// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
 */

#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>

struct nft_range_expr {
        struct nft_data         data_from;
        struct nft_data         data_to;
        u8                      sreg;
        u8                      len;
        enum nft_range_ops      op:8;
};

void nft_range_eval(const struct nft_expr *expr,
                    struct nft_regs *regs, const struct nft_pktinfo *pkt)
{
        const struct nft_range_expr *priv = nft_expr_priv(expr);
        int d1, d2;

        d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
        d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);
        switch (priv->op) {
        case NFT_RANGE_EQ:
                if (d1 < 0 || d2 > 0)
                        regs->verdict.code = NFT_BREAK;
                break;
        case NFT_RANGE_NEQ:
                if (d1 >= 0 && d2 <= 0)
                        regs->verdict.code = NFT_BREAK;
                break;
        }
}

static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {
        [NFTA_RANGE_SREG]               = { .type = NLA_U32 },
        [NFTA_RANGE_OP]                 = NLA_POLICY_MAX(NLA_BE32, 255),
        [NFTA_RANGE_FROM_DATA]          = { .type = NLA_NESTED },
        [NFTA_RANGE_TO_DATA]            = { .type = NLA_NESTED },
};

static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
                        const struct nlattr * const tb[])
{
        struct nft_range_expr *priv = nft_expr_priv(expr);
        struct nft_data_desc desc_from = {
                .type   = NFT_DATA_VALUE,
                .size   = sizeof(priv->data_from),
        };
        struct nft_data_desc desc_to = {
                .type   = NFT_DATA_VALUE,
                .size   = sizeof(priv->data_to),
        };
        int err;
        u32 op;

        if (!tb[NFTA_RANGE_SREG]      ||
            !tb[NFTA_RANGE_OP]        ||
            !tb[NFTA_RANGE_FROM_DATA] ||
            !tb[NFTA_RANGE_TO_DATA])
                return -EINVAL;

        err = nft_data_init(NULL, &priv->data_from, &desc_from,
                            tb[NFTA_RANGE_FROM_DATA]);
        if (err < 0)
                return err;

        err = nft_data_init(NULL, &priv->data_to, &desc_to,
                            tb[NFTA_RANGE_TO_DATA]);
        if (err < 0)
                goto err1;

        if (desc_from.len != desc_to.len) {
                err = -EINVAL;
                goto err2;
        }

        err = nft_parse_register_load(ctx, tb[NFTA_RANGE_SREG], &priv->sreg,
                                      desc_from.len);
        if (err < 0)
                goto err2;

        err = nft_parse_u32_check(tb[NFTA_RANGE_OP], U8_MAX, &op);
        if (err < 0)
                goto err2;

        switch (op) {
        case NFT_RANGE_EQ:
        case NFT_RANGE_NEQ:
                break;
        default:
                err = -EINVAL;
                goto err2;
        }

        priv->op  = op;
        priv->len = desc_from.len;
        return 0;
err2:
        nft_data_release(&priv->data_to, desc_to.type);
err1:
        nft_data_release(&priv->data_from, desc_from.type);
        return err;
}

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

        if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg))
                goto nla_put_failure;
        if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))
                goto nla_put_failure;

        if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,
                          NFT_DATA_VALUE, priv->len) < 0 ||
            nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,
                          NFT_DATA_VALUE, priv->len) < 0)
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -1;
}

static const struct nft_expr_ops nft_range_ops = {
        .type           = &nft_range_type,
        .size           = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),
        .eval           = nft_range_eval,
        .init           = nft_range_init,
        .dump           = nft_range_dump,
        .reduce         = NFT_REDUCE_READONLY,
};

struct nft_expr_type nft_range_type __read_mostly = {
        .name           = "range",
        .ops            = &nft_range_ops,
        .policy         = nft_range_policy,
        .maxattr        = NFTA_RANGE_MAX,
        .owner          = THIS_MODULE,
};