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 const struct nft_data **data)
32{
33 int err;
34
35 err = nft_chain_validate_dependency(chain: ctx->chain, type: NFT_CHAIN_T_NAT);
36 if (err < 0)
37 return err;
38
39 return nft_chain_validate_hooks(chain: ctx->chain,
40 hook_flags: (1 << NF_INET_POST_ROUTING));
41}
42
43static int nft_masq_init(const struct nft_ctx *ctx,
44 const struct nft_expr *expr,
45 const struct nlattr * const tb[])
46{
47 u32 plen = sizeof_field(struct nf_nat_range, min_proto.all);
48 struct nft_masq *priv = nft_expr_priv(expr);
49 int err;
50
51 if (tb[NFTA_MASQ_FLAGS])
52 priv->flags = ntohl(nla_get_be32(tb[NFTA_MASQ_FLAGS]));
53
54 if (tb[NFTA_MASQ_REG_PROTO_MIN]) {
55 err = nft_parse_register_load(attr: tb[NFTA_MASQ_REG_PROTO_MIN],
56 sreg: &priv->sreg_proto_min, len: plen);
57 if (err < 0)
58 return err;
59
60 if (tb[NFTA_MASQ_REG_PROTO_MAX]) {
61 err = nft_parse_register_load(attr: tb[NFTA_MASQ_REG_PROTO_MAX],
62 sreg: &priv->sreg_proto_max,
63 len: plen);
64 if (err < 0)
65 return err;
66 } else {
67 priv->sreg_proto_max = priv->sreg_proto_min;
68 }
69 }
70
71 return nf_ct_netns_get(net: ctx->net, nfproto: ctx->family);
72}
73
74static int nft_masq_dump(struct sk_buff *skb,
75 const struct nft_expr *expr, bool reset)
76{
77 const struct nft_masq *priv = nft_expr_priv(expr);
78
79 if (priv->flags != 0 &&
80 nla_put_be32(skb, attrtype: NFTA_MASQ_FLAGS, htonl(priv->flags)))
81 goto nla_put_failure;
82
83 if (priv->sreg_proto_min) {
84 if (nft_dump_register(skb, attr: NFTA_MASQ_REG_PROTO_MIN,
85 reg: priv->sreg_proto_min) ||
86 nft_dump_register(skb, attr: NFTA_MASQ_REG_PROTO_MAX,
87 reg: priv->sreg_proto_max))
88 goto nla_put_failure;
89 }
90
91 return 0;
92
93nla_put_failure:
94 return -1;
95}
96
97static void nft_masq_eval(const struct nft_expr *expr,
98 struct nft_regs *regs,
99 const struct nft_pktinfo *pkt)
100{
101 const struct nft_masq *priv = nft_expr_priv(expr);
102 struct nf_nat_range2 range;
103
104 memset(&range, 0, sizeof(range));
105 range.flags = priv->flags;
106 if (priv->sreg_proto_min) {
107 range.min_proto.all = (__force __be16)
108 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_min]);
109 range.max_proto.all = (__force __be16)
110 nft_reg_load16(sreg: &regs->data[priv->sreg_proto_max]);
111 }
112
113 switch (nft_pf(pkt)) {
114 case NFPROTO_IPV4:
115 regs->verdict.code = nf_nat_masquerade_ipv4(skb: pkt->skb,
116 hooknum: nft_hook(pkt),
117 range: &range,
118 out: nft_out(pkt));
119 break;
120#ifdef CONFIG_NF_TABLES_IPV6
121 case NFPROTO_IPV6:
122 regs->verdict.code = nf_nat_masquerade_ipv6(skb: pkt->skb, range: &range,
123 out: nft_out(pkt));
124 break;
125#endif
126 default:
127 WARN_ON_ONCE(1);
128 break;
129 }
130}
131
132static void
133nft_masq_ipv4_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
134{
135 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_IPV4);
136}
137
138static struct nft_expr_type nft_masq_ipv4_type;
139static const struct nft_expr_ops nft_masq_ipv4_ops = {
140 .type = &nft_masq_ipv4_type,
141 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
142 .eval = nft_masq_eval,
143 .init = nft_masq_init,
144 .destroy = nft_masq_ipv4_destroy,
145 .dump = nft_masq_dump,
146 .validate = nft_masq_validate,
147 .reduce = NFT_REDUCE_READONLY,
148};
149
150static struct nft_expr_type nft_masq_ipv4_type __read_mostly = {
151 .family = NFPROTO_IPV4,
152 .name = "masq",
153 .ops = &nft_masq_ipv4_ops,
154 .policy = nft_masq_policy,
155 .maxattr = NFTA_MASQ_MAX,
156 .owner = THIS_MODULE,
157};
158
159#ifdef CONFIG_NF_TABLES_IPV6
160static void
