/*	$NetBSD: in6_gif.c,v 1.96 2022/12/07 08:30:15 knakahara Exp $	*/
/*	$KAME: in6_gif.c,v 1.62 2001/07/29 04:27:25 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: in6_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/queue.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>
#ifdef INET
#include <netinet/ip.h>
#endif
#include <netinet/ip_encap.h>
#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet6/in6_gif.h>
#include <netinet6/in6_var.h>
#endif
#include <netinet6/ip6protosw.h> /* for struct ip6ctlparam */
#include <netinet/ip_ecn.h>

#include <net/if_gif.h>

static int gif_validate6(const struct ip6_hdr *, struct gif_variant *,
	struct ifnet *);

int	ip6_gif_hlim = GIF_HLIM;
int	ip6_gif_pmtu = 0;

static const struct encapsw in6_gif_encapsw;

/* 
 * family - family of the packet to be encapsulate. 
 */

static int
in6_gif_output(struct gif_variant *var, int family, struct mbuf *m)
{
	struct rtentry *rt;
	struct gif_softc *sc;
	struct sockaddr_in6 *sin6_src;
	struct sockaddr_in6 *sin6_dst;
	struct ifnet *ifp;
	struct ip6_hdr *ip6;
	struct route *ro_pc;
	kmutex_t *lock_pc;
	int proto, error;
	u_int8_t itos, otos;

	KASSERT(gif_heldref_variant(var));

	sin6_src = satosin6(var->gv_psrc);
	sin6_dst = satosin6(var->gv_pdst);
	ifp = &var->gv_softc->gif_if;

	if (sin6_src == NULL || sin6_dst == NULL ||
	    sin6_src->sin6_family != AF_INET6 ||
	    sin6_dst->sin6_family != AF_INET6) {
		m_freem(m);
		return EAFNOSUPPORT;
	}

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

		proto = IPPROTO_IPV4;
		if (m->m_len < sizeof(*ip)) {
			m = m_pullup(m, sizeof(*ip));
			if (!m)
				return ENOBUFS;
		}
		ip = mtod(m, struct ip *);
		itos = ip->ip_tos;
		break;
	    }
#endif
#ifdef INET6
	case AF_INET6:
	    {
		proto = IPPROTO_IPV6;
		if (m->m_len < sizeof(*ip6)) {
			m = m_pullup(m, sizeof(*ip6));
			if (!m)
				return ENOBUFS;
		}
		ip6 = mtod(m, struct ip6_hdr *);
		itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
		break;
	    }
#endif
	default:
#ifdef DEBUG
		printf("in6_gif_output: warning: unknown family %d passed\n",
			family);
#endif
		m_freem(m);
		return EAFNOSUPPORT;
	}

	/* prepend new IP header */
	M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
	if (m && m->m_len < sizeof(struct ip6_hdr))
		m = m_pullup(m, sizeof(struct ip6_hdr));
	if (m == NULL)
		return ENOBUFS;

	ip6 = mtod(m, struct ip6_hdr *);
	ip6->ip6_flow	= 0;
	ip6->ip6_vfc	&= ~IPV6_VERSION_MASK;
	ip6->ip6_vfc	|= IPV6_VERSION;
#if 0	/* ip6->ip6_plen will be filled by ip6_output */
	ip6->ip6_plen	= htons((u_int16_t)m->m_pkthdr.len);
#endif
	ip6->ip6_nxt	= proto;
	ip6->ip6_hlim	= ip6_gif_hlim;
	ip6->ip6_src	= sin6_src->sin6_addr;
	/* bidirectional configured tunnel mode */
	if (!IN6_IS_ADDR_UNSPECIFIED(&sin6_dst->sin6_addr))
		ip6->ip6_dst = sin6_dst->sin6_addr;
	else  {
		m_freem(m);
		return ENETUNREACH;
	}
	if (ifp->if_flags & IFF_LINK1)
		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
	else
		ip_ecn_ingress(ECN_NOCARE, &otos, &itos);
	ip6->ip6_flow &= ~ntohl(0xff00000);
	ip6->ip6_flow |= htonl((u_int32_t)otos << 20);

	sc = ifp->if_softc;
	if_tunnel_get_ro(sc->gif_ro_percpu, &ro_pc, &lock_pc);
	rt = rtcache_lookup(ro_pc, var->gv_pdst);
	if (rt == 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);

#ifdef IPV6_MINMTU
	int flags;

