ip6_fw.c
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ip6_fw.c
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	/* $FreeBSD$ */
	/* $KAME: ip6_fw.c,v 1.15 2000/07/02 14:17:37 itojun Exp $ */

	/*
	* Copyright (c) 1993 Daniel Boulet
	* Copyright (c) 1994 Ugen J.S.Antsilevich
	* Copyright (c) 1996 Alex Nash
	*
	* Redistribution and use in source forms, with and without modification,
	* are permitted provided that this entire comment appears intact.
	*
	* Redistribution in binary form may occur without any restrictions.
	* Obviously, it would be nice if you gave credit where credit is due
	* but requiring it would be too onerous.
	*
	* This software is provided ``AS IS'' without any warranties of any kind.
	*/

	/*
	* Implement IPv6 packet firewall
	*/

	#include "opt_ip6fw.h"
	#include "opt_inet.h"
	#include "opt_inet6.h"

	#ifdef IP6DIVERT
	#error "NOT SUPPORTED IPV6 DIVERT"
	#endif
	#ifdef IP6FW_DIVERT_RESTART
	#error "NOT SUPPORTED IPV6 DIVERT"
	#endif

	#include <sys/param.h>
	#include <sys/systm.h>
	#include <sys/malloc.h>
	#include <sys/mbuf.h>
	#include <sys/queue.h>
	#include <sys/kernel.h>
	#include <sys/socket.h>
	#include <sys/socketvar.h>
	#include <sys/time.h>
	#include <net/if.h>
	#include <net/route.h>
	#include <netinet/in_systm.h>
	#include <netinet/in.h>
	#include <netinet/ip.h>

	#include <netinet/ip6.h>
	#include <netinet6/ip6_var.h>
	#include <netinet6/in6_var.h>
	#include <netinet/icmp6.h>

	#include <netinet/in_pcb.h>

	#include <netinet6/ip6_fw.h>
	#include <netinet/ip_var.h>
	#include <netinet/tcp.h>
	#include <netinet/tcp_seq.h>
	#include <netinet/tcp_timer.h>
	#include <netinet/tcp_var.h>
	#include <netinet/udp.h>

	#include <sys/sysctl.h>

	#include <net/net_osdep.h>

	MALLOC_DEFINE(M_IP6FW, "Ip6Fw/Ip6Acct", "Ip6Fw/Ip6Acct chain's");

	static int fw6_debug = 1;
	#ifdef IPV6FIREWALL_VERBOSE
	static int fw6_verbose = 1;
	#else
	static int fw6_verbose = 0;
	#endif
	#ifdef IPV6FIREWALL_VERBOSE_LIMIT
	static int fw6_verbose_limit = IPV6FIREWALL_VERBOSE_LIMIT;
	#else
	static int fw6_verbose_limit = 0;
	#endif

	LIST_HEAD (ip6_fw_head, ip6_fw_chain) ip6_fw_chain;

	#ifdef SYSCTL_NODE
	SYSCTL_DECL(_net_inet6_ip6);
	SYSCTL_NODE(_net_inet6_ip6, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
	SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, debug, CTLFLAG_RW, &fw6_debug, 0, "");
	SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw6_verbose, 0, "");
	SYSCTL_INT(_net_inet6_ip6_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw6_verbose_limit, 0, "");
	#endif

	#define dprintf(a) if (!fw6_debug); else printf a

	#define print_ip6(a) printf("[%s]", ip6_sprintf(a))

	#define dprint_ip6(a) if (!fw6_debug); else print_ip6(a)

	static int add_entry6 __P((struct ip6_fw_head chainptr, struct ip6_fw frwl));
	static int del_entry6 __P((struct ip6_fw_head *chainptr, u_short number));
	static int zero_entry6 __P((struct mbuf *m));
	static struct ip6_fw check_ip6fw_struct __P((struct ip6_fw m));
	static struct ip6_fw check_ip6fw_mbuf __P((struct mbuf fw));
	static int ip6opts_match __P((struct ip6_hdr *ip6, struct ip6_fw f,
	struct mbuf **m,
	int off, int nxt, u_short *offset));
	static int port_match6 __P((u_short *portptr, int nports, u_short port,
	int range_flag));
	static int tcp6flg_match __P((struct tcphdr tcp6, struct ip6_fw f));
	static int icmp6type_match __P((struct icmp6_hdr * icmp, struct ip6_fw * f));
	static void ip6fw_report __P((struct ip6_fw f, struct ip6_hdr ip6,
	struct ifnet rif, struct ifnet oif, int off, int nxt));

	static int ip6_fw_chk __P((struct ip6_hdr **pip6,
	struct ifnet oif, u_int16_t cookie, struct mbuf **m));
	static int ip6_fw_ctl __P((int stage, struct mbuf **mm));

	static char err_prefix[] = "ip6_fw_ctl:";

