FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_divert.c

     /*
      * Copyright (c) 1982, 1986, 1988, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: releng/5.2/sys/netinet/ip_divert.c 122991 2003-11-26 01:40:44Z sam $
     */
    
    #include "opt_inet.h"
    #include "opt_ipfw.h"
    #include "opt_ipdivert.h"
    #include "opt_ipsec.h"
    #include "opt_mac.h"
    
    #ifndef INET
    #error "IPDIVERT requires INET."
    #endif
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mac.h>
    #include <sys/mbuf.h>
    #include <sys/proc.h>
    #include <sys/protosw.h>
    #include <sys/signalvar.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sx.h>
    #include <sys/sysctl.h>
    #include <sys/systm.h>
    
    #include <vm/uma.h>
    
    #include <net/if.h>
    #include <net/route.h>
    
    #include <netinet/in.h>
    #include <netinet/in_pcb.h>
    #include <netinet/in_systm.h>
    #include <netinet/in_var.h>
    #include <netinet/ip.h>
    #include <netinet/ip_var.h>
    
    /*
     * Divert sockets
     */
    
    /*
     * Allocate enough space to hold a full IP packet
     */
    #define DIVSNDQ         (65536 + 100)
    #define DIVRCVQ         (65536 + 100)
    
    /*
     * Divert sockets work in conjunction with ipfw, see the divert(4)
     * manpage for features.
     * Internally, packets selected by ipfw in ip_input() or ip_output(),
     * and never diverted before, are passed to the input queue of the
     * divert socket with a given 'divert_port' number (as specified in
     * the matching ipfw rule), and they are tagged with a 16 bit cookie
     * (representing the rule number of the matching ipfw rule), which
     * is passed to process reading from the socket.
     *
     * Packets written to the divert socket are again tagged with a cookie
     * (usually the same as above) and a destination address.
     * If the destination address is INADDR_ANY then the packet is
     * treated as outgoing and sent to ip_output(), otherwise it is
     * treated as incoming and sent to ip_input().
     * In both cases, the packet is tagged with the cookie.
     *
    * On reinjection, processing in ip_input() and ip_output()
    * will be exactly the same as for the original packet, except that
    * ipfw processing will start at the rule number after the one
    * written in the cookie (so, tagging a packet with a cookie of 0
    * will cause it to be effectively considered as a standard packet).
    */
   
   /* Internal variables */
   static struct inpcbhead divcb;
   static struct inpcbinfo divcbinfo;
   
   static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
   static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
   
   /*
    * Initialize divert connection block queue.
    */
   void
   div_init(void)
   {
           INP_INFO_LOCK_INIT(&divcbinfo, "div");
           LIST_INIT(&divcb);
           divcbinfo.listhead = &divcb;
           /*
            * XXX We don't use the hash list for divert IP, but it's easier
            * to allocate a one entry hash list than it is to check all
            * over the place for hashbase == NULL.
            */
           divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
           divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
           divcbinfo.ipi_zone = uma_zcreate("divcb", sizeof(struct inpcb),
               NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
           uma_zone_set_max(divcbinfo.ipi_zone, maxsockets);
   }
   
   /*
    * IPPROTO_DIVERT is not in the real IP protocol number space; this
    * function should never be called.  Just in case, drop any packets.
    */
   void
   div_input(struct mbuf *m, int off)
   {
           ipstat.ips_noproto++;
           m_freem(m);
   }
   
   /*
    * Divert a packet by passing it up to the divert socket at port 'port'.
    *
    * Setup generic address and protocol structures for div_input routine,
    * then pass them along with mbuf chain.
    */
   void
   divert_packet(struct mbuf *m, int incoming, int port, int rule)
   {
           struct ip *ip;
           struct inpcb *inp;
           struct socket *sa;
           u_int16_t nport;
           struct sockaddr_in divsrc;
   
           /* Sanity check */
           KASSERT(port != 0, ("%s: port=0", __func__));
   