	/*
	 * - GIF_PMTU_MINMTU
	 *   Force fragmentation to minimum MTU to avoid path MTU discovery
	 * - GIF_PMTU_OUTERMTU
	 *   Trust outer MTU is large enough to send all packets
	 *
	 * It is too painful to ask for resend of inner packet, to achieve
	 * path MTU discovery for encapsulated packets.
	 *
	 * See RFC4459.
	 */
	if (sc->gif_pmtu == GIF_PMTU_SYSDEFAULT) {
		switch (ip6_gif_pmtu) {
		case GIF_PMTU_MINMTU:
			flags = IPV6_MINMTU;
			break;
		case GIF_PMTU_OUTERMTU:
			flags = 0;
			break;
		default:
#ifdef DEBUG
			log(LOG_DEBUG, "%s: ignore unexpected ip6_gif_pmtu %d\n",
			    __func__, ip6_gif_pmtu);
#endif
			flags = IPV6_MINMTU;
			break;
		}
	} else {
		switch (sc->gif_pmtu) {
		case GIF_PMTU_MINMTU:
			flags = IPV6_MINMTU;
			break;
		case GIF_PMTU_OUTERMTU:
			flags = 0;
			break;
		default:
#ifdef DEBUG
			log(LOG_DEBUG, "%s: ignore unexpected gif_pmtu of %s %d\n",
			    __func__, ifp->if_xname, sc->gif_pmtu);
#endif
			flags = IPV6_MINMTU;
			break;
		}
	}

	error = ip6_output(m, 0, ro_pc, flags, NULL, NULL, NULL);
#else
	error = ip6_output(m, 0, ro_pc, 0, NULL, NULL, NULL);
#endif
	if_tunnel_put_ro(sc->gif_ro_percpu, lock_pc);
	return (error);
}

int
in6_gif_input(struct mbuf **mp, int *offp, int proto, void *eparg)
{
	struct mbuf *m = *mp;
	struct gif_softc *sc = eparg;
	struct ifnet *gifp;
	struct ip6_hdr *ip6;
	int af = 0;
	u_int32_t otos;

	KASSERT(sc != NULL);

	ip6 = mtod(m, struct ip6_hdr *);

	gifp = &sc->gif_if;
	if ((gifp->if_flags & IFF_UP) == 0) {
		m_freem(m);
		IP6_STATINC(IP6_STAT_NOGIF);
		return IPPROTO_DONE;
	}
#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);
		IP6_STATINC(IP6_STAT_NOGIF);
		return IPPROTO_DONE;
	}

	struct psref psref;
	struct ifnet *rcvif = m_get_rcvif_psref(m, &psref);
	if (rcvif == NULL || !gif_validate6(ip6, var, rcvif)) {
		m_put_rcvif_psref(rcvif, &psref);
		gif_putref_variant(var, &psref_var);
		m_freem(m);
		IP6_STATINC(IP6_STAT_NOGIF);
		return IPPROTO_DONE;
	}
	m_put_rcvif_psref(rcvif, &psref);
	gif_putref_variant(var, &psref_var);
#endif

	otos = ip6->ip6_flow;
	m_adj(m, *offp);

	switch (proto) {
#ifdef INET
	case IPPROTO_IPV4:
	    {
		struct ip *ip;
		u_int8_t otos8;
		af = AF_INET;
		otos8 = (ntohl(otos) >> 20) & 0xff;
		if (m->m_len < sizeof(*ip)) {
			m = m_pullup(m, sizeof(*ip));
			if (!m)
				return IPPROTO_DONE;
		}
		ip = mtod(m, struct ip *);
		if (gifp->if_flags & IFF_LINK1)
			ip_ecn_egress(ECN_ALLOWED, &otos8, &ip->ip_tos);
		else
			ip_ecn_egress(ECN_NOCARE, &otos8, &ip->ip_tos);
		break;
	    }
#endif /* INET */
#ifdef INET6
	case IPPROTO_IPV6:
	    {
		struct ip6_hdr *ip6x;
		af = AF_INET6;
		if (m->m_len < sizeof(*ip6x)) {
			m = m_pullup(m, sizeof(*ip6x));
			if (!m)
				return IPPROTO_DONE;
		}
		ip6x = mtod(m, struct ip6_hdr *);
		if (gifp->if_flags & IFF_LINK1)
			ip6_ecn_egress(ECN_ALLOWED, &otos, &ip6x->ip6_flow);
		else
			ip6_ecn_egress(ECN_NOCARE, &otos, &ip6x->ip6_flow);
		break;
	    }
#endif
	default:
		IP6_STATINC(IP6_STAT_NOGIF);
		m_freem(m);
		return IPPROTO_DONE;
	}

	gif_input(m, af, gifp);
	return IPPROTO_DONE;
}

/*
 * validate outer address.
 */
static int
gif_validate6(const struct ip6_hdr *ip6, struct gif_variant *var, 
	struct ifnet *ifp)
{
	const struct sockaddr_in6 *src, *dst;
	int ret;

	src = satosin6(var->gv_psrc);
	dst = satosin6(var->gv_pdst);

	ret = in6_tunnel_validate(ip6, &src->sin6_addr, &dst->sin6_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_in6 sin6;
		} u;
		struct rtentry *rt;

