// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2015 Pablo Neira Ayuso <[email protected]>
*/
#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 <linux/ip.h>
#include <linux/ipv6.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_offload.h>
#include <net/netfilter/nf_dup_netdev.h>
#include <net/neighbour.h>
#include <net/ip.h>
struct nft_fwd_netdev {
u8 sreg_dev;
};
static void nft_fwd_netdev_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_fwd_netdev *priv = nft_expr_priv(expr);
int oif = regs->data[priv->sreg_dev];
struct sk_buff *skb = pkt->skb;
/* This is used by ifb only. */
skb->skb_iif = skb->dev->ifindex;
skb_set_redirected(skb, nft_hook(pkt) == NF_NETDEV_INGRESS);
nf_fwd_netdev_egress(pkt, oif);
regs->verdict.code = NF_STOLEN;
}
static const struct nla_policy nft_fwd_netdev_policy[NFTA_FWD_MAX + 1] = {
[NFTA_FWD_SREG_DEV] = { .type = NLA_U32 },
[NFTA_FWD_SREG_ADDR] = { .type = NLA_U32 },
[NFTA_FWD_NFPROTO] = NLA_POLICY_MAX(NLA_BE32, 255),
};
static int nft_fwd_netdev_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_fwd_netdev *priv = nft_expr_priv(expr);
if (tb[NFTA_FWD_SREG_DEV] == NULL)
return -EINVAL;
return nft_parse_register_load(ctx, tb[NFTA_FWD_SREG_DEV], &priv->sreg_dev,
sizeof(int));
}
static int nft_fwd_netdev_dump(struct sk_buff *skb,
const struct nft_expr *expr, bool reset)
{
struct nft_fwd_netdev *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static int nft_fwd_netdev_offload(struct nft_offload_ctx *ctx,
struct nft_flow_rule *flow,
const struct nft_expr *expr)
{
const struct nft_fwd_netdev *priv = nft_expr_priv(expr);
int oif = ctx->regs[priv->sreg_dev].data.data[0];
return nft_fwd_dup_netdev_offload(ctx, flow, FLOW_ACTION_REDIRECT, oif);
}
static bool nft_fwd_netdev_offload_action(const struct nft_expr *expr)
{
return true;
}
struct nft_fwd_neigh {
u8 sreg_dev;
u8 sreg_addr;
u8 nfproto;
};
static void nft_fwd_neigh_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_fwd_neigh *priv = nft_expr_priv(expr);
void *addr = ®s->data[priv->sreg_addr];
int oif = regs->data[priv->sreg_dev];
unsigned int verdict = NF_STOLEN;
struct sk_buff *skb = pkt->skb;
struct net_device *dev;
int neigh_table;
switch (priv->nfproto) {
case NFPROTO_IPV4: {
struct iphdr *iph;
if (skb->protocol != htons(ETH_P_IP)) {
verdict = NFT_BREAK;
goto out;
}
if (skb_try_make_writable(skb, sizeof(*iph))) {
verdict = NF_DROP;
goto out;
}
iph = ip_hdr(skb);
ip_decrease_ttl(iph);
neigh_table = NEIGH_ARP_TABLE;
break;
}
case NFPROTO_IPV6: {
struct ipv6hdr *ip6h;
if (skb->protocol != htons(ETH_P_IPV6)) {
verdict = NFT_BREAK;
goto out;
}
if (skb_try_make_writable(skb, sizeof(*ip6h))) {
verdict = NF_DROP;
goto out;
}
ip6h = ipv6_hdr(skb);
ip6h->hop_limit--;
neigh_table = NEIGH_ND_TABLE;
break;
}
default:
verdict = NFT_BREAK;
goto out;
}
dev = dev_get_by_index_rcu(nft_net(pkt), oif);
if (dev == NULL)
return;
skb->dev = dev;
skb_clear_tstamp(skb);
neigh_xmit(neigh_table, dev, addr, skb);
out:
regs->verdict.code = verdict;
}
static int nft_fwd_neigh_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_fwd_neigh *priv = nft_expr_priv(expr);
unsigned int addr_len;
int err;
if (!tb[NFTA_FWD_SREG_DEV] ||
!tb[NFTA_FWD_SREG_ADDR] ||
!tb[NFTA_FWD_NFPROTO])
return -EINVAL;
priv->nfproto = ntohl(nla_get_be32(tb[NFTA_FWD_NFPROTO]));
switch (priv->nfproto) {
case NFPROTO_IPV4:
addr_len = sizeof(struct in_addr);
break;
case NFPROTO_IPV6:
addr_len = sizeof(struct in6_addr);
break;
default:
return -EOPNOTSUPP;
}
err = nft_parse_register_load(ctx, tb[NFTA_FWD_SREG_DEV], &priv->sreg_dev,
sizeof(int));
if (err < 0)
return err;
return nft_parse_register_load(ctx, tb[NFTA_FWD_SREG_ADDR], &priv->sreg_addr,
addr_len);
}
static int nft_fwd_neigh_dump(struct sk_buff *skb,
const struct nft_expr *expr, bool reset)
{
struct nft_fwd_neigh *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev) ||
nft_dump_register(skb, NFTA_FWD_SREG_ADDR, priv->sreg_addr) ||
nla_put_be32(skb, NFTA_FWD_NFPROTO, htonl(priv->nfproto)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static int nft_fwd_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
return nft_chain_validate_hooks(ctx->chain, (1 << NF_NETDEV_INGRESS) |
(1 << NF_NETDEV_EGRESS));
}
static struct nft_expr_type nft_fwd_netdev_type;
static const struct nft_expr_ops nft_fwd_neigh_netdev_ops = {
.type = &nft_fwd_netdev_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_neigh)),
.eval = nft_fwd_neigh_eval,
.init = nft_fwd_neigh_init,
.dump = nft_fwd_neigh_dump,
.validate = nft_fwd_validate,
.reduce = NFT_REDUCE_READONLY,
};
static const struct nft_expr_ops nft_fwd_netdev_ops = {
.type = &nft_fwd_netdev_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_netdev)),
.eval = nft_fwd_netdev_eval,
.init = nft_fwd_netdev_init,
.dump = nft_fwd_netdev_dump,
.validate = nft_fwd_validate,
.reduce = NFT_REDUCE_READONLY,
.offload = nft_fwd_netdev_offload,
.offload_action = nft_fwd_netdev_offload_action,
};
static const struct nft_expr_ops *
nft_fwd_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
if (tb[NFTA_FWD_SREG_ADDR])
return &nft_fwd_neigh_netdev_ops;
if (tb[NFTA_FWD_SREG_DEV])
return &nft_fwd_netdev_ops;
return ERR_PTR(-EOPNOTSUPP);
}
static struct nft_expr_type nft_fwd_netdev_type __read_mostly = {
.family = NFPROTO_NETDEV,
.name = "fwd",
.select_ops = nft_fwd_select_ops,
.policy = nft_fwd_netdev_policy,
.maxattr = NFTA_FWD_MAX,
.owner = THIS_MODULE,
};
static int __init nft_fwd_netdev_module_init(void)
{
return nft_register_expr(&nft_fwd_netdev_type);
}
static void __exit nft_fwd_netdev_module_exit(void)
{
nft_unregister_expr(&nft_fwd_netdev_type);
}
module_init(nft_fwd_netdev_module_init);
module_exit(nft_fwd_netdev_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <[email protected]>");
MODULE_DESCRIPTION("nftables netdev packet forwarding support");
MODULE_ALIAS_NFT_AF_EXPR(5, "fwd");