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6bbb9ad3 JGG |
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 | ||
b6459415 | 7 | #include <linux/etherdevice.h> |
6bbb9ad3 JGG |
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(nskb, nskb->dev, ntohs(oldskb->protocol), | |
22 | eth_hdr(oldskb)->h_source, eth_hdr(oldskb)->h_dest, | |
23 | nskb->len); | |
24 | dev_queue_xmit(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(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(dest) || | |
93 | is_multicast_ether_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(nft_net(pkt), pkt->skb, | |
101 | nft_in(pkt), | |
102 | nft_hook(pkt), | |
103 | priv->icmp_code); | |
104 | break; | |
105 | case NFT_REJECT_TCP_RST: | |
106 | nft_reject_netdev_send_v4_tcp_reset(nft_net(pkt), pkt->skb, | |
107 | nft_in(pkt), | |
108 | nft_hook(pkt)); | |
109 | break; | |
110 | case NFT_REJECT_ICMPX_UNREACH: | |
111 | nft_reject_netdev_send_v4_unreach(nft_net(pkt), pkt->skb, | |
112 | nft_in(pkt), | |
113 | nft_hook(pkt), | |
114 | nft_reject_icmp_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(nft_net(pkt), pkt->skb, | |
122 | nft_in(pkt), | |
123 | nft_hook(pkt), | |
124 | priv->icmp_code); | |
125 | break; | |
126 | case NFT_REJECT_TCP_RST: | |
127 | nft_reject_netdev_send_v6_tcp_reset(nft_net(pkt), pkt->skb, | |
128 | nft_in(pkt), | |
129 | nft_hook(pkt)); | |
130 | break; | |
131 | case NFT_REJECT_ICMPX_UNREACH: | |
132 | nft_reject_netdev_send_v6_unreach(nft_net(pkt), pkt->skb, | |
133 | nft_in(pkt), | |
134 | nft_hook(pkt), | |
135 | nft_reject_icmpv6_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(ctx->chain, (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, | |
b2d30654 | 162 | .reduce = NFT_REDUCE_READONLY, |
6bbb9ad3 JGG |
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"); |