kernel / net / netfilter / nft_lookup.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2009 Patrick McHardy <[e-mail]>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>

struct nft_lookup {
	struct nft_set			*set;
	u8				sreg;
	u8				dreg;
	bool				dreg_set;
	bool				invert;
	struct nft_set_binding		binding;
};

static const struct nft_set_ext *
__nft_set_do_lookup(const struct net *net, const struct nft_set *set,
		    const u32 *key)
{
#ifdef CONFIG_MITIGATION_RETPOLINE
	if (set->ops == &nft_set_hash_fast_type.ops)
		return nft_hash_lookup_fast(net, set, key);
	if (set->ops == &nft_set_hash_type.ops)
		return nft_hash_lookup(net, set, key);

	if (set->ops == &nft_set_rhash_type.ops)
		return nft_rhash_lookup(net, set, key);

	if (set->ops == &nft_set_bitmap_type.ops)
		return nft_bitmap_lookup(net, set, key);

	if (set->ops == &nft_set_pipapo_type.ops)
		return nft_pipapo_lookup(net, set, key);
#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
	if (set->ops == &nft_set_pipapo_avx2_type.ops)
		return nft_pipapo_avx2_lookup(net, set, key);
#endif

	if (set->ops == &nft_set_rbtree_type.ops)
		return nft_rbtree_lookup(net, set, key);

	WARN_ON_ONCE(1);
#endif
	return set->ops->lookup(net, set, key);
}

static unsigned int nft_base_seq(const struct net *net)
{
	/* pairs with smp_store_release() in nf_tables_commit() */
	return smp_load_acquire(&net->nft.base_seq);
}

static bool nft_lookup_should_retry(const struct net *net, unsigned int seq)
{
	return unlikely(seq != nft_base_seq(net));
}

const struct nft_set_ext *
nft_set_do_lookup(const struct net *net, const struct nft_set *set,
		  const u32 *key)
{
	const struct nft_set_ext *ext;
	unsigned int base_seq;

	do {
		base_seq = nft_base_seq(net);

		ext = __nft_set_do_lookup(net, set, key);
		if (ext)
			break;
		/* No match?  There is a small chance that lookup was
		 * performed in the old generation, but nf_tables_commit()
		 * already unlinked a (matching) element.
		 *
		 * We need to repeat the lookup to make sure that we didn't
		 * miss a matching element in the new generation.
		 */
	} while (nft_lookup_should_retry(net, base_seq));

	return ext;
}
EXPORT_SYMBOL_GPL(nft_set_do_lookup);

void nft_lookup_eval(const struct nft_expr *expr,
		     struct nft_regs *regs,
		     const struct nft_pktinfo *pkt)
{
	const struct nft_lookup *priv = nft_expr_priv(expr);
	const struct nft_set *set = priv->set;
	const struct net *net = nft_net(pkt);
	const struct nft_set_ext *ext;
	bool found;

	ext = nft_set_do_lookup(net, set, &regs->data[priv->sreg]);
	found = !!ext ^ priv->invert;
	if (!found) {
		ext = nft_set_catchall_lookup(net, set);
		if (!ext) {
			regs->verdict.code = NFT_BREAK;
			return;
		}
	}

	if (ext) {
		if (priv->dreg_set)
			nft_data_copy(&regs->data[priv->dreg],
				      nft_set_ext_data(ext), set->dlen);

		nft_set_elem_update_expr(ext, regs, pkt);
	}
}

static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
	[NFTA_LOOKUP_SET]	= { .type = NLA_STRING,
				    .len = NFT_SET_MAXNAMELEN - 1 },
	[NFTA_LOOKUP_SET_ID]	= { .type = NLA_U32 },
	[NFTA_LOOKUP_SREG]	= { .type = NLA_U32 },
	[NFTA_LOOKUP_DREG]	= { .type = NLA_U32 },
	[NFTA_LOOKUP_FLAGS]	=
		NLA_POLICY_MASK(NLA_BE32, NFT_LOOKUP_F_INV),
};

static int nft_lookup_init(const struct nft_ctx *ctx,
			   const struct nft_expr *expr,
			   const struct nlattr * const tb[])
{
	struct nft_lookup *priv = nft_expr_priv(expr);
	u8 genmask = nft_genmask_next(ctx->net);
	struct nft_set *set;
	u32 flags;
	int err;

	if (tb[NFTA_LOOKUP_SET] == NULL ||
	    tb[NFTA_LOOKUP_SREG] == NULL)
		return -EINVAL;

