1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (c) 2020 Laura Garcia Liebana <nevola@gmail.com> |
4 | * Copyright (c) 2020 Jose M. Guisado <guigom@riseup.net> |
5 | */ |
6 | |
7 | #include <linux/etherdevice.h> |
8 | #include <linux/kernel.h> |
9 | #include <linux/init.h> |
10 | #include <linux/module.h> |
11 | #include <linux/netlink.h> |
12 | #include <linux/netfilter.h> |
13 | #include <linux/netfilter/nf_tables.h> |
14 | #include <net/netfilter/nf_tables.h> |
15 | #include <net/netfilter/nft_reject.h> |
16 | #include <net/netfilter/ipv4/nf_reject.h> |
17 | #include <net/netfilter/ipv6/nf_reject.h> |
18 | |
19 | static void nft_reject_queue_xmit(struct sk_buff *nskb, struct sk_buff *oldskb) |
20 | { |
21 | dev_hard_header(skb: nskb, dev: nskb->dev, ntohs(oldskb->protocol), |
22 | daddr: eth_hdr(skb: oldskb)->h_source, saddr: eth_hdr(skb: oldskb)->h_dest, |
23 | len: nskb->len); |
24 | dev_queue_xmit(skb: nskb); |
25 | } |
26 | |
27 | static void nft_reject_netdev_send_v4_tcp_reset(struct net *net, |
28 | struct sk_buff *oldskb, |
29 | const struct net_device *dev, |
30 | int hook) |
31 | { |
32 | struct sk_buff *nskb; |
33 | |
34 | nskb = nf_reject_skb_v4_tcp_reset(net, oldskb, dev, hook); |
35 | if (!nskb) |
36 | return; |
37 | |
38 | nft_reject_queue_xmit(nskb, oldskb); |
39 | } |
40 | |
41 | static void nft_reject_netdev_send_v4_unreach(struct net *net, |
42 | struct sk_buff *oldskb, |
43 | const struct net_device *dev, |
44 | int hook, u8 code) |
45 | { |
46 | struct sk_buff *nskb; |
47 | |
48 | nskb = nf_reject_skb_v4_unreach(net, oldskb, dev, hook, code); |
49 | if (!nskb) |
50 | return; |
51 | |
52 | nft_reject_queue_xmit(nskb, oldskb); |
53 | } |
54 | |
55 | static void nft_reject_netdev_send_v6_tcp_reset(struct net *net, |
56 | struct sk_buff *oldskb, |
57 | const struct net_device *dev, |
58 | int hook) |
59 | { |
60 | struct sk_buff *nskb; |
61 | |
62 | nskb = nf_reject_skb_v6_tcp_reset(net, oldskb, dev, hook); |
63 | if (!nskb) |
64 | return; |
65 | |
66 | nft_reject_queue_xmit(nskb, oldskb); |
67 | } |
68 | |
69 | |
70 | static void nft_reject_netdev_send_v6_unreach(struct net *net, |
71 | struct sk_buff *oldskb, |
72 | const struct net_device *dev, |
73 | int hook, u8 code) |
74 | { |
75 | struct sk_buff *nskb; |
76 | |
77 | nskb = nf_reject_skb_v6_unreach(net, oldskb, dev, hook, code); |
78 | if (!nskb) |
79 | return; |
80 | |
81 | nft_reject_queue_xmit(nskb, oldskb); |
82 | } |
83 | |
84 | static void nft_reject_netdev_eval(const struct nft_expr *expr, |
85 | struct nft_regs *regs, |
86 | const struct nft_pktinfo *pkt) |
87 | { |
88 | struct ethhdr *eth = eth_hdr(skb: pkt->skb); |
89 | struct nft_reject *priv = nft_expr_priv(expr); |
90 | const unsigned char *dest = eth->h_dest; |
91 | |
92 | if (is_broadcast_ether_addr(addr: dest) || |
93 | is_multicast_ether_addr(addr: dest)) |
94 | goto out; |
95 | |
96 | switch (eth->h_proto) { |
97 | case htons(ETH_P_IP): |
98 | switch (priv->type) { |
99 | case NFT_REJECT_ICMP_UNREACH: |
100 | nft_reject_netdev_send_v4_unreach(net: nft_net(pkt), oldskb: pkt->skb, |
101 | dev: nft_in(pkt), |
102 | hook: nft_hook(pkt), |
