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408 lines
11 KiB
C
408 lines
11 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1993
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* The Regents of the University of California. 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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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_ipsec.h"
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#include "opt_sctp.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/errno.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.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 <net/if.h>
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#include <net/route.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/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_options.h>
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#include <netinet/ip_ipsec.h>
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#ifdef SCTP
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#include <netinet/sctp_crc32.h>
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#endif
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#include <machine/in_cksum.h>
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#ifdef IPSEC
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#include <netipsec/ipsec.h>
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#include <netipsec/xform.h>
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#include <netipsec/key.h>
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#endif /*IPSEC*/
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extern struct protosw inetsw[];
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#ifdef IPSEC
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#ifdef IPSEC_FILTERTUNNEL
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static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
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#else
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static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
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#endif
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#define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
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SYSCTL_DECL(_net_inet_ipsec);
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SYSCTL_VNET_INT(_net_inet_ipsec, OID_AUTO, filtertunnel,
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CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0,
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"If set filter packets from an IPsec tunnel.");
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#endif /* IPSEC */
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/*
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* Check if we have to jump over firewall processing for this packet.
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* Called from ip_input().
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* 1 = jump over firewall, 0 = packet goes through firewall.
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*/
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int
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ip_ipsec_filtertunnel(struct mbuf *m)
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{
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#if defined(IPSEC)
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/*
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* Bypass packet filtering for packets previously handled by IPsec.
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*/
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if (!V_ip4_ipsec_filtertunnel &&
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m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
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return 1;
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#endif
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return 0;
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}
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/*
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* Check if this packet has an active SA and needs to be dropped instead
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* of forwarded.
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* Called from ip_input().
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* 1 = drop packet, 0 = forward packet.
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*/
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int
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ip_ipsec_fwd(struct mbuf *m)
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{
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#ifdef IPSEC
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struct m_tag *mtag;
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struct tdb_ident *tdbi;
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struct secpolicy *sp;
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int s, error;
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mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
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s = splnet();
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if (mtag != NULL) {
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tdbi = (struct tdb_ident *)(mtag + 1);
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sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
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} else {
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sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
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IP_FORWARDING, &error);
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}
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if (sp == NULL) { /* NB: can happen if error */
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splx(s);
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/*XXX error stat???*/
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DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/
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return 1;
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}
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/*
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* Check security policy against packet attributes.
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*/
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error = ipsec_in_reject(sp, m);
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KEY_FREESP(&sp);
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splx(s);
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if (error) {
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IPSTAT_INC(ips_cantforward);
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return 1;
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}
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#endif /* IPSEC */
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return 0;
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}
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/*
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* Check if protocol type doesn't have a further header and do IPSEC
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* decryption or reject right now. Protocols with further headers get
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* their IPSEC treatment within the protocol specific processing.
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* Called from ip_input().
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* 1 = drop packet, 0 = continue processing packet.
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*/
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int
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ip_ipsec_input(struct mbuf *m)
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{
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#ifdef IPSEC
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struct ip *ip = mtod(m, struct ip *);
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struct m_tag *mtag;
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struct tdb_ident *tdbi;
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struct secpolicy *sp;
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int s, error;
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/*
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* enforce IPsec policy checking if we are seeing last header.
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* note that we do not visit this with protocols with pcb layer
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* code - like udp/tcp/raw ip.
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*/
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if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
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/*
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* Check if the packet has already had IPsec processing
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* done. If so, then just pass it along. This tag gets
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* set during AH, ESP, etc. input handling, before the
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* packet is returned to the ip input queue for delivery.
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*/
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mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
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s = splnet();
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if (mtag != NULL) {
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tdbi = (struct tdb_ident *)(mtag + 1);
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sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
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} else {
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sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
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IP_FORWARDING, &error);
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}
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if (sp != NULL) {
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/*
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* Check security policy against packet attributes.
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*/
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error = ipsec_in_reject(sp, m);
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KEY_FREESP(&sp);
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} else {
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/* XXX error stat??? */
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error = EINVAL;
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DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
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return 1;
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}
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splx(s);
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if (error)
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return 1;
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}
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#endif /* IPSEC */
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return 0;
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}
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/*
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* Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
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* Called from ip_forward().
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* Returns MTU suggestion for ICMP needfrag reply.
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*/
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int
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ip_ipsec_mtu(struct mbuf *m, int mtu)
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{
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/*
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* If the packet is routed over IPsec tunnel, tell the
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* originator the tunnel MTU.
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* tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
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* XXX quickhack!!!
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*/
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struct secpolicy *sp = NULL;
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int ipsecerror;
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int ipsechdr;
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struct route *ro;
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sp = ipsec_getpolicybyaddr(m,
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IPSEC_DIR_OUTBOUND,
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IP_FORWARDING,
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&ipsecerror);
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if (sp != NULL) {
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/* count IPsec header size */
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ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
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/*
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* find the correct route for outer IPv4
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* header, compute tunnel MTU.
