1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2014 Arturo Borrero Gonzalez <arturo@debian.org>
4 */
5
6#include <linux/kernel.h>
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/netlink.h>
10#include <linux/netfilter.h>
11#include <linux/netfilter/nf_tables.h>
12#include <net/netfilter/nf_tables.h>
13#include <net/netfilter/nf_nat.h>
14#include <net/netfilter/nf_nat_masquerade.h>
15
16struct nft_masq {
17 u32 flags;
18 u8 sreg_proto_min;
19 u8 sreg_proto_max;
20};
21
22static const struct nla_policy nft_masq_policy[NFTA_MASQ_MAX + 1] = {
23 [NFTA_MASQ_FLAGS] =
24 NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
25 [NFTA_MASQ_REG_PROTO_MIN] = { .type = NLA_U32 },
26 [NFTA_MASQ_REG_PROTO_MAX] = { .type = NLA_U32 },
27};
28
29static int nft_masq_validate(const struct nft_ctx *ctx,
30 const struct nft_expr *expr)
31{
32 int err;
33
34 err = nft_chain_validate_dependency(chain: ctx->chain, type: NFT_CHAIN_T_NAT);
35 if (err < 0)
36 return err;
37
38 return nft_chain_validate_hooks(chain: ctx->chain,
39 hook_flags: (1 << NF_INET_POST_ROUTING));
40}
41
42static int nft_masq_init(const struct nft_ctx *ctx,
43 const struct nft_expr *expr,
44 const struct nlattr * const tb[])
45{
46 u32 plen = sizeof_field(struct nf_nat_range, min_proto.all);
47 struct nft_masq *priv = nft_expr_priv(expr);
48 int err;
49
50 if (tb[NFTA_MASQ_FLAGS])
51 priv->flags = ntohl(nla_get_be32(tb[NFTA_MASQ_FLAGS]));
52
53 if (tb[NFTA_MASQ_REG_PROTO_MIN]) {
54 err = nft_parse_register_load(ctx, attr: tb[NFTA_MASQ_REG_PROTO_MIN],
55 sreg: &priv->sreg_proto_min, len: plen);
56 if (err < 0)
57 return err;
58
59 if (tb[NFTA_MASQ_REG_PROTO_MAX]) {
60 err = nft_parse_register_load(ctx, attr: tb[NFTA_MASQ_REG_PROTO_MAX],
61 sreg: &priv->sreg_proto_max,
62 len: plen);
63 if (err < 0)
64 return err;
65 } else {
66 priv->sreg_proto_max = priv->sreg_proto_min;
67 }
68 }
69
70 return nf_ct_netns_get(net: ctx->net, nfproto: ctx->family);
71}
72
73static int nft_masq_dump(struct sk_buff *skb,
74 const struct nft_expr *expr, bool reset)
75{
76 const struct nft_masq *priv = nft_expr_priv(expr);
77
78 if (priv->flags != 0 &&
79 nla_put_be32(skb, attrtype: NFTA_MASQ_FLAGS, htonl(priv->flags)))
80 goto nla_put_failure;
81
82 if (priv->sreg_proto_min) {
83 if (nft_dump_register(skb, attr: NFTA_MASQ_REG_PROTO_MIN,
84 reg: priv->sreg_proto_min) ||
85 nft_dump_register(skb, attr: NFTA_MASQ_REG_PROTO_MAX,
86 reg: priv->sreg_proto_max))
87 goto nla_put_failure;
88 }
89
90 return 0;
91
92nla_put_failure:
93 return -1;
94}
95
96static void nft_masq_eval(const struct nft_expr *expr,
97 struct nft_regs *regs,
98 const struct nft_pktinfo *pkt)
99{
100 const struct nft_masq *priv = nft_expr_priv(expr);
101 struct nf_nat_range2 range;
102
103 memset(&range, 0, sizeof(range));
104 range.flags = priv->flags;
105 if (priv->sreg_proto_min) {
106 range.min_proto.all = (__force __be16)
107 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_min]);
108 range.max_proto.all = (__force __be16)
109 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_max]);
110 }
111
112 switch (nft_pf(pkt)) {
113 case NFPROTO_IPV4:
114 regs->verdict.code = nf_nat_masquerade_ipv4(skb: pkt->skb,
115 hooknum: nft_hook(pkt),
116 range: &range,
117 out: nft_out(pkt));
118 break;
119#ifdef CONFIG_NF_TABLES_IPV6
120 case NFPROTO_IPV6:
121 regs->verdict.code = nf_nat_masquerade_ipv6(skb: pkt->skb, range: &range,
122 out: nft_out(pkt));
123 break;
124#endif
125 default:
126 WARN_ON_ONCE(1);
127 break;
128 }
129}
130
131static void
132nft_masq_ipv4_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
133{
134 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_IPV4);
135}
136
137static struct nft_expr_type nft_masq_ipv4_type;
138static const struct nft_expr_ops nft_masq_ipv4_ops = {
139 .type = &nft_masq_ipv4_type,
140 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
141 .eval = nft_masq_eval,
142 .init = nft_masq_init,
143 .destroy = nft_masq_ipv4_destroy,
144 .dump = nft_masq_dump,
