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. 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: src/sys/netinet/ip_divert.c,v 1.42.2.6 2003/01/23 21:06:45 sam Exp $
     */
    
    #define _IP_VHL
    
    #include "opt_inet.h"
    #include "opt_ipdivert.h"
    #include "opt_ipsec.h"
    
    #ifndef INET
    #error "IPDIVERT requires INET."
    #endif
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/protosw.h>
    #include <sys/socketvar.h>
    #include <sys/socketvar2.h>
    #include <sys/sysctl.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/priv.h>
    #include <sys/in_cksum.h>
    #include <sys/lock.h>
    #include <sys/msgport.h>
    
    #include <net/if.h>
    #include <net/route.h>
    
    #include <net/netmsg2.h>
    #include <net/netisr2.h>
    #include <sys/thread2.h>
    #include <sys/mplock2.h>
    
    #include <netinet/in.h>
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/in_pcb.h>
    #include <netinet/in_var.h>
    #include <netinet/ip_var.h>
    #include <netinet/ip_divert.h>
    
    /*
     * Divert sockets
     */
    
    /*
     * Allocate enough space to hold a full IP packet
     */
    #define DIVSNDQ         (65536 + 100)
    #define DIVRCVQ         (65536 + 100)
    
    #define DIV_IS_OUTPUT(sin)      ((sin) == NULL || (sin)->sin_addr.s_addr == 0)
    
    #define DIV_OUTPUT      0x10000
    #define DIV_INPUT       0x20000
    
    /*
     * 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 inpcbinfo divcbinfo;
   
   static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */
   static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */
   
   static struct mbuf *ip_divert(struct mbuf *, int, int);
   
   static struct lwkt_token div_token = LWKT_TOKEN_INITIALIZER(div_token);
   
   /*
    * Initialize divert connection block queue.
    */
   void
   div_init(void)
   {
           in_pcbinfo_init(&divcbinfo);
           /*
            * 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.wildcardhashbase = hashinit(1, M_PCB,
                                                 &divcbinfo.wildcardhashmask);
           divcbinfo.ipi_size = sizeof(struct inpcb);
           ip_divert_p = ip_divert;
   }
   
   /*
    * IPPROTO_DIVERT is not a real IP protocol; don't allow any packets
    * with that protocol number to enter the system from the outside.
    */
   int
   div_input(struct mbuf **mp, int *offp, int proto)
   {
           struct mbuf *m = *mp;
   
           ipstat.ips_noproto++;
           m_freem(m);
           return(IPPROTO_DONE);
   }
   
   /*
    * 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.
    */
   static void
   div_packet(struct mbuf *m, int incoming, int port)
   {
           struct sockaddr_in divsrc = { sizeof divsrc, AF_INET };
           struct inpcb *inp;
           struct socket *sa;
           struct m_tag *mtag;
           struct divert_info *divinfo;
           u_int16_t nport;
   
           /* Locate the divert info */
           mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
           divinfo = m_tag_data(mtag);
           divsrc.sin_port = divinfo->skipto;
   
           /*
            * Record receive interface address, if any.
            * But only for incoming packets.
            */
           divsrc.sin_addr.s_addr = 0;
           if (incoming) {
                   struct ifaddr_container *ifac;
   
                   /* Find IP address for receive interface */
                   TAILQ_FOREACH(ifac, &m->m_pkthdr.rcvif->if_addrheads[mycpuid],
                                 ifa_link) {
                           struct ifaddr *ifa = ifac->ifa;
   
                           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.)
                    */
                   ksnprintf(divsrc.sin_zero, sizeof divsrc.sin_zero, "%s",
                             m->m_pkthdr.rcvif->if_xname);
           }
   
           /* Put packet on socket queue, if any */
           sa = NULL;
           nport = htons((u_int16_t)port);
   
