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764d8a9f PM |
1 | /* |
2 | * IP6 tables REJECT target module | |
3 | * Linux INET6 implementation | |
4 | * | |
5 | * Copyright (C)2003 USAGI/WIDE Project | |
6 | * | |
7 | * Authors: | |
8 | * Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp> | |
9 | * | |
10 | * Based on net/ipv4/netfilter/ipt_REJECT.c | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
16 | */ | |
ff67e4e4 | 17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
764d8a9f | 18 | |
5a0e3ad6 | 19 | #include <linux/gfp.h> |
764d8a9f PM |
20 | #include <linux/module.h> |
21 | #include <linux/skbuff.h> | |
22 | #include <linux/icmpv6.h> | |
23 | #include <linux/netdevice.h> | |
24 | #include <net/ipv6.h> | |
25 | #include <net/tcp.h> | |
26 | #include <net/icmp.h> | |
27 | #include <net/ip6_checksum.h> | |
28 | #include <net/ip6_fib.h> | |
29 | #include <net/ip6_route.h> | |
30 | #include <net/flow.h> | |
6709dbbb | 31 | #include <linux/netfilter/x_tables.h> |
764d8a9f PM |
32 | #include <linux/netfilter_ipv6/ip6_tables.h> |
33 | #include <linux/netfilter_ipv6/ip6t_REJECT.h> | |
34 | ||
35 | MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>"); | |
2ae15b64 | 36 | MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6"); |
764d8a9f PM |
37 | MODULE_LICENSE("GPL"); |
38 | ||
764d8a9f | 39 | /* Send RST reply */ |
e10aad99 | 40 | static void send_reset(struct net *net, struct sk_buff *oldskb) |
764d8a9f PM |
41 | { |
42 | struct sk_buff *nskb; | |
43 | struct tcphdr otcph, *tcph; | |
44 | unsigned int otcplen, hh_len; | |
45 | int tcphoff, needs_ack; | |
3cf93c96 JE |
46 | const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); |
47 | struct ipv6hdr *ip6h; | |
764d8a9f PM |
48 | struct dst_entry *dst = NULL; |
49 | u8 proto; | |
50 | struct flowi fl; | |
51 | ||
52 | if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || | |
53 | (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { | |
ff67e4e4 | 54 | pr_debug("addr is not unicast.\n"); |
764d8a9f PM |
55 | return; |
56 | } | |
57 | ||
58 | proto = oip6h->nexthdr; | |
59 | tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto); | |
60 | ||
61 | if ((tcphoff < 0) || (tcphoff > oldskb->len)) { | |
ff67e4e4 | 62 | pr_debug("Cannot get TCP header.\n"); |
764d8a9f PM |
63 | return; |
64 | } | |
65 | ||
66 | otcplen = oldskb->len - tcphoff; | |
67 | ||
68 | /* IP header checks: fragment, too short. */ | |
7c4e36bc | 69 | if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) { |
ff67e4e4 | 70 | pr_debug("proto(%d) != IPPROTO_TCP, " |
0d53778e PM |
71 | "or too short. otcplen = %d\n", |
72 | proto, otcplen); | |
764d8a9f PM |
73 | return; |
74 | } | |
75 | ||
76 | if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr))) | |
77 | BUG(); | |
78 | ||
79 | /* No RST for RST. */ | |
80 | if (otcph.rst) { | |
ff67e4e4 | 81 | pr_debug("RST is set\n"); |
764d8a9f PM |
82 | return; |
83 | } | |
84 | ||
85 | /* Check checksum. */ | |
86 | if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP, | |
87 | skb_checksum(oldskb, tcphoff, otcplen, 0))) { | |
ff67e4e4 | 88 | pr_debug("TCP checksum is invalid\n"); |
764d8a9f PM |
89 | return; |
90 | } | |
91 | ||
92 | memset(&fl, 0, sizeof(fl)); | |
93 | fl.proto = IPPROTO_TCP; | |
