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/param.h>
31 #include <sys/systm.h>
32 #include <sys/counter.h>
33 #include <sys/kernel.h>
34 #include <sys/lock.h>
35 #include <sys/mbuf.h>
36 #include <sys/module.h>
37 #include <sys/rmlock.h>
38 #include <sys/rwlock.h>
39 #include <sys/socket.h>
40 #include <sys/sysctl.h>
41
42 #include <net/if.h>
43 #include <net/if_var.h>
44 #include <net/if_pflog.h>
45 #include <net/pfil.h>
46
47 #include <netinet/in.h>
48 #include <netinet/ip.h>
49 #include <netinet/ip_icmp.h>
50 #include <netinet/ip_var.h>
51 #include <netinet/ip_fw.h>
52 #include <netinet/ip6.h>
53 #include <netinet/icmp6.h>
54 #include <netinet6/ip_fw_nat64.h>
55
56 #include <netpfil/ipfw/ip_fw_private.h>
57 #include <netpfil/pf/pf.h>
58
59 #include "nat64clat.h"
60
61 #define NAT64_LOOKUP(chain, cmd) \
62 (struct nat64clat_cfg *)SRV_OBJECT((chain), (cmd)->arg1)
63
64 static void
nat64clat_log(struct pfloghdr * plog,struct mbuf * m,sa_family_t family,uint32_t kidx)65 nat64clat_log(struct pfloghdr *plog, struct mbuf *m, sa_family_t family,
66 uint32_t kidx)
67 {
68 static uint32_t pktid = 0;
69
70 memset(plog, 0, sizeof(*plog));
71 plog->length = PFLOG_HDRLEN;
72 plog->af = family;
73 plog->action = PF_NAT;
74 plog->dir = PF_IN;
75 plog->rulenr = htonl(kidx);
76 pktid++;
77 plog->subrulenr = htonl(pktid);
78 plog->ruleset[0] = '\0';
79 strlcpy(plog->ifname, "NAT64CLAT", sizeof(plog->ifname));
80 ipfw_bpf_mtap2(plog, PFLOG_HDRLEN, m);
81 }
82
83 static int
nat64clat_handle_ip4(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)84 nat64clat_handle_ip4(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
85 struct mbuf *m)
86 {
87 struct pfloghdr loghdr, *logdata;
88 struct in6_addr saddr, daddr;
89 struct ip *ip;
90
91 ip = mtod(m, struct ip*);
92 /* source address for CLAT may be private with no harm */
93 if (nat64_check_ip4(ip->ip_src.s_addr) != 0 ||
94 nat64_check_ip4(ip->ip_dst.s_addr) != 0 ||
95 nat64_check_private_ip4(&cfg->base, ip->ip_dst.s_addr) != 0)
96 return (NAT64SKIP);
97
98 memcpy(&saddr, &cfg->base.clat_prefix, sizeof(saddr));
99 nat64_embed_ip4(&saddr, cfg->base.clat_plen, ip->ip_src.s_addr);
100 memcpy(&daddr, &cfg->base.plat_prefix, sizeof(daddr));
101 nat64_embed_ip4(&daddr, cfg->base.plat_plen, ip->ip_dst.s_addr);
102 if (cfg->base.flags & NAT64_LOG) {
103 logdata = &loghdr;
104 nat64clat_log(logdata, m, AF_INET, cfg->no.kidx);
105 } else
106 logdata = NULL;
107 return (nat64_do_handle_ip4(m, &saddr, &daddr, 0, &cfg->base,
108 logdata));
109 }
110
111 static int
nat64clat_handle_ip6(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)112 nat64clat_handle_ip6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
113 struct mbuf *m)
114 {
115 struct pfloghdr loghdr, *logdata;
116 struct ip6_hdr *ip6;
117 uint32_t aaddr;
118
119 /*
120 * NOTE: we expect ipfw_chk() did m_pullup() up to upper level
121 * protocol's headers. Also we skip some checks, that ip6_input(),
122 * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did.
