1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2014 Pablo Neira Ayuso <pablo@netfilter.org>
4 */
5
6#include <linux/kernel.h>
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/netlink.h>
10#include <linux/netfilter.h>
11#include <linux/netfilter/nf_tables.h>
12#include <net/netfilter/nf_tables.h>
13#include <net/netfilter/nft_reject.h>
14#include <net/netfilter/ipv4/nf_reject.h>
15#include <net/netfilter/ipv6/nf_reject.h>
16#include <linux/ip.h>
17#include <net/ip.h>
18#include <net/ip6_checksum.h>
19#include <linux/netfilter_bridge.h>
20#include <linux/netfilter_ipv6.h>
21#include "../br_private.h"
22
23static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb,
24 struct sk_buff *nskb)
25{
26 struct ethhdr *eth;
27
28 eth = skb_push(skb: nskb, ETH_HLEN);
29 skb_reset_mac_header(skb: nskb);
30 ether_addr_copy(dst: eth->h_source, src: eth_hdr(skb: oldskb)->h_dest);
31 ether_addr_copy(dst: eth->h_dest, src: eth_hdr(skb: oldskb)->h_source);
32 eth->h_proto = eth_hdr(skb: oldskb)->h_proto;
33 skb_pull(skb: nskb, ETH_HLEN);
34
35 if (skb_vlan_tag_present(oldskb)) {
36 u16 vid = skb_vlan_tag_get(oldskb);
37
38 __vlan_hwaccel_put_tag(skb: nskb, vlan_proto: oldskb->vlan_proto, vlan_tci: vid);
39 }
40}
41
42/* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT)
43 * or the bridge port (NF_BRIDGE PREROUTING).
44 */
45static void nft_reject_br_send_v4_tcp_reset(struct net *net,
46 struct sk_buff *oldskb,
47 const struct net_device *dev,
48 int hook)
49{
50 struct sk_buff *nskb;
51
52 nskb = nf_reject_skb_v4_tcp_reset(net, oldskb, NULL, hook);
53 if (!nskb)
54 return;
55
56 nft_reject_br_push_etherhdr(oldskb, nskb);
57
58 br_forward(to: br_port_get_rcu(dev), skb: nskb, local_rcv: false, local_orig: true);
59}
60
61static void nft_reject_br_send_v4_unreach(struct net *net,
62 struct sk_buff *oldskb,
63 const struct net_device *dev,
64 int hook, u8 code)
65{
66 struct sk_buff *nskb;
67
68 nskb = nf_reject_skb_v4_unreach(net, oldskb, NULL, hook, code);
69 if (!nskb)
70 return;
71
72 nft_reject_br_push_etherhdr(oldskb, nskb);
73
74 br_forward(to: br_port_get_rcu(dev), skb: nskb, local_rcv: false, local_orig: true);
75}
76
77static void nft_reject_br_send_v6_tcp_reset(struct net *net,
78 struct sk_buff *oldskb,
79 const struct net_device *dev,
80 int hook)
81{
82 struct sk_buff *nskb;
83
84 nskb = nf_reject_skb_v6_tcp_reset(net, oldskb, NULL, hook);
85 if (!nskb)
86 return;
87
88 nft_reject_br_push_etherhdr(oldskb, nskb);
89
90 br_forward(to: br_port_get_rcu(dev), skb: nskb, local_rcv: false, local_orig: true);
91}
92
93
94static void nft_reject_br_send_v6_unreach(struct net *net,
95 struct sk_buff *oldskb,
96 const struct net_device *dev,
97 int hook, u8 code)
98{
99 struct sk_buff *nskb;
100
101 nskb = nf_reject_skb_v6_unreach(net, oldskb, NULL, hook, code);
102 if (!nskb)
103 return;
104
105 nft_reject_br_push_etherhdr(oldskb, nskb);
106
107 br_forward(to: br_port_get_rcu(dev), skb: nskb, local_rcv: false, local_orig: true);
108}
109
110static void nft_reject_bridge_eval(const struct nft_expr *expr,
111 struct nft_regs *regs,
112 const struct nft_pktinfo *pkt)
113{
114 struct nft_reject *priv = nft_expr_priv(expr);
