1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2019 Yandex LLC
5 * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
6 * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/counter.h>
34 #include <sys/kernel.h>
35 #include <sys/lock.h>
36 #include <sys/mbuf.h>
37 #include <sys/module.h>
38 #include <sys/rmlock.h>
39 #include <sys/rwlock.h>
40 #include <sys/socket.h>
41 #include <sys/sysctl.h>
42
43 #include <net/if.h>
44 #include <net/if_var.h>
45 #include <net/if_pflog.h>
46 #include <net/pfil.h>
47
48 #include <netinet/in.h>
49 #include <netinet/ip.h>
50 #include <netinet/ip_icmp.h>
51 #include <netinet/ip_var.h>
52 #include <netinet/ip_fw.h>
53 #include <netinet/ip6.h>
54 #include <netinet/icmp6.h>
55 #include <netinet6/ip_fw_nat64.h>
56
57 #include <netpfil/ipfw/ip_fw_private.h>
58 #include <netpfil/pf/pf.h>
59
60 #include "nat64clat.h"
61
62 #define NAT64_LOOKUP(chain, cmd) \
63 (struct nat64clat_cfg *)SRV_OBJECT((chain), (cmd)->arg1)
64
65 static void
nat64clat_log(struct pfloghdr * plog,struct mbuf * m,sa_family_t family,uint32_t kidx)66 nat64clat_log(struct pfloghdr *plog, struct mbuf *m, sa_family_t family,
67 uint32_t kidx)
68 {
69 static uint32_t pktid = 0;
70
71 memset(plog, 0, sizeof(*plog));
72 plog->length = PFLOG_HDRLEN;
73 plog->af = family;
74 plog->action = PF_NAT;
75 plog->dir = PF_IN;
76 plog->rulenr = htonl(kidx);
77 pktid++;
78 plog->subrulenr = htonl(pktid);
79 plog->ruleset[0] = '\0';
80 strlcpy(plog->ifname, "NAT64CLAT", sizeof(plog->ifname));
81 ipfw_bpf_mtap2(plog, PFLOG_HDRLEN, m);
82 }
83
84 static int
nat64clat_handle_ip4(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)85 nat64clat_handle_ip4(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
86 struct mbuf *m)
87 {
88 struct pfloghdr loghdr, *logdata;
89 struct in6_addr saddr, daddr;
90 struct ip *ip;
91
92 ip = mtod(m, struct ip*);
93 /* source address for CLAT may be private with no harm */
94 if (nat64_check_ip4(ip->ip_src.s_addr) != 0 ||
95 nat64_check_ip4(ip->ip_dst.s_addr) != 0 ||
96 nat64_check_private_ip4(&cfg->base, ip->ip_dst.s_addr) != 0)
97 return (NAT64SKIP);
98
99 memcpy(&saddr, &cfg->base.clat_prefix, sizeof(saddr));
100 nat64_embed_ip4(&saddr, cfg->base.clat_plen, ip->ip_src.s_addr);
101 memcpy(&daddr, &cfg->base.plat_prefix, sizeof(daddr));
102 nat64_embed_ip4(&daddr, cfg->base.plat_plen, ip->ip_dst.s_addr);
103 if (cfg->base.flags & NAT64_LOG) {
104 logdata = &loghdr;
105 nat64clat_log(logdata, m, AF_INET, cfg->no.kidx);
106 } else
107 logdata = NULL;
108 return (nat64_do_handle_ip4(m, &saddr, &daddr, 0, &cfg->base,
109 logdata));
110 }
111
112 static int
nat64clat_handle_ip6(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)113 nat64clat_handle_ip6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
114 struct mbuf *m)
115 {
116 struct pfloghdr loghdr, *logdata;
117 struct ip6_hdr *ip6;
118 uint32_t aaddr;
119
120 /*
121 * NOTE: we expect ipfw_chk() did m_pullup() up to upper level
122 * protocol's headers. Also we skip some checks, that ip6_input(),
123 * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did.