145 .validate = nft_masq_validate,
146 .reduce = NFT_REDUCE_READONLY,
147};
148
149static struct nft_expr_type nft_masq_ipv4_type __read_mostly = {
150 .family = NFPROTO_IPV4,
151 .name = "masq",
152 .ops = &nft_masq_ipv4_ops,
153 .policy = nft_masq_policy,
154 .maxattr = NFTA_MASQ_MAX,
155 .owner = THIS_MODULE,
156};
157
158#ifdef CONFIG_NF_TABLES_IPV6
159static void
160nft_masq_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
161{
162 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_IPV6);
163}
164
165static struct nft_expr_type nft_masq_ipv6_type;
166static const struct nft_expr_ops nft_masq_ipv6_ops = {
167 .type = &nft_masq_ipv6_type,
168 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
169 .eval = nft_masq_eval,
170 .init = nft_masq_init,
171 .destroy = nft_masq_ipv6_destroy,
172 .dump = nft_masq_dump,
173 .validate = nft_masq_validate,
174 .reduce = NFT_REDUCE_READONLY,
175};
176
177static struct nft_expr_type nft_masq_ipv6_type __read_mostly = {
178 .family = NFPROTO_IPV6,
179 .name = "masq",
180 .ops = &nft_masq_ipv6_ops,
181 .policy = nft_masq_policy,
182 .maxattr = NFTA_MASQ_MAX,
183 .owner = THIS_MODULE,
184};
185
186static int __init nft_masq_module_init_ipv6(void)
187{
188 return nft_register_expr(&nft_masq_ipv6_type);
189}
190
191static void nft_masq_module_exit_ipv6(void)
192{
193 nft_unregister_expr(&nft_masq_ipv6_type);
194}
195#else
196static inline int nft_masq_module_init_ipv6(void) { return 0; }
197static inline void nft_masq_module_exit_ipv6(void) {}
198#endif
199
200#ifdef CONFIG_NF_TABLES_INET
201static void
202nft_masq_inet_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
203{
204 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_INET);
205}
206
207static struct nft_expr_type nft_masq_inet_type;
208static const struct nft_expr_ops nft_masq_inet_ops = {
209 .type = &nft_masq_inet_type,
210 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
211 .eval = nft_masq_eval,
212 .init = nft_masq_init,
213 .destroy = nft_masq_inet_destroy,
214 .dump = nft_masq_dump,
215 .validate = nft_masq_validate,
216 .reduce = NFT_REDUCE_READONLY,
217};
218
219static struct nft_expr_type nft_masq_inet_type __read_mostly = {
220 .family = NFPROTO_INET,
221 .name = "masq",
222 .ops = &nft_masq_inet_ops,
223 .policy = nft_masq_policy,
224 .maxattr = NFTA_MASQ_MAX,
225 .owner = THIS_MODULE,
226};
227
228static int __init nft_masq_module_init_inet(void)
229{
230 return nft_register_expr(&nft_masq_inet_type);
231}
232
233static void nft_masq_module_exit_inet(void)
234{
235 nft_unregister_expr(&nft_masq_inet_type);
236}
237#else
238static inline int nft_masq_module_init_inet(void) { return 0; }
239static inline void nft_masq_module_exit_inet(void) {}
240#endif
241
242static int __init nft_masq_module_init(void)
243{
244 int ret;
245
246 ret = nft_masq_module_init_ipv6();
247 if (ret < 0)
248 return ret;
249
250 ret = nft_masq_module_init_inet();
251 if (ret < 0) {
252 nft_masq_module_exit_ipv6();
253 return ret;
254 }
255
256 ret = nft_register_expr(&nft_masq_ipv4_type);
257 if (ret < 0) {
258 nft_masq_module_exit_inet();
259 nft_masq_module_exit_ipv6();
260 return ret;
261 }
262
263 ret = nf_nat_masquerade_inet_register_notifiers();
264 if (ret < 0) {
265 nft_masq_module_exit_ipv6();
266 nft_masq_module_exit_inet();
267 nft_unregister_expr(&nft_masq_ipv4_type);
268 return ret;
269 }
270
271 return ret;
272}
273
274static void __exit nft_masq_module_exit(void)
275{
276 nft_masq_module_exit_ipv6();
277 nft_masq_module_exit_inet();
278 nft_unregister_expr(&nft_masq_ipv4_type);
279 nf_nat_masquerade_inet_unregister_notifiers();
280}
281
282module_init(nft_masq_module_init);
283module_exit(nft_masq_module_exit);
284
285MODULE_LICENSE("GPL");
286MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo@debian.org>");
287MODULE_ALIAS_NFT_EXPR("masq");
288MODULE_DESCRIPTION("Netfilter nftables masquerade expression support");
289

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