	/*
	* Returns 1 if the port is matched by the vector, 0 otherwise
	*/
	static
	__inline int
	port_match6(u_short *portptr, int nports, u_short port, int range_flag)
	{
	if (!nports)
	return 1;
	if (range_flag) {
	if (portptr[0] <= port && port <= portptr[1]) {
	return 1;
	}
	nports -= 2;
	portptr += 2;
	}
	while (nports-- > 0) {
	if (*portptr++ == port) {
	return 1;
	}
	}
	return 0;
	}

	static int
	tcp6flg_match(struct tcphdr tcp6, struct ip6_fw f)
	{
	u_char flg_set, flg_clr;

	if ((f->fw_tcpf & IPV6_FW_TCPF_ESTAB) &&
	(tcp6->th_flags & (IPV6_FW_TCPF_RST \| IPV6_FW_TCPF_ACK)))
	return 1;

	flg_set = tcp6->th_flags & f->fw_tcpf;
	flg_clr = tcp6->th_flags & f->fw_tcpnf;

	if (flg_set != f->fw_tcpf)
	return 0;
	if (flg_clr)
	return 0;

	return 1;
	}

	static int
	icmp6type_match(struct icmp6_hdr icmp6, struct ip6_fw f)
	{
	int type;

	if (!(f->fw_flg & IPV6_FW_F_ICMPBIT))
	return(1);

	type = icmp6->icmp6_type;

	/* check for matching type in the bitmap */
	if (type < IPV6_FW_ICMPTYPES_DIM * sizeof(unsigned) * 8 &&
	(f->fw_icmp6types[type / (sizeof(unsigned) * 8)] &
	(1U << (type % (8 * sizeof(unsigned))))))
	return(1);

	return(0); /* no match */
	}

	static int
	is_icmp6_query(struct ip6_hdr *ip6, int off)
	{
	const struct icmp6_hdr *icmp6;
	int icmp6_type;

	icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
	icmp6_type = icmp6->icmp6_type;

	if (icmp6_type == ICMP6_ECHO_REQUEST \|\|
	icmp6_type == ICMP6_MEMBERSHIP_QUERY \|\|
	icmp6_type == ICMP6_WRUREQUEST \|\|
	icmp6_type == ICMP6_FQDN_QUERY \|\|
	icmp6_type == ICMP6_NI_QUERY)
	return(1);

	return(0);
	}

	static int
	ip6opts_match(struct ip6_hdr *pip6, struct ip6_fw f, struct mbuf **m,
	int off, int nxt, u_short *offset)
	{
	int len;
	struct ip6_hdr ip6 = pip6;
	struct ip6_ext *ip6e;
	u_char opts, nopts, nopts_sve;

	opts = f->fw_ip6opt;
	nopts = nopts_sve = f->fw_ip6nopt;

	*nxt = ip6->ip6_nxt;
	*off = sizeof(struct ip6_hdr);
	len = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr);
	while (*off < len) {
	ip6e = (struct ip6_ext )((caddr_t) ip6 + off);
	if ((m)->m_len < off + sizeof(*ip6e))
	goto opts_check; /* XXX */

	switch(*nxt) {
	case IPPROTO_FRAGMENT:
	if ((m)->m_len < off + sizeof(struct ip6_frag)) {
	struct ip6_frag *ip6f;

	ip6f = (struct ip6_frag ) ((caddr_t)ip6 + off);
	*offset = ip6f->ip6f_offlg \| IP6F_OFF_MASK;
	}
	opts &= ~IPV6_FW_IP6OPT_FRAG;
	nopts &= ~IPV6_FW_IP6OPT_FRAG;
	*off += sizeof(struct ip6_frag);
	break;
	case IPPROTO_AH:
	opts &= ~IPV6_FW_IP6OPT_AH;
	nopts &= ~IPV6_FW_IP6OPT_AH;
	*off += (ip6e->ip6e_len + 2) << 2;
	break;
	default:
	switch (*nxt) {
	case IPPROTO_HOPOPTS:
	opts &= ~IPV6_FW_IP6OPT_HOPOPT;
	nopts &= ~IPV6_FW_IP6OPT_HOPOPT;
	break;
	case IPPROTO_ROUTING:
	opts &= ~IPV6_FW_IP6OPT_ROUTE;
	nopts &= ~IPV6_FW_IP6OPT_ROUTE;
	break;
	case IPPROTO_ESP:
	opts &= ~IPV6_FW_IP6OPT_ESP;
	nopts &= ~IPV6_FW_IP6OPT_ESP;
	break;
	case IPPROTO_NONE:
	opts &= ~IPV6_FW_IP6OPT_NONXT;
	nopts &= ~IPV6_FW_IP6OPT_NONXT;
	goto opts_check;
	break;
	case IPPROTO_DSTOPTS:
	opts &= ~IPV6_FW_IP6OPT_OPTS;
	nopts &= ~IPV6_FW_IP6OPT_OPTS;
	break;
	default:
	goto opts_check;
	break;
	}
	*off += (ip6e->ip6e_len + 1) << 3;
	break;
	}
	*nxt = ip6e->ip6e_nxt;

