The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  * 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: releng/5.1/sys/netinet/ip_divert.c 113255 2003-04-08 14:25:47Z des $
   34  */
   35 
   36 #include "opt_inet.h"
   37 #include "opt_ipfw.h"
   38 #include "opt_ipdivert.h"
   39 #include "opt_ipsec.h"
   40 #include "opt_mac.h"
   41 
   42 #ifndef INET
   43 #error "IPDIVERT requires INET."
   44 #endif
   45 
   46 #include <sys/param.h>
   47 #include <sys/kernel.h>
   48 #include <sys/lock.h>
   49 #include <sys/malloc.h>
   50 #include <sys/mac.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/proc.h>
   53 #include <sys/protosw.h>
   54 #include <sys/signalvar.h>
   55 #include <sys/socket.h>
   56 #include <sys/socketvar.h>
   57 #include <sys/sx.h>
   58 #include <sys/sysctl.h>
   59 #include <sys/systm.h>
   60 
   61 #include <vm/uma.h>
   62 
   63 #include <net/if.h>
   64 #include <net/route.h>
   65 
   66 #include <netinet/in.h>
   67 #include <netinet/in_pcb.h>
   68 #include <netinet/in_systm.h>
   69 #include <netinet/in_var.h>
   70 #include <netinet/ip.h>
   71 #include <netinet/ip_var.h>
   72 
   73 /*
   74  * Divert sockets
   75  */
   76 
   77 /*
   78  * Allocate enough space to hold a full IP packet
   79  */
   80 #define DIVSNDQ         (65536 + 100)
   81 #define DIVRCVQ         (65536 + 100)
   82 
   83 /*
   84  * Divert sockets work in conjunction with ipfw, see the divert(4)
   85  * manpage for features.
   86  * Internally, packets selected by ipfw in ip_input() or ip_output(),
   87  * and never diverted before, are passed to the input queue of the
   88  * divert socket with a given 'divert_port' number (as specified in
   89  * the matching ipfw rule), and they are tagged with a 16 bit cookie
   90  * (representing the rule number of the matching ipfw rule), which
   91  * is passed to process reading from the socket.
   92  *
   93  * Packets written to the divert socket are again tagged with a cookie
   94  * (usually the same as above) and a destination address.
   95  * If the destination address is INADDR_ANY then the packet is
   96  * treated as outgoing and sent to ip_output(), otherwise it is
   97  * treated as incoming and sent to ip_input().
   98  * In both cases, the packet is tagged with the cookie.
   99  *
  100  * On reinjection, processing in ip_input() and ip_output()
  101  * will be exactly the same as for the original packet, except that
  102  * ipfw processing will start at the rule number after the one
  103  * written in the cookie (so, tagging a packet with a cookie of 0
  104  * will cause it to be effectively considered as a standard packet).
  105  */
  106 
  107 /* Internal variables */
  108 static struct inpcbhead divcb;
  109 static struct inpcbinfo divcbinfo;
  110 
  111 static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
  112 static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
  113 
  114 /* Optimization: have this preinitialized */
  115 static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };
  116 
  117 /*
  118  * Initialize divert connection block queue.
  119  */
  120 void
  121 div_init(void)
  122 {
  123         INP_INFO_LOCK_INIT(&divcbinfo, "div");
  124         LIST_INIT(&divcb);
  125         divcbinfo.listhead = &divcb;
  126         /*
  127          * XXX We don't use the hash list for divert IP, but it's easier
  128          * to allocate a one entry hash list than it is to check all
  129          * over the place for hashbase == NULL.
  130          */
  131         divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
  132         divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
  133         divcbinfo.ipi_zone = uma_zcreate("divcb", sizeof(struct inpcb),
  134             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  135         uma_zone_set_max(divcbinfo.ipi_zone, maxsockets);
  136 }
  137 
  138 /*
  139  * IPPROTO_DIVERT is not in the real IP protocol number space; this
  140  * function should never be called.  Just in case, drop any packets.
  141  */
  142 void
  143 div_input(struct mbuf *m, int off)
  144 {
  145         ipstat.ips_noproto++;
  146         m_freem(m);
  147 }
  148 
  149 /*
  150  * Divert a packet by passing it up to the divert socket at port 'port'.
  151  *
  152  * Setup generic address and protocol structures for div_input routine,
  153  * then pass them along with mbuf chain.
  154  */
  155 void
  156 divert_packet(struct mbuf *m, int incoming, int port, int rule)
  157 {
  158         struct ip *ip;
  159         struct inpcb *inp;
  160         struct socket *sa;
  161         u_int16_t nport;
  162 
  163         /* Sanity check */
  164         KASSERT(port != 0, ("%s: port=0", __func__));
  165 
  166         divsrc.sin_port = rule;         /* record matching rule */
  167 
  168         /* Assure header */
  169         if (m->m_len < sizeof(struct ip) &&
  170             (m = m_pullup(m, sizeof(struct ip))) == 0)
  171                 return;
  172         ip = mtod(m, struct ip *);
  173 
  174         /*
  175          * Record receive interface address, if any.
