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//==========================================================================

//

//      src/sys/netinet/ip_encap.c

//

//==========================================================================

//####BSDCOPYRIGHTBEGIN####

//

// -------------------------------------------

//

// Portions of this software may have been derived from OpenBSD, 

// FreeBSD or other sources, and are covered by the appropriate

// copyright disclaimers included herein.

//

// Portions created by Red Hat are

// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.

//

// -------------------------------------------

//

//####BSDCOPYRIGHTEND####

//==========================================================================

/*      $KAME: ip_encap.c,v 1.73 2001/10/02 08:30:58 itojun Exp $       */

/*

 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.

 * 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 project 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 PROJECT 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 PROJECT 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.

 */

/*

 * My grandfather said that there's a devil inside tunnelling technology...

 *

 * We have surprisingly many protocols that want packets with IP protocol

 * #4 or #41.  Here's a list of protocols that want protocol #41:

 *      RFC1933 configured tunnel

 *      RFC1933 automatic tunnel

 *      RFC2401 IPsec tunnel

 *      RFC2473 IPv6 generic packet tunnelling

 *      RFC2529 6over4 tunnel

 *      RFC3056 6to4 tunnel

 *      isatap tunnel

 *      mobile-ip6 (uses RFC2473)

 * Here's a list of protocol that want protocol #4:

 *      RFC1853 IPv4-in-IPv4 tunnelling

 *      RFC2003 IPv4 encapsulation within IPv4

 *      RFC2344 reverse tunnelling for mobile-ip4

 *      RFC2401 IPsec tunnel

 * Well, what can I say.  They impose different en/decapsulation mechanism

 * from each other, so they need separate protocol handler.  The only one

 * we can easily determine by protocol # is IPsec, which always has

 * AH/ESP/IPComp header right after outer IP header.

 *

 * So, clearly good old protosw does not work for protocol #4 and #41.

 * The code will let you match protocol via src/dst address pair.

 */

/* XXX is M_NETADDR correct? */

/*

 * With USE_RADIX the code will use radix table for tunnel lookup, for

 * tunnels registered with encap_attach() with a addr/mask pair.

 * Faster on machines with thousands of tunnel registerations (= interfaces).

 *

 * The code assumes that radix table code can handle non-continuous netmask,

 * as it will pass radix table memory region with (src + dst) sockaddr pair.

 *

 * FreeBSD is excluded here as they make max_keylen a static variable, and

 * thus forbid definition of radix table other than proper domains.

 */

#include <sys/param.h>

#include <sys/socket.h>

#include <sys/sockio.h>

#include <sys/mbuf.h>

#include <sys/errno.h>

#include <sys/protosw.h>

#include <sys/queue.h>

#include <net/if.h>

#include <net/route.h>

#include <netinet/in.h>

#include <netinet/in_systm.h>

#include <netinet/ip.h>

#include <netinet/ip_var.h>

#include <netinet/ip_encap.h>

#ifdef MROUTING

#include <netinet/ip_mroute.h>

#endif /* MROUTING */

#ifdef __OpenBSD__

#include <netinet/ip_ipsp.h>

#endif

#ifdef INET6

#include <netinet/ip6.h>

#include <netinet6/ip6_var.h>

#include <netinet6/ip6protosw.h>

#include <netinet6/in6_var.h>

#if (defined(__FreeBSD__) && __FreeBSD__ >= 3) || defined(__OpenBSD__) || (defined(__bsdi__) && _BSDI_VERSION >= 199802)

#include <netinet/in_pcb.h>

#else

#include <netinet6/in6_pcb.h>

#endif

#include <netinet/icmp6.h>

#endif

#include <stdarg.h>

#include <sys/malloc.h>

/* to lookup a pair of address using radix tree */

struct sockaddr_pack {

        u_int8_t sp_len;

        u_int8_t sp_family;     /* not really used */

        /* followed by variable-length data */

} __attribute__((__packed__));

struct pack4 {

        struct sockaddr_pack p;

        struct sockaddr_in mine;

        struct sockaddr_in yours;