94 | ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr); | |
95 | ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr); | |
96 | fl.fl_ip_sport = otcph.dest; | |
97 | fl.fl_ip_dport = otcph.source; | |
beb8d13b | 98 | security_skb_classify_flow(oldskb, &fl); |
e10aad99 | 99 | dst = ip6_route_output(net, NULL, &fl); |
764d8a9f PM |
100 | if (dst == NULL) |
101 | return; | |
52479b62 | 102 | if (dst->error || xfrm_lookup(net, &dst, &fl, NULL, 0)) |
764d8a9f | 103 | return; |
764d8a9f PM |
104 | |
105 | hh_len = (dst->dev->hard_header_len + 15)&~15; | |
106 | nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) | |
107 | + sizeof(struct tcphdr) + dst->trailer_len, | |
108 | GFP_ATOMIC); | |
109 | ||
110 | if (!nskb) { | |
111 | if (net_ratelimit()) | |
ff67e4e4 | 112 | pr_debug("cannot alloc skb\n"); |
764d8a9f PM |
113 | dst_release(dst); |
114 | return; | |
115 | } | |
116 | ||
adf30907 | 117 | skb_dst_set(nskb, dst); |
764d8a9f PM |
118 | |
119 | skb_reserve(nskb, hh_len + dst->header_len); | |
120 | ||
1ced98e8 ACM |
121 | skb_put(nskb, sizeof(struct ipv6hdr)); |
122 | skb_reset_network_header(nskb); | |
0660e03f | 123 | ip6h = ipv6_hdr(nskb); |
764d8a9f PM |
124 | ip6h->version = 6; |
125 | ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT); | |
126 | ip6h->nexthdr = IPPROTO_TCP; | |
764d8a9f PM |
127 | ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr); |
128 | ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr); | |
129 | ||
130 | tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); | |
131 | /* Truncate to length (no data) */ | |
132 | tcph->doff = sizeof(struct tcphdr)/4; | |
133 | tcph->source = otcph.dest; | |
134 | tcph->dest = otcph.source; | |
135 | ||
136 | if (otcph.ack) { | |
137 | needs_ack = 0; | |
138 | tcph->seq = otcph.ack_seq; | |
139 | tcph->ack_seq = 0; | |
140 | } else { | |
141 | needs_ack = 1; | |
142 | tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin | |
143 | + otcplen - (otcph.doff<<2)); | |
144 | tcph->seq = 0; | |
145 | } | |
146 | ||
147 | /* Reset flags */ | |
148 | ((u_int8_t *)tcph)[13] = 0; | |
149 | tcph->rst = 1; | |
150 | tcph->ack = needs_ack; | |
151 | tcph->window = 0; | |
152 | tcph->urg_ptr = 0; | |
153 | tcph->check = 0; | |
154 | ||
155 | /* Adjust TCP checksum */ | |
0660e03f ACM |
156 | tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr, |
157 | &ipv6_hdr(nskb)->daddr, | |
764d8a9f | 158 | sizeof(struct tcphdr), IPPROTO_TCP, |
a47362a2 | 159 | csum_partial(tcph, |
764d8a9f PM |
160 | sizeof(struct tcphdr), 0)); |
161 | ||
08857fa7 YK |
162 | nf_ct_attach(nskb, oldskb); |
163 | ||
ef76bc23 | 164 | ip6_local_out(nskb); |
764d8a9f PM |
165 | } |
166 | ||
167 | static inline void | |
e10aad99 AD |
168 | send_unreach(struct net *net, struct sk_buff *skb_in, unsigned char code, |
169 | unsigned int hooknum) | |
764d8a9f | 170 | { |
6e23ae2a | 171 | if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL) |
e10aad99 | 172 | skb_in->dev = net->loopback_dev; |
764d8a9f | 173 | |
3ffe533c | 174 | icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0); |
764d8a9f PM |
175 | } |
176 | ||
d3c5ee6d | 177 | static unsigned int |
4b560b44 | 178 | reject_tg6(struct sk_buff *skb, const struct xt_action_param *par) |
764d8a9f | 179 | { |
