| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright (c) 2020 Laura Garcia Liebana <nevola@gmail.com> |
| * Copyright (c) 2020 Jose M. Guisado <guigom@riseup.net> |
| */ |
| |
| #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.h> |
| #include <net/netfilter/nft_reject.h> |
| #include <net/netfilter/ipv4/nf_reject.h> |
| #include <net/netfilter/ipv6/nf_reject.h> |
| |
| static void nft_reject_queue_xmit(struct sk_buff *nskb, struct sk_buff *oldskb) |
| { |
| dev_hard_header(nskb, nskb->dev, ntohs(oldskb->protocol), |
| eth_hdr(oldskb)->h_source, eth_hdr(oldskb)->h_dest, |
| nskb->len); |
| dev_queue_xmit(nskb); |
| } |
| |
| static void nft_reject_netdev_send_v4_tcp_reset(struct net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v4_tcp_reset(net, oldskb, dev, hook); |
| if (!nskb) |
| return; |
| |
| nft_reject_queue_xmit(nskb, oldskb); |
| } |
| |
| static void nft_reject_netdev_send_v4_unreach(struct net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook, u8 code) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v4_unreach(net, oldskb, dev, hook, code); |
| if (!nskb) |
| return; |
| |
| nft_reject_queue_xmit(nskb, oldskb); |
| } |
| |
| static void nft_reject_netdev_send_v6_tcp_reset(struct net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v6_tcp_reset(net, oldskb, dev, hook); |
| if (!nskb) |
| return; |
| |
| nft_reject_queue_xmit(nskb, oldskb); |
| } |
| |
| |
| static void nft_reject_netdev_send_v6_unreach(struct net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook, u8 code) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v6_unreach(net, oldskb, dev, hook, code); |
| if (!nskb) |
| return; |
| |
| nft_reject_queue_xmit(nskb, oldskb); |
| } |
| |
| static void nft_reject_netdev_eval(const struct nft_expr *expr, |
| struct nft_regs *regs, |
| const struct nft_pktinfo *pkt) |
| { |
| struct ethhdr *eth = eth_hdr(pkt->skb); |
| struct nft_reject *priv = nft_expr_priv(expr); |
| const unsigned char *dest = eth->h_dest; |
| |
| if (is_broadcast_ether_addr(dest) || |
| is_multicast_ether_addr(dest)) |
| goto out; |
| |
| switch (eth->h_proto) { |
| case htons(ETH_P_IP): |
| switch (priv->type) { |
| case NFT_REJECT_ICMP_UNREACH: |
| nft_reject_netdev_send_v4_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| priv->icmp_code); |
| break; |
| case NFT_REJECT_TCP_RST: |
| nft_reject_netdev_send_v4_tcp_reset(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt)); |
| break; |
| case NFT_REJECT_ICMPX_UNREACH: |
| nft_reject_netdev_send_v4_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| nft_reject_icmp_code(priv->icmp_code)); |
| break; |
| } |
| break; |
| case htons(ETH_P_IPV6): |
| switch (priv->type) { |
| case NFT_REJECT_ICMP_UNREACH: |
| nft_reject_netdev_send_v6_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| priv->icmp_code); |
| break; |
| case NFT_REJECT_TCP_RST: |
| nft_reject_netdev_send_v6_tcp_reset(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt)); |
| break; |
| case NFT_REJECT_ICMPX_UNREACH: |
| nft_reject_netdev_send_v6_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| nft_reject_icmpv6_code(priv->icmp_code)); |
| break; |
| } |
| break; |
| default: |
| /* No explicit way to reject this protocol, drop it. */ |
| break; |
| } |
| out: |
| regs->verdict.code = NF_DROP; |
| } |
| |
| static int nft_reject_netdev_validate(const struct nft_ctx *ctx, |
| const struct nft_expr *expr, |
| const struct nft_data **data) |
| { |
| return nft_chain_validate_hooks(ctx->chain, (1 << NF_NETDEV_INGRESS)); |
| } |
| |
| static struct nft_expr_type nft_reject_netdev_type; |
| static const struct nft_expr_ops nft_reject_netdev_ops = { |
| .type = &nft_reject_netdev_type, |
| .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), |
| .eval = nft_reject_netdev_eval, |
| .init = nft_reject_init, |
| .dump = nft_reject_dump, |
| .validate = nft_reject_netdev_validate, |
| }; |
| |
| static struct nft_expr_type nft_reject_netdev_type __read_mostly = { |
| .family = NFPROTO_NETDEV, |
| .name = "reject", |
| .ops = &nft_reject_netdev_ops, |
| .policy = nft_reject_policy, |
| .maxattr = NFTA_REJECT_MAX, |
| .owner = THIS_MODULE, |
| }; |
| |
| static int __init nft_reject_netdev_module_init(void) |
| { |
| return nft_register_expr(&nft_reject_netdev_type); |
| } |
| |
| static void __exit nft_reject_netdev_module_exit(void) |
| { |
| nft_unregister_expr(&nft_reject_netdev_type); |
| } |
| |
| module_init(nft_reject_netdev_module_init); |
| module_exit(nft_reject_netdev_module_exit); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Laura Garcia Liebana <nevola@gmail.com>"); |
| MODULE_AUTHOR("Jose M. Guisado <guigom@riseup.net>"); |
| MODULE_DESCRIPTION("Reject packets from netdev via nftables"); |
| MODULE_ALIAS_NFT_AF_EXPR(5, "reject"); |