} __attribute__((__packed__));

struct pack6 {

        struct sockaddr_pack p;

        struct sockaddr_in6 mine;

        struct sockaddr_in6 yours;

} __attribute__((__packed__));

enum direction { INBOUND, OUTBOUND };

#ifdef INET

static struct encaptab *encap4_lookup __P((struct mbuf *, int, int,

        enum direction));

#endif

#ifdef INET6

static struct encaptab *encap6_lookup __P((struct mbuf *, int, int,

        enum direction));

#endif

static int encap_add __P((struct encaptab *));

static int encap_remove __P((struct encaptab *));

static int encap_afcheck __P((int, const struct sockaddr *, const struct sockaddr *));

#ifdef USE_RADIX

static struct radix_node_head *encap_rnh __P((int));

static int mask_matchlen __P((const struct sockaddr *));

#endif

#ifndef USE_RADIX

static int mask_match __P((const struct encaptab *, const struct sockaddr *,

                const struct sockaddr *));

#endif

static void encap_fillarg __P((struct mbuf *, const struct encaptab *));

#ifndef LIST_HEAD_INITIALIZER

/* rely upon BSS initialization */

LIST_HEAD(, encaptab) encaptab;

#else

LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);

#endif

#ifdef USE_RADIX

extern int max_keylen;  /* radix.c */

struct radix_node_head *encap_head[2];  /* 0 for AF_INET, 1 for AF_INET6 */

#endif

void

encap_init()

{

        static int initialized = 0;

        if (initialized)

                return;

        initialized++;

#if 0

        /*

         * we cannot use LIST_INIT() here, since drivers may want to call

         * encap_attach(), on driver attach.  encap_init() will be called

         * on AF_INET{,6} initialization, which happens after driver

         * initialization - using LIST_INIT() here can nuke encap_attach()

         * from drivers.

         */

        LIST_INIT(&encaptab);

#endif

#ifdef USE_RADIX

        /*

         * initialize radix lookup table.

         * max_keylen initialization should happen before the call to rn_init().

         */

        rn_inithead((void **)&encap_head[0], sizeof(struct sockaddr_pack) << 3);

        if (sizeof(struct pack4) > max_keylen)

                max_keylen = sizeof(struct pack4);

#ifdef INET6

        rn_inithead((void **)&encap_head[1], sizeof(struct sockaddr_pack) << 3);

        if (sizeof(struct pack6) > max_keylen)

                max_keylen = sizeof(struct pack6);

#endif

#endif

}

#ifdef INET

static struct encaptab *

encap4_lookup(m, off, proto, dir)

        struct mbuf *m;

        int off;

        int proto;

        enum direction dir;

{

        struct ip *ip;

        struct pack4 pack;

        struct encaptab *ep, *match;

        int prio, matchprio;

#ifdef USE_RADIX

        struct radix_node_head *rnh = encap_rnh(AF_INET);

        struct radix_node *rn;

#endif

#ifdef DIAGNOSTIC

        if (m->m_len < sizeof(*ip))

                panic("encap4_lookup");

#endif

        ip = mtod(m, struct ip *);

        bzero(&pack, sizeof(pack));

        pack.p.sp_len = sizeof(pack);

        pack.mine.sin_family = pack.yours.sin_family = AF_INET;

        pack.mine.sin_len = pack.yours.sin_len = sizeof(struct sockaddr_in);

        if (dir == INBOUND) {

                pack.mine.sin_addr = ip->ip_dst;

                pack.yours.sin_addr = ip->ip_src;

        } else {

                pack.mine.sin_addr = ip->ip_src;

                pack.yours.sin_addr = ip->ip_dst;

        }

        match = NULL;

        matchprio = 0;

#ifdef USE_RADIX

        rn = rnh->rnh_matchaddr((caddr_t)&pack, rnh);

        if (rn && (rn->rn_flags & RNF_ROOT) == 0) {

                match = (struct encaptab *)rn;

                matchprio = mask_matchlen(match->srcmask) +

                    mask_matchlen(match->dstmask);

        }

#endif

        for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {

                if (ep->af != AF_INET)