	}
	opts_check:
	if (f->fw_ip6opt == f->fw_ip6nopt) /* XXX */
	return 1;

	if (opts == 0 && nopts == nopts_sve)
	return 1;
	else
	return 0;
	}

	static
	__inline int
	iface_match(struct ifnet ifp, union ip6_fw_if ifu, int byname)
	{
	/* Check by name or by IP address */
	if (byname) {
	/* Check unit number (-1 is wildcard) */
	if (ifu->fu_via_if.unit != -1
	&& ifp->if_unit != ifu->fu_via_if.unit)
	return(0);
	/* Check name */
	if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN))
	return(0);
	return(1);
	} else if (!IN6_IS_ADDR_UNSPECIFIED(&ifu->fu_via_ip6)) { /* Zero == wildcard */
	struct ifaddr *ia;

	for (ia = ifp->if_addrlist.tqh_first; ia; ia = ia->ifa_list.tqe_next)
	{

	if (ia->ifa_addr == NULL)
	continue;
	if (ia->ifa_addr->sa_family != AF_INET6)
	continue;
	if (!IN6_ARE_ADDR_EQUAL(&ifu->fu_via_ip6,
	&(((struct sockaddr_in6 *)
	(ia->ifa_addr))->sin6_addr)))
	continue;
	return(1);
	}
	return(0);
	}
	return(1);
	}

	static void
	ip6fw_report(struct ip6_fw f, struct ip6_hdr ip6,
	struct ifnet rif, struct ifnet oif, int off, int nxt)
	{
	static int counter;
	struct tcphdr const tcp6 = (struct tcphdr ) ((caddr_t) ip6+ off);
	struct udphdr const udp = (struct udphdr ) ((caddr_t) ip6+ off);
	struct icmp6_hdr const icmp6 = (struct icmp6_hdr ) ((caddr_t) ip6+ off);
	int count;

	count = f ? f->fw_pcnt : ++counter;
	if (fw6_verbose_limit != 0 && count > fw6_verbose_limit)
	return;

	/* Print command name */
	printf("ip6fw: %d ", f ? f->fw_number : -1);
	if (!f)
	printf("Refuse");
	else
	switch (f->fw_flg & IPV6_FW_F_COMMAND) {
	case IPV6_FW_F_DENY:
	printf("Deny");
	break;
	case IPV6_FW_F_REJECT:
	if (f->fw_reject_code == IPV6_FW_REJECT_RST)
	printf("Reset");
	else
	printf("Unreach");
	break;
	case IPV6_FW_F_ACCEPT:
	printf("Accept");
	break;
	case IPV6_FW_F_COUNT:
	printf("Count");
	break;
	case IPV6_FW_F_DIVERT:
	printf("Divert %d", f->fw_divert_port);
	break;
	case IPV6_FW_F_TEE:
	printf("Tee %d", f->fw_divert_port);
	break;
	case IPV6_FW_F_SKIPTO:
	printf("SkipTo %d", f->fw_skipto_rule);
	break;
	default:
	printf("UNKNOWN");
	break;
	}
	printf(" ");

	switch (nxt) {
	case IPPROTO_TCP:
	printf("TCP ");
	print_ip6(&ip6->ip6_src);
	if (off > 0)
	printf(":%d ", ntohs(tcp6->th_sport));
	else
	printf(" ");
	print_ip6(&ip6->ip6_dst);
	if (off > 0)
	printf(":%d", ntohs(tcp6->th_dport));
	break;
	case IPPROTO_UDP:
	printf("UDP ");
	print_ip6(&ip6->ip6_src);
	if (off > 0)
	printf(":%d ", ntohs(udp->uh_sport));
	else
	printf(" ");
	print_ip6(&ip6->ip6_dst);
	if (off > 0)
	printf(":%d", ntohs(udp->uh_dport));
	break;
	case IPPROTO_ICMPV6:
	if (off > 0)
	printf("IPV6-ICMP:%u.%u ", icmp6->icmp6_type, icmp6->icmp6_code);
	else
	printf("IPV6-ICMP ");
	print_ip6(&ip6->ip6_src);
	printf(" ");
	print_ip6(&ip6->ip6_dst);
	break;
	default:
	printf("P:%d ", nxt);
	print_ip6(&ip6->ip6_src);
	printf(" ");
	print_ip6(&ip6->ip6_dst);
	break;
	}
	if (oif)
	printf(" out via %s", if_name(oif));
	else if (rif)
	printf(" in via %s", if_name(rif));
	printf("\n");
	if (fw6_verbose_limit != 0 && count == fw6_verbose_limit)
	printf("ip6fw: limit reached on rule #%d\n",
	f ? f->fw_number : -1);
	}

	/*
	* Parameters:
	*
	* ip Pointer to packet header (struct ip6_hdr *)
	* hlen Packet header length
	* oif Outgoing interface, or NULL if packet is incoming
	* #ifndef IP6FW_DIVERT_RESTART
	* *cookie Ignore all divert/tee rules to this port (if non-zero)
	* #else
	* *cookie Skip up to the first rule past this rule number;
	* #endif
	* *m The packet; we set to NULL when/if we nuke it.
	*
	* Return value:
	*
	* 0 The packet is to be accepted and routed normally OR
	* the packet was denied/rejected and has been dropped;
	* in the latter case, *m is equal to NULL upon return.
	* port Divert the packet to port.
	*/

	static int
	ip6_fw_chk(struct ip6_hdr **pip6,
	struct ifnet oif, u_int16_t cookie, struct mbuf **m)
	{
	struct ip6_fw_chain *chain;
	struct ip6_fw *rule = NULL;
	struct ip6_hdr ip6 = pip6;
	struct ifnet const rif = (m)->m_pkthdr.rcvif;
	u_short offset = 0;
	int off = sizeof(struct ip6_hdr), nxt = ip6->ip6_nxt;
	u_short src_port, dst_port;
	#ifdef IP6FW_DIVERT_RESTART
	u_int16_t skipto = *cookie;
	#else
	u_int16_t ignport = ntohs(*cookie);
	#endif

