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(&regs->data[priv->sreg_proto_min]);
59	range->max_proto.all = (__force __be16)
60		nft_reg_load16(&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(pkt->skb, &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, regs, priv);
116		if (priv->flags & NF_NAT_RANGE_NETMAP)
117			nft_nat_setup_netmap(&range, pkt, priv);
118	}
119
120	if (priv->sreg_proto_min)
121		nft_nat_setup_proto(&range, regs, priv);
122
123	range.flags = priv->flags;
124
125	regs->verdict.code = nf_nat_setup_info(ct, &range, 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			    const struct nft_data **data)
142{
143	struct nft_nat *priv = nft_expr_priv(expr);
144	int err;
145
146	if (ctx->family != NFPROTO_IPV4 &&
147	    ctx->family != NFPROTO_IPV6 &&
148	    ctx->family != NFPROTO_INET)
149		return -EOPNOTSUPP;
150
151	err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
152	if (err < 0)
153		return err;
154
155	switch (priv->type) {
156	case NFT_NAT_SNAT:
157		err = nft_chain_validate_hooks(ctx->chain,
158					       (1 << NF_INET_POST_ROUTING) |
159					       (1 << NF_INET_LOCAL_IN));
160		break;
161	case NFT_NAT_DNAT:
162		err = nft_chain_validate_hooks(ctx->chain,
163					       (1 << NF_INET_PRE_ROUTING) |
164					       (1 << NF_INET_LOCAL_OUT));
165		break;
166	}
167
168	return err;
169}
170
171static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
172			const struct nlattr * const tb[])
173{
174	struct nft_nat *priv = nft_expr_priv(expr);
175	unsigned int alen, plen;
176	u32 family;
177	int err;
178
179	if (tb[NFTA_NAT_TYPE] == NULL ||
180	    (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
181	     tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
182		return -EINVAL;
183
184	switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
185	case NFT_NAT_SNAT:
186		priv->type = NF_NAT_MANIP_SRC;
187		break;
188	case NFT_NAT_DNAT:
189		priv->type = NF_NAT_MANIP_DST;
190		break;
191	default:
192		return -EOPNOTSUPP;
193	}
194
195	if (tb[NFTA_NAT_FAMILY] == NULL)
196		return -EINVAL;
197
198	family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
199	if (ctx->family != NFPROTO_INET && ctx->family != family)
200		return -EOPNOTSUPP;
201
202	switch (family) {
203	case NFPROTO_IPV4:
204		alen = sizeof_field(struct nf_nat_range, min_addr.ip);
205		break;
206	case NFPROTO_IPV6:
207		alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
208		break;
209	default:
210		if (tb[NFTA_NAT_REG_ADDR_MIN])
211			return -EAFNOSUPPORT;
212		break;
213	}
214	priv->family = family;
215
216	if (tb[NFTA_NAT_REG_ADDR_MIN]) {
217		err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MIN],
218					      &priv->sreg_addr_min, alen);
219		if (err < 0)
220			return err;
221
222		if (tb[NFTA_NAT_REG_ADDR_MAX]) {
223			err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MAX],
224						      &priv->sreg_addr_max,
225						      alen);
226			if (err < 0)
227				return err;
228		} else {
229			priv->sreg_addr_max = priv->sreg_addr_min;
230		}
231
232		priv->flags |= NF_NAT_RANGE_MAP_IPS;
233	}
234
235	plen = sizeof_field(struct nf_nat_range, min_proto.all);
236	if (tb[NFTA_NAT_REG_PROTO_MIN]) {
237		err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MIN],
238					      &priv->sreg_proto_min, plen);
239		if (err < 0)
240			return err;
241
242		if (tb[NFTA_NAT_REG_PROTO_MAX]) {
243			err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MAX],
244						      &priv->sreg_proto_max,
245						      plen);
246			if (err < 0)
247				return err;
248		} else {
249			priv->sreg_proto_max = priv->sreg_proto_min;
250		}
251
252		priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
253	}
254
255	if (tb[NFTA_NAT_FLAGS])
256		priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
257
258	return nf_ct_netns_get(ctx->net, family);
259}
260
261static int nft_nat_dump(struct sk_buff *skb,
262			const struct nft_expr *expr, bool reset)
263{
264	const struct nft_nat *priv = nft_expr_priv(expr);