           /*
            * XXX
            * Following loop to locate the inpcb is MPSAFE since the inpcb
            * insertion/removal happens on the same CPU (CPU0), however,
            * saving/testing the socket pointer is not MPSAFE.  So we still
            * need to hold BGL here.
            */
           lwkt_gettoken(&div_token);
           LIST_FOREACH(inp, &divcbinfo.pcblisthead, inp_list) {
                   if (inp->inp_flags & INP_PLACEMARKER)
                           continue;
                   if (inp->inp_lport == nport)
                           sa = inp->inp_socket;
           }
           if (sa) {
                   lwkt_gettoken(&sa->so_rcv.ssb_token);
                   if (ssb_appendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc, m, NULL) == 0)
                           m_freem(m);
                   else
                           sorwakeup(sa);
                   lwkt_reltoken(&sa->so_rcv.ssb_token);
           } else {
                   m_freem(m);
                   ipstat.ips_noproto++;
                   ipstat.ips_delivered--;
           }
           lwkt_reltoken(&div_token);
   }
   
   static void
   div_packet_handler(netmsg_t msg)
   {
           struct mbuf *m;
           int port, incoming = 0;
   
           m = msg->packet.nm_packet;
   
           port = msg->lmsg.u.ms_result32 & 0xffff;
           if (msg->lmsg.u.ms_result32 & DIV_INPUT)
                   incoming = 1;
           div_packet(m, incoming, port);
           /* no reply, msg embedded in mbuf */
   }
   
   static void
   divert_packet(struct mbuf *m, int incoming)
   {
           struct m_tag *mtag;
           struct divert_info *divinfo;
           int port;
   
           M_ASSERTPKTHDR(m);
   
           /* Assure header */
           if (m->m_len < sizeof(struct ip) &&
               (m = m_pullup(m, sizeof(struct ip))) == NULL)
                   return;
   
           mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
           KASSERT(mtag != NULL, ("%s no divert tag!", __func__));
           divinfo = m_tag_data(mtag);
   
           port = divinfo->port;
           KASSERT(port != 0, ("%s: port=0", __func__));
   
           if (mycpuid != 0) {
                   struct netmsg_packet *nmp;
   
                   nmp = &m->m_hdr.mh_netmsg;
                   netmsg_init(&nmp->base, NULL, &netisr_apanic_rport,
                               0, div_packet_handler);
                   nmp->nm_packet = m;
   
                   nmp->base.lmsg.u.ms_result32 = port; /* port is 16bits */
                   if (incoming)
                           nmp->base.lmsg.u.ms_result32 |= DIV_INPUT;
                   else
                           nmp->base.lmsg.u.ms_result32 |= DIV_OUTPUT;
   
                   lwkt_sendmsg(netisr_cpuport(0), &nmp->base.lmsg);
           } else {
                   div_packet(m, incoming, port);
           }
   }
   
   /*
    * 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_tag *mtag;
           struct divert_info *divinfo;
   
           if (control)
                   m_freem(control);               /* XXX */
   
           /*
            * 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.
            */
           mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, sizeof(*divinfo), MB_DONTWAIT);
           if (mtag == NULL) {
                   error = ENOBUFS;
                   goto cantsend;
           }
           m_tag_prepend(m, mtag);
   
           /* Loopback avoidance and state recovery */
           divinfo = m_tag_data(mtag);
           if (sin)
                   divinfo->skipto = sin->sin_port;
           else
                   divinfo->skipto = 0;
   
           /* Reinject packet into the system as incoming or outgoing */
           if (DIV_IS_OUTPUT(sin)) {
                   struct ip *const ip = mtod(m, struct ip *);
   
                   /* Don't allow packet length sizes that will crash */
                   if ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len) {
                           error = EINVAL;
                           goto cantsend;
                   }
   
                   /* 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(m, NULL, NULL,
                               (so->so_options & SO_DONTROUTE) |
                               IP_ALLOWBROADCAST | IP_RAWOUTPUT,
                               NULL, NULL);
           } else {
                   ip_input(m);
           }
           return error;
   
   cantsend:
           m_freem(m);
           return error;
   }
   
   static void
   div_attach(netmsg_t msg)
   {
           struct socket *so = msg->attach.base.nm_so;
           int proto = msg->attach.nm_proto;
           struct pru_attach_info *ai = msg->attach.nm_ai;
           struct inpcb *inp;
           int error;
   
           inp  = so->so_pcb;
           if (inp)
                   panic("div_attach");
           error = priv_check_cred(ai->p_ucred, PRIV_ROOT, NULL_CRED_OKAY);
           if (error)
                   goto out;
   
