1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *
  4 * Generic part shared by ipv4 and ipv6 backends.
  5 */
  6
  7#include <linux/kernel.h>
  8#include <linux/init.h>
  9#include <linux/module.h>
 10#include <linux/netlink.h>
 11#include <linux/netfilter.h>
 12#include <linux/netfilter/nf_tables.h>
 13#include <net/netfilter/nf_tables_core.h>
 14#include <net/netfilter/nf_tables.h>
 15#include <linux/in.h>
 16#include <net/xfrm.h>
 17
 18static const struct nla_policy nft_xfrm_policy[NFTA_XFRM_MAX + 1] = {
 19	[NFTA_XFRM_KEY]		= NLA_POLICY_MAX(NLA_BE32, 255),
 20	[NFTA_XFRM_DIR]		= { .type = NLA_U8 },
 21	[NFTA_XFRM_SPNUM]	= NLA_POLICY_MAX(NLA_BE32, 255),
 22	[NFTA_XFRM_DREG]	= { .type = NLA_U32 },
 23};
 24
 25struct nft_xfrm {
 26	enum nft_xfrm_keys	key:8;
 27	u8			dreg;
 28	u8			dir;
 29	u8			spnum;
 30	u8			len;
 31};
 32
 33static int nft_xfrm_get_init(const struct nft_ctx *ctx,
 34			     const struct nft_expr *expr,
 35			     const struct nlattr * const tb[])
 36{
 37	struct nft_xfrm *priv = nft_expr_priv(expr);
 38	unsigned int len = 0;
 39	u32 spnum = 0;
 40	u8 dir;
 41
 42	if (!tb[NFTA_XFRM_KEY] || !tb[NFTA_XFRM_DIR] || !tb[NFTA_XFRM_DREG])
 43		return -EINVAL;
 44
 45	switch (ctx->family) {
 46	case NFPROTO_IPV4:
 47	case NFPROTO_IPV6:
 48	case NFPROTO_INET:
 49		break;
 50	default:
 51		return -EOPNOTSUPP;
 52	}
 53
 54	priv->key = ntohl(nla_get_be32(tb[NFTA_XFRM_KEY]));
 55	switch (priv->key) {
 56	case NFT_XFRM_KEY_REQID:
 57	case NFT_XFRM_KEY_SPI:
 58		len = sizeof(u32);
 59		break;
 60	case NFT_XFRM_KEY_DADDR_IP4:
 61	case NFT_XFRM_KEY_SADDR_IP4:
 62		len = sizeof(struct in_addr);
 63		break;
 64	case NFT_XFRM_KEY_DADDR_IP6:
 65	case NFT_XFRM_KEY_SADDR_IP6:
 66		len = sizeof(struct in6_addr);
 67		break;
 68	default:
 69		return -EINVAL;
 70	}
 71
 72	dir = nla_get_u8(tb[NFTA_XFRM_DIR]);
 73	switch (dir) {
 74	case XFRM_POLICY_IN:
 75	case XFRM_POLICY_OUT:
 76		priv->dir = dir;
 77		break;
 78	default:
 79		return -EINVAL;
 80	}
 81
 82	if (tb[NFTA_XFRM_SPNUM])
 83		spnum = ntohl(nla_get_be32(tb[NFTA_XFRM_SPNUM]));
 84
 85	if (spnum >= XFRM_MAX_DEPTH)
 86		return -ERANGE;
 87
 88	priv->spnum = spnum;
 89
 90	priv->len = len;
 91	return nft_parse_register_store(ctx, tb[NFTA_XFRM_DREG], &priv->dreg,
 92					NULL, NFT_DATA_VALUE, len);
 93}
 94
 95/* Return true if key asks for daddr/saddr and current
 96 * state does have a valid address (BEET, TUNNEL).
