1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
4 * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
5 * Copyright (c) 2012 Intel Corporation
6 */
7
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/skbuff.h>
11#include <linux/ip.h>
12#include <linux/string.h>
13#include <linux/netlink.h>
14#include <linux/netfilter.h>
15#include <linux/netfilter_ipv4.h>
16#include <linux/netfilter/nfnetlink.h>
17#include <linux/netfilter/nf_tables.h>
18#include <net/netfilter/nf_conntrack.h>
19#include <net/netfilter/nf_nat.h>
20#include <net/netfilter/nf_tables.h>
21#include <net/ip.h>
22
23struct nft_nat {
24 u8 sreg_addr_min;
25 u8 sreg_addr_max;
26 u8 sreg_proto_min;
27 u8 sreg_proto_max;
28 enum nf_nat_manip_type type:8;
29 u8 family;
30 u16 flags;
31};
32
33static void nft_nat_setup_addr(struct nf_nat_range2 *range,
34 const struct nft_regs *regs,
35 const struct nft_nat *priv)
36{
37 switch (priv->family) {
38 case AF_INET:
39 range->min_addr.ip = (__force __be32)
40 regs->data[priv->sreg_addr_min];
41 range->max_addr.ip = (__force __be32)
42 regs->data[priv->sreg_addr_max];
43 break;
44 case AF_INET6:
45 memcpy(range->min_addr.ip6, &regs->data[priv->sreg_addr_min],
46 sizeof(range->min_addr.ip6));
47 memcpy(range->max_addr.ip6, &regs->data[priv->sreg_addr_max],
48 sizeof(range->max_addr.ip6));
49 break;
50 }
51}
52
53static void nft_nat_setup_proto(struct nf_nat_range2 *range,
54 const struct nft_regs *regs,
55 const struct nft_nat *priv)
56{
57 range->min_proto.all = (__force __be16)
58 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_min]);
59 range->max_proto.all = (__force __be16)
60 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_max]);
61}
62
63static void nft_nat_setup_netmap(struct nf_nat_range2 *range,
64 const struct nft_pktinfo *pkt,
65 const struct nft_nat *priv)
66{
67 struct sk_buff *skb = pkt->skb;
68 union nf_inet_addr new_addr;
69 __be32 netmask;
70 int i, len = 0;
71
72 switch (priv->type) {
73 case NFT_NAT_SNAT:
74 if (nft_pf(pkt) == NFPROTO_IPV4) {
75 new_addr.ip = ip_hdr(skb)->saddr;
76 len = sizeof(struct in_addr);
77 } else {
78 new_addr.in6 = ipv6_hdr(skb)->saddr;
79 len = sizeof(struct in6_addr);
80 }
81 break;
82 case NFT_NAT_DNAT:
83 if (nft_pf(pkt) == NFPROTO_IPV4) {
84 new_addr.ip = ip_hdr(skb)->daddr;
85 len = sizeof(struct in_addr);
86 } else {
87 new_addr.in6 = ipv6_hdr(skb)->daddr;
88 len = sizeof(struct in6_addr);
89 }
90 break;
91 }
92
93 for (i = 0; i < len / sizeof(__be32); i++) {
94 netmask = ~(range->min_addr.ip6[i] ^ range->max_addr.ip6[i]);
95 new_addr.ip6[i] &= ~netmask;
96 new_addr.ip6[i] |= range->min_addr.ip6[i] & netmask;
97 }
98
99 range->min_addr = new_addr;
100 range->max_addr = new_addr;
101}
102
103static void nft_nat_eval(const struct nft_expr *expr,
104 struct nft_regs *regs,
105 const struct nft_pktinfo *pkt)
106{
107 const struct nft_nat *priv = nft_expr_priv(expr);
108 enum ip_conntrack_info ctinfo;
109 struct nf_conn *ct = nf_ct_get(skb: pkt->skb, ctinfo: &ctinfo);
110 struct nf_nat_range2 range;
111
112 memset(&range, 0, sizeof(range));
113
114 if (priv->sreg_addr_min) {
115 nft_nat_setup_addr(range: &range, regs, priv);
116 if (priv->flags & NF_NAT_RANGE_NETMAP)
117 nft_nat_setup_netmap(range: &range, pkt, priv);
118 }
119
120 if (priv->sreg_proto_min)
121 nft_nat_setup_proto(range: &range, regs, priv);
122
123 range.flags = priv->flags;
124
125 regs->verdict.code = nf_nat_setup_info(ct, range: &range, maniptype: priv->type);
126}
127
128static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
129 [NFTA_NAT_TYPE] = { .type = NLA_U32 },
130 [NFTA_NAT_FAMILY] = { .type = NLA_U32 },
131 [NFTA_NAT_REG_ADDR_MIN] = { .type = NLA_U32 },
132 [NFTA_NAT_REG_ADDR_MAX] = { .type = NLA_U32 },
