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
20static 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	struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out);
26
27	switch (pkt->ops->pf) {
28	case NFPROTO_IPV4:
29		switch (priv->type) {
30		case NFT_REJECT_ICMP_UNREACH:
31			nf_send_unreach(pkt->skb, priv->icmp_code,
32					pkt->ops->hooknum);
33			break;
34		case NFT_REJECT_TCP_RST:
35			nf_send_reset(pkt->skb, pkt->ops->hooknum);
36			break;
37		case NFT_REJECT_ICMPX_UNREACH:
38			nf_send_unreach(pkt->skb,
39					nft_reject_icmp_code(priv->icmp_code),
40					pkt->ops->hooknum);
41			break;
42		}
43		break;
44	case NFPROTO_IPV6:
45		switch (priv->type) {
46		case NFT_REJECT_ICMP_UNREACH:
47			nf_send_unreach6(net, pkt->skb, priv->icmp_code,
48					 pkt->ops->hooknum);
49			break;
50		case NFT_REJECT_TCP_RST:
51			nf_send_reset6(net, pkt->skb, pkt->ops->hooknum);
52			break;
53		case NFT_REJECT_ICMPX_UNREACH:
54			nf_send_unreach6(net, pkt->skb,
55					 nft_reject_icmpv6_code(priv->icmp_code),
56					 pkt->ops->hooknum);
57			break;
58		}
59		break;
60	}
61
62	regs->verdict.code = NF_DROP;
63}
64
65static int nft_reject_inet_init(const struct nft_ctx *ctx,
66				const struct nft_expr *expr,
67				const struct nlattr * const tb[])
68{
69	struct nft_reject *priv = nft_expr_priv(expr);
70	int icmp_code;
71
72	if (tb[NFTA_REJECT_TYPE] == NULL)
73		return -EINVAL;
74
75	priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
76	switch (priv->type) {
77	case NFT_REJECT_ICMP_UNREACH:
78	case NFT_REJECT_ICMPX_UNREACH:
79		if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
80			return -EINVAL;
81
82		icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
83		if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
84		    icmp_code > NFT_REJECT_ICMPX_MAX)
85			return -EINVAL;
86
87		priv->icmp_code = icmp_code;
88		break;
89	case NFT_REJECT_TCP_RST:
90		break;
91	default:
92		return -EINVAL;
93	}
94	return 0;
95}
96
97static int nft_reject_inet_dump(struct sk_buff *skb,
98				const struct nft_expr *expr)
99{
100	const struct nft_reject *priv = nft_expr_priv(expr);
101
102	if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
103		goto nla_put_failure;
104
105	switch (priv->type) {
106	case NFT_REJECT_ICMP_UNREACH:
107	case NFT_REJECT_ICMPX_UNREACH:
108		if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
109			goto nla_put_failure;
110		break;
111	default:
112		break;
113	}
114
115	return 0;
116
117nla_put_failure:
118	return -1;
119}
120
121static struct nft_expr_type nft_reject_inet_type;
122static const struct nft_expr_ops nft_reject_inet_ops = {
123	.type		= &nft_reject_inet_type,
124	.size		= NFT_EXPR_SIZE(sizeof(struct nft_reject)),
125	.eval		= nft_reject_inet_eval,
126	.init		= nft_reject_inet_init,
127	.dump		= nft_reject_inet_dump,
128};
129
130static 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
139static int __init nft_reject_inet_module_init(void)
140{
141	return nft_register_expr(&nft_reject_inet_type);
142}
143
144static void __exit nft_reject_inet_module_exit(void)
145{
146	nft_unregister_expr(&nft_reject_inet_type);
147}
148
149module_init(nft_reject_inet_module_init);
150module_exit(nft_reject_inet_module_exit);
151
152MODULE_LICENSE("GPL");
153MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
154MODULE_ALIAS_NFT_AF_EXPR(1, "reject");
155