103 | code: priv->icmp_code); |
104 | break; |
105 | case NFT_REJECT_TCP_RST: |
106 | nft_reject_netdev_send_v4_tcp_reset(net: nft_net(pkt), oldskb: pkt->skb, |
107 | dev: nft_in(pkt), |
108 | hook: nft_hook(pkt)); |
109 | break; |
110 | case NFT_REJECT_ICMPX_UNREACH: |
111 | nft_reject_netdev_send_v4_unreach(net: nft_net(pkt), oldskb: pkt->skb, |
112 | dev: nft_in(pkt), |
113 | hook: nft_hook(pkt), |
114 | code: nft_reject_icmp_code(code: priv->icmp_code)); |
115 | break; |
116 | } |
117 | break; |
118 | case htons(ETH_P_IPV6): |
119 | switch (priv->type) { |
120 | case NFT_REJECT_ICMP_UNREACH: |
121 | nft_reject_netdev_send_v6_unreach(net: nft_net(pkt), oldskb: pkt->skb, |
122 | dev: nft_in(pkt), |
123 | hook: nft_hook(pkt), |
124 | code: priv->icmp_code); |
125 | break; |
126 | case NFT_REJECT_TCP_RST: |
127 | nft_reject_netdev_send_v6_tcp_reset(net: nft_net(pkt), oldskb: pkt->skb, |
128 | dev: nft_in(pkt), |
129 | hook: nft_hook(pkt)); |
130 | break; |
131 | case NFT_REJECT_ICMPX_UNREACH: |
132 | nft_reject_netdev_send_v6_unreach(net: nft_net(pkt), oldskb: pkt->skb, |
133 | dev: nft_in(pkt), |
134 | hook: nft_hook(pkt), |
135 | code: nft_reject_icmpv6_code(code: priv->icmp_code)); |
136 | break; |
137 | } |
138 | break; |
139 | default: |
140 | /* No explicit way to reject this protocol, drop it. */ |
141 | break; |
142 | } |
143 | out: |
144 | regs->verdict.code = NF_DROP; |
145 | } |
146 | |
147 | static int nft_reject_netdev_validate(const struct nft_ctx *ctx, |
148 | const struct nft_expr *expr, |
149 | const struct nft_data **data) |
150 | { |
151 | return nft_chain_validate_hooks(chain: ctx->chain, hook_flags: (1 << NF_NETDEV_INGRESS)); |
152 | } |
153 | |
154 | static struct nft_expr_type nft_reject_netdev_type; |
155 | static const struct nft_expr_ops nft_reject_netdev_ops = { |
156 | .type = &nft_reject_netdev_type, |
157 | .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), |
158 | .eval = nft_reject_netdev_eval, |
159 | .init = nft_reject_init, |
160 | .dump = nft_reject_dump, |
161 | .validate = nft_reject_netdev_validate, |
162 | .reduce = NFT_REDUCE_READONLY, |
163 | }; |
164 | |
165 | static struct nft_expr_type nft_reject_netdev_type __read_mostly = { |
166 | .family = NFPROTO_NETDEV, |
167 | .name = "reject" , |
168 | .ops = &nft_reject_netdev_ops, |
169 | .policy = nft_reject_policy, |
170 | .maxattr = NFTA_REJECT_MAX, |
171 | .owner = THIS_MODULE, |
172 | }; |
173 | |
174 | static int __init nft_reject_netdev_module_init(void) |
175 | { |
176 | return nft_register_expr(&nft_reject_netdev_type); |
177 | } |
178 | |
179 | static void __exit nft_reject_netdev_module_exit(void) |
180 | { |
181 | nft_unregister_expr(&nft_reject_netdev_type); |
182 | } |
183 | |
184 | module_init(nft_reject_netdev_module_init); |
185 | module_exit(nft_reject_netdev_module_exit); |
186 | |
187 | MODULE_LICENSE("GPL" ); |
188 | MODULE_AUTHOR("Laura Garcia Liebana <nevola@gmail.com>" ); |
189 | MODULE_AUTHOR("Jose M. Guisado <guigom@riseup.net>" ); |
190 | MODULE_DESCRIPTION("Reject packets from netdev via nftables" ); |
191 | MODULE_ALIAS_NFT_AF_EXPR(5, "reject" ); |
192 | |