133 [NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
134 [NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
135 [NFTA_NAT_FLAGS] =
136 NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
137};
138
139static int nft_nat_validate(const struct nft_ctx *ctx,
140 const struct nft_expr *expr)
141{
142 struct nft_nat *priv = nft_expr_priv(expr);
143 int err;
144
145 if (ctx->family != NFPROTO_IPV4 &&
146 ctx->family != NFPROTO_IPV6 &&
147 ctx->family != NFPROTO_INET)
148 return -EOPNOTSUPP;
149
150 err = nft_chain_validate_dependency(chain: ctx->chain, type: NFT_CHAIN_T_NAT);
151 if (err < 0)
152 return err;
153
154 switch (priv->type) {
155 case NFT_NAT_SNAT:
156 err = nft_chain_validate_hooks(chain: ctx->chain,
157 hook_flags: (1 << NF_INET_POST_ROUTING) |
158 (1 << NF_INET_LOCAL_IN));
159 break;
160 case NFT_NAT_DNAT:
161 err = nft_chain_validate_hooks(chain: ctx->chain,
162 hook_flags: (1 << NF_INET_PRE_ROUTING) |
163 (1 << NF_INET_LOCAL_OUT));
164 break;
165 }
166
167 return err;
168}
169
170static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
171 const struct nlattr * const tb[])
172{
173 struct nft_nat *priv = nft_expr_priv(expr);
174 unsigned int alen, plen;
175 u32 family;
176 int err;
177
178 if (tb[NFTA_NAT_TYPE] == NULL ||
179 (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
180 tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
181 return -EINVAL;
182
183 switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
184 case NFT_NAT_SNAT:
185 priv->type = NF_NAT_MANIP_SRC;
186 break;
187 case NFT_NAT_DNAT:
188 priv->type = NF_NAT_MANIP_DST;
189 break;
190 default:
191 return -EOPNOTSUPP;
192 }
193
194 if (tb[NFTA_NAT_FAMILY] == NULL)
195 return -EINVAL;
196
197 family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
198 if (ctx->family != NFPROTO_INET && ctx->family != family)
199 return -EOPNOTSUPP;
200
201 switch (family) {
202 case NFPROTO_IPV4:
203 alen = sizeof_field(struct nf_nat_range, min_addr.ip);
204 break;
205 case NFPROTO_IPV6:
206 alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
207 break;
208 default:
209 if (tb[NFTA_NAT_REG_ADDR_MIN])
210 return -EAFNOSUPPORT;
211 break;
212 }
213 priv->family = family;
214
215 if (tb[NFTA_NAT_REG_ADDR_MIN]) {
216 err = nft_parse_register_load(ctx, attr: tb[NFTA_NAT_REG_ADDR_MIN],
217 sreg: &priv->sreg_addr_min, len: alen);
218 if (err < 0)
219 return err;
220
221 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
222 err = nft_parse_register_load(ctx, attr: tb[NFTA_NAT_REG_ADDR_MAX],
223 sreg: &priv->sreg_addr_max,
224 len: alen);
225 if (err < 0)
226 return err;
227 } else {
228 priv->sreg_addr_max = priv->sreg_addr_min;
229 }
230
231 priv->flags |= NF_NAT_RANGE_MAP_IPS;
232 }
233
234 plen = sizeof_field(struct nf_nat_range, min_proto.all);
235 if (tb[NFTA_NAT_REG_PROTO_MIN]) {
236 err = nft_parse_register_load(ctx, attr: tb[NFTA_NAT_REG_PROTO_MIN],
237 sreg: &priv->sreg_proto_min, len: plen);
238 if (err < 0)
239 return err;
240
241 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
242 err = nft_parse_register_load(ctx, attr: tb[NFTA_NAT_REG_PROTO_MAX],
243 sreg: &priv->sreg_proto_max,
244 len: plen);
245 if (err < 0)
246 return err;
247 } else {
248 priv->sreg_proto_max = priv->sreg_proto_min;
249 }
250
251 priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
252 }
253
254 if (tb[NFTA_NAT_FLAGS])
255 priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
256
257 return nf_ct_netns_get(net: ctx->net, nfproto: family);
258}
259
260static int nft_nat_dump(struct sk_buff *skb,
261 const struct nft_expr *expr, bool reset)
262{
263 const struct nft_nat *priv = nft_expr_priv(expr);
264
265 switch (priv->type) {
266 case NF_NAT_MANIP_SRC:
267 if (nla_put_be32(skb, attrtype: NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
