1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2020 Laura Garcia Liebana <nevola@gmail.com>
4 * Copyright (c) 2020 Jose M. Guisado <guigom@riseup.net>
7 #include <linux/kernel.h>
8 #include <linux/init.h>
9 #include <linux/module.h>
10 #include <linux/netlink.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter/nf_tables.h>
13 #include <net/netfilter/nf_tables.h>
14 #include <net/netfilter/nft_reject.h>
15 #include <net/netfilter/ipv4/nf_reject.h>
16 #include <net/netfilter/ipv6/nf_reject.h>
18 static void nft_reject_queue_xmit(struct sk_buff *nskb, struct sk_buff *oldskb)
20 dev_hard_header(nskb, nskb->dev, ntohs(oldskb->protocol),
21 eth_hdr(oldskb)->h_source, eth_hdr(oldskb)->h_dest,
26 static void nft_reject_netdev_send_v4_tcp_reset(struct net *net,
27 struct sk_buff *oldskb,
28 const struct net_device *dev,
33 nskb = nf_reject_skb_v4_tcp_reset(net, oldskb, dev, hook);
37 nft_reject_queue_xmit(nskb, oldskb);
40 static void nft_reject_netdev_send_v4_unreach(struct net *net,
41 struct sk_buff *oldskb,
42 const struct net_device *dev,
47 nskb = nf_reject_skb_v4_unreach(net, oldskb, dev, hook, code);
51 nft_reject_queue_xmit(nskb, oldskb);
54 static void nft_reject_netdev_send_v6_tcp_reset(struct net *net,
55 struct sk_buff *oldskb,
56 const struct net_device *dev,
61 nskb = nf_reject_skb_v6_tcp_reset(net, oldskb, dev, hook);
65 nft_reject_queue_xmit(nskb, oldskb);
69 static void nft_reject_netdev_send_v6_unreach(struct net *net,
70 struct sk_buff *oldskb,
71 const struct net_device *dev,
76 nskb = nf_reject_skb_v6_unreach(net, oldskb, dev, hook, code);
80 nft_reject_queue_xmit(nskb, oldskb);
83 static void nft_reject_netdev_eval(const struct nft_expr *expr,
84 struct nft_regs *regs,
85 const struct nft_pktinfo *pkt)
87 struct ethhdr *eth = eth_hdr(pkt->skb);
88 struct nft_reject *priv = nft_expr_priv(expr);
89 const unsigned char *dest = eth->h_dest;
91 if (is_broadcast_ether_addr(dest) ||
92 is_multicast_ether_addr(dest))
95 switch (eth->h_proto) {
98 case NFT_REJECT_ICMP_UNREACH:
99 nft_reject_netdev_send_v4_unreach(nft_net(pkt), pkt->skb,
104 case NFT_REJECT_TCP_RST:
105 nft_reject_netdev_send_v4_tcp_reset(nft_net(pkt), pkt->skb,
109 case NFT_REJECT_ICMPX_UNREACH:
110 nft_reject_netdev_send_v4_unreach(nft_net(pkt), pkt->skb,
113 nft_reject_icmp_code(priv->icmp_code));
117 case htons(ETH_P_IPV6):
118 switch (priv->type) {
119 case NFT_REJECT_ICMP_UNREACH:
120 nft_reject_netdev_send_v6_unreach(nft_net(pkt), pkt->skb,
125 case NFT_REJECT_TCP_RST:
126 nft_reject_netdev_send_v6_tcp_reset(nft_net(pkt), pkt->skb,
130 case NFT_REJECT_ICMPX_UNREACH:
131 nft_reject_netdev_send_v6_unreach(nft_net(pkt), pkt->skb,
134 nft_reject_icmpv6_code(priv->icmp_code));
139 /* No explicit way to reject this protocol, drop it. */
143 regs->verdict.code = NF_DROP;
146 static int nft_reject_netdev_validate(const struct nft_ctx *ctx,
147 const struct nft_expr *expr,
148 const struct nft_data **data)
150 return nft_chain_validate_hooks(ctx->chain, (1 << NF_NETDEV_INGRESS));
153 static struct nft_expr_type nft_reject_netdev_type;
154 static const struct nft_expr_ops nft_reject_netdev_ops = {
155 .type = &nft_reject_netdev_type,
156 .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
157 .eval = nft_reject_netdev_eval,
158 .init = nft_reject_init,
159 .dump = nft_reject_dump,
160 .validate = nft_reject_netdev_validate,
163 static struct nft_expr_type nft_reject_netdev_type __read_mostly = {
164 .family = NFPROTO_NETDEV,
166 .ops = &nft_reject_netdev_ops,
167 .policy = nft_reject_policy,
168 .maxattr = NFTA_REJECT_MAX,
169 .owner = THIS_MODULE,
172 static int __init nft_reject_netdev_module_init(void)
174 return nft_register_expr(&nft_reject_netdev_type);
177 static void __exit nft_reject_netdev_module_exit(void)
179 nft_unregister_expr(&nft_reject_netdev_type);
182 module_init(nft_reject_netdev_module_init);
183 module_exit(nft_reject_netdev_module_exit);
185 MODULE_LICENSE("GPL");
186 MODULE_AUTHOR("Laura Garcia Liebana <nevola@gmail.com>");
187 MODULE_AUTHOR("Jose M. Guisado <guigom@riseup.net>");
188 MODULE_DESCRIPTION("Reject packets from netdev via nftables");
189 MODULE_ALIAS_NFT_AF_EXPR(5, "reject");