Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 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 | */ |
| 17 | |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 18 | #include <linux/module.h> |
| 19 | #include <linux/skbuff.h> |
| 20 | #include <linux/icmpv6.h> |
| 21 | #include <linux/netdevice.h> |
| 22 | #include <net/ipv6.h> |
| 23 | #include <net/tcp.h> |
| 24 | #include <net/icmp.h> |
| 25 | #include <net/ip6_checksum.h> |
| 26 | #include <net/ip6_fib.h> |
| 27 | #include <net/ip6_route.h> |
| 28 | #include <net/flow.h> |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 29 | #include <linux/netfilter/x_tables.h> |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 30 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 31 | #include <linux/netfilter_ipv6/ip6t_REJECT.h> |
| 32 | |
| 33 | MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>"); |
| 34 | MODULE_DESCRIPTION("IP6 tables REJECT target module"); |
| 35 | MODULE_LICENSE("GPL"); |
| 36 | |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 37 | /* Send RST reply */ |
| 38 | static void send_reset(struct sk_buff *oldskb) |
| 39 | { |
| 40 | struct sk_buff *nskb; |
| 41 | struct tcphdr otcph, *tcph; |
| 42 | unsigned int otcplen, hh_len; |
| 43 | int tcphoff, needs_ack; |
Arnaldo Carvalho de Melo | 0660e03 | 2007-04-25 17:54:47 -0700 | [diff] [blame] | 44 | struct ipv6hdr *oip6h = ipv6_hdr(oldskb), *ip6h; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 45 | struct dst_entry *dst = NULL; |
| 46 | u8 proto; |
| 47 | struct flowi fl; |
| 48 | |
| 49 | if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || |
| 50 | (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 51 | pr_debug("ip6t_REJECT: addr is not unicast.\n"); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 52 | return; |
| 53 | } |
| 54 | |
| 55 | proto = oip6h->nexthdr; |
| 56 | tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto); |
| 57 | |
| 58 | if ((tcphoff < 0) || (tcphoff > oldskb->len)) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 59 | pr_debug("ip6t_REJECT: Can't get TCP header.\n"); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 60 | return; |
| 61 | } |
| 62 | |
| 63 | otcplen = oldskb->len - tcphoff; |
| 64 | |
| 65 | /* IP header checks: fragment, too short. */ |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 66 | if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 67 | pr_debug("ip6t_REJECT: proto(%d) != IPPROTO_TCP, " |
| 68 | "or too short. otcplen = %d\n", |
| 69 | proto, otcplen); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 70 | return; |
| 71 | } |
| 72 | |
| 73 | if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr))) |
| 74 | BUG(); |
| 75 | |
| 76 | /* No RST for RST. */ |
| 77 | if (otcph.rst) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 78 | pr_debug("ip6t_REJECT: RST is set\n"); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 79 | return; |
| 80 | } |
| 81 | |
| 82 | /* Check checksum. */ |
| 83 | if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP, |
| 84 | skb_checksum(oldskb, tcphoff, otcplen, 0))) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 85 | pr_debug("ip6t_REJECT: TCP checksum is invalid\n"); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 86 | return; |
| 87 | } |
| 88 | |
| 89 | memset(&fl, 0, sizeof(fl)); |
| 90 | fl.proto = IPPROTO_TCP; |
| 91 | ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr); |
| 92 | ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr); |
| 93 | fl.fl_ip_sport = otcph.dest; |
| 94 | fl.fl_ip_dport = otcph.source; |
Venkat Yekkirala | beb8d13 | 2006-08-04 23:12:42 -0700 | [diff] [blame] | 95 | security_skb_classify_flow(oldskb, &fl); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 96 | dst = ip6_route_output(NULL, &fl); |
| 97 | if (dst == NULL) |
| 98 | return; |
Patrick McHardy | e104411b | 2005-09-08 15:11:55 -0700 | [diff] [blame] | 99 | if (dst->error || xfrm_lookup(&dst, &fl, NULL, 0)) |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 100 | return; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 101 | |
| 102 | hh_len = (dst->dev->hard_header_len + 15)&~15; |
| 103 | nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) |
| 104 | + sizeof(struct tcphdr) + dst->trailer_len, |
| 105 | GFP_ATOMIC); |
| 106 | |
| 107 | if (!nskb) { |
| 108 | if (net_ratelimit()) |
