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/netinet/ip_ipsec.c 290165 2015-10-29 21:26:32Z gnn $");
32
33 #include "opt_ipsec.h"
34 #include "opt_sctp.h"
35
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/errno.h>
39 #include <sys/kernel.h>
40 #include <sys/malloc.h>
41 #include <sys/mbuf.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
44 #include <sys/socketvar.h>
45 #include <sys/sysctl.h>
46
47 #include <net/if.h>
48 #include <net/if_var.h>
49 #include <net/vnet.h>
50
51 #include <netinet/in.h>
52 #include <netinet/in_systm.h>
53 #include <netinet/in_var.h>
54 #include <netinet/ip.h>
55 #include <netinet/in_pcb.h>
56 #include <netinet/ip_var.h>
57 #include <netinet/ip_options.h>
58 #include <netinet/ip_ipsec.h>
59 #ifdef SCTP
60 #include <netinet/sctp_crc32.h>
61 #endif
62
63 #include <machine/in_cksum.h>
64
65 #include <netipsec/ipsec.h>
66 #include <netipsec/xform.h>
67 #include <netipsec/key.h>
68
69 extern struct protosw inetsw[];
70
71 #ifdef IPSEC_FILTERTUNNEL
72 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 1;
73 #else
74 static VNET_DEFINE(int, ip4_ipsec_filtertunnel) = 0;
75 #endif
76 #define V_ip4_ipsec_filtertunnel VNET(ip4_ipsec_filtertunnel)
77
78 SYSCTL_DECL(_net_inet_ipsec);
79 SYSCTL_INT(_net_inet_ipsec, OID_AUTO, filtertunnel,
80 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip4_ipsec_filtertunnel), 0,
81 "If set filter packets from an IPsec tunnel.");
82
83 /*
84 * Check if we have to jump over firewall processing for this packet.
85 * Called from ip_input().
86 * 1 = jump over firewall, 0 = packet goes through firewall.
87 */
88 int
89 ip_ipsec_filtertunnel(struct mbuf *m)
90 {
91
92 /*
93 * Bypass packet filtering for packets previously handled by IPsec.
94 */
95 if (!V_ip4_ipsec_filtertunnel &&
96 m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
97 return 1;
98 return 0;
99 }
100
101 /*
102 * Check if this packet has an active SA and needs to be dropped instead
103 * of forwarded.
104 * Called from ip_forward().
105 * 1 = drop packet, 0 = forward packet.
106 */
107 int
108 ip_ipsec_fwd(struct mbuf *m)
109 {
110
111 return (ipsec4_in_reject(m, NULL));
112 }
113
114 /*
115 * Check if protocol type doesn't have a further header and do IPSEC
116 * decryption or reject right now. Protocols with further headers get
117 * their IPSEC treatment within the protocol specific processing.
118 * Called from ip_input().
119 * 1 = drop packet, 0 = continue processing packet.
120 */
121 int
122 ip_ipsec_input(struct mbuf *m, int nxt)
123 {
124 /*
125 * enforce IPsec policy checking if we are seeing last header.
126 * note that we do not visit this with protocols with pcb layer
127 * code - like udp/tcp/raw ip.
128 */
129 if ((inetsw[ip_protox[nxt]].pr_flags & PR_LASTHDR) != 0)
130 return (ipsec4_in_reject(m, NULL));
131 return (0);
132 }
133
134 /*
135 * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
136 * Called from ip_forward().
137 * Returns MTU suggestion for ICMP needfrag reply.
138 */
139 int
140 ip_ipsec_mtu(struct mbuf *m, int mtu)
141 {
142 /*
143 * If the packet is routed over IPsec tunnel, tell the
144 * originator the tunnel MTU.
145 * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
146 * XXX quickhack!!!
147 */
148 return (mtu - ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, NULL));
149 }
150
151 /*
152 *
153 * Called from ip_output().
154 * 1 = drop packet, 0 = continue processing packet,
155 * -1 = packet was reinjected and stop processing packet
156 */
157 int
158 ip_ipsec_output(struct mbuf **m, struct inpcb *inp, int *error)
159 {
160 struct secpolicy *sp;
161
162 if (!key_havesp(IPSEC_DIR_OUTBOUND))
163 return 0;
164
165 /*
166 * Check the security policy (SP) for the packet and, if
167 * required, do IPsec-related processing. There are two
168 * cases here; the first time a packet is sent through
169 * it will be untagged and handled by ipsec4_checkpolicy.
170 * If the packet is resubmitted to ip_output (e.g. after
171 * AH, ESP, etc. processing), there will be a tag to bypass
172 * the lookup and related policy checking.
173 */
174 if (m_tag_find(*m, PACKET_TAG_IPSEC_OUT_DONE, NULL) != NULL) {
175 *error = 0;
176 return (0);
177 }
178 sp = ipsec4_checkpolicy(*m, IPSEC_DIR_OUTBOUND, error, inp);
179 /*
180 * There are four return cases:
181 * sp != NULL apply IPsec policy
182 * sp == NULL, error == 0 no IPsec handling needed
183 * sp == NULL, error == -EINVAL discard packet w/o error
184 * sp == NULL, error != 0 discard packet, report error
185 */
186 if (sp != NULL) {
187 /*
188 * Do delayed checksums now because we send before
189 * this is done in the normal processing path.
190 */
191 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
192 in_delayed_cksum(*m);
193 (*m)->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
194 }
195 #ifdef SCTP
196 if ((*m)->m_pkthdr.csum_flags & CSUM_SCTP) {
197 struct ip *ip = mtod(*m, struct ip *);
198
199 sctp_delayed_cksum(*m, (uint32_t)(ip->ip_hl << 2));
200 (*m)->m_pkthdr.csum_flags &= ~CSUM_SCTP;
201 }
202 #endif
203
204 /* NB: callee frees mbuf */
205 *error = ipsec4_process_packet(*m, sp->req);
206 KEY_FREESP(&sp);
207 if (*error == EJUSTRETURN) {
208 /*
209 * We had a SP with a level of 'use' and no SA. We
210 * will just continue to process the packet without
211 * IPsec processing and return without error.
212 */
213 *error = 0;
214 goto done;
215 }
216 /*
217 * Preserve KAME behaviour: ENOENT can be returned
218 * when an SA acquire is in progress. Don't propagate
219 * this to user-level; it confuses applications.
220 *
221 * XXX this will go away when the SADB is redone.
222 */
223 if (*error == ENOENT)
224 *error = 0;
225 goto reinjected;
226 } else { /* sp == NULL */
227
228 if (*error != 0) {
229 /*
230 * Hack: -EINVAL is used to signal that a packet
231 * should be silently discarded. This is typically
232 * because we asked key management for an SA and
233 * it was delayed (e.g. kicked up to IKE).
234 */
235 if (*error == -EINVAL)
236 *error = 0;
237 goto bad;
238 }
239 /* No IPsec processing for this packet. */
240 }
241 done:
242 return (0);
243 reinjected:
244 return (-1);
245 bad:
246 if (sp != NULL)
247 KEY_FREESP(&sp);
248 return 1;
249 }
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