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/gfp.h>
19 #include <linux/module.h>
20 #include <linux/skbuff.h>
21 #include <linux/icmpv6.h>
22 #include <linux/netdevice.h>
26 #include <net/ip6_checksum.h>
27 #include <net/ip6_fib.h>
28 #include <net/ip6_route.h>
30 #include <linux/netfilter/x_tables.h>
31 #include <linux/netfilter_ipv6/ip6_tables.h>
32 #include <linux/netfilter_ipv6/ip6t_REJECT.h>
34 MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
35 MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
36 MODULE_LICENSE("GPL");
39 static void send_reset(struct net
*net
, struct sk_buff
*oldskb
)
42 struct tcphdr otcph
, *tcph
;
43 unsigned int otcplen
, hh_len
;
44 int tcphoff
, needs_ack
;
45 const struct ipv6hdr
*oip6h
= ipv6_hdr(oldskb
);
47 struct dst_entry
*dst
= NULL
;
51 if ((!(ipv6_addr_type(&oip6h
->saddr
) & IPV6_ADDR_UNICAST
)) ||
52 (!(ipv6_addr_type(&oip6h
->daddr
) & IPV6_ADDR_UNICAST
))) {
53 pr_debug("ip6t_REJECT: addr is not unicast.\n");
57 proto
= oip6h
->nexthdr
;
58 tcphoff
= ipv6_skip_exthdr(oldskb
, ((u8
*)(oip6h
+1) - oldskb
->data
), &proto
);
60 if ((tcphoff
< 0) || (tcphoff
> oldskb
->len
)) {
61 pr_debug("ip6t_REJECT: Can't get TCP header.\n");
65 otcplen
= oldskb
->len
- tcphoff
;
67 /* IP header checks: fragment, too short. */
68 if (proto
!= IPPROTO_TCP
|| otcplen
< sizeof(struct tcphdr
)) {
69 pr_debug("ip6t_REJECT: proto(%d) != IPPROTO_TCP, "
70 "or too short. otcplen = %d\n",
75 if (skb_copy_bits(oldskb
, tcphoff
, &otcph
, sizeof(struct tcphdr
)))
80 pr_debug("ip6t_REJECT: RST is set\n");
85 if (csum_ipv6_magic(&oip6h
->saddr
, &oip6h
->daddr
, otcplen
, IPPROTO_TCP
,
86 skb_checksum(oldskb
, tcphoff
, otcplen
, 0))) {
87 pr_debug("ip6t_REJECT: TCP checksum is invalid\n");
91 memset(&fl
, 0, sizeof(fl
));
92 fl
.proto
= IPPROTO_TCP
;
93 ipv6_addr_copy(&fl
.fl6_src
, &oip6h
->daddr
);
94 ipv6_addr_copy(&fl
.fl6_dst
, &oip6h
->saddr
);
95 fl
.fl_ip_sport
= otcph
.dest
;
96 fl
.fl_ip_dport
= otcph
.source
;
97 security_skb_classify_flow(oldskb
, &fl
);
98 dst
= ip6_route_output(net
, NULL
, &fl
);
101 if (dst
->error
|| xfrm_lookup(net
, &dst
, &fl
, NULL
, 0))
104 hh_len
= (dst
->dev
->hard_header_len
+ 15)&~15;
105 nskb
= alloc_skb(hh_len
+ 15 + dst
->header_len
+ sizeof(struct ipv6hdr
)
106 + sizeof(struct tcphdr
) + dst
->trailer_len
,
111 printk("ip6t_REJECT: Can't alloc skb\n");
116 skb_dst_set(nskb
, dst
);
118 skb_reserve(nskb
, hh_len
+ dst
->header_len
);
120 skb_put(nskb
, sizeof(struct ipv6hdr
));
121 skb_reset_network_header(nskb
);
122 ip6h
= ipv6_hdr(nskb
);
124 ip6h
->hop_limit
= dst_metric(dst
, RTAX_HOPLIMIT
);
125 ip6h
->nexthdr
= IPPROTO_TCP
;
126 ipv6_addr_copy(&ip6h
->saddr
, &oip6h
->daddr
);
127 ipv6_addr_copy(&ip6h
->daddr
, &oip6h
->saddr
);
129 tcph
= (struct tcphdr
*)skb_put(nskb
, sizeof(struct tcphdr
));
130 /* Truncate to length (no data) */
131 tcph
->doff
= sizeof(struct tcphdr
)/4;
132 tcph
->source
= otcph
.dest
