576 lines
14 KiB
C
576 lines
14 KiB
C
/*-
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* Copyright (c) 2004 Andre Oppermann, Internet Business Solutions AG
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ipfw.h"
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#ifndef INET
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#error IPFIREWALL requires INET.
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#endif /* INET */
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/module.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/rwlock.h>
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#include <sys/socket.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/ethernet.h>
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#include <net/pfil.h>
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#include <net/vnet.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_fw.h>
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#ifdef INET6
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.h>
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#endif
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#include <netgraph/ng_ipfw.h>
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#include <netpfil/ipfw/ip_fw_private.h>
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#include <machine/in_cksum.h>
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static VNET_DEFINE(int, fw_enable) = 1;
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#define V_fw_enable VNET(fw_enable)
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#ifdef INET6
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static VNET_DEFINE(int, fw6_enable) = 1;
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#define V_fw6_enable VNET(fw6_enable)
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#endif
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static VNET_DEFINE(int, fwlink_enable) = 0;
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#define V_fwlink_enable VNET(fwlink_enable)
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int ipfw_chg_hook(SYSCTL_HANDLER_ARGS);
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/* Forward declarations. */
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static int ipfw_divert(struct mbuf **, int, struct ipfw_rule_ref *, int);
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int ipfw_check_packet(void *, struct mbuf **, struct ifnet *, int,
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struct inpcb *);
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int ipfw_check_frame(void *, struct mbuf **, struct ifnet *, int,
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struct inpcb *);
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#ifdef SYSCTL_NODE
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SYSBEGIN(f1)
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SYSCTL_DECL(_net_inet_ip_fw);
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SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, enable,
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CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
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&VNET_NAME(fw_enable), 0, ipfw_chg_hook, "I", "Enable ipfw");
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#ifdef INET6
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SYSCTL_DECL(_net_inet6_ip6_fw);
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SYSCTL_PROC(_net_inet6_ip6_fw, OID_AUTO, enable,
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CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
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&VNET_NAME(fw6_enable), 0, ipfw_chg_hook, "I", "Enable ipfw+6");
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#endif /* INET6 */
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SYSCTL_DECL(_net_link_ether);
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SYSCTL_PROC(_net_link_ether, OID_AUTO, ipfw,
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CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
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&VNET_NAME(fwlink_enable), 0, ipfw_chg_hook, "I",
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"Pass ether pkts through firewall");
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SYSEND
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#endif /* SYSCTL_NODE */
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/*
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* The pfilter hook to pass packets to ipfw_chk and then to
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* dummynet, divert, netgraph or other modules.
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* The packet may be consumed.
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*/
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int
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ipfw_check_packet(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
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struct inpcb *inp)
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{
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struct ip_fw_args args;
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struct m_tag *tag;
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int ipfw;
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int ret;
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/* convert dir to IPFW values */
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dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT;
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bzero(&args, sizeof(args));
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again:
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/*
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* extract and remove the tag if present. If we are left
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* with onepass, optimize the outgoing path.
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*/
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tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL);
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if (tag != NULL) {
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args.rule = *((struct ipfw_rule_ref *)(tag+1));
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m_tag_delete(*m0, tag);
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if (args.rule.info & IPFW_ONEPASS)
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return (0);
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}
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args.m = *m0;
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args.oif = dir == DIR_OUT ? ifp : NULL;
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args.inp = inp;
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ipfw = ipfw_chk(&args);
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*m0 = args.m;
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KASSERT(*m0 != NULL || ipfw == IP_FW_DENY, ("%s: m0 is NULL",
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__func__));
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/* breaking out of the switch means drop */
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ret = 0; /* default return value for pass */
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switch (ipfw) {
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case IP_FW_PASS:
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/* next_hop may be set by ipfw_chk */
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if (args.next_hop == NULL && args.next_hop6 == NULL)
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break; /* pass */
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#if (!defined(INET6) && !defined(INET))
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ret = EACCES;
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#else
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{
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struct m_tag *fwd_tag;
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size_t len;
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KASSERT(args.next_hop == NULL || args.next_hop6 == NULL,
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("%s: both next_hop=%p and next_hop6=%p not NULL", __func__,
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args.next_hop, args.next_hop6));
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#ifdef INET6
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if (args.next_hop6 != NULL)
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len = sizeof(struct sockaddr_in6);
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#endif
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#ifdef INET
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if (args.next_hop != NULL)
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len = sizeof(struct sockaddr_in);
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#endif
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/* Incoming packets should not be tagged so we do not
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* m_tag_find. Outgoing packets may be tagged, so we
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* reuse the tag if present.
