1 /*
2  * Copyright (c) 2014 Patrick McHardy <kaber@trash.net>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/netlink.h>
13 #include <linux/netfilter.h>
14 #include <linux/netfilter/nf_tables.h>
15 #include <net/netfilter/nf_tables.h>
16 #include <net/netfilter/nft_reject.h>
17 #include <net/netfilter/ipv4/nf_reject.h>
18 #include <net/netfilter/ipv6/nf_reject.h>
19 
20 static void nft_reject_inet_eval(const struct nft_expr *expr,
21 				 struct nft_regs *regs,
22 				 const struct nft_pktinfo *pkt)
23 {
24 	struct nft_reject *priv = nft_expr_priv(expr);
25 
26 	switch (nft_pf(pkt)) {
27 	case NFPROTO_IPV4:
28 		switch (priv->type) {
29 		case NFT_REJECT_ICMP_UNREACH:
30 			nf_send_unreach(pkt->skb, priv->icmp_code,
31 					nft_hook(pkt));
32 			break;
33 		case NFT_REJECT_TCP_RST:
34 			nf_send_reset(nft_net(pkt), pkt->skb, nft_hook(pkt));
35 			break;
36 		case NFT_REJECT_ICMPX_UNREACH:
37 			nf_send_unreach(pkt->skb,
38 					nft_reject_icmp_code(priv->icmp_code),
39 					nft_hook(pkt));
40 			break;
41 		}
42 		break;
43 	case NFPROTO_IPV6:
44 		switch (priv->type) {
45 		case NFT_REJECT_ICMP_UNREACH:
46 			nf_send_unreach6(nft_net(pkt), pkt->skb,
47 					 priv->icmp_code, nft_hook(pkt));
48 			break;
49 		case NFT_REJECT_TCP_RST:
50 			nf_send_reset6(nft_net(pkt), pkt->skb, nft_hook(pkt));
51 			break;
52 		case NFT_REJECT_ICMPX_UNREACH:
53 			nf_send_unreach6(nft_net(pkt), pkt->skb,
54 					 nft_reject_icmpv6_code(priv->icmp_code),
55 					 nft_hook(pkt));
56 			break;
57 		}
58 		break;
59 	}
60 
61 	regs->verdict.code = NF_DROP;
62 }
63 
64 static int nft_reject_inet_init(const struct nft_ctx *ctx,
65 				const struct nft_expr *expr,
66 				const struct nlattr * const tb[])
67 {
68 	struct nft_reject *priv = nft_expr_priv(expr);
69 	int icmp_code;
70 
71 	if (tb[NFTA_REJECT_TYPE] == NULL)
72 		return -EINVAL;
73 
74 	priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
75 	switch (priv->type) {
76 	case NFT_REJECT_ICMP_UNREACH:
77 	case NFT_REJECT_ICMPX_UNREACH:
78 		if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
79 			return -EINVAL;
80 
81 		icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
82 		if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
83 		    icmp_code > NFT_REJECT_ICMPX_MAX)
84 			return -EINVAL;
85 
86 		priv->icmp_code = icmp_code;
87 		break;
88 	case NFT_REJECT_TCP_RST:
89 		break;
90 	default:
91 		return -EINVAL;
92 	}
93 	return 0;
94 }
95 
96 static int nft_reject_inet_dump(struct sk_buff *skb,
97 				const struct nft_expr *expr)
98 {
99 	const struct nft_reject *priv = nft_expr_priv(expr);
100 
101 	if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
102 		goto nla_put_failure;
103 
104 	switch (priv->type) {
105 	case NFT_REJECT_ICMP_UNREACH:
106 	case NFT_REJECT_ICMPX_UNREACH:
107 		if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
108 			goto nla_put_failure;
109 		break;
110 	default:
111 		break;
112 	}
113 
114 	return 0;
115 
116 nla_put_failure:
117 	return -1;
118 }
119 
120 static struct nft_expr_type nft_reject_inet_type;
121 static const struct nft_expr_ops nft_reject_inet_ops = {
122 	.type		= &nft_reject_inet_type,
123 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_reject)),
124 	.eval		= nft_reject_inet_eval,
125 	.init		= nft_reject_inet_init,
126 	.dump		= nft_reject_inet_dump,
127 	.validate	= nft_reject_validate,
128 };
129 
130 static struct nft_expr_type nft_reject_inet_type __read_mostly = {
131 	.family		= NFPROTO_INET,
132 	.name		= "reject",
133 	.ops		= &nft_reject_inet_ops,
134 	.policy		= nft_reject_policy,
135 	.maxattr	= NFTA_REJECT_MAX,
136 	.owner		= THIS_MODULE,
137 };
138 
139 static int __init nft_reject_inet_module_init(void)
140 {
141 	return nft_register_expr(&nft_reject_inet_type);
142 }
143 
144 static void __exit nft_reject_inet_module_exit(void)
145 {
146 	nft_unregister_expr(&nft_reject_inet_type);
147 }
148 
149 module_init(nft_reject_inet_module_init);
150 module_exit(nft_reject_inet_module_exit);
151 
152 MODULE_LICENSE("GPL");
153 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
154 MODULE_ALIAS_NFT_AF_EXPR(1, "reject");
155