  176          * But only for incoming packets.
  177          */
  178         divsrc.sin_addr.s_addr = 0;
  179         if (incoming) {
  180                 struct ifaddr *ifa;
  181 
  182                 /* Sanity check */
  183                 M_ASSERTPKTHDR(m);
  184 
  185                 /* Find IP address for receive interface */
  186                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
  187                         if (ifa->ifa_addr == NULL)
  188                                 continue;
  189                         if (ifa->ifa_addr->sa_family != AF_INET)
  190                                 continue;
  191                         divsrc.sin_addr =
  192                             ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
  193                         break;
  194                 }
  195         }
  196         /*
  197          * Record the incoming interface name whenever we have one.
  198          */
  199         bzero(&divsrc.sin_zero, sizeof(divsrc.sin_zero));
  200         if (m->m_pkthdr.rcvif) {
  201                 /*
  202                  * Hide the actual interface name in there in the 
  203                  * sin_zero array. XXX This needs to be moved to a
  204                  * different sockaddr type for divert, e.g.
  205                  * sockaddr_div with multiple fields like 
  206                  * sockaddr_dl. Presently we have only 7 bytes
  207                  * but that will do for now as most interfaces
  208                  * are 4 or less + 2 or less bytes for unit.
  209                  * There is probably a faster way of doing this,
  210                  * possibly taking it from the sockaddr_dl on the iface.
  211                  * This solves the problem of a P2P link and a LAN interface
  212                  * having the same address, which can result in the wrong
  213                  * interface being assigned to the packet when fed back
  214                  * into the divert socket. Theoretically if the daemon saves
  215                  * and re-uses the sockaddr_in as suggested in the man pages,
  216                  * this iface name will come along for the ride.
  217                  * (see div_output for the other half of this.)
  218                  */ 
  219                 snprintf(divsrc.sin_zero, sizeof(divsrc.sin_zero),
  220                         "%s%d", m->m_pkthdr.rcvif->if_name,
  221                         m->m_pkthdr.rcvif->if_unit);
  222         }
  223 
  224         /* Put packet on socket queue, if any */
  225         sa = NULL;
  226         nport = htons((u_int16_t)port);
  227         LIST_FOREACH(inp, &divcb, inp_list) {
  228                 if (inp->inp_lport == nport)
  229                         sa = inp->inp_socket;
  230         }
  231         if (sa) {
  232                 if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,
  233                                 m, (struct mbuf *)0) == 0)
  234                         m_freem(m);
  235                 else
  236                         sorwakeup(sa);
  237         } else {
  238                 m_freem(m);
  239                 ipstat.ips_noproto++;
  240                 ipstat.ips_delivered--;
  241         }
  242 }
  243 
  244 /*
  245  * Deliver packet back into the IP processing machinery.
  246  *
  247  * If no address specified, or address is 0.0.0.0, send to ip_output();
  248  * otherwise, send to ip_input() and mark as having been received on
  249  * the interface with that address.
  250  */
  251 static int
  252 div_output(struct socket *so, struct mbuf *m,
  253         struct sockaddr_in *sin, struct mbuf *control)
  254 {
  255         int error = 0;
  256         struct m_hdr divert_tag;
  257 
  258         /*
  259          * Prepare the tag for divert info. Note that a packet
  260          * with a 0 tag in mh_data is effectively untagged,
  261          * so we could optimize that case.
  262          */
  263         divert_tag.mh_type = MT_TAG;
  264         divert_tag.mh_flags = PACKET_TAG_DIVERT;
  265         divert_tag.mh_next = m;
  266         divert_tag.mh_data = 0;         /* the matching rule # */
  267         m->m_pkthdr.rcvif = NULL;       /* XXX is it necessary ? */
  268 
  269 #ifdef MAC
  270         mac_create_mbuf_from_socket(so, m);
  271 #endif
  272 
  273         if (control)
  274                 m_freem(control);               /* XXX */
  275 
  276         /* Loopback avoidance and state recovery */
  277         if (sin) {
  278                 int i;
  279 
  280                 divert_tag.mh_data = (caddr_t)(uintptr_t)sin->sin_port;
  281                 /*
  282                  * Find receive interface with the given name, stuffed
  283                  * (if it exists) in the sin_zero[] field.
  284                  * The name is user supplied data so don't trust its size
  285                  * or that it is zero terminated.
