// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2017 Pablo M. Bermudo Garay <pablombg@gmail.com>
 *
 * This code is based on net/netfilter/nft_fib_inet.c, written by
 * Florian Westphal <fw@strlen.de>.
 */

#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/ipv6.h>

#include <net/netfilter/nft_fib.h>

static void nft_fib_netdev_eval(const struct nft_expr *expr,
                                struct nft_regs *regs,
                                const struct nft_pktinfo *pkt)
{
        const struct nft_fib *priv = nft_expr_priv(expr);

        switch (ntohs(pkt->skb->protocol)) {
        case ETH_P_IP:
                switch (priv->result) {
                case NFT_FIB_RESULT_OIF:
                case NFT_FIB_RESULT_OIFNAME:
                        return nft_fib4_eval(expr, regs, pkt);
                case NFT_FIB_RESULT_ADDRTYPE:
                        return nft_fib4_eval_type(expr, regs, pkt);
                }
                break;
        case ETH_P_IPV6:
                if (!ipv6_mod_enabled())
                        break;
                switch (priv->result) {
                case NFT_FIB_RESULT_OIF:
                case NFT_FIB_RESULT_OIFNAME:
                        return nft_fib6_eval(expr, regs, pkt);
                case NFT_FIB_RESULT_ADDRTYPE:
                        return nft_fib6_eval_type(expr, regs, pkt);
                }
                break;
        }

        regs->verdict.code = NFT_BREAK;
}

static int nft_fib_netdev_validate(const struct nft_ctx *ctx,
                                   const struct nft_expr *expr)
{
        const struct nft_fib *priv = nft_expr_priv(expr);
        unsigned int hooks;

        switch (priv->result) {
        case NFT_FIB_RESULT_OIF:
        case NFT_FIB_RESULT_OIFNAME:
                hooks = (1 << NF_NETDEV_INGRESS);
                break;
        case NFT_FIB_RESULT_ADDRTYPE:
                if (priv->flags & NFTA_FIB_F_IIF)
                        hooks = (1 << NF_NETDEV_INGRESS);
                else if (priv->flags & NFTA_FIB_F_OIF)
                        hooks = (1 << NF_NETDEV_EGRESS);
                else
                        hooks = (1 << NF_NETDEV_INGRESS) |
                                (1 << NF_NETDEV_EGRESS);
                break;
        default:
                return -EINVAL;
        }

        return nft_chain_validate_hooks(ctx->chain, hooks);
}

static struct nft_expr_type nft_fib_netdev_type;
static const struct nft_expr_ops nft_fib_netdev_ops = {
        .type           = &nft_fib_netdev_type,
        .size           = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
        .eval           = nft_fib_netdev_eval,
        .init           = nft_fib_init,
        .dump           = nft_fib_dump,
        .validate       = nft_fib_netdev_validate,
};

static struct nft_expr_type nft_fib_netdev_type __read_mostly = {
        .family         = NFPROTO_NETDEV,
        .name           = "fib",
        .ops            = &nft_fib_netdev_ops,
        .policy         = nft_fib_policy,
        .maxattr        = NFTA_FIB_MAX,
        .owner          = THIS_MODULE,
};

static int __init nft_fib_netdev_module_init(void)
{
        return nft_register_expr(&nft_fib_netdev_type);
}

static void __exit nft_fib_netdev_module_exit(void)
{
        nft_unregister_expr(&nft_fib_netdev_type);
}

module_init(nft_fib_netdev_module_init);
module_exit(nft_fib_netdev_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo M. Bermudo Garay <pablombg@gmail.com>");
MODULE_ALIAS_NFT_AF_EXPR(5, "fib");
MODULE_DESCRIPTION("nftables netdev fib lookups support");