           /* Assure header */
           if (m->m_len < sizeof(struct ip) &&
               (m = m_pullup(m, sizeof(struct ip))) == 0)
                   return;
           ip = mtod(m, struct ip *);
   
           /*
            * Record receive interface address, if any.
            * But only for incoming packets.
            */
           bzero(&divsrc, sizeof(divsrc));
           divsrc.sin_len = sizeof(divsrc);
           divsrc.sin_family = AF_INET;
           divsrc.sin_port = rule;         /* record matching rule */
           if (incoming) {
                   struct ifaddr *ifa;
   
                   /* Sanity check */
                   M_ASSERTPKTHDR(m);
   
                   /* Find IP address for receive interface */
                   TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
                           if (ifa->ifa_addr == NULL)
                                   continue;
                           if (ifa->ifa_addr->sa_family != AF_INET)
                                   continue;
                           divsrc.sin_addr =
                               ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
                           break;
                   }
           }
           /*
            * Record the incoming interface name whenever we have one.
            */
           if (m->m_pkthdr.rcvif) {
                   /*
                    * Hide the actual interface name in there in the 
                    * sin_zero array. XXX This needs to be moved to a
                    * different sockaddr type for divert, e.g.
                    * sockaddr_div with multiple fields like 
                    * sockaddr_dl. Presently we have only 7 bytes
                    * but that will do for now as most interfaces
                    * are 4 or less + 2 or less bytes for unit.
                    * There is probably a faster way of doing this,
                    * possibly taking it from the sockaddr_dl on the iface.
                    * This solves the problem of a P2P link and a LAN interface
                    * having the same address, which can result in the wrong
                    * interface being assigned to the packet when fed back
                    * into the divert socket. Theoretically if the daemon saves
                    * and re-uses the sockaddr_in as suggested in the man pages,
                    * this iface name will come along for the ride.
                    * (see div_output for the other half of this.)
                    */ 
                   strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
                       sizeof(divsrc.sin_zero));
           }
   
           /*
            * XXX sbappendaddr must be protected by Giant until
            * we have locking at the socket layer.  When entered
            * from below we come in w/o Giant and must take it
            * here.  Unfortunately we cannot tell whether we're
            * entering from above (already holding Giant),
            * below (potentially without Giant), or otherwise
            * (e.g. from tcp_syncache through a timeout) so we
            * have to grab it regardless.  This causes a LOR with
            * the tcp lock, at least, and possibly others.  For
            * the moment we're ignoring this. Once sockets are
            * locked this cruft can be removed.
            */
           mtx_lock(&Giant);
           /* Put packet on socket queue, if any */
           sa = NULL;
           nport = htons((u_int16_t)port);
           INP_INFO_RLOCK(&divcbinfo);
           LIST_FOREACH(inp, &divcb, inp_list) {
                   INP_LOCK(inp);
                   /* XXX why does only one socket match? */
                   if (inp->inp_lport == nport) {
                           sa = inp->inp_socket;
                           if (sbappendaddr(&sa->so_rcv,
                               (struct sockaddr *)&divsrc, m,
                               (struct mbuf *)0) == 0)
                                   sa = NULL;      /* force mbuf reclaim below */
                           else
                                   sorwakeup(sa);
                           INP_UNLOCK(inp);
                           break;
                   }
                   INP_UNLOCK(inp);
           }
           INP_INFO_RUNLOCK(&divcbinfo);
           mtx_unlock(&Giant);
           if (sa == NULL) {
                   m_freem(m);
                   ipstat.ips_noproto++;
                   ipstat.ips_delivered--;
           }
   }
   
   /*
    * Deliver packet back into the IP processing machinery.
    *
    * If no address specified, or address is 0.0.0.0, send to ip_output();
    * otherwise, send to ip_input() and mark as having been received on
    * the interface with that address.
    */
   static int
   div_output(struct socket *so, struct mbuf *m,
           struct sockaddr_in *sin, struct mbuf *control)
   {
           int error = 0;
           struct m_hdr divert_tag;
   
