break;
  825         default:
  826                 err = EOPNOTSUPP;
  827                 break;
  828         }
  829         return err;
  830 }
  831 
  832 static moduledata_t ipdivertmod = {
  833         "ipdivert",
  834         div_modevent,
  835         0
  836 };
  837 
  838 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
  839 MODULE_DEPEND(ipdivert, ipfw, 3, 3, 3);
  840 MODULE_VERSION(ipdivert, 1);

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