                        continue;

                if (ep->proto >= 0 && ep->proto != proto)

                        continue;

                if (ep->func)

                        prio = (*ep->func)(m, off, proto, ep->arg);

                else {

#ifdef USE_RADIX

                        continue;

#else

                        prio = mask_match(ep, (struct sockaddr *)&pack.mine,

                            (struct sockaddr *)&pack.yours);

#endif

                }

                /*

                 * We prioritize the matches by using bit length of the

                 * matches.  mask_match() and user-supplied matching function

                 * should return the bit length of the matches (for example,

                 * if both src/dst are matched for IPv4, 64 should be returned).

                 * 0 or negative return value means "it did not match".

                 *

                 * The question is, since we have two "mask" portion, we

                 * cannot really define total order between entries.

                 * For example, which of these should be preferred?

                 * mask_match() returns 48 (32 + 16) for both of them.

                 *      src=3ffe::/16, dst=3ffe:501::/32

                 *      src=3ffe:501::/32, dst=3ffe::/16

                 *

                 * We need to loop through all the possible candidates

                 * to get the best match - the search takes O(n) for

                 * n attachments (i.e. interfaces).

                 *

                 * For radix-based lookup, I guess source takes precedence.

                 * See rn_{refines,lexobetter} for the correct answer.

                 */

                if (prio <= 0)

                        continue;

                if (prio > matchprio) {

                        matchprio = prio;

                        match = ep;

                }

        }

        return match;

#undef s

#undef d

}

void

#if (defined(__FreeBSD__) && __FreeBSD__ >= 4)

encap4_input(struct mbuf *m, int off)

#else

#if __STDC__

encap4_input(struct mbuf *m, ...)

#else

encap4_input(m, va_alist)

        struct mbuf *m;

        va_dcl

#endif

#endif /* (defined(__FreeBSD__) && __FreeBSD__ >= 4) */

{

#if !(defined(__FreeBSD__) && __FreeBSD__ >= 4)

        int off, proto;

        va_list ap;

#else

        int proto;

#endif /* !(defined(__FreeBSD__) && __FreeBSD__ >= 4) */

        const struct protosw *psw;

        struct encaptab *match;

#if !(defined(__FreeBSD__) && __FreeBSD__ >= 4)

        va_start(ap, m);

        off = va_arg(ap, int);

#if !defined(__OpenBSD__)

        proto = va_arg(ap, int);

#endif

        va_end(ap);

#endif /* !(defined(__FreeBSD__) && __FreeBSD__ >= 4) */

#if defined(__OpenBSD__) || (defined(__FreeBSD__) && __FreeBSD__ >= 4)

        proto = mtod(m, struct ip *)->ip_p;

#endif

        match = encap4_lookup(m, off, proto, INBOUND);

        if (match) {

                /* found a match, "match" has the best one */

                psw = match->psw;

                if (psw && psw->pr_input) {

                        encap_fillarg(m, match);

#if defined(__FreeBSD__) && __FreeBSD__ >= 4

                        (*psw->pr_input)(m, off);

#else

                        (*psw->pr_input)(m, off, proto);

#endif

                } else

                        m_freem(m);

                return;

        }

        /* for backward compatibility - messy... */

#if defined(__NetBSD__)

        /* last resort: inject to raw socket */

        rip_input(m, off, proto);

#elif defined(__OpenBSD__)

# if defined(MROUTING) || defined(IPSEC)

        if (proto == IPPROTO_IPV4) {

                ip4_input(m, off, proto);

                return;

        }

# endif

        /* last resort: inject to raw socket */

        rip_input(m, off, proto);

#elif (defined(__FreeBSD__) && __FreeBSD__ >= 5)

        /* last resort: inject to raw socket */

        rip_input(m, off);

#elif defined(__FreeBSD__) && __FreeBSD__ >= 4

#ifdef MROUTING

        if (proto == IPPROTO_IPV4) {

                ipip_input(m, off);

                return;

        }

#endif

        /* last resort: inject to raw socket */

        rip_input(m, off);

