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.
18 #include <linux/module.h>
19 #include <linux/skbuff.h>
20 #include <linux/icmpv6.h>
21 #include <linux/netdevice.h>
25 #include <net/ip6_checksum.h>
26 #include <net/ip6_fib.h>
27 #include <net/ip6_route.h>
29 #include <linux/netfilter/x_tables.h>
30 #include <linux/netfilter_ipv6/ip6_tables.h>
31 #include <linux/netfilter_ipv6/ip6t_REJECT.h>
33 MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
34 MODULE_DESCRIPTION("IP6 tables REJECT target module");
35 MODULE_LICENSE("GPL");
40 #define DEBUGP(format, args...)
44 static void send_reset(struct sk_buff
*oldskb
)
47 struct tcphdr otcph
, *tcph
;
48 unsigned int otcplen
, hh_len
;
49 int tcphoff
, needs_ack
;
50 struct ipv6hdr
*oip6h
= ipv6_hdr(oldskb
), *ip6h
;
51 struct dst_entry
*dst
= NULL
;
55 if ((!(ipv6_addr_type(&oip6h
->saddr
) & IPV6_ADDR_UNICAST
)) ||
56 (!(ipv6_addr_type(&oip6h
->daddr
) & IPV6_ADDR_UNICAST
))) {
57 DEBUGP("ip6t_REJECT: addr is not unicast.\n");
61 proto
= oip6h
->nexthdr
;
62 tcphoff
= ipv6_skip_exthdr(oldskb
, ((u8
*)(oip6h
+1) - oldskb
->data
), &proto
);
64 if ((tcphoff
< 0) || (tcphoff
> oldskb
->len
)) {
65 DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
69 otcplen
= oldskb
->len
- tcphoff
;
71 /* IP header checks: fragment, too short. */
72 if ((proto
!= IPPROTO_TCP
) || (otcplen
< sizeof(struct tcphdr
))) {
73 DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n",
78 if (skb_copy_bits(oldskb
, tcphoff
, &otcph
, sizeof(struct tcphdr
)))
83 DEBUGP("ip6t_REJECT: RST is set\n");
88 if (csum_ipv6_magic(&oip6h
->saddr
, &oip6h
->daddr
, otcplen
, IPPROTO_TCP
,
89 skb_checksum(oldskb
, tcphoff
, otcplen
, 0))) {
90 DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
94 memset(&fl
, 0, sizeof(fl
));
95 fl
.proto
= IPPROTO_TCP
;
96 ipv6_addr_copy(&fl
.fl6_src
, &oip6h
->daddr
);
97 ipv6_addr_copy(&fl
.fl6_dst
, &oip6h
->saddr
);
98 fl
.fl_ip_sport
= otcph
.dest
;
99 fl
.fl_ip_dport
= otcph
.source
;
100 security_skb_classify_flow(oldskb
, &fl
);
101 dst
= ip6_route_output(NULL
, &fl
);
104 if (dst
->error
|| xfrm_lookup(&dst
, &fl
, NULL
, 0))
107 hh_len
= (dst
->dev
->hard_header_len
+ 15)&~15;
108 nskb
= alloc_skb(hh_len
+ 15 + dst
->header_len
+ sizeof(struct ipv6hdr
)
109 + sizeof(struct tcphdr
) + dst
->trailer_len
,
114 printk("ip6t_REJECT: Can't alloc skb\n");
121 skb_reserve(nskb
, hh_len
+ dst
->header_len
);
123 skb_put(nskb
, sizeof(struct ipv6hdr
));
124 skb_reset_network_header(nskb
);
125 ip6h
= ipv6_hdr(nskb
);
127 ip6h
->hop_limit
= dst_metric(dst
, RTAX_HOPLIMIT
);
128 ip6h
->nexthdr
= IPPROTO_TCP
;
129 ipv6_addr_copy(&ip6h
->saddr
, &oip6h
->daddr
);
130 ipv6_addr_copy(&ip6h
->daddr
, &oip6h
->saddr
);
132 tcph
= (struct tcphdr
*)skb_put(nskb
, sizeof(struct tcphdr
));
133 /* Truncate to length (no data) */
134 tcph
->doff
= sizeof(struct tcphdr
)/4;
135 tcph
->source
= otcph