	*cookie = 0;
	/*
	* Go down the chain, looking for enlightment
	* #ifdef IP6FW_DIVERT_RESTART
	* If we've been asked to start at a given rule immediatly, do so.
	* #endif
	*/
	chain = LIST_FIRST(&ip6_fw_chain);
	#ifdef IP6FW_DIVERT_RESTART
	if (skipto) {
	if (skipto >= 65535)
	goto dropit;
	while (chain && (chain->rule->fw_number <= skipto)) {
	chain = LIST_NEXT(chain, chain);
	}
	if (! chain) goto dropit;
	}
	#endif /* IP6FW_DIVERT_RESTART */
	for (; chain; chain = LIST_NEXT(chain, chain)) {
	register struct ip6_fw *const f = chain->rule;

	if (oif) {
	/* Check direction outbound */
	if (!(f->fw_flg & IPV6_FW_F_OUT))
	continue;
	} else {
	/* Check direction inbound */
	if (!(f->fw_flg & IPV6_FW_F_IN))
	continue;
	}

	#define IN6_ARE_ADDR_MASKEQUAL(x,y,z) (\
	(((x)->s6_addr32[0] & (y)->s6_addr32[0]) == (z)->s6_addr32[0]) && \
	(((x)->s6_addr32[1] & (y)->s6_addr32[1]) == (z)->s6_addr32[1]) && \
	(((x)->s6_addr32[2] & (y)->s6_addr32[2]) == (z)->s6_addr32[2]) && \
	(((x)->s6_addr32[3] & (y)->s6_addr32[3]) == (z)->s6_addr32[3]))

	/* If src-addr doesn't match, not this rule. */
	if (((f->fw_flg & IPV6_FW_F_INVSRC) != 0) ^
	(!IN6_ARE_ADDR_MASKEQUAL(&ip6->ip6_src,&f->fw_smsk,&f->fw_src)))
	continue;

	/* If dest-addr doesn't match, not this rule. */
	if (((f->fw_flg & IPV6_FW_F_INVDST) != 0) ^
	(!IN6_ARE_ADDR_MASKEQUAL(&ip6->ip6_dst,&f->fw_dmsk,&f->fw_dst)))
	continue;

	#undef IN6_ARE_ADDR_MASKEQUAL
	/* Interface check */
	if ((f->fw_flg & IF6_FW_F_VIAHACK) == IF6_FW_F_VIAHACK) {
	struct ifnet *const iface = oif ? oif : rif;

	/* Backwards compatibility hack for "via" */
	if (!iface \|\| !iface_match(iface,
	&f->fw_in_if, f->fw_flg & IPV6_FW_F_OIFNAME))
	continue;
	} else {
	/* Check receive interface */
	if ((f->fw_flg & IPV6_FW_F_IIFACE)
	&& (!rif \|\| !iface_match(rif,
	&f->fw_in_if, f->fw_flg & IPV6_FW_F_IIFNAME)))
	continue;
	/* Check outgoing interface */
	if ((f->fw_flg & IPV6_FW_F_OIFACE)
	&& (!oif \|\| !iface_match(oif,
	&f->fw_out_if, f->fw_flg & IPV6_FW_F_OIFNAME)))
	continue;
	}

	/* Check IP options */
	if (!ip6opts_match(&ip6, f, m, &off, &nxt, &offset))
	continue;

	/* Fragments */
	if ((f->fw_flg & IPV6_FW_F_FRAG) && !offset)
	continue;

	/* Check protocol; if wildcard, match */
	if (f->fw_prot == IPPROTO_IPV6)
	goto got_match;

	/* If different, don't match */
	if (nxt != f->fw_prot)
	continue;

	#define PULLUP_TO(len) do { \
	if ((*m)->m_len < (len) \
	&& (m = m_pullup(m, (len))) == 0) { \
	goto dropit; \
	} \
	pip6 = ip6 = mtod(m, struct ip6_hdr *); \
	} while (0)

	/* Protocol specific checks */
	switch (nxt) {
	case IPPROTO_TCP:
	{
	struct tcphdr *tcp6;

	if (offset == 1) { /* cf. RFC 1858 */
	PULLUP_TO(off + 4); /* XXX ? */
	goto bogusfrag;
	}
	if (offset != 0) {
	/*
	* TCP flags and ports aren't available in this
	* packet -- if this rule specified either one,
	* we consider the rule a non-match.
	*/
	if (f->fw_nports != 0 \|\|
	f->fw_tcpf != f->fw_tcpnf)
	continue;

	break;
	}
	PULLUP_TO(off + 14);
	tcp6 = (struct tcphdr *) ((caddr_t)ip6 + off);
	if (f->fw_tcpf != f->fw_tcpnf && !tcp6flg_match(tcp6, f))
	continue;
	src_port = ntohs(tcp6->th_sport);
	dst_port = ntohs(tcp6->th_dport);
	goto check_ports;
	}

