/*      $NetBSD: in_gif.c,v 1.96 2022/12/07 08:30:15 knakahara Exp $    */
/*      $KAME: in_gif.c,v 1.66 2001/07/29 04:46:09 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in_gif.c,v 1.96 2022/12/07 08:30:15 knakahara Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/syslog.h>
#include <sys/kernel.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/in_gif.h>
#include <netinet/in_var.h>
#include <netinet/ip_encap.h>
#include <netinet/ip_ecn.h>

#ifdef INET6
#include <netinet/ip6.h>
#endif

#include <net/if_gif.h>

static int gif_validate4(const struct ip *, struct gif_variant *,
        struct ifnet *);

int ip_gif_ttl = GIF_TTL;

static const struct encapsw in_gif_encapsw = {
        .encapsw4 = {
                .pr_input       = in_gif_input,
                .pr_ctlinput    = NULL,
        }
};

static int
in_gif_output(struct gif_variant *var, int family, struct mbuf *m)
{
        struct rtentry *rt;
        struct gif_softc *sc;
        struct sockaddr_in *sin_src;
        struct sockaddr_in *sin_dst;
        struct ifnet *ifp;
        struct route *ro_pc;
        kmutex_t *lock_pc;
        struct ip iphdr;        /* capsule IP header, host byte ordered */
        int proto, error;
        u_int8_t tos;

        KASSERT(gif_heldref_variant(var));

        sin_src = satosin(var->gv_psrc);
        sin_dst = satosin(var->gv_pdst);
        ifp = &var->gv_softc->gif_if;

        if (sin_src == NULL || sin_dst == NULL ||
            sin_src->sin_family != AF_INET ||
            sin_dst->sin_family != AF_INET) {
                m_freem(m);
                return EAFNOSUPPORT;
        }

        switch (family) {
#ifdef INET
        case AF_INET:
            {
                const struct ip *ip;

                proto = IPPROTO_IPV4;
                if (m->m_len < sizeof(*ip)) {
                        m = m_pullup(m, sizeof(*ip));
                        if (m == NULL)
                                return ENOBUFS;
                }
                ip = mtod(m, const struct ip *);
                tos = ip->ip_tos;
                break;
            }
#endif /* INET */
#ifdef INET6
        case AF_INET6:
            {
                const struct ip6_hdr *ip6;
                proto = IPPROTO_IPV6;
                if (m->m_len < sizeof(*ip6)) {
                        m = m_pullup(m, sizeof(*ip6));
                        if (m == NULL)
                                return ENOBUFS;
                }
                ip6 = mtod(m, const struct ip6_hdr *);
                tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
                break;
            }
#endif /* INET6 */
        default:
#ifdef DEBUG
                printf("in_gif_output: warning: unknown family %d passed\n",
                        family);
#endif
                m_freem(m);
                return EAFNOSUPPORT;
        }

        memset(&iphdr, 0, sizeof(iphdr));
        iphdr.ip_src = sin_src->sin_addr;
        /* bidirectional configured tunnel mode */
        if (sin_dst->sin_addr.s_addr != INADDR_ANY)
                iphdr.ip_dst = sin_dst->sin_addr;
        else {
                m_freem(m);
                return ENETUNREACH;
        }
        iphdr.ip_p = proto;
        /* version will be set in ip_output() */
        iphdr.ip_ttl = ip_gif_ttl;
        iphdr.ip_len = htons(m->m_pkthdr.len + sizeof(struct ip));
        if (ifp->if_flags & IFF_LINK1)
                ip_ecn_ingress(ECN_ALLOWED, &iphdr.ip_tos, &tos);
        else
                ip_ecn_ingress(ECN_NOCARE, &iphdr.ip_tos, &tos);

        /* prepend new IP header */
        M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
        /* XXX Is m_pullup really necessary after M_PREPEND? */
        if (m != NULL && M_UNWRITABLE(m, sizeof(struct ip)))
                m = m_pullup(m, sizeof(struct ip));
        if (m == NULL)
                return ENOBUFS;
        bcopy(&iphdr, mtod(m, struct ip *), sizeof(struct ip));

        sc = var->gv_softc;
        if_tunnel_get_ro(sc->gif_ro_percpu, &ro_pc, &lock_pc);
        if ((rt = rtcache_lookup(ro_pc, var->gv_pdst)) == NULL) {
                if_tunnel_put_ro(sc->gif_ro_percpu, lock_pc);
                m_freem(m);
                return ENETUNREACH;
        }

        /* If the route constitutes infinite encapsulation, punt. */
        if (rt->rt_ifp == ifp) {
                rtcache_unref(rt, ro_pc);
                rtcache_free(ro_pc);
                if_tunnel_put_ro(sc->gif_ro_percpu, lock_pc);
                m_freem(m);
                return ENETUNREACH;     /*XXX*/
        }
        rtcache_unref(rt, ro_pc);

        error = ip_output(m, NULL, ro_pc, 0, NULL, NULL);
        if_tunnel_put_ro(sc->gif_ro_percpu, lock_pc);
        return (error);
}

void
in_gif_input(struct mbuf *m, int off, int proto, void *eparg)
{
        struct gif_softc *sc = eparg;
        struct ifnet *gifp = &sc->gif_if;
        const struct ip *ip;
        int af;
        u_int8_t otos;

