linux/net/netfilter/nft_immediate.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_offload.h>

void nft_immediate_eval(const struct nft_expr *expr,
			struct nft_regs *regs,
			const struct nft_pktinfo *pkt)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);

	nft_data_copy(&regs->data[priv->dreg], &priv->data, priv->dlen);
}

static const struct nla_policy nft_immediate_policy[NFTA_IMMEDIATE_MAX + 1] = {
	[NFTA_IMMEDIATE_DREG]	= { .type = NLA_U32 },
	[NFTA_IMMEDIATE_DATA]	= { .type = NLA_NESTED },
};

static enum nft_data_types nft_reg_to_type(const struct nlattr *nla)
{
	enum nft_data_types type;
	u8 reg;

	reg = ntohl(nla_get_be32(nla));
	if (reg == NFT_REG_VERDICT)
		type = NFT_DATA_VERDICT;
	else
		type = NFT_DATA_VALUE;

	return type;
}

static int nft_immediate_init(const struct nft_ctx *ctx,
			      const struct nft_expr *expr,
			      const struct nlattr * const tb[])
{
	struct nft_immediate_expr *priv = nft_expr_priv(expr);
	struct nft_data_desc desc = {
		.size	= sizeof(priv->data),
	};
	int err;

	if (tb[NFTA_IMMEDIATE_DREG] == NULL ||
	    tb[NFTA_IMMEDIATE_DATA] == NULL)
		return -EINVAL;

	desc.type = nft_reg_to_type(tb[NFTA_IMMEDIATE_DREG]);
	err = nft_data_init(ctx, &priv->data, &desc, tb[NFTA_IMMEDIATE_DATA]);
	if (err < 0)
		return err;

	priv->dlen = desc.len;

	err = nft_parse_register_store(ctx, tb[NFTA_IMMEDIATE_DREG],
				       &priv->dreg, &priv->data, desc.type,
				       desc.len);
	if (err < 0)
		goto err1;

	if (priv->dreg == NFT_REG_VERDICT) {
		struct nft_chain *chain = priv->data.verdict.chain;

		switch (priv->data.verdict.code) {
		case NFT_JUMP:
		case NFT_GOTO:
			err = nf_tables_bind_chain(ctx, chain);
			if (err < 0)
				return err;
			break;
		default:
			break;
		}
	}

	return 0;

err1:
	nft_data_release(&priv->data, desc.type);
	return err;
}

static void nft_immediate_activate(const struct nft_ctx *ctx,
				   const struct nft_expr *expr)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);
	const struct nft_data *data = &priv->data;
	struct nft_ctx chain_ctx;
	struct nft_chain *chain;
	struct nft_rule *rule;

	if (priv->dreg == NFT_REG_VERDICT) {
		switch (data->verdict.code) {
		case NFT_JUMP:
		case NFT_GOTO:
			chain = data->verdict.chain;
			if (!nft_chain_binding(chain))
				break;

			chain_ctx = *ctx;
			chain_ctx.chain = chain;

			list_for_each_entry(rule, &chain->rules, list)
				nft_rule_expr_activate(&chain_ctx, rule);

			nft_clear(ctx->net, chain);
			break;
		default:
			break;
		}
	}

	return nft_data_hold(&priv->data, nft_dreg_to_type(priv->dreg));
}

static void nft_immediate_chain_deactivate(const struct nft_ctx *ctx,
					   struct nft_chain *chain,
					   enum nft_trans_phase phase)
{
	struct nft_ctx chain_ctx;
	struct nft_rule *rule;

	chain_ctx = *ctx;
	chain_ctx.chain = chain;

	list_for_each_entry(rule, &chain->rules, list)
		nft_rule_expr_deactivate(&chain_ctx, rule, phase);
}

static void nft_immediate_deactivate(const struct nft_ctx *ctx,
				     const struct nft_expr *expr,
				     enum nft_trans_phase phase)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);
	const struct nft_data *data = &priv->data;
	struct nft_chain *chain;

	if (priv->dreg == NFT_REG_VERDICT) {
		switch (data->verdict.code) {
		case NFT_JUMP:
		case NFT_GOTO:
			chain = data->verdict.chain;
			if (!nft_chain_binding(chain))
				break;

			switch (phase) {
			case NFT_TRANS_PREPARE_ERROR:
				nf_tables_unbind_chain(ctx, chain);
				nft_deactivate_next(ctx->net, chain);
				break;
			case NFT_TRANS_PREPARE:
				nft_immediate_chain_deactivate(ctx, chain, phase);
				nft_deactivate_next(ctx->net, chain);
				break;
			default:
				nft_immediate_chain_deactivate(ctx, chain, phase);
				nft_chain_del(chain);
				chain->bound = false;
				nft_use_dec(&chain->table->use);
				break;
			}
			break;
		default:
			break;
		}
	}