  286                  */
  287                 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
  288                         ;
  289                 if ( i > 0 && i < sizeof(sin->sin_zero))
  290                         m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
  291         }
  292 
  293         /* Reinject packet into the system as incoming or outgoing */
  294         if (!sin || sin->sin_addr.s_addr == 0) {
  295                 struct inpcb *const inp = sotoinpcb(so);
  296                 struct ip *const ip = mtod(m, struct ip *);
  297 
  298                 /*
  299                  * Don't allow both user specified and setsockopt options,
  300                  * and don't allow packet length sizes that will crash
  301                  */
  302                 if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
  303                      ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
  304                         error = EINVAL;
  305                         goto cantsend;
  306                 }
  307 
  308                 /* Convert fields to host order for ip_output() */
  309                 ip->ip_len = ntohs(ip->ip_len);
  310                 ip->ip_off = ntohs(ip->ip_off);
  311 
  312                 /* Send packet to output processing */
  313                 ipstat.ips_rawout++;                    /* XXX */
  314                 error = ip_output((struct mbuf *)&divert_tag,
  315                             inp->inp_options, &inp->inp_route,
  316                             (so->so_options & SO_DONTROUTE) |
  317                             IP_ALLOWBROADCAST | IP_RAWOUTPUT,
  318                             inp->inp_moptions, NULL);
  319         } else {
  320                 if (m->m_pkthdr.rcvif == NULL) {
  321                         /*
  322                          * No luck with the name, check by IP address.
  323                          * Clear the port and the ifname to make sure
  324                          * there are no distractions for ifa_ifwithaddr.
  325                          */
  326                         struct  ifaddr *ifa;
  327 
  328                         bzero(sin->sin_zero, sizeof(sin->sin_zero));
  329                         sin->sin_port = 0;
  330                         ifa = ifa_ifwithaddr((struct sockaddr *) sin);
  331                         if (ifa == NULL) {
  332                                 error = EADDRNOTAVAIL;
  333                                 goto cantsend;
  334                         }
  335                         m->m_pkthdr.rcvif = ifa->ifa_ifp;
  336                 }
  337                 /* Send packet to input processing */
  338                 ip_input((struct mbuf *)&divert_tag);
  339         }
  340 
  341         return error;
  342 
  343 cantsend:
  344         m_freem(m);
  345         return error;
  346 }
  347 
  348 static int
  349 div_attach(struct socket *so, int proto, struct thread *td)
  350 {
  351         struct inpcb *inp;
  352         int error, s;
  353 
  354         inp  = sotoinpcb(so);
  355         if (inp)
  356                 panic("div_attach");
  357         if (td && (error = suser(td)) != 0)
  358                 return error;
  359 
  360         error = soreserve(so, div_sendspace, div_recvspace);
  361         if (error)
  362                 return error;
  363         s = splnet();
  364         error = in_pcballoc(so, &divcbinfo, td);
  365         splx(s);
  366         if (error)
  367                 return error;
  368         inp = (struct inpcb *)so->so_pcb;
  369         inp->inp_ip_p = proto;
  370         inp->inp_vflag |= INP_IPV4;
  371         inp->inp_flags |= INP_HDRINCL;
  372         /* The socket is always "connected" because
  373            we always know "where" to send the packet */
  374         so->so_state |= SS_ISCONNECTED;
  375         return 0;
  376 }
  377 
  378 static int
  379 div_detach(struct socket *so)
  380 {
  381         struct inpcb *inp;
  382 
  383         inp = sotoinpcb(so);
  384         if (inp == 0)
  385                 panic("div_detach");
  386         in_pcbdetach(inp);
  387         return 0;
  388 }
  389 
  390 static int
  391 div_abort(struct socket *so)
  392 {
  393         soisdisconnected(so);
  394         return div_detach(so);
  395 }
  396 
  397 static int
  398 div_disconnect(struct socket *so)
  399 {
  400         if ((so->so_state & SS_ISCONNECTED) == 0)
  401                 return ENOTCONN;
  402         return div_abort(so);
  403 }
  404 
  405 static int
  406 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
  407 {
  408         struct inpcb *inp;
  409         int s;
  410         int error;
  411 
  412         s = splnet();
  413         inp = sotoinpcb(so);
  414         /* in_pcbbind assumes that nam is a sockaddr_in
  415          * and in_pcbbind requires a valid address. Since divert
  416          * sockets don't we need to make sure the address is
  417          * filled in properly.
  418          * XXX -- divert should not be abusing in_pcbind
  419          * and should probably have its own family.