| 109 | printk("ip6t_REJECT: Can't alloc skb\n"); |
| 110 | dst_release(dst); |
| 111 | return; |
| 112 | } |
| 113 | |
| 114 | nskb->dst = dst; |
| 115 | |
| 116 | skb_reserve(nskb, hh_len + dst->header_len); |
| 117 | |
Arnaldo Carvalho de Melo | 1ced98e | 2007-03-10 19:57:15 -0300 | [diff] [blame] | 118 | skb_put(nskb, sizeof(struct ipv6hdr)); |
| 119 | skb_reset_network_header(nskb); |
Arnaldo Carvalho de Melo | 0660e03 | 2007-04-25 17:54:47 -0700 | [diff] [blame] | 120 | ip6h = ipv6_hdr(nskb); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 121 | ip6h->version = 6; |
| 122 | ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT); |
| 123 | ip6h->nexthdr = IPPROTO_TCP; |
| 124 | ip6h->payload_len = htons(sizeof(struct tcphdr)); |
| 125 | ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr); |
| 126 | ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr); |
| 127 | |
| 128 | tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); |
| 129 | /* Truncate to length (no data) */ |
| 130 | tcph->doff = sizeof(struct tcphdr)/4; |
| 131 | tcph->source = otcph.dest; |
| 132 | tcph->dest = otcph.source; |
| 133 | |
| 134 | if (otcph.ack) { |
| 135 | needs_ack = 0; |
| 136 | tcph->seq = otcph.ack_seq; |
| 137 | tcph->ack_seq = 0; |
| 138 | } else { |
| 139 | needs_ack = 1; |
| 140 | tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin |
| 141 | + otcplen - (otcph.doff<<2)); |
| 142 | tcph->seq = 0; |
| 143 | } |
| 144 | |
| 145 | /* Reset flags */ |
| 146 | ((u_int8_t *)tcph)[13] = 0; |
| 147 | tcph->rst = 1; |
| 148 | tcph->ack = needs_ack; |
| 149 | tcph->window = 0; |
| 150 | tcph->urg_ptr = 0; |
| 151 | tcph->check = 0; |
| 152 | |
| 153 | /* Adjust TCP checksum */ |
Arnaldo Carvalho de Melo | 0660e03 | 2007-04-25 17:54:47 -0700 | [diff] [blame] | 154 | tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr, |
| 155 | &ipv6_hdr(nskb)->daddr, |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 156 | sizeof(struct tcphdr), IPPROTO_TCP, |
Jan Engelhardt | a47362a | 2007-07-07 22:16:55 -0700 | [diff] [blame] | 157 | csum_partial(tcph, |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 158 | sizeof(struct tcphdr), 0)); |
| 159 | |
Yasuyuki Kozakai | 08857fa | 2006-02-15 15:23:28 -0800 | [diff] [blame] | 160 | nf_ct_attach(nskb, oldskb); |
| 161 | |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 162 | NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev, |
| 163 | dst_output); |
| 164 | } |
| 165 | |
| 166 | static inline void |
| 167 | send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum) |
| 168 | { |
| 169 | if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL) |
Eric W. Biederman | 2774c7a | 2007-09-26 22:10:56 -0700 | [diff] [blame] | 170 | skb_in->dev = init_net.loopback_dev; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 171 | |
| 172 | icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL); |
| 173 | } |
| 174 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 175 | static unsigned int reject6_target(struct sk_buff *skb, |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 176 | const struct net_device *in, |
| 177 | const struct net_device *out, |
| 178 | unsigned int hooknum, |
Patrick McHardy | c498673 | 2006-03-20 18:02:56 -0800 | [diff] [blame] | 179 | const struct xt_target *target, |
Patrick McHardy | fe1cb10 | 2006-08-22 00:35:47 -0700 | [diff] [blame] | 180 | const void *targinfo) |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 181 | { |
| 182 | const struct ip6t_reject_info *reject = targinfo; |
| 183 | |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 184 | pr_debug("%s: medium point\n", __FUNCTION__); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 185 | /* WARNING: This code causes reentry within ip6tables. |
| 186 | This means that the ip6tables jump stack is now crap. We |
| 187 | must return an absolute verdict. --RR */ |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 188 | switch (reject->with) { |
| 189 | case IP6T_ICMP6_NO_ROUTE: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 190 | send_unreach(skb, ICMPV6_NOROUTE, hooknum); |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 191 | break; |
| 192 | case IP6T_ICMP6_ADM_PROHIBITED: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 193 | send_unreach(skb, ICMPV6_ADM_PROHIBITED, hooknum); |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 194 | break; |