	if (phase == NFT_TRANS_COMMIT)
		return;

	return nft_data_release(&priv->data, nft_dreg_to_type(priv->dreg));
}

static void nft_immediate_destroy(const struct nft_ctx *ctx,
				  const struct nft_expr *expr)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);
	const struct nft_data *data = &priv->data;
	struct nft_rule *rule, *n;
	struct nft_ctx chain_ctx;
	struct nft_chain *chain;

	if (priv->dreg != NFT_REG_VERDICT)
		return;

	switch (data->verdict.code) {
	case NFT_JUMP:
	case NFT_GOTO:
		chain = data->verdict.chain;

		if (!nft_chain_binding(chain))
			break;

		/* Rule construction failed, but chain is already bound:
		 * let the transaction records release this chain and its rules.
		 */
		if (chain->bound) {
			nft_use_dec(&chain->use);
			break;
		}

		/* Rule has been deleted, release chain and its rules. */
		chain_ctx = *ctx;
		chain_ctx.chain = chain;

		nft_use_dec(&chain->use);
		list_for_each_entry_safe(rule, n, &chain->rules, list) {
			nft_use_dec(&chain->use);
			list_del(&rule->list);
			nf_tables_rule_destroy(&chain_ctx, rule);
		}
		nf_tables_chain_destroy(&chain_ctx);
		break;
	default:
		break;
	}
}

static int nft_immediate_dump(struct sk_buff *skb,
			      const struct nft_expr *expr, bool reset)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_IMMEDIATE_DREG, priv->dreg))
		goto nla_put_failure;

	return nft_data_dump(skb, NFTA_IMMEDIATE_DATA, &priv->data,
			     nft_dreg_to_type(priv->dreg), priv->dlen);

nla_put_failure:
	return -1;
}

static int nft_immediate_validate(const struct nft_ctx *ctx,
				  const struct nft_expr *expr,
				  const struct nft_data **d)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);
	struct nft_ctx *pctx = (struct nft_ctx *)ctx;
	const struct nft_data *data;
	int err;

	if (priv->dreg != NFT_REG_VERDICT)
		return 0;

	data = &priv->data;

	switch (data->verdict.code) {
	case NFT_JUMP:
	case NFT_GOTO:
		pctx->level++;
		err = nft_chain_validate(ctx, data->verdict.chain);
		if (err < 0)
			return err;
		pctx->level--;
		break;
	default:
		break;
	}

	return 0;
}

static int nft_immediate_offload_verdict(struct nft_offload_ctx *ctx,
					 struct nft_flow_rule *flow,
					 const struct nft_immediate_expr *priv)
{
	struct flow_action_entry *entry;
	const struct nft_data *data;

	entry = &flow->rule->action.entries[ctx->num_actions++];

	data = &priv->data;
	switch (data->verdict.code) {
	case NF_ACCEPT:
		entry->id = FLOW_ACTION_ACCEPT;
		break;
	case NF_DROP:
		entry->id = FLOW_ACTION_DROP;
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int nft_immediate_offload(struct nft_offload_ctx *ctx,
				 struct nft_flow_rule *flow,
				 const struct nft_expr *expr)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);

	if (priv->dreg == NFT_REG_VERDICT)
		return nft_immediate_offload_verdict(ctx, flow, priv);

	memcpy(&ctx->regs[priv->dreg].data, &priv->data, sizeof(priv->data));

	return 0;
}

static bool nft_immediate_offload_action(const struct nft_expr *expr)
{
	const struct nft_immediate_expr *priv = nft_expr_priv(expr);

	if (priv->dreg == NFT_REG_VERDICT)
		return true;

	return false;
}

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

	if (priv->dreg != NFT_REG_VERDICT)
		nft_reg_track_cancel(track, priv->dreg, priv->dlen);

	return false;
}

static const struct nft_expr_ops nft_imm_ops = {
	.type		= &nft_imm_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_immediate_expr)),
	.eval		= nft_immediate_eval,
	.init		= nft_immediate_init,
	.activate	= nft_immediate_activate,
	.deactivate	= nft_immediate_deactivate,
	.destroy	= nft_immediate_destroy,
	.dump		= nft_immediate_dump,
	.validate	= nft_immediate_validate,
	.reduce		= nft_immediate_reduce,
	.offload	= nft_immediate_offload,
	.offload_action	= nft_immediate_offload_action,
};

struct nft_expr_type nft_imm_type __read_mostly = {
	.name		= "immediate",
	.ops		= &nft_imm_ops,
	.policy		= nft_immediate_policy,
	.maxattr	= NFTA_IMMEDIATE_MAX,
	.owner		= THIS_MODULE,
};