#else

#ifdef MROUTING

        if (proto == IPPROTO_IPV4) {

                ipip_input(m, off, proto);

                return;

        }

#endif

        /* last resort: inject to raw socket */

        rip_input(m, off, proto);

#endif

}

#endif

#ifdef INET6

static struct encaptab *

encap6_lookup(m, off, proto, dir)

        struct mbuf *m;

        int off;

        int proto;

        enum direction dir;

{

        struct ip6_hdr *ip6;

        struct pack6 pack;

        int prio, matchprio;

        struct encaptab *ep, *match;

#ifdef USE_RADIX

        struct radix_node_head *rnh = encap_rnh(AF_INET6);

        struct radix_node *rn;

#endif

#ifdef DIAGNOSTIC

        if (m->m_len < sizeof(*ip6))

                panic("encap6_lookup");

#endif

        ip6 = mtod(m, struct ip6_hdr *);

        bzero(&pack, sizeof(pack));

        pack.p.sp_len = sizeof(pack);

        pack.mine.sin6_family = pack.yours.sin6_family = AF_INET6;

        pack.mine.sin6_len = pack.yours.sin6_len = sizeof(struct sockaddr_in6);

        if (dir == INBOUND) {

                pack.mine.sin6_addr = ip6->ip6_dst;

                pack.yours.sin6_addr = ip6->ip6_src;

        } else {

                pack.mine.sin6_addr = ip6->ip6_src;

                pack.yours.sin6_addr = ip6->ip6_dst;

        }

        match = NULL;

        matchprio = 0;

#ifdef USE_RADIX

        rn = rnh->rnh_matchaddr((caddr_t)&pack, rnh);

        if (rn && (rn->rn_flags & RNF_ROOT) == 0) {

                match = (struct encaptab *)rn;

                matchprio = mask_matchlen(match->srcmask) +

                    mask_matchlen(match->dstmask);

        }

#endif

        for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {

                if (ep->af != AF_INET6)

                        continue;

                if (ep->proto >= 0 && ep->proto != proto)

                        continue;

                if (ep->func)

                        prio = (*ep->func)(m, off, proto, ep->arg);

                else {

#ifdef USE_RADIX

                        continue;

#else

                        prio = mask_match(ep, (struct sockaddr *)&pack.mine,

                            (struct sockaddr *)&pack.yours);

#endif

                }

                /* see encap4_lookup() for issues here */

                if (prio <= 0)

                        continue;

                if (prio > matchprio) {

                        matchprio = prio;

                        match = ep;

                }

        }

        return match;

#undef s

#undef d

}

int

encap6_input(mp, offp, proto)

        struct mbuf **mp;

        int *offp;

        int proto;

{

        struct mbuf *m = *mp;

        const struct ip6protosw *psw;

        struct encaptab *match;

        match = encap6_lookup(m, *offp, proto, INBOUND);

        if (match) {

                /* found a match */

                psw = (const struct ip6protosw *)match->psw;

                if (psw && psw->pr_input) {

                        encap_fillarg(m, match);

                        return (*psw->pr_input)(mp, offp, proto);

                } else {

                        m_freem(m);

                        return IPPROTO_DONE;

                }

        }

#ifdef __OpenBSD__

        /* last resort */

        return ip4_input6(mp, offp, 0); /* XXX last argument ignored */

#else

        /* last resort: inject to raw socket */

        return rip6_input(mp, offp, proto);

#endif

}

#endif

static int

encap_add(ep)

        struct encaptab *ep;

{

#ifdef USE_RADIX

        struct radix_node_head *rnh = encap_rnh(ep->af);

#endif

        int error = 0;

        LIST_INSERT_HEAD(&encaptab, ep, chain);

#ifdef USE_RADIX

        if (!ep->func && rnh) {

                if (!rnh->rnh_addaddr((caddr_t)ep->addrpack,

                    (caddr_t)ep->maskpack, rnh, ep->nodes)) {

                        error = EEXIST;

                        goto fail;

                }

        }

#endif

        return error;

#ifdef USE_RADIX

 fail:

        LIST_REMOVE(ep, chain);

        return error;