7eb35586 JE |
180 | const struct ip6t_reject_info *reject = par->targinfo; |
181 | struct net *net = dev_net((par->in != NULL) ? par->in : par->out); | |
764d8a9f | 182 | |
0dc47877 | 183 | pr_debug("%s: medium point\n", __func__); |
1ab1457c YH |
184 | switch (reject->with) { |
185 | case IP6T_ICMP6_NO_ROUTE: | |
7eb35586 | 186 | send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum); |
1ab1457c YH |
187 | break; |
188 | case IP6T_ICMP6_ADM_PROHIBITED: | |
7eb35586 | 189 | send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum); |
1ab1457c YH |
190 | break; |
191 | case IP6T_ICMP6_NOT_NEIGHBOUR: | |
7eb35586 | 192 | send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum); |
1ab1457c YH |
193 | break; |
194 | case IP6T_ICMP6_ADDR_UNREACH: | |
7eb35586 | 195 | send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum); |
1ab1457c YH |
196 | break; |
197 | case IP6T_ICMP6_PORT_UNREACH: | |
7eb35586 | 198 | send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum); |
1ab1457c YH |
199 | break; |
200 | case IP6T_ICMP6_ECHOREPLY: | |
764d8a9f PM |
201 | /* Do nothing */ |
202 | break; | |
203 | case IP6T_TCP_RESET: | |
e10aad99 | 204 | send_reset(net, skb); |
764d8a9f PM |
205 | break; |
206 | default: | |
207 | if (net_ratelimit()) | |
ff67e4e4 | 208 | pr_info("case %u not handled yet\n", reject->with); |
764d8a9f PM |
209 | break; |
210 | } | |
211 | ||
212 | return NF_DROP; | |
213 | } | |
214 | ||
135367b8 | 215 | static int reject_tg6_check(const struct xt_tgchk_param *par) |
764d8a9f | 216 | { |
af5d6dc2 JE |
217 | const struct ip6t_reject_info *rejinfo = par->targinfo; |
218 | const struct ip6t_entry *e = par->entryinfo; | |
764d8a9f | 219 | |
764d8a9f | 220 | if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) { |
ff67e4e4 | 221 | pr_info("ECHOREPLY is not supported.\n"); |
d6b00a53 | 222 | return -EINVAL; |
764d8a9f PM |
223 | } else if (rejinfo->with == IP6T_TCP_RESET) { |
224 | /* Must specify that it's a TCP packet */ | |
3666ed1c JP |
225 | if (e->ipv6.proto != IPPROTO_TCP || |
226 | (e->ipv6.invflags & XT_INV_PROTO)) { | |
ff67e4e4 | 227 | pr_info("TCP_RESET illegal for non-tcp\n"); |
d6b00a53 | 228 | return -EINVAL; |
764d8a9f PM |
229 | } |
230 | } | |
d6b00a53 | 231 | return 0; |
764d8a9f PM |
232 | } |
233 | ||
d3c5ee6d | 234 | static struct xt_target reject_tg6_reg __read_mostly = { |
764d8a9f | 235 | .name = "REJECT", |
ee999d8b | 236 | .family = NFPROTO_IPV6, |
d3c5ee6d | 237 | .target = reject_tg6, |
7f939713 PM |
238 | .targetsize = sizeof(struct ip6t_reject_info), |
239 | .table = "filter", | |
6e23ae2a PM |
240 | .hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) | |
241 | (1 << NF_INET_LOCAL_OUT), | |
d3c5ee6d | 242 | .checkentry = reject_tg6_check, |
764d8a9f PM |
243 | .me = THIS_MODULE |
244 | }; | |
245 | ||
d3c5ee6d | 246 | static int __init reject_tg6_init(void) |
764d8a9f | 247 | { |
d3c5ee6d | 248 | return xt_register_target(&reject_tg6_reg); |
764d8a9f PM |
249 | } |
250 | ||
d3c5ee6d | 251 | static void __exit reject_tg6_exit(void) |
764d8a9f | 252 | { |
d3c5ee6d | 253 | xt_unregister_target(&reject_tg6_reg); |
764d8a9f PM |
254 | } |
255 | ||
d3c5ee6d JE |
256 | module_init(reject_tg6_init); |
257 | module_exit(reject_tg6_exit); |