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4f7418a09f
in OpenBSD. As it is now, there is no way for this to be useful, since IPsec is free to forward packets via whatever interface it wants, so checking capabilities of the interface passed from ip_output (fetched from the routing table) serves no purpose. Discussed with: sam@
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 from a tunnel.
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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->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);
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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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