Jan Engelhardt | 2cbc78a | 2012-09-21 11:41:34 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * (C) 1999-2001 Paul `Rusty' Russell |
| 3 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> |
| 4 | * Copyright (c) 2011 Patrick McHardy <kaber@trash.net> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | * |
| 10 | * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6 |
| 11 | * NAT funded by Astaro. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/if.h> |
| 15 | #include <linux/inetdevice.h> |
| 16 | #include <linux/ip.h> |
| 17 | #include <linux/kernel.h> |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/netdevice.h> |
| 20 | #include <linux/netfilter.h> |
| 21 | #include <linux/types.h> |
| 22 | #include <linux/netfilter_ipv4.h> |
| 23 | #include <linux/netfilter_ipv6.h> |
| 24 | #include <linux/netfilter/x_tables.h> |
| 25 | #include <net/addrconf.h> |
| 26 | #include <net/checksum.h> |
| 27 | #include <net/protocol.h> |
| 28 | #include <net/netfilter/nf_nat.h> |
| 29 | |
| 30 | static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT; |
| 31 | |
| 32 | static unsigned int |
| 33 | redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par) |
| 34 | { |
| 35 | const struct nf_nat_range *range = par->targinfo; |
| 36 | struct nf_nat_range newrange; |
| 37 | struct in6_addr newdst; |
| 38 | enum ip_conntrack_info ctinfo; |
| 39 | struct nf_conn *ct; |
| 40 | |
| 41 | ct = nf_ct_get(skb, &ctinfo); |
| 42 | if (par->hooknum == NF_INET_LOCAL_OUT) |
| 43 | newdst = loopback_addr; |
| 44 | else { |
| 45 | struct inet6_dev *idev; |
| 46 | struct inet6_ifaddr *ifa; |
| 47 | bool addr = false; |
| 48 | |
| 49 | rcu_read_lock(); |
| 50 | idev = __in6_dev_get(skb->dev); |
| 51 | if (idev != NULL) { |
| 52 | list_for_each_entry(ifa, &idev->addr_list, if_list) { |
| 53 | newdst = ifa->addr; |
| 54 | addr = true; |
| 55 | break; |
| 56 | } |
| 57 | } |
| 58 | rcu_read_unlock(); |
| 59 | |
| 60 | if (!addr) |
| 61 | return NF_DROP; |
| 62 | } |
| 63 | |
| 64 | newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; |
| 65 | newrange.min_addr.in6 = newdst; |
| 66 | newrange.max_addr.in6 = newdst; |
| 67 | newrange.min_proto = range->min_proto; |
| 68 | newrange.max_proto = range->max_proto; |
| 69 | |
| 70 | return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); |
| 71 | } |
| 72 | |
| 73 | static int redirect_tg6_checkentry(const struct xt_tgchk_param *par) |
| 74 | { |
| 75 | const struct nf_nat_range *range = par->targinfo; |
| 76 | |
| 77 | if (range->flags & NF_NAT_RANGE_MAP_IPS) |
| 78 | return -EINVAL; |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | /* FIXME: Take multiple ranges --RR */ |
| 83 | static int redirect_tg4_check(const struct xt_tgchk_param *par) |
| 84 | { |
| 85 | const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo; |
| 86 | |
| 87 | if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) { |
| 88 | pr_debug("bad MAP_IPS.\n"); |
| 89 | return -EINVAL; |
| 90 | } |
| 91 | if (mr->rangesize != 1) { |
| 92 | pr_debug("bad rangesize %u.\n", mr->rangesize); |
| 93 | return -EINVAL; |
| 94 | } |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | static unsigned int |
| 99 | redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par) |
| 100 | { |
| 101 | struct nf_conn *ct; |
| 102 | enum ip_conntrack_info ctinfo; |
| 103 | __be32 newdst; |
| 104 | const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo; |
| 105 | struct nf_nat_range newrange; |
| 106 | |
| 107 | NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || |
| 108 | par->hooknum == NF_INET_LOCAL_OUT); |
| 109 | |
| 110 | ct = nf_ct_get(skb, &ctinfo); |
| 111 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); |
| 112 | |
| 113 | /* Local packets: make them go to loopback */ |
| 114 | if (par->hooknum == NF_INET_LOCAL_OUT) |
| 115 | newdst = htonl(0x7F000001); |
| 116 | else { |
| 117 | struct in_device *indev; |
| 118 | struct in_ifaddr *ifa; |
| 119 | |
| 120 | newdst = 0; |
| 121 | |
| 122 | rcu_read_lock(); |
| 123 | indev = __in_dev_get_rcu(skb->dev); |
| 124 | if (indev && (ifa = indev->ifa_list)) |
| 125 | newdst = ifa->ifa_local; |
| 126 | rcu_read_unlock(); |
| 127 | |
| 128 | if (!newdst) |
| 129 | return NF_DROP; |
| 130 | } |
| 131 | |
| 132 | /* Transfer from original range. */ |
| 133 | memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); |
| 134 | memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); |
| 135 | newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS; |
| 136 | newrange.min_addr.ip = newdst; |
| 137 | newrange.max_addr.ip = newdst; |
| 138 | newrange.min_proto = mr->range[0].min; |
| 139 | newrange.max_proto = mr->range[0].max; |
| 140 | |
| 141 | /* Hand modified range to generic setup. */ |
| 142 | return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); |
| 143 | } |
| 144 | |
| 145 | static struct xt_target redirect_tg_reg[] __read_mostly = { |
| 146 | { |
| 147 | .name = "REDIRECT", |
| 148 | .family = NFPROTO_IPV6, |
| 149 | .revision = 0, |
| 150 | .table = "nat", |
| 151 | .checkentry = redirect_tg6_checkentry, |
| 152 | .target = redirect_tg6, |
| 153 | .targetsize = sizeof(struct nf_nat_range), |
| 154 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
| 155 | (1 << NF_INET_LOCAL_OUT), |
| 156 | .me = THIS_MODULE, |
| 157 | }, |
| 158 | { |
| 159 | .name = "REDIRECT", |
| 160 | .family = NFPROTO_IPV4, |
| 161 | .revision = 0, |
| 162 | .table = "nat", |
| 163 | .target = redirect_tg4, |
| 164 | .checkentry = redirect_tg4_check, |
| 165 | .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat), |
| 166 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
| 167 | (1 << NF_INET_LOCAL_OUT), |
| 168 | .me = THIS_MODULE, |
| 169 | }, |
| 170 | }; |
| 171 | |
| 172 | static int __init redirect_tg_init(void) |
| 173 | { |
| 174 | return xt_register_targets(redirect_tg_reg, |
| 175 | ARRAY_SIZE(redirect_tg_reg)); |
| 176 | } |
| 177 | |
| 178 | static void __exit redirect_tg_exit(void) |
| 179 | { |
| 180 | xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg)); |
| 181 | } |
| 182 | |
| 183 | module_init(redirect_tg_init); |
| 184 | module_exit(redirect_tg_exit); |
| 185 | |
| 186 | MODULE_LICENSE("GPL"); |
| 187 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
| 188 | MODULE_DESCRIPTION("Xtables: Connection redirection to localhost"); |
| 189 | MODULE_ALIAS("ip6t_REDIRECT"); |
| 190 | MODULE_ALIAS("ipt_REDIRECT"); |