	case IPPROTO_UDP:
	{
	struct udphdr *udp;

	if (offset != 0) {
	/*
	* Port specification is unavailable -- if this
	* rule specifies a port, we consider the rule
	* a non-match.
	*/
	if (f->fw_nports != 0)
	continue;

	break;
	}
	PULLUP_TO(off + 4);
	udp = (struct udphdr *) ((caddr_t)ip6 + off);
	src_port = ntohs(udp->uh_sport);
	dst_port = ntohs(udp->uh_dport);
	check_ports:
	if (!port_match6(&f->fw_pts[0],
	IPV6_FW_GETNSRCP(f), src_port,
	f->fw_flg & IPV6_FW_F_SRNG))
	continue;
	if (!port_match6(&f->fw_pts[IPV6_FW_GETNSRCP(f)],
	IPV6_FW_GETNDSTP(f), dst_port,
	f->fw_flg & IPV6_FW_F_DRNG))
	continue;
	break;
	}

	case IPPROTO_ICMPV6:
	{
	struct icmp6_hdr *icmp;

	if (offset != 0) /* Type isn't valid */
	break;
	PULLUP_TO(off + 2);
	icmp = (struct icmp6_hdr *) ((caddr_t)ip6 + off);
	if (!icmp6type_match(icmp, f))
	continue;
	break;
	}
	#undef PULLUP_TO

	bogusfrag:
	if (fw6_verbose)
	ip6fw_report(NULL, ip6, rif, oif, off, nxt);
	goto dropit;
	}

	got_match:
	#ifndef IP6FW_DIVERT_RESTART
	/* Ignore divert/tee rule if socket port is "ignport" */
	switch (f->fw_flg & IPV6_FW_F_COMMAND) {
	case IPV6_FW_F_DIVERT:
	case IPV6_FW_F_TEE:
	if (f->fw_divert_port == ignport)
	continue; /* ignore this rule */
	break;
	}

	#endif /* IP6FW_DIVERT_RESTART */
	/* Update statistics */
	f->fw_pcnt += 1;
	f->fw_bcnt += ntohs(ip6->ip6_plen);
	f->timestamp = time_second;

	/* Log to console if desired */
	if ((f->fw_flg & IPV6_FW_F_PRN) && fw6_verbose)
	ip6fw_report(f, ip6, rif, oif, off, nxt);

	/* Take appropriate action */
	switch (f->fw_flg & IPV6_FW_F_COMMAND) {
	case IPV6_FW_F_ACCEPT:
	return(0);
	case IPV6_FW_F_COUNT:
	continue;
	case IPV6_FW_F_DIVERT:
	#ifdef IP6FW_DIVERT_RESTART
	*cookie = f->fw_number;
	#else
	*cookie = htons(f->fw_divert_port);
	#endif /* IP6FW_DIVERT_RESTART */
	return(f->fw_divert_port);
	case IPV6_FW_F_TEE:
	/*
	* XXX someday tee packet here, but beware that you
	* can't use m_copym() or m_copypacket() because
	* the divert input routine modifies the mbuf
	* (and these routines only increment reference
	* counts in the case of mbuf clusters), so need
	* to write custom routine.
	*/
	continue;
	case IPV6_FW_F_SKIPTO:
	#ifdef DIAGNOSTIC
	while (chain->chain.le_next
	&& chain->chain.le_next->rule->fw_number
	< f->fw_skipto_rule)
	#else
	while (chain->chain.le_next->rule->fw_number
	< f->fw_skipto_rule)
	#endif
	chain = chain->chain.le_next;
	continue;
	}

	/* Deny/reject this packet using this rule */
	rule = f;
	break;
	}

	#ifdef DIAGNOSTIC
	/* Rule 65535 should always be there and should always match */
	if (!chain)
	panic("ip6_fw: chain");
	#endif

	/*
	* At this point, we're going to drop the packet.
	* Send a reject notice if all of the following are true:
	*
	* - The packet matched a reject rule
	* - The packet is not an ICMP packet, or is an ICMP query packet
	* - The packet is not a multicast or broadcast packet
	*/
	if ((rule->fw_flg & IPV6_FW_F_COMMAND) == IPV6_FW_F_REJECT
	&& (nxt != IPPROTO_ICMPV6 \|\| is_icmp6_query(ip6, off))
	&& !((*m)->m_flags & (M_BCAST\|M_MCAST))
	&& !IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
	switch (rule->fw_reject_code) {
	case IPV6_FW_REJECT_RST:
	{
	struct tcphdr *const tcp =
	(struct tcphdr *) ((caddr_t)ip6 + off);
	struct {
	struct ip6_hdr ip6;
	struct tcphdr th;
	} ti;
	tcp_seq ack, seq;
	int flags;

	if (offset != 0 \|\| (tcp->th_flags & TH_RST))
	break;