           error = soreserve(so, div_sendspace, div_recvspace, ai->sb_rlimit);
           if (error)
                   goto out;
           lwkt_gettoken(&div_token);
           sosetport(so, netisr_cpuport(0));
           error = in_pcballoc(so, &divcbinfo);
           if (error) {
                   lwkt_reltoken(&div_token);
                   goto out;
           }
           inp = (struct inpcb *)so->so_pcb;
           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.
            */
           sosetstate(so, SS_ISCONNECTED);
           lwkt_reltoken(&div_token);
           error = 0;
   out:
           lwkt_replymsg(&msg->attach.base.lmsg, error);
   }
   
   static void
   div_detach(netmsg_t msg)
   {
           struct socket *so = msg->detach.base.nm_so;
           struct inpcb *inp;
   
           inp = so->so_pcb;
           if (inp == NULL)
                   panic("div_detach");
           in_pcbdetach(inp);
           lwkt_replymsg(&msg->detach.base.lmsg, 0);
   }
   
   /*
    * NOTE: (so) is referenced from soabort*() and netmsg_pru_abort()
    *       will sofree() it when we return.
    */
   static void
   div_abort(netmsg_t msg)
   {
           struct socket *so = msg->abort.base.nm_so;
   
           soisdisconnected(so);
           div_detach(msg);
           /* msg invalid now */
   }
   
   static void
   div_disconnect(netmsg_t msg)
   {
           struct socket *so = msg->disconnect.base.nm_so;
           int error;
   
           if (so->so_state & SS_ISCONNECTED) {
                   soreference(so);
                   div_abort(msg);
                   /* msg invalid now */
                   sofree(so);
                   return;
           }
           error = ENOTCONN;
           lwkt_replymsg(&msg->disconnect.base.lmsg, error);
   }
   
   static void
   div_bind(netmsg_t msg)
   {
           struct socket *so = msg->bind.base.nm_so;
           struct sockaddr *nam = msg->bind.nm_nam;
           int error;
   
           /*
            * 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;
                   error = in_pcbbind(so->so_pcb, nam, msg->bind.nm_td);
           }
           lwkt_replymsg(&msg->bind.base.lmsg, error);
   }
   
   static void
   div_shutdown(netmsg_t msg)
   {
           struct socket *so = msg->shutdown.base.nm_so;
   
           socantsendmore(so);
   
           lwkt_replymsg(&msg->shutdown.base.lmsg, 0);
   }
   
   static void
   div_send(netmsg_t msg)
   {
           struct socket *so = msg->send.base.nm_so;
           struct mbuf *m = msg->send.nm_m;
           struct sockaddr *nam = msg->send.nm_addr;
           struct mbuf *control = msg->send.nm_control;
           int error;
   
           /* Length check already done in ip_hashfn() */
           KASSERT(m->m_len >= sizeof(struct ip), ("IP header not in one mbuf"));
   
           /* Send packet */
           error = div_output(so, m, (struct sockaddr_in *)nam, control);
           lwkt_replymsg(&msg->send.base.lmsg, error);
   }
   
   SYSCTL_DECL(_net_inet_divert);
   SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, &divcbinfo, 0,
               in_pcblist_global, "S,xinpcb", "List of active divert sockets");
   
   struct pr_usrreqs div_usrreqs = {
           .pru_abort = div_abort,
           .pru_accept = pr_generic_notsupp,
           .pru_attach = div_attach,
           .pru_bind = div_bind,
           .pru_connect = pr_generic_notsupp,
           .pru_connect2 = pr_generic_notsupp,
           .pru_control = in_control_dispatch,
           .pru_detach = div_detach,
           .pru_disconnect = div_disconnect,
           .pru_listen = pr_generic_notsupp,
           .pru_peeraddr = in_setpeeraddr_dispatch,
           .pru_rcvd = pr_generic_notsupp,
           .pru_rcvoob = pr_generic_notsupp,
           .pru_send = div_send,
           .pru_sense = pru_sense_null,
           .pru_shutdown = div_shutdown,
           .pru_sockaddr = in_setsockaddr_dispatch,
           .pru_sosend = sosend,
           .pru_soreceive = soreceive
   };
   
   static struct mbuf *
   ip_divert_out(struct mbuf *m, int tee)
   {
           struct mbuf *clone = NULL;
           struct ip *ip = mtod(m, struct ip *);
   