        KASSERT(sc != NULL);

        ip = mtod(m, const struct ip *);

        gifp = &sc->gif_if;
        if ((gifp->if_flags & IFF_UP) == 0) {
                m_freem(m);
                ip_statinc(IP_STAT_NOGIF);
                return;
        }
#ifndef GIF_ENCAPCHECK
        struct psref psref_var;
        struct gif_variant *var = gif_getref_variant(sc, &psref_var);
        /* other CPU do delete_tunnel */
        if (var->gv_psrc == NULL || var->gv_pdst == NULL) {
                gif_putref_variant(var, &psref_var);
                m_freem(m);
                ip_statinc(IP_STAT_NOGIF);
                return;
        }

        struct ifnet *rcvif;
        struct psref psref_rcvif;
        rcvif = m_get_rcvif_psref(m, &psref_rcvif);
        if (!gif_validate4(ip, var, rcvif)) {
                m_put_rcvif_psref(rcvif, &psref_rcvif);
                gif_putref_variant(var, &psref_var);
                m_freem(m);
                ip_statinc(IP_STAT_NOGIF);
                return;
        }
        m_put_rcvif_psref(rcvif, &psref_rcvif);
        gif_putref_variant(var, &psref_var);
#endif
        otos = ip->ip_tos;
        m_adj(m, off);

        switch (proto) {
#ifdef INET
        case IPPROTO_IPV4:
            {
                struct ip *xip;
                af = AF_INET;
                if (M_UNWRITABLE(m, sizeof(*xip))) {
                        if ((m = m_pullup(m, sizeof(*xip))) == NULL)
                                return;
                }
                xip = mtod(m, struct ip *);
                if (gifp->if_flags & IFF_LINK1)
                        ip_ecn_egress(ECN_ALLOWED, &otos, &xip->ip_tos);
                else
                        ip_ecn_egress(ECN_NOCARE, &otos, &xip->ip_tos);
                break;
            }
#endif
#ifdef INET6
        case IPPROTO_IPV6:
            {
                struct ip6_hdr *ip6;
                u_int8_t itos;
                af = AF_INET6;
                if (M_UNWRITABLE(m, sizeof(*ip6))) {
                        if ((m = m_pullup(m, sizeof(*ip6))) == NULL)
                                return;
                }
                ip6 = mtod(m, struct ip6_hdr *);
                itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
                if (gifp->if_flags & IFF_LINK1)
                        ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
                else
                        ip_ecn_egress(ECN_NOCARE, &otos, &itos);
                ip6->ip6_flow &= ~htonl(0xff << 20);
                ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
                break;
            }
#endif /* INET6 */
        default:
                ip_statinc(IP_STAT_NOGIF);
                m_freem(m);
                return;
        }
        gif_input(m, af, gifp);
        return;
}

/*
 * validate outer address.
 */
static int
gif_validate4(const struct ip *ip, struct gif_variant *var, struct ifnet *ifp)
{
        struct sockaddr_in *src, *dst;
        int ret;

        src = satosin(var->gv_psrc);
        dst = satosin(var->gv_pdst);

        ret = in_tunnel_validate(ip, src->sin_addr, dst->sin_addr);
        if (ret == 0)
                return 0;

        /* ingress filters on outer source */
        if ((var->gv_softc->gif_if.if_flags & IFF_LINK2) == 0 && ifp) {
                union {
                        struct sockaddr sa;
                        struct sockaddr_in sin;
                } u;
                struct rtentry *rt;

                sockaddr_in_init(&u.sin, &ip->ip_src, 0);
                rt = rtalloc1(&u.sa, 0);
                if (rt == NULL || rt->rt_ifp != ifp) {
#if 0
                        log(LOG_WARNING, "%s: packet from 0x%x dropped "
                            "due to ingress filter\n",
                            if_name(&var->gv_softc->gif_if),
                            (u_int32_t)ntohl(u.sin.sin_addr.s_addr));
#endif
                        if (rt != NULL)
                                rt_unref(rt);
                        return 0;
                }
                rt_unref(rt);
        }

        return ret;
}

#ifdef GIF_ENCAPCHECK
/*
 * we know that we are in IFF_UP, outer address available, and outer family
 * matched the physical addr family.  see gif_encapcheck().
 */
int
gif_encapcheck4(struct mbuf *m, int off, int proto, struct gif_variant *var)
{
        struct ip ip;

        struct ifnet *ifp = NULL;
        int r;
        struct psref psref;

        m_copydata(m, 0, sizeof(ip), &ip);
        if ((m->m_flags & M_PKTHDR) != 0)
                ifp = m_get_rcvif_psref(m, &psref);

        r = gif_validate4(&ip, var, ifp);

        m_put_rcvif_psref(ifp, &psref);
        return r;
}
#endif

int
in_gif_attach(struct gif_variant *var)
{
#ifndef GIF_ENCAPCHECK
        struct sockaddr_in mask4;

        memset(&mask4, 0, sizeof(mask4));
        mask4.sin_len = sizeof(struct sockaddr_in);
        mask4.sin_addr.s_addr = ~0;

        if (!var->gv_psrc || !var->gv_pdst)
                return EINVAL;

        var->gv_encap_cookie4 = encap_attach_addr(AF_INET, -1, var->gv_psrc,
            var->gv_pdst, NULL, &in_gif_encapsw, var->gv_softc);
#else
        var->gv_encap_cookie4 = encap_attach_addr(AF_INET, -1, var->gv_psrc,
            var->gv_pdst, gif_encapcheck, &in_gif_encapsw, var->gv_softc);
#endif
        if (var->gv_encap_cookie4 == NULL)
                return EEXIST;

        var->gv_output = in_gif_output;
        return 0;
}

int
in_gif_detach(struct gif_variant *var)
{
        int error;
        struct gif_softc *sc = var->gv_softc;

        error = encap_detach(var->gv_encap_cookie4);
        if (error == 0)
                var->gv_encap_cookie4 = NULL;

        if_tunnel_ro_percpu_rtcache_free(sc->gif_ro_percpu);

        return error;
}