// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Generic part shared by ipv4 and ipv6 backends.
 */

#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/nft_fib.h>

#define NFTA_FIB_F_ALL (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR | \
                        NFTA_FIB_F_MARK | NFTA_FIB_F_IIF | NFTA_FIB_F_OIF | \
                        NFTA_FIB_F_PRESENT)

const struct nla_policy nft_fib_policy[NFTA_FIB_MAX + 1] = {
        [NFTA_FIB_DREG]         = { .type = NLA_U32 },
        [NFTA_FIB_RESULT]       = { .type = NLA_U32 },
        [NFTA_FIB_FLAGS]        =
                NLA_POLICY_MASK(NLA_BE32, NFTA_FIB_F_ALL),
};
EXPORT_SYMBOL(nft_fib_policy);

int nft_fib_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_INET_PRE_ROUTING) |
                        (1 << NF_INET_LOCAL_IN) |
                        (1 << NF_INET_FORWARD);
                break;
        case NFT_FIB_RESULT_ADDRTYPE:
                if (priv->flags & NFTA_FIB_F_IIF)
                        hooks = (1 << NF_INET_PRE_ROUTING) |
                                (1 << NF_INET_LOCAL_IN) |
                                (1 << NF_INET_FORWARD);
                else if (priv->flags & NFTA_FIB_F_OIF)
                        hooks = (1 << NF_INET_LOCAL_OUT) |
                                (1 << NF_INET_POST_ROUTING) |
                                (1 << NF_INET_FORWARD);
                else
                        hooks = (1 << NF_INET_LOCAL_IN) |
                                (1 << NF_INET_LOCAL_OUT) |
                                (1 << NF_INET_FORWARD) |
                                (1 << NF_INET_PRE_ROUTING) |
                                (1 << NF_INET_POST_ROUTING);

                break;
        default:
                return -EINVAL;
        }

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

int nft_fib_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
                 const struct nlattr * const tb[])
{
        struct nft_fib *priv = nft_expr_priv(expr);
        unsigned int len;
        int err;

        if (!tb[NFTA_FIB_DREG] || !tb[NFTA_FIB_RESULT] || !tb[NFTA_FIB_FLAGS])
                return -EINVAL;

        priv->flags = ntohl(nla_get_be32(tb[NFTA_FIB_FLAGS]));

        if (priv->flags == 0)
                return -EINVAL;

        if ((priv->flags & (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR)) ==
                           (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR))
                return -EINVAL;
        if ((priv->flags & (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF)) ==
                           (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF))
                return -EINVAL;
        if ((priv->flags & (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR)) == 0)
                return -EINVAL;

        priv->result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));

        switch (priv->result) {
        case NFT_FIB_RESULT_OIF:
                if (priv->flags & NFTA_FIB_F_OIF)
                        return -EINVAL;
                len = sizeof(int);
                break;
        case NFT_FIB_RESULT_OIFNAME:
                if (priv->flags & NFTA_FIB_F_OIF)
                        return -EINVAL;
                len = IFNAMSIZ;
                break;
        case NFT_FIB_RESULT_ADDRTYPE:
                len = sizeof(u32);
                break;
        default:
                return -EINVAL;
        }

        err = nft_parse_register_store(ctx, tb[NFTA_FIB_DREG], &priv->dreg,
                                       NULL, NFT_DATA_VALUE, len);
        if (err < 0)
                return err;

        return 0;
}
EXPORT_SYMBOL_GPL(nft_fib_init);

int nft_fib_dump(struct sk_buff *skb, const struct nft_expr *expr, bool reset)
{
        const struct nft_fib *priv = nft_expr_priv(expr);

        if (nft_dump_register(skb, NFTA_FIB_DREG, priv->dreg))
                return -1;

        if (nla_put_be32(skb, NFTA_FIB_RESULT, htonl(priv->result)))
                return -1;

        if (nla_put_be32(skb, NFTA_FIB_FLAGS, htonl(priv->flags)))
                return -1;

        return 0;
}
EXPORT_SYMBOL_GPL(nft_fib_dump);

void nft_fib_store_result(void *reg, const struct nft_fib *priv,
                          const struct net_device *dev)
{
        u32 *dreg = reg;
        int index;

        switch (priv->result) {
        case NFT_FIB_RESULT_OIF:
                index = dev ? dev->ifindex : 0;
                if (priv->flags & NFTA_FIB_F_PRESENT)
                        nft_reg_store8(dreg, !!index);
                else
                        *dreg = index;

                break;
        case NFT_FIB_RESULT_OIFNAME:
                if (priv->flags & NFTA_FIB_F_PRESENT)
                        nft_reg_store8(dreg, !!dev);
                else
                        strscpy_pad(reg, dev ? dev->name : "", IFNAMSIZ);
                break;
        default:
                WARN_ON_ONCE(1);
                *dreg = 0;
                break;
        }
}
EXPORT_SYMBOL_GPL(nft_fib_store_result);

bool nft_fib_reduce(struct nft_regs_track *track,
                    const struct nft_expr *expr)
{
        const struct nft_fib *priv = nft_expr_priv(expr);
        unsigned int len = NFT_REG32_SIZE;
        const struct nft_fib *fib;

        switch (priv->result) {
        case NFT_FIB_RESULT_OIF:
                break;
        case NFT_FIB_RESULT_OIFNAME:
                if (priv->flags & NFTA_FIB_F_PRESENT)
                        len = NFT_REG32_SIZE;
                else
                        len = IFNAMSIZ;
                break;
        case NFT_FIB_RESULT_ADDRTYPE:
             break;
        default:
                WARN_ON_ONCE(1);
                break;
        }

        if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
                nft_reg_track_update(track, expr, priv->dreg, len);
                return false;
        }

        fib = nft_expr_priv(track->regs[priv->dreg].selector);
        if (priv->result != fib->result ||
            priv->flags != fib->flags) {
                nft_reg_track_update(track, expr, priv->dreg, len);
                return false;
        }

        if (!track->regs[priv->dreg].bitwise)
                return true;

        return false;
}
EXPORT_SYMBOL_GPL(nft_fib_reduce);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Query routing table from nftables");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");