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(ctx->chain, NFT_CHAIN_T_NAT);
36	if (err < 0)
37		return err;
38
39	return nft_chain_validate_hooks(ctx->chain,
40				        (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(tb[NFTA_MASQ_REG_PROTO_MIN],
56					      &priv->sreg_proto_min, plen);
57		if (err < 0)
58			return err;
59
60		if (tb[NFTA_MASQ_REG_PROTO_MAX]) {
61			err = nft_parse_register_load(tb[NFTA_MASQ_REG_PROTO_MAX],
62						      &priv->sreg_proto_max,
63						      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(ctx->net, 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, NFTA_MASQ_FLAGS, htonl(priv->flags)))
81		goto nla_put_failure;
82
83	if (priv->sreg_proto_min) {
84		if (nft_dump_register(skb, NFTA_MASQ_REG_PROTO_MIN,
85				      priv->sreg_proto_min) ||
86		    nft_dump_register(skb, NFTA_MASQ_REG_PROTO_MAX,
87				      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(&regs->data[priv->sreg_proto_min]);
109		range.max_proto.all = (__force __be16)
110			nft_reg_load16(&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(pkt->skb,
116							    nft_hook(pkt),
117							    &range,
118							    nft_out(pkt));
119		break;
120#ifdef CONFIG_NF_TABLES_IPV6
121	case NFPROTO_IPV6:
122		regs->verdict.code = nf_nat_masquerade_ipv6(pkt->skb, &range,
123							    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(ctx->net, 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(ctx->net, 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(ctx->net, 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