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 | |
23 | static 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 | */ |
45 | static 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 | |
61 | static 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 | |
77 | static 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 | |
94 | static 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 | |
110 | static 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 | } |
168 | out: |
169 | regs->verdict.code = NF_DROP; |
170 | } |
171 | |
172 | static int nft_reject_bridge_validate(const struct nft_ctx *ctx, |
173 | const struct nft_expr *expr, |
174 | const struct nft_data **data) |
175 | { |
176 | return nft_chain_validate_hooks(chain: ctx->chain, hook_flags: (1 << NF_BR_PRE_ROUTING) | |
177 | (1 << NF_BR_LOCAL_IN)); |
178 | } |
179 | |
180 | static struct nft_expr_type nft_reject_bridge_type; |
181 | static const struct nft_expr_ops nft_reject_bridge_ops = { |
182 | .type = &nft_reject_bridge_type, |
183 | .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), |
184 | .eval = nft_reject_bridge_eval, |
185 | .init = nft_reject_init, |
186 | .dump = nft_reject_dump, |
187 | .validate = nft_reject_bridge_validate, |
188 | .reduce = NFT_REDUCE_READONLY, |
189 | }; |
190 | |
191 | static struct nft_expr_type nft_reject_bridge_type __read_mostly = { |
192 | .family = NFPROTO_BRIDGE, |
193 | .name = "reject" , |
194 | .ops = &nft_reject_bridge_ops, |
195 | .policy = nft_reject_policy, |
196 | .maxattr = NFTA_REJECT_MAX, |
197 | .owner = THIS_MODULE, |
198 | }; |
199 | |
200 | static int __init nft_reject_bridge_module_init(void) |
201 | { |
202 | return nft_register_expr(&nft_reject_bridge_type); |
203 | } |
204 | |
205 | static void __exit nft_reject_bridge_module_exit(void) |
206 | { |
207 | nft_unregister_expr(&nft_reject_bridge_type); |
208 | } |
209 | |
210 | module_init(nft_reject_bridge_module_init); |
211 | module_exit(nft_reject_bridge_module_exit); |
212 | |
213 | MODULE_LICENSE("GPL" ); |
214 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>" ); |
215 | MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject" ); |
216 | MODULE_DESCRIPTION("Reject packets from bridge via nftables" ); |
217 | |