#endif

}

static int

encap_remove(ep)

        struct encaptab *ep;

{

#ifdef USE_RADIX

        struct radix_node_head *rnh = encap_rnh(ep->af);

#endif

        int error = 0;

        LIST_REMOVE(ep, chain);

#ifdef USE_RADIX

        if (!ep->func && rnh) {

                if (!rnh->rnh_deladdr((caddr_t)ep->addrpack,

                    (caddr_t)ep->maskpack, rnh))

                        error = ESRCH;

        }

#endif

        return error;

}

static int

encap_afcheck(af, sp, dp)

        int af;

        const struct sockaddr *sp;

        const struct sockaddr *dp;

{

        if (sp && dp) {

                if (sp->sa_len != dp->sa_len)

                        return EINVAL;

                if (af != sp->sa_family || af != dp->sa_family)

                        return EINVAL;

        } else if (!sp && !dp)

                ;

        else

                return EINVAL;

        switch (af) {

        case AF_INET:

                if (sp && sp->sa_len != sizeof(struct sockaddr_in))

                        return EINVAL;

                if (dp && dp->sa_len != sizeof(struct sockaddr_in))

                        return EINVAL;

                break;

#ifdef INET6

        case AF_INET6:

                if (sp && sp->sa_len != sizeof(struct sockaddr_in6))

                        return EINVAL;

                if (dp && dp->sa_len != sizeof(struct sockaddr_in6))

                        return EINVAL;

                break;

#endif

        default:

                return EAFNOSUPPORT;

        }

        return 0;

}

/*

 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.

 * length of mask (sm and dm) is assumed to be same as sp/dp.

 * Return value will be necessary as input (cookie) for encap_detach().

 */

const struct encaptab *

encap_attach(af, proto, sp, sm, dp, dm, psw, arg)

        int af;

        int proto;

        const struct sockaddr *sp, *sm;

        const struct sockaddr *dp, *dm;

        const struct protosw *psw;

        void *arg;

{

        struct encaptab *ep;

        int error;

        int s;

        size_t l;

        struct pack4 *pack4;

#ifdef INET6

        struct pack6 *pack6;

#endif

#if defined(__NetBSD__) || defined(__OpenBSD__)

        s = splsoftnet();

#else

        s = splnet();

#endif

        /* sanity check on args */

        error = encap_afcheck(af, sp, dp);

        if (error)

                goto fail;

        /* check if anyone have already attached with exactly same config */

        for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {

                if (ep->af != af)

                        continue;

                if (ep->proto != proto)

                        continue;

                if (ep->func)

                        continue;

#ifdef DIAGNOSTIC

                if (!ep->src || !ep->dst || !ep->srcmask || !ep->dstmask)

                        panic("null pointers in encaptab");

#endif

                if (ep->src->sa_len != sp->sa_len ||

                    bcmp(ep->src, sp, sp->sa_len) != 0 ||

                    bcmp(ep->srcmask, sm, sp->sa_len) != 0)

                        continue;

                if (ep->dst->sa_len != dp->sa_len ||

                    bcmp(ep->dst, dp, dp->sa_len) != 0 ||

                    bcmp(ep->dstmask, dm, dp->sa_len) != 0)

                        continue;

                error = EEXIST;

                goto fail;

        }

        switch (af) {

        case AF_INET:

                l = sizeof(*pack4);

                break;

#ifdef INET6

        case AF_INET6:

                l = sizeof(*pack6);

                break;

#endif

        default:

                goto fail;

        }

#ifdef DIAGNOSTIC

        /* if l exceeds the value sa_len can possibly express, it's wrong. */

        if (l > (1 << (8 * sizeof(ep->addrpack->sa_len)))) {

                error = EINVAL;

                goto fail;

        }

#endif

        ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);  /* M_NETADDR ok? */

        if (ep == NULL) {

                error = ENOBUFS;

                goto fail;

        }

        bzero(ep, sizeof(*ep));

        ep->addrpack = malloc(l, M_NETADDR, M_NOWAIT);

        if (ep->addrpack == NULL) {