	set = nft_set_lookup_global(ctx->net, ctx->table, tb[NFTA_LOOKUP_SET],
				    tb[NFTA_LOOKUP_SET_ID], genmask);
	if (IS_ERR(set))
		return PTR_ERR(set);

	err = nft_parse_register_load(ctx, tb[NFTA_LOOKUP_SREG], &priv->sreg,
				      set->klen);
	if (err < 0)
		return err;

	if (tb[NFTA_LOOKUP_FLAGS]) {
		flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));

		if (flags & NFT_LOOKUP_F_INV)
			priv->invert = true;
	}

	if (tb[NFTA_LOOKUP_DREG] != NULL) {
		if (priv->invert)
			return -EINVAL;
		if (!(set->flags & NFT_SET_MAP))
			return -EINVAL;

		err = nft_parse_register_store(ctx, tb[NFTA_LOOKUP_DREG],
					       &priv->dreg, NULL,
					       nft_set_datatype(set),
					       set->dlen);
		if (err < 0)
			return err;
		priv->dreg_set = true;
	} else if (set->flags & NFT_SET_MAP) {
		/* Map given, but user asks for lookup only (i.e. to
		 * ignore value assoicated with key).
		 *
		 * This makes no sense for anonymous maps since they are
		 * scoped to the rule, but for named sets this can be useful.
		 */
		if (set->flags & NFT_SET_ANONYMOUS)
			return -EINVAL;
	}

	priv->binding.flags = set->flags & NFT_SET_MAP;

	err = nf_tables_bind_set(ctx, set, &priv->binding);
	if (err < 0)
		return err;

	priv->set = set;
	return 0;
}

static void nft_lookup_deactivate(const struct nft_ctx *ctx,
				  const struct nft_expr *expr,
				  enum nft_trans_phase phase)
{
	struct nft_lookup *priv = nft_expr_priv(expr);

	nf_tables_deactivate_set(ctx, priv->set, &priv->binding, phase);
}

static void nft_lookup_activate(const struct nft_ctx *ctx,
				const struct nft_expr *expr)
{
	struct nft_lookup *priv = nft_expr_priv(expr);

	nf_tables_activate_set(ctx, priv->set);
}

static void nft_lookup_destroy(const struct nft_ctx *ctx,
			       const struct nft_expr *expr)
{
	struct nft_lookup *priv = nft_expr_priv(expr);

	nf_tables_destroy_set(ctx, priv->set);
}

static int nft_lookup_dump(struct sk_buff *skb,
			   const struct nft_expr *expr, bool reset)
{
	const struct nft_lookup *priv = nft_expr_priv(expr);
	u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;

	if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
		goto nla_put_failure;
	if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
		goto nla_put_failure;
	if (priv->dreg_set)
		if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
			goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static int nft_lookup_validate(const struct nft_ctx *ctx,
			       const struct nft_expr *expr)
{
	const struct nft_lookup *priv = nft_expr_priv(expr);
	struct nft_set_iter iter = {
		.genmask	= nft_genmask_next(ctx->net),
		.type		= NFT_ITER_UPDATE,
		.fn		= nft_setelem_validate,
	};

	if (!(priv->set->flags & NFT_SET_MAP) ||
	    priv->set->dtype != NFT_DATA_VERDICT)
		return 0;

	priv->set->ops->walk(ctx, priv->set, &iter);
	if (!iter.err)
		iter.err = nft_set_catchall_validate(ctx, priv->set);

	if (iter.err < 0)
		return iter.err;

	return 0;
}

static bool nft_lookup_reduce(struct nft_regs_track *track,
			      const struct nft_expr *expr)
{
	const struct nft_lookup *priv = nft_expr_priv(expr);

	if (priv->set->flags & NFT_SET_MAP)
		nft_reg_track_cancel(track, priv->dreg, priv->set->dlen);

	return false;
}

static const struct nft_expr_ops nft_lookup_ops = {
	.type		= &nft_lookup_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
	.eval		= nft_lookup_eval,
	.init		= nft_lookup_init,
	.activate	= nft_lookup_activate,
	.deactivate	= nft_lookup_deactivate,
	.destroy	= nft_lookup_destroy,
	.dump		= nft_lookup_dump,
	.validate	= nft_lookup_validate,
	.reduce		= nft_lookup_reduce,
};

struct nft_expr_type nft_lookup_type __read_mostly = {
	.name		= "lookup",
	.ops		= &nft_lookup_ops,
	.policy		= nft_lookup_policy,
	.maxattr	= NFTA_LOOKUP_MAX,
	.owner		= THIS_MODULE,
};