.dest
;
136 tcph
->dest
= otcph
.source
;
140 tcph
->seq
= otcph
.ack_seq
;
144 tcph
->ack_seq
= htonl(ntohl(otcph
.seq
) + otcph
.syn
+ otcph
.fin
145 + otcplen
- (otcph
.doff
<<2));
150 ((u_int8_t
*)tcph
)[13] = 0;
152 tcph
->ack
= needs_ack
;
157 /* Adjust TCP checksum */
158 tcph
->check
= csum_ipv6_magic(&ipv6_hdr(nskb
)->saddr
,
159 &ipv6_hdr(nskb
)->daddr
,
160 sizeof(struct tcphdr
), IPPROTO_TCP
,
161 csum_partial((char *)tcph
,
162 sizeof(struct tcphdr
), 0));
164 nf_ct_attach(nskb
, oldskb
);
170 send_unreach(struct sk_buff
*skb_in
, unsigned char code
, unsigned int hooknum
)
172 if (hooknum
== NF_IP6_LOCAL_OUT
&& skb_in
->dev
== NULL
)
173 skb_in
->dev
= &loopback_dev
;
175 icmpv6_send(skb_in
, ICMPV6_DEST_UNREACH
, code
, 0, NULL
);
178 static unsigned int reject6_target(struct sk_buff
*skb
,
179 const struct net_device
*in
,
180 const struct net_device
*out
,
181 unsigned int hooknum
,
182 const struct xt_target
*target
,
183 const void *targinfo
)
185 const struct ip6t_reject_info
*reject
= targinfo
;
187 DEBUGP(KERN_DEBUG
"%s: medium point\n", __FUNCTION__
);
188 /* WARNING: This code causes reentry within ip6tables.
189 This means that the ip6tables jump stack is now crap. We
190 must return an absolute verdict. --RR */
191 switch (reject
->with
) {
192 case IP6T_ICMP6_NO_ROUTE
:
193 send_unreach(skb
, ICMPV6_NOROUTE
, hooknum
);
195 case IP6T_ICMP6_ADM_PROHIBITED
:
196 send_unreach(skb
, ICMPV6_ADM_PROHIBITED
, hooknum
);
198 case IP6T_ICMP6_NOT_NEIGHBOUR
:
199 send_unreach(skb
, ICMPV6_NOT_NEIGHBOUR
, hooknum
);
201 case IP6T_ICMP6_ADDR_UNREACH
:
202 send_unreach(skb
, ICMPV6_ADDR_UNREACH
, hooknum
);
204 case IP6T_ICMP6_PORT_UNREACH
:
205 send_unreach(skb
, ICMPV6_PORT_UNREACH
, hooknum
);
207 case IP6T_ICMP6_ECHOREPLY
:
215 printk(KERN_WARNING
"ip6t_REJECT: case %u not handled yet\n", reject
->with
);
222 static int check(const char *tablename
,
224 const struct xt_target
*target
,
226 unsigned int hook_mask
)
228 const struct ip6t_reject_info
*rejinfo
= targinfo
;
229 const struct ip6t_entry
*e
= entry
;
231 if (rejinfo
->with
== IP6T_ICMP6_ECHOREPLY
) {
232 printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
234 } else if (rejinfo
->with
== IP6T_TCP_RESET
) {
235 /* Must specify that it's a TCP packet */
236 if (e
->ipv6
.proto
!= IPPROTO_TCP
237 || (e
->ipv6
.invflags
& XT_INV_PROTO
)) {
238 DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
245 static struct xt_target ip6t_reject_reg
= {
248 .target
= reject6_target
,
249 .targetsize
= sizeof(struct ip6t_reject_info
),
251 .hooks
= (1 << NF_IP6_LOCAL_IN
) | (1 << NF_IP6_FORWARD
) |
252 (1 << NF_IP6_LOCAL_OUT
),
257 static int __init
ip6t_reject_init(void)
259 return xt_register_target(&ip6t_reject_reg
);
262 static void __exit
ip6t_reject_fini(void)
264 xt_unregister_target(&ip6t_reject_reg
);
267 module_init(ip6t_reject_init
);
268 module_exit(ip6t_reject_fini
);