2 * IP6 tables REJECT target module
3 * Linux INET6 implementation
5 * Copyright (C)2003 USAGI/WIDE Project
8 * Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
10 * Based on net/ipv4/netfilter/ipt_REJECT.c
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.
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/gfp.h>
20 #include <linux/module.h>
21 #include <linux/skbuff.h>
22 #include <linux/icmpv6.h>
23 #include <linux/netdevice.h>
27 #include <net/ip6_checksum.h>
28 #include <net/ip6_fib.h>
29 #include <net/ip6_route.h>
31 #include <linux/netfilter/x_tables.h>
32 #include <linux/netfilter_ipv6/ip6_tables.h>
33 #include <linux/netfilter_ipv6/ip6t_REJECT.h>
35 MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
36 MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
37 MODULE_LICENSE("GPL");
40 static void send_reset(struct net *net, struct sk_buff *oldskb)
43 struct tcphdr otcph, *tcph;
44 unsigned int otcplen, hh_len;
45 int tcphoff, needs_ack;
46 const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
48 struct dst_entry *dst = NULL;
52 if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
53 (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
54 pr_debug("addr is not unicast.\n");
58 proto = oip6h->nexthdr;
59 tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
61 if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
62 pr_debug("Cannot get TCP header.\n");
66 otcplen = oldskb->len - tcphoff;
68 /* IP header checks: fragment, too short. */
69 if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) {
70 pr_debug("proto(%d) != IPPROTO_TCP, "
71 "or too short. otcplen = %d\n",
76 if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
81 pr_debug("RST is set\n");
86 if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
87 skb_checksum(oldskb, tcphoff, otcplen, 0))) {
88 pr_debug("TCP checksum is invalid\n");
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;
98 security_skb_classify_flow(oldskb, &fl);
99 dst = ip6_route_output(net, NULL, &fl);
100 if (dst == NULL || dst->error) {
104 dst = xfrm_lookup(net, dst, &fl, NULL, 0);
108 hh_len = (dst->dev->hard_header_len + 15)&~15;
109 nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
110 + sizeof(struct tcphdr) + dst->trailer_len,
115 pr_debug("cannot alloc skb\n");
120 skb_dst_set(nskb, dst);
122 skb_reserve(nskb, hh_len + dst->header_len);
124 skb_put(nskb, sizeof(struct ipv6hdr));
125 skb_reset_network_header(nskb);
126 ip6h = ipv6_hdr(nskb);
128 ip6h->hop_limit = ip6_dst_hoplimit(dst);
129 ip6h->nexthdr = IPPROTO_TCP;
130 ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
131 ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
133 tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
134 /* Truncate to length (no data) */
135 tcph->doff = sizeof(struct tcphdr)/4;
136 tcph->source = otcph.dest;
137 tcph->dest = otcph.source;
141 tcph->seq = otcph.ack_seq;
145 tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
146 + otcplen - (otcph.doff<<2));
151 ((u_int8_t *)tcph)[13] = 0;
153 tcph->ack = needs_ack;
158 /* Adjust TCP checksum */
159 tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
160 &ipv6_hdr(nskb)->daddr,
161 sizeof(struct tcphdr), IPPROTO_TCP,
163 sizeof(struct tcphdr), 0));
165 nf_ct_attach(nskb, oldskb);
171 send_unreach(struct net *net, struct sk_buff *skb_in, unsigned char code,
172 unsigned int hooknum)
174 if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
175 skb_in->dev = net->loopback_dev;
177 icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
181 reject_tg6(struct sk_buff *skb, const struct xt_action_param *par)
183 const struct ip6t_reject_info *reject = par->targinfo;
184 struct net *net = dev_net((par->in != NULL) ? par->in : par->out);
186 pr_debug("%s: medium point\n", __func__);
187 switch (reject->with) {
188 case IP6T_ICMP6_NO_ROUTE:
189 send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum);
191 case IP6T_ICMP6_ADM_PROHIBITED:
192 send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum);
194 case IP6T_ICMP6_NOT_NEIGHBOUR:
195 send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum);
197 case IP6T_ICMP6_ADDR_UNREACH:
198 send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum);
200 case IP6T_ICMP6_PORT_UNREACH:
201 send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum);
203 case IP6T_ICMP6_ECHOREPLY:
207 send_reset(net, skb);
211 pr_info("case %u not handled yet\n", reject->with);
218 static int reject_tg6_check(const struct xt_tgchk_param *par)
220 const struct ip6t_reject_info *rejinfo = par->targinfo;
221 const struct ip6t_entry *e = par->entryinfo;
223 if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
224 pr_info("ECHOREPLY is not supported.\n");
226 } else if (rejinfo->with == IP6T_TCP_RESET) {
227 /* Must specify that it's a TCP packet */
228 if (e->ipv6.proto != IPPROTO_TCP ||
229 (e->ipv6.invflags & XT_INV_PROTO)) {
230 pr_info("TCP_RESET illegal for non-tcp\n");
237 static struct xt_target reject_tg6_reg __read_mostly = {
239 .family = NFPROTO_IPV6,
240 .target = reject_tg6,
241 .targetsize = sizeof(struct ip6t_reject_info),
243 .hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
244 (1 << NF_INET_LOCAL_OUT),
245 .checkentry = reject_tg6_check,
249 static int __init reject_tg6_init(void)
251 return xt_register_target(&reject_tg6_reg);
254 static void __exit reject_tg6_exit(void)
256 xt_unregister_target(&reject_tg6_reg);
259 module_init(reject_tg6_init);
260 module_exit(reject_tg6_exit);