           /* Clone packet if we're doing a 'tee' */
           if (tee)
                   clone = m_dup(m, MB_DONTWAIT);
   
           /*
            * XXX
            * delayed checksums are not currently compatible
            * with divert sockets.
            */
           if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
                   in_delayed_cksum(m);
                   m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
           }
   
           /* Restore packet header fields to original values */
           ip->ip_len = htons(ip->ip_len);
           ip->ip_off = htons(ip->ip_off);
   
           /* Deliver packet to divert input routine */
           divert_packet(m, 0);
   
           /* If 'tee', continue with original packet */
           return clone;
   }
   
   static struct mbuf *
   ip_divert_in(struct mbuf *m, int tee)
   {
           struct mbuf *clone = NULL;
           struct ip *ip = mtod(m, struct ip *);
           struct m_tag *mtag;
   
           if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
                   const struct divert_info *divinfo;
                   u_short frag_off;
                   int hlen;
   
                   /*
                    * Only trust divert info in the fragment
                    * at offset 0.
                    */
                   frag_off = ip->ip_off << 3;
                   if (frag_off != 0) {
                           mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
                           m_tag_delete(m, mtag);
                   }
   
                   /*
                    * Attempt reassembly; if it succeeds, proceed.
                    * ip_reass() will return a different mbuf.
                    */
                   m = ip_reass(m);
                   if (m == NULL)
                           return NULL;
                   ip = mtod(m, struct ip *);
   
                   /* Caller need to redispatch the packet, if it is for us */
                   m->m_pkthdr.fw_flags |= FW_MBUF_REDISPATCH;
   
                   /*
                    * Get the header length of the reassembled
                    * packet
                    */
                   hlen = IP_VHL_HL(ip->ip_vhl) << 2;
   
                   /*
                    * Restore original checksum before diverting
                    * packet
                    */
                   ip->ip_len += hlen;
                   ip->ip_len = htons(ip->ip_len);
                   ip->ip_off = htons(ip->ip_off);
                   ip->ip_sum = 0;
                   if (hlen == sizeof(struct ip))
                           ip->ip_sum = in_cksum_hdr(ip);
                   else
                           ip->ip_sum = in_cksum(m, hlen);
                   ip->ip_off = ntohs(ip->ip_off);
                   ip->ip_len = ntohs(ip->ip_len);
   
                   /*
                    * Only use the saved divert info
                    */
                   mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL);
                   if (mtag == NULL) {
                           /* Wrongly configured ipfw */
                           kprintf("ip_input no divert info\n");
                           m_freem(m);
                           return NULL;
                   }
                   divinfo = m_tag_data(mtag);
                   tee = divinfo->tee;
           }
   
           /*
            * Divert or tee packet to the divert protocol if
            * required.
            */
   
           /* Clone packet if we're doing a 'tee' */
           if (tee)
                   clone = m_dup(m, MB_DONTWAIT);
   
           /*
            * Restore packet header fields to original
            * values
            */
           ip->ip_len = htons(ip->ip_len);
           ip->ip_off = htons(ip->ip_off);
   
           /* Deliver packet to divert input routine */
           divert_packet(m, 1);
   
           /* Catch invalid reference */
           m = NULL;
           ip = NULL;
   
           ipstat.ips_delivered++;
   
           /* If 'tee', continue with original packet */
           if (clone != NULL) {
                   /*
                    * Complete processing of the packet.
                    * XXX Better safe than sorry, remove the DIVERT tag.
                    */
                   mtag = m_tag_find(clone, PACKET_TAG_IPFW_DIVERT, NULL);
                   KKASSERT(mtag != NULL);
                   m_tag_delete(clone, mtag);
           }
           return clone;
   }
   
   static struct mbuf *
   ip_divert(struct mbuf *m, int tee, int incoming)
   {
           struct mbuf *ret;
   
           if (incoming)
                   ret = ip_divert_in(m, tee);
           else
                   ret = ip_divert_out(m, tee);
           return ret;
   }

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