nft_masq.c

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