  420          */
  421         if (nam->sa_family != AF_INET)
  422                 error = EAFNOSUPPORT;
  423         else {
  424                 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
  425                 error = in_pcbbind(inp, nam, td);
  426         }
  427         splx(s);
  428         return error;
  429 }
  430 
  431 static int
  432 div_shutdown(struct socket *so)
  433 {
  434         socantsendmore(so);
  435         return 0;
  436 }
  437 
  438 static int
  439 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
  440          struct mbuf *control, struct thread *td)
  441 {
  442         /* Packet must have a header (but that's about it) */
  443         if (m->m_len < sizeof (struct ip) &&
  444             (m = m_pullup(m, sizeof (struct ip))) == 0) {
  445                 ipstat.ips_toosmall++;
  446                 m_freem(m);
  447                 return EINVAL;
  448         }
  449 
  450         /* Send packet */
  451         return div_output(so, m, (struct sockaddr_in *)nam, control);
  452 }
  453 
  454 static int
  455 div_pcblist(SYSCTL_HANDLER_ARGS)
  456 {
  457         int error, i, n, s;
  458         struct inpcb *inp, **inp_list;
  459         inp_gen_t gencnt;
  460         struct xinpgen xig;
  461 
  462         /*
  463          * The process of preparing the TCB list is too time-consuming and
  464          * resource-intensive to repeat twice on every request.
  465          */
  466         if (req->oldptr == 0) {
  467                 n = divcbinfo.ipi_count;
  468                 req->oldidx = 2 * (sizeof xig)
  469                         + (n + n/8) * sizeof(struct xinpcb);
  470                 return 0;
  471         }
  472 
  473         if (req->newptr != 0)
  474                 return EPERM;
  475 
  476         /*
  477          * OK, now we're committed to doing something.
  478          */
  479         s = splnet();
  480         gencnt = divcbinfo.ipi_gencnt;
  481         n = divcbinfo.ipi_count;
  482         splx(s);
  483 
  484         xig.xig_len = sizeof xig;
  485         xig.xig_count = n;
  486         xig.xig_gen = gencnt;
  487         xig.xig_sogen = so_gencnt;
  488         error = SYSCTL_OUT(req, &xig, sizeof xig);
  489         if (error)
  490                 return error;
  491 
  492         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
  493         if (inp_list == 0)
  494                 return ENOMEM;
  495         
  496         s = splnet();
  497         for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
  498              inp = LIST_NEXT(inp, inp_list)) {
  499                 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->td, inp))
  500                         inp_list[i++] = inp;
  501         }
  502         splx(s);
  503         n = i;
  504 
  505         error = 0;
  506         for (i = 0; i < n; i++) {
  507                 inp = inp_list[i];
  508                 if (inp->inp_gencnt <= gencnt) {
  509                         struct xinpcb xi;
  510                         xi.xi_len = sizeof xi;
  511                         /* XXX should avoid extra copy */
  512                         bcopy(inp, &xi.xi_inp, sizeof *inp);
  513                         if (inp->inp_socket)
  514                                 sotoxsocket(inp->inp_socket, &xi.xi_socket);
  515                         error = SYSCTL_OUT(req, &xi, sizeof xi);
  516                 }
  517         }
  518         if (!error) {
  519                 /*
  520                  * Give the user an updated idea of our state.
  521                  * If the generation differs from what we told
  522                  * her before, she knows that something happened
  523                  * while we were processing this request, and it
  524                  * might be necessary to retry.
  525                  */
  526                 s = splnet();
  527                 xig.xig_gen = divcbinfo.ipi_gencnt;
  528                 xig.xig_sogen = so_gencnt;
  529                 xig.xig_count = divcbinfo.ipi_count;
  530                 splx(s);
  531                 error = SYSCTL_OUT(req, &xig, sizeof xig);
  532         }
  533         free(inp_list, M_TEMP);
  534         return error;
  535 }
  536 
  537 /*
  538  * This is the wrapper function for in_setsockaddr.  We just pass down
  539  * the pcbinfo for in_setpeeraddr to lock.
  540  */
  541 static int
  542 div_sockaddr(struct socket *so, struct sockaddr **nam)
  543 {
  544         return (in_setsockaddr(so, nam, &divcbinfo));
  545 }
  546 
  547 /*
  548  * This is the wrapper function for in_setpeeraddr. We just pass down
  549  * the pcbinfo for in_setpeeraddr to lock.
  550  */
  551 static int
  552 div_peeraddr(struct socket *so, struct sockaddr **nam)
  553 {
  554         return (in_setpeeraddr(so, nam, &divcbinfo));
  555 }
  556 
  557 
  558 SYSCTL_DECL(_net_inet_divert);
  559 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
  560             div_pcblist, "S,xinpcb", "List of active divert sockets");
  561 
  562 struct pr_usrreqs div_usrreqs = {
  563         div_abort, pru_accept_notsupp, div_attach, div_bind,
  564         pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
  565         div_disconnect, pru_listen_notsupp, div_peeraddr, pru_rcvd_notsupp,
  566         pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
  567         div_sockaddr, sosend, soreceive, sopoll
  568 };

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