		/* XXX scopeid */
		sockaddr_in6_init(&u.sin6, &ip6->ip6_src, 0, 0, 0);
		rt = rtalloc1(&u.sa, 0);
		if (rt == NULL || rt->rt_ifp != ifp) {
#if 0
			char ip6buf[INET6_ADDRSTRLEN];
			log(LOG_WARNING, "%s: packet from %s dropped "
			    "due to ingress filter\n",
			    if_name(&var->gv_softc->gif_if),
			    IN6_PRINT(ip6buf, &u.sin6.sin6_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_encapcheck6(struct mbuf *m, int off, int proto, struct gif_variant *var)
{
	struct ip6_hdr ip6;
	struct ifnet *ifp = NULL;
	int r;
	struct psref psref;

	m_copydata(m, 0, sizeof(ip6), (void *)&ip6);
	if ((m->m_flags & M_PKTHDR) != 0)
		ifp = m_get_rcvif_psref(m, &psref);

	r = gif_validate6(&ip6, var, ifp);

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

int
in6_gif_attach(struct gif_variant *var)
{
#ifndef GIF_ENCAPCHECK
	struct sockaddr_in6 mask6;

	memset(&mask6, 0, sizeof(mask6));
	mask6.sin6_len = sizeof(struct sockaddr_in6);
	mask6.sin6_addr.s6_addr32[0] = mask6.sin6_addr.s6_addr32[1] =
	    mask6.sin6_addr.s6_addr32[2] = mask6.sin6_addr.s6_addr32[3] = ~0;

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

	var->gv_encap_cookie6 = encap_attach_addr(AF_INET6, -1, var->gv_psrc,
	    var->gv_pdst, NULL, &in6_gif_encapsw, var->gv_softc);
#else
	var->gv_encap_cookie6 = encap_attach_addr(AF_INET6, -1, var->gv_psrc,
	    var->gv_pdst, gif_encapcheck, &in6_gif_encapsw, var->gv_softc);
#endif
	if (var->gv_encap_cookie6 == NULL)
		return EEXIST;

	var->gv_output = in6_gif_output;
	return 0;
}

int
in6_gif_detach(struct gif_variant *var)
{
	int error;
	struct gif_softc *sc = var->gv_softc;

	error = encap_detach(var->gv_encap_cookie6);
	if (error == 0)
		var->gv_encap_cookie6 = NULL;

	if_tunnel_ro_percpu_rtcache_free(sc->gif_ro_percpu);

	return error;
}

void *
in6_gif_ctlinput(int cmd, const struct sockaddr *sa, void *d, void *eparg)
{
	struct gif_softc *sc = eparg;
	struct gif_variant *var;
	struct ip6ctlparam *ip6cp = NULL;
	struct ip6_hdr *ip6;
	const struct sockaddr_in6 *dst6;
	struct route *ro_pc;
	kmutex_t *lock_pc;
	struct psref psref;

	if (sa->sa_family != AF_INET6 ||
	    sa->sa_len != sizeof(struct sockaddr_in6))
		return NULL;

	if ((unsigned)cmd >= PRC_NCMDS)
		return NULL;
	if (cmd == PRC_HOSTDEAD)
		d = NULL;
	else if (inet6ctlerrmap[cmd] == 0)
		return NULL;

	/* if the parameter is from icmp6, decode it. */
	if (d != NULL) {
		ip6cp = (struct ip6ctlparam *)d;
		ip6 = ip6cp->ip6c_ip6;
	} else {
		ip6 = NULL;
	}

	if (!ip6)
		return NULL;

	var = gif_getref_variant(sc, &psref);
	if (var->gv_psrc == NULL || var->gv_pdst == NULL) {
		gif_putref_variant(var, &psref);
		return NULL;
	}
	if (var->gv_psrc->sa_family != AF_INET6) {
		gif_putref_variant(var, &psref);
		return NULL;
	}
	gif_putref_variant(var, &psref);

	if_tunnel_get_ro(sc->gif_ro_percpu, &ro_pc, &lock_pc);
	dst6 = satocsin6(rtcache_getdst(ro_pc));
	/* XXX scope */
	if (dst6 == NULL)
		;
	else if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst6->sin6_addr))
		rtcache_free(ro_pc);

	if_tunnel_put_ro(sc->gif_ro_percpu, lock_pc);
	return NULL;
}

ENCAP_PR_WRAP_CTLINPUT(in6_gif_ctlinput)
#define	in6_gif_ctlinput	in6_gif_ctlinput_wrapper

static const struct encapsw in6_gif_encapsw = {
	.encapsw6 = {
		.pr_input	= in6_gif_input,
		.pr_ctlinput	= in6_gif_ctlinput,
	}
};