           /*
            * Prepare the tag for divert info. Note that a packet
            * with a 0 tag in mh_data is effectively untagged,
            * so we could optimize that case.
            */
           divert_tag.mh_type = MT_TAG;
           divert_tag.mh_flags = PACKET_TAG_DIVERT;
           divert_tag.mh_next = m;
           divert_tag.mh_data = 0;         /* the matching rule # */
           divert_tag.mh_nextpkt = NULL;
           m->m_pkthdr.rcvif = NULL;       /* XXX is it necessary ? */
   
   #ifdef MAC
           mac_create_mbuf_from_socket(so, m);
   #endif
   
           if (control)
                   m_freem(control);               /* XXX */
   
           /* Loopback avoidance and state recovery */
           if (sin) {
                   int i;
   
                   divert_tag.mh_data = (caddr_t)(uintptr_t)sin->sin_port;
                   /*
                    * Find receive interface with the given name, stuffed
                    * (if it exists) in the sin_zero[] field.
                    * The name is user supplied data so don't trust its size
                    * or that it is zero terminated.
                    */
                   for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
                           ;
                   if ( i > 0 && i < sizeof(sin->sin_zero))
                           m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
           }
   
           /* Reinject packet into the system as incoming or outgoing */
           if (!sin || sin->sin_addr.s_addr == 0) {
                   struct ip *const ip = mtod(m, struct ip *);
                   struct inpcb *inp;
   
                   INP_INFO_WLOCK(&divcbinfo);
                   inp = sotoinpcb(so);
                   INP_LOCK(inp);
                   /*
                    * Don't allow both user specified and setsockopt options,
                    * and don't allow packet length sizes that will crash
                    */
                   if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
                        ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
                           error = EINVAL;
                           m_freem(m);
                   } else {
                           /* Convert fields to host order for ip_output() */
                           ip->ip_len = ntohs(ip->ip_len);
                           ip->ip_off = ntohs(ip->ip_off);
   
                           /* Send packet to output processing */
                           ipstat.ips_rawout++;                    /* XXX */
   
                           error = ip_output((struct mbuf *)&divert_tag,
                                       inp->inp_options, NULL,
                                       (so->so_options & SO_DONTROUTE) |
                                       IP_ALLOWBROADCAST | IP_RAWOUTPUT,
                                       inp->inp_moptions, NULL);
                   }
                   INP_UNLOCK(inp);
                   INP_INFO_WUNLOCK(&divcbinfo);
           } else {
                   if (m->m_pkthdr.rcvif == NULL) {
                           /*
                            * No luck with the name, check by IP address.
                            * Clear the port and the ifname to make sure
                            * there are no distractions for ifa_ifwithaddr.
                            */
                           struct  ifaddr *ifa;
   
                           bzero(sin->sin_zero, sizeof(sin->sin_zero));
                           sin->sin_port = 0;
                           ifa = ifa_ifwithaddr((struct sockaddr *) sin);
                           if (ifa == NULL) {
                                   error = EADDRNOTAVAIL;
                                   goto cantsend;
                           }
                           m->m_pkthdr.rcvif = ifa->ifa_ifp;
                   }
                   /* Send packet to input processing */
                   ip_input((struct mbuf *)&divert_tag);
           }
   
           return error;
   
   cantsend:
           m_freem(m);
           return error;
   }
   
   static int
   div_attach(struct socket *so, int proto, struct thread *td)
   {
           struct inpcb *inp;
           int error;
   
