nft_lookup.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2009 Patrick McHardy <kaber@trash.net>
  4 *
  5 * Development of this code funded by Astaro AG (http://www.astaro.com/)
  6 */
  7
  8#include <linux/kernel.h>
  9#include <linux/init.h>
 10#include <linux/list.h>
 11#include <linux/rbtree.h>
 12#include <linux/netlink.h>
 13#include <linux/netfilter.h>
 14#include <linux/netfilter/nf_tables.h>
 15#include <net/netfilter/nf_tables.h>
 16#include <net/netfilter/nf_tables_core.h>
 17
 18struct nft_lookup {
 19	struct nft_set			*set;
 20	u8				sreg;
 21	u8				dreg;
 22	bool				dreg_set;
 23	bool				invert;
 24	struct nft_set_binding		binding;
 25};
 26
 27static const struct nft_set_ext *
 28__nft_set_do_lookup(const struct net *net, const struct nft_set *set,
 29		    const u32 *key)
 30{
 31#ifdef CONFIG_MITIGATION_RETPOLINE
 32	if (set->ops == &nft_set_hash_fast_type.ops)
 33		return nft_hash_lookup_fast(net, set, key);
 34	if (set->ops == &nft_set_hash_type.ops)
 35		return nft_hash_lookup(net, set, key);
 36
 37	if (set->ops == &nft_set_rhash_type.ops)
 38		return nft_rhash_lookup(net, set, key);
 39
 40	if (set->ops == &nft_set_bitmap_type.ops)
 41		return nft_bitmap_lookup(net, set, key);
 42
 43	if (set->ops == &nft_set_pipapo_type.ops)
 44		return nft_pipapo_lookup(net, set, key);
 45#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
 46	if (set->ops == &nft_set_pipapo_avx2_type.ops)
 47		return nft_pipapo_avx2_lookup(net, set, key);
 48#endif
 49
 50	if (set->ops == &nft_set_rbtree_type.ops)
 51		return nft_rbtree_lookup(net, set, key);
 52
 53	WARN_ON_ONCE(1);
 54#endif
 55	return set->ops->lookup(net, set, key);
 56}
 57
 58static unsigned int nft_base_seq(const struct net *net)
 59{
 60	/* pairs with smp_store_release() in nf_tables_commit() */
 61	return smp_load_acquire(&net->nft.base_seq);
 62}
 63
 64static bool nft_lookup_should_retry(const struct net *net, unsigned int seq)
 65{
 66	return unlikely(seq != nft_base_seq(net));
 67}
 68
 69const struct nft_set_ext *
 70nft_set_do_lookup(const struct net *net, const struct nft_set *set,
 71		  const u32 *key)
 72{
 73	const struct nft_set_ext *ext;
 74	unsigned int base_seq;
 75
 76	do {
 77		base_seq = nft_base_seq(net);
 78
 79		ext = __nft_set_do_lookup(net, set, key);
 80		if (ext)
 81			break;
 82		/* No match?  There is a small chance that lookup was
 83		 * performed in the old generation, but nf_tables_commit()
 84		 * already unlinked a (matching) element.
 85		 *
 86		 * We need to repeat the lookup to make sure that we didn't
 87		 * miss a matching element in the new generation.
 88		 */
 89	} while (nft_lookup_should_retry(net, base_seq));
 90
 91	return ext;
 92}
 93EXPORT_SYMBOL_GPL(nft_set_do_lookup);
 94
 95void nft_lookup_eval(const struct nft_expr *expr,
 96		     struct nft_regs *regs,
 97		     const struct nft_pktinfo *pkt)
 98{
 99	const struct nft_lookup *priv = nft_expr_priv(expr);
100	const struct nft_set *set = priv->set;
101	const struct net *net = nft_net(pkt);
102	const struct nft_set_ext *ext;
103	bool found;
104
105	ext = nft_set_do_lookup(net, set, &regs->data[priv->sreg]);
106	found = !!ext ^ priv->invert;
107	if (!found) {
108		ext = nft_set_catchall_lookup(net, set);
109		if (!ext) {
110			regs->verdict.code = NFT_BREAK;
111			return;
112		}
113	}
114
115	if (ext) {
116		if (priv->dreg_set)
117			nft_data_copy(&regs->data[priv->dreg],
118				      nft_set_ext_data(ext), set->dlen);
119
120		nft_set_elem_update_expr(ext, regs, pkt);
121	}
122}
123
124static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
125	[NFTA_LOOKUP_SET]	= { .type = NLA_STRING,
126				    .len = NFT_SET_MAXNAMELEN - 1 },
127	[NFTA_LOOKUP_SET_ID]	= { .type = NLA_U32 },
128	[NFTA_LOOKUP_SREG]	= { .type = NLA_U32 },
129	[NFTA_LOOKUP_DREG]	= { .type = NLA_U32 },
130	[NFTA_LOOKUP_FLAGS]	=
131		NLA_POLICY_MASK(NLA_BE32, NFT_LOOKUP_F_INV),
132};
133
134static int nft_lookup_init(const struct nft_ctx *ctx,
135			   const struct nft_expr *expr,
136			   const struct nlattr * const tb[])
137{
138	struct nft_lookup *priv = nft_expr_priv(expr);
139	u8 genmask = nft_genmask_next(ctx->net);
140	struct nft_set *set;
141	u32 flags;
142	int err;
143
144	if (tb[NFTA_LOOKUP_SET] == NULL ||
145	    tb[NFTA_LOOKUP_SREG] == NULL)
146		return -EINVAL;
147
148	set = nft_set_lookup_global(ctx->net, ctx->table, tb[NFTA_LOOKUP_SET],
149				    tb[NFTA_LOOKUP_SET_ID], genmask);
150	if (IS_ERR(set))
151		return PTR_ERR(set);
152
153	err = nft_parse_register_load(ctx, tb[NFTA_LOOKUP_SREG], &priv->sreg,
154				      set->klen);
155	if (err < 0)
156		return err;
157
158	if (tb[NFTA_LOOKUP_FLAGS]) {
159		flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
160
161		if (flags & NFT_LOOKUP_F_INV)
162			priv->invert = true;
163	}
164
165	if (tb[NFTA_LOOKUP_DREG] != NULL) {
166		if (priv->invert)
167			return -EINVAL;
168		if (!(set->flags & NFT_SET_MAP))
169			return -EINVAL;
170
171		err = nft_parse_register_store(ctx, tb[NFTA_LOOKUP_DREG],
172					       &priv->dreg, NULL,
173					       nft_set_datatype(set),
174					       set->dlen);
175		if (err < 0)
176			return err;
177		priv->dreg_set = true;
178	} else if (set->flags & NFT_SET_MAP) {
179		/* Map given, but user asks for lookup only (i.e. to
180		 * ignore value assoicated with key).