124 */
125 ip6 = mtod(m, struct ip6_hdr *);
126 /* Check ip6_dst matches configured prefix */
127 if (memcmp(&ip6->ip6_dst, &cfg->base.clat_prefix,
128 cfg->base.clat_plen / 8) != 0)
129 return (NAT64SKIP);
130 /* Check ip6_src matches configured prefix */
131 if (memcmp(&ip6->ip6_src, &cfg->base.plat_prefix,
132 cfg->base.plat_plen / 8) != 0)
133 return (NAT64SKIP);
134
135 if (cfg->base.flags & NAT64_LOG) {
136 logdata = &loghdr;
137 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
138 } else
139 logdata = NULL;
140
141 aaddr = nat64_extract_ip4(&ip6->ip6_src, cfg->base.plat_plen);
142 return (nat64_do_handle_ip6(m, aaddr, 0, &cfg->base, logdata));
143 }
144
145 static int
nat64clat_handle_icmp6(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)146 nat64clat_handle_icmp6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
147 struct mbuf *m)
148 {
149 struct pfloghdr loghdr, *logdata;
150 struct nat64_counters *stats;
151 struct ip6_hdr *ip6i;
152 struct icmp6_hdr *icmp6;
153 uint32_t daddr;
154 int hlen, proto;
155
156 hlen = 0;
157 stats = &cfg->base.stats;
158 proto = nat64_getlasthdr(m, &hlen);
159 if (proto != IPPROTO_ICMPV6) {
160 NAT64STAT_INC(stats, dropped);
161 return (NAT64MFREE);
162 }
163 icmp6 = mtodo(m, hlen);
164 switch (icmp6->icmp6_type) {
165 case ICMP6_DST_UNREACH:
166 case ICMP6_PACKET_TOO_BIG:
167 case ICMP6_TIME_EXCEED_TRANSIT:
168 case ICMP6_PARAM_PROB:
169 break;
170 default:
171 NAT64STAT_INC(stats, dropped);
172 return (NAT64MFREE);
173 }
174 hlen += sizeof(struct icmp6_hdr);
175 if (m->m_pkthdr.len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) {
176 NAT64STAT_INC(stats, dropped);
177 return (NAT64MFREE);
178 }
179 if (m->m_len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN)
180 m = m_pullup(m, hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN);
181 if (m == NULL) {
182 NAT64STAT_INC(stats, nomem);
183 return (NAT64RETURN);
184 }
185 /*
186 * Use destination address from inner IPv6 header to determine
187 * IPv4 mapped address.
188 */
189 ip6i = mtodo(m, hlen);
190 daddr = nat64_extract_ip4(&ip6i->ip6_dst, cfg->base.clat_plen);
191 if (daddr == 0) {
192 NAT64STAT_INC(stats, dropped);
193 return (NAT64MFREE);
194 }
195 if (cfg->base.flags & NAT64_LOG) {
196 logdata = &loghdr;
197 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
198 } else
199 logdata = NULL;
200 return (nat64_handle_icmp6(m, 0, daddr, 0, &cfg->base, logdata));
201 }
202
203 int
ipfw_nat64clat(struct ip_fw_chain * chain,struct ip_fw_args * args,ipfw_insn * cmd,int * done)204 ipfw_nat64clat(struct ip_fw_chain *chain, struct ip_fw_args *args,
205 ipfw_insn *cmd, int *done)
206 {
207 ipfw_insn *icmd;
208 struct nat64clat_cfg *cfg;
209 int ret;
210
211 IPFW_RLOCK_ASSERT(chain);
212
213 *done = 0; /* try next rule if not matched */
214 icmd = cmd + 1;
215 if (cmd->opcode != O_EXTERNAL_ACTION ||
216 cmd->arg1 != V_nat64clat_eid ||
217 icmd->opcode != O_EXTERNAL_INSTANCE ||
218 (cfg = NAT64_LOOKUP(chain, icmd)) == NULL)
219 return (0);
220
221 switch (args->f_id.addr_type) {
222 case 4:
223 ret = nat64clat_handle_ip4(chain, cfg, args->m);
224 break;
225 case 6:
226 ret = nat64clat_handle_ip6(chain, cfg, args->m);
227 break;
228 default:
229 return (0);
230 }
231
232 if (ret == NAT64SKIP) {
233 /*
234 * In case when packet is ICMPv6 message from an intermediate
235 * router, the source address of message will not match the
236 * addresses from configured prefixes.
237 */
238 if (args->f_id.proto != IPPROTO_ICMPV6)
239 return (0);
240
241 ret = nat64clat_handle_icmp6(chain, cfg, args->m);
242 }
243
244 if (ret == NAT64SKIP)
245 return (0);
246
247 *done = 1; /* terminate the search */
248 if (ret == NAT64MFREE)
249 m_freem(args->m);
250
251 args->m = NULL;
252 return (IP_FW_NAT64);
253 }
254