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*/
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if (sp->req != NULL &&
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sp->req->sav != NULL &&
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sp->req->sav->sah != NULL) {
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ro = &sp->req->sav->sah->route_cache.sa_route;
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if (ro->ro_rt && ro->ro_rt->rt_ifp) {
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mtu =
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ro->ro_rt->rt_rmx.rmx_mtu ?
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ro->ro_rt->rt_rmx.rmx_mtu :
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ro->ro_rt->rt_ifp->if_mtu;
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mtu -= ipsechdr;
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}
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}
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KEY_FREESP(&sp);
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}
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return mtu;
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}
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/*
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*
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* Called from ip_output().
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* 1 = drop packet, 0 = continue processing packet,
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* -1 = packet was reinjected and stop processing packet
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*/
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int
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ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error)
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{
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#ifdef IPSEC
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struct secpolicy *sp = NULL;
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struct ip *ip = mtod(*m, struct ip *);
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struct tdb_ident *tdbi;
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struct m_tag *mtag;
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int s;
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/*
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* Check the security policy (SP) for the packet and, if
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* required, do IPsec-related processing. There are two
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* cases here; the first time a packet is sent through
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* it will be untagged and handled by ipsec4_checkpolicy.
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* If the packet is resubmitted to ip_output (e.g. after
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* AH, ESP, etc. processing), there will be a tag to bypass
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* the lookup and related policy checking.
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*/
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mtag = m_tag_find(*m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
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s = splnet();
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if (mtag != NULL) {
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tdbi = (struct tdb_ident *)(mtag + 1);
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sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
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if (sp == NULL)
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*error = -EINVAL; /* force silent drop */
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m_tag_delete(*m, mtag);
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} else {
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sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, *flags,
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error, inp);
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}
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/*
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* There are four return cases:
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* sp != NULL apply IPsec policy
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* sp == NULL, error == 0 no IPsec handling needed
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* sp == NULL, error == -EINVAL discard packet w/o error
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* sp == NULL, error != 0 discard packet, report error
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*/
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if (sp != NULL) {
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/* Loop detection, check if ipsec processing already done */
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KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
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for (mtag = m_tag_first(*m); mtag != NULL;
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mtag = m_tag_next(*m, mtag)) {
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if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
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continue;
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if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
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mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
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continue;
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/*
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* Check if policy has an SA associated with it.
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* This can happen when an SP has yet to acquire
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* an SA; e.g. on first reference. If it occurs,
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* then we let ipsec4_process_packet do its thing.
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*/
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if (sp->req->sav == NULL)
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break;
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tdbi = (struct tdb_ident *)(mtag + 1);
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if (tdbi->spi == sp->req->sav->spi &&
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tdbi->proto == sp->req->sav->sah->saidx.proto &&
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bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
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sizeof (union sockaddr_union)) == 0) {
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/*
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* No IPsec processing is needed, free
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* reference to SP.
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*
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* NB: null pointer to avoid free at
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* done: below.
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*/
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KEY_FREESP(&sp), sp = NULL;
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splx(s);
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goto done;
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}
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}
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/*
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* Do delayed checksums now because we send before
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* this is done in the normal processing path.
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*/
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if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
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in_delayed_cksum(*m);
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(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
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}
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#ifdef SCTP
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if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
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sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2));
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(*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
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}
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#endif
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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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/* NB: callee frees mbuf */
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*error = ipsec4_process_packet(*m, sp->req, *flags, 0);
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if (*error == EJUSTRETURN) {
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/*
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* We had a SP with a level of 'use' and no SA. We
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* will just continue to process the packet without
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* IPsec processing and return without error.
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*/
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*error = 0;
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ip->ip_len = ntohs(ip->ip_len);
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ip->ip_off = ntohs(ip->ip_off);
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goto done;
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}
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/*
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* Preserve KAME behaviour: ENOENT can be returned
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* when an SA acquire is in progress. Don't propagate
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* this to user-level; it confuses applications.
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*
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* XXX this will go away when the SADB is redone.
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*/
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if (*error == ENOENT)
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*error = 0;
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splx(s);
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goto reinjected;
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} else { /* sp == NULL */
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splx(s);
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if (*error != 0) {
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/*
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* Hack: -EINVAL is used to signal that a packet
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* should be silently discarded. This is typically
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* because we asked key management for an SA and
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* it was delayed (e.g. kicked up to IKE).
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*/
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if (*error == -EINVAL)
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*error = 0;
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goto bad;
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} else {
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/* No IPsec processing for this packet. */
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}
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}
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done:
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if (sp != NULL)
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KEY_FREESP(&sp);
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return 0;
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reinjected:
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if (sp != NULL)
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KEY_FREESP(&sp);
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return -1;
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bad:
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if (sp != NULL)
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KEY_FREESP(&sp);
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return 1;
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#endif /* IPSEC */
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return 0;
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}
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