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
.flowi_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
);