           INP_INFO_WLOCK(&divcbinfo);
           inp  = sotoinpcb(so);
           if (inp != 0) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return EINVAL;
           }
           if (td && (error = suser(td)) != 0) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return error;
           }
           error = soreserve(so, div_sendspace, div_recvspace);
           if (error) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return error;
           }
           error = in_pcballoc(so, &divcbinfo, td, "divinp");
           if (error) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return error;
           }
           inp = (struct inpcb *)so->so_pcb;
           INP_LOCK(inp);
           INP_INFO_WUNLOCK(&divcbinfo);
           inp->inp_ip_p = proto;
           inp->inp_vflag |= INP_IPV4;
           inp->inp_flags |= INP_HDRINCL;
           /* The socket is always "connected" because
              we always know "where" to send the packet */
           INP_UNLOCK(inp);
           so->so_state |= SS_ISCONNECTED;
           return 0;
   }
   
   static int
   div_detach(struct socket *so)
   {
           struct inpcb *inp;
   
           INP_INFO_WLOCK(&divcbinfo);
           inp = sotoinpcb(so);
           if (inp == 0) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return EINVAL;
           }
           INP_LOCK(inp);
           in_pcbdetach(inp);
           INP_INFO_WUNLOCK(&divcbinfo);
           return 0;
   }
   
   static int
   div_abort(struct socket *so)
   {
           struct inpcb *inp;
   
           INP_INFO_WLOCK(&divcbinfo);
           inp = sotoinpcb(so);
           if (inp == 0) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return EINVAL;  /* ??? possible? panic instead? */
           }
           INP_LOCK(inp);
           soisdisconnected(so);
           in_pcbdetach(inp);
           INP_INFO_WUNLOCK(&divcbinfo);
           return 0;
   }
   
   static int
   div_disconnect(struct socket *so)
   {
           if ((so->so_state & SS_ISCONNECTED) == 0)
                   return ENOTCONN;
           return div_abort(so);
   }
   
   static int
   div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
   {
           struct inpcb *inp;
           int error;
   
           INP_INFO_WLOCK(&divcbinfo);
           inp = sotoinpcb(so);
           if (inp == 0) {
                   INP_INFO_WUNLOCK(&divcbinfo);
                   return EINVAL;
           }
           /* in_pcbbind assumes that nam is a sockaddr_in
            * and in_pcbbind requires a valid address. Since divert
            * sockets don't we need to make sure the address is
            * filled in properly.
            * XXX -- divert should not be abusing in_pcbind
            * and should probably have its own family.
            */
           if (nam->sa_family != AF_INET)
                   error = EAFNOSUPPORT;
           else {
                   ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
                   INP_LOCK(inp);
                   error = in_pcbbind(inp, nam, td);
                   INP_UNLOCK(inp);
           }
           INP_INFO_WUNLOCK(&divcbinfo);
           return error;
   }
   
   static int
   div_shutdown(struct socket *so)
   {
           struct inpcb *inp;
   
           INP_INFO_RLOCK(&divcbinfo);
           inp = sotoinpcb(so);
           if (inp == 0) {
                   INP_INFO_RUNLOCK(&divcbinfo);
                   return EINVAL;
           }
           INP_LOCK(inp);
           INP_INFO_RUNLOCK(&divcbinfo);
           socantsendmore(so);
           INP_UNLOCK(inp);
           return 0;
   }
   
   static int
   div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
            struct mbuf *control, struct thread *td)
   {
           /* Packet must have a header (but that's about it) */
           if (m->m_len < sizeof (struct ip) &&
               (m = m_pullup(m, sizeof (struct ip))) == 0) {
                   ipstat.ips_toosmall++;
                   m_freem(m);
                   return EINVAL;
           }
   
           /* Send packet */
           return div_output(so, m, (struct sockaddr_in *)nam, control);
   }
   
   void
   div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
   {
           struct in_addr faddr;
   
           faddr = ((struct sockaddr_in *)sa)->sin_addr;
           if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
                   return;
           if (PRC_IS_REDIRECT(cmd))
                   return;
   }
   
   static int
   div_pcblist(SYSCTL_HANDLER_ARGS)
   {
           int error, i, n;
           struct inpcb *inp, **inp_list;
           inp_gen_t gencnt;
           struct xinpgen xig;
   