;
133 tcph
->dest
= otcph
.source
;
137 tcph
->seq
= otcph
.ack_seq
;
141 tcph
->ack_seq
= htonl(ntohl(otcph
.seq
) + otcph
.syn
+ otcph
.fin
142 + otcplen
- (otcph
.doff
<<2));
147 ((u_int8_t
*)tcph
)[13] = 0;
149 tcph
->ack
= needs_ack
;
154 /* Adjust TCP checksum */
155 tcph
->check
= csum_ipv6_magic(&ipv6_hdr(nskb
)->saddr
,
156 &ipv6_hdr(nskb
)->daddr
,
157 sizeof(struct tcphdr
), IPPROTO_TCP
,
159 sizeof(struct tcphdr
), 0));
161 nf_ct_attach(nskb
, oldskb
);
167 send_unreach(struct net
*net
, struct sk_buff
*skb_in
, unsigned char code
,
168 unsigned int hooknum
)
170 if (hooknum
== NF_INET_LOCAL_OUT
&& skb_in
->dev
== NULL
)
171 skb_in
->dev
= net
->loopback_dev
;
173 icmpv6_send(skb_in
, ICMPV6_DEST_UNREACH
, code
, 0);
177 reject_tg6(struct sk_buff
*skb
, const struct xt_target_param
*par
)
179 const struct ip6t_reject_info
*reject
= par
->targinfo
;
180 struct net
*net
= dev_net((par
->in
!= NULL
) ? par
->in
: par
->out
);
182 pr_debug("%s: medium point\n", __func__
);
183 /* WARNING: This code causes reentry within ip6tables.
184 This means that the ip6tables jump stack is now crap. We
185 must return an absolute verdict. --RR */
186 switch (reject
->with
) {
187 case IP6T_ICMP6_NO_ROUTE
:
188 send_unreach(net
, skb
, ICMPV6_NOROUTE
, par
->hooknum
);
190 case IP6T_ICMP6_ADM_PROHIBITED
:
191 send_unreach(net
, skb
, ICMPV6_ADM_PROHIBITED
, par
->hooknum
);
193 case IP6T_ICMP6_NOT_NEIGHBOUR
:
194 send_unreach(net
, skb
, ICMPV6_NOT_NEIGHBOUR
, par
->hooknum
);
196 case IP6T_ICMP6_ADDR_UNREACH
:
197 send_unreach(net
, skb
, ICMPV6_ADDR_UNREACH
, par
->hooknum
);
199 case IP6T_ICMP6_PORT_UNREACH
:
200 send_unreach(net
, skb
, ICMPV6_PORT_UNREACH
, par
->hooknum
);
202 case IP6T_ICMP6_ECHOREPLY
:
206 send_reset(net
, skb
);
210 printk(KERN_WARNING
"ip6t_REJECT: case %u not handled yet\n", reject
->with
);
217 static bool reject_tg6_check(const struct xt_tgchk_param
*par
)
219 const struct ip6t_reject_info
*rejinfo
= par
->targinfo
;
220 const struct ip6t_entry
*e
= par
->entryinfo
;
222 if (rejinfo
->with
== IP6T_ICMP6_ECHOREPLY
) {
223 printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
225 } else if (rejinfo
->with
== IP6T_TCP_RESET
) {
226 /* Must specify that it's a TCP packet */
227 if (e
->ipv6
.proto
!= IPPROTO_TCP
||
228 (e
->ipv6
.invflags
& XT_INV_PROTO
)) {
229 printk("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
236 static struct xt_target reject_tg6_reg __read_mostly
= {
238 .family
= NFPROTO_IPV6
,
239 .target
= reject_tg6
,
240 .targetsize
= sizeof(struct ip6t_reject_info
),
242 .hooks
= (1 << NF_INET_LOCAL_IN
) | (1 << NF_INET_FORWARD
) |
243 (1 << NF_INET_LOCAL_OUT
),
244 .checkentry
= reject_tg6_check
,
248 static int __init
reject_tg6_init(void)
250 return xt_register_target(&reject_tg6_reg
);
253 static void __exit
reject_tg6_exit(void)
255 xt_unregister_target(&reject_tg6_reg
);
258 module_init(reject_tg6_init
);
259 module_exit(reject_tg6_exit
);