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*/
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fwd_tag = (dir == DIR_IN) ? NULL :
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m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL);
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if (fwd_tag != NULL) {
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m_tag_unlink(*m0, fwd_tag);
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} else {
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fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD, len,
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M_NOWAIT);
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if (fwd_tag == NULL) {
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ret = EACCES;
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break; /* i.e. drop */
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}
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}
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#ifdef INET6
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if (args.next_hop6 != NULL) {
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bcopy(args.next_hop6, (fwd_tag+1), len);
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if (in6_localip(&args.next_hop6->sin6_addr))
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(*m0)->m_flags |= M_FASTFWD_OURS;
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(*m0)->m_flags |= M_IP6_NEXTHOP;
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}
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#endif
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#ifdef INET
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if (args.next_hop != NULL) {
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bcopy(args.next_hop, (fwd_tag+1), len);
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if (in_localip(args.next_hop->sin_addr))
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(*m0)->m_flags |= M_FASTFWD_OURS;
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(*m0)->m_flags |= M_IP_NEXTHOP;
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}
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#endif
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m_tag_prepend(*m0, fwd_tag);
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}
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#endif /* INET || INET6 */
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break;
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case IP_FW_DENY:
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ret = EACCES;
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break; /* i.e. drop */
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case IP_FW_DUMMYNET:
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ret = EACCES;
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if (ip_dn_io_ptr == NULL)
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break; /* i.e. drop */
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if (mtod(*m0, struct ip *)->ip_v == 4)
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ret = ip_dn_io_ptr(m0, dir, &args);
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else if (mtod(*m0, struct ip *)->ip_v == 6)
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ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args);
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else
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break; /* drop it */
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/*
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* XXX should read the return value.
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* dummynet normally eats the packet and sets *m0=NULL
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* unless the packet can be sent immediately. In this
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* case args is updated and we should re-run the
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* check without clearing args.
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*/
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if (*m0 != NULL)
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goto again;
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break;
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case IP_FW_TEE:
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case IP_FW_DIVERT:
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if (ip_divert_ptr == NULL) {
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ret = EACCES;
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break; /* i.e. drop */
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}
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ret = ipfw_divert(m0, dir, &args.rule,
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(ipfw == IP_FW_TEE) ? 1 : 0);
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/* continue processing for the original packet (tee). */
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if (*m0)
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goto again;
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break;
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case IP_FW_NGTEE:
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case IP_FW_NETGRAPH:
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if (ng_ipfw_input_p == NULL) {
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ret = EACCES;
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break; /* i.e. drop */
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}
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ret = ng_ipfw_input_p(m0, dir, &args,
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(ipfw == IP_FW_NGTEE) ? 1 : 0);
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if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */
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goto again; /* continue with packet */
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break;
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case IP_FW_NAT:
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/* honor one-pass in case of successful nat */
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if (V_fw_one_pass)
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break; /* ret is already 0 */
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goto again;
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case IP_FW_REASS:
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goto again; /* continue with packet */
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default:
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KASSERT(0, ("%s: unknown retval", __func__));
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}
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if (ret != 0) {
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if (*m0)
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FREE_PKT(*m0);
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*m0 = NULL;
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}
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return ret;
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}
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/*
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* ipfw processing for ethernet packets (in and out).
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* Inteface is NULL from ether_demux, and ifp from
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* ether_output_frame.