 97 */
 98static bool xfrm_state_addr_ok(enum nft_xfrm_keys k, u8 family, u8 mode)
 99{
100	switch (k) {
101	case NFT_XFRM_KEY_DADDR_IP4:
102	case NFT_XFRM_KEY_SADDR_IP4:
103		if (family == NFPROTO_IPV4)
104			break;
105		return false;
106	case NFT_XFRM_KEY_DADDR_IP6:
107	case NFT_XFRM_KEY_SADDR_IP6:
108		if (family == NFPROTO_IPV6)
109			break;
110		return false;
111	default:
112		return true;
113	}
114
115	return mode == XFRM_MODE_BEET || mode == XFRM_MODE_TUNNEL;
116}
117
118static void nft_xfrm_state_get_key(const struct nft_xfrm *priv,
119				   struct nft_regs *regs,
120				   const struct xfrm_state *state)
121{
122	u32 *dest = &regs->data[priv->dreg];
123
124	if (!xfrm_state_addr_ok(priv->key,
125				state->props.family,
126				state->props.mode)) {
127		regs->verdict.code = NFT_BREAK;
128		return;
129	}
130
131	switch (priv->key) {
132	case NFT_XFRM_KEY_UNSPEC:
133	case __NFT_XFRM_KEY_MAX:
134		WARN_ON_ONCE(1);
135		break;
136	case NFT_XFRM_KEY_DADDR_IP4:
137		*dest = (__force __u32)state->id.daddr.a4;
138		return;
139	case NFT_XFRM_KEY_DADDR_IP6:
140		memcpy(dest, &state->id.daddr.in6, sizeof(struct in6_addr));
141		return;
142	case NFT_XFRM_KEY_SADDR_IP4:
143		*dest = (__force __u32)state->props.saddr.a4;
144		return;
145	case NFT_XFRM_KEY_SADDR_IP6:
146		memcpy(dest, &state->props.saddr.in6, sizeof(struct in6_addr));
147		return;
148	case NFT_XFRM_KEY_REQID:
149		*dest = state->props.reqid;
150		return;
151	case NFT_XFRM_KEY_SPI:
152		*dest = (__force __u32)state->id.spi;
153		return;
154	}
155
156	regs->verdict.code = NFT_BREAK;
157}
158
159static void nft_xfrm_get_eval_in(const struct nft_xfrm *priv,
160				    struct nft_regs *regs,
161				    const struct nft_pktinfo *pkt)
162{
163	const struct sec_path *sp = skb_sec_path(pkt->skb);
164	const struct xfrm_state *state;
165
166	if (sp == NULL || sp->len <= priv->spnum) {
167		regs->verdict.code = NFT_BREAK;
168		return;
169	}
170
171	state = sp->xvec[priv->spnum];
172	nft_xfrm_state_get_key(priv, regs, state);
173}
174
175static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv,
176				  struct nft_regs *regs,
177				  const struct nft_pktinfo *pkt)
178{
179	const struct dst_entry *dst = skb_dst(pkt->skb);
180	int i;
181
182	for (i = 0; dst && dst->xfrm;
183	     dst = ((const struct xfrm_dst *)dst)->child, i++) {
184		if (i < priv->spnum)
185			continue;
186
187		nft_xfrm_state_get_key(priv, regs, dst->xfrm);
188		return;
189	}
190
191	regs->verdict.code = NFT_BREAK;
192}
193
194static void nft_xfrm_get_eval(const struct nft_expr *expr,
195			      struct nft_regs *regs,
196			      const struct nft_pktinfo *pkt)
197{
198	const struct nft_xfrm *priv = nft_expr_priv(expr);
199
200	switch (priv->dir) {
201	case XFRM_POLICY_IN:
202		nft_xfrm_get_eval_in(priv, regs, pkt);
203		break;
204	case XFRM_POLICY_OUT:
205		nft_xfrm_get_eval_out(priv, regs, pkt);
206		break;
207	default:
208		WARN_ON_ONCE(1);
209		regs->verdict.code = NFT_BREAK;
210		break;
211	}
212}
213
214static int nft_xfrm_get_dump(struct sk_buff *skb,
