1/*-
2 * Copyright (c) 1982, 1986, 1988, 1993
3 *      The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: releng/11.0/sys/netinet6/ip6_ipsec.c 288418 2015-09-30 08:16:33Z ae $");
32
33#include "opt_inet.h"
34#include "opt_sctp.h"
35#include "opt_ipsec.h"
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/kernel.h>
40#include <sys/mac.h>
41#include <sys/malloc.h>
42#include <sys/mbuf.h>
43#include <sys/protosw.h>
44#include <sys/socket.h>
45#include <sys/socketvar.h>
46#include <sys/sysctl.h>
47#include <sys/syslog.h>
48
49#include <net/if.h>
50#include <net/if_var.h>
51#include <net/vnet.h>
52
53#include <netinet/in.h>
54#include <netinet/in_systm.h>
55#include <netinet/in_var.h>
56#include <netinet/ip.h>
57#include <netinet/ip6.h>
58#include <netinet/in_pcb.h>
59#include <netinet/ip_var.h>
60#include <netinet/ip_options.h>
61#ifdef SCTP
62#include <netinet/sctp_crc32.h>
63#endif
64
65#include <machine/in_cksum.h>
66
67#include <netipsec/ipsec.h>
68#include <netipsec/ipsec6.h>
69#include <netipsec/xform.h>
70#include <netipsec/key.h>
71#ifdef IPSEC_DEBUG
72#include <netipsec/key_debug.h>
73#else
74#define	KEYDEBUG(lev,arg)
75#endif
76
77#include <netinet6/ip6_ipsec.h>
78#include <netinet6/ip6_var.h>
79
80extern	struct protosw inet6sw[];
81
82#ifdef IPSEC_FILTERTUNNEL
83static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 1;
84#else
85static VNET_DEFINE(int, ip6_ipsec6_filtertunnel) = 0;
86#endif
87#define	V_ip6_ipsec6_filtertunnel	VNET(ip6_ipsec6_filtertunnel)
88
89SYSCTL_DECL(_net_inet6_ipsec6);
90SYSCTL_INT(_net_inet6_ipsec6, OID_AUTO, filtertunnel,
91	CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_ipsec6_filtertunnel),  0,
92	"If set filter packets from an IPsec tunnel.");
93
94/*
95 * Check if we have to jump over firewall processing for this packet.
96 * Called from ip6_input().
97 * 1 = jump over firewall, 0 = packet goes through firewall.
98 */
99int
100ip6_ipsec_filtertunnel(struct mbuf *m)
101{
102
103	/*
104	 * Bypass packet filtering for packets previously handled by IPsec.
105	 */
106	if (!V_ip6_ipsec6_filtertunnel &&
107	    m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
108		return (1);
109	return (0);
110}
111
112/*
113 * Check if this packet has an active SA and needs to be dropped instead
114 * of forwarded.
115 * Called from ip6_forward().
116 * 1 = drop packet, 0 = forward packet.
117 */
118int
119ip6_ipsec_fwd(struct mbuf *m)
120{
121
122	return (ipsec6_in_reject(m, NULL));
123}
124
125/*
126 * Check if protocol type doesn't have a further header and do IPSEC
127 * decryption or reject right now.  Protocols with further headers get
128 * their IPSEC treatment within the protocol specific processing.
129 * Called from ip6_input().
130 * 1 = drop packet, 0 = continue processing packet.
131 */
132int
133ip6_ipsec_input(struct mbuf *m, int nxt)
134{
135
136	/*
137	 * enforce IPsec policy checking if we are seeing last header.
138	 * note that we do not visit this with protocols with pcb layer
139	 * code - like udp/tcp/raw ip.
140	 */
141	if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0)
142		return (ipsec6_in_reject(m, NULL));
143	return (0);
144}
145
146/*
147 * Called from ip6_output().
148 * 1 = drop packet, 0 = continue processing packet,
149 * -1 = packet was reinjected and stop processing packet
150 */
151
152int
153ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *error)
154{
155	struct secpolicy *sp;
156
157	/*
158	 * Check the security policy (SP) for the packet and, if
159	 * required, do IPsec-related processing.  There are two
160	 * cases here; the first time a packet is sent through
161	 * it will be untagged and handled by ipsec4_checkpolicy.