           /*
            * The process of preparing the TCB list is too time-consuming and
            * resource-intensive to repeat twice on every request.
            */
           if (req->oldptr == 0) {
                   n = divcbinfo.ipi_count;
                   req->oldidx = 2 * (sizeof xig)
                           + (n + n/8) * sizeof(struct xinpcb);
                   return 0;
           }
   
           if (req->newptr != 0)
                   return EPERM;
   
           /*
            * OK, now we're committed to doing something.
            */
           INP_INFO_RLOCK(&divcbinfo);
           gencnt = divcbinfo.ipi_gencnt;
           n = divcbinfo.ipi_count;
           INP_INFO_RUNLOCK(&divcbinfo);
   
           sysctl_wire_old_buffer(req, 2 * sizeof(xig) + n*sizeof(struct xinpcb));
   
           xig.xig_len = sizeof xig;
           xig.xig_count = n;
           xig.xig_gen = gencnt;
           xig.xig_sogen = so_gencnt;
           error = SYSCTL_OUT(req, &xig, sizeof xig);
           if (error)
                   return error;
   
           inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
           if (inp_list == 0)
                   return ENOMEM;
           
           INP_INFO_RLOCK(&divcbinfo);
           for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
                inp = LIST_NEXT(inp, inp_list)) {
                   INP_LOCK(inp);
                   if (inp->inp_gencnt <= gencnt &&
                       cr_canseesocket(req->td->td_ucred, inp->inp_socket) == 0)
                           inp_list[i++] = inp;
                   INP_UNLOCK(inp);
           }
           INP_INFO_RUNLOCK(&divcbinfo);
           n = i;
   
           error = 0;
           for (i = 0; i < n; i++) {
                   inp = inp_list[i];
                   if (inp->inp_gencnt <= gencnt) {
                           struct xinpcb xi;
                           xi.xi_len = sizeof xi;
                           /* XXX should avoid extra copy */
                           bcopy(inp, &xi.xi_inp, sizeof *inp);
                           if (inp->inp_socket)
                                   sotoxsocket(inp->inp_socket, &xi.xi_socket);
                           error = SYSCTL_OUT(req, &xi, sizeof xi);
                   }
           }
           if (!error) {
                   /*
                    * Give the user an updated idea of our state.
                    * If the generation differs from what we told
                    * her before, she knows that something happened
                    * while we were processing this request, and it
                    * might be necessary to retry.
                    */
                   INP_INFO_RLOCK(&divcbinfo);
                   xig.xig_gen = divcbinfo.ipi_gencnt;
                   xig.xig_sogen = so_gencnt;
                   xig.xig_count = divcbinfo.ipi_count;
                   INP_INFO_RUNLOCK(&divcbinfo);
                   error = SYSCTL_OUT(req, &xig, sizeof xig);
           }
           free(inp_list, M_TEMP);
           return error;
   }
   
   /*
    * This is the wrapper function for in_setsockaddr.  We just pass down
    * the pcbinfo for in_setpeeraddr to lock.
    */
   static int
   div_sockaddr(struct socket *so, struct sockaddr **nam)
   {
           return (in_setsockaddr(so, nam, &divcbinfo));
   }
   
   /*
    * This is the wrapper function for in_setpeeraddr. We just pass down
    * the pcbinfo for in_setpeeraddr to lock.
    */
   static int
   div_peeraddr(struct socket *so, struct sockaddr **nam)
   {
           return (in_setpeeraddr(so, nam, &divcbinfo));
   }
   
   
   SYSCTL_DECL(_net_inet_divert);
   SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
               div_pcblist, "S,xinpcb", "List of active divert sockets");
   
   struct pr_usrreqs div_usrreqs = {
           div_abort, pru_accept_notsupp, div_attach, div_bind,
           pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
           div_disconnect, pru_listen_notsupp, div_peeraddr, pru_rcvd_notsupp,
           pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
           div_sockaddr, sosend, soreceive, sopoll, in_pcbsosetlabel
   };

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