	ti.ip6 = *ip6;
	ti.th = *tcp;
	NTOHL(ti.th.th_seq);
	NTOHL(ti.th.th_ack);
	ti.ip6.ip6_nxt = IPPROTO_TCP;
	if (ti.th.th_flags & TH_ACK) {
	ack = 0;
	seq = ti.th.th_ack;
	flags = TH_RST;
	} else {
	ack = ti.th.th_seq;
	if (((*m)->m_flags & M_PKTHDR) != 0) {
	ack += (*m)->m_pkthdr.len - off
	- (ti.th.th_off << 2);
	} else if (ip6->ip6_plen) {
	ack += ntohs(ip6->ip6_plen) + sizeof(*ip6)
	- off - (ti.th.th_off << 2);
	} else {
	m_freem(*m);
	*m = 0;
	break;
	}
	seq = 0;
	flags = TH_RST\|TH_ACK;
	}
	bcopy(&ti, ip6, sizeof(ti));
	m_freem(*m);
	*m = NULL;
	break;
	}
	default: /* Send an ICMP unreachable using code */
	if (oif)
	(*m)->m_pkthdr.rcvif = oif;
	icmp6_error(*m, ICMP6_DST_UNREACH,
	rule->fw_reject_code, 0);
	*m = NULL;
	break;
	}
	}

	dropit:
	/*
	* Finally, drop the packet.
	*/
	if (*m) {
	m_freem(*m);
	*m = NULL;
	}
	return(0);
	}

	static int
	add_entry6(struct ip6_fw_head chainptr, struct ip6_fw frwl)
	{
	struct ip6_fw *ftmp = 0;
	struct ip6_fw_chain fwc = 0, fcp, *fcpl = 0;
	u_short nbr = 0;
	int s;

	fwc = malloc(sizeof *fwc, M_IP6FW, M_DONTWAIT);
	ftmp = malloc(sizeof *ftmp, M_IP6FW, M_DONTWAIT);
	if (!fwc \|\| !ftmp) {
	dprintf(("%s malloc said no\n", err_prefix));
	if (fwc) free(fwc, M_IP6FW);
	if (ftmp) free(ftmp, M_IP6FW);
	return (ENOSPC);
	}

	bcopy(frwl, ftmp, sizeof(struct ip6_fw));
	ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0';
	ftmp->fw_pcnt = 0L;
	ftmp->fw_bcnt = 0L;
	fwc->rule = ftmp;

	s = splnet();

	if (!chainptr->lh_first) {
	LIST_INSERT_HEAD(chainptr, fwc, chain);
	splx(s);
	return(0);
	} else if (ftmp->fw_number == (u_short)-1) {
	if (fwc) free(fwc, M_IP6FW);
	if (ftmp) free(ftmp, M_IP6FW);
	splx(s);
	dprintf(("%s bad rule number\n", err_prefix));
	return (EINVAL);
	}

	/* If entry number is 0, find highest numbered rule and add 100 */
	if (ftmp->fw_number == 0) {
	for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
	if (fcp->rule->fw_number != (u_short)-1)
	nbr = fcp->rule->fw_number;
	else
	break;
	}
	if (nbr < (u_short)-1 - 100)
	nbr += 100;
	ftmp->fw_number = nbr;
	}

	/* Got a valid number; now insert it, keeping the list ordered */
	for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
	if (fcp->rule->fw_number > ftmp->fw_number) {
	if (fcpl) {
	LIST_INSERT_AFTER(fcpl, fwc, chain);
	} else {
	LIST_INSERT_HEAD(chainptr, fwc, chain);
	}
	break;
	} else {
	fcpl = fcp;
	}
	}

	splx(s);
	return (0);
	}

	static int
	del_entry6(struct ip6_fw_head *chainptr, u_short number)
	{
	struct ip6_fw_chain *fcp;
	int s;

	s = splnet();

	fcp = chainptr->lh_first;
	if (number != (u_short)-1) {
	for (; fcp; fcp = fcp->chain.le_next) {
	if (fcp->rule->fw_number == number) {
	LIST_REMOVE(fcp, chain);
	splx(s);
	free(fcp->rule, M_IP6FW);
	free(fcp, M_IP6FW);
	return 0;
	}
	}
	}

	splx(s);
	return (EINVAL);
	}

	static int
	zero_entry6(struct mbuf *m)
	{
	struct ip6_fw *frwl;
	struct ip6_fw_chain *fcp;
	int s;

	if (m && m->m_len != 0) {
	if (m->m_len != sizeof(struct ip6_fw))
	return(EINVAL);
	frwl = mtod(m, struct ip6_fw *);
	}
	else
	frwl = NULL;

	/*
	* It's possible to insert multiple chain entries with the
	* same number, so we don't stop after finding the first
	* match if zeroing a specific entry.
	*/
	s = splnet();
	for (fcp = ip6_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next)
	if (!frwl \|\| frwl->fw_number == fcp->rule->fw_number) {
	fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
	fcp->rule->timestamp = 0;
	}
	splx(s);

	if (fw6_verbose) {
	if (frwl)
	printf("ip6fw: Entry %d cleared.\n", frwl->fw_number);
	else
	printf("ip6fw: Accounting cleared.\n");
	}

	return(0);
	}

	static struct ip6_fw *
	check_ip6fw_mbuf(struct mbuf *m)
	{
	/* Check length */
	if (m->m_len != sizeof(struct ip6_fw)) {
	dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
	sizeof(struct ip6_fw)));
	return (NULL);
	}
	return(check_ip6fw_struct(mtod(m, struct ip6_fw *)));
	}