161nft_masq_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
162{
163 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_IPV6);
164}
165
166static struct nft_expr_type nft_masq_ipv6_type;
167static const struct nft_expr_ops nft_masq_ipv6_ops = {
168 .type = &nft_masq_ipv6_type,
169 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
170 .eval = nft_masq_eval,
171 .init = nft_masq_init,
172 .destroy = nft_masq_ipv6_destroy,
173 .dump = nft_masq_dump,
174 .validate = nft_masq_validate,
175 .reduce = NFT_REDUCE_READONLY,
176};
177
178static struct nft_expr_type nft_masq_ipv6_type __read_mostly = {
179 .family = NFPROTO_IPV6,
180 .name = "masq",
181 .ops = &nft_masq_ipv6_ops,
182 .policy = nft_masq_policy,
183 .maxattr = NFTA_MASQ_MAX,
184 .owner = THIS_MODULE,
185};
186
187static int __init nft_masq_module_init_ipv6(void)
188{
189 return nft_register_expr(&nft_masq_ipv6_type);
190}
191
192static void nft_masq_module_exit_ipv6(void)
193{
194 nft_unregister_expr(&nft_masq_ipv6_type);
195}
196#else
197static inline int nft_masq_module_init_ipv6(void) { return 0; }
198static inline void nft_masq_module_exit_ipv6(void) {}
199#endif
200
201#ifdef CONFIG_NF_TABLES_INET
202static void
203nft_masq_inet_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
204{
205 nf_ct_netns_put(net: ctx->net, nfproto: NFPROTO_INET);
206}
207
208static struct nft_expr_type nft_masq_inet_type;
209static const struct nft_expr_ops nft_masq_inet_ops = {
210 .type = &nft_masq_inet_type,
211 .size = NFT_EXPR_SIZE(sizeof(struct nft_masq)),
212 .eval = nft_masq_eval,
213 .init = nft_masq_init,
214 .destroy = nft_masq_inet_destroy,
215 .dump = nft_masq_dump,
216 .validate = nft_masq_validate,
217 .reduce = NFT_REDUCE_READONLY,
218};
219
220static struct nft_expr_type nft_masq_inet_type __read_mostly = {
221 .family = NFPROTO_INET,
222 .name = "masq",
223 .ops = &nft_masq_inet_ops,
224 .policy = nft_masq_policy,
225 .maxattr = NFTA_MASQ_MAX,
226 .owner = THIS_MODULE,
227};
228
229static int __init nft_masq_module_init_inet(void)
230{
231 return nft_register_expr(&nft_masq_inet_type);
232}
233
234static void nft_masq_module_exit_inet(void)
235{
236 nft_unregister_expr(&nft_masq_inet_type);
237}
238#else
239static inline int nft_masq_module_init_inet(void) { return 0; }
240static inline void nft_masq_module_exit_inet(void) {}
241#endif
242
243static int __init nft_masq_module_init(void)
244{
245 int ret;
246
247 ret = nft_masq_module_init_ipv6();
248 if (ret < 0)
249 return ret;
250
251 ret = nft_masq_module_init_inet();
252 if (ret < 0) {
253 nft_masq_module_exit_ipv6();
254 return ret;
255 }
256
257 ret = nft_register_expr(&nft_masq_ipv4_type);
258 if (ret < 0) {
259 nft_masq_module_exit_inet();
260 nft_masq_module_exit_ipv6();
261 return ret;
262 }
263
264 ret = nf_nat_masquerade_inet_register_notifiers();
265 if (ret < 0) {
266 nft_masq_module_exit_ipv6();
267 nft_masq_module_exit_inet();
268 nft_unregister_expr(&nft_masq_ipv4_type);
269 return ret;
270 }
271
272 return ret;
273}
274
275static void __exit nft_masq_module_exit(void)
276{
277 nft_masq_module_exit_ipv6();
278 nft_masq_module_exit_inet();
279 nft_unregister_expr(&nft_masq_ipv4_type);
280 nf_nat_masquerade_inet_unregister_notifiers();
281}
282
283module_init(nft_masq_module_init);
284module_exit(nft_masq_module_exit);
285
286MODULE_LICENSE("GPL");
287MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo@debian.org>");
288MODULE_ALIAS_NFT_EXPR("masq");
289MODULE_DESCRIPTION("Netfilter nftables masquerade expression support");
290

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