268 goto nla_put_failure;
269 break;
270 case NF_NAT_MANIP_DST:
271 if (nla_put_be32(skb, attrtype: NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
272 goto nla_put_failure;
273 break;
274 }
275
276 if (nla_put_be32(skb, attrtype: NFTA_NAT_FAMILY, htonl(priv->family)))
277 goto nla_put_failure;
278
279 if (priv->sreg_addr_min) {
280 if (nft_dump_register(skb, attr: NFTA_NAT_REG_ADDR_MIN,
281 reg: priv->sreg_addr_min) ||
282 nft_dump_register(skb, attr: NFTA_NAT_REG_ADDR_MAX,
283 reg: priv->sreg_addr_max))
284 goto nla_put_failure;
285 }
286
287 if (priv->sreg_proto_min) {
288 if (nft_dump_register(skb, attr: NFTA_NAT_REG_PROTO_MIN,
289 reg: priv->sreg_proto_min) ||
290 nft_dump_register(skb, attr: NFTA_NAT_REG_PROTO_MAX,
291 reg: priv->sreg_proto_max))
292 goto nla_put_failure;
293 }
294
295 if (priv->flags != 0) {
296 if (nla_put_be32(skb, attrtype: NFTA_NAT_FLAGS, htonl(priv->flags)))
297 goto nla_put_failure;
298 }
299
300 return 0;
301
302nla_put_failure:
303 return -1;
304}
305
306static void
307nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
308{
309 const struct nft_nat *priv = nft_expr_priv(expr);
310
311 nf_ct_netns_put(net: ctx->net, nfproto: priv->family);
312}
313
314static struct nft_expr_type nft_nat_type;
315static const struct nft_expr_ops nft_nat_ops = {
316 .type = &nft_nat_type,
317 .size = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
318 .eval = nft_nat_eval,
319 .init = nft_nat_init,
320 .destroy = nft_nat_destroy,
321 .dump = nft_nat_dump,
322 .validate = nft_nat_validate,
323 .reduce = NFT_REDUCE_READONLY,
324};
325
326static struct nft_expr_type nft_nat_type __read_mostly = {
327 .name = "nat",
328 .ops = &nft_nat_ops,
329 .policy = nft_nat_policy,
330 .maxattr = NFTA_NAT_MAX,
331 .owner = THIS_MODULE,
332};
333
334#ifdef CONFIG_NF_TABLES_INET
335static void nft_nat_inet_eval(const struct nft_expr *expr,
336 struct nft_regs *regs,
337 const struct nft_pktinfo *pkt)
338{
339 const struct nft_nat *priv = nft_expr_priv(expr);
340
341 if (priv->family == nft_pf(pkt) ||
342 priv->family == NFPROTO_INET)
343 nft_nat_eval(expr, regs, pkt);
344}
345
346static const struct nft_expr_ops nft_nat_inet_ops = {
347 .type = &nft_nat_type,
348 .size = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
349 .eval = nft_nat_inet_eval,
350 .init = nft_nat_init,
351 .destroy = nft_nat_destroy,
352 .dump = nft_nat_dump,
353 .validate = nft_nat_validate,
354 .reduce = NFT_REDUCE_READONLY,
355};
356
357static struct nft_expr_type nft_inet_nat_type __read_mostly = {
358 .name = "nat",
359 .family = NFPROTO_INET,
360 .ops = &nft_nat_inet_ops,
361 .policy = nft_nat_policy,
362 .maxattr = NFTA_NAT_MAX,
363 .owner = THIS_MODULE,
364};
365
366static int nft_nat_inet_module_init(void)
367{
368 return nft_register_expr(&nft_inet_nat_type);
369}
370
371static void nft_nat_inet_module_exit(void)
372{
373 nft_unregister_expr(&nft_inet_nat_type);
374}
375#else
376static int nft_nat_inet_module_init(void) { return 0; }
377static void nft_nat_inet_module_exit(void) { }
378#endif
379
380static int __init nft_nat_module_init(void)
381{
382 int ret = nft_nat_inet_module_init();
383
384 if (ret)
385 return ret;
386
387 ret = nft_register_expr(&nft_nat_type);
388 if (ret)
389 nft_nat_inet_module_exit();
390
391 return ret;
392}
393
394static void __exit nft_nat_module_exit(void)
395{
396 nft_nat_inet_module_exit();
397 nft_unregister_expr(&nft_nat_type);
398}
399
400module_init(nft_nat_module_init);
401module_exit(nft_nat_module_exit);
402
403MODULE_LICENSE("GPL");
404MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
405MODULE_ALIAS_NFT_EXPR("nat");
406MODULE_DESCRIPTION("Network Address Translation support");
407

source code of linux/net/netfilter/nft_nat.c