181		 *
182		 * This makes no sense for anonymous maps since they are
183		 * scoped to the rule, but for named sets this can be useful.
184		 */
185		if (set->flags & NFT_SET_ANONYMOUS)
186			return -EINVAL;
187	}
188
189	priv->binding.flags = set->flags & NFT_SET_MAP;
190
191	err = nf_tables_bind_set(ctx, set, &priv->binding);
192	if (err < 0)
193		return err;
194
195	priv->set = set;
196	return 0;
197}
198
199static void nft_lookup_deactivate(const struct nft_ctx *ctx,
200				  const struct nft_expr *expr,
201				  enum nft_trans_phase phase)
202{
203	struct nft_lookup *priv = nft_expr_priv(expr);
204
205	nf_tables_deactivate_set(ctx, priv->set, &priv->binding, phase);
206}
207
208static void nft_lookup_activate(const struct nft_ctx *ctx,
209				const struct nft_expr *expr)
210{
211	struct nft_lookup *priv = nft_expr_priv(expr);
212
213	nf_tables_activate_set(ctx, priv->set);
214}
215
216static void nft_lookup_destroy(const struct nft_ctx *ctx,
217			       const struct nft_expr *expr)
218{
219	struct nft_lookup *priv = nft_expr_priv(expr);
220
221	nf_tables_destroy_set(ctx, priv->set);
222}
223
224static int nft_lookup_dump(struct sk_buff *skb,
225			   const struct nft_expr *expr, bool reset)
226{
227	const struct nft_lookup *priv = nft_expr_priv(expr);
228	u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
229
230	if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
231		goto nla_put_failure;
232	if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
233		goto nla_put_failure;
234	if (priv->dreg_set)
235		if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
236			goto nla_put_failure;
237	if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
238		goto nla_put_failure;
239	return 0;
240
241nla_put_failure:
242	return -1;
243}
244
245static int nft_lookup_validate(const struct nft_ctx *ctx,
246			       const struct nft_expr *expr)
247{
248	const struct nft_lookup *priv = nft_expr_priv(expr);
249	struct nft_set_iter iter = {
250		.genmask	= nft_genmask_next(ctx->net),
251		.type		= NFT_ITER_UPDATE,
252		.fn		= nft_setelem_validate,
253	};
254
255	if (!(priv->set->flags & NFT_SET_MAP) ||
256	    priv->set->dtype != NFT_DATA_VERDICT)
257		return 0;
258
259	priv->set->ops->walk(ctx, priv->set, &iter);
260	if (!iter.err)
261		iter.err = nft_set_catchall_validate(ctx, priv->set);
262
263	if (iter.err < 0)
264		return iter.err;
265
266	return 0;
267}
268
269static bool nft_lookup_reduce(struct nft_regs_track *track,
270			      const struct nft_expr *expr)
271{
272	const struct nft_lookup *priv = nft_expr_priv(expr);
273
274	if (priv->set->flags & NFT_SET_MAP)
275		nft_reg_track_cancel(track, priv->dreg, priv->set->dlen);
276
277	return false;
278}
279
280static const struct nft_expr_ops nft_lookup_ops = {
281	.type		= &nft_lookup_type,
282	.size		= NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
283	.eval		= nft_lookup_eval,
284	.init		= nft_lookup_init,
285	.activate	= nft_lookup_activate,
286	.deactivate	= nft_lookup_deactivate,
287	.destroy	= nft_lookup_destroy,
288	.dump		= nft_lookup_dump,
289	.validate	= nft_lookup_validate,
290	.reduce		= nft_lookup_reduce,
291};
292
293struct nft_expr_type nft_lookup_type __read_mostly = {
294	.name		= "lookup",
295	.ops		= &nft_lookup_ops,
296	.policy		= nft_lookup_policy,
297	.maxattr	= NFTA_LOOKUP_MAX,
298	.owner		= THIS_MODULE,
299};