	static struct ip6_fw *
	check_ip6fw_struct(struct ip6_fw *frwl)
	{
	/* Check for invalid flag bits */
	if ((frwl->fw_flg & ~IPV6_FW_F_MASK) != 0) {
	dprintf(("%s undefined flag bits set (flags=%x)\n",
	err_prefix, frwl->fw_flg));
	return (NULL);
	}
	/* Must apply to incoming or outgoing (or both) */
	if (!(frwl->fw_flg & (IPV6_FW_F_IN \| IPV6_FW_F_OUT))) {
	dprintf(("%s neither in nor out\n", err_prefix));
	return (NULL);
	}
	/* Empty interface name is no good */
	if (((frwl->fw_flg & IPV6_FW_F_IIFNAME)
	&& !*frwl->fw_in_if.fu_via_if.name)
	\|\| ((frwl->fw_flg & IPV6_FW_F_OIFNAME)
	&& !*frwl->fw_out_if.fu_via_if.name)) {
	dprintf(("%s empty interface name\n", err_prefix));
	return (NULL);
	}
	/* Sanity check interface matching */
	if ((frwl->fw_flg & IF6_FW_F_VIAHACK) == IF6_FW_F_VIAHACK) {
	; /* allow "via" backwards compatibility */
	} else if ((frwl->fw_flg & IPV6_FW_F_IN)
	&& (frwl->fw_flg & IPV6_FW_F_OIFACE)) {
	dprintf(("%s outgoing interface check on incoming\n",
	err_prefix));
	return (NULL);
	}
	/* Sanity check port ranges */
	if ((frwl->fw_flg & IPV6_FW_F_SRNG) && IPV6_FW_GETNSRCP(frwl) < 2) {
	dprintf(("%s src range set but n_src_p=%d\n",
	err_prefix, IPV6_FW_GETNSRCP(frwl)));
	return (NULL);
	}
	if ((frwl->fw_flg & IPV6_FW_F_DRNG) && IPV6_FW_GETNDSTP(frwl) < 2) {
	dprintf(("%s dst range set but n_dst_p=%d\n",
	err_prefix, IPV6_FW_GETNDSTP(frwl)));
	return (NULL);
	}
	if (IPV6_FW_GETNSRCP(frwl) + IPV6_FW_GETNDSTP(frwl) > IPV6_FW_MAX_PORTS) {
	dprintf(("%s too many ports (%d+%d)\n",
	err_prefix, IPV6_FW_GETNSRCP(frwl), IPV6_FW_GETNDSTP(frwl)));
	return (NULL);
	}
	/*
	* Protocols other than TCP/UDP don't use port range
	*/
	if ((frwl->fw_prot != IPPROTO_TCP) &&
	(frwl->fw_prot != IPPROTO_UDP) &&
	(IPV6_FW_GETNSRCP(frwl) \|\| IPV6_FW_GETNDSTP(frwl))) {
	dprintf(("%s port(s) specified for non TCP/UDP rule\n",
	err_prefix));
	return(NULL);
	}

	/*
	* Rather than modify the entry to make such entries work,
	* we reject this rule and require user level utilities
	* to enforce whatever policy they deem appropriate.
	*/
	if ((frwl->fw_src.s6_addr32[0] & (~frwl->fw_smsk.s6_addr32[0])) \|\|
	(frwl->fw_src.s6_addr32[1] & (~frwl->fw_smsk.s6_addr32[1])) \|\|
	(frwl->fw_src.s6_addr32[2] & (~frwl->fw_smsk.s6_addr32[2])) \|\|
	(frwl->fw_src.s6_addr32[3] & (~frwl->fw_smsk.s6_addr32[3])) \|\|
	(frwl->fw_dst.s6_addr32[0] & (~frwl->fw_dmsk.s6_addr32[0])) \|\|
	(frwl->fw_dst.s6_addr32[1] & (~frwl->fw_dmsk.s6_addr32[1])) \|\|
	(frwl->fw_dst.s6_addr32[2] & (~frwl->fw_dmsk.s6_addr32[2])) \|\|
	(frwl->fw_dst.s6_addr32[3] & (~frwl->fw_dmsk.s6_addr32[3]))) {
	dprintf(("%s rule never matches\n", err_prefix));
	return(NULL);
	}

	if ((frwl->fw_flg & IPV6_FW_F_FRAG) &&
	(frwl->fw_prot == IPPROTO_UDP \|\| frwl->fw_prot == IPPROTO_TCP)) {
	if (frwl->fw_nports) {
	dprintf(("%s cannot mix 'frag' and ports\n", err_prefix));
	return(NULL);
	}
	if (frwl->fw_prot == IPPROTO_TCP &&
	frwl->fw_tcpf != frwl->fw_tcpnf) {
	dprintf(("%s cannot mix 'frag' with TCP flags\n", err_prefix));
	return(NULL);
	}
	}