115 const unsigned char *dest = eth_hdr(skb: pkt->skb)->h_dest;
116
117 if (is_broadcast_ether_addr(addr: dest) ||
118 is_multicast_ether_addr(addr: dest))
119 goto out;
120
121 switch (eth_hdr(skb: pkt->skb)->h_proto) {
122 case htons(ETH_P_IP):
123 switch (priv->type) {
124 case NFT_REJECT_ICMP_UNREACH:
125 nft_reject_br_send_v4_unreach(net: nft_net(pkt), oldskb: pkt->skb,
126 dev: nft_in(pkt),
127 hook: nft_hook(pkt),
128 code: priv->icmp_code);
129 break;
130 case NFT_REJECT_TCP_RST:
131 nft_reject_br_send_v4_tcp_reset(net: nft_net(pkt), oldskb: pkt->skb,
132 dev: nft_in(pkt),
133 hook: nft_hook(pkt));
134 break;
135 case NFT_REJECT_ICMPX_UNREACH:
136 nft_reject_br_send_v4_unreach(net: nft_net(pkt), oldskb: pkt->skb,
137 dev: nft_in(pkt),
138 hook: nft_hook(pkt),
139 code: nft_reject_icmp_code(code: priv->icmp_code));
140 break;
141 }
142 break;
143 case htons(ETH_P_IPV6):
144 switch (priv->type) {
145 case NFT_REJECT_ICMP_UNREACH:
146 nft_reject_br_send_v6_unreach(net: nft_net(pkt), oldskb: pkt->skb,
147 dev: nft_in(pkt),
148 hook: nft_hook(pkt),
149 code: priv->icmp_code);
150 break;
151 case NFT_REJECT_TCP_RST:
152 nft_reject_br_send_v6_tcp_reset(net: nft_net(pkt), oldskb: pkt->skb,
153 dev: nft_in(pkt),
154 hook: nft_hook(pkt));
155 break;
156 case NFT_REJECT_ICMPX_UNREACH:
157 nft_reject_br_send_v6_unreach(net: nft_net(pkt), oldskb: pkt->skb,
158 dev: nft_in(pkt),
159 hook: nft_hook(pkt),
160 code: nft_reject_icmpv6_code(code: priv->icmp_code));
161 break;
162 }
163 break;
164 default:
165 /* No explicit way to reject this protocol, drop it. */
166 break;
167 }
168out:
169 regs->verdict.code = NF_DROP;
170}
171
172static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
173 const struct nft_expr *expr)
174{
175 return nft_chain_validate_hooks(chain: ctx->chain, hook_flags: (1 << NF_BR_PRE_ROUTING) |
176 (1 << NF_BR_LOCAL_IN));
177}
178
179static struct nft_expr_type nft_reject_bridge_type;
180static const struct nft_expr_ops nft_reject_bridge_ops = {
181 .type = &nft_reject_bridge_type,
182 .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
183 .eval = nft_reject_bridge_eval,
184 .init = nft_reject_init,
185 .dump = nft_reject_dump,
186 .validate = nft_reject_bridge_validate,
187 .reduce = NFT_REDUCE_READONLY,
188};
189
190static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
191 .family = NFPROTO_BRIDGE,
192 .name = "reject",
193 .ops = &nft_reject_bridge_ops,
194 .policy = nft_reject_policy,
195 .maxattr = NFTA_REJECT_MAX,
196 .owner = THIS_MODULE,
197};
198
199static int __init nft_reject_bridge_module_init(void)
200{
201 return nft_register_expr(&nft_reject_bridge_type);
202}
203
204static void __exit nft_reject_bridge_module_exit(void)
205{
206 nft_unregister_expr(&nft_reject_bridge_type);
207}
208
209module_init(nft_reject_bridge_module_init);
210module_exit(nft_reject_bridge_module_exit);
211
212MODULE_LICENSE("GPL");
213MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
214MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");
215MODULE_DESCRIPTION("Reject packets from bridge via nftables");
216

source code of linux/net/bridge/netfilter/nft_reject_bridge.c