9108601915
the ipfw KLD. For IPFIREWALL_FORWARD this does not have any side effects. If the module has it but not the kernel it just doesn't do anything. For IPDIVERT the KLD will be unloadable if the kernel doesn't have IPDIVERT compiled in too. However this is the least disturbing behaviour. The user can just recompile either module or the kernel to match the other one. The access to the machine is not denied if ipfw refuses to load.
407 lines
9.2 KiB
C
407 lines
9.2 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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* $FreeBSD$
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*/
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#include "opt_ipfw.h"
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#include "opt_ipdn.h"
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#include "opt_ipdivert.h"
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#include "opt_inet.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/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <sys/ucred.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/pfil.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.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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#include <netinet/ip_divert.h>
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#include <netinet/ip_dummynet.h>
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#include <machine/in_cksum.h>
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static int ipfw_pfil_hooked = 0;
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/* Dummynet hooks. */
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ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL;
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#define DIV_DIR_IN 1
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#define DIV_DIR_OUT 0
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static int ipfw_divert(struct mbuf **, int, int);
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int
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ipfw_check_in(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir)
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{
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struct ip_fw_args args;
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struct m_tag *dn_tag;
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int ipfw = 0;
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int divert;
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#ifdef IPFIREWALL_FORWARD
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struct m_tag *fwd_tag;
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#endif
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KASSERT(dir == PFIL_IN, ("ipfw_check_in wrong direction!"));
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if (!fw_enable)
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goto pass;
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bzero(&args, sizeof(args));
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dn_tag = m_tag_find(*m0, PACKET_TAG_DUMMYNET, NULL);
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if (dn_tag != NULL){
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struct dn_pkt_tag *dt;
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dt = (struct dn_pkt_tag *)(dn_tag+1);
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args.rule = dt->rule;
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m_tag_delete(*m0, dn_tag);
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}
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args.m = *m0;
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ipfw = ipfw_chk(&args);
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*m0 = args.m;
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if ((ipfw & IP_FW_PORT_DENY_FLAG) || *m0 == NULL)
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goto drop;
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if (ipfw == 0 && args.next_hop == NULL)
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goto pass;
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if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
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ip_dn_io_ptr(*m0, ipfw & 0xffff, DN_TO_IP_IN, &args);
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*m0 = NULL;
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return 0; /* packet consumed */
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}
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if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
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if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
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divert = ipfw_divert(m0, DIV_DIR_IN, 1);
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else
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divert = ipfw_divert(m0, DIV_DIR_IN, 0);
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/* tee should continue again with the firewall. */
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if (divert) {
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*m0 = NULL;
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return 0; /* packet consumed */
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} else
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goto pass; /* continue with packet */
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}
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#ifdef IPFIREWALL_FORWARD
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if (ipfw == 0 && args.next_hop != NULL) {
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fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD,
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sizeof(struct sockaddr_in), M_NOWAIT);
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if (fwd_tag == NULL)
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goto drop;
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bcopy(args.next_hop, (fwd_tag+1), sizeof(struct sockaddr_in));
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m_tag_prepend(*m0, fwd_tag);
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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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goto pass;
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}
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#endif
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drop:
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if (*m0)
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m_freem(*m0);
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*m0 = NULL;
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return (EACCES);
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pass:
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return 0; /* not filtered */
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}
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int
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ipfw_check_out(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir)
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{
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struct ip_fw_args args;
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struct m_tag *dn_tag;
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int ipfw = 0;
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int divert;
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#ifdef IPFIREWALL_FORWARD
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struct m_tag *fwd_tag;
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#endif
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KASSERT(dir == PFIL_OUT, ("ipfw_check_out wrong direction!"));
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if (!fw_enable)
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goto pass;
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bzero(&args, sizeof(args));
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dn_tag = m_tag_find(*m0, PACKET_TAG_DUMMYNET, NULL);
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if (dn_tag != NULL) {
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struct dn_pkt_tag *dt;
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dt = (struct dn_pkt_tag *)(dn_tag+1);
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args.rule = dt->rule;
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m_tag_delete(*m0, dn_tag);
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}
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args.m = *m0;
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args.oif = ifp;
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ipfw = ipfw_chk(&args);
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*m0 = args.m;
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if ((ipfw & IP_FW_PORT_DENY_FLAG) || *m0 == NULL)
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goto drop;
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if (ipfw == 0 && args.next_hop == NULL)
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goto pass;
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if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
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ip_dn_io_ptr(*m0, ipfw & 0xffff, DN_TO_IP_OUT, &args);
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*m0 = NULL;
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return 0; /* packet consumed */
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}
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if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
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if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
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divert = ipfw_divert(m0, DIV_DIR_OUT, 1);
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else
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divert = ipfw_divert(m0, DIV_DIR_OUT, 0);
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if (divert) {
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*m0 = NULL;
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return 0; /* packet consumed */
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} else
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goto pass; /* continue with packet */
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}
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#ifdef IPFIREWALL_FORWARD
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if (ipfw == 0 && args.next_hop != NULL) {
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/* Overwrite existing tag. */
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fwd_tag = m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL);
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if (fwd_tag == NULL)
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fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD,
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sizeof(struct sockaddr_in), M_NOWAIT);