162	 * If the packet is resubmitted to ip6_output (e.g. after
163	 * AH, ESP, etc. processing), there will be a tag to bypass
164	 * the lookup and related policy checking.
165	 */
166	if (m_tag_find(*m, PACKET_TAG_IPSEC_OUT_DONE, NULL) != NULL) {
167		*error = 0;
168		return (0);
169	}
170	sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, error, inp);
171	/*
172	 * There are four return cases:
173	 *    sp != NULL		    apply IPsec policy
174	 *    sp == NULL, error == 0	    no IPsec handling needed
175	 *    sp == NULL, error == -EINVAL  discard packet w/o error
176	 *    sp == NULL, error != 0	    discard packet, report error
177	 */
178	if (sp != NULL) {
179		/*
180		 * Do delayed checksums now because we send before
181		 * this is done in the normal processing path.
182		 */
183#ifdef INET
184		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
185			in_delayed_cksum(*m);
186			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
187		}
188#endif
189		if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
190			in6_delayed_cksum(*m, (*m)->m_pkthdr.len - sizeof(struct ip6_hdr),
191							sizeof(struct ip6_hdr));
192			(*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
193		}
194#ifdef SCTP
195		if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
196			sctp_delayed_cksum(*m, sizeof(struct ip6_hdr));
197			(*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
198		}
199#endif
200
201		/* NB: callee frees mbuf */
202		*error = ipsec6_process_packet(*m, sp->req);
203		KEY_FREESP(&sp);
204		if (*error == EJUSTRETURN) {
205			/*
206			 * We had a SP with a level of 'use' and no SA. We
207			 * will just continue to process the packet without
208			 * IPsec processing.
209			 */
210			*error = 0;
211			goto done;
212		}
213
214		/*
215		 * Preserve KAME behaviour: ENOENT can be returned
216		 * when an SA acquire is in progress.  Don't propagate
217		 * this to user-level; it confuses applications.
218		 *
219		 * XXX this will go away when the SADB is redone.
220		 */
221		if (*error == ENOENT)
222			*error = 0;
223		goto reinjected;
224	} else {	/* sp == NULL */
225		if (*error != 0) {
226			/*
227			 * Hack: -EINVAL is used to signal that a packet
228			 * should be silently discarded.  This is typically
229			 * because we asked key management for an SA and
230			 * it was delayed (e.g. kicked up to IKE).
231			 */
232			if (*error == -EINVAL)
233				*error = 0;
234			goto bad;
235		}
236		/* No IPsec processing for this packet. */
237	}
238done:
239	return (0);
240reinjected:
241	return (-1);
242bad:
243	if (sp != NULL)
244		KEY_FREESP(&sp);
245	return (1);
246}
247
248#if 0
249/*
250 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
251 * Called from ip_forward().
252 * Returns MTU suggestion for ICMP needfrag reply.
253 */
254int
255ip6_ipsec_mtu(struct mbuf *m)
256{
257	int mtu = 0;
258	/*
259	 * If the packet is routed over IPsec tunnel, tell the
260	 * originator the tunnel MTU.
261	 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
262	 * XXX quickhack!!!
263	 */
264#ifdef IPSEC
265	struct secpolicy *sp = NULL;
266	int ipsecerror;
267	int ipsechdr;
268	struct route *ro;
269	sp = ipsec_getpolicybyaddr(m,
270				   IPSEC_DIR_OUTBOUND,
271				   IP_FORWARDING,
272				   &ipsecerror);
273	if (sp != NULL) {
274		/* count IPsec header size */
275		ipsechdr = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL);
276
277		/*
278		 * find the correct route for outer IPv4
279		 * header, compute tunnel MTU.
280		 */
281		if (sp->req != NULL &&
282		    sp->req->sav != NULL &&
283		    sp->req->sav->sah != NULL) {
284			ro = &sp->req->sav->sah->route_cache.sa_route;
285			if (ro->ro_rt && ro->ro_rt->rt_ifp) {
286				mtu = ro->ro_rt->rt_mtu ? ro->ro_rt->rt_mtu :
287				    ro->ro_rt->rt_ifp->if_mtu;
288				mtu -= ipsechdr;
289			}
290		}
291		KEY_FREESP(&sp);
292	}
293#endif /* IPSEC */
294	/* XXX else case missing. */
295	return mtu;
296}
297#endif
298