// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nft_fib.h>
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#include <net/ip_fib.h>
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#include <net/route.h>
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/* don't try to find route from mcast/bcast/zeronet */
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static __be32 get_saddr(__be32 addr)
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{
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if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
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ipv4_is_zeronet(addr))
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return 0;
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return addr;
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}
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#define DSCP_BITS 0xfc
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void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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const struct nft_fib *priv = nft_expr_priv(expr);
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int noff = skb_network_offset(pkt->skb);
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u32 *dst = ®s->data[priv->dreg];
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const struct net_device *dev = NULL;
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struct iphdr *iph, _iph;
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__be32 addr;
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if (priv->flags & NFTA_FIB_F_IIF)
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dev = nft_in(pkt);
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else if (priv->flags & NFTA_FIB_F_OIF)
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dev = nft_out(pkt);
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iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
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if (!iph) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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if (priv->flags & NFTA_FIB_F_DADDR)
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addr = iph->daddr;
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else
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addr = iph->saddr;
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*dst = inet_dev_addr_type(nft_net(pkt), dev, addr);
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}
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EXPORT_SYMBOL_GPL(nft_fib4_eval_type);
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void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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const struct nft_fib *priv = nft_expr_priv(expr);
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int noff = skb_network_offset(pkt->skb);
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u32 *dest = ®s->data[priv->dreg];
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struct iphdr *iph, _iph;
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struct fib_result res;
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struct flowi4 fl4 = {
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.flowi4_scope = RT_SCOPE_UNIVERSE,
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.flowi4_iif = LOOPBACK_IFINDEX,
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};
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const struct net_device *oif;
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const struct net_device *found;
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/*
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* Do not set flowi4_oif, it restricts results (for example, asking
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* for oif 3 will get RTN_UNICAST result even if the daddr exits
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* on another interface.
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*
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* Search results for the desired outinterface instead.
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*/
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if (priv->flags & NFTA_FIB_F_OIF)
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oif = nft_out(pkt);
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else if (priv->flags & NFTA_FIB_F_IIF)
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oif = nft_in(pkt);
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else
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oif = NULL;
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if (priv->flags & NFTA_FIB_F_IIF)
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fl4.flowi4_oif = l3mdev_master_ifindex_rcu(oif);
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if (nft_hook(pkt) == NF_INET_PRE_ROUTING &&
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nft_fib_is_loopback(pkt->skb, nft_in(pkt))) {
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nft_fib_store_result(dest, priv, nft_in(pkt));
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return;
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}
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iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
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if (!iph) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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if (ipv4_is_zeronet(iph->saddr)) {
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if (ipv4_is_lbcast(iph->daddr) ||
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ipv4_is_local_multicast(iph->daddr)) {
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nft_fib_store_result(dest, priv, pkt->skb->dev);
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return;
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}
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}
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if (priv->flags & NFTA_FIB_F_MARK)
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fl4.flowi4_mark = pkt->skb->mark;
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fl4.flowi4_tos = iph->tos & DSCP_BITS;
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if (priv->flags & NFTA_FIB_F_DADDR) {
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fl4.daddr = iph->daddr;
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fl4.saddr = get_saddr(iph->saddr);
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} else {
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fl4.daddr = iph->saddr;
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fl4.saddr = get_saddr(iph->daddr);
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}
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*dest = 0;
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if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
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return;
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switch (res.type) {
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case RTN_UNICAST:
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break;
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case RTN_LOCAL: /* Should not see RTN_LOCAL here */
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return;
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default:
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break;
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}
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if (!oif) {
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found = FIB_RES_DEV(res);
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} else {
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if (!fib_info_nh_uses_dev(res.fi, oif))
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return;
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found = oif;
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}
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nft_fib_store_result(dest, priv, found);
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}
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EXPORT_SYMBOL_GPL(nft_fib4_eval);
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static struct nft_expr_type nft_fib4_type;
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static const struct nft_expr_ops nft_fib4_type_ops = {
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.type = &nft_fib4_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
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.eval = nft_fib4_eval_type,
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.init = nft_fib_init,
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.dump = nft_fib_dump,
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.validate = nft_fib_validate,
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};
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static const struct nft_expr_ops nft_fib4_ops = {
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.type = &nft_fib4_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
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.eval = nft_fib4_eval,
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.init = nft_fib_init,
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.dump = nft_fib_dump,
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.validate = nft_fib_validate,
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};
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static const struct nft_expr_ops *
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nft_fib4_select_ops(const struct nft_ctx *ctx,
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const struct nlattr * const tb[])
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{
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enum nft_fib_result result;
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if (!tb[NFTA_FIB_RESULT])
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return ERR_PTR(-EINVAL);
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result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
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switch (result) {
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case NFT_FIB_RESULT_OIF:
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return &nft_fib4_ops;
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case NFT_FIB_RESULT_OIFNAME:
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return &nft_fib4_ops;
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case NFT_FIB_RESULT_ADDRTYPE:
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return &nft_fib4_type_ops;
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default:
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return ERR_PTR(-EOPNOTSUPP);
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}
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}
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static struct nft_expr_type nft_fib4_type __read_mostly = {
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.name = "fib",
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.select_ops = nft_fib4_select_ops,
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.policy = nft_fib_policy,
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.maxattr = NFTA_FIB_MAX,
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.family = NFPROTO_IPV4,
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.owner = THIS_MODULE,
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};
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static int __init nft_fib4_module_init(void)
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{
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return nft_register_expr(&nft_fib4_type);
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}
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static void __exit nft_fib4_module_exit(void)
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{
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nft_unregister_expr(&nft_fib4_type);
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}
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module_init(nft_fib4_module_init);
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module_exit(nft_fib4_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
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MODULE_ALIAS_NFT_AF_EXPR(2, "fib");
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MODULE_DESCRIPTION("nftables fib / ip route lookup support");
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