/*	$NetBSD: in_gif.c,v 1.94.6.1 2019/09/24 03:10:35 martin 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 1.94.6.1 2019/09/24 03:10:35 martin 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(AF_INET, -1, var->gv_psrc,
	    (struct sockaddr *)&mask4, var->gv_pdst, (struct sockaddr *)&mask4,
	    &in_gif_encapsw, var->gv_softc);
#else
	var->gv_encap_cookie4 = encap_attach_func(AF_INET, -1, 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;
}