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*/
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int
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ipfw_check_frame(void *arg, struct mbuf **m0, struct ifnet *dst, int dir,
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struct inpcb *inp)
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{
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struct ether_header *eh;
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struct ether_header save_eh;
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struct mbuf *m;
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int i, ret;
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struct ip_fw_args args;
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struct m_tag *mtag;
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/* fetch start point from rule, if any */
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mtag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL);
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if (mtag == NULL) {
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args.rule.slot = 0;
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} else {
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/* dummynet packet, already partially processed */
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struct ipfw_rule_ref *r;
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/* XXX can we free it after use ? */
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mtag->m_tag_id = PACKET_TAG_NONE;
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r = (struct ipfw_rule_ref *)(mtag + 1);
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if (r->info & IPFW_ONEPASS)
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return (0);
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args.rule = *r;
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}
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/* I need some amt of data to be contiguous */
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m = *m0;
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i = min(m->m_pkthdr.len, max_protohdr);
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if (m->m_len < i) {
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m = m_pullup(m, i);
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if (m == NULL) {
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*m0 = m;
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return (0);
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}
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}
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eh = mtod(m, struct ether_header *);
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save_eh = *eh; /* save copy for restore below */
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m_adj(m, ETHER_HDR_LEN); /* strip ethernet header */
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args.m = m; /* the packet we are looking at */
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args.oif = dir == PFIL_OUT ? dst: NULL; /* destination, if any */
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args.next_hop = NULL; /* we do not support forward yet */
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args.next_hop6 = NULL; /* we do not support forward yet */
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args.eh = &save_eh; /* MAC header for bridged/MAC packets */
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args.inp = NULL; /* used by ipfw uid/gid/jail rules */
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i = ipfw_chk(&args);
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m = args.m;
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if (m != NULL) {
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/*
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* Restore Ethernet header, as needed, in case the
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* mbuf chain was replaced by ipfw.
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*/
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M_PREPEND(m, ETHER_HDR_LEN, M_NOWAIT);
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if (m == NULL) {
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*m0 = NULL;
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return (0);
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}
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if (eh != mtod(m, struct ether_header *))
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bcopy(&save_eh, mtod(m, struct ether_header *),
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ETHER_HDR_LEN);
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}
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*m0 = m;
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ret = 0;
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/* Check result of ipfw_chk() */
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switch (i) {
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case IP_FW_PASS:
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break;
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case IP_FW_DENY:
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ret = EACCES;
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break; /* i.e. drop */
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case IP_FW_DUMMYNET:
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ret = EACCES;
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int dir;
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if (ip_dn_io_ptr == NULL)
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break; /* i.e. drop */
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*m0 = NULL;
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dir = PROTO_LAYER2 | (dst ? DIR_OUT : DIR_IN);
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ip_dn_io_ptr(&m, dir, &args);
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return 0;
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default:
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KASSERT(0, ("%s: unknown retval", __func__));
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}
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if (ret != 0) {
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if (*m0)
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FREE_PKT(*m0);
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*m0 = NULL;
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}
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return ret;
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}
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/* do the divert, return 1 on error 0 on success */
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static int
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ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule,
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int tee)
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{
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/*
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* ipfw_chk() has already tagged the packet with the divert tag.
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* If tee is set, copy packet and return original.
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* If not tee, consume packet and send it to divert socket.
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*/
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struct mbuf *clone;
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struct ip *ip = mtod(*m0, struct ip *);
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struct m_tag *tag;
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/* Cloning needed for tee? */
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if (tee == 0) {
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clone = *m0; /* use the original mbuf */
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*m0 = NULL;
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} else {
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clone = m_dup(*m0, M_NOWAIT);
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/* If we cannot duplicate the mbuf, we sacrifice the divert
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* chain and continue with the tee-ed packet.
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*/
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if (clone == NULL)
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return 1;
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}
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/*
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* Divert listeners can normally handle non-fragmented packets,
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* but we can only reass in the non-tee case.
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* This means that listeners on a tee rule may get fragments,
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* and have to live with that.
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* Note that we now have the 'reass' ipfw option so if we care
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* we can do it before a 'tee'.
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*/
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if (!tee) switch (ip->ip_v) {
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case IPVERSION:
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if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) {
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int hlen;
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struct mbuf *reass;
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reass = ip_reass(clone); /* Reassemble packet. */
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if (reass == NULL)
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return 0; /* not an error */
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/* if reass = NULL then it was consumed by ip_reass */
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/*
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* IP header checksum fixup after reassembly and leave header
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* in network byte order.