215			     const struct nft_expr *expr, bool reset)
216{
217	const struct nft_xfrm *priv = nft_expr_priv(expr);
218
219	if (nft_dump_register(skb, NFTA_XFRM_DREG, priv->dreg))
220		return -1;
221
222	if (nla_put_be32(skb, NFTA_XFRM_KEY, htonl(priv->key)))
223		return -1;
224	if (nla_put_u8(skb, NFTA_XFRM_DIR, priv->dir))
225		return -1;
226	if (nla_put_be32(skb, NFTA_XFRM_SPNUM, htonl(priv->spnum)))
227		return -1;
228
229	return 0;
230}
231
232static int nft_xfrm_validate(const struct nft_ctx *ctx, const struct nft_expr *expr)
233{
234	const struct nft_xfrm *priv = nft_expr_priv(expr);
235	unsigned int hooks;
236
237	if (ctx->family != NFPROTO_IPV4 &&
238	    ctx->family != NFPROTO_IPV6 &&
239	    ctx->family != NFPROTO_INET)
240		return -EOPNOTSUPP;
241
242	switch (priv->dir) {
243	case XFRM_POLICY_IN:
244		hooks = (1 << NF_INET_FORWARD) |
245			(1 << NF_INET_LOCAL_IN) |
246			(1 << NF_INET_PRE_ROUTING);
247		break;
248	case XFRM_POLICY_OUT:
249		hooks = (1 << NF_INET_FORWARD) |
250			(1 << NF_INET_LOCAL_OUT) |
251			(1 << NF_INET_POST_ROUTING);
252		break;
253	default:
254		WARN_ON_ONCE(1);
255		return -EINVAL;
256	}
257
258	return nft_chain_validate_hooks(ctx->chain, hooks);
259}
260
261static bool nft_xfrm_reduce(struct nft_regs_track *track,
262			    const struct nft_expr *expr)
263{
264	const struct nft_xfrm *priv = nft_expr_priv(expr);
265	const struct nft_xfrm *xfrm;
266
267	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
268		nft_reg_track_update(track, expr, priv->dreg, priv->len);
269		return false;
270	}
271
272	xfrm = nft_expr_priv(track->regs[priv->dreg].selector);
273	if (priv->key != xfrm->key ||
274	    priv->dreg != xfrm->dreg ||
275	    priv->dir != xfrm->dir ||
276	    priv->spnum != xfrm->spnum) {
277		nft_reg_track_update(track, expr, priv->dreg, priv->len);
278		return false;
279	}
280
281	if (!track->regs[priv->dreg].bitwise)
282		return true;
283
284	return nft_expr_reduce_bitwise(track, expr);
285}
286
287static struct nft_expr_type nft_xfrm_type;
288static const struct nft_expr_ops nft_xfrm_get_ops = {
289	.type		= &nft_xfrm_type,
290	.size		= NFT_EXPR_SIZE(sizeof(struct nft_xfrm)),
291	.eval		= nft_xfrm_get_eval,
292	.init		= nft_xfrm_get_init,
293	.dump		= nft_xfrm_get_dump,
294	.validate	= nft_xfrm_validate,
295	.reduce		= nft_xfrm_reduce,
296};
297
298static struct nft_expr_type nft_xfrm_type __read_mostly = {
299	.name		= "xfrm",
300	.ops		= &nft_xfrm_get_ops,
301	.policy		= nft_xfrm_policy,
302	.maxattr	= NFTA_XFRM_MAX,
303	.owner		= THIS_MODULE,
304};
305
306static int __init nft_xfrm_module_init(void)
307{
308	return nft_register_expr(&nft_xfrm_type);
309}
310
311static void __exit nft_xfrm_module_exit(void)
312{
313	nft_unregister_expr(&nft_xfrm_type);
314}
315
316module_init(nft_xfrm_module_init);
317module_exit(nft_xfrm_module_exit);
318
319MODULE_LICENSE("GPL");
320MODULE_DESCRIPTION("nf_tables: xfrm/IPSec matching");
321MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
322MODULE_AUTHOR("Máté Eckl <ecklm94@gmail.com>");
323MODULE_ALIAS_NFT_EXPR("xfrm");