| 195 | case IP6T_ICMP6_NOT_NEIGHBOUR: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 196 | send_unreach(skb, ICMPV6_NOT_NEIGHBOUR, hooknum); |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 197 | break; |
| 198 | case IP6T_ICMP6_ADDR_UNREACH: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 199 | send_unreach(skb, ICMPV6_ADDR_UNREACH, hooknum); |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 200 | break; |
| 201 | case IP6T_ICMP6_PORT_UNREACH: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 202 | send_unreach(skb, ICMPV6_PORT_UNREACH, hooknum); |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 203 | break; |
| 204 | case IP6T_ICMP6_ECHOREPLY: |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 205 | /* Do nothing */ |
| 206 | break; |
| 207 | case IP6T_TCP_RESET: |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame^] | 208 | send_reset(skb); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 209 | break; |
| 210 | default: |
| 211 | if (net_ratelimit()) |
| 212 | printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with); |
| 213 | break; |
| 214 | } |
| 215 | |
| 216 | return NF_DROP; |
| 217 | } |
| 218 | |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 219 | static bool check(const char *tablename, |
| 220 | const void *entry, |
| 221 | const struct xt_target *target, |
| 222 | void *targinfo, |
| 223 | unsigned int hook_mask) |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 224 | { |
YOSHIFUJI Hideaki | 1ab1457 | 2007-02-09 23:24:49 +0900 | [diff] [blame] | 225 | const struct ip6t_reject_info *rejinfo = targinfo; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 226 | const struct ip6t_entry *e = entry; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 227 | |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 228 | if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) { |
| 229 | printk("ip6t_REJECT: ECHOREPLY is not supported.\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 230 | return false; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 231 | } else if (rejinfo->with == IP6T_TCP_RESET) { |
| 232 | /* Must specify that it's a TCP packet */ |
| 233 | if (e->ipv6.proto != IPPROTO_TCP |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 234 | || (e->ipv6.invflags & XT_INV_PROTO)) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 235 | printk("ip6t_REJECT: TCP_RESET illegal for non-tcp\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 236 | return false; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 237 | } |
| 238 | } |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 239 | return true; |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 240 | } |
| 241 | |
Patrick McHardy | 9f15c53 | 2007-07-07 22:22:02 -0700 | [diff] [blame] | 242 | static struct xt_target ip6t_reject_reg __read_mostly = { |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 243 | .name = "REJECT", |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 244 | .family = AF_INET6, |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 245 | .target = reject6_target, |
Patrick McHardy | 7f93971 | 2006-03-20 18:01:43 -0800 | [diff] [blame] | 246 | .targetsize = sizeof(struct ip6t_reject_info), |
| 247 | .table = "filter", |
| 248 | .hooks = (1 << NF_IP6_LOCAL_IN) | (1 << NF_IP6_FORWARD) | |
| 249 | (1 << NF_IP6_LOCAL_OUT), |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 250 | .checkentry = check, |
| 251 | .me = THIS_MODULE |
| 252 | }; |
| 253 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 254 | static int __init ip6t_reject_init(void) |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 255 | { |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 256 | return xt_register_target(&ip6t_reject_reg); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 257 | } |
| 258 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 259 | static void __exit ip6t_reject_fini(void) |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 260 | { |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 261 | xt_unregister_target(&ip6t_reject_reg); |
Patrick McHardy | 764d8a9 | 2005-08-21 23:31:06 -0700 | [diff] [blame] | 262 | } |
| 263 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 264 | module_init(ip6t_reject_init); |
| 265 | module_exit(ip6t_reject_fini); |