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*/
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ip = mtod(reass, struct ip *);
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hlen = ip->ip_hl << 2;
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ip->ip_sum = 0;
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if (hlen == sizeof(struct ip))
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ip->ip_sum = in_cksum_hdr(ip);
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else
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ip->ip_sum = in_cksum(reass, hlen);
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clone = reass;
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}
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break;
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#ifdef INET6
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case IPV6_VERSION >> 4:
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{
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struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *);
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if (ip6->ip6_nxt == IPPROTO_FRAGMENT) {
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int nxt, off;
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off = sizeof(struct ip6_hdr);
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nxt = frag6_input(&clone, &off, 0);
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if (nxt == IPPROTO_DONE)
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return (0);
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}
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break;
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}
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#endif
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}
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/* attach a tag to the packet with the reinject info */
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tag = m_tag_alloc(MTAG_IPFW_RULE, 0,
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sizeof(struct ipfw_rule_ref), M_NOWAIT);
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if (tag == NULL) {
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FREE_PKT(clone);
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return 1;
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}
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*((struct ipfw_rule_ref *)(tag+1)) = *rule;
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m_tag_prepend(clone, tag);
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/* Do the dirty job... */
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ip_divert_ptr(clone, incoming);
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return 0;
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}
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/*
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* attach or detach hooks for a given protocol family
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*/
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static int
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ipfw_hook(int onoff, int pf)
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{
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struct pfil_head *pfh;
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void *hook_func;
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pfh = pfil_head_get(PFIL_TYPE_AF, pf);
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if (pfh == NULL)
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return ENOENT;
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hook_func = (pf == AF_LINK) ? ipfw_check_frame : ipfw_check_packet;
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(void) (onoff ? pfil_add_hook : pfil_remove_hook)
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(hook_func, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh);
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return 0;
|
|
}
|
|
|
|
int
|
|
ipfw_attach_hooks(int arg)
|
|
{
|
|
int error = 0;
|
|
|
|
if (arg == 0) /* detach */
|
|
ipfw_hook(0, AF_INET);
|
|
else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) {
|
|
error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */
|
|
printf("ipfw_hook() error\n");
|
|
}
|
|
#ifdef INET6
|
|
if (arg == 0) /* detach */
|
|
ipfw_hook(0, AF_INET6);
|
|
else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) {
|
|
error = ENOENT;
|
|
printf("ipfw6_hook() error\n");
|
|
}
|
|
#endif
|
|
if (arg == 0) /* detach */
|
|
ipfw_hook(0, AF_LINK);
|
|
else if (V_fwlink_enable && ipfw_hook(1, AF_LINK) != 0) {
|
|
error = ENOENT;
|
|
printf("ipfw_link_hook() error\n");
|
|
}
|
|
return error;
|
|
}
|
|
|
|
int
|
|
ipfw_chg_hook(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
int newval;
|
|
int error;
|
|
int af;
|
|
|
|
if (arg1 == &V_fw_enable)
|
|
af = AF_INET;
|
|
#ifdef INET6
|
|
else if (arg1 == &V_fw6_enable)
|
|
af = AF_INET6;
|
|
#endif
|
|
else if (arg1 == &V_fwlink_enable)
|
|
af = AF_LINK;
|
|
else
|
|
return (EINVAL);
|
|
|
|
newval = *(int *)arg1;
|
|
/* Handle sysctl change */
|
|
error = sysctl_handle_int(oidp, &newval, 0, req);
|
|
|
|
if (error)
|
|
return (error);
|
|
|
|
/* Formalize new value */
|
|
newval = (newval) ? 1 : 0;
|
|
|
|
if (*(int *)arg1 == newval)
|
|
return (0);
|
|
|
|
error = ipfw_hook(newval, af);
|
|
if (error)
|
|
return (error);
|
|
*(int *)arg1 = newval;
|
|
|
|
return (0);
|
|
}
|
|
/* end of file */
|