	/* Check command specific stuff */
	switch (frwl->fw_flg & IPV6_FW_F_COMMAND)
	{
	case IPV6_FW_F_REJECT:
	if (frwl->fw_reject_code >= 0x100
	&& !(frwl->fw_prot == IPPROTO_TCP
	&& frwl->fw_reject_code == IPV6_FW_REJECT_RST)) {
	dprintf(("%s unknown reject code\n", err_prefix));
	return(NULL);
	}
	break;
	case IPV6_FW_F_DIVERT: /* Diverting to port zero is invalid */
	case IPV6_FW_F_TEE:
	if (frwl->fw_divert_port == 0) {
	dprintf(("%s can't divert to port 0\n", err_prefix));
	return (NULL);
	}
	break;
	case IPV6_FW_F_DENY:
	case IPV6_FW_F_ACCEPT:
	case IPV6_FW_F_COUNT:
	case IPV6_FW_F_SKIPTO:
	break;
	default:
	dprintf(("%s invalid command\n", err_prefix));
	return(NULL);
	}

	return frwl;
	}

	static int
	ip6_fw_ctl(int stage, struct mbuf **mm)
	{
	int error;
	struct mbuf *m;

	if (stage == IPV6_FW_GET) {
	struct ip6_fw_chain *fcp = ip6_fw_chain.lh_first;
	mm = m = m_get(M_WAIT, MT_DATA); / XXX */
	if (!m)
	return(ENOBUFS);
	if (sizeof *(fcp->rule) > MLEN) {
	MCLGET(m, M_WAIT);
	if ((m->m_flags & M_EXT) == 0) {
	m_free(m);
	return(ENOBUFS);
	}
	}
	for (; fcp; fcp = fcp->chain.le_next) {
	memcpy(m->m_data, fcp->rule, sizeof *(fcp->rule));
	m->m_len = sizeof *(fcp->rule);
	m->m_next = m_get(M_WAIT, MT_DATA); /* XXX */
	if (!m->m_next) {
	m_freem(*mm);
	return(ENOBUFS);
	}
	m = m->m_next;
	if (sizeof *(fcp->rule) > MLEN) {
	MCLGET(m, M_WAIT);
	if ((m->m_flags & M_EXT) == 0) {
	m_freem(*mm);
	return(ENOBUFS);
	}
	}
	m->m_len = 0;
	}
	return (0);
	}
	m = *mm;
	/* only allow get calls if secure mode > 2 */
	if (securelevel > 2) {
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return(EPERM);
	}
	if (stage == IPV6_FW_FLUSH) {
	while (ip6_fw_chain.lh_first != NULL &&
	ip6_fw_chain.lh_first->rule->fw_number != (u_short)-1) {
	struct ip6_fw_chain *fcp = ip6_fw_chain.lh_first;
	int s = splnet();
	LIST_REMOVE(ip6_fw_chain.lh_first, chain);
	splx(s);
	free(fcp->rule, M_IP6FW);
	free(fcp, M_IP6FW);
	}
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return (0);
	}
	if (stage == IPV6_FW_ZERO) {
	error = zero_entry6(m);
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return (error);
	}
	if (m == NULL) {
	printf("%s NULL mbuf ptr\n", err_prefix);
	return (EINVAL);
	}

	if (stage == IPV6_FW_ADD) {
	struct ip6_fw *frwl = check_ip6fw_mbuf(m);

	if (!frwl)
	error = EINVAL;
	else
	error = add_entry6(&ip6_fw_chain, frwl);
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return error;
	}
	if (stage == IPV6_FW_DEL) {
	if (m->m_len != sizeof(struct ip6_fw)) {
	dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
	sizeof(struct ip6_fw)));
	error = EINVAL;
	} else if (mtod(m, struct ip6_fw *)->fw_number == (u_short)-1) {
	dprintf(("%s can't delete rule 65535\n", err_prefix));
	error = EINVAL;
	} else
	error = del_entry6(&ip6_fw_chain,
	mtod(m, struct ip6_fw *)->fw_number);
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return error;
	}

	dprintf(("%s unknown request %d\n", err_prefix, stage));
	if (m) {
	(void)m_freem(m);
	*mm = 0;
	}
	return (EINVAL);
	}

	void
	ip6_fw_init(void)
	{
	struct ip6_fw default_rule;

	ip6_fw_chk_ptr = ip6_fw_chk;
	ip6_fw_ctl_ptr = ip6_fw_ctl;
	LIST_INIT(&ip6_fw_chain);

	bzero(&default_rule, sizeof default_rule);
	default_rule.fw_prot = IPPROTO_IPV6;
	default_rule.fw_number = (u_short)-1;
	#ifdef IPV6FIREWALL_DEFAULT_TO_ACCEPT
	default_rule.fw_flg \|= IPV6_FW_F_ACCEPT;
	#else
	default_rule.fw_flg \|= IPV6_FW_F_DENY;
	#endif
	default_rule.fw_flg \|= IPV6_FW_F_IN \| IPV6_FW_F_OUT;
	if (check_ip6fw_struct(&default_rule) == NULL \|\|
	add_entry6(&ip6_fw_chain, &default_rule))
	panic(__FUNCTION__);

	printf("IPv6 packet filtering initialized, ");
	#ifdef IPV6FIREWALL_DEFAULT_TO_ACCEPT
	printf("default to accept, ");
	#endif
	#ifndef IPV6FIREWALL_VERBOSE
	printf("logging disabled\n");
	#else
	if (fw6_verbose_limit == 0)
	printf("unlimited logging\n");
	else
	printf("logging limited to %d packets/entry\n",
	fw6_verbose_limit);
	#endif
	}

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