123 */
124 ip6 = mtod(m, struct ip6_hdr *);
125 /* Check ip6_dst matches configured prefix */
126 if (memcmp(&ip6->ip6_dst, &cfg->base.clat_prefix,
127 cfg->base.clat_plen / 8) != 0)
128 return (NAT64SKIP);
129 /* Check ip6_src matches configured prefix */
130 if (memcmp(&ip6->ip6_src, &cfg->base.plat_prefix,
131 cfg->base.plat_plen / 8) != 0)
132 return (NAT64SKIP);
133
134 if (cfg->base.flags & NAT64_LOG) {
135 logdata = &loghdr;
136 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
137 } else
138 logdata = NULL;
139
140 aaddr = nat64_extract_ip4(&ip6->ip6_src, cfg->base.plat_plen);
141 return (nat64_do_handle_ip6(m, aaddr, 0, &cfg->base, logdata));
142 }
143
144 static int
nat64clat_handle_icmp6(struct ip_fw_chain * chain,struct nat64clat_cfg * cfg,struct mbuf * m)145 nat64clat_handle_icmp6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
146 struct mbuf *m)
147 {
148 struct pfloghdr loghdr, *logdata;
149 struct nat64_counters *stats;
150 struct ip6_hdr *ip6i;
151 struct icmp6_hdr *icmp6;
152 uint32_t daddr;
153 int hlen, proto;
154
155 hlen = 0;
156 stats = &cfg->base.stats;
157 proto = nat64_getlasthdr(m, &hlen);
158 if (proto != IPPROTO_ICMPV6) {
159 NAT64STAT_INC(stats, dropped);
160 return (NAT64MFREE);
161 }
162 icmp6 = mtodo(m, hlen);
163 switch (icmp6->icmp6_type) {
164 case ICMP6_DST_UNREACH:
165 case ICMP6_PACKET_TOO_BIG:
166 case ICMP6_TIME_EXCEED_TRANSIT:
167 case ICMP6_PARAM_PROB:
168 break;
169 default:
170 NAT64STAT_INC(stats, dropped);
171 return (NAT64MFREE);
172 }
173 hlen += sizeof(struct icmp6_hdr);
174 if (m->m_pkthdr.len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) {
175 NAT64STAT_INC(stats, dropped);
176 return (NAT64MFREE);
177 }
178 if (m->m_len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN)
179 m = m_pullup(m, hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN);
180 if (m == NULL) {
181 NAT64STAT_INC(stats, nomem);
182 return (NAT64RETURN);
183 }
184 /*
185 * Use destination address from inner IPv6 header to determine
186 * IPv4 mapped address.
187 */
188 ip6i = mtodo(m, hlen);
189 daddr = nat64_extract_ip4(&ip6i->ip6_dst, cfg->base.clat_plen);
190 if (daddr == 0) {
191 NAT64STAT_INC(stats, dropped);
192 return (NAT64MFREE);
193 }
194 if (cfg->base.flags & NAT64_LOG) {
195 logdata = &loghdr;
196 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
197 } else
198 logdata = NULL;
199 return (nat64_handle_icmp6(m, 0, daddr, 0, &cfg->base, logdata));
200 }
201
202 int
ipfw_nat64clat(struct ip_fw_chain * chain,struct ip_fw_args * args,ipfw_insn * cmd,int * done)203 ipfw_nat64clat(struct ip_fw_chain *chain, struct ip_fw_args *args,
204 ipfw_insn *cmd, int *done)
205 {
206 ipfw_insn *icmd;
207 struct nat64clat_cfg *cfg;
208 int ret;
209
210 IPFW_RLOCK_ASSERT(chain);
211
212 *done = 0; /* try next rule if not matched */
213 icmd = cmd + 1;
214 if (cmd->opcode != O_EXTERNAL_ACTION ||
215 cmd->arg1 != V_nat64clat_eid ||
216 icmd->opcode != O_EXTERNAL_INSTANCE ||
217 (cfg = NAT64_LOOKUP(chain, icmd)) == NULL)
218 return (0);
219
220 switch (args->f_id.addr_type) {
221 case 4:
222 ret = nat64clat_handle_ip4(chain, cfg, args->m);
223 break;
224 case 6:
225 ret = nat64clat_handle_ip6(chain, cfg, args->m);
226 break;
227 default:
228 return (0);
229 }
230
231 if (ret == NAT64SKIP) {
232 /*
233 * In case when packet is ICMPv6 message from an intermediate
234 * router, the source address of message will not match the
235 * addresses from configured prefixes.
236 */
237 if (args->f_id.proto != IPPROTO_ICMPV6)
238 return (0);
239
240 ret = nat64clat_handle_icmp6(chain, cfg, args->m);
241 }
242
243 if (ret == NAT64SKIP)
244 return (0);
245
246 *done = 1; /* terminate the search */
247 if (ret == NAT64MFREE)
248 m_freem(args->m);
249
250 args->m = NULL;
251 return (IP_FW_NAT64);
252 }
253