[apple/xnu.git] / bsd / netinet / ip_divert.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * 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.
 *
 */

#if ISFB31
#include "opt_inet.h"
#include "opt_ipfw.h"
#include "opt_ipdivert.h"
#endif

#ifndef INET
#error "IPDIVERT requires INET."
#endif

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/proc.h>

#if ISFB31
#include <vm/vm_zone.h>
#endif

#include <net/if.h>
#include <net/route.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>

/*
 * Divert sockets
 */

/*
 * Allocate enough space to hold a full IP packet
 */
#define DIVSNDQ         (65536 + 100)
#define DIVRCVQ         (65536 + 100)

/* Global variables */

/*
 * ip_input() and ip_output() set this secret value before calling us to
 * let us know which divert port to divert a packet to; this is done so
 * we can use the existing prototype for struct protosw's pr_input().
 * This is stored in host order.
 */
u_short ip_divert_port;

/*
 * A 16 bit cookie is passed to the user process.
 * The user process can send it back to help the caller know something
 * about where the packet came from.
 *
 * If IPFW is the caller then the cookie is the rule that sent
 * us here. On reinjection is is the rule after which processing
 * should continue. Leaving it the same will make processing start
 * at the rule number after that which sent it here. Setting it to
 * 0 will restart processing at the beginning. 
 */
u_int16_t ip_divert_cookie;

/* 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 ? */

/* Optimization: have this preinitialized */
static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };

/* Internal functions */

static int div_output(struct socket *so,
                struct mbuf *m, struct sockaddr *addr, struct mbuf *control);

/*
 * Initialize divert connection block queue.
 */
void
div_init(void)
{
        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 = (void *) zinit(sizeof(struct inpcb),(maxsockets * sizeof(struct inpcb)),
                                   4096, "divzone");

/*
 * ### LD 08/03: init IP forwarding at this point [ipfw is not a module yet]
 */
#if !IPFIREWALL_KEXT
        ip_fw_init();
#endif
}

/*
 * Setup generic address and protocol structures
 * for div_input routine, then pass them along with
 * mbuf chain. ip->ip_len is assumed to have had
 * the header length (hlen) subtracted out already.
 * We tell whether the packet was incoming or outgoing
 * by seeing if hlen == 0, which is a hack.
 */
void
div_input(struct mbuf *m, int hlen)
{
        struct ip *ip;
        struct inpcb *inp;
        struct socket *sa;

        /* Sanity check */
        if (ip_divert_port == 0)
                panic("div_input: port is 0");

        /* Assure header */
        if (m->m_len < sizeof(struct ip) &&
            (m = m_pullup(m, sizeof(struct ip))) == 0) {
                return;
        }
        ip = mtod(m, struct ip *);

        /* Record divert cookie */
        divsrc.sin_port = ip_divert_cookie;
        ip_divert_cookie = 0;

        /* Restore packet header fields */
        ip->ip_len += hlen;
        HTONS(ip->ip_len);
        HTONS(ip->ip_off);

        /*
         * Record receive interface address, if any
         * But only for incoming packets.
         */
        divsrc.sin_addr.s_addr = 0;
        if (hlen) {
                struct ifaddr *ifa;

#if DIAGNOSTIC
                /* Sanity check */
                if (!(m->m_flags & M_PKTHDR))
                        panic("div_input: no pkt hdr");
#endif

                /* More fields affected by ip_input() */
                HTONS(ip->ip_id);

                /* Find IP address for receive interface */
                for (ifa = m->m_pkthdr.rcvif->if_addrhead.tqh_first;
                    ifa != NULL; ifa = ifa->ifa_link.tqe_next) {
                        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.
         */
        bzero(&divsrc.sin_zero, sizeof(divsrc.sin_zero));
        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.)
                 */ 
                snprintf(divsrc.sin_zero, sizeof(divsrc.sin_zero),
                        "%s%d", m->m_pkthdr.rcvif->if_name,
                        m->m_pkthdr.rcvif->if_unit);
        }

        /* Put packet on socket queue, if any */
        sa = NULL;
        for (inp = divcb.lh_first; inp != NULL; inp = inp->inp_list.le_next) {
                if (inp->inp_lport == htons(ip_divert_port))
                        sa = inp->inp_socket;
        }
        ip_divert_port = 0;
        if (sa) {
                if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,
                                m, (struct mbuf *)0) == 0)
                        m_freem(m);
                else
                        sorwakeup(sa);
        } else {
                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(so, m, addr, control)
        struct socket *so;
        register struct mbuf *m;
        struct sockaddr *addr;
        struct mbuf *control;
{
        register struct inpcb *const inp = sotoinpcb(so);
        register struct ip *const ip = mtod(m, struct ip *);
        struct sockaddr_in *sin = (struct sockaddr_in *)addr;
        int error = 0;

        if (control)
                m_freem(control);               /* XXX */

        /* Loopback avoidance and state recovery */
        if (sin) {
                int     len = 0;
                char    *c = sin->sin_zero;

                ip_divert_cookie = sin->sin_port;