265
266	switch (priv->type) {
267	case NF_NAT_MANIP_SRC:
268		if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
269			goto nla_put_failure;
270		break;
271	case NF_NAT_MANIP_DST:
272		if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
273			goto nla_put_failure;
274		break;
275	}
276
277	if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
278		goto nla_put_failure;
279
280	if (priv->sreg_addr_min) {
281		if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
282				      priv->sreg_addr_min) ||
283		    nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
284				      priv->sreg_addr_max))
285			goto nla_put_failure;
286	}
287
288	if (priv->sreg_proto_min) {
289		if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
290				      priv->sreg_proto_min) ||
291		    nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
292				      priv->sreg_proto_max))
293			goto nla_put_failure;
294	}
295
296	if (priv->flags != 0) {
297		if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
298			goto nla_put_failure;
299	}
300
301	return 0;
302
303nla_put_failure:
304	return -1;
305}
306
307static void
308nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
309{
310	const struct nft_nat *priv = nft_expr_priv(expr);
311
312	nf_ct_netns_put(ctx->net, priv->family);
313}
314
315static struct nft_expr_type nft_nat_type;
316static const struct nft_expr_ops nft_nat_ops = {
317	.type           = &nft_nat_type,
318	.size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
319	.eval           = nft_nat_eval,
320	.init           = nft_nat_init,
321	.destroy        = nft_nat_destroy,
322	.dump           = nft_nat_dump,
323	.validate	= nft_nat_validate,
324	.reduce		= NFT_REDUCE_READONLY,
325};
326
327static struct nft_expr_type nft_nat_type __read_mostly = {
328	.name           = "nat",
329	.ops            = &nft_nat_ops,
330	.policy         = nft_nat_policy,
331	.maxattr        = NFTA_NAT_MAX,
332	.owner          = THIS_MODULE,
333};
334
335#ifdef CONFIG_NF_TABLES_INET
336static void nft_nat_inet_eval(const struct nft_expr *expr,
337			      struct nft_regs *regs,
338			      const struct nft_pktinfo *pkt)
339{
340	const struct nft_nat *priv = nft_expr_priv(expr);
341
342	if (priv->family == nft_pf(pkt) ||
343	    priv->family == NFPROTO_INET)
344		nft_nat_eval(expr, regs, pkt);
345}
346
347static const struct nft_expr_ops nft_nat_inet_ops = {
348	.type           = &nft_nat_type,
349	.size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
350	.eval           = nft_nat_inet_eval,
351	.init           = nft_nat_init,
352	.destroy        = nft_nat_destroy,
353	.dump           = nft_nat_dump,
354	.validate	= nft_nat_validate,
355	.reduce		= NFT_REDUCE_READONLY,
356};
357
358static struct nft_expr_type nft_inet_nat_type __read_mostly = {
359	.name           = "nat",
360	.family		= NFPROTO_INET,
361	.ops            = &nft_nat_inet_ops,
362	.policy         = nft_nat_policy,
363	.maxattr        = NFTA_NAT_MAX,
364	.owner          = THIS_MODULE,
365};
366
367static int nft_nat_inet_module_init(void)
368{
369	return nft_register_expr(&nft_inet_nat_type);
370}
371
372static void nft_nat_inet_module_exit(void)
373{
374	nft_unregister_expr(&nft_inet_nat_type);
375}
376#else
377static int nft_nat_inet_module_init(void) { return 0; }
378static void nft_nat_inet_module_exit(void) { }
379#endif
380
381static int __init nft_nat_module_init(void)
382{
383	int ret = nft_nat_inet_module_init();
384
385	if (ret)
386		return ret;
387
388	ret = nft_register_expr(&nft_nat_type);
389	if (ret)
390		nft_nat_inet_module_exit();
391
392	return ret;
393}
394
395static void __exit nft_nat_module_exit(void)
396{
397	nft_nat_inet_module_exit();
398	nft_unregister_expr(&nft_nat_type);
399}
400
401module_init(nft_nat_module_init);
402module_exit(nft_nat_module_exit);
403
404MODULE_LICENSE("GPL");
405MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
406MODULE_ALIAS_NFT_EXPR("nat");
407MODULE_DESCRIPTION("Network Address Translation support");
408