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if (fwd_tag == NULL)
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goto drop;
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bcopy(args.next_hop, (fwd_tag+1), sizeof(struct sockaddr_in));
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m_tag_prepend(*m0, fwd_tag);
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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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goto pass;
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}
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#endif
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drop:
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if (*m0)
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m_freem(*m0);
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*m0 = NULL;
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return (EACCES);
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pass:
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return 0; /* not filtered */
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}
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static int
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ipfw_divert(struct mbuf **m, int incoming, int tee)
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{
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/*
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* ipfw_chk() has already tagged the packet with the divert
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* tag. For tee we need to remove the 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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#ifdef IPDIVERT
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struct mbuf *clone, *reass;
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struct m_tag *mtag;
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struct ip *ip;
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int hlen;
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reass = NULL;
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/* Cloning needed for tee? */
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if (tee)
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clone = m_dup(*m, M_DONTWAIT);
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else
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clone = *m;
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/* In case m_dup was unable to allocate mbufs. */
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if (clone == NULL)
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goto teeout;
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/*
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* Divert listeners can only handle non-fragmented packets.
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* However when tee is set we will *not* de-fragment the packets;
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* Doing do would put the reassembly into double-jeopardy. On top
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* of that someone doing a tee will probably want to get the packet
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* in its original form.
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*/
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ip = mtod(clone, struct ip *);
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if (!tee && ip->ip_off & (IP_MF | IP_OFFMASK)) {
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/* Reassemble packet. */
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reass = ip_reass(clone);
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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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if (reass != NULL) {
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ip = mtod(reass, struct ip *);
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hlen = ip->ip_hl << 2;
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ip->ip_len = htons(ip->ip_len);
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ip->ip_off = htons(ip->ip_off);
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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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} else
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clone = NULL;
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} else {
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/* Convert header to network byte order. */
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ip->ip_len = htons(ip->ip_len);
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ip->ip_off = htons(ip->ip_off);
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}
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/* Do the dirty job... */
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if (clone)
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divert_packet(clone, incoming);
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teeout:
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if (tee) {
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mtag = m_tag_find(*m, PACKET_TAG_DIVERT, NULL);
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if (mtag != NULL)
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m_tag_delete(*m, mtag);
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return 0; /* continue with original packet. */
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}
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/* Packet diverted and consumed */
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return 1;
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#else
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m_freem(*m);
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return 1;
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#endif /* ipdivert */
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}
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static int
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ipfw_hook(void)
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{
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struct pfil_head *pfh_inet;
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if (ipfw_pfil_hooked)
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return EEXIST;
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pfh_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET);
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if (pfh_inet == NULL)
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return ENOENT;
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pfil_add_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet);
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pfil_add_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet);
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return 0;
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}
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static int
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ipfw_unhook(void)
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{
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struct pfil_head *pfh_inet;
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if (!ipfw_pfil_hooked)
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return ENOENT;
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pfh_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET);
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if (pfh_inet == NULL)
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return ENOENT;
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pfil_remove_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet);
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pfil_remove_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet);
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return 0;
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}
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static int
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ipfw_modevent(module_t mod, int type, void *unused)
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{
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int err = 0;
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switch (type) {
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case MOD_LOAD:
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if (ipfw_pfil_hooked) {
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printf("IP firewall already loaded\n");
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err = EEXIST;
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} else {
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if ((err = ipfw_init()) != 0) {
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printf("ipfw_init() error\n");
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break;
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}
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if ((err = ipfw_hook()) != 0) {
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printf("ipfw_hook() error\n");
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break;
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}
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ipfw_pfil_hooked = 1;
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}
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break;
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case MOD_UNLOAD:
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if (ipfw_pfil_hooked) {
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if ((err = ipfw_unhook()) > 0);
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break;
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ipfw_destroy();
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ipfw_pfil_hooked = 0;
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} else {
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printf("IP firewall already unloaded\n");
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}
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break;
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default:
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return EOPNOTSUPP;
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break;
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}
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return err;
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}
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static moduledata_t ipfwmod = {
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"ipfw",
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ipfw_modevent,
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0
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};
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DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
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MODULE_VERSION(ipfw, 2);
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