                /*
                 * Find receive interface with the given name or IP address.
                 * The name is user supplied data so don't trust it's size or 
                 * that it is zero terminated. The name has priority.
                 * We are presently assuming that the sockaddr_in 
                 * has not been replaced by a sockaddr_div, so we limit it
                 * to 16 bytes in total. the name is stuffed (if it exists)
                 * in the sin_zero[] field.
                 */
                while (*c++ && (len++ < sizeof(sin->sin_zero)));
                if ((len > 0) && (len < sizeof(sin->sin_zero)))
                        m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
        } else {
                ip_divert_cookie = 0;
        }

        /* Reinject packet into the system as incoming or outgoing */
        if (!sin || sin->sin_addr.s_addr == 0) {
                /*
                 * 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;
                        goto cantsend;
                }

                /* Convert fields to host order for ip_output() */
                NTOHS(ip->ip_len);
                NTOHS(ip->ip_off);

                /* Send packet to output processing */
                ipstat.ips_rawout++;                    /* XXX */
                error = ip_output(m, inp->inp_options, &inp->inp_route,
                        (so->so_options & SO_DONTROUTE) |
                        IP_ALLOWBROADCAST | IP_RAWOUTPUT, inp->inp_moptions);
        } else {
                struct  ifaddr *ifa;

                /* If no luck with the name above. check by IP address.  */
                if (m->m_pkthdr.rcvif == NULL) {
                        /*
                         * Make sure there are no distractions
                         * for ifa_ifwithaddr. Clear the port and the ifname.
                         * Maybe zap all 8 bytes at once using a 64bit write?
                         */
                        bzero(sin->sin_zero, sizeof(sin->sin_zero));
                        /* *((u_int64_t *)sin->sin_zero) = 0; */ /* XXX ?? */
                        sin->sin_port = 0;
                        if (!(ifa = ifa_ifwithaddr((struct sockaddr *) sin))) {
                                error = EADDRNOTAVAIL;
                                goto cantsend;
                        }
                        m->m_pkthdr.rcvif = ifa->ifa_ifp;
                }

                /* Send packet to input processing */
                ip_input(m);
        }

        /* paranoid: Reset for next time (and other packets) */
        /* almost definitly already done in the ipfw filter but.. */
        ip_divert_cookie = 0;
        return error;

cantsend:
        ip_divert_cookie = 0;
        m_freem(m);
        return error;
}

static int
div_attach(struct socket *so, int proto, struct proc *p)
{
        struct inpcb *inp;
        int error, s;

        inp  = sotoinpcb(so);
        if (inp)
                panic("div_attach");
        if (p && (error = suser(p->p_ucred, &p->p_acflag)) != 0)
                return error;

        s = splnet();
        error = in_pcballoc(so, &divcbinfo, p);
        splx(s);
        if (error)
                return error;
        error = soreserve(so, div_sendspace, div_recvspace);
        if (error)
                return error;
        inp = (struct inpcb *)so->so_pcb;
        inp->inp_ip_p = proto;
        inp->inp_flags |= INP_HDRINCL | INP_IPV4;
        /* The socket is always "connected" because
           we always know "where" to send the packet */
        so->so_state |= SS_ISCONNECTED;
#if IPSEC
        error = ipsec_init_policy(so, &inp->inp_sp);
        if (error != 0) {
                in_pcbdetach(inp);
                return error;
        }
#endif /*IPSEC*/
        return 0;
}

static int
div_detach(struct socket *so)
{
        struct inpcb *inp;

        inp = sotoinpcb(so);
        if (inp == 0)
                panic("div_detach");
        in_pcbdetach(inp);
        return 0;
}

static int
div_abort(struct socket *so)
{
        soisdisconnected(so);
        return div_detach(so);
}

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 proc *p)
{
        struct inpcb *inp;
        int s;
        int error;

        s = splnet();
        inp = sotoinpcb(so);
        error = in_pcbbind(inp, nam, p);
        splx(s);
        return 0;
}

static int
div_shutdown(struct socket *so)
{
        socantsendmore(so);
        return 0;
}

static int
div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
         struct mbuf *control, struct proc *p)
{
        /* 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, nam, control);
}

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, in_setpeeraddr, pru_rcvd_notsupp,
        pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
        in_setsockaddr, sosend, soreceive, sopoll
};